| The continuous advancement of urbanization has caused many cities to face the problem of environmental pollution caused by a large amount of garbage.Using municipal solid waste incineration(MSWI)to dispose of garbage will produce fly ash containing heavy metal elements and other harmful substances,which will make harm to the living environment.The stabilization method can use the silicon-containing oxide contained in the MSWI fly ash itself to form a glass body with a stable structure,and in this process,the heavy metal elements are embedded to make it difficult to discharge.This paper intends to design a swirl-flow combustor using natural gas as the main combustion component of the swirl-flow furnace to melt the fly ash of the MSWI,and to conduct research on its combustion and flow field characteristics and the air-carrying characteristics of fly ash,and then based on the design parameters,form the overall design plan of the experimental system.The main contents are as follows:In order to establish suitable combustion and flow field conditions,the existing combustor was modified to be suitable for melting the fly ash,and then a threedimensional model was established and a grid was drawn to carry out numerical simulation work.By adjusting the head intake equivalent ratio of the combustor,the swirling parameters of the radial swirler,and the structure of the boundary,the combustor can stably establish combustion.The overall equivalence ratio and flow field characteristics of the combustor are studied by changing the intake air volume of the secondary air and the deflection parameters of the intake flow path,so that the temperature field and flow field in the combustor can meet the requirements of fly ash melting.It is found that the intake air equivalent ratio of 0.8 and the radial swirler eccentricity of 28 mm are more suitable for the stable combustion of the combustor.When the overall equivalent ratio is 0.6,the high temperature conditions and swirl performance required for the melting of fly ash can be guaranteed.Research on the air-carrying characteristics of single particle size and multiple particle size in the combustor.Using numerical simulation method,by changing the deflection parameters of the air inlet of the secondary air,the performance of the combustor for the disposing of fly ash is evaluated from the four aspects of operation:trajectory,time,spatial distribution and temperature characteristics.The results show that both larger and smaller secondary air inlet eccentricity can make the combustor become stable faster,and at the same time achieve a higher capture rate,but too large eccentricity will cause particles to accumulate in the upstream of the combustor;Large-diameter particles are difficult to escape,but it is also hard to heat up.In the combustor designed in this paper,the escaped particles with a particle diameter of less than 73 μm are in a molten state.When the eccentricity is 28 mm,it can simultaneously meet the requirements of high capture rate and high temperature of the escaped fly ash.Design the experimental system based on the numerical simulation results.The experimental system is divided into five parts: the main body of the test section,the air/gas pipeline,the fly ash conveying device,the slag dealing device and the flue gas dealing device,and the design of the structure of each part and the connection mode of the parts are completed.It is found that the most difficult point in the operation of the experimental system lies in the disposing of secondary fly ash and flue gas,and use the cooling water and water membrane separation to solve the problem. |
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