The Experts below are selected from a list of 3912 Experts worldwide ranked by ideXlab platform
Henrik Saxen - One of the best experts on this subject based on the ideXlab platform.
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nonlinear optimization of steel production using traditional and novel blast Furnace operation strategies
Chemical Engineering Science, 2011Co-Authors: Hannu Helle, Mikko Helle, Henrik SaxenAbstract:The high energy requirements in primary steelmaking make this industrial sector a major contributor to the global emissions of carbon dioxide. Ways to suppress the use of fossil reductants and the emissions from the processes should therefore be developed. The present work applies simulation and optimization for studying the economic feasibility of recycling blast Furnace Top gas to the combustion zones after CO2 stripping. The study comprises the unit processes in an integrated steel plant, paying special attention to the blast Furnace and the preheating of the blast or the recycled Top gas. The system is optimized with nonlinear programming with respect to some central variables under different CO2 sequestration and emission costs, which yields information about the economic feasibility of the concept. It is demonstrated that the optimal states of the plant show complex transitions, where the costs play a decisive role. It is also shown that hot gas recycling with CO2 capture and storage would dramatically reduce the harmful emissions from the process. The conditions under which Top gas recycling is economically feasible are also reported, as well as the effect of omitting oil injection in a blast Furnace with Top gas recycling.
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multiobjective optimization of Top gas recycling conditions in the blast Furnace by genetic algorithms
Materials and Manufacturing Processes, 2011Co-Authors: Tamoghna Mitra, Mikko Helle, Frank Pettersson, Henrik Saxen, Nirupam ChakrabortiAbstract:Limited natural resources and a growing concern about the potential effect of carbon dioxide emissions on the world's climate have triggered a search of ways to suppressing the emissions of CO2 in primary steelmaking. A possible future solution is to strip CO2 from the blast Furnace Top gas, feeding back the gas to the tuyere level. The work reported in this article explores states of an integrated steel plant that arise if both production costs and emissions are simultaneously minimized. This multiobjective problem is tackled by genetic algorithms using a predator–prey strategy for constructing the Pareto-frontier of nondominating solutions. Four alternative ways of treating the Top gas recycling problem are explored, and the resulting solutions are analyzed with respect to the two objectives and to the internal states of the plant they correspond to. Conclusions are drawn concerning the solutions in terms of technical feasibility and complexity.
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multi objective optimization of ironmaking in the blast Furnace with Top gas recycling
Isij International, 2010Co-Authors: Hannu Helle, Mikko Helle, Frank Pettersson, Henrik SaxenAbstract:Concern about the growing carbon dioxide content in the atmosphere has induced increasing research activities in the search for means to suppress the emissions of CO2 in primary steelmaking. Blast Furnace Top gas recycling, combined with CO2 stripping, has been proposed as a promising concept. The paper presents a numerical analysis of Top gas recycling under massive oxygen enrichment of the blast based on a simulation of the process chain from coal and ore to liquid steel. Because of the conflicting goals of reducing both production costs and emissions, the task is formulated as a multi-objective optimization problem. The optimal states of the system studied were found to vary significantly on the Pareto frontier, which demonstrates that fundamentally different states of operation may be selected to strongly reduce the emissions, still keeping the steelmaking economically feasible. The findings stress the importance of selecting a proper state of operation for achieving a cost-efficient production of steel with reduced environmental impact. The results also show how emissions can be “artificially” reduced by minimizing the arising emissions within the system boundary.
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experimental and dem study of segregation of ternary size particles in a blast Furnace Top bunker model
Chemical Engineering Science, 2010Co-Authors: Henrik SaxenAbstract:Size segregation of pellets in the Top bunker (hopper) of a blast Furnace is an important factor affecting the radial distribution of the charged burden and indirectly also the distribution of gas in the shaft and cohesive zone. This paper studies size segregation of ternary size pellets during the discharging process of a hopper model through experiments and simulations. The simulations, which are based on the discrete element method (DEM), are first validated using four experimental cases applying different bunker filling methods. The effects of various variables, such as fine mass fraction, particle friction coefficients, diameter ratio of fine to coarse and filling method (random, layered or industrial filling), as well as the interaction with wall (static and rolling friction) on the segregation are investigated. The results show that even though many factors affect the extent of segregation during the discharging process, the most important factors are the filling method, diameter ratio of fine to coarse, wall-particle static and rolling friction, interparticle rolling friction as well as mass fraction of fine particles. Reducing wall-particle rolling or static friction or the fraction of fine particles decreased the extent of size segregation.
Johnsson Filip - One of the best experts on this subject based on the ideXlab platform.
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Dynamic Modeling of the Reactive Side in Large-Scale Fluidized Bed Boilers
'American Chemical Society (ACS)', 2021Co-Authors: Martinez-castilla Guillermo, Mocholí Montañés Rubén, Pallarès David, Johnsson FilipAbstract:This work presents a dynamic model of the reactive side of large-scale fluidized bed (FB) boilers that describes the in-Furnace transient operation of both bubbling and circulating FB boilers (BFB and CFB, respectively). The model solves the dynamic mass and energy balances accounting for the bulk solids, several gas species, and the fuel phase. The model uses semi-empirical expressions to describe the fluid dynamics, fuel conversion, and heat transfer to the Furnace walls, as derived from units other than the studied ones. The model is validated against operational data from two different industrial units: an 80 MW CFB and a 130 MW BFB, both at steady-state and transient conditions. The validated model is used to analyze: (i) the performance of the reactive side of two FB boilers under off-design, steady-state conditions of operation; and (ii) the open-loop transient response when varying load or fuel moisture. The results underline the key role of heat capacity on the stabilization time. Within a given unit, the differences in heat capacity between the Top and bottom of the Furnace affect also the stabilization times, with the Furnace Top (lower heat capacity) being 1–3 times faster in the CFB unit and up to 10 times faster in the BFB unit. Due to the differences in gas velocity, the investigated boilers are found to stabilize more rapidly to input changes when running at full load than at partial load. Lastly, a variable ramping rate analysis shows that the inherent transient responses of the reactive side disappear when disturbances are introduced at (slower) rates, typical of industrial operation. Thus, the reactive side could be modeled as pseudo-static
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Dynamic Modeling of the Reactive Side in Large-Scale Fluidized Bed Boilers
'American Chemical Society (ACS)', 2021Co-Authors: Martinez-castilla Guillermo, Mocholí Montañés Rubén, Pallarès David, Johnsson FilipAbstract:This work presents a dynamic model of the reactive side of large-scale fluidized bed (FB) boilers that describes the in-Furnace transient operation of both bubbling and circulating FB boilers (BFB and CFB, respectively). The model solves the dynamic mass and energy balances accounting for the bulk solids, several gas species, and the fuel phase. The model uses semi-empirical expressions to describe the fluid dynamics, fuel conversion, and heat transfer to the Furnace walls, as derived from units other than the studied ones. The model is validated against operational data from two different industrial units: an 80 MW CFB and a 130 MW BFB, both at steady-state and transient conditions. The validated model is used to analyze: (i) the performance of the reactive side of two FB boilers under off-design, steady-state conditions of operation; and (ii) the open-loop transient response when varying load or fuel moisture. The results underline the key role of heat capacity on the stabilization time. Within a given unit, the differences in heat capacity between the Top and bottom of the Furnace affect also the stabilization times, with the Furnace Top (lower heat capacity) being 1–3 times faster in the CFB unit and up to 10 times faster in the BFB unit. Due to the differences in gas velocity, the investigated boilers are found to stabilize more rapidly to input changes when running at full load than at partial load. Lastly, a variable ramping rate analysis shows that the inherent transient responses of the reactive side disappear when disturbances are introduced at (slower) rates, typical of industrial operation. Thus, the reactive side could be modeled as pseudo-static.publishedVersio
Hannu Helle - One of the best experts on this subject based on the ideXlab platform.
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nonlinear optimization of steel production using traditional and novel blast Furnace operation strategies
Chemical Engineering Science, 2011Co-Authors: Hannu Helle, Mikko Helle, Henrik SaxenAbstract:The high energy requirements in primary steelmaking make this industrial sector a major contributor to the global emissions of carbon dioxide. Ways to suppress the use of fossil reductants and the emissions from the processes should therefore be developed. The present work applies simulation and optimization for studying the economic feasibility of recycling blast Furnace Top gas to the combustion zones after CO2 stripping. The study comprises the unit processes in an integrated steel plant, paying special attention to the blast Furnace and the preheating of the blast or the recycled Top gas. The system is optimized with nonlinear programming with respect to some central variables under different CO2 sequestration and emission costs, which yields information about the economic feasibility of the concept. It is demonstrated that the optimal states of the plant show complex transitions, where the costs play a decisive role. It is also shown that hot gas recycling with CO2 capture and storage would dramatically reduce the harmful emissions from the process. The conditions under which Top gas recycling is economically feasible are also reported, as well as the effect of omitting oil injection in a blast Furnace with Top gas recycling.
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multi objective optimization of ironmaking in the blast Furnace with Top gas recycling
Isij International, 2010Co-Authors: Hannu Helle, Mikko Helle, Frank Pettersson, Henrik SaxenAbstract:Concern about the growing carbon dioxide content in the atmosphere has induced increasing research activities in the search for means to suppress the emissions of CO2 in primary steelmaking. Blast Furnace Top gas recycling, combined with CO2 stripping, has been proposed as a promising concept. The paper presents a numerical analysis of Top gas recycling under massive oxygen enrichment of the blast based on a simulation of the process chain from coal and ore to liquid steel. Because of the conflicting goals of reducing both production costs and emissions, the task is formulated as a multi-objective optimization problem. The optimal states of the system studied were found to vary significantly on the Pareto frontier, which demonstrates that fundamentally different states of operation may be selected to strongly reduce the emissions, still keeping the steelmaking economically feasible. The findings stress the importance of selecting a proper state of operation for achieving a cost-efficient production of steel with reduced environmental impact. The results also show how emissions can be “artificially” reduced by minimizing the arising emissions within the system boundary.
Chenn Q Zhou - One of the best experts on this subject based on the ideXlab platform.
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simulation of the transfer process in the blast Furnace shaft with layered burden
Applied Thermal Engineering, 2016Co-Authors: Ping Zhou, Pengyu Shi, Chenn Q ZhouAbstract:Abstract A symmetric, two dimensional, steady state burden distribution model is proposed to simulate the flow of gases and solids in a blast Furnace. The charged material is treated as porous media with alternating coke and ore layers of different permeability. Their heat transfer processes coupled with fluid flowing and chemical reactions are predicted by Fluent . To investigate the influence of the layered burden treatment on the calculated in-Furnace condition, a mixed burden model, in which the charging materials are assumed as mixed layer of coke and ore, has also been developed with the same boundary condition except for the burden properties. The results indicate that the layered burden treatment has great influence on the calculated temperature distribution as well as the gas pressure distribution. Validation of the layered burden treatment has also been performed. The gas temperature at the Furnace Top as well as the gas pressure at the Furnace wall are in good agreement with the measured data in the operating blast Furnace. Obviously, a mathematical model that takes the layered structure into consideration is necessary to simulate the temperature and chemical reactions of materials in the blast Furnace.
Mikko Helle - One of the best experts on this subject based on the ideXlab platform.
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nonlinear optimization of steel production using traditional and novel blast Furnace operation strategies
Chemical Engineering Science, 2011Co-Authors: Hannu Helle, Mikko Helle, Henrik SaxenAbstract:The high energy requirements in primary steelmaking make this industrial sector a major contributor to the global emissions of carbon dioxide. Ways to suppress the use of fossil reductants and the emissions from the processes should therefore be developed. The present work applies simulation and optimization for studying the economic feasibility of recycling blast Furnace Top gas to the combustion zones after CO2 stripping. The study comprises the unit processes in an integrated steel plant, paying special attention to the blast Furnace and the preheating of the blast or the recycled Top gas. The system is optimized with nonlinear programming with respect to some central variables under different CO2 sequestration and emission costs, which yields information about the economic feasibility of the concept. It is demonstrated that the optimal states of the plant show complex transitions, where the costs play a decisive role. It is also shown that hot gas recycling with CO2 capture and storage would dramatically reduce the harmful emissions from the process. The conditions under which Top gas recycling is economically feasible are also reported, as well as the effect of omitting oil injection in a blast Furnace with Top gas recycling.
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multiobjective optimization of Top gas recycling conditions in the blast Furnace by genetic algorithms
Materials and Manufacturing Processes, 2011Co-Authors: Tamoghna Mitra, Mikko Helle, Frank Pettersson, Henrik Saxen, Nirupam ChakrabortiAbstract:Limited natural resources and a growing concern about the potential effect of carbon dioxide emissions on the world's climate have triggered a search of ways to suppressing the emissions of CO2 in primary steelmaking. A possible future solution is to strip CO2 from the blast Furnace Top gas, feeding back the gas to the tuyere level. The work reported in this article explores states of an integrated steel plant that arise if both production costs and emissions are simultaneously minimized. This multiobjective problem is tackled by genetic algorithms using a predator–prey strategy for constructing the Pareto-frontier of nondominating solutions. Four alternative ways of treating the Top gas recycling problem are explored, and the resulting solutions are analyzed with respect to the two objectives and to the internal states of the plant they correspond to. Conclusions are drawn concerning the solutions in terms of technical feasibility and complexity.
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multi objective optimization of ironmaking in the blast Furnace with Top gas recycling
Isij International, 2010Co-Authors: Hannu Helle, Mikko Helle, Frank Pettersson, Henrik SaxenAbstract:Concern about the growing carbon dioxide content in the atmosphere has induced increasing research activities in the search for means to suppress the emissions of CO2 in primary steelmaking. Blast Furnace Top gas recycling, combined with CO2 stripping, has been proposed as a promising concept. The paper presents a numerical analysis of Top gas recycling under massive oxygen enrichment of the blast based on a simulation of the process chain from coal and ore to liquid steel. Because of the conflicting goals of reducing both production costs and emissions, the task is formulated as a multi-objective optimization problem. The optimal states of the system studied were found to vary significantly on the Pareto frontier, which demonstrates that fundamentally different states of operation may be selected to strongly reduce the emissions, still keeping the steelmaking economically feasible. The findings stress the importance of selecting a proper state of operation for achieving a cost-efficient production of steel with reduced environmental impact. The results also show how emissions can be “artificially” reduced by minimizing the arising emissions within the system boundary.
