Pyrolysis Of Refinery Dry Gas To Acetylene By Rotating Arc Hydrogen Plasma

Refinery dry gas used as the fuel of gas pipe network or torch is always produced during the secondary petroleum processing,which not only causes serious waste of resources,but also intensifies environmental pollution.Based on the characteristics of high temperature,high enthalpy and strong reaction activity of thermal plasma,we use the rotating arc plasma reactor to investigate the basic rules of preparing acetylene from refinery dry gas through hydrogen plasma pyrolysis technology.It lays the foundation for opening up a new way for the utilization of refinery dry gas.The cracking properties of ethane and ethylene which can not be ignored in refinery dry gas were studied first.Experimental results show that the cracking law of ethane is highly similar but obvious inferior to that of methane.Overall,optimal cracking effect can be reached when the input power is about 16.1 kW and the feed rate remains 6.2 Nm3/h.The percentage of acetylene is 8.3%,the selectivity and yield is 53.6%,52.9%,respectively.The specific energy requirement of acetylene is 19.8 kWh/kg C₂H₂.As for ethylene,the cracking law is different and even worse than that of methane and ethane.The optimum pyrolysis effect?the content of acetylene is 5.4%,the selectivity is 43.4%,the yield of acetylene amount is 34.7%,and the minimum specific energy requirement is 41.1 kWh/kg-C₂H₂?is obtained under the input power of 14 kW and feed rate of 5.1 Nm³/h.The effects of ethane and ethylene on mixed hydrocarbons cracking were studied subsequently.The results show that the cracking law of the former mixture which contains 10%of ethane is similar to that of methane and ethane.Meanwhile,it is found that certain amount of ethane exists in the feedstock can promote the optimization of mixed hydrocarbons to acetylene,therefore the separation of ethane is not necessary before the pyrolysis process.But for the later C₂H₄/CH₄/H₂ mixture,it exhibits a different pyrolysis law from ethylene,and the existence of ethylene is not conducive to the cracking of the mixture.So ethylene is necessary to be removed before the pyrolysis.In the process of cracking the octa-component mixture simulated by FCC dry gas from Funshun Petrochemical Company of PetroChina,high content of acetylene?8.5%?and low content of byproducts such as methane,ethylene,toxic gas hydrogen cyanide can be obtained under the power of 14.5 kW.The selectivity,yield,specific energy requirement of acetylene are 72.7%,43.8%,21.7 kWh/kg C₂H₂,respectively.The effect of feed rate on the pyrolysis process is complex.Overall,optimum cracking result can be obtained when the input power of 14.5 kW and feed rate of 7.6 Nm³/h.