Effects of pyrolysis temperature and atmosphere on rapid coal pyrolysis in transport bed reactor

doi:10.11949/j.issn.0438-1157.20161270

Abstract

Abstract:

The effects of pyrolysis temperature and atmosphere on rapid pyrolysis of Buliangou subbitumibous coal were investigated in a transport bed reactor with a continuous feeding of 1.2 kg·h^-1. Under N₂, tar yield increased rapidly with raising temperature to a peak value of 10.3% (daf) at 600℃, and then decreased due to its secondary reactions. Correspondingly, char yield displayed a continued slowdown while gas yield and gas to tar ratio increased with increasing temperature. Higher temperature promoted the release and secondary reactions of volatiles. Part of solid and liquid products were converted into gas products, in which the yields of H₂, CH₄, C₂H_2, etc. increased. At 700℃, H₂ could inhibit volatiles secondary reactions and happen to be free radical stabilizer and hydrogenation agent, well encouraging tar production, especially for light tar, and CH₄ formation. Under CO atmosphere, both light tar and heavy tar yields increased slightly. CO₂ and steam could enhance tar cracking, in particular for heavy tar, thus improving tar quality but causing the reduction of tar yield. CH₄ enhanced the formation of heavy tar and brought about an increase in tar yield.

Key words: pyrolysis, coal, atmosphere, transport bed, tar, reaction, syngas

摘要：

在连续进料量为1.2 kg·h^-1的输送床反应器中考察了热解温度和反应气氛对不连沟次烟煤快速热解的影响。N₂气氛下，随着煤热解温度升高，焦油产率先增加后减小，600℃时达到最大值10.3%；对应的半焦产率下降，气体产率以及气油比增加。高温促进了煤挥发分的释放以及挥发分在气相中的二次反应，部分产物从固相和液相产品转化为气相产品，氢气、甲烷和乙烯等气体组分的产率明显增加。700℃下，H₂气氛能够抑制挥发分二次反应的发生，起到稳定自由基和加氢的作用，显著提高焦油产率和油品品质，同时有利于甲烷的生成。CO气氛在一定程度上同时提高了轻质和重质焦油产率。CO₂和水蒸气能够促进焦油的二次反应，特别是重质焦油的裂解，具有一定的提质作用，但会导致焦油产率下降。CH₄气氛促进了重质焦油组分的生成，使得热解焦油产率提高。

关键词: 热解, 煤, 气氛, 输送床, 焦油, 反应, 合成气

CLC Number:

TQ530.2

CHEN Zhaohui, DUN Qimeng, SHI Yong, GAO Shiqiu. Effects of pyrolysis temperature and atmosphere on rapid coal pyrolysis in transport bed reactor[J]. CIESC Journal, 2017, 68(4): 1566-1573.

陈兆辉, 敦启孟, 石勇, 高士秋. 热解温度和反应气氛对输送床煤快速热解的影响[J]. 化工学报, 2017, 68(4): 1566-1573.

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