Study On Mixed Combustion And Pollutant Emission Of Biomass With Coal Gangue Under Oxygen-Enriched Atmosphere

Biomass is energy of large output,wide distribution and strong recyclability,and it has the characteristics of low ash content,high volatile content.Coal gangue is an undesired but inevitable by-product of coal mining and washing,and has become one of the largest industrial wastes,and it has the characteristics of high ash content,low volatile content.At present,the utilization of coal gangue and biomass has been paid more attention with the shortage of energy,environmental protection requirements are more and more stringent.Coal gangue and biomass are complementary in nature.The mixed combustion of the biomass with coal gangue could improved the burnout rate of coal gangue and reduced the emission of pollutants,which has certain reference value for practical application.In this paper,the coal gangue from the Xilinhot coal field in Inner Mongolia,and the biomass was corn stalk in Inner Mongolia.The combustion characteristics,pollutants emission characteristics and microstructure evolution characteristics respectively of the biomass with coal gangue were studied.Firstly,the combustion characteristics of the biomass with coal gangue were studied by using thermogravimetric analyzer.The results showed that the 21%O₂/CO₂ atmosphere could inhibit the combustion process to some extent,because the nature of the combustion atmosphere was different under the air and 21%O₂/CO₂ atmosphere.It could promote the combustion process of mixed samples with the increase of oxygen concentration and biomass content,under the 21%O₂/CO₂ atmosphere.The heating rate has great influence on the exothermic characteristics of the mixed samples.The whole combustion process of coal gangue conforms to the second-order dynamic model.The whole combustion process of mixed samples,the low-temperature and medium-temperature interval conforms to the first-order kinetic model,while the high-temperature interval conforms to the second-order kinetic model.Secondly,the combustion pollutants emission characteristics of coal gangue and biomass mixed samples were studied by using circulating fluidized bed of 36 k W/h.The results showed that the emissions of NO and SO₂for burning coal gangue increase gradually with the increase of primary or secondary air rate.The NO emission in 21%O₂/CO₂atmosphere was 25%?35%lower and the SO₂ emission in 21%O₂/CO₂ atmosphere was28%?35%lower than that in air atmosphere.With the increase of oxygen concentration,the oxidation in furnace increases gradually,and the NO and SO₂ emission in flue gas increases gradually.The NO emission shows a trend of first rising and then falling and the SO₂ content in the flue gas decreases gradually,with the increase of biomass content.Finally,the microscope property of samples were studied by using FESEM.The results showed that the particles size of ash samples decreases gradually with the increase of temperature.At a temperature of 300?500?,the particles showed obvious porous morphology,and the overall structure was relatively loose.After the temperature exceeds600?,glass fragments appeared on the particle surface,and the porous form gradually disappears.When the temperature reaches 1000?,the glass fragments on the particle surface gradually disappears,and the rock crack-like structure were formed on the particle surface.