JP2804615B2 - Pump sealing device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a water sealing device of a pump for increasing the working fluid used in a power plant in a power plant such as a nuclear power plant, and more particularly to a turbo pump. The present invention relates to a pump water sealing device suitable for increasing the operating efficiency of a pump by minimizing the leakage of the working fluid inside the device to the outside.

[Background Art] In a water sealing device of a turbo-type pump for increasing the temperature of a high-temperature working fluid in a power plant, for example, as shown in FIG. 8, a non-contact type shaft seal type such as a throttle bush seal is used. Things have been adopted. In FIG.
First and second non-contact type shaft seal members c and d are mounted between the rotary shaft a of the pump and the seal box b along the axial direction of the rotary shaft a. A fluid A for sealing the shaft, which is made of room-temperature water, is supplied to the shaft seal member d.

When the fluid A is injected between the first and second shaft seal members c and d in such a pump sealing device, the fluid A flows from between the first shaft seal member c and the rotary shaft a. It mixes with the leaking internal fluid (high-temperature water) B of the pump and, as mixed, is guided as drainage fluid C to the outside of the water sealing device as shown in FIG. Will be collected. In this case, the drainage fluid C is measured by the thermometer f, and based on the measurement, the injection water control valve g is set to, for example, 50 to 70 ° C. even if the drainage fluid C is mixed with the internal fluid B of the pump.
The fluid A is controlled so that the temperature becomes about the same.

Related devices of this type include, for example, Japanese Utility Model Laid-Open No. Sho 62-172903 and Japanese Patent Laid-Open No. Sho 62-242707.

[Problems to be Solved by the Invention] By the way, in the above-mentioned conventional technology, when the fluid A is injected between the first and second shaft seal members c and d, the fluid A mixes with the internal fluid B leaking from the pump. No consideration has been given to the fluid behavior until the internal fluid B is mixed with the fluid.

That is, if the pump is handling particularly hot saturated water,
The internal fluid B of the pump includes a first shaft sealing member c and a rotating shaft a.
If there is a gap between the outer end of the seal box b and the rotating shaft a, there is a certain gap 1 between the outer end of the seal box b and the rotary shaft a. Therefore, when the internal fluid B of the pump leaks to the seal box b side, the pressure is rapidly reduced and flash (self-evaporation) occurs, and the internal fluid B is condensed by mixing with the fluid A having a lower temperature. So
As a result of the occurrence of water hammer or cavitation, there has been a problem that the rotating shaft a is damaged and reliability is reduced.

Further, as described above, since the inside of the seal box b is at the atmospheric pressure, even if the fluid A is at a certain pressure, when the seal box b is supplied, the pressure becomes the same as the atmospheric pressure. The drainage fluid C discharged from the tank must be recovered in the recovery tank e by using gravity, and a prescribed gradient of the piping system of the drainage fluid C is required.
Therefore, it is necessary to set the recovery tank e lower than the pump. However, when attempting to recover using gravity, it is necessary to form a concave portion for installing the recovery tank e on the floor of the building, and there is a problem that the shape of the building must be changed.

In order to solve this, for example, when installing a collection tank outside the building, not only must the collection tank be installed underground, but the space required for installing the collection tank is large, so There is also the problem of high costs.

SUMMARY OF THE INVENTION An object of the present invention is to provide a pump capable of preventing a flush from occurring even if the internal fluid of the pump leaks, and capable of collecting drainage fluid without changing the floor shape of a building in view of the above-mentioned problems of the related art. It is to provide a water sealing device.

[Means for Solving the Problems] For the purpose described above, according to the present invention, a non-contact type first shaft seal member disposed on the pump side is provided inside a seal box disposed on an outer peripheral portion of a rotary shaft of the pump. A non-contact type second shaft seal member disposed at a closer position is attached along the axial direction of the rotating shaft, respectively, and a first shaft seal member between the first shaft seal member and the second shaft seal member in the seal box is provided. In a pump water sealing device configured to supply a shaft sealing fluid to a space, a contact-type third shaft disposed in the seal box at a position outside the second shaft seal member with a second space therebetween. A seal member is attached, and a shaft sealing fluid having a pressure lower than the pressure of the internal fluid of the pump is configured to flow sequentially from the first space portion to the second shaft seal member, between the rotating shaft, and the second space portion. It has a special feature.

[Operation] In the present invention, as described above, the contact-type shaft seal member disposed at a position closer to the outside than the second shaft seal member is mounted in the seal box. When the pressure inside the seal box is higher than the atmospheric pressure and the internal fluid B of the pump leaks into the seal box 2, the internal fluid B does not fall below the atmospheric pressure even if the leaked internal fluid B is decompressed. B can be prevented from flashing. Therefore, since flushing does not occur due to leakage of the internal fluid B, occurrence of water hammer, cavitation, and the like can be reliably prevented.

Further, as described above, since the inside of the seal box is a pressure chamber higher than the atmospheric pressure by attaching the third shaft seal member, even if a fluid is supplied into the seal box, the pressure may fall below the atmospheric pressure. Absent. Therefore, the drainage fluid flowing from the inside of the seal box does not fall below the atmospheric pressure, so that the drainage fluid can be guided upward, and the collection tank can be easily installed at an upper position in the building. Therefore, it is not necessary to install an installation hole or the like on the floor of a building or the like in order to install the collection tank as in the related art, and the collection tank can be easily installed at an arbitrary position in the building.

Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 to 7. FIG. 1 is a cross-sectional view showing a first embodiment of a pump water sealing device according to the present invention, FIG. 2 is an explanatory diagram showing recovery of drainage fluid of the water sealing device, and FIG. 3 is a turbo type to which the present invention is applied. It is a schematic system diagram showing a power plant using a pump.

In FIG. 3, the steam generated from the reactor 21 is sequentially introduced into the high-pressure turbine 22 and the low-pressure turbine 23 to drive the turbines, and then is condensed by passing through the condenser 24 to be condensed. Be transformed into The condensate stored in the condenser 24 is pressurized by a condensate pump 25 and heated by a low-pressure feed water heater 26.
The water is pressurized again by the feed water pump 27 via the drain pump up point 34 and the like, and further heated to a desired temperature by the high pressure feed water heater 28 to return to the reactor 21.

The low-pressure turbine 23 and the low-pressure feedwater heater 26 are connected by an extraction pipe 29, and steam extracted from the low-pressure turbine 23 is used as a heat source of the low-pressure feedwater heater 26.

On the other hand, the high-pressure turbine 22 and the high-pressure feedwater heater 28 are
The steam extracted from the high-pressure turbine 22 is used as a heat source of the high-pressure feed water heater 28, and is condensed by exchanging heat with the feed water of the high-pressure feed water heater 28 to become a drain of the high-pressure feed water heater, Collected in the high-pressure drain tank 31. Then, the drain in the high-pressure drain tank 31 is pressurized by the high-pressure drain pump 32 and adjusted in flow rate by the control valve 33, so that the drain merges with the condensate that has passed through the low-pressure feed water heater 26 at the drain pump up point 34.

In addition, the high pressure drain pump 32 and the discharge side of the condensate pump 25 are connected by a fluid supply pipe 35, and a part of the condensate discharged from the condensate pump 25 is used as shaft sealing water of the high pressure drain pump 32. I am trying to do it.

In the water sealing device of the high-pressure drain pump 32, as shown in FIG. 1, first and second shaft seal members 3 and 4 are mounted in the seal box 2 along the axial direction of the rotating shaft 1. .
The first shaft seal member 3 is a non-contact type like the second shaft seal member 4 and is located in the seal box 2 on the inner fluid side of the pump on the left side in the figure, The shaft seal member 4 is located outside the first shaft seal member 3 in the seal box 2.

When the fluid A for shaft sealing is supplied to the first space portion 5 between the first shaft seal member 3 and the second shaft seal member 4 in the seal box 2, the fluid A is supplied as shown in FIG. As shown by a broken line in FIG. 7, the fluid flows through the space between the second shaft seal member 4 and the rotating shaft 1 and flows to the fluid drain pipe 36 as the drain fluid C. The end of the fluid drain pipe 36 is connected to the recovery tank 6 as shown in FIG.

In the water sealing device of the embodiment, a third shaft seal member 7 is attached inside the seal box 2 along the first and second shaft seal members 3 and 4. Third shaft seal member 7
Is a contact type that can come into close contact with the rotating shaft 1 and is mounted inside the seal box 2 outside the second shaft seal 4 with the second space 8 therebetween. By sealing the inside and the outside of the box 2, the inside of the seal box 2 becomes a space chamber having a pressure higher than the atmospheric pressure. Therefore, the third shaft seal member 7 may be a mechanical seal member that can airtightly shield the inside and the outside of the seal box 2, and may be, for example, a labyrinth packing.

Further, the first shaft seal member 3 and the second shaft seal member 4
Is set at a pressure higher than the pressure of the internal fluid of the pump. For this reason, the condensate pump 25 sends condensate having a pressure higher than the pressure of the internal fluid of the drain pump 32 to the drain pump 32 as the fluid A.

In the water sealing device having the above-described configuration, the condensate pump 25 supplies fluid to the first space 5 between the first shaft seal member 3 and the second shaft seal member 4 in the seal box 2 of the drain pump 32. When the fluid A is supplied, the fluid A passes between the second shaft seal member 4 and the rotating shaft 1 as shown by a broken line in FIG. The fluid flows through the second space 8 between the shaft seal member 7 and the fluid drain pipe 36.

In this case, in the drain pump 32, the internal fluid B may leak into the inside of the seal box 2 and flush may occur.

However, the seal box 2 has the second shaft seal member 4
A contact-type third shaft seal member 7 disposed further outside
Is mounted, and the inside of the seal box 2 is higher than the atmospheric pressure by the third shaft seal member 7, so that when the internal fluid B of the pump leaks into the seal box 2, even if the leaked internal fluid B is reduced in pressure, The flushing of the leaked internal fluid B can be prevented without falling below the atmospheric pressure. Therefore, since flushing does not occur due to leakage of the internal fluid B, occurrence of water hammer, cavitation, and the like can be reliably prevented. Moreover, in this example, since the fluid A sent to the seal box 2 has a higher pressure than the pressure of the internal fluid B of the drain pump 32,
Since the first and second shaft seal members 3 and 4 are of a non-contact type, even if the seal box 2 and the inside of the pump are in communication with each other, it is possible to prevent the internal fluid B from leaking into the seal box 2. It can be suppressed reliably.

Further, as described above, since the inside of the seal box 2 is a pressure chamber higher than the atmospheric pressure by attaching the third shaft seal member 7, even if the fluid A is supplied into the seal box 2, the atmospheric pressure is maintained. Never go down. Therefore, since the drainage fluid C flowing from the inside of the seal box 2 to the fluid drainage pipe 36 is higher than the atmospheric pressure, the drainage fluid C can be guided upward, and as shown in FIG.
Can easily be installed at an upper position in the building. Therefore, it is not necessary to install an installation hole or the like on the floor of a building or the like in order to install the collection tank as in the related art, and the collection tank 6 can be easily installed at an arbitrary position in the building.

FIG. 4 shows a second embodiment of the water sealing device according to the present invention.

The difference between this embodiment and the first embodiment is that
The point is that a pressure adjusting mechanism for maintaining the difference between the pressure of the fluid A sent into the seal box 2 and the pressure of the internal fluid B of the drain pump 32 at a specified value is provided.

That is, the pressure adjusting mechanism is provided at an intermediate position of the fluid supply pipe 35, and detects a pressure of the fluid A passing through the fluid supply pipe 35, and a pressure gauge 9 upstream of the pressure gauge 9 of the fluid supply pipe 35. An injection water control valve 10 for adjusting the pressure of the fluid A supplied to the seal box 2, a pressure gauge 11 for detecting the pressure of the internal fluid B of the drain pump 32, and a control unit 12. When the fluid A is sent into the seal box 2, the controller 12 reads the pressure of the fluid A by detecting the pressure gauge 9, reads the pressure of the internal fluid B by the pressure gauge 11, and reads the internal fluid B and the fluid A. Is calculated, and the opening degree of the injection water control valve 10 is controlled so that the pressure difference becomes a predetermined specified value. In this case, the pressure of the fluid A is adjusted so that no flash or the like occurs when the internal fluid B leaks to the seal box 2 side.
The pressure is selected to be slightly lower than the pressure of the internal fluid B.

In FIG. 4, the same reference numerals as those in FIG. 1 denote the same components.

According to this embodiment, since the pressure of the fluid A to be supplied to the seal box 2 is maintained at a prescribed value slightly lower than the internal fluid B of the pump by the pressure adjusting mechanism, the internal fluid B Even if leakage occurs, the flow velocity of the leaked internal fluid can be reduced, and leakage of the internal fluid B can be reduced as much as possible. Therefore, it is possible to prevent a flash from occurring and to prevent cavitation or the like from occurring. In addition, when the pressure of the fluid A is selected to be lower than the pressure of the internal fluid B, the fluid A sequentially moves from the first space 5 to the space between the rotary shaft 1 and the second shaft seal member 4 and to the second space 8. When the fluid pressure decreases stepwise due to the circulation, the pressure difference in the third shaft sealing member 7 does not exceed the allowable pressure difference (the pressure difference at which the shaft sealing member 7 can secure the sealing function), and the sealing function does not occur. Can be favorably maintained. Further, as described above, since the pressure in the seal box 2 is higher than the atmospheric pressure, the pressure of the fluid A does not fall below the atmospheric pressure. 6 can be easily installed at an upper position in the building.

FIG. 5 shows a third embodiment of the water sealing device according to the present invention.

In this case, the seal box 2 is
Is maintained so that the difference between the temperature of the fluid A fed into the second space 8 and the temperature of the fluid passing through the second space 8 in the seal box 2 becomes a specified value. That is, as shown in FIG. 5, the temperature adjusting mechanism is provided at an intermediate position of the fluid supply pipe 35 and detects the temperature of the fluid A passing through the fluid supply pipe 35.
An injection water control valve 14 provided upstream of the thermometer 13 of the fluid supply pipe 35, and a seal box 2 of the fluid drain pipe 36.
A thermometer 15 for detecting the temperature of the drainage fluid C and a control unit 16 are provided at the side position. When the fluid A is sent into the seal box 2, the control unit 16
Is read by the detection of the thermometer 13, the temperature of the fluid passing through the second space 8 in the seal box 2 is read by the thermometer 15, the temperature difference between them is calculated, and the temperature difference is set in advance. The opening of the injection water control valve 16 is controlled so as to reach the specified value. In this case, the pressure of the fluid A sent into the seal box 2 is higher than the atmospheric pressure, and the temperature is selected to be slightly lower than the temperature of the fluid passing through the second space 8.

As described above, when the difference between the temperature of the fluid A and the temperature of the fluid passing through the second space 8 is kept at a specified value by the temperature adjustment mechanism,
When the internal fluid B leaks into the seal box 2, the flow velocity of the wet internal fluid can be reduced, and the leakage of the internal fluid B can be reduced as much as possible.
Even if the internal fluid B leaking to the side is at a high temperature, cavitation and the like can be prevented from occurring.

FIG. 6 shows a fourth embodiment of the water sealing device according to the present invention.

This embodiment has a drainage fluid pressure adjusting mechanism for keeping the pressure of the drainage fluid C discharged from the seal box 2 at a specified value.

The drainage fluid pressure adjusting mechanism is provided in the drainage fluid line, is provided at a position halfway through the fluid drainage pipe 36, and detects a pressure of the drainage fluid C passing through the fluid drainage pipe 36, and a pressure gauge 17; It comprises a pressure control valve 18 that adjusts the opening based on the detection of the pressure gauge 17 to maintain the pressure of the drainage fluid C with respect to the condenser 24 at a preset specified value. One end of the drainage fluid pipe 36 is connected to the fluid discharge portion of the seal box 2,
And the other end is connected to the inflow part of the condenser 24, respectively.

According to this embodiment, since the drain fluid C discharged from the seal box 2 has a pressure exceeding the atmospheric pressure due to the provision of the third shaft seal member 7, the drain fluid C
Not only can be reliably fed into the condenser 24, but also as described above, the drainage fluid pressure adjusting mechanism keeps the pressure of the drainage fluid C substantially constant.
24, and the drainage fluid C can be used effectively. In addition, the drainage fluid pressure adjustment mechanism consists of a pressure gauge 17 and a control valve.
18, the drainage fluid C is no longer temporarily stored in the recovery tank as in the embodiment shown in FIG.
Since the liquid is directly guided to the condenser 24, a collection tank, a pressure increasing pump, and the like are not required.

FIG. 7 shows another example of the drainage fluid pressure adjusting mechanism of the drainage fluid line.

The drainage fluid pressure adjusting mechanism of this embodiment includes a drainage fluid pipe 36.
Between the pressure gauge 17 provided at the middle position of the drainage fluid pipe 36, the pressure control valve 18 provided downstream of the pressure gauge 17 of the drainage fluid pipe 36, and the pressure gauge 17 and the pressure control valve 18 of the drainage fluid pipe 36. The pressure gauge 17 detects the pressure of the drainage fluid C, while the pressure gauge 19 pressurizes the drainage fluid C, and the pressure control valve 18 adjusts the opening based on the detection of the pressure gauge 17. By adjusting, the drainage fluid C is recovered by sending it to the high-pressure feedwater heater 25 or the drain tank 31 or the like.

According to this embodiment, the drainage fluid C is boosted by the drainage fluid pressure adjusting mechanism and is recovered at a substantially constant pressure, so that the drainage fluid C can be used effectively.

[Effects of the Invention] As described above, according to the present invention, a shaft sealing fluid having a pressure lower than the pressure of the internal fluid of the pump is supplied into the seal box, and the shaft sealing fluid is supplied inside the seal box. Since the first space portion is configured to sequentially flow between the second shaft seal member, the rotating shaft, and the second space portion, even if the internal fluid of the pump leaks into the seal box, a flush occurs in the seal box. Can prevent water hammer and the like, and can prevent the fluid passing through the seal box from dropping below the atmospheric pressure and guide the drainage fluid to a desired upper position. As a result of being able to collect the drainage fluid without any change, there is an effect that reliability can be improved accordingly.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of a pump sealing device according to the present invention, FIG. 2 is an explanatory diagram showing recovery of drainage fluid of the pump sealing device, and FIG. 3 is a turbo to which the present invention is applied. FIG. 4 is a schematic diagram showing a power plant using a type pump, FIG. 4 is a sectional view showing a second embodiment of the pump sealing device according to the present invention, and FIG. 5 is a third embodiment of the pump sealing device. FIG. 6 is an explanatory view of a drainage fluid pressure adjusting mechanism showing a fourth embodiment of the pump water sealing device, FIG. 7 is an explanatory view showing another example of the drainage fluid pressure adjusting mechanism, FIG. Is a cross-sectional view showing an example of a configuration of a conventional pump water sealing device, and FIG. 9 is an explanatory diagram showing a drainage fluid line using the conventional pump water sealing device. 1 ... rotating shaft, 2 ... seal box, 3 ... non-contact type first shaft seal member, 4 ... non-contact type second shaft seal member, 5 ... first space portion, 6 ... … Recovery tank, 7 ……
Third shaft seal member, 8 second space section, 9 pressure gauge, 10 injection water control valve, 11 pressure gauge, 12 control section, 13 thermometer, 14 Injection water control valve, 15 ... thermometer, 16 ... control unit, 17 ... pressure gauge, 18 ... pressure control valve,
19 ... booster pump, 35 ... fluid supply pipe, 36 ... fluid drain pipe, A ... fluid, B ... pump internal fluid, C ... drain fluid.

Continuation of the front page (72) Inventor Ken Fujita 603, Kandamachi, Tsuchiura-shi, Ibaraki Pref. Tsuchiura Plant, Hitachi, Ltd. (58) Field surveyed (Int. Cl. ⁶ , DB name) F04D 29/10 F16J 15 / 40

Claims (1)

(57) [Claims] 1. A non-contact type first shaft seal member arranged on the pump side and a non-contact type second shaft member arranged closer to the outside in a seal box arranged on an outer peripheral portion of a rotary shaft of the pump. A shaft sealing member is attached along the axial direction of the rotating shaft, and a fluid for shaft sealing is supplied to a first space between the first shaft sealing member and the second shaft sealing member in the seal box. In the pump water sealing device, a contact-type third shaft seal member disposed in the seal box at a position outside the second shaft seal member with a second space portion interposed therebetween,
A fluid for shaft sealing smaller than the pressure of the internal fluid of the pump is configured to sequentially flow from the first space portion to the second shaft seal member, between the rotating shaft, and the second space portion. Pump sealing device.