Centrifugal pumps tackle cheese making
3 Jul 2015
Manufacturer compares centrifugal pumps to tackle the problem of curd fines in cheese making.
In the complex process of making cheese, excess curd fines can decrease the quality and yield of the cheese.
Often these curd fines are formed while pumping the curd at too high speeds.
Packo, a manufacturer of industrial pumps, was contacted by a Swiss cheese dairy about this problem and looked to offer a solution by developing a new centrifugal pump.
The centrifugal pumps that tend to be used for pumping curd mostly have a semi-open recessed impeller, with straight blades and a completely round pump casing.
This vortex type of impeller is considered to be the best for pumping curd because it is assumed that the liquid is not passing through the impeller and hence the curd is not coming into contact with the impeller.
It was this type of pump that was being used at the Swiss cheese dairy.
As part of its solution, Packo used computational fluid dynamics (CFD) to investigate the flow and behavior of liquids inside this traditional type of pump and a new Packo centrifugal pump with a volute pump casing and special closed impeller.
Both pumps had the same duty point - 60m³/h on 6m head – and during the experiment the velocity inside the pumps were measured.
The velocities in the pump with the semi-open recessed impeller and round casing were much higher than Packo’s new closed impeller pump.
There were significant differences in velocity in the traditional centrifugal pump, with some velocities being over 15m/s, while elsewhere the CFD recorded dead zones where the fluid stood still in the pump.
The contrast in velocity created high turbulence, which is a major contributor to the creation of “cheese fines”.
In the Packo pump the velocities in the impeller and the pump casing were much lower and there were no dead areas.
This resulted in less turbulence and a higher efficiency, significantly reducing the potential to damage the curd.
Packo supplied one of the new pumps for testing, and it was monitored during a two-month trial period.
The pumping of the curd with the new design proved to be much steadier than with the traditional vortex pump.
