| Coke oven coking is an important basis for the development of Chinese steel-making industry.Large-scale coke oven is the inevitable choice for the development of coke oven coking.Although large-scale coke oven was equipped with a complete set of dust collection and dedusting equipment for pollution control,the dust collection equipment used by various coking enterprises in actual production was difficult to achieve a complete collection of the smoke and dust discharged in the process of coke pushing,which resulted in visual smoke and dust emissions,and cloud not meet the requirements of environmental protection.The pollution emission of coking mainly involves the high-temperature soot airflow in the carbonization room,because it is discharged from the coke oven head in a short period of time during the coke pushing process,while the current dust collection equipment is unable to collect the soot completely,causing the spread of furnace head smoke.At the same time,the lack of theoretical researches on high temperature buoyant jet diffusion and high temperature buoyant jet impact diffusion caused the difficulties to design various dust collection and ventilation systems and to complete and efficiently captured the discharged flue gas for the coke oven dust collecting equipment,which was one of the important reasons for the difficulty in completely controlling the furnace head smoke in the coking process.Coke oven coking is an important basis for steel-making industrial development of China.Large-scale coke oven is the inevitable choice for development of coke oven coking which is equipped with a complete set of dust collection and dedusting equipment for pollution control.However,the dust collection equipment used by various coking enterprises in practice is difficult to achieve a complete collection of the smoke and dust discharged in the process of coke pushing,which results in visual smoke and dust emissions.It cannot meet the requirements of environmental protection.The pollution emission of coking mainly involves the high-temperature soot airflow in the carbonization room.And this airflow is discharged from the coke oven head in a short period of time during the coke pushing process.However,the current dust collection equipment is unable to collect the soot completely.At present,there is a lack of research on high temperature buoyant jet diffusion and high temperature buoyant jet impact diffusion.Moreover,the design of various dust collection and ventilation systems lacks sufficient theoretical guidance.That makes it difficult for coke oven dust collection equipment to complete the high temperature buoyancy diffusion and high temperature impact diffusion of smoke efficient treatment.In this paper,the theoretic analysis,experimental research,and numerical analysis were used to research and analyze the high-temperature smoke gas diffusion,the impact diffusion of high-temperature smoke gas,and the operating characteristics of the guided side suction dust collection and ventilation system.The author proposed the buoyant jet diffusion model and gas-solid coupling diffusion model of coke oven flue gas.And the dust collecting cover of coke oven flue gas was optimized according to the model results,which realized the complete collection of different emission forms of flue gas,reduced the air volume demand of dust collecting cover,and improved the collection efficiency of flue gas.The main research contents of the paper were as follows.(1)By analyzing and testing the emission process of smoke and dust gas from machine side,coke side and furnace top in the coking process of various types of ramming coke oven and top-loading coke oven,the emission rules of smoke and dust gas,the characteristics of smoke and dust gas components and the emission differences in the coking process of coke oven were obtained.At the same time,the influences of the diffusivity characteristics of hearth smoke on the diversion structure,suction velocity and boundary distribution design of hearth smoke hood were analyzed and determined.(2)By analyzing the theory of buoyancy jet diffusion and comparing various analytical models of buoyancy jet diffusion,the horizontal plane buoyancy jet diffusion model of hearth smoke was proposed based on the analysis of the characteristics of dry air changing with temperature.Based on the theory of wall-attached jet,the theory of impingement diffusion and the process of ceiling jet diffusion,the paper presented the impingement diffusion model of the vertical discharge of hearth smoke along the near wall surface.Based on the analysis of the mechanical model of soot particles in the fluid,a gas-solid coupling analysis model based on soot gas was proposed.A gas-solid coupling analysis model based on soot gas was proposed in this paper based on the analysis of the mechanical model of soot particles in the fluid.(3)Based on the similarity theory,the model test and the numerical analysis model of flue gas diffusion analysis were established,which verified the correctness of the numerical model.The variation rules of jet velocity and jet trajectory in the diffusion of high temperature plane buoyancy jet were obtained,as well as the diffusion characteristics of particles in the two-phase flow diffusion of high temperature plane buoyancy jet.The distribution characteristics of jet velocity along the side plate and roof were obtained,as well as the influence of inclination of inclined guide roof and jet flow temperature on the distribution of jet velocity on the roof.The results of diffusion boundary and diffusion velocity of coke oven hearth smoke in different discharge processes were obtained,which provided the basis for the design optimization of hearth smoke hood.(4)The dust collecting structure of the side suction hood was designed based on the theory of side suction and collection ventilation.And three factors affecting the collecting efficiency of the side suction hood were determined:the inclination angle of the guide plate,the suction speed of the dust collection hood and the width of the dust collection hood.By means of experiments and numerical analysis,the paper determined the dust collection process of impingement efflux diffusing flue gas on the near wall surface by the deflector side suction hood.The increase of the inclination angle of the deflector and the temperature of the flue gas would increase the diffusion speed of the jet along the deflector and decrease the dust collection efficiency.At the same suction air volume,the dust collection efficiency could be achieved by increasing the dust collection speed by increasing the width ratio of the dust collection hood.(5)Based on the characteristics of smoke diffusion and the characteristics of the deflector dust collecting cover,the optimization scheme of the smoke collecting cover of coke oven was put forward,which solved the problems of the traditional smoke collecting cover,such as the small effective dust collecting section,the lack of smoke controlling wind speed and the problem of the hearth smoke emission and reduces the design air volume of the flue gas hood at the furnace head by more than 30%.Through the design of distributed dust collection structure,combined with flue gas pretreatment unit,cyclone bag dust collection and chain control test scheme,an efficient and convenient vehicle mounted dust collection system of coke was obtained,which solved the problem of flue gas treatment at the side of top loaded coke oven and reduced the flue gas emission concentration to less than 10 mg/m~3.In order to solve the problem of treatment the dust particles collected by the duster,a new method of preparing coke ash slurry was proposed in this paper,which provided an important basis for treatment of flue gas diffusion at coke furnace head. |
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