Design of Dehydrator
Transcript of Design of Dehydrator
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Dehydration design:
Gas production rate = 250 MMscfd = 7.078 Msd
Operating Pressure = 1000 psig = 1014.7 psia = 6997.93 Kpa
Container maximum working pressure = 1500 psig = 1514.7 psia = 10344.82 Kpa
Gas inlet temperature = 100 = 37.78 = 560° = 310.78°
Given sample of gas is:
S.no Compound Mole fraction Molecular Mass Kg/Kg-mol
Of mixture
1 C1 89.470 16.043 14.35367
2 C2 6.0664 30.070 1.824166
3 C3 2.7386 44.097 1.20764
4 iC4 0.1000 58.124 0.0581245 nC4 0.1200 58.124 0.069749
6 iC5 0.0769 72.150 0.055483
7 nC5 0.0081 72.150 0.005844
8 N2 0.0000 28.013 0
9 CO2 1.4200 44.010 0.624942
Total Total 10018.19962
Hence
Now we need to calculate Z
Calculations for Pseudo-critical Temperature and Pressure: By using the correlations we get:
Or
Or
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Pseudo-reduce Temperature and Pressures are calculated as:
Now,
= 0.9790
From Standing & Katz chart we will calculate Z-factor as 0.88
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Optimized required Dehydration rate = 95% (Based on economical aspects)
Glycol to water circulation rate = 5.5 gal TEG/ lb = 45.89 litres TEG/Kg
Lean Glycol concentration = 99.5
Water content specification is 7 lb = 112.13 mg
From figure 20-4 (GPSA) @ 6997.93 Kpa, dew point is -3, 970 mg
Now, Water removal efficiency is given as
= 88.44%
This value is less than our required Removal efficiency of 95%.
Hence we proceed as follows
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From figure 20-70, numbers of theoretical stages are calculated as
Given: 45.89 litres TEG/Kg & Lean Glycol concentration = 99.5%
This gives:
Required water removal efficiency is 95% which is greater than 94.5%, hence numbers of
required stages are more than 1.5
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From figure 20-71 GPSA
This gives:
Required water removal efficiency is 95% which is lesser than 96.5%, hence numbers of
required stages are 2.
2 trays = 8 bubble cap trays @ 0.6 m tray spacing or is equal to 3 m of structural packing.
(From table 20-75 GPSA)
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For size of contactor:
From table 20-75 GPSA
C = 176
For TEG = 1119.7 (From table 20-56 GPSA)
Now,
H
M=
Now, Area (A) = M/G =/31032.23 = 7.3138
Hence we get diameter = 3.052 m
For structured packing:
From table 20-75 (GPSA)
C structured packing = 384 (Taking average value of 329 and 439)
D = *(D bubble cap)
= *3.052 = 2.066 m.