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May 30, 2012, 05:34 |
Coal gasification: reactions not working
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#1 |
New Member
rabbahs
Join Date: Aug 2010
Posts: 11
Rep Power: 15 |
Dear all, First of all thanks for reading the thread, I really appreciate it. I am trying to model coal gasification process in fluent using the species transport. The step that I follow to perform the analysis are given below. The parameters that are not mentioned are taken by default. I am only performing this exercise to see the potential of species transport for the coal gasification, but at the end of the day the simulation was not working ... yyyyyyyyyyyyyyyyyy ... I don’t have any clue Anyway, the steps are given below, 1) Import the mesh file in Ansys Fluent 12.1.4. The geometry is a 2D rectangle (10m by 1m), have a nozzle in the center and an end face as outlet. (fairly simple geometry) 2) Define>model>energy equation> ON 3) Define>model>viscous model>K-epsilon 4)define>model>species model>species transport. 5) under species transport, the volumetric and particle surface reaction are unabled. 6) similary, finate rate/eddy dissipation model is selected. 7) species mode> coal calculator> default values selected that generate a mixture material “coal-volatiles air”. 8) now in the material panel: material are selected and edited for mixture so that it contain “vol, o2, h2, co and n2” in the fluid speices and “C<s>” in the solid species. 9) now the two reaction are defined as, a) volumetric reaction vol + 0.885 o2 = 1.898 co + 2.381 h2 + 0.017 n2 b) particle surface c<s> + 0.5 o2 = co2 10) define injection >new Injection type>surface> “NOZZLE surface” b) Particle type>combusting c) Custom law> ticked d) Temp>450, velocity>5 m/s, flow rate>0.1 kg/s 11) Material>combusting particle>combustion model> “multiple surface reaction” is selected. 12) Define>boundary condition>nozzle (velocity inlet)> velocity =10 m/s, species > o2 mole fraction =0.21, temperature=450 13) Initialized and run for couple of thousand iterations. The only check I have that I check the temperature contours. Because if reactions are working than the temperature should go up. Remember, the temperature I am putting for air inlet and injecting particle are above the devolatalization temperature. But I never get any reaction happening and maximum temperature remain the same as inlet conditions Any comments and suggestions are welcome. At this point I can try anything because the grid is fairly small so it will not take any time. If anything is unclear then just shoot a question. Thanks |
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Tags |
coal gasificaton, finite/eddy, species transport |
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