(137b) Highly Efficient Warm Gas Carbon Capture System for IGCC Power Plants

TDA is developing a novel sorbent that removes CO₂ via physical adsorption from synthesis gas. The relatively strong affinity of the sorbent to CO₂ enables effective operation at temperatures up to 300^oC (well above the dew point of synthesis gas stream generated by commercial gasifiers). However, because the sorbent and the CO₂ do not form a true covalent bond, the energy needed to regenerate TDAâ??s sorbent (5.4 kcal per mol of CO₂) is much lower than that observed for either chemical absorbents (e.g., 29.9 kcal/mol CO₂ for sodium carbonate) or amine-based solvents (e.g., 14.2 kcal/mol CO₂ for monoethanolamine). TDAâ??s sorbent can be regenerated isothermally and CO₂ can be recovered at pressure (as high as 150 psia). Thus, the energy needed to regenerate the sorbent and compress the CO₂ for sequestration is significantly lower than that for any other technology reported to date. The high surface area and favorable porosity of the sorbent also provides a unique platform to introduce additional functionality, such as active groups to catalyze the water-gas-shift (WGS) reaction or to remove trace metals (e.g., Hg, As). Hence, TDAâ??s CO₂ sorbent could be used to do a warm gas capture of CO₂ above the dew point of the synthesis gas in an Integrated Gasification Combined Cycle (IGCC) power plant. TDA's pre-combustion CO₂ capture system achieves a net plant efficiency of 34% on a coal high heating value basis when operated on bituminous coal, which is significantly higher than that can be achieved with the Selexol^TM scrubber at 31.6% (state-of-the-art pre-combustion carbon capture technology). The levelized cost of electricity including the transport, storage and monitoring costs for CO₂ is calculated as $92.9/MWh for TDA's system, in comparison to $105.2/MWh for Selexol^TM. In a current DOE sponsored project, TDA is preparing to carryout field tests with the warm gas CO₂ capture unit at 0.1 MWe scale. In this paper we present the results from the system analysis, bench-scale evaluations, and the fabrication and testing of the 0.1 MWe field test unit.