Modeling of heat and mass transfer during thermal decomposition of a single solid fuel particle

Open access

Abstract

The aim of this work was to investigate the heat and mass transfer during thermal decomposition of a single solid fuel particle. The problem regards the pyrolysis process which occurs in the absence of oxygen in the first stage of fuel oxidation. Moreover, the mass transfer during heating of the solid fuels is the basic phenomenon in the pyrolysis-derived alternative fuels (gas, liquid and solid phase) and in the gasification process which is focused on the generation of syngas (gas phase) and char (solid phase). Numerical simulations concern pyrolysis process of a single solid particle which occurs as a consequence of the particle temperature increase. The research was aimed at an analysis of the influence of particle physical properties on the devolatilization process. In the mathematical modeling the fuel grain is treated as an ideal sphere which consists of porous material (solid and gaseous phase), so as to simplify the final form of the partial differential equations. Assumption that the physical properties change only in the radial direction, reduces the partial derivatives of the angular coordinates. This leads to obtaining the equations which are only the functions of the radial coordinate. The model consists of the mass, momentum and energy equations for porous spherical solid particle heated by the stream of hot gas. The mass source term was determined in the wide range of the temperature according to the experimental data. The devolatilization rate was defined by the Arrhenius formula. The results of numerical simulation show that the heating and devolatilization time strongly depend on the physical properties of fuel. Moreover, proposed model allows to determine the pyrolysis process direction, which is limited by the equilibrium state.

[1] Kurose R., Watanabe H., Makino H.: Numerical simulations of pulverized coalcombustion. KONA Powder Part. J. 27(2009), 144-156.

[2] Fu Z., Guo Z., Yuan Z., Wang Z.: Swelling and shrinkage behavior of raw andprocessed coals during pyrolysis. Fuel 86(2007), 418-425.

[3] Tomeczek J.: Coal combustion. The academic scripts 1667. Silesian University of Technology, Gliwice 1992 (in Polish).

[4] Wardach-Świ¸ecicka I., Kardaś D., Pozorski J.: Modelling of interactionsbetween variable mass and density solid particles and swirling gas stream. J. Phys. Conf. Ser., EIOP Publishing Ltd. ETC13 318(2011), 13/11.

[5] Tuck A.R.C., Hallet W.L.H.: Modelling of particle pyrolysis in a packed bedcombustor. Tech. Rep., University of Ottawa, Ontario 2004.

[6] Iciek J., Kamiński W., Kudra T, Markowski A.: The heat transfer calculations. The academic scripts, Technical University of Łodź, Łodź 1993 (in Polish).

[7] Wardach-Świ¸ecicka I., Kardaś D.: Modeling of solid fuel particles combustion. Proc. Int. Symp. on Turbulence, 7th, Heat and Mass Transfer, CD, ISBN 978-1-56700-302-4, Palermo 2012.

[8] Kardaś D.: Model of the coal and biomass pyrolysis rate in the non-equilibriumthermodynamic state. Tech. Rep. IF-FM PASci. 227/2010, Gdańsk 2010 (in Polish).

[9] Ści ¸ażko M.: Modeling of pressure generation from the thermally plastified packedbed coal grains. Tech. Rep. IChPC, Zabrze 2005 (in Polish).

[10] Polesek-Karczewska S.: Comparative analysis of the kinetics of gasificationof different types of biomass and fossil fuels. Tech. Rep. IF-FM PASci. 141/2008, Gdańsk 2008 (in Polish).

[11] Kardaś D., Polesek-Karczewska S.: Description and solution of onedimensionalunsteady biomass pyrolysis problem in the reactor. Tech. Rep. UWM, Olsztyn 2013 (in Polish).

[12] ANSYS Fluent 12.0 Tutorial Guide. Updated for ANSYS Fluent 12.1, ANSYS, Inc., 2009.

[13] Carslaw H.S., Jaeger J.C.: Conduction of heat in solids. Oxford UP, Ely House, London 1959.

[14] Kalinowski E.: Heat transfer and heat exchangers. Oficyna Wydawnicza Politechniki Wrocławskiej, Wrocław 1995 (in Polish).

[15] Ści ¸ażko M.: Coal classification models - thermodynamic and kinetic approach. Wydawnictwa AGH, Krakow 2010 (in Polish).

[16] Yang Y.B., Yamauchi H., Nasserzadeh V., Swithenbank J.: Effects of fueldevolatilisation on the combustion of wood chips and incineration of simulated municipalsolid wastes in a packed bed. Fuel 82(2003), 2205-2221.

[17] Ross R.J. (Ed.): Wood Handbook, Wood as an Engineering Material. Forest Products Laboratory, United States Department of Agriculture Forest Service, Madison, Wisconsin 2010.

[18] Heidenreich C.A., Yan H.M., Zhang D.K.: Mathematical modelling of devolatilizationof large coal particles in a convective environment. Fuel 78(1999), 557-566.

[19] Speight J.G.: Handbook of Coal Analysis. John Wiley & Sons, Inc., New Jersey 2005.

[20] Navarro M.V., Martinez J.D., Murillo R., Garcia T., López J.M., Callén M.S., Mastral A.M.: Application of particle model to pyrolysis. Comparisonof different feedstock: Plastic, tyre, coal and biomass. Fuel Process. Tech. 103(2012), 1-8.

Archives of Thermodynamics

The Journal of Committee on Thermodynamics and Combustion of Polish Academy of Sciences

Journal Information


CiteScore 2016: 0.54

SCImago Journal Rank (SJR) 2016: 0.319
Source Normalized Impact per Paper (SNIP) 2016: 0.598

Cited By

Metrics

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 212 212 16
PDF Downloads 88 88 9