Analysis of operation of cogeneration installation equipped with a fix bed downdraft gasifier

The study presented in this paper examines the operation and performance of a low-power cogeneration plant equipped with a downdraft gasifier for biomass, municipal waste and sewage sludge treatment. Use of this technology opens up promising prospects for significant saving of fossil fuel resources, and environmentally friendly utilization of gasified wastes. The cogeneration installation is well-suited for a distributed energy system, in locations where biomass resource density is high and there is demand for both heat and power. The analysis was performed using SimTech’s IPSEPro program. The most important objectives were to analyze the effciency of the cogeneration plant and the gas composition as a function of key fuel and operating parameters. The results indicate that complementing the gasifier design by adding an internal heat exchanger boosts the effciency of the gasification process and causes an increase in the lower heating value (LHV) of syngas. It was proved that one of the most important process parameters is the air flow rate, which controls the degree of combustion. It was shown that by changing the air flow rate it is possible to control the gasification process and to change the gas composition. The analysis presented in the paper demonstrates the possibility of using the gas composition for diagnostics of the gasifier operation point. Supplementary tests of the real installation as well as discussion of the results of measurements, i.e., gas composition, lower heating value (LHV) are presented.