The flow field in a cold model of 2500 t/d five-stage cyclone preheater and precalciner system was numerically simulated. Renault stress model (RSM) turbulent model was adopted to simulate the flow field, and a hybrid...The flow field in a cold model of 2500 t/d five-stage cyclone preheater and precalciner system was numerically simulated. Renault stress model (RSM) turbulent model was adopted to simulate the flow field, and a hybrid mesh scheme was selected to generate calculation mesh. With the first order upwind difference, finite-volume method was used to convert turbulent equations into difference equations pressure-velocity coupling which were solved by the classic simple algorithm, and during the course of numerical solution, mesh self-adapting technology was applied. The main flow field structures of the whole system and each part of the cold model were studied by analyzing the simulation results.展开更多
Ammonium bisulfate(ABS)is a viscous compound produced by the escape NH_(3) in the NO reduction process and SO_(3) in the flue gas at a certain temperature,which can cause the ash corrosion of the air preheater in coal...Ammonium bisulfate(ABS)is a viscous compound produced by the escape NH_(3) in the NO reduction process and SO_(3) in the flue gas at a certain temperature,which can cause the ash corrosion of the air preheater in coal-fired power plants.Therefore,it is essential to study the formation temperature of ABS to prevent the deposition of ABS in air preheaters.In this paper,the SO_(3) reaction kinetic model is used to analyze the SO_(3) generation process from coal combustion to the selective catalytic reduction(SCR)exit stage,and the kinetic model of NO reduction is used to analyze the NH_(3) escape process.A prediction model for calculating the ABS formation temperature based on the S content in coal and NO reduction parameters of the SCR is proposed,solving the difficulty of measuring SO_(3) concentration and NH_(3) concentration in the previous calculation equation of ABS formation temperature.And the reliability of the model is verified by the actual data of the power plant.Then the influence of S content in coal,NH_(3)/NO_(x) molar ratio,different NO_(x) concentrations at SCR inlet,and NO removal efficiency on the formation temperature of ABS are analyzed.展开更多
Demand of cement in developing countries is directly proportional to the development rate of that country. But increasing input cost of cement manufacturing, decreasing margin of profit, scarcity of raw coal availabil...Demand of cement in developing countries is directly proportional to the development rate of that country. But increasing input cost of cement manufacturing, decreasing margin of profit, scarcity of raw coal availability and emission of greenhouse gases are some constraints, which restrict the growth of cement industry. Hence to combat with all these adverse situations simultaneously, this project report introduces and efforts to generate clean and green energy with the help of combination of preheater tower, which is available in all integrated cement plants and an augmented wind turbine. Hence, the technology is named as “Power Producing Preheaters” or 3P.H. Introduction of 3P.H. in cement industry, generates a definite amount of clean and green energy (as per site conditions), which is directly used in cement production to avoid grid connectivity cost of wind turbine output. Calculations are done to show the overall cost of project, its payback period and reduction in emission of greenhouse gases along with its benefits in cement industry.展开更多
Compound casting is an efficient method for bonding dissimilar metals,in which a dramatic reaction can occur between the melt and solid.The centrifugal casting process,a type of compound casting,was applied to cast Al...Compound casting is an efficient method for bonding dissimilar metals,in which a dramatic reaction can occur between the melt and solid.The centrifugal casting process,a type of compound casting,was applied to cast Al/Mg dissimilar bimetals.Magnesium melt was poured at 700 °C,with melt-to-solid volume ratios(Vm/Vs) of 1.5 and 3,into a preheated hollow aluminum cylinder.The preheating temperatures of the solid part were 320,400,and 450 °C,and the constant rotational speed was 1,600 rpm.The cast parts were kept inside the casting machine until reaching the cooling temperature of 150 °C.The result showed that an increase in preheating temperature from 320 to 450 °C led to an enhanced reaction layer thickness.In addition,an increase in the Vm/Vs from 1.5 to 3 resulted in raising the interface thickness from 1.2 to 1.8 mm.Moreover,the interface was not continuously formed when a Vm/Vs of 3 was selected.In this case,the force of contraction overcame the resultant acting force on the interface.An interface formed at the volume ratio of 1.5 was examined using scanning electron microscopy(SEM) equipped with energy-dispersive X-ray spectroscopy(EDS),and the results demonstrated the formation of Al_(3)Mg_(2),Al_(12)Mg_(17) and(δ+Al_(12)Mg_(17)) eutectic structures in the interface.展开更多
文摘The flow field in a cold model of 2500 t/d five-stage cyclone preheater and precalciner system was numerically simulated. Renault stress model (RSM) turbulent model was adopted to simulate the flow field, and a hybrid mesh scheme was selected to generate calculation mesh. With the first order upwind difference, finite-volume method was used to convert turbulent equations into difference equations pressure-velocity coupling which were solved by the classic simple algorithm, and during the course of numerical solution, mesh self-adapting technology was applied. The main flow field structures of the whole system and each part of the cold model were studied by analyzing the simulation results.
基金the Key Research and Development Plan of Shandong Province (2019GSF109004)Natural Science Foundation of Shandong Province (ZR2020ME190) for funding and supporting this work
文摘Ammonium bisulfate(ABS)is a viscous compound produced by the escape NH_(3) in the NO reduction process and SO_(3) in the flue gas at a certain temperature,which can cause the ash corrosion of the air preheater in coal-fired power plants.Therefore,it is essential to study the formation temperature of ABS to prevent the deposition of ABS in air preheaters.In this paper,the SO_(3) reaction kinetic model is used to analyze the SO_(3) generation process from coal combustion to the selective catalytic reduction(SCR)exit stage,and the kinetic model of NO reduction is used to analyze the NH_(3) escape process.A prediction model for calculating the ABS formation temperature based on the S content in coal and NO reduction parameters of the SCR is proposed,solving the difficulty of measuring SO_(3) concentration and NH_(3) concentration in the previous calculation equation of ABS formation temperature.And the reliability of the model is verified by the actual data of the power plant.Then the influence of S content in coal,NH_(3)/NO_(x) molar ratio,different NO_(x) concentrations at SCR inlet,and NO removal efficiency on the formation temperature of ABS are analyzed.
文摘Demand of cement in developing countries is directly proportional to the development rate of that country. But increasing input cost of cement manufacturing, decreasing margin of profit, scarcity of raw coal availability and emission of greenhouse gases are some constraints, which restrict the growth of cement industry. Hence to combat with all these adverse situations simultaneously, this project report introduces and efforts to generate clean and green energy with the help of combination of preheater tower, which is available in all integrated cement plants and an augmented wind turbine. Hence, the technology is named as “Power Producing Preheaters” or 3P.H. Introduction of 3P.H. in cement industry, generates a definite amount of clean and green energy (as per site conditions), which is directly used in cement production to avoid grid connectivity cost of wind turbine output. Calculations are done to show the overall cost of project, its payback period and reduction in emission of greenhouse gases along with its benefits in cement industry.
文摘Compound casting is an efficient method for bonding dissimilar metals,in which a dramatic reaction can occur between the melt and solid.The centrifugal casting process,a type of compound casting,was applied to cast Al/Mg dissimilar bimetals.Magnesium melt was poured at 700 °C,with melt-to-solid volume ratios(Vm/Vs) of 1.5 and 3,into a preheated hollow aluminum cylinder.The preheating temperatures of the solid part were 320,400,and 450 °C,and the constant rotational speed was 1,600 rpm.The cast parts were kept inside the casting machine until reaching the cooling temperature of 150 °C.The result showed that an increase in preheating temperature from 320 to 450 °C led to an enhanced reaction layer thickness.In addition,an increase in the Vm/Vs from 1.5 to 3 resulted in raising the interface thickness from 1.2 to 1.8 mm.Moreover,the interface was not continuously formed when a Vm/Vs of 3 was selected.In this case,the force of contraction overcame the resultant acting force on the interface.An interface formed at the volume ratio of 1.5 was examined using scanning electron microscopy(SEM) equipped with energy-dispersive X-ray spectroscopy(EDS),and the results demonstrated the formation of Al_(3)Mg_(2),Al_(12)Mg_(17) and(δ+Al_(12)Mg_(17)) eutectic structures in the interface.
