Coal direct chemical looping process: 250 kW pilot-scale testing for power generation and carbon capture

Chemical looping combustion (CLC) is an energy conversion technology that can produce concentrated CO2 stream without the need for a gas separation step, and thus, has the potential to drastically reduce the energy consumption and cost associated with CO2 capture in power generation. The coal-direct chemical looping (CDCL) process is a CLC technology that uses a moving bed reducer configuration that can directly consume coal as a feedstock without requiring an upstream gasification step. An integrated 250 kW(th) CDCL pilot unit using iron based oxygen carriers was constructed and demonstrated for over 1000 h of testing. The principles for the CDCL pilot unit design and operation are summarized in this article. During the 288-hour continuous operation testing, the CDCL pilot unit achieved 96% coal conversion with a CO2 purity of >97%. Low carbon carryover into the combustor, i.e. <2%, was also confirmed during the test, which shows the capability of the moving bed reactor to retain and convert coal using the oxygen available on the iron-based oxygen carrier. The results from the pilot unit testing confirms the CDCL concept as a promising coal combustion technology for heat and power generation with CO2 capture.

Automated summary

Chemical looping combustion (CLC) and coal-direct chemical looping (CDCL) are promising technologies for generating concentrated CO2 streams and reducing energy consumption and costs in power generation. The CDCL pilot unit testing using iron based oxygen carriers successfully achieved high coal conversion rates and confirmed the concept's potential for coal combustion with CO2 capture.