Amine Scrubbing Process

The process finally selected by Pioneer for the CCF was amine scrubbing, which is a widely-practiced chemical process also known as amine gas treating, gas sweetening and acid gas removal. It is a process commonly employed in oil refineries, but also in natural gas processing plants in Alberta and other natural gas producing regions. One of the goals of Project Pioneer was to demonstrate the applicability of amine absorption to coal-fired power plants, which would be a relatively new application for the process.

Amine scrubbing refers to a number of commercial technologies that use various alkanolamines to remove acidic components such as hydrogen sulfide (H2S) and CO2 from gas streams. The underlying principle is the exothermic, reversible reaction between a weak acid such as CO2 and a weak base such as an alkanolamine. The flue gas to be treated is contacted by the aqueous alkanolamines solution in an absorbing column or vessel where a soluble salt is formed from the reaction between the CO2 and the alkanolamines. The flue gas, now depleted of CO2, is then released to the atmosphere. The solution, 'enriched' with the CO2, is sent to a stripping column or vessel where, by the addition of heat, the salt formation reaction is reversed and the CO2 and the alkanolamines are regenerated. The "lean" alkanolamines solution is recycled to the absorbing unit while the CO2 is made ready for transportation by dehydrating and compressing it.

The following figure shows the process flow diagram for amine capture.

fig. 3.0

AMINE SCRUBBING PROCESS