Breweries move lots of liquids around the plant including wort, beer, spent grain, CIP solutions, process chemicals and utility/service waters.
For each application there are pumps available to optimize the process.
In small brewpub operations there may be only one pump that is called upon to serve many different duties and that workhorse pump can be fitted with a variable frequency drive (VFD) to make it more flexible for duties that can allow for both gently moving wort and beer to high capacity and high flow cleaning operations.
Essentially, in the world of pumps there are two basic categories, each containing different types that can be tailored to different applications.
The two main categories are positive displacement and centrifugal.
Centrifugal pumps are the most commonly used and least expensive pumps for moving a variety liquids in the plant but do have their limitations.
Centrifugal pumps have a housing with an inlet (usually in the center) and an outlet coming tangentially off the housing.
Inside the housing is an impeller with curved blades.
The pumps work by spinning the impeller and circulating the liquid around the outside of the pump housing creating a vacuum at the inlet of the pump which draws in liquid.
Centrifugal pumps can be self-priming (flooded inlet housing with top discharge), but typically need to be located under the process tank so that there is a certain amount of gravity to feed the inlet (net positive suction).
The inlet feed should be oversized (i.e., feed a 2” inlet with a 2.5” or larger pipe) so that the pump is not “starved.”
Centrifugal pumps can pump against a closed valve without significant pressure build up but can overheat and damage wort or beer if allowed to pump against a “dead head” for long periods of time.
They are commonly used on keg washer tanks where they run constantly while valves open and close but should not be allowed to run dry as this will cause damage.
Figure 1. Cart pump with a VFD drive attached, used for moving beer at lower speeds,
it can be used for tank CIP using higher speeds and output.
Low speed sanitary 3-A designed stainless steel centrifugal pumps are the workhorse of the brewhouse and commonly used to pump mash to the lauter tun, lauter runnings to the brewkettle, knock out wort to the whirlpool and hot wort through cooling to the fermenters. In the cellars they are typically employed to move beer from the fermenters through the rest of the process. Normally the delicate mash, wort and beer pumping processes use high volume but low pressure flows utilizing low speed (1725 rpm or less) motors to reduce foam and mouthfeel destroying shear forces. Hot wort applications will normally require a double mechanical water-flush seal to extend pump seal life.
Centrifugal pumps are also used in more severe duties, i.e. recirculating CIP solutions and on bottle washers and pasteurizers using high speed motors (3600 rpm) to produce higher pressure and flows.
Figure 2. Centrifugal pump used for a CIP station, note the in-line strainer on the output to
remove debris that might clog a CIP cleaning head in the tank being washed.
The pump construction for these duties is typically stainless steel but depending on the application 3-A sanitary ratings may not be required. Pumps on chemical systems will typically use a water flush seal to extend seal life.
Positive displacement pumps differ from centrifugal pumps with the ability to self-prime (do not require a gravity feed) and the capacity to gently pump large amounts of liquids in a more controlled manner against high pressure. They can also be used to pump thick materials like yeast and DE slurries at a fairly high volume. Positive displacement pumps cannot be pumped against a closed valve without generating a significant and potentially dangerous amount of pressure, they should never be allowed to run dry. They are used in breweries in a variety of applications including:
- Spent grains
- Yeast pitching
- Finings injections
- DE feed pumps
- Beer transfers
- Boiler feed water
There are a variety of positive displacement pump styles to choose including:
- Helical screw pumps, “Moynol” style, using a rotating helical screw inside a rubber stator housing, each movement of the screw pushes a contained amount of liquid forward. These pumps can move thick slurries like spent grain, spent hops, and spent DE.
Figure 3. Helical screw pump used to move spent grain.
- Rotary lobe pumps can be sanitary 3-A design for yeast injection or beer movement including centrifuge and filler supply. When fitted with a VFD they feature gentle, controlled product movement.
Figure 4. Sanitary stainless steel rotary lobe pump used to move beer from fermenters.
- Hose pumps use a hose fitted on the out edge of a housing that includes a rotating lobe impeller in the middle. As the rotor moves it creates suction in the hose and draws the liquid in and trough the housing. These types of hoses make idea injection pumps for finings and DE.
Figure 5. Hose pump used to inject finings.
- Piston pumps are used mainly for service or utility applications requiring high pressure discharge like boiler feed or chemical dosing applications but are also commonly used to supply label glue to the labeler.
Figure 6. Piston pump used to supply thick label glue to a labeler glue roller.
- Double Diaphragm pumps use compressed air to move two rubberized diaphragms back and forward creating suction and discharge with each stroke. The pumps can be set to run at a particular pressure and will stop operating if they achieve that amount of pressure resistance.
Figure 7. Diaphragm pump used to draw off yeast from a fermenter,
could also be used to inject chemicals into a CIP system or pump away trub from a whirlpool tank.
There are a number of pumps available that can facilitate each duty in the brewery. Talk to your pump supplier to ascertain the most effective pump for the application you are looking for. They will also help in sizing the pump for the duty requirements.