GB2024943A

GB2024943A - Two-stage centrifugal pump

Info

Publication number: GB2024943A
Application number: GB7917052A
Authority: GB
Original assignee: Pumpen & Verdichter Veb K
Current assignee: Pumpen & Verdichter Veb K
Priority date: 1978-05-29
Filing date: 1979-05-16
Publication date: 1980-01-16
Also published as: AT362234B; FR2427492A1; ATA248279A; JPS5564192A; DE2912959B2; DE2912959A1; DD136760A1

Abstract

A high-speed H.P. impeller 2 concentrically surrounds a low-speed L.P. impeller 1 in a common radial plane A-A within a housing 4, the impellers rotating in the same or opposite directions. The driving motor 6 of the H.P. impeller may be of higher speed than the driving motor 5 of the L.P. impeller or, as shown, step-up gearing 11 may be used. In the former case, one of the driving shafts may be hollow and concentrically surround the other. The motors may be of frequency-controlled three-phase type or may be of D.C. type fed with rectified current from a three-phase supply, or I.C. engines or turbines may be used. <IMAGE>

Description

SPECIFICATION High-pressure centrifugal pump assembly The invention relates to a two-stage highpressure centrifugal pump assembly of vertical or horizontal constructional form for delivering liquids to relatively high delivery heads.

The pumps of the centrifugal pump assemblies for delivering liquids to relatively high delivery heads are mainly designed as multi-stage centrifugal pumps containing up to 1 5 stages. The electric prime mover which is mainly employed is a three-phase induction motor with an upper limiting speed of nSyn=3000 mien~1 conditional on the mains frequency of 50 Hz, (European mains supply) and nSvn=3600~ at 60 Hz, (North American mains supply). it is also usual to arrange a gearing between the electric prime mover and a multi-stage centrifugal pump for increasing the speed of rotation, so as to obtain a speed higher than 3000 mien~1 for driving the pump.

(Technisches Handbuch Pumpen, VEB Verlag Technik Berlin, 5th Edition 1976;Kleines Pumpen Handbuch fur Chemie und Technik, Verlag Chemie GmbH, Weinheim 1967). Other prime movers such as internal combustion engines and turbines are likewise used.

The disadvantage as regards these pump assemblies consists particularly in that, related to the overall size when using the conventional contructional form of the pump assemblies, it is not possible to achieve a relatively high delivery head while simultaneously maintaining a good efficiency, a good suction capacity and operational reliability with an economically tenable expenditure in construction.

The expenditure in construction is too high as regards production time, consumption of material and dimensions.

The known multi-stage developments of the pump assemblies of conventional design; which incorporate the present-day technical developments, are consequently not optimal economic solutions. An additional factor is that the performance in operation, more especially the performance as regards vibration and wear and tear, is not satisfactory. Attemps have been made recently to obviate the disadvantages which have to be accepted with the constructional form of assemblies having multi-stage centrifugal pumps by using single-stage centrifugal pumps with a high speed of rotation.Starting from the basis that, with a prescribed efficiency, the impeller diameter is smaller in proportion as the driving speed is chosed to be higher, the complete pump assembly is more compact and economic as regards manufacture, purchase, installation and in operation as the driving speed which is provided is higher, and at the same time the performance during operation is improved.

These considerations ied to the development of a known single-stage or two-stage high-speed geared centrifugal pump for the output range V up to 160 ma/h and a delivery head H up to 1700 m.

The disadvantages of the relatively poor suction capacity are in this case reduced by an inducer on the input side of the high-pressure stage, The pump is driven by a three-phase induction motor.

The suction stage (inducer) and the high-pressure stage are seated on a shaft and run at the same speed of rotation. The vertical gear arranged between centrifugal pump and prime mover or driving motor converts the motor speed from 3000 mien~1 to driving speeds up to ranges of about 40 000 min-'. Provided inside the gear are control instruments which supervise the operational conditions. A volumetric oil pump provides for a continuous circulation of lubricating oil inside the gear. Responsibility for regenerating the lubricating oil is assumed by filters and heat exchangers (Kleines Pumpenhandbuch fur Chemie und Technik, Verlag Chemie GmbH, Weinheim 1967).

One improvement carried out in the design of the gear has resulted in the oil pump and the heat exchanger being dispensed with, despite the high rotational speeds up to 40 000 mains' (German Offenlegungsschrift 22 13 731).

The requirement for varying the delivery flow on the installed centriiugal pump asseinbly in the industrial piant, is, within certain limits, primarily allowed for, by using the uneconomic reactance or throttling control.

Substantially more economic than the reactance control is the low-loss stepless speed control. With the multi-stage and single-stage centrifugal pump assemblies, the economic, stepless variation in delivery flow is not readily possible, for example, with the known electric prime movers. All prior known mechanical and electrotechnical devices for an infinitely variable regulation of the speed of rotation, as for example a fluid clutch, control gear, HF motor with frequency converter, d.c. motor with mercury-arc rectifier, and others, combined with the known multi-stage centrifugal pumps, are economically expensive solutions.

The object of the invention consists in providing a high-pressure centrifugal pump assembly which is more advantageous in a technical and economic respect as compared with the known constructional forms.

The invention has for its object to develop a high-pressure centrifugal pump assembly which is characterised by a greater delivery head, while simultaneously achieving an efficiency more tenable as regards energy consumption, very good intake behaviour of the first stage and also by the possibility of a low-loss delivery flow control while maintaining extremely small dimensions and weights.

According to the invention, the object is achieved by the fact that a single-part or multipart pump housing contains a low-revolution intake impeller and a high-revolution highpressure impeller which is arranged radially in one plane following the low-revolution intake impeller and of which the direction of rotation is the same as or opposite to that of the low-revolution intake impeller and a fixed distributor which is fixed in the pump housing and is arranged radially following the high-revolution high-pressure impeller, the drive of the low-revolution intake impeller and of the high-revolution high-pressure impeller occurring independently of one another at a constant or variable speed of rotation.

Another characteristic of the invention consists in that the drive of the low-revolution intake impeller is through a hollow shaft from a known, low-revolution prime mover, of which the speed may or may not be regulated and which is flanged on the intake side of the pump housing, whereas the drive of the high-revolution, high-pressure impeller is through a solid shaft from a known high-revolution prime mover, of which the speed may or may not be regulated and which is connected in tandem with the prime mover of the low-revolution intake impeller, the said solid shaft being guided through the said hollow shaft.

A further development of the invention is to be seen in that the drive of the high-revolution highpressure impeller is through a hollow shaft from a known high-revolution prime mover of which the speed may or may not be regulated and which is flanged on the pressure side of the pump housing, and the drive of the low-revolution intake impeller is through a solid shaft from a known lowrevolution prime mover, of which the speed may or may not be regulated and which is arranged in tandem with the prime mover of the highrevolution, high-pressure impeller, said solid shaft being guided through the said hollow shaft.

It is another feature of the invention that the drive of the low-revolution intake impeller through a shaft from a known low-revolution prime mover, of which the speed may or may not be regulated and which is flanged on the intake side of the pump housing, and the drive of the highrevolution, high-pressure impeller through a shaft from a known high-revolution prime mover, of which the speed may or may not be regulated and which is flanged on the pressure side of the pump housing, occur independently of one another.

It is also a feature of the invention that the drive of the low-revolution intake impeller through a shaft of a known low-revolution prime mover, of which the speed may or may not be regulated and which is flanged on the intake side of the pump housing, and the drive of the high-revolution highpressure impeller of a known low-revolution prime mover, of which the speed may or may not be regulated, is through a gear connected fast to the pressure side of the pump housing and the prime mover.

Finally, the invention is so developed that the prime movers are known direct-current motors fed by way of diodes or thyristors as rectifiers from the alternating-current or three-phase mains circuit, frequency-controlled three-phase motors, internal combustion engines or turbines.

The invention is hereinafter to be more fully explained by reference to one constructional example.

In the accompanying drawings: Figure 1 is a centrifugal pump assembly with a prime mover, arranged in tandem, Figure 2 is a centrifugal pump assembly with the prime mover arranged in tandem, but having pump stages arranged differently as compared with Figure 1, Figure 3 is a centrifugal pump assembly with prime movers arranged on both sides of the pump housing, Figure 4 is a centrifugal pump assembly with prime movers arranged on both sides of the pump housing, but with interposition of a gear for driving the high-pressure impeller, Figure 5 is the section A-A according to Figures 1 to 4.

In accordance with Figure 1, a low-revolution intake impeller 1 is contained in a single-part or multi-part pump housing 4. The intake impeller 1 is radially followed by a high-revolution highpressure impeller 2 which rotates in a direction which is the same as or opposite to that of the low-revolution intake impeller 1. A guiding device 3 disposed radially following the high-pressure impeller 2 is fixedly arranged in the pump housing 4. Flanged on the intake side of the pump housing 4 is a known, low-revolution prime mover 5 of which the speed may or may not be adjustable, the said prime mover driving the intake impeller 1 through a hollow shaft 8.Arranged in tandem with the prime mover 5 is a known, high-revolution prime mover 6, of which the speed may or may not be adjustable, said prime mover driving the high-pressure impeller 2, the drive being by way of a solid shaft 7, which is guided through the hollow shaft 8.

Represented in Figure 2 is a constructional form in which a single-part or multi-part pump housing 4 contains therein an intake impeller 1 and a highpressure impeller 2 arranged radially in the same plane as the intake impeller 1 and a guiding device 3 which is fixed in the pump housing 4 and which radially follows the high-pressure impeller 2.

Flanged on the pressure side of the pump housing 4 is a known, high-revolution prime mover 5 which may or may not be adjustable as regards speed of rotation and which drives the high-pressure impeller 2 through a hollow shaft 8.

Arranged in tandem with the prime mover 5 is a known, low-revolution prime mover 6 of which the speed may or may not be adjustable, said prime mover serving to drive the intake impeller 1, the drive being effected through a solid shaft 7, which - is guided through the hollow shaft 8.

Figure 3 shows a constructional form in which, in a single-part or multi-part pump housing 4, a high-revolution high-pressure impeller 2 is arranged radially following the low-revolution intake impeller 1 in the same plane and a guiding device 3 fixed in the pump housing 4 is likewise arranged radially following the high-pressure impeller 2. In order to drive the low-revolution suction or intake impeller 1 , the suction or intake side of the pump housing 4 has flanged thereon a known low-revolution prime mover 5, of which the speed may or may not be adjustable and which sets the intake impeller 1 in motion, directly through the shaft 9. Flanged on the pressure side of the pump housing 4 is a known, high-revolution prime mover 6 of which the speed may or may not be adjustable, said prime mover driving the highpressure impeller 2 by means of the shaft 10.

In the constructional example according to Figure 4, the arrangement of the intake impeller 1, the high-pressure impeller 2, the fixed guide arrangement 3 in the pump housing 4, and also the prime mover 5 for the low-revolution intake impeller 1, is the same as in Figure 3. Differing from the constructional form according to Figure 3, a known low-revolution prime mover 5 which may or may not be regulated as regards speed is provided for driving the high-revolution highpressure impeller 2. Connected fast between the prime mover 5 for driving the high-pressure impeller 2 and the pressurised side of the pump housing 4 is a gear 11, which imposes the required speed of rotation or the high-pressure impeller 2.

Figure 5 shows the section A-A of Figures 1 to 4, from which it is possible to see the arrangement of the low-revolution intake impeller 1, with the angular velocity w1, of the high-revolution highpressure impeller 2, with the angular velocity 2 and of the fixed guide device 3 in the pump housing 4.

The advantage of the invention consists in that, by the radial arrangement of the intake impeller, of the high-pressure impeller and of the guide device, arranged in one plane, a pump is established in a single-part or multi-part pump housing, which pump is characterised by small dimensions and weights. However, the most important advantage is to be seen in the fact that, in addition to the favourable arrangement of the impellers and guiding means, the driving of the impellers independently of one another is effected with low and high revolutions and also at a constant or variable speed of rotation. Using this centrifugal pump assembly, it is possible with different constructional forms to produce a large delivery head, a simultaneous and very good suction or intake performance, an efficiency which can be operated economically as regards energy and also an economic manufacture and operation.

Claims

1. A two-stage high-pressure centrifugal pump assembly for liquid, comprising a housing which contains a low-revolution intake impeller and a high-revolution high-pressure impeller arranged radially in a common plane, the high-pressure impeller following the intake impeller, a guide arrangement being fixed in the housing and radially following the high-pressure impeller, the drive of the intake impeller and the drive of the high-pressure impeller being effected independently of one another.

2. A pump assembly according to Claim 1 wherein the intake impeller is driven, via a hollow shaft, by a low-revolution prime mover which is flanged on the intake side of the housing, and the high-pressure impeller is driven, via a solid shaft passing through the hollow shaft, by a highrevolution prime mover which is arranged in tandem with the low-revolution prime mover.

3. A pump assembly according to Claim 1 wherein the high-pressure impeller is driven, via a hollow shaft, by a high-revolution prirne mover which is flanged on the pressure side of the housing, and the intake impeller is driven, via a solid shaft passing through the hollow shaft, by a low-revolution prime mover which is arranged in tandem with the high-revolution prime mover.

4. A pump assembly according to Claim 1 wherein the intake impeller is driven, via a first shaft, by a low-revolution prime mover which is flanged on the intake side of the housing, and the high-pressure impeller is driven, via a second shat by a high-revolution prime mover which is flanged on the pressure side of the housing.

5. A pump assembly according to Claim 1 wherein the intake impeller is driven, via a shaft, by a first low-revolution prime mover which is flanged on the intake side of the housing, and the high-pressure impeller is driven by a second low revolution prime mover through a gear interposed between the pressure side of the housing and the second prime mover and connected thereto.

6. A pump assembly according to any one of claims 1 to 5 wherein the prime movers are direct-current motors, frequency-controlled threephase motqrs, internal combustion engines or turbines.

7. A pump assembly according to any of Claims 1 to 6 wherein the speed of at least one of the prime movers is adjustable.

8. A two-stage high-pressure centrifugal pump assembly for liquid constructed, arranged and adapted to operate substantially as hereih described with reference to, and as shown in Figure 1, Figure 2, Figure 3 or Figure 4 of the accompanying drawings.