JP3664759B2 - Flash prevention device - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a water supply facility such as a steam power plant, and more particularly to a flash prevention device for preventing a deaerator flash phenomenon that occurs in a sudden load drop process such as when a load of a plant is cut off.
[0002]
[Prior art]
In a steam power plant, a flash phenomenon may occur in the deaerator water storage tank due to a sudden load drop when the load of the plant is cut off.
In addition, a flash phenomenon may occur in the deaerator downcomer pipe and the feed water pump connecting pipe when the feed water pump is started up when the unit is started up.
[0003]
This flash phenomenon will be described below with reference to FIG. 7 showing a part of a conventional water supply system.
As shown in FIG. 7, in the conventional water supply equipment, the deaerator 1 and the deaerator water storage tank 2 are installed at a position higher than the water supply booster pump 3 in order to secure the suction pressure of the water supply booster pump 3. . The feed water is led from the condenser (not shown) through the deaerator water level control valve 5 and the low pressure heater 8 to the deaerator 1 from the feed water pipe 17. It is led to the deaerator water storage tank 2. Normally, the water supplied from the condenser is at a temperature substantially equal to the saturation temperature of the internal pressure of the deaerator 1 during plant load operation. This water supply is stored in the deaerator water storage tank 2, and the water supply amount in the deaerator water storage tank 2 is kept constant by the deaerator water level control valve 5. And the water supply in this deaerator water storage tank 2 is pressure | voltage-risen via the water supply booster pump 3, the water supply pump communication pipe 11, and the main water supply pump 4 from the deaerator precipitating pipe 15, and a boiler (not shown) from the supply piping 18 It is configured to be supplied with water. A recirculation pipe 19 is connected to the supply pipe 18 on the downstream side of the main water supply pump 4, and the recirculation pipe 19 is connected to the upper portion of the deaerator water storage tank 2 via the water supply pump recirculation valve 12. ing.
[0004]
Further, a deaerator circulation pipe 20 and a deaerator blow recovery pipe 21 are connected to the deaerator precipitating pipe 15, and the deaerator circulation pipe 20 is connected to the water supply pipe 17 via the deaerator circulation pump 13. The deaerator blow recovery pipe 21 is connected to the downstream side of the low pressure heater 8 and is connected to the condenser via the deaerator blow recovery valve 7.
[0005]
In the above configuration, when a sudden load drop occurs, such as when the load is cut off, the turbine bleeder, which is a heating steam source to the deaerator 1, is cut off, and the internal pressure of the deaerator 1 rapidly decreases. However, the water supply temperature of the deaerator water storage tank 2 becomes higher than the saturation temperature of the internal pressure of the deaerator 1, and a flash phenomenon occurs. Similarly, in the process of shutting down the plant, the decrease in the turbine pressure to the deaerator 1 causes the pressure drop speed to be faster than the feed water temperature drop speed in the deaerator water tank 2. The feed water temperature becomes higher than the saturation temperature of the internal pressure of the deaerator 1 and a flash phenomenon occurs.
[0006]
Conventionally, in order to prevent such a flash phenomenon, as described in Japanese Utility Model Laid-Open No. 53-101101, when the internal pressure of the deaerator 1 is reduced, extraction is performed as a steam source to the deaerator 1. Auxiliary steam was supplied from the auxiliary steam pipe 25 connected to the pipe 24 via the auxiliary steam control valve 9 to prevent a decrease in the internal pressure.
[0007]
[Problems to be solved by the invention]
However, there is a limit to the amount of auxiliary steam that can be used as a steam source for the deaerator, and it is not possible to secure the necessary amount to prevent sudden internal pressure of the deaerator. There was a possibility that the flash phenomenon could not be completely prevented.
[0008]
In addition, when the main feed pump is started, the feed water staying in the deaerator downcomer pipe and feed pump connection pipe is also flushed, and separated into gas and liquid in the pipe, depending on the stop time when the main feed pump is started. There was a possibility that hammering might occur due to the water supply entering the gas section at the time of startup.
[0009]
When such a flush phenomenon occurs, the water level in the deaerator water storage tank becomes unstable, and there is a risk of causing problems such as hammering in the main feed pump trip or deaerator downcomer pipe and feed pump connection pipe due to low water level. there were.
[0010]
The present invention has been made to solve these problems, and it is an object of the present invention to provide a flash prevention device that prevents a flash phenomenon from occurring in a deaerator, a deaerator downpipe, and a feed water pump connecting pipe. .
[0011]
[Means for Solving the Problems]
In order to achieve the above object, the present invention according to claim 1 is directed to deaeration from a deaerator water storage tank in order to prevent a flash phenomenon that occurs in a deaerator, a deaerator downcomer pipe, and a feed pump communication pipe. In a water supply facility that supplies water to the main water supply pump via a condenser precipitator, adjust to a deaerator blow recovery pipe that branches from the deaerator precipitator and is connected to a condenser when a sudden load drop occurs Provided is a flash prevention device which is provided with a valve and performs control to rapidly replace water supplied in a deaerator water storage tank.
[0012]
[Action]
According to the flash prevention device of the present invention as set forth in claim 1, the maximum amount of condensate flow into the deaerator is allowed when a sudden load drop occurs, and the water supply in the deaerator water storage tank is increased. By discharging the water into the condenser, the water supply in the deaerator water storage tank can be replaced in a short time, and the temperature of the water supplied in the deaerator water storage tank can be lowered to prevent the flash phenomenon.
[0013]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a system configuration diagram of a deaerator flush prevention device showing a first embodiment of the present invention. In FIG. 1, the same parts as those in FIG. 7 are denoted by the same reference numerals, and description of the configuration of those parts is omitted. In FIG. 1, the deaerator 1 and the deaerator water storage tank 2 are installed at a position higher than the feed water booster pump 3 in order to secure the suction pressure of the feed water booster pump 3. This configuration is the same as the conventional example, but in the present invention, the feed water in the deaerator water tank 2 is discharged from the middle of the deaerator downcomer pipe 15 extending from the deaerator water tank 2 to the feed booster pump 3 while the plant is stopped. For this purpose, a bypass pipe 22 that bypasses the deaerator blow recovery valve 7 provided in the deaerator blow recovery pipe 21 provided for this purpose is provided in the deaerator blow recovery pipe 21, and the bypass pipe 22 is degassed. An air blow control valve 6 is installed. A high-pressure heater drain recovery pipe 23 is connected to the deaerator water storage tank 2 via a high-pressure heater drain recovery valve 10. Further, a bleed pipe 24 through which bleed air is guided is connected to the deaerator 1, and an auxiliary steam pipe 25 is connected to the bleed pipe 24 via the auxiliary steam control valve 9. With this configuration, this embodiment is controlled as shown in FIG. In FIG. 2, when a load drop occurs, such as when the load is cut off, the water supply in the deaerator water storage tank 2 is normally controlled to a certain level (Block A). The deaerator water level control valve 5a is forcibly fully opened. (Block B), the deaerator blow control valve 6 is shifted from the fully closed state (Block C) to a mode (Block D) for controlling the level in the deaerator water storage tank 2.
[0014]
That is, the deaerator water level control valve 5a is forcibly opened to supply the deaerator 1 and the deaerator water storage tank 2 at the maximum flow rate that allows water to flow. The water supply in the deaerator water storage tank 2 can be replaced in a short time by discharging the water supply in the water storage tank 2. Thus, by replacing the water supply in the deaerator water storage tank 2, the temperature of the water supply in the deaerator water storage tank 2 is lowered, and the water supply in the deaerator water storage tank 2 is reduced to the internal pressure of the deaerator 1. By making the temperature lower than the saturation temperature, the flash phenomenon can be prevented.
[0015]
As shown in FIG. 2, when the signal such as the load cutoff is released, the normal mode is set by the NOT circuits E and F, the deaerator blow control valve 6 is closed, and the deaerator water level control valve 5a is released. It is changed to the water level control of the gas storage tank 2.
[0016]
Next, a second embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a system configuration diagram of the second embodiment of the present invention. Since this configuration is the same as that of the first embodiment, description of the configuration is omitted. In the present invention, as shown in FIG. 3, the high-pressure heater drain water, which is high-temperature water condensed by a high-pressure heater that is arranged upstream of the boiler and raises the temperature of the feed water introduced into the boiler, is recovered in the deaerator water storage tank 2. The high-pressure heater drain collection pipe 23 is normally fully opened (block G), and the high-pressure heater drain collection valve 10 is forcibly closed when a sudden load drop such as load interruption occurs (block H). That is, by preventing the inflow of high-temperature water into the deaerator water storage tank 2, the water supply temperature in the deaerator water storage tank 2 is lowered, and the internal pressure of the deaerator 1 is reduced below the saturation temperature. The flash phenomenon can be prevented.
[0017]
If the load cutoff signal is canceled as shown in FIG. 3, the NOT circuit I enters the normal mode, and the high-pressure heater drain recovery valve 10 is fully opened.
Next, a third embodiment of the present invention will be described with reference to FIG. In FIG. 4, the same parts as those in FIG. 7 are denoted by the same reference numerals, and description of the structure of those parts is omitted.
[0018]
FIG. 4 is a system configuration diagram of the third embodiment of the present invention. In FIG. 4, a feed water pump communication pipe 11 between the feed water booster pump 3 and the main feed water pump 4 includes a feed water pump communication pipe 11 and a deaerator precipitation. The deaerator blow piping 26 which discharges the water supply in the pipe | tube 15 and the deaerator water storage tank 2 is connected via the deaerator blow control valve 6a. The deaerator blow pipe 26 continuously replaces the feed water in the feed water pump communication pipe 11 and the deaerator precipitator pipe 15 by discharging the feed water when the main feed water pump 4 and the feed water booster pump 3 are stopped. That is, the water in the deaerator water storage tank 2 is continuously supplied to the deaerator downcomer pipe 15 and the feed pump communication pipe 11 to prevent the stagnant water from being flushed. Hammering in the downcomer pipe 15 and the feed water pump communication pipe 11 can be prevented.
[0019]
Next, a fourth embodiment of the present invention will be described with reference to FIGS. In FIG. 5, the same parts as those in FIG. 7 are denoted by the same reference numerals, and description of the configuration of those parts is omitted. FIG. 5 is a system configuration diagram of the fourth embodiment of the present invention. In FIG. 5, water is supplied so that the minimum flow rate of the main feed pump 4 can be secured from the outlet side supply pipe 18 of the main feed pump 4 to the deaerator water storage tank 2. A circulation valve bypass pipe 27 that bypasses the feed water pump recirculation valve 12 is connected to the feed water pump recirculation pipe 19 that discharges water, and a deaerator circulation pump 28 is connected to the deaerator circulation pump through the inlet valves 16 and 14. It is installed.
[0020]
The control circuit of the fourth embodiment having the above arrangement will be described with reference to FIG.
While the main feed pump 4 and the feed booster pump 3 are stopped, the deaerator circulation pump inlet / outlet valves 16 and 14 are fully opened, and the deaerator circulation pump 28 is activated (block J). When the main feed pump 4 or the feed booster pump 3 is activated, the deaerator circulation pump inlet / outlet valves 16 and 14 are fully closed, and the feed water is controlled by the feed water pump recirculation valve 12 (block K). In the figure, L indicates an AND circuit, and M indicates a NOT circuit.
[0021]
Therefore, by operating the deaerator circulation pump 28 while the main feed water pump is stopped, the feed water in the deaerator water storage tank 2 is passed through the deaerator downcomer pipe 15 and the feed water pump communication pipe 11 to stay. This prevents water flushing and prevents the hammering phenomenon when the main feed pump is activated.
[0022]
【The invention's effect】
As described above, according to the first aspect of the present invention, the feed water temperature in the deaerator water storage tank can be maintained at the saturation temperature drop of the deaerator pressure, and a sudden load drop such as load cutoff Sometimes flushing in the deaerator water tank can be prevented.
[Brief description of the drawings]
FIG. 1 is a system configuration diagram of a flash prevention apparatus showing first and second embodiments of the present invention.
FIG. 2 is a control circuit diagram applied to the first embodiment of the present invention.
FIG. 3 is a control circuit diagram applied to a second embodiment of the present invention.
FIG. 4 is a system configuration diagram of a flash prevention apparatus showing a third embodiment of the present invention.
FIG. 5 is a system configuration diagram of a flash prevention apparatus showing a fourth embodiment of the present invention.
FIG. 6 is a control circuit diagram applied to a fourth embodiment of the present invention.
FIG. 7 is a system configuration diagram showing a conventional example of a flash prevention device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Deaerator 2 ... Deaerator water storage tank 3 ... Feed water booster pump 4 ... Main feed water pump 5, 5a ... Deaerator water level control valve 6, 6a ... Deaerator blow control valve 7 ... Deaerator blow recovery valve DESCRIPTION OF SYMBOLS 8 ... Low pressure heater 9 ... Auxiliary steam control valve 10 ... High pressure heater drain recovery valve 11 ... Feed water pump communication pipe 12 ... Feed water pump recirculation valve 13, 28 ... Deaerator circulation pump 14 ... Deaerator circulation pump outlet valve 15 ... Desorption Degasifier pipe 16 ... Deaerator circulation pump inlet valve 17 ... Water supply pipe 18 ... Supply pipe 19 ... Recirculation pipe 20 ... Deaerator circulation pipe 21 ... Deaerator blow recovery pipe 22 ... Bypass pipe 23 ... High-pressure heater drain recovery Pipe 24 ... Extraction pipe 25 ... Auxiliary steam pipe 26 ... Deaerator blow pipe 27 ... Circulation valve bypass pipe

Claims (1)

A deaerator that guides the water supply from the condenser through the water supply pipe and degass the water supply, a deaerator water storage tank that stores the water degassed by the deaerator, and the deaerator water storage tank The deaerator downcomer pipe connected to the lower part of the degasser and leads the water supply to the boiler, and the water in the deaerator water storage tank branched from the deaerator downcomer pipe is passed through the deaerator blow recovery valve when the system is stopped. the degassing said and recovery Datsukiki blow recovery pipe leading to the water vessel, wherein disposed in the connected bypass pipe a deaerator blow recovery valve bypassing the deaerator blow recovery pipe under load cutoff occurs Te A deaerator blow control valve that is controlled to open and close according to the water level of the storage tank, and is controlled to open and close according to the water level of the deaerator storage tank that is connected to the water supply pipe and is normally operated, and is fully opened when load interruption occurs. A deaerator water level control valve Flash prevention device.

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