What is the best method for return pure hydrogen from H.P off gas of hydrocracker unit to input of this unit (pure H2 gas)?
Do you think the membranes system is the best and economic for this application?
Answers
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06/12/2007
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Roger Haglund, Eprom, r_haglund44@hotmail.com
Many installations are using PSA for recovering Hydrogen in these circumstances. PSA is reliable, so from operational perspective this is a viable option. Cryogenic separation is also possible but can be somewhat more problematic to operate. Hydrocrackers usually demands higher purity in favour of recovery which favours PSA before cryogenics.
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16/09/2007
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Original Questioner, Follow Up,
The specification of gas inlet membrane is:
Normal flow rate 10000NM3/hr
Max flow rate 20000NM3/hr
Temperature is: 60C(max)
Pressure inlet is 29 Barg
The result of our gas is:
H.P.GAS
H2 mol% 75.6
C1 mol% 4.9
C2 mol% 2.3
C3 mol% 2.5
iC4 mol% 1.3
nC4 mol% 1.1
iC5 mol% 0.5
nC5 mol% 0.3
C6+ mol% TR.
H2S mol% 11.5
NH3 ppm TR.
The Property of product out of membare is:
H2>= 99.9% , pressure> 22 Bar , Temp.<40 (By cooler or ext..) , maximum recovery
can we use a membrane system for separation of hydrogen from outlet gas of this Unit ?
I'd be very interested in finding out more about costs of systems.
......
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10/09/2007
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Kaveh Farzadkia, Tehran Oil Refining, kavehfarzadkia@gmail.com
This depends on several factors such as the amount of your off gas, pressure of pure hydrogen etc. But there are several good articles about the selection of hydrogen recovery system that explain about the criteria that you must consider in making a decision.......
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09/09/2007
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Pietro Di Zanno, Air Liquide E&C, pietro.dizanno@airliquide.com
Membrane systems can be useful in this application as there is a pressure delta between the recycle hydrogen compressor and the make-up hydrogen compressor.
What is important is the amount of H2 recovery that is desired and its purity. These will have an impact on the membrane modules costs.
In terms of OPEX, the modules are quite robust, but they should not be used for H2S removal.......
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