Steam regulation

[Bolverk]

Howdy all,

Ok steam gurus, got a question..

When using low pressure steam to heat a reboiler where do you put the control valve, on the steam side or condensate side?

I feel like if i put the valve on the steam side it will just blow past the restriction, where as if I put it on the condensate side you'd get a little back pressure to push the water along... but I'm 100% guessing here.

Any info would be appreciated.
Thanks in advance,

[zach]

I'm not sure how your reboiler is configured, but on an industrial setting there would be valves at both inlet and outlet of the heat exchanger. The inlet steam valve controls the temperature of the process fluid, and the outlet has a condensate drainer that allows the liquid to drain to atmospheric pressure and keeps heat exchanger free of liquid.

If you have no other loads on your steam generator maybe you don't need a control valve on the inlet and just modulate the boiler input energy.

The outlet might be drained through a water trap the distance equal to the pressure you want to maintain.

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[Bolverk]

Thank you! That makes sense!

[Wildcats]

I don't know much about steam distilling. But thanks to this thread, I've been reading all about it for the last two hours! Thanks!!

[Bolverk]

I don't know much about steam distilling. But thanks to this thread, I've been reading all about it for the last two hours! Thanks!!

Yeah man, it's another whole ass rabbit hole to down

[acfixer69]

Howdy all,

Ok steam gurus, got a question..

When using low pressure steam to heat a reboiler where do you put the control valve, on the steam side or condensate side?

I feel like if i put the valve on the steam side it will just blow past the restriction, where as if I put it on the condensate side you'd get a little back pressure to push the water along... but I'm 100% guessing here.

Any info would be appreciated.
Thanks in advance,

As I read this question it sound like you don't have the knowledge to safely attempt this steam project andsteam and valves are a major concern.

[Bolverk]

As I read this question it sound like you don't have the knowledge to safely attempt this steam project andsteam and valves are a major concern.

Delete the post if you feel its unsafe. I don't know what else to say...

[acfixer69]

As I read this question it sound like you don't have the knowledge to safely attempt this steam project andsteam and valves are a major concern.

Delete the post if you feel its unsafe. I don't know what else to say...

No need to delete it at this time. I do have a concern with the difference between open and close systems being confused. Diagram above is for closed with condensate return.

[Bolverk]

No need to delete it at this time. I do have a concern with the difference between open and close systems being confused. Diagram above is for closed with condensate return.

My idea is a open system with two outputs
one leg is open to atmosphere, the other would run through a heat exchanger with the condensate running back to the open boiler.

There is no risk closing off the main output and causing any over pressure situation. Worst thing that would happen is that I don't have enough heat where I want it.

[acfixer69]

No need to delete it at this time. I do have a concern with the difference between open and close systems being confused. Diagram above is for closed with condensate return.

My idea is a open system with two outputs
one leg is open to atmosphere, the other would run through a heat exchanger with the condensate running back to the open boiler.

There is no risk closing off the main output and causing any over pressure situation. Worst thing that would happen is that I don't have enough heat where I want it.

With a steam trap and condensate return pump the system is closed, and not what a home distillation system would typically be.

[Bolverk]

With a steam trap and condensate return pump the system is closed, and not what a home distillation system would typically be.

Not a closed system

[zach]

It looks good except the part you have open should be trapped with a few feet of water to provide the back pressure you need for the heat exchange to prove the capacity needed. The deeper the column the higher the steam condensing pressure and higher saturation temperature.

[Bolverk]

It looks good except the part you have open should be trapped with a few feet of water to provide the back pressure you need for the heat exchange to prove the capacity needed. The deeper the column the higher the steam condensing pressure and higher saturation temperature.

Thanks Zack, yeah it will be, this was just a quick drawing to show it wasn't going to be unsafe.

[GrumbleStill]

Hey Bolverk, I don’t want to be a negative Nancy, but I struggle to see how this design will work. It looks like the steam supply and condensate return are both connected to the boiler, so will be at the same pressure, so nowhere for the steam to flow other than out the vent, without going through the hx. If you want to recycle condensate back to the boiler you’ll need a condensate pump.

For safety’s sake, I’d suggest sketching out your full design and do the maths to estimate the temperatures, pressures and flows you’ll have through the system. Or else use a known design where someone else has done the hard yards. Steam is awesome, but it really is a dangerous beast.

Have fun and stay safe.

[HDNB]

i use prolly the simplest steam system that is possible.

the boiler makes steam (duh) and is modulated through a ball valve, after the heat exchange there is a condensate trap that gravity feeds a reservoir.

from the reservoir, water is pumped (back) to the boiler and has 2 check valves in the feed line, in case one has a small leak back, the other catches it.

the reservoir is open to atmosphere.

there is a 15psi PRV on the steam side

there is a vacuum break after the ball valve to protect the steam jacket

there is a 3 psi / vacuum breaker on the kettle itself.

the system needs to run at a few PSI and rounds out at about 11 psi at tails. without the pressure there is not enough temp delta to do the job in a timely fashion.

the safeties include flame roll out, exhaust block, hi and low water, hi pressure, electric shut down and a holy shit switch on the wall on the way out the door.

[zach]

There is a reason most jurisdictions require an operator's license for steam boiler operation and contractor or engineering license for design. My first post in this thread was an answer to a theoretical question, but as been pointed out is not practical or affordable for this hobby, especially for those who don't fall in the first three categories.

It is possible to feed steam to a heat exchanger with condensate return in a one pipe system if the the piping allows gravity return. This piping needs to be purged of air on start up. Many older heating systems use one pipe radiators. In effect it is like a reflux condenser.

If it's not possible to get the condensate generated in the heat exchanger back to the boiler because of geometry, then a separate water trap can be used to provide back pressure and accumulate condensate. Again air purge valves may be needed to remove non condensable gas. This type of feed is less efficient as condensate does not return to the boiler, and the boiler feed water is at a lower temperature.

[Bolverk]

Zack so if you were returning the condensate back to the boiler would you use a Hartford loop?

[zach]

I've never heard of a Hartford loop, but what shown is a two pipe system which is common way of condensate return.

Yes I would use a two pipe system, If one pipe doesn't work.

[shadylane]

I'm thinking.
Instead of using valves, control the power going into the boiler to regulate the steam pressure.
And also have "the safeties including flame roll out, exhaust block, hi and low water, hi pressure, electric shut down and a holy shit switch on the wall on the way out the door"