EP2054622B1 - Delivery pump - Google Patents

Abstract

The delivery pump has a variable-speed drive (5) and is configured as a single-stage centrifugal pump having a radial wheel (2), which rotates in a rotor space (6) of a pump housing (1), for conveying a fluid between a pump inlet (4) and a pump outlet (13). The radial wheel has delivery channels (3) and the centrifugal pump is designed for part-load operation. The delivery quantities of the centrifugal pump are in the range from 0 to 3600 milliliters per minute and in the case of delivery heights from 20 to 300 meters.

Description

The invention relates to a feed pump with a variable speed drive for a metered flow rate delivery, wherein the feed pump is designed as a single-stage centrifugal pump in a impeller space of a pump housing without a sealing gap rotationally arranged radial centrifugal type for conveying a fluid between a pump inlet and a pump outlet.

In the area of research and development processes in the chemical and pharmaceutical industry, there is a demand for ever faster developments at lower costs. In the production of such substances more flexible, smaller and more environmentally friendly processes are required. This leads to the use of procedural components, which are sometimes operated with very small filling volumes and continuous material flow. Due to the requirement of a flexible use of such systems, a good flushability of the entire system with the units mounted therein with the help of special flushing media is necessary.

Such systems require a precise, constant, freely adjustable and pulsation-free volume flow of liquid substances. For high-precision, continuous flow rates ranging from zero milliliters per minute up to three-digit liters per hour, positive displacement pumps are used in the form of micro gear and gear pumps as well as diaphragm and piston pumps. Disadvantage of such positive displacement pumps are the lack of reliability due to friction between the relatively moving, sealed components and their pulsating flow. A consequent maintenance and the cost of wearing parts and their replacement hinder rapid research and development and interfere with a production process sensitive.

By the WO 2005/052365 A2 is known as a canned motor pump centrifugal pump for the circulation of supercritical hydrocarbons known. The drive motor has a PEEK split tube inside which a rotor protected by a stainless steel coating is located. Ceramic bearings of the pump shaft and the drive rotor are lubricated by a partial flow of the pumped liquid taken from the pump housing. The open impeller has a diameter between 1 and 2 inches and the impeller driving rotor of the roller bearing DC motor has a diameter between 1.5 and 2 inches. The single-stage pumping device with the open impeller should reach maximum speeds of up to 60,000 rpm. Suction nozzle, discharge nozzle and a downstream of the impeller type of spiral space are arranged in an outer pump housing part, while an inner pump housing part has the cantilevered impeller and a mounting for a variable speed DC canned motor as a drive motor.

The publication GB2187232A , which will be the closest prior art, discloses the features of the preamble of claim 1.

A disadvantage of this canned motor design is the large number of columns, which hinder the cleaning of the pump due to the complex flow guidance between the pump and canned motor. Since a part of the pumped liquid flows through the motor and its gap permanently, created by the frictional heat of the bearings and the heat loss of the canned motor an unacceptably high heat input into the fluid.

The invention is based on the problem, for the promotion and dosage of liquid substances in the milliliter range of chemical, pharmaceutical and / or cosmetic components to develop a pump unit, the flow rate pulsation-free and precisely adjustable over a wide range for different Flow media with different properties is variable and for quick product change the pump is easy to clean.

The problem is solved with the features of claim 1. Thus, a metering pump is realized as centrifugal centrifugal type, which is designed for continuous operation in a partial load operating point field. Its flow limits are in the range of 0 ml / min to 3600 ml / min at delivery height limits of 20 m to 300 m. The impeller rotates without contact within an impeller space and a return flow within the wheel sidewalls is permitted. This ensures a wear-free operation of the impeller. And in complete contrast to all applicable centrifugal pump layout regulations, the centrifugal pump is designed for an extreme part-load operation, whereby small amounts are conveyed pulsation-free.

The diameter of the impeller space is at most 4% larger than an outer diameter of a radial wheel arranged therein and the impeller space is provided with one or more, acute-angled or tangential to Radialradaußendurchmesser arranged pump outlet channels. As a result, the delivery of the centrifugal pump results from a proportion of static pressure, which builds up due to the centrifugal force within the impeller space and a dynamic proportion in the form of the dynamic pressure, which occurs at the transition from the impeller space to the pump outlet in the form of a Druckstutzen- or outlet channel. The dynamic pressure component at the outlet opening from the impeller space corresponds to a maximum. The addition of the centrifugal delivery head component and the delivery head component due to the back pressure to a total delivery head of the pump results in the high pressure factor for this type of pump.

In complete contrast, conventional centrifugal pumps are designed in which the pressure build-up predominantly by a speed delay due to an increase in the downstream of the impeller flow space results in the flow direction.

To get along with minimal loss of valuable funding in a cleaning of the feed pump or a conversion to other funding, has the pump housing with a radial wheel disposed in the region between a pump inlet and a pump outlet whose cross-sectional areas are defined by contact surfaces of lines to be connected, a residual volume equal to or less than 50 milliliters. A batch or product change results in a minimal loss with faster pump cleanability.

For the promotion of different funding, the pump housing is provided with a tempering device. Thus, a simple temperature adjustment is possible. In this case, the tempering device may be formed as a heat exchanger which completely or partially surrounds the wetted parts of the pump housing. For this purpose, liquid-tight connections penetrate the tempering device and establish a fluid-conducting connection between a system and the impeller space. Depending on the temperature of the delivery fluid, the pump housing is disposed within the tempering device to cool or heat the delivery fluid.

The radial wheel has at least two delivery channels and at the Radialradaußendurchmesser several conveyor wells are arranged. These arranged on the radial wheel conveyor wells are designed as blind holes, pockets or tooth-shaped recesses. The delivery channels are formed as open recesses in the form of blade channels, grooves or grooves. In one embodiment of the radial wheel as a closed impeller, a suction and / or pressure-side cover disk can have known conveying grooves.

In the radial wheel, the number and arrangement of the inlet openings of the delivery channels is chosen so that they do not increase a Radialradeintrittsdurchmesser. Thus, with the small dimensions, a maximum area on the impeller for generating the centrifugal forces is obtained.

A sealing of the impeller space relative to the atmosphere or the tempering takes place with one or more shaft seals between a housing wall of the impeller space and a rotary Radialrad- or a shaft part penetrating them. These can be known shaft seals or low-friction mechanical seals. Such seals can be dispensed with if a hermetically sealed, magnetically coupled drive transmits a torque to the radial wheel. This can also be designed as a tear-resistant hysteresis coupling. Next can be connected to the radial wheel an electric, pneumatic or hydraulic drive. Such a drive motor is attached to the pump or Temperiergehäuse and connected via a guided through this housing shaft with the radial wheel. The arranged in the drive motor bearing the rotor shaft can be found in a conventional manner at the same time as storage of the pump shaft and the radial wheel use.

In addition, a heat barrier between the drive motor and the tempering and / or pump housing may be arranged, wherein the drive motor is connected via a shaft performed with the radial wheel. Connecting zones between the parts of the pump housing and the temperature control housing are rotationally symmetrical and sealed against each other. This provides an improved seal important in the promotion of very small quantities of hazardous or valuable fluids in the form of liquid chemicals and / or solutions. Due to the controllable drive of the centrifugal pump designed for continuous operation in the extreme part-load range, a uniform pulsation-free adjustable delivery of very small amounts of such fluids is possible.

Furthermore, the feed pump is connected to a control device, which is connected to an internal or external volume flow measurement and independent of a back pressure of a system with the drive motor generates an adjustable constant volume flow. With the control device, a variable speed range of the drive motor with a quantity factor up to the value 5000 is generated in the switching or control range between minimum and maximum delivery. And in the speed range of the drive motor from 0 to 35000 revolutions / min is a centrifugal pump delivery pressure between 0 to 300 bar. Such centrifugal pump operating data are only possible due to the contrary to all known design rules interpretation of radial wheel and housing of the pump unit for an extreme permanent part-load operation. For simple installation options, the pump unit, drive motor, switching or control device and associated electronic operating, measuring and control elements are combined to form an assembly-capable module.

Fig. 1

eine Förderpumpe im Längsschnitt,

Fig. 2

eine perspektivische Ansicht auf die Pumpeneinheit, die

Fig. 3

eine perspektivische Ansicht auf ein Laufrad, die

Fig. 4

ein Laufrad im Schnitt und die

Fig. 5

einen Querschnitt durch die Förderpumpe

Embodiments of the invention are illustrated in the drawings and will be described in more detail below. It show the

Fig. 1

a feed pump in longitudinal section,

Fig. 2

a perspective view of the pump unit, the

Fig. 3

a perspective view of an impeller, the

Fig. 4

an impeller in the section and the

Fig. 5

a cross section through the feed pump

In Fig. 1 is a delivery pump in a single-stage design shown. In the pump housing 1, a radial wheel 2 centrifugal type is arranged to rotate. The radial wheel 2 has delivery channels 3 and is centrally through a pump inlet 4 flows. The radial wheel 2 is connected to transmit power to a variable speed drive 5 and has an outer diameter D _LA , which may be up to 50 mm. The radial wheel rotates in an impeller space 6, the inner diameter D _{LRI is designed to be} only 4% larger than the outer diameter D _{LA of} the radial wheel 2.

The pump housing 1 is provided with a tempering device 7, which is integrated in this embodiment in the pump housing. There are also other designs possible. Fridges 7.1 to 7.3 surround the impeller space 6 and also adjacent to the pump housing 1 seal housing 8. Within the seal housing 8 is arranged as a kind of shaft seal a seal 9, which is shown in the embodiment as a lip seal. Depending on the fluid used, the seal 9 may also be formed as a mechanical seal. The seal 9, depending on the selected connection between the impeller and a shaft 10 of the drive sealingly against the impeller 2, on an impeller hub 2.1 or on the shaft 10. The tempering 7.1 to 7.3 are acted upon by external means. As a result, the parts of the pump housing contacted by the delivery fluid are reliably cooled, since the centrifugal pump is designed for continuous operation in a partial load operating point field whose delivery limits are in the range of 0 milliliter / min. up to 3600 milliliters / min. at a headroom limit of 20 meters - 300 meters. As a result of the necessary high speed of the drive 5 additional coolant 11 are arranged on the outer circumference of the drive 5. And the drive 5 is connected to transmit power to the tempering device 7 or attached thereto.

The area of the pump inlet 4 is defined by a contact surface 12 located in the immediate vicinity of the pump interior, against which a line to be connected for a delivery fluid bears sealingly. An analogous training is on the - here below the drawing plane, only partially visible as a semicircle - pump outlet 13 is present. The attachment of it to be connected pump lines - not shown here - by known means, such as union nuts. By the immediate approach of a pump line to the impeller space 6 and the small differences in diameter between impeller outer diameter D _LA and inner diameter D _{LRI of} the impeller _chamber 6, results within the pump housing with mounted radial wheel for a fluid delivery a residual volume of equal to or less than 50 milliliters. This very small amount has the advantage that only a slight loss occurs when changing the valuable production fluids.

From the Fig. 2 , the perspective view of the unitary pump, the pump inlet 4 and the pump outlet 13 can be seen. The tempering device 7 is integrated in the pump housing 1 and pump inlet 4 and pump outlet 13 are passed through the tempering 7 to the impeller space.

External temperature control, for example, coolant, are fed through the optional axial or radial ports 14, 15 the temperature control chambers 7.1 to 7.3 and derived. Pump unit and drive motor 5 are combined to form a structural unit and held in a support member 16. The support element 16 provides the prerequisite for the modular design or installation in an existing system.

Fig. 3 shows a perspective view of a radial wheel 2. The radial wheel 2 is designed disc-shaped and provided in this example with a hub 2.1. Within the hub 2.1 is a force-transmitted connection with the shaft 10, not shown here of the drive 5. Within the radial wheel 2, four conveyor channels 3 are arranged. In addition, a plurality of conveying recesses 18 are arranged on the impeller periphery 17, which are designed in the form of blind holes. With the help of these delivery wells, the pressure coefficient of the centrifugal impeller is significantly improved. In addition, the pressure and suction side shrouds 19, 20 a plurality of radially extending conveyor grooves 21. The feed grooves 21 also improve the pressure digit of one Fig. 1 in an impeller room 6 built-in impeller. The impeller in the axial direction penetrating compensation bores 22 serve to equalize pressure within the pump housing and at the same time as an assembly aid in the preparation of a connection to the drive.

Fig. 4 shows a section through an impeller 2. It can be seen that here only a total of four conveyor channels 3 are used. Their diameter is adjusted so that they do not intersect an adjacent conveyor channel in the region of the impeller inlet 23. Thus, the maintenance of a defined impeller inlet diameter is guaranteed. The depth T of the conveying recesses 18 is selected as a function of the desired residual volume of a fully assembled pump.

Instead of the conveying recesses 18 shown here in the form of bores, any other shape, such as grooves, slots or the like, find application, with which in the range of the impeller outer diameter, an energy transfer is possible.

Fig. 5 shows a cross section through the feed pump. Due to the generous temperature control room 7.2, which is in operative connection with the other temperature control room, a permanent extreme partial load operation is guaranteed.

The minimized impeller space 6 results between the outer diameter D _{LA of} the radial wheel and the enveloping, surrounding diameter D _{LRI of} the impeller _space 6 a radial gap _width which is in the single-digit millimeter range. With a centrifugal pump running, the radial gap between impeller and housing is in the range of 2 mm. In the area of the axial impeller sides, the gap between the impeller and the housing is of an analogous order of magnitude. As a result of this configuration of the area in the housing which has a minimal residual volume, the pump can be cleaned very quickly and reliably by a flushing medium. And with lowest losses of production product parts be adapted to changed conditions or facilities. The continuous rotation of the centrifugal impeller 2 results in a pulsation-free operation of this feed pump.

Due to the minimized gap between impeller outer diameter and impeller space, the peripheral component of the impeller simultaneously approaches the peripheral speed and in combination with an obliquely inclined, preferably tangential, impeller 2 disposed pump outlet 13 results for this centrifugal pump at the outlet opening a maximum possible back pressure. In conjunction with the variable-speed motor, high delivery heads can be realized with a minimum residual volume within the pump housing.

The non-contact arrangement of the impeller within the impeller space avoids sealingly abutting friction surfaces. This measure prevents the generation of mechanical frictional heat, prevents fretting and consequent contamination of a pumped liquid with abraded particles and improves reliability through significantly extended periods of use. In addition, the cleanability counteracting sealing gaps are avoided.

LIST OF REFERENCE NUMBERS

1 =

pump housing

2 =

radial

2.1 =

hub

3 =

conveying channels

4 =

pump inlet

5 =

adjustable drive

6 =

impeller chamber

7 =

tempering

7.1 - 7.3 =

refrigerators

8 =

seal housing

9 =

poetry

10 =

Wave,

11 =

coolant

12 =

contact surface

13 =

pump outlet

14, 15 =

Connections for temperature control

16 =

supporting member

17 =

wheel circumference

18 =

conveyor wells

19, 20 =

cover disc

21 =

transporting grooves

22 =

equalization bores

23 =

impeller inlet

D _LA =

Outer diameter radial wheel 2

D _LRI =

Inner diameter impeller space 6

Claims (20)

1. Feed pump with a variable-speed drive (5) for metered dispensing of feed quantity, the feed pump being constructed as a single-stage centrifugal pump with a radial wheel (2) of centrifugal structure, arranged rotationally, without a sealing gap, in an impeller chamber (6) of a pump casing (1), in order to convey a fluid between a pump inlet (4) and a pump outlet (13), the radial wheel (2) being connected to a drive motor of variable rotational speed having a five-digit range of revolutions per minute, the radial wheel (2) receiving the flow centrally, being provided with feed ducts (3) and having an outside diameter of up to 50 mm, characterized in that, for use in a process engineering system with continuous feed quantities, the centrifugal pump is constructed for partial-load operation, the feed quantities of which lie in the range of 0 ml/min to 3600 ml/min and with lifts of 20 m to 300 m, in that an inside diameter (D_LR1) of the impeller chamber (6) is constructed to be at most 4% larger than an outside diameter (D_LA) of the radial wheel (2), in that a seal (9) is arranged between the impeller chamber (6) and the radial wheel (2) and/or its shaft (10), and in that the impeller chamber (6) is provided on the circumference with one or more pump outlet ducts (13) arranged at an acute angle or tangentially to the outside diameter of the radial wheel.
2. Feed pump according to Claim 1, characterized in that the pump casing (1), with a radial wheel (2) arranged in it, has a residual volume equal to or smaller than 50 milliliters in the region between a pump inlet (4) and a pump outlet (13), the cross-sectional areas of which are defined by bearing surfaces of lines to be connected to them.
3. Feed pump according to Claim 1 or 2, characterized in that the pump casing (1) is provided with a heat regulating device (7 - 7.3).
4. Feed pump according to Claim 3, characterized in that the heat regulating device (7) is constructed as a heat exchanger, and completely or partially surrounds the parts of the pump casing (1) and/or of the impeller chamber (6) contacted by the pumped fluid.
5. Feed pump according to one or more of Claims 1 to 4, characterized in that fluid-tight connections extend through the heat regulating casing (7) and connect a system to the impeller chamber (6).
6. Feed pump according to one or more of Claims 1 to 5, characterized in that the radial wheel (2) has at least two feed ducts (3), and a plurality of feed depressions (18) are arranged on the outside diameter (D_LA) of the radial wheel.
7. Feed pump according to Claim 6, characterized in that the feed depressions (18) on the radial wheel (2) are configured as blind bores, pockets or tooth-shaped recesses.
8. Feed pump according to Claim 6 or 7, characterized in that the feed ducts (3) are constructed as open depressions in the form of blade channels, grooves or flutes.
9. Feed pump according to one of Claims 1 to 8, characterized in that suction-side and/or delivery-side impeller cover discs are provided with feed grooves known per se.
10. Feed pump according to one of Claims 1 to 9, characterized in that the number and the arrangement of the inlet orifices of the feed ducts (3) of the radial wheel (2) do not enlarge a radial-wheel inlet diameter.
11. Feed pump according to one of Claims 1 to 10, characterized in that a hermetically leak-tight magnet-coupled drive transmits a torque to the radial wheel (2).
12. Feed pump according to one of Claims 1 to 11, characterized in that an electric, pneumatic or hydraulic drive is connected to the radial wheel (2).
13. Feed pump according to one or more of Claims 1 to 12, characterized in that the drive motor (5) is fastened to the pump device (1) or heat regulating device (7) and is connected by means of a shaft (4) extending through it to the radial wheel (2).
14. Feed pump according to one or more of Claims 1 to 12, characterized in that a thermal barrier is arranged between the drive motor (5) and the heat regulating device (7) and/or pump casing (1), and the drive motor (5) is connected to the radial wheel (2) via a shaft (4) which extends through the thermal barrier.
15. Feed pump according to one or more of Claims 1 to 14, characterized in that connection zones between the parts of the pump casing (1) and the heat regulating device (7) have a rotationally symmetrical configuration and are sealed relative to one another.
16. Feed pump according to one or more of Claims 1 to 15, characterized in that a regulating device is connected to an internal or external volume flow measurement device and generates an adjustable constant volume flow by means of the drive motor (5) independently of the back-pressure of the system.
17. Feed pump according to one or more of Claims 1 to 16, characterized in that a variable rotational speed range of the drive motor (5) generates a quantity factor up to the value of 5000 in the switching or regulating range between a minimum and maximum feed quantity.
18. Feed pump according to one or more of Claims 1 to 17, characterized in that, in the rotational speed range of the drive motor (5) of 0 to 35 000 revolutions/minute, a centrifugal pump feed pressure lies between 0 and 30 bar.
19. Feed pump according to one or more of Claims 1 to 18, characterized in that the radial wheel (2) and the casing of the centrifugal pump are constructed for extreme continuous part-load operation.
20. Feed pump according to one or more of Claims 1 to 19, characterized in that the pump, drive motor, switching or regulating device and associated electronic operating, measuring and control elements are combined into a mountable module.

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