Down wind glc calcs of solids from flue gas and Hg

[Flareman]

A client requiring a combustion process provides a mercury (Hg) content as part of the input. If I generate HgO (which I know to be a poison) what do I need to know about down wind glc's.

I normally calculate glc based on Pasquill/Gifford and Briggs plume rise, but HgO will quickly become a solid in the flue gas (particle size unknown to me) and I feel that the standard dispersion coefficients, which I would use for gases, will probably not apply. Are there alternative dispersion models which cover solids and does it depend on particle size? If I were calculating this in a pipeline for example, I'd be using Stokes law.

I'm very uneasy about Hg in the first place so anyone with experience feel free to jump in.

Thanks

David

 

[owg]

I think you may be at the sharp end of technology. Try an email to Mark.Cohen@noaa.gov <Mark.Cohen@noaa.gov>

HAZOP at

http://www.curryhydrocarbons.ca

 

[owg]

Here is a good paper on the species of mercury found in flue gas. It looks like it is Hg, and HgCl2, rather than HgO.

http://www.awma.org/journal/pdfs/2002/8/Meij.pdf

HAZOP at

http://www.curryhydrocarbons.ca

 

[Nkhurd]

Hi,

You will need the particle size and density to model the dispersion of particulates. You will also need the scavenging coefficients to calculate wet and dry deposition rates.

NK

 

[Easel]

The mercury constituents leaving the stack depend on the process chemistry. IF there is combustion and chlorine, the mercury will preferentially go to HgCl2. It can go to HgO but will often leave the stack as vaporous Hg.

EPA work in the Utility Industry shows that HgCl2 is captured relatively easily by a baghouse. The vaporous Hg can be captured with activated carbon.

There are multiple issues surrounding the capture of vaporous Hg. The international issue is that vaporous mercury has a atmospheric lifetime measured in years.

The key is the process, its chemistry and the quantity of mercury being liberated.