NUMERICAL MODELLING OF INFLUENCE DEGREE OF TURBULENCE IN THE COMBUSTION CHAMBER
Askarova A.S1 , Bolegenova S.A2 , Bekmukhamet A2 , Maximov V.Yu2
1Al-Farabi Kazakh National University 1, Almaty, Kazakhstan,
2Al-Farabi Kazakh National University 2, Almaty,Kazakhstan
e-mail addresses: firstname.lastname@example.org
The urgency of the given problem and growing attention it relate to the work of existing power plants, the creation of new combustion chambers, with increase in quantity of the polluting substances entering in atmosphere.
Investigated object in the given work the combustion chamber of copper RK 39. The block 300 МВТ, steam capacity 475 T/hour is chosen. The copper is established on Aqsw power stations (Kazakhstan). The calculation area for carrying out computational experiments and creation of a database for modelling with useful programme in complex PREPROZ. In created files geometrical data of investigated process, initial and boundary conditions for process modelling heat-and-mass transfer in reacting streams contain.
Influence of initial level of turbulence on the basic characteristics of burning process which shown has been investigated, that change of turbulence degree of dust gas a stream essentially affects distribution of the basic characteristics of burning process in top internal space.
We according to investigating that , comparing the obtained data for concentration of CO, СО2, СН4 for two degrees of turbulence Tu=10 and Tu=5. it is possible to draw a conclusion, that increase in degree of turbulence there is maximum hashing of mix and the minimum emission of harmful substances in environment. So for example, on exit concentration CO at degree of turbulence Tu=10 decrease on 52 % in comparison with exit of the same substance at Tu=5 (Value CO on an exit for Tu=10-0,00933 kg/kg, For Tu=5 - 0.00611 kg/kg).
Figure1- Comparison maximum concentration of CO along the combustion chamber for two degrees of turbulence Tu=5 and Tu=10 .
Figure-2. Concentration distribution in the combustion chamber height for the average value at
Tu = 5 and at Tu = 10 for CO2
It is visible, that maxima of concentration of carbonic oxide are reached in the centre of the top internal chamber, in area where the core gasification. according to an approach measure to exit CO takes place reacts with oxygen and occurs after combustion to CO2. Concentration value CO on exit from top internal space essentially decrease.
Figure-3. The temperature distribution on the Figure-4. The temperature distribution on the
height of the combustion chamber at Tu =5 height of the combustion chamber at Tu =10
From the diagram in Fig. 1-2 shows the concentration distribution of the height of the combustion chamber, depending on the gas (CO, CO2) at different values of turbulence Tu= 5 and at Tu = 10. From graphs we realized than more turbulence the less ejection harmful substances and better affects for complete combustion.
From the diagram in Fig. 3-4 distribution of temperature for various gases (CO, CO2, CH4, coke, etc.) in height in the combustion chamber differs slightly.
1. Askarova A.S., Heierle Ye., Leithner R., Müller H.CFD simulationen der NOx production in Kohlenstaub-befeuerten Brennkammern. VDI-Berichte 2056, VDI Verlag GmbH, Düsseldorf, 2009, S.575-579.
2. Askarova A.S., Lavrichsheva Y. Use of 3D-CFD tool FLOREAN to model overfire air technology in coal-fired boilers of Kazakhstan power plants. Mater. VII All-RussianConference "The burning of solid fuels", Novosibirsk, 2009, pp. 111-118