WO2018209545A1 - 核反应堆冷却剂泵及其非能动停车密封装置 - Google Patents

核反应堆冷却剂泵及其非能动停车密封装置 Download PDF

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Publication number
WO2018209545A1
WO2018209545A1 PCT/CN2017/084473 CN2017084473W WO2018209545A1 WO 2018209545 A1 WO2018209545 A1 WO 2018209545A1 CN 2017084473 W CN2017084473 W CN 2017084473W WO 2018209545 A1 WO2018209545 A1 WO 2018209545A1
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Prior art keywords
seal
ring
sealing
reactor coolant
nuclear reactor
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PCT/CN2017/084473
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English (en)
French (fr)
Inventor
丛国辉
罗志远
王学灵
张翊勋
Original Assignee
中广核工程有限公司
中国广核集团有限公司
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Application filed by 中广核工程有限公司, 中国广核集团有限公司 filed Critical 中广核工程有限公司
Priority to PCT/CN2017/084473 priority Critical patent/WO2018209545A1/zh
Priority to GB1918483.7A priority patent/GB2578030B/en
Publication of WO2018209545A1 publication Critical patent/WO2018209545A1/zh

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    • 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
    • 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
    • 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16J—PISTONS; CYLINDERS; SEALINGS
    • F16J15/00—Sealings
    • F16J15/16—Sealings between relatively-moving surfaces
    • F16J15/164—Sealings between relatively-moving surfaces the sealing action depending on movements; pressure difference, temperature or presence of leaking 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
    • F05D2300/00—Materials; Properties thereof
    • F05D2300/40—Organic materials
    • F05D2300/43—Synthetic polymers, e.g. plastics; Rubber
    • F05D2300/431—Rubber
    • 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
    • F05D2300/00—Materials; Properties thereof
    • F05D2300/50—Intrinsic material properties or characteristics
    • F05D2300/501—Elasticity

Definitions

  • the invention belongs to the field of nuclear power technology, and more particularly to a nuclear reactor coolant pump and its passive parking sealing device.
  • the hydrostatic shaft seal type coolant pump is a single-stage, single-suction, vertical mixed-flow pump driven by a three-phase induction motor.
  • 1 is a schematic view showing the structure of an existing nuclear reactor coolant pump, which includes, in order from top to bottom, an electric motor 10, a static pressure shaft seal assembly 12 and a hydraulic member 14, wherein the pump shaft runs through the center of the entire coolant pump, the reactor The coolant is pumped by an impeller mounted at the lower end of the pump shaft, which is drawn through the bottom of the pump casing and flows upward through the impeller and then discharged through the vanes and an outlet connection on the side of the pump casing.
  • the static pressure shaft seal assembly 12 in the coolant pump employs a three-stage shaft seal, including a first seal assembly 15, a second seal assembly 16, and a third, which are sequentially disposed between the hydraulic member 14 and the motor 10.
  • the seal assembly 17, three seal assemblies 15, 16, 17 are disposed in the circumferential direction of the pump shaft 18 and are arranged in the axial direction of the pump shaft 18, and a seal housing 19 is further disposed outside the first seal assembly 15 and the second seal assembly 16.
  • the first seal assembly 15 is a balanced hydrostatic type controllable leak seal
  • the second seal assembly 16 is a pressure balanced type end seal
  • the third seal assembly 17 is a ⁇ double seal.
  • the first seal assembly 15 includes a movable ring 150, a stationary ring 152, a seal insert 154, and a seal insert support 156 which are sequentially disposed between the hydraulic member 14 and the second seal assembly 16; the seal insert There is a gap between the inner wall of the 154 and the seal insertion support 156 and the pump shaft 18; the movable ring 150 is fixed on the pump shaft 18 and rotates with the pump shaft 18, and the stationary ring 152 does not rotate but can be along the axial direction of the pump shaft 18 or The tilting direction moves up and down slightly to maintain the proper clearance of the follower ring 150.
  • the static ring 152 is fluid-statically balanced, and a small gap is formed between the moving ring 150 and the stationary ring 152 to form a liquid film, so that the two end faces of the moving ring 150 and the stationary ring 152 slide relative to each other on both sides of a thin water film. It is not in direct contact during operation, thereby controlling the amount of leakage and the amount of wear of the first seal assembly 15.
  • An O-ring and an auxiliary element are disposed between the stationary ring 152 and the adjacent structural member to form a slippable auxiliary seal between the high pressure zone and the low pressure zone.
  • the cooling of the first seal assembly 15 is ensured by the injected water provided by the RCV system (Chemical and Volume Control System).
  • the RCV system Controller and Volume Control System
  • the RRI system Equipment Cooling Water System
  • the function of the equipment cooling water system is also lost and it is not possible to provide backup cooling for the first seal assembly 15 in the coolant pump.
  • the high temperature fluid of the primary circuit referring to the main circuit of the reactor coolant system
  • the static pressure shaft seal assembly 12 will quickly threaten the static pressure shaft seal assembly 12, and its thermal stress may cause the coolant pump shaft seal function to be lost, thereby destroying the primary circuit pressure boundary.
  • some nuclear power plants supply power to the primary circuit hydraulic test pump through the hydraulic test pump diesel generator set (LLS system) after the whole plant breaks the electrical condition to ensure that the hydraulic test pump seals to the coolant pump shaft.
  • Emergency flooding maintains cooling and lubrication at the first seal assembly 15 while confining the high temperature and high pressure reactor coolant below the first seal assembly 15 to ensure that the temperature at the first seal assembly 15 is within its operational requirements, preventing cooling
  • the seal pump seal accident (Seal LOCA) occurs to ensure the integrity of the pressure boundary of the primary circuit.
  • the two units share a hydraulic test pump, and only one unit is considered to have a power failure. Therefore, the nominal flow of the hydraulic test pump is 6m3/h.
  • some nuclear power plants propose to protect the closed reactor coolant leakage path.
  • the safety of the core is to avoid the dependence of the emergency pump seal injection system of the coolant pump under the condition of the entire factory.
  • an active parking seal can be used to limit leakage at the shaft seal, but an auxiliary system (such as a nitrogen drive system) is required to control its startup and shutdown.
  • the flow direction of the high temperature and high pressure fluid at the first seal assembly 15 of the coolant pump is as shown by the arrow in Fig. 4.
  • the key to limiting the leakage of the reactor coolant to the environment lies in The two important sealing locations 20, 22 are sealed.
  • Some existing nuclear power plants have begun to adopt passive parking sealing technology to ensure the integrity of the coolant pump shaft seal, independent of the configuration of the auxiliary system, the specific operation mode is: 1) directly in the coolant pump first seal assembly 15
  • the non-reactive parking seal 24 is added to the seal insert 154 to achieve the seal at the first sealing position 20; 2) the high temperature rubber O-ring 26 is used to achieve the second sealing position 22 (ie, the seal insert support 156 is Sealing between the sealing shells 19).
  • the existing passive parking seal 24 has many components and complicated assembly, which not only makes the shaft seal assembly difficult to manufacture and cost, but also easily causes seal failure due to failure of one or more components.
  • the object of the present invention is to overcome the deficiencies of the prior art and provide a nuclear reactor coolant pump with a simple structure and a firm seal and a passive parking seal device thereof.
  • the present invention provides a nuclear reactor coolant pump passive parking seal device comprising:
  • the sealing ring when the limiting ring is below the state transition temperature, the sealing ring surrounds the circumferential direction of the nuclear reactor coolant pump shaft under the support of the limiting ring and maintains a gap with the pump shaft; the limiting ring is at the state transition temperature or Above the state transition temperature, the limit ring softens or melts, the seal ring loses the support of the limit ring and holds the pump shaft, preventing the reactor coolant from flowing along the pump shaft.
  • the seal ring is made of a material having elastic deformation ability, which tends to close when being radially limited by the limit ring; When the limit ring is at or above the state transition temperature, the seal ring is elastically held by the pump shaft.
  • the seal ring is made of a rubber or polymer material and is resistant to high temperatures of 292 degrees Celsius and above.
  • the seal ring is made of ethylene propylene diene monomer (EPDM).
  • the retaining ring is made of a high molecular polymer which is kept rigid at normal temperature and softened or melted at a high temperature.
  • the softening temperature of the polymer material of the limiting ring is from 80 degrees Celsius to 260 degrees Celsius.
  • the inner diameter of the retaining ring is slightly larger than the outer diameter of the pump shaft, and a gap is formed between the pump shaft and the pump shaft.
  • the present invention also provides a nuclear reactor coolant pump comprising an electric motor arranged in order from top to bottom, a static pressure shaft seal assembly and a hydraulic component, and a pump shaft extending through the center of the entire coolant pump.
  • the static pressure shaft seal assembly includes a plurality of seal assemblies disposed in sequence between a coolant pump hydraulic component and an electric motor, the plurality of seal assemblies being disposed in a circumferential direction of the pump shaft, wherein at least one of the plurality of seal assemblies and the pump
  • the aforementioned nuclear reactor coolant pump passive parking seal device is disposed between the shafts.
  • a seal assembly closest to the hydraulic component in the static pressure shaft seal assembly is a first seal assembly, and a nuclear reactor coolant pump passive parking seal device is installed in the static pressure shaft seal assembly. On a sealed assembly.
  • the first sealing assembly of the nuclear reactor coolant pump static pressure shaft seal assembly comprises a moving ring, a static ring, a sealing insert and a sealing insertion support, and a nuclear reverse
  • the passive coolant pump sealing device is installed in the receiving groove formed by the inner wall of the sealing insert, or is installed in the receiving groove formed by the inner wall of the sealing insertion support; under the condition of the whole factory breaking electric, slightly changed
  • the soft sealing ring is pressed against the pump shaft while being driven by the coolant, and is also pressed against the sealing insert or the sealing insertion support in the direction away from the split ring, driven by the coolant, and inserted in the pump shaft and the seal. There is a slight amount of extrusion in the gap between the support or the sealing insert.
  • the static pressure shaft seal assembly adopts a three-stage shaft seal, and includes a first seal assembly, a second seal assembly and a third seal assembly which are sequentially disposed between the hydraulic component and the motor;
  • the first sealing component is a balanced hydrostatic type controllable leakage sealing
  • the second sealing component is a pressure balanced type end face sealing
  • the third sealing component is a ⁇ type double end sealing.
  • the passive reactor sealing device of the nuclear reactor coolant pump of the present invention only has two components: a sealing ring and a limiting ring, and the sealing ring is independent of the starting position to the starting position. External force, the whole seal has the advantages of simple structure and reliable sealing.
  • Figure 1 is a schematic view showing the structure of a conventional nuclear reactor coolant pump.
  • FIG. 2 is a schematic cross-sectional view of a static pressure shaft seal assembly in the coolant pump of FIG. 1.
  • Figure 3 is a cross-sectional view of the first seal assembly of the coolant pump of Figure 1.
  • FIG. 4 is a schematic structural view of a conventional passive parking seal device.
  • Figure 5 is a schematic view showing the installation of the nuclear reactor coolant pump passive parking seal device on the first seal assembly of the nuclear reactor coolant pump.
  • FIG. 6 is an exploded perspective view of a passive shutdown sealing device for a nuclear reactor coolant pump of the present invention.
  • Figure 7 is a schematic view showing the assembly of the passive parking seal device of the nuclear reactor coolant pump of the present invention.
  • Figure 8 is a schematic view showing the state of the passive parking seal device of the nuclear reactor coolant pump of the present invention and the flow direction of the coolant in the vicinity under normal operating conditions.
  • Fig. 9 is a schematic view showing the state of the passive parking seal device of the nuclear reactor coolant pump of the present invention and the flow direction of the coolant in the vicinity thereof under the condition of the whole plant breaking electrical condition.
  • the nuclear reactor coolant pump of the present invention comprises an electric motor arranged in order from top to bottom, a static pressure shaft seal assembly and a hydraulic component, and a pump shaft running through the center of the entire coolant pump, wherein the reactor coolant is installed at the lower end of the pump shaft.
  • the impeller is pumped through the bottom of the pump casing and flows upward through the impeller, and then exits through the vanes and an outlet connection on the side of the pump casing.
  • the static pressure shaft seal assembly adopts a three-stage shaft seal, and includes a first seal assembly, a second seal assembly and a third seal assembly which are sequentially disposed between the coolant pump hydraulic component and the electric motor, wherein the three seal assemblies are disposed on the pump shaft
  • the circumferential direction is arranged in the axial direction of the pump shaft, and a sealing shell is further disposed outside the first sealing assembly and the second sealing assembly.
  • the first seal assembly is a balanced hydrostatic type controllable leak seal
  • the second seal assembly is a pressure balanced end seal
  • the third seal assembly is a ⁇ double seal.
  • the first seal assembly includes a moving ring, a stationary ring, a seal insert, and a seal insert support disposed in sequence between the hydraulic component and the second seal assembly; the inner wall of the seal insert and the seal insert support are present between the pump shaft and the pump shaft a slit; a portion of the outer wall of the sealing insertion support member is in close contact with the sealing case to be sealed with the sealing case.
  • the moving ring is fixed on the pump shaft and rotates with the pump shaft.
  • the static ring does not rotate but can move up and down slightly along the axial or oblique direction of the pump shaft to maintain proper clearance with the moving ring.
  • the static ring Under normal operating conditions, the static ring is hydrostatically balanced, and a small gap is formed between the moving ring and the stationary ring to form a liquid film, so that the two end faces of the moving ring and the stationary ring are on both sides of a thin water film. Relative sliding, no direct contact during operation, thereby controlling the amount of leakage and wear of the first seal assembly.
  • An O-ring and an auxiliary element are disposed between the stationary ring and the adjacent structural member to form a slippable auxiliary seal between the high pressure zone and the low pressure zone.
  • the present invention also provides a passive parking seal between the first seal assembly and the pump shaft.
  • the nuclear reactor coolant pump passive parking seal device 30 of the present invention is installed in a receiving groove formed by the inner wall of the sealing insert 154 of the first seal assembly 15 of the nuclear reactor coolant pump, which is in normal operation. There is a gap between the pump shaft 18 and the pump coolant 18, so that the reactor coolant can flow freely along the pump shaft 18, but the pump seal 18 will be in close contact with the pump shaft 18 to achieve the first seal assembly 15 and the pump shaft 18 Circumferential seal between.
  • the nuclear reactor coolant pump passive parking seal 30 of the present invention includes a seal ring 40, a retaining ring 50 that fits over the seal ring 40 and supports the seal ring 40.
  • the sealing ring 40 is a closed complete ring which is expanded by the limiting ring 50 and has an inner diameter slightly larger than the outer diameter of the pump shaft 18. Therefore, in the normal state, when the sealing ring 40 surrounds the pump shaft 18, the pump can be combined with the pump.
  • the shaft 18 retains a gap to allow free flow of reactor coolant between the seal ring 40 and the pump shaft 18.
  • the seal ring 40 is made of a rubber material such as EPDM or other resilient sealing material and can withstand temperatures of 292 degrees Celsius. The material of the seal ring 40 maintains its elasticity at normal temperature and high temperature, and a reliable seal can be achieved.
  • the limiting ring 50 is made of a high molecular polymer which is kept rigid at normal temperature and softened or melted at a high temperature, and the softening temperature of the polymer material of the limiting ring 50 is 80 degrees Celsius to 260 degrees Celsius.
  • the retaining ring 50 supports the seal ring 40. At normal temperature, it maintains a gap between the seal ring 40 and the pump shaft 18, so that the reactor coolant can flow freely between the seal ring 40 and the pump shaft 18; at high temperatures, All or part of the polymeric material used therein is softened or melted, thereby no longer limiting the sealing ring 40 from gripping the pump shaft 18.
  • the stop ring 50 may be made of a single material or a plurality of materials, or may be implemented by a single component or a plurality of components.
  • the seal ring 40 of the nuclear reactor coolant pump passive parking seal device 30 of the present invention is received in a receiving groove formed by the inner wall of the sealing insert 154 of the first seal assembly 15 .
  • the seal ring 40 With the support of the stop ring 50, the seal ring 40 surrounds the pump shaft 18 and maintains a gap 32 with the pump shaft 18, so that the reactor coolant leakage can be in the direction indicated by the arrow A in the passive parking seal 30 and the pump. Free flow between the shafts 18, through the seal insert 154 into the first seal Leaked in the pipeline.
  • the high-temperature high-pressure reactor coolant flows upward along the pump shaft 18, and the temperature at the limit ring 50 After reaching its softening or melting temperature and after a certain period of time (the preset time, usually a few minutes to ten minutes), the limit ring 50 will lose the limit support. At this time, the seal ring 40 is contracted toward the pump shaft 18 by its own elasticity to hold the pump shaft 18, thereby achieving a sealing function.
  • the nuclear reactor coolant pump passive parking seal 30 of the present invention may also be mounted on the seal insert 154 of the first seal assembly 15 instead of being mounted on the first The seal of the seal assembly 15 is inserted into the support member 156 as long as it can limit the leakage of the reactor coolant to the environment.
  • the nuclear reactor coolant pump passive parking seal of the present invention has the following advantages over the prior art:
  • the passive reactor sealing device of the nuclear reactor coolant pump of the present invention only has two components: a sealing ring 40 and a limiting ring 50 for limiting.
  • the sealing ring 40 does not depend on external force from the non-starting position to the starting position.
  • the seal has the advantages of simple structure and reliable sealing.
  • the sealing ring 40 is no longer restricted by the high temperature lower limit ring 50, so that the sealing ring is tightly held by the pump shaft 18, thereby effectively ensuring the functional integrity of the coolant pump static pressure shaft seal under the entire factory electrical condition, and the pair is released.
  • the emergency shaft seal injection system and the active drive depend on it, and effectively reduce the core damage probability of the nuclear power plant;
  • the present invention merely grooves the inner wall of the seal insert 154 or the seal insert support 156 of the first seal assembly 15, thereby having no effect on other structures of the coolant pump, and does not affect the coolant pump in normal operation. Performance at runtime.

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

Abstract

一种核反应堆冷却剂泵非能动停车密封装置（30），其包括：可在启动位置和非启动位置的完整密封环（40）；以及可在达到状态转化温度时发生软化的完整限位环（50）；其中，在限位环处于状态转化温度以下时，密封环在限位环的支撑作用下环绕在核反应堆冷却剂泵泵轴（18）的周向并与泵轴保持间隙；在限位环处于状态转化温度或高于状态转化温度时，限位环发生软化或熔化，密封环失去限位环的支撑并抱紧泵轴，阻止反应堆冷却剂沿泵轴流动。所述核反应堆冷却剂泵非能动停车密封装置仅设有起密封的密封环和起限位作用的限位环两个元件，密封环从非启动位置到启动位置不依赖于外力，整个密封具有结构简单、密封可靠的优点。

Description

核反应堆冷却剂泵及其非能动停车密封装置 技术领域
本发明属于核电技术领域，更具体地说，本发明涉及一种核反应堆冷却剂泵及其非能动停车密封装置。
背景技术
在压水堆核电厂中，流体静压轴封型冷却剂泵是由三相感应式电动机驱动的单级、单吸、立式混流泵。图1所示为一种现有核反应堆冷却剂泵的结构示意图，其从上至下依次包括电动机10、静压轴封组件12和水力部件14，其中，泵轴贯穿整个冷却剂泵的中心，反应堆冷却剂由一个装在泵轴下端的叶轮泵送，其通过泵壳底部吸入并向上流过叶轮，然后通过导叶和泵壳侧面的一个出口接管排出。
请参阅图2所示，冷却剂泵中的静压轴封组件12采用三级轴封，包括依次设置在水力部件14和电动机10之间的第一密封组件15、第二密封组件16和第三密封组件17，三个密封组件15、16、17设置在泵轴18的周向并沿泵轴18轴向依次排列，第一密封组件15和第二密封组件16外部还设有密封壳19。第一密封组件15是平衡型流体静压型可控泄漏密封，第二密封组件16是压力平衡型端面密封，第三密封组件17是堰式双端面密封。
请参阅图3所示，第一密封组件15包括依次设置在水力部件14和第二密封组件16之间的动环150、静环152、密封插入件154和密封插入支撑件156；密封插入件154和密封插入支撑件156的内壁均与泵轴18之间存在缝隙；动环150固定在泵轴18上而随泵轴18转动，静环152不转动但可以沿泵轴18的轴向或倾斜方向小幅上下移动，以跟动环150保持恰当间隙。在正常运行工况下， 静环152通过流体静力平衡，控制动环150、静环152之间保持极小的间隙形成液膜，使动环150、静环152两个端面在一层薄水膜两侧相对滑动，运转时不直接接触，从而控制第一密封组件15的泄漏量和磨损量。在静环152与相邻的结构件之间配有O形环及辅助元件，以在高压区和低压区之间形成一个可滑移的辅助密封。
在正常运行工况下，第一密封组件15的冷却由RCV系统(Chemical and Volume Control System，即化学及容积控制系统)提供的注入水来保障。但是，在事故工况下(如全厂断电工况)，RCV系统功能会丧失而无法为冷却剂泵中的静压轴封组件12提供正常冷却，同时，RRI系统(Equipment Cooling Water System，即设备冷却水系统)的功能也会丧失，无法为冷却剂泵中的第一密封组件15提供备用冷却。此时，一回路(指反应堆冷却剂系统主回路)的高温流体将很快威胁到静压轴封组件12，其热应力可能使冷却剂泵轴封功能丧失，从而破坏一回路压力边界。
为此，部分核电厂在全厂断电工况发生后，通过水压试验泵柴油发电机组(LLS系统)向一回路的水压试验泵供电，以保证水压试验泵向冷却剂泵轴封应急注水，维持第一密封组件15处的冷却及润滑，同时将高温高压反应堆冷却剂限制在第一密封组件15下方，保证第一密封组件15处的温度在其运行要求的范围内，防止冷却剂泵轴封破口事故(Seal LOCA)发生，保证一回路压力边界的完整性。但是，由于现有核电厂多为双堆布置，两台机组共用一台水压试验泵，在设计上也仅考虑单台机组发生断电事故，因此水压试验泵的名义流量为6m3/h，仅能满足一台机组3台冷却剂泵的轴封水注入量需求；这导致在全厂断电工况时，另外一台机组的冷却剂泵应急轴封注入无法保证而发生轴封破口事故；在失去了所有的补水手段后，一回路的泄漏无法得到补充，水装量得不到保证，将使得堆芯逐渐裸露并最终熔化。
为了解决上述问题，一些核电厂提出通过封闭反应堆冷却剂泄漏途径来保 证堆芯的安全，以避免全厂断电工况下对冷却剂泵应急轴封注入系统的依赖。通常，可以采用能动式停车密封对于轴封处的泄漏进行限制，但需要辅助系统(如氮气驱动系统)控制其启动和关闭。
在全厂断电工况下，冷却剂泵第一密封组件15处的高温高压流体流动方向如图4的箭头所示，从图4中可以看出，限制反应堆冷却剂向环境泄漏的关键在于对两个重要密封位置20、22进行密封。现有的部分核电厂已开始采用非能动停车密封技术来保证冷却剂泵轴封的完整性，不依赖辅助系统的配置，其具体操作方式是：1)直接在冷却剂泵第一密封组件15的密封插入件154内增加非能动停车密封装置24，来实现第一密封位置20处的密封；2)采用耐高温橡胶O圈26，实现第二密封位置22处(即密封插入支撑件156与密封壳19之间)的密封。但是，现有的非能动停车密封装置24大多元件众多且装配复杂，不仅使得轴封组件制造难度和成本加大，而且易于因某一个或多个元件故障而导致密封失效。
有鉴于此，确有必要提供一种结构简单、密封牢固的核反应堆冷却剂泵非能动停车密封装置。
发明内容
本发明的目的在于：克服现有技术的不足，提供一种结构简单、密封牢固的核反应堆冷却剂泵及其非能动停车密封装置。
为了实现上述发明目的，本发明提供了一种核反应堆冷却剂泵非能动停车密封装置，其包括：
可在启动位置和非启动位置的完整密封环；以及
可在达到状态转化温度时发生软化的完整限位环；
其中，在限位环处于状态转化温度以下时，密封环在限位环的支撑作用下环绕在核反应堆冷却剂泵泵轴的周向并与泵轴保持间隙；在限位环处于状态转化温度或高于状态转化温度时，限位环发生软化或熔化，密封环失去限位环的支撑并抱紧泵轴，阻止反应堆冷却剂沿泵轴流动。
作为本发明核反应堆冷却剂泵非能动停车密封装置的一种改进，所述密封环由具有弹性变形能力的材料制成，其在被所述限位环进行径向限位时趋向闭合；在所述限位环处于所述状态转化温度或高于所述状态转化温度时，所述密封环依靠自身弹性抱紧泵轴。
作为本发明核反应堆冷却剂泵非能动停车密封装置的一种改进，所述密封环由橡胶或高分子聚合物材料制成，能够耐292摄氏度及以上的高温。
作为本发明核反应堆冷却剂泵非能动停车密封装置的一种改进，所述密封环由三元乙丙橡胶(EPDM)制成。
作为本发明核反应堆冷却剂泵非能动停车密封装置的一种改进，所述限位环由常温下保持刚性、高温下变软或熔化的高分子聚合物制成。
作为本发明核反应堆冷却剂泵非能动停车密封装置的一种改进，所述限位环的高分子聚合物材料的软化温度为80摄氏度～260摄氏度。
作为本发明核反应堆冷却剂泵非能动停车密封装置的一种改进，所述限位环的内径略大于泵轴的外径，与泵轴之间形成允许流体经过的间隙。
为了实现上述发明目的，本发明还提供了一种核反应堆冷却剂泵，其包括从上至下依次设置的电动机、静压轴封组件和水力部件，以及一根贯穿整个冷却剂泵中心的泵轴，静压轴封组件包括依次设置在冷却剂泵水力部件和电动机之间的多个密封组件，多个密封组件均设置在泵轴的周向，其中，所述多个密封组件中的至少一个与泵轴之间设有前述核反应堆冷却剂泵非能动停车密封装置。
作为本发明核反应堆冷却剂泵的一种改进，所述静压轴封组件中最靠近水力部件的一个密封组件为第一密封组件，核反应堆冷却剂泵非能动停车密封装置安装在静压轴封组件的第一密封组件上。
作为本发明核反应堆冷却剂泵的一种改进，所述核反应堆冷却剂泵静压轴封组件的第一密封组件包括动环、静环、密封插入件和密封插入支撑件，核反 应堆冷却剂泵非能动停车密封装置安装在密封插入件内壁所开设的收容槽中，或是安装在密封插入支撑件内壁所开设的收容槽中；在全厂断电工况下，略微变软的密封环在冷却剂驱动下向泵轴方向压紧的同时，还在冷却剂驱动下沿远离开口环的方向，向密封插入件或密封插入支撑件压紧，并在泵轴与密封插入支撑件或密封插入件之间的缝隙中有微量挤出。
作为本发明核反应堆冷却剂泵的一种改进，所述静压轴封组件采用三级轴封，包括依次设置在水力部件和电动机之间的第一密封组件、第二密封组件和第三密封组件；其中，第一密封组件是平衡型流体静压型可控泄漏密封，第二密封组件是压力平衡型端面密封，第三密封组件是堰式双端面密封。
相对于现有技术，本发明核反应堆冷却剂泵非能动停车密封装置仅设有起密封的密封环和起限位作用的限位环两个元件，密封环从非启动位置到启动位置不依赖于外力，整个密封具有结构简单、密封可靠的优点。
附图说明
下面结合附图和具体实施方式，对本发明核反应堆冷却剂泵及其非能动停车密封装置进行详细说明。
图1为现有核反应堆冷却剂泵的结构示意图。
图2是图1所示冷却剂泵中的静压轴封组件的剖视示意图。
图3是图1所示冷却剂泵中的第一密封组件的剖视示意图。
图4为现有非能动停车密封装置的结构示意图。
图5为本发明核反应堆冷却剂泵非能动停车密封装置在核反应堆冷却剂泵第一密封组件上的安装示意图。
图6为本发明核反应堆冷却剂泵非能动停车密封装置的分解示意图。
图7为本发明核反应堆冷却剂泵非能动停车密封装置的组装示意图。
图8为正常工况下，本发明核反应堆冷却剂泵非能动停车密封装置的状态及其附近冷却剂流向的示意图。
图9为全厂断电工况下，本发明核反应堆冷却剂泵非能动停车密封装置的状态及其附近冷却剂流向的示意图。
具体实施方式
为了使本发明的发明目的、技术方案及其有益技术效果更加清晰，以下结合附图和具体实施方式，对本发明进行进一步详细说明。应当理解的是，本说明书中描述的具体实施方式仅仅是为了解释本发明，并非为了限定本发明。
本发明核反应堆冷却剂泵包括从上至下依次设置的电动机、静压轴封组件和水力部件，以及一根贯穿整个冷却剂泵中心的泵轴，其中，反应堆冷却剂由一个装在泵轴下端的叶轮泵送，其通过泵壳底部吸入并向上流过叶轮，然后通过导叶和泵壳侧面的一个出口接管排出。
静压轴封组件采用三级轴封，包括依次设置在冷却剂泵水力部件和电动机之间的第一密封组件、第二密封组件和第三密封组件，其中，三个密封组件设置在泵轴的周向并沿泵轴轴向依次排列，第一密封组件和第二密封组件外部还设有密封壳。第一密封组件是平衡型流体静压型可控泄漏密封，第二密封组件是压力平衡型端面密封，第三密封组件是堰式双端面密封。
第一密封组件包括依次设置在水力部件和第二密封组件之间的动环、静环、密封插入件和密封插入支撑件；密封插入件和密封插入支撑件的内壁均与泵轴之间存在缝隙；密封插入支撑件的部分外壁紧贴密封壳而与密封壳密封。动环固定在泵轴上而随泵轴转动，静环不转动但可以沿泵轴轴向或倾斜方向小幅上下移动，以跟动环保持恰当间隙。在正常运行工况下，静环通过流体静力平衡，控制动环、静环之间保持极小的间隙形成液膜，使动环、静环的两个端面在一层薄水膜两侧相对滑动，运转时不直接接触，从而控制第一密封组件的泄漏量和磨损量。在静环与相邻的结构件之间配有O形环及辅助元件，以在高压区和低压区之间形成一个可滑移的辅助密封。为了能够在全厂断电工况下保证堆芯的安全，本发明还在第一密封组件与泵轴之间设置了一个非能动停车密封装置。
请参阅图5至图9所示，本发明核反应堆冷却剂泵非能动停车密封装置30安装在核反应堆冷却剂泵第一密封组件15的密封插入件154内壁所开设的收容槽中，其在正常工况下与泵轴18之间存在间隙，使反应堆冷却剂可以沿泵轴18自由流动，但在全厂断电工况下将紧贴泵轴18而实现第一密封组件15与泵轴18之间的周向密封。
请参阅图6至图7所示，本发明核反应堆冷却剂泵非能动停车密封装置30包括密封环40、贴合在密封环40上并用于支撑密封环40的限位环50。
密封环40为闭合的完整圆环，其被限位环50撑开后内径略大于泵轴18的外径，因此，在正常状态下，密封环40环绕在泵轴18外时，可与泵轴18保留一定间隙以允许反应堆冷却剂在密封环40与泵轴18之间自由流动。密封环40由橡胶材料制成，如由三元乙丙橡胶(EPDM)或是其他具有弹性的密封材料制成，且可以耐受292摄氏度的高温。密封环40的材料使其在常温和高温下保持弹性，且可以实现可靠密封。
限位环50由常温下保持刚性、高温下变软或熔化的高分子聚合物制成，限位环50的高分子聚合物材料的软化温度为80摄氏度～260摄氏度。限位环50支撑密封环40，在常温下，其维持密封环40与泵轴18之间的间隙，使反应堆冷却剂可以在密封环40和泵轴18之间自由流动；在高温下，可利用其采用的全部或部分的高分子聚合物材料变软或熔化，从而不再限制密封环40抱紧泵轴18。限位环50可以由单一材料或多种材料制成，也可以由单一部件或多个部件共同实现功能。
请参阅图8所示，在正常工况下，本发明核反应堆冷却剂泵非能动停车密封装置30的密封环40收容在第一密封组件15的密封插入件154内壁所开设的收容槽中，在限位环50的支撑作用下密封环40环绕在泵轴18周向并与泵轴18保持间隙32，使反应堆冷却剂泄漏可以沿着箭头A所示的方向在非能动停车密封装置30与泵轴18之间自由流动，穿过密封插入件154而进入到第一密封泄 漏管线中。
请参阅图9所示，在全厂断电工况下，冷却剂泵轴封注入水和冷却水同时丧失时，高温高压反应堆冷却剂沿泵轴18向上流动，当限位环50处的温度达到其变软或熔化温度并经过一定的时间(时间为预设时间，一般为几分钟到十几分钟)后，限位环50将失去限位支撑作用。此时，密封环40将在自身弹性的作用下向泵轴18收缩而抱紧泵轴18，实现密封功能。
可以理解的是，在本发明的其他实施方式中，本发明核反应堆冷却剂泵非能动停车密封装置30也可以不安装在第一密封组件15的密封插入件154上，而改为安装在第一密封组件15的密封插入支撑件156上，只要能达到限制反应堆冷却剂向环境泄漏的目的即可。
结合以上对本发明实施方式的详细描述可知，相对于现有技术，本发明核反应堆冷却剂泵非能动停车密封装置具有以下优点：
本发明核反应堆冷却剂泵非能动停车密封装置仅设有起密封的密封环40和起限位作用的限位环50两个元件，密封环40从非启动位置到启动位置不依赖于外力，整个密封具有结构简单、密封可靠的优点。
通过高温下限位环50不再对密封环40进行限位实现密封环抱紧泵轴18实现密封，从而有效保证冷却剂泵静压轴封在全厂断电工况下的功能完整性，解除了对应急轴封注入系统和能动驱动装置的依赖，并且有效降低了核电厂的堆芯损坏概率；
此外，本发明只是对第一密封组件15的密封插入件154或密封插入支撑件156的内壁进行开槽，因此对冷却剂泵的其他结构没有任何影响，也不会影响冷却剂泵在正常工况下运行时的性能。
根据上述说明书的揭示和教导，本发明所属领域的技术人员还可以对上述实施方式进行适当的变更和修改。因此，本发明并不局限于上面揭示和描述的具体实施方式，对本发明的一些修改和变更也应当落入本发明的权利要求的保 护范围内。此外，尽管本说明书中使用了一些特定的术语，但这些术语只是为了方便说明，并不对本发明构成任何限制。

Claims (11)

  1. 一种核反应堆冷却剂泵非能动停车密封装置，其特征在于，包括：
    可在启动位置和非启动位置的完整密封环；以及
    可在达到状态转化温度时发生软化的完整限位环；
    其中，在限位环处于状态转化温度以下时，密封环在限位环的支撑作用下环绕在核反应堆冷却剂泵泵轴的周向并与泵轴保持间隙；在限位环处于状态转化温度或高于状态转化温度时，限位环发生软化或熔化，密封环失去限位环的支撑并抱紧泵轴，阻止反应堆冷却剂沿泵轴流动。
  2. 根据权利要求1所述的核反应堆冷却剂泵非能动停车密封装置，其特征在于：所述密封环由具有弹性变形能力的材料制成，其在被所述限位环进行径向限位时趋向闭合；在所述限位环处于所述状态转化温度或高于所述状态转化温度时，所述密封环依靠自身弹性抱紧泵轴。
  3. 根据权利要求2所述的核反应堆冷却剂泵非能动停车密封装置，其特征在于：所述密封环由橡胶或高分子聚合物材料制成，能够耐292摄氏度及以上的高温。
  4. 根据权利要求3所述的核反应堆冷却剂泵非能动停车密封装置，其特征在于：所述密封环由三元乙丙橡胶制成。
  5. 根据权利要求1所述的核反应堆冷却剂泵非能动停车密封装置，其特征在于：所述限位环由常温下保持刚性、高温下变软或熔化的高分子聚合物制成。
  6. 根据权利要求5所述的核反应堆冷却剂泵非能动停车密封装置，其特征在于：所述限位环的高分子聚合物材料的软化温度为80摄氏度～260摄氏度。
  7. 根据权利要求1所述的核反应堆冷却剂泵非能动停车密封装置，其特征在于：所述限位环的内径略大于泵轴的外径，与泵轴之间形成允许流体经过的间隙。
  8. 一种核反应堆冷却剂泵，其包括从上至下依次设置的电动机、静压轴封组件和水力部件，以及一根贯穿整个冷却剂泵中心的泵轴，静压轴封组件包括依次设置在冷却剂泵水力部件和电动机之间的多个密封组件，多个密封组件均设置在泵轴的周向，其特征在于：所述多个密封组件中的至少一个与泵轴之间设有权利要求1至7中任一项所述的核反应堆冷却剂泵非能动停车密封装置。
  9. 根据权利要求8所述的核反应堆冷却剂泵，其特征在于：所述静压轴封组件中最靠近水力部件的一个密封组件为第一密封组件，核反应堆冷却剂泵非能动停车密封装置安装在静压轴封组件的第一密封组件上。
  10. 根据权利要求9所述的核反应堆冷却剂泵，其特征在于：所述核反应堆冷却剂泵静压轴封组件的第一密封组件包括动环、静环、密封插入件和密封插入支撑件，核反应堆冷却剂泵非能动停车密封装置安装在密封插入件内壁所开设的收容槽中，或是安装在密封插入支撑件内壁所开设的收容槽中；在全厂断电工况下，略微变软的密封环在冷却剂驱动下向泵轴方向压紧的同时，还在冷却剂驱动下沿远离开口环的方向，向密封插入件或密封插入支撑件压紧，并在泵轴与密封插入支撑件或密封插入件之间的缝隙中有微量挤出。
  11. 根据权利要求10所述的核反应堆冷却剂泵，其特征在于：所述静压轴封组件采用三级轴封，包括依次设置在水力部件和电动机之间的第一密封组件、第二密封组件和第三密封组件；其中，第一密封组件是平衡型流体静压型可控泄漏密封，第二密封组件是压力平衡型端面密封，第三密封组件是堰式双端面密封。
PCT/CN2017/084473 2017-05-16 2017-05-16 核反应堆冷却剂泵及其非能动停车密封装置 WO2018209545A1 (zh)

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