城市污泥/褐煤共水热碳化产物的热化学转化特性及规律研究

污泥和褐煤通过共水热碳化预处理以制备高品质固体燃料,为污泥和低阶煤的有效处理提供了一种可行方案。本研究主要考察了城市污泥(SS)和褐煤(LC)在不同温度下(120,180,240和300℃)进行共水热碳化制得的固相产物(水热炭)的热化学转化特性和规律,包括燃烧、热解和半焦CO₂气化过程,并分析了这些过程中的协同作用。结果表明,共水热碳化预处理对城市污泥和褐煤的热利用行为有显著影响。一方面,共水热碳化处理后的水热炭相对其计算值具有更高的产率、煤化程度、热值等,同时具有更低的灰分含量。另一方面,混合物水热炭在燃烧、热解和半焦CO₂气化过程均表现出一定的协同作用(促进燃烧和热解行为,降低气化活性),且水热温度在240℃附近时,这种作用最为明显。鉴于热解和气化过程的协同效果均低于燃烧过程,共水热碳化产物被认为更适合用于燃烧。这些发现表明,将共水热碳化改性提质处理与后续热化学工艺相结合,对于能源的产生和有机废弃物的利用都有一定的积极意义。

Investigation on thermochemical conversion characteristics and regularity of co-hydrothermal carbonization solid fuel from sewage sludge and lignite

The sludge and lignite are pretreated by co-hydrothermal carbonization to prepare high-quality solid fuel, which provides a feasible solution for the effective treatment of sludge and low-rank coal. This study mainly investigated the thermochemical conversion characteristics and regularity of solid phase products (hydrochars) prepared by Co-HTC of sewage sludge (SS) and lignite (LC) at different temperatures (120, 180, 240 and 300℃). Experiments included combustion, pyrolysis and char CO₂-gasification processes, and the synergistic effects in these processes were also analyzed. The results show that Co-HTC pretreatment has some significant effects on the thermal behavior of SS and LC. On the one hand, compared with the calculated value, the hydrochars after co-hydrothermal carbonization have higher yield, fuel rate, coalification degree, calorific value, etc., and they have lower ash content. On the other hand, all hydrochars have a certain synergistic effects in combustion, pyrolysis and char CO₂-gasification (promoting combustion and pyrolysis behavior, reducing gasification activity), and when the hydrothermal temperature is around 240℃, these synergistic effects are most obvious. Given that the synergistic effects of the pyrolysis and gasification processes are lower than the combustion process, co-hydrothermal carbonization products are considered to be more suitable for combustion. These findings indicate that the combination of the upgrading of Co-HTC with subsequent thermochemical processes has positive implications for the generation of energy and the utilization of organic wastes.