JP3317536B2 - Saturated drain discharge piping system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a saturated drain discharge piping system having a heat exchanger and the like used in power generation equipment and the like.

[0002]

2. Description of the Related Art In a power generation facility, a heat exchanger or the like is provided for the purpose of improving the thermal efficiency of a plant. The heat exchanger and the like are a feed water heater, a moisture separator, a moisture separator and a drain tank thereof, and are disposed in a saturated drain discharge piping system.

That is, FIG. 3 is a schematic system example of a power generation facility of a nuclear power plant, in which main steam generated in a nuclear reactor 1 is guided to a high-pressure turbine 3 via a main steam pipe 2, and heat energy is converted into rotational energy. Is converted. High pressure turbine 3
Is passed through a cross-around pipe 4 to a moisture separator / heater 5 where the moisture is removed therefrom, further heated and passed through a cross-around pipe 6 to a low-pressure turbine 7. The steam that has finished its work in the low-pressure turbine 7 is condensed in the condenser 8 to be condensed, and after being pressurized by the condensate pump 9, is sent to the water supply pump 11 through the low-pressure water heater 10. Water supply pump 11
The condensed water further increased in pressure is supplied to the reactor 1 as feed water through a high-pressure feed water heater 12.

A moisture separation element 13, a first-stage heating heat transfer tube 14 and a second-stage heating heat transfer tube 15 are provided in the main body of the moisture separation heater 5. The extracted steam from the high-pressure turbine 3 is supplied to the heat transfer tube 14 via a conduit 16, and a part of the main steam is supplied to the second-stage heating heat transfer tube 15 via a conduit 17. And, the two heat transfer tubes 14, 15
The heated steam exchanged in the above is collected in the heated steam drain tanks 20 and 21 through the heated steam drain pipes 18 and 19, and is recovered to the high-pressure feed water heater 12 and the like while controlling the water level.

[0005] Heat exchange is performed between the heating steam flowing through the heat transfer tubes, which are respectively guided to the first-stage heating heat transfer tubes 14 and the second-stage heating heat transfer tubes 15, and the outside thereof.

That is, the cycle steam having a humidity of about 12% (at the rated load of the plant) at the outlet of the high-pressure turbine, after most of the moisture is removed by the moisture separating element 13, is transferred to the first stage heating transfer. The heat pipe 14 is successively guided to the second-stage heating heat transfer pipe 15, and during this time, becomes superheated steam heated by the heating steam, and is sent to the low-pressure turbine. On the other hand, the heated steam is deprived of heat by the cycle steam and condensed, and is discharged from the moisture separation heater 5 to the heated steam drain tanks 20 and 21 as a drain.

The heating steam drain tanks 20, 21 are provided with water level controllers 26, 27, and by controlling the opening of the water level control valves 28, 29 by signals from the water level controllers 26, 27, The water level in the heated steam drain tanks 20, 21 is controlled.

[0008]

However, when the turbine load is interrupted during the operation of the plant, it is necessary to increase the turbine load as quickly as possible. That is, it is necessary to restart the turbine while the load is interrupted, particularly at a high temperature, so that there is a problem in the conventional water level adjustment of a heat exchanger or the like when the turbine load is interrupted.

When the turbine load is cut off during the operation of the plant, the steam flowing into the high-pressure turbine 3 stops, and the pressure in the moisture separation heater 5 and the feed water heaters 12A, 12B, 10A, 10B decreases. Due to the pressure drop of the feed water heater or the like, for example, the drains in the drain pipes 18A, 18B, 18C, and 18D are saturated drains, so that flash occurs. On the other hand, control valve 29
In A and 29B, since the steam to the feed water heater or the like stops, no drain is generated and the operation is performed in the closing direction. If the drain pipe 18 has a check valve 43 necessary for the system, the flashed steam is sealed in the pipes 18C and 18D.

When the plant is restarted in this state, low-pressure steam flows into the heat exchanger and the like, and a low-temperature drain is generated and flows into the drain pipes 18C and 18D. However, since the drain pipes 18C and 18D contain the flashed relatively high-temperature steam, the drain pipes 18C and 18D come into contact with the low-temperature drain and rapidly drain.

At this time, the hammer phenomenon occurs due to the sudden decrease in volume. This hammer phenomenon causes the piping system to vibrate violently, and in severe cases, may cause damage to the piping system.

SUMMARY OF THE INVENTION In view of the foregoing, an object of the present invention is to prevent a hammer phenomenon in a saturated drain discharge pipe of a feed water heater or the like, thereby enabling a sound operation even when a turbine load is cut off. A saturated drain discharge piping system is provided.

[0013]

SUMMARY OF THE INVENTION According to the present invention, a control valve for a saturated drain discharge pipe such as a feed water heater is forcibly opened when a turbine load is cut off, or when the turbine is started, the control valve is opened after the turbine is restarted. Control to maintain the load until it reaches a certain load, and connect a piping system with a downward slope from the feed water heater etc. to the next stage heat exchanger, etc., or a piping with a control valve from the bottom of the piping to the condenser. It features a piping system.

[0014]

[Function] Forcibly open the control valve of the saturated drain discharge pipe such as the feed water heater when the turbine load is cut off, or start the turbine.
By controlling the opening of the control valve during operation until a certain load is reached after restarting the turbine, it is possible to discharge flash steam generated when the turbine load is cut off to the next-stage feed water heater or the like. Also, if there is a piping system that does not have a rising pipe shape that makes it difficult to discharge flash steam, or if there is a rising piping shape that makes it difficult to discharge flash steam, the piping that connects the control valve to the condenser Flash steam can be reliably discharged by the system.

[0015]

An embodiment of the present invention will be described below with reference to FIG.

In FIG. 1, the saturated drain generated in the feed water heater 45 is discharged to the next-stage exchanger 12 through the pipe 18.
The pipe 18 is piped with a downward gradient from the heat exchanger 45 to the next-stage heat exchanger 12, and the control valve 29 A and the check valve 43
A is installed.

When the turbine load interruption occurs, a signal 37 corresponding to the turbine load interruption or load interruption is input to the water level controller 26, so that the control valve 29A is independent of the signal of the water level detector 36 of the heat exchanger 45. Opens. On the other hand, 18
The drain in B and 18C causes a flash phenomenon due to a decrease in the internal pressure of the heat exchanger 45 and the next stage heat exchanger 12 due to the interruption of the turbine load, and the control valve 29A is opened as described above. Flows into the heat exchanger 12 while expanding the volume. Further, since the pipe 18 has a downward slope, there is no accumulation of flash steam in the middle of the pipe 18. Therefore, after the turbine load is cut off, the internal pressure of the pipe 18 becomes the same pressure as that of the next stage heat exchanger, and since the internal temperature is saturated steam, there is no high temperature steam that may cause a hammer phenomenon. The hammer phenomenon does not occur even if water flows in. FIG. 2 shows an embodiment in which there is an uphill flow path in the middle of the pipe 18, and the control valve 41 of the control valve control system according to the present invention.
To the condenser 8 having a pipe 40.

The rising portion 3 is connected to the pipe 18 by the pipe 40.
Even if there is 9, the drain in the pipe is completely discharged by the control valve 41 after the turbine load is cut off, and as a result, the inside of the pipe 18 has the same pressure as that of the next stage feed water heater 12 and the saturation temperature, and the hammer phenomenon occurs. Since there is no high-temperature steam to be generated, the hammer phenomenon does not occur even if a low-temperature drain at the restart of the turbine flows in. In addition, in the configuration of FIG. 1 and FIG.
When the turbine starts, the control valve is
Is opened to a certain load by a signal corresponding to the turbine load.
Control.

[0019]

By discharging the flash steam to the next-stage feed water heater, the fluid temperature in the saturated drain discharge pipe can be kept at the same low temperature as the next-stage feed water heater at the same time as the turbine restart. The hammer phenomenon caused by the inflow of the drain having a low temperature at the time of starting can be prevented.

[Brief description of the drawings]

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

FIG. 2 is a system diagram showing another embodiment of the present invention.

FIG. 3 is a system diagram showing a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Reactor, 2 ... Main steam pipe, 3 ... High pressure turbine, 4 ... Cross around pipe, 5 ... Moisture separation heater, 6 ... Cross around pipe, 7 ... Low pressure turbine, 8 ... Condenser, 9 ... Condenser Water pump, 10… low pressure feed water heater, 11… reactor feed pump,
12: high pressure feed water heater, 13: moisture separation element, 14: first heat transfer tube, 15: second heat transfer tube, 16: extraction tube,
17 ... Main steam conduit, 18,19 ... Drain pipe, 20,21 ... Drain tank, 26,27,36 ... Water level control device, 37 ... Turbine load cutoff signal, 38 ... Turbine load signal, 39 ... Rise pipe, 40
... drain drain pipe, 41 ... regulating valve, 43 ... check valve, 45 ... heat exchanger, etc.

Claims (4)

(57) [Claims] 1. A saturated drain discharge piping system having a feed water heater or a moisture separator or a moisture separator and a heat exchanger such as a drain tank thereof in a power generation facility,
A check valve and a first control valve are provided in order from the upstream side in the system from the upstream heat exchanger to the next heat exchanger.
A system connected between the stop valve and the first control valve and connected to the condenser from the bottom of the pipe via a second control valve;
The saturated drain discharge piping system, wherein the second control valve is controlled to open by a load cutoff or a signal corresponding to the load cutoff when the load on the turbine is cut off. 2. A saturated drain discharge piping system having a feed water heater or a moisture separator or a moisture separator and a heat exchanger such as a drain tank thereof in a power generation facility,
A check valve and a first control valve are provided in order from the upstream side in the system from the upstream heat exchanger to the next heat exchanger.
A system connected between the stop valve and the first control valve and connected to the condenser from the bottom of the pipe via a second control valve;
The saturated drain discharge piping system, wherein the second control valve is opened to a certain load by a turbine load or a signal corresponding to the turbine load when the turbine is started. 3. A feed water heater or a moisture content in a power generation facility.
Separators or moisture separation heaters and their drain tanks, etc.
In a saturated drain discharge piping system having a heat exchanger, etc.,
Reverse in the system from the upstream heat exchanger etc. to the next heat exchanger etc.
A stop valve and a control valve are provided in order from the upstream side,
From the heat exchanger to the next heat exchanger, etc.
In addition, the control valve operates when the load of the turbine is interrupted.
Open control by a signal equivalent to disconnection or load shedding
Features a saturated drain discharge piping system. 4. A feed water heater or a moisture content in a power generation facility.
Separators or moisture separation heaters and their drain tanks, etc.
In a saturated drain discharge piping system having a heat exchanger, etc.,
Reverse in the system from the upstream heat exchanger etc. to the next heat exchanger etc.
A stop valve and a control valve are provided in order from the upstream side,
From the heat exchanger to the next heat exchanger, etc.
In addition, the control valve operates at the time of turbine start-up.
Or open to a certain load by a signal corresponding to turbine load
A saturated drain discharge piping system, characterized in that: