JP2020071196A - Method for determining leakage in tubular heat exchanger - Google Patents

Abstract

To provide a method for determining leakage in a tubular heat exchanger with which it is possible to easily and quickly specify a leaking tube, shorten the time before being specified, cut back repair costs and reduce the burden of a worker.SOLUTION: The representative configuration of a tubular heat exchanger (first heat exchanger 110) leakage determination method pertaining to the present invention is a tubular heat exchanger leakage determination method for determining the presence of leakage in a tube 114 inside of which a gaseous substance and a heat exchanging medium pass through, characterized in that the inside pressure of a smoke tunnel 112 in which the heat exchanger is installed is negative, and the method includes stopping the passage of the medium in the tube 114, removing the medium inside of the tube 114 and releasing open to the atmosphere by pulling medium in the tube, measuring the temperature of the tube 114 on the outside of the smoke tunnel after the passage of a prescribed time, and determining that the tube 114 is leaking when the tube temperature is less than a prescribed value.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a leak determination method for a tube heat exchanger that determines whether or not there is a leak in a tube through which a medium that exchanges heat with a gaseous substance such as air and exhaust gas passes.

  In a facility such as a power plant or a factory that emits high-temperature exhaust gas, a heat exchanger may be provided to cool the exhaust gas or recover the heat of the exhaust gas. There are various types of heat exchangers, and a tube heat exchanger can be exemplified as one of them. For example, Patent Document 1 discloses a heat exchanger in which a tube in which water that absorbs latent heat is circulated in a path of exhausted combustion gas is housed inside a casing into which combustion gas is introduced.

JP, 2008-170088, A

  In a tube heat exchanger, it is general that a plurality of tubes are used instead of one tube. For this reason, for example, when a hole is formed in one tube due to deterioration or damage and the liquid (medium) inside leaks out (when a leak occurs), other tubes or surrounding devices should not be damaged. There is an urgent need to identify the perforated tube and repair it (replacement, stopcock, etc.). However, during operation of the heat exchanger, it is difficult to visually confirm a leak that has occurred in the tube due to the installation environment of the heat exchanger (generally installed in the flue duct).

  Therefore, when identifying a leaked tube, a medium is first discharged from the tube, and then one of the plurality of tubes is cut to perform an airtight test. As a result, if the pressure is maintained, it can be determined that there is no leak, so the cut tube is restored, and the work of cutting, airtightness, and restoration is repeated until the leaked tube is found. Then, if a tube having a pressure drop is confirmed in the airtight test, the tube is identified as a leaking tube. When the leaking tube is identified, repair (replace, stop plug) the tube. Then, the medium is caused to flow into the tube, and the heat exchanger is restored.

  As described above, according to the conventional method, the work of cutting, airtightness, and restoration must be repeated in order from the end until the leaked tube is specified. For this reason, much time is required for identification, repair costs are high, and the burden on the operator is large. Therefore, there has been a demand for the development of a method capable of more efficiently identifying leaked tubes.

  In view of such problems, the present invention can easily and quickly identify a leaking tube, shorten the time until identification, reduce repair costs, and reduce the burden on workers. It is an object of the present invention to provide a leak determination method for a tube heat exchanger.

  In order to solve the above problems, a typical configuration of the leak determination method for a tube heat exchanger according to the present invention is to determine the presence or absence of a leak of a tube through which a medium that exchanges heat with a gaseous substance passes through. This is a method of judging the leak of a tube heat exchanger, in which the inside of the flue airway where the heat exchanger is installed has a negative pressure, the passage of the medium in the tube is stopped, and the medium in the tube is removed to release it to the atmosphere. The temperature of the tube is measured outside the flue passage after a predetermined time has elapsed, and when the temperature of the tube is less than a predetermined value, it is determined that the tube is leaking.

  When the inside of the flue airway where the heat exchanger is installed has a negative pressure, and if a leak occurs in the tube, the inside of the tube from which the medium has been removed also has a negative pressure. If the atmosphere is released in this state, the temperature of the leaked tube approaches the atmospheric temperature and becomes less than a predetermined value because the atmosphere is sucked into the tube. Therefore, the temperature of the tube is measured, and if the temperature is less than the predetermined value, it can be determined that the tube is leaking. With this, for example, it is possible to easily and quickly identify a leaking tube without requiring cutting, airtightness, and restoration work in order from the end, shortening the time until identification, reducing repair costs, and It is possible to reduce the burden on the.

  In order to solve the above problems, another configuration of the leak determination method for a tube heat exchanger according to the present invention is a tube for determining the presence or absence of a leak of a tube through which a medium that exchanges heat with a gaseous substance passes through. This is a leak determination method for a heat exchanger, in which a plurality of tubes are provided, the inside of the flue airway where the heat exchanger is installed is negative pressure, the passage of the medium in the tube is stopped, and the inside of the tube is stopped. After removing the medium, release the medium to the atmosphere, measure the temperature of the tubes outside the flue passage after a lapse of a predetermined time, and judge that the tubes are leaking if the temperature difference between multiple tubes exceeds a predetermined value. It is characterized by

  Even in such a configuration, if a leak occurs in the tube, the temperature of the leaked tube is lowered because the atmosphere is sucked into the tube when the tube is opened to the atmosphere. At this time, among the plurality of tubes, a normal tube in which no leak has occurred does not have a temperature drop because the atmosphere is not sucked. Therefore, a clear temperature difference occurs between the leaking tube and the non-leaking tube. Therefore, if the temperature difference exceeds a predetermined value, it can be determined that a leak has occurred in the tube on the lower temperature side, and the same effect as described above can be obtained.

  In order to solve the above problems, another configuration of the leak determination method for a tube heat exchanger according to the present invention is a tube for determining the presence or absence of a leak of a tube through which a medium that exchanges heat with a gaseous substance passes through. A method for determining a leak of a heat exchanger, the inside of the flue passage in which the heat exchanger is installed has a positive pressure, the passage of the medium in the tube is stopped, the medium in the tube is removed, and the atmosphere is released, The temperature of the tube is measured outside the flue passage after a predetermined time has elapsed, and it is determined that the tube is leaking when the temperature of the tube exceeds a predetermined value.

  When the inside of the flue airway where the heat exchanger is installed has a positive pressure, and if a leak occurs in the tube, the inside of the tube from which the medium has been removed also has a positive pressure. If the air is released in that state, the temperature of the leaked tube approaches the temperature of the gaseous substance and exceeds a predetermined value because the gaseous substance in the flue gas duct is sucked into the tube. Therefore, the temperature of the tube is measured, and if the temperature exceeds a predetermined value, it can be determined that the tube is leaking. With this, for example, it is possible to easily and quickly identify a leaking tube without requiring cutting, airtightness, and restoration work in order from the end, shortening the time until identification, reducing repair costs, and It is possible to reduce the burden on the.

  In order to solve the above problems, another configuration of the leak determination method for a tube heat exchanger according to the present invention is a tube for determining the presence or absence of a leak of a tube through which a medium that exchanges heat with a gaseous substance passes through. This is a leak determination method for a heat exchanger in which multiple tubes are provided, the inside of the flue airway where the heat exchanger is installed is positive pressure, the passage of the medium in the tube is stopped, and the inside of the tube is stopped. After removing the medium, release the medium to the atmosphere, measure the temperature of the tubes outside the flue passage after a lapse of a predetermined time, and judge that the tubes are leaking if the temperature difference between multiple tubes exceeds a predetermined value. It is characterized by

  Even in such a configuration, if the tube leaks, the temperature of the leaked tube rises because the gaseous substance in the flue gas is sucked into the tube when the tube is exposed to the atmosphere. At this time, among the plurality of tubes, the normal tube in which no leak has occurred does not have the temperature rise because the gaseous substance is not sucked. Therefore, a clear temperature difference occurs between the leaking tube and the non-leaking tube. Therefore, if the temperature difference exceeds a predetermined value, it can be determined that a leak has occurred in the tube on the higher temperature side, and the same effect as described above can be obtained.

  ADVANTAGE OF THE INVENTION According to this invention, the tube heat exchanger which can identify the leaked tube easily and quickly, can shorten the time to identification, can reduce a repair cost, and can reduce a worker's burden. It is possible to provide a leak judgment method of

It is a figure explaining the equipment which applies the leak determination method of the tube type heat exchanger concerning this embodiment. It is a figure explaining the 1st heat exchanger of FIG. It is a flow chart of the leak judgment method concerning this embodiment. It is a figure explaining the measurement result of the temperature of a some tube. It is a figure explaining the measurement result of the temperature of a some tube.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating understanding of the invention, and do not limit the invention unless otherwise specified. In this specification and the drawings, elements having substantially the same function and configuration are denoted by the same reference numerals to omit redundant description, and elements not directly related to the present invention are omitted. To do.

  FIG. 1 is a diagram illustrating equipment to which the leak determination method for a tube heat exchanger according to this embodiment is applied. In this embodiment, the thermal power plant 100 is exemplified as the equipment, but the equipment is not limited to this. The leak determination method of the present embodiment can be applied to other equipment as long as the equipment includes a tube heat exchanger.

  As shown in FIG. 1, the thermal power plant 100 is provided with a gas-gas heater including a first heat exchanger 110 and a second heat exchanger 108. The gas-gas heater is a device that recovers heat from the exhaust gas, performs a predetermined process such as dust collection or desulfurization, and then reheats the exhaust gas. First, high-heat exhaust gas from the boiler 102 is sent to the first heat exchanger 110. In the first heat exchanger 110, exhaust gas is cooled by heat exchange with a medium (not shown). Dust is removed from the cooled exhaust gas by passing through the electric dust collector 104. Then, the exhaust gas is sucked by the induced draft fan 106 in the lower stage of the electric dust collector 104, and the first heat exchanger 110 is reheated in the second heat exchanger 108 by using the heat obtained from the exhaust gas. Then, it is discharged from the chimney 109.

  FIG. 2 is a diagram illustrating the first heat exchanger 110 of FIG. The first heat exchanger 110 shown in FIG. 2 is a tube heat exchanger including a tube 114 through which a medium that exchanges heat with a gaseous substance such as air and exhaust gas passes. In the leak determination method of this embodiment, the presence or absence of a leak in the tube 114 in the first heat exchanger 110 is determined.

  The high-temperature exhaust gas from the boiler 102 passes through the flue gas duct 112 in which the first heat exchanger 110 is installed. As described above, since the exhaust air is sucked by the induced draft fan 106, the inside of the flue airway has a negative pressure. As shown in FIG. 2, a tube 114 through which water as a medium passes is arranged in the flue airway.

  Note that, for convenience of illustration, FIG. 2 illustrates the configuration in which three tubes 114 are arranged, but in reality, a plurality of tubes 114 are further arranged in the vertical direction. In addition, in the present embodiment, the configuration in which the first heat exchanger 110 includes the plurality of tubes 114 is illustrated, but the configuration is not limited to this. As will be described later, the leak determination method of this embodiment can be applied to a configuration including only one tube 114.

  The end of the tube 114 is arranged outside the flue gas duct 112 in which the first heat exchanger 110 is installed, and the inlet header 116a and the outlet header 116b are connected to each other. The inlet header 116a and the outlet header 116b are provided with a vent valve 118, a blow valve 119, or both, respectively. When the vent valve 118 and the blow valve 119 are opened, the medium passing through the tube 114 can be discharged and the tube 114 can be exposed to the atmosphere.

  As shown by the broken line circle D in FIG. 2, when the tube 114 is punctured due to deterioration or damage, the medium inside leaks, so-called leak occurs. If this leak is left unattended, the leaked medium may damage other tubes 114, peripheral equipment, etc. due to corrosion, etc. Therefore, the leaked tube 114 should be identified immediately and repaired (replacement, closing, etc.). It is necessary to put it on.

  FIG. 3 is a flowchart of the leak determination method according to this embodiment. As shown in FIG. 3, in the leak determination method of this embodiment, first, passage of the medium through the tube 114 is stopped (step S202). Then, by opening the vent valve 118 and the blow valve 119, the medium in the tube 114 is removed and the atmosphere is released (step S204).

  After a lapse of a predetermined time after releasing the atmosphere, the temperatures of the plurality of tubes 114 are measured outside the flue gas duct 112 in which the first heat exchanger 110 is installed using the thermometer 120 (step S206), and the plurality of tubes 114 are measured. It is determined whether or not the temperature difference is above a predetermined value (step S208). If the temperature difference is less than or equal to the predetermined value, it is determined that the tube 114 has not leaked (step S210). On the other hand, if the temperature difference exceeds the predetermined value, it is determined that the tube 114 is leaking (step S212).

  As described above, in the case where the inside of the flue gas duct 112 in which the first heat exchanger 110 is installed has a negative pressure, if the tube 114 leaks, the inside of the tube 114 from which the medium has been removed is also negative. It becomes pressure. When the atmosphere is released in this state, the temperature of the leaking tube 114 becomes lower than the temperature of the leaking tube 114 because the atmosphere is sucked into the tube 114 and cooled. Therefore, a clear temperature difference occurs between the leaking tube 114 and the non-leaking tube 114. As a result, if the temperature difference exceeds the predetermined value, it can be determined that leakage has occurred in the tube on the lower temperature side.

  4 and 5 are diagrams for explaining the measurement results of the temperatures of the plurality of tubes 114. FIG. 4 illustrates a case where there is one leaking tube 114, and FIG. 5 illustrates a case where there is a plurality of leaking tubes 114. 4 and 5, the vertical axis represents temperature and the horizontal axis represents tube numbers of the plurality of tubes 114. The upper pipe temperature is the temperature of the tube 114 arranged in the upper stage of the flue gas duct 112, and the lower pipe temperature is the temperature of the tube 114 arranged in the lower stage of the flue gas duct 112.

  In the example shown in FIG. 4, the temperature of the 13th upper tube (tube) is lower than the other tubes by 10 ° C. or more (the temperature difference exceeds a predetermined value). Therefore, it can be determined that a leak has occurred in the 13th upper tube. As described above, according to the leak determination method of the present embodiment, the leaked tube 114 can be easily and promptly identified without requiring the work of cutting, airtightness, and restoration which has been conventionally performed. Therefore, it is possible to shorten the time until identification, reduce the repair cost, and reduce the burden on the worker.

  In the example shown in FIG. 5, the 12th upper tube (tube) has a temperature lower by about 15 ° C. than the other tubes 114, and the 14th and 16th upper tubes (tubes) have a temperature lower than that of the other tubes 114 by 10 ° C. ℃ is low. Therefore, it can be determined that a leak occurs in these three tubes 114 whose temperature is lower than that of the other tubes 114 by 10 ° C. or more, that is, the temperature difference exceeds a predetermined value. As described above, according to the leak determination method of the present embodiment, even if a plurality of tubes 114 are leaking, it is possible to easily identify the leaking tube 114.

  Using the leak determination method described above, the temperature of 56 tubes was measured, and the tube 114 having a temperature difference exceeding a predetermined value was cut, and an airtight test was performed. As a result, since the pressure drop was confirmed, as an example, the first heat exchanger 110 was restored after the stop plug was attached instead of replacement. From the past results, it took about 12 working days to perform airtightness for 56 tubes, but when the leak determination method of this embodiment is applied, the number of working days becomes 2 days, and a significant reduction in construction period can be realized. Was possible.

  In the above embodiment, it is determined whether the temperature difference between the plurality of tubes 114 exceeds a predetermined value. That is, the leaked tube 114 was identified by relatively judging the temperature of the tube 114. However, the present invention is not limited to this. For example, when the temperature of the tube is less than a predetermined value, it may be determined that the tube 114 is leaking, that is, the leaking tube 114 may be specified by the absolute value of the temperature of the tube 114. According to this, even if the number of tubes 114 is one, it is possible to determine whether or not there is a leak.

  Further, in the above-described embodiment, the leak determination method when the flue passage 112 has a negative pressure has been described, but the leak determination method of the present invention can be applied even when the flue passage 112 has a positive pressure. You can If the inside of the flue gas duct 112 has a positive pressure, and if a leak occurs in the tube 114, the inside of the tube 114 from which the medium has been removed will also have a positive pressure. If the atmosphere is released in this state, the temperature of the tube 114 rises because the exhaust air of the flue airway 112 is sucked into the tube 114.

  On the other hand, the normal tube 114 in which no leak has occurred does not rise in temperature because the exhaust gas is not sucked in. Therefore, a clear temperature difference occurs between the leaking tube 114 and the non-leaking tube 114. Therefore, if the temperature difference exceeds a predetermined value, it can be determined that a leak has occurred in the tube 114 on the higher temperature side, and the same effect as described above can be obtained. Further, when the absolute value of the temperature is used for determination, contrary to the case where the smoke duct 112 has a negative pressure, when the temperature of the tube 114 exceeds a predetermined value, the tube 114 leaks. You can judge.

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but it goes without saying that the present invention is not limited to such examples. It is obvious to those skilled in the art that various changes or modifications can be conceived within the scope described in the claims, and naturally, these also belong to the technical scope of the present invention. Understood.

  INDUSTRIAL APPLICABILITY The present invention can be used as a leak determination method for a tube heat exchanger that determines whether or not there is a leak in a tube through which a medium that exchanges heat with a gaseous substance passes.

100 ... Thermal power plant, 102 ... Boiler, 104 ... Electric dust collector, 106 ... Induction fan, 108 ... Second heat exchanger, 109 ... Chimney, 110 ... First heat exchanger, 112 ... Smoke passage, 114 ... Tube, 116a ... Inlet header, 116b ... Outlet header, 118 ... Vent valve, 119 ... Blow valve, 120 ... Thermometer

Claims (4)

A leak determination method for a tube heat exchanger for determining the presence or absence of a leak of a tube through which a medium that exchanges heat with a gaseous substance passes,
The inside of the flue airway where the heat exchanger is installed is negative pressure,
Stopping the passage of media through the tube,
The medium in the tube is pulled out and released to the atmosphere,
After the elapse of a predetermined time, the temperature of the tube is measured outside the flue airway,
A method for determining leakage of a tube heat exchanger, comprising determining that the tube is leaking when the temperature of the tube is less than a predetermined value. A leak determination method for a tube heat exchanger for determining the presence or absence of a leak of a tube through which a medium that exchanges heat with a gaseous substance passes,
A plurality of the tubes are provided,
The inside of the flue airway where the heat exchanger is installed is negative pressure,
Stopping the passage of media through the tube,
The medium in the tube is pulled out and released to the atmosphere,
After the elapse of a predetermined time, the temperature of the tube is measured outside the flue airway,
A method for determining leakage in a tube heat exchanger, comprising determining that the tubes are leaking when the temperature difference between the plurality of tubes exceeds a predetermined value. A leak determination method for a tube heat exchanger for determining the presence or absence of leakage of a tube through which a medium that exchanges heat with a gaseous substance passes,
The inside of the flue airway where the heat exchanger is installed is positive pressure,
Stopping the passage of media through the tube,
The medium in the tube is pulled out and released to the atmosphere,
After the elapse of a predetermined time, the temperature of the tube is measured outside the flue airway,
A method for determining leakage of a tube heat exchanger, comprising determining that the tube is leaking when the temperature of the tube exceeds a predetermined value. A leak determination method for a tube heat exchanger for determining the presence or absence of a leak of a tube through which a medium that exchanges heat with a gaseous substance passes,
A plurality of the tubes are provided,
The inside of the flue airway where the heat exchanger is installed is positive pressure,
Stopping the passage of media through the tube,
The medium in the tube is pulled out and released to the atmosphere,
After the elapse of a predetermined time, the temperature of the tube is measured outside the flue airway,
A method for determining leakage in a tube heat exchanger, comprising determining that the tubes are leaking when the temperature difference between the plurality of tubes exceeds a predetermined value.

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