Design Calculations for Line sizing and pressure drop for Steam Turbine and Process steam lines
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Sanstar Bio-Polymers Ltd
Line sizing calculations
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
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Line sizing calculations
Sanstar Bio-Polymers Ltd
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, c alculation sheet is given below.
Pipe size Working Pressure
Working Temp.above 495 degC(925 degF)
200 NB 68 kg/cm2 g
1.0Pipe Material=
A335 P11
2.0Type/Class of Pipe=
Seamless
3.0Operating Temperature=495 deg c 4.0O.D. of Pipe(
D
)=
925
in Deg.F
8.625
in INCH.
5.0Schdule of pipe selected=
Sch 100
6.0Designated Thickness as per Sch.No. less 12.5 % thickness mill under tolerance
0.594 0.51975
in Inch
Therefore,R/2.7
60000 22222.222
in psi in psi
*Yield Point(Et) Et/R20 ratio at 500 deg c = Et Therefore,Et/1.5
0.23 13800.000 9200.000
in psi in psi
DESIGN DATA: *Min.Tensile strength at room Temp( R ).=
Formula:
allowable working Pr. W=
2fe(t-C)
in psi
D-t+C Allowable Working Pr.in Kg/Cm2 = Actual Working Pressure in Kg/cm2 g=
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76.30284028 68
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Line sizing calculations
Sanstar Bio-Polymers Ltd
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 Steam Temperature Req'd capacity Pipe size Pipe length
68
barg
490
degC
35000
kg/h
202.72
mm
53
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
m
Results Pressure at end of pipe
67.68
bar
Upstream velocity
11.42
m/s
Downstream velocity
11.48
m/s
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Line sizing calculations
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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
250NB
200NB
Turbine MP header
Starch Block
Starch Block
Steam Header (Dryer section)
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
327.6
185.28
4
8
32
24
Eq length
120
72
20% margin
144
86.4
471.6
271.68
0.39
0.39
25
28
9.61
9.22
Size From To Expansion loops
20% margin Additional bends total bends
Total eq length Pr drop Velocity (m/s) Pressure at end point
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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 From To
250NB Turbine DSH/ LP header in Turbine house 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 20% margin
157.5 189
Total eq length
612.6
Pr drop
0.17
Velocity (m/s) Pressure at end point
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18 4.33
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Line sizing calculations
Sanstar Bio-Polymers Ltd
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
300NB
250NB
From
Turbine DSH
To
Starch Block
Starch Block Inlet of 4.5barg PRS
200NB 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
24
29
27
9.68
9.51
9.32
Size
Velocity (m/s) Pressure at end point
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Line sizing calculations
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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
1.2
3.1
65NB
100NB
Steam Header (Dryer section)
Steam Header (Dryer section)
Final evaporators
Jet cooker
2
1
8
4
1
1.3
4
2.6
78
43
82
45.6
98.4
54.72
4
2
12
6
12
9
14.4
10.8
112.8
65.52
115
70
0.3
0.12
19
21
9.02
9.2
Flow TPH Size From To Expansion loops No of bends Loop vertical length Exp. Loop vertical length Actual Pipe length Total pipe length 20% margin Additional bends total bends Eq length 20% factor Total eq length Round off length Pr drop Velocity (m/s) Pressure at end point
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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
40NB LP header in Process
80NB
65NB
80NB
LP header in Process
Near dryers header
Near dryers header
80NB LP header in Process
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 Exp. Loop vertical length
0.8
1.2
1
1.2
1.2
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 Eq length per bend (mtr)
19
6
11
11
11
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
3.93
4.19
3.79
4.06
4.06
Size
From
To
Pressure at end point
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Line sizing calculations
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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
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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 Process LP hdr to DMH dryers HDR
40NB 40NB
4.5 4.5
0.6 0.2
40 40
CS CS
14 183
4 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 LP line near MP Hdr to 2.5barg PRS I/L
80NB 40NB
4.5 4.5
1 0.2
40 40
CS CS
97 15
11 3
2.5barg PRS O/L to Saccfn. HDR
40NB
2.5
0.2
40
CS
5
3
25NB**
2.5
40
CS
75
9
20NB**
2.5
40
CS
30
30
HDR to sacrfn. Tanks I/L
MP lines - Header to equipment I/L MP header to Final evaporators
