Implementation of a Demoisturization and Devolatilization Model in Multi-Phase Simulation of a Hybrid Entrained-Flow and Fluidized Bed Mild Gasifier

Affiliation(s)

Energy Conversion & Conservation Center, University of New Orleans, New Orleans, USA.

Energy Conversion & Conservation Center, University of New Orleans, New Orleans, USA.

ABSTRACT

A mild gasification process has been implemented to provide an alternative form of clean coal technology called the Integrated Mild Gasification Combined Cycle (IMGCC), which can be utilized to build a new, highly efficient, and compact power plant or to retrofit an existing coal-fired power plant in order to achieve lower emissions and significantly improved thermal efficiency. The core technology of the mild gasification power plant lies on the design of a compact and effective mild gasifier that can produce synthesis gases with high energy volatiles through a hybrid system: utilizing the features of both entrained-flow and fluidized bed gasifiers. To aid in the design of the mild gasifier, a computational model has been implemented to investigate the thermal-flow and gasification process inside this mild gasifier using the commercial CFD (Computational Fluid Dynamics) solver ANSYS/FLUENT. The Eulerian-Eulerian method is employed to model both the primary phase (air) and the secondary phase (coal particles). However, the Eulerian-Eulerian model used in the software does not facilitate any built-in devolatilization model. The objective of this study is therefore to implement a devolatilization model (along with demoisturization) and incorporate it into the existing code. The Navier-Stokes equations and seven species transport equations are solved with three heterogeneous (gas-solid) and two homogeneous (gas-gas) global gasification reactions. Implementation of the complete model starts from adding demoisturization first, then devolatilization, and then adding one chemical equation at a time until finally all reactions are included in the multiphase flow. The result shows that the demoisturization and devolatilization models are successfully incorporated and a large amount of volatiles are preserved as high-energy fuels in the syngas stream without being further cracked or reacted into lighter gases. The overall results are encouraging but require future experimental data for verification.

A mild gasification process has been implemented to provide an alternative form of clean coal technology called the Integrated Mild Gasification Combined Cycle (IMGCC), which can be utilized to build a new, highly efficient, and compact power plant or to retrofit an existing coal-fired power plant in order to achieve lower emissions and significantly improved thermal efficiency. The core technology of the mild gasification power plant lies on the design of a compact and effective mild gasifier that can produce synthesis gases with high energy volatiles through a hybrid system: utilizing the features of both entrained-flow and fluidized bed gasifiers. To aid in the design of the mild gasifier, a computational model has been implemented to investigate the thermal-flow and gasification process inside this mild gasifier using the commercial CFD (Computational Fluid Dynamics) solver ANSYS/FLUENT. The Eulerian-Eulerian method is employed to model both the primary phase (air) and the secondary phase (coal particles). However, the Eulerian-Eulerian model used in the software does not facilitate any built-in devolatilization model. The objective of this study is therefore to implement a devolatilization model (along with demoisturization) and incorporate it into the existing code. The Navier-Stokes equations and seven species transport equations are solved with three heterogeneous (gas-solid) and two homogeneous (gas-gas) global gasification reactions. Implementation of the complete model starts from adding demoisturization first, then devolatilization, and then adding one chemical equation at a time until finally all reactions are included in the multiphase flow. The result shows that the demoisturization and devolatilization models are successfully incorporated and a large amount of volatiles are preserved as high-energy fuels in the syngas stream without being further cracked or reacted into lighter gases. The overall results are encouraging but require future experimental data for verification.

Cite this paper

J. Khan and T. Wang, "Implementation of a Demoisturization and Devolatilization Model in Multi-Phase Simulation of a Hybrid Entrained-Flow and Fluidized Bed Mild Gasifier,"*International Journal of Clean Coal and Energy*, Vol. 2 No. 3, 2013, pp. 35-53. doi: 10.4236/ijcce.2013.23005.

J. Khan and T. Wang, "Implementation of a Demoisturization and Devolatilization Model in Multi-Phase Simulation of a Hybrid Entrained-Flow and Fluidized Bed Mild Gasifier,"

References

[1] D. B. Anthony, J. B. Howard, H. C. Hottel and H. P. Meissner, “Rapid Devolatilization of Pulverized Coal,” 15th International Symposium on Combustion, Tokyo, 25-31 August 1975, pp. 1303-1317.

[2] S. Ergun, “Fluid Flow through Packed Columns,” Journal of Chemical Engineering Progress, Vol. 48, No. 2, 1952, pp. 89-94.

[3] M. Syamlal and D. Gidaspow, “Hydrodynamic of Fluidization: Prediction of Wall to Bed Heat Transfer Coefficients,” AIChE Journal, Vol. 31, No. 1, 1985, pp. 127-135. doi:10.1002/aic.690310115

[4] M. Syamlal, “The Particle-Particle Drag Term in a Multi-Particle Model of Fluidization,” Topical Report, Work Performed under Contract No.: DE-AC21-85MC21353, 1987.

[5] W. C. Yang and D. L. Keairns, “Rate of Particle Separation in a Gas Fluidized Bed,” Journal of Industrial Engineering Chemical Fundamentals, Vol. 21, No. 3, 1982, pp. 228-235. doi:10.1021/i100007a007

[6] M. Syamlal and T. J. O’Brien, “Computer Simulation of Bubbles in a Fluidized Bed,” AlChE Symposium Series, Vol. 85, No. 270, 1989, pp. 22-31.

[7] D. J. Gunn, “Transfer of Heat or Mass to Particles in Fixed and Fluidized Beds,” Journal of Heat Mass Transfer, Vol. 21, No. 4, 1978, pp. 467-476. doi:10.1016/0017-9310(78)90080-7

[8] C. K. K. Lun, S. B. Savage, D. J. Jeffrey and N. Chepurniy, “Kinetic Theories for Granular Flow: Inelastic Particles in Couette Flow and Slightly Inelastic Particles in a General Flowfield,” Journal of Fluid Mechanics, Vol. 140, 1984, pp. 223-2565. doi:10.1017/S0022112084000586

[9] S. B. Savage and D. J. Jeffrey, “The Stress in a Granular Flow at High Shear Rates,” Journal of Fluid Mechanics, Vol. 110, 1981, pp. 255-272. doi:10.1017/S0022112081000736

[10] J. A. M. Kuipers, W. Prins and W. P. M. Van Swaaij, “Numerical Calculation of Wall-to-Bed Heat-Transfer Coefficients in Gas-Fluidized Beds,” AlChE Journal, Vol. 38, No. 7, 1992, pp. 1079-1091. doi:10.1002/aic.690380711

[11] H. Enwald and A. E. Almstedt, “Fluid Dynamics of a Pressurized Fluidized Bed: Comparison between Numerical Solutions from Two-Fluid Models and Experimental Results,” Journal of Chemical Engineering Science, Vol. 54, No. 3, 1999, pp. 329-342. doi:10.1016/S0009-2509(98)00187-0

[12] V. Jiradilok, D. Gidaspow, S. Damronglerd, W. J. Koves and R. Mostofi, “Kinetic Theory Based CFD Simulation of Turbulent Fluidization of FCC Particles in a Riser,” Chemical Engineering Science, Vol. 61, No. 17, 2006, pp. 5544-5559. doi:10.1016/j.ces.2006.04.006

[13] R. Panneerselvam, S. Savithri and G. D. Surneder, “CFD Based Investigation on Hydrodynamics and Energy Dissipation Due to Solid Motion in Liquid Fluidized Bed,” Journal of Chemical Engineering, Vol. 132, No. 1-3, 2007, pp. 159-171. doi:10.1016/j.cej.2007.01.042

[14] N. Reuge, L. Cadoret, C. C. Saudejaud, S. Pannala, M. Syamlal and B. Caussat, “Multifluid Eulerian Modeling of Dense Gas-Solid Fluidized Bed Hydrodynamics: Influence of the Dissipation Parameters,” Journal of Chemical Engineering Science, Vol. 63, No. 22, 2008, pp. 5540-5551. doi:10.1016/j.ces.2008.07.028

[15] Department of Energy, National Energy Technology Laboratory, “Multiphase Flow with Interphase eXchange,” 2012. https://mfix.netl.doe.gov/

[16] F. Chejne and J. P. Hernandez, “Modeling and Simulation of Coal Gasification process in Fluidized Bed,” Fuel, Vol. 81, No. 13, 2002, pp. 1687-1702. doi:10.1016/S0016-2361(02)00036-4

[17] L. Yu, J. Lu, X. Zhang and S. Zhang, “Numerical Simulation of the Bubbling Fluidized Bed Coal Gasification by the Kinetic Theory of Granular Flow (KTGF),” Fuel, Vol. 86, No. 5-6, 2007, pp. 722-734. doi:10.1016/j.fuel.2006.09.008

[18] X. Wang, B. Jin and W. Zhong, “Three-Dimensional Simulation of Fluidized Bed Coal Gasification,” Chemical Engineering and Processing: Process Intensification, Vol. 48, No. 2, 2009, pp. 695-705. doi:10.1016/j.cep.2008.08.006

[19] A. Suo-Anttila, J. D. Smith and L. D. Berg, “Development and Application of an LES Based CFD Code to Simulate Coal and Biomass Combustion in General Reactor Configurations,” 9th European Conference on Industrial Furnaces and Boilers, Estoril, 26-29 April 2011.

[20] R. Gupta, B. Turk and M. Lesemann, “RTI/Eastman Warm Syngas Clean-Up Technology: Integration with Carbon Capture,” Presented at the 2009 Gasification Technologies Conference, 2009.

[21] R. Gupta, A. Jamal, B. Turk and M. Lesemann, “Scaled and Commercialization of Warm Syngas Cleanup Technology with Carbon Capture and Storage,” Presented at the 2010 Gasification Technologies Conference, Washington DC, 2010.

[22] A. Wormser, “Repowering Steam Plants with Mild Gasification IGCCs,” Proceedings of the 24th International Pittsburgh Coal Conference, Johannesburg, 10-14 September 2007.

[23] A. Wormser, “Converting PC to Very-High-Efficiency IGCC: The MaGICTM of Mild Gasification,” Modern Power System, November 2008, pp. 21-26.

[24] A. K. M. Mazumder and T. Wang, “Development of a Simulation Model for Fluidized Bed Mild Gasifier,” ECCC Report 2010-05, Energy Conversion and Conservation Center, University of New Orleans, November 2010.

[25] A. K. M. Mazumder, T. Wang and J. R. Khan, “Design and Simulation of a Mild Gasifier, Part 1—Development of a Multiphase Computational Model,” ASME Paper IMECE 2011-64473, Proceedings of the ASME International Mechanical Engineering Congress & Exposition, Denver, 11-17 November 2011.

[26] A. K. M. Mazumder, T. Wang and J. R. Khan, “Design and Simulation of a Mild Gasifier, Part 2—Case Study and Analysis,” ASME Paper IMECE 2011-64485, Proceedings of the ASME International Mechanical Engineering Congress & Exposition, Denver, 11-17 November 2011.

[27] H. Kobayashi, J. B. Howard and A. F. Sarofim, “Coal Devolatilization at High Temperatures,” 16th Symposium (International) on Combustion, The Combustion Institute, 1976.

[28] S. Badzioch and P. G. W. Hawsley, “Kinetics of Thermal Decomposition of Pulverized Coal Particles,” Industrial & Engineering Chemistry Process Design and Development, Vol. 9, No. 4, 1970, pp. 521-530. doi:10.1021/i260036a005

[29] M. M. Baum and P. J. Street, “Predicting the Combustion Behavior of Coal Particles,” Combustion Science and Technology, Vol. 3, 1971, pp. 231-243.

[30] K. K. Pillai, “The Influence of Coal Type on Devolatilization and Combustion in Fluidized Beds,” Journal of the Energy Institute, Vol. 54, 1981, pp. 142-150.

[31] T. H. Fletcher, A. R. Kerstein, R. J. Pugmire and D. M. Grant, “Chemical Percolation Model for Devolatilization: 2. Temperature and Heating Rate Effects on Product Yields,” Energy Fuels, Vol. 4, No. 1, 1990, pp. 54-60. doi:10.1021/ef00019a010

[32] T. H. Fletcher and A. R. Kerstein, “Chemical Percolation Model for Devolatilization: 3. Direct Use of CNMR Date to Predict Effects of Coal Type,” Energy Fuels, Vol. 6, No. 4, 1992, pp. 414-431. doi:10.1021/ef00034a011

[33] D. M. Grant, R. J. Pugmire, T. H. Fletcher and A. R. Kerstein, “Chemical Percolation of Coal Devolatilization Using Percolation Lattice Statistics,” Energy Fuels, Vol. 3, No. 2, 1989, pp. 175-186. doi:10.1021/ef00014a011

[34] A. Silaen and T. Wang, “Effect of Turbulence and Devolatilization Models on Coal Gasification Simulation in an Entrained-Flow Gasifier,” International Journal of Heat and Mass Transfer, Vol. 53, No. 9-10, 2010, pp. 2074-2091. doi:10.1016/j.ijheatmasstransfer.2009.12.047

[35] I. W. Smith, “The Combustion Rates of Coal Chars: A Review,” 19th International Symposium on Combustion, Vol. 19, No. 1, 1982, pp. 1045-1065.

[36] S. V. Patankar, “Numerical Heat Transfer and Fluid Flow,” McGraw Hill, New York, 1980.

[1] D. B. Anthony, J. B. Howard, H. C. Hottel and H. P. Meissner, “Rapid Devolatilization of Pulverized Coal,” 15th International Symposium on Combustion, Tokyo, 25-31 August 1975, pp. 1303-1317.

[2] S. Ergun, “Fluid Flow through Packed Columns,” Journal of Chemical Engineering Progress, Vol. 48, No. 2, 1952, pp. 89-94.

[3] M. Syamlal and D. Gidaspow, “Hydrodynamic of Fluidization: Prediction of Wall to Bed Heat Transfer Coefficients,” AIChE Journal, Vol. 31, No. 1, 1985, pp. 127-135. doi:10.1002/aic.690310115

[4] M. Syamlal, “The Particle-Particle Drag Term in a Multi-Particle Model of Fluidization,” Topical Report, Work Performed under Contract No.: DE-AC21-85MC21353, 1987.

[5] W. C. Yang and D. L. Keairns, “Rate of Particle Separation in a Gas Fluidized Bed,” Journal of Industrial Engineering Chemical Fundamentals, Vol. 21, No. 3, 1982, pp. 228-235. doi:10.1021/i100007a007

[6] M. Syamlal and T. J. O’Brien, “Computer Simulation of Bubbles in a Fluidized Bed,” AlChE Symposium Series, Vol. 85, No. 270, 1989, pp. 22-31.

[7] D. J. Gunn, “Transfer of Heat or Mass to Particles in Fixed and Fluidized Beds,” Journal of Heat Mass Transfer, Vol. 21, No. 4, 1978, pp. 467-476. doi:10.1016/0017-9310(78)90080-7

[8] C. K. K. Lun, S. B. Savage, D. J. Jeffrey and N. Chepurniy, “Kinetic Theories for Granular Flow: Inelastic Particles in Couette Flow and Slightly Inelastic Particles in a General Flowfield,” Journal of Fluid Mechanics, Vol. 140, 1984, pp. 223-2565. doi:10.1017/S0022112084000586

[9] S. B. Savage and D. J. Jeffrey, “The Stress in a Granular Flow at High Shear Rates,” Journal of Fluid Mechanics, Vol. 110, 1981, pp. 255-272. doi:10.1017/S0022112081000736

[10] J. A. M. Kuipers, W. Prins and W. P. M. Van Swaaij, “Numerical Calculation of Wall-to-Bed Heat-Transfer Coefficients in Gas-Fluidized Beds,” AlChE Journal, Vol. 38, No. 7, 1992, pp. 1079-1091. doi:10.1002/aic.690380711

[11] H. Enwald and A. E. Almstedt, “Fluid Dynamics of a Pressurized Fluidized Bed: Comparison between Numerical Solutions from Two-Fluid Models and Experimental Results,” Journal of Chemical Engineering Science, Vol. 54, No. 3, 1999, pp. 329-342. doi:10.1016/S0009-2509(98)00187-0

[12] V. Jiradilok, D. Gidaspow, S. Damronglerd, W. J. Koves and R. Mostofi, “Kinetic Theory Based CFD Simulation of Turbulent Fluidization of FCC Particles in a Riser,” Chemical Engineering Science, Vol. 61, No. 17, 2006, pp. 5544-5559. doi:10.1016/j.ces.2006.04.006

[13] R. Panneerselvam, S. Savithri and G. D. Surneder, “CFD Based Investigation on Hydrodynamics and Energy Dissipation Due to Solid Motion in Liquid Fluidized Bed,” Journal of Chemical Engineering, Vol. 132, No. 1-3, 2007, pp. 159-171. doi:10.1016/j.cej.2007.01.042

[14] N. Reuge, L. Cadoret, C. C. Saudejaud, S. Pannala, M. Syamlal and B. Caussat, “Multifluid Eulerian Modeling of Dense Gas-Solid Fluidized Bed Hydrodynamics: Influence of the Dissipation Parameters,” Journal of Chemical Engineering Science, Vol. 63, No. 22, 2008, pp. 5540-5551. doi:10.1016/j.ces.2008.07.028

[15] Department of Energy, National Energy Technology Laboratory, “Multiphase Flow with Interphase eXchange,” 2012. https://mfix.netl.doe.gov/

[16] F. Chejne and J. P. Hernandez, “Modeling and Simulation of Coal Gasification process in Fluidized Bed,” Fuel, Vol. 81, No. 13, 2002, pp. 1687-1702. doi:10.1016/S0016-2361(02)00036-4

[17] L. Yu, J. Lu, X. Zhang and S. Zhang, “Numerical Simulation of the Bubbling Fluidized Bed Coal Gasification by the Kinetic Theory of Granular Flow (KTGF),” Fuel, Vol. 86, No. 5-6, 2007, pp. 722-734. doi:10.1016/j.fuel.2006.09.008

[18] X. Wang, B. Jin and W. Zhong, “Three-Dimensional Simulation of Fluidized Bed Coal Gasification,” Chemical Engineering and Processing: Process Intensification, Vol. 48, No. 2, 2009, pp. 695-705. doi:10.1016/j.cep.2008.08.006

[19] A. Suo-Anttila, J. D. Smith and L. D. Berg, “Development and Application of an LES Based CFD Code to Simulate Coal and Biomass Combustion in General Reactor Configurations,” 9th European Conference on Industrial Furnaces and Boilers, Estoril, 26-29 April 2011.

[20] R. Gupta, B. Turk and M. Lesemann, “RTI/Eastman Warm Syngas Clean-Up Technology: Integration with Carbon Capture,” Presented at the 2009 Gasification Technologies Conference, 2009.

[21] R. Gupta, A. Jamal, B. Turk and M. Lesemann, “Scaled and Commercialization of Warm Syngas Cleanup Technology with Carbon Capture and Storage,” Presented at the 2010 Gasification Technologies Conference, Washington DC, 2010.

[22] A. Wormser, “Repowering Steam Plants with Mild Gasification IGCCs,” Proceedings of the 24th International Pittsburgh Coal Conference, Johannesburg, 10-14 September 2007.

[23] A. Wormser, “Converting PC to Very-High-Efficiency IGCC: The MaGICTM of Mild Gasification,” Modern Power System, November 2008, pp. 21-26.

[24] A. K. M. Mazumder and T. Wang, “Development of a Simulation Model for Fluidized Bed Mild Gasifier,” ECCC Report 2010-05, Energy Conversion and Conservation Center, University of New Orleans, November 2010.

[25] A. K. M. Mazumder, T. Wang and J. R. Khan, “Design and Simulation of a Mild Gasifier, Part 1—Development of a Multiphase Computational Model,” ASME Paper IMECE 2011-64473, Proceedings of the ASME International Mechanical Engineering Congress & Exposition, Denver, 11-17 November 2011.

[26] A. K. M. Mazumder, T. Wang and J. R. Khan, “Design and Simulation of a Mild Gasifier, Part 2—Case Study and Analysis,” ASME Paper IMECE 2011-64485, Proceedings of the ASME International Mechanical Engineering Congress & Exposition, Denver, 11-17 November 2011.

[27] H. Kobayashi, J. B. Howard and A. F. Sarofim, “Coal Devolatilization at High Temperatures,” 16th Symposium (International) on Combustion, The Combustion Institute, 1976.

[28] S. Badzioch and P. G. W. Hawsley, “Kinetics of Thermal Decomposition of Pulverized Coal Particles,” Industrial & Engineering Chemistry Process Design and Development, Vol. 9, No. 4, 1970, pp. 521-530. doi:10.1021/i260036a005

[29] M. M. Baum and P. J. Street, “Predicting the Combustion Behavior of Coal Particles,” Combustion Science and Technology, Vol. 3, 1971, pp. 231-243.

[30] K. K. Pillai, “The Influence of Coal Type on Devolatilization and Combustion in Fluidized Beds,” Journal of the Energy Institute, Vol. 54, 1981, pp. 142-150.

[31] T. H. Fletcher, A. R. Kerstein, R. J. Pugmire and D. M. Grant, “Chemical Percolation Model for Devolatilization: 2. Temperature and Heating Rate Effects on Product Yields,” Energy Fuels, Vol. 4, No. 1, 1990, pp. 54-60. doi:10.1021/ef00019a010

[32] T. H. Fletcher and A. R. Kerstein, “Chemical Percolation Model for Devolatilization: 3. Direct Use of CNMR Date to Predict Effects of Coal Type,” Energy Fuels, Vol. 6, No. 4, 1992, pp. 414-431. doi:10.1021/ef00034a011

[33] D. M. Grant, R. J. Pugmire, T. H. Fletcher and A. R. Kerstein, “Chemical Percolation of Coal Devolatilization Using Percolation Lattice Statistics,” Energy Fuels, Vol. 3, No. 2, 1989, pp. 175-186. doi:10.1021/ef00014a011

[34] A. Silaen and T. Wang, “Effect of Turbulence and Devolatilization Models on Coal Gasification Simulation in an Entrained-Flow Gasifier,” International Journal of Heat and Mass Transfer, Vol. 53, No. 9-10, 2010, pp. 2074-2091. doi:10.1016/j.ijheatmasstransfer.2009.12.047

[35] I. W. Smith, “The Combustion Rates of Coal Chars: A Review,” 19th International Symposium on Combustion, Vol. 19, No. 1, 1982, pp. 1045-1065.

[36] S. V. Patankar, “Numerical Heat Transfer and Fluid Flow,” McGraw Hill, New York, 1980.