Controlling the Solid Circulation Rate and Residence Time in Whole Loops of a 1.5 MW_th Chemical Looping Combustion Cold Model

Abstract

Autothermal operation is a big challenge for a chemical looping combustion (CLC) demonstration plant. One of the key points of CLC autothermal operation is to achieve a high solid circulation rate and enough solid residence time. To address this challenge, a dedicated lifter is proposed to control the solid circulation rate and residence time in the dual fluidized bed reactor system. This dedicated lifter is integrated into a 1.5 MWth CLC cold flow model to evaluate the control of the solid circulation rate and residence time of this new CLC scheme. Continuous and stable circulation of solid particle operation is achieved in the cold flow model, and it has been demonstrated that the dedicated lifter can effectively control the solid circulation rate. The effect of gas velocity, bed inventory, and particle size on the fluidization in the whole loops is studied. The dedicated lifter can control the solid circulation rate in the range of 20–68 kg m–2 s–1, and residence time in the fuel reactor is maintained in the range of 180–610 s. The solid circulation rate and residence time obtained in this work satisfy the theoretical requirements of CLC autothermal and char gasification, respectively, which indicates that the autothermal operation of the CLC unit as well as high carbon capture efficiency can be realized in this new CLC scheme.