Help me invent a rotating dry hopper

[thefost]

Ok so this is pretty weird =]
I want to build a rotating dry hopper.

Lets say I have beer in a corny keg. I want to stick some hops in a small container and put that container in the keg. I want to attach the container to the lid of the corny keg, which will then be attached to a motor on the outside of the keg.

Here is a terrible drawing of the idea:

So the only issue is the thing I need to install in the keg lid. It ideally should be pressure capable and sanitary. Some sort of full enclosed pressure capable bearing would work, but I don't think that exists.

So I'm looking for ideas on how to do this. Any ideas greatly appreciated!

The easier way to do this would be to stick the keg on a rotating platform, but that would require a lot bigger motor, so I want to exhaust all options for the dry hop spinner first.

 

[chezhed]

uhhhhh.....why?

That's going to be awfully difficult. You will have to encase a bearing in a pressure lock with gaskets on the bottom (probably not enough room on top) of the keg top and figure out how to "lock" down a motor/shaft assembly and press fit (interference fit) it to the bearing...and then have a coupler to the shaft on your hop container. The bearing case would best be welded to the lid....

Seems like a whole lot of engineering and work.....I created a quick diagram and will try to get it...really slow to upload from Mexico

 

[jbaysurfer]

Do dizzy dryhops smell better?

 

[TrickyDick]

Was an article in zymurgy or BYO, forget which, where they build a kettle hopping device for making a continually hopped IPA. I built one. Never used it. Doubt it could be built as you've described with respect to pressurize-able and sanitary. At least not inexpensively.

TD


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[number40fan]

I don't think it would be horribly difficult to make, but I don't see a reason why you would want to spin the hops.

 

[dlaramie08]

Dry hops are extremely delicate animals. I think this would only end up making some lupulin dust and a bunch of loose leaves.


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[thefost]

uhhhhh.....why?

Ya know, I seem to get that question in a lot of my threads

That main reason is that recirculating liquid through hops will extract oils faster and more efficiently. You can read about it in this thesis if you want: http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/34093/Wolfe_thesis.pdf?sequence=1
Also been discussed plenty of other places. Moral of the story is 1 hour of recirculating beer though dry hops will give you better aroma than 10 days of passive dry hopping.

I've experimented with recirulation, but then this spinning hopper idea popped in my head. I had no idea if anything like I'm describing exists to spin this thing, but its worth a shot.

And I guess the main reason I'm asking is, I just like building strange contraptions to experiment with new techniques.

Seems like a whole lot of engineering and work.....I created a quick diagram and will try to get it...really slow to upload from Mexico

Would love to see that diagram! =D

 

[thefost]

Dry hops are extremely delicate animals. I think this would only end up making some lupulin dust and a bunch of loose leaves.


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Agreed, if I did this I would be spinning them extremely slowly

 

[YeastMode]

Crazy thought....why not make what would basically be a giant stir plate? you can sit the keg on it, and have the hops spin inside by using a large stir bar?

 

[johngaltsmotor]

I've experimented with recirulation, but then this spinning hopper idea popped in my head.

I would think that recirculating through a hopback would have to be easier and more effective. Plus being on the outside of a keg you only need 1 for your fleet of kegs instead of modifying every keg lid.

 

[Bensiff]

Oxygen is going to be an issue here. I'd think it would be better to flush a hop back with co2 and recirc or for a single infusion do a nice slow transfer.

 

[grainbill]

Seems way to complex. Why not just make a "Randle" since you are kegging anyway...

 

[Peyope]

Crazy thought....why not make what would basically be a giant stir plate? you can sit the keg on it, and have the hops spin inside by using a large stir bar?

Seems like it would get caught on the dip tube.

 

[chezhed]

I would think that recirculating through a hopback would have to be easier and more effective. Plus being on the outside of a keg you only need 1 for your fleet of kegs instead of modifying every keg lid.

Now I like that idea....seems like all you would have to do is "transfer" from one keg to another and pass it through a "special" hopback, one with an internal chamber that would spin as fluid flowed in

 

[Brettomomyces]

Wonder what a sonicator big enough to handle a keg would cost. That would be an interesting idea, vibrate the whole vessel during dry hopping.

 

[ArkotRamathorn]

Wonder what a sonicator big enough to handle a keg would cost. That would be an interesting idea, vibrate the whole vessel during dry hopping.

If you had the right sound equipment, couldnt you just jam a subwoofer or something up against the keg and play a sound at a really high frequency that humans cant hear and vibrate the hell out of keg. Basically just brown noise your kegs.

On a serious note, I guess the first thing I thought of was putting the keg (sealed with hops and beer inside) on a sort of U shaped base with wheels inside the U, place the keg on its side inside the U, then it shouldn't take a lot of power but a little rubber wheel that spins the keg in place slowly connected to an electric engine of some sort. Bonus points connect it to a bicycle wheel or something, good excercise, then you could brag about how you pedaled your beer into deliciousness.

 

[Brettomomyces]

There are people doing something like that with wine, actually putting a speaker into the wine itself during the aging.

 

[chezhed]

anybody ever pressure test a bucket with a lid?....curious if a bucket used as a secondary would handle the pressure of transfer to a keg if rigged up properly incorporating this external hop spinner
fun for the weekend!!! pressure test a bucket...oh boy, wait till the neighbor hears this pop....though I do think I might ruin a good bucket lid in the process.... roflmao

 

[feinbera]

Maybe you could disassemble one of those pumps where the pump head is magnetically coupled rather than physically coupled to the motor? That way you wouldn't have to breach the wall of the keg, although it's been way too long since I've taken a physics class for me to tell you if the magnetic coupling will worth though a metal keg wall...

...of course, if you're gonna sacrifice a pump to the project, you might as well just pump through a hop back and still have a pump you can use for other beer-moving applications.

 

[feinbera]

On a serious note, I guess the first thing I thought of was putting the keg (sealed with hops and beer inside) on a sort of U shaped base with wheels inside the U, place the keg on its side inside the U, then it shouldn't take a lot of power but a little rubber wheel that spins the keg in place slowly connected to an electric engine of some sort. Bonus points connect it to a bicycle wheel or something, good excercise, then you could brag about how you pedaled your beer into deliciousness.

Rock-a-bye-Keg(tm) It could be painted a nice pastel yellow, with pink and baby blue duckies and bunnies...

I think you'd have to have little walls or spikes or something on the inside of the keg, though, to keep the beer, or at least the hops, from simply sitting in the lowest part of the keg, while the smooth wall rolled by underneath with minimal resistance. Think of a hamster wheel – the hamster just stays in the bottom of the wheel, no fuss, no muss, no matter how fast he's running. Now, imagine the hamster wheel with hurdles...

 

[ArkotRamathorn]

Rock-a-bye-Keg(tm) It could be painted a nice pastel yellow, with pink and baby blue duckies and bunnies...



I think you'd have to have little walls or spikes or something on the inside of the keg, though, to keep the beer, or at least the hops, from simply sitting in the lowest part of the keg, while the smooth wall rolled by underneath with minimal resistance. Think of a hamster wheel – the hamster just stays in the bottom of the wheel, no fuss, no muss, no matter how fast he's running. Now, imagine the hamster wheel with hurdles...

Could throw a bunch of sanitized steel ball bearings inside. Bonus you could make the loudest most annoying sound ever. Are the tops and bottoms of Kegs super smooth? I guess I figured there'd be something on the inside to help get the whole thing swirling.

I think I just invented a keg destroyer. I can see the advertisements "Need to destroy your legs in 15 minutes or less?".

 

[dlaramie08]

Agreed, if I did this I would be spinning them extremely slowly

Ha! I don't know why but I read this as you were rotating the hops as you dried them. I was very confused about the whole thing. Proceed.


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[thefost]

This thread is too funny =]

Ok I'm going to respond to a few posts

Crazy thought....why not make what would basically be a giant stir plate? you can sit the keg on it, and have the hops spin inside by using a large stir bar?

That's a great idea, but I don't think it would work because the stainless steel keg is itself magnetic.

I would think that recirculating through a hopback would have to be easier and more effective. Plus being on the outside of a keg you only need 1 for your fleet of kegs instead of modifying every keg lid.

I might actually be one of the only people to ever do that, see this thread: https://www.homebrewtalk.com/f11/corny-keg-recirculating-dry-hopper-482964/
Works pretty well!

Oxygen is going to be an issue here. I'd think it would be better to flush a hop back with co2 and recirc or for a single infusion do a nice slow transfer.

Why would oxygen be an issue with a pressurized keg?

Seems way to complex. Why not just make a "Randle" since you are kegging anyway...

Randals seem to give a different flavor, ends up grassy and earthy to my taste buds - not a flavor I really like. I much prefer dry hopping at warm temperatures then using gelatin. But yes, this is way too complex, which is what makes it fun!

Wonder what a sonicator big enough to handle a keg would cost. That would be an interesting idea, vibrate the whole vessel during dry hopping.

I hadn't even thought about audio, now that is a sweet idea!

I also like the rock-a-bye keg.

As for the hampster wheel analogy... you'd really have to sanitize that hampster before putting him in the keg.

 

[TrickyDick]

Most stainless steel isn't non-ferromagnetic. Have you tried seeing if a magnet will stick?




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[max384]

Why not instead just dry hop in the secondary (or primary if you don't use secondary fermenters) with a spinning dry hopper. You could simply dump the hops in, and then have a stirrer that would stir it all together and get the agitation you desire, but without having to overcome all of the pressure issues with doing this in the keg. Just make sure that it is reasonably airtight to avoid oxygenation during stirring.

I wouldn't mess with my keg lids. I'm sure the guy you pay to refill your CO2 tanks would support this idea though. lol

 

[thefost]

Why not instead just dry hop in the secondary (or primary if you don't use secondary fermenters) with a spinning dry hopper. You could simply dump the hops in, and then have a stirrer that would stir it all together and get the agitation you desire, but without having to overcome all of the pressure issues with doing this in the keg. Just make sure that it is reasonably airtight to avoid oxygenation during stirring.

I wouldn't mess with my keg lids. I'm sure the guy you pay to refill your CO2 tanks would support this idea though. lol

Yeah I've pretty much abandoned the original sketch idea. I was hoping something already existed that I could use to keep it pressurized, but looks like that's unlikely. I could definitely use some kind of stirer and try to keep it sanitary without introducing o2.

 

[thefost]

Most stainless steel isn't non-ferromagnetic. Have you tried seeing if a magnet will stick?

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Interesting, I know magnets stick to my sanke keg but I haven't tried a corny. Will give it a try tonight.

 

[max384]

Interesting, I know magnets stick to my sanke keg but I haven't tried a corny. Will give it a try tonight.

They're made of stainless steel, so they shouldn't be magnetic, or very weakly magnetic, depending upon the ferritin content of the stainless steel used.

 

[Bensiff]

I don't see how you are going to do this without allowing oxygen into the system. When you stir you will also disturb the airspace which will lose you the benefit of the CO2 blanket. If you do a multiple step dry hop you will compound the problem every time you open the system to add new hops.

 

[thefost]

I don't see how you are going to do this without allowing oxygen into the system. When you stir you will also disturb the airspace which will lose you the benefit of the CO2 blanket. If you do a multiple step dry hop you will compound the problem every time you open the system to add new hops.

Well the original idea was to add the hops, then purge the airspace with co2, then spin the liquid in a pressurized environment.

However, even if I didn't pressurize the keg and started spinning it some other way, I think the CO2 blanket would still be fine. I mean, we use stir plates all the time and that doesn't seem to oxidize the starter wort. Not sure how this is any different.

I'm with you though, I want to make sure there is 0% chance of oxidizing.

 

[thefost]

Ok here's another silly idea, basically stick the motor in the keg

Take a cup and attach it to the top of the dry hopper. Stick a battery powered case fan in there, remove the fins so its not circulating air. Case fan spins one way in floating cup, dry hopper spins the other way.

 

[max384]

Well the original idea was to add the hops, then purge the airspace with co2, then spin the liquid in a pressurized environment.

However, even if I didn't pressurize the keg and started spinning it some other way, I think the CO2 blanket would still be fine. I mean, we use stir plates all the time and that doesn't seem to oxidize the starter wort. Not sure how this is any different.

I'm with you though, I want to make sure there is 0% chance of oxidizing.

The entire point of using a stir plate IS to oxygenate the starter wort. That is literally the only reason we use stir plates when making starters. The yeast starters are done to maximize growth, not to create alcohol. Yeast grow and replicate much better in an oxygenated environment using aerobic respiration. If they are forced to, they will utilize anaerobic respiration (alcohol is a byproduct of this), but this is a much more energy inefficient process, and thus replication will not occur as rapidly as it would if they were able to use aerobic respiration.

This being said, if you have a CO2 blanket and it is airtight, than stirring won't introduce oxygen into the system. However, if your system is not airtight and oxygen is able to get in, than stirring can and probably will introduce oxygen into your beer.

Ok here's another silly idea, basically stick the motor in the keg

Take a cup and attach it to the top of the dry hopper. Stick a battery powered case fan in there, remove the fins so its not circulating air. Case fan spins one way in floating cup, dry hopper spins the other way.

I'd worry about sanitation issues with this idea. How are you going to adequately sanitize the motor and batteries? And to tell you the truth, I wouldn't be crazy about having that stuff in my beer vessel even if it were sanitized.

 

[KegWrangler]

Why not just put the keg on a lazy-susan. Then it would just take a small motor to keep the whole thing spinning since the only energy input needed is to overcome the friction of the ball bearings.

I'd try it with a remote control car motor - those have some pretty good torque.

 

[hungry4hops]

Lay the keg on its side and figure out a way to roll it like one of those hot dog rollers lol

 

[thefost]

The entire point of using a stir plate IS to oxygenate the starter wort. That is literally the only reason we use stir plates when making starters. The yeast starters are done to maximize growth, not to create alcohol. Yeast grow and replicate much better in an oxygenated environment using aerobic respiration. If they are forced to, they will utilize anaerobic respiration (alcohol is a byproduct of this), but this is a much more energy inefficient process, and thus replication will not occur as rapidly as it would if they were able to use aerobic respiration.

I always thought the stir plate mainly introduced oxygen at the beginning of the starter. Then when the starter wort starts fermenting a blanket of co2 is created and the starter wort no longer is getting oxygenated, and the stirring is mainly to keep the yeast in constant motion for better contact with the wort. Is this incorrect?

 

[max384]

I always thought the stir plate mainly introduced oxygen at the beginning of the starter. Then when the starter wort starts fermenting a blanket of co2 is created and the starter wort no longer is getting oxygenated, and the stirring is mainly to keep the yeast in constant motion for better contact with the wort. Is this incorrect?

Sorry, but this is indeed incorrect. Continual oxygenation is the purpose of a stir plate. The agitation produced by the stirring also disrupts the blanket of CO2 on top, thus allowing air flow (as opposed to stagnant water, where there is nothing to move the heavier blanket of CO2, and it does a much better job protecting the beer from oxygen). This is why aluminum foil is loosely wrapped around the top of a flask, rather than an airlock. You want air flow in and out of the flask when making a starter.

 

[grainbill]

maybe.. if you could retrofit another pressure relief valve and run the "drive shaft" through the retro fit?

 

[Bensiff]

When you grow a starter you are doing two things, intentionally introducing oxygen to grow biomass and doing so in a low gravity solution so as to avoid the Crabtree effect. At this point, like the growth stage of yeasts cycle when pitching into wort, oxidation is a non issue. Once the sugars are exhausted and the yeast have gone dormant is when oxidation becomes a particular problem. Now if you could run a sealed fermentation and install one of those little rotary fish food automated feeders on the inside of the fermenter and set it to do your dry hop additions without opening the container you would have little to no worry about oxidation. Of course you would still have to figure out how to stir it.

 

[biertourist]

Recirculation is the obvious solution for what you're trying to do.

If you're worried about dry hopping time, warmer temperatures also enable more oils to go into solution faster and pellet hops enable hop oils to go into solution faster than whole hops.

SOO if ultra rapid "dry hopping" is your goal, then you want a conical fermenter; dump all yeast / trub after primary fermentation is complete (yeast pull hop oils out of solution as the oils stick to the cell surface), then add your dry hops and recirculate through a pump pulling beer out of the very bottom of the cone and returning to the top of the fermenter or the top of the cone if the conical has a racking cane fitting at the top of the cone.

If you have a whirlpool kettle you could transfer from your fermenter back into your kettle for your "rapid dryhopping" and pump through the whirlpool; -this would make transfering off of the hop pellet crud and back into your fermenter also easy.

Just pumping liquid through a hop back, as has been said multiple times isn't a bad idea, but you want to fill the hop back from the bottom up slowly and then seal it to avoid oxygenation.

If you are doing this whole thing cold, it will take a bit longer, but it's more akin to Sierra Nevada's Hop Torpedo system.

The rotating dry hopper is not the right solution for what you're trying to do; if you just want to do it because you just want to make a rotating dry hopper in a pressurized vessel, that's a totally different issue; just proceed with the unnecessary crazy in that case.

-For what it's worth, recirculation during fermentation also makes fermentation proceed faster, so a gentle pump that can recirculate through a conical could pull double-duty, if you're interested in turning over lots of hoppy beer rapidly.

Adam

 

[TrickyDick]

Lay the keg on its side and figure out a way to roll it like one of those hot dog rollers lol

Roller dog IPA!!


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