JPS6333636A - Leak detection for condensate heat exchanger - Google Patents

Abstract

PURPOSE:To detect a heat exchange pipe having a leak hole efficiency in a short time, by checking a temperature difference with an infrared temperature sensor as generated by leakage or suction of air at the leak hole of a heat exchange pipe. CONSTITUTION:When a leak is judged to be existent with conductivity meters 4 and 5 or the like at a condensate heat exchanger 2, sea water is drained from a feed pipe 12, a drain tube 14 and a pipe 7 and furthermore, both valves 11 and 13 are closed. Under such a condition, a valve 15 is released to feed a high pressure air into a pipe 7. This causes a temperature difference in the leak hole from the perimeter thereof. The temperature difference is detected including those at the length-wise position and the height-wise position of the leak hole with the scanning by a infrared temperature sensor 29.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a condenser equipped with a large number of heat exchange pipes used for condensing steam from a turbine of a nuclear power plant. In particular, the present invention relates to a method for quickly detecting a leak in a condenser pipe.

``Conventional technology'' Large condensing heat exchangers used in nuclear power plants use seawater to exchange heat from the steam coming out of the turbine. If a damaged part such as a hole or crack occurs in the heat exchanger, seawater leaks from the damaged part, causing an increase in the conductivity and chlorine concentration of the condensate.

This will lead to problems that will hinder reactor operation, such as corrosion of various pipes and an increase in activated products such as Mn and 50Co contained in seawater. It is necessary to stop.

The conventional method for detecting leaks in ascites heat exchangers is to gradually drain the seawater in the heat exchange pipes of the condensing heat exchanger during periodic inspections of the reactor, and detecting broken pipes in the height direction of the condensing heat exchanger. Roughly determine the location of the The heat exchange pipes in the vicinity were detected one by one using a detection method such as the eddy current method or the water manometer method.

``Problems to be Solved by the Invention'' In the conventional leak detection method described above, if the damaged part of the heat exchange pipe, that is, the leak hole, does not have a certain size, the height direction during seawater drainage will increase. The problem is that it cannot be detected. Furthermore, the number of heat exchange pipes in the condensate heat exchanger is approximately 7,000, and it is necessary to perform leak detection on many of the heat exchange pipes. There are problems such as increased time and radiation exposure.

"Means for Solving Problems" In the present invention, during periodic inspection of a nuclear reactor, the seawater in the heat exchange pipe of the ascites heat exchanger is drained, and the inside of the heat exchange pipe is pressurized or depressurized. Detecting the temperature difference caused by air leakage or suction at the leak hole of the heat exchange pipe using an infrared temperature sensor that scans the top and one side of the condensate heat exchanger in a direction perpendicular to the heat exchange pipe. Detects leak holes in heat exchange pipes.

"Example" An embodiment of the present invention will be described below based on the drawings.

In FIGS. 1 and 2, one system of low pressure turbine 1
It has two systems of condensate heat exchangers 2 for each water system (
A conductivity level of 4.5 is provided in each of the paths (as shown in the figure). When there are three ascites heat exchangers 2 in a nuclear reactor, a total of six condensate heat exchangers 2 each having the above-mentioned conductivity of 4.5 are arranged.

If seawater leaks during reactor operation, it is possible to easily determine which condensate heat exchanger 2 is leaking from the electrical conductivity of each water system, which is 4.5. Thereby, the determined leakage of the ascites heat exchanger 2 is inspected as described below.

A plurality of heat exchange pipes 7 are provided in the main body 6 of the condensate heat exchanger 2.
are installed horizontally, and each end thereof is electrically connected to a hollow connecting portion 8.9 formed at the front and rear of the main body 6, respectively.

A seawater supply pipe 12 is connected to the connection part 8 through a valve 11, and a discharge pipe 14 is connected to the connection part 9 through a valve 13. An air pipe 16 is connected to the supply pipe 12 via a valve 15 .

In the support mechanism 17 shown in FIGS. 3 and 4, both ends of a guide shaft 21 are fixed to arm portions 18a119b of a pair of brackets 18, 19, respectively. Further, both ends of a feed screw 22 are pivotally attached to the arm portions 18a and 19b, respectively.

The gear fixed to one end of the feed screw 22 and the gear fixed to the output shaft of the motor 23 fixed to the arm 18a of the bracket 18 are in mesh with each other, and are rotated forward and backward by the feed screw 22. It has become so.

The movable member 25, which has an infrared temperature sensor 24 fixed to its lower part, is loosely fitted onto the guide shaft 21 and is threaded onto the feed screw 22, so that when the feed screw 22 is rotated forward or backward, the movable member 25 moves between the brackets 18 and 19. reciprocate.

A pair of guide rollers 26, 27 are each pivotally supported on opposing sides of both brackets 18, 19, and a similar pair of guide rollers 26, 27 is also provided at the bottom of the bracket 18, 19.
8 are each pivotally supported. Said guide roller 26.
28 and guide rollers 27, 28 to the condensing heat exchanger 2.
By pressing the support mechanism 17 in the front-rear direction (left-right direction in FIG. 1) while in contact with both corners of the upper part of the main body 6, the infrared temperature sensor 24 is moved a certain distance from the upper part of the main body 6. is moved forward and backward.

The condensing heat exchanger 2 condenses steam from the turbine 1 using seawater supplied into the heat exchange pipe 7 through the supply pipe 12 and the discharge pipe 14 .

At this time, both valves 11, 12 are in an open state and valve 15 is in a closed state. When a leak in a certain condensing heat exchanger 2 is determined by a conductivity meter 4.5 or the like, the seawater in the supply pipe 12, discharge pipe 14, and heat exchange pipe 7 is drained, and both valves 11.12 are closed. Obstructed. In this state, the valve 15 is opened and high pressure air is supplied into the heat exchange pipe 7. Due to this air supply, the air leaks forcefully from the leak hole of the heat exchange pipe 7, and this causes a temperature difference with the surroundings.

Next, the support mechanism 17 is placed on one end of the upper part of the condensate heat exchanger 2, and the infrared temperature sensor 24 is moved back and forth. Further, as shown in FIG. 1, each time the infrared temperature sensor 24 is moved at an appropriate interval in the direction of the arrow, the infrared temperature sensor 24 is reciprocated to scan the upper part of the support mechanism 17.

By this scanning of the infrared temperature sensor 24, the distance in the longitudinal direction and the distance in the width direction of the ascites heat exchanger 2 where the leak hole is located is detected.

A support mechanism (not shown) similar to the support mechanism 17 described above is applied to the side of the condensate heat exchanger 2, and the infrared temperature sensor 29 is attached to the side of the condensate heat exchanger 2 as shown in FIG. It moves at appropriate intervals in the front-back direction and reciprocates in the up-down direction. By scanning the infrared temperature sensor 29, the position in the longitudinal direction and the position in the height direction of the leak hole are detected.

After the approximate position of the leak hole is detected in this way, by inspecting a small number of heat exchange pipes 7 in the vicinity,
The heat exchange pipe 7 having the leak hole of the ascites heat exchanger 2 can be detected in a short time.

In the above embodiment, the case where the inside of the heat exchange pipe 7 is pressurized is described, but the position of the ultrasonic wave generated by the air sucked from the leak hole by reducing the pressure inside the heat exchange pipe 7 is detected. Even if the heat exchange pipe 7 is used, it is possible to detect the leak hole in the heat exchange pipe 7 in the same manner as described above.

"Effects of the Invention" According to the above-described ↓ sea urchin, seawater in the heat exchange pipe of a condensing heat exchanger is drained, and the heat exchange pipe is pressurized or depressurized. By detecting the temperature difference with the surrounding area caused by air leakage or suction at the leak hole of the condensing heat exchanger using an infrared temperature sensor that scans in a direction perpendicular to the heat exchange pipe at the top and one side of the condensate heat exchanger. , a heat exchange pipe having a leak hole can be efficiently detected within a short time.

[Brief explanation of drawings]

Fig. 1 is a side view of a condensing heat exchanger to which the leak detection method for a condensing heat exchanger of the present invention is applied and its related parts, Fig. 2 is a longitudinal sectional view of the condensing heat exchanger, and Fig. 3 4 is a plan view of the support mechanism of the infrared temperature sensor, and FIG. 4 is a front view of the support mechanism. 1... Turbine, 2... Condensing heat exchanger, 4.5... Conductivity scale, 6... Main body, 7... Heat exchange pipe, 12... Supply pipe, 14... Discharge pipe, 16... Air pipe, 17... Support mechanism, 24.29 ...Infrared temperature sensor. Applicant: Japan Atomic Energy Corporation, Agent

Claims (1)

[Claims] A main body to which steam discharged from the turbine is supplied, a plurality of heat exchange pipes installed horizontally in parallel within the main body, a supply pipe that supplies seawater for cooling to each of the heat exchange pipes, and a heat exchanger. In a condensate heat exchange system having a discharge pipe for discharging seawater after cooling from a service pipe, the seawater in the supply pipe, discharge pipe, and heat exchange pipe is removed, and appropriate places in the supply pipe and discharge pipe are blocked. In this state, the heat exchange pipe is depressurized or pressurized, and an infrared temperature sensor is scanned at appropriate intervals in a direction perpendicular to the heat exchange pipe at the top and one side of the main body to detect damage to the pipe. 1. A method for detecting a leak in a condensing heat exchanger, the method comprising detecting a heat exchange pipe in a leak state by measuring a temperature difference caused by air leaking or being sucked in a condensing heat exchanger.