Questions about a steam setup

[snowman_fs]

I'm planning on building a 5500w steam generator and have a few questions for those who have experience running steam. My plan is to use a direct injection "wand" for cooking, mashing and general water heating in various 10-50 Gallon BOPs depending on the need and an indirect "coil" internal to my 13.2 Gallon boiler to keep the condensate out of the boiler.

1. Do indirect coils boil on the grain well or should I plan on injection there too? If they work, do you need to ramp temperature slowly and/or stir until it's ready to roll? I would like to use a length of 1/2"x10' CSST as the indirect "element" within the boiler. A significant motivator for me is boiling on the grain but I also want to be able to use the boiler for beer/wort where the condensate can be an issue in the boil volume. Opinions either way, are appreciated.
2. What about the steam generator reservoir volume. I could use a sealed 6 Gal keg but would rather keep the start-up time/energy short and run-time indefinite via something like:



I'm thinking a 3" tube/pipe with a ULWD element as compared to 2" shown. Does anyone have a good lower level to the working ratio of power to reservoir volume? I can also reduce the fill "shot volume" by sizing the level sensing tube smaller or using a shorter action level sensor. It is a trade-off between too much cold water that quenches the steam output to excess or wasted energy within the system at shutdown.

[varocketry]

Great diagram.

That setup is beyond my capabilities at present but it's of interest. You might enjoy these discussions:

1) http://homedistiller.org/forum/viewtopi ... d#p7362737

2) http://www.artisan-distiller.net/phpBB3 ... or#p128535" onclick="window.open(this.href);return false;" rel="nofollow

3) https://www.stilldragon.org/discussion/ ... nerator/p1" onclick="window.open(this.href);return false;" rel="nofollow

4) https://www.stilldragon.org/discussion/ ... m-stripper" onclick="window.open(this.href);return false;" rel="nofollow


Please continue to share your ideas and work here.

[Brutal]

I had convinced myself that I didn't need a steam gen like this, but lately it just makes too much sense. I've not built one but read all I can so take my advise with a grain of salt. I don't think the 3" tube will do anything but take about 4-5 minutes longer to heat up. I don't believe the inlet water will come in fast enough to hurt the boil. If there is a problem I would likely wrap the inlet line to the steam chamber around the bottom several times before going in.

I am excited to see your build! I want one but haven't finished several projects so it will be a little while.

[bearriver]

Already dubbed the "Steam Dragon" by it's designers over at the Still Dragon forums.

I am going to put one together. For me it is simply a matter of having the money and the time. I have been broke for a few months now after each bill cycle.

Telluride Distilling posted in the link above. If you go down this route, I would be sure to thank him!

[RedwoodHillBilly]

Gotta love the t-slot extrusions. Looks like Bosch, I've used 80/20 a lot in industrial automation and have a bunch of it here at home. Erector sets for engineers.

[snowman_fs]

yup, telluride and "steam dragon" serves as the inspiration. If they are lurking I send on many thanks.
If it were possible I would just duplicate their design but I also need to make it with a budget in mind. The final design they use is with 4" pipe.

Industrial boiler design ratios for 5.5 kW round out to be near 20 L water volume and 150 cm^2 of evaporative surface. Which turns out to be a 5.5" pipe ID x 4' in this vertical pipe configuration. I'm sure there are a lot of margins in the design books and any "compromises" will just reduce the maximum sustained output from the full 5.5kW to something less, which is fine as I have always found I had plenty of power as an immersion element. I'll stick with 3" tube and deal with it.

Sanitary tube is actually a pretty good "value" for the main boiler chamber, (since I want stainless) but outside of that I'm going to switch to NPT pipe and seamless tube and compression fittings.

[snowman_fs]

Just noodling around in the garage and I came up with this out of spare parts. What I have is an 1-1/4" main tube with a 1" bushing in the bottom of the Tee to accept an element. Everything is hand fit for now as I need to shop for some more parts; but I'll get there soon. I have abandoned the idea of 3" dairy tube since I have this and it won't require drilling, tapping and brazing stainless end caps like I was planning before.

Brutal, I think you might be correct about tube size being a non-issue for our purposes. Modern electric boilers get pretty small. Gas fired monotube boilers with a single coiled water tube also have extreme turbulence in the boiling. I'm not trying to be a power plant here and can tolerate the compromise of "wet" steam or reduced output efficiency.

Now for sanity check; with a 5.5kW and a design point of 123oC/220 kPa, (250oF/15psig) it should consume 124 ml/min of 10oC feedwater or 134 ml/min of 60oC feedwater, (0.5kW more steam power if I use domestic hot vs cold water ). The water level in the 1-1/4" tube will drop at a rate of about 5"/minute which also seems pretty quick. I'll consider adding volume to the system and/or using an orifice plate on the fill to prevent short cycling the valve and also stabilizing the system.

Which brings me to the output side. I want to run it "valveless" on the steam discharge side with PID temperature controller and an orifice plate. A 0.125" orifice will induce upto 202 kPa (15 psig) of backpressure to the boiler given max power and will smooth the steam production. A globe valve just seems unnecessary and also a hazard if it were to be shut by accident. I already have the PID temp control available which can to throttle the power as I see fit through the orifice. The question becomes what temperature do I monitor for the control feedback? The boiler temp or product temp? I'll have to prove to myself that the orifice will limit the upper temp/pressure under full power to 250oF/15psig before I try anything else but it seems pretty slick to just set a product temp with steam. If the steam can also induce effective agitation... happy still'n ahead.

There will be 200 L/s of steam passing through the orifice into 1/2" CSST at about 20 miles per hour. Hopefully fully condensing within my coil or mash...

I need to keep playing with an idea I have for the level control. My basic plan is to fabricate a hollow SS "pill" that can ride vertically inside a sight glass and float in water. Then a standard prox switch could be clamped to the exterior of the sight tube to trigger the fill.

[Brutal]

Just noodling around in the garage and I came up with this out of spare parts. What I have is an 1-1/4" main tube with a 1" bushing in the bottom of the Tee to accept an element. Everything is hand fit for now as I need to shop for some more parts; but I'll get there soon. I have abandoned the idea of 3" dairy tube since I have this and it won't require drilling, tapping and brazing stainless end caps like I was planning before.

Brutal, I think you might be correct about tube size being a non-issue for our purposes. Modern electric boilers get pretty small. Gas fired monotube boilers with a single coiled water tube also have extreme turbulence in the boiling. I'm not trying to be a power plant here and can tolerate the compromise of "wet" steam or reduced output efficiency.

2016-02-09.jpg

Now for sanity check; with a 5.5kW and a design point of 123oC/220 kPa, (250oF/15psig) it should consume 124 ml/min of 10oC feedwater or 134 ml/min of 60oC feedwater, (0.5kW more steam power if I use domestic hot vs cold water ). The water level in the 1-1/4" tube will drop at a rate of about 5"/minute which also seems pretty quick. I'll consider adding volume to the system and/or using an orifice plate on the fill to prevent short cycling the valve and also stabilizing the system.

Which brings me to the output side. I want to run it "valveless" on the steam discharge side with PID temperature controller and an orifice plate. A 0.125" orifice will induce upto 202 kPa (15 psig) of backpressure to the boiler given max power and will smooth the steam production. A globe valve just seems unnecessary and also a hazard if it were to be shut by accident. I already have the PID temp control available which can to throttle the power as I see fit through the orifice. The question becomes what temperature do I monitor for the control feedback? The boiler temp or product temp? I'll have to prove to myself that the orifice will limit the upper temp/pressure under full power to 250oF/15psig before I try anything else but it seems pretty slick to just set a product temp with steam. If the steam can also induce effective agitation... happy still'n ahead.

There will be 200 L/s of steam passing through the orifice into 1/2" CSST at about 20 miles per hour. Hopefully fully condensing within my coil or mash...

I need to keep playing with an idea I have for the level control. My basic plan is to fabricate a hollow SS "pill" that can ride vertically inside a sight glass and float in water. Then a standard prox switch could be clamped to the exterior of the sight tube to trigger the fill.

Are you planning to run the steam under pressure? I hadn't thought of that. I was assuming just a wet steam situation similar to what I run now. I have to admit a moment of ignorance as well, that Google couldn't even save me from. What is the "oC" specification? I'm familiar with psi and kpa but lost on that spec.

Running under pressure is going to be a lot less dangerous with such a small boiler size.. It's a pretty good idea. If a keg full of super heated water vents to atmosphere it could be catastrophic, but this little tube boiler.. not that it wouldn't suck, but it wouldn't scorch everything in the room.

I see now there is more to this design that I do not know. My previous advise on tube size was an assumption. As I mentioned I have no practical experience with the design. I am going to correct that soon though. This is just too interesting. So many design variables to ponder. your SS pipe is a very interesting approach. It looks very strong. This could be done in other ways too. What is we made the main body out of one of those borosilicate tube sections people put in their columns? That would take the guesswork out of fluid bed levels and flow. Might not be good for use under pressure though. This whole thing could potentially be built out of copper pipe too.

I very much appreciate you starting this thread and project, and sharing it with us here. This whole design is based on things working together as a system, and working together to create a steam output with a small "boiler" capacity. It relies on the water feed to keep up with the conversion rate to steam. If that keeps the element below water then it's just driving the heater to get what you want. It makes it almost a steam on demand system. It now looks like it could also be a super heated steam on demand system. The pressure could be regulated through some kind of a valve, and made safe with a blow off and a gauge.

[snowman_fs]

oops, "oC" is just my short version of degrees Celcius.

Yes, my plan is to run under a slight pressure within the boiler. I'm going to keep everything rated for 150 psig steam or more but not be able to run it over 15 psig +/-. I will have to swap out to a smaller orifice to do so anyway. My PRV is going to be either 100 or 125 psig in case the orifice gets plugged but the temp controller can also prevent that from happening. A PID can be set to limit psig via temp, say 130oC which translates to 25 psig. The gauge glass seals will be the weakest links followed by the element seal. If the gauge glass doesn't work out I'll just have to use a typical level sensor. Although I like the idea of seeing the level.

I'm much more comfortable using a small volume; steam scares me. I have parts on the way now and should be able to get mocked up even further by the weekend. I'll be sure to post back as I go.

[yakattack]

Forgive my ignorance, but one thing you may want to consider is having your condensor water feed your steam boiler. This will help with the efficiency. It may only mean a small increase but maybe worth it if you can.

I'm really liking where you are taking this. Keep updates coming.

Yak

[snowman_fs]

Forgive my ignorance, but one thing you may want to consider is having your condensor water feed your steam boiler. This will help with the efficiency. It may only mean a small increase but maybe worth it if you can.

I like the idea of using the hottest feedwater possible. That is how large boilers conserve energy as well as protect from cold feedwater shock. It results in about +10% difference to the steam output.

The tricky part is that the supply has to be under pressure to feed into the pressurized boiler; since it will also be under pressure. It is easy to just use my domestic hot water at 60-80 psig, but I like the idea of recovering the still's condensing water energy when it's available. It will have to be through a heat exchanger as there are flow and pressure differences between the condensing water (500ml/min and 0 psig) and boiler feedwater (125ml/min and >15 psig).

I have a SS plate exchanger from brewing I can plumb in later.

[snowman_fs]

Small update. I was able to float in water a section of 3/8" ss tube with .010" wall thickness with crimped closed ends. The success gives me hope that I can make my level sensor work with a sight glass tube and floating SS vertical pill inside.

That's the good news. The bad news is that the floating SS tube doesn't fit within the sight glass I now own. I miscalculated the ID of the glass... Worse is that the smaller diameter SS tubes that fit in the glass I have can't float. So I need a bigger sight glass, which requires bigger fittings and o-rings. But I need to prove that the seal from gauge glass to compression fittings will hold back at least mains water pressure before I order new fittings. I'll try and test that tonight.

I also found a main boiler tube that gives 12" of space above the element. I'll split that space for water and steam 50/50. That's much more manageable than the shorter pipe. The total volume of system is only going to be about 700 ml. Which means from power on to full boil is only about a minute to a minute and a half.

[shadylane]

Just an intoxicated thought or two.
Your idea of using an electric element to heat the minimum amount of water needed at the moment is a good idea.
Direct steam injection at atmospheric pressure might be better for cooking, mashing and general water heating.
But that limits the steams temp to 212f or slightly higher.

Personally
I'd have a water level sight glass and a separate way to control the boiler water level.
Not try to do both with the same thing.
I'd also limit the max pressure with a 15psi pressure relief valve.

[shadylane]

Dadburnit I forgot what I original wanted to say.
The PRV needs to relieve the pressure well below what the feed water pressure is or you might start blowing steam back into the cities water pipes

[snowman_fs]

Yeah I thought about the PRV and its setting for a while. The only time pressure can rise above the 15 psi orifice back pressure is if there is an obstruction to the steam outflow; again why I don't want a valve that can be closed by accident on the outflow. But a plug is a reasonable scenario to consider. When a plug happens the water levels will not drop since its a restricted or closed system, temps will rise, the PID will cut out and over temp alarms will trip. I want this to quietly happen well before I start venting steam, even at 15 psi.

Even worse, say the steam orifice gets plugged and the SSR also fails in a current passing scenario, (to which my breaker didn't trip). The water volume won't drop to trigger the fill valve. Even if the fill valve was open, the water fill orifice plate would slow the steam backflow to domestic lines. At .020" it can only pass 1 lb/hr of steam at 100 psig to the domestic 40 psig. Again, I would rather send steam into the domestic lines then a direct vent to atmosphere. If it continued long enough the excess pressure would be handled by the domestic boiler expansion tank and 15 psig PRV, venting within my utility room where there is little to no risk of hurting anyone. My new electric boiler would eventually empty itself of water until the element was dry firing and burned itself out. A scenario I am content with.

If all else goes wrong and pressures rise out of control, beyond the element burning up and casually failing within a pipe is the time I want the PRV to do its job and prevent a pipe explosion. At that time, the lesser of two evils is a direct vent of steam.

I feel like my tone during all of this sounds rather aggressive; I don't want it to by any means and always appreciate feedback. I will be the first to admit I hate the threat of steam. It deserves more respect for safety than just about anything else.

I think the greater risk is from level control failure. Low water levels being the only hazardous failure of level control. Especially since I have not designed in a low limit cutout. The element will eventually dry fire and burn up. Since it's contained within a pipe I'm willing to view the element itself as the fuse in this case and replace it if need be.

[snowman_fs]

The new shape of things to come.

The dipped handle on the pipe wrench at the bottom serves as the mockup 12" insertion depth of the 5500w element.

On top I have a Pt100 temperature probe, 0.125" steam orifice out to the right and a tee for the PRV as you goto the left. As you continue counterclockwise down the 1/2" steel tube there is another tee with a 0.020" orifice for the fill solenoid connection. The horizontal pipe will have the level sensor inserted in the left side of the big tee. At the other end of the horizontal pipe more 1/2" seamless tube to connect to the bottom of the boiler. I'm abandoning the glass gauge idea as it doesn't fit within the 1/2" compression fittings. I'm cutting my losses on that one.

Things I like about this new layout.
1. A single level switch with hysteresis in the horizontal pipe can be used to hold the level. I'll try and calculate the expected open/close times on the fill valve at max power. I'll have about 1/3 of the water capacity of the system over in the well and something like 90% of the surface area. I'm hopeful that it keeps the level more stable in the system.
2. The placement of the fill valve will make the level sensor the coolest place within the system. Well below boiling anyway.
3. All solid pipe and industry fittings gets rid of any pressure capacity unknowns. It will also make it shed tough; I now have no fear of accidental bumps breaking glass.

[snowman_fs]

So close. I wanted to be making a steam cloud this weekend as a test but I couldn't quite make it. I'm missing precious few parts that are unavailable on the weekend but the rest is tight and ready.

[raketemensch]

Gah, isn't that just the worst feeling, being that close and having to wait through a weekend when you have time to build? Sure there are other projects, but it's just not the same.

[snowman_fs]

I have runsteam a couple times now and don't quite have it down yet. I have been boiling down maple sap as a test and am not ready for it to be used for stilling yet. The major problem I think I have is that my level sensor for the feed water is vertical in the pipe tee and an air pocket gets stuck there; that never lets the fill switch turn off the feedwater. So I'm generating steam and a lot of extra hot water that floods out of the system. Thus robbing a lot of potential energy. I'll replumb the tee and try again soon. I already took bits apart trying to sort out the trouble and noticed the fill orifice I chose was partially plugged with a thread of Teflon pipe joint tape. Not wanting this to cause a future issue I drilled out the orifice to both let water in faster and reduce the risk of a feedwater plug.

Good news is that it heats up within a minute or two and also shuts down in seconds when requested. I also tested the system as a sealed unit and ran the temp upto 135 deg C with no issue.

Be back soon when I can try another run with properly working fill control.

[snowman_fs]

I have been playing and tweaking my steam setup for some time now. The largest thing learned is that Indirect steam heat with domestic cold makeup and no condensate recovery has a large efficiency loss. From my 5500w input power, I estimate about 2500w of effective heat to the pot, (nothing insulated yet). That's fine for holding temps but a pain to ramp or distill with. So I'm looking into closing the steam loop with a Harvard loop and gaining a significant chunk of that power back and no condensate to remove. The current reduction in power means boiling on the grain is a bit slower than I wanted and I can't effectively run my 3" reflux with steam and need to use the ULWD immersion element.

Direct injection with steam is great for mashing as many here know. Start thick as the condensate will dilute the mash over time, do the math you need to but it can be significant.

Here is a pic inside my pot as I was heating water with indirect steam to clean and passivate after I reworked my bottom drain. You can see lots of bubbles forming on the CSST. The immersion element was not powered here.

[Brutal]

Thanks for the update Snowman. So your work has been with indirect steam heating? I thought you were going to do some direct as well? Maybe I just remember it wrong. Anyway have you done any direct steam injection with your set up?

[engunear]

I've tried indirect steam heating with a copper coil. It did not work for me, the steam just blew out the end of the pipe. So if someone has made it work, I love to know how.

Having been burnt a few times by low pressure steam, high-pressure scares the crap out of me. I'd put it up there with plastics as something to avoid. Someone mentioned steam travelling at 20 miles an hour, or 2kW across an area less than 1 inch square - and it dumps all that energy into the cold mash. If it gets loose, it can't tell the difference between cold mash and cold skin, hand, face, eyeball, what me worry?

If that design is based on a working one, it intrigues me muchly. What does the pipe at the top joining the vertical two reservoirs do? If it has air in it, all is well. But it is likely to fill with steam and then the steam will go back down it, and heat the water in the left hand reservoir, won't it? In which case, whats the point of the two reservoirs? Not wishing to be narky or anything silly here, but I've pondered this a lot and find myself coming up with ways of doing this that just wont work. My solution in the end was to say "ah stuff it" and add extra water to my boiler pot. But the problem reminds me of the search for perpetual motion, somehow.

[engunear]

Going to answer my own question, having done some more homework.

This question came up in the Stilldragon thread. I didn't see an answer, but just the observation that it works, so thats it. Hypothesis is it works because there is air and not steam in the top piece of pipe joining the reservoirs. The air has nowhere to go and blocks the steam from going back. I suspect if this were operated continuously for long enough, the air would diffuse out, and it would start to misbehave, but with regular startup cycles the air gets replaced.

[snowman_fs]

I What does the pipe at the top joining the vertical two reservoirs do?

Sorry, I have been away for a while. This fall I should get back into stilling when the temps drop. The steam setup is one of the components I want to resurrect and get dialed in.

The purpose of the connecting pipe(s) and remote well is to equalize pressure between the boiler section and the float/level section. The reason for the remote well is two-fold:
1. It has a calm water surface for accurate level sensing; as the boiling in the main tube is violent and presumably difficult to use a float level sensor within.
2. If the well was not connected with a top and bottom tube, a pressure lock or pressure differential would exist between the two reservoirs. The only way water would move between them would be from supply pressure, I want/need a gravity balance within the system.