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Which diameter for CSST indirect steam heating?

Posted: Wed Feb 22, 2017 2:13 pm
by Evil Wizard
Hello gents,

I want to boil on the grain and on the herb using corrugated stainless steel tubing running through a 3" tri clamp end cap (modified) at the bottom of my boiler. I figure I can wrap multiple loops around the inside of the boiler and inject steam from the 3/4 nipple on a small water heater. The other end of the CSST would drop into a bucket (preventing pressure) that would feed back into the water heater with a check valve to prevent back flow. (This works great on my continuous distiller.)

My question is should I use 1/2", 3/4" or 1" CSST?

Suppositions:
The larger the diameter, the less surface area and slower vapour speed and less vapour resistance.
The smaller the diameter, the more surface area for heat transfer and higher vapour speed and higher resistance.

Comments would be greatly appreciated before I place an order.

Re: Which diameter for CSST indirect steam heating?

Posted: Wed Feb 22, 2017 3:54 pm
by Truckinbutch
Not sure about your configuration . I would like to interject that a simple 1" copper tube to the bottom of my thumper with a couple of notches in the end works wonders in distilling dirty mash that might scorch in the boiler .
One of my next projects is to replace a keg top with a ss plate with a 2" ferrule for the vapor tube , a 4" access hole for loading and cleaning for on grain distilling and a 1" bottom drain .

Re: Which diameter for CSST indirect steam heating?

Posted: Wed Feb 22, 2017 5:30 pm
by Evil Wizard
Hey TruckinButch,

I guess your steam is thumping directly into your kettle? This is indirect, so the steam passes through the CSST, exchanges heat with the wash, and passes out through the CSST without adding liquid to the boiler.

Here's a napkin sketch. Obviously not to scale.

Image

Re: Which diameter for CSST indirect steam heating?

Posted: Wed Feb 22, 2017 5:45 pm
by Truckinbutch
Understand your concept . Unnecessarily complicated for my setup . Not calling you wrong . Just offering a shorter path for stillin on grain .
SRD and I are setting batches that will charge a boiler with cleared mash and a thumper with the dirty . Thumper mods will eliminate all the straining and squeezing because we can steam the grains in the thumper .
At least that is our hope . Wouldn't be the first time I turned up wrong .

Re: Which diameter for CSST indirect steam heating?

Posted: Wed Feb 22, 2017 5:52 pm
by Evil Wizard
Yeah I will be using direct injection of steam to get the mash up to temp. I'm actually distilling herbs, not grain - this is an absinthe distillation.

I'm thinking that I will probably be able to get more BTUs through a 1" CSST and at a safer (lower) vapour speed).

Re: Which diameter for CSST indirect steam heating?

Posted: Wed Feb 22, 2017 6:03 pm
by Truckinbutch
Makes sense to me . More volume at lower pressure . More thorough cook What are the negatives for that ?

Re: Which diameter for CSST indirect steam heating?

Posted: Wed Feb 22, 2017 8:23 pm
by FuelMaker
I looked into using CSST as a monotube dry steam generator w/ a gas fired boiler - the stuff is really expensive by the foot and has comparitively poor thermal transfer characteristics. The only reason I was looking at CSST is its corrosion resistance to being exposed to a gas flame.

If you dont need the corrosion resistance you'd be much better off using 1/2 or 5/8 copper refrigeration tubing. The better thermal transfer of copper will let you use a shorter length of it.

What you're planning is what I'm planning on doing, only I'm not sure whether I'm going to be doing direct injection or indirect w/ a return line. In either case I'll be coming down through the lid vs going through the side wall of the boiler - I want to minimize the boiler penetrations.

Direct injection or not all really depend on what I observe with my steam generator - how long of a coil will I need to completely condense the 450 degree steam. I imagine you'll have to do the same kind of experiments to see.

Re: Which diameter for CSST indirect steam heating?

Posted: Wed Feb 22, 2017 11:38 pm
by Evil Wizard
Hey Fuelmaker, thanks for the reply.

I can get 1" csst off amazon.ca for $4.68/ft CDN (so about $3.50USD) I don't consider that expensive -I'm going legit and can expense it. If I have to do 3 boiler wraps I'm ok with that as long as I don't create a u-trap and blow it up from over pressure.

I agree - stainless steel has terrible thermal transfer compared to copper. I'm just not sure if I can bend 5/8 copper sufficiently to get it in and out of the boiler. I want it to be removable.

Any idea where to find the minimum bend radius of refrigeration copper? Late night + 3 drinks + google isn't helping.

I also want to use the same csst of whatever I buy inside the dephlamator of my 6" flute build. The minimum bend radius of Home-flex brand 1" is given as 2". My 6" pipe is type k, so ID of that is 5.7412", the OD of the csst is 1.05" so (5.7412"-1.05"-1.05")/2 = 1.8206" compared to 2" and so I think I can squeeze it into the 6" pipe and angle it if necessary.

Cheers.

Re: Which diameter for CSST indirect steam heating?

Posted: Thu Feb 23, 2017 8:43 pm
by FuelMaker
I'm thinking if you use refrigeration tubing you can bend it a lot easier than copper pipe, refrigeration tubing is dead soft. Into/out the boiler could be done with standard plumbing elbows and other fittings. With fittings you can make as sharp a turn as you need.admin edit- Refrigeration tubing can be either hard or soft copper

Re: Which diameter for CSST indirect steam heating?

Posted: Thu Feb 23, 2017 9:42 pm
by Fills Jars Slowly
I will second what Truckinbutch said about the ease of steam injection. It is the simplest and easiest way to skin the cat. The main difference is that if you tell people you are running cleared mash in your boiler and the thicker stuff in your thumper they will nod and approve, and if you tell them you have a steam injection distillation system they will get uptight about the number and type of pressure release mechanisms you have on the steam boiler. I speak from experience. They are the same thing, but... All joking aside, make sure you can never build more than a negligible amount of pressure in any distillation related vessel, and make sure that if you do so accidentally that it can be vented safely. Same thing goes for negative pressure. There are plenty of internet pictures of kegs and other vessels crumpled from the effects of holding a vacuum as they cool. I am sure you know all that.

As for the benefits of copper over CSST in terms of heat transfer, I have real data on it, and it doesn't jibe with conventional wisdom. Conventional wisdom accurately states that copper has better thermal transfer characteristics than stainless. That is true, but it leaves out important information. Corrugated stainless is much thinner walled and has a much greater surface area than a similar specification of non-corrugated copper. For $1.26 per foot on Ebay, 3/8" CSST has a much better performance "IRL", as the kids say, than copper of a similar cross section, both in terms of doing the job and cost. In other words, the added surface area of the corrugations plus the thinner walls to transfer heat through more than compensate for copper's clearly superior thermal transfer numbers.

They say a picture is worth a thousand words, so here is a picture that illustrates the thermal transfer characteristics of a 25 foot long 3/8" CSST wort chiller coil chilling a 10 gallon pot of boiling water versus a 25 foot long 3/8" copper tubing wort chiller versus a 25 foot counterflow chiller of a similar diameter versus a plate chiller doing the same thing. It is an inverse (but equal) example to your mash/still heating problem. The CSST is superior to all but the plate chiller, which is a seriously more expensive option and only works on beer wort or other liquid without much solids content. You can stick a CSST wort chiller/heater in your pot of mushy mash and get it cooled/heated much more efficiently than a copper coil.
ChillerPerformance.png
In all, I would recommend you avoid the whole issue and direct inject your still and use the CSST in condensers of various types for distilling and HERMS units of various types for brewing. You mention direct injection as part of your process. Why is it unacceptable to use that for the whole thing? It will always be more efficient than indirect steam heating. With direct injection ALL of the heat goes into the pot.

Re: Which diameter for CSST indirect steam heating?

Posted: Mon Mar 20, 2017 8:50 am
by Evil Wizard
Wow, great post, FJS, thanks for that. It does make sense that the corrugations of the CSST will aid thermal transfer, and the stuff is just so much easier to fabricate. I already built a 1" copper internal steam element but I doubt it will be the last thing I build.

Regarding direct injection of steam into the mash, I figured it would give me problems by increasing the water to alcohol ratio in the boiler. What if I fill up the boiler before the run is finished? And won't it take more energy to keep all that water hot in the boiler?

Re: Which diameter for CSST indirect steam heating?

Posted: Mon Mar 20, 2017 10:25 am
by ShineRunner
I'm not sure exactly what you're asking, but if you're injecting steam into the mash for cooking corn and such, then you don't have alcohol in there. Yes, it adds water to your mash, but just start with less and go from there. I calculate direct heating of my mash with steam is somewhere around 10-15% of my initial water. Start with less than that and top up later if needed.

If you're talking about steam injection for distillation, then yes, again it adds water. It will dilute your beer some, but not as much as when heating water alone. The beer will boil at a lower temp due to presence of alcohol and come up to temp faster. You might notice a slight difference in your low wine ABV, but i personally wouldn't worry.

It will fill the still a little, so you're going to want to leave more headspace than usual. The still will fill with condensed water until it starts boiling. Once it reaches boiling, it will essentially match the boil off rate of your boiler, and thus stop filling. This is essentially how a thumper works. A thumper is basically a steam injected still- injected with alcohol vapor, or whatever is in your primary boiler. This is what it sounds like you're building?

SR

Re: Which diameter for CSST indirect steam heating?

Posted: Tue May 02, 2017 7:02 pm
by Brutal
@Evil Wizard, great thread! Lots of good info and discussion here. I hate to "jump on the direct injection bandwagon," but I have to. Honestly I can think of very few indirect heated set ups that actually work that I've seen on the 'net. The only ones of note are the coveted double walled boilers. And the people that have them have reported quite a few quirks. Like the inability to boil a smaller boiler charge (mash.) The boiler in question will boil a more full load of mash, but struggles with a half charge. The difference being contact area. The smaller charge is more shallow, and therefore contacts much less of the jacketed skin of the boiler. Less contact area means less total heat transferred. But back to the point there are very few indirect distilling set ups out there that work. At the same time people have a near 100% success rate with direct injection. It's a sure thing and twice as easy.

@Fills Jars Slowly this made me laugh out loud so much. Then I tried to explain it to my wife. You just have to be one of us to get it! I'm putting it in Notable and Quotable!
Fills Jars Slowly wrote: The main difference is that if you tell people you are running cleared mash in your boiler and the thicker stuff in your thumper they will nod and approve, and if you tell them you have a steam injection distillation system they will get uptight about the number and type of pressure release mechanisms you have on the steam boiler.

Re: Which diameter for CSST indirect steam heating?

Posted: Tue May 02, 2017 8:11 pm
by Hank Reardon
Brutal wrote:@Evil Wizard, great thread! Lots of good info and discussion here. I hate to "jump on the direct injection bandwagon," but I have to. Honestly I can think of very few indirect heated set ups that actually work that I've seen on the 'net. The only ones of note are the coveted double walled boilers. And the people that have them have reported quite a few quirks. Like the inability to boil a smaller boiler charge (mash.) The boiler in question will boil a more full load of mash, but struggles with a half charge. The difference being contact area. The smaller charge is more shallow, and therefore contacts much less of the jacketed skin of the boiler. Less contact area means less total heat transferred. But back to the point there are very few indirect distilling set ups out there that work. At the same time people have a near 100% success rate with direct injection. It's a sure thing and twice as easy.
Evil,

I agree with Brutal. I looked for a long time at a double walled boiler, and went with the setup that FJS mentions. I personally went with an injector from the topside of the boiler and have run it a few times with some thick on the grain mash. It works great, and it was very easy to build. It also gives me some great versatility to put cleared mash in one boiler, goop in the "thumper", which I actually did with Bentstick's Oat, Wheat, Rye and it was awesome. Something about that vapor coming through the grain that makes the flavor very grain-forward. Delicious. Anyway, good luck with your design.

FJS's quote is some funny shit....very snarky - which is hilarious most of the time. :) I still use a PRV though, because not knowing is worse. A manometer comes recommended by many here, but I have not yet built one.

Re: Which diameter for CSST indirect steam heating?

Posted: Wed May 03, 2017 8:33 am
by Evil Wizard
Hey guys, I had no idea we were still talking about this.

I finished the build a month or two ago and will be testing it out next week on a wheat - vodka mash. I will be fermenting and distilling on the grain in the same kettle.

Now when I said I was building an indirect steamer a few people must have assumed I meant jacketed or double bottomed. In fact I built an internal 1" copper loop for steam. Then I threw in a 1/2" direct injection port anyway. That's been handy for steam cleaning and sterilizing.

My latest question regards backflow through the direct steam port from the kettle into the 15 times smaller and physically lower steam generator. Should I build a u-trap to prevent backflow? I'm not sure how many watts would be needed to blast through the down pressure of 400L of mash.