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Keywords:

  • fluidization;
  • circulating fluidized bed;
  • reactor system;
  • combustion;
  • chemical looping;
  • carbon capture

Abstract

A fluidized bed system combining two circulating fluidized bed reactors is proposed and investigated for chemical looping combustion. Direct hydraulic communication of the two circulating fluidized bed reactors via a fluidized loop seal allows for high rates of global solids circulation and results in a stable solids distribution in the system. A 120 kW fuel power bench scale unit was designed, built, and operated. Experimental results are presented for natural gas as fuel using a nickel-based oxygen carrier. No carbon was lost to the air reactor under any conditions operated. It is shown from fuel power variations that a turbulent/fast fluidized bed regime in the fuel reactor is advantageous. Despite the relatively low riser heights (air reactor: 4.1 m, fuel reactor: 3.0 m), high CH4 conversion and CO2 yield of up to 98% and 94%, respectively, can be reported for the material tested. © 2009 American Institute of Chemical Engineers AIChE J, 2009