热等离子体煤制乙炔裂解气烃类循环过程分析

Process analysis of effluent hydrocarbon recycling for coal pyrolysis to acetylene in thermal plasma

针对等离子体煤裂解制乙炔过程,提出了将过程裂解气中副产的烃类分离,循环输入等离子体反应器的新型工艺流程。基于新疆天业2 MW示范平台装置的典型运行参数,采用热力学分析手段,理论上分析了该工艺流程对于体系乙炔产量、单位质量乙炔煤耗和裂解电耗等的影响。结果表明,裂解气烃类循环可以有效提高裂解气中乙炔浓度和产率,同时减少煤粉输送气等流程气体的使用。典型操作条件下,采用裂解气烃类循环工艺可以增加35.6%的乙炔收率和13.4%的氢气收率,降低30%的单位乙炔煤耗和裂解电耗,是高效可行的优化方案。

Coal pyrolysis via thermal plasma provides an alternative path to realize the effective conversion from coal to acetylene. Recycling the hydrocarbons in the effluent gas to the plasma pyrolysis process is proposed in this work to improve the reactor performance. Thermodynamic analysis is made as the reference on the basis of the pilot-plant results of Xinjiang Tianye 2 MW plasma pyrolysis device. The comparison results show that the recycling of effluent hydrocarbons（except acetylene） can raise the volume fraction and mass flow rate of acetylene in the product gas. The hydrocarbons in cracked gas is ample to be used as the conveying and accelerating gas for coal and the protecting gas for plasma torch, which can reduce the input amount of working gas and optimize the whole gas flow of the process. Different optimization cases are discussed to compare the products（i.e., acetylene and hydrogen） output and the gas input of the thermal plasma pyrolysis system. The optimized results show that the recycling process is feasible and effective, with reduced coal consumption（30%） and pyrolysis energy consumption（30%） as well as increased acetylene yield（35.6%）.