Investigation Of PM₁₀ Emissions During Co-combustion Of Coal With Solid Waste

With the development of the economy and the continuous acceleration of the urbanization process,the problem of solid waste disposal has become a major issue that the entire society needs to pay attention to.At present,China’s solid waste output is relatively high,and it is also seeking various better ways to achieve scientific disposal of waste.The traditional waste disposal methods are mainly landfill and incineration,but both have certain problems.Landfills occupy land resources,and improper disposal can easily cause environmental pollution;the construction cost of incineration stations is relatively high.The use of existing coal-fired boilers for the co-combustion of waste is a way to dispose of a large amount of waste in a short period of time,and it can also use the thermal energy in the waste,while the cost is relatively low and the area is small.However,there are also some problems in the process of co-firing coal and waste,such as the effect of co-combustion on the combustion performance and release of pollutants,especially the release of particulate matter,one of the main atmospheric pollutants.Therefore,this paper explores the effect of the co-combustion of coal and waste on the combustion characteristics and the possible interaction of mineral elements that may be present during the co-firing process on the particulate generation characteristics.Firstly,a biomass waste tea stem was selected,blended with Datong coal and Wanxiang coal according to the calorific value ratio 90/10 and 80/20（coal/waste）,and then all the fuels were burned in a thermogravimetric analyzer and an electrical heated drop-tube furnace.The thermogravimetric experiment is an air atmosphere with a heating rate of 10K/min.The TG-DTG curve obtained from the analysis experiment is used to study the effect of co-combustin on the combustion characteristics.Subsequently,a combustion experiment was carried out in a high-temperature electrical heated drop-tube furnace.The particulate matter generated by the combustion was collected by a low-pressure impactor（LPI）particulate sampling system.The mass particle size distribution of the particulate matter was obtained by a one-millionth balance and passed through an X-ray fluorescence spectrometer（XRF）and field emission scanning electron microscope（SEM）and other test methods to analyze the composition and morphology of the particulate matter generated by combustion.The experimental results show that the co-combustion of tea stems can improve the combustion characteristics of the fuel,reduce the ignition point of the fuel,and inhibit the release of PM₁₀（particulate matter with an aerodynamic diameter of less than 10μm）to varying degrees.Among them,the release of PM₁during the co-combustin of Datong coal is well suppressed.The main reason is the capture of alkali metal by aluminosilicate in coal and the conversion of Cl into flue gas.The main reason for the decrease of PM_1-10 is the formation of low melting point minerals promotes collision polymerization.The co-firing of Wanxiang coal is mainly the reduction of PM_1-10,because the collision promotes coalescence and then melts to form a spherical structure of Si-Al-Ca.Then,a paper-based municipal solid waste milk carton was selected,blended with Datong coal and Wanxiang coal according to the calorific value ratio 90/10 and 80/20（coal/waste）.The experimental results show that the co-combustion of the milk carton can reduce the ignition point of the fuel and improve the combustion characteristics of the fuel.When the milk carton is burned alone,the mass particle size distribution curve of the particulate matter follows a three-peak distribution,which is quite different from the mass particle size distribution curve of coal single combustion.During the co-combustion of Datong coal and milk carton,its PM_1-10 aluminosilicate collided to capture the Si-Al-Ca sub-micron particles generated by the milk carton combustion,resulting in the reduction of PM₁ during the co-combustion process.However,when the Vientiane coal was mixed with the milk carton,the amount of PM₁ produced slightly increased.