ESTONIAN ACADEMY
PUBLISHERS
eesti teaduste
akadeemia kirjastus
PUBLISHED
SINCE 1984
 
Oil Shale cover
Oil Shale
ISSN 1736-7492 (Electronic)
ISSN 0208-189X (Print)
Impact Factor (2022): 1.9
CO-COMBUSTION OF COAL AND OIL SHALE BLENDS IN CIRCULATING FLUIDIZED BED BOILERS; pp. 114–127
PDF | https://doi.org/10.3176/oil.2019.2S.03

Authors
ALAR KONIST, Heliis Pikkor, Dmitri Neshumayev, LAURI LOO, OLIVER JÄRVIK, ANDRES SIIRDE, TÕNU PIHU
Abstract

Coal co-firing experiments were conducted in a 250 MW oil shale fired circulating fluidized bed combustion (CFBC) boiler. The objective of the experiments was to test whether adding coal to oil shale would allow the use of the latter with lower heating value. Bituminous coal was mixed with oil shale and fed into the boiler via existing fuel feeding ports. Two test series were accomplished: 11–29% thermal input of coal mixed with 8.4 MJ/kg oil shale (standard fuel), and 12–32% thermal input of coal mixed with 7.5 MJ/kg oil shale. During the experiments, which lasted in total for 15 days, ash samples were collected and flue gas analysis was performed. The boilers were able to continue work with all the fuel mixtures, but a significant increase of nitrogen oxides (NOx) emissions and heat losses due to unburnt carbon in the bottom and fly ashes were observed. The heat losses can be reduced by upgrading the fuel preparation system, but NOx emissions limit can be reached only with installation of an additional DeNOx system. The ash chemical composition remained similar. Sulphur emissions stayed minimal, but a slight increase of carbon monoxide concentration was noticed. Coal co-firing is possible in oil shale CFBC boilers, but the coal must have low fuel nitrogen content and extra attention to the fuel preparation system has to be paid.

References

 

1.      Konist, A., Pihu, T., Neshumayev, D., Külaots, I. Low grade fuel - oil shale and biomass co-combustion in CFB boiler. Oil Shale, 2013, 30(2S), 294–304.
https://doi.org/10.3176/oil.2013.2S.09

2.      Pihu, T., Konist, A., Neshumayev, D., Loo, L., Molodtsov, A., Valtsev, A. Full-scale tests on the co-firing of peat and oil shale in an oil shale fired circulating fluidized bed boiler. Oil Shale, 2017, 34(3), 250–262.
https://doi.org/10.3176/oil.2017.3.04

3.      Konist, A., Järvik, O., Pihu, T., Neshumayev, D. Combustion as a possible solution to pyrolytic wastewater utilization. Chem. Eng. Trans., 2018, 70, 859−864.

4.      Neshumayev, D., Rummel, L., Konist, A., Ots, A., Parve, T. Power plant fuel consumption rate during load cycling. Appl. Energ., 2018, 224, 124−135.
https://doi.org/10.1016/j.apenergy.2018.04.063

5.      Rummel, L., Neshumayev, D., Konist, A. Power plant ash composition transformations during load cycling. Chem. Eng. Trans., 2018, 70, 655−660.

6.      Kokko, A., Nylund, M. Biomass and coal co-combustion in utility scale: operat­ing experience of Alholmens Kraft. In: Proceedings of the 18th International Conference on Fluidized Bed Combustion, Toronto, Ontario, Canada, May 22–25, 2005. New York, 2005.
https://doi.org/10.1115/FBC2005-78035

7.      Sahu, S. G., Chakraborty, N., Sarkar, P. Coal–biomass co-combustion: An overview. Renew. Sust.. Energ. Rev., 2014, 39, 575–586.
https://doi.org/10.1016/j.rser.2014.07.106

8.      Krzywanski, J., Rajczyk, R., Bednarek, M., Wesolowska, M., Nowak, W. Gas emissions from a large scale circulating fluidized bed boilers burning lignite and biomass. Fuel Process. Technol., 2013, 116, 27–34.
https://doi.org/10.1016/j.fuproc.2013.04.021

9.      Coda Zabetta, E., Barisic, V., Peltola, K., Sarkki, J., Jantti, T. Advanced technology to co-fire large shares of agricultural residues with biomass in utility CFBs. Fuel Process. Technol., 2013, 105, 2–10.
https://doi.org/10.1016/j.fuproc.2011.05.006

10. Valgma, I., Reinsalu, E., Sabanov, S., Karu, V. Quality control of oil shale production in Estonian mines. Oil Shale, 2010, 27(3), 239–249.
https://doi.org/10.3176/oil.2010.3.05

11. Plamus, K., Ots, A., Pihu, T., Neshumayev, D. Firing Estonian oil shale in CFB boilers – Ash balance and behaviour of carbonate minerals. Oil Shale, 2011, 28(1), 58–67.
https://doi.org/10.3176/oil.2011.1.07

12. Parve, T., Ots, A., Skrifars, B.-J., Hupa, M. The sintering of Estonian oil shale ashes. Oil Shale, 1995, 12(4), 341–356.

13. Al-Otoom, A., Al-Harahsheh, M., Batiha, M. Sintering of Jordanian oil shale under similar conditions of fluidized bed combustion systems. Oil Shale, 2014, 31(1), 54–65.
https://doi.org/10.3176/oil.2014.1.06

14. Plamus, K., Soosaar, S., Ots, A., Neshumayev, D. Firing Estonian oil shale of higher quality in CFB boilers - environmental and economic impact. Oil Shale, 2011, 28(1S), 113–126.
https://doi.org/10.3176/oil.2011.1S.04

15. Konist, A., Pihu, T., Neshumayev, D., Siirde, A. Oil shale pulverized firing: boiler efficiency, ash balance and flue gas composition. Oil Shale, 2013, 30(1), 6–18.
https://doi.org/10.3176/oil.2013.1.02

16. Loo, L., Konist, A., Neshumayev, D., Pihu, T., Maaten, B., Siirde. A. Ash and flue gas from oil shale oxy-fuel circulating fluidized bed combustion. Energies, 2018, 11(5), 1218.
https://doi.org/10.3390/en11051218

17. Al-Makhadmeh, L., Maier, J., Al-Harahsheh, M., Scheffknecht, G. Oxy-fuel technology: An experimental investigation into oil shale combustion under oxy-fuel conditions. Fuel, 2013, 103, 421–429.
https://doi.org/10.1016/j.fuel.2012.05.054

18. Al-Makhadmeh, L., Maier, J., Al-Harahsheh, M., Scheffknecht, G. Oxyfuel technology: Oil shale desulphurisation behaviour during unstaged combustion. Fuel, 2015, 158, 460–470.
https://doi.org/10.1016/j.fuel.2015.05.059

 

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