CN113339317A - Three-stage fluid dynamic pressure type nuclear main pump mechanical seal pressure dividing device - Google Patents
Three-stage fluid dynamic pressure type nuclear main pump mechanical seal pressure dividing device Download PDFInfo
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- CN113339317A CN113339317A CN202110357600.3A CN202110357600A CN113339317A CN 113339317 A CN113339317 A CN 113339317A CN 202110357600 A CN202110357600 A CN 202110357600A CN 113339317 A CN113339317 A CN 113339317A
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- 239000012530 fluid Substances 0.000 title claims abstract description 15
- 238000009826 distribution Methods 0.000 claims abstract description 20
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 17
- 238000002347 injection Methods 0.000 claims description 11
- 239000007924 injection Substances 0.000 claims description 11
- 238000003825 pressing Methods 0.000 claims description 5
- 238000012360 testing method Methods 0.000 claims description 5
- 238000004804 winding Methods 0.000 claims description 5
- 238000000034 method Methods 0.000 claims description 4
- 238000004806 packaging method and process Methods 0.000 claims description 4
- 239000000463 material Substances 0.000 claims description 3
- 238000005259 measurement Methods 0.000 claims description 3
- 230000007246 mechanism Effects 0.000 claims description 3
- 238000003466 welding Methods 0.000 claims description 2
- 230000003068 static effect Effects 0.000 description 13
- 238000007789 sealing Methods 0.000 description 10
- 230000008901 benefit Effects 0.000 description 7
- 238000012423 maintenance Methods 0.000 description 4
- 239000002826 coolant Substances 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical group [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 230000006835 compression Effects 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 239000002354 radioactive wastewater Substances 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000001050 lubricating effect Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
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Classifications
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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
- F04D29/086—Sealings especially adapted for liquid pumps
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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
- F04D15/00—Control, e.g. regulation, of pumps, pumping installations or systems
- F04D15/0088—Testing machines
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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
- F04D29/106—Shaft sealings especially adapted for liquid pumps
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Sealing (AREA)
- Structures Of Non-Positive Displacement Pumps (AREA)
Abstract
The invention particularly relates to a three-level fluid dynamic pressure nuclear main pump mechanical seal pressure dividing device which comprises a first restrictor, a second restrictor, a third restrictor and a fourth restrictor, wherein the first restrictor and the third restrictor are respectively connected with a second-level mechanical seal cavity, and the second restrictor and the fourth restrictor are respectively connected with a third-level mechanical seal cavity, and the three-level fluid dynamic pressure nuclear main pump mechanical seal pressure dividing device is characterized in that the first restrictor, the second restrictor, the third restrictor and the fourth restrictor distribute the pressure of a first-level mechanical seal cavity, the pressure of a second-level mechanical seal cavity and the pressure of a third-level mechanical seal cavity into 4: 4: 2. the mechanical seal pressure dividing device for the three-stage hydrodynamic nuclear main pump reduces the pressure borne by the third-stage seal by adjusting the pressure distribution proportion of the three-stage hydrodynamic mechanical seal so as to reduce the flow rate of low-pressure leakage flow and alleviate the problem of high low-pressure leakage flow.
Description
Technical Field
The invention relates to the technical field of mechanical seal, in particular to a three-stage hydrodynamic pressure type mechanical seal pressure dividing device for a nuclear main pump.
Background
The nuclear power plant reactor main coolant pump (hereinafter referred to as a nuclear main pump) provides a driving pressure head for the nuclear power plant reactor main coolant, sends heat generated by the nuclear power plant reactor to an evaporator, and finally sends the heat back to the nuclear power plant reactor by the nuclear main pump for circulation, and is one of key equipment of the nuclear power plant.
The three-stage fluid dynamic pressure mechanical seal is the most central important component in the nuclear main pump structure, and is directly related to whether the nuclear main pump can safely and reliably run in a nuclear power station. If the seal leaks, the reactor is directly shut down, huge economic loss is brought to the nuclear power station, and environmental radiation pollution is caused in serious cases.
Referring to fig. 1, the three-stage hydrodynamic mechanical seal is structurally characterized by non-contact, balance, static and multi-spring, a plurality of large corrugations are arranged on the end face of a dynamic ring, and a support ring is additionally arranged on the inner diameter of a static ring. The first two stages of the three-stage fluid dynamic pressure mechanical seal are assembled together, the third stage is an independent assembled type, each stage is gradually increased with the interface size of the pump body and gradually reduced with the interface size of the pump shaft, and therefore the mounting is more convenient and rapid.
The dynamic pressure shaft seal has similar three-stage structure and is installed on the shaft in series. In each of these stages, as shown, the first sleeve 44, the second sleeve 50 and the third sleeve 55 are all directly mounted on the shaft 28, with each sleeve being driven by a fork lug and groove. For example, in stage 1, the rotating ring 248.8 is mounted on the sleeve and is driven into position by member pin 248.14. The sealing movable ring is embedded and integrated by an inner lantern ring 248.9, a graphite ring 248.13 and a movable ring outer lantern ring 248.6. The seal rotating ring is clamped on the rotating ring seat 248.8 through a rotating ring clamp ring 248.7. The static ring is formed by inlaying a static ring seat 248.1, a hard alloy ring 248.12 and a static ring outer sleeve 248.5, and the static ring is pressed and mounted on the static ring seat 248.1 by a static ring pressing ring 248.2 to form a static ring assembly. The stationary ring assembly is sleeved on the stationary ring guide ring 43. The stationary ring guide ring 43 is fixedly connected with the sealing cavity in a pressing way and keeps stationary.
When the device works, the movable ring assembly rotates relative to the static ring assembly under the driving of the shaft and the shaft sleeve, and the fluid dynamic pressure groove is formed in the end face of the static ring to form opening force, so that the end face of the movable ring is disengaged.
The pressure of a primary loop system of the nuclear power station is 15.4 MPa. Under the normal operation working condition of the nuclear main pump, the system pressure is reduced to the atmospheric pressure through the three-stage fluid dynamic pressure mechanical seal. The three-stage fluid dynamic pressure mechanical seal is formed by distributing the sealing pressure by three stages of same sealing pairs, each stage can bear full pressure, the distribution of the sealing pressure of the three stages is 3:3:3, namely each stage bears about 5-5.2MPa of pressure, and the leakage rate of each stage is about 5-15L/h.
After high-pressure shaft seal injection water with the flow rate of 1920L/h and the pressure of 15.4MPa provided by a centrifugal charging pump of an RCV system of a nuclear power plant enters a shaft seal system, the pressure of the shaft seal injection water is higher than that of a primary circuit system, so that the injection water is divided into three flow directions. A flow 1115L/h to water lubricated journal bearings into a loop system prevents reactor coolant from entering the mechanical seal chamber. The other two flow directions respectively enter a secondary mechanical seal and a tertiary mechanical seal at the flow rate of 400L/h, and the pressures of the two flow directions are respectively 10.4MPa and 5.4 MPa.
This split flow is accomplished by 4 chokes 1, 2, 3, 4. When the pressure of injected water passing through the restrictor 1 is reduced to 10.3MPa, the pressure difference between the front end and the rear end of the first-stage shaft seal is 5.1MPa, the leakage rate of the first-stage shaft seal surface is 5-15L/h, and the leakage rate is mainly the lubricating and heat-radiating effect of the seal surface. The 5-15L/h leakage flow rate is reduced to 10.3MPa before flowing to the second stage shaft seal. On the same principle, under the combined action of the 2-stage and 3-stage seals and the throttler, the pressure of high-pressure seal injection water with the pressure of 15.4MPa is also reduced to 0.2 MPa-0.3 MPa, the high-pressure seal injection water is respectively injected into an RCV system of the nuclear power station, and 5-15L/h leakage flow leaked from a third-stage shaft seal sealing surface flows into a low-pressure leakage system.
Due to the design reason, the time is as short as 5 years since the hydrodynamic pressure type nuclear main pump mechanical seal is self-debugged, and as many as 20 times of high-pressure leakage flow events of the nuclear main pump mechanical seal occur, the shutdown and shutdown maintenance or major maintenance main line delay of a nuclear power station is caused, the nuclear safety and the economic benefit of the nuclear power station are seriously influenced, and the problem is solved to be a very urgent task for ensuring the safe and stable operation of the main pump.
Disclosure of Invention
Therefore, it is necessary to provide a hydrodynamic pressure-dividing device for a mechanical seal of a nuclear main pump, which reduces the pressure borne by the third-stage seal by adjusting the pressure distribution ratio of the three-stage hydrodynamic pressure-dividing device, so as to reduce the flow rate of the low-pressure leakage flow and alleviate the problem of high low-pressure leakage flow, in order to solve the problem of high low-pressure leakage flow of the conventional hydrodynamic pressure-dividing device for a mechanical seal of a nuclear main pump.
In order to achieve the above purpose, the invention provides the following technical scheme:
the utility model provides a tertiary fluid dynamic pressure nuclear main pump mechanical seal bleeder mechanism, includes No. one throttle, No. two throttles, No. three throttles and No. four throttles, No. one throttle and No. three throttles are connected with second grade mechanical seal chamber respectively, No. two throttles and No. four throttles are connected with tertiary mechanical seal chamber respectively, its characterized in that, No. one throttle, No. two throttles, No. three throttles and No. four throttles are 4 with the pressure distribution in one-level mechanical seal chamber, second grade mechanical seal chamber and tertiary mechanical seal chamber: 4: 2.
further, the restrictor comprises a restrictor joint and a restrictor main body, wherein the restrictor joint is welded at one end of the restrictor main body, the restrictor is inserted into an injection hole of the mechanical seal cavity, and then the restrictor joint groove is clamped through pin positioning to realize connection of the restrictor and the mechanical seal cavity.
Further, the throttle body is prepared by the following method: and winding the pipeline with enough length on a special tool for several turns to obtain the throttle body.
Furthermore, the pressure distribution of the primary mechanical seal cavity, the secondary mechanical seal cavity and the tertiary mechanical seal cavity is realized by adjusting the sizes of the first restrictor, the second restrictor, the third restrictor and the fourth restrictor, the change amount of the mechanical seal of the nuclear main pump is small, but the low-pressure leakage flow can be obviously reduced, and better benefits are obtained.
Further, the pressure of the three-level mechanical sealing cavity is 3-3.1 MPa.
Further, the sizes of the first throttle, the second throttle, the third throttle and the fourth throttle are obtained through the following steps: 1. the pressure distribution according to one-level mechanical seal cavity, second grade mechanical seal cavity and tertiary mechanical seal cavity is 4: 4: 2, the differential pressure is 6.16MPa, 6.16MPa and 3.08MPa, and the calculated sizes of the first restrictor, the second restrictor, the third restrictor and the fourth restrictor are obtained through a pipe differential pressure model; 2. according to the requirement of 800L/h of output flow of high-pressure shaft seal injected water, the length of the throttle is cut off from long to short on the basis of size calculation, and a special tool is adopted for pressurizing and calibrating until the measured value of a pressure gauge meets the pressure distribution of a first-stage mechanical seal cavity, a second-stage mechanical seal cavity and a third-stage mechanical seal cavity to be 4: 4: 2, the differential pressure is 6.16MPa, 6.16MPa and 3.08 MPa.
Further, the length of the first throttle is 2.04m, the length of the second throttle is 4.1m, the length of the third throttle is 2.96m, and the length of the fourth throttle is 0.92 m.
Further, the first restrictor, the second restrictor, the third restrictor and the fourth restrictor are all made of 304 materials.
The preparation method of the mechanical seal pressure dividing device of the three-level hydrodynamic pressure nuclear main pump comprises the following steps:
1. and winding a pipeline with enough length on a special tool for a plurality of turns, and welding a restrictor joint at one end.
2. According to the pipe network pressure difference model, calculating the pressure distribution of the first-stage mechanical seal cavity, the second-stage mechanical seal cavity and the third-stage mechanical seal cavity to be 4: 4: 2, the lengths of the respective restrictors when the differential pressures were 6.16MPa, and 3.08 MPa.
3. According to the requirement of 800L/h of flow, the length of the throttle is cut off from long to short on the basis of the calculation result, and a special tool is adopted to carry out pressurization and calibration until the measurement value of the pressure gauge meets the pressure difference described in the upper section.
4. Filling the manufactured first throttler, second throttler, third throttler and fourth throttler into the original mechanical seal;
5. and completing the three-level packaging mechanical seal pressing test.
The invention has the beneficial technical effects that:
the mechanical seal pressure dividing device of the three-level fluid dynamic pressure nuclear main pump is applied to mechanical seal of the three-level fluid dynamic pressure nuclear main pump, can solve the problem of high low-pressure leakage flow of the mechanical seal of the three-level fluid dynamic pressure nuclear main pump, can reduce the emission of about 300 tons of radioactive wastewater per year by two units, and has better social benefit and economic benefit; in addition, because the third-stage seal bearing pressure is reduced to 3MPa from 5MPa, the load is reduced, the specific pressure of the end face is reduced by 40%, the reliability and the service life of the third-stage seal are favorably improved, the method has great significance for guaranteeing the safety of the nuclear power station, and has strong practicability and popularization value.
Drawings
FIG. 1 is a schematic view of a mechanical seal structure of a hydrodynamic pressure type nuclear main pump of a conventional nuclear power plant;
FIG. 2 is a schematic diagram of pressure distribution of a three-stage mechanical seal cavity;
FIG. 3 is a schematic view of the pressure division of the restriction;
FIG. 4 is a model of a computation of a choke network;
FIG. 5 is a prior art pressure reduction model of a restrictor network;
FIG. 6 is a pressure reduction model of a restrictor pipe network of the present invention;
FIG. 7 is a schematic view of a throttle body I according to the present invention;
FIG. 8 is a schematic view of a second choke configuration of the present invention;
FIG. 9 is a schematic view of a third choke configuration of the present invention;
fig. 10 is a schematic view of a fourth throttle structure of the present invention.
In the figure, 248.1, a stationary ring seat; 248.2, a static ring compression ring; 248.3, a stationary ring pin; 248.4, a stationary ring spring; 248.5, a static ring outer sleeve ring; 248.6, moving ring outer sleeve ring; 248.7, a dynamic ring compression ring; 248.8, a movable ring seat; 248.9, an inner collar; 248.10, a first O-ring; 248.11, a second O-ring; 248.12, cemented carbide ring; 248.13, graphite ring; 248.14, a rotating ring pin; 248.15, a rotating ring pin; 248.16, support ring; 248.17, a third O-ring; 248.18, a moving ring spring; 28. a shaft; 43. a stationary ring guide ring; 44. a first bushing; 50. a second shaft sleeve; 55. a third shaft sleeve; 57. a stationary ring guide sleeve; 1. injecting water into the high-pressure shaft seal; 2. a lower guide bearing; 3. a first throttling device; 4. a second throttling device; 5. a third throttling device; 6. a fourth throttler; 7. a high pressure leak system; 8. a low pressure leak system; 9. a primary mechanical seal cavity; 10. a secondary mechanical seal cavity; 11. a three-stage mechanical seal cavity; 12. a restrictor body; 13. the choke joint.
Detailed Description
In the description of the present invention, it is to be understood that the terms "left end", "right end", "above", "below", "outside", "inside", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, are not to be construed as limiting the present invention.
In the prior art, in the mechanical seal of the three-stage hydrodynamic pressure type nuclear main pump, a first restrictor 3, a second restrictor 4, a third restrictor 5 and a fourth restrictor 6 distribute the pressure of a first-stage mechanical seal cavity 9, a second-stage mechanical seal cavity 10 and a third-stage mechanical seal cavity 11 into 3:3: 3.
each stage of mechanical seal cavity can bear the total system pressure of 15.4MPa in the initial stage, but each stage of mechanical seal cavity only bears 1/3 total system pressure which is about 5-5.2MPa when the nuclear main pump is in normal operation.
Referring to FIGS. 2-3, a centrifugal fill pump of a nuclear power plant RCV system provides high pressure shaft seal injection water 1 at a flow rate of 1920L/h and a pressure of 15.5 MPa.
After high-pressure shaft seal injected water 1 with the flow rate of 1920L/h and the pressure of 15.5MPa enters a shaft seal system from an injection port, the high-pressure shaft seal injected water 1 with the flow rate of 1115L/h and the pressure of 15.4MPa flows downwards to guide a bearing 2 downwards; after high-pressure shaft seal injection water 1 with the flow rate of 400L/h and the pressure of 15.4MPa passes through a first throttleer 3, the pressure is reduced to 10.3MPa, and then the water enters a secondary mechanical seal cavity 10; the high-pressure shaft seal injected water 1 with the flow rate of 400L/h and the pressure of 15.4MPa passes through a second throttleer 4, the pressure is reduced to 5.3MPa, and then enters a three-stage mechanical seal cavity 11; a third restrictor 5 is additionally connected with the secondary mechanical seal cavity 10, the pressure is reduced to 0.2MPa, and then the high-pressure leakage system 7 is entered; a fourth restrictor 6 is additionally connected with the third-stage mechanical seal cavity 11, the pressure is reduced to 0.2MPa, and then the pressure enters a high-pressure leakage system 7; thereby finishing the arrangement of the network management of the restrictor.
The controllable leakage of each stage of mechanical seal cavity is 5-15L/h, the leakage flow leaked from the seal surface of the first stage of mechanical seal cavity 9 flows into the second stage of mechanical seal cavity 10, the leakage flow leaked from the seal surface of the second stage of mechanical seal cavity 10 flows into the third stage of mechanical seal cavity 11, and the leakage flow leaked from the seal surface of the third stage of mechanical seal cavity 11 flows into the low-pressure leakage system 8.
The aperture of the restrictor is fixed, the roughness of the inner surface is certain, and the radius of gyration is the same. The inlet and outlet pressure is a fixed value. Therefore, the length of the throttle is determined only according to the requirement of the pressure difference between the front and the rear of the throttle.
Specific parameters of the first restrictor 3, the second restrictor 4, the third restrictor 5 and the fourth restrictor 6 are shown in table 1.
TABLE 1 Performance parameters of the throttle
Since the conventional three-level hydrodynamic pressure type nuclear main pump mechanical seal is self-debugged, the time is as short as 5 years, and as many as 20 secondary nuclear main pump mechanical seal low-pressure leakage flow high (leakage from the three-level mechanical seal is up to 50L/h and flows into a low-pressure leakage system 8) events occur, so that the shutdown maintenance or major maintenance line delay of a nuclear power station is caused, the nuclear safety and the economic benefit of the nuclear power station are seriously influenced, and the problem is solved to become a very urgent task for ensuring the safe and stable operation of the main pump.
According to the invention, the pressure distribution of the primary mechanical seal cavity 9, the secondary mechanical seal cavity 10 and the tertiary mechanical seal cavity 11 is adjusted to reduce the low-pressure leakage flow and alleviate the problem of high low-pressure leakage flow.
In order to achieve the above purpose, the invention provides the following technical scheme:
the utility model provides a tertiary fluid dynamic pressure nuclear main pump mechanical seal bleeder mechanism, includes No. 3 throttles of a throttle, No. 4 throttles of No. 4, No. 5 throttles of No. three and No. 6 throttles of No. 6, No. 3 throttles of a throttle and No. 5 throttles are connected with second grade mechanical seal chamber 10 respectively, No. 4 throttles of throttle and No. 6 throttles of No. two are connected with tertiary mechanical seal chamber 11 respectively, its characterized in that, No. 3 throttles of a throttle, No. 4 throttles of throttle, No. 5 throttles of No. four 6 are 4 with the pressure distribution of one-level mechanical seal chamber 9, second grade mechanical seal chamber 10 and tertiary mechanical seal chamber 11: 4: 2.
further, the restrictor comprises a restrictor joint 13 and a restrictor body 12, wherein the restrictor joint 13 is welded at one end of the restrictor body 12, the restrictor is inserted into an injection hole of a mechanical seal cavity, and then the groove of the restrictor joint 13 is clamped through pin positioning to realize the connection of the restrictor and the mechanical seal cavity.
Further, the restrictor body 12 is prepared by the following method: the choke body 12 is obtained by winding a sufficiently long pipe several times on a special tool.
Furthermore, the pressure distribution of the primary mechanical seal cavity 9, the secondary mechanical seal cavity 10 and the tertiary mechanical seal cavity 11 is realized by adjusting the sizes of the first throttle 3, the second throttle 4, the third throttle 5 and the fourth throttle 6, the change amount of the mechanical seal of the nuclear main pump is small, but the low-pressure leakage flow can be obviously reduced, and better benefits are obtained.
Further, the pressure of the three-level mechanical sealing cavity is 3-3.1 MPa.
Further, the size of the first throttle 3, the second throttle 4, the third throttle 5 and the fourth throttle 6 is obtained by the following steps: 1. the pressure distribution according to the first-stage mechanical seal cavity 9, the second-stage mechanical seal cavity 10 and the third-stage mechanical seal cavity 11 is 4: 4: 2, the differential pressure is 6.16MPa, 6.16MPa and 3.08MPa, and the calculated sizes of the first throttle 3, the second throttle 4, the third throttle 5 and the fourth throttle 6 are obtained through a pipe differential pressure model; 2. according to the requirement of 800L/h of output flow of 1 injected water for sealing the high-pressure shaft, the length of the throttle is cut off from long to short on the basis of size calculation, and a special tool is adopted for pressurizing and calibrating until the measured value of a pressure gauge meets the pressure distribution of a first-stage mechanical seal cavity 9, a second-stage mechanical seal cavity 10 and a third-stage mechanical seal cavity 11 to be 4: 4: 2, the differential pressure is 6.16MPa, 6.16MPa and 3.08 MPa.
Further, the length of the first throttle 3 is 2.04m, the length of the second throttle 4 is 4.1m, the length of the third throttle 5 is 2.96m, and the length of the fourth throttle 6 is 0.92 m. The performance parameters of the choke of the present invention are seen in table 2.
Table 2 performance parameters of the throttle of the present invention
Further, the first throttle 3, the second throttle 4, the third throttle 5 and the fourth throttle 6 are all made of 304 materials.
A preparation method of a mechanical seal pressure dividing device of a three-level hydrodynamic pressure nuclear main pump comprises the following steps:
1. a sufficiently long pipe is wound several turns on a special tool and a restrictor joint 13 is welded at one end.
2. According to the pipe network pressure difference model, calculating the pressure distribution of a first-stage mechanical seal cavity 9, a second-stage mechanical seal cavity 10 and a third-stage mechanical seal cavity 11 to be 4: 4: 2, the lengths of the respective restrictors when the differential pressures were 6.16MPa, and 3.08 MPa.
3. According to the requirement of 800L/h of flow, the length of the throttle is cut off from long to short on the basis of the calculation result, and a special tool is adopted to carry out pressurization and calibration until the measurement value of the pressure gauge meets the pressure difference described in the upper section.
4. The manufactured first throttler 3, second throttler 4, third throttler 5 and fourth throttler 6 are installed in the original mechanical seal;
5. and completing the three-level packaging mechanical seal pressing test.
The existing first throttler 3, second throttler 4, third throttler 5 and fourth throttler 6, and the first throttler 3, second throttler, third throttler 5 and fourth throttler 6 of the invention are all installed in the original mechanical seal, and the three-level packaging mechanical seal pressure test is completed, and the test results are shown in table 3.
TABLE 3 Low-pressure leakage flow rate meter
| Original design | After improvement | |
| Low pressure leakage flow | 13.6L/h | 7.9L/h |
| Third stage sealing pressure | 5MPa | 3MPa |
From the table 3, it can be seen that, compared with the prior art, the mechanical seal partial pressure of the three-stage hydrodynamic nuclear main pump reduces the low-pressure leakage flow rate of each nuclear main pump by 5.7l/h and by about 42%, and it is estimated that the emission of about 300 tons of radioactive wastewater can be reduced by two units every year, so that the three-stage hydrodynamic nuclear main pump has better social and economic benefits. In addition, the bearing pressure of the third-stage seal is reduced from 5MPa to 3MPa, so that the load is reduced, the specific pressure of the end face is reduced by 40%, and the reliability and the service life of the third-stage seal are improved.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (9)
1. The utility model provides a tertiary fluid dynamic pressure nuclear main pump mechanical seal bleeder mechanism, includes No. one throttle (3), No. two throttle (4), No. three throttle (5) and No. four throttle (6), No. one throttle (3) and No. three throttle (5) are connected with second grade mechanical seal chamber (10) respectively, No. two throttle (4) and No. four throttle (6) are connected with tertiary mechanical seal chamber (11) respectively, its characterized in that, No. one throttle (3), No. two throttle (4), No. three throttle (5) and No. four throttle (6) are 4 with the pressure distribution of one-level mechanical seal chamber (9), second grade mechanical seal chamber (10) and tertiary mechanical seal chamber (11): 4: 2.
2. the three-stage hydrodynamic nuclear main pump mechanical seal pressure dividing device according to claim 1, wherein the pressure distribution of the primary mechanical seal cavity (9), the secondary mechanical seal cavity (10) and the tertiary mechanical seal cavity (11) is realized by adjusting the size of the first restrictor (3), the second restrictor (4), the third restrictor (5) and the fourth restrictor (6).
3. The three-stage hydrodynamic nuclear main pump mechanical seal pressure dividing device according to claim 2, wherein the size of the first restrictor (3), the second restrictor (4), the third restrictor (5) and the fourth restrictor (6) is obtained by the following steps:
(1) the pressure distribution according to the first-stage mechanical seal cavity (9), the second-stage mechanical seal cavity (10) and the third-stage mechanical seal cavity (11) is 4: 4: 2, the differential pressure is 6.16MPa, 6.16MPa and 3.08MPa, and the calculated sizes of the first throttle (3), the second throttle (4), the third throttle (5) and the fourth throttle (6) are obtained through a pipe differential pressure model;
(2) according to the requirement of 800L/h of output flow of high-pressure shaft seal injected water (1), the length of the throttle is cut off from long to short on the basis of calculating the size, and the special tool is adopted for pressurizing and calibrating until the measured value of the pressure gauge meets the pressure distribution of a first-level mechanical seal cavity (9), a second-level mechanical seal cavity (10) and a third-level mechanical seal cavity (11) to be 4: 4: 2, the differential pressure is 6.16MPa, 6.16MPa and 3.08 MPa.
4. The three-stage hydrodynamic nuclear main pump mechanical seal pressure dividing device according to claim 3, wherein the length of the first restrictor (3) is 2.04m, the length of the second restrictor (4) is 4.1m, the length of the third restrictor (5) is 2.96m, and the length of the fourth restrictor (6) is 0.92 m.
5. The three-stage hydrodynamic nuclear main pump mechanical seal pressure dividing device according to claim 1, wherein the restrictor comprises a restrictor joint (13) and a restrictor main body (12), the restrictor main body (12) is welded with the restrictor joint (13) at one end, the restrictor is inserted into an injection hole of the mechanical seal cavity, and then the restrictor joint (13) is positioned and clamped through a pin to realize connection of the restrictor and the mechanical seal cavity.
6. The three-stage hydrodynamic nuclear main pump mechanical seal pressure dividing apparatus of claim 5, wherein the restrictor body (12) is prepared by: and winding the pipeline with enough length on a special tool for several times to obtain the throttle body (12).
7. The three-stage hydrodynamic nuclear main pump mechanical seal pressure-dividing device of claim 1, wherein the pressure of the three-stage mechanical seal cavity is 3-3.1 MPa.
8. The mechanical seal pressure dividing device for the three-stage hydrodynamic nuclear main pump according to claim 1, wherein the first restrictor (3), the second restrictor (4), the third restrictor (5) and the fourth restrictor (6) are all made of 304 materials.
9. The method for preparing a three-stage hydrodynamic nuclear main pump mechanical seal pressure dividing device as claimed in any one of claims 1 to 8, comprising the steps of:
(1) winding a pipeline with enough length on a special tool for a plurality of circles, and welding a throttler joint (13) at one end;
(2) according to the pipe network pressure difference model, calculating the pressure distribution of a first-level mechanical seal cavity (9), a second-level mechanical seal cavity (10) and a third-level mechanical seal cavity (11) to be 4: 4: 2, the length of each throttler when the differential pressure is 6.16MPa, 6.16MPa and 3.08 MPa;
(3) according to the requirement of the flow rate of 800L/h, on the basis of a calculation result, the length of the throttle is cut off from long to short, and a special tool is adopted to carry out pressurization calibration until the measurement value of the pressure gauge meets the pressure difference described in the upper section;
(4) the manufactured first throttler (3), second throttler (4), third throttler (5) and fourth throttler (6) are installed in the original mechanical seal;
(5) and completing the three-level packaging mechanical seal pressing test.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101649834A (en) * | 2009-09-08 | 2010-02-17 | 合肥通用机械研究院 | Hydrostatic and hydrodynamic combined type three-stage mechanical seal device for nuclear main pump |
| CN103821757A (en) * | 2014-02-21 | 2014-05-28 | 清华大学 | Dynamic pressure and static pressure mechanical seal combined type nuclear main pump gland seal system with parking sealing component |
| US9920839B1 (en) * | 2016-11-28 | 2018-03-20 | Westinghouse Electric Company Llc | Hydrostatic mechanical face seal |
| CN215214075U (en) * | 2021-04-01 | 2021-12-17 | 中核核电运行管理有限公司 | Three-stage fluid dynamic pressure type nuclear main pump mechanical seal pressure dividing device |
-
2021
- 2021-04-01 CN CN202110357600.3A patent/CN113339317A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101649834A (en) * | 2009-09-08 | 2010-02-17 | 合肥通用机械研究院 | Hydrostatic and hydrodynamic combined type three-stage mechanical seal device for nuclear main pump |
| CN103821757A (en) * | 2014-02-21 | 2014-05-28 | 清华大学 | Dynamic pressure and static pressure mechanical seal combined type nuclear main pump gland seal system with parking sealing component |
| US9920839B1 (en) * | 2016-11-28 | 2018-03-20 | Westinghouse Electric Company Llc | Hydrostatic mechanical face seal |
| CN215214075U (en) * | 2021-04-01 | 2021-12-17 | 中核核电运行管理有限公司 | Three-stage fluid dynamic pressure type nuclear main pump mechanical seal pressure dividing device |
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