Combustion And Gas Emission Characteristics Of Blends Of Bituminous Coal And Biomass Chars

The use of fossil energy causes increasingly harsh environmental problems,seeking renewable clean energy is one of the major energy issues in the 21st century.Biomass resource is the fourth largest energy source on the earth besides coal,oil,and natural gas and it is considered to be a sustainable,environmentally friendly energy source and have received much attention all over the world.The technology of co-combustion of coal and biomass not only alleviate the fossil crisis,but also reduce the pollution caused by the combustion of fossil fuels,it is a very promising biomass utilization method.Biomass char can improve the disadvantages of biomass,such as,poor grindability,low calorific value and large volume,and it is more suitable for burning in existing coal-fired devices.This article selected wheat straw and bituminous coal as the research object.Biomass char produced by pyrolysis of wheat straw under N2 and CO2 atmospheres and moderate to low temperatures(300? and 500?).The basic properties of biomass char prepared under different pyrolysis conditions were studied.The prepared char was subjected to industrial analysis and elemental analysis and the surface morphology,specific surface area and pore size distribution were characterized by SEM and BET methods.The thermogravimetric analyzer was used to monitor the combustion process of biomass char and coal and their mixtures in air to study the combustion characteristics of fuels.The mass spectrometer was used to monitor the instantaneous emission of CO2,NO,NO2 during the combustion of the fuel,and the emission of polluting gases was analyzed.The experiment results showed that biomass char had higher calorific value and fixed carbon content than the raw biomass.The biomass char surface had more small holes and a larger specific surface area.With the same pyrolysis temperature,the biomass char prepared under the N2 and CO2 atmosphere had little difference in combustion characteristic parameters such as the ignition temperature,the burnout time and the maximum burning rate,and the pyrolysis temperature had a greater impact on the combustion characteristics of biomass char.The reactivity of biomass char was greater than that of coal,and a significant synergistic effect can occur between the two co-combustion,which can improve the combustion activity of coal.The blending of biomass char and coal reduced the fuel activation energy,the first-order chemical reaction model can be used to describe its chemical reaction rate.Fewer NOx emissions from biomass char.The CharCO2-500 contains more alkali metal and had a catalytic effect on coal combustion and NOx conversion.The co-combustion of coal and biomass char can reduce NOx emissions.