CIESC Journal ›› 2019, Vol. 70 ›› Issue (8): 2928-2937.DOI: 10.11949/0438-1157.20190411

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Characteristic and kinetics of light calcination of magnesite in micro fluidized bed reaction analyzer

Weiwei JIANG1(),Wenqian HAO1,Xuejing LIU1(),Zhennan HAN1,Junrong YUE2,Guangwen XU1,2()   

  1. 1. Institute of Industrial Chemistry and Energy Technology, Laboratory on Resources Chemicals and Materials of Ministry of Education, Shenyang University of Chemical Technology, Shenyang 110142, Liaoning, China
    2. State Key Laboratory of Multi-phase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
  • Received:2019-04-18 Revised:2019-07-01 Online:2019-08-05 Published:2019-08-05
  • Contact: Xuejing LIU,Guangwen XU

微型流化床内菱镁矿轻烧反应特性及动力学

姜微微1(),郝文倩1,刘雪景1(),韩振南1,岳君容2,许光文1,2()   

  1. 1. 沈阳化工大学能源与化工产业技术研究院,资源化工与材料教育部重点实验室,辽宁 沈阳 110142
    2. 中国科学院过程工程研究所多相复杂系统国家重点实验室,北京 100190
  • 通讯作者: 刘雪景,许光文
  • 作者简介:姜微微(1994—),女,硕士研究生,814265991@qq.com
  • 基金资助:
    辽宁省教育厅重点项目(LZ2017001);辽宁省高水平创新团队国(境)外培养项目(2018LNGXGJWPY-ZD002)

Abstract:

The calcination reaction characteristics and reaction kinetics of magnesite powder in nitrogen and air atmosphere were studied by microfluidic bed reaction analyzer (MFBRA) and thermogravimetric analyzer (TGA). It was shown that the activation energy of magnesite calcination measured in nitrogen and air was quite similar, indicating that the oxygen in the air had little effect on the calcination of magnesite. The time for complete decomposition of magnesite in MFBRA was short as a few seconds in MFBRA at temperatures above 800℃, showing its reaction rate much quicker than that in TGA,which revealed the difference between TGA and MFBRA in measuring the reaction kinetics. Both activation energy and pre-exponential factor are significantly lower in MFBRA (about 125 kJ/mol, 105 s-1) than in TGA (about 200 kJ/mol,1015 s-1). The gas product CO2 produced by magnesite decomposition is difficult to fully flow out from the crucible of TGA and thus inhibits the decomposition reaction of magnesite. For MFBRA, it can effectively reduce the inhibition effect from the formed CO2 that easily flows into the main gas flow surrounding the particles. It is also found that the magnesite decomposition reaction follows the nucleation and growth control model in both MFBRA and TGA. Overall, for the reaction in fluidized beds, the study verifies that MFBRA provides a reliable secure of the reaction rate and kinetic parameters for the gas-formation calcination or decomposition reactions like tested light calcination of magnesite.

Key words: fluidized bed, kinetics, magnesite, light calcination, diffusion

摘要:

通过微型流化床反应分析仪(MFBRA)和热重分析仪(TGA)对比研究了菱镁矿粉在氮气和空气气氛中的煅烧反应特性和反应动力学特性。结果表明:菱镁矿在氮气和空气中测得的表观活化能相似,说明空气中的氧气对菱镁矿的煅烧没有影响。MFBRA中菱镁矿粉在800℃以上完全分解的时间只有短短数秒,显著少于在TGA中完全分解的时间,揭示了TGA和MFBRA在测定反应动力学方面的差异。MFBRA测定菱镁矿在空气和氮气气氛中分解的表观活化能(约125 kJ/mol)和指前因子(105 s-1)显著低于TGA所得结果(约200 kJ/mol,1015 s-1),进一步测试表明这与TGA中的反应受气氛抑制有关。即菱镁矿在TGA坩埚内分解产生的CO2不能及时随气流排出,抑制了轻烧反应的进行,而MFBRA可有效降低外扩散对反应的影响。但两种仪器测试的反应均遵循成核与生长控制模型。对于流化床反应,证明了MFBRA测试结果具有更高的准确性,为有气体生成的煅烧或分解反应(如菱镁矿轻烧)提供了可靠的反应测试方法和仪器。

关键词: 流化床, 动力学, 菱镁矿, 轻烧, 扩散

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