Process for CO2 Capture from High-Pressure and Moderate-Temperature Gas Streams

A novel CO2 capture process was developed using a Mg(OH)(2)-based sorbent suitable for warm gas CO2 removal from high-pressure coal gasification gas streams. The purpose of this study is to perform a preliminary energy study and develop a method to implement this sorbent in a power plant. The proposed CO2 removal process involves sorption of CO2 at 200-300 degrees C and regeneration at 385 degrees C. The operational temperature is ideal for CO2 capture downstream to the water-gas shift reactor in an integrated gasification combined cycle (IGCC) power plant but is applicable to other warm gas cleanup processes as well. This technology offers the ability to fully utilize the potential efficiency increases associated with warm gas clean up. Additionally, the sorbent is able to operate in the presence of steam, which distinguishes it from other technologies that require an energy-intensive drying step prior to CO2 separation. Regeneration is carried out at 280 psi and 400 degrees C, resulting in a high-pressure CO2 product stream, which significantly reduces the auxiliary load normally associated with CO2 compression for sequestration. The chemistry of the sorption process also reduces the amount of steam traditionally required for the water-gas shift reactor by 50%, increasing the overall efficiency of the plant. The incorporation of the sorbent and the described methods resulted in an overall IGCC power plant efficiency greater than that of the competing Selexol technology.