Water Saturation

[npf]

All:

Could you help me in determining the amount of water(steam) required for saturating the hot air stream ? This is 100 scfm of air at 265F and 1psig.

Thanks,
sp77

 

[katmar]

265F is above the boiling point for water at 1PSIG. This makes it superheated steam. Even if there was no air present you would not get any moisture precipitating. So you would never be able to saturate air with steam under these conditions - the steam itself is not saturated.

 

[25362]

Saturation could be attained by quenching the hot air stream down to a temperature at which the vapor pressure of water is below the prevailing total pressure of 1 psig.

 

[npf]

All:

Thanks for your comments. But I am looking for some sort of steam injection source where the air stream would be say 70-80% saturated and not fully saturated. Could I be able to determine the quantity of steam to be injected.

Regards,

sp77.

 

[katmar]

sp77,

Because full saturation makes no sense in these conditions, 70-80% saturation makes no sense either.

What is the temperature and pressure of the air before you add in the steam?

What pressure and temperature steam do you have available?

What pressure and temperature do you want the air to be after the steam in injected?

Why do you want to do this? If you explain your application we may be able to see what you are trying to achieve.

 

[25362]

You are probably speaking of moisture content not saturation. Answering katmar's questions, may help you in getting the help you are seeking.

 

[npf]

Katmar:

The availabe steam source is 1000psig (70%)steam. Right now the air stream is at 50scfm ,1psig, 265 F (with no steam addition). This hot air stream has H2S ppms which will pass thru sulfur removal beds and the stream needs to be water saturated for the efficient bed use. So trying to figure out amount of water to be added for saturation??

Regards,

sp77.

 

[25362]

sp77, at what temperature are the H2S-removing beds working ? 40^oC or so ?

 

[npf]

Yes you can say around 40C (100F)

Thanks,

sp77

 

[Montemayor]

In the face of an inept query and absurd data, I've got to interject some comments/questions--

If sp77 is really trying to saturate a heated (265 oF) air stream and assuming this is not an academic exercise or homework problem, why doesn't he do it the way we all would do it in an industrial application: simply sparge the hot air in a pool of cool, clear water? Or better still, spray the cool, clear water into a packed bed, counter-current to the rising hot air? It's called a humidifier.

Spraying hot, high pressure steam into the air is only going to heat even more. Is this a Hot Zinc Oxide Unit Operation?

 

[25362]

sp77.


This means that the air stream must be pre-cooled, besides being moistened.

For moist air at 100^oF the tabulated vapor pressure of water is 0.949 psia. If the total pressure is, say, 15.5 psia, full saturation would be attained with 6.1% water by volume. This is considering air and its humidity an ideal gas when mol%, i.e, volume%, equals partial pressure.

Have you already considered the procedure to be used to cool and humidify your hot air stream ?