Sheathed housing pump with ventilation device and subordinate method

Abstract

The present invention relates to a centrifugal pump with a sheath housing (1). An insert is arranged in the sheath housing (1). The insert (2) has a shaft (3). At least one impeller (4) is arranged on the shaft (3). The impeller is surrounded by a stage housing (5). The stage housing (5) separates the internal pressure space (9) from the external pressure space (10). According to the invention, at least one ventilation device (8) is arranged in the stage housing (5).

Description

Field of the Invention

[0001] The present invention relates to a centrifugal pump (Kreiselpumpe) with a casing (Mantelgehäuse) according to the present invention. Background Art

[0002] An insert is arranged in the casing, the insert having a shaft on which at least one impeller (Laufrad, sometimes referred to as an impeller) is arranged, the at least one impeller being surrounded by a stage casing (Stufengehäuse) that separates an internal pressure space from an external pressure space.

[0003] Such a type of centrifugal pump is also referred to as a casing pump, a double-casing pump or a "barrel-type" pump or a can-type pump. Such a casing pump is described, for example, in document DE4005923A1.

[0004] The pump is surrounded by a can-like casing. Usually the pump is a multi-stage pump for use as a high-pressure pump and an ultra-high-pressure pump, especially also for use as a boiler feed pump in a power station. In addition, such multi-stage casing pumps are used in the steel industry and in petrochemistry, for example in refineries.

[0005] A centrifugal pump of the can-type casing is described in document DE4310467A1. A flow-guiding stage casing is arranged between the respective pump impellers.

[0006] Document DE29819363U1 relates to a centrifugal pump with a casing. The casing has an inlet through which the transport medium flows in. An insert is arranged in the casing. The insert includes a shaft on which a plurality of impellers and guide wheels with associated stage casings are arranged. The stage casing separates an internal pressure space in which the impellers are arranged from an external pressure space between the stage casing and the casing.

[0007] Casing pumps must undergo a pressure test before their use. For this purpose, the casing forming the pressure shell of the pump is designed for the maximum discharge pressure on the pressure side in a conventional casing pump. The pressure test must be carried out before the final installation. Summary of the Invention

[0008] The object of the present invention is to create a casing pump in which a pressure test in the installed state is possible. The pump should be outstanding through a reliable and cost-effective operating mode. In addition, the pump should have a long life. In addition, the casing pump should be manufacturable as inexpensively as possible and the casing pump should be outstanding through simple installation. Repeated testing in the equipment should be time-saving and risk-free.

[0009] This task is solved by a centrifugal pump according to the invention. Preferred embodiments are implemented in the description.

[0010] In the stage housing of the centrifugal pump according to the invention, openings for ventilation are introduced. The centrifugal pump according to the invention makes it possible to fill the pump in the fully installed state by automatically ventilating the stage housing. Contrary to conventional canned motor pumps, in which air cannot escape from the internal pressure space through the stage housing because the separating seam between the stage housings is metallically sealing, the pump according to the invention has a ventilation device.

[0011] The ventilation device preferably comprises at least one opening that connects the internal pressure space to the external pressure space. In conventional centrifugal pumps, for example in power plants or refineries, retrofitting the pump for hydrostatic testing takes several working days. This significant time expenditure is largely saved when using the canned motor pump according to the invention, because at least partial disassembly of the pump and separation of the pressure shell into a high-pressure space and a low-pressure space by means of special tools is dispensed with. This makes a significant cost reduction possible, because in power plants or refineries several canned motor pumps are often operated in parallel and a significant amount of work expenditure is saved in each of the pumps by the design according to the invention.

[0012] The pump is filled in the fully installed state and air can escape from the internal pressure space through the opening in the stage housing via the ventilation device. Thus, a canned motor pump with automatic ventilation of the stage housing is created.

[0013] In a particularly suitable embodiment of the invention, the ventilation device comprises an element that can cause the opening of the medium exchange from the internal pressure space to the external pressure space or block the medium exchange between the internal and external pressure spaces. This element makes it possible for air to escape first from the internal pressure space through the ventilation device when filling the canned motor pump. If the canned motor pump is filled with a working medium such as water, the element closes the opening and thus blocks the medium exchange between the internal and external pressure spaces. Thereby, it is prevented that the working medium flows from the external pressure space into the internal pressure space.

[0014] The element is preferably arranged in a guide. The guide makes it possible to displace the element. By means of this displacement, it is possible for the element to either open the medium exchange between the internal and external pressure spaces (for example for ventilation) or block the medium exchange, so that after filling the canned motor pump, the operating fluid cannot flow back from the external pressure space into the internal pressure space.

[0015] In addition, a receiving portion can be introduced into the stage housing, and the component is arranged in the receiving portion. The receiving portion can be a hole, in which, for example, a cylindrical or plate-shaped component is arranged. Here, the lateral guiding portion and the movement limit of the component are formed by the wall of the receiving portion.

[0016] Preferably, the opening transitions into the receiving portion. Thus, for example, the opening can also be implemented as a hole in the stage housing, where the diameter of the opening hole is smaller than the diameter of the receiving portion hole, and the component is placed in the receiving portion hole. Therefore, the connection introduced in the stage housing between the internal and external pressure spaces expands from the smaller opening diameter to the larger receiving portion diameter, which not only serves as a sealing surface but also for the movement limit of the component for sealing.

[0017] According to the invention, there is always still a sufficiently large free cross-section between the wall of the receiving portion and the component that enables air to escape. Air flows through the opening into the receiving portion and then through the free cross-section between the component and the wall of the receiving portion into the external pressure space.

[0018] The component is configured to be larger than the opening. This feature is a prerequisite for the component to be able to close the opening when the operating medium flows back. In this design of the invention, the ventilation device is thus equipped with backflow protection. If the pressure in the external pressure space rises above the pressure in the internal pressure space, the component is pushed against the opening and prevents the medium exchange.

[0019] The cylindrical or plate-shaped component is here pushed against the bottom of the receiving portion and closes the opening introduced in the bottom of the receiving portion by means of a suitable sealing surface design (for example, an annular protrusion pointing towards the stage housing, which is formed as a single piece with the component).

[0020] Preferably, the ventilation device has a stop for the component. The stop can be arranged, for example, at the wall of the receiving portion. The stop can be a protrusion that extends into the receiving portion and thus prevents the component from rushing out of or jamming in the receiving portion. Preferably, the stop only extends into the receiving portion at some locations, so that there is always still a free cross-section for air to escape.

[0021] The ventilation device is preferably arranged in the upper region of the stage housing, where especially the 12 o'clock position is suitable because air accumulates at the highest point.

[0022] Another object of the invention is to provide a method for performing a pressure test on a sheathed housing pump for use.

[0023] According to the invention, the sheathed housing pump is first fully installed. Then, the centrifugal pump is filled with the operating medium. In the method according to the invention, air can escape from the stage housing in the fully installed state. Description of the Drawings

[0024] Additional advantages and features of the present invention result from the description of the embodiments according to the drawings and from the drawings themselves.

[0025] Here:

[0026] Figure 1 An axial section through the sheathed housing pump is shown.

[0027] Figure 2 A schematic view of the ventilation device is shown. Detailed Description

[0028] Figure 1 A centrifugal pump with a sheathed housing 1 is shown. An insert 2 is arranged in the sheathed housing 1. The insert 2 includes a shaft 3, on which a plurality of impellers 4 are arranged in sequence. The impellers 4 are radial-flow wheels in this embodiment.

[0029] Each impeller 4 is surrounded by a stage housing 5. The adjacent stage housings 5 are adjacent to each other. The separating seams between the stage housings 5 are metallically sealed in the embodiment.

[0030] A suction connection 6 is molded at the sheathed housing 1, through which the operating medium enters the centrifugal pump. The operating medium leaves the centrifugal pump through a pressure connection 7.

[0031] According to the invention, ventilation devices 8 are respectively arranged at the 12 o'clock position in the upper region in the pressure housing 5. The sheathed housing pump according to the invention can thus be pressure-tested in the fully installed state. This is only made possible by the integrated ventilation device 8. The ventilation device 8 is responsible for the sheathed housing pump that has been fully installed in the equipment being able to be filled and for the air being able to escape through the ventilation device 8.

[0032] Figure 2 A schematic view of the ventilation device 8 is shown. The ventilation device 8 is integrated into each stage housing 5. The stage housing 5 separates the internal pressure space 9 from the external pressure space 10. The internal pressure space 9 is arranged around the impeller 4. The external pressure space 10 is located between the stage housing 5 and the sheathed housing 1 and is in pressure-technical connection with the interior of the pressure connection 7.

[0033] According to the present invention, the ventilation device 8 includes an opening 11 which is introduced into the stage housing 5 as a hole. In addition, the ventilation device 8 includes a receiving portion 12. The receiving portion 12 is a notch which, in this embodiment, is introduced into the outer circumferential surface of the stage housing 5 in the form of a circular notch as a hole. The notch forms a region of the opening 11 with an enlarged inner diameter. An element 13 is arranged in the receiving portion 12. The element 13 is a plate-shaped element in this embodiment and is configured to be cylindrical. The diameter of the element 13 is smaller than the diameter of the receiving portion 12, so that the element 13 is arranged in the receiving portion 12 in a manner that can be displaced in the radial direction.

[0034] In Figure 2 the solution presented, the ventilation device 8 includes a stop portion 14 which prevents the element 13 from being taken out of the receiving portion 12. The stop portion 14 can be a protrusion extending into the receiving portion 12 or a snap ring inserted into an annular groove provided in the receiving portion 12.

[0035] If the sheath housing pump is filled with the operating medium for a pressure test, the element 13 is pushed upward or radially outward and opens a free cross-section for air to escape. The stop portion 14 serves as a protective element and prevents the element 13 from being taken out of the receiving portion 12, for example, due to vibrations during operation or by the air flow during ventilation. During the filling process, the rising operating medium in the internal pressure space 9 lifts the element 13 by the hydrostatic head until all the air escapes. The fully ventilated system is now put into operation. During operation, a higher operating pressure appears in the external pressure space 10 relative to the internal pressure space 9. Due to this pressure difference, the element is pushed to the bottom of the receiving portion 12 of the stage housing 5. The element 13 is implemented as a sealing element and prevents the operating medium from flowing back from the external pressure space 10 into the internal pressure space 9. For this purpose, the contact surface between the bottom of the receiving portion 12 and the element 3 is implemented such that a reliable seal is ensured.

[0036] The ventilation device according to the present invention is fully capable of coping without elastic elements. By dispensing with elastic elements, the ventilation device according to the present invention proves to be wear-free and low-maintenance. The ventilation device is outstanding for its reliable operating mode and high service life. In addition to the operating medium, no additional energy source is required. Therefore, the ventilation device according to the present invention is independent of external energy sources and does not additionally increase the operating costs.

Claims

1. A centrifugal pump, having an impeller (4), a pressure connection (7), a shroud casing (1) and at least one stage casing (5), the at least one stage casing (5) separating an internal pressure space (9) from an external pressure space (10), wherein, The internal pressure space (9) is arranged around the impeller (4), and the external pressure space (10) is located between the stage shroud (5) and the sheath shroud (1) and is in pressure-technical connection with the interior of the pressure connection (7). At least one ventilation device (8) is arranged in the stage shroud (5). The ventilation device (8) includes an opening (11) and a receiving portion (12). The opening (11) is introduced as a hole into the stage shroud (5) and connects the internal pressure space (9) with the external pressure space (10). The receiving portion (12) is a notch, and the notch is introduced as a circular recess in the form of a hole into the outer circumferential surface of the stage shroud (5). It is characterized in that the receiving portion (12) forms a region of the opening (11) with an enlarged inner diameter, and the ventilation device (8) includes a plate-shaped element (13) for promoting the opening or blocking of the medium exchange between the internal pressure space (9) and the external pressure space (10), and it is arranged in the receiving portion (12) in a radially displaceable manner. A free cross-section for medium exchange exists between the wall of the receiving portion (12) and the plate-shaped element (13). The ventilation device (8) is arranged in the upper region of the stage shroud (5).

2. The centrifugal pump according to claim 1, wherein, The element (13) is arranged in a guide portion.

3. The centrifugal pump according to claim 1, wherein The opening (11) is introduced into the bottom of the receiving portion (12).

4. The centrifugal pump according to any one of claims 1 to 3, characterized in that, The element (13) is configured to be larger than the opening (11).

5. The centrifugal pump according to any one of claims 1 to 3, characterized in that, The ventilation device (8) has a stop portion (14) for the element (13).

6. The centrifugal pump according to any one of claims 1 to 3, characterized in that, The ventilation device (8) is arranged at the 12 o'clock position.

7. A method for performing a pressure test in a centrifugal pump according to any one of claims 1 - 6, having the following steps: - Install the centrifugal pump in a device. - Fill the centrifugal pump with an operating medium. - Allow air to escape from the internal pressure space (9) through the stage shroud (5) into the external pressure space (10).

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