CO2 capture using calcium oxide under biomass gasification conditions

Abstract

A laboratory scale CO2 capture apparatus was designed, fabricated, and tested for performing CO2 capture via carbonation of fine calcium oxide (CaO) with particle size in micrometers. This apparatus included a fixed-bed reactor made of stainless steel (12.7mm in diameter and 76.2mm long) packed with CaO particles dispersed in sand. The reactor was heated and maintained at isothermal conditions (500–595°C) during each experiment. The pressure along the reactor was kept constant using a back pressure regulator. The conditions of the experiments were relevant to biomass gasification with in situ CO2 capture. 1% CO2 in 99% N2 flowed through the reactor at a flow rate of 150ml/min (at standard conditions). The CO2 percentage of the outlet gas stream was measured by using a CO2 analyzer and was used to calculate the conversion of CaO. The results indicated that the rate of CaO carbonation considerably increased with reactor temperature increasing from 500°C to 595°C. The conversion rates of CaO carbonation were well fitted to Lee's and Shih's models for CO2 capture in dry and moist stream, respectively.