Study Of The Impact Of Alkali On Slagging During Biomass Combustion

The text selects corn straw as the research object,and it is washed by water and hydrochloric acid.First,analyze the corn straw by proximate analysis,elemental analysis and SEM-EDS analysis.The results show that water pretreatment remove the clay and the dust on surface,reduce the ash content;Acid-washing pretreatment reduce most metallic element content,K element content reduce from 0.94% to 0.36%.Then,the corn straw ash was prepared in a muffle furnace at 600 ?,analyze micro topography and elementary composition by SEM-EDS,measure oxide content of ash by XRF,and measure the ash fusion point.The results show that the major component of ash are potassium oxide and silicon oxide,acid-washing pretreatment has no effect on Si element,K element reduced obviously;K element separate out at high temperature and consist in outside surface in the shape of granule.K element increase cohesiveness and adhere to surface of ash with the oxide of Si and Ca;acid-washing increase the characteristic temperature.One more,respectively add K₂CO₃,KOH to ash and add KOH to straw,measure the ash fusion point.The results show that K₂CO₃ and KOH react with acidic oxide to form lowmelting-point matter at high temperature,K element is important factor to influence ash fusion point,acid-washing pretreatment increase ash fusion point.When the content of K element in ash is 30%,ash fusion point is at a minimum.Moiety of K element volatilize during combustion process of biomass as the flue gas.Finally,mixture the coal and the corn straw in different ratio,and is burned to ash in a muffle furnace.Analyze the component of ash and measure the ash fusion point.The results show that the contents of alkali and alkaline-earth metals of coal ash is very few;the Rb/a of coal and compounds are 0.15⁰.75,present rising trend;with the content of corn straw increases,the ash fusion point reduces,and slag easily.