Chemical Technology August 2016

PUMPS AND VALVES

Figure 1: The new Amarex KRT F-Max.

New impeller combines reliability and efficiency by Bryan Orchard

Growing demands from the water and wastewater treatment industries for submersible motor pumps that resist clogging, deliver reliability and contribute to improving energy efficiency, have led to KSB AG’s new centrifugal pump.

A gainst a background of growing demands from the water and wastewater treatment industries for submersible motor pumps that resist clogging, deliver reliability and contribute to improving energy ef- ficiency, KSB AG has developed a new centrifugal pump, the Amarex-KRT F-Max (Figure 1) that addresses these issues. Improved hydraulic system and motor performance are delivered through the design of a new vortex impel- ler and a motor that offers efficiencies currently calcu- lated according to the same IEC 60034-2 measurement method as that used for motors of dry-installed pumps. In order to attain a pump’s optimum operating point, it is essential to select the correct impeller and size of impeller for the application. Whilst free-flow or ‘open’ impellers enable suspended solids in wastewater to pass more easily through the pump than closed single channel or multi-channel impellers, they do not compare favourably when it comes to performance. It is for these reasons that KSB has focused on designing an open impeller that can achieve and even exceed the efficiency levels associated

with single-channel impellers. To improve overall efficiency, KSB has looked to optimise the motors’ efficiency in an- ticipation of future standards and market requirements is in compliance with IE3.This has enabled KSB to markedly reduce energy consumption. Impeller development The concept behind the design of the new pump is the elimination clogging, a problem that causes inefficient flows and possibly subsequent pump failure through the presence of solids in wastewater. According to KSB the first stage in finding a solution to clogging was to differentiate between rigid and non-rigid solids. Michael Lebkuecher, who headed the product management solid burden pumps, comments: “Rigid solids need to have sufficient space in the pump chamber for them to pass through the pump. When it comes to non-rigid solids we have to ensure that the presence of wet tissues and similar fibrous materials do not form a mass. These problems were resolved, but then the next challenge was to address overall efficiency.”

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Chemical Technology • August 2016