Abstract: The pyrolysis of coal tar using thermal plasma provides a direct and cleaner route to produce acetylene with low hazardous emission, since the ultra-high temperatures and concentrated active species in thermal plasma can easily decompose solid/liquid/gas feedstock into smaller molecules. Experiments were carried out in a lab-scale thermal plasma test platform to investigate the effects of key operating conditions including the sample inject temperature, plasma atmosphere, and coal tar specific enthalpy on the performance of coal tar pyrolysis. The results demonstrated that coal tar can be rapidly cracked to acetylene and other light gases in the thermal plasma reactor. The viscosity of coal tar can be decreased by pre-heated, thereby increasing the mix efficiency between coal tar and thermal plasma jet. The increased hydrogen concentration in plasma working gases improves the coal tar conversion and the yield of acetylene, and reduces coking as well. Higher specific input power of coal tar leads to higher coal tar conversion, acetylene yield and the yields of light gases. 86.3% coal tar conversions, 24.6% acetylene yields and 51.7% yield of light gases were obtained in the optimal experiment. In addition, plasma pyrolysis process can generate ethylene as by-products, and the concentration ratio of ethylene to acetylene can be used to predict the gas reaction temperature.

Key words: pyrolysis, coal tar, thermal plasma, multiphase reaction, chemical reactors

摘要： 利用热等离子高温、高焓等特性热解煤焦油制乙炔是一条清洁高效的乙炔生产技术。在实验室对热等离子体热解煤焦油反应中的原料进样温度、反应气氛、输入比焓等关键因素展开了研究。结果表明，热等离子体可将煤焦油直接转化为乙炔及其他小分子气态产品，预热煤焦油可改善其流动性从而提高煤焦油和等离子体射流的初始混合效率；氢等离子体的加入可显著提高煤焦油转化率和乙炔收率并减少结焦；随着输入比焓的增加，煤焦油转化率、乙炔收率和气态产品总收率均得到提高。在实验中得到的煤焦油转化率最高为86.3%，乙炔收率最高为24.6%，气态产品总收率最高为51.7%。煤焦油在热等离子体的热解过程中副产乙烯，乙烯收率达到7.9%。乙炔收率和乙烯收率的比值可用于预测气相体系温度。

关键词: 热解, 煤焦油, 热等离子体, 多相反应, 化学反应器