Study On Alkali Metal And Chlorine Coupling Corrosion In Solid Waste Incinerator

In the recycling of solid waste,solid waste incineration has become the important way.But the coupling alkali metal and chlorine corrosion limits the application of the technology promotion.In order to study the alkali metal and chlorine coupling corrosion mechanism and influencing factors,this article focus on agricultural waste with high alkali metal and chlorine.the relevant study on the coupling corrosion.The fly ash after biomass combustion will lead to the deposition and slagging of solid waste boiler superheater and the occurrence of high-temperature corrosion.What's more.The two processes will affect and promote each other,resulting in the boiler superheater tube explosion accident,seriously threatening the stability and safety of boiler operation.Based on multiple power plant superheater tube project example,to explore the common problems of corrosion,to conduct simulation in the laboratory and thermodynamic calculation simulation software,to investigate the precipitation and deposition characteristics of caustic components such as alkali metals and chlorine when the temperature of flue gas,fuel Chemistry and atmosphere change,and conduct simulation analysis of high-temperature corrosion during combustion.The main research contents are as follows:1.For multiple power plant heating surface corrosion and fuel samples,using industrial analysis,element analysis and ash composition analysis methods to analyze the characteristics of the fuel,and use the phase analysis?XRD?,element analysis?EDS?,scanning electron microscope?SEM?,and other physical and chemical means analysis section of corrosion,and the corrosion mechanism was comprehensively studied.The results showed that the alkali metal and chlorine content of the fuel of the agricultural waste power plant exceeded the warning line of slagging and corrosion,which easily caused ash accumulation and slagging on the heating surface,and caused serious corrosion at high temperature.However,in the industrial waste power plant,there is a high content of alkali metal and element S in the fuel,and a high content of Cl on the surface of the corroded pipe section.It is speculated that the corrosion behavior is mainly caused by the combined action of alkali metal,Cl and S.2.In order to study the high temperature corrosion of solid waste boiler,a high temperature corrosion simulation system was built.high temperature corrosion simulation system with controllable temperature of pipe furnace provides the solid waste boiler high temperature environment.The power plant fly ash smear evenly on the metal plate on the simulation of solid waste boiler superheater surface dust,and use the cylinders made HCl,O₂,N₂ mixed gas and water vapor to simulate the solid waste boiler flue gas atmosphere.The experimental results show that,in the study of corrosion characteristics,?1?temperature has a significant impact on the corrosion rate of metal.At different temperatures,the corrosion law is parabolic.When the temperature is lower than 450?,the corrosion rate is lower.When the temperature reaches the"inflection point"of 550?.The corrosion rate will change from slow growth to accelerated growth.?2?metal materials also have a great influence on the corrosion rate of metal.Alloy steel?such as 12CrMoVG?and carbon steel?such as 20G?have similar corrosion rates.And stainless steel?such as:TP304H?shows better corrosion resistance.?3?the type and content of alkali metals also have a certain influence on the corrosion rate.The higher the content of alkali metals is,the faster the corrosion rate is.The effect of KCl on corrosion rate was slightly higher than that of NaCl.3.According to the thermodynamic equilibrium calculation results,temperature change has a great impact on the existence form and content of alkali metal K/Na.At about 600?,gas phase NaCl and KCl begin to appear.At the same temperature,when the excess air coefficient A<1,with the increase of the excess air coefficient,HCl content first increases rapidly and then flattens out.However,when A?1,the content of HCl had almost no difference at the same temperature.When the Cl content is low,the sediments are dominated by the carbonate of alkali metals,with a small amount of alkali metal chlorides,and the high-temperature corrosion is relatively light.However,with the increase of Cl content,the carbonate of alkali metals is completely transformed into the chloride of alkali metals,and the high-temperature corrosion is serious with the increase of gas phase HCl concentration.