Shell & Tube Heat Exchanger

Page 1 of 10

JACOBS H&G

QUALITY WORK INSTRUCTION

SHELL & TUBE HEAT EXCHANGER DESIGN BY USING HTRI PACKAGE

DOCUMENT NO:

P WI 05

PREVIOUS DOC No:

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Rev No.

Issue Date

Pages

Rev Description

Prepared By

Checked By

Approved By

A

25th April 2004

10 + 2 Annex.

For Comments

SPP

RGP

VVD

0

1st June 2004

10 + 2 Annex.

Issue for use

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VVD

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03/02/03; 5:53 A11/P11

TABLE OF CONTENTS 1.0

PURPOSE

2.0

SCOPE

3.0

DEFINITIONS

4.0

METHOD (PROCEDURE) 4.1 4.2 4.3 4.4 4.5 4.6

GENERAL FORMAT CONTENT VALIDATED SOFTWARE CHECKING AND APPROVAL ISSUING, FILING, AND STORAGE

5.0

RELATED DOCUMENTATION (REFERENCES)

6.0

RECORDS

7.0

ATTACHMENTS/APPENDICES

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JACOBS H&G LTD DATE: 01 June 2004 PAGE: 3 of 10 REVISION NO: 0

1.0

QUALITY WORK INSTRUCTION

SHELL & TUBE HEAT EXCHANGER DESIGN BY HTRI PACKAGE

PURPOSE The purpose of this procedure is to define the workflow, format, and procedure of Shell & Tube Heat exchanger Design by using HTRI Package.

2.0

SCOPE This procedure applies to all Shell & Tube Heat Exchangers performed by the Process Department.

3.0

DEFINITIONS none.

4.0

METHOD (PROCEDURE) 4.1

GENERAL It is the responsibility of the individual to design Shell & Tube Type heat Exchanger in accordance with this procedure.

4.2

FORMAT None.

4.3 CONTENT Shell & tube Heat exchanger Design steps

Input all data, which is required for heat exchanger design. 4.3.1) Process Parameters Input Flow rate, Temperature & Vapor fraction at Inlet/Outlet condition. Input Allowed Pressure drop for shell & tube side. For liquid vapor fraction is "0", for gas it is "1" & for two phase it is in between 0 & 1. 4.3.2)

Geometry Input following configuration TEMA type

Hot fluid side

As per given in Data sheet(If not given then it depend upon Fluid type, condition etc.) Orientation may be Horizontal, Vertical or Inclined with some Angle in between 0 to 90 Deg. Either Shell side or Tube side.

Tube type

Plane or finned.(for shell & tube generally plane tubes are used )

Tube length

In design mode you can enter length & design exchanger

Orientation

for various shell ID, Tube length, Pitch. In FPS Units 4,6,8,10,12,14,16,18,20,22,24 ft. are std.Tube length /var/www/apps/conversion/tmp/scratch_7/293923885.docx07/11/15

are used. In MKS unit we can use tube length with step of 500 mm. Some times we suppose to use FPS std.Tube in MKS unit. (i.e. 6096 mm,3048 mm etc.) For small exchangers we can use tube of 1000 mm length also. Effective Tube length

This item need not be input.HTRI calculate tube sheet thickness & Calculate effective tube length Tube length, which is used for heat transfer. (Total tube length - Tube sheet thickness - Tube projection)

Surface area Gross

Total installed area. ( no of tubes x total tube length x PI x Tube OD) Surface area Effective Total installed area. ( no of tubes x Effective Tube length x PI x Tube OD) Shell ID

In design mode this input is not required. HTRI will calculate. IF you want to design exchanger for fixed Shell ID then input ID. IF you want to design exchanger from 'xx' mm to 'xx' mm shell ID IF you want to design exchanger from 'xx' mm to 'xx' mm Tube Length IF you want to design exchanger for Single or double segmental baffle or NTIW Design. IF you want to design exchanger Various Tube OD or Various Tube Pitch IF you want to design exchanger Various TEMA Type Shell (i.e. F shell,J-shell,Floating head etc.) then We can enter All these option in Grid design.

Tube OD

Generally 19.05,25.4,31.75,38.1,50.1 mm

Tube Pitch

Generally 1.25 times tube OD

Tube layout

30,60,45,90

Flow Direction

Flow Direction 30 O Layout Tube passes Tube count Tube material Baffle type Baffle cut

Flow Direction

60 O Layout

Flow Direction 90 O Layout

45 O Layout

For design case not required. (for floating head even no of passes, for U-tube 2,4,6,8 etc.) For design case not required. Select from HTRI data bank For design case not required.(Single,Double,NTIW,None,Rod) For design case not required.(Vertical & Horizontal) Baffle cut is with respect to shell inlet nozzle axis.(i.e. if baffle cut is perpendicular to nozzle axis then cut is horizontal and if cut is parallel to nozzle axis then it is vertical cut)

Baffle spacing

For design case not required.

Parallel pass lane Perpendicular pass lane

For design case not required.(Refer HTRI help) For design case not required.(Refer HTRI help)

JACOBS H&G LTD DATE: 01 June 2004 PAGE: 5 of 10 REVISION NO: 0

Sealing strips

QUALITY WORK INSTRUCTION

SHELL & TUBE HEAT EXCHANGER DESIGN BY HTRI PACKAGE

For design case not required.(Refer HTRI help) Sealing strips reduces leakage in bundle & shell, which Increases cross flow fraction.

Shell side inlet / outlet nozzle Std., Schedule,Nos,ID,Type,Position

For design case not required.

Tube side inlet / outlet nozzle Std., Schedule,Nos,ID,Type,Position

For design case not required.

Impingement plate For design case not required. If Shell side nozzle inlet / outlet RV2 is more than allowed limit then HTRI will consider Impingement plate. For gas & two phase flow Imp. Plate is required, For Liquid Phase it depends on RV2.Generally rectangular Imp. plate are used for Exchanger. There is some optional data, which is not required for design purpose. But this data Should be corrected at the time of rating & fine-tuning, which is given below. Total tube sheet thickness, Floating head support plate, Support at U-bend, Design temperature & pressure etc. 4.3.3)

Piping

4.3.4)

Process Exchanger Duty Duty Multiplier Fouling resistance

4.3.5)

4.3.6)

Enter Actual exchanger duty. if 10% Over design on duty then you have to enter 1.1. Input, which is given in data sheet. If not given in data sheet then use process heat transfer by D.Q.Kern for guidance.

Physical properties for Hot & Cold fluid Physical properties input Three options are available, first is mixture property via grid, Second is component by component, Third is Grid & Component. Heat release curve

Three options are available, first is user specified, Second is Specified dew/bubble point, Third is programmed calculated.

Composition units

Moles, mass

Flash type

Differential (Separate & not in contact), Integral (Well mixed and in thermal & chemical equilibrium)

Design Geometry a)Shell ID b)Baffle spacing c)Tube passes d)Tube length

You have to enter minimum, maximum Shell ID and no of steps in nos or step size in mm or Inch. You have to enter minimum, maximum baffle spacing and no of steps in nos or step size in mm or Inch. You have to enter minimum, maximum no of passes and odd or even nos. You have to enter minimum, maximum tube length and no of steps in nos or step size in mm or Inch.

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f)Tube Diameter

g)Shell type

Duty (MM

Over Design % Total Area (m2)

Baffle Type

Sng. Seg. Sng. Seg.

E

10

1.3000

20.000

4

4999.9

464.522

1219.20

1

3

1.632

0.836

4.50

17.76

1001.62

1466.41

E

12

1.3000

20.000

2

5999.9

477.573

863.602

1

3

1.085

1.402

6.06

19.15

1063.00

1975.51

378.15

Here you can give name of client, Exchanger, Project No. etc. Here you can give case description (Design case, Rating Case, With ___ Length, With ____ Shell Type etc.) 46.7

12.8518

751.001

1.58

Warnings You can give warnings as given In HTRI Constraints,options,warnings are not required for simple design. Control Name Case

Sng. Seg.

2

E

1.3000

20.000

2

1000.0

1524.00

1

9

0.497

0.820

5.45

2.48

398.42

1144.24

59.0

201.06 345.75

12.8518

1349.65

45.7

12.8518

1319.87

1.66 61.50

Options

You can give constraints of Hot fluid velocity, cold fluid velocity, Pressure drop etc. You can give options as given In HTRI Program.

8999.9

20.000

1.3000

16

E

Sng. Seg.

5999.9

20.000

1.3000

12

E

Sng. Seg.

814.16 2280.81

542.577

1277.88 2028.59

477.573

304.86 499.95

1371.60

46.2 50.0

863.602

12.8518 12.8518

Methods,Safety,User defined methods,Vibration,F & J curve etc are not required for Simple design. 3158.81

1.511

3

1.643

3

4

0.877 1.197

1

3.45

13.66

5.17

Design & rating Once you enter all above Data you can run case by claiking run option on tool bar. Programme gives various designs for given options. Typical design table is given below

17.69

2

Selection of optimum design from various design reported by HTRI. 1

4.3.9)

Constraints

779.736

4.3.8)

HTRI gives various design with different shell ID with optimum baffle spacing for given various tube length & tube passes. HTRI gives shell ID in STD. Inch format. We are suppose to fine-tune for nearest round number which is divisible by 5 in Rating mode. We are varying only Tube length, No of passes in design mode. For special case you can very all other parameters.

240.42

4.3.7)

In Design mode we are not varying Shell ID,Baffle spacing, Pitch ratio, Shell type, Baffle type.

49.41

Xist Rating 1 Shortcut Design 18 Shortcut Design 11 Shortcut Design 10 Shortcut Design 1

Case

h)Baffle type

U Shell h (kcal/m2Tube h (kcal/m2Shell Velocity Tube Velocity Shell DP (kgf/cm2) Tube DP (kgf/cm2) Shells In Series Shells In Parallel Shell ID (mm) Baffle Spacing Tube Passes Tube Length Tube Dia. (mm) Tube Pitch CrossPas ses ShellType

You have to enter minimum, maximum pitch ratio and no of steps in nos or step size in mm or Inch. 1.25 or 1.3 times tube OD are standard pitch ratios. You have to enter minimum, maximum tube diameter and no of steps in nos or step size in mm or Inch. 19.05,25.4,31.75,38.1,50.1 mm are standard tube OD's All TEMA shell type. TEMA E,F,G,H,J12,J21,X,K type shell Single,Double,NTIW,None,Rod EMTD (C)

e)Pitch ratio

Take printout of various designs. Analyze and evaluate % over design, Pressure drop, No of Shell in series, No of shell in parallel, Area, H.T. Coefficient, Velocity etc. Select one case for rating. Select Optimum case from various design & Click right button of mouse and save input as rating file with different file name. Open rating file and run case again. Analyze result for Pressure drop, Over design, Warnings, H.T.Coefficient etc. If Over design is more then 5.0 %( Our standard) you can reduce tube no’s, or tube length. Check Flow fractions. a)Try to increase B-stream flow fraction and minimize leakage stream flow fractions. In actual practice, it is not possible or necessarily desirable to eliminate leakage streams completely because clearances are required to construct the heat exchanger. B-stream fraction

JACOBS H&G LTD DATE: 01 June 2004 PAGE: 7 of 10 REVISION NO: 0

QUALITY WORK INSTRUCTION

SHELL & TUBE HEAT EXCHANGER DESIGN BY HTRI PACKAGE

should be more than 40 %.(for viscous fluid it less & Shell side condensing fluid it is less) B-stream can be increased by increasing baffle cut, Reducing no of baffles, and also reducing other leakages. b)The magnitude of the tube-to-baffle clearance affects the size of the "A" leakage stream. Because the "A" stream is thermally effective, a significant "A" stream does not have a large negative impact on thermal performance of the exchanger. c)C-stream bypassing can result because of bundle to shell clearance, which can be reduced by using sealing strips. For floating head exchanger this stream is on higher side which can be reduced up to some extent by using sealing strIps.HTRI calculate sealing strip pairs, but you can use one pair for every 5 tube rows which are in overlap region. d)"E" stream is not thermally effective, a large "E" stream has a large negative impact on the Exchanger’s thermal performance."E"stream is because of baffle to shell clearance. HTRI uses TEMA Std.You can vary This clearance with the help of fabricator advise. e)The F stream travels along tube pass partition lanes. Because these bypass streams can affect heat transfer and pressure drop performance, they must be modeled accurately. Thus, usually you do not run a case with these streams blocked. HTRI block this stream by using seal rod of same OD of tube or smaller OD. 4.3.10)

Tips to decide optimum & good design of Shell & Tube Heat exchanger a)Find out which coefficient is governing. If shell side coefficient is governing then check All DP is used or not. If all DP is not used then increase no of baffles or reduce Baffle cut. If DP is Higher than allowed then reduce no of baffles or increase Baffle cut. Some time you can go for Double segmental Baffle for very low DP in shell side. b)When you are specifying no of baffles ensure shell side Inlet / Outlet nozzle location. if you want shell side nozzle on opposite side then no of baffle cross passes are odd. c)Generally for horizontal shell nozzles are on opposite side. For vertical shell Nozzle can be on opposite side or same side. d)Inlet / Outlet Baffle spacing is dependent on nozzle ID.Baffle should not foul nozzle. Generally Inlet / Outlet spacing is Equal to or More than Mid Baffle Spacing. Try to set baffle spacing divisible by 5 mm in MKS unit or 1 Inch in FPS units. Check % Contribution of DP in Nozzle, Cross Flow. If DP In nozzle is high then go for Higher nozzle size. e)If shell side coefficient is very low you can increase it by using fin tube, but shell side fluid should be very clean.(Special Design) f)If tube side coefficient is governing then check All DP is used or not. If all DP is not used then increase tube length & reduce no of tubes at the same time by kipping same H.T.area. If all DP is not used & actual DP is very less then increase tube passes. You can go for smaller tube OD but you have to run Design mode again with two different tube OD & fine-tune. g)For single phase on shell side you can use vertical as well as horizontal cut baffles. For two phase flow on shell side mostly use vertical cut baffles. some time you can use horizontal baffles with cutout at bottom. h)Nozzle orientation should be such that we get counter current flow in 1st tube pass. i)U-tube exchanger is cheaper because only one tube sheet is required. (for U-tube type exchanger Tube side cleaning is not possible.) j)Specify Location of nozzle at U-bend for U-tube Exchanger. Options are At U-bend, Before U-bend & After U-bend.

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k)Specify Shell inlet nozzle Location.(Options are-Programme decides,top,bottom or side.) l)NTIW type baffle will eliminate vibration problem but it increases shell ID. By using intermediate support in between two baffles we can eliminate vibrations. When you are designing NTIW design keep watch on window velocity. It should be as per HTRI guidelines. Generally you can't use intermediate support for single or double segmented baffle. m)For U-tube exchanger generally bend radius is 2 times tube OD.HTRI is considering 1.5 times tube OD. We are supposed to enter Pass lane manually. n)If there are more shell in series then at the time of rating & fine tuning you should input shell side inlet/outlet nozzle location for each shell.(i.e.at top or bottom, at front end or rear end) o)You can use different geometry for shells in series. 4.3.11)

Procedure for preparing Shell & Tube heat exchanger process data sheet First copy standard Shell & Tube Heat exchanger process data sheet from standard format. a) Read following points when updating standard process data sheet. a1) Marked cells to be checked / rewritten / deleted as per requirement. b1) Please note that for fixed tube-sheet exchanger mean metal temperature to be given for various conditions as in sheet-4. c1) Copy Tube Layout from HTRI output on sheet-6. d1) When Shells in series are more than one, then we are supposed to give detailed Interconnection drawing on separate sheet.(sheet-3) e1) When Shells in series are more than one & MOC for Tubes & Shells are different for different shells then give table for MOC.( sheet-3 ) f1) If we require Duty or Flow margin then we are supposed to specify in remark. G1) For double segmented baffle there is no provision to specify cut for inner baffle & outer baffle. We suppose to include this point in to remarks. h1) There is no provision in HTRI to specify whether Exchanger is IBR approved or not. We suppose to include this point in remarks. b)Copy from TEMA-1 Sheet from Row -9 to Row-58 & Paste only the Values at location given in standard data sheet.(Sheet-2) c)Copy Sketch of Individual shell from individual & connect to each other.(Sheet-3) Please check inlet & outlet nozzle location are correctly shown for shell side & Tube side. This sheet is required when there are more than one shells in series or parallel. In Design pressure, Design temperature, Material of construction are different for different shell then Specify in Sheet-3. d)Mean Metal Temperature : This is required For Fixed Tube Sheet Exchangers Only. If no of shells in series are more than one then we are supposed to specify mean metal temperature for All shell's. Specify Nozzle schedule in Sheet-4. e)Draw sketch of reboiler & piping details in Sheet-5. Sheet-5 is required when Exchanger is reboiler & piping details are required to ensure pressure drop in inlet / outlet Piping. f)Copy Tube layout from HTRI Output (Drawing-Tube layout) & paste in Sheet-6. If tube layout is not fitting width wise then reduce size of tube layout by changing object size. Remove Shell side nozzle ID from tube layout. We are specifying nozzle schedule in Sheet-4. g)Delete Sheets & data depending on type of exchanger. 4.4

SOFTWARE

JACOBS H&G LTD DATE: 01 June 2004 PAGE: 9 of 10 REVISION NO: 0

QUALITY WORK INSTRUCTION

SHELL & TUBE HEAT EXCHANGER DESIGN BY HTRI PACKAGE

This work instruction is prepared for Shell & Tube type Heat exchanger by using HTRI package. 4.5

CHECKING AND APPROVAL None.

4.6

ISSUING, FILING, AND STORAGE None.

5.0

RELATED DOCUMENTATION (REFERENCES) None.

6.0

RECORDS Calculation no to be given to Shell & Tube Heat Exchanger Design.

7.0

ATTACHMENTS / APPENDICES

7.1 Standard Process data sheet for Shell & tube heat exchanger.

"Standard Data Sheet For Shell & Tube Heat Exchanger.xls "

7.2 Scanned drawings from HTRI Help file.

Shell & Tube Exchanger Drawings .pdf

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