Classifications

• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21C—NUCLEAR REACTORS
  • G21C15/00—Cooling arrangements within the pressure vessel containing the core; Selection of specific coolants
  • G21C15/24—Promoting flow of the coolant
  • G21C15/243—Promoting flow of the coolant for liquids
• • 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
  • F04D29/04—Shafts or bearings, or assemblies thereof
  • F04D29/046—Bearings
  • F04D29/047—Bearings hydrostatic; hydrodynamic
• • 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
  • F04D29/58—Cooling; Heating; Diminishing heat transfer
  • F04D29/586—Cooling; Heating; Diminishing heat transfer specially adapted for liquid pumps
  • F04D29/588—Cooling; Heating; Diminishing heat transfer specially adapted for liquid pumps cooling or heating the machine
• • 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
  • F04D29/58—Cooling; Heating; Diminishing heat transfer
  • F04D29/586—Cooling; Heating; Diminishing heat transfer specially adapted for liquid pumps
  • F04D29/5893—Cooling; Heating; Diminishing heat transfer specially adapted for liquid pumps heat insulation or conduction
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
  • F04D7/00—Pumps adapted for handling specific fluids, e.g. by selection of specific materials for pumps or pump parts
  • F04D7/02—Pumps adapted for handling specific fluids, e.g. by selection of specific materials for pumps or pump parts of centrifugal type
  • F04D7/06—Pumps adapted for handling specific fluids, e.g. by selection of specific materials for pumps or pump parts of centrifugal type the fluids being hot or corrosive, e.g. liquid metals
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
  • F04D7/00—Pumps adapted for handling specific fluids, e.g. by selection of specific materials for pumps or pump parts
  • F04D7/02—Pumps adapted for handling specific fluids, e.g. by selection of specific materials for pumps or pump parts of centrifugal type
  • F04D7/08—Pumps adapted for handling specific fluids, e.g. by selection of specific materials for pumps or pump parts of centrifugal type the fluids being radioactive
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E30/00—Energy generation of nuclear origin
  • Y02E30/30—Nuclear fission reactors

Definitions

• the invention generally relates to nuclear reactor pumps, in particular primary pumps, intended to set in motion the primary fluid of the reactor.
• the invention relates in a first aspect to a pump for a fluid of a nuclear reactor, the pump comprising:
• a pump shaft movable in rotation relative to the fixed structure about an axis of rotation
• a structure for guiding the fluid set in motion by the pump wheel fixed to the fixed structure, the guiding structure comprising a tubular part placed around the pump shaft, the guiding structure delimiting internally a circulation chamber of the fluid in which is placed the pump wheel;
• thermal barrier interposed radially between the tubular part and the pump shaft, the thermal barrier comprising a thermal barrier body and a thermal barrier cover interposed axially along the pump shaft between the thermal barrier body and the thermal barrier; pump wheel, the thermal barrier comprising a heat exchanger placed in a housing delimited by the thermal barrier cover;
• a heat shield interposed radially between the thermal barrier and the tubular portion of the guide structure.
• Such a pump typically comprises a diffuser defining the tubular portion. It is possible to fix the heat shield against the tubular part. There is then a gap between the heat shield and the thermal barrier body.
• Such pumps generally include a dynamic sealing device, with an injection of a barrier fluid along the pump shaft.
• This barrier fluid flows at the sealing device as well as along the pump shaft, into the housing receiving the heat exchanger, and into the chamber above the pump impeller. finally in the primary fluid.
• the high temperature primary fluid rises from the circulation chamber along the shaft in the housing receiving the heat exchanger. It flows to the dynamic sealing device. In parallel with this main flow, high temperature primary fluid recirculations occur in the gap between the heat shield and the thermal barrier body.
• the heat of the primary fluid diffuses through the thermal barrier body to the seals around the pump shaft.
• the thermal power of the primary fluid rising through the exchanger is partly extracted by it.
• the recirculations of primary fluid between the screen and the thermal barrier uncooled by the heat exchanger provide a thermal power directly in the upper part of the thermal barrier body and by diffusion to the cavity upstream of the sealing device.
• the dynamic sealing device therefore has a higher temperature than during operation of the pump with injection.
• the temperature of the joints must remain permanently below 90 ° C.
• the heat flux diffused through the thermal barrier body is a difficulty in obtaining this result.
• the invention aims to provide a pump in which it is easier to maintain the seals of the pump shaft below their maximum allowed temperature.
• the invention relates to a pump of the aforementioned type, characterized in that the heat shield comprises a top heat shield interposed radially between the thermal barrier body and the tubular portion and a lower heat shield interposed radially between the lid thermal barrier and the tubular portion, the upper heat shield being pressed against the thermal barrier body and the lower heat shield being pressed against the tubular portion.
• the pump may further have one or more of the following features, considered individually or in any technically feasible combination:
• the upper heat shield is rigidly fixed to the thermal barrier body;
• the upper heat shield has a lower axial end towards the lower heat shield, rigidly fixed to the tubular portion by a sealed peripheral weld;
• the upper heat shield is separated from the tubular portion by an upper gap, a cavity between the upper heat shield and the lower heat shield fluidly connecting the upper gap to the housing;
• the thermal barrier comprises at least one pressure drop or sealing device placed in the upper gap or in the cavity;
• the lower heat shield is rigidly attached to the tubular portion
• the lower heat shield comprises an extension engaged in the upper gap and rigidly fixed to the tubular portion;
• the lower heat shield is separated from the thermal barrier cover by a lower gap fluidly communicating with the housing;
• the lower and / or upper heat shield comprises a box and a plurality of plates arranged parallel to each other in the box, the plates being separated from each other by liquid strips of thickness less than 1.5 mm ;
• each plate has a thickness of less than 0.8 mm
• the pump further comprising a device for injecting a barrier fluid comprising a circuit for injecting a barrier fluid into the chamber, the flushing fluid flowing along the pump shaft along a path from the chamber to the housing, and from the housing to the fluid circulation chamber;
• the guide structure comprises a volute internally defining the flow chamber, and a diffuser disposed within the volute and defining the tubular portion;
• the upper and lower heat shields are two structures independent of each other;
• the thermal barrier body and the thermal barrier cover are two separate structures
• the tubular portion is delimited radially inwardly by a substantially cylindrical surface, coaxial with the axis of rotation, the thermal barrier body being delimited radially outwardly by a substantially cylindrical surface, coaxial with the axis of rotation the upper heat shield being placed between the surface of the tubular portion and the surface of the thermal barrier body.
• the invention relates to a nuclear reactor comprising a vessel in which are placed nuclear fuel assemblies, and a primary circuit, the vessel having a primary fluid inlet and a primary fluid outlet, the primary circuit connecting fluidically the primary fluid outlet to the primary fluid inlet and having a pump having the above characteristics arranged in order to ensure the circulation of the primary fluid from the primary fluid outlet of the vessel to the primary fluid inlet.
• FIG. 1 is a partial view of a nuclear reactor primary pump according to the invention
• FIG. 2 is an enlarged view of the thermal barrier and the heat shield of the pump of FIG. 1;
• the pump 1 shown in FIG. 1 is intended to set in motion a fluid of a nuclear reactor.
• this pump is a primary pump, intended to set in motion the primary fluid of the nuclear reactor.
• the reactor comprises a vessel containing the nuclear fuel assemblies, and a steam generator.
• the steam generator has a primary side and a secondary side, in which the primary fluid and the secondary fluid circulate respectively, the primary fluid yielding part of its heat energy to the secondary fluid in the steam generator.
• the reactor includes a primary circuit connecting a primary fluid outlet of the vessel to an inlet on the primary side of the steam generator, and connecting an outlet on the primary side of the steam generator to a primary fluid inlet of the vessel.
• the pump is inserted in the primary circuit and circulates the primary fluid in the primary circuit.
• the pump is a secondary pump, interposed on the secondary circuit of the nuclear reactor. It ensures the circulation of the secondary fluid between the secondary side of the steam generator and a steam turbine.
• the primary circuit directly connects the reactor vessel to the steam turbine.
• the pump is interposed on the primary circuit between the turbine and the primary fluid inlet of the tank.
• the pump is used in other circuits of the nuclear reactor, to set in motion any type of fluid.
• the pump comprises a fixed structure 3 intended to be rigidly connected to the civil engineering of the reactor by different devices not shown in FIG.
• the fixed structure 3 is only partially shown in FIG. It comprises in particular a main flange 5 and a motor support 7 These parts are linked together by any appropriate means.
• the pump 1 further comprises a pump shaft 9, rotatable relative to the fixed structure 3 about an axis of rotation X.
• the axis of rotation X is typically substantially vertical.
• the pump 1 typically comprises an engine (not shown) housed above the engine support 7.
• the motor drives the pump shaft 9 in rotation.
• the pump 1 further comprises a pump wheel 1 1, rigidly fixed to the pump shaft 9.
• the pump wheel 1 1 is rigidly fixed to a lower end 13 of the pump shaft 9.
• the pump 1 comprises a guide structure 15 of the fluid set in motion by the pump wheel 1 1.
• the guide structure 15 delimits internally a fluid circulation chamber 17, in which the pump wheel 1 1 is placed.
• the guide structure 15 has a tubular portion 19 placed around the pump shaft.
• the tubular portion 19 is coaxial with the X axis.
• the guide structure 15 comprises a volute 21 which internally delimits the circulation chamber 17.
• the volute 21 is rigidly fixed to the fixed structure 3, and more particularly to the main flange 5.
• the pump 1 is of helico-centrifugal type, the volute 21 having a fluid inlet 23 located below the pump wheel January 1, in the extension thereof along the axis X.
• the output of fluid not shown is formed in the volute 21, in a radial direction relative to the axis X.
• the guide structure 15 comprises a diffuser 25 disposed inside the volute 21.
• the diffuser 25 defines the tubular portion 19.
• the diffuser 25 is also rigidly fixed to the fixed structure 3, by any appropriate means.
• the diffuser 25 typically comprises a fluid guide portion 27 extending the tubular portion 19 downwardly.
• the guide portion 27 is disposed in the extension of the pump wheel January 1 and has internal passages 29 guiding the fluid discharged by the pump wheel to the chamber 17.
• the volute 21 has an upper portion 31 forming a flange 31, rigidly fixed to the main flange 5.
• the tubular portion 19 comprises an upper section 33 forming a flange, placed inside the flange 31.
• the tubular portion 19 also includes an intermediate portion 35, connecting the upper portion 33 to the lower guide portion 27.
• the tubular portion 19 internally defines a conduit for the passage of the pump shaft 9, and for housing various equipment which will be described below.
• the pump 1 further comprises a thermal barrier 37 interposed radially between the tubular portion 19 and the pump shaft 9.
• This thermal barrier 37 comprises a thermal barrier body 39 and a thermal barrier cover 41.
• the thermal barrier body 39 is tubular, and surrounds the pump shaft 9.
• the cover 41 is interposed axially along the pump shaft 9 between the thermal barrier body 39 and the pump wheel 11.
• the cover 41 and the thermal barrier body 39 are two separate structures.
• the cover 41 is attached to the thermal barrier body 39 at its lower face. It is located substantially at the level of the upper 33 and intermediate 35 sections.
• the tubular portion 19 delimits with the pump shaft 9 an annular volume in which the thermal barrier 37 is housed.
• This annular volume is closed axially towards the pump wheel 11 by a wall in the form of a ring 43, part of the diffuser 25. It is delimited radially outwards by the sections 33 and 35. It is delimited radially inwards by the pump shaft 9.
• the thermal barrier 37 furthermore comprises a heat exchanger 45 placed in a housing 47 delimited by the thermal barrier cover 41.
• the housing 47 is cylindrical and completely surrounds the pump shaft 9. It is closed axially towards the pump wheel 1 1 by an annular wall 49 of the thermal barrier cover.
• the housing 47 is closed radially outwardly by a cylindrical wall 51 of the thermal barrier cover.
• the housing 47 is closed axially opposite the pump wheel by the thermal barrier body 39.
• the housing 47 is closed radially inwardly by the labyrinth ring 53, integral with the thermal barrier body.
• the thermal barrier 37 further comprises a supply 55 of cooling fluid. It is connected to the heat exchanger 45 and ensures a circulation of the cooling fluid inside thereof.
• a heat shield 57 is interposed radially between the thermal barrier 37 and the tubular portion 19. This heat shield 57 will be described in detail below.
• the pump 1 typically comprises one or more shaft seals, placed around the pump shaft 9.
• the pump comprises three shaft seals 59, 61, 63, placed axially behind each other. These seals are axially separated from the pump impeller 1 1 by a bearing 65 as well as by the thermal barrier 37.
• the heat exchanger integrated with the latter makes it possible to thermally protect the shaft seals, in the event of loss of feed. dam fluid.
• the bearing 65 ensures the rotational guidance of the pump shaft 9.
• the bearing 65 is housed in a chamber 66 delimited radially between the thermal barrier body 39 and the pump shaft 9. It is rigidly fixed in the lower part to the thermal barrier body 39.
• the chamber 66 is located axially along the pump shaft 9 between the shaft seal 59 and the thermal barrier housing 47.
• the chamber 66 is formed radially between the thermal barrier body 39 and the pump shaft 9.
• the pump 1 further comprises a device 67 for injecting a barrier fluid.
• the role of the barrier fluid is to avoid a rise of the fluid through the entire pump to the shaft seal device 59, 61, 63.
• the device 67 comprises a circuit 69 designed to inject a cold barrier fluid into the chamber 66.
• the cold barrier fluid flows through the shaft seals 59, 61, 63 as well as towards the chamber 17 of the volute 21.
• the flow of the barrier fluid follows the path 71 along the pump shaft 9 from the chamber 66 to the housing 47, then from the housing 47 to the circulation chamber 17.
• the heat shield 57 comprises an upper thermal shield 73 interposed radially between the thermal barrier body 39 and the tubular portion 19, and a lower heat shield 75 interposed radially between the thermal barrier cover 41 and the tubular portion 19.
• the upper and lower heat shields are two structures independent of each other, that is to say without rigid attachment to one another.
• the upper heat shield 73 is cylindrical and coaxial with the X axis.
• the upper heat shield 73 is placed around the thermal barrier body 19.
• the upper heat shield 73 is pressed against the thermal barrier body 39.
• plated against is meant here that the upper heat shield 73 is in contact with or separated from the thermal barrier body by a gap of very small thickness. This thickness is typically less than 2 mm, preferably less than 1 mm.
• This interstice 76 has a thickness greater than 3 mm, preferably greater than 5 mm.
• the thermal barrier body 39 comprises a tubular portion 78 radially outwardly delimiting the chamber 66. It further comprises a flange 79 protruding radially outwardly from the upper end of the portion 79. The flange 79 is pinched axially between the main flange 5 and the upper section 33.
• the thermal barrier body 39 further includes a re-entrant portion 80, extending the lower end of the tubular portion 79 radially inwardly and axially toward the pump wheel.
• the reentrant portion 80 separates the chamber 66 from the housing 47.
• the upper heat shield 73 is rigidly attached to the thermal barrier body
• the upper heat shield 73 has a lower axial end 81 facing the lower heat shield 75, attached to the thermal barrier body 19.
• the lower axial end 81 is fixed to the thermal barrier body 39 by a sealed circumferential weld 82.
• This weld 82 extends over the entire periphery of the thermal barrier body 39.
• the gap between the thermal barrier body 39 and the upper screen 73 is thus sealed by the weld 82 in the lower part, which prevents any circulation of liquid between the upper heat shield 73 and the thermal barrier body 39.
• the tubular portion 19 is delimited radially inwardly by a substantially cylindrical surface 83, coaxial with the axis X.
• the thermal barrier body 39 and more specifically the cylindrical portion 79 of this body, is delimited radially outwards. by a substantially cylindrical surface 84, coaxial with the X axis.
• the upper heat shield 73 is placed between the surfaces 83 and 84.
• the upper heat shield 73 is delimited radially inwardly by an inner surface 85.
• This surface 85 is typically substantially cylindrical, and coaxial with the X axis.
• the inner surface 85 is pressed against the surface 84 of the thermal barrier body 39.
• an axially lower zone of the surface 85 is directly in contact with the zone facing the surface 84, or is separated from the zone facing a gap of thickness less than 1 mm. , for example of thickness 0.5 mm.
• the remainder of the surface 85 is separated from the surface 84 by a gap of slightly greater thickness, for example between 0.5 and 1.5 mm.
• the lower heat shield 75 is pressed against the tubular portion 19. It is rigidly fixed by welding to the radially inner surface 83. It is pressed against the intermediate portion 35 of the tubular portion 19. It is cylindrical and coaxial with the X axis.
• the lower heat shield 75 is separated from the thermal barrier cover 41 by a lower gap 86, fluidly communicating with the housing 47. As shown in the figures, the lower heat shield 75 is inserted between the wall 51 of the thermal barrier cover and the tubular portion 19. The wall 51 is delimited radially outwardly by a substantially cylindrical surface 87. The lower gap 86 is delimited radially inwards by the surface 87 and radially outwardly by the lower heat shield 75.
• this cavity 88 there is a cavity 88 between the upper heat shield and the lower heat shield.
• the volume of this cavity 88 depends on the connection between the thermal barrier cover 39 and the thermal barrier body, the design of the lower and upper heat shields, the fixing thereof and the respective deformations under different conditions. operating the pump.
• the volume of this cavity 88 will be reduced to a minimum in order to limit the thermal bridges between the chamber 17 and the thermal barrier 37.
• the upper heat shield 73 and the lower heat shield 75 have a limited axial spacing relative to each other. This spacing must however remain greater than a minimum value, for example 1.5 mm.
• the lower gap 86 also fluidly communicates with the cavity 88.
• a gap 89 is provided between the thermal barrier body 39 and the thermal barrier cover 41 (FIG. 3), and fluidly connects the cavity 88 and the housing 47.
• the lower heat shield 75 comprises an extension 91 engaged in the upper gap 76 and rigidly attached to the tubular portion 19.
• the extension 91 has a cylindrical shape. It extends the radially outer wall of the lower heat shield 75. It extends over the entire axial height of the upper heat shield 73.
• the upper edge 93 of the extension 91 is welded by a weld bead 95, visible on the Figure 4, at the tubular portion 19. This extension makes it possible to conveniently secure the lower heat shield to the tubular portion 19.
• the extension 91 rises substantially upstream of the upper flange section 33 and can be welded easily.
• the thermal barrier 37 advantageously comprises at least one pressure drop or sealing device 97 placed in the upper gap 76 or in the cavity 88.
• This device is intended to limit or prevent the flow of fluid in the upper gap 76, in particular the primary fluid that rises from the housing 47 in the event of loss of the dynamic sealing device 67.
• the device 97 is interposed between the screen 73 and the extension 91.
• the device or devices 97 are interposed between the upper heat shields 75 and lower 73, in the cavity 88.
• the device or devices 97 are of all types: metal blade, braid, labyrinth seal, seal, segment etc. ..
• the device or devices 97 in the example shown in Figures 2 and 3, are attached to the lower end of the upper heat shield. Alternatively, they are mounted differently, and are for example compressed between the two screens.
• the upper and lower heat shields 73 and 73 typically have the same structure. They each advantageously comprise a cylindrical box 99 and a plurality of plates 101 arranged parallel to each other inside the box 99.
• the box 99 and the plates 101 are typically metallic.
• the plates 101 each have a cylindrical shape, and are placed concentrically parallel to each other. They have for example a thickness of less than 0.8 mm, typically 0.4 mm.
• Each screen comprises a large number of plates, preferably at least thirty plates 101, still preferably at least forty plates 101.
• Spacers 105 make it possible to maintain the spacing between the plates 101.
• the spacers 105 are integral with the upper cover 107 of the box.
• Orifices such as port 109 allow the upper screen to be drained during maintenance on the pump hydraulics.
• the supply 55 injects a cooling fluid into the heat exchanger 45.
• the device 67 injects a barrier fluid into the chamber 66, the latter flowing in the seals 59 , 61, 63 and along the circulation path 71 into the housing 47 and the housing 47 in the flow chamber 17.
• This barrier fluid thus fills the chamber 47, the cavity 88 and the upper gaps 76 and lower 86
• the upper heat shields 73 and lower 75 are also filled with a fluid, for example by the barrier fluid.
• This barrier fluid is typically water
• the primary fluid does not rise along the pump shaft 9 to the joints 59, 61 and 63 which are therefore maintained at their nominal temperature.
• the heat conduction from the circulation chamber 17 through the diffuser 25 to the seals 59, 61, 63 is limited by the presence of the cold barrier fluid injection device 67, the exchanger 47 thermal and upper and lower heat shields 73 and 75.
• the one or more pressure drop or sealing devices 97 limit the recirculations in the upper gap 76.
• the primary fluid can not flow between the thermal barrier body 39 and the upper heat shield 73. supply of thermal power generated by possible recirculations in the upper part is removed. Thermal transfers by conduction through the thermal barrier body 39 are therefore limited. As a result, the rise in temperature of the gasket 59 and the other seals 61 and 63 is also limited.
• the fact that the lower gap 86 continuously communicates fluidically with the housing 47 makes it possible to obtain a uniform temperature in the thermal barrier cover 41. This is advantageous in the long term for the mechanical strength of this lid.

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• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Mechanical Engineering (AREA)
• Thermal Sciences (AREA)
• Plasma & Fusion (AREA)
• High Energy & Nuclear Physics (AREA)
• Fluid Mechanics (AREA)
• Structures Of Non-Positive Displacement Pumps (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=59699763

Family Applications (1)

Country Status (5)

Family Cites Families (6)

• 2017
  • 2017-04-04 FR FR1752924A patent/FR3064808B1/fr active Active
• 2018
  • 2018-04-03 JP JP2019554644A patent/JP7079263B2/ja active Active
  • 2018-04-03 CN CN201880024186.0A patent/CN110494926B/zh active Active
  • 2018-04-03 EP EP18716206.0A patent/EP3607560A1/de active Pending
  • 2018-04-03 WO PCT/EP2018/058483 patent/WO2018185096A1/fr unknown

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