微波复合直流等离子体转化天然气制乙炔的研究

MW-DC Hybrid Plasma Conversion of Natural Gas to Acetylene

利用微波复合直流等离子体对天然气转化制乙炔反应进行了研究.考察了氢烷比、气体流量、功率等参数对装置的能量利用率以及天然气转化反应的影响,并考核了微波复合直流等离子体转化天然气制乙炔工艺的稳定性.实验结果表明:微波复合直流等离子体装置的能量利用率随等离子体工作气体的流量的增加而提高;由于微波的作用使传统直流柱状等离子体分化为多根丝状等离子体,从而使得电极的烧蚀方式由传统的点烧蚀变为面烧蚀,并大幅度提高等离子体转化天然气工艺的稳定性和电极寿命;甲烷的转化率和乙炔的收率随功率的增加而提高,随CH4/H2比和气体流量的增加而降低,在氢烷比为0.9、总气体流量为760L/min、微波源输出电功率6kW、直流电源输出功率90kW时,甲烷转化率可达84.4%,乙炔选择性为75.6%,乙炔收率为63.8%,乙炔能耗达10.8kWh?kg-1;电极寿命超过200h.

The conversion of methane to acetylene in MW (microwave)-DC (direct current) hybrid plasma was studied. The effects of H-2/CH4 ratio, flow rate and power on the reaction and the stability of the device were investigated. The energy efficiency of the MW-DC hybrid plasma device was increased with the increase of the flow rate. The conventional DC plasma column was split into tens of plasma filaments, which changed the erosion mode of the electrode from point erosion to face erosion. The conversion of methane and the yield of acetylene are increased with the increase of the feed power or decrease of the H2/CH4 ratio and flow rate. With a total flow rate of 760 L/min, H-2/CH4 ratio of 0.9, DC power of 90 kW, MW power of 6 kW, the conversion of methane, yield of acetylene and specific energy of requirement (SER) could reach 84.4%, 63.8% and 10.8 kWh center dot kg(-l) respectively. The electrode life was extended to more than 200 h.