Experimental investigation of the absorption enhanced reforming of biomass in a 20 kWth dual fluidized bed system

Abstract

A gasification product gas with a hydrogen content over 75 vol-%_db and a heating value of 15 MJ/m³_STP,db has been obtained through the absorption enhanced reforming of biomass. The Absorption Enhanced Reforming (AER) process involves a Dual Fluidized Bed (DFB) system consisting of a gasifier and a regenerator (calciner). In the DFB system, the Ca - looping ratio is an important parameter defined as the ratio of the molar flow rate of regenerated sorbent (F_Ca) and carbon (F_c) which enters the gasifier as fuel. A special feature of the 20 kW_th DFB test facility at IFK is the Ca - looping rate control through a cone valve. Therefore, the Ca - looping ratio  (F_Ca/F_C)  was varied between a value of  2 and 12 mol_CaO/mol_C to investigate its influence on the cold gas efficiency, product gas yield, yield of gas components and gravimetric tar concentration during the AER of biomass. The experiments were carried out with wood pellets and a Greek limestone as CO₂ sorbent. The experimental work shows a clear influence of the Ca - looping ratio on the AER process. It shows also that beyond a certain value of this parameter, the tar and gas composition is stabilized.

 

 

Keywords

• Steam gasification, Biomass, Tar, Dual fluidized bed gasifier, CO2 capture, Hydrogen