(580b) Performance of a 10 Kwth Dual Fluidized Bed Chemical Looping Combustion Reactor Operating in Ig-Clc and CLOU Modes

2015
AIChE Annual Meeting- "Chemical Looping Processes"

Performance of
a 10 kW_th Dual Fluidized Bed Chemical Looping Combustion Reactor
Operating in iG-CLC and CLOU Modes

Kirsten M. Merrett and Kevin
J. Whitty

Dept. of Chemical
Engineering, University of Utah, Salt Lake City, UT

ABSTRACT

Chemical looping combustion
(CLC) is a technology to combust solid fuels while intrinsically separating the
greenhouse gas CO₂. This eliminates the energy cost associated with
gas separation, making CLC an attractive technology for CO₂
separation. CLC involves circulating a metal-based "oxygen carrier" between two
reactors in which it is oxidized by air and then reduced by a fuel, in essence
combusting the fuel. In the variant of CLC known as chemical looping with
oxygen uncoupling (CLOU), the oxygen carrier releases gas-phase oxygen as O₂
once in the fuel reactors reducing environment, allowing for a gas-solid
reaction to occur. Particles are then circulated to the air reactor and reoxidized. The natural mineral ilmenite presents a
cost-effective oxygen carrier material with demonstrated strength and cyclability, while copper allows for the desired oxygen
uncoupling behavior of the metal oxide during CLOU operation.

The University of Utah has
developed a 10 kW_th bench scale dual fluidized
bed chemical looping combustion system. The goal of the study presented here was to assess
system performance and compare conventional chemical looping combustion, known
as indirect gasification-CLC or iG-CLC, with CLOU
chemical looping. In this study two different fuels, coal and coal char, were
processed and the degree of fuel conversion, CO₂ capture efficiency
and CO₂ purity were evaluated. Performance of the unit itself is
also evaluated by changing variables such as temperature, flow rate, bed
inventory, and circulation rate to determine optimal performance.