Delivery Pump

Abstract

A delivery pump for conveying a liquid between a pump inlet and a pump outlet, the pump being constructed as a single-stage centrifugal pump with a radial impeller (2) having a centrifugal construction arranged rotatably in an impeller chamber (6) of a pump casing (1); the impeller being connected to a variable-speed drive motor (5) variable in speed into the five-digit range of revolutions per minute, and the impeller receiving liquid flow centrally, and being provided with radially-extending delivery ducts (3), and at outside impeller diameters of up to 55 mm developing rotational speed-dependent delivery heads of up to 300 m. For use in a process engineering system, the delivery pump is designed for nominal operation in the form of continuous centrifugal pump part-load operation with delivery rates in the range of 0 ml / min to 7000 ml / min; the nominal operation is characterized by a centrifugal pump part-load-specific rotational speed nqTL≧0.05≦10 (l / min), and the impeller chamber (6) comprises one or more pump outlet ducts (13) located on the circumference at acute angles to or tangentially to the outside diameter of the radial impeller.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation of international patent application no. PCT / EP2008 / 002767, filed Apr. 8, 2008 designating the United States of America and published in German on Nov. 6, 2008 as WO 2008 / 131846 A1, the entire disclosure of which is incorporated herein by reference. Priority is claimed based on Federal Republic of Germany patent application no. DE 10 2007 020 218.2, filed Apr. 28, 2007.BACKGROUND OF THE INVENTION[0002]The invention relates to a delivery pump with a variable-speed drive, the delivery pump being designed as a single-stage centrifugal pump with a radial impeller (2) of centrifugal type of construction, arranged rotatably in an impeller chamber of a pump casing (1), for delivering a fluid between a pump inlet (4) and a pump outlet (13), the radial impeller (2) being connected to a drive motor variable in speed into the five-digit range of revolutions per minute, the radial impeller (2) receiving the flow cent...

AI Technical Summary

Benefits of technology

[0009]A further object of the invention is to provide a pump unit having a delivery rate which is variable, pulsation-free and accurately adjustable over a wide range for delivering differing media having different properties.

[0010]An additional object of the invention is to provide a delivery pump which which can be cleaned easily for rapid product changes.

[0014]According to further embodiments, the pump casing, with a radial impeller arranged in it, preferably has a residual volume lower than 30 milliliters. This has the considerable advantage that the delivery pump is easily scavengable. In addition, as a result of the low residual volume and the minimum number of gaps, when a fluid to be pumped is changed in the pump, only low product losses occur during a cleaning or scavenging of the delivery pump. Furthermore, an inside diameter of the impeller chamber is designed to be a maximum of 4% larger than an outside diameter of the radial impeller. Also, by reducing the size of the impeller chamber surrounding the radial impeller, the dynamic pressure prevailing at the pump outlet duct is increased. In this case, the inlet ports of one or more pump outlet ducts are constructed in the form of pressure tubes or similarly to a pressure tube.

[0016]This device improves the delivery of sensitive fluids and / or of fluids with a low boiling point by means of the delivery pump capable of being operated in a wide nqTL range.

Problems solved by technology

Such positive-displacement pumps have the disadvantage of the lack of reliability due to friction between the components to be sealed off, moved in relation to one another, and their pulsating delivery stream.

A resulting outlay in terms of maintenance and the costs for wearing parts and for exchanging these are detrimental to rapid research and development work and appreciably disrupt a production process.

The disadvantage of this canned motor design is the multiplicity of gaps which, because of the complex flow routing between the pump and canned motor, seriously impede the cleaning of the pump.

Since part of the delivery fluid flows permanently through the motor and its gap space, a high introduction of heat into the delivery fluid occurs due to the frictional heat of the rolling bearings and to the heat loss from the canned motor.

If this pump were operating under part load, an inadmissibly high introduction of heat would take place very quickly.

This would result not only in damage to the fluid, but also in a failure of the pump as a result of cavitation or dry running.

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