Centrifugal pump

Details Centrifugal pump Centrifugal pump

1989-08-04

1991-04-16

Look, Edward K.

Rotary kinetic fluid motors or pumps

Pump having rotating inlet end or scoop immersed in liquid

4151691, 415203, 415206, F04D 112

Patent

active

050077988

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention relates to pumps for pumping liquids and mixtures of liquids and gases over a wide range of pressures and flow rates. In particular, the invention provides pumps which are capable of accommodating entrained gas and vapour at low absolute suction pressures.
The invention was developed for use with domestic vacuum distillation systems (desalinators) but it will be appreciated that the invention is not limited to this particular application.


DEFICIENCIES OF BACKGROUND ART

Problems are encountered when attempting to pump liquids, and particularly mixtures of liquids and gases, at low absolute suction pressures and low flow rates using a centrifugal device. These problems arise largely from the gas and vapour content of the flow, which is more prominent at lower pressures. These may be dissolved gases which separate at low pressures or the gaseous phase of the liquid itself.
At high flow rates in the order of hundreds of litres per minute, the flow velocity is such that entrained vapour tends to be purged from the system in the high velocity fluid flow. However, known centifugal pumps are unable to operate at low pressures of the order of 23 to 25 inches of mercury and low flow rates of the order of 300 mls per minute. In fact these known pumps are unable to accommodate significant quantities of gas and vapour at these pressures, regardless of the flow rate.
Problems are also encountered in providing reliable long lived seals for these pumps.


Disclosure of the Invention

According to the invention there is provided a centrifugal pump having an impellor mounted for rotation about an axis, said impellor having a central inlet chamber with a peripheral wall concentric with said axis and at least one passage extending outwardly from an inlet port in said wall to an exit port radially spaced from said chamber; wherein, stationery inlet port means are located within said chamber wherein, stationary inlet port means are located within said chamber for separating the spinning impellor from incoming fluid entering said inlet port means thereby to prevent induced rotation of said incoming fluid, said stationary inlet port means including an annular portion concentric with said axis and in substantial alignment with said impellor inlet port, at least one channel extending radially outwardly from the interior to the exterior of said annular portion for supplying said incoming of said impellor passage.
In this way the impellor is prevented from imparting a spinning velocity to the incoming fluid which would otherwise tend to separate the liquid from any entrained vapour and ultimately choke-off the supply entirely.
In a second aspect of the invention the impellor is located within its own delivery volume and wholly immersed in previously delivered fluid so as to deliver directly from said impellor to the previously delivered fluid. The impellor may be arranged at any desired orientation to the vertical. This provides a very simple pump with no peripheral structure since the delivery is directly from the impellor to the surrounding fluid.
The invention may also advantageously provide means for slowing the peripheral flow velocity of fluid immediately adjacent the impellor periphery.


BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:
FIG. 1 is a cut-away and elevation of a pump adapted for pumping water and entrained air at low pressures and flow rates.
FIG. 2 is a section taken on line 2--2 of FIG. 1.
FIG. 3 is a fragmentary section taken on line 3--3 of FIG. 1.
FIG. 4 is a sectional side elevation of a second pump.
FIG. 5 is a view taken generally on line 5--5 of FIG. 4 with the cover plate removed.
FIG. 6 is a plan view of the pump of FIG. 4, and
FIG. 7 is an enlarged section taken on line 7--7 of FIG. 5.
FIG. 8 is a view similar to FIG. 7 but illustrating an alternative arrangement.
FIG. 9 is a view taken on line 9--9 of FIG. 8.
FIG. 10 is a partly sectio

REFERENCES:
patent: 1786435 (1930-12-01), Komfala
patent: 4416586 (1983-11-01), Diederich et al.
patent: 4439200 (1984-03-01), Meyer et al.
AU,B, 4991/51 (158673) (Farm Technical Services Pty. Ltd.), Sep. 11, 1952.
GB,A 494469, The Candy Filter Company Ltd. et al, 11/1938.
GB,A, 901160 (Q.V.F. Limited et al), Jul. 18, 1962.

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