Experimental studies of the influence of pressure of slurry fuel and air on the spray cone structure during atomization

Results of experimental studies of pneumomechanical atomization process of slurry fuel with a plasticizer in an aerodynamic simulator of power boiler furnace are presented. Analysis of the current state in the field of research of slurry fuel atomization processes has been conducted. Influence of pressure of slurry fuel and air on the structure of the emerging spray cone have been analyzed. The values of characteristic dimensions of three zones of spray cone have been determined: core, middle and outer zones. Effect of pressure of the sprayed slurry fuel and air on the period of stable spray cone formation and geometric characteristics of the zones has been experimentally confirmed. Ranges of velocities and sizes of droplets in the flow at various pressures have been distinguished. The quantitative values of slurry fuel droplets with different velocities in the process of its pneumatic spraying have been obtained. It has been established that the largest number of particles in the study area have velocities up to 8 m/s; a significant number of droplets (up to 20%) have velocities from 8 to 32 m/s; velocities of 32 m/s and more are typical for 1% of droplets. During the results processing, aerosol particles with a size of 1 micron or less have not been taken into account. The values of We criterion for the respective sizes and velocities of the sprayed fuel droplets have been determined. It has been established that significant part of the droplets undergoes catastrophic crushing, which is characteristic for the values of We numbers from 7800 and higher. The obtained results can be used for mathematical and physical modeling of the process of slurry fuels atomization in the furnaces of power boilers in order to predict the aerodynamic characteristics of the designed and existing units.

1. Ovchinnikov YuV, Boyko EE, Serant FA. Problems of combustion of coal-water fuels and proposals for the development of combustion technology. Reports of the Academy of Sciences of Higher School of the Russian Federation. 2015;1 (26):85-93. Available at: https://doi.org/10.17212/1727-2769-2015- 1-85-93.

2. Status of DOE's Clean Coal Program. Available at: URL: https://www.energy.gov/fe/articles/status-does-clean-coal-program. Accessed to: 19 Feb 2019.

3. Delyagin GN. Ecological clean fuel ECOWET - the way of a sharp improvement of the ecological situation in the power industry of Russia. Materials of the international scientific-practical conference “Ecology of power engineering 2000”. 2000. pp. 320-323.

4. Salomatov VV. The state and prospects of coal and nuclear power engineering in Russia. Thermophysics and Aeromechanics. 2009;16(4):531-544.

5. Clean Coal Technology Demonstration Program. Available at: URL:https://www.energy.gov/fe/downloads/clean-coal-technology-demonstration-program. Accessed to: 19 Feb 2019.

6. Kurgankina MA, Nyashina GS, Strizhak PA. Advantages of switching coal-burning power plants to coal-water slurries containing petrochemicals. Applied Thermal Engineering. 2019. pp. 998-1008.

7. Murko V, Hamalainen V. The Development of Environmentally Friendly Technologies of Using Coals and Products of Their Enrichment in the Form of Coal Water Slurries. E3S Web of Conferences. 2017. V. 21.

8. Lefebvre AH. Airblast atomization. Progress in Energy and Combustion Science. 1980. V. 6. pp. 233-261.

9. Lefebvre AH. McDonell VG. Atomization and Sprays. 2nd edition. Boca Raton: CRC Press, 2017.

10. Urbán A, Malý M, Józsa V, Jedelský J. Effect of liquid preheating on high-velocity airblast atomization: From water to crude rapeseed oil. Experimental Thermal and Fluid Science. 2019. pp. 137-151.

11. Esteban B, Riba J.-R, Baquero G, Rius A., et al. Temperature dependen cofdensity and viscosity of vegetable oils. Biomass & Bioenergy. 2012;42:164-171.

12. Wang XF, Lefebvre AH. Influence of fuel temperature on atomization performance of pressure- swirl atomizers. Journal of Propulsion and Power. 1988;4:222–227.

13. Shah PR, Ganesh A. Study the influence of pre-heating on atomization of straight vegetable oil through Ohnesorge number and Sauter mean diameter. Journal of the Energy Institute. 2017.

14. Hanna R, Zoughaib A. Atomization of high viscosity liquids through hydraulic atomizers designed for water atomization. Experimental Thermal and Fluid Science. 2017;85:140-153.

15. Park SH, Kim HJ, Suh HK, et al. Experimental and numerical analysis of spray-atomization characteristics of biodiesel fuel in various fuel and ambient temperatures conditions. International Journal of Heat and Fluid Flow. 2009;30:960–970.

16. Al-Shudeifat MA, Donaldson AB. Combustion of waste trap grease oil in gas turbine generator. Fuel. 2010;89:549-553.

17. Seljak T, Oprešnik SR, Kunaver M, et al. Effects of primary air temperature on emissions of a gas turbine fired by liquefied spruce wood. Biomass & Bioenergy. 2014;71:394-407.

18. Seljak T, Katrašnik T. Designing the microturbine engine for waste-derived fuels. Waste Management. 2016. V. 47. pp. 299-310.

19. Zenkov A, Larionov K, Yankovsky S, et al. Research of rheological properties improvement methods of coal-water fuel based on low-grade coal. MATEC Web of Conferences. 2017. V.141.

20. Kijo–Kleczkowska A. Combustion of coal-water suspensions. Fuel. 2011;90:865-877.

21. Saito M, Sadakata M, Sakai T. Single droplet combustion of coal-oil/methanol/water mixtures Fuel. 1983; 63:1481-1486.

22. Borodulya VA, Buchilko EK, Vinogradov LM. Some special features of combusting the coal- water fuel made of Belarussian brown coals in the fluidized bed. Thermal Engineering. 2014;61:497-502.

23. Robak J, Ignasiak K, Rejdak M. Evaluation of the effects of coal grinding in terms of coal water slurry preparation // E3S Web of Conference. 2016.

24. Glushkov DO, Lyrshchikov SY, Shevyrev SA, et al. Burning properties of slurry based on coal and oil processing waste. Energy&Fuels. 2016;30:3441-3450.

25. Glushkov DO, Kuznetsov GV, Strizhak PA. Simultaneous ignition of several droplets of coal– water slurry containing petrochemicals in oxidizer flow. Fuel Processing Technology. 2016;152:22-33.

26. Glushkov DO, Syrodoy SV, Zhakharevich AV, et al. Ignition of promising coal-water slurry containing petrochemicals: analysis of key aspects. Fuel Processing Technology. 2016;148:224-235.

27. Larionov KB, Zenkov AV, Yankovsky SA, et al. Change of coal-water fuel rheological properties by rotary flows modulation. Proceedings - 2016 11th International Forum on Strategic Technology, IFOST 2016;568-571.

28. Moriyama R, Takeda S, Onozaki M, et al. Upgrading of lowrank coal as coal water slurry and its utilization. International Journal of Coal Preparation and Utilization. 2005;25:193-210.

29. Egorov RI, Zaitsev AS, Salgansky EA. Activation of the fuels with low reactivity using the high- power laser pulses. Energies. 2018;11(11).

30. Hsu TC, Yang SI. Viscosity Effects of Spray Characteristics in Air-Blast Atomizer. Key Engineering Materials. 2015;656:142-147.

31. Yeh YH, Hsu TC, Yang SI. High viscosity fluid spray characteristics in the twin-fluid atomizer. ASPACC 2015 - 10th Asia-Pacific Conference on Combustion. 2015.

32. Galustov VS. Direct-flow spray devices in power system. M: Energoatomizdat, 1989. 240 p.

33. Gvozdyakov DV, Zenkov AV, Gubin VE, et al. On the study of coal-water fuel flow structure during its pneumatic-mechanical atomization. Bulletin of the South Ural State University. Energy series. 2018;18(4):5-13.