污泥掺混褐煤水热制固体燃料的理化特性

Physicochemical analysis on hydrothermal upgrading of sewage sludge with lignite for solid fuel

为了解决污泥单独水热碳化灰分高、热值和资源化利用率低等问题,通过水热处理的方法对城市污泥掺混低阶褐煤进行提质处理,对水热提质固体燃料的燃料特性、孔隙结构以及化学结构的变化等理化特性进行研究.结果表明,当污泥与褐煤质量添加比为1∶9时,随着水热温度的提高,固体燃料中碳含量以及热值大幅度提高,且原子个数比n(H)/n(C)和n(O)/n(C)显著下降.固体燃料羟基或羧基官能团中—OH和酰胺官能团或羧基官能团中—C≡O的相对光谱吸收强度显著降低,表明提质过程中污泥与褐煤发生了显著的脱水和脱羧反应.通过13 C核磁共振波谱分析,发现随着提质温度的升高,甲氧基减少的速率最快,摩尔分数从5.76%减少到了1.31%,羧基和羰基的摩尔分数从9.03%减少到5.64%,说明固体燃料中氧元素的丢失不仅与脱水作用有关,与羰基和羧基的转化以及甲氧基的变化也密切相关;芳香化碳的摩尔分数显著增加,表明固体燃料的芳香化程度加深,煤质特性提升.

Hydrothermal treatment of municipal sewage sludge with low rank lignite was conducted in order to solve the problems of high ash content,low resource utilization rate and calorific value of sewage sludge hydrothermal carbonization. The physicochemical characteristics of the solid fuel,including fuel characteristics,pore structure and the changes of chemical structure were analyzed.Results show that the carbon content and calorific value of the solid fuel greatly promoted and the atomic ratio of n（H）/n（C）and n（O）/n（C）significantly descend with the temperature increasing when the quality ratio of sewage sludge and lignite is 1∶9.Relative absorption intensity of—OH in hydroxyl or carboxyl groups and —C O in amide or carboxyl groups were significantly reduced,indicating that dehydration and decarboxylation reactions occurred during the upgrading process.The 13 C NMR spectrum showed that the relative content of methoxyl carbons and carboxyl/carbonyl groups diminished from 5.76% to 1.31% and 9.03% to5.64%,respectively,which suggested that oxygen loss not only corresponds to dewatering,but a significant correlation with conversion of = O and COOH and change of methoxyl carbons.The relative content of aromatic carbon was greatly improved,which indicated that the degree of aromatization and coalification deepened.