EP2142804A1

EP2142804A1 - Delivery pump

Info

Publication number: EP2142804A1
Application number: EP08735086A
Authority: EP
Inventors: Axel Binder; Christoph Jäger; Christoph Keller
Original assignee: KSB AG
Current assignee: KSB AG
Priority date: 2007-04-28
Filing date: 2008-04-08
Publication date: 2010-01-13
Also published as: CN101680456A; JP2010525223A; AU2008243437A1; DE102007020218A1; WO2008131846A1; TW200916660A; ZA200905469B; US20100111680A1

Abstract

The invention relates to a delivery pump comprising a variable-speed drive (5), wherein the delivery pump is designed as a single-stage rotary pump having a radial impeller (2) of a centrifugal type rotatively located in an impeller chamber (6) of a pump housing (1) for delivering a fluid between a pump inlet (4) and a pump outlet (13). The radial impeller (2) is connected to a variable-speed drive motor capable of speeds in the range of 5-digit revolutions per minute, the radial impeller (2) being centrally subjected to flow, being provided with delivery channels (3), and with an external diameter of up to 55 mm being capable of delivery heights of up to 300 m, depending on speed. For use in a process engineering system, the delivery pump is designed for nominal operation in the form of a permanent rotary pump partial load operation for delivery quantities in the range of 0 ml/min to 7000 ml/min. The nominal operation is characterized by a rotary pump partial load-specific rotational speed nq TL ≥ 0.05 < 10 (1/min), and the impeller chamber (6) comprises one or more pump outlet channels (13) located on the circumference at acute angles or tangentially to the radial impeller outer diameter.

Description

K S B A k t i e n g e s e n c e s a t e

description

feed pump

The invention relates to a feed pump with a variable-speed drive, wherein the feed pump as a single-stage centrifugal pump with in a impeller space of a pump housing (1) rotatably mounted radial wheel (2) centrifugal design for conveying a fluid between a pump inlet (4) and a pump outlet (13) is, the radial wheel (2) is connected to a up to the five-digit range of revolutions per minute variable speed drive motor, the radial wheel (2) is centrally flowed, with delivery channels (3) is provided and with an outer diameter up to 55 mm at Has delivery heights up to 300 m.

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 materials, more flexible, smaller and more environmentally friendly processes are required. This leads to the use of process components, some of which are 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 by means 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 volume flows in the range of zero milliliters per minute to a three-digit number of liters per hour, positive displacement pumps in the form of micro-toothed ring and gear pumps as well as in the form of diaphragm and piston pumps are used. 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 related maintenance and the cost of wear and tear Parts as well as their change hinder rapid research and development and interfere with a production process sensitive.

WO 2005/052365 A2 discloses a centrifugal pump in the form of a canned motor pump for circulating supercritical hydrocarbons. The drive motor has a split tube made of PEEK ₁ within which a rotor protected by a stainless steel coating is arranged. 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-formed impeller has a diameter between see 1 and 2 inches and the rotor driving the rotor of the roller-mounted 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 type of spiral space downstream of the impeller 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.

A disadvantage of this canned motor design is the large number of gaps, which greatly hinder the cleaning of the pump due to the complex flow guidance between pump and canned motor. Since part of the pumped liquid continuously flows through the motor and its gap, the frictional heat of the roller bearings and the heat loss of the canned motor cause a high heat input into the pumped liquid. As a result, this pump can only be operated in close proximity to an undefined optimum operating point. In a partial load operation of this pump, an inadmissibly high heat input would take place very quickly. This would in addition to damage to the fluid also a failure of the pump due to cavitation or dry running result.

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 media is variable with different characteristics and for quick product changes the pump is easy to clean.

The solution to the problem occurs with the features of claim 1. Thus, a metering pump in the form of a centrifugal centrifugal centrifugal design is realized. This is designed as a feed pump for use in a process plant for a nominal operation in the form of a permanent centrifugal pump partial load operation with flow rates in the range of 0 ml / min to 7000 ml / min, the rated operation by a centrifugal pump part-load specific speed nq _T L ≥ 0.05 <10 (1 / min) is characterized and wherein the impeller space is provided at the periphery with one or more, acute-angled or tangential to Radialradaußendurchmesser arranged Pumpenauslasskanälen.

In complete contrast to all applicable centrifugal pump design rules or regulations, this centrifugal pump is designed for extreme part-load operation, which promotes small amounts without pulsation. For this purpose, the feed pump preferably has a centrifugal pump partial load-specific speed nq _T L ≥ 0.05 <3 (1 / min). Advantageously, the design of the feed pump for a centrifugal pump partial load operating range nq - _{TL has} proven <2.5. The outer diameter of the radial wheel (2) can be up to a maximum of 70 mm.

According to further embodiments, the pump housing with a radial wheel arranged therein preferably has a residual volume of less than 30 milliliters. This has the significant advantage of easy flushing of the feed pump. And as a result of the small residual volume and the minimum number of slots, only a small loss of product occurs during a cleaning or flushing of a fluid to be delivered in the feed pump. Furthermore, an inner diameter of the impeller space is formed at most 4% larger than an outer diameter of the radial wheel. And by means of a reduction of the impeller space surrounding the radial wheel takes place at the Pumpenauslasskanal an increase in a pending there pitotast. there the inlet openings of one or more Pumpenauslasskanälen are formed in the form of pitot tubes or pitot tube-like.

According to another embodiment of the feed pump this is provided with a tempering device, preferably for a nominal operation with a centrifugal pump partial-speed specific speed nq _T L ≥ 0.05 <1 (1 / min).

This improves the delivery of sensitive fluids and / or low-boiling-point fluids through the feed pump operable in a large nq _T L range.

According to another embodiment, a seal is arranged between the impeller space and the radial wheel and / or its shaft. Likewise, an embodiment is possible in which a hermetically sealed, magnetically coupled drive transmits a torque to the radial wheel. And on the pump housing, the tempering and / or on a bearing housing a bearing for the shaft is arranged. Also, the feed pump may be formed as a block aggregate with flanged engine.

Depending on a drive to be used, the feed pump is characterized by a constant travel operation or a metering operation.

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

Fig. 1 is a feed pump in longitudinal section

Fig. 2 is a perspective view of the pump unit, the

Fig. 3 is a perspective view of an impeller, the

Fig. 4 is an impeller in section, the

5 shows a cross section through the feed pump and FIG. 6 shows the position of the feed pump in a nq diagram In Fig. 1, a feed pump is shown in a single-stage design. 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 DL _A , which may be up to 70 mm. The radial wheel rotates in an impeller space 6 whose inner diameter D _L RI is designed to be at most 4% larger than the outer diameter DLA 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 conveying fluid used, the seal 9 can also be designed 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. This reliably cools the parts of the pump housing that are in contact with the pump fluid, as the centrifugal pump is designed for continuous operation in a part-load operating point range whose flow limits range from 0 milliliter / min to 3600 milliliter / min, with a head 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 the tempering device 7 in a force-transmitting manner or fastened 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 direct approach of a pump line to the impeller space 6 and the small differences in diameter between impeller outer diameter DLA and inner diameter D _L RI of the impeller space 6, results within the pump housing with mounted radial wheel for a delivery fluid 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 Fig. 2, the perspective view of the unitized 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 tempering means, for example, coolants, are fed and discharged through the optionally usable axial or radial ports 14, 15 to the temperature control chambers 7.1 to 7.3. 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 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 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 wells the pressure digit of the centrifugal impeller is improved. In one possible embodiment, the pressure and suction-side cover disks 19, 20 have a plurality of radially extending feed grooves 21. The conveyor grooves 21 also improve the pressure digit of a built-in impeller 6 in accordance with FIG. 1 impeller. The impeller in the axial direction penetrating compensation bores 22 serve to equalize the pressure within the pump housing and at the same time as an assembly aid in making a connection to the drive.

4 shows a section through an impeller 2, in which 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 pump outlet channel 13 may be designed as a simple bore or it may - as shown - be formed by a pitot tube-like insert 24 having an inlet opening 25. The latter allows for easy customization.

Due to the minimized impeller space 6, a radial gap width, which lies in the single-digit millimeter range, results between the outside diameter DL _{A of} the radial wheel and the enveloping, surrounding diameter D _LR I of the rotor wheel space 6. 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 the lowest losses of conveying product parts to changed delivery conditions or plants. be fit. 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 wear and the resulting contamination of a pumped liquid with abraded particles, and improves the operational safety through significantly extended service lives. In addition, the cleanability counteracting sealing gaps are avoided.

In FIG. 6, the nq values of centrifugal pumps are compared with those of the positive displacement pumps in a nq diagram in characteristic diagrams drawn with solid lines. The new delivery pump covers the area between these two opposing pump types with its characteristic diagram of the centrifugal pump partial-load-specific speed nq γ _L.

LIST OF REFERENCE NUMBERS

1 pump housing

2 radial wheel

2.1 = hub

3 conveyor channels

4 pump inlet

5 adjustable drive

impeller chamber

7 tempering device

7.1 - 7.3 = cold rooms

8 seal housing

9 seal

10 wave

11 coolant

12 contact surface

13 pump outlet

14, 15 = connections for temperature control

16 supporting element

17 impeller circumference

18 production wells

19, 20 = cover disk

21 conveyor grooves

22 compensation holes

23 impeller entry

24 entrance opening

25 pitot tube

DLA = outer diameter of radial wheel 2

DLRI = inner diameter impeller space 6

Claims

Patent claims

1. Feed pump with a variable-speed drive (5), the feed pump being a single-stage centrifugal pump with a centrifugal radial wheel (2) arranged to rotate in an impeller space (6) of a pump housing (1) for conveying a fluid between a pump inlet (4) and a pump outlet (13), the radial wheel (2) is connected to a drive motor that can be varied in speed up to the five-digit range of revolutions per minute, the flow flows from the center of the radial wheel (2), and is provided with delivery channels (3). an outer diameter of up to 55 mm and speed-dependent delivery heads of up to 300 m. characterized in that for use in a process engineering system, the feed pump is designed for nominal operation in the form of permanent centrifugal pump partial load operation with delivery rates in the range of 0 ml/min to 7000 ml/ min is designed that the nominal operation is characterized by a centrifugal pump partial load-specific speed nq TL ≥ 0.05 < 10 (1/min), and that the impeller space (6) on the circumference with one or more, acute angle or tangential to the radial wheel outer diameter arranged pump outlet channels (13).

2. Feed pump according to claim 1, characterized in that the nominal operation preferably has a centrifugal pump partial load-specific speed nq _T L ≥ 0.05 <3 (1/min).

3. Feed pump according to claim 1 or 2, characterized in that the feed pump is designed for a centrifugal pump partial load operating range nq _T L <2.5.

4. Feed pump according to claim 1, 2 or 3, characterized in that the outer diameter of the radial wheel (2) is a maximum of 70 mm.

5. Feed pump according to one of claims 1 to 4, characterized in that the pump housing (1) with a radial wheel (2) arranged therein preferably has a residual volume of less than 30 milliliters.

6. Feed pump according to claim 5, characterized in that an inner diameter (D _LRI ) of the impeller space (6) is a maximum of 4% larger than an outer diameter (D _LA ) of the radial wheel (2).

7. Feed pump according to claim 4 or 5, characterized in that by reducing the size of the impeller space (6) surrounding the radial wheel (2).

Pump outlet channel (13) increases the dynamic pressure there.

8. Feed pump according to one or more of claims 1 to 7, characterized in that inlet openings (24) of one or more pump outlet channels (13) are designed in the form of pitot tubes (25) or similar to pitot tubes.

9. Feed pump according to one or more of claims 1 to 8, characterized in that the pump housing (1) is equipped with a temperature control device (7 -

7.3).

10. Feed pump according to claim 9, characterized in that preferably for a nominal operation with a centrifugal pump partial load-specific speed nq TL > 0.05 < 1 (1/min) the pump housing (1) with a temperature control device (7 -

7.3).

11. Feed pump according to one or more of claims 1 to 10, characterized in that a seal (9) is arranged between the impeller space (6) and the radial wheel (2) and / or its shaft (10).

12. Feed pump according to one of claims 1 to 11, characterized in that a hermetically sealed, magnetically coupled drive transmits a torque to the radial wheel (2).

13. Feed pump according to one of claims 1 to 12, characterized in that a bearing for the shaft (10) is arranged on the pump housing (1), on the temperature control housing (7) and / or on a bearing housing.

14. Feed pump according to one of claims 1 to 13, characterized in that the feed pump is designed as a block unit.

15. Feed pump according to one or more of claims 1 to 14, characterized by a constant driving operation or a metering operation.