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

Q3 Energy

燃料化学学报 Pub Date : 2023-09-01 DOI:10.1016/S1872-5813(23)60356-1

Pan GAO , Xing-qi HUANG , Yu-tong LIU , Aikeremu ABULAITI , Shao-xia YANG

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引用次数: 0

Abstract

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: Ca₂Fe₂O₅ > CaFe₂O₄ > Fe₂O₃, and CaFe₂O₄ > Ca₂Fe₂O₅ > Fe₂O₃, respectively. The oxygen carriers can be completely reduced to Fe and CaO by biochar. The activation energy of CaFe₂O₄ reduction is in the range of 167.44–600.83 kJ/mol; and the activation energy of Ca₂Fe₂O₅ reduction is in the range of 413.62–583.51 kJ/mol. The CaFe₃O₅ generated during the reduction of CaFe₂O₄ may have a negative influence on the lattice oxygen diffusion. The reduction of CaFe₂O₄ can be divided into two stages: when the conversion degree α is less than 0.15, the CaFe₂O₄ is reduced to Ca₂Fe₂O₅ following the random nucleation and nuclei growth model; when α is greater than 0.15, Ca₂Fe₂O₅ is further reduced to CaO and Fe following the 3-D diffusion mechanism. The mechanism function of the reduction of Ca₂Fe₂O₅ is the same as that of the second stage of CaFe₂O₄ reduction.

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铁酸钙为氧载体的生物炭化学环气化动力学分析

采用热重分析仪研究了以铁酸钙为氧载体的生物炭的化学环气化动力学，以及不同种类铁酸钙和生物炭对化学环气化的影响。采用XRD、SEM、BET等分析了生物炭和铁酸钙的性质。采用Škvára-Šesták法确定其动力学机理函数。结果表明，氧载体的还原反应速率和载氧能力顺序为:Ca2Fe2O5 >CaFe2O4祝辞Fe2O3和CaFe2O4 >Ca2Fe2O5祝辞分别Fe2O3。生物炭可以将氧载体完全还原为Fe和CaO。CaFe2O4的还原活化能在167.44 ~ 600.83 kJ/mol之间;Ca2Fe2O5的还原活化能在413.62 ~ 583.51 kJ/mol之间。CaFe2O4还原过程中产生的CaFe3O5可能对晶格氧扩散产生负面影响。CaFe2O4的还原可分为两个阶段:当转化率α < 0.15时，CaFe2O4遵循随机成核和核生长模式还原为Ca2Fe2O5;当α大于0.15时，Ca2Fe2O5进一步还原为CaO和Fe。Ca2Fe2O5的还原机理与CaFe2O4的第二阶段还原作用相同。

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来源期刊

燃料化学学报 Chemical Engineering-Chemical Engineering (all)

CiteScore

2.80

自引率

0.00%

发文量

5825

期刊介绍： Journal of Fuel Chemistry and Technology (Ranliao Huaxue Xuebao) is a Chinese Academy of Sciences(CAS) journal started in 1956, sponsored by the Chinese Chemical Society and the Institute of Coal Chemistry, Chinese Academy of Sciences(CAS). The journal is published bimonthly by Science Press in China and widely distributed in about 20 countries. Journal of Fuel Chemistry and Technology publishes reports of both basic and applied research in the chemistry and chemical engineering of many energy sources, including that involved in the nature, processing and utilization of coal, petroleum, oil shale, natural gas, biomass and synfuels, as well as related subjects of increasing interest such as C1 chemistry, pollutions control and new catalytic materials. Types of publications include original research articles, short communications, research notes and reviews. Both domestic and international contributors are welcome. Manuscripts written in Chinese or English will be accepted. Additional English titles, abstracts and key words should be included in Chinese manuscripts. All manuscripts are subject to critical review by the editorial committee, which is composed of about 10 foreign and 50 Chinese experts in fuel science. Journal of Fuel Chemistry and Technology has been a source of primary research work in fuel chemistry as a Chinese core scientific periodical.