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EP-4001658-B1 - ROTARY PUMP FOR CONVEYING A FLUID

EP4001658B1EP 4001658 B1EP4001658 B1EP 4001658B1EP-4001658-B1

Inventors

  • WELSCHINGER, THOMAS
  • Luis, Antonio

Dates

Publication Date
20260506
Application Date
20211021

Claims (14)

  1. A rotary pump for conveying a fluid, comprising a pump housing (2) with an inlet (3) for receiving the fluid having a suction pressure (SP) , and an outlet (4) for discharging the fluid having a discharge pressure (DP), further comprising an impeller (5) for conveying the fluid from the inlet (3) to the outlet (4) and for pressurizing the fluid from the suction pressure (SP) such, that the fluid is discharged with the discharge pressure (DP), and a shaft (6) for rotating the impeller (5) about an axial direction (A), wherein the impeller (5) is configured as an overhung impeller (5) and the pump is configured as a single stage pump having exactly one impeller (5), wherein a pressure chamber (15) is arranged upstream of the impeller (5) between the inlet (3) and the impeller (5), wherein the pressure chamber (15) is delimited by a stationary part (18) and a rotary part (16), wherein the stationary part (18) is configured to be stationary with respect to the pump housing (2), wherein the rotary part (16) is fixedly connected to the shaft (6), wherein a relief passage (19) extends from the pressure chamber (15) to a low pressure location (17), and wherein at least one balance line (30) is provided, which is configured for supplying the fluid having the discharge pressure (DP) to the pressure chamber (15), characterized in that the stationary part (18) and the rotary part (16) are configured to overlap with respect to the axial direction (A), such that the relief passage (19) is provided between the rotary part (16) and the stationary part (18).
  2. A rotary pump in accordance with claim 1, wherein the low pressure location (17) is connected to a suction pressure line (25), which is configured to adjust the pressure at the low pressure location (17) to the suction pressure (SP).
  3. A rotary pump in accordance with anyone of the preceding claims, wherein the impeller (5) is configured as an axial impeller or as a semi-axial impeller or as a helico-axial impeller.
  4. A rotary pump in accordance with anyone of the preceding claims, comprising a discharge chamber (9) for receiving the fluid from the impeller (5), wherein the discharge chamber (9) is in fluid communication with the outlet (4), and wherein the balance line (30) is connected to the discharge chamber (9).
  5. A rotary pump in accordance with anyone of the preceding claims, comprising a diffuser (8) for receiving the fluid from the impeller (5).
  6. A rotary pump in accordance with anyone of the preceding claims, wherein the stationary part (18) comprises a flow guiding element (10) widening with respect to the radial direction, when viewed from the inlet (3) towards the impeller (5), wherein the flow guiding element (10) is configured to guide the fluid from the inlet (3) to a annular suction chamber (11) in front of the impeller (5).
  7. A rotary pump in accordance with claim 6, comprising a plurality of ribs (12) for fixing the flow guiding element (10) to the pump housing (2), wherein each rib (12) extends from the flow guiding element (10) in radial direction to the pump housing (2).
  8. A rotary pump in accordance with claim 7, wherein the at least one balance line (30) is arranged inside one of the ribs (12).
  9. A rotary pump in accordance with anyone of claims 7-8, comprising a plurality of balance lines (30), wherein each balance line (30) is arranged inside one of the ribs (12).
  10. A rotary pump in accordance with anyone of the preceding claims, wherein the rotary part (16) is configured as a separate component, which is fixed to the shaft (6) and arranged between the impeller (5) and an end (61) of the shaft (6).
  11. A rotary pump in accordance with anyone of claims 1-9 wherein the rotary part (16) is formed integrally with the impeller (5).
  12. A rotary pump in accordance anyone of the preceding claims, wherein the impeller (5) comprises a plurality of relief bores (21), with each relief bore (21) extending completely through the impeller (5) with respect to the axial direction (A).
  13. A rotary pump in accordance with claim 12, wherein each relief bore (21) discharges into the low pressure location (17).
  14. A rotary pump in accordance with anyone of the preceding claims, configured for conveying a multiphase process fluid.

Description

The invention relates to a rotary pump for conveying a fluid in accordance with the preamble of the independent patent claim. Rotary pumps for conveying a fluid, for example a liquid such as water, are used in many different industries. Examples are the oil and gas industry, the hydrocarbon processing industry, the power generation industry, the chemical industry, the water and wastewater industry or the pulp and paper industry. Rotary pumps have a hydraulic unit comprising at least one impeller and in many cases a volute or a diffuser. A shaft is provided for rotating the impeller(s). The at least one impeller may be configured for example as a radial impeller or as an axial or semi-axial impeller or as a helico-axial impeller. A specific type of a rotary pump is a rotary pump with overhung impeller(s). In an overhung impeller pump the impeller(s) is/are mounted on or near the end of the shaft that rotates the impeller meaning that the shaft overhangs its bearings. A rotary pump may be designed as a single stage pump having only one impeller mounted to the shaft or as a multistage pump comprising a plurality of impellers, wherein the impellers are arranged one after another on the shaft. In many applications overhung impeller pumps are designed as single stage pumps. However, in other applications the overhung impeller pump may be configured as a two stage pump with two impellers fixed at or near one end of the shaft. Furthermore, multiphase pumps are known configured as single stage or as multistage pumps and both in a overhung design and a between-bearing design. Multiphase pumps are used in applications, where it is necessary to convey a multiphase process fluid which comprises a mixture of a plurality of phases, for example a liquid phase and a gaseous phase. An important example is the oil and gas processing industry where multiphase pumps are used for conveying hydrocarbon fluids, for example for extracting the crude oil from the oil field or for transportation of the oil/gas through pipelines or within refineries. Fossil fuels are usually not present in pure form in oil fields or gas fields, but as a multiphase mixture which contains liquid components, gas components and possibly also solid components. This multiphase mixture of e.g. crude oil, natural gas, chemicals, seawater and sand has to be pumped from the oil field or gas field. For such a conveying of fossil fuels, multiphase pumps are used which are able to pump a liquid-gas mixture which may also contain solid components, sand for example. In particular in overhung impeller pumps there is often a high axial thrust acting on the shaft which needs to be supported by an axial bearing, which is also referred to as a thrust bearing. This is specifically true for pumps having an axial or a semi-axial or a helico-axial impeller. The high axial load requires strong and large axial bearing, which are expensive. In some applications the axial thrust acting on the shaft is as large that it is no longer possible to use antifriction bearings as axial bearings. Then, more complicated and more expensive axial or thrust bearings are required, for example tilting pad bearings. These bearings require an additional lubrication system for the bearing, which increases the costs and the complexity of the pump. Rotary pumps belonging to the prior art are known from documents RU 2 027 073 C1, US 2 681 010 A and CN 205 559 355 U. It is therefore an object of the invention to propose a rotary pump for conveying a fluid, the pump having an overhung impeller, wherein the axial thrust that has to be carried by the axial bearing (thrust bearing) is considerably reduced. The subject matter of the invention satisfying this object is characterized by the features of the independent claim. Thus, according to the invention, a rotary pump for conveying a fluid is proposed, comprising a pump housing with an inlet for receiving the fluid having a suction pressure, and an outlet for discharging the fluid having a discharge pressure, further comprising an impeller for conveying the fluid from the inlet to the outlet and for pressurizing the fluid from the suction pressure such, that the fluid is discharged with the discharge pressure, and a shaft for rotating the impeller about an axial direction, wherein the impeller is configured as an overhung impeller, wherein a pressure chamber is arranged upstream of the impeller between the inlet and the impeller, wherein the pressure chamber is delimited by a stationary part and a rotary part, wherein the stationary part is configured to be stationary with respect to the pump housing, wherein the rotary part is fixedly connected to the shaft, wherein the stationary part and the rotary part are configured to overlap with respect to the axial direction, such that a relief passage is provided between the rotary part and the stationary part, wherein the relief passage extends from the pressure chamber to a low pressure location, and wherein a