The University of Illinois Urbana-Champaign and URS Corporation are investigating a concept in which a dry sorbent technology is configured to combine the water-gas-shift (WGS) reaction with CO2 removal for coal gasification systems. A solid sorbent bed removes CO2 at conditions designed to improve WGS efficiency, subsequently eliminating the need for a catalyst. It also enables CO2 capture and regeneration at high temperature and pressure, thus minimizing energy efficiency impacts on the treated IGCC plant. Driving the WGS reaction toward H2 production / CO2 capture in this manner can provide a more direct and less expensive path to market.
A key technical issue for advancing the sorption-enhanced WGS is to identify and develop high-performance, high-efficiency sorbents with properties suitable for CO2 capture at high pressure and high temperature syngas conditions. To achieve this goal, a combination of process simulation modeling and sorbent molecular and thermodynamic analyses are being performed to determine sorbent properties and optimal temperature and pressure windows for maximizing the energy efficiency of the combined WGS-CO2 capture process. A desired adsorbent should possess high CO2 adsorption capacity and selectivity in a temperature range between 200 and 550 C and be able to regenerate at elevated pressures.
A commercial software package, FactSage 6.1, is being used to perform thermodynamic calculations for different classes of potential adsorbents. Fundamental properties, such as entropy and enthalpy, of various metals oxides and other potential sorbents are used to evaluate the CO2 capture and WGS reaction under different process conditions and syngas environment. The results from these thermodynamics calculations will later be integrated in the process simulation to evaluate the energy performance of the SEWGS integrated in a coal gasification process. This presentation will provide a summary of the results from the thermodynamic study.
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