Chilled ammonia process for CO2 capture

Abstract

Abstract The Chilled Ammonia Process (CAP) can be applied to capture CO2 from flue gases exhausted from coal-fired boilers and natural gas combined cycle (NGCC) systems, as well as a wide variety of industrial applications. Initial tests conducted at the We Energies Pleasant Prairie Power Plant indicate that CAP can absorb CO2 using regenerated ionic solution on a continuous basis. The We Energies facility is designed to capture over 35 tonnes/day of CO2 at design rates. The facility was engineered, installed, and is being operated as a co-operative effort between Alstom (the process supplier) who engineered and constructed the pilot; EPRI (including 37 funders) who is conducting data collection and process evaluation; and We Energies who is providing operating utilities and is serving as the site host. The CAP is a solvent-based regenerable process that uses an aqueous ammonium solution to capture CO2 by forming ammonium bicarbonate. The bicarbonate is subsequently heated to drive off the CO2 with the resulting carbonate returned to the CO2 absorption system for re-use. Anticipated advantages of the CAP over an amine-based process include: Lower energy for regeneration Regeneration at pressure Ability to offset LP steam consumption with reject heat (Not tested at We Energies) Cooling to minimize ammonia penetration from the absorber. Results from the initial operation of the CAP process at the We Energies site are presented in this paper.