CHANGE OF EQUIVALENT LAYER POROSITY OF PELLETS ALONG THE LENGTH OF BURNING CONVEYOR MACHINE

Difficulties in determining the flow resistance of layer of pellets in the burning conveyor type machines during the heat treatment, associated with significant changes in the layer structure due to its shrinkage during the drying process, the low strength of raw pellets, adjustment layer segregation, sintering and melting of pellets, were considered. As a result, flow resistance of pellets layer on conveyor machines greatly exceeds the resistance value which is obtained in laboratory tests of gas dynamics of pellet layer. According to the impact of many factors on the structure of a burnt pellets layer, which can be taken into account only in their cumulative effect, the authors have introduced the concept of an equivalent porosity. As a result of calculating the amount of equivalent porosity with the available literature data and the data obtained in working out the pellets burning technology in a high layer on Kachkanar conveyor machines, a pattern of its distribution along the length of the conveyor machine was revealed. It was established that most significantly the porosity of the layer reduce due to layer shrinkage in the drying zone and cracking of pellets at the outlet of it. The analysis of estimated expressions to determine the gas-dynamic characteristics of the pellets layer helped to get the dependencies that with a sufficient degree of accuracy can be used to calculate the gas-dynamic characteristics of the layer on the conveyor machines considering different porosity. The obtained results can be used in determining the gas dynamic and thermal conditions, providing work of burning conveyor machines with low specific fuel consumption and high quality of the calcined product.

Government of the Russian Federation (Act 211, contract no. 02.А03.21.0006)

1. Liu H., Jonsson L. T.I., Olofsson U., Jönsson P.G. A simulation study of particles generated from pellet wear contacts during a laboratory test. ISIJ International. 2016, vol. 56, no. 11, pp. 1910–1919.

2. Panic B., Janiszewski K. Model investigations 3D of gas-powder two phase flow in descending packed bed in metallurgical shaft furnaces. Metalurgija. 2014, vol. 53 (3), pp. 331–334.

3. Liu, Y., Su, F.-Y., Wen Z. CFD modeling of flow, temperature, and concentration fields in a pilot-scale rotary hearth furnace. Metallurgical and Materials Transactions B. 2014, vol. 45 (1), pp. 251–261.

4. Dai C., Lei Z., Li Q. Pressure drop and mass transfer study in structured catalytic packings. Sep. Purif. Technol. 2012, vol. 98 (1), pp.  78–87.

5. Li L., Remmelgas J., van Wachem B.G.M. Effect of drag models on residence time distributions of particles in a wurster fluidized bed: a DEM-CFD study. Kona powder and particle journal. 2016, vol.  33, pp. 264–277.

6. Dmitriev E.A., Nosyrev M.A., Trushin A.M. On the issue of determining the porosity of the fluidized bed in the system of solid particles – gas. Khimicheskaya promyshlennost’ segodnya. 2013, no.  9, pp. 53–56. (In Russ.).

7. Dmitriev E.A., Kabanov O.V., Kulikov M.V., Nosyrev M.A., Trushin A.M. On the issue of porosity of a heterogeneous fluidized bed. Teoreticheskie osnovy khimicheskoi tekhnologii. 2015, vol. 49, no. 6, pp. 644–650. (In Russ.).

8. Guo L., Morita K., Tobita Y. Numerical simulation of three-phase flows with rich solid particles by coupling multi-fluid model with discrete element method. Proceedings of the 20th Int. Conf. on Nuclear Engineering and the ASME 2012 Power Conf. 2012, vol. 4, pp.  371–382.

9. Croft T. N., Cross M., Slone A. K. CFD analysis of an induration cooler on an iron ore grate-kiln pelletising process. Minerals Engineering. 2009, vol. 22, pp. 859–873.

10. Barati M. Dynamic simulation of pellet induration process in straight-grate system. International Journal of Mineral Processing. 2008, vol. 89 (1 – 4), pp. 30–39.

11. Todd R.S., Webley, P.A. Pressure drop in a packed bed under nonadsorbing and adsorbing conditions. Industrial & Engineering Chemistry Research. 2005, vol. 44 (18), pp. 7234–7241.

12. Schults H.J., Abel O. Durck Störmungsverhalten von FormkoksErz-Stükkoks-Systemen. Arch. Eisenhüttenwesen. 1974, Bd. 45, no.  5, pр. 279–285. (In Germ.)

13. Abzalov V.M., Gorbachev V.A., Evstyugin S.V. etc. Fiziko-khimicheskie i teplotekhnicheskie osnovy proizvodstva zhelezorudnykh okatyshei [Physical-chemical and thermotechnical basis of the iron-ore pellet production]. Leont’ev L.I. ed. Ekaterinburg: NPVP TOREKS, 2012, 340 p. (In Russ.).

14. Yur’ev B.P., Gol’tsev V.A., Lugovkin V.V., Yarchuk V.F. Hydraulic drag of dense beds consisting of particles of different shape. Steel in Translation. 2015, vol. 45. no. 9, pp. 662–668.

15. Bryukhanov O.N., Korobko V.I., Melik-Arakelyan A.T. Osnovy gidravliki, teplotekhniki i aerodinamiki [Basics of hydraulics, thermal technology and aerodynamics]. Moscow: INFRA-M, 2012, 253 p. (In Russ.).

16. Rtishchev A.S. Teoreticheskie osnovy gidravliki i teplotekhniki [Theoretical basics of hydraulics and thermal technology]. Ulyanovsk: UlGTU, 2007, 171 p. (In Russ.).

17. Stulov V.P. Lektsii po gazovoi dinamike [Lectures on gas dynamics]. Moscow: FIZMATLIT, 2006, 192 p. (In Russ.).

18. Bryukhanov O.N., Melik-Arakelyan A.T., Korobko V.I. Osnovy gidravliki i teplotekhniki [Basics of hydraulics and thermal technology]. Moscow: Akademiya, 2011, 240 p. (In Russ.).

19. Gushchin S.N., Kazyaev M.D., Kiselev E.V., Shavrin V.S., Yur’ev  B.P. Gidravlicheskii raschet truboprovodov i vybor tyagodut’evykh sredstv, obespechivayushchikh rabotu promyshlennykh pechei [Pipeline system hydraulic calculation and choice of a draft capacity options providing the work of industrial furnaces]. Ekaterinburg: UrFU, 2011, 140 p. (In Russ.).

20. Idel’chik I.E. Spravochnik po gidravlicheskim soprotivleniyam [Reference book on hydraulic resistance]. Moscow: Mashinostroenie, 1992, 672 p. (In Russ.).

21. Aerov M.E., Todes O.M., Narinskii D.A. Apparaty so statsionarnym zernistym sloem [Units with stationary granular layer]. Leningrad: Khimiya, 1979, 176 p. (In Russ.).

22. Volkov K.N., Deryugin Yu.N., Emel’yanov V.N. Metody uskoreniya gazodinamicheskikh raschetov na nestrukturirovannykh setkakh [Acceleration methods of gas-dynamic calculations on non-structured grids]. Moscow: FIZMATLIT, 2014, 535 p. (In Russ.).

23. Volkov K.N., Emel’yanov V.N. Vychislitel’nye tekhnologii v zadachakh mekhaniki zhidkosti i gaza [Computing technologies in tasks of liquids and gases mechanics]. Moscow: FIZMATLIT, 2013, 468 p. (In Russ.).

24. Chechetkin A.V. Vysokotemperaturnye teplonositeli [High-temperature heat-carrying agents]. Moscow: Energiya, 1971, 496 p. (In Russ.).

25. Rovenskii I.I., Berezhnoi N.N. Research of gas transmission in pellets layer. IzvestiyaVUZov. Chernaya metallurgiya = Izvestiya. Ferrous Metallurgy. 1964, no. 1, pp. 27–32. (In Russ.).

26. Bratchikov S.G., Berman Yu.A., Belotserkovskii Ya.L. etc. Teplotekhnika okuskovaniya zhelezorudnogo syr’ya [Thermal technology of iron-ore raw material pelletizing]. Moscow: Metallurgiya, 1970, 344 p. (In Russ.).

27. Kuznetsov R.F., Maizel’ G.M., Belotserkovskii Ya.L., Onishchenko  A.E., Dokuchaev P.N., Antuganova G.M. Aerodynamic characteristics of calcining conveyor machines. Metallurgist. 1974, vol.  18, no. 7, pp. 514-517.