Collection device for bearing oil mist from Reactor Coolant Pump motors

Abstract

In the bearing oil vapor collection device of the reactor coolant pump motor according to the present invention, the coolant pump motor comprises a stator, a rotor, an upper bearing, and a lower bearing; an upper shaft, a guide bearing, and a thrust bearing are installed in the upper bearing of the motor; high-temperature oil circulating inside the oil reservoir of the upper bearing of the motor is cooled by a water cooler and flows into an oil port; the oil supplied from the oil port flows into the space between the upper shaft and the labyrinth seal to lubricate the guide bearing; a lower shaft and a guide bearing are installed in the lower bearing of the motor; high-temperature oil circulating inside the oil reservoir of the lower bearing of the motor is cooled by a water cooler and flows into an oil port; the oil supplied from the oil port flows into the space between the lower shaft and the labyrinth seal to lubricate the guide bearing; and an oil deflector for collecting oil vapor is installed above the oil port. This concerns a vapor capture device.

Description

Technology Field

[0001] The present invention relates to a device for capturing bearing oil mist of a reactor coolant pump (RCP) motor. Background Technology

[0003] The configuration of a bearing assembly for a coolant pump comprising a coolant pump having a shaft, an electric motor having an electric drive shaft aligned with the shaft, and a coupling unit coupled to surround the outer circumference of the shaft and the electric drive shaft so as to reduce axial vibration of the aligned connecting shaft is disclosed in Korean Registered Patent Publication No. 10-1409881.

[0004] The power transmission unit of the bearing assembly for the coolant pump includes a frame supporting the drive unit, an upper shaft arranged along the axial direction inside the frame, a coupling unit that is detachably coupled to the drive unit and the upper shaft to transmit power from the drive unit to the upper shaft, and an oil reservoir formed around the perimeter of the bearing assembly for the coolant pump, with an opening formed at the top having a diameter larger than the diameter of the bearing cover.

[0005] The coupling unit is coupled to surround the outer circumference of the shaft and the drive shaft so as to reduce axial vibration of the axially aligned connecting shaft, and is equipped with gears formed to mesh with each other between the coupling unit and the shaft, and between the coupling unit and the drive shaft, respectively.

[0006] Korean Published Patent Application No. 10-2013-0079097 discloses a reactor coolant pump capable of separating and inspecting an axial thrust bearing assembly without lifting the electric motor.

[0007] A reactor coolant pump includes a pumping section, a driving section, and a power transmission section that transmits power from the driving section to the pumping section.

[0008] It is provided with an upper shaft that is arranged along the vertical direction inside a frame supporting the drive unit of the power transmission unit and connected to a pumping unit at the bottom.

[0009] An axial thrust bearing assembly is configured to support an upper shaft in the axial direction by comprising a collar member coupled to an upper shaft, a bearing housing that accommodates the collar member internally, and a bearing cover disposed in the upper opening of the bearing housing.

[0010] A coupling unit is configured having a first toothed member detachably coupled to an upper shaft, a first coupling housing toothedly coupled to the first toothed member, and a second coupling housing detachably coupled to the first coupling housing.

[0011] The configuration includes an oil reservoir formed around the perimeter of the bearing housing and an oil reservoir cover provided at the top of the oil reservoir, with a through opening in the center through which the bearing cover can be pulled out.

[0012] As a result, the shaft thrust bearing assembly can be disassembled and inspected at every inspection cycle without lifting the electric motor. Prior art literature

[0014] Korean Registered Patent Publication KR 10-1409881 B1 Korean Published Patent Publication KR 10-2013-0079097 A The problem to be solved

[0015] Oil leakage in the lower bearings of standard reactor coolant pump motors occurs due to the difference between the internal and external pressures of the oil reservoir during motor rotation.

[0016] After lubricating the lower guide bearing, the vaporized oil leaks in the form of oil mist through the gap between the shaft and the bearing.

[0017] An oil leak occurred in the lower bearing of the reactor coolant pump motor of the Korean standard nuclear power plant type OPR (Optimized Power Reactor)-1000.

[0018] As an improvement measure to prevent oil leakage, atmospheric pressure compensation piping was expanded and added to reduce negative pressure, but complete prevention of oil leakage was not easy.

[0019] Therefore, the purpose is to prevent oil leakage from the lower bearing of a standard reactor coolant pump motor by capturing oil vapor generated during the bearing lubrication process in an oil reservoir and reducing the pressure difference by decreasing the internal pressure of the oil reservoir. means of solving the problem

[0021] In the bearing oil vapor capture device of the reactor coolant pump motor of the present invention, the coolant pump motor includes a stator, a rotor, an upper bearing, and a lower bearing.

[0022] An upper shaft, a guide bearing, and a thrust bearing are installed in the upper bearing of the motor according to the present invention, and high-temperature oil circulating inside the oil reservoir of the upper bearing of the motor is cooled in a water cooler and flows into an oil port, and the oil supplied from the oil port flows into the space between the upper shaft and the labyrinth seal to lubricate the guide bearing.

[0023] A lower shaft and a guide bearing are installed in the lower bearing of the motor of the present invention, and high-temperature oil circulating inside the oil reservoir of the lower bearing of the motor is cooled by a water cooler and flows into an oil port, and the oil supplied from the oil port flows into the space between the lower shaft and the labyrinth seal to lubricate the guide bearing, and an oil deflector is installed above the oil port to collect oil vapor.

[0024] The lubricating oil reservoir of the lower bearing of the electric motor according to the present invention is configured to include an air intake pipe for reducing pressure and an atmospheric pressure compensation pipe for preventing a decrease in negative pressure in the oil reservoir.

[0025] The high-temperature oil vapor passing through the lower guide bearing of the present invention is liquefied in a low-temperature oil deflector installed in contact with the passage through which cooling water flows in from the cooling water supply unit, and is recirculated to the oil port of the oil storage tank.

[0026] The oil vapor of the present invention is first collected and liquefied in an oil storage tank, and the oil vapor that is not collected and liquefied is introduced into an air intake pipe and is introduced into a lower bearing oil storage tank through a flexible metal pipe that is bent into a U-shape in the form of a metal bellows connected to the air intake pipe.

[0027] The metal corrugated tube of the present invention, which is bent into a U-shape, is configured to reduce the flow velocity of the incoming oil vapor and increase the cross-sectional area where the oil vapor is deposited due to the shape of the corrugated tube inside the metal corrugated tube, thereby increasing the collection and liquefaction of the oil vapor.

[0028] The oil supplied from the oil port of the present invention flows into the space between the lower shaft and the labyrinth seal, flows along the oil circulation path to lubricate the guide bearing, and then the high-temperature oil is cooled in a water cooler and flows back to the oil port in a recirculation process.

[0029] The present invention is configured such that oil vapor flows into the oil storage tank of the lower bearing through a metal corrugated pipe connected to an air intake pipe installed in four directions on the motor frame. Effects of the invention

[0031] The present invention provides a vapor capture device that captures and liquefies oil vapor in the oil storage tank of a nuclear reactor coolant pump motor, which can improve the reliability and safety of the motor.

[0032] Furthermore, the collection device of the present invention, which collects and liquefies oil vapor, has the effect of preventing motor fires inside the reactor containment building during normal operation, reducing maintenance time and costs caused by motor oil leakage, and preventing radiation exposure to workers that may occur during motor oil replenishment. Brief explanation of the drawing

[0034] Figure 1 is a reactor cooling system diagram including a reactor coolant pump and an electric motor for removing heat from the reactor core and forcing the circulation of coolant. Figure 2 is a cross-sectional view of a reactor coolant pump motor. Figure 3 shows the path through which oil circulates for the upper bearing of the electric motor and bearing lubrication. Figure 4 shows the path through which oil circulates for the motor lower bearing and bearing lubrication. Figure 5 illustrates a configuration in which an oil deflector is provided in the lower bearing oil reservoir. Figure 6 illustrates the configuration of an air intake pipe for collecting oil vapor and increasing air intake. Specific details for implementing the invention

[0035] The reactor coolant pump motor provides power to the pump and supplies a sufficient forced circulation flow rate to the reactor coolant system to properly remove heat generated in the reactor core.

[0036] A reactor coolant pump motor equipped with an inertia wheel provides sufficient inertia slow flow rate to adequately cool the reactor core when the power supply is lost.

[0037] The reactor coolant pump motor is a device designed to support the rotor load and convert electrical energy generated in the stator into mechanical energy to transmit to the rotor; bearings are used at the top and bottom of the motor, and lubricating oil is supplied to the motor bearings to minimize mechanical friction and losses.

[0038] Hereinafter, the bearing oil vapor capture device for a nuclear reactor coolant pump motor according to the present invention will be described in more detail with reference to the attached drawings.

[0039] Figure 1 is a reactor cooling system diagram including a reactor coolant pump and an electric motor for removing heat from the reactor core and forcing the circulation of coolant.

[0040] The reactor coolant pump motor provides power to the pump to provide a sufficient forced circulation flow rate to the reactor coolant system in order to properly remove heat generated in the reactor core.

[0041] In addition, the reactor coolant pump motor equipped with an inertia wheel provides sufficient inertia slow flow rate to adequately cool the reactor core when the power supply is lost.

[0042] The reactor coolant pump is an upright, single-stage pump that is an electric motor-driven centrifugal pump that sucks in from the bottom and discharges horizontally.

[0043] The reactor coolant pump motor is an AC induction motor composed of a stator, a rotor, and bearings.

[0044] Figure 2 is a cross-sectional view of a reactor coolant pump motor.

[0045] The reactor coolant pump motor consists of a stator, a rotor, an upper bearing, and a lower bearing.

[0046] The motor stator generates a rotating magnetic field when current flows through the stator windings by the power supply, and its main components consist of an iron core, an insulation system, and a frame.

[0047] The motor rotor transmits power to the pump using the torque generated as current induced by the rotating magnetic field generated in the stator flows through the rotor bars.

[0048] The main components of the rotor consist of a shaft, iron core, rotor bar, end ring, inertia wheel, etc.

[0049] An electric motor bearing is a component that supports the rotor and connects the stationary part, the stator, with the rotating part, the rotor.

[0050] The reactor coolant pump motor is a device designed to support the rotor load and convert electrical energy generated in the stator into mechanical energy to transmit to the rotor; upper bearings are used at the top of the motor, and lower bearings are used at the bottom.

[0051] The upper bearing consists of a guide bearing that supports radial loads and a thrust bearing that supports axial loads, and the lower bearing consists only of a guide bearing that supports radial loads.

[0052] Electric motor bearings are oil-lubricated to minimize mechanical friction and losses.

[0053] Figure 3 shows the path through which oil circulates for the upper bearing of the electric motor and bearing lubrication.

[0054] The upper shaft (120), guide bearing (130), and thrust bearing (140) are installed on the upper bearing (100) of the motor.

[0055] An oil reservoir is defined as the space surrounding a bearing assembly that contains oil for lubrication purposes.

[0056] The high-temperature oil circulating inside the oil storage tank (150) of the upper bearing (100) of the motor is cooled by the water cooler (180) by the cooling water supplied through the cooling water supply unit (170) and flows into the oil pot (110).

[0057] The oil supplied from the oil port (110) flows into the space between the upper shaft (120) and the labyrinth seal, flows along the oil circulation path (indicated by the arrow) (160) to lubricate the guide bearing (130), and then the high-temperature oil is cooled in the water cooler (180) and flows back to the oil port (110) in a recirculation process.

[0058] In the upper bearing (100) of the motor, oil flowing along the oil circulation path (160) between the upper shaft (120), the guide bearing (130), and the thrust bearing (140) performs normal lubrication.

[0059] Figure 4 shows the path through which oil circulates for the motor lower bearing and bearing lubrication.

[0060] The lower shaft (220) and guide bearing (230) are installed in the lower bearing (200) of the motor.

[0061] An air intake pipe (400) for reducing pressure and an atmospheric pressure compensation pipe (500) for preventing a decrease in negative pressure in the oil storage tank are installed in the lubricating oil storage tank (250) of the lower bearing (200) of the motor.

[0062] The high-temperature oil circulating inside the oil storage tank (250) of the lower bearing (200) of the motor is cooled by the water cooler (280) by the cooling water supplied through the cooling water supply unit (270) and flows into the oil pot (210).

[0063] The oil supplied from the oil port (210) flows into the space between the lower shaft (220) and the labyrinth seal, flows along the oil circulation path (arrow) (260) to lubricate the guide bearing (230), and then the high-temperature oil is cooled in the water cooler (280) and flows back to the oil port (210) in a recirculation process.

[0064] The gap between the guide bearing (230) and the shaft (220) forms a normal oil passage where oil normally performs lubrication.

[0065] Oil leakage mostly occurs in the lower bearing (200) through the gap between the shaft (220) and the bearing (230) where oil mist vaporized due to the high-speed rotation of the electric motor passes through the oil leakage path (300).

[0066] Although a labyrinth seal is installed between the shaft and the bearing housing to prevent oil leakage, vaporized oil passes through the gap between the shaft and the bearing housing and oil leakage occurs through the oil leakage path (300).

[0067] The cause of the oil leak is that as the electric motor rotates, oil vapor is generated as oil flows through the oil leak passage (300), which is the gap between the lower guide bearing (230) and the shaft (220) at a high temperature, and the oil vapor leaks out due to the pressure difference.

[0068] Since the internal pressure of the lower bearing oil reservoir is greater than the internal pressure of the motor, vaporized oil leaks into the motor, where the pressure is relatively lower, through the gap between the shaft (220) and the bearing (230).

[0069] In addition, if operated for a long period, oil vapor causes oil to accumulate in the air breather pipeline (400), blocking air intake and increasing the pressure inside the oil storage tank, resulting in continuous oil leakage.

[0070] Oil leakage from the lower bearing (200) of the standard reactor coolant pump motor is caused by the difference between the internal pressure and the external pressure of the oil storage tank that occurs during motor rotation.

[0071] After lubricating the lower guide bearing (230), the vaporized oil leaks through the gap between the shaft (220) and the guide bearing (230), and at this time, the vaporized oil is in the form of oil mist.

[0072] To prevent oil leakage from the lower bearing (200) of the standard reactor coolant pump motor, it is very important to collect the oil vapor generated during the lubrication process of the guide bearing (230) in the oil storage tank and to reduce the pressure difference by reducing the internal pressure of the oil storage tank.

[0073] Oil mist is collected from the oil storage tank to reduce the pressure difference by decreasing the internal pressure of the oil storage tank.

[0074] Oil vapor refers to a state in which oil droplets vaporize and spray particles with a size of 1 to 10 µm are distributed in the air.

[0075] If there is a capture device capable of capturing and suppressing oil vapors floating in the oil storage tank in the first stage, it is possible to capture the oil vapors and prevent them from leaking to the outside.

[0076] In addition, the pressure difference inside the oil storage tank is reduced by capturing oil vapor and increasing air intake through the air breather pipeline.

[0077] A large amount of oil vapor is reduced in the oil vapor capture device of the oil storage tank in the first stage, but some of it flows into the air intake pipe.

[0078] Therefore, oil vapor entering the air intake pipe is secondarily blocked at the flexible metal pipe.

[0079] To reduce the internal pressure difference of the oil storage tank, the air intake flow rate can be increased up to four times.

[0080] The configuration for collecting oil vapor in an oil storage tank and increasing oil vapor collection and air intake in an air intake pipe according to the present invention is as follows.

[0081] Figure 5 illustrates a configuration in which an oil deflector is provided in the lower bearing oil reservoir.

[0082] The lower bearing (200) of the motor is equipped with a shaft (220), a guide bearing (230), an oil reservoir (250), an air intake pipe (400), and an atmospheric pressure compensation pipe (500).

[0083] An oil deflector (600) in the shape of a tooth, which collects oil vapor and is a device for minimizing oil leakage that occurs during the operation of the lubrication device, is provided on the upper part of the oil port (210).

[0084] An oil deflector (600) is installed in contact with the passage through which the cooling water flows in from the cooling water supply unit (270), so that the oil deflector (600) that collects oil vapor maintains a low temperature state.

[0085] The high-temperature oil passing through the lower guide bearing (230) vaporizes and becomes an oil mist.

[0086] That is, due to the difference between the internal and external pressures of the oil reservoir that occurs during the rotational operation of the electric motor, oil mist vaporized after lubricating the lower guide bearing leaks through the oil leakage path (300) in the gap between the shaft (220) and the bearing (230).

[0087] Therefore, to collect oil vapor, an oil deflector (600) is installed on the upper part of the oil storage tank (250) to collect the oil vapor and liquefy it.

[0088] The principle of collecting oil vapor has a mechanism in which high-temperature oil vapor is liquefied in an oil deflector (600) with a relatively low temperature and circulated to an oil storage tank.

[0089] The oil deflector is a device designed to minimize oil leakage from the lower bearing during electric motor operation. It is installed on the side of the bearing and the outer side of the rotor to prevent the intrusion of atmospheric foreign substances and fine dust drawn in through the air intake pipe and atmospheric pressure compensation pipe into the inside of the oil reservoir.

[0090] Figure 6 illustrates the configuration of an air intake pipe for collecting oil vapor and increasing air intake.

[0091] The oil vapor is collected and liquefied in the oil storage tank in the first stage, but some of it flows into the air intake pipe (400).

[0092] A flexible metal pipe (410) in the form of a metal bellows is bent into a U-shape to reduce the flow velocity of the oil vapor, and the interior of the U-shaped metal pipe increases the cross-sectional area where the oil vapor is deposited, thereby increasing the collection and liquefaction of the oil vapor.

[0093] That is, the metal corrugated pipe (410) bent into a U-shape reduces the flow velocity of the incoming oil vapor, and the cross-sectional area where the oil vapor is deposited increases due to the corrugated pipe shape inside the metal corrugated pipe (410), thereby increasing the collection and liquefaction of the oil vapor.

[0094] Oil vapor flows into the oil storage tank (250) of the lower bearing (200) through a metal corrugated pipe (410) connected to an air intake pipe (400) installed in four directions on the motor frame (290).

[0095] The configuration involves heavy oil vapor deposition and liquefaction in low-temperature metal corrugated pipes, while light air flows into the oil storage tank.

[0096] The present invention provides a vapor capture device that captures and liquefies oil vapor in the oil storage tank of a nuclear reactor coolant pump motor, which has the effect of increasing the reliability and safety of the motor.

[0097] The vapor capture device of the present invention has the effect of preventing motor fires inside the reactor containment building during normal operation, reducing maintenance time and costs caused by motor oil leakage, and preventing radiation exposure to workers that may occur when replenishing motor oil.

[0098] Although the present invention has been described in detail through representative embodiments above, those skilled in the art will understand that various modifications can be made to the above-described embodiments within the scope of the present invention.

[0099] Therefore, the scope of the rights of the present invention should not be limited to the described embodiments, but should be determined by the claims set forth below as well as all modifications or variations derived from the claims and equivalent concepts. Explanation of the symbols

[0101] 00: Upper bearing 110: Oil port 120: Upper shaft 130: Guide bearing 140: Thrust bearing 150: Oil storage tank 160: Oil circulation route 170: Coolant supply unit 180: Water cooler 200: Lower bearing 210: Oil port 220: Lower shaft 230: Guide bearing 250: Oil storage tank 260: Oil circulation route 270: Coolant supply unit 280: Water cooler 290: Motor Frame 400: Air intake pipe 410: Metal corrugated tube 500: Atmospheric pressure compensation piping 600: Oil Deflector

Claims

Claim 1 In a bearing oil vapor collection device for a nuclear reactor coolant pump motor, the coolant pump motor includes a stator, a rotor, an upper bearing, and a lower bearing; a lower shaft (220) and a guide bearing (230) are installed on the motor lower bearing (200); high-temperature oil circulating inside the oil storage tank (250) of the motor lower bearing (200) is cooled by a water cooler (280) and flows into an oil port (210); the oil supplied from the oil port (210) flows into the space between the lower shaft (220) and the labyrinth seal to lubricate the guide bearing (230); an oil deflector (600) for collecting oil vapor is installed on the upper part of the oil port (210); the oil vapor is first collected and liquefied in the oil storage tank (250); and the oil vapor that is collected but not liquefied A bearing oil vapor collection device for a reactor coolant pump motor, characterized by being introduced into an air intake pipe (400) and into a lower bearing oil storage tank (250) through a metal bellows-shaped flexible metal pipe (410) connected to the air intake pipe (400). Claim 2 A bearing oil vapor collection device for a reactor coolant pump motor, characterized in that, in claim 1, an air intake pipe (400) for reducing pressure and an atmospheric pressure compensation pipe (500) for preventing negative pressure reduction in the oil storage tank are installed in the lubricating oil storage tank (250) of the lower bearing (200) of the motor. Claim 3 A bearing oil vapor collection device for a reactor coolant pump motor, characterized in that, in claim 1, the high-temperature oil vapor passing through the lower guide bearing (230) is liquefied in a low-temperature oil deflector (600) installed in contact with the passage through which coolant flows in from the coolant supply unit (270) and is recirculated to the oil port (210) of the oil storage tank. Claim 4 delete Claim 5 A bearing oil vapor collection device for a reactor coolant pump motor, characterized in that, in claim 1, the metal corrugated tube (410) bent into a U-shape reduces the flow velocity of the incoming oil vapor and increases the cross-sectional area where the oil vapor is deposited due to the corrugated tube shape inside the metal corrugated tube (410), thereby increasing oil vapor collection and liquefaction. Claim 6 A bearing oil vapor collection device for a reactor coolant pump motor, characterized in that, in any one of claims 1 to 3 and 5, the oil supplied from the oil port (210) flows into the space between the lower shaft (220) and the labyrinth seal, flows along the oil circulation path (260) to lubricate the guide bearing (230), and then the high-temperature oil is cooled in the water cooler (280) and flows back to the oil port (210) in a recirculation process. Claim 7 In a bearing oil vapor collection device for a reactor coolant pump motor, the coolant pump motor comprises a stator, a rotor, an upper bearing, and a lower bearing; a lower shaft (220) and a guide bearing (230) are installed in the motor lower bearing (200); oil circulating inside the oil storage tank (250) of the motor lower bearing (200) flows into an oil port (210); oil supplied from the oil port (210) flows into the space between the lower shaft (220) and the labyrinth seal to lubricate the guide bearing (230); an oil deflector (600) for collecting oil vapor is installed above the oil port (210); and oil vapor is transferred to the oil of the lower bearing (200) through a metal corrugated pipe (410) connected to an air intake pipe (400) installed in four directions on the motor frame (290). A bearing oil vapor collection device for a reactor coolant pump motor, characterized by being fed into a storage tank (250).

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