[Kummi]

Hello everyone,
Currently, my topic of research is regarding flare gas analysis. The main objective of this study is to identify evaporated gas dispersion scenarios from the flare tower height and highlight the areas where the flammable limit criteria are exceeded on specified location with and without the effects of radiation and recommend the safety action for protection of personnel and equipment if required.


The three dimensional domain is investigated using a commercial CFD tool, ANSYS FLUENT. The flow is assumed to be steady and turbulent. Air and methane gas are used as a fluid mediums. The methane fuel is assumed to be completely evaporated before releasing from the flare tower height.


Boundary conditions and preprocessing setups which are prescribed by industry as follows:
Inlet (Wind velocity) → Logarithmic wind profile (height above ground - 65m and ground roughness - 0.0002m (Water surfaces)) 10m/s @ atmospheric temperature
Inlet (plume mass flow rate) → 7.57kg/s @ 1350K, CO2= 0.095, H2O= 0.19 (stoichiometric ratio)
Outlet → Outflow (Neumann Boundary condition)
k-epsilon realizable turbulence model with effects of gravity
Turbulence chemistry → Eddy dissipation model
Density → Incompressible ideal gas
Radiation → P1 model (Grey model), Absorption coefficient (wsggm domain based)
Pressure-velocity coupling → SIMPLE
Spatial discretization → LSQ cell based, second order upwind schemes


Fig 1: Schematic modeling
Fig 2: Model with boundary conditions
Fig 3: Effect of radiation from plume release point
Fig 4: CO2 and H2O contour plots for with and without radiation cases


My query is all about, the results for with and without radiation cases seems to be identical with no apparent changes (Fig. 4). I have tried my best in all possible ways to figure out the solution but still I didn't get any conclusive result. Certain tips or word of advice to manipulate the appropriate solution will be more helpful.


Thank you ^^
Fig. 1.PNG

Fig. 2.PNG

Fig. 3.jpg

Fig. 4.PNG

[Kummi]

Can someone help me out here ???

[Kummi]

Hello everyone,

Here comes two cases:

1) If the methane fuel is assumed to be completely combusted before releasing from the flare tower tip, there found no effect of radiation in the model
[@ Flare tip, CH4=0, CO2=0.095, H2O=0.19, N2=0.715 @ 1350K] at stoichiometric

2) On the other hand, the presence of methane fuel at the flare tower tip invites the effect of radiation. [@ Flare tip, CH4=0.85, N2=0.15 @ 300K]

1st condition was given for my analysis. Can someone tell me why there is no radiation effect if the methane is completed combusted..

Kindly share your ideas.. Thank you

[Weiqiang Liu]

Hi bro,

is it reasonable that radiation do have obvious effect? because your geometry is kind of big. I think convection of heat is dominant.

weiqiang