Mining of Mineral Deposits

ISSN 2415-3443 (Online)

ISSN 2415-3435 (Print)

# Substantiating parameters of stratification cavities formation in the roof rocks during underground coal gasification

V. Falshtynskyi1, V. Lozynskyi1, P. Saik1, R. Dychkovskyi1, M. Tabachenko1

1Underground Mining Department, National Mining University, Dnipropetrovsk, Ukraine

Min. miner. depos. 2016, 10(1):16-24

https://doi.org/10.15407/mining10.01.016

Full text (PDF)

ABSTRACT

Purpose. Underground coal gasification, as a complex and technically difficult process, should be supported in many aspects by computer simulations or analytical calculations of rock mass behavior. However, little is known about the formation of stratification cavities in the roof rocks during coal seam gasification. To research the formation of stratification cavities and rocks deformations by mine pressure with the methods of calculation based on hypotheses or statistical information, a number of hypotheses are used. The main purpose is to examine the rock mass behavior and formation of stratification cavities during gasification of a thick coal seam.

Methods. Analytical calculations were used as the research method for the work presented. The mathematical model of the stress-strain state of rock mass based on the theory of elasticity, resiliency, and maximum equilibrium, was developed and used in this paper.

Findings. Critical analysis of geomechanical models of coal gasification together with their mathematical formulation was the result of considerations presented in this paper. Equations were derived for substantiating parameters of stratification cavities above the goaf of the underground gasifier. Subsequently, the volumes of stratification cavities depending on the length of gasification channel were calculated. The results have significant influence on gasifiers development and the final efficiency of gasification process.

Originality. The research results were obtained from analytical calculations of rock mass behavior during thick coal seams gasification. The authors implemented a mathematical model based on the method suggested by professor A. Savostianov which was used in carrying out the calculations.

Practical implications. The present study provides a starting point for further research and analytical calculations of rock mass behavior. The data and conclusions outlined in this paper may be useful in preliminary optimization and analysis of coal seams gasification. They can also be a point of reference for more advanced geomechanical simulations.

Keywords: underground coal gasification, gasifier, rock mass, stratification cavities, goaf

REFERENCES

Astafiev, D., & Shapovalov, Y. (2013). On the question of implementation prospects of selective mining for exploitation unconditional coal seams. Mining Of Mineral Deposits, 313-317.
https://doi.org/10.1201/b16354-58

Bhutto, A., Bazmi, A., & Zahedi, G. (2013). Underground coal gasification: From fundamentals to applications. Progress In Energy And Combustion Science, 39(1), 189-214.
https://doi.org/10.1016/j.pecs.2012.09.004

Den’gina, N., Kazak, V., & Pristash, V. (1993). Changes in rocks at high temperatures. Journal of Mining Science, 29(5), 472-477.
https://doi.org/10.1007/bf00733026

Dychkovskyi, R., Falshtynskyi, V., Lozynskyi, V., & Saik, P. (2015). Development the concept of borehole underground coal gasification technology in Ukraine. New Developments in Mining Engineering 2015, 91-95.
https://doi.org/10.1201/b16354-23

Falshtyns’kyy, V., Dychkovs’kyy, R., Lozyns’kyy, V., & Saik, P. (2013). Justification of the gasification channel length in underground gas generator. Mining of Mineral Deposits, 125-132.
https://doi.org/10.1201/b19901-18

Falshtynskyi, V., Dychkovskyi, R., Lozynskyi, V., & Saik, P. (2013). Determination of the Technological Parameters of Borehole Underground Coal Gasification for Thin Coal Seams. Journal of Sustainable Mining, 12(3), 8-16.
https://doi.org/10.7424/jsm130302

Falshtynskyy, V., Dychkovskyy, R., Lozynskyy, V., & Saik, P. (2012). New method for justification the technological parameters of coal gasification in the test setting. Geomechanical Processes during Underground Mining: School of Underground Mining 2012, 201-208.
https://doi.org/10.1201/b13157-35

Kapusta, K., Stańczyk, K., Wiatowski, M., & Chećko, J. (2013). Environmental aspects of a field-scale underground coal gasification trial in a shallow coal seam at the Experimental Mine Barbara in Poland. Fuel, 113, 196-208.
https://doi.org/-10.1016/j.fuel.2013.05.015

Kononenko, M., & Khomenko, O. (2010). Technology of support of workings near to extraction chambers. New Techniques and Technologies in Mining, 193-197.
https://doi.org/10.1201/b11329-32

Lozynskyi, V.H., Dychkovskyi, R.O, Falshtynskyi, V.S., & Saik, P.B. (2015). Revisiting possibility to cross disjunctive geological faults by underground gasifier.. Naukovyi Visnyk Natsionalnoho Hirnychoho Universytetu, (4), 22-27.

Morris, J.P., Buscheck, T.A., & Hao, Y. (2009). Coupled geomechanical simulations of UCG cavity evolution. In Proceedings of the 2009 International Pittsburgh Coal Conference, Pittsburgh PA.

Nowak, J., & Kudelko, J. (2012). LGOM region as a perspective power energy basin and implementation of innovative lignite development methods. Mineral Economics, 25(2-3), 65-70.
https://doi.org/10.1007/s13563-012-0024-y

Otto, C., & Kempka, T. (2015). Thermo-Mechanical Simulations of Rock Behavior in Underground Coal Gasification Show Negligible Impact of Temperature-Dependent Parameters on Permeability Changes. Energies, 8(6), 5800-5827.
https://doi.org/10.3390/en8065800

Perkins, G., & Sahajwalla, V. (2007). Modelling of Heat and Mass Transport Phenomena and Chemical Reaction in Underground Coal Gasification. Chemical Engineering Research And Design, 85(3), 329-343.
https://doi.org/10.1205/cherd06022

Savostianov, A.V., & Klochkov, V.H. (1992). Upravlenie sostoyaniem massiva hornyh porod (p. 276). Dnipropetrovsk: National Mining University.

Vorobiev, O.Y., Morris, J.P., Antoun, T.H., & Friedmann, S.J. (2008). Geomechanical simulations related to UCG activities. InternationalPittsburgh Coal Conference, Pittsburgh, PA.

Wachowicz, J., Łączny, J., Iwaszenko, S., Janoszek, T., & Cempa-Balewicz, M. (2015). Modelling of Underground Coal Gasification Process Using CFD Methods / Modelowanie Procesu Podziemnego Zgazowania Węgla

Kamiennego Z Zastosowaniem Metod CFD. Archives Of Mining Sciences, 60(3).
https://doi.org/10.1515/amsc-2015-0043

Wolf, K., & Bruining, H. (2007). Modelling the interaction between underground coal fires and their roof rocks. Fuel, 86(17-18), 2761-2777.
https://doi.org/10.1016/j.fuel.2007.03.009

Yang, D., Sarhosis, V., & Sheng, Y. (2014). Thermal-mechanical modelling around the cavities of underground coal gasification. Journal Of The Energy Institute, 87(4), 321-329.
https://doi.org/10.1016/j.joei.2014.03.029