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Indonesia INDRAMAYU Power Plant 3X330MW APH O&M Manual

INDONESIA INDRAMAYU POWER PLANT

3X330MW APH O&M MANUAL Howden Hua Engineering Co., Ltd.

O&M MANUAL

Contract No.：07Z06244

Rev.:0

30th Jan. 2008

Howden Hua Engineering Co., Ltd. Beijing Office 12B/F Jinyu Mansion No. 129 Xuanwumen Xidajie, Xicheng District,Beijing 100031, P.R.China

Tel：010 6641 9988

Fax：010 6641 0071

Web：www.howden.com

Howden


SPECIAL NOTE

This file may contain confidential information which may also be privileged. It is for the exclusive use of the recipients only. Distribution, copying and printing is strictly prohibited. Erectors are responsible for preventing from injure by proper safety measure during construction. Any confused or different contents in this file or other files specified in the contract shall be notified to Howden Hua, otherwise are regarded as well understanding and implementation. Howden Hua Services shall offer technical supports for key and difficult points in this file during machine installation.

This file may contain confidential information which may also be privileged. It is for the exclusive use of the recipients only. Distribution, copying and printing is strictly prohibited. Signature on inspection list is only for confirmation of measured data, other than accomplished part. Handling of the machine shall comply with the instructions, drawings and standards.

Edition

Rev. Page Contents Prepared by

Checked by

Approved by Date

0 First edition MB YYS TH 2008-1-29

Howden


第 i 页

CONTENT

SESCTION 1 INTRODUCTION................................................................................1

1.1 CONTRACT DETAILS ................................................................................................................... .1

1.2 SAFETY INSTRUCTIONS.............................................................................................................1

1.2.1 GENERAL ..................................................................................................................................1

1.2.2 DANGEROUS FUME .................................................................................................................2

1.2.3 ACID MATTER ...........................................................................................................................2

1.2.4 HP OVERHEAT STEAM ............................................................................................................2

1.2.5 ELECTRICAL DEVICES.............................................................................................................3

SECTION 2 TECHNICAL DATA .............................................................................5

2.1 STRUCTURE DATA...............................................................................................................……5

ELEMENT ...........................................................................................................................................5

ELEMENT PACKS ..............................................................................................................................5

SEAL SYSTEM ...................................................................................................................................5

DRIVE MOTOR ...................................................................................................................................5

GEAR BOX..........................................................................................................................................5

COUPLING..........................................................................................................................................5

CONTRACT POWER SUPPLY...........................................................................................................6

ROTOR BEARINGS............................................................................................................................6

BEARING LUBRICATION ...................................................................................................................6

GEARBOX LUBRICATION..................................................................................................................6

SOOTBLOWER...................................................................................................................................6

FIRE FIGHTING DEVICE....................................................................................................................7

FIRE MONITORING DEVICE..............................................................................................................7

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2.2 APH DATA.....................................................................................................................................7

2.3 FUEL ANALYSIS...........................................................................................................................8

SECTION 3 VN APH INTRODUCTION .....................................................................9

3.1 VN APH DESIGN CONCEPT........................................................................................................9

3.2 DETAIL DESCRIPTION OF PLANT ............................................................................................10

3.2.1 HEATING ELEMENT................................................................................................................10

3.2.2 ROTOR.....................................................................................................................................10

3.2.3 ROTOR HOUSING...................................................................................................................10

3.2.4 END PILLAR.............................................................................................................................11

3.2.5 TOP FRAME STRUCTURE......................................................................................................11

3.2.6 BOTTOM FRAME STRUCTURE..............................................................................................11

3.2.7 TRANSITION DUCT.................................................................................................................11

3.2.8 ROTOR DRIVE ASSEMBLY ....................................................................................................12

3.2.9 BOTTOM THRUST BEARING..................................................................................................12

3.2.10 ROTOR STEADY BEARING ..................................................................................................13

3.2.11 ROTOR SEALING ..................................................................................................................13

3.2.12 RADIAL SEALS………………………………………………………………………………………13

3.2.13 AXIAL SEALS ………………………………………………………………………………………..13

3.2.14 CIRCUMFERENTIAL SEALS ………………………………………………………………………14

3.2.15 HUB SEALS ………………………………………………………………………………………….14

3.2.16 SOOTBLOWER......................................................................................................................14

3.2.17 INSULATION ..........................................................................................................................14

3.2.18 TOP/BOTTOM ACCESS PLATFORM FOR APH BODY........................................................16

3.2.19 FIRE FIGHTING DEVICE.......................................................................................................16

3.2.20 GENERAL OF FIRE FIGHTING DEVICE...............................................................................16

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3.2.21 FIRE DETECTION PROBES ………………………………………………………………………17

3.2.22 LOCAL CONTROL CABINET ……………………………………………………………………..17

3.2.23 BEARING OIL TEMPERATURE MORNITORING DEVICE....................................................18

SECTION IV OPERATION OF PLANT ....................................................................19

4.1 GENERAL REMARK ...................................................................................................................19

4.2 CORROSION ..............................................................................................................................19

4.3 PRECAUTION.............................................................................................................................20

4.3.1 DEPOSITE ON ELEMENT .......................................................................................................21

4.3.2 PRECAUTION ..........................................................................................................................20

4.3.3 ACTION IN THE EVENT OF SUSPECTED FIRE ....................................................................20

4.4 GENERAL NOTE ON PRE-COMMISSION .................................................................................21

4.4.1 GENERAL ................................................................................................................................22

4.4.2 PRE-COMMISSIONING CHECKS ...........................................................................................21

4.4.3 BOILER OUT (NO GAS PASS) ................................................................................................22

4.4.4 PRESSURE RASING AND FLOATING SAFETY VALVE(NO GAS PASS) .............................23

4.4.5 PREPARATION OF PREHEATERS FOR COMMERCIAL LOAD ............................................23

4.4.6 SUBSEQUENT RE-FLOATING OF VALVES...........................................................................25

4.5 LUBRICATION ............................................................................................................................24

4.5.1 ROTOR BEARING ...................................................................................................................25

4.5.2 DRIVE UNIT REDUCTION GEARBOEX..................................................................................25

4.5.3 DRIVE UNIT .............................................................................................................................25

4.5.4 SOOTBLOWER........................................................................................................................25

4.6 STARTING UP ............................................................................................................................24

4.6.1 NORMAL START UP ...............................................................................................................25

4.6.2 START UP OPERATIONS .......................................................................................................25

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4.7 CONTROL...................................................................................................................................25

4.8 SHUTTING DOWN......................................................................................................................26

4.8.1 NORMAL SHUT DOWN FOR COLD START ...........................................................................27

4.8.2 NORMAL SHUT DOWN FOR HOT START (I.E SHUT DOWN UP TO 8 HOURS)..................26

4.8.3 EMERGENCY SHUT DOWN ...................................................................................................26

4.9 SOOTBLOWER...........................................................................................................................27

4.9.1 COMMENTS ON SOOTBLOWERING .....................................................................................28

4.9.2 SOOTBLOWING PROCEDURE...............................................................................................28

SECTION V MAINTENANCE OF PLANT .................................................................30

5.1 ROUTIN SERVICING ..................................................................................................................30

5.1.1 SEALING SYSTEM ..................................................................................................................30


5.1.3 ROTOR TOP/BOTTOM BEARINGS ........................................................................................32

5.1.4 DRIVE MOTORS......................................................................................................................32

5.1.5 SOOTBLOWER........................................................................................................................33

5.1.6 FIRE FIGHTING EQUIPMENT.................................................................................................33

5.1.7 LOCAL CONTROL PANEL INSPECTION PROCEDURE........................................................33

5.1.8 PROBE INSPECTION RROCEDURE ......................................................................................33

5.1.9 ELEMENT INSPECITON..........................................................................................................33

5.1.10 AIR PREHEATER...................................................................................................................34

5.2 ELEMENT WASHING .................................................................................................................34

5.2.1 CLEANING OF ELEMENTS......................................................................................................34

5.2.2 WATER WASHING PROCEDURE...........................................................................................35

5.3 LUBRICATION ............................................................................................................................36

5.3.1 AIR PREHEATER TOP AND BOTTOM BEARING ..................................................................36

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5.3.2 REDUCTION GEAR UNIT........................................................................................................36

5.3.3 LUBRICATION OF DRIVE MOTOR .........................................................................................37

5.3.4 LUBRICATION OF SOOTBLOWER.........................................................................................37

5.3.5 GENERAL ................................................................................................................................37

5.3.6 LUBRICATION SCHEDULE.....................................................................................................37

5.4 COUPLING..................................................................................................................................38

5.5 FAULT FINDING-LOCATION AND RECTIFICATION .................................................................38

5.5.1 AIR PREHEATER IN GENERAL ..............................................................................................38


5.5.3 BEARING AND GEARING LUBRICATION ..............................................................................39

5.5.4 SOOTBLOWER........................................................................................................................39

5.5.5 FIRE MONITORING DEVICE...................................................................................................39

5.6 PRECAUTIONS BEFORE MAINTENANCE................................................................................39



5.6.3 SOOTBLOWERS .....................................................................................................................40

5.6.4 LOCAL CONTROL PANEL.......................................................................................................41

5.7 REMOVING AND MAINTENANCE .............................................................................................41

5.7.1 REMOVING AND REPLACING ELEMENT PACKS.................................................................41

5.7.2 REMOVING AND REPLACING OF TOP RADIAL SEALS .......................................................42

5.7.3 REMOVING AND REPLACING BOTTOM RADIAL SEALS .....................................................42

5.7.4 REMOVING AND REPLACING AXIAL SEALS ........................................................................43

5.7.5 REMOVING AND REPLACING CIRCUMFERENTIAL SEALS ................................................43

5.7.6 REMOVING AND REPLACING HUB SEALS...........................................................................44

5.7.7 REMOVING AND REPLACING SOOTBLOWER .....................................................................44

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5.7.8 REMOVING AND REPLACING DRIVE MOTOR......................................................................45

5.7.9 REMOVING AND REPLACING THE PRIMARY GEAR ...........................................................45

5.7.10 REMOVING AND REPLACING THE SECONDARY GEAR...................................................46

5.7.11 REMOVING AND REPLACING OF CENTER DRIVE UNIT ...................................................46

5.7.12 REMOVING AND REPLACING TOP STEADY BEARING .....................................................47

5.7.13 REMOVING AND REPLACING BOTTOM THRUST BEARING.............................................48

5.7.14 REMOVING AND REPLACING ROTOR STOP ALARM SENSORS .....................................49

5.7.15 REMOVING AND REPLACING FIRE DETECTION PROBES ...............................................50

5.7.16 REMOVE AND REPLACE FIRE DETECTION PROBE THERMOCOUPLE ..........................51

5.8 PRECAUTIONS AFTER MAINTENANCE...................................................................................52



5.8.3 SOOTBLOWERS .....................................................................................................................53

5.8.4 LOCAL CONTROL PANEL.......................................................................................................54

5.9 SPECIAL TOOLS ........................................................................................................................54

ANNEX I ASME PTC 4.3 TEST STANDARD.............................................................56

ANNEX A：DEFINITIONS AND NOMENCLATURE..................................................... .68

ANNEX B：ITEMS TO BE CHECKED BEFORE TEST ................................................. .70

ANNEX II APH PERFORMANCE ANALYSIS AND OPERATING DATAS...........................70

ANNEX III APH FAULT FINDING AND RECTIFICATIONS ............................................73

ANNEX IV HOWDEN VN APH SPARE PARTS LIST ...................................................78

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Page 1 of 1

Section 1 Introduction

1.1 Contract details

Contract No.： 07Z06244

Location： Indonesia INDRAMAYU Power Plant

No. of Boilers： 3

Fuel： Coal

APH Type： 29VNT2500（150）

No. of APH： 2/Per Boiler， 6 in all

1.2 Safety instructions

1.2.1 General So far as is reasonably practicable the Air Preheater has been so designed and constructed as to be safe and without risks to health when properly used.

Howden always maintains the highest safety standards and our products are manufactured and tested in accordance with these requirements.

Providing the instructions in this Operating and Maintenance Instruction Manual are observed, the safety and health of personnel involved in operating, maintaining or installing the equipment should be safeguarded.

Personnel must be made aware of the current Safety Instruction appertaining to the Site and must be provided with the necessary protection for their safety and health. Relevant clauses in this Instruction Manual will help to the establishment of necessary safety measures for operation and maintenance.

Prior to any maintenance to the air preheater and associated equipment, it is recommended that all personnel involved in the power plant are fully acquainted with Section 5 of this manual and in particular Section 5.6 'Precautions before Maintenance'.

Special note: It is of utmost importance that no repair work is carried out to any part of the plant prior to full safe work permits being issued i.e. the plant must be isolated and the working area pronounced safe.

Some of the inherent dangers associated with this plant and the requirements for safety of personnel are outlined as follows:

Dangerous Fumes Acidic matter HP overheat steam Connection of electricity

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1.2.2 Dangerous fume

During normal operation of the plant, the hot gases will contain a quantity of harmful sulphur dioxide, depending on the sulphur in the fuel and combustion efficiency. During plant shut down when performing an internal inspection or carrying out internal maintenance of the equipment or associated ducting, the plant must be suitably cooled down and ventilated to remove dangerous fumes. The rotor should be rotating during the initial cooling down period to prevent distortion of the rotor and seals. Open the drain hole to release gas pockets. Stop the rotor and electrically isolate the drive motor when the cooling down process is complete.

A responsible person should then test and certify that the atmosphere within the plant is clear of dangerous fumes and that the plant is suitably ventilated and cool enough for personnel to enter and work in safety. The appointed responsible person should ensure also that effective steps have been taken to prevent the ingress of dangerous fumes while personnel are working within the plant.

The following gives some indication of the risk to personnel from various concentrations of sulphur dioxide (SO2):

Olfaction influence： 3-5 ppm

Irritation of throat： 8-12 ppm

Coughing： 20 ppm

One- hour exposure： 50-100 ppm

30- minutes exposure： 200-500 ppm

Allowable Limit Value： 5 ppm

1.2.3 Acid matter

During the combustion of fuel, most of the sulphur in the fuel is converted to sulphur dioxide, but about 1-5% of the sulphur is converted to sulphur trioxide, depending on sulphur content of the fuel, excess air, etc.

This sulphur trioxide when combined with the moisture in the flue gas forms sulphuric acid that can cause severe corrosion of metal and be dangerous to personnel.

Prior to personnel entering the ducting it is strongly recommended that all internal landing points for internal platforms are fully inspected for signs of corrosion and certified to be safe.

Personnel working in the air preheater or associated ducting during an shutdown should be aware of above-mentioned possible hazard and be provided with suitable safety belt, protective clothing, respirator and safety glasses etc..

1.2.4 HP overheat steam

As all air preheater are fitted with a steam sootblower, it is extremely important that the appointed Safety Officer should check and ensure that the steam isolating valves to the sootblowers are completely closed and locked before personnel are permitted to carry out repairs to the sootblowers, or to enter the ducting, or to remove the manhole.

In the event of a leaky isolating valve local to the blower, isolate the air supply upstream, preferably at the source.

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It is essential that all leaks and any other potential faults in the sootblowers or supply line, which may affect the safety of personnel, must be reported to the maintenance staff in time for settlement.

1.2.5 Electrical devices

The customer is reminded, in connection with the installation and cabling of electrical equipment, of his obligation to ensure the safety of personnel in operating and maintaining the plant.

Prior to carrying out any maintenance to electrical equipment it is essential to check that the equipment involved has been electrically isolated and locked.

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Center drive unit

Secondar

Gas

Rotor

Top structure

Rotor

End

Primary air Client

Bottom

Note：Typical arrangement of VN APH of Howden

VN Tri-section APH Sketch

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Section 2 Technical data

2.1 Structure data

Elements

Hot end： HS7， 0.5mm thick， 1200mm deep，Mild steel

Warm end： HS7，0.5mm thick，1000mm deep，Mild steel

Cold end： HS7， 0.8mm thick，300mm deep，Equal to Corten steel

Element packs

Type： ⅢType，invertible

Material： Mild steel

Airflow arrangement： Gas down，air up

Seal system

Top Sector Plate： Fixed, unadjustable

Axial Seal Plates： Fixed, unadjustable

Bottom Sector Plate: Fixed, unadjustable

Seal settings of rotor can meet its hot deformation.

Drive motor

GAMAK Motor，2，11kW，Speed1455 rev/min，Frame size D160；

Frame type: GM160L, B class temperature rise, with thermosensitive protection, F-class insulation protection, 380V±10%，3 phase，50Hz，Protection class IP55， suitable for an annual average relative humidity of 83% ；

Conversion control;

Main drive motor with hand-turning device output shaft at non drive end

Gear box

GMF5D gear box RITESPEED，2，speed ratio 9.110:1；

TSMWD17scroll worm gear box TITAN，primary speed ratio 43:4，secondary speed ratio 59:4；

Coupling

2 set of D71BBWP couplings，separately connected to main and accessory drive motors；

Shrink disc of drive unit output mounting bell：SD220-91.

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Contract power supply

380V，AC，3 phase，50Hz.

Rotor bearings

Top steady roller bearings： SKF C3172M/C4

Bottom roller thrust bearings： SKF 29480EM

Top bearing mounting bell shrink disc： SD280-71

Rotor Speed： 1.0 rev/min(normal operation)，0.5 rev/min (water washing)

Bearing Lubrication

Oil bath lubrication for both rotor bearings.

Top Steady Bearing： Mobil SHC 639 20 L

Bottom thrust bearing： Mobil SHC 639 40 L

Lubricant grade： ISO VG 1000，Synthetic oil

Gearbox lubrication

Lubrication of gear box is listed below：

Gear box Viscosity(40 )℃ Volume Type First filling oil grade GMF5D 288-352 Cst 2X2 L Synthetic oil SHELL OMALA 320RL

TSMWD17 288-352 Cst 125 L Synthetic oil SHELL OMALA 320RL

Sootblower

Manufacturer： Hubei Diamond Machinery Co., Ltd.

Model： One IK-AH/B and one IK-AH type (semi-retractable)

Blowing media： Overheat steam

Steam pressure before blower regulating valve during operation： 1.2MPa

Steam temperature before blower regulating valve during operation： 300~350℃

Steam pressure before blower regulating valve at start up： 1.5MPa

Steam temperature before blower regulating valve at start up： 300~350℃

Staem pressure at blower nozzle： 0.93~1.07MPa

Steam flow： 44kg/min /single lance

Installation location： inlet/outlet ducts

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Radial coverage range： 4102mm

Blowing cycle： 30min/single lance

Blowing sequence： First to outlet then inlet

Blowing interval： every 8 hours normally(recommended)

Blowing speed： 1 rev/min

LP washing： Combined with soot blower

Water washing media： Over 20 ℃ (50－60℃ preferable) industrial water

Pressure before LP water valve： 0.52 MPa

Water supply： 630 kg/min /single lance

Lance location： Inlet gas duct

Radial coverage range： 4102mm

Water washing cycle： 58min

Water washing interval： After boiler shutdown in necessary

Water washing speed： 0.5 rev./min

Fire fighting devices

The air preheater is equipped with 3 sets of Tyco water spraying equipments for fire fighting, separately installed in top gas ducts, primary and secondary air duct.

Spraying volume of each hydrant ：

Gas side： 2323~2718 L/Min

Secondary air side ： 2323~2718 L/Min

Primary air side： 694~812 L/Min

Total： 5340~6248 L/Min

Working pressure range： 0.38~0.52MPa

Fire monitoring device

Secondary air outlet side of each APH is fitted with 5 fire monitoring probes and 1 local cabinet.

2.2 APH data

APH design model： 29 VNT 2500 (150)

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Total heated area by elements (single sides，each APH)： 36573m2

APH(main body)gross weight： 409T or so

Height of housing： 3590mm

Operating environment： Outdoor

Fuel： Coal

No. of APH for each boiler： 2

Air flow arrangement： Gas down，air up

Rotation direction： Gas/ Primary / Secondary

Load： See《Technical agreement of boiler APH》

Recommended integrative temperature at cold end: Gas outlet temp. + air inlet temp.(Refer to APH performance data) shall be no lower than the specified “ min. integrative temperature at cold end”.

If the fuel is charcoal with sulfur content ＜1.5, the integrative temperature at this cold end shall be no lower than 148℃.

Note： Set the sectorplates and sealing strips to proper max. temperature during APH commissioning：

Δt=298.5℃，where：

Δt= Average temp. at hot end- Average temp. at cold end

If APH runs when Δt＞298.5℃, its sealing system shall be reset, at this time you should consult Howden Hua Engineering Co. Ltd. in advance.

Note： APH max. allowable inlet temp. shall be no higher than 15 under BMCR working ℃

condition, i.e. 423℃. If APH is possible to run when inlet temperature over this data, sealing

system shall be reset, at this time you should consult Howden Hua Engineering Co. Ltd. in

advance.

2.3 Fuel analysis

See 《APH Technical Agreement》for the result.

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Section 3 VN APH Introduction

3.1 VN APH DESIGN CONCEPT

Howden Rotary Regenerative Air Preheater is designed to supply hot air for combustion so as to further save fuel. The air preheater contains within a relatively small space a large heating surface area.

A proportion of the heat in the flue gas side is transferred to the elements when APH pass through the flue gas side and this heat is in turn transferred to the air when the elements pass through the air side. Thus the heat in the flue gases is recovered and returned to the furnace via the airflow, so the gas emission temp. is reduced and the initial temp. of fuel and air rises, then boiler efficiency is improved further.

The rotor is the central part containing the heating elements. Radial plates extending from the hub divide the rotor into twenty-four sectors, which in turn are sub-divided to 48 sectors by secondary radial division plates. Sector division plates, between radial division plates and secondary radial division plates strengthen the rotor and support the element containers. The whole weight of the rotating parts like rotor, elments etc. is carried on the underside by a spherical roller bearing whilst at the top a spherical roller guide bearing is provided to resist radial loads.

The Trisector design has three streams, the flue gas, the secondary air and the primary air, the flue gas being on one side of the rotor and the opposite side being divided into a further two segments for secondary air and primary air. Three groups of axial sealing plates and sectorplates separate all three sections from each other. The gas and air streams flow in opposite directions, i.e. in contra flow, with the gas flow down and air up. Double sealing and tri-sealing can be achieved by changing the width of sectorplates and axial seal plates, so as to meet the total air leakage and primary air leakage requirements of the power plant for APH.

Enclosing the rotor is the casing, which is connected to transition ducts on top and at bottom. Transition ducts connects rotor housing at one side, the other side connects expansion joints of client’s gas/air ducts, the height and the dimension of interface flange can be changed correspondingly according to different requirements of client for duct arrangement. Rotor housing is also installed with outer circumferential seals so as to control the direct leakage of air to gas and bypass volume of gas/air.

The casing is attached to the end pillar hinge of the air preheater and welded together to be supported by the bottom girder. The Air and Gas side of rotor casing is supported by two sets of hinged side pillars to hold rotor casing on the client framework, which will ensure rotor casing expanded towards outside when being heated.

The drive unit is mounted directly to the rotor hub drive shaft. This drive assembly provides the facility of main AC electric drive and emergency AC electric drive, gear box, coupling, shrink disc and frequency inverter.

As per design requirements, the drive unit must be started through inverter to reduce start up

torque to protect gear box and transmitter. It is strictly forbidden to start up drive unit directly!

Rotor will rotate with low speed when water washing. In addition, drive unit is equipped with hand turning gear to turn the rotor during erection and maintenance.

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The stationary sealing plates consisting of sector plate and axial sealing plate. Sector plate is arranged along the diameter of rotor. Axial sealing plates are attached to the end pillars and seal against the periphery of the rotor. Sealing strips are attached to the top and bottom edges of the rotor radial division plates and secondary radial plates, and down the outside edges of the rotor. Correctly set these seals through calculation and the experience of site erection to ensure minimum leakage between air and gas flows under normal operating conditions.

Circumferential sealing between the top and bottom perimeters of the rotor and the casing is provided on the bottom side by strips attached to the casing which seal against the bottom circumferential tyre and on the top by strips attached to housing which seal against the circumferential tyre.

3.2 DETAIL DESCRIPTION OF PLANT

3.2.1 Heating Surface Elements.

The heating surface elements are manufactured from thin steel sheet with two different profiles. One element having undulations the other having alternate undulations and notches. These elements are then packed together, undulated/notched and

undulated, alternately. The notches run parallel with the rotor axis and space the elements correctly at a set distance apart. The undulations lie at an angle of 30° to the notches. These undulations impart a high turbulence to the gas and air as it passes through the air preheater.

As the cold end i.e. gas leaving - air entering the preheater, is most susceptible to corrosion due to temperature and fuel conditions the elements are arranged in tiers, where ‘Hot End’ and ‘Warm End’ elements are manufactured from mild steel and the "Cold End" elements from equal to

corten steel.

The elements are packed into containers to facilitate removal and handling from the rotor. As per agreement, hot end and intermediate heating elements are removed vertically upward. And cold end element containers are removed in an axial direction from the rotor.

3.2.2 Rotor

Refer to 001007 and 001008.

The rotor is constructed from carbon steel plates carried on a central hub. Sectors consist of spider and outer section. Spider is fabricated by hub and inner section, where, radial plates are integrated with hub. Radial plates extending from the hub to the periphery of the rotor divide the rotor into 24 sectors which, in turn, are sub-divided by secondary radial division plates and sector division plates. The compartments so formed are filled with the heating surface elements.

At cold end, cold end heating element support grid are provided, in addition, each rotor ourter tyre division plate is provided with cold end heating element side withdraw door.

3.2.3 Rotor Housing

Refer to 001001 and 126001.

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The rotor housing, forming part of the air preheater, is manufactured from fabricated Carbon steel plates and encloses the periphery of the rotor.

The air preheater casing takes the shape of an octagon with six housing segments assembled between the end pillars. On each side of the end pillars, rotor housing was supported on the client steel work with hinged side pillar, the arrangement of side pillar take the expansion of rotor housing and side pillar into consideration.

The setting of each silde pillar and end pillar shall ensure static parts can expand to different direction to realize the safe and economic operation of APH.

The rotor housing supports the outer sections of the top and bottom transition ducts, which are attached to the housing top and bottom landing plates.

3.2.4 End Pillars

Refer to 001001 and 101001.

The end pillars support the top structure including the rotor steady bearing.

Each end pillar carries an axial sealing plate which attached to top and bottom sector plates.

The end pillars are connected to the false sector plate on bottom structure and the total loading is transmitted directly through the hinged connections to the bottom girder ends and the client steelwork.

3.2.5 Top Frame Structure

Refer to 001001 and117001.

The top frame is connected with top sector plate which hung on false sector plate by some adjusting screw rod before set up. The top structure bridges the end pillars to form a frame taken traverse load from top bearing located in center position one hand, the other hand, transferred from torque arm on motors.

Some ventilation holes are norched on wing plates at gas and air side to make temperature fileds around top structure girder uniform as possible, so that minimize vertical termal deformation of top structure and variation of radial clearance at rotor hot end.

3.2.6 Bottom Frame Structure

Refer to 001001、100001 and105001.

The bottom structure consists of girders, bottom sector plate and bottom false sector plate. Girders support the bottom-bearing stool carrying the weight of the rotor. The girders also support the end pillars, bottom sector plates and the bottom false sector plate. The transition ducts are also partly supported from the bottom frame.

The total loading on the girder is conveyed through the girder ends to the client’s supporting steelwork.

3.2.7 Transition Ducts

Refer to 001001、116001、116002、116003 and130001~130006.

Transitional ducts are located on the gas and air sides of the rotor to convey the fluid streams to and from the rotor. The air duct is divided into two, one for the secondary air flows and one for the primary air flow

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These transitional ducts are attached to the rotor housing landing plates and to the top and bottom frame structures. Flange interface size and type shall comply with ducts design.

Tubular stiffeners that radiate from the inner duct wall strengthen the outer duct wall in each duct assembly.

3.2.8 Rotor Drive Assembly

Refer to 136001 and GA of Drive Unit 11843/2M (Renold).

The rotor is driven by an electric motor that is directly connected to the rotor top drive shaft as indicted on Drawing No. 136001.

Both the main and auxiliary motor can drive APH forward and reversely, and it is only allowed to reverse direction when APH is not being loaded.

Two drive motors are flange mounted to primary reduction gearboxes.

The secondary gear unit is mounted directly on the rotor shaft, and is secured by means of a shrink disc.

A torque arm is provided attached to the side of the secondary unit housing and torque brackets locate this arm to the top frame, which will react on drive unit by torque arm to rotate end shaft and rotor and enables vertical axial movement to accomodate top structure thermal expension.

The non-drive side of main motor is fitted with output shaft with key connected to facilitate hand turning gear with hand turning device when maintenance.

Gear box is oil-bath lubricated.

The drive motor is fitted with inverter to reduce the start up torque at the time of APH being

started to realize “soft start up”. In addition, through inverter, the speed of APH can be changed

to suit the requirement of water washing when APH operates at Low speed.

3.2.9 Bottom Thrust Bearing

Refer to 144001.

The rotor is supported by means of a self aligning spherical roller thrust bearing which is located in a bearing housing mounted on the support stool. This bearing takes the full rotating weight of the loaded rotor.

After bearing housing position, retaining plates are bolted and welded on the stool.

Protective fense mounted at both sides of bottom bearing to provent ponsernnel from accidence due to access the rotary parts duing APH running norally.

The bearing runs in an oil bath and the housing is fitted with an oil filler and level indicator. The housing is tapped ½" BSP suitable for two oil temperature probes.

Shimming material is provided under the bearing housing initially for rotor positioning and additional shimming is added during erection to compensate for beam deflection.

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3.2.10 Rotor Steady Bearing

Refer to 001001 and 136001.

The assembly of the top steady bearing consists of a spherical roller bearing (SKF ‘CARB’ type) located on a mounting bell which in turn is located by a shoulder on the rotor shaft and is secured to the shaft by a shrink disc. Most part of steady bearing and mounting bell located in bearing housing.

Channel stifferners welded at both sides of top bearing housing. Top bearing position can be regulated by adjusting screws on top structure to the stifferners. These stiffernerns and top structure are secured by 8 setscrews and pads. After top bearing alignment finally, pads a.m. shall be welded on top structure plate. Levelling and positioning of the bearing housing is provided by means of shimming under the stifferners. The bearing runs in an oil bath the grade of oil being similar to that of the support bearing. (Details for the relative discription)

Top steady bearing house is fitted with oil hole, oil filler, level gauge, breather and drain plug, as well is tapped ½" BSP suitable foroil temperature probes.

Top bearing house also is equipped with water cooling system and supply a mating flange which suit for site connecting cooling water. The inlet temperature of cooling water flange shall be not higher than 38 , the flow of cooling water shall be not lower than required value. ℃

The relative dimension and size of the top cover for top steady bearing house and top mounting

bell is consist with that in 136001. This top steady bearing adopts CARB bearing, the “0”scale

(middle line) on the mounting bell must be aligned with tope bearing house cover at cold state.

3.2.11 Rotor Sealing.

The sealing system of APH consists of Radial, axial, circumferential seal and rotor hub seal.

3.2.12 Radial Seals

Refer to HSTD186001-29.

The radial seals are attached to the top and bottom edges

These seals are manufactured from 1.6mm thick Corten Steel and are secured to the rotor division plates with 6mm thick mild steel backing strips by ‘Aerotight’ nuts. All the seals are straight design. Radial seal plate is used to reduce the direct leakage from air to gas.

3.2.13 Axial Seals

Refer to HSTD/185001-2.

The axial seals work in conjunction with the radial seals to minimise the gap between the rotor and the sealing plates. Axial seals are fabricated by 1.6mm THK Corden Plate or equal and attached to the outside edge of the radial division plates. The seals are initially set during cold conditions such that the seal clearance will be kept minimum value with the axial seal plates when boiler operate with load and shut down. The fitting method of axial seal is the same as that of radial seal plates.

The axial seal plates were supplied with margin for trimming at the top and bottom end. They can be trimmed as per actual position of rotor tyre.

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3.2.14 Circumferential Seals

Refer to189001 (outer circumferential seals) and HSTD186001-29 (inner circumferential seals).

Circumferential seals are fitted at the hub and periphery of the rotor, both top and bottom. Their essential function is to prevent bypassing of air or gas round the outside of the rotor thus impairing the thermal performance of the air preheater. In carrying out this function these seals are of assistance to the axial seals since they reduce the pressure difference across the axial seals.

At the bottom periphery point of the rotor, the single circumferential sealing strip of 1.6mm thick Corten is mounted on the bottom transition ducts and seals against the bottom rotor tyre. This seal is pre-set a clearance to suit vertical downward capping of the rotor and casing expansions at 100% operating conditions. The seals are secured by aerotight nuts and retaining plates.

The top outer circumferential seal strips are welded to rotor casing. When setting seals, the radial rotor and casing deformation at 100% operating condition shall be considered.

Inner circumferential seal strips are provided around the top and bottom of the rotor hub and seal against the top and bottom sector plates. Both these seals are secured by means of set screws and the nuts for which are welded to the inside of the fixing plate.

3.2.15 Hub Seals


The hub seal assemblies comprise a double seal arrangement incorporating a sealing air system. The assemblies, one at each end, are attached to the sector plates and seal against the hub. The inner seal comprises two flat rings of 1.6mm thick Corten steel material separated and supported by mild steel rings and attached directly to the sector plates.

For easy replacement, inner seal is of split structure to facilitate replacement and erection.

Outer seal is packing seal. The supporting plate of packing base is fastened to the circumferential stiffeners on the sector plate. Packing material is special designed for non-asbester, the heat withstanding temperature shall be no lower than 500℃. Packing material is of three layers, section area is 15mmx15mm.

The circumferential chamber between inner hub and outer seal shall be fitted with one channel pipe directly go to gas side, leading the air and gas into gas side through the negative pressure of gas side.

The main purpose of hub seal is to reduce the air leakage into the air.

3.2.16 Sootblowers

Refer to dwg. 001001.

The air preheater is fitted with two sootblowers, at the gas inlet and outlet. The sootblower is provided by Howden. Refer to the sub-contractor documents for the details.

3.2.17 Insulation

Refer to174001，174002 for the insulation arrangement.

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Insulation must be applied to preheater surfaces to reduce heat loss and to maintain uniform structure temperatures. The main aim is to minimise possible distortion of the components that carry the sealing surfaces. Insulation is also used to protect personnel.

This insulation should be applied externally over the Rotor Housing, Top Structure and Top False Sector Plate, Top Tri-section False Sector, Bottom Structure, Bottom False Sector Plates, and Bottom Tri-section False Sector, End Pillars, Gas Inlet Duct, Gas Outlet Duct, Air Outlet Duct and the Air Inlet Duct, etc. as indicated in the drawing 174001.

Insulation material shall be decided by insulation contractor.

The total thickness of insulation and cladding should be such that the external surface temperature is limited to a maximum of 50℃ as designed ambient temperature is 27℃. When ambient temperature greater than 27℃, the allowed maximum internal surface temperature is 25 higher than ambient ℃temperature. All flanges must be insulated.

All cladding plates should be generally fixed to the preheater surface by means of angle supports. In addition to this, self-tapping screws can be used at suitable intervals to prevent distortion and drumming of plates and to present a first class appearance. The size of the panels will vary to suit the arrangement of the surface and stiffeners involved. These panels should be overlapped with allowance for expansion and sealed with suitable tape or compound against the ingress of moisture.

Opens on APH, such as access door and sight galss, shall be fixed with removal insulation to avoid disassembling adjacent cladding plates while maintanence.

The internal surface temperature of the following parts shall be taken into consideration when design the thickness of insulation material:

Gas inlet：················································································································408℃

Gas outlet： ·············································································································141℃

PA inlet： ···················································································································38℃

PA outlet： ···············································································································394℃

SA inlet： ···················································································································33℃

SA outlet： ············································································································380.5℃

End pillar and rotor housing： ···············································································248.2℃

Top structure：······································································································397.4℃

Bottom structure： ··································································································98.9℃

Top tri-section structure： ·····················································································383.9℃

Bottom tri-section structure： ··················································································34.7℃

As per contract requirements, all materials are not within Howden supply.

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3.2.18 Top/Bottom Access Platform for APH Body

Refer to 001001、159001、163001.

The top access platform provides access to the centre drive unit, the top steady bearing assembly, rotor stall alarm probe and the fire detection probes.

The bottom access platform provides access to the bottom bearing assembly, bottom hub seals and needle gauge points.

The above platform shall be designed and provided by Howden. In addition, APH must be fitted with the following platform and staircase.

Access to the top, bottom duct and staircase.

Access to axial seal door and staircase.

The access and staircase for maintenance top and bottom sootblower.

Access to sight glass and staircase.

The side withdraw door platform and staircase for the cold end heating element.

Bottom tri-section needle gauge inspection platform and staircase.

The above top, bottom platform and staircase from client platform to APH

Except the special requirements in the contract, the above platform shall be designed and supplied by boiler plant.

3.2.19 Fire Fighting Equipment

Refer to dwg. 001001、8001198-M03、8001198-M04(Tyco) and sub-contractor manual.

Fire fighting equipment of the Tyco installed in the top transition ducts. Each duct incorporates a cluster of nozzles so designed as to efficiently cover the rotor area in each duct. The terminal point being at the nozzle manifold flange which onto the client fire fighting pipe is being welded directly.

Each nozzle is fitted with a blow off cap to prevent ingress of foreign matter entering the system and these cap are designed to blow out at a low pressure of approximately 0.07 MPa.

Note; titanic disc is not allowed to be removed.

Water drainage system is fitted at the lowest point of bottom gas duct and the air duct, and the water drainage system and fire fighting pipe is not within Howden supply.

3.2.20 General of fire fighting device

APH will not fire at clean state, even if heating element surfaces are not clean, if APH works under stable BMCR, the possibility of internal firing are not negliable.

A serious fire risk, however, presents itself during any period of low load or poor combustion operation, particularly while oil firing. Deposits formed on the heating surface under these circumstances are of finely divided carbon that can fairly readily ignite at a temperature only slightly above the temperature of deposition. These deposits will not ignite instantaneously at all points in the heating surface but rather at

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some particular point in the heating surface, spreading with increasing intensity outwards from this point. In most cases, the deposit will burn itself out without affecting the metal of the heating surface elements. There is, however, always the possibility that, with sufficiently heavy deposits, the temperature arising from the burning deposit will become sufficiently high to ignite the metal of the elements with serious consequences.

Fortunately there is a considerable delay between the initial ignition and spread of the deposit fire and the ignition of the metal. The heat being removed by the flue gases and air passing over the burning area, result in a deposit fire requiring at least some 60-90 minutes to spread through one pack of elements and considerably longer, some three to tree to four hours, to affect the metal and spread to adjacent packs. During the early period the pack of elements is describing an annulus around the preheater due to the rotation of the rotor. The air or flue gases leaving this pack of elements will be superheated by the fire, giving rise to a stream of superheated gases describing an annulus along with the rotor.

The fire detection equipment is so designed that a number of stationary thermocouple points fixed radially across the rotor, but separate from the rotor, will monitor the temperature of the fluid issuing from the annuli. Should the temperature at any one point in any annuli momentarily exceed its normal an alarm sequence will be initiated.

3.2.21 Fire Detection Probes

Refer to 368001.

The fire probes are positioned radially in the outlet transition air duct. Probes are supported with fixed flange and can be withdrawn from APH during operating for inspection and maintenance.

The fire detection probe is structure of tube. Attached to the end of the thermowell is a cap that is arranged in the form of a cage, so that the protruding thermocouple is mechanically protected yet open to the free passage of the preheater hot air.

Thermal couple is located via ceramic pipe and end cover insulation, the other end is fastened to probe flange via stainless steel cover. In addition, the thermal couple compensate terminals are within Howden supply, but the cable are not supplied by Howden.

Above each ring of rotor sector, fire detection probe was fitted to supervise the transient temperature and temperature rise of the element of each ring.

Thermal couple is inserted into duct via ceramic pipe which is being fitted with 1/2” BSP isolating valve to help to replace thermal couple probe during APH running. When taken out fire fighting probe, connect compressed air before removing fire probes.

Caution: wear fire protection cloth when replacing fire probe.

3.2.22 Local control cabinet

There are three leds on front panel of local control cabinet, they are:

alarm： red

fault： yellow

power on： green

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In addition, there is one more test button.

Normally, only the green led “power on” will be lighten.

High temperature alarm

If a certain thermal couple detected tempreture rose above pre-seeting temperature or temperature rose too high (exceed 35℃/s), the red led on the front panel will be lighten. At the meanwhile, internal alarm relay RL2 output dry contact signal to the center control room.

To identify alarm point, it is necessary to open local control panle to check the alarm unit, where one or many unit shall be in alarm status to further determine the detailed high temperature alarm position and monitor temperature change trend as well development by temperature indication.

After alarm released, press reset button to restore local control panel to normal status.

Thermal couple circuit break alarm

If thermal couple’s circuit was broken, the yellow “fault” led will be lightened, then relay RL3 will output dry contact alarm signal to center control room. To determine which thermal couple faults, it will be necessary to open local control panel to check the thermal couple signal processing unit. If a certain fault led being lightened, it will indicate the corresponding thermal couple or wiring broken.

Remove the fault and presse the rest button to return local control cabinet to normal.

Power supply fault alarm

If power supply fault, all three alarm output relay will be activated, where relay RL1 will output power supply failure alarm signal to the center control room. All leds on the local control panel will be turned out after power supply was faulty.

Rotor Stall Alarm System

Refer to HSTD/196-1.

The rotor stall alarm system is provided to give warning that the rotor has stalled so that action can be taken to prevent rotor deformation occurring.

The detail description of rotor stall alarm device pls refer to APH Erection Manual.

Speed sensor is connected with local control panel via terminal box, rotor stall alarm relay is fitted inside the local control panel.

3.2.23 Bearing oil temperature monitoring device

Refer to136001，144001，088005.

Both the top and bottom bearing housings are provided with a 1/2" BSP tapping point for mounting thermal sensor.

The thermocouples have two settings: high oil temperature warning is set at 70C; overhigh oil temperature alarm is set at 85 C. Refer to 088005 for the detail. When bearing set out high temperature alarm, check the bearing oil level and oil quality, and take suitable measures to reduce temperature. Watch closely the variation of oil temperature.

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SECTION IV OPERATION OF PLANT

It is recommended that consideration be given to employing the services of a Howden Power Ltd. Commissioning Engineer throughout the pre-commissioning and commissioning of the plant. 4.1 GENERAL REMARKS Before putting the air heater into operation it is important to note that the "Cold End Combined Temperature" (i.e. the sum of the gas leaving and air entering) be maintained at/or above the established "Min. Combined Temperature".

For this project, the”min. cold end combined temperature”has been given in the “APH performance parameter”, which is related to the detailed operating environment, coal type and combustion condition etc.

Special care: to reduce corrosion and foul of cold end heating element, to enable APH meet with requirements. Special care must be taken to ensure APH not long term operates at the “cold end combined temperature” lower than given.

The "Cold End Combined Temperature" is normally maintained at or above the recommended "Minimum Combined Temperature" by controlling the air inlet temperature.The air inlet temperature to the rotary air preheater should be controlled to maintain the "Cold End Combined Temperature" at or above the established minimum for the particular fuel in use. The minimum combined cold end temperature for coal firing is 148℃based on sulphur content in the coal lower than 1.5 %.

4.2 CORROSION

In practice almost all fuels burned in boiler plants contain sulphur. During combustion, most of the sulphur in the fuel is converted to sulphur dioxide, but about 1% - 5% of the sulphur is converted to sulphur trioxide. The amount of sulphur trioxide in the flue gas depends upon a number of factors including the sulphur content of the fuel, the amount of excess air for combustion and the presence of deposits which catalyse the oxidation of sulphur dioxide to sulphur trioxide.

Corrosion of mild steel heating surface results from the presence of this sulphur trioxide that combines with moisture in the flue gases to form a film of sulphuric acid on the element plates.The maximum temperature at which a continuous film of sulphuric acid can be formed on the heating surface exposed to the flue gas is known as the 'acid dew point' of the flue gas. When element wall temperature lower than ‘dew point’, acid moisture will condense on the wall to erode elements and adhere dust to jam finally, which will result in reduceing element exchang effective and lifetime. Thus it will threat APH safe and economical operation.

Deposition of sulphuric acid at or below the dew point temperature can cause severe corrosion, the rate of corrosion becoming a maximum at about 20 -45℃ below the dew point temperature.

To keep cold end preheater corrosion to a minimum, it is essential to comply with the following:-Never operate the preheater with a 'Cold End Combined Temperature' (gas out + air inlet temperature) for an extended period at less than the minimum recommended for this plant.

The carry over of moisture due to a faulty economiser or steam air heater will tend to raise the dew point of the flue gases and this combining with the carry over of any unburned fuel particles can promote corrosion of the elements. To avoid element rapid corrosion, leakage pipe shall be repaired sooner and higher burning effective shall be guaranteed.

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4.3 Precautions

4.3.1 Deposits on Elements

Deposits (oil and flammable carbon) on the preheater element sheets caused by low load operation or poor combustion conditions are highly inflammable. Precautions must therefore be taken to prevent such a build up of these deposits on the elements, otherwise a serious fire may result.

4.3.2 Precautions

Precautions to be taken when commissionng the preheater during No-load and Low-Load operation:

1) The rotor should be revolving.

2) Particular attention must be paid to keeping the elements clean by frequent sootblowing (as described in the section on sootblowing instructions under 4.9).

3) Close attention should be paid to the preheater gas and air temperatures. Note that any unusual increase in either of these temperatures should be regarded as indicating the possibility of a fire and must be investigated immediately.

4) The preheater elements should be inspected as soon as possible after shut down following No-Load or Low-Load operation and cleaned as necessary.

5) The fire detection equipment should be operating.

4.3.3 Action in the event of a suspected fire

The symptoms of High Temperature Alarm Fire Condition are:-

a) Local high temperature warning L.E.D. indicator light.

b) Remote 'Fire Unit Alarm Indication' in Control Room.

On receipt of an alarm, the following actions should be initiated by the Control Room Engineer:-

i) The operator display for the fire detection provides indication on each channel and indicates which type of alarm is active.

ii) Open the door of local control panel.

iii) If local control panel lost power, “power on”LED will be off, detect the reason and reset as soon as possible.

iv) If the air outlet temperater is too high or tempreture rise too high, then the red LED on the panel of local control panel will be illuminated. Through temperature indicator, we can monitor the temperature variation.

v) The yellow indicator will indicate thermocouple open when illuminated, reset the button after fault was deliminated.

Before taking action to put out the fire, a check should be made for possible visible evidence of the fire. It should be noted that signs of a fire might not be visible.

If the fire detection equipment detects a fire, the following action should be taken.

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1) Accept alarm signal from fire detection equipment.

2) Confirm that air preheater is on fire by checking the air preheater.

3) Shut off the FD fan and ID fan then completely shut down boiler.

4) It is essential that the air preheater is kept rotating.

5) Close Gas, air isolating dampers of air preheater.

6) Open the drains in all the bottom ducts beneath the air preheater.

7) Turn on the fire valves and extinguish the fire by means of the spray nozzles situated in the top gas and air ducts, and check that the duct drains are operating.

8) Continue to spray water from all these ducts on to the air preheater rotor until the fire is completely extinguished and the rotor has completely cooled.

Watch closely if the other APH exists the same potential fire.

4.4 General Note on Pre-Commissioning

4.4.1 General

During this period of operation, deposits on the preheater element sheets, caused by low load operation or poor combustion conditions, are highly inflammable and the precautions outlined in Section 4.3 should be strictly adhered to.

4.4.2 Pre-Commissioning Checks

After erection of the preheater is completed and all the final inspection checks have been satisfactorily completed, it is essential that the following checks be carried out.

1) Inspect the inside of the preheater ducts for any loose materials such as planking, staging etc., and remove any such materials so found.

2) Check if the static parts on the APH will expand freely. Enough room shall be reserved between inlet door platform and APH to ensure end pillar and side hinged pillar will expand freely.

Special care: except the bottom girder and hinged side pillar, no other part of APH can be connected to boiler steel structure and platform!

3) Check that the preheater seal clearances are in accordance with the pre-commissioning setting stated on the cold seal setting chart.

Check that all site erection welds have been carried out as per the drawings.

Special care: check the bracket of sootblower lance to be reliable, not loosen, corrosion or crack, take measures to stiffen if necessary to avoid it dropping into APH rotor section and causing rotor jam and unit shut down.

5) Check direction of rotation of both the electric main drive motor and the emergency air drive motor against the rotation given on the Drive Unit Arrangement Drawing and check that the seals are fitted to suit this rotation.

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Special care: each time when we commission and rewiring, the rotating direction of individual motor must be checked and verfied. When check the running of the motor, it must ensure one motor was disenergized and rotor stopped completely, another motor can be checked.

6) Check that the preheater rotor bearings are filled to the proper level with the correct grade of oil (see Lubrication Section 5.3).

7) Check that the rotor is free to turn by means of the hand turning device provided, turning the rotor at least two complete revolutions.

Special care：Hand turning the motor must be executed with the hand turning device Howden provided, turning torque can not exceed the rated torque of driving motor to avoid damaging the motor.

8) Check drive unit inverter has been fitted and commissioned as required, ensure drive unit will be started via inverter.

9) Check if the water drainage of sootblower steam pipe is reasonable, if the pressure before sootblower valve and overheating meeting with design requirement.

10) Check that Rotor Stall Alarm is commissioned and energised.

11) Check that top and bottom bearing oil temperature monitoring equipment alarms/trips are set correctly and energised.

12) Check that sootblowing, water washing and fire detection services are commissioned and operational and that water supply is available for the fire fighting equipment.

13) Check that the drive unit is filled to the correct level or capacity with the appropriate lubrication (see section 5.3).

14) Check that the sootblowers are correctly lubricated.

15) Check that all tapping points to the ducts are completely clear of debris and blow out as necessary.

16) Check that all external insulation of the preheater has been completed as per relative standard (GB50264-97; DL/T5072-1997).

17) Check if the client gas duct and APH transition duct has been fitted with suitable expansion joint and necessary slinger guide device, ensure external force applied by APH at cold state will be kept minimum to ensure a long term safe operation.

4.4.3 Boil Out (No Gas Bypass)

During the early stages of commissioning when poor combustion is normally experienced, the following procedure should be adopted to reduce the risk of fire.

1) To eliminate potention fire, remove the combustible material, such as paper, putty, tape etc in the APH element.

2) Remove all heating elements which need to be boiled out in these two sectors at gas side of APH, then turn thes two sectors to the center of gas side and fasten it.

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3) Cover the elements (not supplied by Howden) at the top of rotor gas side and air side.

4) APH rotor shall be kept still during the procedure of boil out. To avoid starting up APH by mistake, cut off the power of motor and remove insurance in advance.

5) This procedure will provide a sufficient bypass for the small amount of gas produced by this boil out.

6) After boil out the element should be reloaded and all covers should be removed. Water washed or steam washed and inspected to ensure they are thoroughly clean befor the safety pressure valve was put into service.

4.4.4 Pressure Raising and Floating Safety Valves - (No Gas Bypasses)

During the period of floating safety valves fluctuating temperatures can produce abnormal rotor expansions that may lead to excessive seal wear or even in severe cases to rotor trip out, unless certain precautions are taken.

Normal seal plate positions cater for differential temperatures at the hot and cold ends of the air preheater rotor. This differential may not be maintained during safety valve floating if little or no air is passing through the preheater and may result in cold end expansions even at no load or little load conditions, exceeding those which will be encountered under normal design conditions at full load.

The rotor must be kept rotating throughout this process and fire detection equipment must be in operation.

A thermal balance must be maintained through the preheater by either increasing the air flow and/or air temperature or reducing the gas inlet temperature. With the steam air heater in operation pass the hot air through the preheater endeavouring to obtain a thermal balance.

Opening the access doors at the economiser outlet can reduce the preheater gas inlet temperature.

The quantity of air flowing through the preheater can be increased by introducing excess air to the furnace, air preheater and top burner boxes via the F.D. fan.

The preheater must be sootblown regularly during this period of operation.

4.4.5 Preparation of Preheaters for Rated Load

After all the pre-commissioning work is completed the air preheaters should be inspected closely with particular attention paid to the following:-

1) Cleanliness of Heating Surface

Prior to going onto commercial load the heating surface elements must be thoroughly cleaned by sootblowing or if this does not achieve clean elements, then by water washing.

2) Sealing Cleanrance

Special care：Hand turning the motor must be executed with the hand turning device Howden provided, turning torque can not exceed the rated torque of driving motor to avoid damaging the motor.

Before operate with full load, measure the rotor cold state seal clearlance and check with relative personnel.

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Note: without the permission of Howden Hua siter service engineer, adjustment of seal strip is strictly forbidden.

3) Fire detection device

Ensure fire detection device is in normal working.

4.4.6 Subsequent Re-floating of Valves

Any subsequent re-floating of safety valves should be carried out in accordance with our recommendations given under Section 4.4.4.

Note: Element cleanliness is important during periods where combustion is inefficient, and sootblowing during or immediately following such periods is recommended, especially with oil firing.

4.5 LUBRICATION 4.5.1 Rotor Bearings

The rotor bearings run in an oil bath and a regular check must be carried out on the oil level indicators to ensure adequate lubrication. Topping up with oil can be carried out during operation.

4.5.2 Drive Unit Reduction Gearboxes

All gearboxes are oil bath lubricated. Each gearbox has a filler/breather plug becides oil level sight glass. Topping up with oil can be carried out during operation through the filler/breather plug. Check oil levels once per month.

4.5.3 Drive unit

Drive unit bearing has been lubricated before leaving the factory. This bearing must be changed every 3 year.

4.5.4 Sootblower

Refer to sootblower manul for information.

4.6 STARTING UP

4.6.1 Normal Start Up

Consult Boilermaker's sequence for start up

1) Check that the air preheater rotor is free to rotate by means of the hand turning device.

2) Ensure hand turning lever being removed from main motor non-drive end shaft and all protective covers are fastened.

3) Check air preheater isolation dampers are closed.

4) Check sootblower lances are fully retracted.

5) Switch on fire detection equipment and check that it is operational by visual means on control panel.

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6) Ensure sootlbow pipe water drainage is normal, pressure before entering sootblower valve and overheating is normal.

7) Check that the supply of fire fighting water meet with requirements.

8) Check that rotor stall alarm system is operational.

9) Initiate cooling water to the top steady bearing housing and further check is the cooling water temperature, pressure and flow and cooling water circulation is normal.

10) Check if all manholes are closed.

4.6.2 Starting Operations

1) Energise Rotor Stop Alarm system.

2) Start main motor via inverter as per required rotating direction.

Special care: to protect the drive unit and reduce the start up torque and impact load and avoid damaging the drive motor and transmitting part due to the over high start up torque. The main and auxiliary motor must be started via inverter, it is strictly forbidden motor directly drive the rotor or multi-motor drive the rotor at the same time in the same direction or reverse direction.

3) Gas and Air can now be introduced into air preheater by opening isolation dampers.

5) Check boiler load conditions are satisfactory.

6) The air preheater should be sootblown as soon as possible after the boiler has reached a steady load, in accordance with recommendations given in Section 4.9.

4.7 CONTROL

When unit is being loaded, the following shall be controlled.

1) The "combined temperature" should always be above the absolute minimum for the plant.

2) It is recommended that the following observations are made once per day and a log kept of the readings:-

Measuring the level and temperature of oil in the top steady bearing and bottom support bearing.

Record the resistance at air and gas side.

The gas inlet and outlet temperature of APH

The air inlet and outlet temperature of APH

Motor current

Oil level of drive unit reduction gear box

Special care: watch closely that the APH inlet gas temperature will not rise up too quick to avoid rotor deform and further affect APH safe operation.

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4.8 SHUTTING DOWN

4.8.1 Normal Shut Down for Cold Start

Consult Boilermaker's sequence for shut down.

1) prior to reducing load sootblow the air preheater in accordance with the requirements in Section 4.9.

2) Stop FD and ID fan.

3) Isolate air preheater with dampers.

4) Keep the air preheater rotor turning to ensure that there is no risk of a fire within the air preheater and gas inlet temperature lower than 125℃ .

5) Switch off rotor stop alarm system.

6) Switch off the fire detection equipment.

7) Stop the air preheater main drive motor.

8) Stop cooling water supply to top steady bearing.

Note: If heating element surface was contamined with acid, it shall be water washed to reduce the corrosion to the minimum.

4.8.2 Normal Shut Down for Hot Start (i.e. Shut down up to 8 hours)

1) prior to reducing load sootblow the air preheater in accordance with the requirements in Section 4.9.

2) Stop FD and ID fan.

3) Isolate air preheater with dampers.

4) Keep the air preheater rotor turning to ensure that there is no risk of a fire within the air preheater and gas inlet temperature lower than 125℃ .

5) Keep the fire detection equipment in operation.

6) Keep circulating cooling water to top steady bearing.

7) Keep the rotor stop alarm switched on.

4.8.3 Emergency Shut Down

1) Failure of Main Drive and Emergency Drive Motors

If alarm from both rotor stop alarm sensors is received, the sensors and local panel power are healthy and neither drive motor is in operation then the I.D. Fan and F.D. Fan require to be shut down and the air preheater taken out of service.

2) Failure of Electrical Power

In the event of the main drive motor failure, the ermergency motor shall be started and keep runing as the previous rotating direction.

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In the event of rotor drive failure due to a "unit trip" the effect of leaving the rotor in the stopped position would result in abnormal rotor expansions causing fouls or seal rubs to the sealing plate surfaces.

Then APH should be immediately shut down.

It shall be at least after 30mins after power supply restored, can main motor be restarted. Start up procedure shall be as per 4.6.

Special care: if APH jam occurs, it is strictly forbidden to force turn the rotor by pushing the hand turning device to avoid damaging drive unit. Under this situation, APH gas/air side damper shall be closed on time, and open hot end gas side manhole. Suitably open ID fan damper to cool APH, and at the same time control the temperature difference between gas and air side not to big. APH can only be put into service when APH is enough cooled and can turn the hand turning device easily. Ensure the APH will be turned without being loaded with sufficient time till rotor deformation was maximizely restored. If boiler needs to be loaded, it shall be noted that load can’t be added too quick. Monitor APH current shall be increased stably. During the above procedure, watch APH fire closely.

3) Failure of System outwith Air Preheater

This constitutes a normal shut down for the air preheaters and Section 4.8.1 of this manual should be consulted.

Special care: In the event of current rise during shutt down, suitably open ID fan damper to cool APH, and at the same time control the temperature difference between gas and air side not to big. Ensure the APH will be turned without being loaded with sufficient time till rotor deformation was maximizely restored. During the above procedure, temperature lowered not more than 60 /℃ H and watch APH fire closely.

4.9 SOOTBLOWER

4.9.1 Comments on Sootblowing

1) The air preheater is fitted with two cleaning devices, one at the gas inlet and the other at the gas outlet. Each device consists of a semi-retractable lance for sootblowing using superheated steam as a medium.

2) The air preheaters are likely to require more frequent sootblowing than the boilers.

3) The sootblowers should be operated initially at least once per shift with the frequency adjusted, based on actual operating experience, to maintain the operation resistance within the range of the design figure.

4) In addition, sootblowing should be performed just prior to shutting down boiler and also on start up after reaching a steady load. The sootblowing prior to shutting down is required to remove deposits from the heating surface that can lead to corrosion of the element plates while the plant is cooling. Sootblowing following start up, is required to remove any smuts produced when withdrawing and inserting boiler burners which could ignite any deposits still adhering to the element surface of the air preheater.

It is also advisable to sootblow the air preheater following a situation that produced poor combustion conditions.

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To avoid risk of condensation on the element plates during sootblowing high heating surface temperatures should be maintained therefore whenever possible should be carried out on up to certain boiler load.

5) The air preheater sootblower type, medium and blowing frequency shall ensure heating element surface far from damage, otherwise, heating exchanging performance and lifetime will be affected.

6) When the air preheater is being sootblown in the same operation as the boiler and economiser, the air preheater sootblower should be operated last, as in the following sequence:

Boiler: Economiser: Air Preheater

7) To ensure an effective sootblow, one hand it is essential that there is no water or moisture leaking into the preheater. On the other hand, overheat steam with certain pressure and temperature must be selected to provide dry blowing medium. The APH blowing steam must be at least over 111~130℃, pressure before sootblower valve is required to be 1.5MPa at start up and 1.2MPa at operation.

8) It is essential to drain the line to the sootblowers before operation, normally thermal automatical water drainage will be adopted. Its working procedure is: open automatic water drainage valve, drain off condensed water, until the thermal couple displayed steam temperature reached the required value and delayed a period of time. Close water drainage valve, at the same time, open the steam inlet valve of sootblower automatically, sootblower motor will react and start to blow. Such will acquire a satisfactory sootblowing result to ensure APH will operate at good condition.

9) Water or moisture in the line will cause corrosion and may harden any deposit on the heating surface that would be impossible to remove by further sootblowing and result in chock and fouls becoming more serious.

Note: it shall be ensured that there is no water or steam leaking into APH from the fire fighting device, water wash valve, economizer and air heater etc which is essential to reduce heating element corrosion and foul.

10) The sootblower should therefore be operated initially at least once per shift (8 hours), with frequency adjusted following actual operating or when -：

The resistance across the air preheater above the design figure.

APH gas leaving temperature is too high.

The boiler first goes on load following start-up.

There has been a change in load.

Poor combustion has given rise to sooty conditions.

Before shutting down the boiler or air preheater

Special care: if this is not carried out, there are risks that a fire may occur, heating element foul and corrosion etc.

4.9.2 Sootblowing Procedure

The method of operation of sootblower described must be strictly followed to ensure that the heating surface is cleaned by the sootblower and the desired effect obtained.

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1) Suitable heat the steam pipe line and drain the sootblower pipe completely and effectively before starting sootblowing.

2) Operate the sootblowers as per manufacturers Instruction Manual

3) Ascertain that the sootblower valves are fully opened and that the required pressure is being maintained at the sootblower valve to ensure that blowing effect comply with the design.

4) Check that the timers for blowing are set correctly as designed. Otherwise, it can not guarantee the whole surface of heating element being cleaned completely.

5) At the finish of sootblowing check that the steam line valves are firmly closed.

6) If during the sootblowing operation it has been found necessary to raise the element plate temperature at cold end (by air heater or hot air recycling system) so as to maintain the "Cold end combined temperature" not lower than the recommended minimum value for the plant.

7) Also it is essential for the steam temperature to the sootblowers to be adequately superheated. Wet steam will only give poor cleaning and will create problems with element chokage, erosion of sootblower nozzles etc. and must be avoided.

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Section V MAINTENANCE OF PLANT

5.1 ROUTINE SERVICING

5.1.1 Sealing system

Check the seal clearance, adjust when necessary.

Note: all clearance have been set to suit the worse expected conditions to avoid damage to the seals.

The radial seal clearances at cold end should be checked by sealing clearance measuring device and measuring points on bottom sector plate and cold seal clearance against rotor be adjusted accordingly.

All sealing strips should be checked during the annual outage for wear and either replaced or reset in accordance with the following instructions.

5.1.1.1 Top and Bottom Radial Seals

Refer to Drawing No HSTD186001-29 and HSTD186003-2.

1） Fit the fixed radial seal seting bar.

2） Select one set of radial seals for one radial plate complete with cover strips and hand turn the rotor until seals are in alignment with the top sector plate. Reset the seals as site engineer requirement and tighten the fixings.

3） Turn the rotor until seals are in alignment with the setting bar.

4） Rotate the rotor by means of the hand turning device to bring remaining seals into line with the seal setting bar then fixed.

5） Take care not to damage seals when fitting and setting.

6） Remove the seal-setting bar.

7） Check that all cover plates and tighteners have been fitted.

5.1.1.2 Axial seal

Refer to dwg No. HSTD/185001-2，HSTD186004-2

1） Access to set or fit axial seals is by means of the axial seal doors on the rotor housing.

2） Rotate the rotor by means of the hand turning device until the selected seal is in line with the axial seal plate.

3） Reset the seals as site engineer requirement and tighten the fixings.

4） Fit the seal setting bar to the correct position.

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5） The mounted seal is in alignment with seal setting bar and set the bar to the seal.

6） Set the all axial seals to the seal bar.

7） Remove the axial seal setting bar.

8） Ensure all centre seal strip have been located and locked.

5.1.1.3 The usage of needle gauage for measuring APH seal clearance

1） The measuring point of needle gauage located outside the bottom sector plate, screw off the test point screw plug before take measures.

2） Loose the screw on the needle gauage, when the needle extend a certain length, tight the screw and nut.

3） Insert needle gauage onto the test points of sector plate, ensure the head of needle gauage flush with the internal surface of sector plate.

4） Align one radial seal strip with measuring point, screw needle guage carefully till the needle just contacting seal strip, then measure the clearance between the rings. Ensure rotor has turned one revolution before each time screwing in needle.

5） Record the seal clearance of each testing point.

Note:

① When measuring clearance with needle gauage, it must be careful enough to avoid damaging seal strips once needle gauage inserted too deep.

② Compare the cold seal clearance with real measuring clearance under hot state.

③ To obtain a correct reading, the initial setting of need gauage at hot and cold state shall be the same.

6） Take out needle gauage, replace screw plug.

Note: operator must wear protective clothes when measuring seal clearance with needle gauageb under hot state. It was strictly forbidden to contact hot gas directly, and eyes shall be protected.

The importance of measuring seal clearance under hot state

When APH operate under BMCR, seal clearance under hot state shall be measured frequently to determine the relative position between rotor and sector plate, as well as the deflection under hot state. Based on this clearance, readjust cold state seal clearance or pre-adjust rotor position.

5.1.1.4 Circumferential Sealing

1) Outer Hot End and Cold End Seals

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Refer to 189001.

Check the cold end seal stiffeners to see if any loose or corrosion.

After commissioning check the seal edges for signs of rubbing and re-set if required.

2) Top and Bottom Inner Circumferential Seals


These seals are set flush with top and bottom radial seals.

3) Hub Seals


The top and bottom hub seals are set to zero clearance with the rotor hub and should be checked for wear.

The hub seals are attached to the inner face of the sector plates. To gain access to these the gland seal assembly indicated on drawing must first be removed.


Refer to Drawing No.136001，11843/2M (Renold) and subcontractor drawings

The following points should be checked:

1) The complete drive assembly for security on its mountings and in particular the torque arm connection every three months.

2) The oil ventilators in the reduction gear units every three months.

3) A monthly check should be made on the oil levels in the reduction gear units. Refer to Section No. 5.3 for lubrication details - do not overfill.

5.1.3 Rotor Top/Bottom Bearings

Refer to dwg.136001 and 144001.

1） The oil level in both the top and bottom bearing housings should be checked weekly and maintained with the correct quantity and grade of lubricant. (See Lubrication Section 5.3)

2） See Sections 5.3 for oil filling and grade of oil.

In order to predict when a bearing is likely to fail , regular (every four months recommended) monitoring by taking oil samples from bearing oil bath will enable the amount of metal in the oil to be determined. A prediction can therefore be made giving adequate notice of a problem bearing which allows a replacement to be made during a normal annual outage period.

5.1.4 Drive Motors

1) Every 3 years the bearings in all motors should be examined and greased in accordance with Section 5.3.

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2) During examination of the bearings care must be taken that ingress of dirt or foreign matter does not occur through contaminated grease, etc.

5.1.5 Sootblowers

1) Check complete unit for security on its mountings, block of nozzle and corrosion, as well as the seal and corrosion of spray gun during annual outage.

2) Check for signs of oil leakage or for signs of steam leaks every 3 months.

3) Check gun tube retracted freely and inner support bracket security. Fixed bracket if found problems to prevent from droping into rotor sector to jam APH and damage seals, result in shutting down.

5.1.6 Fire Fighting Equipment

During annual boiler outage check that each fire-fighting nozzle terminates with a bursting disc. If any

bursting discs are missing these will require to be replaced. Also check the nozzles themselves for signs of

corrosion or erosion and replace if required.

5.1.7 Local Control Panel Inspection Procedure

Except checking the internal indicator, the local control panel door shall ensure to be closed.

Open the front door monthly, push the test button and check the conditions of indicator.

By opening the front door the panel indicators, push buttons and switches can be inspected for mechanical damage. If necessary clean the panel

5.1.8 Fire Detection Probe Inspection Procedure

Fire detection probes comprise very sensitive components and as such it is imperative that the probes are not roughly handled. Each probe can be removed from its air preheater in one length.

Warning: if fire detection probes are being withdrawn from the ducts when the boiler is in operation, protective clothing must be worn and personnel should always keep any unprotected skin well clear of opening in the duct as a safeguard against hot blast of air escaping.

Each probe guide tube is permanently welded on top structure in a position to ensure that the probe is at its correct angle thus simplifying probe replacement.

5.1.9 Element Inspection

During boiler outage the heating surface elements should be examined for corrosion, foul and deposits which have resisted removal by sootblowing.

If necessary wash the elements and renew any badly corroded or damaged heating surface. For washing recommendations refer to Section 5.2. Increased pressure drop across the air preheater is an indication of element chokage or corrosion.

Damage to heating surface elements may be caused by sootblowing with pressure in excess to that recommended.

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5.1.10 Air Preheater

During annual outage the following should be checked:

The internals of the air preheater should be checked for any signs of either corrosion or erosion and a record kept of the extent found.

Sector plate, axial seal plate and seal strips shall be checked for friction.

All internal bolts should be checked for loose and damage.

All closing plates between sector plates and false plates should be checked for signs of leakage paths.

This also applies to the sealing between axial seal plates and end pillars.

The externally insulated surfaces should be checked for damage and repaired as found necessary.

Check the expansion joint for leakage and damage.

Special care: for exposed or half-exposed APH, at the bad wether condition, it shall be inspected frequently to ensure the insulation of APH will not leak. Take weather-proof measures to avoid rain when necessary. It was strictly forbidden to have rain water or snow leaking into insulation layer to avoid rotor jam and further lead to unit trip.

5.2 ELEMENT WASHING

5.2.1 Cleaning of Elements

If regular sootblowing is carried out, water washing should not be required assuming of course that the air preheater is being operated under normal conditions. From long term operation experience, indication was brought out that sootblowing is effective method to control deposite accelerating speed.

If regular sootblowing is not cleaning the heating surface elements, steps should be taken to find out the

reasons for this. When the resistance of APH exceeds the design value but lower than 130% of design value,

low pressure washing should be adopted. Low pressure water washing device is designed one piece with

steam sootblower, which is motorized half-retracting doule lance structure. Each washing lance is fitted with

sufficient nozzles to adequately cover the rotor surface. The washing lances are installed primarily to clear

the deposit from the hot and cold end elements.

After washing it is necessary to inspect the heating surface to determine if further washing is required. It

should be noted that, once water washing is started, complete cleanliness of the heating surface elements

should be aimed for, since only partial washing leaves a deposit on the heating surfaces which bakes hard

when the air preheater returns on-load, which can not be removed by washing in next time. Therefore,

elements must be cleaned before APH runing on load. To reduce water washing time and the corrosion

caused thereof, we recommend to improve water temperature up to 50∼60 . Howden will not suggest to ℃

adopt alkaline water washing on the coal-fired unit.

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Water washing is normally carried out under low speed, therefore water drainage pipe should be fitted at

gas and air side. If possible preparation for washing should be started before the preheater is taken off load,

in order that the metal temperature of the element surface will still be warm (30- 40℃ higher than ambient

temperature) for deposit removal.

Special note:

1．After water washing completed, it shall be dried with hot air to avoid the corrosion of APH and other equipments.

2．When the resistance of APH exceeds 30% of design value and element being fouled seriously, it shall be subjected to HP washing as earlier as possible.

5.2.2 Water Washing Procedure

It is our recommendation that water washing be carried out when the boiler is off-load to the following

procedure:

1） Stop the air preheater rotor and ensure that the main and standby drive motors are electrically isolated.

2） Inspect the heating surface elements to ascertain the extent of deposit on the elements, precautions

under Section 5.6 must therefore be observed.

3） Check the direction of water washing nozzle, ensure they will not be blocked.

4） Check that the drains in the ducting below the preheater are open and flushing water can be drained

effectively.

5） Restart the preheater rotor by means of low speed motor or frequency inverter.

6） Ensure that water supply is available and proceed to wash the heating surface elements.

7） After the initial water washing completed, a visual check on the cleaness of heating element shall be

carried out on element baskets. The personnel performing this should wear protective clothes, note

waste liquid takes no acid.

It was highly suggested that the inspection should be checked by two person together, i.e, one person hand

turn the rotor slowly and lighting with torch from bottom to top, the other one will check heating elements

from top.

Special care: Not to injure operator with the rotating rotor.

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The heating element shall try to be thoroughly cleaned at the initial washing period, or else it will short the life

time of APH heating element. After water washing, the residule deposit will be harden and difficult to be

removed during the next time cleaning. Therefore, if it was found heating element was not cleaned at the

initial period, the next cycle of water washing shall be started.

8） Having thoroughly washed and dried all sectors of the rotor with hot air, stop the rotor.

9） Remove all debris from inside the ducts and replace all access doors.

10） Electrically re-connect the main drive motors.

11） Test that Fire Detection Equipment is operating correctly.

12） Check that all drain valves in bottom ducts are closed.

13） The air preheater is now ready to start under normal start up conditions in accordance with that

stipulated under Section 4.6.

5.3 LUBRICATION

5.3.1 Air Preheater Top and Bottom Bearings

Both bearings are lubricated by means of an oil bath. The bearings should be drained, flushed out with a

good quality of flushing oil if considered necessary and refilled with correct grade and quantity of oil.

A synthetic lubricant can be used to give longer life therefore oil replacement should only be required every

10,000 operating hours. If mineral lubricant applied, replace it at annual outage.

Note: hand turn the rotor where flushing is carried out.

Filling is carried out via the oil filler and and must be done during the erection of the air preheater.

Don’t overfill. Do not mix synthetic lubricants with mineral lubricants.

5.3.2 Reduction Gear Units

For the secondary and primary units the lubrication system is self contained, positive and automatic at all speeds of operation. Effective oil seals prevent leakage and the only attention required in service is a visual check to ensure that there is no leakage. It is most important to ensure that the correct level of oil is maintained in the units via the oil level sight glasses.

The recommended lubricant must be synthetic and must not be mixed with mineral oils. If mineral oil required, fill with mineral oils.

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An oil change should be carried out every 10,000 operating hours or every three years. These figures may be necessary to change the oil at more frequent intervals if working under severe conditions. For full details refer to manufacturer literature.

The unit is provided with a ventilator which, in order to function correctly, must be maintained in a clean condition. See Suppliers literature for oil breather/filler, oil level sightglass/grease fittings and oil drains.

These units are despatched to site with the correct grade and quantity of oil. However, this should be re-checked at erection.

5.3.3 Lubrication of Drive Motor

These motors have ball bearings, which are filled initially by the manufacturers with their grade of grease. The motors do not have grease nipples the bearings being pre-packed with grease for a life of 3 years. After 3 years, remove motor and refill this bearing with suitable grade grease.

5.3.4 Lubrication of sootblower

Refer to sootblower manual for the detail of sootblower lubrication.

5.3.5 General

Where it is found necessary for flushing oils to be used to clean out units do not use paraffin as this may promote the formation of rust.

When topping up or renewing oil ensure that overfilling does not take place as excessive oil only results in churning with consequent overheating.

5.3.6 Lubrication Schedule

PART RECOMMENDED LUBRICANT

QUANTITY REQUIRED PER AIR PREHEATER

FREQUENCY LUBRICATION

POINT

APPLICATION METHOD

Air Preheater Rotor Main Bearings

(Top and Bottom)

High grade synthetic oil MOBIL SHC 639

VG1000

Top bearing：20L

Bottom bearing：40L

Every 10,000hours or

2 years.

Top and bottom bearing

housings by oil bath

Filler on bearing

housings

Main gear box

TSMWD17①

(Renold)

High grade synthetic oil SHELL OMALA

320RL288~352 Cst (40 )℃

125 lit Refer to

manufacture documents

Main gear box (oil bath) Oil filler plug

Note: the datas in above table are just for first oil filling of drive unit, the detailed information pls refer to Renold document.

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PART RECOMMENDED LUBRICANT

QUANTITY REQUIRED PER AIR PREHEATER

FREQUENCY LUBRICATION

POINT

APPLICATION METHOD

Motor gear reduction

box GMF5D

(Renold)

High grade synthetic oil

SHELL OMALA 320RL

288~352 Cst

(40 )℃

2x2 L Refer to

manufacture documents

Motor gear box (oil bath) oil filler plug

Sootblower Refer to subcontractor documents

Note: for the parts not specified lub oil type, pls refer to the manufacture manual for information.

5.4 Coupling

Main motor is connected to primary gear box via flexible coupling. The final reduction gear box output shaft is fastened to rotor drive shaft via a shrink disc.

5.5 FAULT FINDING - LOCATION AND RECTIFICATION

5.5.1 Air Preheater in general

Failure of the air preheater mechanism may be as a result of power failure, check that power is available to the main drive motor. If power is available but still there is no rotation, a continuous overload reading of the ammeter or operation of the overload cut out will indicate mechanical fouling of the rotating parts. Switch off the electric power and turn the rotor by the hand turning device to free the rotor or locate the source of the fault. This may in fact free the rotor. However if this does not suffice, and the rotor still does not start, then the air preheater must be fully checked for mechanical failure or foreign matter being present within the air preheater.

Note; stopping the air preheater requires the boiler plant to be shut down or close all inlet/outlet damper of the faulty APh and reduce boiler load to be below 60%.

Check top and bottom sector plates for foreign matter having become jammed

Check that all radial, axial and outer circumferential seals are tightly secured.

Check all reduction gearboxes and drive couplings.

Not only should the repair of the defective item be undertaken, but also an investigation should be

undertaken to ascertain the reason for the failure and measures taken to prevent a recurrence.

Should the air preheater efficiency be reduced, as indicated by the gas outlet temperature increasing and air

outlet temperature reducing with increasing pressure loss across the air preheater elements, then this would

indicate fouling of the elements and at the worst, corrosion. If this condition is not cleared by sootblowing

then the elements should be inspected at the first opportunity, since such a condition could result in a fire,

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within the preheater, due to the excessive deposits on the elements.

A sudden increase in temperature will result in the Fire Detection equipment initiating an alarm, then follow

the requirements in 4.3 to put the fire fighting equipment into service immediately if doubt or asure firing in

the rotor.


Failure of the main drive motor should initiate the emergency electric drive motor. Failure of both main electric drive motors necessitates either isolating the air preheater or shutting down the boiler.

Failure of motors may be due to the electrical supply being cut off or through overload or a blown fuse. If supply of power to the motor is proven, then either the motor is faulty or there is a seizure, or breakage’s in the transmission.

Uncouple the motor and try turning it by hand. If it is free to rotate, then switch on power, briefly, to prove the motor. If each motor is proven, then the gearbox assemblies must be removed for inspection. For removal, of the primary and secondary reduction gear units, refer to Section 5.7.

5.5.3 Bearing and Gearing Lubrication

Total loss of oil from a rotor bearing or from a reduction gearbox requires in immediate shutdown of the air preheater.

Loss of oil from bearing housing would indicate a fault in the oil filler assembly and this should have alarmed under the high temperature alarm system. Loss of oil from a gearbox would indicate an oil seal failure.

5.5.4 Sootblower

Check the sootblower pipework for leaks whilst the system is in operation. Repair any leaks that are found. Worn or damaged flange jointing or gland packing should be renewed as soon as possible.

Poor sootblowing when full steam pressure is available will indicate leaks or eroded nozzles, these should be rectified or replaced as soon as possible.

Check that steam lines are properly drained of condensate and that the water shuts off valves do not leak when closed, this is very important as element corrosion can result.

5.5.5 Fire monitoring device

Pls refer to subcontractor documents.

5.6 PRECAUTIONS BEFORE MAINTENANCE


Obtain a work permit.

Ensure that personnel involved fully understand the Health and Safety at Work Regulations.

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Ensure that the air preheater is electrically isolated and locked thus.

Removes all access doors from the gas and air ducts.

Ensure adequate ventilation and air supply within the air preheater, check for poisonous gases, and the

temperature of the air preheater before entering.

Check that the steam supply to the sootblowers and water supply to the water washing are completely

shut off, ensure that water supply to fire fighting equipment is shut off and valves completely isolated.

Arrange means of portable lighting for use inside duct.

Arrange for necessary staging to enable access to be gained below the air preheater rotor in both ducts.

Ensure that the air preheater rotor is not turned by means of the hand turning device when personnel

are inside ducting without first giving adequate warning.

Wear suitable protective clothing and respirator.




Ensure that main and standby drive motorsare electrically isolated and locked out. If the electric motor is to be lifted off, disconnect the power leads from the terminal box.

5.6.3 Sootblowers



Ensure air preheater is electrically isolated and locked.

Ensure that steam supply is shut off and ensure that any electrically operated valves are closed and

isolated.

Remove the access doors from the gas ducts.

Ensure adequate ventilation and air supply within the air preheater.

Check within the air preheater for poisonous gases before entering.

Arrange for necessary staging to enable access to be gained below the air preheater rotor in both ducts.

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Ensure that the air preheater rotor is not turned by means of the hand turning device when personnel

are inside ducting without first giving adequate warning.

Arrange suitable portable lighting for use inside the duct.

Wear suitable protective clothing and respirator.

5.6.4 Local Control Panel


Ensure that personnel involved fully understand the health and safety at work regulations.

Open front door of panel.

Switch off the power supply

5.7 Removing and maintenance

5.7.1 Removing and Replacing Element Packs

Refer to Drawing No. 200001 and HSTD/200-1.

All element packs require to be lifted directly upwards from the rotor via the top gas side duct using the

special lifting slings provided.

To minimise the hand turning of the rotor and to keep the time involved as short as possible it is always

recommended that the new element packs are replaced as the old ones are removed. If this procedure is

adopted then the rotor is always kept in balance.

The following step by step procedure should be adopted:-

1) Electrically isolate the drive motor supply

2) Remove element-handling door in top gas inlet duct.

3) Install runway beam (not Howden Hua Limited supply) in gas duct.

4) Install hoist onto runway beam

5) Open access door in top gas inlet duct to enable access to be gained to the APH.

6) Turn the rotor by means of the hand turning device, until one sector of the rotor is directly below the

runway beam.

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Note: Great care is required when hand turning the rotor to ensure that personnel within the air preheater are not in danger of being injured!

7) If new packs are readily available then those should be replaced immediately the old ones are removed

from the rotor thus saving handling time.

8) Remove the top radial seals and cover plate as per 5.7.2.

9) Starting at the periphery of the rotor remove the outer packs by a direct lift upwards until clear of the

rotor, then through the door and hence to the dropping zone.

10) Repeat steps 8 and 9 and remove and replace packs.

11) Turn the rotor by means of the hand turning device provided and repeat steps 8-10 inclusive until all

element packs have been removed and replaced.

12) If new element packs are not readily available and it is proposed to remove all the element packs

leaving the rotor empty then it is imperative to remove packs from diametrically opposite sectors in such

a manner to avoid unbalance of the rotor.

13) The reverse procedure should be adopted when replacing element packs remembering to avoid

unbalance of the rotor.

5.7.2 Removing and Replacing Top Radial Seals

Refer to Drawing No. HSTD186001-29。

The top radial seals are the straight seal strips that are bolted along the radial division plates. These seals

are removed by removing the aerotight nuts and set screws securing the seals to the rotor plates, turning the

rotor by hand, using the hand turning device provided, to gain access as required.

When replacing these seals they should be set in accordance with the procedure stipulated under Section

5.1.1 of this manual using the seal setting bar provided. Ensure that they are positioned to suit direction of

rotation as indicated in the drawing.

Check the aerotight nuts, set screws and cover strips for corrosion or damage and replace as found

necessary.

After all seals have been fitted and checked replace access doors.

5.7.3 Removing and Replacing Bottom Radial Seals

Refer to Drawing No. HSTD186001-29.

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The bottom radial seals are the straight strips that are bolted along the radial division plates. Scaffold and

safety plank the bottom air inlet duct as required. These seals are removed by removing the aerotight nuts

and set screws securing the seals to the rotor plates, turning the rotor by the hand, using the hand turning

device provided, to gain access as required.

When replacing these seals they should be set in accordance with the procedure stipulated under Section

5.1.1 of this manual using the seal setting bar provided. Ensure that they are positioned in line with the axial

seals as indicated in the drawing.

Check the aerotight nuts, set screws and cover strips for corrosion or damage and replace as found

necessary.

After all seals have been fitted and checked replace access doors.

5.7.4 Removing and Replacing Axial Seals

Refer to Drawing No. HSTD/185001-2.

The axial seals are the straight seal strips bolted to the radial division plates, at the periphery of the rotor.

These seals are removed by removing the aerotight nuts and set screws securing the seals to the rotor

plates.

Doors are provided on the rotor housing local to each end pillar. These doors should be removed for

examination or replacement of the axial seals as required, the rotor being turned by the hand turning device,

to bring each seal into line with the access doors.

When replacing axial seals they should be set in accordance with the procedure stipulated under Section

5.1.1 of this manual using the seal setting bar provided. Ensure that they are positioned in line with the top

and bottom radial seals.

Note that there is a trimming allowance for fitting.

After all seals have been fitted and checked, replace all access doors.

5.7.5 Removing and Replacing Circumferential Seals

Refer to dwg No. HSTD186001-29、189001.

1) Bottom Outer Circumferential Seals

Access to these seals is from inside the bottom gas, air ducts. These ducts require temporary scaffolding

and planking to gain access to the seals.

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These strips are in sections to facilitate handling and are replaced by removing the domed nuts provided on

holding attachment.

Check the aerotight nuts and washers for corrosion or damage and replace as found necessary.

2) Top Outer Circumferential Seals

Top outer circumferential seals welded on plates on top of the rotor housing. If they are found to be damaged

new seal bars should be welded in position as shown in 189001.

3) Inner Circumferential Seals

The seals are secured to the fixed annular seal support bar at both the top and bottom of the rotor hub. To

replace the set screws require to be removed and the seal strips slipped out. Hand turn the rotor as required

to gain access to each seal strip.

When replacing seals ensure the seals are set with the radial seals.

Check the setscrews and washers for corrosion or damage and replace as found necessary.

5.7.6 Removing and Replacing Hub Seals

Refer to dwg No. HSTD182-00.

The hub seals are double seal arrangement, mounted on the sector plate, seal against hub. The inner seals

consists of rings, manufactured from Corten steel, 1.6mm thick. Two rings are fixed with mild carbon steel

supporting ring, inner seal was fitted to sector plate directly.

These seals are each split in two to facilitate removal and mounting.

Outside seal are packing seals. The supporting plate of packing material seat is fixed to the stiffeners of

sector plate. Packing material is non-asbestor material. Temperature withstanding temperature shall be

not lower than 500℃. There are three layers for packing material, section area is 15mmx 15mm.

The packing chamber between the hub and outside seal, being provided with two channel ducts directly

going to gas side, will lead air and ash into packing chamber by the negative pressure in the gas side.

5.7.7 Removing and Replacing Sootblowers

If it is found necessary to remove the complete sootblower from the air preheater ducting the following

procedure should be adopted:-

1) Electrically isolate main drive motor

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2) Isolate steam, electrical supplies and water supplies to the sootblower

3) Disconnect steam and flushing water inlet flange

4) Disconnect electrical supply cables to the terminal box.

5) Support the sootblower assembly externally from the air preheater by means of suitable slings and take

up slack.

6) Disconnect sootblower assembly flange from APH

7) Disconnect sootblower from permanent support structure

8) The wall sleeve should be left in the air preheater housing to ensure correct re-assembly of sootblower.

9) For replacing sootblower reverse the above procedure with personnel being inside duct to guide lance

through the wall sleeve and through the internal support.

After replacing sootblower it is recommended that the travel checked manually to ensure that the nozzles

and limit switches have not been disturbed.

5.7.8 Removing and Replacing Drive Motor

Refer to Drawing No 136001、200001 and subcontractor’s manual.

1) Ensure that electric power supply to the motor is disconnected

2) Arrange suitable lifting equipment

3) Sling motor and take up slack

4) Remove the mounting bolts in the mounting flange of the motor.

5) Carefully withdraw the motor from the gear unit, until two halves of the coupling splited.

6) Remove motor to service area.

7) To replace the motor it is a reversal of the above procedure. Pay attention to position of halves of the

coupling.

Refer to motor documents for maintenance.

5.7.9 Removing and replacing the primary gear

1) Remove motor as per requirements in 5.7.8

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2) Mount the suitable lifting device and take slack.

3) Remove fixing screws to disconnect primary and secondary gear.

4) Lift to the designated place.

5) The replace is totally contrary to above

Refer to sub contractor documents for maintenance the gear box.

5.7.10 Removing and replacing the secondary gear

1) Remove motor as per requirements in 5.7.8

2) Remove two primary gears as per requirements in 5.7.9

3) Mount the suitable lifting device

4) Remove shaft end protective guard.

5) Remove rotor stop alarm and target plate.

6) Remove tightening disc from the top of driving shaft as per 136001.

7) Lift the gearbox vertically and evenly until clear of torque arm, then continuously lifting until totally

clear of driving shaft.


9) The replace is totally contrary to above, tighten shrink disc following the correct procedure to the

torque 240Nm.

10) After mounting shrink disc, make sure all parts of rotor stop alarm will be adjusted to initial position.

11) Paste anti-friction material on the torque arm and its braket to ensure the correct clearance on both

sides.


Make sure the correct mounting of oil seal and bearing.

5.7.11 Removing and replacing of center drive unit

Refer to Drawing No. 136001、200001 and subcontractor manual.

1) Ensure that electrical supply of both motors are disconnected

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2) Arrange suitable lifting equipment

3) Sling the complete assembly carefully and take up slack

4) Remove cover guard

5) Remove rotor stop alarm and target plate.

6) Remove tightening disc from the top of driving shaft as per 136001.

7) Lift the gearbox vertically and evenly until clear of torque arm, then continuously lifting until totally

clear of driving shaft.


9) The replace is totally contrary to above, tighten shrink disc following the correct procedure to the

torque 240Nm.

10) After mounting shrink disc, make sure all parts of rotor stop alarm will be adjusted to initial position.

11) Paste anti-friction material on the torque arm and its braket to ensure the correct clearance on both

sides.


5.7.12 Removing and replacing Top Steady Bearing

Refer to Drawing No. 136001.

1) Remove the rotor drive assembly as per Section No. 5.7.11.

2) Temporary bracing should be arranged between the rotor and the rotor casing to prevent rotor tilt when

the top steady bearing is removed. This is important and sufficient bracing must be installed to ensure

that the rotor is held in its vertical position.

3) Drain the oil from the top bearing housing.

4) Loosen shrink disc as stated in drawing and remove from mounting bell.

5) Remove the top cover plate

6) By using the removal holes provided on the top face of the bearing mounting bell sling and carefully

remove mounting bell complete with top steady bearing vertically upwards.

7) Remove this assembly to service area.

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8) By removing the bearing retainer ring the steady bearing can now be withdrawn from the mounting bell.

9) To replace top steady bearing the reversal of the above procedure should be adopted.

Note: this top steady bearing will adopt CARB bearing,, it must be ensured that top bearing top cover in line with the “0”line on the top bearing mounting bell (refer to 136001).

Ensure that shrinc disc shall be correctly tightened to 470NM.

If it is found necessary to remove top steady bearing it is recommended that The top and bottom white felt

packing and the Klingersil joint are also replaced.

5.7.13 Removing and replacing Bottom Thrust Bearing

Refer to Drawing No. 144001、154001、200001.

1) Isolate the driver motors

2) Remove the wire mesh guard at both end of bottom bearing

3) Drain the oil from the bottom bearing housing

4) Disconnect the temperature monitoring thermocouple from bottom bearing housing thermowells

5) Remove the top inner circumferential seals. Refer to Section 5.7.5

6) Remove the top radial seals under the centre portion of top sector plate. Refer to Section 5.7.2.

7) Remove the bottom bearing housing retaining segment in way of removal direction.

8) Install the hydraulic jacks as per drawing No. 154001.

Note: the jacking height of bottom bearing house should not be over 10mm to avoid damaging top bearing (especially CARB bearing).

9) Ensure hydraulic system working correctly

10) Install removal rails and associated supports as shown in Drawing No. 200001

11) Install replacement pull point across the bottom girder.

12) Arrange suitable pull lift and wire rope (not Howden Power supply).

13) Unload hydraulic jacks and drain oil from cylinder.

14) Carefully withdraw bottom bearing housing complete with bearing from its location onto the suitable

skid rails and withdraw to destination area.

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15) Remove spacer/cover from bearing.

16) The following procedure shall be followed when removing bearing house and bearing:

a) Insert three wedges beneath the surface of bearing bottom outer ring or adopt lifting device.

b) Knock wedge carefully to loose bearing to match with bearing house.

c) Remove the bearing.

d) Remove the inner ring from bearing top

Remove outer ring and roller assembly by using sling and the lifting device which has inserted under

bearing bottom outer ring.

17) The replace of bottom bearing reverse the above procedure. After bearing house being moved to

removing rail, bolted with lifting lug on the other side of bottom girder, and pull the bearing house into

position.

Note: Inser washers of suitable height between the bottom bearing house and bearing stool.

Special care：This top steady bearing will adopt CARB bearing, it must be ensured that top bearing top cover in line with the “0”line on the top bearing mounting bell (refer to 136001)when replace.

18) Apply anti-friction material between drive unit torque arm and braket, ensure they match well before

rotor test run.

19) Replace bottom bearing bolt and limit, tighten them as required.

20) Replace top radial seals and inner circumferential seal strip as per 5.1.

21) Remove all auxiliary devices and hand over to relative department for storage.

22) After verfied bottom bearing house has been located correctly, hand turn rotor at least one revolution

to ensure rotor will rotate freely.

23) Replace bearing protective guard when bottom bearing maintenance completed.

5.7.14 Removing and Replacing Rotor Stop Alarm Sensor

Refer to Drawing No. HSTD/196-1。

1) Electrically isolate the rotor stop alarm system.

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2) Unscrew locknut from sensor body.

3) Open the local junction box and disconnect the wires from the terminals.

4) Replace sensor by reversal of the above procedure ensuring that sensor tip is adjusted to its correct

position from the target plate bolted to the end of the drive shaft.

For detail of operation and maintenance refer to sub-contractors instructions manual.

5.7.15 Removing and Replacing Fire Detection Probes

Refer to Drawing No. 368001.

Fire detection probes comprise thermoal couple so it is imperative that the probes are not roughly handled.

Each probe can be removed from its air preheater in one length.

Warning: if the fire detection probes are being withdrawn from the ducts when the boiler is in operation protective clothing must be worn and personnel should always keep any unprotected skin well clear of opening in the duct as a safeguard against hot blast of air escaping. Compressed air should be supplied as sealing air to awoid this.

Each probe guide tube is welded on the top structure to ensure that the probe is at its correct angle and

that the probe tip is the correct distance away from the heating surface area thus simplifying probe

replacement.

5.7.15.1 Remove the probe

1) Electrically isolate the probe and disconnect the probe.

2) Open air-cooling valves situated on the guide tube and ensure that cool air is flowing into guide tube.

3) Remove the stiffeners of probe flange.

4) Withdraw the probe from the guide tube taking care not to damage the thermocouple at the end of the

probe.

5) If replacement probe is not being immediately installed blank off the opening in the guide tube by

means of blanking plate.

5.7.15.2 Cleaning and Inspection of Probe

1) Wire brush the probe tube to remove any deposits. Do not wire brush the thermocouple.

2) With a soft bristle brush and weak solution of washing soda, carefully clean the thermocouple end of the

probes. Rinse with clean water and allow probe to dry off quickly.

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3) Inspect the probe for any signs of corrosion or damage to the thermocouple.

4) Continuity Test: Check the resistance of the thermocouple at the probe socket terminals. A resistance

reading in excess of 30 Ohms indicates a defective thermocouple.

5) Check resistance between each thermocouple and earth. If low, then thermocouple insulation is

defective.

6) Replace a faulty probe with a spare probe.

7) The faulty probe should then be repaired and kept in store for future use.

5.7.15.3 Replacing the probe

Warning: personnel handling fire detection probes when boiler is on load must wear protective clothing.

1) Ensure that the sealing air valve is open before removing the blanking off plate covering the guide tube

flange.

2) Ensure that thermal insulation joint between probe flange and guide tube flange is fitted.

3) Carefully install probe into guide tube ensuring that probe tip is not damaged.

4) Re-connect the probe.

5) Re-wiring

6) After probe has been replaced remember to shut off the air cooling valve.

7) Energise control panel, restart its function and work normoally.

Note: The sealing air is only required when removing and replacing a probe.

5.7.16 Remove and Replace Fire Detection Probe Thermocouple

Refer to dwg No. 368001。

1) Removing the Thermocouple

a) Disconnect screw from thermocouple terminal head.

b) Remove gland and olive piece.

c) Remove thermocouple.

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2) Replacing the Thermocouple

a) Gently push thermocouple through gland and probe tube.

b) Fit terminal box. Avoid thermocouple wires twisted when mounting terminal box.

c) Reconnect thermocouple wires in terminal head.

d) Place completed probe in store.

5.8 PRECAUTIONS AFTER MAINTENANCE


1) Ensure that all tools and equipment have been removed from inside the ducts etc.

2) Check all parts on which work has been carried out, for security of mountings.

3) Check that any bearings that have been serviced are recharged with the correct grade and quantity of

lubricant.

4) Rotate the air preheater by means of the hand turning device for at least one complete revolution to

prove freedom of rotation. If this proves to be unsuccessful it is essential to find out the cause of

obstruction.

5) Remove all internal staging.

6) Replace and secure all access doors ensuring that all personnel have vacated the area.

7) Restore power to the drive motors

8) Restore power to all other electrically operated equipment.

9) Check that steam is available for sootblowing.

10) Check that water is available for water washing and for fire fighting equipment.

11) Switch the air preheater main drive motor on momentarily to check direction of rotation and, also, carry

out same check for other drive.

Note: when commissioning or cabling, rotating direction of each motor must be checked and verified. In adiition, motor can only be started when the other must was electrically isolated and rotor completely stopped.

12) Check that all interlocks for drive motors are connected.

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13) Check that rotor stop alarm equipment is operational.

14) Check that fire detection equipment is operational.

15) Check that drains in lower ducting are closed.

After complete plant has been deemed to be safe, return permit to work.


1) Check the oil level in all reduction gear units.

2) Check that all oil breathers in primary and secondary reduction gear units are clean.

3) Check the security of mounting, in particular the torque arms bracket, and arm move freely in bracket

in vertical.

4) Rotate by hand to prove freedom.

5) Check that electrical supply is connected to the motor

6) Switch on briefly to prove direction of rotation of motors.

Note: when commissioning or cabling, rotating direction of each motor must be checked and verified. In adiition, motor can only be started when the other must was electrically isolated and rotor completely stopped.

After plant has been deemed to be safe, return permit to work.

5.8.3 Sootblowers

1) Ensure all tools and equipments have been removed from the gas ducts.

2) Manually operate sootblowers to ensure that full travel of lance can be obtained without fouling, and

remove hand crank.

3) Ensure the guide support in APH is strongly connected, and corrosion-proof.

4) Remove all internal temporary staging.

5) Replace and secure all access doors ensuring that all personnel have vacated the area.

6) Ensure that sootblower mountings are secure.

7) Reconnect the electrical supply to the unit.

8) Ensure that steam supply is available.

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9) Reconnect the drive motors.

After plant has been deemed to be safe, return permit to work.

5.8.4 Local Control Panel

1) Check that the inside of the panel is completely clean.

2) Switch mains circuit breakers to 'On' position.

3) Push down test button to check the equipment.

After panel has been deemed to be safe, return permit to work.

5.9 SPECIAL TOOLS

Unless otherwise noted, the quantity below is just for one boiler.

Description Quantity Drawing No.

1) Hydraulic Jacks (two set in the contract, comprises the follows for each)

109 Tonne Hydraulic Jacks 4 sets 154001

High pressure oil pipe 4 pcs 154001

Hydraulic hand pump with flexible piping 1 set 154001

2) Bottom Bearing Removal（in this contract）

Bottom bearing removal rails 1 set 200001

Pull point for bottom bearing removal 1 set 200001

3) Hand Turning

Hand Turning Devices (accompany supplied with drive unit) 1 set 11843/2M (Renold)

4) Fire fighting probe

Simulated probe 1 off 368001

Valve lever supplied with fire probe 1 off 368001

5) Element Pack Lifting device

Special sling 1 set HSTD/200-1

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Rotor locking piece 2 sets 200001

6) Seal Setting

Radial Seal Setting Bars 1 set HSTD186003-2

Axial Seal Setting Bars 1 set HSTD186004-2

Needle Gauges 1 off HSTD/206-2

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Appendix I RECOMMENDED PROCEDURE FOR SITE TESTING OF AIR PREHEATERS Variations to ASME PTC 4.3

1. Scope

The purpose of this instruction is to outline procedures for conducting site tests on APH to determine the following operating characteristics:

• Air to Gas side leakage

• Gas and air pressure drops

• Thermal performance

Guarantees are not specifically dealt within this document and must be agreed upon between all parties prior to the test.

2. Preparation for Testing

2 . 1 Selection of Personnel

To ensure reliable results, all personnel participating in the test shall be fully qualified to perform their particular function. Parties to the test may designate a person to direct the test and to serve as arbiter in the event of disputes as to the accuracy of observations, conditions or methods of operation.

Responsibility should be appointed to a single person for all performance and operating conditions that affect the test

2 . 2 Heater Inspection & Operation

It is recommended that the air preheater be inspected prior to the test to note the condition of all parts that can affect the performance. In particular, the condition and cleanliness of elements should be examined and the air preheater placed in proper operating condition.

Any external air bypasses or recirculating dampers must be checked for sealing effectiveness, and any expansion joints between the test points should be checked for integrity.

All heating elements should be 'commercially clean' (normal operating cleanliness) before starting the test. All 'on-load' sootblowing must be carried out prior to commencement of the test, and no cleaning shall be permitted during the test.

2 . 3 Preferred Sampling and Measurement Technique for Leakage Measurement

The preferred sampling technique for airheater tests to measure airheater leakage is to complete simultaneous traverses across the gas inlet and outlet ducts to withdraw individual gas samples for analysis. Using this method, a separate O2 measurement will be taken of each of the grid of sampling points being measured across each duct. The number of sampling points included in this grid will be in keeping with the requirements of ASME PTC 4.3.

At the same time a pitot traverse of the gas outlet ducts will be performed to determine whether there is any severe velocity stratification in the duct at the measuring plane. If significant velocity stratification

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exists across the duct, these velocity measurements must be used to calculate a volume weighted mean O2 level for the sampling plane as a whole, rather than using a simple arithmetical average.

The above sampling traverse method is referred to in ASME PTC 4.3 as a necessary preparation for setting up a fixed sampling grid as used thereafter in that Code.

The advantages of the fixed sampling grid in ASME PTC 4.3 is perceived as the increased speed of sampling of the bulk flue gas during a performance test.

However, it is Howden's experience that the sampling traverse method described above is the preferred method for completing the full performance test for the following reasons:

It avoids the need for long lengths of sample tube and a complicated array of connections. In practice, such tubing has been found to be prone to both leakage and blockage of individual tubes during the test period. Moreover, using such bulk sampling techniques, it is very difficult when such problems occur.

Using the individual, sampling traverse technique, such extended lengths of tubing are kept to a minimum and the O2 analysers can be positioned close to the sampling point.

Further, using the sampling traverse technique, by studying the nature of the variations in O2 across both sampling planes relative to the geometry of the heater, it is possible to determine whether or not individual samples or groups of samples of O2 measurements look believable.

For example, highly stratified O2 levels measured at the outlet of the airheater with peak O2 levels occurring well away from the airheater sector plates - perhaps on the other side of the duct - cannot be associated with airheater leakage. Instead, such peaks may be associated with either air ingress into the sampling points or some other form of air ingress into the duct such as a leaking expansion joint.

If such unusual variations are discovered, rather than disregard a complete sampling plane or test, the individual parties involved in the test can agree as to how to compensate for such errors. A suggested solution would be to discount the dubious sample or samples and to replace their measured values with O2 readings measured at adjacent sampling points.

When completing such sample traverse procedures are used to measure the leakage across the air heater, the tests must be repeated until two successive sets of test measurements produce measured leakage levels that agree with each other within an acceptable level of tolerance. Moreover, when completing such repeat tests, the O2 meteres used at the gas inlet and outlet, respectively, should be switched to help eliminate or assees instrumentation error. If successive tests do not agree to such acceptable tolerance levels, the tests must be repeated until such agreement occurs or until a statistical average can be made of all the sets of tests.

Also, a pitot traverse of the PA inlet and SA inlet shall be done to determine the flows entering the heater at the design load. These shall be used later to weight the air inlet temperatures.

The unit will be considered unfit for testing if it is found that the recorded O2 gas inlet level does not fall within the agreed deviation.

3. Test Conditions

3 . 1 General Test Conditions

It is important that air and gas flow through the air preheater remains essentially constant, and the O2 levels are steady throughout the test. The steam generator output shall be set as close as possible to the design value and shall be held stable for at least 30 minutes prior to the start of each test. Testing shall commence only when the parties to the test certify that the unit is operating to their satisfaction and is,

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therefore, ready for test. Where a test is being carried out as part of a guarantee agreement Howden reserve the right to be given a reasonable period to correct and re-test the equipment should a shortfall in performance be found in any of the guarantee parameters.

3 . 2 Duration

Test runs shall be of at least two hours duration but sufficiently long to permit the taking of at least two complete sets of consistent readings for a single air preheater.

3 . 3 Gas Side Effectiveness

If the test results exceed the previously agreed upon deviation in gas side effectiveness between runs, a third run shall be required. The test effectiveness will be the average of the two runs that fall within the permissible deviation.

3 . 4 Rejection of Run or Agreed Adjustment of Test Measurements

Should inconsistencies in the observed data be detected during a run or during the computations that would cause obviously untrue results, the run may be rejected completely. A run that has been rejected shall be repeated to attain the objectives of the test.

As an alternative to rejecting the run altogether, in the case of suspiciously high O2 measurements, a small group of such measurements may be disregarded by mutual agreement or preferably replaced by the O2 readings of adjacent measured sampling points. (See Section 2.3)

3 . 5 Records & Test Reports

All observations, measurements and instrument readings necessary for the objective of the test shall be recorded as observed. Corrections and corrected values shall be entered separately in the test record.

4. Test Measurements

The following measurements are required in order to determine the performance of a trisector air preheater:

Temperature of secondary air entering heater

Ta1s

Temperature of primary air entering heater

Ta1p

Temperature of secondary air leaving heater

Ta2s

Temperature of primary air leaving heater

Ta2p

Gas inlet temperature Tg1

Secondary air side inlet & outlet static pressure

Psa1s，Psa2s

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Primary air side inlet & outlet static pressure

Psa1p，Psa2p

Gas side inlet & outlet static pressure Psg1，Psg2

Secondary air outlet flow (measured) Ma2s

Gas inlet mass flow (measured) Mg1

Gas outlet mass flow (calculated) Mg2

% O2 & CO content of dry gas entering & leaving heater

O2in, O2out

COin, COout

In addition, a sample of the fuel and flue gas should be sent for laboratory analysis to determine the fuel and flue gas constituents. It is vital for the calculation of the leakage that the moisture content and density of the flue gas is known.

To allow complete analysis of the test data, printouts of control panel recordings at regular intervals should be supplied by the Power Station detailing the following:

• Boiler load

• All recorded temperatures, mass flows and pressures

• Fan amps

• Any other factors which may affect heater performance i.e. Control Damper Positions

5. Test Apparatus

The apparatus required for the test is as follows:

5 . 1 Thermocouples

Calibrated NiCr: NiAl thermocouples (Type K) shall be used with a calibrated Digital Thermometer or with a Digital Indicator. The thermocouples shall comply with the following specifications:

Operating Temperature Range : 0 - 1000ºC

Accuracy : ± 1.5ºC

5 . 2 Manometers

Calibrated Electronic Micro-manometers or U-Tube/Inclined manometers filled with water or a light liquid of known specific gravity shall be used.

5 . 3 Gas Analysers

Gas analysers shall be used to determine the percentage concentration of oxygen in the gas streams.

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While these can be of any type:

Paramagnetic Attraction

Catalytic Combustion

Electro-chemical Membrane Diffusion

Zirconia Cell Diffusion

The calibration of this equipment shall be checked on site prior to and after each test to ensure consistency of readings and free from any significant deviations. For the O2 analysers, a 100% N2 gas bottle is used for the zero calibration setting and a 95% N2 + 5% O2 gas mix is used for the span calibration setting.

6. Test Procedure

6 . 1 Location of Test Points

Sampling points in the gas inlet and outlet ducts should be located as close to the air preheater as practical, and as consistent as possible with good velocity measurement practice. Due to the probable stratification at the gas outlet caused by the rotation of the air preheater the traverse section should be located as far from the rotor as possible but prior to any expansion joints which may allow air ingress to influence the measurements.

6 . 2 Temperatures

Temperature shall be measured by installing fixed grids of probes with thermocouples attached and utilising data loggers to scan all the thermocouples giving information of time and spatial variations.

Locations:

SA Inlet : FD fan discharge – after the PA take off + sootblower seal air take off

SA Outlet : at the windbox inlet

PA Inlet : PA fan discharge – after the bypass takeoff

SA Outlet : before any flow additions

Gas Inlet : After grit collector at economiser exit – on horizontal section

Gas Outlet : After grit collector and bend before precipitator

Each thermocouple will have its unique correction factor applied to its individual readings as per its calibration certificate.

6.3 Static Pressure

Static pressures shall be measured by connecting suitably sized manometers to the pressure tappings on the faces of the preheater transition ducts. Experience has shown that side-wall static tappings give sufficiently accurate values of average static pressures compared to those obtained with traverses.

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Reading of oxygen content in gas

Measurement of oxygen content in gas is purpose for calculating of air leakage. Leakage and flow shall be measured at same time. For boiler with stable operation on load, oxygen content at boiler discharge/ APH inlet change little with time passing by, so that oxygen content can be measured with single sampling probe moving in duct all round. See figure 1. However, also content can be measured by sampling gas from multi-probes arranged in whole duct or fixed in the duct. Average value from these probes is equal to measurement by tranverse movement. It is very important that each probe must sample same volume of gas. So length of sampling tube shall be same.

Proper steps shall be taken to prevent air ingress in gas analysing apparatus and sampling lines.

Apparatus should be kept clean, and human errors minimised by employing careful operators who are given adequate information on common sources of error. Gas and air content shall be measured by pitot traverse movement or thermal balance. If inlet air flow rate determined, air discharge shall be checked before APH and after FD fan. If leakage through bypass or recirculating dampers is significant, it must be taken into account seriously and any possible influence of hot and cold crossover ducts will have to be considered.

6 . 4 Flue Gas Analysis

Flue gas CO & O2 measurements are required to calculate the gas flows.

The preferred method of sample withdrawal and analysis shall be the full sample traverse method as described in Section 2.3.

Proper steps shall be taken to prevent air ingress in gas analysing apparatus and sampling lines. Apparatus should be kept clean, and human errors minimised by employing careful operators who are given adequate information on common sources of error.

Analyser drift corrections will be applied to each O2 and CO measurement on a linear basis over the period of the sampling.

a) Flue Gas & Air Flow：

If possible the inlet gas flow rate to the heater will be determined by completing a pitot traverse across the gas inlet plane.

In heater installations where the gas inlet flow cannot be measured it may be estimated as follows.

Measure the CO and O2 in the relevant ducts and using combustion and gas recirculation calculations to determine the remaining flue gas constituents and the weight of flue gas per unit weight of fuel burned.

The weight fuel burned can be estimated from the steam generator output and the assumed overall system efficiency.

The above two factors can be combiined to allow the overall boiler gas flow rate to be calculated.

However, it is emphasised that such an estimated is a much less preferred option as due both to inaccuracies in the assumed cycle efficiencies and maldistribution of the gas flow rate between heaters operating in parallel.

Howden


Page 62 of 62

b) SECONDARY AIR (SA) FLOW：

If possible the SA outlet flow will be measured by pitot traverse across the air outlet duct.

As there is a crossover duct before these measuring points, the FD fan flows (taken from axial flow fan installed devices) will be compared for both heaters to determine whether the balance of flow over each heater is equal.

Viewing from experience, traverse test was carried out successfully in Gaobeidian Power Plant in 1998 by Howden Sircocco firstly with 5 meters and calibrated pitot pipe.

c) PRIMARY AIR (PA) FLOW：

If the above two flow rates can be measured as suggested above, the PA outlet flow will be calculated by an energy balance across the airheater using the Gas Inlet flow and SA Outlet flow along with all the measured temperatures and calculated specific heats.

Alternatively, where both the SA and PA outlet flows can be measured by pitot traverse but the gas inlet traverse is difficult, the gas inlet flow may be calculated by heat balance.

The PA fan amps will also be compared to check the balance of PA through each heater. A crosscheck can also be made with the mill inlet flow and temperatures.

If leakage through bypass or recirculating dampers is significant, it must be taken into account and any possible influence of hot and cold crossover ducts will have to be considered.

6 . 5 Velocity Weighting of Gas Analysis Measurements

If the preliminary check run indicates stratification, it is recommended that the measurements at individual locations in the duct cross section be weighted in proportion to the gas flow at the corresponding locations, and an average of the weighted values be used as representing the measurement at the cross section. If this is necessary, velocity pressures should be measured using a pitot-tube at the same positions and time as the gas sampling/temperature measurements. If severe flow stratification is experienced, velocity weighting should definitely be used.

7. Calculations & Formulae

For clarification of the symbols in the following equations, please refer to Appendix A: Definitions & Nomenclature.

7 . 1 Leakage

Leakage percentage at gas inlet flow will be calculated by the following formula.

％

Where:

( )L

O out O in FactorO out

=− ×−

2 2

221

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996011.128701.1×⎟⎟⎠

⎞⎜⎜⎝

⎛×−= kFactor

gρ

This factor converts from a dry basis to a wet basis, and the density & moisture content of the flue gas will be calculated from a combustion analysis

In practice, it has been found that the above equation and the much more complicated ASME equations produce similar results. Hence, if there is a noticeable difference between the two analysis methods, this would suggest an error in calculation.

7 . 2 Undiluted Gas Exit Temperature

( )Tg L Tg Ta TgNL2 2 1 2= × − +

where L is the leakage and expressed by algorism.

7 . 3 Air Preheater Energy Balance

In a bisector air preheater, it is often convenient to measure the air inlet flow into the heater from test points of the FD fan outlet. It is then possible to calculate the gas inlet mass flow from the heat balance equation:

( ) ( ) 1

1 LCpTCpTCpTaMgM

aagg

aa

××Δ+×Δ×Δ×

=&

&

In trisector heaters, however, there are two separate flows of air through the rotor. The leakage measured by the oxygen concentrations gives the total air to gas leakage from both the primary and secondary flows. It is not possible to determine how much of this total comes from each air stream, or how much air passes from the high pressure primary to the lower pressure secondary air side.

With these unknowns, the measurement of the two air inlet flows and manipulation of the heat balance equation will not work. For an accurate analysis of a tri-sector heater therefore, air outlet mass flow shall be measured and calculate gas mass by the following formula:

[ ] [ ]SecondaryCpTaMimaryCpTaMCpTgM aaaagg ×Δ×+×Δ×=×Δ× 221 Pr &&&

Note that, when performing the energy balance, we assume that the radiation losses are insignificant.

7 . 4 Composite Air Temperatures (for thermal analysis)

Air inlet temperature： ( ) ( )( ) ( )pssspp MaMaMaTaMaTaTa 1111111 +⋅+⋅=

Air outlet temperature： ( ) ( )( ) ( )pssspp MaMaMaTaMaTaTa 2222222 +⋅+⋅=

7 . 5 Temperature Differentials

Gas side： NLg TgTgT 21 −=Δ

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Composite air side： 12 TaTaTa −=Δ

7 . 6 Definition of Thermal Effectiveness

Gas side：ηgTg TgTg Ta

NL = 1 2

1 1100

−−

× ％

7 . 7 Pressure Drops

Gas side pressure drop： Psg Psg Pg1 2− = Δ

Secondary air pressure drop： asss PPsaPsa Δ=− 21

Primary air pressure drop： appp PPsaPsa Δ=− 21

7 . 8 Pressure Differentials

Mean Hot End Pressure Differential： ( ) ( )12s2p PsgPsaPsaHEPD = −+ 2

Mean Cold End Pressure Differential： ( ) ( )211 2 PsgPsaPsaCEPD = sp −+

7 . 9 Mean Specific Heats

( ) ( ) ( ) ( )

21

21

21

21 ,TaTa

CpTaCpTaCpTgTg

CpTgCpTgCp a

NL

NLg −

×−×=

−×−×

=

Cp is the specific heat of the gas or air at the associated temperatures.

8. Comparison of Test Measurements to Design Conditions

8 . 1 Thermal Operating Margin

The Gas Exit Temperature referral will be as per the ASME equations and Howden correction curve, but using a composite heater basis and analysing it as a bi-sector. This means we need to use composite air inlet temperatures.

The air outlet temperatures can be weighted using the SA and PA flow rates. The air inlet temperatures can be weighted using the flows measured in the pre-test. Alternatively, if this proves to give spurious results, the air outlet flows can be used to give a reasonably accurate composite value.

8 . 2 Leakage Analysis

The measured leakage must be adjusted for both flow and driving pressure difference from the quoted “design” condition before comparisons are made with the design leakage level.

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Measured leakage will be referred using the ASME equation 7.13.1, and a composite air inlet temperature. This adjustment is made as follows;

L L MgMg

CEPDCEPD

TaTaR T

T

D

D

T

T

D= × ×

⎛⎝⎜

⎞⎠⎟ ×

++

⎛⎝⎜

⎞⎠⎟1

1

1

1

2731527315

.

.

where LR is the leakage referred to design flow and cold end pressure differential.

8 . 3 Pressure Drop Analysis

The pressure drop referral to design conditions will be completed according to the following Howden standard equation:

Δ ΔP = PR T × ×⎛

⎝⎜

⎞

⎠⎟ ×

⎛

⎝⎜

⎞

⎠⎟

⎡

⎣

⎢⎢

⎤

⎦

⎥⎥

+ρρ

μμ

β βT

D

T

D

D

T

MM

&

&

2

where: the subscripts T and D refer to Test and Design conditions, respectively

μ is the viscosity of the flow at the mean flow temperature

ρ is the density of the flow at the mean flow temperature

β is the friction factor coefficient for the heating elements used

For typical heat transfer elements as used by Howden, -0.32 ≈β and the above equation reduces to the following

Note that the ASME equation for correcting pressure drops does not take account that the heater operates in the transition zone between turbulent and laminar flow.

Unlike the ASME code, which simplistically assumes fully turbulent conditions and uses a simple square law relationship for correction, Howden’s equation above more accurately accounts for this by using the friction factor coefficient of the installed elements.

8 . 4 Schedule of Items to Agree Prior to Testing

ITEM Howden Standard Value

Thermocouple tolerance (for NiCr:NiAl) ± 1.5℃

Temperature measurement instrument tolerance ± 1.0℃

Oxygen analyser instrument tolerance ± 0.1% O2

⎥⎥⎦

⎤

⎢⎢⎣

⎡⎟⎟⎠

⎞⎜⎜⎝

⎛×⎟⎟

⎠

⎞⎜⎜⎝

⎛××ΔΔ

− 68.132.0

TR P = PT

D

D

T

D

T

MM&

&

μμ

ρρ

Howden


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Pressure measurement instrument tolerance ± 4%

Permissible deviation in gas side thermal effectiveness between test runs

± 5%

Permissible deviation in inlet oxygen level from design conditions and between test runs ± 1% O2

O2 analyser Zero calibration gas 0.0% O2, 100.0% N2

O2 analyser Span calibration gas 5.0% O2, 95.0% N2

8 . 5 Overall Error Analysis

The present version of ASME PTC 4.3 makes detailed mention of an Error Analysis for the calculation of the overall measurement accuracy in the calculation of any of the three main heater performance parameters - leakage, thermal performance and pressure drop.

For any factor calculated from a range of separate measurements, it should be apparent that any derived measurement will have a measurement tolerance subject to a number of different factors including:

The individual instrument accuracy (as listed above)

Sampling accuracy - i.e. how accurately do a number of individual sample points measured across a plane represent the mean gas conditions across that plane.

The calculation technique depends on the subtraction of two O2 values, which can be relatively close to one another.

While an error analysis will not be presented herein, it is worth highlighting that an independent error analysis completed almost 20 years ago by the CEGB came to the conclusion that airheater leakage can be measured no more accurately than within around ± 20% by using differential O2 or CO2 techniques. Hence, it is possible to measure an actual leakage level of 7.5% as lying anywhere between 6.0% - 9.0%, depending on how the measurement and sampling errors add up.

This inevitable scatter in measurement errors is one reason why Howden's own measurements over a wide range of heaters of different have indeed reflected a similar range of scatter.

When considering high measured leakage levels, therefore, it is important to distinguish between differences due to measurement error and those due to inadequately adjusted seal settings.

Given the levels of error in leakage measurement of up to ±20% stated above, a design level of 7.5% leakage may be measured at up to 9.0% leakage without being proved to be inappropriately high. Correspondingly, however, providing the correct measurement practices are adopted, measurements of leakage as high as 11% on the same heater will patently demonstrate a heater that is failing to meet its guaranteed leakage levels. Under such circumstances, these heaters have invariably been identified to have been set up outside the seal setting tolerances.

Howden


Page 67 of 67

Annex A: Definitions & Nomenclature

Air leakage Amount of air passing from the air side to the gas side, assumed to pass directly from the air inlet to the gas outlet.

Undiluted exit gas temperature

The temperature at which the gas would have left the heater if there were no leakage.

Exit gas temperature The measured gas temperature.

Gas side effectiveness Ratio of the gas temperature drop, to the difference between the air inlet and gas inlet temperatures.

Symbols Used Description Units

M Mass flow rate kg/s

T Temperature ℃

L Leakage (% of gas inlet mass flow) %

Ps Static pressure kPa

Pv Velocity pressure kPa

Bp Barometric pressure kPa

P　 Pressure difference kPa

A Duct area m²

η Effectiveness %

Cp Specific heat J/kg℃

TM Thermal margin %

k % moisture in flue gas entering heater %

ρg Density of flue gas at NTP kg/m³

ρa Air temperature at NPT kg/m³

ρw Density of water vapour at NTP kg/m³

Subscript Definition

a air side parameter

g gas side parameter

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1 entering condition

2 leaving condition

T test condition

D design condition

NL no leakage (undiluted)

s Secondary air flow

p Primary air flow

Howden


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Annex B：Items to be checked before testing

Item Description Remark

1 calibrate the gas analyzer before and after test

2 check the tightness of system

3 check the tightenss between the points of manhole, damper and expansion joint.

4 check the tightenss of economizer and ash hooper.

5 check the tightenss of sootblower wall box

6 Check if any sealing air introduced into gas exit ductwork originated from hopper and manage to eliminate its influence if any.

7 Check if any suction pressure system led into gas exit ductwork and manage to eliminate its influence if any.

8 If isolating value fitted between air and gas fire fighting water pipe?

9 Is there water washing pipe connected between air and gas side?

10 Watch if the gas analyzer readings abnormally, if it is, find out the reason.

11 check static pressure not to be fouled.

12 The measuring section shall be as close to APH as possible, or else pressure loss shall be considered.

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Annex II APH performance analysis and operating datas

I. APH performance analyse items

Comparison between the actual thermal performance and design value

Comparison between the actual air leakage and design value

Comparison between actual air, gas side pressure drop and design value.

For retrofit project, compare the value before and after retrofit.

II. Factors affecting APH performance

Air and gas flow which passing the APH

Air and gas inlet temperature of APH

Air leakage of APH (sealing condition)

Air recirculation and air bypass system which control cold end temperature

Heating element corrosion, worn and foul

Boiler and other system leakage

Purified system

Burning system

Operating mode

III. Datas for analyse aph performance

No. description unit data

CY

HY

OY

NY

SY

WY

AshY

%

1 Fuel element *** analysis(received base)

high calorific power

kJ/kg

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Net calorific power

2 load MW

3 Fuel consumption*** kg/s

4 Furnace outlet excessive aircoefficient ***

5 atmospheric pressure kPa

6 dry bulb tempreature ℃

7 wet bulb temperature ℃

8 ambinent temperature ℃

9 atmospheric humidity %

PA 10 APH air inlet

temperature *** SA

PA 11 APH air outlet

temperature *** SA

℃

12 APH gas inlet temperature *** ℃

13 APH gas outlet temperature *** ℃

14 APH gas inlet static pressure *** kPa

15 APH gas inlet outlet pressure *** kPa

PA kPa 16 APH air inlet static

pressure *** SA kPa

PA kPa 17 APH air outlet static

pressure *** SA kPa

18 Oxygen at gas inlet of APH *** %

19 Oxygen at gas outlet of APH *** %

20 the average gas specific heat J/kg.K

21 the average air specific heat J/kg.K

22 mass flow at APH gas inlet kg/s

23 Mill inlet temperature of mixed PA *** ℃

Howden


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24 Inlet total air flow from PA to mill *** kg/s

25 the propotion of PA and SA air flow

26 ID fan current * A

27 ID fan damper open angle %

28 PA fan current A

29 PA fan damper open angle %

30 FD fan current A

31 FD fan damper open angle %

32 steam pressure at the rear of sootblower when sootblowing

bar.g

33 steam temperature at the inlet of sootblower flange

℃

34 rotor drive motor current A

PA and gas side sector plate

mm

SA and gas side sector plate mm

35

measurement of seal clearance,

Needle gauage measurement between

between the sector plate of PA and SA side mm

deflection mm

36 deflection of the center of rotor driving shaft

(angle) degree

Note: the item *** marked are datas we must obtained.

Howden


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Annex III APH faults finding and rectifications

From the experience of both overseas and domestic APH, air leakage, corrosion, foul, current fluctuation and emergency shut down are the main problems affecting heater operation which will impact directly the combustion of boiler as well as the power consumption of ID and FD fan, at the same time, causing fan stall and running without full load etc. therefore, the operating of APH related closely to the safe, economic and stalbe of the unit.

The follow are the main faults and their rectifications.

Item Fault Main reason Recommended rectification

test points location or test method improper

test instrument accuracy exceeding tolerance

test condition unstable

Follow ASME PTC 4.3 and relative Howden standard closely

operating paramet differ from design parameter too much

adjust operating parameter to the design condition then subject to air leakage test

APH sealing clearance is too big Check, recalculate as per design requirement, readjust and set the seals which exceeded the tolerance.

APH seal structure part worn badly Check and remedy if necessary.

Pressure difference between gas side and air side is too high caused by the serious fouling of heating elements.

Before test, strengthen the sootblowing of heating element. When necessary, shut down the unit for HP water flushing to ensure the cleaniess.

APH transition duct, rotor casing and sootlbower (including wall box etc) are seriously worn and leaked.

Check the possible leaking points carefully and mend on time

1

High leakage rate

expansion joint, damper and system duct etc around test points leaking

Check the possible leaking points carefully and mend on time

2 heating element low t t

adopts the bad quality coal of high sulphur content control the sulphur content in the fuel

Howden


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The cold combined temperature lower than the recommended lowest value.

Remember to start up air heater at the low load condition and winter time to ensure the combined cold end temperature always higher than the lowest recommended value.

sootlbowing with water Increase the degree of superheat of steam, improve steam drain water and control system.

air heater leaking ensure air heater in normal service

Heating element corrugate and material selection are improper.

Subject heating elements to thermal performance calculation as per real coal adopted. Optimize the design of heating elements.

Adopt bad quality coal. Try to avoid using bad quality coal.

Cold end combined temperature is too low

Remember to start up air heater at the low load condition and winter time to ensure the combined cold end temperature always higher than the lowest recommended value.

sootlbowing with water increase the degree of superheat of steam, improve steam drain water and control system.

air heater leaking ensure air heater in normal service

the quality of steam can not meet with the requirments

improve steam quality to meet with design requirement

sootblow frequency and volume insufficient

Adjust sootblowing pressure and frequency. When necessary, add HP water (off line or on line) flushing device.

3

APH resistance is high and fouled seriously

heating element corrugate and material selection are improper.

Adjust suitably the sootblow pressure and frequency, when necessary, provide HP water washing device (on line and off line). Subject heating elements to thermal performance calculation as per real coal adopted. Optimize the design of heating elements.

Howden


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Top structure and end pillar etc were not insulated as per requirement which led to APH uneven thermal expansion.

Top structure insulation was leaked into water which led to deformation.

Closely follow the design drawing to Insulate APH

temperature rose too quick when start up and shut down APH

Watch closely driving motor current when start up and shut down APH, reduce temperature rising speed when APH was found abnormal.

Seals were jammed. Check the worn of seals, adjust the worn part suitably.

The inlet gas temperature is higher than the design value.

Control the inlet gas temperature of APH, recalculate seal clearance as per real inlet gas temperature.

Top and bottom rotor hub seal packing binding and compressing.

Check, adjust and replace the packing of rotor hub.

Foreign materials enter into APH which stop rotor from rotation.

Shut down unit for checking, deliminate the foreign material.

APH transition duct connecting flange adopts metallic expansion joint, which led to APH rotor or casing deviation.

APH transition duct connecting flange adopts non-metallic expansion joint to ensure it will expand freely.

4 driving motor current fluctuates

Factors preventing APH thermal expansion exist.

Check the factors preventing APH thermal expansion, if any, deliminated.

Howden


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Top structure, end piller etc were not insulated as per required, or during the operation, insulation was leaked into water which led to uneven thermal expansion,

temperature rose too quich when start up/shut down APH

seals were jammed.

the inlet gas temperature is higher than the design value.

top and bottom rotor hub seal packing binding and compressing.

Foreign materials enter into APH which stop rotor from rotation.

APH transition duct connecting flange adopts metallic expansion joint, which led to APH rotor or casing deviation.

Shut down program improper which led to APH expand abnormally and further caused jam.

APH rotor top and bottom bearing fault

Due to other equipment fault, APH was not cooled sufficiently, heat exchange unevenly.

5 Emergency

shutdown

Due to the fault of other equipment.

Close APH gas inlet damper immediately

Open APH top gas duct manhole.

Ensure ID fan damper open.

Ensure APH rotating all the time, and cooled evenly and quickly.

Howden


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the change of coal

the increase of APH inlet gas flow

the variation of APH X-ration (heat capacity ratio of gas and air)

gas inlet temperature high

Air inlet temperature high

heating element foul and corrosion seriously

sootblow incomplete

furnace air leakage

the worn of rotor sector plate and outer circumferential seal

the selection of heating element improper

air and gas flow enter into APH unevenly

6

APH gas leaving temperature high

combustion system

improve sootblow, ensure the cleaniess of heating element to increase utilization

replace heating element

adjust suitabley and replace outer circumferential seal

Improve the design of gas duct to improve air and gas flow for the higher heat transmission rate.

improve combustion system

Change the coal type and operating parameters.

Howden


Page 78 of 78

Annex IV Howden VN APH spare parts list

I. Spare parts for emergency use

Item Description Size Unit Quantity Remark

1 Drive unit GMF5D/TSMWD17 Set 1

2 Top steady bearing SKF C3172M/C4 off 1

3 Bottom thrust bearing SKF 29480EM Off 1

4 Main drive motor GAMAK电机，GM160L Unit 1

5 Inverter ACS800 Set 1

6 Bearing lub oil Mobil SHC 639 Lit

7 Lub oil for drive uint SHELL OMALA 320RL lit

II. Spare parts for maintenance use

Item Description Size Unit Quantity* Remark

1 hot end radial seal strip, cover plate and stiffener Set 1

2 cold end radial seal strip, cover plate and stiffener Set 1

3 axial seal strip, cover plate and stiffener Set 1

4 bottom outer circumferential seal Set 1

5 Top outer circumferential seal Set 1

6 bottom inner circumferential seal Set 1

7 Top inner circumferential seal Set 1

8 bottom hub seal strips Set 1

9 top hub seal strips Set 1

10 hub seal packing Set 2

11 Main drive motor GAMAK，GM160L unit 1

Howden


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12 Inverter ACS800 set 1

13 Drive unit, primary reduction gear Set 1

14 Drive unit, primary reduction worm, pinion Set 1

15 Drive unit, secondary reduction worm, pinion Set 1

16 bearing for drive unit primary gear box Set 1

17 Bearing for drive unit primary worm, pinion reduction gear Set 1

18 Bearing for drive unit secondary worm, pinion reduction gear

Set 1

19 oil seal for drive unit secondary worm, pinion reduction gear

Set 1

20 top bearing oil level meter Set 1

21 bottom bearing oil level meter Set 1

22 fire fighting probe (thermal couple) K scale Set 1 For each

boiler

23 rotor stall alarm probe Off 2 For each boiler

24 Top bearing oil temperature probe Pt100 Set 1 For each

boiler

25 bottom bearing oil temperature probe Pt100 Set 1 For each

boiler

26 drive unit primary worm gear reduction box torque arm Set 1

27 drive unit secondary worm gear reduction box torque arm

Set 1

28 Sootblower seal washer Set 1

29 Sootblower motor Unit 1

30 Sootblower nozzle Off 2

31 Fire fighting nozzel S190、S247 Off 2

Howden


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32 Hot end heating element HS7 1200X0.5 Set 1

33 Intermediate heating element HS7 1000X0.5 Set 1

34 Cold end element HS7 300X0.8 Set 1

35 Top steady bearing SKF C3172M/C4 Off 1

36 Bottom thrust bearing SKF 29480EM Off 1

*Note：Unless other statements, quantity in the column is only for one APH.

APH down

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