Case Study- Helicoidal Impeller Pump for Mash Transfer

At Triplex, we specialize in helping customers with their hard to handle fluid transfer applications. Recently, a brewery in the St. Louis area contacted us because they were having trouble transferring mash with their flexible impeller pump. While flex impeller pumps are widely used in craft breweries as well as distilleries for mash transfer, this customer’s pump just wasn’t keeping up. So what is a helicoidal impeller pump and why was it the solution? Let’s take a closer look.

Let’s start by understanding the product better- mash. What is mash or mashing? Mashing is the process of combining grains- typically barley, flake oats, rye, or wheat- with water, heating, and stirring. By adding hot water (or hot liquor as it’s known in the beer world) and stirring, we release enzymes in the malt that break down starches in the grain into sugar. The resulting sugar water is known as “wort” and is what we end up fermenting to convert sugars into alcohol. But before we do that, we need to do a few things, including lautering the wort. Lautering is the process of separating sweet wort from spent grain. While historically mashing and lautering are done in a single vessel, modern brewers have found better efficiencies and product quality can be achieved by using two vessels- a mash tun and a lauter tun.

Ok so we have two vessels- a mash tun and lauter tun. To get from one vessel to the next we need something. What’s that something? A pump. So let’s use a centrifugal! Well, not so fast. Mash has a high amount of solids (up to 60%) and is relatively thick. Additionally, mash is delicate and best product quality is achieved through gentle handling. So traditional centrifugals are not a great fit here.

Inoxpa Flexible Impeller Pump

Enter the flexible impeller pump. Flex impellers are a pseudo-PD pump, using a finned rubber stator and eccentric casing to create expanding and collapsing cavities, drawing fluid through the pump. Pump design is simple, and maintenance is relatively straight forward. Flex impeller pumps are cost effective and we can handle low to medium viscosity products up to about 60 psi of discharge head.

Failed Flexible impeller

So why wasn’t a flexible impeller right for this application? First, the impeller has an ultra tight fit in the casing. This requires high breakaway torques to start the pump, especially with a non-lubricating or sticky products. Operation is also loud and flexible impeller pumps are very sensitive to dry running. Mash can sometimes bridge, requiring re-hydration, which extend both the mash transfer time and subsequent lautering process. Additionally, this customer specifically was having to replace their impeller with higher-than-expected frequency.

Inoxpa RV Series Helicoidal Impeller Pump

To solve the challenge, Triplex partnered with Inoxpa to provide their RV helicoidial centrifugal impeller pump to replace the flexible impeller pump. The RV’s unique impeller shape helps prevent clogging and is able to handle whole particles up to 3mm in size without compromising the product. The RV series is close coupled to a C-Face motor, so it’s compact, and comes complete with a casing drain. Operation noise is comparable to a centrifugal pump and high efficiencies mean we can move considerable volumes with even smaller pump sizes. Helicoidal impeller pumps are cost effective, priced at a modest premium to flexible impeller and conventional centrifugal pumps. This customer specifically was able to reduce their transfer time from 45 minutes to an hour to 10-15 minutes while maintaining product integrity.

At Triplex, we’re always searching for products and technologies that help us take things from “can do” to “can do better”. For mash transfer or any high solids transfer application, Inoxpa’s RV series helicoidal impeller pump is one more tool in our belt. If you have any questions about helicoidal impeller pumps or any of your pumping needs, contact a Triplex Sales Engineer today!

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