超高温等离子体气化熔融对垃圾焚烧飞灰的影响

Influence of ultra-high temperature plasma gasification and melting on municipal solid waste incineration fly ash

近年来我国垃圾焚烧无害化处理量逐年递增,伴随垃圾焚烧后产生的飞灰量日益增长,而飞灰中的重金属等有害物质会污染环境。以太原市某垃圾发电厂产生的垃圾焚烧飞灰为研究对象,在中试现场利用超高温等离子体气化熔融炉在1700℃下分别对灰/焦(6∶1)和灰/焦(9∶1)的样品进行熔融处理,利用XRF、XRD和SEM-EDS对垃圾焚烧飞灰和熔融后的玻璃熔渣进行物质组成、微观结构和元素分布的表征与分析。研究表明,垃圾焚烧飞灰中的金属氯化物多以NaCl、KCl等形式存在,占飞灰组分的5%左右,高温熔融有助于垃圾焚烧飞灰中氯盐的气化,降低垃圾焚烧飞灰中氯盐含量。飞灰多以絮状和球状为主,表面富集了众多金属元素,高温熔融可以对飞灰中酸性氧化物SiO_(2)进行重组,实现对重金属的包裹。熔融后的玻璃熔渣浸出量低于各国浸出毒性标准。在1700℃下高温熔融会使炉体内部的耐高温材料ZrO_(2)发生脱落,缩短使用周期。碱度系数是影响熔融温度的主要原因,适当减小碱度系数可以降低熔融温度,需要进一步调整碱度系数从而降低炉内熔融温度,延长ZrO_(2)的使用寿命。因此,熔融处理前,可测定样品的灰熔点特征温度,据此设定熔融炉的熔融温度,避免因温度过高导致隔热材料的脱落。

In recent years,the amount of harmless waste incineration treatment in China has been increasing year by year.With the increasing amount of fly ash generated after garbage incineration,the heavy metals and other harmful substances in fly ash have great pollution to the environment.Taking the municipal solid waste incineration(MSWI)fly ash produced by a municipal solid waste power plant in Taiyuan as the research object,The samples of ash/coke(6∶1)and ash/coke(9∶1)were melted at 1700℃in an ultra-high temperature plasma gasification melting furnace,and the composition,microstructure and element distribution of MSW fly ash and molten glass slag were characterized and analyzed by XRF,XRD and SEM-EDS.The study shows that the metal chlorides in the fly ash of MSWI mostly exist in the form of NaCl and KCl,accounting for about 5%of the composition of the fly ash.High temperature melting is conducive to the gasification of chlorine salt in the fly ash of MSWI,and the content of chlorine salt in the fly ash of MSWI is reduced.The fly ash is mainly flocculent and spherical,and the surface is enriched with many metal elements.can The acid oxide SiO_(2) in the fly ash can be recombined by the high temperature melting,which realize the encapsulation of heavy metals.The leaching amount of molten glass slag after melting is lower than the leaching toxicity standard of various countries.The high temperature melting at 1700℃will make the high temperature resistant material ZrO_(2) fall off inside the furnace,leading to a shorter service cycle.The basicity coefficient is the main reason affecting the melting temperature.The reduction of basicity coefficient can reduce the melting temperature.It is necessary to further adjust the basicity coefficient so as to reduce the melting temperature in the furnace and extend the service life of ZrO_(2).Therefore,before melting treatment,the characteristic temperature of the ash melting point of the sample can be determined,and the melting temperature of the melting furnace can be set accordingly to avoid the falling off of the insulation material due to the high temperature.