CO2 removal from power station flue gas

What about scrubbing the gasses and then heating the water under controlled conditions to release the CO2?

I would suggest that you read these two Wikipedia articles: one about the use of aqueous amine solutions to absorb and recover either CO2 or H2S (or both) from gas streams and the other about using Pressure Swing Adsorbtion on a solid media for recovery of CO2 from gas streams.

http://en.wikipedia.org/wiki/Amine_gas_treating
http://en.wikipedia.org/wiki/Pressure_Swing_Adsorption

I used to be involved in research/design of systems for scrubbing CO2 from flue gases. Amine solutions were typically the preferred method.

It would appear that the intent of the original question was how to dispose of CO2 permanantly. While an amine absorber can be used, the regenerator discharges the CO2 to the atmosphere. Other temporary storage methods have the same probllem. Average CO2 content in flue gas when oil is burned is about 15%-17%, more for coal and less for natural gas, So the absorber and regenerator train have a purpose in reducing the total volume of gas to be compressed and sent underground (sans nitrogen), the only means now appearing practical to get rid of the stuff. But compression and underground long term reintroduction of carbon to the earth in that form must be used if we are to maintain atmospheric CO2 levels below 350 PPM at year 2050. One additional consideration about an amine absorber train is efficiency: The gas needs to be introduced to the absorber (involving compression at at high pressure of ALL flue gas components, and once absorbed, there is a letdown to atmospheric pressure at which point the CO2 comes out of solution, often violently, involving Letdown valves with stellited plugs and seats (requiring frequent mainenance) or multi-stage letdown. Both the need for inlet compression and letdown afterwards contribute to inefficiency. Expanders to recover shaft work from the letdown are not practical due to the violent nature of CO2 evolution during letdown. Expanders are essentially reverse turbines used to remove shaft work from expanding gases, as in refrigeration trains used for very low temperature fractional distillation, as found in ethylene production.

BernieK

Just my two cents after the first half of my career spent with Lummus company, former division of Combustion Engineering.

Good day Berniek,

Firstly this is not spam, but a serious request for help

Having worked in water treatment for quite a few years, now find a gap in my knowledge and don't want to redesign the wheel if someone can help.

The original question was probably to general, I need to remove from chimney gases, CO2 and nitrogen, this then needs to be stored for reuse within the process

The stored gases need to be clean, so they can be re-injected

At this point need to keep things general, would discuss on a one to one if you can supply an e mail address

Hi Waterdoc,

Just to clear things up, no one is stating that your post is SPAM. We (the CR4 admin) removed a comment that another user posted in this thread that was indeed SPAM.

- Chris

waterdoc:

Your latest post is quite different from your first one. In your first one, you inquired about "CO2 removal from chimney gases" (i.e., combustion flue gases).

In your latest post, you state "I need to remove from chimney gases, CO2 and nitrogen, this then needs to be stored for reuse within the process". As I read that, you are now inquiring about removing CO2 and Nitrogen, which is essentially all of the flue gas except water vapor, small amounts of excess Oxygen, and traces of NOx, SO2, etc. Did you really mean that?

Also, when you say "this then needs ...", do you mean that you need to store both the CO2 and Nitrogen for storage?

Please clarify and make explicit exactly what you want to do.

There is also a process under a Japanese patent which claims a better process at less cost, producing a CO2 in recoverable form. The process uses a compression chamber and water spray with an organic additive. Claims are this process is cleaner and consideraby cheaper than those used in coal gasification by CE, Foster-Wheeler and others. Richard

rlphaywards@hotmail.com

Another method of stripping the CO2 is being developed by Binair Technologies. They dissolve the CO2 in water and the methane remains in gaseous form for burning. Then they remove the CO2 from the water for commercial use. see it at www.binair.ca

"As for the future, your task is not to forsee it, but to enable it." -- Antoine de Saint-Exupéry

Mailman:

The original poster is not asking about removal of CO2 from fuel gases. He is asking about how to remove CO2 from the chimney gases (combustion flue gases) formed by the combustion (burning) of fuels. From what little I can glean from the www.binair.ca site that you mentioned, their technology is for the removal of CO2 from fuel gases such as biogas and syngas, rather than from combustion flue gases.

When you say "They dissolve the CO2 in water and the methane remains in gaseous form for burning", I would point out that there is very, very little methane (if any) left in typical chimney gases.

Scrub the flue exhaust with sodium hydroxide, ammonium hydroxide or some other alkali. Carbon dioxide, being acidic, will chemically combine with them. You can later recover the CO2 by heating the sodium or ammonium carbonate after separating it from the water. Simply scrubbing it with water will remove the CO2, but once the carbonic acid gets exposed to the atmosphere, if the CO2 concentration of the water is much higher than the surrounding air, it will come out of solution again.

CO2 removal from flue gases.

Check out US patent 6372023 by Kiyono/Saito

rlphaywards@hotmail.com

Why not cool the hot gases to near ambient and send the CO2 and H2O to greenhouse farms? Removal of SO2 and NOX of course would be beneficial.

Get really green.