Coal conversion in a fluidized bed chemical looping reactor using a copper-based oxygen carrier

Conference · Mon Sep 24 04:00:00 EDT 2018

OSTI ID:1593124

Merrett, Kirsten M. ^[1]; Whitty, Kevin J.

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1. University of Utah

Chemical looping combustion (CLC) of coal presents interesting challenges, particularly with regard to conversion of the solid char that remains after devolatilization. Reaction of solid char with solid oxygen carriers is inefficient, so conventional chemical looping oxygen carriers rely on in-situ gasification of char in the fuel reactor to produce combustible gas. Chemical looping with oxygen uncoupling (CLOU) is a variant of CLC that uses an oxygen carrier that releases gaseous O2 in the fuel reactor, allowing for a rapid reaction with solid fuels. However, even with CLOU, there is competition between consumption of available gaseous and metal bound oxygen by volatiles versus char. This study aims to better understand the mechanisms of coal conversion in a 10 kWth bench-scale fluidized bed reactor system using a copper-based CLOU carrier. Both coal and coal char were evaluated when fuel was fed in small batches. The effect of coal particle size and temperature on the pathway of carbon conversion was evaluated. Smaller coal particles are more effectively converted through the CLOU pathway; however, more particles were entrained with the fluidizing gas and exited the reactor before being fully converted. Larger particles rely primarily on conversion of volatiles and gasification products because the large solid char particles are ineffectively converted by both gaseous oxygen and solid oxygen carrier contact. The advantage of larger coal particles is the decrease in elutriated fuel particles. This paper summarizes the experimental results and discusses the mechanisms of carbon conversion for a CLOU system.

• Research Organization: University of Utah
• Sponsoring Organization: USDOE Office of Fossil Energy (FE)
• DOE Contract Number: FE0025076
• OSTI ID: 1593124
• Report Number(s): DOE-U_Utah-0025067-05
• Country of Publication: United States
• Language: English