Application of Concrete and Demolition Waste as CO_2 Sorbent in Chemical Looping Gasification of Biomass

摘要

This paper summarizes the results of an experimental investigation into sorbent chemical looping gasification (SCLG) of biomass for the production of high-purity hydrogen and in situ capture of the resulting CO_2. The key innovation was the use of concrete and demolition waste (CDW) as the source of CO_2 sorbent. A comprehensive series of thermogravimetric analysis (TGA) experiments was carried out over a range of temperatures between 650 and 900 ℃ and pressures up to 20 atm to benchmark the CO_2 capture efficiency of CDW against conventional lime-based sorbents [e.g., calcined limestone (CL) and hydrated Portland cement (HPC)]. Effects of controlling parameters, such as the Ca/C ratio, steam/carbon (S/C) ratio, steam partial pressure, and total pressure, on the gas yield, gas composition, and CO_2 capture efficiency were thoroughly examined. Experimental results confirmed that CO_2 capture efficiencies as high as 56.4% and high-grade hydrogen production can be achieved when CDW is used as a sorbent. These results combined with the high mechanical strength, durability, and low cost make CDW an attractive sorbent for chemical looping gasification of carbonaceous solid fuels, particularly biomass.