Flash boiler

willynilly said:

I try to keep my inbox full, so I dont get PMs What is up man?

When you are heating that .5GPM from 50F to 210F you are getting 664 BTUs per minute, so that is 39,840 BTU/hr heat source (equivilent)

664BTUs per minute / 110F temp rise = 6 pounds of water/min

160F output at that BTU rating: .73 GPM at the afore mentioned BTU output (39.8K BTUs)

664BTUs per minute / 120F temp rise = 5.5 pounds of water/min

170F output at that BTU rating: .66 GPM at the afore mentioned BTU output

That is the mathematical result, your results may vary.

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Just in reference to me trying to follow you around and answer all your questions. I could just tell you all the info in one shot.

At .5GPM my boiler shutters and puts out 212* water. It is boiling in the boiler at that rate of flow.

So I had a thought while studying for a thermodynamics exam a little bit ago

What would be an interesting experiment would be to turn your flash boiler/coil heat exchanger setup into essentially one giant Heat Pipe

You would need to run it at a vacuum essentially, at least at room temperature where the only fluid was water, The thing could be gravity powered and its flow would be self regulated.

like this

That design and theory are good, the problem is the system friction losses require a pump to assist flow.

if you run it on a vapor cycle, you really wouldnt need a pump provided you apply all your heat on a vertical section

The demon in the works is friction, yes if the piping were made large enough to work without auxillary pumping it would be difficult to work with, down sizing the tubing and using a pump reduces cost of materials and size of distribution piping. What you have drawn is an example of steam heating systems with gravity return, research 1 pipe steam heating systems for a simpler design.

Its a bit different than a 1 pipe system as a 1 pipe system has to operate above atmospheric pressure, if something like this was implemented, it would be able to operate far below atmospheric pressure for superior heat transfer at lower temperatures. If the steam generator was of vertical orientation, it would be able to generate ρgz psi where ρ is the density of water in lbm/ft^3, g is the gravitational constant, and z is the change in height across the steam generator assuming a constant water level higher than the steam generator, ideally the fluid level would sit about even with the top of the boiler.

Since it would be operating at the vapor pressure of water, it would always be at its boiling point and allow approximately isentropic heat transfer as the temperature differential would approach 0 which would be the best that can occur without operating a heat pump

Tubing coils aren't very effective moisture separators and you'd end up with a lot of liquid blocking steam flow, and probably develop some dangerous pressures.

diatonic said:

Tubing coils aren't very effective moisture separators and you'd end up with a lot of liquid blocking steam flow, and probably develop some dangerous pressures.

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I was thinking about, that, what You could do is on the exit of the steam generator, run it through a wider section of tubing with a drain back into the feed side, then you are left with only steam exiting.

Plus, if pressures climbed, the temperature would go up and excess heat would be forced back out in the pot anyway. Since the coils in the pot would be colder than those in the burner, the steam would HAVE to flow that way as it would be at a lower pressure than in the boiler. EDIT: as long as there is no air in the system

Mista_Sparkle said:

Plus, if pressures climbed, the temperature would go up and excess heat would be forced back out in the pot anyway. Since the coils in the pot would be colder than those in the burner, the steam would HAVE to flow that way as it would be at a lower pressure than in the boiler. EDIT: as long as there is no air in the system

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Or your household plumbing grade copper experiences a catastrophic failure sending copper shrapnel and steam in to you & your brewing buddies

I ran the boiler today with nothing more then just an outlet. I had 58* inlet water, at a rate of 48oz/min. AKA 3.131lbs/min. I saw a output of 165*. So it would appear that the boiler itself is very efficient in what it does. About 93% efficient. Interesting?


Edit: Its only fair that I say I used the firing rate at 2.5 PSI. Which I/we assume is a pound of propane per hour usage. So, 21,952 BTUs/hr was the rate of burn. Or 365.8667 BTUs/min.

GreenMonti said:

I ran the boiler today with nothing more then just an outlet. I had 58* inlet water, at a rate of 48oz/min. AKA 3.131lbs/min. I saw a output of 165*. So it would appear that the boiler itself is very efficient in what it does. About 93% efficient. Interesting?


Edit: Its only fair that I say I used the firing rate at 2.5 PSI. Which I/we assume is a pound of propane per hour usage. So, 21,952 BTUs/hr was the rate of burn. Or 365.8667 BTUs/min.

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This is a bit off. i should have posted this in the drunk thread.

The 165 output number was a different number. I did have 58* input at a rate of 48oz/min. The output was 156*. That makes the boiler 83% efficient.

The 165* output number was when I was testing to see how much water I could run through it at max fire. I was able to a little over 3/4 of gallon a min. The efficiency went down into the basement on that one. So it would appear that propane is more efficient at a lower pressure like Willy was saying.

GreenMonti said:

This is a bit off. i should have posted this in the drunk thread.

The 165 output number was a different number. I did have 58* input at a rate of 48oz/min. The output was 156*. That makes the boiler 83% efficient.

The 165* output number was when I was testing to see how much water I could run through it at max fire. I was able to a little over 3/4 of gallon a min. The efficiency went down into the basement on that one. So it would appear that propane is more efficient at a lower pressure like Willy was saying.

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Yeah, it is a somewhat linear progression...

I think the issue is one of velocity. As you increase the pressure, and BTUs, you are also blowing those BTUs through that chimney at a much higher velocity, so you are losing a larger % of the heat to ambient.

83% is still pretty darned good, which amounts to 18,400 BTU/hr

It only takes 15,400 BTUs to get 12 gallons boiling from 58F
So at your 18,400 BTU/hr flow rate you could boil that 12 gallons in 50 minutes (if the transfer to the kettle is 100% eff)

That is using 1lb of propane per hour, which is VERY efficient IMHO.

something to keep in mind though is that the efficiency will decrease as the water/steam temp gets higher.

That is quite impressive though

willynilly said:

Yeah, it is a somewhat linear progression...

I think the issue is one of velocity. As you increase the pressure, and BTUs, you are also blowing those BTUs through that chimney at a much higher velocity, so you are losing a larger % of the heat to ambient.

83% is still pretty darned good, which amounts to 18,400 BTU/hr

It only takes 15,400 BTUs to get 12 gallons boiling from 58F
So at your 18,400 BTU/hr flow rate you could boil that 12 gallons in 50 minutes (if the transfer to the kettle is 100% eff)

That is using 1lb of propane per hour, which is VERY efficient IMHO.

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Yea I agree. It would appear though that I will loose the same on the condensing coil. So 17% twice. I believe that a fair estimate would be about 66% all said and done right now. The issue I have right now is I have to heat the water tank with the waste/condensate. So, in essence I am heating up much more liquid then what is in the kettle. I am going to run it again all from a cold start and see how long it takes me to get a boil at the 2.5 PSI firing rate. Once it boils I will take the temp reading of the water tank and note the time.

Mista_Sparkle said:

something to keep in mind though is that the efficiency will decrease as the water/steam temp gets higher.

That is quite impressive though

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Right. The more equal they get I slow down.

What is it? and what's it for ?

For clarification, 2.5 PSI is equaling about 22,000 BTU/hr correct?

willynilly said:

For clarification, 2.5 PSI is equaling about 22,000 BTU/hr correct?

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Yes, my understanding is 1 lb of propane is equal to 21,591 BTU potential.


I did another run and like before I hit the same number of 66% total system efficiency. That was for the first 30 min of run time. I didn't run it any longer.

I'd hate to see your propane bills

diatonic said:

I'd hate to see your propane bills

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I have only bought 3 tanks worth since the boiler was built back in December. I have made two batches of beer, run the boiler tests, and used up the rest on the grill. I still have 30 lbs in my current tank. Not bad. We pay like 13 bucks a fill.

30 pounds in the tank? What size tanks? Mine only holds about 18 pounds total.

willynilly said:

30 pounds in the tank? What size tanks? Mine only holds about 18 pounds total.

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Total weight. Tank plus the gas. Full tanks weigh about 37 lbs.

I should build one of these to make a steam room. Powered via natural gas, naturally. Drool...

do you have a working link of the videos of it in use? i just have a little photobucket square saying the movie has been moved or deleted!cheers,martin

martinworswick said:

do you have a working link of the videos of it in use? i just have a little photobucket square saying the movie has been moved or deleted!cheers,martin

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What would you like to see? I had an issue with my photo bucket account a while back and lost a lot of data. I might be able to re do a video. If I haven't use any of the pieces for something else.

i mainly want to see how you've attached it to your mashtun to deliver the steam,it may be in a picture but i can't see the majority of them!
also,when you were using steam to boil,how did you get the steam to the coil?did you valve the output somewhere?cheers,martin

Here is a shot of the steam mixer built for the second steam injection system https://picasaweb.google.com/kevin.ladue/NewSystemSteamMixer#5156297767550785986. Steam enters through small tube at right, wort through side of right hand tee, mixture leaves out side of left hand tee. After testing the screen was shortened to 1" and the transparent tubing was replaced with stainless tubing for better support for the leaving tubing. The primary principals involved here are high velocity/turbulent flow over screen, and screen provides boundary for steam absorption into the liquid. At high steam flow the sound is a sizzling sound like frying bacon, at low steam flow it is not noticeable.
When you route the boiler flow through the mixer to the mash tun you will not need to move plumbing connections, just adjust fire and water flow for the various modes, strike water, step heating, and fly sparging. Having built the first steam injection system 8 years ago and brewed quite a few beers with it, and tought SWMBO to operate it, it is not difficult to use. Here is a picture of the old steam system https://picasaweb.google.com/kevin.ladue/OldBrewingSystem#5035126853377761794.

ok,that makes sense,sort of like a mini rims tube with the element replaced by steam injection!
originally i pictured the steam being injected directly to the mash via the false bottom or whatever is in your system which is why i thought it must be valved in order to fly sparge.
what is the actual mixer part? is it an off the shelf item?
cheers,martin

The mixer is stainless steel screen wire, 12 wires/inch, rolled over a 1/8" rod and expanded to fit over a 1/4" stainless tube. the screen was then silver soldered to the tube with 56% silver as my welding skills are not anywhere close to GreenMontis, with the correct flux and a butane micro torch, it is not difficult.
This was a scaled copy of the same process used for water heating in sterilizing bottling equipment and starch cooking for paper industry. The steam injection lets you transfer much more heat than is possible with electric RIMS system, but the automatic control is much more complicated and expensive. For a manual control scheme I used a needle valve in the gas supply to the burner, and a needle valve and flow meter for the water flow into boiler. There is no outlet valve in the boiler so pressure developed is a function of plumbing back pressure only, no explosion potential.

martinworswick said:

ok,that makes sense,sort of like a mini rims tube with the element replaced by steam injection!
originally i pictured the steam being injected directly to the mash via the false bottom or whatever is in your system which is why i thought it must be valved in order to fly sparge.
what is the actual mixer part? is it an off the shelf item?
cheers,martin

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No, its not an off the shelf item.
It sounds like you may have it. Kladue is the guy to listen to though. I've only followed in his foot steps. He soldered his screen material, and I welded mine. Believe it or not, for me it was easier to weld then solder. This is a pic of the two I have on hand for my build.