JPH06257564A - High-pressure drain pump shaft sealing equipment - Google Patents

Abstract

(57) [Summary] [Object] An object of the present invention is to obtain a high-pressure drain pump shaft sealing facility suitable for flash prevention at the time of a sudden plant load change. [Structure] The high-pressure drain pump shaft sealing equipment of the present invention includes a condensate injection pipe branched from the condensate pipe of the discharge part of the high-pressure condensate pump with a normal operating temperature of 30 to 40 ° C in the shaft seal portion of the drain pump. The return water recovery tank that seals the return water with condensate and collects the return water of this condensate is equipped with a recovery pump to return this return water to the condenser, and the recovery pump and the recovery tank and the recovery between the condenser A water level control valve for controlling the water level in the return water recovery tank is provided in the line, and a temperature control device for controlling the return water temperature of the sealing water is provided in the middle of the condensate injection pipe.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-pressure feed water heater drain pump up system for a power plant, and more particularly to a high-pressure drain pump shaft sealing facility suitable for preventing flash when a sudden load change occurs in the plant.

[0002]

2. Description of the Related Art A steam turbine plant is usually constructed as illustrated in FIG.

In the figure, steam generated in a steam generator 1 including a nuclear reactor, a boiler, etc. is sequentially introduced into a high-pressure turbine 2 and a low-pressure turbine 3, and these turbines and a generator 4 directly connected to them are rotated. After driving
It is guided to the condenser 5 and condensed.

Condensed water stored in the condenser 4 is pressurized by a low pressure condensate pump 6, purified by a condensate purification device 7, and then sent to a high pressure condensate pump 8. After being further pressurized by the high-pressure condensate pump 8 and heated by the low-pressure feed water heater 10, it is pressurized again by the feed water pump 13 and returns to the steam generator 1 via the high-pressure feed water heater 14.

The low-pressure turbine 3 and the low-pressure feed water heater 10 are connected by a low-pressure extraction pipe 11, and the steam extracted from the low-pressure turbine 3 is used as a heat source of the low-pressure feed water heater 10. Drain from 10 is collected in the condenser 5 via the drain pipe 12.

The high-pressure turbine 2 and the high-pressure feed water heater 14
Are connected by a high-pressure extraction pipe 15, the steam extracted from the high-pressure turbine is used as a heat source for the high-pressure feed water heater 14, and the drain from the high-pressure feed water heater 14 is drained via a drain pipe 16 to a drain tank 17 Will be introduced to. The drain temporarily stored in the drain tank 17 is pressurized by the drain pump 20 and injected into the upstream side of the water supply pump 13. A balance pipe 18 connects the drain tank 17 and the high-pressure feed water heater 14.

By the way, a mechanical seal, a gland packing method or the like is adopted for the shaft seal portion of the drain pump 20, but in these methods, the shaft water is usually sealed and the shaft is sealed. In the conventional steam turbine plant, this shaft sealing water is connected by a self-pressurized water line 40 between the discharge side of the drain pump 20 and the seal box of the drain pump 20, as shown in FIG. It is done by press-fitting the high pressure shaft sealing water discharged from the box.

[0008]

In such a system, when the plant load is suddenly reduced due to the cutoff of the plant load or the like, the pressure in the feedwater heater is rapidly reduced, so that the drain tank and the drain pump are The drain filling up to the drain pipe up to is also flushed. The drain temperature of the high pressure drain pump up system is usually about 18
Since it is a saturated drain at about 0 ° C, the absorption line of the drain pump is easily flushed by the pressure drop. For this reason,
In the worst case, the pump vibrates, such that the sealing water cannot be sufficiently supplied to the shaft seal part of the drain pump, the temperature of the shaft seal part rises, and the shaft of the pump changes or the vibration increases. May occur and lead to damage. Therefore, it is necessary to trip the drain pump to protect it.

On the other hand, if the drain pump becomes inoperable, the amount of water supply to the steam generator will decrease sharply.
The reactor bypass valve also discharges excess steam to the condenser in order to protect the reactor by preventing sudden changes in reactor heat output even when the load suddenly decreases, so the supply of water to the steam generator does not decrease sharply. It is necessary to secure

Therefore, the amount of water supplied to the steam generator needs to be supplied by the condensate pump upstream because the drain pump is stopped. However, the amount of drain injected into the water supply system by the drain pump is a large amount equivalent to about 30% of the rated water supply flow rate to the reactor.Conversely, the low-pressure water supply pump and the high-pressure water supply pump on the upstream side of the water supply pump are rated water supply. It only has the capacity to transfer about 70% of the flow rate. Similarly, the low-pressure feed water heater and the condensate purification device also have a treatment capacity of only about 70%.

On the other hand, even when the load is suddenly reduced, such as when the load is cut off, in order to protect the reactor from a sudden change in heat output, the required feed water flow rate does not suddenly decrease, but a 100% feed water flow rate is required. Therefore, the low-pressure condensate pump and the high-pressure condensate pump are operated at a flow rate higher than the specified point, so the discharge pressure drops and the pump drive motor is overpowered. May cause a trip due to a decrease in inlet pressure, and a low pressure condensate pump and a high pressure condensate pump may cause a trip due to an excessive output of the electric motor, and the reactor will lose cooling water and scram.

As described above, in the case of a BWR plant, if the load cutoff change rate is large at the time of load cutoff, the drain pump may be damaged. In this case, in the worst case, the condensate / water supply system trips. There was a problem of loss of reactor cooling water and generation of reactor scrum.

As described above, the drain pump shaft sealing method has not been conventionally considered when the load change rate such as load cutoff is large, and when the load change rate is large, the drain pump up system drain pump The reality is that there was no optimum system and equipment for a method of stably operating the shaft seal without flushing it. An object of the present invention is to obtain a high-pressure drain pump shaft sealing facility suitable for flash prevention when a sudden plant load change occurs.

[0014]

In order to achieve the above object, the high-pressure drain pump shaft sealing equipment according to the present invention has a high-pressure condensate pump discharge at a normal operating temperature of 30-40 ° C in the shaft sealing portion of the drain pump. The return water recovery tank has a return water recovery tank that seals the condensate in the condensate injection pipe branched from the condensate water recovery pipe and collects the return water from this condensate. Has a recovery pump for returning to the reactor, a recovery line between the recovery pump and the recovery tank and the condenser, and a water level control valve for controlling the water level in the return water recovery tank in the recovery line, A temperature adjusting device for controlling the return water temperature of the sealing water is provided in the middle of the condensate injection pipe.

[0015]

As described above, according to the present invention, the condensate at the outlet of the high-pressure condensate pump, which has a low temperature and is clean and has a high pressure downstream of the condensate purifier, is used as the shaft sealing water for the drain pump. Therefore, the shaft sealing portion of the high pressure drain pump can always be set sufficiently lower than the drain pump suction drain temperature. In addition, this is set by controlling the return water of the sealing water. For this reason, the shaft sealing portion of the pump does not flash in response to a pressure change, the pump can be operated stably, and abnormal vibration can be suppressed.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a system diagram showing an embodiment of the present invention.

The shaft sealing portion of the high-pressure drain pump 20 is provided with a sealing water pipe 22 branched from the middle of the condensate pipe 9 of the discharge portion of the high-pressure condensate pump 8, and a high-pressure drain pump is provided in the middle of the sealing water pipe 22.
A temperature control valve 23 that controls the temperature of the return water in response to a control signal from a temperature detection controller 24 installed in the middle of a water return water pipe 25 from the shaft sealing portion 20 is installed. The return water has the same pressure as the atmospheric pressure and is collected by gravity in the return water recovery tank 26 through the sealed water return pipe 25. Return water recovery tank 26
The return water inside is regulated by limiting the flow rate of the return water recovery pump 27 by the water level control valve 29 which receives the signal from the water level detection controller 30 provided in the return water recovery tank and controls the level in the tank. The water is recovered by the return water recovery line 28 in the condenser 5. The return water recovery pump 27 is usually installed in the return water recovery tank 26. Return water recovery line
A line 28a that bypasses the return water recovery pump 27 is provided at 28, and check valves 31 and 32 are provided at the discharge part of the return water recovery pump and the bypass line, respectively. The bypass line can also be used to collect return water to the condenser regardless of the pump due to the difference between the vacuum degree of the condenser and the atmospheric pressure. Since the pressures of the high-pressure feed water heater 14 and the drain tank 17 are the same, the drain of the high-pressure feed water heater 14 is collected in the drain tank 17, and the drain in the high-pressure feed water heater drain pipe 16 is collected in the drain tank due to the positional difference. There must be. Therefore, the drain tank 17 should be laid out on the floor below the high-pressure feed water heater 14. Similarly, the high-pressure drain pump 20 must be installed with a sufficient level difference (level difference satisfying the required NPSH) with the drain tank 17 so that the drain on the suction side does not flash. Therefore, the high-pressure drain pump is generally installed at the bottom of the turbine building. Or it is usually installed at a level dug from the bottom. Further, since the return water of the high-pressure drain pump 27 is generally atmospheric pressure, the return-water recovery tank 26 must be installed at a level lower than that of the high-pressure drain pump 27 to recover this return water.

Due to such a relationship, the return water recovery tank 26 needs to be provided at the lowest level of the turbine building, or the position of the return water recovery tank 26 needs to be provided at a level deeper than the lowest level. The return water recovery tank 26 is most preferably installed in the chamber of the high-pressure drain pump 27, but it is considered that the return water recovery tank 26 is adjacent to the adjacent chamber.

FIG. 2 is a detailed sectional view of the pump shaft sealing portion.
The sealing water flows 34a and 34b flow into the pump shaft 33 from the direction perpendicular to the pump shaft 33, and the pump suction water flows 35a and 35b flow into the pump shaft 33 from the direction of the pump shaft 33. In the figure, A is the atmosphere side and B is the pump suction side. FIG. 3 is a sectional view showing the relationship between the high-pressure drain pump up system to which the present invention is applied and the level inside the turbine building.

[0020]

With such a structure, the shaft seal portion of the high-pressure drain pump 27 is controlled to a temperature of about 50 to 60 ° C., which is sufficiently lower than the pump suction temperature of about 180 ° C. or more. Therefore, even if a pressure drop such as load cutoff of the plant occurs, the pump shaft seal portion does not flash, so that the shaft seal function is not lost. Further, since the return water recovery tank 22 is installed at a level lower than that of the high-pressure drain pump 27 and adjacently installed, recovery of return water can occur without problems.

As described above, according to the present invention, the pump shaft sealing portion does not flush even when the plant load such as the cutoff of the plant load suddenly decreases, which contributes to the stable operation of the high-pressure drain pump, which contributes to the condensate. Contribute to stable operation of the water supply system. Therefore, stable operation of the plant becomes possible.

Further, since this system has many lines to be recovered by gravity flow, the related equipment is installed as close to each other as possible and its level is changed so that it is economically efficient without unnecessarily deepening the turbine building. We can provide high pressure drain pump shaft sealing equipment.

[Brief description of drawings]

FIG. 1 is a system diagram showing an embodiment of the present invention.

FIG. 2 is a detailed sectional view of a pump shaft sealing portion of the present invention.

FIG. 3 is a sectional view showing the turbine building of the present invention.

FIG. 4 is a system diagram showing a conventional example.

[Explanation of symbols]

1 ... Steam generator, 2 ... High pressure turbine, 3 ... Low pressure turbine, 4 ... Generator, 5 ... Condenser, 6 ... Low pressure condensate pump, 7
… Condensate purification device, 8… High pressure condensate pump, 9… Condensate piping,
10 ... Low pressure water heater, 11 ... Low pressure extraction pipe, 12 ... Low pressure water heater drain pipe, 13 ... Water pump, 14 ... High pressure water heater,
15 ... High pressure extraction pipe, 16 ... High pressure water heater drain pipe, 17 ... Drain tank, 18 ... Balance pipe, 19 ... Drain downfall pipe, 20 ...
High-pressure drain pump, 21 ... Drain injection pipe, 22 ... Sealing pipe,
23 ... Temperature control valve, 24 ... Temperature detection controller, 25 ... Sealing water return pipe, 26 ... Return water recovery tank, 27 ... Return water recovery pump, 28
… Return water recovery line, 29… Water level control valve, 30… Water level detection controller, 31… Check valve, 32… Check valve, 33… Pump shaft, 34… Sealing water flow, 35… Pump suction water flow , 36 ... Return water flow, 37 ... 3rd floor, 38 ... 2nd floor, 39 ... 1st floor.

Claims (2)

[Claims] 1. A steam generator, a steam turbine driven by steam from this steam generator, a condenser for condensing steam that has finished its work in this steam turbine, and a condenser in this condenser. A low-pressure condensate pump that sends out condensate, a condensate purification device that purifies this condensate, a high-pressure condensate pump that further pressurizes this condensate, a low-pressure feed water heater that heats this condensate, and a condensate A water supply pump that further increases the pressure for sending water to the steam generator, a high-pressure water supply heater that heats this water supply, a drain tank that stores the drain that flows out from this high-pressure water supply heater, and a drain inside this drain tank. In a high-pressure drain pump up facility for a steam turbine equipped with a drain pump that feeds the condensate pipe on the suction side of the pump, the shaft sealing part of the drain pump was branched from the condensate pipe of the discharge part of the high-pressure condensate pump. There is a return water recovery tank that seals the condensate from the sealing water pipe for injecting the condensate, and collects the return water of this condensate.The return water recovery tank has this return water to the condenser. It has a recovery pump for returning, a recovery line between the recovery pump and the recovery tank and the condenser, and a water level control valve for controlling the water level in the return water recovery tank in the recovery line. A high-pressure drain pump shaft sealing facility with a control device that controls the temperature of the return water of the sealing water in the middle of the injection pipe. 2. The return water recovery tank is installed at a level lower than the installation level of the high-pressure drain pump, and is installed adjacent to the installation position of the high-pressure drain pump. High pressure drain pump shaft sealing equipment.