June, 2005
Vol 1 Chapter 36: Construction and 100 h of Operational Experience of a 10-kw Chemical-looping Combustor
Anders Lyngfelt and Hilmer Thunman
Abstract: Chemical-looping combustion (CLC) is a new technology for burning gaseous fuels, with inherent separation of CO2. Metal oxide particles are used for the transfer of oxygen from the combustion air to the fuel, thus the combustion products CO2 and H2O are obtained in a separate stream. A 10-kW prototype for CLC has been designed, built and run with nickel-based oxygen-carrier particles. A total operation time of more than 100 h was accomplished with the same batch of particles, i.e. without adding fresh, unused material. A high conversion of the fuel was reached, with approximately 0.5% CO, 1% H2 and 0.1% methane in the exit stream, corresponding to a fuel conversion efficiency of 99.5% based on fuel heating value. The best way to treat the unconverted fuel is not clear, although it is believed that it can be separated from the liquefied CO2 at a reasonable cost and recycled to the process. There was no detectable leakage between the two reactor systems. Firstly, no CO2 escapes from the system via the air reactor. Thus, 100% of the CO2 is captured in the process. Secondly, it should be possible to achieve an almost pure stream of CO2 from the fuel reactor, with the possible exception of unconverted fuel, or inert compounds associated with the fuel, e.g. N2. No decrease in reactivity or particle strength was seen during the test period. The loss of fines was small and decreased continuously during the test period. At the end of the period the loss of fines, i.e. particles smaller than 45 mm was 0.0023% per hour. If this can be assumed to be a relevant measure of the steady-state attrition, it corresponds to a lifetime of the particles of 40,000 h. Assuming a lifetime of the particles one order of magnitude lower, i.e. 4000 h, the cost of particles in the process is estimated to be below e1 per ton of CO2 captured.
Carbon Dioxide Capture for Storage in Deep Geologic Formations – Results from the CO2 Capture Project Capture and Separation of Carbon Dioxide from Combustion Sources - Volume 1
Edited by: David C. Thomas, Senior Technical Advisor, Advanced Resources International Inc, USA
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