JP4587045B2 - Decontamination method for finned heat exchanger and finned heat exchanger decontamination system - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a finned heat exchanger decontamination method and a finned heat exchanger decontamination system, and more particularly to a fin contaminated with radioactive material in a nuclear facility such as a nuclear power plant. The present invention relates to a decontamination method for a heat exchanger with fins and a decontamination system for a heat exchanger with fins.

  Conventionally, in a nuclear facility such as a nuclear power plant, a method including a blast decontamination process is known as a decontamination method for a finned heat exchanger contaminated with a radioactive substance. In the blast decontamination process, the surface of the finned heat exchanger contaminated with radioactive material is sprayed with a blast material made of particles of metal, ceramics, glass, plastic, dry ice, ice, etc., and the surface is ground. Thus, radioactive substances are removed.

  However, in such a blast decontamination process, for example, there is a possibility that contamination due to the radioactive substance may remain locally in the gap between the fin member and the fin member. Therefore, the finned heat exchanger that has been subjected to the blast decontamination step enters a decontamination tank in which the decontamination liquid is stored and is immersed in the decontamination liquid, thereby performing chemical decontamination for decontamination of radioactive substances. A decontamination method combining a dyeing process is known (see, for example, Patent Document 1).

JP 2002-3111191 A

  However, in the decontamination method proposed in Patent Document 1, the chemical decontamination process is combined with the blast decontamination process, but the cost required for the chemical decontamination process is high, and as a result, heat exchange with fins is performed. There is a problem that the cost required for decontamination of the vessel becomes excessive. In addition, due to the structure of the heat exchanger with fins, it is difficult to confirm whether or not the decontamination of the gap between the fin members has been completed, and the reliability of the decontamination method is sufficiently high. Absent.

  In view of the above circumstances, an object of the present invention is to provide a finned heat exchanger decontamination method and a decontamination system that can perform highly reliable decontamination while reducing costs. .

  In order to achieve the above object, a finned heat exchanger decontamination method according to claim 1 of the present invention includes a long cylindrical heat transfer tube whose inside is a heat medium flow path, and an outer periphery of the heat transfer tube. A finned heat exchanger decontamination method comprising a plurality of fin members erected on the surface in a manner along the outer peripheral direction of the heat transfer tube and in the axial direction of the heat transfer tube, The fin member while cutting the surface of the heat transfer tube with the tip edge by pressing a cylindrical cutting member whose edge is the cutting edge in such a manner that the heat transfer tube relatively enters the hollow inside of the cutting member Including a separation step of separating the heat transfer tube from the heat transfer tube, and a decontamination step of blast decontamination of the fin member separated by the separation step.

The finned heat exchanger decontamination method according to claim 2 of the present invention includes the slit forming step of forming a slit in each fin member in claim 1 described above, and the separating step includes forming the slit. Each fin member in which the slit was formed by the process is separated from the heat transfer tube.

  The finned heat exchanger decontamination method according to claim 3 of the present invention is the above-described decontamination method according to claim 1 or 2, wherein the tip edge of the cutting member is formed in a wave shape along the circumferential direction. It is characterized by comprising.

  A finned heat exchanger decontamination system according to claim 4 of the present invention includes a long cylindrical heat transfer tube having a heat medium passage inside, and the heat transfer tube on the outer peripheral surface of the heat transfer tube. In the decontamination system for decontaminating a heat exchanger with fins provided with a plurality of fin members erected along the outer circumferential direction of the heat transfer tube and in the axial direction of the heat transfer tube, the tip edge is a blade edge The cylindrical cutting member is pressed in such a manner that the heat transfer tube relatively enters the hollow inside of the cutting member, so that the fin member is transferred to the fin member while cutting the surface of the heat transfer tube with the tip edge. Separating means for separating from the heat tube and decontaminating means for blast decontaminating the fin member separated by the separating means are provided.

  Further, the finned heat exchanger decontamination system according to claim 5 of the present invention includes the slit forming means for forming a slit in each fin member in the above-described claim 4, wherein the separating means is the slit forming. Each fin member in which the slit is formed by the means is separated from the heat transfer tube.

  Further, in the finned heat exchanger decontamination system according to claim 6 of the present invention, in the above-mentioned claim 4 or claim 5, the tip edge of the cutting member is formed in a wave shape along the circumferential direction. It is characterized by comprising.

  According to the finned heat exchanger decontamination method of the present invention, a cylindrical cutting member whose tip edge is a cutting edge in the separation step is pressed in such a manner that the heat transfer tube relatively enters the hollow interior of the cutting member. Thus, the fin member is separated from the heat transfer tube while cutting the surface of the heat transfer tube with the tip edge, and the fin member separated by the separation step in the decontamination step is blast decontaminated, so that the radioactive material on the surface of the heat transfer tube In addition to reliably decontaminating, the fin member can also be decontaminated reliably. Further, there is no need to use a chemical decontamination process that requires high costs as in the prior art. Therefore, it is possible to perform highly reliable decontamination while reducing the cost.

  Moreover, according to the finned heat exchanger decontamination system of the present invention, the separating means enters the cylindrical cutting member whose tip edge is the cutting edge, and the heat transfer tube relatively enters the hollow inside of the cutting member. By pressing in the mode, the fin member is separated from the heat transfer tube while scraping the surface of the heat transfer tube with the tip edge, and the decontamination means blast decontaminates the fin member separated by the separation means. In addition to reliably decontaminating the radioactive material on the surface, the fin member can also be decontaminated reliably. Further, there is no need to use chemical decontamination that requires high costs as in the prior art. Therefore, it is possible to perform highly reliable decontamination while reducing the cost.

  Exemplary embodiments of a finned heat exchanger decontamination method and a finned heat exchanger decontamination system according to the present invention will be described below in detail with reference to the accompanying drawings. In the following, for convenience of explanation, the decontamination method will be described as appropriate while explaining the decontamination system of the finned heat exchanger.

1 and 2 schematically show a finned heat exchanger decontamination system according to an embodiment of the present invention. FIG. 1 is a block diagram, and FIG. 2 shows a decontamination process. It is the schematic diagram shown collectively. 1 and 2, the decontamination system 10 includes a pre-cleaning unit 11, a slit forming unit (slit forming means) 12, a separation unit (separating means) 13, and a blast decontamination unit (decontamination means) 14. A post-cleaning unit 15, a radiation dose measuring unit 16, and a control unit 17. Here, the finned heat exchanger 20 to be decontaminated includes a heat transfer tube 21 and a plurality of fin members 22. The heat transfer tube 21 has a long cylindrical shape, and the inside serves as a flow path for the heat medium. Each of the plurality of fin members 22 is in the form of a donut-shaped disk, and is disposed in a state where it is thermally connected to the heat transfer tube 21, thereby expanding the heat exchange area with the heat medium flowing inside the heat transfer tube 21. It is something to be made. More specifically, the fin members 22 are erected along the outer peripheral direction of the heat transfer tube 21 on the outer peripheral surface of the heat transfer tube 21 and are arranged in the axial direction (longitudinal direction) of the heat transfer tube 21. Are arranged upright with a gap between them. Such a finned heat exchanger 20 will be described as being contaminated with radioactive materials in a nuclear facility such as a nuclear power plant.

  The pre-cleaning unit 11 performs primary cleaning on the finned heat exchanger 20 that has been transported by a transport mechanism (not shown). The tip cleaning unit 11 includes a first cleaning liquid tank (not shown) and a first cleaning nozzle 111. The first cleaning liquid tank stores a predetermined primary cleaning liquid 112. The first cleaning nozzle 111 injects the primary cleaning liquid 112 stored in the first cleaning liquid tank toward the finned heat exchanger 20.

  The slit forming unit 12 forms a slit 23 (see FIG. 3) in each fin member 22 of the heat exchanger 20 with fins that has been primarily cleaned by the first cleaning unit 11. The slit forming unit 12 includes a notch member 120 such as a cutter. As shown in FIG. 3, the notch member 120 has a disk-shaped blade edge portion, and moves along the longitudinal direction (axial direction) of the heat transfer tube 21 by rotating the blade edge portion. A slit 23 is formed in 22.

  The separation unit 13 separates the finned heat exchanger 20 in which the slits 23 are formed by the slit forming unit 12, and more specifically, separates each fin member 22 from the heat transfer tube 21. The separation unit 13 includes a cutting member 130. As shown in FIG. 3, the cutting member 130 has a cylindrical shape with a hollow portion 130 a formed therein, and has a cutting edge portion 131. The blade edge portion 131 is a cylindrical portion having an inner diameter that matches the outer diameter of the heat transfer tube 21, and the tip edge 131 a is the blade edge. The leading edge 131a is formed in a wave shape along the circumferential direction. Here, the wave shape is not particularly limited, but it is sufficient that the irregularities are continuously formed along the circumferential direction. On the proximal end side of the blade edge portion 131, a tapered portion 132 is formed continuously, and the inner diameter and the outer diameter gradually increase as the distance from the blade edge portion 131 increases. Is formed by continuously forming a cylindrical base portion 133 having a larger inner diameter and outer diameter than the cutting edge portion 131. Such a cutting member 130 advances and moves in such a manner that the heat transfer tube 21 relatively enters the hollow portion 130 a, thereby removing the fin member 22 from the heat transfer tube 21 while cutting the surface of the heat transfer tube 21 with the tip edge 131 a. To be separated.

  The blast decontamination unit 14 is for blast decontamination of the heat transfer tube 21 and the fin member 22 separated by the separation unit 13. The blast decontamination unit 14 includes a container (not shown) that contains a blast material made of particles of metal, ceramics, glass, plastic, dry ice, ice, and the like, and a blast material 142 that is contained in the container. The blast nozzle 141 sprays the heat transfer tube 21 and the fin member 22 on the respective surfaces.

  The post-cleaning unit 15 performs secondary cleaning on the heat transfer tube 21 and the fin member 22 blast-decontaminated by the blast decontamination unit 14. Thereafter, the cleaning unit 15 has a second cleaning liquid tank (not shown) and a second cleaning nozzle 151. The second cleaning liquid tank stores a predetermined secondary cleaning liquid 152. The second cleaning nozzle 151 injects the secondary cleaning liquid 152 stored in the second cleaning tank toward each of the heat transfer tube 21 and the fin member 22.

  The radiation dose measurement unit 16 measures the radiation dose of each of the heat transfer tube 21 and the fin member 22 that have been secondarily cleaned by the post-cleaning unit 15. The radiation dose measuring unit 16 has a measuring device (not shown). Data measured by the measuring instrument is output to the control unit 17 as a measurement signal.

  The control unit 17 has a built-in memory (not shown) such as a ROM and a RAM, for example, and controls the operation of each unit constituting the decontamination system 10 based on programs, data, and the like stored in the memory. To control.

  The decontamination system 10 having the above-described configuration decontaminates the finned heat exchanger 20 contaminated with a radioactive substance as follows. That is, the decontamination method for the finned heat exchanger 20 according to the embodiment of the present invention is performed as follows.

  When the finned heat exchanger 20 contaminated with the radioactive material is conveyed, the control unit 17 of the removal system primarily cleans the finned heat exchanger 20 through the first cleaning unit 11. More specifically, in the first cleaning unit 11, the first cleaning liquid 112 stored in the first cleaning liquid tank is sprayed from the first cleaning nozzle 111 onto the surface of the finned heat exchanger 20 (first cleaning step). Thereby, the surface of the finned heat exchanger 20 is cleaned with the primary cleaning liquid 112.

  When the finned heat exchanger 20 that has been primarily cleaned by the first cleaning unit 11 is conveyed, the control unit 17 forms slits 23 in the fin members 22 through the slit forming unit 12. More specifically, in the slit forming unit 12, by moving the notch member 120 along the longitudinal direction of the heat transfer tube 21 while rotating the blade edge portion, as shown in FIG. 23 is formed (slit forming step).

  When slits 23 are formed in the fin members 22 of the finned heat exchanger 20 by the slit forming unit 12, the control unit 17 separates the finned heat exchanger 20 through the separation unit 13. More specifically, in the separation unit 13, the cutting member 130 advances and moves in such a manner that the heat transfer tube 21 relatively enters the hollow portion 130 a, and as shown in FIG. The surface of the heat transfer tube 21 is shaved and separated from the heat transfer tube 21 while spreading the fin member 22 (separation step).

  Then, the control unit 17 blasts and decontaminates each of the heat transfer tube 21 and the fin member 22 separated by the separation unit 13 through the blast decontamination unit 14. That is, in the blast decontamination unit 14, the blast material 142 accommodated in the container is sprayed from the blast nozzle 141 onto the respective surfaces of the heat transfer tube 21 and the fin member 22 (blast decontamination step). Thereby, each surface of the heat exchanger tube 21 and the fin member 22 is ground by the blast material 142, and thereby the radioactive substance on the surface of the heat exchanger tube 21 and the fin member 22 is removed.

When the heat transfer tube 21 and the fin member 22 decontaminated by the blast decontamination unit 14 are conveyed, the control unit 17 performs secondary cleaning of the heat transfer tube 21 and the fin member 22 through the post-cleaning unit 15. More specifically, in the post-cleaning unit 15, the secondary cleaning liquid 152 stored in the second cleaning liquid tank is sprayed from the second cleaning nozzle 151 onto the respective surfaces of the heat transfer tube 21 and the fin member 22 (post-cleaning). Process). Thereby, the surfaces of the heat transfer tubes 21 and the fin members 22 are cleaned by the secondary cleaning liquid 152.

  Thereafter, the control unit 17 measures the radiation dose of the heat transfer tube 21 and the fin member 22 that have been secondarily cleaned by the post-cleaning unit 15 through the radiation dose measurement unit 16, and outputs the measurement signal output from the radiation dose measurement unit 16. It inputs and complete | finishes decontamination of the heat exchanger 20 with a fin. Thereby, the heat transfer tube 21 and the fin member 22 after the radiation dose measurement are conveyed to the outside of the decontamination system 10.

  In the decontamination system 10 in the present embodiment as described above, the tip edge 131a of the blade edge portion 131 is formed in a wave shape along the circumferential direction on the cutting member 130, so that the cutting member 130 is pressed to advance. When moved, the force can be concentrated on the convex portion 131b of the tip edge 131a, and each fin member 22 can be separated from the heat transfer tube 21 without requiring excessive pressing force. In particular, in the decontamination system 10 according to the present embodiment, after the slits 23 are formed in each heat transfer fin member 22, the cutting member 130 is pressed and moved forward, so that each fin member 22 is pushed with a smaller pressing force. It can be spread out and separated from the heat transfer tube 21. Since the separation unit 13 separates the fin member 22 from the heat transfer tube 21 and the blast decontamination unit 14 blast decontaminates the heat transfer tube 21 and the fin member 22 separated by the separation unit 13, the heat transfer tube 21 and the fin member Each of the 22 surfaces can be reliably decontaminated. Further, there is no need to use chemical decontamination that requires high costs as in the prior art. Therefore, highly reliable decontamination can be performed while reducing the cost.

  Moreover, according to the said decontamination system 10, the heat exchanger tube 21 and the fin member 22 after decontamination can be recycled, and, thereby, reduction of hazardous waste can be achieved.

  According to the decontamination method of the finned heat exchanger 20 in the present embodiment, in the separation step, the cutting edge 130 formed in a wave shape along the circumferential direction is pressed against the cutting edge 130 of the blade edge portion 131 and moved forward. Therefore, the force can be concentrated on the convex portion 131b of the tip edge 131a, and each fin member 22 can be separated from the heat transfer tube 21 without requiring excessive pressing force. In particular, in the decontamination method according to the present embodiment, since the slits 23 are formed in each heat transfer fin member 22 in the slit forming step and then the cutting member 130 is pressed and moved forward, each fin member can be moved with a smaller pressing force. 22 can be expanded and separated from the heat transfer tube 21. And since the fin member 22 is separated from the heat transfer tube 21 in the separation step and the heat transfer tube 21 and the fin member 22 separated in the separation step in the blast decontamination step are blast decontaminated, each of the heat transfer tube 21 and the fin member 22 is separated. Can be reliably decontaminated. Further, there is no need to use chemical decontamination that requires high costs as in the prior art. Therefore, highly reliable decontamination can be performed while reducing costs.

  Moreover, according to the said decontamination method, the heat exchanger tube 21 and the fin member 22 after decontamination can be recycled, and, thereby, reduction of hazardous waste can be achieved.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to this, and various modifications can be made. For example, in the embodiment described above, the separated heat transfer tubes 21 and the fin members 22 are blast decontaminated. However, in the present invention, after the fin members are separated from the heat transfer tubes, the outer diameter of the heat transfer tubes Alternatively, the outer peripheral surface of the heat transfer tube may be ground using a grinding member having a slightly smaller die-shaped cutting edge. According to this, the contaminated part on the surface of the heat transfer tube can be completely removed.

  In the above-described embodiment, the configuration including the pre-cleaning unit 11, the post-cleaning unit 15, and the radiation dose measurement unit 16 has been described as an example of the system configuration. However, these are not indispensable configurations, and as necessary. May or may not be included. In the first cleaning unit 11 and the second cleaning unit 15, the case of performing the cleaning using the primary cleaning liquid 112 and the secondary cleaning liquid 152 has been described. However, in the present invention, the first cleaning unit performs the cleaning using the blast material. The post-cleaning unit may perform cleaning using compressed air. Furthermore, the radiation dose measuring unit is not limited to the unit that measures the radiation dose of the heat transfer tube and the fin member after blast decontamination, and may be the unit that measures the radiation dose before blast decontamination.

  As described above, both the finned heat exchanger decontamination method and the finned heat exchanger decontamination system according to the present invention include fins contaminated with radioactive substances in nuclear facilities such as nuclear power plants. Useful for decontamination of heat exchangers.

It is the block diagram which showed typically the decontamination system of the heat exchanger with a fin which concerns on embodiment of this invention. It is explanatory drawing which showed typically the process of the decontamination system of the heat exchanger with a fin which concerns on embodiment of this invention. It is explanatory drawing which showed typically the separation process by the separation unit which comprises the decontamination system of the heat exchanger with a fin shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Decontamination system 11 Front cleaning unit 111 1st cleaning nozzle 112 Primary cleaning liquid 12 Slit formation unit 120 Notch member 13 Separation unit 130 Cutting member 130a Hollow part 131 Blade edge part 131a Tip edge 131b Convex part 132 Taper part 133 Base 14 Unit 141 Blast nozzle 142 Blast material 15 Post-cleaning unit 151 Second cleaning nozzle 152 Secondary cleaning liquid 16 Radiation dose measurement unit 17 Control unit 20 Heat exchanger with fins 21 Heat transfer tube 21
22 Fin member 23 Slit

Claims (6)

A long cylindrical heat transfer tube whose inside is a flow path for the heat medium;
A finned heat exchanger decontamination method comprising: a plurality of fin members erected on an outer peripheral surface of the heat transfer tube along an outer peripheral direction of the heat transfer tube and arranged in an axial direction of the heat transfer tube In
By pressing the cylindrical cutting member whose tip edge is the cutting edge in such a manner that the heat transfer tube relatively enters the hollow inside of the cutting member, the fins while cutting the surface of the heat transfer tube by the tip edge A separation step of separating the member from the heat transfer tube;
A decontamination step of blast decontamination of the fin member separated by the separation step. Including a slit forming step of forming a slit in each fin member;
2. The decontamination method for a finned heat exchanger according to claim 1, wherein in the separation step, each fin member having slits formed in the slit formation step is separated from the heat transfer tube.   The method for decontaminating a finned heat exchanger according to claim 1 or 2, wherein a tip edge of the cutting member is formed in a wave shape along a circumferential direction. A long cylindrical heat transfer tube whose inside is a flow path for the heat medium;
A finned heat exchanger having a plurality of fin members erected on the outer peripheral surface of the heat transfer tube along the outer peripheral direction of the heat transfer tube and aligned in the axial direction of the heat transfer tube is decontaminated. In the decontamination system for
By pressing the cylindrical cutting member whose tip edge is the cutting edge in such a manner that the heat transfer tube relatively enters the hollow inside of the cutting member, the fins while scraping the surface of the heat transfer tube by the tip edge Separating means for separating the member from the heat transfer tube;
A decontamination system for a finned heat exchanger, comprising: a decontamination unit for blast decontamination of the fin member separated by the separation unit. Slit forming means for forming a slit in each fin member,
The decontamination system for a finned heat exchanger according to claim 4, wherein the separation means separates each fin member having slits formed by the slit formation means from the heat transfer tube.   The decontamination system for a finned heat exchanger according to claim 4 or 5, wherein a tip edge of the cutting member is formed in a wave shape along a circumferential direction.

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