The available studies in the literature on physical and mathematical modeling of the argon oxygen decarburization (AOD) process of stainless steel have briefly been reviewed. The latest advances made by the author wi...The available studies in the literature on physical and mathematical modeling of the argon oxygen decarburization (AOD) process of stainless steel have briefly been reviewed. The latest advances made by the author with his research group have been summarized. Water modeling was used to investigate the fluid flow and mixing characteristics in the bath of an 18 t AOD vessel, as well as the 'back attack' action of gas jets and its effects on the erosion and wear of the refractory lining, with sufficiently full kinematic similarity. The non rotating and rotating gas jets blown through two annular tuyeres, respectively of straight tube and spiral flat tube type, were employed in the experiments. The geometric similarity ratio between the model and its prototype (including the straight tube type tuyeres) was 1:3. The influences of the gas flow rate, the angle included between the two tuyeres and other operating parameters, and the suitability of the spiral tuyere as a practical application, were examined. These latest studies have clearly and successfully brought to light the fluid flow and mixing characteristics in the bath and the overall features of the back attack phenomena of gas jets during the blowing, and have offered a better understanding of the refining process. Besides, mathematical modeling for the refining process of stainless steel was carried out and a new mathematical model of the process was proposed and developed. The model performs the rate calculations of the refining and the mass and heat balances of the system. Also, the effects of the operating factors, including adding the slag materials, crop ends, and scrap, and alloy agents; the non isothermal conditions; the changes in the amounts of metal and slag during the refining; and other factors were all considered. The model was used to deal with and analyze the austenitic stainless steel making (including ultra low carbon steel) and was tested on data of 32 heats obtained in producing 304 grade steel in an 18 t AOD vessel. The changes in 展开更多
The gas-liquid two-phase flow patterns of a centrifugal pump during the self-priming process were investigated numerically and experimentally.The Euler-Euler multiphase model and SST k-ω turbulence model were applied...The gas-liquid two-phase flow patterns of a centrifugal pump during the self-priming process were investigated numerically and experimentally.The Euler-Euler multiphase model and SST k-ω turbulence model were applied for simulating the self-priming process.Meanwhile,the changes of motor speed and self-priming height were considered in the simulation.The overall transient two-phase flow features and water level distributions were mapped.Results showed that the self-priming process was divided into three stages.The liquid level in inlet-pipe rose in oscillation during self-priming process.The variations of water level during self-priming process of numerical simulation and test result agreed well.The inlet-pipe(Ver)was filled at 22 s and 24 s respectively numerically and experimentally.The bubble cloud circulated in the volute during middle stage of self-priming process,and breakup into smaller bubbles by shear force and tongue,and then discharged into chamber.The bubbles in the outlet-pipe mainly included bubbly flow and slug flow at the last stage of self-priming process,which is morphologically consistent with the test results.Also,during the self-priming process,the reflux liquid was pressed by blades and fully mixed with gas;that is the way to realizing the function of self-priming.展开更多
In order to increase the contact area and promote the mass transfer process of gas and liquid,the process of the bubble refine-ment in a metallurgical reactor with mechanical agitation was studied by physical simulati...In order to increase the contact area and promote the mass transfer process of gas and liquid,the process of the bubble refine-ment in a metallurgical reactor with mechanical agitation was studied by physical simulation.Based on the capillary number,a prediction equation for the bubble refinement was established.The effects of the gas flow rate,the stirring speed and thestirring depth on the bubble refinement in the reactor were discussed in detail.The distribution of the bubble diameter in thereactor was obtained under different conditions.The results show that when the stirring speed reaches 300 r/min,the bubblediamcter mainly distributes in the range of 1-2 mm.A higher gas flow rate may increase the number of bubbles in the meltand promote the bubble refinement process.The mechanism of bubble refinement under mechanical agitation was analyzed.and the results indicated that the stirring speed.,the blade area and the blade inclination are the main influencing factors.展开更多
Boil-Off Gas creation and usage has been a source of worry in Liquefied Natural Gas value supply chain. BOG is generated when there is temperature gradient between the environment and LNG temperature within the carrie...Boil-Off Gas creation and usage has been a source of worry in Liquefied Natural Gas value supply chain. BOG is generated when there is temperature gradient between the environment and LNG temperature within the carrier tank, process lines or vessels. In this work, Computer Aided Design for the recovery of BOG from flare in an LNG Plant considered the dynamic nature of the BOG with minimized total energy consumption. A rigorous simulation based optimization model using HYSYS V8.8 was presented. Possible BOG scenarios were formulated in this report and considerations taken from the BOG scenarios to form the basic scope of this work. An Aspen HYSYS Software was used to develop a Process Flow Scheme (PFS) which was simulated using the BOG scenarios formulated. The BOG scenario temperatures considered were -15°C for Warm Ship analogy, -90°C for Cold Ship and -140°C for Normal Design Mode. Assumptions were also made on the feed into the developed PFS before quenching the various BOG temperatures. With HYSYS simulation at assumed constant inlet mass flow rate of 25,000 kg/s for BOG FEED, 6250 kg/s for LNG & LNG1 FEED, quenching at various BOG feed temperature -15°C, -90°C and -140°C, gave a meaningful output. The Mass flow rate recovered from Warm Ship at -15°C for Cold Product was 35,183 Kg/s and for Liquid Product 2317 Kg/s. For Cold ship at -90°C, the Cold Product recovered was 32,174 Kg/s and Liquid Product was 5326 Kg/s. Also, for -140°C, the Cold Product was 28,004 Kg/s and the Liquid Product was 9496 Kg/s. The Energy stream for the Compressor, Cooler and Pump in the Process Flow Stream (PFS) were observed in Table 5. At -15°C, the Compressor energy was 3.22E+07KJ/h, while the Pump energy was 3412KJ/h, and the Cooler gave 1.90E+07KJ/h. The results above showed that excessive BOG from Warm ship can be quenched and recovered for other end users rather than undue flaring of the gases. Extra work needs to be done to ensure minimal energy utilisation, optimal recovery and high efficiency of this developed mod展开更多
In lost foam casting(LFC)the foam pattern is the key criterion,and the filling process is crucialto ensure the high quality of the foam pattern.Filling which lacks uniformity and denseness will cause variousdefects an...In lost foam casting(LFC)the foam pattern is the key criterion,and the filling process is crucialto ensure the high quality of the foam pattern.Filling which lacks uniformity and denseness will cause variousdefects and affect the surface quality of the casting.The influential factors of the filling process are realized in thisresearch.Optimization of the filling process,enhancement of efficiency,decrease of waste,etc.,are obtained bythe numerical simulation of the filling process using a computer.The equations governing the dense gas-solid two-phase flow are established,and the physical significanceof each equation is discussed.The Euler/Lagrange numerical model is used to simulate the fluid dynamiccharacteristics of the dense two-phase flow during the mould filling process in lost foam casting.The experimentsand numerical results showed that this method can be a very promising tool in the mould filling simulation of beads’movement.展开更多
文摘The available studies in the literature on physical and mathematical modeling of the argon oxygen decarburization (AOD) process of stainless steel have briefly been reviewed. The latest advances made by the author with his research group have been summarized. Water modeling was used to investigate the fluid flow and mixing characteristics in the bath of an 18 t AOD vessel, as well as the 'back attack' action of gas jets and its effects on the erosion and wear of the refractory lining, with sufficiently full kinematic similarity. The non rotating and rotating gas jets blown through two annular tuyeres, respectively of straight tube and spiral flat tube type, were employed in the experiments. The geometric similarity ratio between the model and its prototype (including the straight tube type tuyeres) was 1:3. The influences of the gas flow rate, the angle included between the two tuyeres and other operating parameters, and the suitability of the spiral tuyere as a practical application, were examined. These latest studies have clearly and successfully brought to light the fluid flow and mixing characteristics in the bath and the overall features of the back attack phenomena of gas jets during the blowing, and have offered a better understanding of the refining process. Besides, mathematical modeling for the refining process of stainless steel was carried out and a new mathematical model of the process was proposed and developed. The model performs the rate calculations of the refining and the mass and heat balances of the system. Also, the effects of the operating factors, including adding the slag materials, crop ends, and scrap, and alloy agents; the non isothermal conditions; the changes in the amounts of metal and slag during the refining; and other factors were all considered. The model was used to deal with and analyze the austenitic stainless steel making (including ultra low carbon steel) and was tested on data of 32 heats obtained in producing 304 grade steel in an 18 t AOD vessel. The changes in
基金supported by the National Natural Science Foundation of China(51609212,51606167,51779226 and 51976193)。
文摘The gas-liquid two-phase flow patterns of a centrifugal pump during the self-priming process were investigated numerically and experimentally.The Euler-Euler multiphase model and SST k-ω turbulence model were applied for simulating the self-priming process.Meanwhile,the changes of motor speed and self-priming height were considered in the simulation.The overall transient two-phase flow features and water level distributions were mapped.Results showed that the self-priming process was divided into three stages.The liquid level in inlet-pipe rose in oscillation during self-priming process.The variations of water level during self-priming process of numerical simulation and test result agreed well.The inlet-pipe(Ver)was filled at 22 s and 24 s respectively numerically and experimentally.The bubble cloud circulated in the volute during middle stage of self-priming process,and breakup into smaller bubbles by shear force and tongue,and then discharged into chamber.The bubbles in the outlet-pipe mainly included bubbly flow and slug flow at the last stage of self-priming process,which is morphologically consistent with the test results.Also,during the self-priming process,the reflux liquid was pressed by blades and fully mixed with gas;that is the way to realizing the function of self-priming.
基金supported by the National Natural Science Foundation of China(U1508217,U1702253 and 51774078)the Fundamental Research Funds for the Central Universities(N172506009 and N170908001).
文摘In order to increase the contact area and promote the mass transfer process of gas and liquid,the process of the bubble refine-ment in a metallurgical reactor with mechanical agitation was studied by physical simulation.Based on the capillary number,a prediction equation for the bubble refinement was established.The effects of the gas flow rate,the stirring speed and thestirring depth on the bubble refinement in the reactor were discussed in detail.The distribution of the bubble diameter in thereactor was obtained under different conditions.The results show that when the stirring speed reaches 300 r/min,the bubblediamcter mainly distributes in the range of 1-2 mm.A higher gas flow rate may increase the number of bubbles in the meltand promote the bubble refinement process.The mechanism of bubble refinement under mechanical agitation was analyzed.and the results indicated that the stirring speed.,the blade area and the blade inclination are the main influencing factors.
文摘Boil-Off Gas creation and usage has been a source of worry in Liquefied Natural Gas value supply chain. BOG is generated when there is temperature gradient between the environment and LNG temperature within the carrier tank, process lines or vessels. In this work, Computer Aided Design for the recovery of BOG from flare in an LNG Plant considered the dynamic nature of the BOG with minimized total energy consumption. A rigorous simulation based optimization model using HYSYS V8.8 was presented. Possible BOG scenarios were formulated in this report and considerations taken from the BOG scenarios to form the basic scope of this work. An Aspen HYSYS Software was used to develop a Process Flow Scheme (PFS) which was simulated using the BOG scenarios formulated. The BOG scenario temperatures considered were -15°C for Warm Ship analogy, -90°C for Cold Ship and -140°C for Normal Design Mode. Assumptions were also made on the feed into the developed PFS before quenching the various BOG temperatures. With HYSYS simulation at assumed constant inlet mass flow rate of 25,000 kg/s for BOG FEED, 6250 kg/s for LNG & LNG1 FEED, quenching at various BOG feed temperature -15°C, -90°C and -140°C, gave a meaningful output. The Mass flow rate recovered from Warm Ship at -15°C for Cold Product was 35,183 Kg/s and for Liquid Product 2317 Kg/s. For Cold ship at -90°C, the Cold Product recovered was 32,174 Kg/s and Liquid Product was 5326 Kg/s. Also, for -140°C, the Cold Product was 28,004 Kg/s and the Liquid Product was 9496 Kg/s. The Energy stream for the Compressor, Cooler and Pump in the Process Flow Stream (PFS) were observed in Table 5. At -15°C, the Compressor energy was 3.22E+07KJ/h, while the Pump energy was 3412KJ/h, and the Cooler gave 1.90E+07KJ/h. The results above showed that excessive BOG from Warm ship can be quenched and recovered for other end users rather than undue flaring of the gases. Extra work needs to be done to ensure minimal energy utilisation, optimal recovery and high efficiency of this developed mod
基金The National High Technology Research and Development Program of China(863Program)(2006AA04Z140)The National Natural Science Foundation of China(NSFC)(50605024)
文摘In lost foam casting(LFC)the foam pattern is the key criterion,and the filling process is crucialto ensure the high quality of the foam pattern.Filling which lacks uniformity and denseness will cause variousdefects and affect the surface quality of the casting.The influential factors of the filling process are realized in thisresearch.Optimization of the filling process,enhancement of efficiency,decrease of waste,etc.,are obtained bythe numerical simulation of the filling process using a computer.The equations governing the dense gas-solid two-phase flow are established,and the physical significanceof each equation is discussed.The Euler/Lagrange numerical model is used to simulate the fluid dynamiccharacteristics of the dense two-phase flow during the mould filling process in lost foam casting.The experimentsand numerical results showed that this method can be a very promising tool in the mould filling simulation of beads’movement.
