Structural Optimization And Heat Transfer And Mechanics Characteristics Analysis Of Copper Water Jacket In Reaction Shaft Of Kivcet Furnace

When the Kivcet furnace is in operation,oxygen-rich melting is carried out in the reactor with high volumetric thermal strength.The life of copper water jacket in the reactor is an important factor to determine the operation life of Kivcet furnace.At present,the design and operation adjustment of copper water jacket are mostly based on experience and lack of theoretical basis and foresight.In this paper,the water jacket in reaction shaft of Kivcet furnace was taken as the research object,and the numerical calculation models were established to study heat transfer and mechanics characteristics of copper water jacket in reaction shaft.In addition,the structure of the copper water jacket was optimized.The main conclusions of this work are summarized as follows:（1）A heat transfer model of copper water jacket in the reactor was established to analyze the flow heat transfer characteristics of water jacket under different process parameters.The results show that increasing cooling water flow rate will increase the load of pipe wall while enhancing heat transfer.With the increase of near-wall flue gas temperature,the maximum temperature of water jacket,heat flux intensity and heat transfer coefficient increase linearly,and the slag thickness decreases and the distribution becomes more uneven.The best parameter of flow velocity is about 2 m·s^-1and thermal conductivity of refractory brick is about 3.2 W·m^-1·k^-1.（2）The heat transfer characteristics of copper water jacket under slag-falling out and regeneration conditions and extreme harsh conditions were analyzed by heat transfer model.The results show that when slag skin is regenerated in time,the single slag skin falling-regeneration condition has little influence on the safety of the jacket.Under the extreme working condition that slag skin is not regenerated in time,the working indexes of water jacket are far higher than that in normal working conditions,and it is difficult to run normally.（3）Considering the effect of temperature load and pressure load,a stress calculation model of copper water jacket in reaction shaft was established to analysis mechanics characteristic of the water jacket under different process parameters.The results show that the maximum stress on the hot surface occurs in the chamfering region at the top of the wedge groove,and the stress mutation exists in the root wall of the inlet and outlet pipes.The hot surface of the water jacket is convex and the wall surface is curved.With the increase of flue gas temperature,the deformation of water jacket and the equivalent stress of pipe root and hot surface both increase.The increasement of cooling water velocity will lead to the increase of water jacket deformation and the maximum stress of pipe root,but has little effect on the maximum equivalent stress of hot surface.（4）Mechanics characteristics of copper water jacket under slag falling out and regeneration conditions and extreme harsh conditions were analyzed by stress calculation model.The results show that the deformation and stress increase significantly in 60s and gradually recover with the regeneration of slag.Plastic deformation occurs in the local area of the pipe root and hot surface at 60s.Under extreme conditions,the deformation and stress level increase further,but the stress level is still far below the tensile limit.Root fracture of water jacket in the production is mainly caused by slag falling off and regenerating frequently,plastic accumulation of root causes thermal fatigue failure.according to the calculation,there is no fatigue failure in the upper and lower water jacket of the reactor,the thermal fatigue life of copper water jacket of reaction shaft in central is about 12.7 years under normal working condition,and is reduced to 8 years under abnormal conditions（flue gas temperature1450℃）.（5）The structure of copper water jacket in reaction shaft was optimized by response surface optimization method,with the water jacket mass,maximum deformation and maximum equivalent stress on the hot surface as the optimization objectives.After optimization,the thermal fatigue life of tube root is increased by 2.4 years,the maximum deformation is decreased by about 8.0%,the mass is reduced by 3.62%,and the construction cost of Kivcet furnace can be saved by 290,700yuan.