Research On Energy And Efficiency Of Sludge Microwave Pyrolysis-power Generation Combined System

Due to the ever increasing amount of sewage sludge and increasingly stringent environmental standards, the problem of sewage sludge disposal is becoming more serious than before. Meanwhile, as a type of biomass energy, sewage sludge has the potential for energy-oriented use because of its high organic content and heating value. As an alternative, microwave pyrolysis of sewage sludge which have advantages of celerity, saving energy and low cost is the directional development of disposal of sewage sludge. This paper put forward idea of microwave-induced sludge pyrolysis coupled with products comprehensive utilization, laws of microwave pyrolysis and approaches of products energy recovery were studied.Firstly, this paper studied distribution and composition of pyrolysis products, energy requirement of pyrolysis process by batch-type microwave-induced sludge pyrolysis experiments. The results show that, as the terminal temperature is raised the wight-loss ratio of sludge and syngas yield increase according ly. At a higher terminal temperature, both the weight-loss ratio of wet sludge and the removal rate of organics can reach up to above 90%, demontrated that microwave pyrolysis process have significant effect of reduction and stabilization. The results also show that in batch-type pyrolysis experiments, both the energy recuperation ratio and the biogas preparation efficiency reach highest at the terminal temperature of 800 centigrade. Taking the aim of energy recovery maximization into consideration, the optimum terminal temperation should be 800 centigrade. At the same time, this paper made primary simulation of a continuous sludge pyrolysis equipment which is applied to small and medium-sized sewage treatment plants, energy consumption and running cost of this equipment is analyzed.Comparing to traditional sewage disposal methods, all kinds of pyrolysis methods mean relatively high energy consumption. Therefore, it’s crucial to recover energy from pyrolysis syngas. Power generation system composed of solid oxide fuel cell stack and micro gas turbine has adventages of strong fuel adaptability, high efficiency and independent of scale, promised the best mode of small-scale distributed biogas utilization. This research built detailed model of SOFC-MGT power generation system, simulation results show that the power generation efficiency can reach up to 55.9% and the cogeneration efficiency can reach up to 74.8% at design condition, demonstrated that this sort of system can utilize biomass energy efficiently. The impacts of working temperature, current density, operating pressure and utilization factor on system performance were also studied in this paper. Moreover, in the whole process, exergy destructions of each step are calculated, the resuls can provide theorical and technical assistance for design and operation of allied power generation systems.To sum up, in this paper, experimental research on microwave-induced sludge pyrolysis process is carried out, simulative analysis of sludge pyrolysis syngas utilization via power generation is performed. These research results are not only helpful to the resource utilization of sludge pyrolysis products, but also to the widespread use of microwave-induced pyrolysis technology in sludge disposal area.