Numerical Simulation Of Combustible Solid Waste Combustion In Grate-fired Boilers And Furnace Structure Design/Operation Optimization

With the rapid growth of our economy,the living standard of the residents has been greatly improved,the production of solid waste has increased dramatically,and the proper disposal of solid waste has become a critical issue to be solved urgently.In order to achieve disposal targets of reduction,harmless and recycle,incineration is the priority selection for solid waste disposal.In this paper,the biomass grate-fired boiler using agriculture and forestry waste as fuel and the municipal solid waste incinerator were numerically simulated respectively based on the CFD technology.After verifying the reliability of the model,relevant research was carried out on the adaptability of the furnace with the heat value fluctuation of two kind of solid wastes,so as to provide reference and theoretical basis for optimal operation of power plants.In the study of an 130t/h biomass boiler which has been put into operation,the phenomenon of high temperature flue flowing close to the water-cooled wall of first flue was improved by adjusting the fuel stacking thickness,five wind room air distribution at various chambers,excess air ratio,the secondary air ratio of front arch and rear arch.In addition,independent research and design of furnace structure on the basis of the original model through structural modification,such as the flue backwards,reduce the quantity of secondary air duct,and change the direction of secondary air duct vertical injection.It can be concluded that the structure is acceptable when the first flue one meter backwards on the basis of the original model,the angles between secondary air ducts of front/rear arch and horizontal plane angle between the secondary air ducts of front arch and the horizontal direction is 37°/ 55°.In the study of a 750t/d waste incinerator preliminary,a optimized furnace structure was obtained through studying the influence of secondary air duct horizontal injection angleand front/rear arch structure on combustion conditions.Furthermore,the operation of proposed incinerator was optimized and its adaptability to different fuel heat value was verified.The results indicated that with the secondary air injection speed of 45 m/s,excess air ratio of 1.6 and the primary/secondary air ratio of 0.65:0.35,its operation conditions meet the Standard for pollution control on the municipal solid waste incineration and has wide application in fuels with different heat value As the waste heat value increases,the furnace design of the waste incinerator should refer to the biomass furnace,which will lower front arch and extend its grate coverage.Straw as the main component of biomass boiler fuel is strongly influenced by the season,and the herb biomass plays an important role in the ignition of wood biomass.The method of life cycle assessment(LCA)was used to investigate the energy consumption and pollutant emission of the five stages from the plant harvest to the decommissioning of biomass power plant.Analytical results revealed that Hybrid Giant Napier is an environmentally-friendly biomass energy plant in direct-fired power generation with development potential.Therefore,it can be used as an alternative fuel at straw shortage period.