Perhaps the spent grains is too dry?
Hey Guys, Long time reader, first time poster so here's my introduction if anyone cares. Names Danny and I'm an Industrial Mechanic at the Saint Louis Brewery (Schlafly brand beers) in St. Louis Missouri.
So, now that that's out of the way, I have some questions about the progressive cavity pumps that you're using to move spent grain.
We are having to replace our stator about every three months which adds up pretty quickly(around $1300 each go around) Our pump supplier seems to think that this is very unusual to have to replace the stator this often, but hasn't been very helpful about finding a solution. I think they like that 1300 dollar sale every three months.
We're using a Netzsch NEMO pump that discharges into about a 100 foot run of a 6" stainless pipe. There is around 40 foot of discharge head, and pumping around 100psi at the outlet of the pump. According to the pump curves I've seen, everything says that our pump is sized correctly.
Currently We're churning out around 60,000 bbls a year which can give you an idea of how much this pump is used, I can also get stator run time when I'm back at the Brewery (it resets every time we change a stator)
Does anyone out there have a similar setup as us Or have any suggestions?
What brand pumps are you using and what kind of life are you seeing out of your stator?
Thanks Guys, any help is much appreciated!
Perhaps the spent grains is too dry?
Super D I am assuming you mean the field winding in the pump motor which is of course the stator.
I am going to direct you to Mike Holts Electric Forum and look for a Guru there named JRAEF.
There are aspects of your setup that will require more information such as the nameplate specs on the motor along with the supplied voltage and operating currents you are seeing. Also, if its on a VFD, all of that info as well.
IN your case a datalogging meter that can record amps over time might be considered helpful.
The minds on that forum should be able to help.
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Thanks for the reply's.
Starcat I'm not referring to the motor; Progressive cavity pumps share some nomenclature with electric motors. : http://www.enggcyclopedia.com/wp-con...SSECTION11.bmp
grnis, the spent grain is the consistency of oatmeal when it is at the pump, manufacturer thought that this was fine.
We have the same issue with our seepex brand progressive cavity pump. We do about about 15,000bbl and year and sure enough right before the year is up the stator starts getting real slow. Our stator cost about the same and the line runs are about the same. Our pump company said we were running to dry. So we ran wet and no improvement. They then sold us a tension device and said it would give us 3 times the life and that cost us another two grand and when we got it we found out all it is is a pipe repair clamp. That also didn't extend the life one extra day.
All in all I don't think local pump companies know much about brewery needs and they also like the cash flow from replacement parts. I've been looking at the Xeric pump from roper pump company. It uses a stainless steel stator that has zero contact so nothing wears down and nothing to replace. I saw the thing in action and it will pull a vacuum and you can run it dry no problem.
I would really like to hear more thoughts on spent grain pump solutions.
Do you have a flow switch on the pump? If the pump runs empty, the stator heats up and will be destroyed. You are basically using the spent grain (or water) to remove the heat from the pump.
Additionally, you should have a water feed upstream of the stator to prevent the pump from running dry.
Finally, yes, if you have to have very dry spent grain, a progressive cavity may not be the best solution.
Overheating can cause premature stator wear. WHat type of thermal monitoring/protection do you have on the stator? We burned one out within a couple months of installation and turned down the thermostatic cut-off and have been running with the same stator for the last 2 years.We also have Netzsch.
We did have Temperature monitoring at some point before I worked here and for some reason it was deemed unnecessary and removed, or broke and was never replaced. Our Brewers are pretty conscientious about keeping water in the hopper toward the end of grain outs but I guess it wouldn't take much more than a few times running dry to tear that stator up. Thanks for the help guys, ultimately I think we might end up going with that Xeric retrofit, but will also likely implement temp monitoring and a water valve.
Consider using a pondorff type air blow system rather than a pump. 100 psi and 100 ft run is a lot for any pump to run at on a regular basis, though I accept it obviously does - up to a point. The breweries I have worked at with any sort of run like this have all used air for transfer of fluidised draff. Again, not perfect, and occasionally suffer blockages, and need to be designed correctly with large radius bends etc. Also I accept that air is expensive to produce in the quantities required for short bursts such as required by spent grains transfer.
Roper’s Xeric progressive cavity grain-out pumps don’t require any type of sensors on the inlet or stator. With a metal on metal (no elastomer) design the pump can safely run dry without causing any damage to the unit. As the rotor and stator fit is a clearance – as opposed to interference on a rubber lined pump – the temperature when running dry doesn’t spike. Even with a clearance fit the pump can deliver twice the pressure per stage compared to an elastomeric pump which equates directly to faster grain-out times. We can also upgrade most PC pumps in the market today to XERIC technology. It’s a fairly simple process that involves taking the rotor and stator off your existing pump and replacing it with our Xeric design; we’ll even help with the change out. There’s no need to replace the whole pump or modify piping and we offer a 2 year warranty on the upgraded pump element. Roper has been producing progressing cavity pumps since 1972 and originally developed the technology in our XERIC for downhole drilling. If you have any additional questions feel free to reach out to us via Probrewer or our website.
XERIC - Brewery Grain out pumps