SO2 removal characteristics using waste CaO from calcium looping CO2 capture process

作者:Shao, Yan; He, Donglin; Qin, Changlei*; Ran, Jingyu*; Zhang, Li
来源:Greenhouse Gases: Science and Technology , 2017, 7(4): 637-648.
DOI:10.1002/ghg.1676

摘要

Calcium looping (CaL) has been identified to be a valuable candidate for CO2 capture and has entered a stage of large-scale experiment and application. However, the serious loss-in-capacity problem will result in the production of a large amount of waste CaO, which not only increases the economic cost of the capture process, also generates a huge risk of secondary pollution. In this work, the waste CaO from CaL was first proposed to be used for SO2 removal by wet desulfurization and the SO2 sorption characteristics were comprehensively studied. Through experimental test and analysis, it is found that CaL-spent CaO derived from dolomite can achieve higher efficiency than that from the limestone in SO2 removal. The effect of CaL cycle on the SO2 removal performance is observed to be small when the cycle number is under 40. Beyond that, the SO2 removal capacity decreases quickly, which is thought to be due to the variation in slaking rate determined by the compromise between the surface area and pore size distribution of the material. Furthermore, sulfation performance of waste CaO is found to be superior with a particle size smaller than 0.4 mm. This work proves the feasibility of the utilization of CaL-spent CaO in wet SO2 removal, and could be beneficial for understanding the SO2 sorption characteristics of CaL-spent materials.