An overview of equipment and schemes of the coal ASH removal systems of thermal power plants

According to various expert estimates, coal-fired thermal power plants of Russia annually generate 25...30 million tons of the coal ash, and its utilization rate is only 10...12%. Thus, each year 22...27 million tons of the coal ash is transported to the disposal sites, which are the sources of significant environmental pollution. To this day, more than 1.5 billion tons of the coal ash have been accumulated at the disposal areas of the Russian Federation, and their number is growing every year. According to the national plans of the Russian energy industry, coal remains one of the main energy resources, accounting for about 13% of the country's fuel balance. Globally, coal accounts for 36% of all primary sources in the production of heat and electricity; the main share of coal generation is observed in the developing countries – China and India.
In the Russian Federation, the situation is aggravated by the fact that the average age of the coal-fired thermal power plants is about 50 years, which cannot but affect the technical and environmental performance of the coal ash removal systems of thermal power plants, as well as the performance of power plants in general. In this regard, reduction of the negative impact of the fuel and energy complex industries on the environment and coal power, in particular, is one of the global state tasks according to the Energy Strategy of the Russian Federation for the period up to 2035. Thus, the main activities aimed at reducing the negative impact of fuel and energy facilities on the environment are:
• elimination of the accumulated environmental damage, restoration of degraded natural ecosystems;
• reduction or preventing the negative impact of economic activity on the environment and the rational use of natural resources.
The problem of the coal-fired thermal power plants in terms of eliminating the accumulated environmental damage can be solved only by implementing large-scale projects of the integrated coal ash processing to obtain demanded products.
In order to reduce or prevent the accumulation of the coal ash, it is necessary, first of all, to switch to the state-ofthe- art coal ash handling technologies and implement the principles of the Best Available Techniques, use water-free coal ash handling technologies, thereby expanding the range of the coal ash applications, as well as to form and develop the coal ash market in view of the requirements of consumers.
The article includes the classification of the coal ash removal systems of thermal power plant as well as the results of an overview and analysis of the coal ash handling equipment, including the systems of internal and external coal ash transport. It describes the schemes of the traditional coal ash removal system with the joint coal ash collection and conveying, the schemes with separate removal, storage and shipment of the coal ash, as well as the combined coal ash removal scheme. A promising technology of the bottom ash removal applied at thermal power plants is considered. Recommendations for the development of economical and environmentally friendly coal ash removal systems of thermal power plants are given.

1. Sovremennye prirodookhrannye tekhnologii v ehlektroehnergetike: Informatsionnyi sbornik / pod obshchei red. V.YA. Putilova. M.: Izdatel'skii dom MEHI, 2007 – 388 s.: il.

2. Burov V.D., Dorokhov E.V., Elizarov D.P. Teplovye ehlektricheskie stantsii. M.: Izdatel'skii dom MEHI, 2007. 466 s.

3. Putilov V.YA., Putilova I.V. Bar'ery, vozmozhnosti i puti resheniya problemy obrashcheniya s zoloshlakami TEHS v Rossii / Mater. II Mezhd. nauchn. prakt. seminara «Zoloshlaki TEHS ― udalenie, transport, pererabotka, skladirovaniE». Moskva, 23-24 aprelya 2009 g. M.: Izdatel'skii dom MEHI. - s. 13-19.

4. Putilov V.YA., Putilova I.V. Analiz obshchemirovykh tendentsii i perspektiv resheniya problemy zoloshlakov TEHS v Rossii // Mater. I Mezhd. nauchn. prakt. seminar «Zoloshlaki TEHS ― udalenie, transport, pererabotka, skladirovaniE», 23 marta 2007 g., Moskva, Izdatel'skii dom MEHI, - M. s.11-17.

5. http://www.energyland.info/analitic-show-140270

6. Putilov V.YA., Putilova I.V., Malikova E.A. Klyuchevye voprosy resheniya problemy obrashcheniya s zoloshlakami ehnergetiki v Rossii // Materialy V mezhd. konf. «Zoloshlaki TEHS ― udalenie, trans-port, pererabotka, skladirovaniE». Moskva, 24-25 aprelya 2014 g. ― M.: Poligraficheskii tsentr MEHI. - s. 58-63.

7. V. Cianci, “Wet vs. dry bottom ash handling compared: one plant’s experience”, Modern Power Systems, June 2007.

8. V. Quattrucci, “Dry bottom ash technology improves coal fired boiler operations”, Power-Gen Europe, April 2004.

9. Y. Takahashi, “The First dry bottom ash handling system in Japan”, Power-Gen Asia, October 2002.

10. R. Tarli, A. Carrea // An efficient and nonpolluting bottom ash extraction system Energy for the transition age, Florence, Italy (June 1992).

11. F. Bassetti, D. Coppola, D. Ricci // Fully-dry removal system for elimination of pond.

12. Proc. World of Coal Ash Conference (WOCA), May 2015, Nashville, (Tennessee, USA) (May 2015).

13. N.V. Gavlitin, YU.V. Kolomiets. Ehkologicheski priemlemye tekhnologii zoloshlakoudaleniya na primere Reftinskoi GREHS OAO «Ehnel OGK-5» // Materialy IV nauchno-prakticheskogo seminara «Zo-loshlaki TEHS: udalenie, transport, pererabotka, skladirovaniE», Moskva, 19–20 aprelya 2012 g. ― M.: Izdatel'skii dom MEHI, 2012. S. 55 – 58.

14. M. Khili, YU. Kolomiets. Primenenie tekhnologii pnevmotransportirovaniya zoloshlakov ot ehnergoblokov moshchnost'yu 300 i 500 MVt ugol'nykh ehlektrostantsii // Materialy II nauchno-prakticheskogo seminara «Zoloshlaki TEHS: udalenie, transport, pererabotka, skladirovaniE», Moskva, 23–24 aprelya 2009 g. ― M.: Izdatel'skii dom MEHI, 2009. S. 101 – 103.

15. Daniele Ricci, Fulvio Bassetti, Simone Savastano, Beneficial effects of dry bottom ash extraction and recycling in modern PCF power plants, Fuel, Volume 215, 2018, Pages 13-21, ISSN 0016-2361, https://doi.org/10.1016/j.fuel.2017.10.088 Beneficial effects of dry bottom ash extraction and recycling in modern PCF power plants.