厨余沼渣与城市生活垃圾混合燃烧过程的灰熔融特性

ASH FUSION CHARACTERISTIC OF FOOD WASTE DIGESTATE AND MUNICIPAL SOLID WASTE DURING CO-COMBUSTION PROCESS

针对厨余沼渣与城市生活垃圾中灰分含量高、易结渣结焦的问题,通过XRF、XRD、SEM表征及灰熔融特征温度测量、热力学平衡计算,对其混合燃烧的灰熔融特性及矿物转化规律进行研究。结果表明:厨余沼渣灰渣的主要矿物组成为磷酸盐、硅酸盐。城市生活垃圾的灰分则主要由SiO_(2)、CaO、MgO等氧化物与氯化盐构成。磷酸钙和霞石发生低温共熔反应是厨余沼渣灰渣固相组分含量迅速下降的主要原因。城市生活垃圾灰渣在熔融过程中会产生难溶矿物Ca_(4)Si_(2)O_(8)-Ca_(3)P_(2)O_(8),导致灰熔融温度上升。随着城市生活垃圾占比增大,变形温度不断增大,软化温度(ST)、半球温度(HT)、流动温度(FT)先减小后增大。当厨余沼渣的混合比例<10%时,ST、HT和FT均>1400℃,结渣指数Fs均>1342,表现出较弱的结渣倾向。该研究结果可为厨余沼渣在城市生活垃圾焚烧厂中协同处置提供参考。

Aiming at the high ash content and slagging problem of food waste digestate(FWD)and municipal solid waste(MSW),the ash fusion characteristic and mineral transformation law of FWD and MSW during co-combustion process were studied by XRF,XRD,SEM,ash fusion temperature measurement and thermodynamic equilibrium simulation.Results showed the main minerals in FWD ash were phosphate and silicate.MSW ash was mainly composed of oxide,such as SiO_(2),CaO and MgO,and chloride.The low-temperature eutectic reaction occurred between calcium phosphate and nepheline resulting in the rapid decrease of the solid phase in FWD ash.Refractory mineral,Ca_(4)Si_(2)O_(8)-Ca_(3)P_(2)O_(8)was generated during the melting of MSW ash,which led to the increase in ash fusion temperature.With the increase of MSW proportion,the deformation temperature increased,but softening temperature(ST),hemisphere temperature(HT),and flow temperature(FT)first decreased and then increased.When the proportion of FWD was less than 10%,the ST,HT and FT all exceeded 1400℃,and the slagging index Fs was greater than 1342,showing a weak slagging tendency.The results of this paper would play a guiding role in the collaborative disposal of food waste digestate in municipal solid waste incineration plants.