| For the research of biomass energy,the selection of raw materials must meet the most basic requirements,such as wide sources and easy access.As one of the three major crops in China,corn is still the main object of research.The planting area of corn in China has basically remained at about 650 million mu in recent years.In addition to using corn straws as silage and rotten fertilizers,biomass molded fuel is another method of efficient utilization of corn straws.Its main advantages are high density,easy burning,high heating value,and easy storage.However,corn straw molding fuel has obvious slagging during the actual combustion process,which severely corrodes the boiler and affects the safety and stability of the boiler operation.The method of mixed straw forming improves the problem of straw slagging,which not only integrates various forestry and agricultural waste biomass resources,but also has a positive role in promoting the formation of high-grade biomass solid fuels and reducing the overall biomass energy cost.Firstly,two non-slagging biomass raw materials of Caragana korshinskii and Pinus tabulaeformis were mixed with corn straw raw materials by fuzzy mathematical method and slagging rate determination method.The Taguchi method was used to optimize the analysis of the molding parameters and calculate the contribution rate.Then the slagging mechanism and corrosion characteristics of corn straw were studied through the determination of ash and slag composition and microstructure analysis.Finally,the feasibility and rationality of anti-slagging were studied when corn straw was mixed with Caragana korshinskii and Pinus tabulaeformis.It provides a new and reliable method for reducing the slagging rate of corn straw solid fuel,and provides reference for the industrial production of biomass mixed solid fuel in the later stage.The main contents and conclusions are as follows:(1)Judging the slagging properties of the biomass of Caragana korshinskii and Pinus tabulaeformis.Established a subset of evaluation of the slagging tendency of corn straw,Caragana korshinskii and Pinus tabulaeformis biomass raw materials,and comprehensively judged by fuzzy mathematics that corn straw was a severely slagging raw material,and Caragana korshinskii and Pinus tabulaeformis were two kinds of slightly slagging biomass raw material.According to NB / T 34025-2015,the slagging rate of Caragana korshinskii and Pinus tabulaeformis was calculated.The slagging rate curve was drawn in the slagging strength area chart,and it was found that the slagging curve graphs of Caragana korshinskii and Pinus tabulaeformis were both in weak slagging It can also be judged that the slagging strength of Caragana korshinskii and Pinus tabulaeformis biomass raw materials is slight.(2)Optimization analysis of molding parameters and calculation of contribution rate for two raw materials,corn straw and Caragana korshinskii,corn straw and Pinus tabulaeformis.The ratio of raw materials,water content,temperature,and pressure have significant effects on the density of the mixed fuel,and when Caragana: corn straw = 6: 4,water content 8%,temperature 130 ° C,pressure 120 MPa,The mixed fuel of Caragana korshinskii and corn straw has the best molding effect.The contribution of each factor to the fuel density of corn straw and kraft corn is: temperature(45.1%),moisture content(32.0%),pressure(12%)and mixed The proportion(1.6%);when Pinus tabulaeformis: corn straw = 6: 4,moisture content of5%,temperature of 70 ° C,and pressure of 130 MPa,the mixed fuel of Pinus tabulaeformis and corn straw has the best molding effect.The contribution rates of various factors to the fuel density of corn straw and Pinus tabulaeformis are: moisture content(78.17%),mixing ratio(8.66%),pressure(2.48%),and temperature(2.22%).(3)The corn straw was used as the research object to explore the slagging mechanism when biomass fuel was burned in the boiler.The heating surface and bottom ash slag generated when the biomass fuel is burned in the boiler are mainly caused by the characteristics of the biomass raw material itself,that is,the alkali metal elements such as Na and K with a relatively high content and non-metal elements such as Cl.The slag is also affected by factors such as the structure of the furnace and the combustion temperature.(4)Combustion of Caragana korshinskii and corn straw solid fuel,Pinus tabulaeformis and corn straw solid fuel in a boiler for anti-slagging test.It is found that under the same conditions as the strength of the blast,the size of the boiler structure,etc,mixing the corn straw raw materials with Caragana korshinskii and Pinus tabulaeformis can significantly reduce the slagging degree during the combustion process.After the combustion is completed,the bottom ash form is observed.Low tiny slag fast.After scanning through SEM,it was found that the bottom ash of the corn straw briquette fuel burned quickly and densely,but the micro slag after combustion of the two mixed briquette fuels didn’t have the above phenomenon.(5)It was also found in the actual combustion process that when the biomass molding fuel is burned in the boiler,due to its unique framework structure,it reduces the deposition of large fly ash particles on the heating surface,thereby delaying the slagging time of the heating surface of the boiler,which is important for the long-term safe operation of the boiler.The above research provides a strong basis for the vigorous promotion of corn straw solid molding fuel,and at the same time provides a new direction for the research of biomass fuel anti-slagging. |
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