Centrifugal Pump and Hop Recirculation

[kthomlinson]

Hello Everyone,

I recently came across a doctoral thesis about hops. The paper claimed more or less that by continually recirculating dry hops for a day, there was up to a 40% better utilization of aroma.

We experimented with adding the dry hops through a port at the top of our fermenters (20# into 30 BBLS) and then agitating the hops by pushing CO2 into the racking arm for 10 minutes at a time, four days in a row. We perceived a significant aroma increase and a little bit of flavor difference.

My brewing team and I would like to get away from putting the hops directly into the fermenter and exposing the beer. We would rather put the hops into a sanitized yeast brink. Purge the brink with the dry hops inside, back fill with beer, and then recirculate the slurry into our fermenter. We would then recirculate for 24 hours as suggested by the doctoral thesis.

Our fear is that the pump will create a vacuum and collapse the tank in on itself or pull O2 through the PRV. The plan would be to use a 15.5 gallon brink with a centrifugal pump set relatively low.

Any thoughts or tips?

Thanks!

[JDN]

We did something similar, though on a much larger scale at the last place I worked (~10bbl brink and 400-1000bbl FVs).
It worked great. The way you describe recirculating on the tank won't lose pressure in the tank because it's a closed loop. I would, however pressurize the FV to 7-10psi to be safe and keep an eye on it. We usually saw pressure rising in the FV as the hops and turbulence knocked co2 out of suspension.

I'd be wary of running the pump for 24 hours if you aren't a 24hr a day operation.

[Beer_Nut]

That's how Sierra Nevada does it, although they use whole cones. I've toyed with the idea of trying it in our brewery, but that is about as far as I've gone with the idea. The fact that utilization is increased is appealing though.

[Bainbridge]

We recirculate our dryhops using our mobile pump. In from the racking arm, out right up the center of the cone. Run her about an hour, let things settle. Repeat again a day or two later, or in the case of our triple IPA every day, just to kick things back up into the beer column. Figure they aren't doing much good sitting in a big pile down in the cone.

[kthomlinson]

I thought about running the pump with a little pressure on the tank, but I didn't know if that would cause the pump problems. Its good to know that wasn't an issue.


[QUOTE=JDN;131361]We did something similar, though on a much larger scale at the last place I worked (~10bbl brink and 400-1000bbl FVs).
It worked great. The way you describe recirculating on the tank won't lose pressure in the tank because it's a closed loop. I would, however pressurize the FV to 7-10psi to be safe and keep an eye on it. We usually saw pressure rising in the FV as the hops and turbulence knocked co2 out of suspension.

I'd be wary of running the pump for 24 hours if you aren't a 24hr a day operation.[/QUOTE

[sopbeer]

Recirc

At What Hrtz are you running your VFD's for the recirc pump? Just curious if there is and optimal.

[kai]

A centri pump won't be able to pull a vacuum sufficient to implode a tank. If there's not enough pressure for the centri pump to pull the hop slurry into the pump, it will just cavitate.

Either way, running the system under pressure is your better option.

[drewseslu]

I have used a grundy tank to make a slurry with hop pellets and recirculated it back into a 60bbl FV until it was homogenized, it only took a couple hours. The results were very good.

More standard practice at the time was to fill a modified 7bbl FV with whole flower hops and set up a loop to a FV, usually a 120bbl, with a small pump set on a timer to run a few minutes out of each hour, maybe 10, and let it go for 5-7 days. This also worked very well.

There was also a small, pressure capable grant we could load hops into and then pump into an FV, this didn't work as well since the grant wasn't large enough to let the pellets soak up beer until loose, and the pellets would end up clogging up a butterfly valve or hose.

At the last brewery I ran, I decided to dry hop like this:
- Harvest yeast from fermented, bunged and crashed beer, send remaining flocc'd yeast to drain
- Add dry hops to another, cleaned and sanitized FV, then purge & pressurize
- Transfer beer in under dry hops into the receiving FV (keep cold and pressurized)
- Leave hops in beer for 5-7 days, then start dumping them off the bottom
- Once cleared, send to BBT

This time around I will likely be adding the hops at bunging/d-rest until I can get a slurry tank.

[Ted Briggs]

Hello Everyone,
I recently came across a doctoral thesis about hops. The paper claimed more or less that by continually recirculating dry hops for a day, there was up to a 40% better utilization of aroma.

Link to this paper?

[BMan1113VR]

Link to this paper?

http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/34093/Wolfe_thesis.pdf

I am assuming this is the one he is talking about.

[GritCity]

Do any of you guys have worry over oxidation using centrifugal pumps to recirc?

[Smlsound]

Do any of you guys have worry over oxidation using centrifugal pumps to recirc?

I had the same thought. I think it would be easy/desirable to set up a T connecting the pump-feed hose to the tank. You could then hook in a butterfly valve/quick disconnect/drug of choice for adding co2 and purge the circuit until co2 is coming out of the pump-out hose. Continue the flow while you're hooking up the pump-out hose to the tank and I would assume you've expelled most of the O2.

[beermkr]

What about using a stainless hot water circ pump like a

http://www.supplyhouse.com/Taco-006-ST4-006-3-4-Threaded-Stainless-Steel-Circulator-1-40-HP-15052000-p?gclid=CjwKEAjw5disBRCA5r7OjsK_-UgSJAC27JPg6qiMW_v4INYMt6Ez47cvBwL3880NuTQ-xBoqo9QCEBoCFgnw_wcB

I realize that the threads could be an issure but if TC fittings were installed and deinstalled each time it would allow cleaning and sanitation.