JPS62242707A - Steam turbine plant - 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] [Object of the Invention] (Field of Industrial Application) The present invention makes it possible to maintain the integrity of a condensate water supply system in a steam turbine plant such as a nuclear power plant or a thermal power plant. Regarding steam turbine plants.

(Prior Art) A steam turbine plant is constructed as shown at 191 in FIG.

In the figure, steam generated in a steam generator 1 consisting of a nuclear reactor, boiler, etc. is sequentially introduced into a high-pressure turbine 2 and a low-pressure turbine 3, which rotationally drives these turbines and the power generator 4 directly connected to them. After cooling, it is led to a condenser 5 where it is condensed.

The condensate stored in the condenser 4 is pressurized by a condensate pump 6, heated by a low-pressure feed water heater 7, then pressurized again by a feed water pump 8, and passed through a high-pressure feed water heater 9 to generate steam. Return to vessel 1.

Between the low pressure turbine 3 and the low pressure feed water heater 7 is an oil air pipe 1.
The steam extracted from the low-pressure turbine 3 is used as a heat source for the low-pressure feedwater heater 7, and the drain from the low-pressure feedwater heater 7 is connected to the condenser 5 via a drain pipe 11.
will be introduced in

Furthermore, the high-pressure turbine 2 and the high-pressure feedwater heater 9 are connected by an oil air pipe 12, and the steam extracted from the high-pressure turbine is used as a heat source for the high-pressure feedwater heater 9, and the steam extracted from the high-pressure feedwater heater 9 is drained from the high-pressure feedwater heater 9. is introduced into the drain tank 14 via the drain pipe 13.

The drain temporarily stored in the drain tank 14 is pressurized by the drain pump 15, and then passed through the water level control valve 16 to the water supply pump 8.
Water is supplied to the upstream side of the river. The opening degree of the water level control valve 16 is controlled by a level gauge 17 attached to the drain tank 14. Further, the drain tank 14 and the high-pressure feed water heater 9 are communicated with each other through a balance pipe 18.

By the way, a mechanical seal, a gland packing method, etc. are adopted for the shaft seal part of the drain pump 15, but these methods usually have a water seal on the shaft part and f11? Shaft water sealing that also serves as fl is performed. In conventional steam turbine plants, this shaft sealing water is produced by connecting the discharge side of the drain pump 15 and the seal box of the drain pump 15 with one self-pressure water line, as shown in FIG. This is done by press-fitting high-pressure shaft sealing water discharged from line 19 into the box.

(Problems to be Solved by the Invention) In the conventional steam turbine plan 1- configured as described above, when the load of the plant suddenly changes for some reason, the pressure is reduced in response to the change in the internal pressure of the steam turbine. The pressure inside the high-pressure feed water heater 7.9 also changes, and the pressure inside the drain tank 14 also changes.

Therefore, if, for example, the steam/steam turbine blanc suddenly shifts to partial load, the pressure inside the drain tank "+4" will drop rapidly. However, since the temperature of the drain does not drop rapidly, a portion of the high temperature drain before the partial load transition flashes inside the drain tank 14 and the drain pipe 20, causing the drain to dry. Cavitation or abnormal vibration may occur in the pump 15. Also,
Since the pressure on the discharge side of the drain pump 15 also decreases rapidly,
Flushing occurs transiently in the shaft sealing water supplied from the self-pressure water line 19, and there is a risk that the shaft sealing function may be lost.

In the unlikely event that the drain pump 15 is damaged by drainage or abnormal vibration and stops, it will directly affect the water supply to the steam generator 1, and there is a great risk that the plant will stop abnormally. .

The present invention has been made in order to eliminate the above-mentioned drawbacks in the background art, and is designed to reliably prevent drain flushing and abnormal vibrations in the drain pump when the plant is under sudden partial load. The purpose is to provide a highly reliable steam turbine plant that can prevent

[Structure of the Invention] (Means for Solving the Problems) The steam turbine plant of the present invention includes a steam generator, a steam turbine driven by steam from the steam generator, and a steam turbine that completes work with the steam turbine. A condenser that condenses steam, a water pump that sends out condensate in this condenser,
A low-pressure feed water heater and a high-pressure feed water heater that heat the condensate sent out, a drain tank that stores the drain flowing out from the high-pressure feed water heater, and a drain pump that sends the drain in the drain tank to the condensate supply system. In a steam turbine plant, the upstream side of the low-pressure feed water heater and the seal box of the drain pump are connected by a water seal line to supply shaft seal water, and the return flow from the seal box is recorded as 111g. It is characterized in that it is configured to be supplied to the suction side of the drain pump.

(Function) As described above, in the steam turbine plant of the present invention, low-temperature condensate before being heated by the feed water heater is used as the shaft sealing water of the drain pump, and this shaft sealing water is used to prevent leak-off. After mixing, it is returned to the suction side of the drain pump as reflux, so the suction temperature of the drain pump can be maintained at a low temperature at all times, and the occurrence of flashes and abnormal imaging can be prevented even when a steam turbine plant is under partial load. .

(Example) Hereinafter, the present invention will be described in detail with reference to the drawings. In addition,
In these figures, parts 1 that are the same as those in FIG.

In FIG. 1, two-stage low pressure feed water heaters 7a and 7b are used as low pressure feed water heaters, and a low pressure turbine 3
Steam extracted from intermediate stages on the high-pressure side and low-pressure side is introduced into the low-pressure feed water heaters 7a and 7b, and the
Heat exchange is performed with the condensate flowing in the next piping, and the 1"4 condensate passes through the drain pipes 11b and 11a to the condenser 5.
sent to.

In addition, in the condensate supply system connecting the condenser 5 and the steam generator 1, a water sealing line 21 is branched and connected between the condensate pump 6 and the low-pressure water supply 1)n heater 78. .

The narrow end side of this water seal line 21 opens into a seal box 15a of the drain pump 15, as illustrated in FIG. The space between the pump shaft 15b and the flange 15c of the seal box 15a is sealed with a mechanical seal 15d, and the leak-off 15e is mixed with the shaft sealing water 22 from the sealing line 21 to become a low-temperature reflux 23, which is drained through the reflux pipe 24. One person is placed on the suction side of the pump 15.

In the embodiment of the present invention configured as described above, on the suction side of the drain pump 15, there is a low-temperature reflux 23 formed by mixing the leak-off 15e@ with the low-temperature condensate (shaft seal water) 22 from the condenser 5. is supplied to the drain pump 15, even if the steam turbine plant suddenly shifts to partial load.
There is no flash, and the drain pump operates normally.

Next, other embodiments of the present invention will be described.

In FIG. 3, an orifice 25 for restricting the flow Φ and a bypass valve 26 are installed in parallel in the middle of the water sealing line 21.

In this embodiment, the bypass valve 26 is normally closed and the flow rate of the shaft seal water flowing through the seal water line 21 is limited by the orifice 25, but if the steam turbine plant suddenly shifts to partial load. The bypass valve 26 is automatically opened in response to a plant operation command or a signal from a load detection sensor, bypassing the orifice 25 and sending many m of condensate into the seal box of the drain pump 15.

The condensate sent into the seal box is pumped to the pump shaft 15b.
It is mixed with the leak-off 15e leaking along the
Although the temperature rises to some extent, the water still remains at a low temperature and flows back through the reflux pipe 24 to the suction side of the drain pump 15.

Therefore, even when the steam turbine plant is at partial load, the suction temperature of the drain pump remains low and flash is prevented from occurring.

The embodiment shown in FIG. 4 has a water sealing line 211 and a normally closed valve 27.
A check valve 28 is inserted in the self-pressure water line 19, and the downstream side of the self-pressure water line 19 and the sealing water line 21 are merged to form a U opening in the seal box of the drain pump 15.
It is something that

In this embodiment, normally 11,1 is normally closed t? 27 is closed, and a part of the condensate discharged from the drain pump 15 is pressurized into the seal box of the drain pump 15 via the self-pressure water line 19 and the check valve 28, and functions as shaft sealing water. are doing.

On the other hand, if the steam turbine plant suddenly shifts to a partially negative direction, the normally closed valve 27 automatically opens in response to the control command or a signal from the detection sensor, and the normally closed valve 27, which is composed of the condensate pump 6 Sealing line 21 for condensate at device temperature
Since the ceiling-mounted seal box of the drain pump 15 is supplied through the reflux tube 24, low-temperature reflux also flows into the Okawa on the suction side of the drain pump 15 through the reflux pipe 24, and the drain pump 1
The flushing phenomenon caused by the decrease in the internal pressure of No. 5 is suppressed.

[Effects of the Invention] As described above, in the present invention, the shaft sealing water of the drain pump is supplied from the water sealing line branching from the condensate supply pipe upstream of the feed water heater, and the shaft sealing water after sealing is Since the flow is recirculated to the suction side of the drain pump, even if the load on the steam turbine plant suddenly decreases for some reason and the internal pressure of the drain pump decreases as a result, the suction side of the drain pump will be recirculated. The shaft sealing water temperature is low.
Flushing and abnormal vibrations can be prevented, and the shaft seal can be reliably cooled, making it possible to construct a highly reliable steam turbine plant.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing an embodiment of the steam turbine plant of the present invention, and FIG. 2 is a system diagram showing an embodiment of the steam turbine plant of the present invention.
3 and 4 are system diagrams of the vicinity of the drain pump showing other embodiments of the present invention, and FIG. FIG. 1 is a system diagram illustrating a turbine plant. 1... Steam generator 2... High pressure turbine 3... Low pressure turbine 4... Generator 5 ......Condenser 6...Condensate pump 7...Low pressure feed water heater 8...Water supply Pump 9... High pressure water heater 10.12... Bleed pipe 11.13.20... Drain pipe 14... Drain tank 15... ......Drain pump 16...Water level control valve 17...Level meter 18...Balance pipe 19... ...Self-pressure water line 21...Sealing line 25...Orifice 26...Bypass valve 27... ...Normally closed valve 28...Check valve

Claims (3)

[Claims] (1) A steam generator, a steam turbine driven by steam from the steam generator, a condenser that condenses the steam that has finished work in the steam turbine, and condensate in the condenser A water pump that sends out water, a low-pressure feed water heater and a high-pressure feed water heater that heat the sent condensate, a drain tank that stores the condensate flowing out from the high-pressure feed water heater, and a condensate tank that condenses the condensate in the drain tank. In a steam turbine plant equipped with a drain pump that feeds into a supply system, a sealing line connects the upstream side of the low-pressure feed water heater and a seal box of the drain pump to supply shaft sealing water, and the seal box A steam turbine plant, characterized in that the steam turbine plant is configured to supply the recirculated flow from the drain pump to the suction side of the drain pump. (2) Claim 1 characterized in that an orifice for restricting the flow rate of shaft sealing water constantly supplied to the drain pump and a bypass valve parallel to this orifice are installed in the middle of the sealing line. The steam turbine plant described in Section 1. (3) A normally closed valve is inserted in the water sealing line, and the self-pressure water line that branches from the discharge side of the drain pump joins the water sealing line on the downstream side of this normally closed valve. 2. The steam turbine plant according to claim 1, wherein a check valve is inserted in the water line.