Numerical Simulation of Combustion in the Ironmaking Blast Furnace Raceway

As almost all conversion of raw iron ore to pig iron at the start of the ironmaking process currently takes place in a blast furnace, these furnaces remain a critical component in the iron and steelmaking industry. Enhancements in the efficiency of blast furnace operation have a significant effect on industrial energy consumption, as the process represents nearly 70% of the total energy consumption of the iron and steelmaking process. Over the past several decades, auxiliary fuel injection has been adopted as a method of reducing the total amount of coke necessary for furnace operation. Coke making is both energy intensive and environmentally unfriendly, and as such, any reduction in coke usage by the blast furnace is positive for the iron and steelmaking industry. However, the intricate variations in blast furnace raceway conditions and injected fuel combustion characteristics due to the method and conditions at which auxiliary fuels are injected into the furnace are still not fully understood. The goal of this research is to utilize computational fluid dynamics (CFD) modeling to provide a deeper level of understanding of the complex relationships between blast furnace injection system designs and operating conditions on the combustion processes and phenomena within the raceway. In this vein, a multi-stage 3-D CFD model has been developed and applied to simulate combustion phenomena within several industrial blast furnace raceway regions. The three primary components of focus in this research are the tuyere and injection apparatus, raceway formation, and raceway combustion. A comprehensive CFD methodology for simulation operating conditions and combustion within the blast furnace raceway has been developed. This methodology utilizes CFD modeling to simulate conditions within the raceway region. A revised raceway formation model has been developed to better correspond to industrial observations, and new methodology for analysis and presentation of simulation results from these models have been developed. The models have been validated against industrial observation and measurements from three currently operating industrial blast furnaces. The models have also been utilized to examine varied operating conditions in the aforementioned furnaces. Two new methods of exploring raceway gas temperature using simulation modeling were developed in this research, namely a Topographical Flame Temperature (TOFT) and a Raceway Adiabatic Flame Temperature (RAFT) analogue. These methods allow for both better validation of computational modeling results against industrial observation and measurement, as well as providing a new path to explore raceway gas temperature distribution under unique conditions, including extremely high natural gas injection rates, which may present potential for significantly improving the economic and operational efficiency of the furnace. The analyses of industry blast furnaces provide significant insight into the effects of injection conditions and apparatus designs upon combustion characteristics and reaction phenomena within the raceway. Previously unexplored novel fuel injection techniques were explored within this research, and simulations have indicated that injected fuel burnout rates could be improved by as much as 23% in specific scenarios and production could be increased by roughly 2.5%. While a switch to these injection techniques may pose some difficulties in practice, industrial project partners have already begun trials for implementation on a full-scale furnace. Finally, this modeling revealed significant potential benefits to blast furnace operation through modification of natural gas and pulverized coal injection locations, pulverized coal carrier gas type, injection lance tip design, and other parameters. While these exact parameters cannot be implemented identically across all plant furnaces, they provide a baseline of fundamental understanding from which furnace operators and engineers can draw in their ongoing attempts to optimize combustion efficiency and reduce operational expenditures

Numerical Simulation of Combustion in the Ironmaking Blast Furnace Raceway

As almost all conversion of raw iron ore to pig iron at the start of the ironmaking process currently takes place in a blast furnace, these furnaces remain a critical component in the iron and steelmaking industry. Enhancements in the efficiency of blast furnace operation have a significant effect on industrial energy consumption, as the process represents nearly 70% of the total energy consumption of the iron and steelmaking process. Over the past several decades, auxiliary fuel injection has been adopted as a method of reducing the total amount of coke necessary for furnace operation. Coke making is both energy intensive and environmentally unfriendly, and as such, any reduction in coke usage by the blast furnace is positive for the iron and steelmaking industry. However, the intricate variations in blast furnace raceway conditions and injected fuel combustion characteristics due to the method and conditions at which auxiliary fuels are injected into the furnace are still not fully understood. The goal of this research is to utilize computational fluid dynamics (CFD) modeling to provide a deeper level of understanding of the complex relationships between blast furnace injection system designs and operating conditions on the combustion processes and phenomena within the raceway. In this vein, a multi-stage 3-D CFD model has been developed and applied to simulate combustion phenomena within several industrial blast furnace raceway regions. The three primary components of focus in this research are the tuyere and injection apparatus, raceway formation, and raceway combustion. A comprehensive CFD methodology for simulation operating conditions and combustion within the blast furnace raceway has been developed. This methodology utilizes CFD modeling to simulate conditions within the raceway region. A revised raceway formation model has been developed to better correspond to industrial observations, and new methodology for analysis and presentation of simulation results from these models have been developed. The models have been validated against industrial observation and measurements from three currently operating industrial blast furnaces. The models have also been utilized to examine varied operating conditions in the aforementioned furnaces. Two new methods of exploring raceway gas temperature using simulation modeling were developed in this research, namely a Topographical Flame Temperature (TOFT) and a Raceway Adiabatic Flame Temperature (RAFT) analogue. These methods allow for both better validation of computational modeling results against industrial observation and measurement, as well as providing a new path to explore raceway gas temperature distribution under unique conditions, including extremely high natural gas injection rates, which may present potential for significantly improving the economic and operational efficiency of the furnace. The analyses of industry blast furnaces provide significant insight into the effects of injection conditions and apparatus designs upon combustion characteristics and reaction phenomena within the raceway. Previously unexplored novel fuel injection techniques were explored within this research, and simulations have indicated that injected fuel burnout rates could be improved by as much as 23% in specific scenarios and production could be increased by roughly 2.5%. While a switch to these injection techniques may pose some difficulties in practice, industrial project partners have already begun trials for implementation on a full-scale furnace. Finally, this modeling revealed significant potential benefits to blast furnace operation through modification of natural gas and pulverized coal injection locations, pulverized coal carrier gas type, injection lance tip design, and other parameters. While these exact parameters cannot be implemented identically across all plant furnaces, they provide a baseline of fundamental understanding from which furnace operators and engineers can draw in their ongoing attempts to optimize combustion efficiency and reduce operational expenditures

A computational examination of utility scale wind turbine wakes to provide improved siting and efficiency

The purpose of this study is to determine the effects of wakes and vortices generated by upstream turbines on the performance of turbine groupings. This is done by performing numerical simulations of utility scale wind turbines in various arrangements. Optimization of wind farms is an ongoing focus of research in the field of wind energy. Of great import to this field of research is determining new methods to minimize power losses due to wake interaction between upstream and downstream turbines. As a turbine extracts kinetic energy from the wind, the air passing through that turbine is slowed. This slowed air is then experienced by turbines downstream, resulting in lower performance for the wind farm. This study proposes two arrangements of turbine groups that could provide increased power generation by increasing air speed at downstream turbines. By using Computational Fluid Dynamics, simulations of a base case for each arrangement, as well as variations on the distance between turbines, are completed with minimal cost compared to the construction and operation of either wind tunnel models or a large scale experimental test. Finally, an optimum arrangement for application to utility scale wind farms is established by comparing data obtained from each simulation geometry

Impact of Injection Rate on Flow Mixing during the Refining Stage in an Electric Arc Furnace

During the refining stage of electric arc furnace (EAF) operation, molten steel is stirred to facilitate gas/steel/slag reactions and the removal of impurities, which determines the quality of the steel. The stirring process can be driven by the injection of oxygen, which is carried out by burners operating in lance mode. In this study, a computational fluid dynamics (CFD) platform is used to simulate the liquid steel flow dynamics in an industrial-scale scrap-based EAF. The CFD platform simulates the three-dimensional, transient, non-reacting flow of the liquid steel bath stirred by oxygen injection to analyze the mixing process. In particular, the CFD study simulates liquid steel flow in an industrial-scale EAF with three asymmetric coherent jets, which impacts the liquid steel mixing under different injection conditions. The liquid steel mixing is quantified by defining two variables: the mixing time and the standard deviation of the flow velocity. The results indicate that the mixing rate of the bath is determined by flow dynamics near the injection cavities and that the formation of very low-velocity regions or ‘dead zones’ at the center of the furnace and the balcony regions prevents flow mixing. This study includes a baseline case, where oxygen is injected at 1000 SCFM in all the burners. Two sets of cases are also included: The first set considers cases where oxygen is injected at a reduced and at an increased uniform flow rate, 750 and 1250 SCFM, respectively. The second set considers cases with non-uniform injection rates in each burner, which keep the same total flow rate of the baseline case, 3000 SCFM. Comparison between the two sets of simulations against the baseline case shows that by increasing the uniform flow rate from 1000 to 1250 SCFM, the mixing time is reduced by 10.9%. Moreover, all the non-uniform injection cases reduce the mixing time obtained in the baseline case. However, the reduction in mixing times in these cases is accompanied by an increase in the standard deviations of the flow field. Among the non-uniform injection cases, the largest reduction in mixing time compared to the baseline case is 10.2%, which is obtained when the largest flow rates are assigned to coherent jets located opposite each other across the furnace