CaO在生物质定向气化条件下的高温CO2吸收特性

摘要

生物质定向气化可以制备富氢燃气和一定化学当量比的合成气(用于合成醇、醚等),同时有效地减少温室气体排放,是一种可持续的清洁能源转化技术.文章基于生物质定向气化这一背景,结合实际工业生产,采用TG/DTA系统对生物质定向气化条件下CaO吸收CO2的特性进行了研究.实验结果表明:升温速率由10℃/min增加到50℃/min,CaO变温吸收CO2的反应都在800℃左右达到吸收与煅烧平衡,且CaO转化率随升温速率增大而减小;CaO转化率和质量变化速率随CO2浓度增加而增大,根据反应平衡时CO2浓度与温度的关系拟合出CO2平衡分压公式为RCO2,eq=1.16×108exp[-21 399/T];CaO恒温吸收CO2的最终转化率随吸收温度的升高先增加后减小,生物质定向气化中CaO吸收CO2的最佳温度为700～750℃;循环吸收实验中CaO转化率随循环次数增加而减小.%Through biomass directional gasification,we could obtain hydrogen-rich gas and syngas which be used for the synthesis of high valuable chemicals,so it was an effective energy conversion technology.Based on the background of directional biomass gasification and combined with the actual industrial production,we systematically studied the performance of CaO for CO2 absorption at high temperature under biomass directional gasification by investigating the effects of heating rate.The results showed:when the heating rate increased from 10 ℃/min to 50 ℃/min,CO2 absorption reactions bal-anced at 800 ℃ and the CaO conversion decreased with the increase of heating rate.CaO conversion increased with the increase of CO2 concentration.According to the relationship between the concentration of CO2 and temperature when the reactions reached balance,we obtained the fitting formula of the equilibrium partial pressure of CO2:RCO2eq=1.16×108exp [-21 399/T].During the experiments under the constant temperature,the final CaO conversion firstly increased,then decreased with the increase of constant absorbing temperature.The most suitable temperature for CaO absorbing CO2 under biomass directional gasification was between 700 ℃ and 750 ℃.The CaO conversion decreased with the increase of cycling number.