JPS63294409A - Protective device for boiler feed water pump - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to the gland section of a boiler feed pump, and particularly to the protection of pump bearings.

[Conventional technology]

A pump for supplying water to a steam generator in a thermal or nuclear power plant (hereinafter referred to as a boiler feed water pump)
Since pumps generally handle high-head and high-temperature water of approximately 150° C., a water sealing method is often adopted as a sealing method for the penetrating portion between the pump casing and the shaft (hereinafter referred to as the gland portion).

This method supplies low-temperature pressure water (hereinafter referred to as shaft sealing water) to the pump gland to prevent the high-temperature water inside the pump casing from leaking to the outside. A portion of this shaft sealing water is supplied from the gland. Leakage inside the pump casing.

The remaining portion is configured to leak outward from the ground portion.

In the case of boiler feed water pumps, shaft seal water is generally supplied from the low-pressure water supply pipe at the condensate pump outlet during plant operation, and water that leaks outward from the gland (hereinafter referred to as shaft seal water return)
is often collected in a condenser, etc.

On the other hand, in plants where the boiler feed pump suction piping is taken out from the deaerator water storage tank, the pressure inside the deaerator is often quite high when the plant is stopped, so the pressure inside the boiler feed pump casing is Pressure is also high.

For this reason, when the supply of shaft sealing water to the boiler feed pump is stopped, high-temperature water in the casing leaks from the gland part, and the steam generated by flashing contaminates the pump bearing lubricating oil, causing a problem.

Conventional countermeasures to prevent this have been to continuously supply shaft sealing water to the gland of the boiler feed pump even when the plant is stopped, or to close the stop valves on the suction and discharge sides of the boiler feed pump to supply water to the boiler. A method is being implemented to drain the water inside the pump.

In Shinsha's case, there are two methods for supplying shaft sealing water: one method is to continue operating the condensate pump even when the plant is stopped and supply shaft sealing water from the outlet of the same pump, and the other is to use a small capacity pump exclusively for supplying shaft sealing water. However, in the method of using a condensate pump, the flow rate required for shaft sealing is about 20 T/H, which is about 1/40 of the specified flow rate of the condensate pump, which is a very small flow rate. , a large condensate pump throttling power loss occurs, and the power consumption for operating the condensate pump is large, which is uneconomical.

On the other hand, in the method of using a pump exclusively for supplying shaft-sealed water, the dedicated pump is generally connected to an emergency power supply because it is used only when the plant is stopped. Therefore, the capacity and equipment cost of the emergency power source will increase.

The latter method of draining water from the boiler feed pump is as follows:
Since it is necessary to fill the boiler feed pump with water when the plant is started up next time, a lot of human labor is required if there are 3 to 4 boiler feed pumps (as in normal equipment). .

Furthermore, when automating the operation, there is a drawback that equipment costs increase due to the complexity of the device.

In addition, as related technology, for example, Japanese Patent Publication No. 55-21
There is No. 242.

[Problem that the invention seeks to solve]

In the above-mentioned conventional technology, when the plant is stopped, the condensate pump is stopped, so there is no supply of shaft sealing water from the condensate pump outlet. Therefore, the shaft sealing water supply pump is activated by the emergency power supply and supplies shaft sealing water from the make-up water tank. In this case, the equipment cost of the shaft-sealed water supply pump increases and the capacity of the emergency power source also increases.

In addition, if shaft sealing water is not supplied when the plant is stopped, the pressure inside the deaerator and boiler feed water pump casing will be high, and the high-temperature water inside the casing will leak from the gland, flashing in the gland, and the generated steam will reach the pump bearing. There is a problem that it gets mixed into lubricating oil.

The purpose of the present invention is to prevent the lubricating oil from entering the pump bearings by spraying cold water from the storage tank to the gland of the boiler feed pump even when the plant is stopped or the sealing water supply pump is stopped, thereby protecting the pump bearings. At the same time, the purpose is to eliminate the dedicated shaft-sealed water supply pump, reduce equipment costs, and reduce the capacity of the emergency power source.

[Means for solving problems]

In order to solve the above problem, this can be achieved by spraying from the storage tank to the boiler feed water pump gland even when the plant is stopped or the shaft seal water supply pump is stopped.

[Effect]

When the plant is stopped or the shaft sealing water supply pump is stopped, by spraying from the storage tank to the gland of the boiler feed water pump, hot water replaces the steam generated by flushing in the gland, and the steam is converted into pump bearing lubricating oil. to prevent contamination and protect the pump bearings.

〔Example〕

Hereinafter, an example of a shaft sealing equipment for a conventional boiler feed water pump provided with a pump exclusively for supplying shaft sealing water will be explained with reference to FIG.

A condenser 1 for cooling and condensing the exhaust gas of a steam turbine (not shown) is connected to a deaerator 5 through a pipe 3, and a condensate pump 2 and a low-pressure feed water heating device 4 are installed in the middle of the pipe 3.
is provided. The deaerator 5 heats the feed water using extracted steam from the steam turbine supplied via the heating steam pipe 7, and this heated feed water flows into the water storage tank 6.
Further, the water flows into the boiler feed water pump 10 through the pipe 8, and then is supplied through the pipe 13 to a high-pressure feed water heating device or a steam generator (not shown).

A stop valve 9 is provided on the inlet side of the boiler feed pump 10, and a check valve 11 and a stop valve 12 are provided on the outlet side. The gland portion of the pump 10 is connected to a check valve 22. It is connected to the piping 3 via a piping 21 having a regulating valve 23, and is configured to supply shaft sealing water during plant operation. The shaft sealing water returned from the land portion is collected into the condenser 1 via the piping 24.

When the plant is stopped, the shaft sealing water supply pump 16 supplies water (shaft sealing water) from the make-up water tank 14 to the piping 15° stop valve 17.
Boiler water supply pump 10 via piping 21 and regulating valve 23
is supplied to the ground section.

The make-up water tank 14 is generally always provided in a thermal power plant, and its main purpose is to store make-up water to the condenser 1, and when the water level in the condenser 1 falls below a specified value. , the make-up water tank 14 by the make-up water pump 42
Make-up water will be provided within the area. In this case, the regulating valve 43 is automatically opened and closed by the water level regulator 46 of the condenser 1 via the control air pipe 47.

Also, if the water level in the condenser 1 rises above the specified value for some reason during plant operation, the water level regulator 46
The regulating valve 45 is opened, and a part of the condensate of the condenser 1 is returned to the make-up water tank 14 via the pipe 44 that connects to the outlet side pipe 3 of the condensate pump 2, and the water level in the condenser 1 is regulated. value.

As mentioned above, in the conventional shaft sealing system, the condensate pump 2 is stopped when the plant is stopped, so the shaft sealing water is supplied from the make-up water tank 14 to the ground section of the boiler feed water pump IO using the pump 16 dedicated to supplying shaft sealing water. It is configured to supply shaft sealing water and return shaft sealing water from the gland section to the condenser 1.

An embodiment of the present invention will be described with reference to FIGS. 1 and 2.

The device according to the present invention uses a pump 16 exclusively for supplying shaft sealing water from the conventional make-up water tank 14 shown in FIG. In addition to the piping 21 that
A system is provided from 4 to the ground section 61 shown in FIG. 2 via a stop valve 52 provided in a pipe 51.

The supply of shaft sealing water to the gland portion 61 of the boiler feed pump 10 and the return recovery of shaft sealing water by the condensate pump 2 during plant operation are the same as in the conventional system (FIG. 3).

When the plant is stopped, since the condensate pump 2 is stopped, shaft sealing water is not supplied to the ground portion 61 of the boiler feed pump 10.

Therefore, from the make-up water tank 14 to the boiler feed water pump 1
Cold water is sprayed onto the ground section 61 of the boiler feed water pump 10, but the high temperature water in the deaerator water storage tank 6 continues to enter the pump casing and the level of the deaerator water storage tank 6 drops. The inlet side stop valve 9 and the outlet side stop valve 12 are fully closed. Furthermore, even when the inlet side stop valve 9 and the outlet side stop valve 12 are fully closed, if cold water is not sprayed to the gland section 61 of the boiler feed water pump 10, high temperature water in the pump casing will leak from the gland section 61.
The steam generated by flashing in step 1 will mix into the pump bearing lubricating oil, causing a problem.

In this case, cold water is supplied to the gland section 61 of the boiler feed water pump 10 from the make-up water tank 14 through the stop valve 52 provided in the piping 51, from the spray water inlet 62, and from the spray water outlet 63 to the gland section. 61.

Therefore, the hot water in the pump casing is flashed in the gland part 61, and the generated steam is replaced with the hot water to prevent the steam from getting mixed into the pump bearing lubricating oil and protect the pump bearing.

At this time, the eruption water supply pressure is the difference in static water head between the make-up water tank 14 and the ground portion 61 of the boiler feed water pump 10.

In addition, the pressure of high-temperature water inside the deaerator and the casing is about 8 to 10 kg/cJ, and the spray water supply pressure needs to be higher than the high-temperature water pressure. 14 must be installed in a location where pressure higher than the pressure of high-temperature water can be secured.

〔Effect of the invention〕

According to the present invention, when the plant is stopped and the shaft sealing water supply pump is stopped, high-temperature water in the pump casing is prevented from leaking from the gland part by spraying from the make-up water tank to the gland part of the boiler feed water pump. At the same time, this has the effect of preventing steam generated by flashing of high-temperature water in the pump casing at the gland section from mixing with the pump bearing lubricating oil, thereby protecting the pump bearing.

Furthermore, by abolishing the shaft-sealed water supply pump, it is possible to reduce equipment costs and reduce the capacity of the emergency power supply, which saves labor at the power plant, which is economical.

[Brief explanation of drawings]

Fig. 1 is a system configuration diagram of a protection device for a boiler feed pump according to an embodiment of the present invention, Fig. 2 is a sectional view of the gland section of a boiler feed pump according to an embodiment of the present invention, and Fig. 3 is a shaft sealing diagram. FIG. 1 is a system configuration diagram of a conventional boiler feed water pump shaft water sealing device that is provided with a dedicated water supply pump. 1... Condenser, 2... Condensate pump, 5... Deaerator, 10... Boiler feed pump, 14... Make-up water tank, 16... Shaft seal water supply exclusive pump , 42...Makeup water pump, 61...Gland part, 62...Spray water inlet, 63...Spray water outlet.

Claims (1)

[Claims] 1. In a boiler feed pump of a power generation plant that has a steam regeneration cycle, when the seal water supply pump that supplies seal water to the pump gland stops, cold water from the storage tank is sprayed to the boiler feed water pump gland, and the pump A boiler feed pump protection device that protects bearings.