MATHEMATICAL DESCRIPTION OF THE SOLID FUEL GASIFICATION PROCESS IN A FIXED BED: 1. NUMERICAL RESULTS OF THERMAL-CHEMICAL PROCESSING OF PEAT IN A VAPOR- OXYGEN MIXTURE UNDER A PRESSURE OF 3 MPa


Keywords: fixed bed, coal, thermal conductivity, steam-oxygen gasification, conductive, radiation, temperature.

Abstract

With the help of  the developed two-dimensional model presented in the first part of this work, which includes interfacial convective heat transfer, radiation-conductive heat transfer of the solid phase, radiant and conductive heat transfer of the fixed bed with the reactor wall, heterogeneous and homogeneous chemical reactions, gravity and aerodynamic resistance, the non-stationary gasification of Shubarkol  long-flame coal in a steam-oxygen mixture under a pressure of 3 MPa in a fixed bed with solid slag removal at a ratio of mass fractions of  gas components  H2О/O2=72/28 was  numerically investigated. It is shown: 1) in this mode, the temperature of coke-ash particles does not exceed 1000 0С due to the prevalence of heat generation of exothermic reactions C+O2=CO2, C+0,5O2=CO, CO+0,5O2=CO2 and H2+0,5O2=H2O over the heat absorption of endothermic reactions C+СO2=2CO and C+H2O=CO+H2 due to the high concentration of water vapor in the gas mixture. Therefore, calorie and quality of the generator gas (at the time τ = 260 s (by volume): CO=16,4%, H2=44,6%, СO2=27,6%, CH4=10,1% and C6H6=1,16%) is significantly inferior to the synthetic gas obtained with the ratio of mass fractions of gaseous components H2О/O2=40/60  (τ = 280 с: CO=65%, H2=25,6%, СO2=3,8%, CH4=5% and C6H6=0,57%) [1]; 2) To eliminate overheating of the grate due to the low height of the slag pad, due to low ash content of coal 3–9%, it is recommended to add waste ash to the initial fuel, which will increase the height of the protective inert bed. 3) the calculated composition of the synthetic gas at τ = 260 s is in good agreement with the literature data given in [2]: CO=12–21%, H2=37–41%, СO2=27–34% and CH4=10–13,5%. Ref. 1, tab. 1, fig. 10.

References

1. Rokhman B.B. Dvumernaya model processa gazifikacii tverdogo topliva v nepodvizhnom sloe pod davleniem. 1. Issledo-vanie konversii shubarkolskogo kamennogo uglya v parokislo-rodnoj smesi pri otnoshenii massovyh dolej H2О/O2=45/55. [Two-dimensional model of solid fuel gasification in a fixed bed under pressure. 1. Investigation conversion of Shubarkol coal conversion in a steam-oxygen mixture with the mass past of H2О/O2=45/55]. Vidnovluvana energetika. 2019. No. 1. Pp. 61-71. [in Russian].

Author Biography

B. Rokhman, Coal Energy Technology Institute NAS of Ukraine, 04070, Kyiv, str. Andreevskaya 19

Rokhman.jpgAuthor information: the leading researcher of the Institute of Coal Energy Technologies of the NAS of Ukraine, Doctor of Technical Sciences. Biographical information of Rohman B.B. is published in well-known world directories "Who's Who in Science and Engineering" and "2000 Outstanding Intellectuals of the 21st Century".
Education: Novocherkassk Polytechnic Institute.
Research area: Mathematical modeling of aerodynamics, heat and mass transfer and chemical reaction of a polydisperse ensemble of solid fuel in chamber and layer furnaces, in reactors with a circulating fluidized bed and in the fluidized bed.
Publications: more than 90 scientific papers, 27 of them are contained in the science-based Scopus database and 4 in the science-based  Web of Science database.


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Published
2019-09-25
How to Cite
Rokhman, B. (2019). MATHEMATICAL DESCRIPTION OF THE SOLID FUEL GASIFICATION PROCESS IN A FIXED BED: 1. NUMERICAL RESULTS OF THERMAL-CHEMICAL PROCESSING OF PEAT IN A VAPOR- OXYGEN MIXTURE UNDER A PRESSURE OF 3 MPa. Vidnovluvana Energetika, (3(58), 78-90. https://doi.org/https://doi.org/10.36296/1819-8058.2019.3(58).78-90