Co-combustion Characteristics Of Sludge And Coal Slime In A Fluidized Bed And The Design Of The Reaction Device

The output of sludge sewage（SS）and coal slime（CS）is huge.A large amount of sludge sewage and coal slime has not been properly disposed of.Unreasonable disposal methods will cause secondary pollution of the environment,damage to human health and waste of resources.There is an urgent need for a reduction,harmless and resource-based disposal method.Based on experiments and simulation methods,this paper studies the co-combustion characteristics,combustion kinetics,gas-solid flow characteristics,and pollutant emission characteristics of sludge sewage and coal slime;a fluidized bed with integrated drying and incineration of sludge and slime is designed;Numerical simulation of industrial-grade sludge and slime co-combustion fluidized bed was carried out to understand the gas-solid flow characteristics,combustion characteristics and pollutant emission characteristics of sludge and slime in the fluidized bed.The main contents include:The co-combustion characteristics and combustion kinetics characteristics of sludge sewage and coal slime were studied.The results show that with the increase of the sludge sewage mass fraction,the ignition point decreases and the burn-out temperature increases.The combustion characteristic parameter of the mixed fuel containing 25%sludge is 2.56×10^-8%²min^-2·K^-3.The best features.When 25%sludge sewage is mixed with coal slurry,the synergistic effect is strong,and the activation energy is reduced from 112 k J/mol when coal slurry is burned alone to 88.6 k J/mol.The coordinated combustion of sludge sewage and coal slime conforms to the reaction order model.With the increase of the sludge sewage mass fraction,the reaction order and the pre-exponential factor both increase.At the same time,the fluidization characteristics of sludge sewage and coal slime were studied.It was found that the fluidization characteristics of sludge sewage and coal slime alone were poor.The addition of quartz sand can improve the fluidization characteristics,and the fluidization characteristics of mixed particles are similar to that of quartz sand.The conclusions obtained provide references for the design and operation of the sludge and slime fluidized bed.The effects of sludge sewage mass fraction,temperature and water content on the emission of pollutants from the co-combustion of sludge and slime were studied.The results show that the total amount of SO₂ emissions does not change significantly with the mass fraction of sludge sewage,it rises with the rise of temperature,and decreases with the increase of water content;the total amount of NO emissions does not change significantly with the mass fraction of sludge sewage,Decreases with the increase of temperature and water content;the total discharge of HCl increases with the increase of sludge sewage mass fraction,temperature and water content.The sludge mass fraction is 25%,the temperature is 800℃,and the water content is 15%are the most suitable conditions.The ash composition after co-combustion of sludge sewage and coal slime under different conditions was studied,and it was found that the sulfate diffraction peak in the ash changed greatly with the sludge sewage mass fraction and temperature.According to the integrated fluidized bed drying and incineration process,a fluidized bed with a rated processing capacity of 1200t/d of sludge sewage and coal slime was designed,and the main equipment of the process was calculated.According to the research content of the first two chapters,the rated working condition is 800℃,the sludge mass fraction is 25%,and the main parameters of the fluidized bed are calculated and explained.Using Aspen Plus to simulate the sludge sewage and coal slime drying and incineration process.It is found that as the mass fraction of sludge sewage increases,the thermal efficiency of the boiler decreases;as the load of the boiler increases,the thermal efficiency of the boiler increases.A model of co-combustion of sludge sewage and coal slime in a fluidized bed was established.The model is validated by relying on the gas-solid flow characteristics in the cold state and the pollutant emission law in the hot state.The co-combustion of industrial-grade sludge sewage and coal slime fluidized bed is simulated,and the drying fluidized bed has a great influence on the temperature of the incineration fluidized bed.Relying on the feed of the dried fluidized bed is difficult to meet the combustion,the flue gas at the furnace outlet is relatively low,and the O₂concentration is relatively high.An optimization scheme was proposed.The temperature field distribution of the new model is more uniform,and the consumption of O₂ is increased.Finally,the emission characteristics of pollutants are predicted.With the increase of excess air coefficient,both SO₂ and NO emissions increase,and the increase of secondary air helps reduce NO emissions.