JPS62272003A - Feedwater-heater protective device - 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 3. Detailed Description of the Invention [Purpose of the Invention (Industrial Application Field) The present invention provides protection for avoiding major accidents in power generation systems due to abnormalities in feedwater heaters in power generation plants. Regarding equipment.

(Prior Art) For example, in a thermal power plant, steam used in a turbine is used to improve operating efficiency.

After the feed water is heated, it is supplied to the boiler. For this heating, a feed water heater is used that exchanges heat by passing feed water through divided thin tubes and passing steam around the thin tubes. In addition, the steam used in the feed water heater is extracted from the steam used in the turbine.

In the above-mentioned feed water heater, if the water supply pipe is damaged and the feed water leaks, the amount of steam drain increases and the drain water level in the device becomes high. If the drain water level becomes abnormally high, low-temperature water may flow back to the turbine from the bleed inlet through the bleed piping, potentially damaging the turbine.

To prevent such accidents, conventional controls have been used to detect when the drain water level in the feed water heater has become abnormally high, and to close the steam valve of the feed water heater and open the drain relief valve. ing.

Figure 2 is a schematic configuration diagram of a power generation plant having a feedwater heater, showing a conventional example of the same.6 The steam used in the turbine 1 passes through the condenser 2, and the condensed water is supplied to the feedwater heater 3. Ru. This water is in turbine 1
The water is heated by steam passing through the bleed line 4 and supplied to the feed water heater 6 via the deaerator 5. Here, the boiler 8 is further heated by the steam passing through the extraction line 7.
supplied to The boiler 8 converts feed water into steam, sends the steam to the turbine 1 via a steam pipe 9, rotates the turbine, and generates electricity by a generator (not shown).

Next, the peripheral configuration of the feed water heater will be described in detail.

In FIG. 3, the feed water heater generally has two systems for fail-safe purposes, and has a bypass valve 10 that bypasses them. The water condensed by the condenser 2 is supplied to the feed water heaters 12A, 1 through the feed water inlet valves 11A, 11B.
2B and after being heated, the water supply outlet valves 13A, 13B
is sent to boiler 8. Steam for heating is extracted from the turbine 1, passes through the bleed air check valve 14, and passes through the bleed air inlet valve 1.
The water enters the feed water heaters 12A and 12B from 5A and 15B. In addition, the steam drain in the heater is drain relief valve 16A, 1
The above is the peripheral configuration of the feed water heater.

Now, if the amount of steam drain from feed water heater L2A is large for some reason, the drain water level becomes abnormally high.

There is a possibility that steam drain flows backward from the bleed air inlet valve 15A to the turbine side, and in order to prevent this, a detection signal is sent to the control device 18 by the feed water heater abnormality detector 17A. The control device 18 controls to open the drain relief valve 16A of the feed water heater 12A where the drain water level has become high to discharge steam drain, and closes the bleed air inlet valve 15A.

Generally, when two systems are operating at 100% of the water supply to the water heater, if only one system is operating, the amount of water supplied to the water heater is reduced to 75%.
By operating under load and supplementing the water supply amount with the bypass valve 10, the operating system always ensures 100% water supply amount. In other words, if the drain water level in the feed water heater 12A becomes abnormally high and it is necessary to stop the feed water heater 12A, the load on the feed water heater 12B is set to 75%, and the bypass valve 10 is opened. % water supply amount and the water supply inlet valve 11A of the water supply heater 12A.
Then, the water supply outlet valve 13A is closed, and the normal heating system and bypass system operate.

(Problems to be Solved by the Invention) The problem with the above-mentioned control is that the feed water heater 12A
When the drain water level becomes abnormally high.

The bleed air inlet valve 15A is closed, but due to the fact that it is an electric valve and the pipe diameter, it takes several tens of seconds to fully close, and the drain water level quickly rises due to damage to the water supply pipe inside the heater. In such a case, there is a risk that steam drain will flow back into the turbine until the bleed air inlet valve 15A is fully closed.

Therefore, when the drain water level becomes extremely high, a method is adopted in which the bleed air check valve 14 is forcefully closed to prevent backflow to the turbine.

However, if the bleed air check valve 14 is closed, the normal steam system of the feed water heater 12B will also be stopped.

There are problems that make normal driving impossible.

Therefore, the present invention prevents the water level from becoming extremely high even if the drain water level becomes high due to an abnormality in the feed water heater.
Another object of the present invention is to provide a feed water heater protection device that allows one power generation plant to safely continue operating without stopping two systems of heaters at the same time when a check valve is closed.

[Structure of the Invention (Means for Solving Problems)] The present invention provides a bleed air relief valve that bypasses steam or condensate from the bleed air line between the bleed air inlet valve and the feed water heater to a condenser, etc. This bleed air relief valve is designed to open when an abnormality occurs in the feed water heater.

(Function) Due to the above structure, if the feedwater heater malfunctions and the drain water level becomes extremely high, the drain or bleed air will flow backward until the bleed air inlet valve is fully closed.

The bleed air is discharged to the condenser etc. using the bleed air relief valve. This prevents backflow to the turbine without closing the check valve, and prevents a malfunction in one system of feedwater heaters from stopping normal operation of other systems' feedwater heaters.

(Example) FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing only one system of the feed water heater. 1
9A is a bleed air relief valve, and 20 is a control device. The same equipment as in FIG. 3 is given the same reference numeral and the explanation thereof will be omitted.

In the configuration shown in FIG. 1, first, when the drain water level becomes high due to an abnormality such as breakage of the internal tube of the feed water heater 12A, the abnormality detector 17A detects the abnormality of the feed water heater and the control device 2
send a signal to. Based on the above signal, the control device 20 increases the opening degree of the drain relief valve L6A to discharge the drain to the condenser, and also opens the bleed air relief valve 19A to bypass the steam sent from the turbine to the condenser etc. The operation of each valve is controlled accordingly. As a result, a sudden rise in the drain water level in the feed water heater can be suppressed.

Next, the internal tube of the feed water heater 12A was severely damaged.
When the drain water level rises extremely and the turbine-side hedren flows backward from the feedwater heater 12A, the control device 20 first detects the abnormal rise in the feedwater heater 12A using the abnormality detector 17A.

Control is performed to fully open the drain relief valve 16A, fully open the bleed air relief valve 19A, and fully close the bleed air inlet valve 15A.

As a result, although it takes time for the bleed air inlet valve 15A to fully close, the piston valve type bleed air relief valve 19A, which is rapidly fully opened in a few seconds, is fully opened.

Bleed water relief valve 1 for drain water flowing back from the feed water heater 12A
9A can be used to bypass the condenser etc. and control the low temperature water from flowing into the turbine. At the same time, turbine bleed air can be normally supplied to the feed water heater 12B (not shown), and the water supply operation can be maintained continuously.

As described above, by providing the bleed air relief valve 19A and controlling it to open and close in the event of an abnormality, even if the drain water level becomes extremely high, the backflow of condensate to the turbine can be prevented without closing the bleed air check valve 14. Therefore, the normal feed water heater system can be operated without stopping.

The bleed air relief valve 19A can be used not only when the feed water heater 12A is abnormal, but also during normal operation to adjust the drain water level.

Further, in this embodiment, a conventional direct abnormality detector is used as a means for detecting an abnormality in the feed water heater 12A.
This detecting means may be an indirect method such as calculating from the relationship of the amount of water supply and drainage.

[Effects of the Invention] As explained above, according to the present invention, even if an abnormality in which the drain water level becomes high occurs, this abnormality can be dealt with at an early stage to prevent backflow to the turbine side. A safe power generation system can be obtained that eliminates the inconvenience of stopping feedwater heaters in other systems due to an abnormality in the feedwater heater.

[Brief explanation of the drawing]

Fig. 1 is a schematic system diagram showing one system of a feed water heater according to an embodiment of the present invention, Fig. 2 is a schematic configuration diagram of a power generation system having a feed water heater, and Fig. 3 is a schematic diagram of a conventional feed water heater. It is a system diagram. 1... Turbine, 2... Condenser, 3, 6.12 A
, 12 B... Feed water heater, 4, 7... Bleeding line, 5... Deaerator, 8... Boiler, 9... Steam pipe, 10... Bypass valve, 11 A, 11B
... Water supply population valve, 1:3A, 13B ... Water supply outlet valve, 14 ... Bleed air check valve, 15A, 15B ・
... Bleed air inlet valve, 16A, 16B ... Drain relief valve, 17A, 17B ... Feed water heater abnormality detector, 18.20 ... Control device, 19A, 19B ...
・Bleed air relief valve. (7317) Agent: Patent Attorney Noriyuki Chika (
stos) The same prince, Hongbun Bukki, Figures 1 and 2

Claims (1)

[Claims] In a protection device for a feedwater heater that heats feedwater sent from a condenser using turbine bleed air, multiple systems of feedwater heaters are provided, and a bleed air relief valve is provided on the bleed air inlet side of each of these feed water heaters to protect the feed water heater. A water heater protection device characterized in that a corresponding bleed air relief valve is opened in response to an abnormality.