JP2003193807A - Water induction preventive device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water induction preventive device to settle a problem of closing of a cutoff valve even at the time of no water induction in a steam turbine stopping process, etc., at a steam turbine plant for electric power generation of water induction preventive constitution provided with the cutoff valve against the case when water leakage occurs due to breakage of a water feed tube, etc. <P>SOLUTION: This water induction preventive device is devised to close the cutoff valve in the case when a water level in a drain pot 15 exceeds a specified water level by detecting the water level of this drain pot 15 by providing the drain pot 15 in the middle of an inflow conduit pipe to prevent back flow of water of water feed heater 12, etc., to the inside of the stream turbine 11 for electric power generation. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a watertaction prevention device in a steam turbine plant for power generation.

[0002]

2. Description of the Related Art In a steam turbine plant for power generation,
The condenser, feed water heater, and deaerator are important heat exchangers.
The condenser condenses the exhaust steam of the steam turbine for power generation and maintains the back pressure of the turbine in a vacuum to improve the efficiency of the steam turbine plant for power generation, and at the same time, collects the condensed and condensed water to generate power again. It is installed for the purpose of using it for the steam turbine cycle. The feed water heater is installed for the purpose of improving the thermal efficiency of the steam turbine plant for power generation by heating the condensate and the feed water using the extracted air of the steam turbine for power generation. The deaerator separates and removes the non-condensed gas in the boiler feed water by heating the extraction water of the steam turbine for power generation by directly contacting with the feed water, that is,
It is installed for the purpose of degassing and preventing equipment corrosion.

In such a steam turbine plant for power generation, when a water supply tube arranged in a condenser, a feed water heater, and a deaerator is broken and leaks occur, the leaked water rises in an extraction pipe. However, water will enter the steam turbine for power generation. This phenomenon is called water induction, which causes damage to moving blades, stationary blades, rotors, etc. of the steam turbine for power generation.

The conventional method will be described below with reference to FIG. 3 by taking a feed water heater as an example. In FIG. 3, a steam turbine 31 for power generation, a feed water heater 32, and a steam turbine 31 for power generation
Extraction pipe 33 flowing into the feed water heater 32 from the water supply pipe, a shutoff valve 34 provided in the middle of the pipe, and a water level detector 35 and a water level detector 35 for measuring the water level of the feed water heater 32. A water intake prevention circuit 36 is installed to give a command to the shutoff valve 34 based on the water level in the feed water heater 32 obtained from the above.

In such a steam turbine plant for power generation, the water level in the feed water heater 32, which is the source of the inflow of water into the steam turbine 31 for power generation, is determined by the water level detector 3 in the feed water heater.
5 is constantly monitored, and when the water level rises above the dangerous water level, the shutoff valve 34 is fully closed according to a command from the water intake prevention circuit 36, and the inflow conduit between the steam turbine 31 for power generation and the feedwater heater 32 is shut off. It was a method of doing.

According to the conventional method, the amount of steam flowing from the steam turbine 31 for power generation into the condenser, feed water heater and deaerator in the normal state and the drain tank from the condenser, feed water heater and deaerator are used. Although the amount of exhaust gas discharged to, etc. is balanced and controlled to maintain a constant water level, the water supply tubes inside the condenser, feed water heater, and deaerator are damaged, causing water leakage. If you do, condenser, water heater,
The water level inside the deaerator rises abnormally. Then, the water level detector inside the feed water heater detects that the dangerous water level has been reached, and the shutoff valve 34 in the middle of the pipeline is fully closed according to a command from the water intake prevention circuit 36 to prevent reaching water intake. It was a thing.

[0007]

However, the water level in the condenser, the feed water heater, and the deaerator may rise to the dangerous water level other than during the water induction. For example, in the process of stopping the steam turbine for power generation, the amount of steam flowing into the steam turbine for power generation may suddenly change and the internal pressures of the two may reverse, which affects the condenser, feed water heater, and deaerator. The water level of may rise to the dangerous water level. Therefore, this method has a problem that it is fully closed except when a water induction occurs.

The mechanical principle leading to the generation of water induction is that the condenser, the feed water heater and the deaerator, when the pressure in the condenser becomes higher than the pressure in the steam turbine for power generation, the condenser, the feed water heater. The water in the deaerator flows back into the steam turbine for power generation. Therefore, the present invention provides a drain pot in the middle of the steam inflow line to detect the water level of the drain pot, and retains the basic function of the water tide prevention function, while preventing the shutoff valve from being fully closed except when water tide induction occurs. The purpose is to do.

[0009]

A watertight induction prevention device according to the present invention is a power generation steam turbine plant having a shut-off valve installed in the middle of a steam inflow line between a power generation steam turbine and a feedwater heater, A drain pot is provided in the middle of the steam inflow line, and a water level detector in the drain pot for detecting the water level of the drain pot and the shutoff valve is closed based on the detection result of the water level detector in the drain pot Is the gist.

Further, in the water intake prevention device according to the present invention, the feed water heater is provided with a water level detector in the feed water heater, and both detection results of the water level detector in the feed water heater and the water level detector in the drain pot are detected. The gist is that the shut-off valve is closed based on the above.

Further, the water intake prevention device according to the present invention is characterized in that a check valve is provided between the steam inflow line and the drain pot.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of the present invention will be described below with reference to FIG. 1 by taking a feed water heater as an example. In FIG. 1, there are a steam turbine 11 for power generation, a feed water heater 12, and an extraction pipe 13 that flows into the feed water heater 12 from the steam turbine 11 for power generation, and a shutoff valve 14 provided midway in the pipeline. Further, a drain pot 15 is provided between the shutoff valve 14 and the feed water heater 12, and a drain pot water level detector 16 for measuring the water level in the drain pot 15 is provided.
A water-tightening prevention circuit 18 for giving a command to the shutoff valve 14 and the drain discharge on / off valve 17 based on the detection signal obtained from the above is installed.

In the above structure, the water intake prevention circuit 18 constantly monitors the value of the water level detector 16 in the drain pot, and when the water level in the drain pot 15 rises above the safe water level, the water induction prevention circuit 18 is provided.
The shutoff valve 14 is fully closed and a full open command is output to the drain discharge on / off valve 17 to shut off the inflow pipe between the steam turbine 11 for power generation and the feedwater heater 12 and to drain the drain pot 15. This is a method of fully opening the drain discharge line to prevent water induction.

Although the drain pot 15 is provided in the middle of the pipe between the extraction ports 3, a check valve 20 is provided at the branch point between the extraction port 3 and the drain port 15. As a result,
Only the water from the feed water heater 12 to the steam turbine 11 for power generation is allowed to flow into the drain pot 15.

Next, a second embodiment of the present invention will be described with reference to FIG. 2, the same parts as those in FIG. 1 are indicated by the same reference numerals. The water level detector 19 in the feed water heater, which is a conventional technique, is installed in the steam turbine plant for power generation described in the first embodiment. In such a steam turbine plant for power generation, the water level detector 16 in the drain pot measures the water level in the drain pot 15, and the water level detector 19 in the feed water heater measures the water level in the feed water heater 12.

Then, these values are constantly monitored by the water intake prevention circuit 18, and when the water level in the drain pot 15 rises above the safe water level, and the feed water heater 12
When the water level inside rises above the dangerous water level, it is determined that wart induction has occurred, and the shutoff valve 13 is fully closed and the drain discharge on / off valve 17 is fully opened by a command from the watertint prevention circuit 18. This is a method to prevent water induction.

[0017]

According to the present invention, it is possible to improve the problem that the shut-off valve is fully closed except when the water-tightening occurs, which is a problem while keeping the basic function of the conventional water-tightening prevention function. It has become possible.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a water induction protection device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a water-tightening prevention device according to another embodiment of the present invention.

FIG. 3 is a configuration diagram showing a conventional water induction prevention device.

[Explanation of symbols]

11 ... Steam turbine for power generation 12 ... Water heater 13 ... Bleed tube 14 ... Shut-off valve 15 ... Drain pot 16 ... Water level detector in drain pot 17 ... Drain discharge on / off valve 18 ... Water induction protection circuit 19 ... Water level detector in feed water heater 20 ... Check valve

Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F01D 25/00 F01D 25/00 V F term (reference) 3G071 AB01 BA09 BA25 BA32 FA05 HA04

Claims (3)

[Claims] 1. In a steam turbine plant for power generation, which has a shut-off valve installed in the middle of the steam inflow line between the power generation steam turbine and the feedwater heater, a drain pot is provided in the middle of the steam inflow line, and the drain pot is provided. A water level detector for detecting the water level in the drain pot, and a watertightness prevention device configured to close the shutoff valve based on a detection result of the water level detector in the drain pot. 2. The feed water heater is provided with a water level detector in the feed water heater, and the shutoff valve is closed based on both detection results of the water level detector in the feed water heater and the water level detector in the drain pot. The watertint prevention device according to claim 1, wherein the watertint prevention device is configured. 3. A check valve is provided between the steam inflow line and the drain pot.
Alternatively, the water tinction prevention device according to claim 2.