Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
  • F04D15/00—Control, e.g. regulation, of pumps, pumping installations or systems
  • F04D15/02—Stopping of pumps, or operating valves, on occurrence of unwanted conditions
  • F04D15/0245—Stopping of pumps, or operating valves, on occurrence of unwanted conditions responsive to a condition of the pump
  • F04D15/0263—Stopping of pumps, or operating valves, on occurrence of unwanted conditions responsive to a condition of the pump the condition being temperature, ingress of humidity or leakage
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
  • F04D29/00—Details, component parts, or accessories
  • F04D29/08—Sealings
  • F04D29/10—Shaft sealings
  • F04D29/12—Shaft sealings using sealing-rings
  • F04D29/126—Shaft sealings using sealing-rings especially adapted for liquid pumps
  • F04D29/128—Shaft sealings using sealing-rings especially adapted for liquid pumps with special means for adducting cooling or sealing fluid
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2260/00—Function
  • F05D2260/60—Fluid transfer
  • F05D2260/602—Drainage
  • F05D2260/6022—Drainage of leakage having past a seal

Definitions

• the invention relates to a centrifugal pump, in particular a multi-stage centrifugal pump, which is provided for driving by means of a motor designed as a dry rotor, which is connected via a coupling with the pump driving shaft.
• Centrifugal pumps have at least one impeller which is rotatably mounted on a shaft which is sealed by means of at least one seal to a surrounding housing.
• the drive shaft emerging from the pump housing on one side is sealed by a mechanical seal which is intended to prevent leakage of the liquid inside the housing along the outside of the shaft.
• the pressure in this area of the housing is comparatively high, so that a complete tightness can only be achieved with great difficulty.
• the higher the contact pressure of the seal is applied the less liquid can escape through the sealing gap.
• the sealing gap becomes smaller, the frictional forces that have to be additionally applied by the drive, which are converted exclusively into heat and which worsen the efficiency, grow.
• the invention has the object, a centrifugal pump in such a way that the liquid passage can be detected in the shaft seal.
• a centrifugal pump having the features mentioned above in that a container open towards the seal is provided, which is designed and arranged such that it passes the fluid passing through the seal, in particular through the seal trailing liquid traps and the means are further provided which detect the liquid in the container or from the container, d. H. Means that detect the liquid level within the container or the effluent from the container.
• An open towards the seal container in the context of the invention is a container which is open to the sealing gap between the seal and the shaft, d. H. that it can absorb liquid emerging along the shaft or on the seal.
• the centrifugal pump according to the invention which has at least one impeller, which is arranged rotationally fixed on a shaft which is sealed off by means of at least one seal to a surrounding housing, has a container arranged in the housing and at least open to the seal for capturing by Seal passing fluid and is equipped with means for detecting liquid in or out of the container.
• the basic idea of the present invention is therefore to detect and monitor the passage of fluid through the seal, which is a prerequisite for safe operation, in which the passage of a ner certain amount of liquid is tolerated. This operation makes it possible to significantly reduce the frictional forces in the region of the seal and thus to improve the efficiency of the unit and continue to increase the service life of the seal.
• the inventive arrangement controls the fluid passing through the seal, in particular in liquid form, and thus monitors the seal during its operation.
• the arrangement according to the invention therefore not only has the aforementioned advantages in operation, but also provides a reliable function monitoring of the device, so it detects early when the seal or the seals wear before they fail completely.
• the arrangement according to the invention can thus be used not only in pumps in which a liquid passage through the seal is deliberately accepted, but also in those pumps in which this is not desired. So not only mechanical seals but also any other seals, such as O-rings can be monitored for their tightness out.
• the container is annular, the shaft formed surrounding.
• the fluid emerging from the pump housing at the periphery of the shaft or at the seal can be collected in the annular container.
• the liquid is detected by means of electrical contacts, so there are at least two mutually electrically insulated contacts provided, which are electrically connected by the liquid become.
• two states are to be detected electronically, namely the state in which the contacts are connected by gas, typically the ambient air, and the state in which the contacts are connected by liquid.
• the ohmic resistances of these two states are sufficiently different, detection in the non-hazardous low voltage range is readily possible, the evaluation electronics can largely be done by digital logic devices.
• three or more contacts can be arranged at different heights within the container so that the liquid level within the container can be detected in stages.
• the container has a drain opening, through which the liquid in the container is selectively discharged preferably to the outside.
• a discharge of small amounts to the outside is usually unproblematic and tolerable.
• a sensor for detecting the flow in particular a sensor for detecting drops
• a sensor for detecting drops is arranged in or at the drain opening, since the quantity of liquid flowing out can be detected in a simple and effective manner.
• a drop sensor is sufficient, since in a preferred sealing gap dimensioning, a liquid outlet is tolerated which is at a few drops per minute or per hour.
• such a sensor can be formed by means of two mutually electrically isolated contacts whose spacing is dimensioned so that they are electrically connected by a passing liquid drop.
• a resistance measurement as already described in the introduction of the level detection.
• the senor by two mutually electrically insulated but electrically conductive, preferably metallic tubes which are coaxial with each other and in which the inner tube ends at a distance from the end of the outer tube.
• These tubes are tightly incorporated in the drainage opening of the container and preferably arranged approximately at an angle of 45 ° to the vertical. They typically consist of stainless steel and are electrically connected to the evaluation electronics.
• the distance of the tubes is dimensioned so that the passage of the drop, a short circuit between the two tubes or an electrical connection through the drop, so the liquid is produced, which differs from the normal air connection resistance and thus is detectable.
• this sensor not only the dry state and a continuous drop can be detected, but also a continuous flow, ie when a trickle forms, which short-circuits the contacts permanently.
• the sensitivity of the sensor can be adjusted. If the distance is greater than that of a drop, then the sensor is only suitable for detecting rinses which permanently short the contacts.
• the centrifugal pump or the centrifugal pump assembly formed therewith is particularly advantageously one in which the shaft is arranged vertically and the pump is sealed at the top with a mechanical seal in which the container is arranged between the pump and the motor and the pump Container bottom has a drain opening, followed by the sensor formed by tubes, the other end opens into the open or into a drain line.
• a design is typically provided in multi-stage centrifugal pumps, such as those offered by Grundfos in the CR series.
• the container which catches the fluid emerging through the seal and the means for detecting the liquid in or out of the container can be realized in particular in the above-described multi-stage pump with a few inexpensive to produce components, the arrangement in an already existing space is not a problem.
• Such an arrangement is advantageous, in particular, for the use of mechanical seals, since this allows a seal dimensioning which allows a targeted low leakage in order to be able to improve the friction within the seal and the service life of the seal.
• the arrangement is not limited to mechanical seals and can be used in the same way for monitoring O-rings or other seals.
• the sensor according to the invention has two mutually electrically insulating and conductive tubes which lie in one another and from which the inner tube ends at a distance from the end of the outer tube.
• Such a sensor can be provided not only on the above-described container but optionally also on other housing parts to detect leakage and not only qualitatively but also quantitatively.
• the sensor is inexpensive to manufacture, robust and long-term stable.
• the evaluation based on the changing resistance when overflowing a drop is technically less complex and easy to implement electronically.
• FIG. 1 in a simplified perspective view of a multi-level
• the centrifugal pump 1 has a multistage centrifugal pump 1 whose shaft, which is not visible in the drawings, is arranged perpendicularly and exits at the top of the pump housing 2, where it is connected to the shaft of an electric motor 4 via a coupling 3, which is flanged on a motor chair 5 at the top of the pump housing 2.
• the electric motor 4 is a dry runner.
• the pump housing 2 has a base-side foot 6 with two inline connection flanges 7 and 8, one of which the Suction port and the other forms the pressure port of the pump 1.
• the individual pump stages are arranged within a stainless steel jacket, which extends between the foot 6 and an upper housing part 9, which also forms the motor chair 5.
• the housing parts 6 and 9 are clamped together in the usual way via tie rods 10.
• the mechanical seals are arranged in a cartridge-like housing 1 1, the so-called slide ring cartridge and correspond to the example installed in the CR series Grundfos conventional seal cartridges, with which the pump shaft is sealed against the pump housing 2.
• a container 12 which is designed as an annular, upwardly open and lockable by a cover 13 housing.
• the container 12 has on its underside two concentric arranged in different planes grooves 14 and 15, which are directed downwards and are provided for receiving in each case an O-ring.
• the inner tube 21 and the outer tube 22 form electrical contacts, which are connected via an electrical cable 23 to a arranged in an electronics housing 24 evaluation electronics.
• the outer tube 22 projects obliquely downwards and outwards, so that liquid emerging therefrom passes into the side region of the pump housing.
• the electronics housing 24 is rotationally offset from the sensor 20 and mounted below the motor chair 5 within the upper housing part 9. From the electronics housing 24 lead from electrical connections, not shown, to the control electronics of the engine, which is arranged in the illustrated embodiment in a terminal box 25 which receives an electronic speed controller of the engine and the control electronics for it.
• the evaluation electronics so that when using this arrangement, it is firstly possible to reliably detect whether the shaft seal is leak-tight or allows fluid to pass through. If it lets fluid through it can be further detected, how much liquid this is. Small amounts will only be single drops, and the approximate amount can be determined by the time interval between the overflowing drops.
• the electrical connection between the inner tube 21 and the outer tube 22 is permanently short-circuited by liquid, which is also registrable.
• the sensor can be refined, so that at least a coarse flow rate can be determined in a trickle formation. This is done by further increasing the distance between the inner and outer tubes, the larger they are, the larger the amount of water passing through, which causes a permanent short between the tubes, must be. In this way, the sensor can be refined in terms of its quantitative measurement properties.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Structures Of Non-Positive Displacement Pumps (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=48468258

Family Applications (1)

Country Status (2)

Cited By (2)

Families Citing this family (1)

Citations (10)

• 2012
  • 2012-05-31 EP EP12170230.2A patent/EP2669525B1/fr active Active
• 2013
  • 2013-05-08 WO PCT/EP2013/059581 patent/WO2013178444A1/fr not_active Ceased

Patent Citations (10)

Also Published As

Similar Documents

Legal Events