Increasing Flash Boiler Efficiency

[Trouble-Brewing]

So after stumbling across a few threads on here and finding some home depot gift cards in an old pile of stuff I decided to make a flash boiler. I am running 2 20' 3/8" copper coils inside of a 6" aluminum tube, some brass fittings and high temperature hose. I am using a hurricane burner running the cold water in from the top, down the coils and then straight back out the top with a valve on the hot end to regulate flow. I made a forced siphon using a carboy cap, a broken racking cane, a valve off of an old bike inner tube, a bike pump and some hose all sealed to the carboy with a strip of inner tube.

I am heating tap water at about about 60* to about 120* consistently but am hopping to get it to 160* or more if possible. Any suggestions to boost the efficiency would be great. Thanks

Pictures of the setup:

 

[Mista_Sparkle]

lower your water flow rate.

maybe pack some extra course steel wool in there, careful though, it may catch on fire, this is just a thought, it may not work at all. What you need though is turbulent flow, your coil looks too pretty, i would think the steel wool would break that up.if nothing else, block off that open center column so more of your heat needs to flow past the coils.

take a look at green monti's build, its pretty epic

 

[Trouble-Brewing]

I have been running it at about 1/3 of a gallon a min so its going pretty slow, any slower and gets shakey from the steam sputtering (I will be solid mounting it to my brew stand soon so that won't be a problem). What do you mean by turbulent flow? More obstructions for the hot gasses as they exit? I have been reading green monti's build, it was actually the original motivation to make my own

 

[kladue]

A couple suggestions, drop a dowel down center and try to spread the coils to cover as much area inside tube as possible, second is water from bottom up. The water from bottom up is not as efficient but the air that seperates from the water as it heats will block flow and give you the surging and popping sounds you are having. The more the gasses have to go around the tubing the greater the heat transfer, a single chimney up the center lets the heat out too fast. Also trim the air into the burner down to where flame tips turn yellow, this reduces hot gas flow through the boiler and gives it more time for heat exchange.

 

[Trouble-Brewing]

I will try dropping something down the middle and see if that helps. Would a lid of some sort help too? I was running water from the bottom up but read something on here that said for single coils, or rigs without a center manifold, it was more efficient to run it the top down. I will switch it back around and see what happens. If it was solid mounted and the popping was not an issue which way would you run the water? I will mess with the flame too. Thanks for the help I will let you know how it goes.

 

[kladue]

With a rod down the center to hold the coils together, try bending the individual coils so more of the inside of the tube is criss-crossed with tubing and fewer large gaps are left. Bottom up flow get you around the dissolved air problem with this type of boiler.

 

[Trouble-Brewing]

Alright I will see what I can do, I should have some time this weekend. Thanks for the help!

 

[GreenMonti]

Here is a couple of pics of mine. I am able to get 52* inlet water to 212* outlet at .5 GPM. The boiler shutters/shimmies and shakes during this setting. It is going in and out of steam mode. At a rate of .75 GPM I can get an output of 163*. It shimmies and moans at this rate, but I get what I want. I built mine out of 1/4" tubing. The dowel that Kladue is in reference too, would be my water inlet to the bottom. I did add a 10' coil around my 1/4" coils to give me a pre-heat coil before my water gets to the business end.

This is when I first built mine. I was only able to get the water too 137* from 50* at the .5 GPM.

Here is the preheat coil I added. This gave me an extra boost. So, I have 4 12' 1/4" copper coils and a 10' 1/2" outer coil for the preheat.

 

[eriktlupus]

if i read your op right please move your valve to the in side of your boiler. by having it on the outflow side it can create a steam bomb from pressure buildup, with it on the in-flow the excess pressure from steam conversion will just come out the drain side.

 

[GreenMonti]

if i read your op right please move your valve to the in side of your boiler. by having it on the outflow side it can create a steam bomb from pressure buildup, with it on the in-flow the excess pressure from steam conversion will just come out the drain side.

+1

I read that and I forgot to mention it. Things happen almost instantly inside a flash boiler.

 

[Trouble-Brewing]

I posted up a reply on Sunday but it doesn't look like it worked. Oh well, I switched the flow to bottom up and put the valve on the input side (so I won't blow myself up). I have not had time to mess with the coils or mount it yet but I should have time this week.

I am a noob to flash boilers and didn't know that shimmying, popping and shaking was normal, so I will do another test when the modifications are all done. If it isn't getting hot enough I will add a preheating coil.

Thanks again for all of the advice, I really appreciate it

 

[eriktlupus]

if you were only getting to 120-130 then the shimmy/shake was from your boiler water flashing to steam and back repeatedly as it passed over hot spots in your system.

 

[GreenMonti]

Looking at your opening pictures again. I see you have the flow split and going down each coil as if they were different heating coils. I would hook them together as one unit. One inlet and one outlet.

 

[Trouble-Brewing]

Looking at your opening pictures again. I see you have the flow split and going down each coil as if they were different heating coils. I would hook them together as one unit. One inlet and one outlet.

I have no way to solder or weld the two together, otherwise I would. I wish I could, and when I get a propane torch I plan on doing so. I have many projects that a torch would be helpful in but do not have the funds right now to get one

 

[GreenMonti]

I have no way to solder or weld the two together, otherwise I would. I wish I could, and when I get a propane torch I plan on doing so. I have many projects that a torch would be helpful in but do not have the funds right now to get one

I am not sure if you have read this one or not, but here is the link to my build.
https://www.homebrewtalk.com/f51/flash-boiler-153116/


PM sent.

 

[Douglefish]

I would love to build one of these, but I can't weld? What other options do I have to connect the 1/4 Inch copper to the larger inlet and outlet pipes?

Thanks in advance?

 

[GreenMonti]

I would love to build one of these, but I can't weld? What other options do I have to connect the 1/4 Inch copper to the larger inlet and outlet pipes?

Thanks in advance?

I silver brazed my upper connections. I wouldn't use solder.

 

[eriktlupus]

hey aaron,

if your unable to braze(a little harder material than solder and hence takes a hotter torch) then assemble the setup and see if you can get a metal shop to braze it for you. most box stores sell a brazing kit for about 40 bones nowadays. i'm lucky in that i have a full metal shop at work and a friend in said shop that will do 'government' work for homebrew.

 

[Trouble-Brewing]

I would love to build one of these, but I can't weld? What other options do I have to connect the 1/4 Inch copper to the larger inlet and outlet pipes?

Thanks in advance?

I would get a 50' piece of 3/8" copper tube (they run about $60 at home depot) a 10' piece of 3/8" braided pvc tubing like I am using, some hose clamps, a ball valve, and a piece of metal tube with about a 6" to 8" diameter. Bent the tube into a crazy coil which probably wont be pretty, I know mine isn't, and hose clamp the pvc tube and the valve on there and call it good. You could probably do it for about $100 if you have burner, a screwdriver and some time. You could do it with 1/4" too and it might be a little cheaper but I think with 50' you will be able to get enough heat with 3/8" to justify the cost and the added flow rate.


I had some time to work on the boiler tonight, I connected the 2 coils with a compression fitting and reworked the coils a little to take up some of the dead space. I still plan on putting a capped tube down the middle of the coils to send the hot gasses around it to the heating tubes. With any luck my apartments power supply will allow my welder to make some tabs to my brew stand this weekend so it will be solid mounted and sputtering won't be a problem. So if all that goes as planed I should be able to run another test this weekend

 

[Douglefish]

Trouble-Brewing,
So you only have 1 in and then 1 out? Are you able to generate steam with this? The flash boiler that I've been looking at on other threads has 4, 1/4" smaller tubes tied into 1 larger water feed. Does this help with steam production or is it to increase throughput?

 

[Trouble-Brewing]

Yeah it is just one in and one out now. If i could weld copper or stainless or braze I would have made a 4 coil one, but I can't. The whole project was kind of an experiment, not sure if it will produce steam but I don't think it will. I think the four to one is to increase the quantity of water through the boiler, not sure though I am new to these things.

I have not had time to test it yet due to rain but it is solid mounted to my brew stand now. I have to figure out a way to make a removable burner mount so it will stay on a cinder block for now. If it stops raining for a little tomorrow I will test it again

 

[Trouble-Brewing]

I got a chance to do a quick test and got the water to 167* before it started pouring and I had to quit. I think once I get it all tuned it should be able to get the water to 180* for sparging which would cut my brewing time considerably. Because the test was cut short I did not get a chance to time it for a flow rate but I would guess it was around 1/3 to 1/2 gpm. I am pretty happy with it, though I really do need to get a mount for the burner the cinder block is kind of sketchy. I will post some pictures and get a better test and flow rate when the weather clears up

 

[GreenMonti]

I got a chance to do a quick test and got the water to 167* before it started pouring and I had to quit. I think once I get it all tuned it should be able to get the water to 180* for sparging which would cut my brewing time considerably. Because the test was cut short I did not get a chance to time it for a flow rate but I would guess it was around 1/3 to 1/2 gpm. I am pretty happy with it, though I really do need to get a mount for the burner the cinder block is kind of sketchy. I will post some pictures and get a better test and flow rate when the weather clears up

That doesn't seem bad considering the big hole in the middle. Sparging will only use a few ounces per minuet flow. That is if you fly sparge.

It will make steam if you want it too. When I am making steam I am only flowing 3 GPH. That is only 6.5 ounces per minuet. I push a little more then that for my boil, but not much more.

The higher flow rates will only save you time on the strike water.

 

[GreenMonti]

Trouble-Brewing,
So you only have 1 in and then 1 out? Are you able to generate steam with this? The flash boiler that I've been looking at on other threads has 4, 1/4" smaller tubes tied into 1 larger water feed. Does this help with steam production or is it to increase throughput?

The idea behind 4 1/4" tubes is to increase surface area to water ratio. The smaller tube also creates a more turbulent flow through the tubing, making for better mixing and heating of the water inside. If water flow is too linear you can get water that has different temps. What I mean is, a thin film of heated water and cooler water above it. Kinda like the thermo-clines in the ocean. There can be bands of water at different temps, and due to that the densities are different. Giving you layers of water flowing on top of one another. Not mixing.

 

[Trouble-Brewing]

I got to do a real test today and heated water from 57* to 183* fast enough to fly sparge. At 1/3 gpm the water is 147* so a little under 1/3 gpm to strike temp. I also tried to get it to make steam and it did with no issues, which I am pretty excited about. My mash tun struggles to hold heat so steam on demand will be pretty cool.

Here are some pictures of the mount to my ghetto brew-stand and the coil redo. Don't flame the burner mount, a real one is in the works. The brew-stand will get painted and cleaned up as well.

 

[GreenMonti]

If you close the air shutter down to where the burner becomes quiet you will get more heat into the water. The rich flame licks up into the coils. Plus you don't have to listen to the jet engine. My setup runs near silent. You hear the gas hissing and you can hear the boiling water flopping about.

 

[Trouble-Brewing]

I will give that a try, the wind was messing with the flame so it had to be on pretty high to stay lit, the flame was pretty high in the coils. When I get the burner in a solid mount it will be up in the tube a little and be blocked from the wind so I should be able to tune the flame better

 

[GreenMonti]

I will give that a try, the wind was messing with the flame so it had to be on pretty high to stay lit, the flame was pretty high in the coils. When I get the burner in a solid mount it will be up in the tube a little and be blocked from the wind so I should be able to tune the flame better

Yea, once I got mine tuned in, I now run it in my garage. Reason being, I don't run my burner very high any more. Wind is gonna be a problem for you if you want to run lower flame and flow rates.


Running it a little rich will still help with the higher firing rate. I think you will get more out of it.

 

[Trouble-Brewing]

I think you will get more out of it.

Thats what I want to hear