steam line sizing calculations

Sanstar Bio-Polymers Ltd Line sizing calculations

Prepared by Forbes Marshall Pvt. Ltd

Design Calculations

for

Line sizing and pressure drop

for Steam Turbine

and

Process steam lines



Contents 1. Steam Turbine Line Design Calculations: ............................................................................................ 3

1.1 HP steam line thickness calculation from boiler outlet to turbine inlet: ................................ 3

1.2 Line sizing and pressure drop calculation: .............................................................................. 4

2. Process steam pressure drop calculations: ......................................................................................... 5

2.1 Pressure drop calculations for external lines ................................................................................ 5

2.2 Pressure drop calculation for MP and LP steam lines inside the process block: .......................... 8

3. Break-up of Piping BOQ: ................................................................................................................... 10

Option 1: ........................................................................................................................................... 10

Option 2: ........................................................................................................................................... 10

Process block distribution lines: ....................................................................................................... 11



1. Steam Turbine Line Design Calculations:

1.1 HP steam line thickness calculation from boiler outlet to turbine inlet:

Steam line from Power boiler outlet to the turbine inlet is a High pressure critical line, for which

thickness calculations are required to be dons as ASME B31.1, calculation sheet is given below.

Pipe size 200 NB Working Temp.above

Working Pressure 68 kg/cm2 g

495 degC(925 degF)

1.0Pipe Material= A335 P11

2.0Type/Class of Pipe= Seamless

3.0Operating Temperature=495 deg c 925 in Deg.F

4.0O.D. of Pipe( D )= 8.625 in INCH.

5.0Schdule of pipe selected= Sch 100

6.0Designated Thickness as per Sch.No. 0.594 in Inch

less 12.5 % thickness mill under tolerance 0.51975

DESIGN DATA:

*Min.Tensile strength at room Temp(R).=

60000 in psi

Therefore,R/2.7 22222.222 in psi

*Yield Point(Et) = Et/R20 ratio at 500 deg c 0.23

Et 13800.000 in psi

Therefore,Et/1.5 9200.000 in psi

Formula: allowable working Pr. W= 2 f e ( t - C ) in psi

D-t+C

Allowable Working Pr.in Kg/Cm2 = 76.30284028

Actual Working Pressure in Kg/cm2 g= 68



1.2 Line sizing and pressure drop calculation:

Line sizing from boiler outlet to turbine inlet is as given below:

8inch line 100SCH

Steam Pressure 68 barg

Steam Temperature 490 degC

Req'd capacity 35000 kg/h

Pipe size 202.72 mm

Pipe length 53 m

No. of gate valves 4

No. of strainers 1

No. of lift check valves 1

No of 90o elbows 8

Equivalent pipe length 188.45 m

Results

Pressure at end of pipe 67.68 bar

Upstream velocity 11.42 m/s

Downstream velocity 11.48 m/s



2. Process steam pressure drop calculations:

Pressure drop and line sizing is done for two options viz. 1)Single extraction turbine, and 2)Extraction

cum back pressure turbine.

Pressure drop calculations for the external lines would vary for each of the case whereas pressure

drop for internal lines will remain the same.

Therefore Calculations are worked out separately for external lines and internal lines i.e. MP and LP

steam lines from turbine house to process block, and Steam distribution from process headers to

individual equipment which are the internal lines.

2.1 Pressure drop calculations for external lines

Option 1: Below given is the pressure drop calculation for external lines and internal lines

considering Extraction cum back pressure turbine with extraction at 10.5barg and backpressure

at 4.5barg pressures.

a. Pressure drop calculation across MP steam line from turbine house to Process

header:

Inlet Pressure Barg 10 9.61

Flow TPH 25 18

Size 250NB 200NB

From

Turbine MP

header Starch Block

To Starch Block

Steam Header

(Dryer section)

Expansion loops 7 4

No of bends 28 16

Loop vertical length 2.5 1.8

Total length for exp. Loops 35 14.4

Actual Pipe length 238 140

Total pipe length 273 154.4

20% margin 327.6 185.28

Additional bends 4 8

total bends 32 24

Eq length 120 72

20% margin 144 86.4

Total eq length 471.6 271.68

Pr drop 0.39 0.39

Velocity (m/s) 25 28

Pressure at end point 9.61 9.22



b. Pressure drop calculations across LP steam line from LP header in Turbine house to

LP header at the process block:

Pressure Barg 4.5

Flow TPH 10

Size 250NB

From Turbine DSH/ LP header in Turbine house

To LP header in Process

Expansion loops 9

No of bends 36

Loop vertical length 2.5

Exp. Loop vertical length 45

Actual Pipe length 308

Total pipe length 353

20% margin 423.6

Additional bends 6

total bends 42

Eq length 157.5

20% margin 189

Total eq length 612.6

Pr drop 0.17

Velocity (m/s) 18

Pressure at end point 4.33



Option 2: Below given are the pressure drop calculations for main lines considering single

extraction turbine with extraction at 10.5barg pressure

a. Pressure drop calculation across MP steam line from turbine house to steam header

at the process block:

Pressure Barg 10 9.68 9.51

Flow TPH 35 28 18

Size 300NB 250NB 200NB

From Turbine DSH Starch Block

Inlet of

4.5barg PRS

To Starch Block

Inlet of

4.5barg PRS

Steam Header

(Dryer section)

Expansion loops 7 2 2

No of bends 28 8 8

Loop vertical length 3 2.5 1.8

Exp. Loop vertical length 42 10 7.2

Actual Pipe length 238 70 70

Total pipe length 280 80 77.2

20% margin 336 96 92.64

Additional bends 4 6 2

total bends 32 14 10

Eq length 144 52.5 30

20% margin 172.8 63 36

Total eq length 508.8 159 128.64

Round off length 510 160 130

Pr drop 0.32 0.17 0.19

Velocity (m/s) 24 29 27

Pressure at end point 9.68 9.51 9.32



2.2 Pressure drop calculation for MP and LP steam lines inside the process

block:

a. Pressure drop calculations for MP steam lines

Pressure Barg 9.32 9.32

Flow TPH 1.2 3.1

Size 65NB 100NB

From Steam Header

(Dryer section)

Steam Header

(Dryer section)

To Final evaporators Jet cooker

Expansion loops 2 1

No of bends 8 4

Loop vertical length 1 1.3

Exp. Loop vertical length 4 2.6

Actual Pipe length 78 43

Total pipe length 82 45.6

20% margin 98.4 54.72

Additional bends 4 2

total bends 12 6

Eq length 12 9

20% factor 14.4 10.8

Total eq length 112.8 65.52

Round off length 115 70

Pr drop 0.3 0.12

Velocity (m/s) 19 21

Pressure at end point 9.02 9.2



b. Pressure drop calculations for LP steam lines inside process block

Pressure Barg 4.33 4.33 4.19 4.19 4.33

Flow TPH 0.2 1.2 1 1 1.4

Size 40NB 80NB 65NB 80NB 80NB

From

LP header

in

Process

LP header in

Process

Near

dryers header

Near

dryers header

LP header

in

Process

To

DMH

dryers

Near

dryers

header

Steeping

section

Steeping

section

Hydrocyclo

ne

Expansion loops 4 1 2 2 2

No of bends 16 4 8 8 8

Loop vertical length 0.8 1.2 1 1.2 1.2

Exp. Loop vertical

length 6.4 2.4 4 4.8 4.8

Actual Pipe length 146 58 76 76 74

Total pipe length 152.4 60.4 80 80.8 78.8

20% margin 182.88 72.48 96 96.96 94.56

Additional bends 3 2 3 3 3

total bends 19 6 11 11 11

Eq length per bend

(mtr) 0.6 1.2 1 1.2 1.2

Eq length 11.4 7.2 11 13.2 13.2

20% factor 13.68 8.64 13.2 15.84 15.84

Total eq length 196.56 81.12 109.2 112.8 110.4

Round off length 215 90 110 115 115

Pr drop 0.4 0.14 0.4 0.13 0.27

Velocity (m/s) 17 21 31 18 28

Pressure at end point 3.93 4.19 3.79 4.06 4.06



3. Break-up of Piping BOQ:

Option 1:

Descripton Size Pressure Flow Sch Material Pipe length Bends

Boiler to turbine inlet 200NB 68 35 100 P11 46 8

Boiler to bypass pRS inlet 200NB 68 35 100 P11 23 8

bypass Prs O/L to DSH I/L 300NB 10.5 35 40 CS 23 8

Turbine exhaust to DSH I/L 250NB 10.5 25 40 P11 23 8

MP DSH Outlet to MP header 250NB 10.5 35 40 CS 5 3

MP header to LP PRS I/L 150NB 10.5 10 40 CS 10 3

Turbine exhaust to

DSH I/L to LP header 250NB 4.5 10 40 CS 23 8

LP header(turbine) to LP

header (process) 250NB 4.5 10 40 CS 423.6 42

MP Header (turbine) to

Starch Block 250NB 10.5 25 40 CS 327.6 32

Starch block to MP

header(Process) 200NB 10.5 17.5 40 CS 185.28 24

MP header(turbine) 350NB 10.5

40 CS 5

LP header(turbine) 300NB 4.5

40 CS 5

Option 2:

Descripton Size Pressure Flow Sch Material Pipe length Bends

Boiler to turbine inlet 200NB 68 35 100 P11 46 8

Boiler to bypass pRS inlet 200Nb 68 35 100 P11 23 8

bypass Prs O/L to DSH I/L 300NB 10.5 35 40 CS 23 8

Turbine exhaust to DSH I/L 300NB 10.5 35 40 CS 23 8

DSH O/L to DA I/L 100NB 10.5 5 40 CS 37 8

Main line to LP PRS 150NB 10.5 10 40 CS 10 3

DSH O/L to Process(Starch block) 300NB 10.5 35 40 CS 336 32

Starch Block to MP header 250NB 10.5 28 40 CS 96 14



Process block distribution lines:

LP Lines - header to equipment I/L

Process LP hdr to Hydro cyclone 80NB 4.5 1.4 40 CS 95 11

Process LP Hdr to LG evaporator 100NB 4.5 4.7 40 CS 14 4

Process LP Hdr to DMH and DAH evaporator 40NB 4.5 1.6 40 CS 28 8

Process LP Hdr to LG batch evap 40NB 4.5 0.6 40 CS 14 4

Process LP hdr to DMH dryers HDR 40NB 4.5 0.2 40 CS 183 19

DMH HDR to I/L 25NB 4.5 0.1 40 CS 30 6

Process LP hdr to Near MP Hdr 80NB 4.5 1.2 40 CS 72 6

LP line near MP Hdr to Steeping tanks 80NB 4.5 1 40 CS 97 11

LP line near MP Hdr to 2.5barg PRS I/L 40NB 4.5 0.2 40 CS 15 3

2.5barg PRS O/L to Saccfn. HDR 40NB 2.5 0.2 40 CS 5 3

HDR to sacrfn. Tanks I/L

25NB** 2.5 40 CS 75 9

20NB** 2.5 40 CS 30 30

MP lines - Header to equipment I/L

MP header to Final evaporators 65NB 10.5 1.2 40 CS 98 12

MP header to Jet Cooker 100NB 10.5 3.1 40 CS 55 6

MP header to rotary dryers I/L 80NB 10.5 40 CS 25 15

LP headers

LP header(Evaporator) 300NB 4.5 40 CS 7

LP header(DMH) 50NB 4.5 40 CS 5

MP headers

MP header(Dryer section) 250NB 10.5 40 CS 7

MP header(Final evap) 80NB 10.5 40 CS 5

MP header(Starch dryers) 150NB 10.5 40 CS 5

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steam line sizing calculations

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