Study On Combustion Characteristics Of Methanol-based Fuel

Under the background that the state gradually shut down the coal-fired boilers below 10 t/h and vigorously advocated the development of clean alternative energy for coal-fired boilers.Methanol-based fuel has gradually become a clean alternative fuel for coal-fired boilers.Due to the characteristics of low calorific value and high latent heat of vaporization of methanol-based fuel,the existing methanol-based fuel nozzles in the market often have insufficient energy supply for a short time when burning the fuel;the atomization angle is too large when atomizing,and the mixing effect with combustion supporting air is poor,resulting in inadequate fuel combustion;low combustion temperature,short combustion duration and other problems.Therefore,this paper designs a 1 t/h high-efficiency,energy-saving and environmental friendly methanol-based fuel nozzle.The combustion characteristics of methanol based fuel were studied by numerical simulation and experiment.First of all,the combustion calculation is completed according to the main physical and chemical properties of methanol-based fuel,and the main nozzle design is completed according to the combustion calculation results and combustion characteristics of methanol-based fuel.Through the orthogonal test,the nozzle diameter,nozzle length,swirl chamber height,swirl chamber diameter and swirl chamber tangential inlet diameter are the main factors,and fluent is used to simulate the internal flow field of the nozzle,and the nozzle outlet speed is the main factor The main evaluation index is determined by variance and range analysis.The optimal scheme of the main structure parameters of the nozzle is determined.The diameter of the nozzle is 2mm,the length is 1.3mm;the diameter of the swirl chamber is 4mm,the length is 4.5mm,and the tangential inlet diameter of the swirl chamber is 1.5mm.Then,through the numerical simulation software FLUENT,the atomization and combustion characteristics of MF100 are studied on the simplified model of three-dimensional combustion system.The results show that the atomization angle is 40°and the particle size of the oil droplet is mainly concentrated in the 40-130 range,the atomization effect is good;the best air inlet speed is 10 m/s,at this time,thecombustion flame in the furnace is well formed,the ignition distance is relatively matched with the furnace size,and the stable flame of 1073-1460k is formed in the core combustion zone of the furnace,and the temperature field distribution is relatively uniform,the maximum temperature of the furnace is 1640k,and the average temperature is 1106k,The lower the exhaust gas temperature,the lower the average mass fraction of the unburned gas component and the polluting gas component,indicating the better combustion efficiency,economy and environmental protection.Finally,the combustion emission characteristics of methanol based fuel are studied through the methanol based fuel combustion test-bed,and the economy and energy saving of various fuels are compared and analyzed.The results show that with the increase of methanol ratio in methanol based fuel,the emission concentration of HC compound and CO gas in flue gas slightly decreases,and the emission concentration of NOx gas greatly decreases;with the increase of methanol ratio in methanol based fuel,the emission concentration of particulate matter gradually decreases,and the combustion efficiency gradually increases.Mf50 not only has the advantages of clean and environmental protection in combustion emission characteristics,but also has good fuel economy.In the long run,methanol based fuel has a more promising future,which can alleviate the dependence on fossil fuels such as petroleum and liquefied gas,and is the main clean alternative energy in the future.