Steam Pressure Vs Compressed Air

[GlassMann]

I'm using "waste oil" to fire a glass furnace. It's been working great for almost 2 years. It requires compressed air to atomize the oil. I have been using a continuous duty small compressor, 1/3hp. I'd like to simplify the system and use the exhaust heat to produce steam for atomizing the oil. If anyone has any simple helpful advice about rigging up a "steam machine" that produces 2cfm at 20psi I'd appreciate it.

Thanks,
Glenn

 

[a31ford]

Well, Glass Mann, I know the real steam guys in here, won't want to reply to this, simply because steam can be one Dangerous item! BUT, I know where you are coming from.

2cfm @20psi not a lot really, BUT safety would be my first concern, so a pressure "pop off" would be first, BUT make sure that it dumps to some form of container (vented to air) that can hold the entire contents of your "generator" because if it goes, count on everything getting spewed... Second thing, how would you extract the heat to boil the water? A small thick plate cold steel container in the heat circuit? (NOTE: this could be a potential "bomb" if not designed be an engineer!!) The pressure release would have to sit some where in the circuit, and then feed water automated, to replenish the whole thing. I don't know, sounds really complex, to save a few dollars on elec. for the compressor.... OK, I can see a manual replenish thing (hand valve), BUT, what if it runs dry?? Would your oil supply, un-atomized become a problem???? Would this cause a run away fire at the furnace end????? What about using the original compressed air as a backup? Say, a pair of regulators (remember the one has to work in steam) and if the steam quits, the compressed air takes over...

The more I speak about this, the more I realize I better quit, it's getting way to complex....

G.

 

[logoslarry]

Lets see now. Unless you have a boiler in place you'll have to buy or build one. Which means it must comply with the regs and codes. It will require safety valves, shutoffs, secure clean water supply, piping, pumps, fuel supply which could be waste heat, plus, depending on the boiler rating, a qualified person to run it. Basically you'd have to redesign almost your entire plant. Which is certainly possible. If, on the other hand, all you want to do is recover some if the heat going up the stack. Install a heat exchanger in the flue and heat up the water that way. Still needs safeties and a means of cleaning the coil such as soot blowers. That way you're only redesigning part of your plant.
Best advice is if it works don't fix it. Stick with the air compressor.

 

[GlassMann]

Thanks for the responses. I know where you are coming from by saying "don't fix what's not broke". I was just hoping to figure out a way to make the system less dependent on electricity. The burner has to run 24/7 so I have a battery backup to keep it going during black-outs. If the air flow stops for even a few seconds the nozzel's o-ring will melt which causes the oil flow to cease and then only cold air is blown into the furnace, which needless to say is hell on the refrectories. I chose the battery backup over an auto-start generator because it was much less expensive.

Glenn

 

[logoslarry]

A reservoir for pressure does make sense...
I suppose, if worse comes to worse, Glassmann could always go back to the pre-electrical system. Someone pumping a bellows. Actually if he has a stream with sufficient head or steady wind he could set up a mill expressly for that purpose. But I don't think he really wants to go that far. Personally I think he'd be better off going the emergency generator route. With sufficient fuel and proper sizing it would be more than adequate, especially if a blackout lasts more than a day or two.

 

[TD2K]

That could be a big reservoir depending on how high he wants to store the compressed air for backup versus what minimum pressure he can accept (the pressure change sets how much air the vessel will supply).

There's a lot less compressed air available in even a big reservoir than you might initially think, especially for more than a few minutes operation.

 

[GlassMann]

I think for increased back-up time I'll just add more batteries. I started with only one (deep cell, trollng motor type) and it only gave me 20 minutes. When I added another battery I got 1:20. I can add as many additional batteries as I need, up to 10 or 12 I think. Ten batteries would probably give me days of back-up, I don't know the formula though. The bummer is all of the batteries need to be the same age, so I can't just add more without replacing the 2 that I'm currently using. There always seems to be a "catch"!

Thanks Guys,
Glenn