Study On Melting Properties And Behavior Of Incineration Ash During Gasification And Melting Process Of Municipal Solid Waste

To deal with the MSW with direct gasification and melting technology could avoid secondary pollution coused by MSW disposal, and melting slag in gasification and melting process could make into building material to be utilized, so it could achieve the"Reduction, Harmless, Recycling"of MSW disposal. In this paper, experimental study and theoretical analysis were adopted to study the melting behavior and properties of incineration ash, and analyze the temperature of furnace ,melting point and viscosity of incineration ash, appropriate coal ratio and blast air conditions were acquired.①The analysis results of Chongqing MSW and anxiliary fule show that Chongqing MSW's moisture content is high, the calorific value is low and not suit for traditional low-temperature incineration. The composition of incineration ash of MSW and coal were Si02,Al2O3,CaO,Fe2O3 whose total acount for their respective ash composition are 82.9%and 88.8%,and a little oxides of Mg,K,Na,Ti,S in ash.②The DSC study of incineration ash show that the addition of coal ash will cause decrement of latent heat and cause increment of average specific heat of MSW incineration ash. The latent heat of experimental ash is 145.3~252.6KJ/Kg and average specific heat is 1.06~2.36KJ/Kg·℃③The study of melting point and viscosity of incineration ash show that the molting point of incineration ash will increase as the coal ratio increase and additional CaO. Incineration ash's viscosity and activation eneygy of viscous flow will increase as the coal ratio's increment. Add a certain amount CaO into the ash when coal ratio is 20%will decrease the viscosity of ash, but it will increase ash's melting point, so it is not appropriate to add CaO.④The melting behavior study of incineration ash show when coal ratio is low(20%), the maJor phase of ash are potssium mica, belite and so on whose melting point are relatively low, so it's more easily for ash melting and tapping. After increasing coal ratio to 50% or adding CaO into the ash, the low melting point phase in the ash will decrease and high melting point phase such as calcium silicate, fayalite, gehlenite phase will increase in ash, sothat melting point of incineration ash will increase and liquidity will be worse, in this case it's not conductive to melting and topping of molten ash. Base on the phase change before and after ash melting, the paper infers the maJor reaction equation in incineration ash among melting process. ⑤The theoretical calculation of the temperature and the analysis showe that coal ratio, blast air temperature and oxide contents in blast air have significant influence on melting furnace temperature, and oxide contents in blast air has maximun effect on temperature of furnace, followed by coal ratio, the third is blast air temperature. To dispose of Chongqing MSW with direct gasification and melting technology, 20% is the optimal coal ratio. Under this condition, in order to achieve the requirement temperature for melting and tapping of molten incineration ash, blast air conditions need to meet the following requirements: When oxide content is 21%, blast air's temperature need higher than 400℃, when oxide content is 24%, blast air's temperature need higher than 200℃, and when oxide content is more than 27%, blast normal temperature air is suitable.