铁酸钙与生物质焦的化学链气化反应动力学研究  

Kinetic analysis of biochar chemical looping gasification with calcium ferrite as oxygen carriers

作　　者：高攀[1] 黄星琪 刘禹彤 艾科热木·阿卜来提 杨少霞[2] GAO Pan;HUANG Xing-qi;LIU Yu-tong;ABULAITI Aikeremu;YANG Shao-xia(School of New Energy,North China Electric Power University,Beijing 102206,China;School of water conservancy and Hydropower Engineering,North China Electric Power University,Beijing 102206,China)

机构地区：[1]华北电力大学新能源学院,北京102206 [2]华北电力大学水利与水电工程学院,北京102206

出　　处：《燃料化学学报（中英文）》2023年第9期1259-1272,共14页Journal of Fuel Chemistry and Technology

基　　金：国家自然科学基金(51206045);中央高校基金(2018MS033)资助。

摘　　要：为探究铁酸钙载氧体与生物质焦的化学链气化反应动力学,基于热重实验研究了载氧体和生物质焦种类对反应性的影响,结合XRD、SEM、BET等表征手段对实验现象进行分析,并采用Škvára-Šesták方法确定了动力学机制函数。结果表明,载氧体反应速率Ca_(2)Fe_(2)O_(5)>CaFe_(2)O_(4)>Fe_(2)O_(3),载氧量CaFe_(2)O_(4)>Ca_(2)Fe_(2)O_(5)>Fe_(2)O_(3),生物质焦能够将载氧体完全还原为Fe和CaO;CaFe_(2)O_(4)与生物质焦反应的活化能为167.44–600.83 kJ/mol,Ca_(2)Fe_(2)O_(5)与生物质焦反应的活化能为413.62–583.51 kJ/mol;其中,CaFe_(2)O_(4)在还原的过程中生成了中间体CaFe_(3)O_(5),对晶格氧的扩散有一定的影响;CaFe_(2)O_(4)的还原可分为两阶段,当转化率α小于0.15时,CaFe_(2)O_(4)还原为Ca_(2)Fe_(2)O_(5),还原过程遵循随机成核和核生长模型,当α大于0.15时,进一步还原为CaO和Fe,还原过程遵循三维扩散机制;Ca_(2)Fe_(2)O_(5)的还原机制与CaFe_(2)O_(4)还原的第二阶段相同。The chemical looping gasification(CLG)kinetics of biochars with calcium ferrite as oxygen carriers and the effects of different kinds of calcium ferrite and biochars were investigated by TGA.The properties of biochars and calcium ferrite were analyzed by XRD,SEM,BET,etc.The Škvára-Šesták method was used to determine the kinetic mechanism function.The results show that the reduction reaction rate and the oxygen carrying capacity of oxygen carriers follow the sequence:Ca_(2)Fe_(2)O_(5)>CaFe_(2)O_(4)>Fe_(2)O_(3),and CaFe_(2)O_(4)>Ca_(2)Fe_(2)O_(5)>Fe_(2)O_(3),respectively.The oxygen carriers can be completely reduced to Fe and CaO by biochar.The activation energy of CaFe_(2)O_(4) reduction is in the range of 167.44–600.83 kJ/mol;and the activation energy of Ca_(2)Fe_(2)O_(5) reduction is in the range of 413.62–583.51 kJ/mol.The CaFe3O_(5) generated during the reduction of CaFe_(2)O_(4) may have a negative influence on the lattice oxygen diffusion.The reduction of CaFe_(2)O_(4) can be divided into two stages:when the conversion degreeαis less than 0.15,the CaFe_(2)O_(4) is reduced to Ca_(2)Fe_(2)O_(5) following the random nucleation and nuclei growth model;whenαis greater than 0.15,Ca_(2)Fe_(2)O_(5) is further reduced to CaO and Fe following the 3-D diffusion mechanism.The mechanism function of the reduction of Ca_(2)Fe_(2)O_(5) is the same as that of the second stage of CaFe_(2)O_(4) reduction.

关 键 词：化学链气化 铁酸钙 生物质焦 动力学 

分 类 号：TK6[动力工程及工程热物理—生物能]