污泥与煤混烧动力学及常规污染物排放分析

采用热重分析法研究了不同污泥掺烧比例及不同加热速率时污泥与煤的热失重特性.探讨了掺烧污泥对煤燃烧特性的影响,分析了掺入污泥对煤的燃烧变化规律,并进行了动力学分析.结果表明,加热速率增加时,样品的失重速率增大,开始失重温度及最终燃尽温度升高.掺烧时的TG曲线在400~600℃时有一个明显的失重阶段.失重速率峰值随着掺烧比的提高而升高,对应的温度降低.掺烧污泥后的混合样品的燃烧温度范围比单一燃煤时少20~100℃.非等温动力学模型分析可得,少量的污泥与煤掺烧时所需的活化能与煤较接近,对煤的正常燃烧影响不大.不同比例掺烧时产生的烟气中NOx、SO2、CO2生成量及减排规律因N、S、C含量不同而各有差异.热重分析及模型分析法可以为不同理化特性的煤与污泥掺烧提供初始理论依据.

Effects of sewage sludge on coal combustion using thermo-gravimetric kinetic analysis

Co-combustion characteristic and kinetic behaviour of coal and dried sewage sludge were studied at different heating rates (10, 25 and 40℃/min) and different sewage sludge ratios (3%, 5% and 10%) by a thermo-gravimetric analysis (TGA) in the temperature ranging from ambient temperature to 1000℃. Weight loss and kinetics during the combustion of coal and sewage sludge and co-combustion were also illustrated. With the increase of heating rate, terminal temperatures would be higher when mass of fuels corresponding to the ashes remained constant and weight loss started. Increasing the sewage sludge ratio could obtain a lower temperature of ignition point and terminal stage. During the co-combustion process, a clear weigh loss phase appeared between 400~600℃. During co-combustion of sludge and coal, about 20~100℃ was decreased in the temperature range of burning comparing to that of single coal. It could be obtained from further analysis of non-isothermal kinetic model that a small amount of sludge had a little influence on the combustion process. The generation and emission characteristics of NOx, SO2 and CO2 in flue gas varied from content of N, S and C with different sludge blended ratios. Thermal-gravimetric analysis and model analysis could be used as an effective way of assessing co-combustion process and providing initial theoretical basis.