WO1988003230A1

WO1988003230A1 - Centrifugal pump, particularly for dirty liquids

Info

Publication number: WO1988003230A1
Application number: PCT/DK1987/000136
Authority: WO
Inventors: Jens-Ole Aagaard Jensen
Original assignee: Individual
Current assignee: Individual
Priority date: 1986-10-31
Filing date: 1987-10-29
Publication date: 1988-05-05
Anticipated expiration: 1989-04-30
Also published as: AU8236287A; DK522686A; DK156143C; DK156143B; DK522686D0

Abstract

When pumping dirty liquids, such as liquid manure, sewage and similar non-homogenous media, it is difficult to use the ordinary centrifugal pumps, because these often become clogged. Therefore, the capacity of the pumps must normally be increased which causes problems of too high dosage if for instance liquid manure is to be scattered from a spreader. In order to be able to control the pumping out and reduce pump pressure, pump capacity and energy consumption, the invention teaches the use of a pump where a pressure chamber (9) in the form of a ring chamber is provided around the outer rim of the pump wheel (8, 14), into which ring chamber outlet channels (10) open. Moreover, a number of projecting knives (11) can be attached to the end face (14) of the pump wheel, which partly cut the solid particles in the pump medium into small pieces and partly function as valve body in front of the discharge openings (10) in that the knives alternately close and open the openings (10) thereby producing an impulse which enhance the pumpability of the medium in the small discharge tubes.

Description

CENTRIFUGAL PUMP, PARTICULARLY FOR DIRTY LIQUIDS

The invention relates to a centrifugal pump, particu¬ larly for pumping dirty liquids, preferably a radial or semi-axial pump with a pump housing and a pump wheel being rotatably mounted in the pump housing, said wheel comprising an end face being attached to a pump shaft, said end face having curved radial vanes arranged on an axial side of the end face, said pump housing along its radially outermost circumference having a circular cylindrical ring chamber to which outlets are connected in the form of at least one channel.

Pumps of this type are used for pumping many diffe¬ rent media being pumpable, i.e. which can be pumped through inlet pipes, pump and outlet pipes.

In the case of media which are only partially liquid, such as sewage or liquid manure, problems will arise with the pumping in that the more solid components of the media clog in the channels and pipes.

In order to make such media pumpable, either special pumps with relatively large dimensions, high pump pressure and energy consumption must be used, or some sort of mechanical division into fine particles or homogenization of the medium must be carried out.

Especially when spreading liquid manure it is a con¬ siderable disadvantage that the liquid manure is so difficult to pump from a tank and out into a spread- ing heap or into a manure burying device. This there¬ fore requires a comparatively high pump pressure and a dimensioning which makes the spreading capacity far too large with the consequent risk of too high a concentration of manure by this type of spreading. In practice, mechanical spreading by a discharge wheel is therefore often used which, however, produces an unpleasant smell and loss of man rial value due to the relatively high degree of evaporation which takes place during this kind of spreading.

By the known centrifugal pumps of this type, a comparatively high static pressure in the ring chamber occurs, because part of the speed of motion is converted into pressure by deceleration in the ring chamber. This pressure may even in the case of comparatively non-homogenous media make these pump¬ able in that the more solid components in many cases will be triturated during their passage through the discharge pipes due to the comparatively high pump pressure. This is obtained with no need for any larger pump capacity, and the possibility of making even hardly pumpable media pumpable. In this manner the centrifugal pump may in itself contribute to facilitating for instance the spreading of liquid manure with suitable spreading capacity which there¬ fore need not cause top-dressing, etc.

However, channels and/or pipes are easily clogged, because the more solid components in the liquid ma¬ nure tend to lump together on leaving the centrifugal pump, whereafter the spreading of manure must be stopped until the pipes have been cleaned. This may happen many times during one working-day which causes a loss of money.

It is the object of the invention to eliminate these drawbacks of the known pumps, and this is achieved by 5 a centrifugal pump of the mentioned type, said cen¬ trifugal pump being characteristic in that the chan¬ nel or channels open on to a ring chamber in a wall being parallel to the end face, and that plates pro¬ jecting radially and being parallel to the level of 10 the end face are attached to the end face, said plates being constructed in order during the rotation of the pump wheel to close the channel or at least one channel at a time.

15 The fact that the outlet channels open on to the side of the ring chamber first of all provides a high degree of homogenization of the medium in the chamber, and by mounting plate pieces on the pump wheel, which during the rotation alternately covers

20 and opens the outlet channels, a pulsating outflow is obtained which will keep even narrow tubes unclogged.

By, as related to in claim 2, arranging more channels than plates evenly distributed in the ring chamber 25 and over the end face, respectively, a uniform spreading of the medium is achieved.

By, as related to in claim 3, providing a cutting edge along the front edge of the plates, these will 30 be able to cut the more solid components into small pieces which will make pumping easier.

In the following the invention will be described in further detail with reference to the drawing, in

•w. which

Fig. 1 is a sectional view of a centrifugal pump according to the invention seen along I-1 in fig. 2, and

Fig. 2 is a partial cross section of the centri¬ fugal pump according the invention seen along II-II in fig. 1.

The drawing shows an example of a preferred embodi¬ ment of a radial pump according to the invention.

This consists of a pump housing 2 to which a suction brach 1 is connected. To the rear the pump housing is closed by a wall 7 which can be attached by means of screws 4 or similar means to the pump housing. A driving shaft 6 is moreover mounted in a generally known manner in a bearing housing 5, which shaft can be brought to rotate by means of a motor or other drive mechanism, which is not shown.

A pump wheel is attached to the shaft 6 comprising a circular end face 14 and with vanes 8 evenly distri- buted around the shaft on the one axial side of the end face 14 extending parallel to the wall 7.

The pump housing 2 is on its outer side provided with a pressure chamber in the form of a cylindrical ring chamber 9. Discharge branches 3 are arranged in the wall 7 at the back of this ring chamber 9 to which not shown tubes or pipes can be attached.

The branches end in outlets 10 in the form of holes in the wall 7. As shown, these holes 10 are evenly distributd over the entire circumference of the ring chamber 9.

A number of plates 11, whose shape may be rectan¬ gular, are moreover attached by means of rivets 12 to the end face 14 og the pump housing. These plates protrude into the ring chamber 9 and since they are positioned close to the holes 10, they will function as a valve which during the rotation of the pump wheel alternately closes and opens for the passage of the medium from the ring chamber 9 out through the branches 3.

Moreover, these plates 11 will operate as cutters in that they will cut their way through any solid particles in the medium and thereby triturate these in order that the medium can pass unobstructedly through the discharge pipes. This is particularly expedient when the pump is used for spreading sewage or manure.

In this manner even a hardly pumpable medium can be pumped, because it is being made more homogenous and being discharged in a pulsating movement, which part¬ ly ensure the actual pumping and partly reduce the risk of clogging in even comparatively small pipes or tubes. Hereby for instance manure or sewage can more easily be spread and perhaps buried in the ground in a suitable amount so that overdosages or overloading of the receiver is avoided, said receiver for instance being farm land, with the risk of causing damage to the environment. In the shown and described example reference is being made to a radial pump, but it is within the scope of the invention to use a semi-axial pump in that such a pump can also be provided with the channels and plates according to the invention in the cylindrical ring chamber which will function as a pressure chamber.

Claims

P A T E N T C L A I M S

1. Centrifugal pump, particularly for pumping dirty liquids, preferably a radial or semi-axial pump with a pump housing and a pump wheel being rotatably mounted in the pump housing, said wheel comprising an end face (14) being attached to a pump shaft (6) said end face having curved radial vanes (8) arranged on an axial side of the end face, said pump housing (2) along its radially outermost circumference having a circular cylindrical ring chamber (9) to which out¬ lets are connected in the form of at least one channel, c h a r a c t e r i z e d in that the channel (10) or the channels (10) open on to the ring chamber (9) in a wall (7) being parallel to the end face (14), and that plates (11) projecting radially and being parallel to the level of the end face (14) are attached to the end face (14), said plates (11) being constructed in order during the rotation of the pump wheel to close the channel (10) or at least one channel (10) at a time.

2. Centrifugal pump according to claim 1, where there are several channels (10), c h a r a c t e - r i z e d in that the channels (10) and the plates (11) are evenly distributed on the wall (7) and end face (14), respectively, and so that there are more channels (10) than plates (11).

3. Centrifugal pump according to claims 1-2, c h a ¬ r a c t e r i z e d in that the plates (11) are sharpened along the edge pointing in the direction of the rotation.