EXPERIMENTAL STUDY ON CLOSED COMBUSTION CHARACTERISTICS OF BIOMASS PELLET FUEL

摘要

The characteristics of biomass fuel's ignition, and combustion were explored through experiments. The effects of fuel thickness, external temperature and water content on the internal temperature, the moving speed of drying front and carbon oxidation front, ash shrinkage and gas composition of biomass pellet fuel were investigated. When the fuel thickness is 11cm, the closed combustion cannot be carried out. The external temperature mainly affects the cooling condition at the later stage of closed combustion. The higher the external temperature is, the slower the temperature drops. With the increase of water content, the time of temperature below 100°C increases. The external temperature has little effect on the moving velocity of the drying front and the oxidation front. With the increase of water content, the moving speed of drying front decreases. When the water content is 30%, the combustion will be extinguished directly, but the water content has little effect on the carbon oxidation front. This paper also explores the reburning after closed combustion. In the region that starts to cool down to the highest temperature, only ventilation can be reburned. In the region where the maximum temperature falls to 100°C, it is necessary to ventilate first and then add fuel to make it reburned. In the region where the temperature drops to 100°C to extinguish, a small amount of fuel needs to be added before ventilation. After the new fuel is ignited, it can be reburned by adding fuel and ventilation. The experimental results provided a basis for the simulation and in-depth theoretical analysis of biomass particle fuel combustion.