Esp

Station: NTPC- Simhadri

Station: NTPC- SimhadriBHEL Ref No.PS-DC-186-500-0043

NTPC Ref no SIM/1/TS/1/ 43Sheet 1 of 19

Plant area: BOILER

PROCEDURE FOR COMMISSIONING OF ESP

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2.0

3.0

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5.0

6.0

7.0

8.0

9.0

LIST OF CONTENTS

PLANT DETAILS

OBJECTIVE

PROPOSAL

SERVICES REQUIRED

SAFETY PERECAUTIONS

EMERGENCY PROCEDURE

STATE OF THE PLANT

METHOD

COMPLETION CRITERIA



Plant area: BOILER


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1.11.2

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1.2.4

PLANT DETAILS

Four numbers of ESP for each 500MW is provided for precipitating of all dust emanating from the boiler flue gas. Two ESPs are located in the left and two ESPs are located in the right of the boiler flue gas path before ID fans. Each ESP is further divided into eight fields per flue gas path. Ref : O & M Manual for ESP schematic diagram.

Parts of Precipitator (Ref. O & M MANUAL)

Mechanical system:

Precipitator Casing made of pre-fabricated panels. The casing is provided with inspection doors with gas tight seal construction. The roof carries the precipitation internals, insulation housing transformer etc. The Casing support allows for free thermal expansion of the casing during operation.

Hoppers: The hoppers are adequately sized to hold the ash. Baffles are provided in each hopper to avoid gas leakage. Thermostatically controlled heating elements are arranged at the bottom of hopper portion to ensure free flow of ash.

Gas distribution system: Even distribution of gas over the entire cross section of ESP is achieved by guide vanes, splitters and screens provided in the inlet funnel of the ESP.

Collecting electrode system: The collecting plates are made of 1.5mm cold rolled mild steel plate and shaped in one piece by roll forming. The collecting electrode has unique profile designed to give rigidity and to contain the dust in a quiescent zone free from re-entrainment. The 400 mm collecting plates are provided with hooks to their top edge for suspension. The hooks engage in the slots of the supporting angles. All the collecting plates in a row are held in position by a shock bar at the bottom. The shock bars are spaced by guides.STATUS

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Plant area: BOILER


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1.2.5

1.2.6

1.2.7

1.3

1.3.1

Emitting electrode: The most essential port of precipitator is supported by four insulators. The frames are welded to form a rigid box like structure for holding the emitting electrodes are located centrally between collecting electrodes curtains. The emiting electrodes are hept taut between the frames.

Rapping system: Rapping systems are provided for collecting and emitting electrodes. These rappers are driven by geared motors. The rapping system employs tumbling hammers which are mounted on a horizontal shaft. As the shaft rotates slowly the hammers tumble on top the shock bar/shock beam which tr5ansmits the blow to the electrodes. The rapping shaft of emitting electrode of electrically isolated from the geared motor drive by a shaft insulator. The space around the shaft insulator is continuously heated to avoid condensation.

Insulator housing : The support insulators, supporting the emitting electrode system are housed in insulator housings. The HV dc connection is taken through a bushing insulator mounted on the insulator mounted on the insulator housing wall.

Each support insulator is provided with one electrical heating element controlled by thermostat. Figure 16.

ELECTRICAL SYSTEM

High voltage transformer rectifier (HVR) with electronic controller (EC) : The transformer rectifier supplies the power for particulate charging and collection. The basic function of EC is to feed the precipitator with maximum power input under constant current regulation. Whenever there is a flash between emitting and collecting electrodes, the EC will sense the flash over and quickly react by bringing the input voltage to zero an blocking it for a specific period. STATUS

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Plant area: BOILER


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1.3.2

1.3.3

1.4

1.5After the ionized gases are cleared and the dielectric strength restored, the controller will quickly restore the power to a preset value and raise it to the original non sparking level. The EC ensures adequate power input to the precipitator while reckoning the electrical disturbances within the precipitator. Regulated ac power from EC is fed to the primary of the transformer precipitator, which is stepped up and rectified to give a full wave power output. The transformer-rectifier is mounted on roof of the precipitator which the EC is located in an air conditioned control room.Auxiliary control panel(ACP)

This is an LTMCC of modular construction with individual modules for supplying power to the following equipment.

-Hopper heaters for each field

-Support insulator heaters

-Shaft insulator heaters

-Collecting electrode rapping for each field.

-emitting electrode rapping motor for each field.

-Opaque monitor

Safety interlock: A interlock system is incorporated to prevent accidental contact with live parts of the precipitator and to enable energisation only when the EP is boxed up.

Disconnecting switch: each field is provided with one disconnecting switch for isolation of emitting system from the associated transformer. In the ON position the emitting system is connected to transformer and in OFF position the emitting system is grounded. Figure 18.

The specifications of ESP: Refer O & M Format No. 11

Sheets 01 to 06.

Refer to O & M Manual for schematic diagram of ESP.

STATUS

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Plant area: BOILER


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4.2

4.3

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4.6

4.7

4.8

OBJECTIVE : To commission ESP and make it available for Unit operation.

PROPOSAL :

ESP will be commissioned through the following proposalsCompletion of Mechanical & Electrical checks.

Charging field and Air load test.

SERVICE REQUIRED:

Adequate lightening to be provided inside ESP for internal checks.

Availability of L.T. Power Supply

Availability of sealing arrangement at ESP Hopper bottom.

Availability of adequate communication facility at test area.

Availability of 3 Nos of hand torch (Battery operated)

Availability of manpower to check various parts of ESPs. (Both Mechanical & Electrical)

Availability of oil filtering machine

Availability of 2.5/5KV motorized & 500V hand megger / Multimetor / 3 phase variac (15A)

STATUS

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NTPC BHEL



Plant area: BOILER


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5.0

5.1

5.2

5.3

5.4

5.5

5.6

5.7

6.0

6.1

6.2

6.3

SAFETY PRECAUTIONS:Ensure the availability of first aid kit in the ESP room

Ensure the availability of safety helmets for concerned personnel

Always ensure before entering any field the connected HV/LT supply is isolated proper earthing of emitting electrode is done.

Never attempt to carry out Mechanical checking/Electrical commissioning simultaneously

Ensure line clearance from the concerned boiler staff before entering ESP.

The agencies working in ESP area are informed about ESP charging activity.

ESP door interlock system is fully available and the master key should be with designated person in the test team.

EMERGENCY PROCEDURE:

Keep a person always outside the field to extend necessary help in case of Emergency during internal checking of ESP fields.

The test should be aware of the procedure adopted in testing schedule of ESP.

The test team should be aware of steps to be taken in case of damage to equipment / injury to personnel.

STATUS

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NTPC BHEL



Plant area: BOILER


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7.1

7.2

7.3

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7.6

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7.11

STATE OF THE PLANT:

7.1The mechanical erection of all system have been completed During mechanical checking of ESP internals, the connected ESP should have been isolated electrically and proper earthing is done. Should get clearance from boiler operation people to go inside ESP and check.All Electrical system have been erected and electrical clearance available for testing and commissioning.

L.T switch board, EC, ACP and disconnecting switches are off and fuses are removed

All electrical equipment are earthed

Transformers negative bushings and emitting system frame work, inspection doors and covers of insulator housings are earthed through discharge rods.

Interlock sequence strictly adhered to

All safety aspects as given in safety instructions are taken care off. (Refer O & M)

Debris and foreign materials such as welding electrode bits, temporary supports etc are removed.

No hole in the wall, roofs and hopper plates are left open.

EP control room is air conditioned/ventilated.

Ash handling system is ready.

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7.12

Ensure the following Critial dimensions / checks, (Machanical) completed.

(To be verified through Erection log sheets)

-Ensure the gap between Gas distribution screen and bottom of in let funnel of ESP is 100+10 mm

-Ensure Gas entry front casing wall and emitting electrode shock bar is 350+10 mm

-Ensure the distance between roof beam and emitting frame top is 195+5 mm minimum

-Ensure support insulator bottom tip to emitting electrode frame top is maintained as per drawing

-Ensure the central line of collecting rapping drive shaft centre to shock bar centre 310+5mm. If not available maintain it with proper shims.

-Emitting electrode support screen tube edge to emitting frame top edge distance is maintained as per drawing.

-Distance between centre of emitting system suspension point to first hook with collecting electrode frames maintained as per drawing.

-Emitting frames to collecting electrode distance maintained as per drawing

-Deflection plate to Emitting electrode suspension screen tube dimension is maintained as per drawing

-Confirm the suspension rod is centrally located with respect to support insulator.

-Confirm the shock pad and tumbling hammer face are in the same vertical plane. If necessary confirm the same with chalk test by running the collecting rapping of each field.

-Set rings are in position.

-Clearance between shock bar edge to shock bar guide is (40mm) and shock bars are moving freely.

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Plant area: BOILER


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7.13

-Ensure shock bar guides and link rods are aligned properly.

-Clearance between collecting electrode and hopper deflection plate in the vertical plane as per drawing.

-Straightness of shock bar and guide to be ensured.

-The distance between emitting electrode and collecting electrode is as per drawing.

-The pitch distance of emitting electrode as per drawing.

-Randomly check the spring back of emitting electrode

-Verticality of all collecting electrode at all level to be ensured, otherwise to be corrected.

-Ensure deflection plates and throttling plates are arrested by welding

-Distribution screen manhole doors are locked in position.RAPPING SYSTEM

-Confirm collecting rapping gearedmotor, clutch and coupling alignment

A slight axial play of the rapper shaft is maintained.

-With rapping shaft. Mark the direction of rotation of the rapping shaft outside. Even a short running of shaft in reverse direction will extensively damage the shock bars.

-Check the pin wheel arrangement for proper erection and confirm proper transmission of torque from rapping shaft. A minimum axial play of 5 mm on either side of shaft insulator is maintained. Correctly mark the direction of rotation over the geared motor.

-Confirm correct style of scavenging screws are installed concentrically around the shaft insulators.

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Plant area: BOILER


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7.14

8.0

8.1- Check the collecting rapping shaft and emitting electrode rapping shaft-sealing arrangement as per drawing.

-Confirm proper alignment of plain bearing and set rings and proper seating of rapping shaft in the bearing.

-Drain the old oil from the gear box and fill new oil into the gear box as per lubrication recommended upto the correct level marked..

-Confirm all drive motors bearings are greased

-Check all motor bolts are properly tightened after alignment.

-All the drive bolts and nuts are to be tack welded once commissioning check is completed.INSPECTION DOOR ON CASING AND HOPPERS

-Ensure that doors are swinging freely and latches are engaging properly with doors, Gaskets are air tight

-Earthing cable is connected properly.

Interlocks and keys are matching properly

METHOD:

Auxiliary Control Panel (Electrical)

-Confirm the ACP erected as per drawing

-Confirm the availability input power supply and rated voltage etc.

-Check the input and output bus bars for proper tightening of all connected fasteners including earthing.

-Check in each module the followings items wherever supplied for physical availability and conditions.

Ammeter, Voltmeter and their selector switches, Fuse units with correct rated fuses, Isolating switch, Indicator lamps with series resistor, Current trans former, hopper heater, Shaft and support insulator heaters availability at their locations with thermostats, contactors, control supply transformers, thermal overload correct setting as per the rating of the equipment, Ash level indicator sensors availability in their respective hoppers, Start /stop Local push button stations for proper wiring ( confirm water proof arrangement).STATUS

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Plant area: BOILER


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- Confirm the cable size, proper cable glanding, earthing of shielded input cables and output cables as per drawing

-Megger IR value of the input cables to the panel from incomer-A to panel bus section -A and the input cables to the panel from incomer-B to panel bus section-B independently with respect to earth by keeping open their respective ACBs open.

-Megger the panel power supply control supply buses, heater control supply and 240 bus bar.

-Confirm the availability of DC 220V and match both the sources for + and . Close one of the DC-IS switches and establish control DC power supply bus for energizing ACBs. Similarly isolate the first DC-IS and energies the second source and establish 220 V DC control supply bus to ACBs.

-Confirm the two source of power supply from LTMSB, three phases are having the same voltage with respect to earth. Measure phase to phase voltage also and confirm equal. Check and correct phase sequence of both source.

-Check the relay setting of ACB1, ACB2 and ACB3as per recommendations.

-Charge the ACP bus section-A by ACB1 closing.

-Confirm the voltage reading in all the three phases are reading correctly. Check the 240V bus voltage with respect to Neutral bus bar, Similarly check 110V bus voltage with respect to Neutral bus bar for both motor control supply and heater control supply. Similarly Change the TPDT SW of control transformer and repeat checking all bus bar voltages as earlier

-Repeat the same for ACP BUS SECTION-B as 8.49 to 8.50

-The interconnecting ACB3 has to be kept opened, match the phase sequence of the both the panel buses.

-Open ACB2, CloseACB3 check the output bus voltage of entire ACP.

-Open out ACB1, ACB3 opens out. Close ACB2, close ACB3 reconfirm the output bus voltages.STATUS

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NTPC BHEL



Plant area: BOILER


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8.2

8.3

Collecting and emitting Rapping System Commissioning :

Geared motors :

-In case of emitting electrode rapping system confirm that heating elements are properly fixed.

-Confirm glands are properly placed

-Insulators are healthy, clean and rigid without crack.

-Confirm the mechanical clearance for each rapping system and decouple the motor.

-Confirm the tightness of motor terminated cables, proper earthing, proper dressing of cables.

-Megger the motor and record the IR value. Measure the coil resistance and record. Confirm IR value is atleast 1Mohm. Otherwise heat the motor and till the IR value is satisfactory.

-Confirm the local push button station control supply terminal are properly done.

-Energise the concerned module and locally bump and confirm direction.

-If the direction is reverse, correct the direction.

-Couple and take trial run as per duty cycle of the motor to study the proper hammering. If the hammering is in the centre of shock pad in case of collecting rapping system for all the hammers and the hammer in the centr of shock beam in case of emitting rapping, stop the rapping motors.

-Clear for tack welding of all bolt and nuts of hammers etc.

-Commission all the rapping motors of all fields as above.Heating Elements :

-Ensure the IR value is more than 2M ohm

-Continuity is ascertained

Cables are terminated properly with crimped lugs and glands and terminal box cover is watertight.

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Plant area: BOILER


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8.4

8.5

8.6- Cable Armour and earth points are terminated to earth.

-Set the thermostat for hopper heaters at 120 deg C and 140 der C for support insulators. Verify the proper cable termination and continuity of thermostats. Swithch on the module and check the performance.

Disconnecting switches

-Ensure Insulators are healthy, clean and rigid

-HV bus terminal and earthe connections inside are tight.

-Operation of moving blades with HV and HV and earth contact is smooth and proper.

-Copper cable between moving arm and insulator head is properly connected. Each disconnecting switch is provided with a danger plate and two external earth connections to earth mat.

-Doors are closed tightly

-Interlocks provided at doors handles are working properly. INSULATOR HOUSING

-Insulators are clean, healthy and rigid

-Copper tubes are straight and not loose

-Heating elements are properly fixed

-Earthing is proper

-Screw legs and nuts for placement of alignment jigs are welded

-Doors are closed tightly

-Interlocks are working properly

-Each insulator housing is provided with a danger plate and two external earth connection to earth grid.

HIGH VOLTAGE BUS DUCTS

-Ensure flange ioints are provided with gasket and earthing cables.

Copper tubes are straight and tightly connected

STATUS

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NTPC BHEL



Plant area: BOILER


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8.7

8.8

8.9

ELECTRONIC CONTROL(EC) WITH HVR SYSTEM : (Refer INSTRUCTION MANUAL FOR SCR CONTROLLED HVDC Power supply 70KV dc Peak, 1200mA.DC Avg /BHEL/JHANSI and BAPCON MANUAL)

Visual Check : Before energizing the control cubicle a visual check is to be made. Check all components are in proper position and all the connection as per wiring drawings. If necessary restore the connections

Electrical Checks : Refer power and control schematic drawing. Disconnect the connector of Integrated controller short wires :

Group A: Short primary and secondary of aux. transformer T1, T2, T3.

Earthing of one end of winding of above transformer to be removed.

Group :B 103, 104 and Line contact of 52 CONTACTOR.

Measure the insulation resistance with 500 Volt megger between group A and Earth E, B & E and between A & B IT SHOULD BE AS FOLLOWS

A to E > 2Mohm

A to B > 30Mohm

B to E > 30Mohm

a) Normalise the shorting after insulation check and connect microprocessor controller .

b) Connect a load resistor of approximately 4Amps, 2000 watts, 500 Volt at C & D of the panel.

c) Connect supply 415 V AC, 50Hz across terminals A & B of the panel

d) Close the isolator ( 29) and check the indication for mains on , display and flickering of processor health indicating LED of Controller.

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Plant area: BOILER

PR CEDURE FOR COMMISSIONING OF ESP

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e) Check supply 24V AC at terminal 1 & 5 of TB2 with respect to ground.f) Check 18V AC at across pin 1 & 2 of firing circuit.

g) Keep controller in local mode.

h) Press HT on/off of push button of controller AND see that a voltage of the order of 400 volts appears in meter across load. Please note the output voltage cannot be controlled by current limit potentiometer with factory set parameters. For details close loop test manual of microprocessor controller. may be referred.i) Check the annunciation by shorting terminal s 2, 3, 4, 5 of TB1 with respect to earth i.e HVR interconnection. Operate thermal overload relay and check the annunciation and tripping of contactor. Under voltage alarm shall be annunciated of 40 sec time making HT on provided fault exists.

j) Contactor can also be made OFF by pressing HT on/off push button on controller once more.

With this controller is ready for commissioning

HVR SYSTEM : 70 KV DC Peak, 1200 mA.DC Avg. with Silicone oil filled.Input AC current to HVR 241 Amps. Input primary voltage is 415 volt

DRYING OUT CHECKS:

Oil test : Oil samples from top/bottom of tank is taken BDV value to checked at lab. The BDV should be atleast 25kv. If the BDV is less than 25 BDV, the oil is filterd through a filter machine till the BDV is achieved.

Buchholtz relay : Check the the relay for visual damage and correct acting of relays and their mercury switches.

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Plant area: BOILER


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Oil temperature indicator: Check the indicator for visual damage, for proper wiring for alarm and trip.

Completion of job: Check the oil level and top it upto requirement with dry oil. Check the complete wiring for various alarm/trip contacts tank and HIV positive terminal is completed.

IR value of transformer windings : 8.98 Measure the IR value which should be typical to the one given H-E = 200Mohm; L-E = 200Mohm: H-L = 200Mohm.

Open circuit Test :

a). Magnetising Curent Test: Prepare a circuit diagram as shown in the instruction manual of HVR in page C-12. In this test, the primary of HVR is fed from a two phase variac 500V/10A, and the magnetizing current drawn by HVR is measured. This may be compared with the test result of HVR.

b).Output voltage measurement :The measurement of HV open circuit output voltage should be done in conjunction with EC and this should be of the order of rated output DC KV. ( 70KV Peak).

Field IR VALUE measurement: Keep the HVR FIELD ISOLATOR SWITCH in middle position measure the IR of the field and confirm no shorting.

Commissioning the field.Connect the transformer rectifier as per drawing

a) Close the field isolator on top of the EP.

b) Ensure Microprocessor controller is in local mode.

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Plant area: BOILER


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c) Keep current limiting potentiometer of controller in minimum position

d) Close the isolator(29)e) Check the indications and Microprocessor controller as given inn the BAPCON manual.

Check the various settings of Microprocessor Controller parameters by pressing increment or decrement push-button. It should be identical to factory set value ( refer Manual of Microprocessor Controller ).

f) Keep the current limit potentiometer to 50% position, this could be seen in microprocessor controller display parameter (1).

g) Press HT on/off push-button of controller so as to close contactor (52). The output voltage and current shall start building up at time over ride initially then follow T: setting. Increase the current limit to 100% for rated current. Check voltage across shunt, it should be approximately equal to IratedX Rshunt Volts Dc. The voltage at pin F of MCRP card should be approximately 1 volt DC at full load otherwise adjust MCP2 potentiometer.

Follow the safety rules and regulation while charging EC-HVR

a. On appearance of spark across electrode, the spark counter shall register one count and output shall be blocked for a certain time. Then current will reach value as per S control setting and again build up at T setting rate. The spark sensitivity is factory set. However if required can be set with SS potentiometer.

AIR LOAD TEST : Air load test is an important commissioning activity. This gives the diagnosis of the following.

Proper erection and alignment of EP internals

Presence of any left out debris/hanging pieces which may limit the voltage or short the electrodes.

Healthiness of insulators

Healthiness of transformers and electronic controllers.

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NTPC BHEL

Station: NTPC- Simhadri BHEL Ref No.PS-DC-186-500-0043


Plant area: BOILER


SL.NO

PREPARATIONS :

This air load test has to be carried out at a time with one ESP consisting of eight fields.

Remove all temporary earth connection made with discharge rods

Confirm that rapping system/EC-HVR system of all the fields which are to be air load tested are commissioned and ready for operation.

If necessary for reconfirming the IR value of the field, meggering may be carried out by between earthing and emitting electrode at disconnecting switch by keeping open the moving blade in between the two fixed contacts. Close the disconnecting switch after IR value measurement.

Close all insulator housing, disconnecting switch and inspection doors adopting interlock sequence and return the key to the electronic controller.

Confirm from the concerned personnel that nobody having any inspection work in the concerned ESP ducts and get clearance for charging the ESP.

POCEDURE :

Make supply available to ACPs and Ecs.

Switch on all rapping motors on continuous mode.

Switch on EC and slowly raise the current. Note the meter reading for each interval of 50 mA. Raise upto rated current. Look for flashover if any and record.

The rapping motors are to be changed to intermittent rapping mode after taking voltage & current readings.

Keep all the fields energised for a period of 8 hours.

Log air load readings at every one hour interval.

Switch off the ECs, ACPS AND L.T. Board.

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Plant area: BOILER


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9.0

COMPLETION OF ESP COMMISSIONING:

ESP Commissioning completed by completing the proposals given in Section 3.0.

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