Heat Exchangers

By: Baher EL ShaikhBy: Baher EL ShaikhMechanical EngineerMechanical Engineer

EMetahnexEMetahnex

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Shell and tube heat exchangers are one of the most common equipment found in all plants

How it works?

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Heat Exchanger

Cooler

Heater

Condenser

Reboiler

Both sides single phase and process stream

One stream process fluid and the other cooling water or air

One stream process fluid and heating utility as steam

One stream condensing vapor and the other cooling water or air

One stream bottom stream from a distillation column and the other a hot utilityor process stream

Classification according to service .

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Code

Standard

Specifications

Is recommended method of doing something

ASME BPV – TEMA

is the degree of excellence requiredAPI 660-ASME B16.5–ASME B36.10M–ASME B36.19-ASME B16.9–ASME B16.11

Is a detailed description of construction, materials,… etc Contractor or Owner specifications

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2- Channel3- Channel Flange4- Pass Partition5- Stationary Tubesheet6- Shell Flange7- Tube

8- Shell9- Baffles 10- Floating Head backing Device11- Floating Tubesheet12- Floating Head13- Floating Head Flange14 –Shell Cover

1- Channel Cover

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Front Head TypeFront Head Type

A - Type B - Type C - Type

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Shell TypeShell Type

E - Type F - Type

J - TypeK - Type

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Rear End Head TypesRear End Head Types

M - Type S - Type T - TypeFixed Tubesheet Floating Head Pull-Through

Floating Head

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U-Tube Heat ExchangerU-Tube Heat Exchanger

Fixed Tubesheet Heat ExchangerFixed Tubesheet Heat Exchanger

Floating Tubesheet Heat exchangerFloating Tubesheet Heat exchanger

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AES

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Terminology Design data

Material selection

Codes overview

Sample calculations

Hydrostatic test

Sample drawing

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ASME : American Society of Mechanical Engineers

TEMA : Tubular Exchanger Manufacturer Association

API : American Petroleum Institute

MAWP : Maximum Allowable Working Pressure

MDMT : Minimum Design Metal Temperature

PWHT : Post Weld Heat Treatment

NPS – DN – NB – NPT Sch - BWG

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Heat Exchanger Data Sheet :

Design pressure

Design temperature

Dimensions / passes Tubes ( dimensions, pattern) Nozzles & Connections

TEMA type

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Baffles (No. & Type)

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A – Yield StrengthA – Yield Strength

B – Tensile StrengthB – Tensile Strength

C – Rupture C – Rupture pointpoint

AB

C

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Creep Strength a slow plastic strain increased by time and temperature

(time and temperature dependant) for stressed materials

Fatigue Strength The term “fatigue” refers to the situation where a

specimen breaks under a load that it has previously withstood for a length of time

Toughness The materials capacity to absorb energy, which, is

dependant upon strength as well as ductility

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ASME code OverviewASME code Overview

ASME BPV code

Sec.I Power Boilers

Sec.II Materials

Sec.III Nuclear Fuel Containers

Sec.IV Heating Boilers

Sec. V Non Destructive Examination

Sec. VI Operation of heating boilers

Sec. VII Operation of power boilers

Sec. VIII Pressure vessels

Sec. IX Welding and Brazing

Sec. X Fiber-Reinforced plastic PV

Sec. XI Inspection of nuclear power plant

Sec. XII Transport tanks

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ASME code overviewASME code overview Sec. II: Materials

Part A : Ferrous material specifications

Part B : Non-Ferrous material specifications

Part C : Specifications of welding rods, electrodes and filler metals

Part D : Properties

Sec. VIII: Rules of construction of pressure vessels

Division 1 : 3 Subsections + mandatory Annex + non mandatory Annex

Division 2: Alternative rules

Division 3 : Alternative rules of high pressure

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ASME code overviewASME code overview

TEMA code overviewTEMA code overview TEMA classes:

Class R: Generally severe requirements for petroleum

and related processing applications

Class C: Generally moderate requirements of commercialand general processing applications

Class B: Chemical Process service

TEMA subsections 10 subsection

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Sample CalculationsSample Calculations Shell thickness calculations under Internal Pressure:

t : Min. Required Shell Thickness P : Design Pressure of Shell Side S: Max. Allowable Stress of Shell Material R: Shell Inside Radius (corroded conditions) E : Joint Efficiency CA: Corrosion Allowance UT: Under Tolerance (if applicable)

PR .SE – 0.6 P

+ CAt = + UT

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Sample CalculationsSample Calculations Channel thickness calculations under Internal Pressure:

t : Min. Required Channel Thickness P : Design Pressure of Tube Side S: Max. Allowable Stress of Channel Material R: Channel Inside Radius (corroded conditions) E : Joint Efficiency CA: Corrosion Allowance UT: Under Tolerance (if applicable)

PR .SE – 0.6 P

+ CAt = + UT

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Sample CalculationsSample Calculations Body Flanges:

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Sample CalculationsSample Calculations Body Flanges:

Trial and error calculations Gasket seating conditions

No. of bolts and size Bolt circle diameter Inside and outside diameters

Check min. and max. bolt spacing

Detailed analysis of the flange Forces calculations Moment calculations Stresses calculations

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Operating conditions

Sample CalculationsSample Calculations Precautions in body flanges design and installations:

Pairs of flanges Bolt holes shall straddle center line

Corrosion Allowance

Bolts shall be multiple of 4

Bolting shall be allowed to be removed from either side

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Calculated thickness not include the RF

Cladding

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Sample CalculationsSample Calculations Nozzles and standard flanges:

Flange Rating (ASME B16.5)

Nozzle neck thickness calculations

Area replacement calculations

Impingement protection

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Sample CalculationsSample CalculationsTubesheet:

• Tubesheet is the principal barrier between shell side and tube side

• Tubes shall be uniformly distributed

• Tubesheet thickness shall be designed for both sides

• Tubesheet shall be designed for bending stresses and shear stresses

• Corrosion allowance

• Made from around flat piece of metal with holes drilled for the tubes

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Sample CalculationsSample CalculationsTubesheet:

• Tubesheet thickness for bending

T: Effective tubesheet thickness

S: Allowable stress

P: Design pressure corrected for vacuum if applicable at the other side

η: Ligament efficiency

For Square pattern

For Triangular pattern

G: Gasket effective diameter

F: Factor

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Sample CalculationsSample CalculationsTubesheet:

• Tubesheet thickness for Shear:

T: Effective tubesheet thickness

DL: Effective diameter of the tube center parameter DL=4A/C

C: Perimeter of the tube layout A: Total area enclosed by the Perimeter C

P: Design pressure

S: Allowable stress

do: Outside tube diameter

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Tube-to-Tubesheet Tube-to-Tubesheet jointjointExpanded

Seal welded

Strength welded

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Hydrostatic TestHydrostatic Test

Test pressure : 1.3 X MAWP

Test Procedure

Gasket change

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Sample drawingSample drawing

Construction drawing is the design output

Sample drawing 1 Sample drawing 2

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Baher EL [email protected]