城市污泥水热碳化影响因素研究

Study on Influencing Factors of Hydrothermal Carbonization of Sewage Sludge

研究污泥水热碳化过程中反应温度、反应时间和反应介质对污泥水热炭性质的影响。结果表明,在酸性条件下,水热碳化处理能够更好地去除污泥中的水分(水分去除率分别为酸性条件下42.8%~53.3%和中性条件下28.9%~45.2%),其中污泥在240℃条件下进行1小时水热碳化反应后脱水效果最佳。随着反应温度和反应时间的增加,脱水和脱羧反应更充分,污泥水热炭的产率减少,H/C与O/C比值降低。此外,污泥水热碳化处理破坏了污泥的团聚体结构,使水热炭表面产生孔洞和凹槽,比表面积、孔体积和孔径均有所增加,其中在中性、220℃的反应条件下,污泥进行1小时水热碳化反应后得到的水热炭产物具有最高的比表面积(129.98m^(2)/g)和孔体积(0.66cm^(3)/g)。影响水热炭主要成分及晶型结构的因素排序为反应介质>反应温度>反应时间,随着反应温度升高和反应时间延长,水热炭中挥发分的含量降低,固定碳和灰分的含量增加,并且水热炭燃烧的主要放热区间在250~550℃范围内。

The effects of reaction temperature,time,and medium on the properties of sludge hydrochar were experimentally studied.The results demonstrated that hydrothermal carbonization(HTC)treatment enhanced sludge dewatering and volume reduction,with a higher water removal rate(42.8%–53.3%)observed under acidic conditions compared to neutral conditions(28.9%–45.2%).Notably,the highest dehydration rate was achieved after HTC at 240℃ for 1 hour.Increased reaction temperatures and longer reaction times led to reduced hydrochar yield due to enhanced dehydration and decarboxylation reactions.The H/C and O/C atomic ratios gradually decreased as a result.Furthermore,the regular and compact structure of sludge was disrupted to varying degrees following HTC treatment,resulting in the formation of holes and grooves that increased the specific surface area,pore volume,and pore size of the hydrochar produced.Specifically,hydrochar obtained from HTC at 220℃ for 1 hour exhibited the highest specific surface area(129.98 m^(2)/g)and pore volume(0.66 cm^(3)/g).The composition and crystalline structure of hydrochar were primarily influenced by factors such as reaction medium>reaction temperature>reaction time.With the increase of HTC reaction temperature and residence time,the volatile content of hydrochar decreased while the fixed carbon and ash content increased.The main exothermic range during combustion of hydrochar occured between 250–550℃.