Experimental Study Of Combustion With Gasification Of Typical Biomass Pellets

Reliable and sustainable energy supply is the basis of comprehensively building a moderately prosperous society in rural areas, an important guarantee of the urbanization process, and an important part of the new socialist countryside construction. Therefore, biomass pellets fule as a new type of renewable energy is gradually being valued by people. At present, biomass pellets rule is used by direct combustion primarily, but this way is low efficiency and serious environmental pollution, so it needs to further improve and perfect. Biomass is different from coal, its volatile is much higher than coal, and easily precipitate at lower temperatures. In this paper, the combustion with gasification of biomass is raised, included volatiles combustion and fixed carbon combustion. Its characteristics and influence factors are investigated experimentally.I design a small unit test furnace on the basis of gasification combustion. Fuel goes into the gasification combustion chamber top-down, and air is forced into chamber from the top. There are circular holes on the fixed grate uniformly. Resistance wire heating with automatic control is used to simulate the actual products of gasification combustion furnace heating. The thermocouples measure the temperature distribution of gasification combustion chamber, and flue gas analyzer analyze the gasification combustion gas composition.Firstly, I test the industry and elemental analyzes of corn straw and cotton stalk pellet fuel. The analysis results show that moisture content and fixed carbon content of corn straw pellet fuel is lower than the cotton stalk, but the volatile content, calorific value, N content, S content is higher than the cotton stalk. This results provide a basis for the analysis of the ignition timing, combustion time, combustion temperature, NOx emissions, SO2 emissions about the two pellet fuel combustion. Secondly, I analyze the drying process of pellet fuel, and study the drying process at different temperatures of corn straw and cotton stalk pellet fuel. Two pellet fuel moisture variations at different temperatures and moisture content equation are obtained by experiments.The corn straw and cotton stalk pellet fuel gasification combustion of the fixed grate are studied experimentally by the unit test furnace, and then analyses the influencing factors of the biomass pellet fuel gasification combustion, including raw material type, pellet size, material thickness, drying system, air system, heating system. The temperature field curve, weight loss curve, the curve of the flue gas emissions and the slagging phenomenon under different conditions are obtained by experiments. Finally, through the comparison and analysis of the test results, summed up reasons which cause the difference combustion characteristics, such as ignition time, burning time, the combustion temperature.The slagging characteristics of corn straw and cotton stalk pellet fuel are studied by microcomputer ash melting point detector. The instrument measures deformation temperature and softening temperature of two kinds of pellet fuel. Both deformation temperature and softening temperature of the corn straw pellet fuel are higher than cotton stalk, so slagging phenomenon of cotton stalk pellet fuel is more serious than corn straw pellet fuel. Test results are consistent with the results of the combustion experiment.