Designing a New Chemical Pump for the Global Market

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The subsequent analysis of the data gathered is very costly. While the actual ‘solving’ is performed by the computer in the background, the analysis of the calculation results (post-processing) is interactive. Here, the hydraulic engineer interprets the representation of flow vectors or pressure and velocity distributions in selected section planes to derive information on the prevailing flow conditions and make possible improvements.

How to Design the Hydraulic System

With these tools, it is possible to develop hydraulic systems characterized by excellent efficiency levels on one hand and the absence of disadvantages regarding cavitation (NPSHreq) on the other. The optimized hydraulic systems were then incorporated in test pumps, and the test enabled the calibration of the CFD tools for further improvements.

In addition, actual operating points of a chemical plant were analyzed by comparing the energy consumption of the installed CPK/CPKN pumps with those of the new Mega CPK pump series. This comparison proved that energy consumption would be reduced by 6 per cent, if the new pump was used, assuming that no constant bypass is installed.

Back vanes (left) and balancing holes in conjunction with a throttling device (right) are two options to reduce axial thrust caused by different pressure profiles at the front and the rear impeller shroud.
(Picture: KSB)

Hydraulic Coverage

ISO 2858 covers 34 sizes, five of which are optional. According to this standard, the minimum discharge size is DN 32 and the maximum is DN 150. The minimum nominal impeller diameter is 125 mm, the maximum is 400 mm. Flow and head of the best efficiency point (BEP) are limited to 250 m3/h at 125 m for 2-pole (50 Hz) pump sets and 400 m3/h at 50 m for 4-pole (50 Hz) pump sets, respectively. Even in the past, the abovementioned limits were too narrow to meet the customers’ needs. In the sum of typical applications, roughly 15 per cent are used outside the ISO 2858 limits.

By implementing the new Mega CPK type series, the hydraulic coverage has been expanded even further. ISO 2858 also defines the BEPs for the individual pump sizes. In a normative environment where standards are highly prescriptive, the pump size is the dominant parameter for the price to the customer. It is therefore useful to highlight the tight restrictions in question and offer flexibility.

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