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

Abstract

Biomass for energy offers commercially available solutions with good dispatchability as renewable power source. The same applies for municipal waste as well as sewage sludge produced during the municipal wastewater cleaning as a byproduct. With lower energy density of the fuel and lower electric efficiency than baseline non-renewable fuels, utility biomass application is only economically viable in locations where biomass resource density is high and where there is a demand for both heat and power.The purpose of this study is to present one of the basic solution, which could be used locally as an element of distributed power generation system. The attention has been focused on application of technologically simple fix-bed downdraft gasifier, gas purification line and piston engine. The most common problems of such installations are, the low resistance of piston-cylinder system and engine intake system on the gas pollution. On the other hand, the use of this technology opens up a promising prospect for environmentally friendly utilization of wastes accompanied with conversion of its energy, which in other case remains unused.The paper aims to present the results of simulations performed using IPSEPro programme of SimTech company. The most important objectives are to gasify biomass as well as sewage sludge to produce a clean gas of acceptable composition for piston engine, and to convert this solid resource into combustible-clean gas at high efficiency. Parameters and composition of syngas depend on many factors, but the work has focused on evaluation of the role of moisture content and chemical composition of biomass. As demonstrated both of these factors strongly influence the gas calorific value and thus the generated output power. Supplementary tests of the real installation and discussion of the results of measurements i.e. gas composition, lower heating value (LHV) are presented.