![]() The open-channel design of the impeller and its corkscrew motion create a positive displacement action, literally pushing the malt mash away. It is often found in use on applications involving viscous or high-solid content fluids.Īlthough pumping liquids of this nature by other methods can often lead to considerable energy consumption and high maintenance costs, this was not the case with the screw channel pump. ![]() Featuring a corkscrew-profile impeller fitted inside a cone-shaped casing, this pump is ideal for media that contain long fibers, sludges and slurries. The size of progressive cavity pump needed to provide the required power and flow rates would occupy too large an area, and this ruled out this type pump as a solution.Įventually, the decision was made to perform a trial using a high efficiency screw channel pump. However, the new pump was required to sit in the relatively restricted floor area occupied by its predecessor. The relatively gentle action of a progressive cavity pump would certainly be suited to the malt application because it applies low levels of shearing to the pumped fluid and minimizes the likelihood of damage. However, reducing the water content was not an option with the existing pumping arrangement because it was likely to lead to a number of other problems that are common to centrifugal pumps-such as reducing the flow of pumped liquid, which in turn can cause overheating of the pump.Īnother was a peristaltic pump that operates on the positive displacement principle, but the large percentage of solids present in the malt mash could again lead to blockages, caused by the rotor repeatedly opening and closing the flexible tubing used in this type pump.Īny blockage problems could have caused a recurrence of the drying out and thickening process, meaning that a peristaltic pump was not ideally suited to this application.Ī progressive cavity pump offered another possible option.The combination of a rotor and stator generates a positive displacement action by creating a series of small, fixed-shape cavities within the pump.Īs the rotor turns, these cavities fill with the pumped medium before moving along the line of the pump and taking the liquid with them. In addition, the customer ideally wanted to use less water when creating the malt mash because this would lead to a better end product. ![]() ![]() This process lead to additional downtime and extra costs. In many cases, the only option was to open and clean the pump, and sometimes the adjacent piping too, before the pump could be restarted. This in turn made the pump increasingly difficult to restart. As the malt in this case became increasingly dry, it became more and more resistant to being moved. To begin operation, a centrifugal pump must be primed with the fluid to be pumped. Whenever the pump was turned off-even for a little as one hour-moisture would begin to escape from the malt, leaving behind an increasingly less liquid mash. However, in this instance, problems had arisen due to the high solids content of the malt mash. These are regularly used to transport liquids through piping, with the liquid entering the pump impeller along or near its rotating axis and then being driven radially outward into a diffuser before it leaves the pump at a higher speed than it entered. The brewing company had been using a semi-open vortex impeller unit to pump the malt mash.
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