Advanced CO<sub>2</sub> Capture Technology for Low Rank Coal IGCC System

Abstract

The overall objective of the project is to demonstrate the technical and economic viability of a new Integrated Gasification Combined Cycle (IGCC) power plant designed to efficiently process low rank coals. The plant uses an integrated CO{sub 2} scrubber/Water Gas Shift (WGS) catalyst to capture over90 percent capture of the CO{sub 2} emissions, while providing a significantly lower cost of electricity (COE) than a similar plant with conventional cold gas cleanup system based on SelexolTM technology and 90 percent carbon capture. TDA’s system uses a high temperature physical adsorbent capable of removing CO{sub 2} above the dew point of the synthesis gas and a commercial WGS catalyst that can effectively convert CO in The overall objective of the project is to demonstrate the technical and economic viability of a new Integrated Gasification Combined Cycle (IGCC) power plant designed to efficiently process low rank coals. The plant uses an integrated CO{sub 2} scrubber/Water Gas Shift (WGS) catalyst to capture over90 percent capture of the CO{sub 2} emissions, while providing a significantly lower cost of electricity (COE) than a similar plant with conventional cold gas cleanup system based on SelexolTM technology and 90 percent carbon capture. TDA’s system uses a high temperature physical adsorbent capable of removing CO{sub 2} above the dew point of the synthesis gas and a commercial WGS catalyst that can effectively convert CO in bituminous coal the net plant efficiency is about 2.4 percentage points higher than an Integrated Gasification Combined Cycle (IGCC) plant equipped with SelexolTM to capture CO{sub 2}. We also previously completed two successful field demonstrations: one at the National Carbon Capture Center (Southern- Wilsonville, AL) in 2011, and a second demonstration in fall of 2012 at the Wabash River IGCC plant (Terra Haute, IN). In this project, we first optimized the sorbent to catalyst ratio used in the combined WGS and CO{sub 2} capture process and confirmed the technical feasibility in bench-scale experiments. In these tests, we did not observe any CO breakthrough both during adsorption and desorption steps indicating that there is complete conversion of CO to CO{sub 2} and H{sub 2}. The overall CO conversions above 90 percent were observed. The sorbent achieved a total CO{sub 2} loading of 7.82 percent wt. of which 5.68 percent is from conversion of CO into CO{sub 2}. The results of the system analysis suggest that the TDA combined shift and high temperature PSA-based Warm Gas Clean-up technology can make a substantial improvement in the IGCC plant thermal performance for a plant designed to achieve near zero emissions (including greater than 90 percent carbon capture). The capital expenses are also expected to be lower than those of Selexol. The higher net plant efficiency and lower capital and operating costs result in substantial reduction in the COE for the IGCC plant equipped with the TDA combined shift and high temperature PSA-based carbon capture system.