JPH02309197A - Heat transfer pipe leakage surveying method for heat exchange device - Google Patents

Abstract

PURPOSE:To enable specifying of a leaky heat transfer pipe by a method wherein when the leaky heat transfer pipe can not be specified visibly, sheets for detection are inserted from two directions symmetrical with respect to a piping row in a manner to contain the heat transfer pipe to be surveyed, and outflow water drops are confirmed. CONSTITUTION:When a heat transfer pipe 8d leaks, water drops are detected at the outer peripheral group of a pipe group. A specified number of sheets 20a for detection having size large enough to allow carriage of them through the manhole of an exhaust heat recovery heat exchanger from the upper part or the lower part of a pipe group is inserted along the alignment direction of the heat transfer pipe in the vicinity of a place where the water drops are detected. When the sheets 20a for detection are inserted in a manner to nip the heat transfer pipe 8d therebetween, water drops flowing out from the heat transfer pipe 8d flow along the sheets 20a for detection flows to a lower end. Water drops 21 are conformed, and after a row 22 of the heat transfer pipe is distinguished by means of a discriminating mark, the sheets 20a for detection are pulled off, and is inserted along alignment of the heat transfer pipe symmetrically to a preceding direction. This method enables the heat transfer pipe 8d being an intersection between two rows to be specified as a heat transfer, to which leakage occurs, basedon rows 22 and 23 of the heat transfer pipes on which the discriminating marks are drawn.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Field of Application) The present invention provides a method for detecting a heat transfer tube leakage accident by visual inspection, for example, in an emergency measure against a heat transfer tube leakage accident in an exhaust heat recovery heat exchanger used in a combined cycle power generation plant. The present invention relates to a heat exchanger tube leakage detection method that is applied when it is difficult to identify the heat exchanger tube.

(Conventional Welding) A conventional technique will be explained using FIGS. 2, 3, and 4.

FIG. 2 shows a schematic system of a combined cycle power plant that combines a gas turbine and a steam turbine.

First, outside air 1 sucked in by the air compressor 2 is compressed here, becomes high pressure, and is supplied to the combustor 3. In the combustor 3 , fuel is further added and combusted to become high-temperature, high-pressure combustion gas, which is sent to the gas turbine 4 . The combustion gas introduced into the gas turbine 4 expands and performs work, rotates an impeller (not shown), and drives the generator 5. The combustion gas that did work in the gas turbine 4 is
The expanded exhaust gas passes through the duct 6 and is guided to the exhaust heat recovery boiler 7.

The temperature of this exhaust gas is usually as high as 500° C. to 600° C., and it is uneconomical to dispose of this exhaust gas as it is due to a large thermal loss. For this reason, an exhaust heat recovery heat exchanger 7 is provided to recover residual heat contained in the exhaust gas. The exhaust gas introduced into the exhaust heat recovery heat exchanger 7 is cooled by exchanging heat with the water supply passing through the heat exchanger tubes 8, and is released into the atmosphere from the chimney 10 as a low-temperature gas.

Next, we will look at this plant configuration along the flow of water and steam.

The steam introduced into the steam turbine 10 is expanded to perform work, and the expanded steam is exhausted to the condenser 11 and condensed to become condensed water. This condensate is supplied to a water supply system 1 equipped with a water supply pump 12.
3, and is sent to the energy saver 14 of the exhaust heat recovery heat exchanger 7.
It is heated by this economizer 14.

The heated feed water is fed into the water below the steam drum 15.

Water in the steam drum 15 is sent to an evaporator 17 by an ovulation pump 16. The feed water passing through the evaporator 17 is heated and sequentially evaporated, becomes a gas-liquid two-phase flow, is returned to the upper steam of the steam drum 15, and is separated into gas and liquid.

The steam stored in the upper part of the steam drum 15 undergoes moisture separation through a moisture separator (not shown), and is then sent to the superheater 18 to become superheated steam, which is introduced into the steam turbine 10 to drive the steam turbine 11. It is designed to let you do so. A energy saver 14 housed in the exhaust heat recovery heat exchanger 7. Evaporator 17. The superheater 18 is composed of a group of finned heat transfer tubes 8 each having a large heat transfer area. These tube groups are supported by support plates 19 arranged at appropriate intervals to prevent fatigue failure due to fluid-induced vibration.

Economizer 14. Evaporator 17. A heat exchanger tube 8 used in the superheater 18 is shown in FIG.

The length of the heat exchanger tube 8 is usually 40 to 50 mm in consideration of heat exchange performance.
A length of m is required. In order to prevent the equipment of the waste heat recovery heat exchanger 7 from becoming long by making the heat exchanger tubes 8 long, the heat exchanger tubes 8 are formed in a serpentine tube shape, and the length of the straight section of the heat exchanger tubes is approximately 10 m. There is.

Therefore, the heat exchanger tube 8 has a U-shaped heat exchanger tube 8a as shown in FIG.
and a straight heat exchanger tube 8b are welded and connected to have a predetermined length. Economizer 14. Evaporator 17. The tube group of the superheater 18 is
Several hundred such meandering heat exchanger tubes 8 are constructed, and the tube arrangement of the heat exchanger tubes 8 is generally in a staggered arrangement as shown in FIG.

(Problem to be Solved by the Invention) In the exhaust heat recovery heat exchanger 7 as described above, a leakage accident occurs in the heat exchanger tube 8 during operation, and high temperature and high pressure steam or water inside the heat exchanger tube 8 leaks outside the tube. may erupt. Heat exchanger tube 8
If a leak occurs, immediately stop the operation of the waste heat recovery heat exchanger 7, identify the leakage part of the heat exchanger tube 8, take measures such as plugging the leaked heat exchanger tube 8 with a plug, and then restart the operation. Need to restart. In a tube arrangement as shown in FIG.

If the leakage point of the heat exchanger tube 8 is the heat exchanger tube 8C on the outer periphery of the pipe row, it is easy to identify, but if the leak occurs in the heat exchanger tube 8d that enters inside from the outer periphery of the tube group, it is difficult to identify the leakage point. Identification is difficult and takes a lot of time. Normally, resumption of operation after such a leak is urgent, and the search for the leakage part is required to proceed quickly, but this cannot be done satisfactorily.

Therefore, an object of the present invention is to provide a heat exchanger tube for a heat exchanger that can easily identify the leaked heat exchanger tube when a leak occurs in a heat exchanger tube that enters from the outer periphery of a group of heat exchanger tubes in the heat exchanger. The object of the present invention is to provide a leakage detection method.

[Structure of the invention]

(Means for Solving the Problems) A feature of the present invention is that in a heat exchange device consisting of a large number of heat transfer tubes arranged in a staggered manner, A method for detecting a leaking heat exchanger tube when internal fluid flows out from a heat exchanger tube, the method comprising:
A certain number of detection thin plates are inserted along the tube array so as to include the heat transfer tube of interest, and one row containing the heat transfer tube of interest is identified from the internal fluid flowing along the surface of the detection thin plate. , the sensing thin plate is then pulled out from there and inserted along the tube array to include the heat transfer tubes in a direction symmetrical to the previous insertion direction to remove the internal fluid flowing along the surface of the sensing thin plate. The other row containing the heat exchanger tube of interest is specified, and the leaking heat exchanger tube is found at the point where both of the above-mentioned two rows of heat exchanger tubes intersect.

(Function) When a leak occurs in a heat exchanger tube that enters from the outer periphery of a group of heat exchanger tubes in a pan exchanger, and the leaked heat exchanger tube cannot be identified by visual inspection, the heat exchanger tube that is focused on the thin detection plate are inserted from two directions in a symmetrical relationship along the tube arrangement so as to include both rows.

At this time, as long as the detection thin plates are symmetrical, the leaky heat exchanger tube can be found at the intersection of both rows, and its position can be easily identified.

Therefore, it greatly contributes to restarting the operation of the heat exchange device, which is required urgently.

(Example) Hereinafter, one embodiment of the present invention will be described with reference to FIG.

Note that the following explanation is based on the economizer 14. Evaporator 17. Superheater 1
Although this can be applied to any of the tube groups 8, for convenience, the explanation will be based on the assumption that leakage has occurred in the heat exchanger tube 8d shown in FIG.

When a leak occurs in the heat exchanger tube 8d, the water inside the heat exchanger tube 8d flows out of the tube from the broken part, so that water droplets are found on the outer periphery of the tube group. A certain number of detection thin plates 20a of a size that can be carried through the manhole of the exhaust heat recovery heat exchanger are inserted from the upper or lower part of the tube group along the arrangement direction of the heat exchanger tubes in the vicinity where the water droplets are found. When the detection thin plate 20a is inserted between the heat exchanger tubes so as to sandwich the heat exchanger tube 8d, water droplets flowing out from the broken part of the heat exchanger tube 8d flow downward through the detection thin plate 20a, Reach its lower end.

Check the water droplets 21 that have flowed to the lower end of this detection thin plate 20,
The heat exchanger tube row 22 containing the heat exchanger tube 8d is identified and distinguished from other rows using an appropriate identification mark. Thereafter, the detection thin plate 20a is pulled out from the tube group and inserted along the arrangement of the heat exchanger tubes so as to be symmetrical to the previous direction.

Similarly to the above, water droplets flowing out from the damaged portion of the heat exchanger tube 8d are confirmed at the lower end of the detection thin plate 20b (water droplets 21), and an identification mark is drawn on the row 23 of heat exchanger tubes in which the heat exchanger tube 8d is included. After the identification mark distinguishes it from other rows, the detection thin plate 20
b is pulled out from the tube group.

Based on the heat exchanger tube rows 22 and 23 on which identification marks have been drawn in accordance with the above procedure, the heat exchanger tube 8d located at the intersection of the two is identified as the heat exchanger tube in which the leak has occurred.

In this way, even if a leak occurs in a heat exchanger tube that enters from the outer periphery of the tube group, it is easy to identify the heat exchanger tube, and the heat exchanger tube can be plugged with a plug to prevent water or steam from flowing in. be treated.

〔Effect of the invention〕

As explained above, the present invention provides a heat exchange device consisting of a large number of heat exchanger tubes arranged in a staggered manner, in which internal fluid flows out from a certain heat exchanger tube that enters from the outer periphery of a group of heat exchanger tubes. When a certain number of detection thin plates are inserted along the tube array so as to include the leaking heat transfer tube of interest, the internal fluid flowing along the surface of the detection thin plate is removed from the one containing the heat transfer tube of interest. The detection thin plate is then pulled out from there, and the heat transfer is inserted along the tube array to include the focused heat transfer tube in a direction symmetrical to the previous insertion direction, so that the heat is transmitted along the surface of the detection thin plate. The system identifies the other row containing the heat exchanger tube of interest from the internal fluid flowing through it, and locates the leaking heat exchanger tube at the point where both rows of heat exchanger tubes intersect. Even if a leak occurs in a heat exchanger tube that has entered the inside of the pipe, the heat exchanger tube can be easily identified.
This provides an excellent effect in that the operation of the heat exchange device can be restarted quickly.

[Brief explanation of the drawing]

Fig. 1 is a diagram for explaining the heat transfer tube leakage detection method according to the present invention, Fig. 2 is a schematic system diagram showing a conventional combined cycle power plant, and Fig. 3 is a diagram for explaining the heat exchanger tube leakage detection method according to the present invention. A configuration diagram showing a finned heat exchanger tube used as a heat tube,
Figure 4 is a economizer. It is a tube arrangement diagram of heat exchanger tubes of an evaporator and a superheater. 7...Exhaust heat recovery heat exchanger 8...Heat transfer tube 8a...
U-shaped heat exchanger tube 8b...straight heat exchanger tube 8c, 8
d...Heat transfer tube 14 where leakage occurred...Economic device
17...Evaporator 18...Superheater 2
0a, 20b... thin plate for detection 21... water droplet
22.23...Heat transfer tube line agent Patent attorney
Nori Chika Ken Yudo Daishimaru Ken Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] In a heat exchange device consisting of a large number of heat exchanger tubes arranged in a staggered manner, leaking heat exchanger tubes are detected when internal fluid flows out from a heat exchanger tube that enters from the outer periphery of a group of heat exchanger tubes. A method of detecting a heat exchanger tube by inserting a certain number of detection thin plates along a tube arrangement so as to include the heat transfer tube of interest from the internal fluid flowing along the surface of the detection thin plate. After that, the detection thin plate is pulled out from there, and the detection thin plate is inserted along the tube array so as to include the heat transfer tube whose orientation is symmetrical to the previous insertion direction. A heat exchanger characterized by identifying another row containing the heat exchanger tube of interest from the internal fluid flowing along the surface of the thin plate, and finding the leaking heat exchanger tube at the point where both of the above rows of heat exchanger tubes intersect. Method for detecting leakage in heat exchanger tubes of exchange equipment.