Experimental Research On Gliding Arc Cracking Low-calorie Fuel And Stable Combustion

With the rapid development of our country's economy,the demand for energy is increasing.In 2018,our country's external dependence on natural gas consumption was 45.3%,and that of oil was 70.9%,and this value showed an increasing trend year by year.Therefore,it is necessary to develop alternatives to traditional high-quality energy.The blast furnace gas produced by the blast furnace ironmaking process is one of such alternatives.However,in the combustion process of blast furnace gas,there are problems such as poor combustion stability due to its low heating value,and flameout easily occurs.The traditional method to solve the above problems is to use dual fuel nozzles or duty flames,but both will cause a waste of high-quality fuel.The plasma combustion-supporting technology can effectively solve the above problems.Plasma can stabilize combustion from three aspects:thermal effect,chemical effect and transport effect,and does not require additional traditional primary energy.In this paper,the gliding arc is selected as the combustion-supporting plasma,and the gliding arc cracking the incombustible components(the mixture of CO₂ and N₂)in the low calorific value gas and the gliding arc plasma stabilizing combustion of the low calorific value fuel are studied.The main work content and conclusions are as follows:(1)The stability of the gliding arc is studied through experiments,five arc motion states are obtained,and the influence of different input voltages,discharge gaps and gas types on the flow interval of each motion state of the gliding arc is analyzed.Two flow rates are selected as the flow operating point of the cracking test in the stable motion flow range of the gliding arc,and the influence of different input voltages and gas types on the CO₂ cracking effect of the gliding arc is explored.It is concluded that the cracking effect is better when the arc is in the state of uniform motion in the curved arc.Increasing the input voltage may increase the reverse reaction and cause the CO₂ conversion rate to drop.N₂ can effectively promote the cracking of CO₂ and reduce energy consumption.(2)Experiments are carried out on the combustion characteristics of low-calorific value fuels,and five typical flame states of low-calorific value fuel combustion are obtained.The pressure sensor and PMT are used to obtain the thermoacoustic characteristics of low calorific value fuel combustion,and the thermoacoustic characteristics of five typical flame states are analyzed.Experiments are conducted to explore the stabilization effect of gliding arc,and the influence of gliding arc on low calorific value fuel combustion flame shape and thermoacoustic characteristics under different input voltages is obtained,and the combustion interval and flameout limit with or without arc are compared and analyzed.It is concluded that the gliding arc can effectively increase the flame opening angle,shorten the flame length,and improve the combustion stability.The gliding arc can effectively improve the stability of combustion heat release.The gliding arc can broaden the stable combustion range of low-calorific value fuel combustion and the lean-burn flameout limit.