JPS597808A - Detector for leakage of dry heater - 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 The present invention relates to a dry heater for an ultra-supercritical thermal power plant, and more particularly to a device for detecting leakage of feed water from a dry heater.

A currently proposed water supply system for an ultra-supercritical thermal power plant will be explained with reference to FIG.

Figure 1 shows a portion of a thermal power plant.

In this figure, the feed water sent from the low pressure feed water heater passes through the deaerator 4 and is boosted in pressure by the feed water pump 5, and then is heated by the extracted steam from the intermediate pressure turbine 3 and the high pressure turbine 2 for high pressure feed water heating. It is heated in the vessel 6. After that, the pressure is further increased by the boost pump 7, and then the ultra-high pressure feed water heater 8 heated by the extracted steam of the ultra-high pressure turbine is heated and the water enters the dry heater 9.

After being further heated by this dry heater, it is supplied to the boiler.

The dry heater 9 is a feed water heater specific to the ultra supercritical pressure thermal power generation plant feed water heater system.
The aim is to improve the thermal efficiency of the sibrants by installing them.

The function of this dry heater 9 is to heat the feed water using superheated steam, which is extracted steam from the turbine, but the extracted steam that has heated the feed water and lowered its temperature also exits the dry heater 9 in the state of superheated steam. go. In this way, a normal feedwater heater differs from a normal feedwater heater in that the extracted steam is condensed within the vessel.

Here, when the extracted steam after passing through the dry heater 9 is used as a heating source for the high-pressure feed water heater 6 as shown in FIG. 1, the extracted steam at the outlet of the dry heater 9 must be in a superheated steam state. . If a tube leak occurs in the dry heater 9 and part of the feed water flows into the bleed steam, and the bleed steam at the outlet of the dry heater 9 becomes wet steam, it will flow from the dry heater 9 to the high pressure feed water heater 6. The bleed steam piping and the heat transfer tubes of the high-pressure feed water heater 6 are damaged by erosion due to water droplets in the wet steam.

Therefore, early detection of tube leaks in the dry heater 9 is important to prevent equipment damage.

An object of the present invention is to provide a tube leak detection device that can detect a dry heater tube starter at an early stage in a dry heater installed in a feed water heater system of an ultra-supercritical pressure couplant.

The key point of the present invention is to install flowmeters at the inlet and outlet of the dry heater, compare these two flow rate signals, and detect tube leaks in the dry heater at an early stage.

Hereinafter, one embodiment of the present invention will be described based on all the drawings.

One embodiment of the present invention will be explained with reference to FIG. This figure shows only the system of nine dry heaters in the ultra-supercritical pressure pyroelectric power plant shown in FIG. 1. The extracted steam from the steam turbine 1o enters the dry heater 9 through the dry heater inlet bleed steam pipe 11, heats the feed water sent through the water supply pipe 13, and then passes through the dry heater outlet bleed steam pipe 12 to high pressure. Enter the feed water heater 8. In this system, flow rate detectors 14 and 15 are installed in the water supply pipe 13 at the inlet and outlet of the dry heater 9, and signals from these two detectors are input to the leak detector 16.

Next, the function of the leak detector 16 is shown in FIG.

This leak detector 16 compares the flow rate signal F1 from the dry heater inlet water supply flow rate detector 15 and the flow rate signal F2 from the dry heater outlet water supply flow rate detector 16, and determines the presence or absence of a leak based on the magnitude of the signal. be. That is,
The flow rate signals F1 and F2 are compared as shown below to determine the presence or absence of a leak.

1] F2≧F, -α: No leak 2) F, ≦F1-α: Leak exists Here, α is a margin value.

This determination result is used as a signal for alarm or control.

Next, another leak detection method is shown in FIG. This leak detection method inputs a load signal obtained from the load itself or the extracted steam pressure corresponding to the load, and a dry heater outlet water supply amount signal Ft k obtained from the water supply flow rate detector 14 at the outlet of the dry heater 9 to the leak detector 17. In this leak detector 17, the load signal is input to the basic water supply amount calculator 18 to obtain the basic water supply amount Fo corresponding to the load.

This basic water supply amount F. and dry heater output water supply amount signal F,
+Put it into the leak detector 19 and judge whether there is a leak or not as shown below.

1) F, ≧Fo−α: No leak 2) F2≦F1−α: Leak exists Here, α is a margin value.

This determination result is used as a signal for alarm or control.

The leak detector 16 or leak detector 17 described above
Since a leak in the feed water in the tri-heater 9 can be detected at an early stage, it is possible to prevent the leak from occurring in the oil/steam piping or the feed water heating wire heat exchanger tube.

According to the present invention, a leak in the supply water in the dry heater can be detected at an early stage, so that it is possible to prevent the leak from turning the extracted steam at the outlet of the dry heater into wet steam. For this reason, the heat transfer distribution of the bleed steam piping at the dry heater outlet and the high pressure feed water heater that uses steam from the bleed steam piping at the dry heater outlet as a heat source is caused by water droplets in the wet steam generated by tube leaks of the dry heater. It becomes possible to prevent damage due to erosion, improving the reliability of the power plant.

[Brief explanation of the drawing]

Fig. 1 is a water supply system diagram of an ultra-supercritical pressure plant, Fig. 2 is a system diagram showing a dry heater leak detection device according to an embodiment of the present invention, and Fig. 3 explains the contents of the leak detection device according to the present invention. FIG. 4 is a system diagram illustrating another leak detection device according to the present invention.

Claims (1)

[Claims] 1. A dry heater is installed that converts the steam turbine extracted steam into heated steam and heats the feed water with its sensible heat without condensing the steam, and the dry heater heats the feed water. In a thermal power plant that uses latent heat as a heat source for a feedwater heater that heats feedwater, feedwater flow rate detectors are installed in the water supply piping at the inlet and outlet of the dry heater, and the flow rate from these detectors is A leak detection device for a dry heater, comprising a determination device that determines whether there is a tube leak in the dry heater based on a difference in detected values. 2. In the dry heater leak detection device according to claim 1, a water supply flow rate detector is installed in the water supply pipe at the outlet of the dry heater, and a water supply flow rate value and a load signal or load equivalent signal from the flow rate detector are provided. What is claimed is: 1. A leak detection device for a dry heater, comprising: a comparison device for comparing a basic water supply amount determined from the above, and detects a tube leak of the dry heater.