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%).