STEAM+TEMPERATURE+PRESSURE=Head ache...

[SHvanBommel]

How would one (me) go about figuring out the approximate temperature of steam in a system that has water say at 170(F) with a head of 15PSI?
I'm so lost... yet so... really lost...
Thanks in advance...

 

[Special Hops]

I don't get what you are tying to say. If the system is 170 deg and then steam is 170.

 

[SHvanBommel]

I think steam is actually at a higher temp because it is under pressure...
or rather because it is under pressure it has a higher temp. potential when it is released...

 

[Special Hops]

To get Steam at 15 psi (which is 30 absolute) you would need 250deg F.

At 170F to get steam - you would have to be in a vacuum.

 

[SHvanBommel]

ok, so with 250deg water and 15psi of steam, what is the temp of the steam out?
according to a few other tables i've looked at it lookst like you build 15psi at 215(F) and 29.84PSI at 250...

 

[Brew-Happy]

ok, so with 250deg water and 15psi of steam, what is the temp of the steam out?

If you are talking about a closed pressurized system, the temps should be at equilibrium, therefore the water and steam would be at 250F. Is this what you are asking, or are you talking about the temp of the steam as it immediately exits the system and drops in pressure?

 

[SHvanBommel]

Thanks! lets assume that we are running the steam out the top of the the S/G (12QT pressure cooker) into a cylinder (insulated) and within that cylinder there is a copper hose that is runing oh i dunno... mash... because the mash is at a lower temp (wow... 250F mash...) would that not cause the steam to lower in pressure and recirc back into the s/g (the cylinder would be above the s/g so any condensation or cooler temp steam would drop back in the the bottom of the s/g (input)) so you would have an input and output port on the cylinder and an input and output port on the s/g and i would assume that the water level would equalize in part o fthe output pipe from the cylinder with the level of the S/G but still maintain itself as say... a condensation chamber...

 

[LooyvilleLarry]

So basically you are talking about using a steam powered HERMS ? Where the recirculating wort is mixed with steam ( in a diffusion chamber )as necessary to control the temp of the mash?

 

[Special Hops]

You confuse me. A diagram might help exlpain what you are trying to do.

 

[SHvanBommel]

ok sorry.. at work... so the blue bit is water, there should be steam on top, the "pipe" on top sends the steam *there will be a valve there* through to the cylinder on the left, the coilse are actually attached to the output of the pump (attached to the mlt etc.) the copper coil sends the fluid through the cylinder (exchanging the heat with the wort as its being recirc'd) and so on and so forth no the steam cylinder is above the pot because the lower temp steam/condensate would have to travel back to the pot to be converted to steam again.. does this clarify?

 

[Brew-Happy]

If I am understanding correctly, you want to use the heat from the steam to heat your wort.

Not bashing your idea:

One problem I see is the pressure difference between the top and the bottom of the closed system. I don't know if there is enough difference to create the flow you are looking.

2nd problem is that the heat transfer from the steam to the wort will be low since you are transferring from a gas to a liquid state. Related to that, is the problem of the steam cooling back down and reverting to a liquid, which would try to flow back down your tube, taking with it any heat that you can use.

One suggestion would be getting a pump that can handle the heat (March pump I would guess) and circulate the hyper heated water from the bottom of the pot back around to the top of the pot. The transfer would be better from one liquid to another. I know this adds some expense, but I think it work more efficiently.

Great idea tho. Please correct me if my assumptions are wrong here.

 

[Timekiller]

ok, so with 250deg water and 15psi of steam, what is the temp of the steam out?
according to a few other tables i've looked at it lookst like you build 15psi at 215(F) and 29.84PSI at 250...

Yes, @15psi - 215.. remember that 15psi is absolute. 1 atmophere is 14.7psi. so in your brewing [email protected] is no vaccum/pressure.

So @29.84psi or 15.14psi above atmospheric press. is 250*

Steam/water will be the same temp. What would be best is to determine the heat output (ex. btu's) of steam @ 250* and what input you need.

 

[SHvanBommel]

your assumptions are correct, nothing wrong with being a little sensible.. what about if i were to scrap the heat exchanger and go directly into the steamer?so rather then having the coil exchanger, I put the exchanger in the... oh wait... thats a herms... ultimately thats what i want to do i think...

 

[jds]

Here's a link to an online steam table calculator:

eFunda: Saturated Steam Tables

This assumes saturated steam (ie no superheat), and appears to be working from absolute pressure (psia) as opposed to gauge pressure (psig). 15 psig is about 30 psia (at sea level, anyhow).

If I remember my elementary thermodynamics, you'll be releasing about 945 btu per pound of steam you release into the mash. Thermo geeks: Do I have this right?

[edit]^^^^^
ignore this last bit, you're not releasing steam into the mash directly. You should still be releasing 945 BTU/lb of condensate, but you'd need to know the condensation rate to know how much heat you'd need to supply to the boiler to keep this system working.

Also, please, for your own sake: If you don't have a safety valve in this system, get one. Steam carries a MASSIVE amount of energy, and steam explosions are seriously bad news. See, it's not so much the actual temperature of the steam, but the enthalpy. It takes a lot of energy to make the (l) -> (g) phase change. You get that energy back when you condense the steam, and that's what gives steam heating its power.

Example: Suppose you have steam at 212 F and condense it to water at 212 F. You're not getting a temperature change on condensation, but you'll still release about 897 BTU/lb.

In other words, you don't need to get the system temperature up much above boiling to still be able to transfer a lot of energy to the condenser.

I have personally seen the results of leaks of large quantities of steam superheated to 450F. It ain't pretty. This stuff can be dangerous, so proceed with caution.

 

[SHvanBommel]

the safety valve to me would be the one built into the lid, I agree that steam would be bad... bad... news.. if well, lets not think about that....

 

[SHvanBommel]

ok, next question.. lets say that i go with the HERMS idea... would JB weld be sealent enough to seal the fittings in place (Compression fittings) and be able to maintain pressure? would there be any adverse effects on the jb weld with heat/pressure?

 

[kladue]

Great idea but steam heating of liquid is a lot of fun because the time lag between applying steam and seeing a temperature change is large enough that when the temperature target is met there is still steam in chamber that continues to condense and raise temperature.

 

[SHvanBommel]

so then would it be safer to go with a HERMS?

 

[jds]

Here's a thread with another good idea on using steam heating:
https://www.homebrewtalk.com/f51/easy-steam-infusion-mash-system-25974/

Very little additional equipment setup, and, from what I remember, a very controllable and safe process.

 

[SHvanBommel]

yeah that's where I got the idea...

this is what i have to deal with righ tnow though... yes, the kettle is on TWO burners... blaaaa.... I don't know why that just popped into my head, I have a Candy Stove (industrial single burner) but no deck and the whole ventilation thing..... :-\ I dunno, maybe i'll try that this weekend... try and burn my apartment down...

 

[Special Hops]

What you really need to make this system work is a steam trap. A steam trap keeps the steam in the coil but let's the condensate though.

 

[Special Hops]

The real advantage of steam is that it releases a ton of energy when it condenses. So you want the steam to stay around the coil and only get rid of the condensation that forms.

 

[Special Hops]

This condensation you can then just pipe into an open (to atmosphere) drain. Just piping it back to the pressure cooker will not do a thing because it will not move from the lower pressure (coil) to the higher pressure (pressure cooker) on it's own.

 

[SHvanBommel]

its funny.. when I was qualifying for my dolphins (SS) I had to learn about how our nuclear reactor worked... so say something like a "condensate bay" would work? say underneath the coil? in a separate chamber... recirculate cold water maybe?

 

[Special Hops]

This is what you want. The "T" is the steam trap.

 

[Special Hops]

Steam trap is just a little device that opens and closes based on temperature. When there is steam on it is hot and it keeps closed so the steam stays on the coil. As condensate forms, it goes and and hits the trap. The condensate is cooler and the trap opens, allowing the condensate to exit to drain. As soon as the condensate is gone, the steam heats the trap up and it closes.

 

[SHvanBommel]

so where would i find such a device?

 

[Special Hops]

Industrial supply shop. You could try Mcmaster-Carr. Not sure how much one costs.

 

[Timekiller]

there is a few on ebay too!

 

[SHvanBommel]

inverted bucket steam trap.. i think is what I want... sexy piece of gear....