GB2107404A

GB2107404A - Centrifugal pump and turbine set

Info

Publication number: GB2107404A
Application number: GB08228662A
Authority: GB
Inventors: Helmut Munch; Klaus Willumeit
Original assignee: Klein Schanzlin and Becker AG
Current assignee: Klein Schanzlin and Becker AG
Priority date: 1981-10-12
Filing date: 1982-10-07
Publication date: 1983-04-27
Also published as: FR2514429A1; IT8223320A0; GB2107404B; DE3140439C1; JPS6363757B2; CH657673A5; IT1152830B; JPS5874896A; FR2514429B1

Abstract

The set, particularly for the desalination of seawater, has a pressurizing centrifugal pump 1 and, disposed on the same shaft, a Pelton turbine 2 and of an additional centrifugal pump 3 for returning the liquid discharged from the Pelton turbine to its place of origin, for example the sea. The pressurizing centrifugal pump 1, the Pelton turbine 2 and the return centrifugal pump 3 are all being disposed on a common shaft 4 in a common pressure envelope. <IMAGE>

Description

SPECIFICATION A centrifugal pump and turbine set The invention relates to a centrifugal pump and turbine set, for example for the desalination of seawater, the set having a pressurizing centrifugal pump and, disposed on the same shaft, a turbine for recovery of the energy in the returning liquid.

In reverse osmosis seawater desalination plants, centrifugal pumps are normally used for pressurization and only a small proportion of the pressure difference between the reverse osmosis module and the source of the water, (e.g the sea), can be reduced in the module. The residual pressure difference is then often reduced by a restrictor to an extent such that the residual pressure is sufficient to return the liquid to the sea.

Combined centrifugal pump and turbine sets are known wherein pressure reduction is provided by a turbine disposed on the same shaft as the centrifugal pump, more particularly reverse-running pumps being used as turbines (EPA 0 008 260). The advantage of these units or sets is that the pressure difference to be described can be defined clearly and no further conveying facilities are needed. Unfortunately, the turbine operates with very low efficiency and efficiency is a prime consideration in reverse osmosis desalination plants.

It is an object of the invention to provide a centrifugal pump and turbine set having an appreciably greater efficiency than known centrifugal pump and turbine sets used in reverse osmosis desalination plants.

According to the invention there is provided a centrifugal pump and turbine set having a pressurizing centrifugal pump and, disposed on the same shaft, a turbine for recovery of the energy in the returning liquid, wherein the turbine is a Pelton turbine and an additional centrifugal pump is provided for returning the liquid to its place of origin, the pressurizing centrifugal pump, the Pelton turbine and the additional, return centrifugal pump all being disposed on a common shaft in a common pressure envelope.

An embodiment of the invention is described below with reference to the accompanying drawing which shows, in axial section, a centrifugal pump and turbine set embodiment the invention.

Referring to the drawing, a centrifugal pump and turbine set comprises a multistage centrifugal pump 1, a Pelton turbine 2 and a volute-casing centrifugal pump 3 serving to return the liquid. The pumps 1,3 and the turbine 2 are all disposed on a common shaft 4. The three casings are so interconnected as to form a common pressure envelope.

Arrows in the drawing indicate the flow path of the liquid from entry into the pressurizing pump 1 to exit from the return pump 3. The liquid is pumped by the pump 1 to a module 5 where a first component separates out as product for example in a desalination plate, as de-salinated water, and a second component continues to the Pelton turbine 2. The pressure energy present in the second component is converted by the Pelton turbine 2 into mechanical energy to assist in driving the set. The liquid discharges from the Pelton turbine 2 into an un pressurized low-level reservoir 6 whence the centri fugal pump 3, the rotor of which rotates with the Pelton turbine and the other componets secured to said common shaft, returns the liquid to its place of origin, for example the sea, in a desalination plant.

The use of an integrated Pelton turbine may appear in some respects disadvantageous inasmuch as a Pelton turbine must have a pressureless dis charge, otherwise it cannot operate satisfactorily.

The liquid must therefore discharge to a low-level tank and then be returned therefrom to its place of origin, for instance, the sea. Disposing an additional return centrifugal pump on the same shaft and in the same pressure envelope not only makes it unnecessary to provide the electrical interlockings necessary when the items are arranged separately but also obviated the need for complicated seals between the pump and the Pelton turbin and between the Pelton turbine and atmosphere. The advantage of the high efficiency provided by the Pelton turbine is therefore combined with the avoidance of friction in a shaft seal without the need of an additional pump set which would have to be operated electrically and also interlocked with the centrifugal pump and turbine set.

The centrifugal pump and turbine set embodying the invention ensures that the low-level tank receiving the returning liquid is emplited by the pump when the set operates. In other respects, assuming correct matching, the conveying conditions are theoretically equal, since speed always alters in the same sense as frequency or in adaptation to a diesel drive, if used. Water cannot therefore enter the Pelton turbine casing, with the possible risk of water hammer and of a loss of the turbine blading.

1. A centrifugal pump and turbine set having a pressurizing centrifugal pump and, disposed on the same shaft, a turbine for recovery of the energy in the returning liquid, wherein the turbine is a Pelton turbine and on additional centrifugal pump is provided for returing the liquid to its place of origin, the pressurizing centrifugal pump, the Pelton turbine and the additional, return centrifugal pump all being disposed on a common shaft in a common pressure envelope.

2. A centrifugal pump and turbine set substantially as hereinbefore described with reference to, and as shown in the accompanying drawing.

3. Any novel feature or combination of features described herein.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION A centrifugal pump and turbine set The invention relates to a centrifugal pump and turbine set, for example for the desalination of seawater, the set having a pressurizing centrifugal pump and, disposed on the same shaft, a turbine for recovery of the energy in the returning liquid. In reverse osmosis seawater desalination plants, centrifugal pumps are normally used for pressurization and only a small proportion of the pressure difference between the reverse osmosis module and the source of the water, (e.g the sea), can be reduced in the module. The residual pressure difference is then often reduced by a restrictor to an extent such that the residual pressure is sufficient to return the liquid to the sea. Combined centrifugal pump and turbine sets are known wherein pressure reduction is provided by a turbine disposed on the same shaft as the centrifugal pump, more particularly reverse-running pumps being used as turbines (EPA 0 008 260). The advantage of these units or sets is that the pressure difference to be described can be defined clearly and no further conveying facilities are needed. Unfortunately, the turbine operates with very low efficiency and efficiency is a prime consideration in reverse osmosis desalination plants. It is an object of the invention to provide a centrifugal pump and turbine set having an appreciably greater efficiency than known centrifugal pump and turbine sets used in reverse osmosis desalination plants. According to the invention there is provided a centrifugal pump and turbine set having a pressurizing centrifugal pump and, disposed on the same shaft, a turbine for recovery of the energy in the returning liquid, wherein the turbine is a Pelton turbine and an additional centrifugal pump is provided for returning the liquid to its place of origin, the pressurizing centrifugal pump, the Pelton turbine and the additional, return centrifugal pump all being disposed on a common shaft in a common pressure envelope. An embodiment of the invention is described below with reference to the accompanying drawing which shows, in axial section, a centrifugal pump and turbine set embodiment the invention. Referring to the drawing, a centrifugal pump and turbine set comprises a multistage centrifugal pump 1, a Pelton turbine 2 and a volute-casing centrifugal pump 3 serving to return the liquid. The pumps 1,3 and the turbine 2 are all disposed on a common shaft 4. The three casings are so interconnected as to form a common pressure envelope. Arrows in the drawing indicate the flow path of the liquid from entry into the pressurizing pump 1 to exit from the return pump 3. The liquid is pumped by the pump 1 to a module 5 where a first component separates out as product for example in a desalination plate, as de-salinated water, and a second component continues to the Pelton turbine 2. The pressure energy present in the second component is converted by the Pelton turbine 2 into mechanical energy to assist in driving the set. The liquid discharges from the Pelton turbine 2 into an un pressurized low-level reservoir 6 whence the centri fugal pump 3, the rotor of which rotates with the Pelton turbine and the other componets secured to said common shaft, returns the liquid to its place of origin, for example the sea, in a desalination plant. The use of an integrated Pelton turbine may appear in some respects disadvantageous inasmuch as a Pelton turbine must have a pressureless dis charge, otherwise it cannot operate satisfactorily. The liquid must therefore discharge to a low-level tank and then be returned therefrom to its place of origin, for instance, the sea. Disposing an additional return centrifugal pump on the same shaft and in the same pressure envelope not only makes it unnecessary to provide the electrical interlockings necessary when the items are arranged separately but also obviated the need for complicated seals between the pump and the Pelton turbin and between the Pelton turbine and atmosphere. The advantage of the high efficiency provided by the Pelton turbine is therefore combined with the avoidance of friction in a shaft seal without the need of an additional pump set which would have to be operated electrically and also interlocked with the centrifugal pump and turbine set. The centrifugal pump and turbine set embodying the invention ensures that the low-level tank receiving the returning liquid is emplited by the pump when the set operates. In other respects, assuming correct matching, the conveying conditions are theoretically equal, since speed always alters in the same sense as frequency or in adaptation to a diesel drive, if used. Water cannot therefore enter the Pelton turbine casing, with the possible risk of water hammer and of a loss of the turbine blading. CLAIMS

3. Any novel feature or combination of features described herein.