Good morning!
I am simulating a small gas treating plant, for the purposes of throughput increase, that is used to cool and compress a low-pressure mixture of gases (we use HYSYS and PIPEPHASE). This gas is casing vapor (casing gas) from oil wells. A typical dry gas analysis (60° F, 0 psig) is (mole fraction):
CO2 0.55
O2 small, 0.05 or so but can be as high as 0.1 or 0.15
N2 small, 0.05 or so
H2 small, 0.05 or so
H2S 0.02 or so
C1 0.35
C2-C6+ remainder
At process conditions of 230° F and 2-3 psig, at the plant inlet, the analysis is:
H20 ±0.85
The rest is normalized from the above analysis.
I have tried PR, SRK, and CS, among others, in my simulator and I can't get a decent phase envelope. Not even close. It is nowhere close to reality in predicting the phase equilibria at process conditions. The process consists of cooling the gas in a shell-and-tube to about 205° F and then secondary cooling in a fin-fan to about 130° F or so before subsequent compression to about 10 psig.
What brought this all up is - we can't get the simulator to match the exchanger duties we measure in the plant. They are off by at least 30%. I can make 'adjustments' to the simulator to make it match but that is not good practice and will not provide a general solution, and I need a general solution.
Do any of you have any experience with low-pressure mixtures of polar and non-polar gase like this? Which EOS have you used? Any other thoughts or recommendations?
Thanks ! ! ! ! ! ! ! ! Thanks!
Pete
P. J. (Pete) Chandler, PE
Mechanical, Piping, Thermal, Hydraulics
Processes Unlimited International, Inc.
Bakersfield, California USA
pjchandl@prou.com
I am simulating a small gas treating plant, for the purposes of throughput increase, that is used to cool and compress a low-pressure mixture of gases (we use HYSYS and PIPEPHASE). This gas is casing vapor (casing gas) from oil wells. A typical dry gas analysis (60° F, 0 psig) is (mole fraction):
CO2 0.55
O2 small, 0.05 or so but can be as high as 0.1 or 0.15
N2 small, 0.05 or so
H2 small, 0.05 or so
H2S 0.02 or so
C1 0.35
C2-C6+ remainder
At process conditions of 230° F and 2-3 psig, at the plant inlet, the analysis is:
H20 ±0.85
The rest is normalized from the above analysis.
I have tried PR, SRK, and CS, among others, in my simulator and I can't get a decent phase envelope. Not even close. It is nowhere close to reality in predicting the phase equilibria at process conditions. The process consists of cooling the gas in a shell-and-tube to about 205° F and then secondary cooling in a fin-fan to about 130° F or so before subsequent compression to about 10 psig.
What brought this all up is - we can't get the simulator to match the exchanger duties we measure in the plant. They are off by at least 30%. I can make 'adjustments' to the simulator to make it match but that is not good practice and will not provide a general solution, and I need a general solution.
Do any of you have any experience with low-pressure mixtures of polar and non-polar gase like this? Which EOS have you used? Any other thoughts or recommendations?
Thanks ! ! ! ! ! ! ! ! Thanks!
Pete
P. J. (Pete) Chandler, PE
Mechanical, Piping, Thermal, Hydraulics
Processes Unlimited International, Inc.
Bakersfield, California USA
pjchandl@prou.com
