| With the rapid development of China ’s economy and the continuous improvement of people ’s living standards,the environmental problems caused by the substantial increase in the production of municipal solid waste(MSW)are becoming more and more serious.The gasification and melting technology can achieve the harmless,volume reduction and resource treatment of waste.Since the gasification and melting system is composed of multiple process units,each unit interacts with each other before and after.At present,most of the research focuses on the pyrolysis characteristics of MSW and the generation and emission of pollutants.However,the research on the influence between the gasification and melting process system modules and the linkage change process of material flow and energy flow between each reactor is insufficient.This paper mainly simulates the whole process of MSW gasification and melting process,and studies the influence of fuel parameters,operating parameters and waste blending on the process node parameters,material flow and energy flow in the gasification and melting system to better obtain the whole process operation rules and the best operating parameters.In order to improve the slag capture efficiency of the cyclone melting furnace,a new type of annular cyclone melting furnace is proposed in this paper.The gas-solid two-phase flow field in the annular cyclone melting furnace is simulated by numerical calculation method.The particle movement and slag capture process of the annular cyclone melting furnace are studied.The factors affecting the particle movement and slag capture efficiency in the annular cyclone melting furnace are found out,which provides a certain reference value for the operation rules and structural size of the annular cyclone melting furnace.Firstly,Aspen Plus process simulation software was used to establish the simulation process of waste gasification and melting.The actual process was divided into four stages :drying,pyrolysis,gasification and melting.The RStoic module was used in the drying section,the RYield module and the RGibbs module were used in the pyrolysis gasification section,and the RGibbs module was used in the melting section.The pyrolysis temperature of MSW gasification and melting was determined,and the optimum pyrolysis temperature was 500 ℃.The basic working conditions of MSW gasification and melting were studied by process simulation.The results show that the main products of MSW gasification are combustible gases hydrogen and carbon monoxide.Different gasification agents have obvious effects on the simulation results of MSW gasification and melting,which are mainly manifested in the difference of carbon conversion rate,low calorific value of syngas and energy input required for pyrolysis and gasification stage.Secondly,the whole process of waste gasification and melting is simulated,and the effects of fuel parameters(waste moisture content,fly ash melting temperature)and operating parameters(drying temperature,gasification temperature,chemical equivalent ratio)on process node parameters,material flow and energy flow in the process of waste gasification and melting are discussed.The simulation results show that the waste gasification and melting system can achieve energy self-sufficiency through flue gas circulation when the moisture content of waste is less than 9%.When the gasification temperature is 850 ℃ and the steam ratio is 0.5,the system gasification effect is the best.At the same time,the waste was mixed with pulverized coal and biomass straw to study the characteristics of co-gasification and melting of waste.The results show that the effective syngas yield and low-temperature calorific value of syngas after gasification and melting of waste blending are higher than those of waste gasification and melting alone,and the mixing structure of waste and pulverized coal is better than that of waste and biomass straw.Finally,the Fluent software was used to simulate the gas-solid two-phase flow field movement law and the slag capture process in the annular cyclone melting furnace.The effects of velocity field and pressure field on particle motion and slag capture efficiency were studied by changing the structural parameters(ring ratio of annular cyclone melting furnace)and operating parameters(secondary wind speed and particle size)of annular cyclone melting furnace.The results show that with the increase of the ring ratio,the tangential velocity and axial velocity of the flow field near the inner wall are larger.The secondary wind speed affects the flow field above the secondary tuyere.The larger the secondary wind speed,the greater the entrainment effect in this area,and the closer the particles are captured to the upper part of the melting furnace.When the ring ratio is 4 : 1,the slag capture rate of the annular cyclone melting furnace is the largest;fine particles are more easily trapped on the inner ring.When the particle size is small,the influence of secondary wind speed on the trapped particles on the inner ring wall is smaller. |
