PDEC
INDIAN OIL CORPORATION LTDPROCESS DESIGN ENGINEERING CELL(PDEC)
HEAT EXCHANGERS DESIGN &
MANUFACTURING FEATURESBY
M. BALA
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PDEC CONTENT
• DEFINITION OF HEAT EXCHANGERS
• TYPES OF HEAT EXCHANGERS
• CLASSIFICATION OF SHEEL AND TUBE HEAT EXCHANGERS
• DIFFERENT TYPES OF HEAT TRANSFER EQUIPMENTS
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PDEC CONTENT
• COMPONENTS OF SHELL AND TUBE HEAT EXCHANGERS
• NOMENCLATURE OF HEAT EXCHANGERS
• CONSTRUCTION OF HEAT EXCHANGERS
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PDEC CONTENT
• CODES/ STANDARDS
• DESIGN OF HEAT EXCHANGERS
• MATERIAL IDENTIFICATION CHART
• SELECTION OF HEAT EXCHANGERS TYPES
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PDEC CONTENT
• THERMAL DATA SHEET OF HEAT EXCHANGERS
• MECHANICAL DATA SHEET OF HEAT EXCHANGERS
• MANUFACTURING FEATURE
• MAINTENANCE OF HEAT EXCHANGERS
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PDEC HEAT EXCHANGERS DESIGN
DEFINITION OF HEAT EXCHANGER:
A heat exchanger is a piece of equipment built for efficient heat transfer between a hot process stream and a cold process stream.
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PDEC HEAT EXCHANGERS DESIGN
TYPES OF HEAT EXCHANGERS:
• Shell & Tube heat exchanger
• Plate heat exchanger
• Plate & Shell heat exchanger
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PDEC HEAT EXCHANGERS DESIGN
SHELL AND TUBE HEAT EXCHANGER
Shell & tube heat exchangers consist of a series of tubes & cylindrical shell. One set of these tubes contains the fluid that must be either heated or cooled. The second fluid runs over the tubes i.e inside the shell that are being heated or cooled. A set of tubes is called the tube bundle.(as shown in Fig).
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PDEC HEAT EXCHANGERS DESIGN
SHELL AND TUBE HEAT EXCHANGER
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PDEC COMPLETE HEAT EXCHANGER
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PDEC HEAT EXCHANGERS DESIGN
PLATE HEAT EXCHANGER
It is composed of multiple, thin, slightly separated plates that have very large surface areas and fluid flow passages for heat transfer.
• Much higher heat transfer co-efficient• Lower cost, low space requirement
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PDEC PLATE HEAT EXCHANGERS
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PDEC HEAT EXCHANGERS DESIGN
PLATE AND SHELL HEAT EXCHANGERS
• It is combines with plate heat exchanger and shell & tube heat exchanger technologies.
• High heat transfer, high pressure, high operating temperature
• Compact in size• Low fouling
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PDEC HEAT EXCHANGERS DESIGN
PLATE AND SHELL HEAT EXCHANGERS
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PDEC HEAT EXCHANGERS DESIGN
TYPE OF SHELL AND TUBE HEAT EXCHANGERS• Shell and Tube Heat Exchangers (STHEs) are the most
widely and commonly used unfired heat transfer equipment in the chemical process industries.
• Shell and tube heat exchanger may be classifiedBy construction andBy service
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HEAT EXCHANGERS NOMENCLATURE:
An STHE is divided into three parts mainly:
• The front head • The shell and • The rear head
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HEAT EXCHANGERS DESIGN
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TEMA DESIGNATIONS FOR SHELL-AND-TUBE. HEAT EXCHANGERS
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HEAT EXCHANGERS NOMENCLATURE:
• There are five front head types: A, B, C, D and N.
• There are eight rear head types: L, M, N, P, S, T, V, and W which corresponding in practice to only three general construction types, namely fixed tube sheet, U-tube and floating head.
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HEAT EXCHANGERS DESIGN
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Cont:
• Rear head ‘L’ is identical to a front head ‘A’ and rear head ‘M’ is identical to a front head ‘B’ while N is the same nomenclature.
• There are seven types of shell depending on fluid flows through a shell - E, F, G, H, J, K and X.
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HEAT EXCHANGERS DESIGN
PDEC HEAT EXCHANGERS DESIGN
• CLASSIFICATION BY CONSTRUCTION It may be classified into three categories.
• Fixed-tube sheet heat exchanger
• U-tube heat exchanger
• Floating- head heat exchanger
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PDEC HEAT EXCHANGERS DESIGN
FIXED-TUBE SHEET HEAT EXCHANGER
• A fixed-tube sheet heat exchanger has straight tubes secured at both ends to tube sheets welded to the shell.
• The construction may have removable channel covers (e.g. AEL), bonnet –type channel covers (e.g. BEM) or integral tube sheets (e.g. NEN)
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PDEC HEAT EXCHANGERS DESIGN
FIXED-TUBE SHEET HEAT EXCHANGER
Bonnet(StationaryHead)
StationaryTubesheet Support
BracketStationaryTubesheet
Bonnet(StationaryHead)
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PDEC HEAT EXCHANGERS DESIGN
FIXED-TUBE SHEET HEAT EXCHANGER
Advantages of this exchangers• The main advantage of a fixed-tube sheet
construction is low cost as it has the simplest construction.
• Permits mechanical cleaning of the inside of the tubes as these are accessible after removal of the channel cover or bonnet.
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PDEC HEAT EXCHANGERS DESIGN
FIXED-TUBE SHEET HEAT EXCHANGER
• No leakage from the shell side fluid as there are no flanged joint.
Disadvantages of this exchangers• The outside of the tube can not be cleaned
mechanically as the bundle can not be removed from the shell.
• Due to this shell side fluid should be clean
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PDEC HEAT EXCHANGERS DESIGN
U-TUBE HEAT EXCHANGER• As name implies, the tubes of a U-tube heat
exchanger are bent in the shape of a U. There is only one tube sheet in a U-tube heat exchanger.
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PDEC HEAT EXCHANGERS DESIGN
U-TUBE HEAT EXCHANGERAdvantages of this exchangers• It permits the tube bundle to expand or
contract according to the differential stress set up due to free at one end.
• It permits the outside of the tubes cleaning as the tube bundle can be removed.
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PDEC HEAT EXCHANGERS DESIGN
U-TUBE HEAT EXCHANGER Disadvantages of this exchangers• The inside of the tube cannot be cleaned
effectively.
• This exchangers should not be used for services which have dirty fluid inside the tubes.
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PDEC HEAT EXCHANGERS DESIGN
U-TUBE HEAT EXCHANGER
• It places a very severe limitation on U-tube heat exchangers for refinery services, which usually have dirty streams on both the tube side and shell side. This is primarily the reason why U- tube heat exchangers are not generally used in oil refineries .
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PDEC HEAT EXCHANGERS DESIGN
FLOATING- HEAD HEAT EXCHANGER•A Floating-heat exchanger is one where one tube sheet is fixed relative to the shell and the other is free to float within the shell.
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PDEC HEAT EXCHANGERS DESIGN FLOATING- HEAD HEAT EXCHANGER•Advantages of the exchangers
This type of heat exchanger permits free expansion of the tube bundle
It permits cleaning of both the inside and outside of the tubes.
It is used for services where both the shell side and tube side fluids are dirty.
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PDEC HEAT EXCHANGERS DESIGN
FLOATING- HEAD HEAT EXCHANGERFloating head exchanger is the most versatile construction.
•Disadvantages of this exchangersIt is more costlier than Fixed tube & U- tube exchangers due to: More components in this construction Shell diameter is larger than floating tube sheet.
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PDEC HEAT EXCHANGERS DESIGN
FLOATING- HEAD HEAT EXCHANGER
Various types of floating head construction are:
• Pull through with backing device:TEMA type S• Pull through: TEMA type T• Outside- packed stuffing – box: TEMA type P • Outside-packed lantern ring: TEMA type W
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PDEC HEAT EXCHANGERS DESIGN
• PULL THROUGH WITH BACKING DEVICE: TEMA type S
Most commonly used type in the chemical processing industries.
The floating head cover is secured against the floating tube sheet by bolting it to an ingenious device called split backing ring.
The floating head closure is located beyond the end of the shell and contained by a shell cover of a larger diameter.
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PDEC HEAT EXCHANGERS DESIGN
Cont.For dismantling the heat exchanger, the shell
cover is removed first, then the split backing ring and finally the floating head cover after which the tube bundle can be removed from the stationary end.
For assembling the heat exchangers, the reverse order is followed.
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PDEC HEAT EXCHANGERS DESIGN
PULL THROUGH WITH BACKING DEVICE: TEMA type S
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PDEC HEAT EXCHANGERS DESIGN
Pull through: TEMA type T• The floating head cover is bolted directly to
the floating tube sheet so that a split backing ring is not required.
• The advantage of this type construction is that the tube bundle may be removed from the shell without removing either the shell or floating head cover.
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PDEC HEAT EXCHANGERS DESIGN
Pull through: TEMA type T
• It is generally used for kettle re-boilers having a dirty heating medium where u-tube cannot be used.
• The shell diameter is the largest in this type of construction since floating head tube sheet with cover has to be removed through the shell. Hence, the cost is the highest in this type of construction.
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PDEC HEAT EXCHANGERS DESIGN
• Pull through: TEMA type T
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1521
6
4
3
Rear tubad end Shell Stationary Head end
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PDEC HEAT EXCHANGERS DESIGN
OUTSIDE-PACKED STUFFING–BOX:TEMA TYPE P • In this construction, the shell side fluid is sealed
by ring of packing compressed within a stuffing- box by a follower ring.
• This construction is prone to leakage. Due to this, its usage is limited to shell side services, which are:
Non-hazardous and non-toxic services Moderate pressure and temperature (40
kg/cm² and 300ºc).39
PDEC HEAT EXCHANGERS DESIGN OUTSIDE- PACKED STUFFING – BOX: TEMA TYPE P
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PDEC HEAT EXCHANGERS DESIGN
OUTSIDE-PACKED LANTERN RING: TEMA TYPE W
• The shell side and tube side fluids are sealed by separate ring of packing or O-ring and separated by a lantern ring provided with weep holes. Hence any leakage will be the outside.
• The width of the tube sheet necessarily has to be sufficient to accommodate the two packing rings and the lantern ring, plus the expansion margin.
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PDEC HEAT EXCHANGERS DESIGN
OUTSIDE-PACKED LANTERN RING: TEMA TYPE W• This design is limited to 9.9 kg/cm² and 204ºc.
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3
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CLASSIFICATION BY SERVICE It may be classified into four categories.• Single phase (both shell side and tube side)• Condensing (one side condensing and other
single phase)• Vaporizing ( one side vaporizing and the other
single phase)• Condensing/vaporizing (one side condensing and
the other vaporizing)
HEAT EXCHANGERS DESIGN
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DIFFERENT TYPES OF HEAT TRANSFER EQUIPMENTS
• Heat Exchanger: both side single phase process streams (that is not an utility).
• Cooler: One stream a process fluid and the other stream a cold utility, such as cooling water or air.
• .
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Cont.• Heater: One stream a process fluid and the other
stream a hot utility, such as stream or hot oil
• Condenser: One stream a condensing vapor and the other stream a cold utility, such as cooling water or air.
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Cont.• Chiller: One stream a process fluid being condensed at
sub-zero temperature and the other stream a boiling refrigerant or process stream (evidently cryogenic).
• Vaporizer: One stream a vaporizing liquid and the other a gas or a liquid.
• Re-boiler: One stream a bottom stream from a distillation column and other a hot utility (stream or hot oil) or a process stream.
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PDEC RE-BOILER
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COMPONENT OF STHEs :
The principal components of an STHE are:
• Shell and Shell cover
• Tubes
• Channel and Channel cover48
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COMPONENT OF STHEs :
• Tube sheet
• Baffles
• Floating head cover
• Nozzles49
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COMPONENT OF STHEs :
The other components are,
• Tie-rods and spacers,
• Pass partition plates,
• Impingement plate,
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COMPONENT OF STHEs :
• Longitudinal baffles,
• Sealing strips, sliding strips, • Supports and foundation
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VARIOUS PARTS OF HEAT EXCHANGER
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1. Stationary Head-Channel
2. Stationary Head-Bonnet
3. Stationary Head Flange-channel Or Bonnet
4. Channel Cover
5. Stationary Head Nozzle
6. Stationary Tubesheet
7. Tubes
8. Shell
9. Shell Cover
10. Shell Flange-Stationary Head End
11. Shell Flange-Rear Head End
12. Shell Nozzle
13. Shell Cover Flange
14. Expansion Joint
15. Floating Tubesheet
16. Floating Head Cover
17. Floating Head Cover Flange
18. Floating Head Backing Device
19. Split Shear Ring
20. Slip-On Backing Flang
21. Floating Head Cover
22. Floating Tubesheet Skirt
23. Packing Box
24. Packing
25. Packing Gland
26. Lantern Ring
27. Tierods and Spacers
28. Transverse baffles or Support Plates
29. Impingement Plate
30. Longitudinal Baffle
31. Pass Partition
32. Vent Connection
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VARIOUS PARTS OF HEAT EXCHANGER
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SHELL AND SHELL COVER:• The shell is cylinder in which tubes are contained
and serves to contain the shell side flowing stream and forms the outer casing of the tube bundle.
TUBE BUNDLE:• The tube bundle is the heart of the shell and tube
unit and comprises tubes, tube sheets, baffles, floating head cover, split ring. Tie rods, impingement plate, baffle, longitudinal baffle and sealing/sliding strips.
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TUBES:
• Tubes are most vital component of the heat exchangers.
• Tubes are two types, namely a) plain or bare and b) finned – external or internal
• Plain tubes are most common ones which are generally used in refineries
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Cont. • Tubes are usually defined by outer dia (OD)
and wall thickness (or BWG- Birmingham Wire Gauge).
• Wall thickness can be either minimum wall (when there is no under-tolerance, but only over tolerance), or average wall thickness (when there is both under tolerance and over tolerance).
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Cont. • The usual practice is to order tubes with
minimum wall thickness for carbon steel and low alloy steel tubes and with average wall thickness for non-ferrous and high-alloy steel tubes.
• Material of construction of tubes are- carbon steel, low and high alloy steels, special stainless steels, Admiralty brass and bronze, alloys of copper and nickel, Hastealloys and Tantalum. 57
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TUBE SHEETS: • The ends of the tubes fit into a common sheet
and are expanded against or welded to the shell to form a pressure tight seal which separates fluid in the shell and that in the tubes.
Tube sheet are two types
• Fixed/stationary tube sheet – A tube sheet fixed or welded to the shell.
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Welded tube to tube sheet joints are usuallyemployed for severe condition such as high pressure (say, in excess of 80 kg/cm²) or when handling toxic or inflammable fluids where leakage is not permitted.
Floating tube sheet:• A tube sheet which can move to allow for
expansion or contraction of the tubes relative to the shell.
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• Tube sheet thickness can vary from 25 mm for low-pressure low shell dia. to 300 mm for high pressure & large shell
• Depending on the severity of the situation, tubes are either expanded into grooves in the tube sheet or welded to theme to tube sheet
Baffles: • It serve to support the tubes as well as to impart a
sufficiently shell side velocity to yield a satisfactory heat transfer co-efficient.
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• Baffles are held securely in place by a combination of tie rods and spacers.
• The length of spacers is equal to the baffle spacing.
• The outside diameter of the baffle has to be less than the inside diameter of the shell to permit insertion of the tube bundle into the shell and removal of the bundle from the shell.
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• A plate which is placed transversely along the centre line of the shell and is employed to divide the shell into two or more compartments is called longitudinal baffle.
• A single longitudinal baffle from one tube sheet to just sort of the other tube sheet produce on ‘F’ shell i.e. a shell with two shell passes.
LONGITUDINAL BAFFLES:
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• A pair of sliding strips is provided at the bottom of floating head tube bundles for their insertion and removal to and from the shell.
• A sufficient number of sealing strips is required to be inserted in the gap between the shell and outer most tubes in floating head tube bundles to minimize leakage of the shell
SLIDING AND SEALING STRIPS:
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IMPINGEMENT PLATE: • The inlet nozzle is provided with a plate
which is used to protect the uppermost tubes located just below the shell side inlet nozzle against direct impingement by the shell side fluid is called an impingement plate.
CHANNEL, CHANNEL COVER & PASS PARTITION PLATES:
• Channel is the inlet and outlet chambers for the fluids flowing through the tubes.
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• A channel may either be of a bonnet const. where a dished end is welded to channel barrel or a flanged channel cover.
• Pass partition plates are the plate in the channel which make the fluid in the tubes flow through one set of tubes and back through another set. They fit tightly into grooves in the tube sheet and channel cover in order to eliminate the possibility of leakage of the tube side fluid from one pass to the next.
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PDEC PASS PARTITION ARRANGEMENT FOR TUBE PASSES
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CODES/STANDARDS:• API 660 - Shell & tube heat exchangers for general
refinery services.
• ASME Section VIII – Pressure Vessels for Shell thickness cal., Welding & Testing
requirements.
• TEMA(Tubular Exchanger Manufacturers Association) for design of STHEs
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TEMA: There are three classes of TEMA;• Class-R Refinery Service• Class-B Chemical Process service• Class-C General service
LIMITATION OF TEMA:• Inside diameter of shell is 2540 mm• A design pressure of 211 kg/cm2
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BASIC FORMULA:
The basic formula for heat transfer is, Q = A* U*△T Where, Q = Total heat to be transferred, Kcal/hr A = Required effective heat exchanger surface, based on the tube
O.D , m2U= Overall heat transfer co-efficient,Kcal/hr-m2-c
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Cont.△T = effective mean temperature difference, OC
For exchangers where the flow of the hot and cold fluids is true counter or concurrent, △T is equal to the log mean temperature difference (LMTD)
In most commercial exchangers, the use of shell baffles and multiple tube passes causes the flow to be partially counter current and
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Cont. partially concurrent flow. For this mixed flow △T is obtained by
applying a correction factor (F) to the calculated LMTD for a counter current flow arrangement i.e.
△T (effective) = LMTD * F ( F= < 1.0) Where,
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LMTD =△Th - - △Tc
Ln (Ln (△Th / / △Tc )
PDEC
Cont.Where, △Th = T1 - t2
△Tc = T2 - t1
T1 = Inlet temp. of hot fluid
T2 = Outlet temp. of hot fluid
t 1 = Inlet temp. of cold fluid
t 2 = Outlet temp. of cold fluid 72
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Cont. The value of correction factor “F” is obtained from TEMA
chart. “F” is plotted as a function of “P” and “R” . Where” and “R”
P = Temp. effectiveness or efficiency of exch. = ( t of cold fluid) / ( t of hot & cold fluid inlet temp.)△ △
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P =t2 - t1
T1 - t1
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Cont. Where, R = Heat capacity rate ratio. = wc / Wc
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R =T1 - T2
t2 - t1
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BASIS OF DESIGN PRESSURE:• Maximum pump shut of pressure, or• 25 psi or 10% greater than the maximum operating pressure in
PSIG
BASIS OF DESIGN TEMPERATURE:
• The minimum design temp is normally set a 25oC above the maximum operating temp at the exchanger
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DESIGN OF STHEs:
The design of shell and tube heat exchangers comprises two distinct activities
are:• Thermal design and
• Mechanical design
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Thermal design:
• In thermal design, the heat exchangers is sized, which means that all the principal construction parameters such as shell type and diameter, number of tubes, tube OD and thickness, tube length, tube pitch, number of tube passes, baffle spacing & cut and nozzles sizes are determined.
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Basic aims of a thermal designer are: 1.Produce a thermal design that has a low overall cost.• Overall cost = initial cost + operating cost• Initial cost is evidently the fixed cost or first cost of the
heat exchangers• Operating cost = pumping cost + maintenance cost +
down time cost
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Cont.: • Maintenance cost= periodically cleaning cost + anti - foulant
cost + any repair or replace. Cost.2. Utilize allowable pressure drop as fully as possible.• Higher the velocity of the fluid higher will be the heat transfer
co-efficient.• Higher heat transfer co-efficient will be higher pressure drop.
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Cont.: • Higher heat transfer co-efficient will tend to reduce
first cost of the exchangers. • Higher pressure drop will tend to increase the
operating cost of the exchangers• Thus a very important goal for a good thermal design
is the best utilization of the allowable pressure drop
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REQUIRED DATA FOR THERMAL DESIGN : Process dept. have to furnish the following data for thermal design of heat
exchangers:
• Name of the fluids• Flow rate of the fluids• Inlet & outlet temperature of the fluids• Operating pressure of the fluids
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Cont. • Allowable pressure drop Generally 0.5 to 0.7 kg/cm2 per shell for liquid 0.05 to 0.02 kg/cm2
per shell for gases • Fouling refers- accumulation and deposition of living organisms and
certain non-living materials on the surface• Properties of fluids like – Specific gravity/ density, thermal conductivity,
viscosity and specific heat.
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Cont.• Heat release profile for two phase flow – it is a plot of heat duty and weight fraction
vapor versus temperature and is an essential part of the process data sheet.• Heat exchanged i.e. heat duty
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Process data sheet of HE 1.pdf...
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Cont. • Selection of heat exchanger type i.e Fixed tube, U-tube or
Floating head tube exchangers (i.e AES, BEM )etc.
• Placement of Fluids Generally low flow rate fluid is placed on the shell side .This
facilitates provision of adequate turbulence by increasing number of baffles
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Cont. Cooling water which is likely to deposit scales is generally placed on
tube side for facilitating mechanical cleaning of tubes from inside In general highly befouling fluids that need frequent mechanical
cleaning of heat exchangers are usually placed on tube side Highly corrosive fluids are preferably placed on tube side
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Cont. Fluids with very high operating pressure are preferably placed on tube side• Line sizes: Generally line size match with nozzle sizes• Preferred tube size: OD: Commonly used OD 19.05/ 25.4 mm Tube thick.: Commonly used thk.2 / 2.5 mm Length: Commonly used length 6000 / 9000 mm
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Cont.
• Maximum shell diameter As per TEMA ID is 2540 mm As per engineering practice, For floating & U-tube exchangers: Shell ID 1400-1500 mm For fixed tube heat exchanger: No limitation
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Cont.
• Corrosion allowance
Tube: As per TEMA no corrosion allowance is applied in tube Shell: Depends on services and materials of construction. Generally 1.5 to 3 mm is used
depending on materials.
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Cont.
• Velocity –In-general very high velocity lead to erosion. For liquid- minimum recommended velocity in s tube side is 0.9 m/s while
maximum is 2.4 m/s. Shell side velocity is from 0.6 t0 1.5 m/sFor gases – maximum tube side velocity is 35 m/s
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Cont.
• Type of shell As per TEMA, there are seven types of shells like E, F, G, H, J, K & X.
• Tube lay out pattern There are 4 types of tube lay out pattern.
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Rotated Triangular- Not Used when mechanically cleaning is required
Triangular- Not Used when mechanically cleaning is required.
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Square- When mechanically cleaning is required
Rotated square- When mechanically cleaning is required
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• Tube Pitch; center to center distance between two adjacent tubes.
For triangular & rotated triangular pattern tube pitch is 1.25 times the tube OD
For square or rotated square pattern tube pitch is generally (OD+6mm)
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Final decision on exchanger type depends on many factors but the table given below is only for guide lineShell side fluid Tube side fluid Type of exchanger
Clean Dirty Clean Dirty
Yes - Yes - Fixed tube sheet or U-tube with triangular pitch
Yes - - Yes Fixed tube sheet or floating head with triangular pitch
- Yes Yes - U-tube or floating head with square pitch
- Yes - Yes Floating head with square pitch
SELECTION OF HEAT EXC.TYPE BASIS ON SERVICES
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THERMAL DESIGN OF HEAT EXCHANGERS IS DONE BY
• HTRI (Heat Transfer Research Institute) Soft ware, USA
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THERMAL DATA SHEET OF HEAT EXCHANGER:
• Heat exchanger thermal specification sheet is divided into three parts,
General information of exchangers
Performance of exchangers
Construction of exchangers
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THERMAL DATA SHEET.pdf
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• MECHANICAL DESIGN:
Detailed calculations are carried out to determine the dimensions of various components such as tube sheets,girth flanges, shell , shell barrel, channel, channel barrel,Baffle plate, floating head dish, etc and a complete bill of materials and engineering drawings such as bundles assembly and setting plan drawings are generated.
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Generally there are two types of baffles• Plate type - Single segmental
- Double segmental - Triple segmental
Baffles:
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PLATE TYPE BAFFLES:
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ROD TYPE BAFFLE-
Entire heat transfer area is effective
Tube bundle is vibration free
No stagnation of flow, uniform flow
Pressure drop minimum
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ROD TYPE BAFFLE:
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BAFFLE SPACING:
• Center to center line distance between adjacent baffles is called baffle spacing
• Minimum spacing as per TEMA is one fifth of the shell ID or 51 mm whichever is greater.
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BAFFLE SPACING:
• For example if shell inside diameter = 1000 m Then 1/5th = 1000/5 = 200 mm
• So spacing should be 200 mm
• Maximum spacing is usually the shell ID
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BAFFLE CUT: • It is the segment opening heights expressed as a
percentage of the shell inside diameter . Baffle cuts are :• Horizontal- This is used for single pass shell for
minimizing the accumulation of deposit at the bottom.
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BAFFLE CUT: • Vertical - This is used for two pass shell for ease of fabrication and bundle assembly, as well as for condenser.
• Recommended baffle cut is from 20% to 35%
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Baffle or support plate thickness should be as per below table (R-4.41 of TEMA)
Shell ID Plate thickness
Unsupported tube length between central baffles
610 mm & under
Over 610 - 914 mm
Over 914 - 1219 mm
Over 1219 - 1524mm
Over 1525mm
152 – 356 3.2 4.8 6.4 9.5 9.5
381 - 711 4.8 6.4 9.5 9.5 12.7
735 - 965 6.4 7.5 9.5 12.7 15.9
991 - 1524 6.4 9.5 12.7 15.9 15.9
1549 - 2540 9.5 12.7 15.9 19.1 19.1
BAFFLE PLATE THICKNESS :
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Tie rod and spacers shall be provided to retain all baffles and tube support plates securely in position.
Number and size of the tie rods will be as per below table (R-4.71 of TEMA)
Nominal shell diameter in mm
Tie rod diameter in mm Minimum number of tie rod
152 - 381 9.5 4
406 – 686 9.5 6
711 – 838 12.7 6
864 – 1219 12.7 8
1245 – 1524 12.7 10
1549 - 2540 15.9 12
TIE ROD AND SPACERS:
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Material Identification chart:
Description of parts
Carbon steel Alloy steel Stainless Steel
Shell SA516Gr60/70 SA387GR5CL2 SA240Gr316
Shell cover barrel SA516Gr60/70 SA387GR5CL2 SA240Gr316
Shell cover bonnet SA516Gr60/70 SA387GR5CL2 SA240Gr316
Channel SA516Gr60/70 SA387GR5CL2 SA240Gr316
Channel cover SA105 SA182GrF5 SA182Gr316
Tubes SA179 SA213GrT5 SA213Gr316
Tubes sheet SA266Gr.2 SA336GrF5 SA240Gr316
Baffles SA516Gr60/70 SA387 Gr5CL2 SA240Gr316
Floating Head Dish SA266Gr.2 SA336GrF5 SA336Gr316
Girth Flanges SA266Gr.2 SA336GrF5 SA336Gr316
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Material Identification chart:
Description of parts
Carbon steel Alloy steel Stainless Steel
Nozzles Neck SA106GrB SA335GrP5 SA312Gr316
Nozzles Flanges SA105 SA182GrF5 SA182Gr316
PAD SA516Gr60/70 SA387GR5CL2 SA240Gr316
Backing Ring SA105 SA336GrF5 SA336Gr316
Tie Rods SA516Gr60/70 SA387GR5CL2 SA240Gr316
Partition Plate SA516Gr60/70 SA387GR5CL2 SA240Gr316
Impingement plate SA516Gr60/70 SA387GR5CL2 SA240Gr316
Sealing strips SA516Gr60/70 SA387GR5CL2 SA240Gr316
Spacers SA179 SA213GrT5 SA213Gr316
Saddle plate SA516Gr60/70 SA387GR5CL2 SA240Gr311
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PDEC
MECHANICAL DATA SHEET OF EXCHANGER:• This is required for procurement of heat
exchangers.
110
Mechanical Data sheet .pdf
PDEC
• DESIGN SOFTWARE:
• PV ELITE and Microprotol software are being used worldwide
• Microprotol By EU Research, France
• PV- Elite by COADE taken over by Intergraph, USA
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PDEC
DRAWINGS AND ASME CODE DATA REPORT:• Drawings for approval and changeThe manufacturer shall submit for purchaser’s
approval three(3) prints of an outline drawing showing nozzle sizes and locations, overall dimensions, support and weight.
It is anticipated that a reasonable number of minor drawing changes may be required at that time.
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MANUFACTURING FEATURES
PDEC
Cont.Any changes may cause additional expense
chargeable to the purchaser.Purchaser’s approval of drawings does not relieve
the manufacturer of resposibility for compliance with the standard and applicable ASME code requirements.
The manufacturer shall not make any changes on the approved drawings without express agreement of the purchaser.
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MANUFACTURING FEATURES
PDEC
Cont.Any changes may cause additional expense
chargeable to the purchaser.Purchaser’s approval of drawings does not relieve
the manufacturer of responsibility for compliance with the standard and applicable ASME code requirements.
The manufacturer shall not make any changes on the approved drawings without express agreement of the purchaser.
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MANUFACTURING FEATURES
PDEC
Cont.Shop detail drawings are for internal use by the
fabricator, it may be furnished to the purchaser upon request.
• Drawings for recordAfter approval of drawings manufacturer furnished 3 set
of drawings along with all documents to the purchaser
+115
MANUFACTURING FEATURES
PDEC
• Proprietary rights to drawingsThe drawings and the design indicated by the
manufacturer are to be considered the property of the manufacturer and are not to be used or reproduced without his permission, except by the purchaser for his own internal use.
• ASME code data reportsAfter completion of fabrication and inspection of
ASME code stamped exchangers, the manufa. shall furnish 3 set of ASME data report.
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MANUFACTURING FEATURES
PDEC
INSPECTION: There are two yepes of inspection:• Manufacturer’s Inspection• Purchaser’s Inspection
• Manufacturer’s InspectionInspection and testing of units will be provided by
the manufacturer unless otherwise specified.
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MANUFACTURING FEATURES
PDEC
The manufacturer shall carry out the inspection required by the ASME code and also inspection by state and local codes .
• Purchaser’s InspectionThe purchaser shall have the right to make
inspection during fabrication and to witness any test.
Inspection by the purshaser shall not relieve the manufacturer of his responsibilities.
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MANUFACTURING FEATURES
PDEC
PREPARATION FOR SHIPMENT:• CleaningInternal and external surfaces are to be free from
loose scale and other foreign material that is readily removable by hand or power brushing
• DrainingWater, oil or other liquids used for cleaning or
hydro-static testing are to be drained from all units before shipment. 119
MANUFACTURING FEATURES
PDEC
• Flange protectionAll exposed machined contact surfaces shall be
coated with a removable rust preventative.All threaded connections are to be suitably plugged.
• Damage protectionThe exchangers and any spare parts are to be
suitably protected to prevent damage during shipment.
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MANUFACTURING FEATURES
PDEC
GUARANTEES: It may be given on the basis of• Performance and• Defective parts• Performance GuaranteeThe manufacturer shall guarantee thermal
performance and mechanical design of a heat exchanger, when operated at the design conditions specified by the purchaser in his order.
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MANUFACTURING FEATURES
PDEC
Cont.
This guarantee shall extend for a period of twelve months after shipping date.
The thermal guarantee shall not be applicable to exchangers where the thermal perfomance rating was made by the purhaser.
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MANUFACTURING FEATURES
PDEC
• Defective parts Guarantee
The manufacturer shall repair or replace any parts proven defective within the guarantee period.
Finished materials and accessories purchased from other manufacturers, including tubes are warranted only to the extent of the original manufacturer’s warranty to the heat exchanger.
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MANUFACTURING FEATURES
PDEC
MANUFACTURES OF HEAT EXCHANGER:
• M/s Aero-therm Products
• M/s Hindustan Radiators
• M/s Unique Chemo-plant Equipments
• M/s Larsen & Toubro
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PDEC
MANUFACTURES OF HEAT EXCHANGER:
• M/s Hindustan Dorr Oliver Ltd
• M/s Godrej
• M/s Precision Engineering.
• M/s Universal Heat Exchangers
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PDEC
MAINT. OF HEAT EXCHANGERS
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PDEC ROUTINE MAINTENANCE
OPERATIONAL PROBLEMS
• Decline in heat transfer efficiency / high pressure drop
• Scaling, fouling, choking, etc.,
• Internal Leak
Causing contamination between shell and tube fluids
127
PDEC ROUTINE MAINTENANCE
OPERATIONAL PROBLEMS
• Gasket Leaks
Due to thermal shock during start-up, shutdowns & Upsets
• Tube Leaks
Tube failure due to fatigue, ageing & corrosion
BLINDING THE EQUIPMENTS
128
PDEC
• Why ?
(During a shutdown, in the presence of air and liquid water, often dew point water, the sulfides convert to polythionic acid which causes inter-granular Stress Corrosion Cracking to Austenitic steels)
• Materials prone for SCC
(Austenitic SS tube bundles - SS 304, SS310, SS316, SS321, SS347)
PASSIVATION
129
PDEC
• When ? Before Opening of the equipments
• Solution Soaked with a solution of DM Water, Sodium
Carbonate (2%) and Sodium Nitrate (0.5%) for about 8 hours.
PASSIVATION
130
PDEC
• Opening the covers of heat exchangers• Removing of bundle Bundle Extractor or Puller
131
PDEC
• Chemical Cleaning Shell - Fixed Tube Sheet Bundle Vacuum Condensers, Ejector Condensers,
Reboilers 0.5% concentration HCl with inhibitor
circulation for 8 hours Hot water wash Branded chemicals Online by wash water circulation
EXCHANGER CLEANING
132
PDEC
• Kero -bath soaking Crude vacuum, Asphalt services• Hydroblasting (For Tube exteriors) Water jet at a pressure of 300 - 600 Kg/Sq.cm (Up to 35000 psi / 2500 bar)
133
PDEC Hydro-blasting (For Tube exteriors)
Before Cleaning After Cleaning
134
PDEC Hydro-lancing (For Tube interiors)
Manual Operation Power Lancing135
PDEC Hydro-lancing (For Tube interiors)
Before Cleaning After cleaning
136
PDEC
• Gasket Replacement
A gasket is a compressible material, or combination of materials, which when clamped between two stationary members prevents the passage of the media across those members.
• Gasket Selection Tem. of the media to be contained,
Corrosive nature of the application and Criticality of the application
137
PDEC
• GASKET CLASSIFICATION CAF (Compressed asbestos fiber)
250 deg. C, 30 bar, Water, steam and for non-critical applications
138
PDEC
• GASKET CLASSIFICATION IJA (Iron Jacketed Asbestos)
High Temperature applications Sheet Metal - SS, Brass, Monel , Al, In-conel Filler - Asbestos, PTEF, Grafoil
139
PDEC
• GASKET CLASSIFICATION Spiral Wound Gasket (SPWD)
(SPWD) with Asbestos filled & Inner Ring (13mm) & Outer Nose (4 mm width) 260 – 650 C
Winding - SS 410, 304, 316, Monel, InconelFiller - CAF(360oC), PTFE(260oC),
Graphite(550oC), Ceramic(650oC)
140
PDEC
TUBE BUNDLE RETUBING• More number of tubes plugged • Not possible to clear the tubes• Scaling & poor heat transfer• After average life of the bundle• Frequent failures
141
PDEC
TUBE BUNDLE RETUBING• Full or Partial• WhereAt Bundle Shop or at Position
142
PDEC
THANK YOU
143
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