Suppressing device for a vertical pump, vertical pump and method for retrofitting a vertical pump

Abstract

A suppressing device shifts a structural natural frequency of a pump, the pump including a pumping unit with an inlet and an impeller, a discharge unit with an outlet, a drive unit for rotating the impeller, a column pipe extending in an axial direction and having at least one column element with an axial length, the column pipe connecting the pumping unit with the discharge unit, and a line shaft extending within the column pipe operatively connecting the drive unit with the pumping unit. The suppressing device includes at least one rib extending essentially in a radial direction, and is perpendicular to an axial direction of the suppression device. The suppression device has an extension extending in the axial direction of the suppressing device, is at least half the axial length of the column element, and is configured to closely fit around an entire circumference of the column element.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority to U.S. Provisional Application No. 62 / 117,569, filed Feb. 18, 2015, the contents of which is hereby incorporated herein by reference.BACKGROUND[0002]1. Field of Invention[0003]The invention relates to a suppressing device for shifting a structural natural frequency of a vertical pump as well as to a vertical pump in accordance with the preamble of the independent device claim. The invention further relates to a method of retrofitting a vertical pump.[0004]2. Background of the Invention[0005]Vertical pumps, in particular large vertical pumps have been used successfully in a plurality of applications for a very long time. Vertical pumps for specific applications are not infrequently manufactured in accordance with the specifications of the users or are matched in detail to specific requirements.[0006]Important fields of application for the use of vertical pumps are, amongst other things, cooling towers, app...

AI Technical Summary

Benefits of technology

The vertical pump described in this patent has a problem caused by its natural frequencies. These frequencies can cause issues when the pump runs at a speed close to one of its natural frequencies. The invention described in the patent helps suppress these critical frequencies, reducing the load and wear on the pump's components. Overall, this invention makes it easier to design and manufacture better vertical pumps.

Problems solved by technology

One of the problems with vertical pumps is caused by the structural natural frequencies of the pump installation.

Due to a lack of reliable analytical methods many of these pumps were designed with structural natural frequencies at or near the running speed of the pump or multiples or half-integral multiples thereof.

When such a matching occurs a considerable load results especially on the bearings, which causes for example a premature failure of the bearings or the line shaft.

In addition, an enhanced wear or other negative degradation effects may occur.

In many cases, for example in power plants or nuclear installations the user is not willing to replace an entire existing pump or the user is not interested in a complete redesign of its pumps.

Although this method has proven successful in many applications there are some restrictions or drawbacks.

It is possible that the required point mass for effectively lowering the natural frequency is as large that the pump cannot support it structurally.

In other applications the spatial circumstances do not allow for the installation of a point mass at the required location.

Furthermore, in some applications it turned out that the method with the point mass did not at all yield to the desired result.

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