However, build-up around the volute casing and impellers in the pumps severely affected the flow which required the pumps to be dismantled and cleaned – a process which took 2-3 hours per pump, and the pumps being replaced every six months.
In wastewater treatment processes, polymers are used to thicken sludge by attracting all suspended fine particles to produce larger groups of solid materials through a process called flocculation. These flocculants are often extremely viscous and shear-sensitive once hydrated. Incorrect pump selection can affect the metering accuracy, damage the polymer structure and potentially the efficiency of the thickening process.
The use of centrifugal pumps to transfer viscous media reduces their performance due to factors such as the effect of viscosity on the impeller, reduction in flow and the increase in horsepower required. But also their pumping action generates high shear, making them unsuitable to handle shear-sensitive products.
To address these challenges, Seepex was engaged to offer a cost-effective pumping solution.
To meet the application’s requirements, SEEPEX selected progressive cavity pumps from its BW range for transferring the viscous polymer.
Progressive cavity pumps have a low shear pumping action. Their flow rate is directly related to pump speed and have minimal pulsation, producing the lowest mechanical stress and minimising product shear damage.
Additionally, in a PC pump the stator is cleaned by the action of the rotor, eliminating any chance of product build-up and subsequent blockages which would otherwise affect pump performance.
Seepex’s intervention has resulted in cost-savings for the customer, as the new PC pumps have not suffered from blockages, used any spare parts or required maintenance since they were installed in 2018.