Measuring/Controlling boil rate and preventing boil over

[BigBlock]

So I’ve been slowly working proof of concept ideas for my fully automated brew rig and this week I’m tackling how to manage the boil and eliminate boil over. The simple concept is to seal up the boil pot and drill an orifice in the lid as the only outlet for steam to escape. Then measure the (differential) steam pressure in the pot compared to ambient and calculate the steam flow through the orifice. Steam flow should increase as the boil becomes more vigorous, and I can empirically find the pressure that coincides with boil over (may need a pre hot break and post hot break value). The added side benefit is that since I’ll be measuring steam flow, I know the boil rate and can close loop control to 1gal/hr or whatever target I want to hit.

So I did a quick test with a small pot (6”dia), a piece of lexan for the lid, and some gasket material to seal it up as a test. Drilled a ¼” hole as my orifice and threaded in a separate hose barb to connect up to a mpx5010DP sensor wired to an Arduino to monitor steam pressure and calc steam flow.

The Test:
My quick and dirty rig had some minor leakage issues, but when sealed I was getting ~7.1lbs/hr steam flow at full boil (this was just over 1”h20 DP or ~0.04 psi). I initially started with 7 cups of water and after 20 mins I had 2.5 cups left. I had calculated that I should have about 2.6 so I real happy with the results. With a good seal, some tuning of the discharge coefficient, and targeting a larger steam pressure range of 0-4 ”h20, there is an opportunity to be nuts on here.

Lingering issues:
There is one issue that I’m sure is on everyone’s mind and I would like some feedback from your experiences. That issue is DMS. Since I’m venting the steam, I’m hoping my problem is limited to managing the condensation on the lid (which in an ideal world wouldn’t be an issue as it returns to the boil and has another chance to be vented as steam). My initial thought is to use a domed lid and put a “gutter” around the perimeter to catch the condensate.

Looking for feedback:
I was reading that several brewers boil with the lid while partially covering the pot during the boil. In those cases has anyone been lazy and just let the condensate drip back in?
Anyone familiar with a real brewery setup? I assume that is a closed vessel with a vent that would also generate some amount of condensate.
And the obvious question, has anyone done this before?

 

[alphaomega]

Interesting. Well, not really the boiling/boilover part. Controlling the power, controls the boiloff rate and managing boilover is really just to lower power enough when reaching boil temp and wait until hotbreak is over.
IDK if you use gas or electric, but I seriously think you are overthinking this.

What I do find interesting is boiling with the lid on. I have the same idea and it will be my next brewing project. Seal the boil kettle (I'm thinking simple at first, just a silicone gasket and weighing the lid down) and have a single point of exit for the vapour. I want to lead the vapour through a condenser (specifically a type of radiator, finned aluminum piping, used in caravans and buses and such, cooled with fans or possibly a worm in a bucket), since I don't want to steam up my basement where I brew and venting out is a pain, especially during winter.

I think there could be a lot of benefits to this. Not only riddance of steam, but in the event of a boilover it will be forced out the pipe and cleanup will be easier. Power usage should be less, as a rolling boil is a lot easier to do when covered (lower power heater required, lower power fuse et.c), though longer boils might be required to get to correct boiloff.
I really don't think DMS will be an issue, as the steam is still expelled. I'm planning on insulating the lid, just to minimize dripback, but really DMS has such a low boiling point, which should mean that even that condensate should be depleted of DMS quite efficiently through distillation. And again, just increasing the boil length should also help.

I've been searching high and wide on the internet for anyone doing something similar, but the only things I've found are people copying commercial brewery designs (using water spraying, stacks and whatnot) which really makes no sense on a homebrewing scale, or just the reference to the DMS monster without anything backing that up.

No matter what your goal is, I'd LOVE to hear more of your experiences of boiling in a sealed kettle, with a single point of exit for the vapour. I think it is a stellar idea, just not for your reasons And I predict that you will still produce excellent beer and not cabbage soup, but even so, then it would be good to know.

Cheers!

 

[BigBlock]

Of course I'm over thinking this, that's what makes it fun

I use a propane burner so the heat input into the wort can vary a good amount depending on the time of year I brew (I brew in my garage with the door cracked). I tend to have to babysit the burner and make small adjustments periodically during the boil, and this seemed to be a cheap ($12 sensor) way to close the loop and automate my burner control during the boil. My endgoal is a "small" footprint 15 gal fully automated brew rig. Just like making coffee, put in the grain/hops and press brew

I like your idea of condensing the vapor. Not a problem in my setup, but would be nice in the winter when I do get some condensation on the doors and windows.

My initial pass at sealing the pot will likely be to gasket the lid and add a couple of latches on opposite sides of the pot, each with a spring attached to the lid. The springs will be sized as a pressure relief to prevent a big boom if the orifice were to clog. On my planned setup, every 1"h20 steam pressure will exert 10 lbs of force on the lid. I used a weight on my test rig.

 

[trimixdiver1]

Sounds cool, but I always was told to keep the lid off to get a greater surface area for DMS to be driven off. If you slightly pressurize the kettle I would think DMS may be an issue. Don't know though. My kettle is pressurizable as I had a 10" sanitary ferrel installed and will pressurize for transfers from the kettle.

 

[alphaomega]

Yes. That (well, or something similar) is what most of us hear when we start brewing.
But what you said about surface area is simply not true. Surface area of evaporation is still the same. And the amout of pressure we are talking about would most likely be neglible. I'd bet most commercial breweries don't boil with open kettles.

This is exactly what I am referring to. Simply quoting old homebrewing hearsay is not enough. I'd like to know what would the difference be between boiling off 10% with an open kettle or boiling off the same amount with a closed kettle venting through a smaller hole. I can't think of anything that really would have a truly negative impact. I may well be wrong, but in that case then at least there would be at least some empirical data.

 

[BigBlock]

yep, just for reference the max pressure diff in my setup would be 4 "H20 or 0.15psi. This is equivalent to brewing at a slightly lower altitude (~300ft lower).

 

[trimixdiver1]

I hope this is true! If you look a a large boil kettle,

View attachment ImageUploadedByHome Brew1422101340.944461.jpg

Use can see they slightly restrict flow. I have a 3/4 and a 1" triclover in my kettle lid

View attachment ImageUploadedByHome Brew1422101529.953566.jpg

I wonder if the 1" opening would be large enough? The only other issue is how to get hops in there.

 

[BigBlock]

Sweet setup!

1" should be plenty, since I was pushing just under 1gal/hour through a 1/4"hole with a pressure of about 0.05 psi. But anytime you pressurize a vessle you need to have a secondary pressure relief. you could probably use the three quarter inch opening to vent the steam and squeeze the hops for the one inch (custom hop screen tube?). I'll run the calc for home much pressure you would build up for each of those vent sizes when I'm back at my comp.

 

[trimixdiver1]

Sweet setup!



1" should be plenty, since I was pushing just under 1gal/hour through a 1/4"hole with a pressure of about 0.05 psi. But anytime you pressurize a vessle you need to have a secondary pressure relief. you could probably use the three quarter inch opening to vent the steam and squeeze the hops for the one inch (custom hop screen tube?). I'll run the calc for home much pressure you would build up for each of those vent sizes when I'm back at my comp.

Yea, I have 2 reliefs, just not installed in that pic. A swagelok pop it and a variable relief. Plus since I have a press xducer I can use my PLC to open a vent valve too, although that is not safety related.

 

[alphaomega]

@trimixdiver1, what the heck do you do with that kettle if not boiling with the lid on?!?

 

[trimixdiver1]

@trimixdiver1, what the heck do you do with that kettle if not boiling with the lid on?!?

Pressurized transfer through the chiller into my fermenter. Here I go dropping names, but my cousin John Kimmich (Alchemist) had a good idea that I stole. Also it's cheaper than a pump and a lot less likely to break down.

 

[crane]

I hope this is true! If you look a a large boil kettle,

View attachment 251129

Use can see they slightly restrict flow. I have a 3/4 and a 1" triclover in my kettle lid

View attachment 251130

I wonder if the 1" opening would be large enough? The only other issue is how to get hops in there.

All of the micros I've been at where you can see their equipment have boil kettles similar to this with a domed top and a pipe to vent the steam outside the building. I've yet to see a boil kettle with an open top.

 

[alphaomega]

Pressurized transfer through the chiller into my fermenter. Here I go dropping names, but my cousin John Kimmich (Alchemist) had a good idea that I stole. Also it's cheaper than a pump and a lot less likely to break down.

Ok, cool And yes, that IS a good idea! Just looked like something that was built to make 'shine