Steam collecting 1

[ch0ban]

Greetings to all, finding this forum was unbelievable hope that some1 helps me solve an annoying thing in my facility

i have a drying oven, with electric heaters, self made, pure improvisation, but does the job most of the times, to dry chemically pre-treated metallic parts. Those parts, steel tubes and elbows, are then dipped in an enamel slip (containing water and powder enamel coating)... in order to BAKE or "fire" the enamel in the enamelling furnace, ALL the water from the metallic object has to be removed, meaning the object has to be 100% dry

My problem: when putting a dozen of objects in my electric drying oven, a giant CLOUD of steam goes out of the metallic objects, you could not believe how much steam such a little object creates. Is there ANY way, ANYYYYY way please to "collect" the steam from the drying oven without taking out the temperature from the chamber? I mean any other solution besides opening up the oven, installing a whole bunch of more electric heaters in order to get the desired temperature to dry the objects??

Help? Please?
Thanx in advance!

 

[Unotec]

You have no means of exhausting the gases?

<<A good friend will bail you out of jail, but a true friend
will be sitting beside you saying ” Damn that was fun!” - Unknown>>

 

[ch0ban]

well no, I have just started the facility, and everything is new stuff to me... I didnt have the money to buy an industrial drying oven so I have to improvise a few more months :S
what kind of solution do you suggest? what to "add" to the chamber? just a "chimney"-like pipe with a roof-like top of the chamber ??? sorry guys for the ignorance, but I have really not been able to find any authority on the subject here in bosnia, not a lot of thermo-processing and enamelling engineers here :S
my chamber is consisted of 5 kWh infrared heaters, all made of inox, and did the job of drying chemically pre-treated tubes, but 100% drying of enamel slip is much more difficult... I can't just add a bunch of heaters, because the enamel slip would then be ruined, if it gets to a 300 or so celsius temperature before the firing in the main furnace :S dont know what to do.......

 

[Unotec]

I am not sure about your processing particulars. But would pre-heating the material to eliminate the moisture prior to the cooking be an option? You could use a hot/dry air flow to do so.
As for a 'chimney', yes, but you require air intake and you will be loosing heat, so the need of a heat balance becomes more important now.
You will have to be careful you do not displace too much air, just enough to empty the steam before it comes into contact with your parts.

<<A good friend will bail you out of jail, but a true friend
will be sitting beside you saying ” Damn that was fun!” - Unknown>>

 

[ch0ban]

you are absolutelly right, displacing just enough air to empty the steam, because a lot of steam in the chamber ruins the enamel slip on the object surface, sticks on the metal surface and while flowing onto it it removes pieces of enamel off the surface
i thought there was another solution, i saw somewhere people use "steam traps", i dont know how it works but it removes all the steam from the chamber top? not a chimney definatelly, some other technique :S

 

[Unotec]

The steam traps I am familiar with are on steam lines. Basically they stop the flow of steam until it gives all the heat and condenses, allowing the condensate to return to the boiler.
In your case, steam will always be at the top, therefore, if you can create a laminar flow at the top, the steam will be displaced. Hot air enters in one side of the chamber, hot steam/air leaves on the other side.
Are your heaters at the top? How big is your unit? What is the configuration of your unit?
There are too many unknowns to be able to give a more concrete answer. These are all just ideas.

<<A good friend will bail you out of jail, but a true friend
will be sitting beside you saying ” Damn that was fun!” - Unknown>>

 

[ch0ban]

dimension of the chamber:
1,2m height x 1m width and depth
outside isolation done
everything made with stainless steel
on two sides are infrared heaters with the total output of 5kWh
the bottom has no heaters, also isolated in the walls
two doors on the top of the chamber, also with isolation in the walls, and all the objects are put from the top down into the chamber

judging by what you have said my main problem seems to be not having any ways of the air to come from the bottom so the steam could go out to the top through a chimney
i dont know if there is any way, book, person or document that describes how many kWh of infrared heaters would I have to install in this 1,2 cubic of chamber to have 100 celsius inside, and how "big" should the air in/out openings be to maintain 100 degrees celsius

 

[Unotec]

You're talking heat and mass transfer. Any text book on that will have very similar problems in it and all the theory you require.
Your biggest challenge is to determine how much airflow you will require as a minimum to effectively remove the steam.
However, if you open a vent in the top doors, one you can close once the steam has come out, you can rely on the steam making it out through vents on its own due to buoyancy.
In any event, if steam is too much of a problem, you need to evacuate it through some sort of venting system.

<<A good friend will bail you out of jail, but a true friend
will be sitting beside you saying ” Damn that was fun!” - Unknown>>

 

[steamdog]

How about a vent condenser? Using city water you could condense the steam in an upper portion of the chamber and maybe not even have much a vent that would loose the heat.

 

[ch0ban]

man THIS is what I'm talking about!!!! thanx a lot man, will do try an get one of these!

 

[IRstuff]

Based on your other posting, your problem may not be the condensation of the steam, but simply, the amount of air flow you have impinging on the work pieces.

You mention "cloud" of steam. That suggests that the air is moving so slow that you can actually see the "cloud." Assuming a linear flow of air through your chamber, 4 exchanges per hour works out to 1.3 mm/s, which is literally a snail's pace. I think that your air flow needs to be at least 1 part length/second, say more like 50 mm/s.

TTFN

FAQ731-376