Optimization Of Fly Ash Desalination Treatment Process And Its Energy Consumption Analysis

Urban solid waste incineration treatment has become the mainstream technology of waste disposal in today’s society,fly ash is the residue produced in the flue gas purification system during the domestic waste incineration process,fly ash has a variety of harmful substances,regarded as hazardous waste,but the chloride salt in fly ash and similar composition of building raw materials make it still have great recycling value,how to reduce the treatment cost of domestic waste incineration fly ash is a hot issue in China’s development in recent years.In order to realize the safe and economical disposal and utilization of fly ash,this paper designs the optimization process of fly ash water elution desalination and water washing wastewater treatment based on energy consumption and economy.The main research contents and conclusions are as follows:(1)In order to study the effect of water washing method on chloride ions in fly ash,the influence of liquid-solid ratio,washing time and washing temperature on the removal effect of chloride ions was investigated.The results showed that when the liquid-solid ratio was 12:1,the washing time was 25 min,and the washing temperature was 25°C,the chloride ion removal rate in fly ash was 88.72%.The removal effect of countercurrent washing method and primary water washing was compared.The results show that under the same liquid-solid ratio,compared with the primary water wash,the secondary counterflow water washing can effectively save water consumption,and at the same time improve the dechlorination effect of fly ash,and the improvement effect is the most obvious when the solid ratio of the washing liquid is 2～6 m L/g.(2)A reverse osmosis membrane concentration pretreatment process suitable for treating high-concentration saline wastewater is proposed,and a solution is proposed to the problem that affects the separation effect in the reverse osmosis membrane separation process.From the analysis of the energy consumption direction of the combined process,the concentration of wastewater treated by concentration pretreatment is too large or too small,which will lead to an increase in the energy consumption of the combined process,so the concentration of concentrated liquid treated by reverse osmosis membrane should be controlled at about 30%.(3)The thermal calculation model of the main equipment in the MVR system is constructed and the thermal performance of the optimized MVR system and the reference system is analyzed,and the results show that the energy efficiency ratio of the MVR optimization process is improved by about 15% compared with the traditional single-stage MVR system.Aspen Plus software was used to simulate the evaporation crystallization process of MVR and study the influence of important parameters such as discharge concentration,evaporation temperature and heat transfer temperature difference on the energy consumption of MVR system and heat transfer area of heat exchanger.(4)Design calculation and check of the main structure of the evaporator,conduct fluid and heat transfer simulation analysis according to the structural parameters of the evaporator and the physical properties of the fluid medium,and use Ansys fluent software to simulate the heat transfer process of the internal fluid of the evaporator,and obtain the internal temperature and velocity distribution of the fluid to meet the working operation requirements of the evaporator.(5)According to the treatment scale of the original process,determine the main equipment model of each unit of the fly ash treatment optimization process,calculate the cost of the whole system,establish the economic calculation model of each unit,and compare and analyze the operating cost of the original fly ash treatment process,the results show that under the condition of annual treatment of 100,000 tons of domestic waste incineration fly ash,The annual treatment cost of fly ash in the optimized process designed in this project is 1,692,400 yuan,and the annual operating cost is 774,700 yuan less than that of the original process,which has significant economic benefits.