Mash tun / stripping still

[Salt Must Flow]

It really depends on who's specs you read. Some say 200F max working temp. Some say 250F while others claim 300F.

[Bolverk]

Mine is 300°C so I guess I should be fine

[zach]

Most steam boilers have some type of drum to allow for recirculation internally. The drum "floods" the heat exchanger and acts as a separation device to provide dry steam to the load and allows for sufficient internal circulation to provide good heat transfer and eliminate "hot spots" . Internal circulation rates can be many times the evaporation rate.

boiler drum.jpg (13.29 KiB) Viewed 2354 times

The geometry of your boiler with the 2 inch chamber does not allow for much internal circulation. With 4.5 kw you have 15.9 lbs/hr of steam which corresponds to 5 ft/sec in the 2" riser leaving the boiler. A sight glass would be helpful in that you could see if there is condensate carry over and that the element is covered.


A larger diameter tube will allow more internal recirculation.

[Bolverk]

Thanks Zack, I see what you're saying..

I'll add the sight glass at the top of the boiler and see how it's goes. If I blow another element I'll expand the boiler chamber to 4", but that's going to make this this too heavy to hang off the end of the keg so I'll have to redesign the whole thing to stand on its own. If have to do a full redesign I'll make it so that the water can circulate better.

[Bolverk]

Another option would be to make the boiler out of a 20l skinny keg and stick the element up through the bottom... there would only be about 4 gals of water that should come to a boil in roughly 20 mins.

Something like this would definitely be more common.

[zach]

Another possible option. 4" filter housing with 2" connections.

I like the 20 liter keg better.

41MnsJjb9dL._AC_US100_.jpg (2.74 KiB) Viewed 2331 times

[Yummyrum]

That should work Bolverk but surely there has to be a smaller size. Like 20min boil up seems to almost the defeat the purpose.
Got to be a happy medium

[Bolverk]

Oh, the filter housing is a good idea!

Yeah 20 min would not be ideal, but throwing another $500+ in 4" parts at this isn't ideal either lol.

I do like this idea of this being 100% off the shelf so that others without access to a welder can build one if they want

[tjsc5f]

That filter housing looks nice, 4" x 14.5" OAL and reducer tri clamps built in for $70.

20L keg and 20min heatup time would be a no go for me, lol.

[Bolverk]

20 minutes isn't terrible considering your yield will be a little higher working on grain, so it's worth it to me, but if I can get that down to sub 5 minutes I'd definitely be happier.

If I'm not mistaken, your run will also be faster since you can strip at 4500w and not worry about scorching so the 20 minutes may be a wash in the end.

[Tōtōchtin]

A ss 10 Lt milk can should be wide and cheap enough to work. It would seem there would be enough pre run chores to occupy those 20 min.
Tōtō

[zach]

I have my steam generator heating as I do the final assembly of the thumper and condenser. 20 minutes ain't bad.

Badmotivator had a build thread with two elements in the bottom of a 15 gallon keg. viewtopic.php?t=56356


You might install a 2nd tri clamp on the bottom of the 20l keg which would allow boosting the power in the future. Even another 1800 watts on a 120 V circuit would help during the warm up.

[Bolverk]

That's filter assembly is about .75g and at 4500w should only take about 3.5 minutes to start boiling.

My question now becomes is the 4" diameter spool with 2-3" of water coverage enough internal water circulation or would I still need to add the sight glass above it? I dont have an issue with adding the glass, the problem is the braided hose will no longer be long enough, so if I do this ill have to add a new water feed line.

[Bolverk]

You might install a 2nd tri clamp on the bottom of the 20l keg which would allow boosting the power in the future. Even another 1800 watts on a 120 V circuit would help during the warm up.

Oh, for sure, I'd be adding 2 or 3 ports for elements if I go this keg route

[zach]

If you look at the thread I posted above, I asked Badmotivator about min operating level. His answer was 4 gallons in a 13 gallon keg using short 2000 watt elements from Camco. You probably can do the approximate math from there.

With 4.5 kw I would double the distance from the top of the element to the operating level.

[zach]

I would guess 2 inches to not be enough with the 4 inch chamber, but you could try it with a cheap element.

You might be able to fold an element to get a shorter effective length. I've seen pictures of other members bending elements. I see 11 inch long high watt density units at 4500 watts that might be folded to 6 inches long. It might be worth the gamble on the rig you have now.

[Bolverk]

Thanks, I'm at the office. I'll read that thread a little later.

I can extend that tube boiler down about another 12" with 2" spools i already have before I need to make significant changes, so I'll give that a shot. 14" of water coverage should hopefully be safe enough and ill do the sightglass to be sure.

This is the element I got, it wouldn't be too difficult to fold back if needed.
https://www.amazon.com/gp/aw/d/B009AX2C ... asin_title

[tjsc5f]

I think having the sight glass above the element is a good idea, at least initially to verify something goofy/unexpected isn't happening with the water level on that side.

[Bolverk]

Agreed

I suspect that at 4500w there isnt going to be enough water circulation to keep the element wet and I'll keep blowing elements. I'm already in the back of my mind working on a 4" boiler tube version, but it's going to need to be a stand alone.

[Yummyrum]

Been thinking about Zachs thermo cycle idea and wondered if we could achieve something similar by adding some external tubes .
My thinking is that there would be an upward flow around the element that would pull in water through the tubes at the bottom and circulate water for a more even boil ……. Or maybe Im pissing in the wind .

[Salt Must Flow]

I've seen a lot of similar steam builds and I don't recall reading where people had issues with the element inside of 2" or 4" tubes. Before I'd change everything up, I'd have to confirm there's a major issue first.

With that element that burned out, the blackened tip kinda gives it away. It's logical to assume that the water level dropped a bit. I'm hoping just installing a sight glass solves the problem.

[Bolverk]

Yummyrum, I like the idea, but I gotta think just a larger diameter spool should solve the circulation problem.

Salt, you're right this "should" work, just need to figure out the details

OK, It's not ideal, but if this works I'll plumb the feed line at the bottom of the boiler.

The entire element will be at or below the feed point and there will be 8" of water above it.

This (the water level will be in the middle of the sight glass here)

Or this

[zach]

I like the first photo where the operating level is in the sight glass. With 8" of water level above the tip of the element, I bet it will work fine.

[Bolverk]

Thanks, thats what I was thinking too, but also thought that seeing what the water situation right above the element could be beneficial as well.

[Bolverk]

New element is in

You can see that little green line on the segment where water feeds, that's the element height

[Bolverk]

Test 3

[Bolverk]

Continued







After the last video I took the element to 95% and it kept repeating the cycle of boil over and refill and every time it refills it crashes the boiler.

Once before I shut down it did a big burp of water that was very close to the actual element top, I feel like there is not enough circulation for that high powered of an element in that small diameter of a spool.

[Salt Must Flow]

I imagine the appropriate place to connect that stainless water line is as low as possible on that tube. I suspect that as the element starts to boil the water it creates a low pressure zone causing water to surge into the tube. If the water line were plumbed at the very bottom of the tube, I have a feeling this surging wouldn't happen (or at least as violently).

[Bolverk]

Yeah, that makes sense, i had a feeling that having the feed into the center was going to be a problem. I'll try replumbing it into the bottom and rerun the tests.

[Yummyrum]

I agree that the hose mid element is probably a bad place . I also wonder about the size of the connection hose you have . It is possible that the water can too easily move between the boiler and side canister and I wonder if a thiner hose/pipe would restrict or buffet the flow maintaining a more even volume and temp in both .
For testing purposes , I’d just use one of those braided 1/2” lines and even connect a valve in series to further restrict inter chamber flow .

BTW , great videos and good to be able to see whats happening inside