(57b) 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 TDA’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). TDA’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, TDA’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 carrying out field tests with the warm gas CO₂ capture unit at 0.1 MWe scale at the National Carbon Capture Center (NCCC) in Wilsonville, AL and has so far completed over 500 hours of field tests achieving greater than 90% carbon capture. In this paper we present the results from the system analyses and the field test with the 0.1 MW_e pilot unit at NCCC