JP4912430B2 - Repair method for heat exchanger piping - Google Patents

Description

  The present invention relates to a method for repairing a pipe of a heat exchanger composed of a plurality of pipes such as a economizer of an exhaust heat recovery boiler.

  Conventionally, an exhaust heat recovery boiler is installed as a device for generating steam from the exhaust gas of a gas turbine by heat exchange. The exhaust heat recovery boiler is provided with a economizer composed of a plurality of panels connected so that a plurality of pipes through which the refrigerant flows in the vertical direction extends the exhaust gas between the pipes of the economizer, Heat exchange is performed between the exhaust gas and the refrigerant to generate steam, and electric power is generated using this steam (see, for example, Patent Document 1).

  Here, the pipes of the economizer may cause accelerated corrosion due to water passing through the inside, and repair work is required. Repairing the pipes of such economizers involves cutting the top and bottom of the corroded parts of the corroded pipes, connecting sound pipes to the cut parts, and if there is not enough sound pipes, This is done by closing the top and bottom of the cut portion with a stopper plug. At this time, since the pipes of the economizer are densely provided, if corrosion occurs in the pipes in the back, it is necessary to cut the pipes on the near side in order to secure a working space. Therefore, conventionally, as shown in FIG. 7, after the pipes are excised at the time of repair, the pipes 104 and 105 in the central part (B part in the figure) are repaired by attaching a stopper plug to the outer peripheral part (B in the figure). ) Were repaired by connecting a new healthy pipe to the excised part.

JP 2007-298245 A

  Here, fins for improving heat exchange efficiency are provided around the pipes 104 and 105, and when the new healthy pipes 104 and 105 are connected to the part cut out in the B part of FIG. When the welding work is performed, the fins of the surrounding pipes 104 and 105 become obstacles to the work, and therefore the fins of the surrounding pipes 104 and 105 have to be removed.

  This invention is made | formed in view of said problem, The objective is to enable it to perform smoothly the repair work of piping of a economizer, without removing a fin.

The heat exchanger repair method of the present invention is a heat exchanger in which a plurality of heat exchange pipes provided with members for increasing heat exchange efficiency on the outer periphery are arranged so as to be arranged from the near side to the far side . A method of repairing the pipe in which corrosion has occurred, wherein a cutting step of cutting the pipe in which the corrosion has occurred and a pipe in front of the pipe out of the plurality of pipes; Connect a sound pipe to a cut-off portion of the cut pipe that is not attached with the stop plug, and a step of attaching a stop plug to the cut end of the pipe adjacent to the cut pipe. A connection step.

  According to the present invention, since the outer peripheral pipe is repaired by attaching a stopper plug, when the sound pipe is welded and connected to the cut portion of the central pipe, the surrounding pipe is an obstacle to the welding operation. Therefore, it is not necessary to remove the fins of the surrounding piping, and the welding operation can be performed smoothly.

It is a figure which shows the structure of a waste heat recovery boiler. It is a figure which shows a low voltage | pressure side economizer, (A) is a front view, (B) is II sectional drawing in (A), (C) is II-II sectional drawing in (A). It is a block diagram which shows the structure of a low voltage | pressure side economizer. It is an expanded sectional view of the piping panel structure which comprises a low voltage | pressure side economizer. It is a figure which shows the cutting position of piping. It is a figure for demonstrating the piping used as the object of cutting | disconnection, and its repair method, and is II-II sectional drawing of FIG. 5 (A). It is a figure which shows the piping which attached the closing stopper. It is a figure for demonstrating the repair method of the conventional cut | disconnected piping.

Hereinafter, an embodiment of a method for repairing a pipe of a heat exchanger according to the present invention will be described in detail with reference to the drawings, taking as an example the case of repairing a economizer.
FIG. 1 is a diagram illustrating a configuration of an exhaust heat recovery boiler 10. As shown in the figure, the exhaust heat recovery boiler 10 includes a low-pressure side economizer 20, a low-pressure side evaporator 21, a high-pressure side economizer 30, and a high-pressure side evaporator 31 provided in the flue 60, The low pressure side drum 22, the high pressure side drum 32, the superheater 40, the low pressure side pump 50, and the high pressure side pump 51 provided outside the flue 60 are configured.

  The exhaust heat recovery boiler 10 is supplied with combustion exhaust gas into the flue 60, and from the upstream side in the direction of the exhaust gas flow, the superheater 40, the high pressure side evaporator 31, the high pressure side economizer 30, the low pressure side evaporator 21, They are arranged in the order of the low-pressure side economizer 20. The heat of the high-temperature exhaust gas discharged from the gas turbine is exchanged with water flowing in the superheater 40, the high-pressure side evaporator 31, the high-pressure side economizer 30, the low-pressure side evaporator 21, and the low-pressure side economizer 20. Heat exchange takes place between them. The detailed configuration of the low-pressure side economizer 20 will be described in detail later.

  The water pumped from the low-pressure side pump 50 is heated by the exhaust gas in the low-pressure side economizer 20 and sent to the low-pressure side evaporator 21, and is heated by the exhaust gas in the low-pressure side evaporator 21 to generate water vapor. Then, the water vapor generated in the low-pressure side evaporator 21 is sent to the low-pressure side drum 22, the water vapor is separated in the low-pressure side drum 22, and the separated water vapor is sent to the turbine.

  The water pumped from the high-pressure side pump 51 is heated by the exhaust gas in the high-pressure side economizer 30 and sent to the high-pressure side evaporator 31, and is heated by the exhaust gas in the high-pressure side evaporator 31 to generate water vapor. . The water vapor generated in the high-pressure side evaporator 31 is sent to the high-pressure side drum 32, the water vapor is separated in the high-pressure side drum 32, and the separated water vapor is superheated by the superheater 40 and sent to the turbine.

  FIG. 2 is a diagram illustrating a detailed structure of the low-pressure side economizer 20, (A) is a front view, (B) is a cross-sectional view taken along line II in (A), and (C) is II in (A). It is -II sectional drawing. FIG. 3 is a configuration diagram showing a configuration of the low-pressure side economizer 20, and FIG. 4 is an enlarged cross-sectional view of a piping panel structure 100A that constitutes the low-pressure economizer 20. As shown in FIG. 3, the first to fourth panel structures 100A to 100D are arranged in two on the left and right, but only one is shown in FIGS. 2 (B) and 2 (C). Moreover, since the high-pressure side economizer 30 has the same configuration as the low-pressure side economizer 20, the description thereof is omitted.

As shown in FIGS. 2 and 3, the low-pressure side economizer 20 is formed by laminating first to fourth panel structures 100 </ b> A to 100 </ b> D.
The first to third panel structures 100A to 100C include a pair of piping groups 114 and 115 including a plurality of pipings 104 and 105, an upper piping 101, and upstream and downstream lower pipings 102 and 103. The The pipes 104 and 105 constituting the pipe groups 114 and 115 are provided with fins on the outer periphery, and are arranged in a plurality of rows in the depth direction (three rows in the present embodiment) and a plurality of rows in the horizontal direction. The upper ends of the plurality of pipes 104 and 105 constituting the pair of pipe groups 114 and 115 are connected to the upper pipe 101, respectively. Also, the lower ends of the plurality of pipes 104 constituting one pipe group 114 are connected to the lower pipe 102 on the upstream side, and the lower ends of the plurality of pipes 105 constituting the other pipe group 115 are connected to the lower pipe 103 on the downstream side. Has been. With this configuration, the water supplied to the lower pipe 102 on the upstream side flows from the lower side to the upper side of the pipe 104 of the one pipe group 114, passes through the upper pipe 101, and passes through the pipe 105 of the downstream pipe group 115. It flows downward from above and is discharged from the lower pipe 103 on the downstream side.

  The fourth panel structure 100 </ b> D includes a pipe group 123 including a plurality of pipes 124, an upper pipe 122 to which the upper end and the lower end of the pipe 124 of the pipe group 123 are connected, and a lower pipe 121. With this configuration, the water supplied to the lower pipe 121 flows through the pipe 124 of the pipe group 123 from below to the upper pipe 122.

  As shown in FIGS. 2 and 3, the lower pipe 103 on the downstream side of the first panel structure 100A is connected to the lower pipe 102 on the upstream side of the second panel structure 100B. The lower pipe 103 on the downstream side of the second panel structure 100B is connected to the lower pipe 102 on the upstream side of the third panel structure 100C. Further, the lower pipe 103 on the downstream side of the third panel structure 100C is connected to the lower pipe 121 of the fourth panel structure 100D.

  With this configuration, the water supplied to the lower pipe 102 on the upstream side of the first panel structure 100A flows through the pipe groups 114, 115, 123 of the first to fourth panel structures 100A to 100D, and the fourth panel. It is discharged from the upper pipe 112 of the structure 100D. At this time, the exhaust gas circulates between the piping groups 114, 115, and 123 constituting the first to fourth panel structures 100A to 100D, and between the exhaust gas and the water that circulates inside the pipings 104, 105, and 124. Heat exchange is performed and water is heated.

Hereinafter, the repair method of the economizer of this embodiment is demonstrated. In addition, although the following description demonstrates the case where the low voltage | pressure side economizer 20 is repaired, the high voltage | pressure side economizer 30 can also be repaired similarly.
First, a fiberscope is inserted into the pipes 104, 105, and 124 of the pipe groups 114, 115, and 123 of the panel structures 100A to 100D, and the presence or absence of corrosion inside the pipes 104, 105, and 124 is confirmed. When corrosion is confirmed in the pipes 104, 105, and 124, repair work is performed. In the following description, a case where corrosion is confirmed in the pipe 104 on the back side of the pipe group 114 of the second panel structure 100B will be described.

  In performing the repair work, first, a pipe to be cut and a cutting position thereof are determined. In the present embodiment, the pipes 104 and 105 included in the trapezoidal region surrounded by the broken line C shown in FIG. 6 are cut, and the pipe is cut above and below the portion where corrosion has occurred as shown in FIG. . Then, the pipes 104 and 105 to be cut are cut.

  Next, of the cut pipes 104 and 105, the pipes 104 and 105 that are closed by the closing plugs and the pipes 104 and 105 that connect the healthy pipes after cutting are determined. The reason why the sound pipes are not connected to all the cut pipes is that the cost is high if the sound pipes are connected to all the pipes. As shown in FIG. 6, in this embodiment, the pipes 104 and 105 at the center (A part in the figure) of the cut pipe are connected to a healthy pipe, and the surroundings (B part in the figure) The pipes 104 and 105 are closed at their ends by a stopper plug.

  And first, about the piping 104 and 105 of the B section of FIG. 6, a stopper plug is weld-connected to the cut | disconnected edge part. FIG. 7 is a vertical cross-sectional view showing the ends of the pipes 104 and 105 to which the stop valve 200 is connected by welding. As shown in the figure, when attaching the shut-off plug 200, the plug 210 is disposed inside from the cut end of the pipe 104, and the pipe 104 is welded from above. Thus, since the closure plug 200 is constructed from above, the work of welding the plug 210 can be performed even in the state where the fins of the surrounding pipes 104 and 105 are left.

  Next, with respect to the pipes 104 and 105 in part A of FIG. 6, a sound pipe is welded to the cut portion. As a healthy pipe, the pipes 104 and 105 cut at other sites may be reused. At this time, when the sound pipes are welded and connected, it is necessary to weld around the pipes 104 and 105. In this embodiment, the periphery of the central part (A part) where the sound pipes are welded and connected ( The pipes 104 and 105 in (B part) are to be repaired by attaching a stopper plug 210. For this reason, the pipes 104 and 105 do not exist in the surroundings that interfere with the welding operation, and the welding operation can be performed smoothly.

Next, the pipes 104 and 105 are filled with water, and the presence or absence of water leakage from the welded portion is observed to perform a pressure resistance test on the welded portion. The observation of the presence or absence of water leakage from the back surfaces of the pipes 104 and 105 is performed by arranging a mirror on the back side of the pipes 104 and 105 and removing the mirror from the front side. In the present embodiment, the pipes 104 and 105 around the central part (A part) where the sound pipes 104 and 105 are welded and connected (B part) are repaired by attaching the stopper plugs 200. Through the upper part of the attached pipes 104 and 105, a mirror can be disposed on the back surface of the pipes 104 and 105 in which sound pipes are welded, and the pressure resistance test can be performed smoothly.
By the above process, the economizer can be repaired.

  According to the present embodiment, among the pipes 104 and 105 to be cut, the pipes 104 and 105 at the center (A part) are repaired by connecting sound pipes, and the pipes around the pipes (B part) are repaired. Since the pipes 104 and 105 are repaired by attaching the stopper plugs 200, when the pipes 104 and 105 are connected to the cut portions of the pipes 104 and 105, there are pipes 104 and 105 around the pipes 104 and 105 that obstruct the welding work. not exist. For this reason, it is not necessary to remove the fins of the surrounding pipes 104 and 105 as in the prior art, and the welding operation can be performed smoothly.

  Moreover, when performing a pressure test, since a mirror can be arrange | positioned behind the welding location of the piping of a center part through the part which attached the closure plug 200, a pressure test can be performed easily.

  In this embodiment, the case where the corroded portions of the pipes 104 and 105 are removed and a healthy pipe is connected has been described. However, the present invention is not limited thereto, and the pipes 104 and 105 are cut for inspection. Even in this case, the present invention can be applied.

  Moreover, although this embodiment demonstrated the case where repair of piping of a economizer was carried out, not only this but several piping, such as an evaporator, extended in the up-down direction, and heat exchange was carried out between the piping exterior and the inside. The present invention can be applied to any heat exchanger.

DESCRIPTION OF SYMBOLS 10 Waste heat recovery boiler 20 Low pressure side economizer 21 Low pressure side evaporator 22 Low pressure side drum 30 High pressure side economizer 31 High pressure side evaporator 32 High pressure side drum 40 Superheater 50 Low pressure side pump 51 High pressure side pump 60 Flue 100A , 100B, 100C, 100D Panel structures 101, 112, 122 Upper piping 102 Lower upstream piping 103 Downstream lower piping 104, 105 Piping 114, 115, 123 Piping group 121 Lower piping 200 Closure plug 210 Plug

Claims (1)

A method of repairing the pipes that have been corroded in a heat exchanger that is densely arranged so that a plurality of pipes for heat exchange having members for increasing the heat exchange efficiency on the outer periphery are arranged from the near side to the far side. There,
Of the plurality of pipes, a cutting step for cutting the pipe where the corrosion has occurred and a pipe before the pipe;
Of the cut pipes, a stopper plug attaching step for attaching a stopper plug to the cut end of the pipe adjacent to the uncut pipe;
A connection step of connecting a sound pipe to a cut portion of the pipe that is not attached with the shut-off plug among the cut pipes.