Experimental investgation of gasification products at low temperature from wood wastes in a circulating fluidized bed

All fossil fuels and renewable energy sources are solar based. The energy generated in the Sun from the fusion of hydrogen is emitted to the space continuously. The part of this energy, which reaches to the earth, plays an active role in photosynthesis and metabolism processes. Plant leafs produces plant hydrocarbons (CmHn) and emit oxygen to the environment by taking carbon dioxide from air, water and minerals from ground through photosynthesis of chlorophyll by using solar radiation. Plant hydrocarbons are converted to metabolic hydrocarbons and fat in food chains. Coal, petroleum and natural gas have been evolved hundreds of millions of years ago as plant and metabolic matter decomposed and converted at conditions of high temperature and pressure under the earth?s surface in to the hydrocarbon compounds that is called, in general fossil fuels. Since the period of formation of fossil fuels is in the order of millions, these energy sources are considered as non renewable. Biomass, on the other hand, refers to living and recently dead biological material, hydrocarbons, for which the period of formation is relatively very short, less than hundred years. Biomass is a renewable energy source. In this study, a circulating fluidized-bed biomass gasification system has been designed and set up for investigating the gasification conditions and properties vii of biomass wastes from pine and hornbeam chips and barks, by using the facilities of the Thermal Power Laboratory of Engineering Faculty, Gazi University. Due to some shortcomings, steam could not be used in gasification. The thermal energy for the gasification was obtained from the electrical resistance heaters located around the side walls of the bed, and from the heat, which is released in the incomplete combustion in the gasification process. To determine the degree of gasification gross gasification efficiency has been defined. The heating value of the produced gas has been considered as the lower heating value of the biomass, without taking the thermal energy from the electrical heater into account. The research has been conducted for pine and hornbeam chips and hornbeam barks and the gasification efficiencies have been determined as 26,1%, 26,7% and 9,9%, respectively. The possible reasons of inefficiencies in gasification process have been discussed and some methods recommended for increasing the efficiency. Key Words : Gasification, fluidized bed, biomass.