Simulation And Optimization Of Waste Drying System In Waste Incineration Power Plant

Due to the principle of waste treatment,municipal solid waste incineration(MSWI)power generation technology has been widely used to better realize the conversion between waste and energy.With the wide application of MSWI power generation technology and the introduction of municipal solid waste(MSW)classification policy,some problems of MSWI have been concerned.At present,MSW used for incineration has a high moisture content in China,so the design of MSWI boilers is carried out according to the high moisture content.However,the problems of the high moisture content and low calorific value of MSW will cause problems such as high exhaust gas temperature,poor thermal economy and low income of power plant.At the same time,with the introduction of MSW classification policies,the moisture content of MSW will be greatly reduced,which will affect the normal operation of the existing MSWI boilers.Therefore,for improve the adaptability of the existing MSWI boilers and improve the efficiency of the MSWI power plant,this paper will do simulation and optimization research on the waste drying system.Firstly,this paper took a MSWI power plant in Shandong Province as the research object,and used Ebsilon to build the thermal system of MSWI boiler and steam turbine.Perform error analysis on simulation data and design data to verify the accuracy of the model.Based on the accurate model,the coupling of MSWI boiler and steam turbine was realized.Combined with the actual operation of the equipment,the waste drying system was proposed,which included:garbage drying component,negative pressure air leakage component and gas-liquid separation component.Ebsilon was used to build the waste drying system model.Secondly,the flue gas drying system using waste heat of flue gas to dry waste was proposed in this paper,and simulated drying waste to the moisture content of 20%.Through parameter analysis,it is pointed out that the flue gas drying system has limitations,and it is recommended to combine drying with other heat sources.To improve the adaptability of the boiler,this paper proposes to use recycled flue gas to replace the dried water.Thirdly,this paper proposed the steam drying system to avoid the limitations of flue gas drying system.At the same time,four optimization schemes were proposed,and the use of mixed gas for heating under heating conditions was proposed.In each scheme,full consideration was given to energy recovery and utilization to reduce energy loss.According to the analysis of thermal economy and power plant income,it is suggested that the scheme of deaerator extraction and deaerator front backwater is the best one applicable to both the condensing condition and the heating condition,and increasing the heat supply can improve the power plant income.Under the condensing condition,the total plant efficiency of the scheme increases from 22.8%of the original power plant system to 26.9%,and under the heating condition,the total plant efficiency of the scheme increases from 27.9%to 32.5%.However,a large amount of steam in the steam drying system is used to dry waste,which limits the growth of power generation.Fourthly,combining the advantages and disadvantages of flue gas drying system and steam drying system,the combined drying system of flue gas and steam drying was proposed.The optimization scheme and energy recovery method of the combined drying system were the same as that of the steam drying system.Through thermal economic analysis,it is found that the optimal scheme of the condensing condition is inconsistent with that of the heating condition.Further analysis of the power plant income determined that the deaerator extraction and low-pressure heater before the backwater scheme is the best system of the combined drying system,and it is proposed that increasing the heat supply can improve the power plant revenue.Under the condensing condition,the total plant efficiency of the scheme increases from 22.8%of the original power plant system to 28.7%,and under the heating condition,the total plant efficiency of the scheme increases from 27.9%to 34%.Finally,by comparing the steam drying system and the combined drying system,it is proposed that when the MAWI power plant adopts the waste drying technology,the deaerator extraction and low-pressure heater before the backwater scheme of the combined drying system should be given priority,and mixed gas should be used for heating in the heating condition.