co2 gas compression and dehydration
co2 gas compression and dehydration
(OP)
My gas stream is 98% co2, it has 0.46% c1, 1.1% c2, 0.06% h2s, 0.049% argon, 0.063% o2, 0.46% n2. It is the flue gas from amine stripper. I need to compress it to 2000 psig, the flowarte is about 1.8 MMscfd, and transfer it into a pipeline.
What method of dehydration do I need?
What type of compressor?
Could you please outline everything that needs to go into this package?
What critical issues need to be considered?
Thanks
What method of dehydration do I need?
What type of compressor?
Could you please outline everything that needs to go into this package?
What critical issues need to be considered?
Thanks





RE: co2 gas compression and dehydration
Generally, I'd use a 5 stage reciprocating compressor with a TEG dehydrator after the fourth stage.
Read the contracts it'll tell you where you will have problems.
RE: co2 gas compression and dehydration
Why not 4 stages?
Why TEG and not mole sieve dehydration?
This is very preliminary no sales contract, because 2 people sat at breakfast and came up with this idea. They have no knowldge of what will be involved. This is new to me too.
I have simulated it in HYSYS, by saturating it with water, then 4 stages of (recipe)compression (75% efficiency) with final delivery at 2000 psig and 120 F. Inlet gas is at 1.5 psig and 70 F. I knocked out most of the water but still have water going to the pipeline, which means I can have corrosion problems.
I need to know what are the main factors, which need to be considered in designing this system.
RE: co2 gas compression and dehydration
The only reason to use mole sieve is if you need to have water in the 0 to 4 ppm range. Most Co2 sales contracts allow the water to be 7 pounds/mmscfd. The reason for the 7 lb/mmscfd, bceause thats a resonable level of water from a TEG unit.
You will not have corrosion problems if you do not remove the water in a 2000 psig line because the CO2 is above its criticle point and it is hydroscopic and will carry twice as much water in the vapor phase. water in the vapor phase is not corrosive.
RE: co2 gas compression and dehydration
I saturated my co2 flue gas from the stripper and ended up with 224 lb/MMscf of water at 2000 psig and 120 F. As you mentioned it is all in the gas phase. So, does it mean after the last stage it can go to a C.S. pipe as long as it stays in critical region? I have a feeling this will go underground and it could get to 60 F and start condensing. In that case is the 7 lb/MMscf ok, when it comes to corrosion?
Is Natco the one for TEG DEH units?
Thanks for your help!
RE: co2 gas compression and dehydration
- What is the final disposition of the CO2?
- Does it really have to be dried for a process reasons or corrosion reasons?
- Have you looked at doing the first two stages with flooded screws instead of recips? The shape of the constant entropy lines on your mollier diagram really favor using screws to get to about 70 psig.
- How sure are you of your water number? At 2000 psig and 120F I get a number much closer to 20 lbm/MMCf than 224 lbm/MMCF
- Are you going to be handling this stuff as an SCF or a liquid?
If you're just trying to get rid of it then it makes more sense to use corrosion resistant pipe and don't dehydrate at all. It sounds to me like you are a long ways from the point where the TEG vs. Mole Seive decision is critical.
David
RE: co2 gas compression and dehydration
I wouldn't be overly concerned with actual water content, instead, you should look at hydrate temperature, and how cold the line could possibly get during winter conditions.
regards,
Jim
RE: co2 gas compression and dehydration
A single recip is just fine. A srewcip sounds nice but at this low volume, not needed.
RE: co2 gas compression and dehydration
You are the best! Thanks.
RE: co2 gas compression and dehydration
RE: co2 gas compression and dehydration
RE: co2 gas compression and dehydration