Experience with H2S

[hollandhvac]

Hello everybody,

In a job description send to me, there was stated

-Experience in design and operation of high H2S content facilities with stringent requirements in terms of HSE.

Now the only thing I can think of now in the design is H2S sensors in the fresh air intake.

My question is now, what have I missed? is there more to worry about with H2S?

 

[KiwiMace]

Smells like rotten eggs.
Heavier than air, collects in sumps and drains.
Blocks your sense of smell quickly, you get a whiff then nothing, then you pass out and die. Although I cannot speak from personal experience.
Common problem in Pulp and Paper and natural gas industries.

What is the job/industry?

 

[hollandhvac]

The job is an HVAC engineer and the industry is natural gas

 

[SAK9]

Check the following:

Check compatability of H2S with usual HVAC materials like copper,Aluminium(coils),Mild steel (AHU,duct work),Motor class(depending on H2s is flammable or not)

Also check if charcoal filters can block out H2S

 

[TwinScrew]

^^For examples, when I supply equipment up north (Oil Sands, H2S is common place), we typically epoxy-coat (or Heresite coat) the condenser coils, among other things.

 

[stevenw]

Be sure to specify several flag poles around the property with big flags so you know what direction is downwind. (Run upwind). We do that at oil refineries. Don't forget some SCBA packs and OSHA warning signs.

 

[sterl]

HSE is simply Health, Safety, Environmental.

H2S is highly corrosive and reactive; and on exposure to air makes H2SO4 which is sulphuric acid.

Sulphuric acid and any of a variety of metals make a battery. Corrosion plus water flow make nasty sediments. Finned coils turn into shallow mounds of corrosion products.

Close but not contacting metals in an H2S plus Air environment set up electrical differences; add back a little water and you get currents, high locallized corrosion near brackets, hangers, etc.

Brush the charged metals or bridge them and you get arcs...

Arcs in an air-NG mix go BOOM.

 

[runMIPR]

Ok. A small pet peave of mine is the oversimplification of H2S chemistry and bad grammar. The last post contains both.

1) H2S does not react with air (N2, O2) to generate sulfuric acid. It reacts with water (H2O) to form sulfuric acid. It combines with water in the air and forms acidic condensation or acid rain. H2S will react with carbon steel directly and cause corrosion but it will have to be high levels (>10,000 ppm) that people in the area will be severely injured if not killed by the exposure.

2) A simple ARC explosion in a natural gas environment requires that the air composition be an explosive mixture. Most natural gas leaks, thankfully, will cause a non-explosive mixture to form as they will remove oxygen away from the area of the leak by pressure. In other words, the atmosphere is too rich. The danger is at the edge of the plume where oxygen and natural gas are mixed and can be ignited by arcs, combustible solids (FeS), open flames and even the composition itself (auto-ignition). Very often, natural gas facilities have gas and flame detectors to cause an ESD (Emergency Shut-Down) if any of these conditions are even close to being met.

I'll get off my soap box now.

 

[dcfrush]

Is H2S the product or a by-product? In a refinery if there is a sulfur recovery unit there can be large amounts of H2S generated, which can be used in other areas of the refinery for different processes or the elemental hydrogen and sulfur can be separated for other uses. It's also a nasty by-product elsewhere and wherever you get concentrations of H2s >500 ppm, temperatures under 300 degF, and any amount of water you get the potential for environmental cracking.

Not really sure what H2S has to do with HVAC though, let me know if I can be of further assistance.

Good luck.