Membrane-Based Hybrid Process to Capture CO2 from Warm Flue Gas

75772B Most coal-based power plants use pulverized coal boilers to generate superheated steam for turbine applications, accounting for over 50 percent of U.S. electricity generation. The flue gas stream from these plants contains CO2, along with N2 and other minor components such as SO2 and NOx. Although some commercial technologies are available to separate or capture the CO2 from the flue gas, in order to reduce the buildup of greenhouse gases in the atmosphere, these processes are both capital intensive and high in operating costs. This project will develop a membrane-based hybrid process for capturing and enriching the CO2 from the warm flue gas streams emitted from pulverized-coal-fired power plants. When retrofitted on conventional air-based, fossil-fuel-fired power plants or integrated into new power-generation facilities, the process will capture more than 90% of the CO2, and compressed CO2 with greater than 99 vol% purity will be obtained. In Phase I, the membrane-based hybrid system was developed and tested on a simulated flue gas containing 10 to 15% CO2. A product stream containing 99.3-99.6 vol% CO2 was produced with a recovery effeciency of >90%. Parametric optimization and techno-economic analysis were performed over a range of temperatures, CO2 partial pressures, and SO2 contents in the flue gas. In Phase II, the membrane hybrid sytem will be further optimized to provide higher CO2 capture efficiency and higher CO2 purity. Long-term experiments will be performed to test the operational stability of the membrane system when used to treat simulated flue gas containing both SOx and NOx. Finally, a prototype system will be tested in a pilot plant. Commercial Applications And Other Benefits as described by the applicant. The membrane-based hybrid process should provide superior performance compared to the conventional processes for CO2 separation/capture (i.e., amine-based absorption/desorption, membrane gas absorption, and conventional membrane gas permeation processes). The cost of capturing (separating, compressing, and liquifying) 90% CO2 from a flue gas stream containing 15% CO2 would be 1.275 - 1.80 cent/kWh (or 13.5 ¿ 20 dollars/ton CO2 avoided).