餐厨垃圾水热炭化产物分配规律及液固产物特性研究

以实采餐厨垃圾为对象, 探究了3种反应强度(“温和”180℃-1h、“中等”220℃-2h和“剧烈”260℃-4h)下餐厨垃圾水热炭化三相产物分配规律及液固产物特性.结果表明, 反应强度显著影响产物分配.随反应强度提升, 固相产物(水热炭)产率先上升后下降; 液相产物(炭化液)产率先降低后趋于稳定; 而气相产物产率持续上升.但无论何种强度, 产物均以水热炭(40.4%~52.1%)和炭化液(38.3%~57.5%)为主, 仅有少部分转移至气相产物(2.1%~13.3%)中.此外, 反应强度显著影响所得炭化液和水热炭特性.随反应强度提升, 炭化液pH值逐渐提升、COD和sCOD含量逐渐降低, 而电导率值则表现出先降低后升高的变化趋势.进一步分析表明, 炭化液中含有丰富的醛类、酮类和挥发性脂肪酸(VFAs)类物质.随反应强度提升, 水热炭表面更加粗糙、复杂, 比表面积逐渐提升.同时, 水热炭化反应有助于餐厨垃圾中碳元素在水热炭中的富集, 且富集程度随反应强度提升而显著增加.因具备较低H/C和O/C值、和烟煤相似的热值(23.9 ~ 28.3MJ/kg), 以及较高的点火温度(267.5 ~ 302.3℃), 水热炭具有作为安全的清洁燃料进行能量利用的潜力.

The product distribution of hydrothermal carbonization of food waste and the characteristics of liquid-and solid-products

The food waste (FW) collected from a canteen was treated by hydrothermal carbonization (HTC) under three different process conditions: mild (180℃-1h), intermediate (220℃-2h) and severe (260℃-4h), to explore the effects of process severity on the distribution of HTC three-phase products and the characteristics of liquid and solid products. The results showed that the process severity significantly influenced the product distribution. With the increase of the process severity, the yield of hydrochar increased initially and then decreased, the yield of carbonization liquid decreased initially and then stabilized, while the yield of gas product kept increasing. However, despite of different process severities, the HTC products were mainly in the form of hydrochar (40.4%~52.1%), of carbonization liquid (38.3%~57.5%), with a small fraction of gas products (2.1%~13.3%). In addition, the process severity also significantly affected the characteristics of carbonization liquid and hydrochar. With the increase of the process severity, the pH level of the carbonization liquid gradually increased, while COD and sCOD gradually decreased, and the conductivity showed an initial decreasing and then increasing trend. Further qualitative analysis found that the carbonization liquid contained a variety of ketones, aldehydes and volatile fatty acids (VFAs). As the reaction intensity increased, the surface of the hydrochar became more rough and complex, and the specific surface area gradually increased. Meantime, the hydrothermal carbonization reaction contributed to the enrichment of the carbon element from the FW into the hydrochar, and the degree of enrichment increased remarkably with the increasing process severity. Due to the low ratios of H/C and O/C, the calorific values of hydrochar is 23.9MJ/kg, similar to the bituminous coal value of 28.3MJ/kg, and the high ignition temperatures from 267.5℃ to 302.3℃, the hydrochars produced from FW exhibited the potential of safe and clean fuel for energy production.