JPH08170805A - Flashing-proof equipment - Google Patents

Abstract

PURPOSE: To prevent a flashing phenomenon in a deaerator storage tank at the time of a sudden drop of a load by replacing feed water in the deaerator storage tank quickly by a deaerator blow control valve at that time. CONSTITUTION: In the case when a drop of a load occurs at the time of load shutdown or the like, feed water is supplied at the largest possible flow rate to a deaerator 1 and a deaerator storage tank 2 by opening a deaerator level valve 5a and the feed water in the deaerator storage tank 2 is discharged by a deaerator blow control valve 6, whereby the feed water in the deaerator storage tank 2 is replaced in a short time. by replacing the feed water in the deaerator storage tank 2 in this way, the temperature of the feed water therein is lowered to a saturation temperature under the pressure inside the deaerator 1 or below. Thereby a flashing phenomenon in the deaerator storage tank 2 can be prevented at the time of a sudden drop of the load at the load shutdown or the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water supply facility such as a steam power plant, and more particularly to a deaerator flash phenomenon that occurs during a sudden load drop process such as when the load of the plant is cut off, and a deaerator that occurs when the unit is restarted. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flash prevention device for preventing a flash phenomenon of an aerial downcomer pipe and a water supply pump connecting pipe.

[0002]

2. Description of the Related Art In a steam power plant, a flash phenomenon may occur in a deaerator water storage tank due to a sudden load drop such as when the load of the plant is cut off. In addition, a flush phenomenon may occur in the deaerator downcomer pipe and the water supply pump connecting pipe when the water supply pump is activated when the unit is activated.

This flush 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 facility, 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. . Water is supplied from a condenser (not shown) through a deaerator water level control valve 5 and a low-pressure heater 8 to a dewaterer 1 from a water supply pipe 17.
The water supplied to the deaerator 1 is introduced into the deaerator water storage tank 2. Normally, the feed water introduced from the condenser is at a temperature substantially equal to the saturation temperature of the internal pressure of the deaerator 1 during the 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 the deaerator water storage tank 2 is boosted from the deaerator downcomer pipe 15 through the water supply booster pump 3, the water supply pump connecting pipe 11, and the main water supply pump 4 to the boiler (not shown) from the supply pipe 18. It is configured to be. A recirculation pipe 19 is provided downstream of the main water supply pump 4 of the supply pipe 18.
The recirculation pipe 19 is connected to the upper part of the deaerator water storage tank 2 via the water supply pump recirculation valve 12.

Further, a deaerator circulation pipe 20 and a deaerator blow recovery pipe 21 are connected to the deaerator downfall pipe 15, and the deaerator circulation pipe 20 is supplied with water via a deaerator circulation pump 13. The pipe 17 is connected to the downstream side of the low-pressure heater 8, and the deaerator blow recovery pipe 21 is connected to the condenser via the deaerator blow recovery valve 7.

In the above construction, when a sudden load drop occurs, for example, when the load is cut off, the turbine bleed air, which is the heating steam source to the deaerator 1, is cut off and the internal pressure of the deaerator 1 is reduced. The water temperature of the deaerator water storage tank 2 suddenly drops and becomes higher than the saturation temperature of the internal pressure of the deaerator 1,
Flash phenomenon occurs. Similarly, in the process of shutting down the plant, the depressurization speed of the turbine inside the deaerator water tank 2 is faster than that of the feed water temperature inside the deaerator water storage tank 2 due to the reduction of turbine bleed air to the deaerator 1. The feed water temperature becomes higher than the saturation temperature of the internal pressure of the deaerator 1, and a flash phenomenon occurs.

Conventionally, in order to prevent such a flash phenomenon, as described in Japanese Utility Model Application Laid-Open No. 53-101101, when the internal pressure of the deaerator 1 drops, steam to the deaerator 1 Auxiliary steam pipe 2 connected to extraction pipe 24 as a source
Auxiliary steam was supplied from No. 5 through the auxiliary steam control valve 9 to prevent the internal pressure from decreasing.

[0007]

However, there is a limit to the amount of auxiliary steam used as a steam source for the deaerator, and it is not possible to secure the necessary amount for preventing a sudden deaerator internal pressure, so that the deaerator cannot be degassed. It was not possible to completely prevent a decrease in the pressure inside the airway, and there was a risk of a flash phenomenon.

Further, when the main water supply pump is started, the water supply accumulated in the deaerator downcomer pipe and the water supply pump connecting pipe is also flushed, separated into gas and liquid in the pipe, and stopped when the main water supply pump is started. Depending on the time, there was a possibility of hammering due to the rush of water supply to the gas portion at the time of startup.

When such a flush phenomenon occurs, the water level of the deaerator water storage tank becomes unstable, and the low water level causes troubles such as hammering in the main water supply pump trip or the deaerator downcomer pipe and the water supply pump connecting pipe. There was a risk of causing it.

The present invention has been made in order to solve these problems, and provides a flash prevention device which prevents a flash phenomenon from occurring in a deaerator, a deaerator downcomer pipe, and a water supply pump connecting pipe. Especially.

[0011]

In order to achieve the above object, the present invention according to claim 1 is intended to prevent a flash phenomenon which occurs in a deaerator, a deaerator downcomer pipe, and a water supply pump connecting pipe. , In the water supply equipment that supplies water from the deaerator water storage tank to the main feed pump via the deaerator downcomer, if a sudden load drop occurs, branch from the deaerator downcomer and connect to the condenser. A control valve is provided in the deaerator blow recovery pipe, and a flash prevention device is provided for performing control for rapidly replacing the water supply in the deaerator water storage tank. Further, in the present invention according to claim 2, a sudden load is provided. The present invention according to claim 3 provides a flush prevention device for forcibly closing the recovery of the high-pressure heater drain to the deaerator when a drop occurs, and in the present invention according to claim 3, the water supply pump while the main water supply pump and the water supply booster pump are stopped. It's a connecting pipe The deaerator blow pipe for recovering water to the condenser is provided, provides deaerator downcomers, and the flash preventing device for continuously replacing the feed water feed water pump connection tube,
In the present invention according to claim 4, the main water supply pump recirculation line for constantly replacing the water supply in the deaerator downcomer pipe and the water supply pump communication pipe while the main water supply pump and the water supply booster pump are stopped is provided with the deaerator circulation pump. Provided is a flash prevention device characterized by being provided through

[0012]

According to the flash prevention device of the present invention having the above-mentioned structure, the degasser water storage tank can be set to the maximum allowable amount of condensate flowing into the deaerator when a sudden load drop occurs. The temperature of the feed water in the deaerator water storage tank is lowered by discharging the water supply in the deaeration water storage tank in a short time by discharging the water supply in the condenser to the condenser, and further, in the present invention according to claim 2, By shutting off the high temperature drain flowing into the deaerator, the temperature of the feed water in the deaerator water storage tank is decreased in temperature faster, and in the present invention according to claims 3 and 4, the deaerator downcomer pipe and the water feed pump are provided. The flush phenomenon can be prevented by constantly replacing the water supply in the connecting pipe.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a system configuration diagram of a deaerator flash prevention device showing a first embodiment of the present invention. In FIG. 1,
The same parts as those in FIG. 7 are designated by the same reference numerals, and the description of the structure of those parts will be omitted. In FIG. 1, 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. Although this configuration is the same as the conventional example, in the present invention, the water supply in the deaerator water storage tank 2 is discharged from the middle of the deaerator downcomer pipe 15 from the deaerator water storage tank 2 to the water supply booster pump 3 while the plant is stopped. A bypass pipe 22 that bypasses the deaerator blow recovery valve 7 provided in the deaerator blow recovery pipe 21 is provided in the deaerator blow recovery pipe 21 and is connected to the bypass pipe 22. The air blow control valve 6 is installed. And the deaerator water storage tank 2
A high pressure heater drain recovery pipe 23 is connected to the high pressure heater drain recovery valve 10 via a high pressure heater drain recovery valve 10. Furthermore, deaerator 1
A bleed air pipe 24 through which bleed air is guided is connected to, and an auxiliary steam pipe 25 is connected to the bleed air pipe 24 via an auxiliary steam control valve 9. With this configuration, the present embodiment is controlled as shown in FIG. In FIG. 2, when a load drop occurs when the load is cut off, the water supply in the deaerator water storage tank 2 is normally controlled to a constant level (block A), and the deaerator water level control valve 5a is forcibly fully opened. (Block B), the deaerator blow control valve 6 is moved from the fully closed state (Block C) to the mode for controlling the level in the deaerator water storage tank 2 (Block D).

That is, by forcibly opening the deaerator water level control valve 5a, the deaerator 1 and the deaerator water storage tank 2 are supplied at the maximum flow rate for supplying water, and the deaerator blow control valve 6 is supplied. By discharging the water supply in the deaerator water storage tank 2 by this, the water supply in the deaerator water storage tank 2 can be replaced in a short time. By replacing the water supply in the deaerator water storage tank 2 in this way, 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 adjusted to the internal pressure of the deaerator 1. The flash phenomenon can be prevented by keeping the temperature below the saturation temperature.

As shown in FIG. 2, when the signal such as load cutoff is released, the normal mode is set by the NOT circuits E and F, and the deaerator blow control valve 6 is closed, and the deaerator water level control valve is closed. 5a is changed to the water level control of the deaerator water storage tank 2.

Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a system configuration diagram of a second embodiment of the present invention. Since this configuration is the same as that of the first embodiment, the description of the configuration will be omitted. In the present invention, as shown in FIG. 3, high-pressure heater drain water, which is high-temperature water condensed by a high-pressure heater arranged upstream of the boiler to raise the temperature of the feed water introduced into the boiler, is collected in the deaerator water storage tank 2. The high-pressure heater drain recovery pipe 10 is disposed in the high-pressure heater drain recovery pipe 23 and is normally fully open (block G), and the high-pressure heater drain recovery valve 10 is forcibly closed when a sudden load drop such as load cutoff occurs (block H). That is, by preventing the high temperature water from flowing into the deaerator water storage tank 2, the feed water temperature in the deaerator water storage tank 2 can be reduced and the internal pressure of the deaerator 1 can be made equal to or lower than the saturation temperature. The flash phenomenon can be prevented.

If the load cutoff signal is released 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 designated by the same reference numerals, and the description of the structure of those parts will be omitted.

FIG. 4 is a system configuration diagram of a third embodiment of the present invention. In FIG. 4, the water supply pump communication pipe 11 between the water supply booster pump 3 and the main water supply pump 4 is connected to the water supply pump communication pipe 11. An aerator downcomer 15 and a deaerator blow pipe 26 for discharging the water supply in the deaerator water storage tank 2 are connected via a deaerator blow control valve 6a. The deaerator blow pipe 26 discharges the water supply when the main water supply pump 4 and the water supply booster pump 3 are stopped, thereby constantly replacing the water supply in the water supply pump connecting pipe 11 and the deaerator downcomer pipe 15. That is, continuous flushing of the water supply in the deaerator water storage tank 2 to the deaerator downcomer pipe 15 and the water supply pump connecting pipe 11 prevents flushing of stagnant water, and deaeration at the time of starting the main water supply pump 4 and the water supply booster pump 3. It is possible to prevent hammering in the vessel downcomer pipe 15 and the water supply pump connecting pipe 11.

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 designated by the same reference numerals, and the description of the structure of those parts will be omitted. FIG. 5 is a system configuration diagram of a fourth embodiment of the present invention. In FIG. 5, water is supplied from the outlet side supply pipe 18 of the main water supply pump 4 to the deaerator water storage tank 2 so that the minimum flow rate of the main water supply pump 4 can be secured. A circulation valve bypass pipe 27 that bypasses the water supply pump recirculation valve 12 is connected to the water supply pump recirculation pipe 19 that discharges water, and the deaerator circulation pump outlet and inlet valves 16 and 1 are connected.
A deaerator circulation pump 28 is installed via the No. 4 unit.

The control circuit of the fourth embodiment having the above-mentioned structure will be described with reference to FIG. Deaerator circulation pump inlet / outlet valve 1 while main water supply pump 4 and water supply booster pump 3 are stopped
6 and 14 are fully opened, and the deaerator circulation pump 28 is started (block J). Further, when the main water supply pump 4 or the water supply booster pump 3 is activated, the deaerator circulation pump inlet / outlet valve 1
6, 14 are fully closed, and the water supply is controlled by the water supply pump recirculation valve 12 (block K). In the figure, L indicates an AND circuit and M indicates a NOT circuit.

Therefore, by operating the deaerator circulation pump 28 while the main water supply pump is stopped, the deaerator water storage tank 2
The water supply inside is a deaerator downcomer pipe 15 and a water supply pump connecting pipe 11
By passing water through the tank, it is possible to prevent flushing due to accumulated water and prevent a hammering phenomenon when the main water supply pump is started.

[0022]

As described above, according to the present invention according to claims 1 to 2, the feed water temperature in the deaerator water storage tank can be maintained at the saturation temperature decrease of the deaerator pressure. ,
It is possible to prevent the flushing phenomenon in the deaerator water storage tank during a sudden load drop such as load cutoff.

Further, according to the present invention according to claims 3 to 4, the flush phenomenon is prevented by constantly passing water through the deaerator downcomer pipe and the feedwater pump connecting pipe, and the feedwater flow rate is low due to the flush phenomenon. It is possible to prevent equipment damage due to serious accidents and hammering and to carry out stable plant operation.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of a flash prevention device 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 device showing a third embodiment of the present invention.

FIG. 5 is a system configuration diagram of a flash prevention device 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]

 1 ... Deaerator 2 ... Deaerator water storage tank 3 ... Water supply booster pump 4 ... Main water supply pump 5, 5a ... Deaerator water level control valve 6, 6a ... Deaerator blow control valve 7 ... Deaerator blow recovery valve 8 ... Low-pressure heater 9 ... Auxiliary steam control valve 10 ... High-pressure heater drain recovery valve 11 ... Water supply pump connecting pipe 12 ... Water supply pump recirculation valve 13, 28 ... Deaerator circulation pump 14 ... Deaerator circulation pump outlet valve 15 ... Desorption Vaporizer down 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 Piping 24 ... Extraction piping 25 ... Auxiliary steam piping 26 ... Deaerator blow piping 27 ... Circulation valve bypass piping

Claims (4)

[Claims] 1. A deaerator for guiding water supply from a condenser through a water supply pipe to deaerate the water supply, a deaerator water storage tank for storing the water supply deaerated by the deaerator, A deaerator down pipe which is connected to the lower part of the deaerator water storage tank and which guides the feed water to the boiler, and a deaerator down water pipe which is arranged branching from this deaerator water down tank when the system is stopped. It is arranged in a deaerator blow recovery pipe that leads to the condenser via a blow recovery valve, and a bypass pipe that bypasses the deaerator blow recovery valve and is connected to the deaerator blow pipe. A deaerator blow control valve that is controlled to open / close according to the water level of the deaerator water storage tank and open / close control according to the water level of the deaerator water storage tank connected to the water supply pipe during normal operation to cause system load interruption It consists of a deaerator water level control valve which is sometimes fully controlled. Characteristic flash prevention device. 2. A deaerator for guiding water supply from a condenser through a water supply pipe to deaerate the water supply, a deaerator water storage tank for storing the water supply deaerated by the deaerator, and a boiler. High-pressure heater drain pipe that guides the high-pressure heater drain generated from the high-pressure heater that raises the feed water introduced into the degasser water storage tank, and the high-pressure heater drain recovery valve that is connected to this high-pressure heater drain recovery pipe and is fully closed when load interruption occurs And a flash prevention device. 3. A deaerator for guiding water supply from a condenser through a water supply pipe to deaerate the water supply, a deaerator water storage tank for storing the water supply deaerated by the deaerator, Branch from the water supply booster pump and main water supply pump that raise the pressure of the water supply that has been drawn out from below the deaerator water storage tank through the piping and send it to the boiler, and the water supply pump connecting pipe that connects this water supply booster pump and the main water supply pump. And a deaerator blow pipe for guiding the water in the deaerator water storage tank to the condenser through the deaerator blow control valve when the water supply booster pump and the main water supply pump are stopped. Flash protection device. 4. A deaerator for guiding water from a condenser through a water supply pipe to deaerate the water, a deaerator water storage tank for storing the water deaerated by the deaerator, A feed water booster pump and a main feed pump that raise the pressure of the feed water derived from below the deaerator water storage tank via a pipe and send it to the boiler, and a branch from the pipe on the downstream side of this main feed pump through a feed pump recirculation valve. And a recirculation pipe for recirculating the water supply to the deaerator water storage tank, and this recirculation pipe is installed by bypassing the water supply pump recirculation valve to start water supply when the water supply booster pump and the main water supply pump are stopped. A flash prevention device comprising a deaerator circulation pump leading to the deaerator water storage tank.