7 replies to this topic

[WilliamN]

Dear peers,

I try to estimate the temperature at ground level from a flare. This would give me an idea what temperature the nearby equipment sees. I really appreciate your help if you could let me know which procedure I need follow or which software has this feature.

 

Thanks.

[Sathya R]

we use Flaresim.

[cmp74]

You have to use Kutuzowski and Sommers (name may not be accurately printed here) method , which is given in API 521 alongwith your gas composition.

One major factors affecting the radiation profile is wind speed and velocity.

 

Best thing would be to ask the tip vendor for such type of calculations as they have more detailed models of their tips.

[WilliamN]

I have read API 521 flare part, by Sommers, etc. This method calculates heat intensity, like Btu/hr/ft2. I have a need for temperature at certain height. For example, I have a flare with duty 100 MMBtu/hr, stack height 60 feet. I need estimate what’s the temperature at the ground level.  Thanks.

[PingPong]

Temperature will depend on absorption coefficient (absorptivity) of the specific object.

 

Different objects will get different temperatures when placed near your flare stack.

 

It is similar to solar radiation whereby a black object will get much hotter than a white object next to it, although they receive exactly the same solar radiation.

[WilliamN]

Thanks for the response from PingPong. Since We have heat flux calculation equations from API 521, can we compare the calculated heat flux against the max allowed heat flux for the material? For example, above the maximum allowed heat flux, the material starts to melt, or soften, or deform, etc. Now the question is  “ Is the allowed heat flux  a property for a material?”. For example, what’s the allowed heat flux for PVC? What’s the allowed heat flux for aluminum? etc, before they soften?  If this works, we don’t need convert from heat flux to temperature.

 

Appreciate anyone in our community shares his/her experiences with  us. Thanks.

[PingPong]

There is no such thing as an "allowable heat flux" for PVC, or aluminium, or whatever.

They soften due to temperature, irrespective of what causes that temperature.

 

The temperature that an object will get near a flare is the equilibrium temperature, whereby the energy loss of the object, due to convection to air plus its own radiation (depending on its emissivity), is equal to the energy gain due to radiation of sun plus flare.

[S.AHMAD]

1. Normally our concerns is the heat flux as this figure shows whether we are safe or not at the ground level.

2. However, you can convert to temperature if you have the mass of the object, specific heat and emissivity (equal 1 for black body).

3. You need to assume the equilibrium temperature and determine the heat loss to surrounding (you need ambient temperature as well). Equate this heat loss with the heat flux. Yes... you also need to know the effective surface area of the object.

4. The heat transfer coefficient shall depend on the type of object. A circular object has difference equation from a flat object.

5. It shall be interesting if you can share you findings. You will be the first person to do it (CONGRATULATION)

Edited by S.AHMAD, 13 December 2013 - 02:04 AM.