Experimental Study On The Characteristics Of Discharge And Electrostatic Precipitation For High Temperature Pyrolysis Gas

High temperature electrostatic precipitation is the key technology of coal poly-generation system.Compared with other high temperature precipitation technology,electrostatic precipitation technology has the characteristics of lower energy consumption,lower system pressure drop,which has a great development space.Focusing on high temperature electrostatic pricipitation technology,this paper explored the discharge and dust removal characteristics of air,pyrolysis gas and its main components at high temperature,and analysis the influence such as temperature,gas compositions on high temperature electrostatic precipitation,which provided the basis for the application of high temperature electrostatic precipitation technology in coal poly-generation system.First of all,this thesis studied negative DC discharge characteristics in the atmosphere of air,main components of pyrolysis gas?CH₄,H2,N₂,Co2,CO?in a small wire-cylinder discharge device at room temperature?20??and 350-600?.The results showed that both CO₂ and air are electronegative gases,and the discharge characteristics of them are similar.As a non-electronegative gas,N₂ and H2 are relatively close to the discharge characteristics,and their discharge current is much higher than that of air and CO₂.Although CO is an electronegative gas,it has a weak electronegativity,which is close to N₂ and H2 at high temperature,and black solid material will be formed on the anode tube during discharge.In the process of discharge at the atmosphere of CH₄,a network of carbon is formed in the cathode.With temperature rising,the discharge current increases,but different gases have different levels of electrical current rising,and the orders from high to low are:CO>negative electricity gas?air,CO₂?>non-electric negative gas?CH₄,H2 and N₂?.Secondly,this thesis studied the negative DC discharge characteristics in the atmosphere of air,CO₂,N₂ and pyrolysis gas?CNG:40%,H2:40%,CO₂:10%,CO:10%,N₂:10%?in the electrostatic precipitator at the temperature of 300-700?,and explored the influence of the content of the main electronegative CO₂ on the pyrolysis gas discharge characteristics.The results showed that C and H2o are formed during the discharge process in the atmosphere of pyrolysis gas.The discharge characteristic of pyrolysis gas is similar to that of N₂,but there is a buffer when the voltage is low,and then it enters the glow discharge rapidly.The larger the CO₂ concentration in pyrolysis gas,the smaller the discharge current,the more stable the discharge,but the influence of CO₂ concentration on pyrolysis gas discharge current gradually decreases with increasing temperature.Finally,this thesis studied the high temperature electrostatic precipitation characteristics in the atmosphere of pyrolysis gas,air and N₂ at 400-600?.The results showed that the collection efficiency in the atmosphere of air,pyrolysis gas and N₂ were decreased with the increasing of temperature,and the collection efficiency drop in air was slower than N₂ and pyrolysis gas.Under the same temperature and voltage,the collection efficiency in air has the highest value,followed by pyrolysis gas,and N₂ is the lowest.The dust removal characteristics in the atmosphere of pyrolysis gas and N₂ are similar,which are characterized by high energy consumption and low collection efficiency in negative DC electrostatic precipitator.With voltage increasing,the collection efficiency in the atmosphere of air increases,and its growth trend gradually decreases,and the collection efficiency in the atmosphere of N₂ increases linearly,and the collection efficiency in the atmosphere of pyrolysis gas has a process of decreasing and then increasing.