The Use of High Moisture Sewage Sludge In The Chp Unit Integrated With Biomass Drying And Gasification

The paper presents the evaluation of the possibility of the use of a biomass with high moisture content in a cogeneration plant with gas piston engine. The dried sewage sludge-derived syngas is used as a fuel. Sewage sludge are characterized by about 70 wt% of moisture content after the dewatering process. The drying process which is applied as the next step requires great amount of energy. For this reason the thermal integration of the drying process with a piston engine which produce a significant amount of waste heat is proposed. The legal situation of the sewage sludge treatment is briefly explained. The thermodynamic analysis of the cogeneration plant based on the gas piston engine integrated with drying and gasification units was conducted. The models of individual components of the system were developed using Engineering Equation Solver and MS Excel software. The maximum moisture of the fuel acceptable for the autonomic operation of the plant is calculated. The influence of the plant’s scale for the acceptable moisture content in the biomass is studied. The analyzes revealed, that the waste heat from the engine is not sufficient for the drying unit. The operation of cogeneration plant requires an additional source of energy or drying the sewage sludge in an independent installation to moisture content about 50-55%.