Study On The Co-firing Characteristics Of Biomass And Coal

In the world energy consumption, biomass energy has the total amount of about 15% which is Number 4, second only to the coal, petroleum and natural gas. Our country abounds in biomass resources, which mainly comes from agricultural wastes, agricultural and forest products processing wastes, firewood, municipal solid waste, etc.Coal-based is the major feature of Chinese energy structure, 84% of coal is directly used to burn and in the combustion process produces large amounts of dust, CO2, SO2, NOx and other pollutants, all of which cause our air to take on typical coal-burning pollution.It is a kind of clean coal combustion technology for biomass combined with coal to be burned, which can effectively reduce environmental pollution, improve air quality. Based on the TG-FTIR technology, using more abundant straw, wood chips as raw material in biomass resources, the combustion experimental research about they and three kinds of coal in different metamorphic grade has been finished in this article, under the condition of different biomass addition ratio, oxygen concentration, heating rate, etc.Experimental results show that the characters of fuel itself vary, its combustion process also varies. Biomass combustion process is mainly concentrated on the burning of volatile combustion in the early stage, while coal combustion process focused on the burning of fixed carbon in the later stage. The combustion characteristic of biomass is significantly better than raw coal's, such as ignition and burnout. The addition of biomass can effectively improve the comprehensive combustion performance of raw coal, and the higher the fixed carbon of raw coal content, the more greatly additive will affect its combustion performance. Besides, the more the amount of biomass adding, the better the burning feature of biomass with coal mixture. The combustion process and combustion characteristics can be significantly improved by changing the operating condition, such as heating rate and oxygen concentration, etc. Furthermore, under the improvement of heating rate and oxygen concentration, the fuel combustion performance can also be substantially increased, the burning time can be reduced and the burnout rate can be increased. Combustion dynamics analysis indicates that the combustion of biomass, coal and their mixtures can be treated as a level 1 response processing. The activation energy of burning biomass and coal mixture is less than that of the raw coal burning. Adding biomass can increase the reactivity of biomass and coal mixtures. The activation energy of mixture can be reduced under increasing heating rates, and which can be raised by increasing oxygen concentration.The infrared spectroscopy analysis of gaseous combustion products shows that the gaseous products of coal and biomass combustion are diffrent. Increasing biomass addition ratio, oxygen concentration and heating rate can reduce the CO percentage in the burning gaseous products and improve the burnout rate of fuel combustible substances and the utilization rate of energy.