CN203272221U - Fluid dynamic pressure three-level mechanical sealing device of reactor coolant pump - Google Patents

Abstract

The utility model relates to a three-stage fluid dynamic pressure mechanical seal device of a reactor coolant pump. The mechanical seals of each stage have the same structure and function and are convenient for mutual replacement. The combined use of four throttles makes the three-stage fluid dynamic pressure The mechanical seal forms six functional failure modes. In the case of a certain level of mechanical seal damage, the nuclear main pump can still run in a short period of time, avoiding the instantaneous power failure of the nuclear power plant, which not only enhances the maintenance of the nuclear main pump, but also reduces Economic loss of nuclear power plants.

Description

Reactor coolant pump fluid dynamic pressure three-stage mechanical seal device

Technical field: The utility model relates to a reactor coolant pump fluid dynamic pressure three-stage mechanical seal device.

Background technology: The reactor coolant pump fluid dynamic pressure three-stage mechanical seal device is the core and important part of the reactor coolant pump structure, which directly affects whether the nuclear main pump can operate safely and reliably in a nuclear power plant. If the seal leaks, it will directly lead to the shutdown of the reactor, which will bring huge economic losses to the nuclear power plant, and even cause environmental radiation pollution in severe cases. At present, the nuclear main pump is the only equipment in the nuclear island of my country's nuclear power plants that has not been fully localized. The nuclear main pump manufacturing market has been monopolized by developed countries such as Europe, America and Japan for a long time. Due to its technological advancement, my country is in a passive state in the design and manufacture of nuclear main pumps and has always relied on imports.

SUMMARY OF THE INVENTION: The purpose of this utility model is to disclose a hydrodynamic pressure three-stage mechanical seal device for reactor coolant pumps. The technical solution of the utility model is: a reactor coolant pump fluid dynamic pressure three-stage mechanical seal device, which is installed in series with the same three-stage mechanical seal, and the static ring assembly (2-2) is installed to the dynamic ring assembly (2-1 ) upper position, the sealing surfaces of the two are in contact to form a mechanical seal (2), the moving ring (2-1) is axially connected to the No. 1 sealing sleeve (1) through a cylindrical pin, and the No. The outside of the mechanical seal (2) is pressed tightly by the No. 1 guide ring (4), and the groove of the No. 2 seal shaft sleeve (7) is set together with the flange of the No. 1 seal shaft sleeve (1) and is secured by a two-petal clamp ring ( 6) Locking to form a joint body, the same mechanical seal (2) is installed on the No. 2 sealing bushing (7) through a cylindrical pin, and the No. Lock the hexagon head screw (8), and install the joints of the first restrictor (10) and the second restrictor (11) to the lower axial hole and upper axial hole of the second outer ring (9) respectively Inside, locked by hexagonal head screws, the joints of the third restrictor (14) and the fourth restrictor (15) are installed on the radial holes at different angles on the second outer ring (9), and the hexagonal The No. 2 guide ring (12) is pressed onto the No. 2 outer ring (9) and locked by the hexagon socket head screw (13) to form a joint. The groove of the tertiary seal bushing (16) and the The flange sleeve of the secondary seal (7) is pressed tightly, the same mechanical seal (2) is installed and fixed in the tertiary seal sleeve (16) through cylindrical pins, and the No. 3 outer ring (17) is installed with the No. 2 guide ring ( 12) and compressed by the No. 3 guide ring (18) to form the third-stage sealing cavity.

The beneficial effects of the utility model are:

(1) The utility model is composed of three stages of the same mechanical seal installed in series, and the system pressure is reduced step by step through four restrictors, and finally realizes the sealed controllable low pressure "zero leakage" (zero leakage refers to No external leakage of reactor coolant), to ensure the safe and reliable operation of nuclear main pumps, and to prevent environmental nuclear radiation pollution.

(2) The mechanical seal friction pair consists of a moving ring and a static ring. Among them, the moving ring rotates with the sealing sleeve. The end face of the static ring is designed as a special shallow groove corrugated shape, and a liquid film is formed between the sealing friction pairs during operation, and it is in a stable state to avoid dry friction and reduce the life of the mechanical seal.

(3) In terms of structure, the first-stage seal and the second-stage seal realize the overall connection of the two-stage seal through the two-petal clamp ring (6), which is convenient for overall disassembly and assembly, and greatly saves disassembly and assembly time.

(4) The series structure of the three-stage mechanical seal device and four restrictors can form six functional failure modes. When a certain mechanical seal is damaged, it can ensure that the main pump can still run safely within a certain period of time, which is helpful for reactor cooling. The agent pump is safely shut down and maintained.

Explanation of principle of non-leakage principle of reactor coolant pump fluid dynamic pressure three-stage mechanical seal device:

The three-stage fluid dynamic pressure mechanical seal in series adopts the same three-stage fluid dynamic pressure mechanical seal to share the sealing pressure. The high-pressure injection water (higher than the pressure in the reactor coolant pump chamber) from the top charge pump (another device of the nuclear power plant) enters the first-stage sealed chamber, and then is throttled by two restrictors respectively, and then enters the first-stage seal chamber respectively. Secondary and tertiary mechanical seal chambers. The pressure entering the first-stage mechanical seal chamber is 159 bar, the pressure entering the second-stage mechanical seal chamber is 106 bar, and the pressure entering the third-stage mechanical seal chamber is 53 bar. The flow rate of cooling water entering each mechanical seal is 600L/h. Make each stage of the three-stage series mechanical seal have the same working condition. The controllable leakage of each mechanical seal is 5L/h. In the initial stage, each stage of the three-stage hydrodynamic mechanical seal core is designed to withstand the full system pressure of 159bar, but when the main pump is running normally, each stage only bears 1/3 of the full system pressure, about 53bar.

The structural features of the reactor coolant pump fluid dynamic pressure three-stage mechanical seal device are non-contact, balanced, static, and multi-spring. The end face of the rotating ring is provided with multiple large corrugations, and the inner diameter of the static ring is additionally supported by a steel ring. The first two stages of the three-stage series mechanical seal are assembled together, and the third stage is a separate cartridge. The interface size between each stage and the pump body increases step by step, and the interface size with the pump shaft decreases step by step, so that Make installation more convenient and faster.

The primary loop system pressure of the nuclear power plant is 152bar. Under normal operating conditions of the main pump, the system pressure is reduced to atmospheric pressure through the three-stage series mechanical seal.

After the high-pressure shaft seal injection water with a flow rate of 2000L/h and a pressure of 159bar provided by the centrifugal charging pump of the RCV (chemical and volume control) system of the nuclear power plant enters the shaft seal system, the pressure of the shaft seal injection water is higher than that of the primary circuit System pressure, so the injection water is divided into three flow directions. One flow direction enters the primary circuit system with a flow rate of 800L/h to the water-lubricated radial bearing to prevent the reactor coolant from entering the sealed cavity. The other two flow directions enter the second-stage mechanical seal and the third-stage mechanical seal with a flow rate of 600L/h respectively, and their pressures are 106bar and 53bar respectively. The diverted flow is accomplished by a total of four restrictors: the first restrictor, the second restrictor, the third restrictor and the fourth restrictor. When the pressure drop of the injected water through the first restrictor is 106bar, the pressure difference between the front and rear ends of the first-stage mechanical seal is 53bar. At this time, the leakage of the first-stage mechanical seal surface is 5L/h, which is mainly due to the lubrication of the sealing surface and cooling effect. Before the leakage flow of 5L/h flows to the second-stage mechanical seal, the pressure has dropped to 106bar. The same principle, through the same mechanical seal, under the joint action of the second and third mechanical seals and the restrictor, the pressure of the water injected into the high-pressure seal with a pressure of 159bar is also reduced to 2-3bar, and injected into the chemical and volume control system of the nuclear power plant respectively ( RCV), and the 5L/h leakage from the sealing surface of the third-stage mechanical seal flows into the low-pressure leakage system.

The successful development of the three-stage hydrodynamic mechanical seal will make a big step forward in the localization of nuclear main pumps in my country, get rid of the embarrassing situation of being restricted by foreign imports, fill in the blank history that the country has never realized the localization of nuclear main pumps, and replace Import, save foreign exchange, and also prepare for the competition of national nuclear power in the international market and export to third parties.

Description of drawings

Figure 1 is a cross-sectional view of the reactor coolant pump fluid dynamic pressure three-stage mechanical seal device

Figure 2 is an enlarged cross-sectional view of the mechanical seal structure

Figure 3 is the first restrictor

Figure 4 is the second restrictor

Figure 5 is the third restrictor

Figure 6 is the fourth restrictor

Detailed ways

As shown in Figure 1, the reactor coolant pump fluid dynamic pressure three-stage mechanical seal device is installed in series with the same three-stage mechanical seal, as shown in Figure 2, the static ring assembly 2-2 is installed on the upper position of the dynamic ring assembly 2-1, The sealing surfaces of the two are in contact to form a mechanical seal 2. The moving ring 2-1 is axially connected to the No. 1 sealing sleeve 1 through a cylindrical pin. The No. 1 outer ring 3 is installed outside the mechanical seal 2 and is guided by the No. 1 guide ring 4 Compression, the groove of the second seal sleeve 7 is set together with the flange of the first seal sleeve 1 and locked by the two-petal clamp ring 6 to form a joint body, the same mechanical seal 2 is installed to the second seal through a cylindrical pin On the shaft sleeve 7, the No. 2 outer ring 9 is pressed onto the No. 1 guide ring 4 and locked by the hexagon head screw 8. As shown in Fig. 3 and Fig. 4, the first restrictor 10 and the second restrictor The joints of the device 11 are respectively installed in the lower axial hole and the upper axial hole of the second outer ring 9, and are locked by hexagon head screws, as shown in Figure 4 and Figure 5, the third restrictor 14 and the fourth throttle The joints of the flow device 15 are installed on the radial holes at different angles on the No. 2 outer ring 9, and are locked by hexagon head screws. The No. 2 guide ring 12 is loaded on the No. 13 is locked to form a joint body, the groove of the third-stage seal shaft sleeve 16 is pressed tightly with the flange of the second-stage seal shaft sleeve 7, and the same mechanical seal 2 is installed and fixed in the third-stage seal shaft sleeve 16 through cylindrical pins. The outer ring 17 is installed on the No. 2 guide ring 12 and compressed by the No. 3 guide ring 18 to form a third-stage sealed chamber.

The utility model adopts the same three-level mechanical seal 2 to be respectively installed on the No. 1 sealing shaft sleeve 1, the No. 2 sealing shaft sleeve 7, and the third-level sealing shaft sleeve 16, and is connected with the first throttle 10 and the second throttle. 11. The third restrictor 14 and the fourth restrictor 15 form six functional failure modes to ensure that the nuclear main pump can still operate in a short period of time when a certain level of mechanical seal is damaged, and to buy time for the maintenance of the nuclear main pump. Reduce the economic loss of nuclear power plants.

The mechanical seals of each stage of the utility model have the same structure and function and can be replaced with each other, which is beneficial to the maintenance of the nuclear main pump and has a wide application range.

Claims (1)

1. A three-stage hydrodynamic mechanical seal device for reactor coolant pumps, characterized in that: the three-stage mechanical seals are installed in series, and the static ring assembly (2-2) is installed on the upper position of the dynamic ring assembly (2-1) , the sealing surfaces of the two are in contact to form a mechanical seal (2), the moving ring (2-1) is axially connected to the No. (2) The outside is pressed by the No. 1 guide ring (4), and the groove of the No. 2 sealing bushing (7) is set together with the flange of the No. 1 sealing bushing (1) and is secured by a two-petal clamp ring (6). Lock to form a joint body. The same mechanical seal (2) is installed on the No. 2 seal sleeve (7) through a cylindrical pin, and the No. 2 outer ring (9) is pressed onto the No. 1 guide ring (4). The screws (8) are locked tightly, and the joints of the first restrictor (10) and the second restrictor (11) are respectively installed in the lower axial hole and the upper axial hole of the second outer ring (9). Locked by hexagon head screws, the joints of the third restrictor (14) and the fourth restrictor (15) are installed on the radial holes at different angles on the second outer ring (9), and fixed by hexagon head screws Locking, the second guide ring (12) is pressed onto the second outer ring (9) and locked by the hexagon socket head screw (13) to form a joint body, the groove of the third-stage seal shaft sleeve (16) and the second-stage The sealing sleeve (7) is pressed tightly by the flange set, the same mechanical seal (2) is installed and fixed in the third-stage sealing sleeve (16) through cylindrical pins, and the third outer ring (17) is installed with the second guide ring (12) and is compressed by the No. 3 guide ring (18) to form a third-stage sealed chamber.

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