Gillis, PA
1990
An Evaluation of Three-Dimensional Computational Combustion and Fluid Dynamics for Industrial Furnace Geometries
Gillis, P.A. and Smith, P J.
Twenty-third Symposium (International) on Combustion, The Combustion Institute, France, 1990. Funded by Consortium and ACERC.
A three-dimensional gaseous combustion and computational fluid dynamics model is presented for simulating reacting flow in industrial furnaces and utility boilers. Data were obtained for non-reacting flow in both a tangential-fired and a wall-fired furnace. These two cases were simulated with a variety of grid resolutions to establish grid-independent solution requirements. A differencing scheme was used which assured that the numerical solution was exact for linear basis functions on an arbitrarily spaced mesh. This accuracy was demonstrated by comparing numerical results with analytic solutions of the fully coupled equation set. Several variations of the SIMPLE algorithm were incorporated into the flow model to study the importance of velocity/pressure coupling. These variations included SIMPLE, SIMPLER, SIMPLEC, SIMPLEST, and combinations of these algorithms. The robustness and speed of the SIMPLE-based methods were evaluated for a corner-fired furnace and a wall-fired furnace. The importance of temporal fluctuations due to fluid turbulence on the non-linear mixing in gaseous combustion was quantified for corner-fired furnace geometries and compared with similar studies on laboratory scale furnaces.
1989
Large-Scale Predictability of Pulverized Coal Combustion Byproducts
Smith, P.J. and Gillis, P.A.
1st International Congress on Toxic Combustion Byproduct: Formation and Control, Los Angeles, California, 1989. Funded by ACERC (National Science Foundation and Associates and Affiliates) and Brigham Young University.
Mathematical model simulations are presented for pilot plant and laboratory test furnaces to quantify the predictability and accuracy of combustion by-product formation and destruction. The roles of numerical accuracy and of closely coupled physico-chemical processes are explored. Capabilities of 3-D furnace models to describe global, site-specific flow and fine scale mesh resolution is shown to be an important consideration in simulating flow patterns in utility boiler geometries, even for relatively simple configurations. Fabricated exact numerical solutions for the coupled particle differential equation set are shown to be useful in identifying algorithmic and coding errors in these large mathematical models. The coupling between local heat transfer and other physico-chemical processes occurring in coal combustion applications is emphasized. Differences of 50-70% are shown to be obtained if particle-gas convective/conductive heat exchange and gas radiation are ignored or if turbulent fluctuations are not accounted for. This variability is shown to have a large impact than the chemical kinetic reaction rate of CO to CO2. The importance of advancing chemistry submodels and their coupling to the turbulent fluid mechanics for more accurate predictability of combustion by-products is emphasized.
Three-Dimensional Computational Fluid Dynamics Modeling in Industrial Furnace Geometries
Gillis, P.A. and Smith, P.J.
Western States Section, The Combustion Institute, Livermore, California, 1989. Funded by ACERC (National Science Foundation and Associates and Affiliates) and ACERC Consortium: Babcock & Wilcox, Combustion Engineering, Consol, Electric Power Research Institute, Empire State Electrical Energy Research Corp., Foster Wheeler, Pittsburgh Energy Technology Center, and Utah Power & Light.
In recent years, advances in computer technology have revolutionized the methods used to analyze complex flow phenomena. Many practical flows, which were previously expensive and difficult to model, are now gradually yielding their mysteries through the power of today's computers. This process is aided by the continuing development of efficient numerical algorithms and further research into the modeling of physical phenomena that are not well understood, such as turbulence. Several three-dimensional comprehensive combustion models have appeared in the literature over the past three years. Nearly all these models employ similar numerical techniques, variations of the TEACH method. A review of these codes has revealed that they use coarse grid structures and typically lack validation through comparison with experimental data. The purpose of this paper is to describe and demonstrate a three-dimensional CFD (Computational Fluid Dynamics) code that has been designed for industrial geometries. This code includes new numerical techniques, has been validated with data comparisons in several industrial furnaces, and will be used to establish the grid resolution required to obtain grid independent solutions.
The CFD model was designed to be a fundamental element in a larger comprehensive pulverized-coal combustion code for utility boilers. The model handles Cartesian and cylindrical coordinate systems and allows for irregular grid spacing in order to efficiently model the large scale disparities encountered in industrial furnaces. The model includes the option of employing different variations of the SIMPLE algorithm to couple the Navier-Stokes equations. Coupling options include the SIMPLE, SIMPLER, SIMPLEC, SIMPLEST, and various combinations of these algorithms. First-order finite differencing is performed with a combined central and revised upwind scheme that has been adapted to handle grid irregularities. The resulting finite-difference coefficient matrices are solved with a vectorized relaxed Thomas algorithm. Several turbulence models have been incorporated into the code, include the k-e turbulence model. Significant portions of the model have been vectorized to improve code performance.
The emphasis of this paper is on evaluating model performance. Experimental data has been obtained from Consolidation Coal Company for a wall-fired pilot-scale furnace with four swirled burners. Combustion Engineering has also provided a large collection of velocity data from a tangentially fired furnace. Comparisons will be made between predicted and experiment velocities for both configurations. These comparisons will be performed in different locations within each furnace and model performance will be evaluated. Additional numerical experiments were performed to determine the grid resolution needed to achieve grid independent solutions. Recommendations will be made detailing the grid resolution needed to accurately model the major types of industrial furnaces. The different coupling algorithm options employed in the model will also be evaluated for both robustness and efficiency. Additional comparisons between the TEACH method and the model's numerical techniques will be made.
1988
Three-Dimensional Fluid Dynamics Modeling in Furnace Geometries
Gillis, P.A. and Smith, P.J.
Western States Section, 1988, The Combustion Institute, Salt Lake City, UT. 12 pgs. Funded by ACERC Consortium: Babcock & Wilcox, Combustion Engineering, Consol, Electric Power Research Institute, Empire State Electrical Energy Research Corp., Foster Wheeler, Pittsburgh Energy Technology Center, Tennessee Valley Authority, and Utah Power & Light.
A three-dimensional non-reacting flow model has been developed for predicting flow inside industrial furnace configurations. The code uses the SIMPLE algorithm to couple the Navier-Stokes equations and solves the resulting matrices with a vectorized Thomas algorithm. Model predictions have been compared with experimental data in cross-fired furnace geometry. The k-e turbulence model produced significantly superior data agreement than the simpler turbulence models. The effect of inlet condition variation and grid resolution were demonstrated. It was also shown that fine grid spacing is needed to resolve localized large-scale vortex structure.
Gillis, PA
1990
An Evaluation of Three-Dimensional Computational Combustion and Fluid Dynamics for Industrial Furnace Geometries
Gillis, P.A. and Smith, P J.
Twenty-third Symposium (International) on Combustion, The Combustion Institute, France, 1990. Funded by Consortium and ACERC.
A three-dimensional gaseous combustion and computational fluid dynamics model is presented for simulating reacting flow in industrial furnaces and utility boilers. Data were obtained for non-reacting flow in both a tangential-fired and a wall-fired furnace. These two cases were simulated with a variety of grid resolutions to establish grid-independent solution requirements. A differencing scheme was used which assured that the numerical solution was exact for linear basis functions on an arbitrarily spaced mesh. This accuracy was demonstrated by comparing numerical results with analytic solutions of the fully coupled equation set. Several variations of the SIMPLE algorithm were incorporated into the flow model to study the importance of velocity/pressure coupling. These variations included SIMPLE, SIMPLER, SIMPLEC, SIMPLEST, and combinations of these algorithms. The robustness and speed of the SIMPLE-based methods were evaluated for a corner-fired furnace and a wall-fired furnace. The importance of temporal fluctuations due to fluid turbulence on the non-linear mixing in gaseous combustion was quantified for corner-fired furnace geometries and compared with similar studies on laboratory scale furnaces.
1989
Large-Scale Predictability of Pulverized Coal Combustion Byproducts
Smith, P.J. and Gillis, P.A.
1st International Congress on Toxic Combustion Byproduct: Formation and Control, Los Angeles, California, 1989. Funded by ACERC (National Science Foundation and Associates and Affiliates) and Brigham Young University.
Mathematical model simulations are presented for pilot plant and laboratory test furnaces to quantify the predictability and accuracy of combustion by-product formation and destruction. The roles of numerical accuracy and of closely coupled physico-chemical processes are explored. Capabilities of 3-D furnace models to describe global, site-specific flow and fine scale mesh resolution is shown to be an important consideration in simulating flow patterns in utility boiler geometries, even for relatively simple configurations. Fabricated exact numerical solutions for the coupled particle differential equation set are shown to be useful in identifying algorithmic and coding errors in these large mathematical models. The coupling between local heat transfer and other physico-chemical processes occurring in coal combustion applications is emphasized. Differences of 50-70% are shown to be obtained if particle-gas convective/conductive heat exchange and gas radiation are ignored or if turbulent fluctuations are not accounted for. This variability is shown to have a large impact than the chemical kinetic reaction rate of CO to CO2. The importance of advancing chemistry submodels and their coupling to the turbulent fluid mechanics for more accurate predictability of combustion by-products is emphasized.
Three-Dimensional Computational Fluid Dynamics Modeling in Industrial Furnace Geometries
Gillis, P.A. and Smith, P.J.
Western States Section, The Combustion Institute, Livermore, California, 1989. Funded by ACERC (National Science Foundation and Associates and Affiliates) and ACERC Consortium: Babcock & Wilcox, Combustion Engineering, Consol, Electric Power Research Institute, Empire State Electrical Energy Research Corp., Foster Wheeler, Pittsburgh Energy Technology Center, and Utah Power & Light.
In recent years, advances in computer technology have revolutionized the methods used to analyze complex flow phenomena. Many practical flows, which were previously expensive and difficult to model, are now gradually yielding their mysteries through the power of today's computers. This process is aided by the continuing development of efficient numerical algorithms and further research into the modeling of physical phenomena that are not well understood, such as turbulence. Several three-dimensional comprehensive combustion models have appeared in the literature over the past three years. Nearly all these models employ similar numerical techniques, variations of the TEACH method. A review of these codes has revealed that they use coarse grid structures and typically lack validation through comparison with experimental data. The purpose of this paper is to describe and demonstrate a three-dimensional CFD (Computational Fluid Dynamics) code that has been designed for industrial geometries. This code includes new numerical techniques, has been validated with data comparisons in several industrial furnaces, and will be used to establish the grid resolution required to obtain grid independent solutions.
The CFD model was designed to be a fundamental element in a larger comprehensive pulverized-coal combustion code for utility boilers. The model handles Cartesian and cylindrical coordinate systems and allows for irregular grid spacing in order to efficiently model the large scale disparities encountered in industrial furnaces. The model includes the option of employing different variations of the SIMPLE algorithm to couple the Navier-Stokes equations. Coupling options include the SIMPLE, SIMPLER, SIMPLEC, SIMPLEST, and various combinations of these algorithms. First-order finite differencing is performed with a combined central and revised upwind scheme that has been adapted to handle grid irregularities. The resulting finite-difference coefficient matrices are solved with a vectorized relaxed Thomas algorithm. Several turbulence models have been incorporated into the code, include the k-e turbulence model. Significant portions of the model have been vectorized to improve code performance.
The emphasis of this paper is on evaluating model performance. Experimental data has been obtained from Consolidation Coal Company for a wall-fired pilot-scale furnace with four swirled burners. Combustion Engineering has also provided a large collection of velocity data from a tangentially fired furnace. Comparisons will be made between predicted and experiment velocities for both configurations. These comparisons will be performed in different locations within each furnace and model performance will be evaluated. Additional numerical experiments were performed to determine the grid resolution needed to achieve grid independent solutions. Recommendations will be made detailing the grid resolution needed to accurately model the major types of industrial furnaces. The different coupling algorithm options employed in the model will also be evaluated for both robustness and efficiency. Additional comparisons between the TEACH method and the model's numerical techniques will be made.
1988
Three-Dimensional Fluid Dynamics Modeling in Furnace Geometries
Gillis, P.A. and Smith, P.J.
Western States Section, 1988, The Combustion Institute, Salt Lake City, UT. 12 pgs. Funded by ACERC Consortium: Babcock & Wilcox, Combustion Engineering, Consol, Electric Power Research Institute, Empire State Electrical Energy Research Corp., Foster Wheeler, Pittsburgh Energy Technology Center, Tennessee Valley Authority, and Utah Power & Light.
A three-dimensional non-reacting flow model has been developed for predicting flow inside industrial furnace configurations. The code uses the SIMPLE algorithm to couple the Navier-Stokes equations and solves the resulting matrices with a vectorized Thomas algorithm. Model predictions have been compared with experimental data in cross-fired furnace geometry. The k-e turbulence model produced significantly superior data agreement than the simpler turbulence models. The effect of inlet condition variation and grid resolution were demonstrated. It was also shown that fine grid spacing is needed to resolve localized large-scale vortex structure.