On The Preparation Of Acetylene And Ethylene From Natural Gas In Nitrogen Plasma Jet

Chemical Engineering Postgraduate: Guo Chunwen Supervisor: Dai Xiaoyan, Yin YongxiangIn this article, a new technique-the preparation of acetylene and ethylene from natural gas in nitrogen thermal plasma is studied.By theoretical analysis on the pyrolysis reactions of natural gas and hydromechanical simulation on the reactor, carbon sediment phenomenon on the cathode can be avoided if changing the natural gas feed manner,and carbon sediment phenomenon in the reactor can be restrained if optimizing the shape of the reactor, and the quenching position in the reactor is determined.On the basis of theoretical research on the reactions, optimizing reactor and changing the gas-feed manner, the conversion of natural gas to acetylene and ethylene is experimentally studied in a DC thermal plasma reactor at above atmospheric pressure. Using nitrogen plasma as shooting gas, natural gas is injected into the inlet of the reactor from radius direction. The effect of power, natural gas and nitrogen flow rate on natural gas conversion, acetylene and/or ethylene selectivity and/or yield, and acetylene concentration in product gas phase have been investigated. It shows that, during 5~15KW power input, for obtaining maximum acetylene yield, the flow rate ratio of natural gas to nitrogen should be 1:1.8; for obtaining maximum acetylene selectivity, the ratio should be 1:1. When the power input is 5KW, the best results were the conversion of natural gas 72. 7%, yield of acetylene 37. 8%, the volume concentration of acetylene in the product gas 15. 3% excluding nitrogen. It also shows that, the C2 yield will decrease and natural gas will notpyrolysized sufficiently if the flow rate of natural gas or nitrogen is excessive, so nitrogen flow rate and natural gas flow rate should be compatible with power input. In these experiments, carbon sediment phenomenon is not visible.According to hydrodynamics simulation, in order to avoid carbon sediment at the inlet end of the reactor, the reactor should be olive type.