What is Largest Practical Limit?
What is Largest Practical Limit?
(OP)
What is the largest practical limit for a compressor? Is it feasible to compress a gas stream as large as 2e6 acfm to 100 psig?
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What is Largest Practical Limit?
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RE: What is Largest Practical Limit?
If you told us what you were trying to do, you might get some help selecting equipment.
David
RE: What is Largest Practical Limit?
RE: What is Largest Practical Limit?
Most of the time I get asked to look at this sort of problem, the target discharge is 1,000 to 10,000 psig and the hp requirements go way up. Your application is 250 hp (with the lower mass flow rate)--to go to 1,000 psig the hp goes to 1100 hp in three stages, and at 10,000 it is around 2,800 hp in 5 stages.
Compressing flue gas is done every day. Your boiler doesn't sound particularly large (I don't have a feeling for the BTU rating of the boiler based on flue gas flow rate) and this is a pretty easy application.
David
RE: What is Largest Practical Limit?
2E6 acfm * 60 min/hr * 24 hr/day * 88% = 2.5e9 scf/day
= 2500 mscf/day
Theoretical Hp if one stage is approximately
144/33,000*(1.4/(1.4-1))(14.7 psia)*(2e6 acfm)*((115/15)^((1.4-1)/1.4) - 1)
= 354,500 Hp
It looks like we're off by a factor of 10^3.
RE: What is Largest Practical Limit?
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My speculation is; you will only need to get the flue gas pressure to 30 to 50 psig inorder to remove the CO2.
RE: What is Largest Practical Limit?
Thank you for the reference to axial compressors. I knew I would have to use multiple compressors, if it was realistic at all. If my pressure was lower, say the 30 psig you mention, would that allow me to use fewer centrifugal compressors, or some other type?
RE: What is Largest Practical Limit?
As to how high you need to get the pressure, that depends on what you are going to do with the stuff. If you're just going to separate out the CO2 from the water and Nitrogen compounds then you can do it at a pretty low pressure, but what then? Putting pure CO2 into the atmosphere has the same "carbon tax" risks as just letting the mixture go up the stack (to say nothing of the emissions from the compressor drivers). CO2 sequestration projects generally require pretty hig pressures (the one I worked on late last year was at 1,200 psig and that is the lowest I've seen). If you are going to try to get to food grade CO2 the market is pretty saturated.
David
RE: What is Largest Practical Limit?
I also ran simulations and what you find out is you will have amine circulation rates in 50,000 gallons/minute with 20 to 25% of the power plants electricity and low pressure steam being used in recovering the CO2. Then you will expend another 5% to 15% of the power plants output compressing the CO2 to pressure wher it can be sequestered. These papers will also verify the cost to remove. The recovery plant will have a capital of about 25% of the original power plant, then with the loss of 35% of the plants capacity, you'll have to make the power plant 50% larger than you need. The net is the capital cost will nearly double and the energy output price will nearly double.
RE: What is Largest Practical Limit?
David
RE: What is Largest Practical Limit?