Ask The Brewmasters

Hey All,

     Looking for some help trouble shooting a few issues with our GEA westfalia hb centrifuge.   Overall, it seems to run much slower than it should, usually around 10bbl/hour to get NTU output of ~75, has variable DO pick up and would also like to hit some lower NTUs.  
I didn't work here during the instal of this machine and have never ran one before.  The current procedure for everyone has been to just run the preset recipes that got set up during instal but we are looking to improve the operation of it.  We've been having a really hard time getting help from our supplier so figured I'd start here.

Anyone who could help shed some light on this would be much appreciated.  Right now we are running most beers with an inlet NTU of ~200, bowl speed of ~8,000 RPM and outlet NTU of ~75.  This gets us about 10-13bbl/hr.  
Maybe this is normal?  DO can jump from 20ppb to 100+ depending on the day and we aren't sure why.  Going to look into CO2 in solution coming out of the fermenter to see if that effects it.

Thank You!

------------------------------
Jason Brenden
Head Brewer/Director of Operations
Bridger Brewing
Bozeman MT
(218) 256-1132
------------------------------

This message was posted by a user wishing to remain anonymous

Hi Jason, 

  I have had some similar problems with their support, trying to get NTU output down and DO pick up.  First thing I would suggest is to be persistent in hitting them up for some help and don't be afraid to go up the chain if you're not getting a response. I haven't used them but I've heard that Trucent can service GEA centrifuges too.  We recently started getting some DO pick up and it was a double issue of the bowl gasket not always seating properly after every discharge and the stator on the solids tank outlet failing.  Getting DO that high is not acceptable and is a clear indication that something isn't right.  You need to find where that oxygen in coming in from.  When was your last major service?  Maybe it's time to schedule it, get all your gaskets redone and while the tech is out there, maybe go over your SOPs and your preset recipes.  Those preset recipes might not be where you need them so having someone help you dial them in and show you how to troubleshoot and adjust while you're spinning beer would be great training.    

Hard to tell you what is normal because we have different beers and different size centrifuges.  What is your target NTU?  Is it the same for all of your beers or is this a specific brand we're talking about?  The 10-13 BBL/HR is that a normal speed for you or is that you slowing it down to try and lower your NTU?  For the DO pick up, are you measuring it in the FV and then post centrifuge with a Cbox or something or do you have an inline meter?  The fact that it's jumping up and down makes me think it's an issue with the centrifuge.

Sounds like it was recently installed and there wasn't a lot of training for troubleshooting so I hope you can get someone in there soon to help you resolve all those issues.  Best of luck

The fuge is about 1.5 years old and has never been serviced after install.   It doesn't get run every day though.  The slower speed was in an attempt to drop the NTU output.  If we get much above 20BBL/hr NTU's go up into the 100+ range.  We don't target the same numbers on every beer but they are fairly close for ~70% of our beers.  Ideally, I think we would like things to be at 50 or lower for pretty much all our ales, as low as possible for most lagers.  Still new to the NTU readings so I'm not 100% on what the final targets will be...but clear!

  We have started adjusting most recipes and have had pretty good luck with getting NTU down and yield up, but it's not super consistent and DO varies quite a bit.  We are checking this with a Cbox at the fermenter, the fuge outlet, at the brite tank inlet, and in the brite tank.

Thanks for the response.

------------------------------
Jason Brenden
Head Brewer/Director of Operations
Bridger Brewing
Bozeman MT
(218) 256-1132
------------------------------

Original Message:
Sent: 01-08-2024 13:14
From: Anonymous Member
Subject: centrifuge operation

This message was posted by a user wishing to remain anonymous

Hi Jason, 

  I have had some similar problems with their support, trying to get NTU output down and DO pick up.  First thing I would suggest is to be persistent in hitting them up for some help and don't be afraid to go up the chain if you're not getting a response. I haven't used them but I've heard that Trucent can service GEA centrifuges too.  We recently started getting some DO pick up and it was a double issue of the bowl gasket not always seating properly after every discharge and the stator on the solids tank outlet failing.  Getting DO that high is not acceptable and is a clear indication that something isn't right.  You need to find where that oxygen in coming in from.  When was your last major service?  Maybe it's time to schedule it, get all your gaskets redone and while the tech is out there, maybe go over your SOPs and your preset recipes.  Those preset recipes might not be where you need them so having someone help you dial them in and show you how to troubleshoot and adjust while you're spinning beer would be great training.    

Hard to tell you what is normal because we have different beers and different size centrifuges.  What is your target NTU?  Is it the same for all of your beers or is this a specific brand we're talking about?  The 10-13 BBL/HR is that a normal speed for you or is that you slowing it down to try and lower your NTU?  For the DO pick up, are you measuring it in the FV and then post centrifuge with a Cbox or something or do you have an inline meter?  The fact that it's jumping up and down makes me think it's an issue with the centrifuge.

Sounds like it was recently installed and there wasn't a lot of training for troubleshooting so I hope you can get someone in there soon to help you resolve all those issues.  Best of luck

That sounds very slow to me, but not unheard of. For those numbers on our GEA I would expect 30-40 BBLs an hour. We do have some variance on our DO pickup, and I think a slower move could be a little higher, but that also sounds like a lot. I am always scrubbing out O2 as I move the beer and then after until I get below 20ppb. I would say I would average 40-50ppb on a move. Happy to help out with any more info.

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Kris Hough
Head Cellarman
Three Notch'd Brewing Company
Charlottesville VA
(434) 906-5142
------------------------------

Thanks Kris, we've been doing some DO scrubbing when necessary but hoping to avoid it.  I may reach out to pick your brain with a few things over the coming weeks as we work through this.

Appreciate it!

------------------------------
Jason Brenden
Head Brewer/Director of Operations
Bridger Brewing
Bozeman MT
(218) 256-1132
------------------------------

Original Message:
Sent: 01-08-2024 15:34
From: Kris Hough
Subject: centrifuge operation

That sounds very slow to me, but not unheard of. For those numbers on our GEA I would expect 30-40 BBLs an hour. We do have some variance on our DO pickup, and I think a slower move could be a little higher, but that also sounds like a lot. I am always scrubbing out O2 as I move the beer and then after until I get below 20ppb. I would say I would average 40-50ppb on a move. Happy to help out with any more info.

------------------------------
Kris Hough
Head Cellarman
Three Notch'd Brewing Company
Charlottesville VA
(434) 906-5142
------------------------------

Obviously setups will vary, but here's some things we did to get our GEA Centrifuge to a happy spot for us.  Note that it tops out at about 70bbl/hr and the slowest speed we run it is 20-25bbl / hr.

-Ensure sealing water is from a deaerated source - we have a dedicated DAW tank for this as we also produce seltzers.  If that's not an option, you could KO a batch of DAW into a small tank and then keg it for use with the centrifuge. Set up 2 HB in series to feed the 'fuge so you can swap the back one once it kicks.

-Ensure you're meeting CO2 PSI and flow requirments for your hood CO2 and any other CO2 inputs.

-Double check triclamps and all other connections - swap out silicone seals for something like EPDM.

-Ensure you aren't pulling a vaccum on the inlet side of the centrifuge.  You might need a centrifugal pump (or a larger one) feeding the centrifuge in order to give it enough flow. If you're fine there, you might need to mess with the centrifuge's outlet valve. Ours has a variable percentage it is open/closed based on the target speed.  The goal is to keep some backpressure on the bowl as that's key for proper functionality. 

-Minimize discharges - discharges will be your greatest spike in DO as you essentially need to open up the bowl for a milisecond to get your solids out.  Unless we are running hard seltzer, we have the discharges on the longest timer possible (60min for our unit) and adjust throughput speed to get the clarity we're looking for.  Operators will manually perform a partial discharge whenever turbidity goes above our thresholds.

-Don't skimp on best practices for clarity in your CCV - proper fining rates, dumping trub, etc.

-Don't expect to be able to run off the bottom of your tank. Many people talk about the great yield benefits you can get by "blending the cone".  We trialed it via various methods for a while and while it was certainly nice to have an empty tank at the end of a run, we never found the increased ejections, overall turbidity, time, and DO pickup to be worth it. 

-Centrifuges seem to really like consistency.  We run a balance line between our CCV and BBT at about 20PSI. When we don't do this, the runs aren't nearly as smooth.

Hopefully some of this helps.  Good luck with process!

------------------------------
Jeremy Castellano
Director of Brewing Operations
Mission Brewing
San Diego, CA
------------------------------

Hey Jeremy,

-Do you have any recommendations on CO2 LPM and PSI?  We are currently trying to get a PSI regulator installed as it was not installed during install.  

-We do run a pump from the fermenter to the fuge and have just started playing with the speed of that a bit to see how it effects things.  We thought maybe we were running it too fast into the fuge and pulling air on the fermenter side somewhere?  Our bowl pressure has been around 100-110psi.  At 10bbls an hour our inlet valve has been 31% open and outlet is 11% open. 

-we've also been running a balance line and playing with different pressures to see if that matters...

-have you seen much difference on adjusting bowl speed with your runs?  

Thanks for the response!

------------------------------
Jason Brenden
Head Brewer/Director of Operations
Bridger Brewing
Bozeman MT
(218) 256-1132
------------------------------

Original Message:
Sent: 01-08-2024 16:21
From: Jeremy Castellano
Subject: centrifuge operation

Obviously setups will vary, but here's some things we did to get our GEA Centrifuge to a happy spot for us.  Note that it tops out at about 70bbl/hr and the slowest speed we run it is 20-25bbl / hr.

-Ensure sealing water is from a deaerated source - we have a dedicated DAW tank for this as we also produce seltzers.  If that's not an option, you could KO a batch of DAW into a small tank and then keg it for use with the centrifuge. Set up 2 HB in series to feed the 'fuge so you can swap the back one once it kicks.

-Ensure you're meeting CO2 PSI and flow requirments for your hood CO2 and any other CO2 inputs.

-Double check triclamps and all other connections - swap out silicone seals for something like EPDM.

-Ensure you aren't pulling a vaccum on the inlet side of the centrifuge.  You might need a centrifugal pump (or a larger one) feeding the centrifuge in order to give it enough flow. If you're fine there, you might need to mess with the centrifuge's outlet valve. Ours has a variable percentage it is open/closed based on the target speed.  The goal is to keep some backpressure on the bowl as that's key for proper functionality. 

-Minimize discharges - discharges will be your greatest spike in DO as you essentially need to open up the bowl for a milisecond to get your solids out.  Unless we are running hard seltzer, we have the discharges on the longest timer possible (60min for our unit) and adjust throughput speed to get the clarity we're looking for.  Operators will manually perform a partial discharge whenever turbidity goes above our thresholds.

-Don't skimp on best practices for clarity in your CCV - proper fining rates, dumping trub, etc.

-Don't expect to be able to run off the bottom of your tank. Many people talk about the great yield benefits you can get by "blending the cone".  We trialed it via various methods for a while and while it was certainly nice to have an empty tank at the end of a run, we never found the increased ejections, overall turbidity, time, and DO pickup to be worth it. 

-Centrifuges seem to really like consistency.  We run a balance line between our CCV and BBT at about 20PSI. When we don't do this, the runs aren't nearly as smooth.

Hopefully some of this helps.  Good luck with process!

------------------------------
Jeremy Castellano
Director of Brewing Operations
Mission Brewing
San Diego, CA
------------------------------

Centrifuge DO issue and lack of clarity can be driven by many factors.

One challenge with the question is the model HB centrifuge was not mentioned and the different models have different capacities. Another challenge is the inlet turbidity was mentioned in NTU which is a turbidity unit but normally we would think of machine capacity in % volumetric solids. Different materials can increase inlet turbidity without increasing percent solids (think oats used in the brewhouse or glycogen haze from poor yeast health). Finally, even the same model machine can come with a short, medium or long disc stack changing the machine performance and comparability.

Another interesting item to understand is does the machine start up well and then loses clarity over the run (assuming steady incoming solids). Another thing to explore while having issues is if three or four full size shots in a row (as fast as possible) recover the performance of the machine?

Because of all these factors I am assuming the machine used to perform well and that the inlet solids have not changed.

Here is a list of points to consider in rough likelihood:

1)      Solids plugging the disc stack reducing surface area

a.       Too many root cause drivers to list…so after CIP open machine and inspect disc stack and if indeed solids are still present then can pursue this issue further

2)      Improper machine assembly after overhaul or maintenance or failed seal that is letting inlet beer mix with clarified beer

3)      Improper rpm (not likely)

In regards to DO pick up issues again a list in rough order of likelihood (ignoring issues outside the machine):

1)      Running slower than machine design will cause cavitation in the paring disc due low inlet pressures which allows the hydro hermetic seal water and then air to enter the process flow raising the beer DO

a.       This can be offset to a degree (with limits) by varying the outlet pressure to keep the liquid in the paring disc on the "pump curve"

b.       Your supplier should be able to provide the pump curve for your machine so you are aware of the limitations

c.       One note, in my experience seal water on hydro-hermetic machines is not normally deaerated water but of course confirm with your manufacturer what you should use

                                                               i.      If deaerated water is not required by the manufacturer but a brewer finds it helps lower DO then it is likely the machine is being operated in a manner that seal water is being drawn into the process flow

2)      Insufficient CO2/N2 purge around the bowl

3)      Insufficient seal water flow

4)      Damage to the paring disc due to long term cavitation exposure (months) leading to less pumping capacity and changing the pump curve leading to DO pick up

5)      Bad seals allowing oxygen in

Hope this helps and reach out if you need any help.

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Travis Audet
Slant Six Consulting
Hooksett NH
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Jason you already have gotten a ton of great advice.  The only thing I would like to add is that optimal centrifuge operation is very much about the turbidity measurement and the bowl shoots.  A bowl shoot that is too short will not clean the bowl and you will end up with turbid beer, and the beer flow will be controlled to a low flow rate basis that high turbidity.  More than one bowl shoot may be necessary to clean the bowl, if the turbidity doesn't drop back down to what is normal for your beer  afterward.  Each beer has a different natural clean beer turbidity so turbidity set points for bowl shooting need to be adjusted accordingly.  If the bowl shoot is too long then the beer will pick up DO and you will lose good beer into the solids stream.  Make sure your turbidity measurement is performing as you expect.  Obviously the diluent used for seal water and bowl shoot needs to be DO free.  I remember spending long hours watching centrifuge operation and fiddling around with set-points before automating the bowl shoot turbidity set points to be dynamic, based on the clean beer turbidity that was being fed into the centrifuge.

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Vincent Coonce
Consultant
Optimal Process Solutions
Reedsville WI
(414) 550-4403
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UPDATE

I wanted to give everyone who chimed in, and future reads, an update.  We have been working extensively with Kenneth McCullough with GEA the past week and he helped us get things dialed in.  We had a lot of changes that needed to be made to get things running smooth.   It was pretty eye opening the amount of variables to factor in with all of the small adjustments that can be made deeper than just adjusting the obvious things.  Too many things to list on what we changed for this specific round of trouble shooting but speeds have doubled with improved clarity and way better/more consistent DO numbers.  Basically I just wanted to post a shout out to Ken for taking the time to spend many hours on video chats with us to get things running well.

------------------------------
Jason Brenden
Head Brewer/Director of Operations
Bridger Brewing
Bozeman MT
(218) 256-1132
------------------------------