麦秆添加大量CaO热解的TG-FTIR实验研究

TG-FTIR Study on Pyrolysis of Wheat-Straw with Abundant CaO Additives

利用热重-傅里叶变换红外光谱联用方法研究添加CaO对麦秆热解过程和挥发份析出特性的影响。热重和红外光谱分析均表明添加CaO后麦秆热解呈现两个明显的失重和挥发份析出阶段,而纯麦秆热解则只有一个。CaO在第一阶段不但能够吸收CO2,而且能够降低甲苯、苯酚和蚁酸等焦油类物质的产生,使得该阶段失重率和最大失重速率随CaO添加量增加而减小。CaCO3的煅烧分解是添加CaO麦秆热解第二阶段产生的原因,该阶段失重率和最大失重速率随CaO添加量增加而增大。研究结果表明,在采用生物质为原料的零排放系统中添加CaO有利于捕获CO2和减少焦油物质的产生,系统的气化温度应适当降低以防止CaCO3的煅烧分解。

Biomass pyrolysis in presence of abundant CaO additives is a fundamental process prior to CaO sorption enhanced gasification in biomass-based zero emission system.In the present study,thermogravimetric Fourier transform infrared（TG-FTIR） analysis was adopted to examine the effects of CaO additives on the mass loss process and volatiles evolution of wheat-straw pyrolysis.Observations from TG and FTIR analyses simultaneously demonstrated a two-stage process for CaO catalyzed wheat-straw pyrolysis,different from the single stage process for pure wheat-straw pyrolysis.CaO additives could not only absorb the released CO2 but also reduce the yields of tar species such as toluene, phenol,and formic acid in the first stage,resulting in decreased mass loss and maximum mass loss rate in this stage with an increase in CaO addition.The second stage was attributed to the CaCO3 decomposition and the mass loss and maximum mass loss rate increased with increasing amount of CaO additives.The results of the present study demonstrated the great potential of CaO additives to capture CO2 and reduce tars yields in biomass-based zero emission system.The gasification temperature in the system should be lowered down to avoid CaCO3 decomposition.