CCS and Power Systems
Carbon Capture - Post-Combustion Capture
Waste Heat Integration with Solvent Process for More Efficient CO2 Removal from Coal-Fired Flue Gas
Project No: FE0007525
Southern Company Services, Mitsubishi Heavy Industries America (MHIA), and URS Group have teamed to develop viable heat integration methods for the capture of CO2 produced from PC combustion plants, improving upon the current state-of-the-art for solvent-based capture processes. An advanced level of heat integration between the power plant and the CO2 capture facility will be demonstrated by incorporating a waste heat recovery technology into an existing amine-based CO2 capture process. The project will incorporate MHIA’s High Efficiency System (HES) heat recovery and integration technology into a currently operating 25 megawatt (MW) pilot plant demonstration of the Kansai Mitsubishi Carbon Dioxide Recovery (KM-CDRTM) CO2 capture process at Southern Company’s Plant Barry. The KM-CDR demonstration is separately funded by an industry consortium unaffiliated with this project. The 25 MW HES technology will be designed, installed, and operated for 12 months to evaluate the resulting energy performance improvement . The KM-CDR process is designed for 90 percent CO2 capture and is based on an advanced amine with several advantages over monoethanolamine (MEA), resulting in reduced steam demand for regeneration, lower corrosivity, and better stability to flue gas constituents such as oxygen.
The HES incorporates a low temperature flue gas cooler to extract waste heat from flue gas exiting the power plant’s air preheater and makes that heat available for use in both the power and CO2 recovery plants. In a typical coal-fired power plant, the addition of a chemical solvent process for CO2 capture requires the extraction of a relatively large volume of low pressure (LP) steam from the power plant’s steam cycle, which decreases the power generation of the plant. The HES heat integration technology will use waste heat streams to provide needed process stream heating, reducing the amount of LP steam extracted for the solvent regeneration system. The recovered heat will also be used to heat boiler feed water, further reducing the extraction steam demands on the LP turbine and increasing the LP steam available for power generation. The HES has been successfully demonstrated at several low-sulfur, coal-fired power plants outside of the United States, though not with CO2 capture. This project will examine the HES performance with high-sulfur flue gas, and as integrated with a CO2 recovery system. A preliminary techno-economic analysis has indicated that HES with advanced heat integration can reduce the total energy impact of CO2 capture by 26 percent, a considerable step toward meeting the DOE goal for the cost of electricity (COE).
The project will also demonstrate that the HES provides ancillary benefits to the host plant, such as reduced water use in the flue gas desulfurization system due to lower flue gas temperatures, better electrostatic precipitator (ESP) performance due to lower ash resistivity, and better sulfur trioxide capture in the ESP by lowering the flue gas below the acid dew point. These benefits to the host plant will, in turn, provide an additional benefit to the CO2 capture process by reducing the impurity levels in the feed to the CO2 capture process island, thus reducing the solvent consumption due to those impurities.