Ask The Brewmasters

Hi all,

We are installing a used CIP skid in our plant and adding in some items that were either not included or not needed at its former brewery. We will use a portable pump to return CIP solution from tanks back to the skid. I know that best practice is a liquid ring pump, and we actually have one that we use for yeast harvesting, but have some other questions to help us in our design. 

1. In Richard Rench's Brewery Cleaning book he calls out using a standard centrifugal pump with an air eliminator. This would be a much cheaper solution than a liquid ring pump as I've seen sanitary air eliminators for $200-500. Are there any issues with using this set up if need be?
2. Would the smartest solution be to dedicate the liquid ring pump to CIP and implement a better solution for yeast harvest? Kind of a separate thread, but from what I have read this would be a rotary lobe pump?
3. Has anyone set up signal exchange for a portable CIP return pump to feedback to a PLC on a CIP skid? If so, what was the best practice for setting up portable exchange wiring? 

Thanks!

Hi Campbell,

I've used both for CIP return and the air eliminator is cost effective but has its limitations. When it is purging air out, it tends to spit CIP solution out as well, until the pump regains prime and starts pulling it through. Thus, you have caustic or acid or whatever being shot out onto the cellar floor, right where people are working. Not ideal..although there a benefit of some localized floor cleaning! But anyone near that area may be getting spot cleaned as well. And while that pump is spitting out air, it is cavitating, which is not ideal for pump seal life. A liquid ring pump is a much nicer way to go. Pricey, yes, but they can be found at auctions or eBay for cheap, on occasion.  Best scenario is cart mounted with a VFD. 
Can't speak to wiring up communications but adding a return flow meter can be helpful to match supply and return flow rates. There are some nice, relatively inexpensive meters now that give flow, temperature and conductivity display. The latter is great for seeing the transition between cleaning solution and rinse water.

As for yeast harvest, why not just push it with CO2 pressure? If that's not right for your operation, a lobe pump can be nice for this and, again, can be found second hand. But make sure it is fully CIPable internally. Not all are, and you won't want to mess with pulling the pump rotors out to clean it every time. Check the manufacturer's website information before buying, or talk to one of their support staff. Seals for these pumps can be quite pricey, so fair warning. 
Peristaltic, or 'hose pumps', are another good option for yeast. For the amount you are probably moving, it would not need to be very large. Harder to find with sanitary connections on the secondary market though..

Philosophically, it's good to have more pumps than you think you need, because eventually you will need them.

Hi Campbell,

1) I think a critical question to resolve your pump priming and pump choice question is will you have a continuous flow CIP or burst flow? If you're continuously returning, you can balance the flow rates as Andy suggests and the pump type doesn't matter nearly as much. However, with continuous supply you risk a lot of mixing in the vessel and diluting chemicals whenever the supply changes, for example when you switch from detergent to post-detergent rinse. This can lead to sending a lot of chemical down the drain, as well as extending rinse times and rinse water volume. If you're doing a burst of supply and return, you won't have that mixing (as well as achieving impingement in the dish or cone of your vessel), but you'll need to reprime the pump after every burst. In that case, a liquid ring pump is superior. But you'll also need a flow switch or dry run sensor in the circuit to trigger the burst forward/return cycles, as well as communication between any remote sensors and the PLC, and programming in the automation.

2) I also have had great success using lobe pumps with yeast transfers. They are very low shear, can operate at low RPMs / flow rates without any damage (when accompanied by VFD), and don't lose prime. A progressive cavity pump will also work well in this situation. Netzsch makes some really nice, small, cart mounted, sanitary progressive cavity pumps that are great for yeast handling.  

3) If you have a flow switch locally on the CIP skid, you can use that to determine return flow and you don't need any remote sensors, nor communication cables. You can just have the CIP PLC fire a remote power source for the pump to activate and deactivate, such as a wall plug that runs through conduit back to the CIP skid.

Campbell,
in regards to CIP return pumps, you want self priming for reasons stated by other respondents and the most common I see is liquid ring. For this duty they are not usually on a VFD so they are constantly cavitating and thus loud. I have seen another style of self priming CIP return pump that I have used that I tried to find an example online but had no luck. The pump head is larger and asymmetric with a portion "hanging"/formed lower than normal. Maybe someone on the forum can better identify it.

In my internet searches I stumbled on the JEPS CIP return pump and Alfa-Laval LKH Prime pumps which are interesting but I have never used:

 https://texasprocesstechnologies.com/collections/self-priming-cip-return-pumps

https://www.alfalaval.us/lkh-prime

Other options are self priming and a possible solution but likely more expensive or inferior in gas air mixture pumping as I never see them used for this include: sinusoidal and screw.

As far of yeast collection I have never seen liquid ring used for this duty. Without a VFD, I would think this would be high shear and not certain even with a VFD what it would be like. I would be curious if anyone else is using liquid ring pumps for yeast collection and have confirmed yeast health is not impacted.  If the liquid ring you have will meet the needs for the CIP return then you can consider some other options for yeast recovery. Yeast recovery pump options include:
Sinusoidal (with EHEDG certification...not all have it)
Twin Screw
Lobe Pump
Hose Pump
Progressive Cavity (sanitary design...most are not)

One note on lobe pumps is a brewer needs to put a bypass around them to maintain proper CIP line velocity for cleaning as it is almost never able to allow 5ft/sec or 1.5m/sec through a lobe pump even if it is spinning 100% (unless the pump is very oversized compared to line size or portions of the lobes are machined out to allow more flow but less capacity).  A brewer may get away without the lobe pump bypass but if the lower the CIP flow rate is below 5ft/sec line velocity then there is greater the risk if insufficient CIP.

I did find one lobe pump that states “In-Line cleanability without further modifications” which I am assuming bypass is not needed. http://bestprocessequipment.com/ampco-zp3-cip.php

 
Rarely sinusoidal pumps will need a bypass so the application details need to be checked with the supplier. Twin screws almost never need a bypass.
Hope this helps,
Travis

Slant Six Consulting