An integrated fuel reactor coupled with an annular carbon stripper for coal-fired chemical looping combustion

摘要

An integrated fuel reactor (FR) coupled with an annular carbon stripper (CS) was proposed for coal-fired chemical looping combustion. The FR was designed as two independent bubbling fluidized beds that efficiently used the reactor's space and made the particle residence time longer and more uniform. An annular CS was integrated into the FR, which aimed to separate char from the oxygen carrier and decrease the system complexity. A coal-fired CLC system consisting of an integrated fuel reactor and an air reactor for fast fluidization was designed. A cold-flow model of the 30-kWth coal-fired CLC system was built and operated. Plastic beads were used to simulate char particles, and the oxygen carrier was ilmenite. Continuous and stable operation of the cold model was achieved, and the solid circulation rate was easily controlled. The plastic bead was found to be separated efficiently from the oxygen carrier using the annular CS and then concentrated in the FR. The separation efficiency in the CS was increased by decreasing the solid flow rate or by increasing the gas velocity in the annular zone of the CS. The separation efficiency decreased when coupling the annular CS into the CLC system due to the more severe non-uniformity structure of gas-solid two-phase flow in the CS of system. The carbon capture efficiency of the coal-fired CLC system was calculated and predicted, and the integrated FR with annular CS was concluded to greatly enhance the carbon capture efficiency of the coal-fired CLC system. (C) 2017 Published by Elsevier B.V.