Investigation of a dual cold-flow fluidized bed for calcium looping gasification process

Abstract

In this paper, a compact fluidized bed gasifier is proposed for the calcium looping gasification process to produce hydrogen-rich gas with CO2 capture. The design of compact fluidized bed gasifier is according to the adsorption properties of lime under different partial pressure of CO2 and temperature. The compact fluidized bed gasifier consists of two sections: an upper riser and a lower bubbling fluidized bed. The fluid dynamics feasibility of the proposed dual fluidized bed with compact fluidized bed gasifier was evaluated in a cold flow model. The cold flow model can operate in a stable state under designed conditions. Most of the bed materials (>90%) stay in the lower bubbling fluidized bed. The effect of the total solid inventory and the fluidizations in both the lower bubbling fluidized bed and the regenerator on the solid recirculation flux is marginal because of the high resistance in the loop-seal of the lower bubbling fluidized bed to the regenerator. The solid recirculation flux can be controlled effectively by loop-seals, but the fluidization number in the supply section of the loop-seal must be kept lower than 1. No gas leakage was detected in the cold flow model under the designed conditions.