in our refinery we treat the LPG produced from the FCC unit by extraction merox unit.
In the pretreatment to remove the H2S from LPG, the absorber shows low efficiency. What is the problem?
(the abs. press. 10.5 bar
amine conc. % vol.= 19
regenerator good efficincy
H2S in rich Amine = 0.034 WT%)
Answers
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25/10/2007
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A:
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Amarjit Bakshi, Refining Hydrocarbon Technologies LLC, abakshi@rhtgulfcoast.com
The answer provided by Amine experts provides you with starting point and trouble shoot the problem.
But some of the other areas one should look into it are
1. The absorber temperature should be consistent with design: the lower the absorber temperature; the better the efficiency.
2. The LPG or amine is not by-passing due to plugging or fouling of absorber.
3. Absorber is not working at much higher than the design capacity, which will have some effect on efficiency.
It needs a systematic evaluation of the absorber and regenerated amine recycle stream and quality. ......
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17/10/2007
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A:
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Egbert van Hoorn, Hocon B V, Egbertvh@hotmail.com
There can be several problems related to your amine unit. You state that the regenerator has a good efficiency but you do not mention the lean amine loading, nor the top temperature of the regenerator. Perhaps regeneration can be improved.
I suppose that you are using DEA. For DEA the concentration is somewhat on the low side, but that should not be a problem
H2S in the rich DEA seems low, indicating that you are likely to circulate enough DEA.
How do you notice the low efficiency? High caustic consumption?
How long has this been going on?
Could there be something wrong with the LPG distributor?
Have you made a detailed lean amine analysis?
Not only strength and H2S, but also HSAS, metals, water content so that you can be sure that you have amine and water and not a lot of other items.
Sometimes the amine gets contaminated with caustic, which makes it very hard to regnerate properly.
Regarding operating conditions, you should use about the same LPG as amine temperatures
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