RU2305208C1 - Vertical centrifugal screw pump - Google Patents

Abstract

FIELD: mechanical engineering.

SUBSTANCE: proposed pump has housing 1 with centrifugal impeller 3 and screw 4 placed inside lower part of elongated pipe 6. Pipe 6 is cantilever mounted on central suction part of housing 1. Centrifugal impeller 3 and screw 4 are interconnected by elongated transmission 7. Made on suction section of pipe 6 are one or more check valves 10 in form of ports 8 arranged higher than screw 4 which are furnished with normally closed leaf elastic elements 9. With screw 4 being rotated, liquid is taken into pipe 6 through valve 10 and is delivered along pipe 6 to centrifugal impeller 3. Valve 10 is open, and elastic elements 9 close ports 8. After filling of centrifugal impeller 3 with liquid, pump starts operating at nominal duty. Rarefaction is built in suction section of pipe 6, and elastic elements 9 recede from ports 8. Liquid passes into pipe 6 through ports 8 at lower hydrostatic resistance. At subsequent switching on of pump, the latter turns for operation at nominal duty owing to holding of liquid in centrifugal impeller by valves 9, 10.

EFFECT: provision of pump with lower power consumption and increased service life.

2 cl, 2 dwg

Description

The invention relates to mechanical engineering, namely to the designs of centrifugal pumps, mainly vertical screw-centrifugal pumps, and can be widely used in various industries.

As a prototype, a vertical screw-centrifugal pump was selected, comprising a housing with a centrifugal impeller installed in it and an upstream screw located inside the lower part of the elongated pipe, cantileverly fixed to the central suction part of the housing, the wheel and auger connected to each other by an elongated transmission [application for invention of the Russian Federation No. 2002122004/20 (023116) from 08/12/02, cl. F04D 29/04].

A disadvantage of the known pump is the significant hydraulic resistance at the inlet to the pump when the pumped medium passes through the screw, since the volumetric flow of the centrifugal pump is several times higher than the feed of the upstream screw.

The problem to which the invention is directed, is to create a vertical screw-centrifugal pump with low hydraulic resistance at the inlet by providing a bypass passage of the pumped medium to the centrifugal pump, bypassing the screw, when it is operating in nominal mode.

The technical result is achieved by the fact that in a vertical screw-centrifugal pump containing a housing with a centrifugal impeller installed in it and an upstream screw located inside the lower part of the elongated pipe, cantileverly fixed to the central suction part of the housing, the wheel and the screw connected to each other by an elongated transmission , according to the invention, one or more check valves are made on the suction pipe section, for example, in the form of windows located above the upstream screw of the screw, provided with a norm no closed petal elastic elements adapted to opening due to the vacuum pressure of the pumped fluid when it is full, the rotating centrifugal impeller.

In this case, the suction section of the pipe can be additionally equipped with a check valve installed below the upstream screw with the possibility of holding a column of liquid inside the elongated pipe after turning off the pump.

The invention is illustrated by drawings, in which Fig. 1 is a general view of a vertical screw-centrifugal pump, Fig. 2 is a fragment of a pump (centrifugal impeller) with an upstream screw at the time the pump is turned off (with valves closed)

The list of symbols in the drawing.

1 - housing;

2 - shaft of a centrifugal impeller;

3 - centrifugal impeller;

4 - upstream auger;

5 - auger shaft;

6 - pipe;

7 - transmission;

8 - pipe window 6;

9 - flap elastic element;

10 - check valve.

The vertical screw-centrifugal pump contains a housing 1 with a centrifugal impeller 3 mounted on it on a vertical shaft 2 and an upstream screw 4 located on the shaft 5 inside the sectional pipe 6. The shaft 5 of the screw 4 is connected to the impeller 3 by means of an extended sectional transmission 7.

On the suction section of the pipe 6 above the upstream screw 4 there are windows 8 with normally closed flap elastic elements 9 with the possibility of opening the latter due to the rarefaction pressure of the pumped liquid when it is completely filled with a rotating centrifugal impeller 3.

Below the upstream screw 4, a check valve 10 is installed on the suction section of the pipe 6, which is capable of holding a column of liquid inside the pipe 6 when the pump is turned off.

The operation of the pump is as follows.

Before starting work, a transmission 7 and a pipe 6 are drawn from the sections, depending on the specific conditions for installing the pump (the height of the centrifugal impeller 3 relative to the mirror of the pumped liquid medium) so that the suction section of the pipe 6 with windows 8 is in a submerged state.

When the motor is turned on, shafts 2, 5 and transmission 7 begin to rotate, the rotation from which is transmitted to the centrifugal impeller 3 and the upstream screw 4. When the screw 4 is rotated, liquid is taken into the pipe 6 through valve 10 and then pumped through pipe 6 to the suction part centrifugal impeller 3. In this case, the valve 10 is in the open position, and the elastic elements 9 close the windows 8. Next, the liquid medium fills the centrifugal impeller 3 and under the action of centrifugal forces is supplied with a given pressure to the sides at the consumer (not shown).

After filling the working centrifugal wheel 3 with the pumped liquid, the screw-centrifugal pump starts to work in the nominal mode. At the same time, a vacuum is created in the suction section of the pipe 6 due to the fact that the volumetric feed of the centrifugal pump exceeds the feed of the upstream screw 4. Under the action of the vacuum, the elastic flap elements 9 move away from the windows 8 and the latter open. The pumped liquid begins to flow into the pipe 6, bypassing the upstream auger 4, that is, with less hydraulic resistance. Due to this, the load on the pump motor is reduced, which increases its resource and reduces energy consumption.

When the screw-centrifugal pump is turned off, the hydrostatic pressure of the liquid column in the pipe 6 acts on the elements 9 and the valve 10, which leads to the closure of the valve 10 and the windows 8 are blocked by the elements 9. This keeps the liquid column in the pipe 6 to the level of the centrifugal impeller 3 .

The next time the screw-centrifugal pump is turned on, the latter immediately switches to the nominal operating mode due to the presence of a liquid medium in the impeller 3.

The use of the invention allows to create a vertical screw-centrifugal pump with lower power consumption and increased service life.

Claims (2)

1. Vertical screw-centrifugal pump, comprising a housing with a centrifugal impeller installed therein and an upstream screw located inside the lower part of the elongated pipe, cantilevered to the central suction part of the housing, the wheel and the screw connected to each other by an elongated transmission, characterized in that one or more check valves are made on the suction section of the pipe, for example, in the form of windows located above the upstream screw and equipped with normally closed lobe elastic elements with the possibility of opening due to the rarefaction pressure of the pumped liquid when it is completely filled with a rotating centrifugal impeller. 2. The vertical screw-centrifugal pump according to claim 1, characterized in that the suction pipe section is additionally equipped with a check valve installed below the upstream screw with the possibility of holding a liquid column inside the elongated pipe when the pump is turned off.

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