Study On Optimization Of Incinerator Suitable For High Calorific Value Solid Waste

In the 21st century,while China’s comprehensive national strength is constantly improving and the people’s quality of life is steadily advancing,China’s vigorous development of urbanization has brought about an obvious problem:the output of garbage has increased significantly,and then the garbage classification policy has been implemented.With the improvement of the national garbage classification related systems and regulations,garbage classification has entered the right track;The classified garbage has low moisture and high calorific value;Compared with other treatment methods,waste incineration power generation technology has obvious advantages such as"good reduction effect,high harmless degree and high resource utilization rate".Among them,compared with other incineration technologies,mechanical grate incinerator technology has obvious advantages and is the most widely used,which is the subject of research.With the change of composition and calorific value after garbage classification,the original incinerator designed for"high moisture and low calorific value"can no longer meet the demand.Blindly burning the classified high calorific value garbage may bring hidden dangers to the operating incinerator.For the newly designed incinerator,the current situation of"low moisture and high calorific value"of garbage must be considered.In this paper,the burning of high calorific value waste in incinerators is studied by means of experiments and numerical simulation,and optimization suggestions are proposed for possible problems,so as to provide basis for the design and operation of incinerators in the future.First,FLIC bed combustion simulation software is used to simulate the combustion of garbage with different moisture content on the bed.The results show that garbage with 20%humidity content catch fire about 1.8m earlier than garbage with 55.7%,volatile combustion start is extended by 2m,and the maximum gas temperature is increased by over 200℃.Next,the combustion characteristics test of waste with different calorific values on the pilot incineration plant test platform was carried out to get the temperature,speed,concentration and other characteristics of the two types of waste after incineration in the furnace,as well as the pollutant emission characteristics.The results show that when the calorific values of two types of garbage are respectively 12198 k J/kg and 6598 k J/kg,in the working condition of incineration of high calorific value garbage,the average temperature above the grate and the average temperature of the first flue is 690℃and 1047℃,It is about 50℃and 146℃higher than the working conditions of incineration of low calorific value garbage,and the temperature in the furnace is too high,which can cause problems such as burning the grate,coking in the furnace,generating harmful gases and early ignition,which can burn the gate door at the garbage inlet.Then,taking as the simulation object the 650 t/d mechanical grating incineration plant in Hangzhou,the original structure and design parameters of the incineration plant are simulated according to the high calorific value of the waste to be processed,including the establishment of physical models.First,FLIC bed combustion simulation software is used to simulate the combustion of high calorific waste on the bed under the initial combustion plant design and initial design parameters,and then simulated gas phase（CH₄,Co,H₂O（g）,CO₂）concentration,speed and temperature are imported into FLUENT software by script code as the grid inlet limit condition for gas phase combustion simulation,Finally,important parameters such as temperature distribution and concentration distribution of gas components in the furnace and at the first exhaust output are obtained.According to the simulation results,a strategy for optimizing the combustion plant structure and operating parameters is proposed,and the optimized operating parameters and improved combustion plant structure are still examined by the numerical simulation method.Finally,the design of the incineration plant and important operating parameters suitable for the incineration of classified waste with high calorific value are obtained.The results show that when the basic air ratio of the four combustion chambers is adjusted from20%,30%and 20%to 10%,20%,40%and 30%,Secondary air temperature is reduced from 180℃to 25℃.At the same time,to improve combustion conditions in the furnace,the structure is optimized,and the location of the secondary air nozzle on the upper front and rear walls remains unchanged.The distance of the lower secondary air nozzle on the front wall is adjustable to 1700mm,and the angle of the rear arch is optimized to 40°.When burning high calorific value,the furnace temperature is about℃,Parameters such as the concentration of gas components meet the requirements of the relevant national standards for waste incineration plants.Optimized combustion plant design is suitable for incineration of classified waste with high calorific value.