Thermal Calculation And Numerical Simulation Of Cruise Waste Incineration System

In recent years,the problem of marine environmental pollution has attracted more and more attention.With the development of China’s economy,the issue of preventing marine pollution caused by ships has been put in front of us.In order to make the design,production and inspection level of marine incineration system,an important part of it,reach and exceed the international level,the research on the waste incineration system is particularly important.Therefore,it is necessary to determine the cruise incineration system as the research object of this thesis.The main work and conclusions are as follows:Firstly,the total daily waste generated by the data of the per production of the parent ship is 31.2t/d,the total daily generated amount of garbage by each classification is 31.6t/d,and the daily incineration capacity is 22.8t/d.The fuel characteristics of the combustible waste of cruise ship are determined,and the final low calorific value of the waste is obtained,and the value is 7535 k J/kg.Secondly,the waste incineration system is divided into three areas,namely incinerator body,secondary combustion chamber and quench tower.Their structural parameters are designed and determined respectively.The rationality of design data is ensured by checking and calculating,which provides accurate and correct modeling dimensions for simulation simulation.The influence of water spray and primary and secondary air inlet is considered in the thermal calculation of furnace,and the air inlet air volume and water spray quantity of primary and secondary air are obtained which are suitable for incineration of ship waste.The heat and flue gas quantity brought in by auxiliary combustion are considered in the thermal calculation of the second combustion chamber.Combined with the thermal data of furnace,the appropriate auxiliary fuel consumption is obtained.The flue gas heat and flue gas velocity at the outlet of the second combustion chamber are updated,which provides a reference for simulation.In order to make the outlet smoke temperature reach the proper range,the spray water quantity of spray layer is designed according to the inlet smoke temperature and smoke quantity.Finally,the exit boundary conditions of the whole incineration system are determined.In order to ensure that the external wall temperature of the incineration system does not exceed the ambient temperature of 15 ℃,the structure of the furnace wall is designed and determined.The heat transfer calculation is carried out for the furnace wall and air.Finally,the wall temperature of the incinerator in this thesis is within the safe range.Then,based on the visual programming software Excel Visual Basic for applications,a set of thermal software for marine incinerator is developed.The operation interface,calculation function and detailed usage method of the software are introduced in detail.The relationship between excess air coefficient at furnace outlet and actual output flue gas heat is studied by using thermal software.It is found that the incinerator is most suitable for cooling flue gas with moderate water spray under the condition of furnace air leakage coefficient of about 1.8.Through the investigation of the relationship between the total excess air coefficient and the furnace temperature,it is found that the furnace temperature increases with the increase of the total excess air coefficient,while the temperature of the second combustion chamber decreases with the increase of the total excess air coefficient.Through the study of the relationship between the wind speed of cooling interlayer and the temperature of the outer wall of furnace wall,it is found that when the cooling wind speed is within 2-5m/s,the temperature of the outer wall of the furnace wall drops sharply.When the cooling wind speed is within the range of 5-15m/s,the temperature of the furnace wall appears abnormal rising trend.When the cooling wind speed reaches more than 15m/s,the temperature of the outer wall of the furnace wall decreases smoothly,and finally tends to about 35 ℃.And the reasons of these phenomena are explained.Finally,the combustion simulation analysis of the whole incineration system is carried out by FLUENT software.The results show that the water spray in the furnace of 6500 passenger ship waste incineration system is 0.22kg/s and the suitable excess air coefficient is 1.8.The correctness of software preparation is verified.