Abstract:

The pyrolysis characteristics of Naomaohu coal were studied in a moving bed reactor with internals consisting of multi-stage baffles and multi-stage gas outlet lines, and compared with the coal pyrolysis behavior in conventional fixed bed reactor. The effects of heat transfer rate and pyrolysis temperature on products yield, pyrolysis gas composition, and tar composition and quality were investigated in the two reactors. The results showed that the heating time of coal particles in the moving bed reactor with internals was shortened by more than 60% than that of the fixed bed ne during pyrolysis at 450℃, and the internals can significantly enhanced the heat transfer rate of the particles in reactor. With increasing pyrolysis temperature, the ratio of C₂H₄/C₂H₆ and C₃H₆/C₃H₈ in pyrolysis gas increased, the secondary reaction of volatiles increased, but the degree of cracking was lower than that of fixed bed reactor. The tar yield in the moving bed reactor with internals increased first and then decreased with increasing temperature, and reached a maximum mass ratio of 10.8% at 550℃, which was about 28.6% higher than that of the fixed bed one. When the pyrolysis temperature was higher, the content of asphaltene components in the tar produced by the moving bed reactor was lower. At 750℃, the mass ratio of light components in tar reached 85.17% and the content of aliphatic hydrocarbons decreased to 28.00%. Compared with the fixed bed reactor, the role of internals (multi-stage baffles and gas outlet lines) in regulating the pyrolysis reaction of Naomaohu coal and improving the yield and quality of pyrolysis tar was revealed in the moving bed reactor.

Key words: moving bed, pyrolysis, heat transfer, mass transfer, internals, tar quality, regulation

摘要：

在外热式内构件（多级折流板和多段集气管）移动床反应器内研究了淖毛湖煤的热解特性，并与常规固定床反应器中煤热解行为进行对比，考察了两反应器内的传热速率以及热解温度对产物分布、热解气组成、焦油组成和品质等影响规律。结果表明：在450℃低温热解时，煤颗粒在内构件移动床内的升温时间比固定床缩短了60%以上，内构件具有显著提高反应器内颗粒间传热速率的作用。随着热解温度的升高，热解气中的C₂H₄/C₂H₆和C₃H₆/C₃H₈的比值变大，挥发分的二次反应程度加大，但裂解程度低于固定床。内构件移动床中的焦油产率随温度的升高先增加后降低，在550℃时达到最高为10.8%（质量分数），比固定床增高约28.6%。当热解温度越高时，移动床所产焦油中的沥青质组分含量越低，在750℃时焦油中轻质组分质量分数达到85.17%，脂肪烃含量降低到了28.00%。通过与固定床对比，揭示了内构件（多级折流板和集气管）调控淖毛湖煤热解反应并提高热解焦油产率和品质的作用。

关键词: 移动床, 热解, 传热, 传质, 内构件, 焦油品质, 调控