KR102651275B1 - Electric Discharge Machining System for Steam Generator Heat Exchanger Tube and Heat Exchanger Tube Incision Method of Steam Generator Using The Same - Google Patents

Abstract

Various positions of the heat pipe can be easily discharged, the direction and position of the electrode can be easily set, and discharge liquid consumption can be reduced by causing a spark discharge inside the heat pipe of the steam generator between the heat pipe and the heat pipe. An electrode on which processing is performed, a device base that is inserted into the heat pipe and moves back and forth, the electrode is mounted on the tip, and is capable of moving the electrode back and forth, left and right, and rotation, a device stand moving cable connected to the device stand, and a device installed outside the heat pipe. A first transfer roller that moves the device base moving cable back and forth, a discharge liquid supply cable that supplies discharge liquid between the electrode and the heat transfer tube as the discharge liquid is transported inside and discharged from the tip, and a discharge liquid supply cable installed outside the heat transfer tube to supply discharge liquid. Provided is an electrical discharge machining system for a heat transfer tube of a steam generator including a second transfer roller that moves the cable back and forth.

Description

Electric discharge machining system for steam generator heat exchanger tube and heat exchanger tube incision method of steam generator using the same {Electric Discharge Machining System for Steam Generator Heat Exchanger Tube and Heat Exchanger Tube Incision Method of Steam Generator Using The Same}

The present invention relates to an electrical discharge machining system for a heat transfer tube of a steam generator and a method of cutting a heat transfer tube of a steam generator using the same. Discharge machining is performed when processing such as incision or cutting of a heat transfer tube is required to remove foreign substances inside the steam generator or maintain the heat transfer pipe. An electric discharge machining system for the heat transfer tube of a steam generator that facilitates the processing of the heat transfer tube, facilitates the bending of the heat transfer pipe, and safely removes foreign substances through the opening formed through processing to prevent the loss of foreign substances, and cutting the heat transfer tube of the steam generator using the same. It's about method.

In general, a steam generator is a major device that constitutes the primary cooling system of a nuclear power plant. It is a heat exchange device that generates steam by crossing the primary cooling system that circulates the nuclear reactor core and the secondary cooling system of the turbine/generator system to remove radioactive materials. It is one of the most important devices in a nuclear reactor that also has a protective function to prevent primary coolant containing , from leaking to the secondary side.

The steam generator varies depending on the model and capacity, but is usually a huge structure with a height of about 20 meters, a top diameter of about 6 meters, a container wall thickness of about 120 to 170 millimeters, and a weight of about 700 tons. It produces steam with a dryness of 99.75% or more. It is the key device that generates

Steam generators are divided into recirculating type and direct current type or once through type depending on the heat exchange method or the type of heat transfer pipe (or heat exchange tube). In the case of the recirculating type, the water supplied to the water supply pipe flows through the downward flow passage. It goes down and flows across the tube sheet, rising to the top and absorbing heat. In this process, the primary coolant flows inside the pipe, and the temperature of this primary coolant inlet (hot leg, high temperature observation) is around 315~327℃, and the temperature of the cold leg after heat is transferred to the secondary side. is around 288℃.

Westinghouse (WH) and Combustion Engineering (CE) use recirculating steam generators (RSG), while Babcock and Wilcox (B&W) also use once-through steam generators (OTSG). . Most power plants adopt the “U” shaped recirculation type.

Among the defects that currently occur in steam generators, damage to the heat transfer pipe is pointed out as the biggest problem, and stress corrosion cracking (SCC) and fluid induction on the primary and secondary sides due to the use environment such as high temperature and high pressure coolant. Various damages occur due to the structural characteristics of the flow and steam generator. In addition, such damage is caused by a complex effect of water-chemical treatment, thermodynamic design, material selection, manufacturing method, and operation method.

According to the Nuclear Safety Council (a regional organization of the Nuclear Safety and Security Commission), one of the causes of damage to the heat pipe of the steam generator is the presence of foreign substances inside the steam generator, such as wires, bolts, hammers, and parts separated from the secondary system introduced during the manufacturing process. It is becoming.

These foreign substances move inside the steam generator due to the fluid-induced flow that occurs inside the steam generator, which wears out the heat transfer tube and eventually breaks the heat transfer tube, creating a hole.

The foreign substances inside the steam generator cannot be removed using conventional techniques, and when damage occurs due to foreign substances, the heat pipe operation is stopped (heat pipes are blocked) and the heat pipes are regenerated. This can cause a fatal reduction in the utilization rate of nuclear power plants. There is an urgent need for countermeasures.

Public Patent Publication No. 10-2013-0023443 (2013. 03. 08.)

The present invention was made with a bird's eye view of the above-mentioned points, and is capable of electrical discharge machining of a heat transfer tube by accurately inserting an electrode at a set point inside the heat transfer pipe, and is capable of performing discharge machining on the straight pipe portion and the curved pipe portion of the U-shaped heat transfer pipe. The purpose is to provide an electric discharge machining system and a method of cutting a heat transfer tube of a steam generator using the same.

The electrical discharge machining system for the heat transfer pipe of a steam generator proposed by the present invention includes an electrode on which discharge machining of the heat transfer tube is performed by causing a spark discharge between the heat transfer tube and the heat transfer tube of the steam generator, and an electrode that is inserted into the heat transfer tube and moves back and forth, and the tip is A device base on which the electrode is mounted and capable of moving the electrode back and forth, left and right, and rotationally, a device base moving cable connected to the device base, and a first transport installed outside the heat pipe to move the device base moving cable back and forth. A roller, a discharge liquid supply cable that supplies discharge liquid between the electrode and the heat transfer tube while the discharge liquid is transported inside and discharged from the tip, and a second installed outside the heat transfer tube to move the discharge liquid supply cable back and forth. It includes a transfer roller.

The device base includes a rotation support frame to which the device base moving cable is connected on one side, a rotation drive motor installed in the rotation support frame, a forward and backward movement support frame rotated by the rotation drive motor, and one side of the forward and backward movement support frame. A front and rear drive motor installed, a left and right movable support frame that moves back and forth with the front and rear drive motor, a transfer screw that moves the left and right support frame back and forth with the driving force of the front and rear drive motor, and a left and right support frame on one side of the left and right support frame. It includes a left and right moving frame that is movably installed and on which the electrode is mounted on one side, a left and right driving motor installed in the left and right moving support frame, and a left and right moving mechanism that moves the left and right moving frame left and right with the left and right driving motor. .

In addition, the present invention further includes a nozzle for spraying the discharge liquid transported through the discharge liquid supply cable, a camera for photographing the inside of the heat transfer tube, and a cable bear on which the discharge liquid supply cable is loaded and inserted and moved inside the heat transfer tube. It is also possible to include

In addition, the present invention may further include a discharge liquid circulation unit that purifies the discharge liquid discharged from the heat transfer tube and supplies it to the discharge liquid supply cable.

The discharge liquid circulation unit includes a first storage tank in which the discharge liquid discharged from one side of the heat transfer tube is accommodated, a second storage tank in which the discharge liquid discharged from the other side of the heat transfer tube is accommodated, and a first storage tank and a second storage tank. A first pipe through which the discharge liquid is transferred, a settling tank containing the discharge liquid transferred through the first pipe, a first filter for purifying the discharge liquid transferred through the first pipe, and a sedimentation tank accommodated in the settling tank. A second pipe through which the entire amount is transferred, a discharge liquid storage tank containing the discharge liquid transferred to the second pipe, a second filter for purifying the discharge liquid transferred through the second pipe, the discharge liquid storage tank and the It includes a third pipe connecting the discharge liquid supply cable.

In addition, the method of cutting the heat transfer tube of a steam generator using the electrical discharge machining system for the heat transfer tube of the steam generator proposed by the present invention involves inserting a device base with an arch-shaped electrode installed at the front end into the U (U)-shaped heat transfer tube of the steam generator to cut the rear end of the electrode. An electrode insertion step of placing an electrode at the end point of a straight pipe portion of a heat transfer tube, a discharge liquid supply preparation step of inserting a discharge liquid supply cable with a camera installed at the tip into the heat transfer tube and placing the tip opposite to the electrode, and the camera. After checking whether the electrode is in the positive direction through the electrode image captured through the electrode, if it is not in the positive direction, the electrode rotation alignment step of rotating the electrode and placing it in the positive direction, and fixing the device stand in close contact with the inner tube wall of the heat pipe to A processing preparation step to prevent rotation, and an electric discharge machining step in which the curved pipe of the heat transfer pipe is cut by electric discharge machining to form a window as the device table moves the electrode straight while discharging the discharge fluid to the tip of the discharge fluid supply cable. It is made including.

In the direction alignment step, a first line horizontally displayed on the electrode is photographed through the camera, the image captured by the camera is displayed on a monitor, and the monitor displays a second line for guiding the forward direction of the electrode. These are displayed together horizontally, and the user checks whether the first line and the second line are parallel and then rotates the electrodes using the device base so that they are parallel to each other when they are not parallel.

In the electric discharge machining step, the device base is controlled to move straight ahead by the minimum moving distance when the electrode moves back and forth.

According to the electrical discharge machining system for the heat pipe of a steam generator according to an embodiment of the present invention, the electrode can rotate, move back and forth, and move left and right within the heat pipe, so various positions of the heat pipe can be easily discharge machining, and a large area can be done at once. Since electrical discharge machining can be performed, the processing time is shortened and the machined surface can be discharge machined uniformly.

In addition, according to the electrical discharge machining system for the heat pipe of the steam generator according to the embodiment of the present invention, the direction and position of the electrode can be set through monitoring using a camera, thereby improving work efficiency.

In addition, according to the electric discharge machining system for the heat transfer tube of the steam generator according to the embodiment of the present invention, when the discharge liquid supplied to the electric discharge machining area is discharged from the heat transfer tube, the discharge liquid is purified and circulated so that it is supplied to the discharge area again, thereby discharging the discharge. Less total amount is consumed.

Figure 1 is a side view showing an electrical discharge machining system for a heat transfer tube of a steam generator according to an embodiment of the present invention.
Figure 2 is a partial enlarged view of part of Figure 1.
Figure 3 is a partial enlarged view of another part of Figure 1.
Figure 4 is a partial enlarged view of another part of Figure 1.
Figure 5 is a side view showing an electrode of an electrical discharge machining system for a heat transfer tube of a steam generator according to an embodiment of the present invention.
Figure 6 is a cross-sectional view showing an electrode of the electrical discharge machining system for a heat pipe of a steam generator according to an embodiment of the present invention.
Figure 7 is a side view showing the device base of the electrical discharge machining system for the heat transfer tube of the steam generator according to an embodiment of the present invention.
Figure 8 is a longitudinal cross-sectional view showing a rotation support frame in the device base of the electrical discharge machining system for heat transfer tubes of a steam generator according to an embodiment of the present invention.
Figure 9 is a longitudinal cross-sectional view showing the forward and backward movement support frame and transfer screw in the device base of the electrical discharge machining system for heat transfer tubes of a steam generator according to an embodiment of the present invention.
Figure 10 is a cross-sectional view showing the transfer screw in the device base of the electrical discharge machining system for heat transfer tubes of a steam generator according to an embodiment of the present invention.
Figure 11 is a longitudinal cross-sectional view showing the operating state of the forward and backward movement support frame and transfer screw in the device base of the electric discharge machining system for heat transfer tubes of a steam generator according to an embodiment of the present invention.
Figure 12 is a side view showing the left and right movable support frame and the left and right movable frame in the device base of the electrical discharge machining system for heat transfer tubes of a steam generator according to an embodiment of the present invention.
Figure 13 is a longitudinal cross-sectional view showing the left and right moving mechanism in the device base of the electrical discharge machining system for heat transfer tubes of a steam generator according to an embodiment of the present invention.
Figure 14 is a cross-sectional view showing the left and right moving mechanism in the device base of the electrical discharge machining system for heat transfer tubes of a steam generator according to an embodiment of the present invention.
Figure 15 is a side view showing the operating state of the left and right moving frames in the device base of the electrical discharge machining system for heat transfer tubes of a steam generator according to an embodiment of the present invention.
Figure 16 is a perspective view showing the first fixing part and the second fixing part in the device base of the electrical discharge machining system for the heat transfer tube of the steam generator according to an embodiment of the present invention.
Figure 17 is an exploded perspective view showing the first fixing part and the second fixing part in the device base of the electrical discharge machining system for the heat transfer tube of the steam generator according to an embodiment of the present invention.
Figure 18 is a longitudinal cross-sectional view showing the first fixing part and the second fixing part in the device base of the electric discharge machining system for the heat transfer tube of the steam generator according to an embodiment of the present invention.
Figure 19 is a longitudinal cross-sectional view in an operating state showing the first fixing part and the second fixing part in the device base of the electric discharge machining system for heat transfer tubes of a steam generator according to an embodiment of the present invention.
Figure 20 is a side view showing the first movement amount measuring part of the electrical discharge machining system for the heat pipe of the steam generator according to an embodiment of the present invention.
Figure 21 is a cross-sectional view showing a discharge liquid supply cable of an electrical discharge machining system for a heat transfer tube of a steam generator according to an embodiment of the present invention.
Figure 22 is a side view showing the discharge liquid supply cable and cable bear of the electrical discharge machining system for the heat transfer tube of the steam generator according to an embodiment of the present invention.
Figure 23 is a front view showing a camera head of the electrical discharge machining system for a heat pipe of a steam generator according to an embodiment of the present invention.
Figure 24 is a side view showing a camera head of the electrical discharge machining system for a heat pipe of a steam generator according to an embodiment of the present invention.
Figure 25 is a side view showing the second movement amount measuring part of the electrical discharge machining system for the heat transfer tube of the steam generator according to an embodiment of the present invention.
Figure 26 is a diagram showing the discharge liquid circulation part of the electrical discharge machining system for the heat transfer tube of the steam generator according to an embodiment of the present invention.
Figure 27 is a block diagram showing a method of cutting a heat transfer tube of a steam generator using an electrical discharge machining system for a heat transfer tube of a steam generator according to an embodiment of the present invention.
Figure 28 is a cross-sectional view showing the discharge machining step by moving the electrode left and right in the method of cutting the heat transfer tube of the steam generator according to an embodiment of the present invention.
Figure 29 is a cross-sectional view showing the electric discharge machining step by moving the electrode back and forth in the method of cutting a heat transfer tube of a steam generator according to an embodiment of the present invention.
Figure 30 is a cross-sectional view showing the discharge machining step by rotating the electrode in the method of cutting a heat transfer tube of a steam generator according to an embodiment of the present invention.
Figure 31 is a cross-sectional view for explaining the minimum movement distance of the electrode during the discharge machining step in the method of cutting the heat transfer tube of the steam generator according to an embodiment of the present invention.

Next, a preferred embodiment of the electrical discharge machining system for a heat transfer tube of a steam generator according to the present invention and a method of cutting a heat transfer tube of a steam generator using the same will be described in detail with reference to the drawings.

Hereinafter, the same reference numerals will be used for technical elements performing the same function, and repeated detailed descriptions will be omitted to avoid redundant description.

In addition, the examples described below are illustrative in order to effectively demonstrate preferred embodiments of the present invention, and should not be construed to limit the scope of the present invention.

First, the electrical discharge machining system for the heat transfer tube of the steam generator according to an embodiment of the present invention is a heat transfer tube ( 4), an electrode 10 on which electrical discharge processing of the heat transfer tube 4 is performed by causing a spark discharge between the electrodes 10, and the electrode 10, which is inserted into the heat transfer tube 4 and moves back and forth in the longitudinal direction of the heat transfer tube 4, and is placed at the tip of the electrode. A device base 100 on which (10) is mounted and capable of moving the electrode 10 back and forth, left and right, and rotationally, a device base moving cable 200 connected to the rear end of the device base 100, and A first cable movement guide tube (230) is connected to one (lower) end of the heat pipe (4) and moves the device stand moving cable (200) inserted therein, and is installed outside the heat pipe (4) and moves the device. A first transfer roller 220 that moves the main movable cable 200 back and forth, a first movement amount measuring unit 250 that measures the forward and backward movement length of the device movable cable 200, and the first device movable cable 200 ), a first cable reel 260 for winding or unwinding, and a discharge liquid supply in which discharge liquid is transferred inside and discharged from the tip during discharge processing, and discharge liquid is supplied between the electrode 10 and the heat transfer tube 4. A cable 300, a cable bear 310 inserted inside the heat transfer tube 4 and supporting the discharge liquid supply cable 300, and a cable bear 310 installed at the tip of the cable bear 310 to photograph the electrode 10. a camera 312 that is connected to the other end of the heat pipe 4 and a second cable moving guide pipe 330 into which the discharge liquid supply cable 300 is inserted and moved, and the heat pipe 4 ) A second transfer roller 340 installed outside and moving the discharge liquid supply cable 300 back and forth, a second movement amount measuring unit 350 that measures the front and rear movement length of the discharge liquid supply cable 300, and , purifying the discharge liquid drained through the second cable reel 360, which winds or unwinds the discharge liquid supply cable 300, and the first cable movement guide pipe 210 and the second cable movement guide pipe 310. and a discharge liquid circulation unit 400 that supplies and circulates the purified discharge liquid to the discharge liquid supply cable 300.

Referring to Figures 5 and 6, the electrode 10 is fixed to the tip of the device stand 100 and is formed in a "-(one)" shape, so that when inserted into the heat transfer tube 4, the electrode 10 is fixed to the tip of the device stand 100. It consists of a vertical portion 11 disposed in parallel with the straight pipe portion 4a, and a curved portion 12 extending from one end of the vertical portion 11 and forming an arch shape.

The curved portion 12 may be formed with a curvature corresponding to the curvature of the curved pipe portion 4b at the center of the heat transfer pipe 4.

The electrode 10 has one side formed with a circumferential surface corresponding to the inner circumferential surface of the heat pipe 4, and its cross-sectional shape may be approximately half-moon or crescent.

If the electrode 10 is formed as described above, discharge machining can be easily performed on one or both ends of the curved pipe portion 4b of the “U” shaped heat transfer tube 4.

The electrode 10 can also be formed in various shapes depending on the processing area of the heat pipe 4 or the shape to be processed.

Referring to FIG. 7, the device stand 100 includes a rotation support frame 101 to which the device table moving cable 200 is connected, a rotation drive motor 102 installed on the rotation support frame 101, and the A forward and backward movement support frame 120 that is rotated by the driving force of the rotation drive motor 102, a forward and backward drive motor 122 installed on one side of the forward and backward movement support frame 120, and the forward and backward movement support frame 120. A first fixing part 130 for fixing to the inner surface of the heat pipe 4, a left and right support frame 140 that moves back and forth with the driving force of the front and rear drive motor 122, and a left and right support frame 140 are installed on the left and right support frames 140. The left and right driving motor 142, the transfer screw 150 that moves the left and right movable support frame 120 back and forth with the driving force of the front and rear drive motor 122, and the left and right movable support frame 140 are connected to the heat transfer pipe ( 4) A second fixing part 160 for fixing to the inner surface, and a left and right movable frame 170 installed to be movable in the left and right directions on one side of the left and right movable support frame 140 and on which the electrode 10 is mounted on one side. ) and a left and right moving mechanism 180 that moves the left and right moving frame 170 left and right with the driving force of the left and right driving motor 142.

Referring to FIG. 8, the rotation support frame 101 has a substantially cylindrical shape, and the rotation drive motor 102 is mounted on one side of the inside.

A rotation angle measurement sensor 104 may be installed on the rotation support frame 101 to measure the rotation angle of the rotation drive motor 102. The rotation angle measurement sensor 104 may be made of a rotary encoder.

A rotary arm 110 rotated by a rotary drive motor 102 is installed on the other side of the rotary support frame 101.

The rotary arm 110 is rotated by receiving the rotational force of the rotary drive motor 102 through a gear. The gear may be made of an internal gear.

A hinge 112 may be installed in the center of the rotary arm 110. The hinge 112 may be a universal hinge.

The first fixing part 130 is connected to one side of the rotary arm 110, and the first fixing part 130 fixes the forward and backward movement support frame 120 to the inner surface of the heat pipe 4. It is configured to unfasten. The first fixing part 130 will be described in more detail below.

Referring to FIGS. 9 to 11, the forward and backward movement support frame 120 has a substantially cylindrical shape, one side is connected to the first fixing part 130, and the forward and backward driving motor 122 is installed therein.

A rotation angle measurement sensor 124 may be installed in the forward and backward movement support frame 120 to measure the rotation angle of the forward and backward driving motor 122. The rotation angle measurement sensor 124 may be made of a rotary encoder.

A forward and backward movable arm 126 is installed on the other side of the forward and backward movable support frame 120, and the forward and backward movable arm 126 is connected to the left and right movable support frame 140.

The transfer screw 150 is installed inside the back and forth support frame 120 and is rotated by the front and rear drive motor 122, and includes a transfer shaft 151 on which a screw is formed on the outer circumference, and the back and forth movement arm 126. ) and includes a transfer nut 152 that is installed on one side and coupled to the transfer shaft 151.

The second fixing part 160 is installed between the forward and backward movable arm 126 and the left and right movable support frame 140. The second fixing part 160 is configured to fix or release the left and right movable support frame 140 to the inner surface of the heat pipe 4.

The second fixing part 160 will be described in more detail below.

Referring to FIGS. 12 to 15 , a rotation angle measurement sensor 144 may be installed in the left and right movable support frame 140 to measure the rotation angle of the left and right drive motors 142. The rotation angle measurement sensor 144 may be made of a rotary encoder.

The left and right moving mechanism 180 includes a transfer shaft 181 rotated by the front and rear drive motor 142, and a transfer nut 184 that is screw-coupled with the transfer shaft 181 and has protruding cams 185 on both sides. ) and a home cam 186 formed on both sides of the left and right moving frame 170, the protruding cam 185 is assembled inside, and the left and right moving frame 170 moves left and right when the protruding cam 185 moves back and forth. It is done including.

Here, a limit switch that measures the transfer range of the transfer nut 184 may be installed on the left and right movable support frame 144.

Next, the first fixing part 130 and the second fixing part 160 will be described in more detail.

First, referring to FIGS. 16 to 19, the first fixing part 130 includes a fixing body 131 having a cylindrical shape and having a plurality of ribs 132 formed at regular intervals around one end edge. , an expansion ring 133 coupled to the outside of the rib 132, a fixed drive motor 134 installed inside the fixed body 131 and capable of forward and reverse rotation, and a cylindrical shape, the fixed drive motor A rotating cam cylinder 135 that is rotated by (134) and has a spiral cam hole 136 formed on the side, and is installed to be movable back and forth inside the rotating cam cylinder 135 and uses a plurality of ribs 132 when moving forward. A forward and backward moving member 137 that spreads outward to expand the expansion ring 133, one side of which is fixed to the forward and backward moving member 137 and the other side of which is assembled into the cam hole 136, moves the rotating cam cylinder 135 forward and backward. When rotating, the forward and backward moving member 137 includes a pair of moving pins 138 that move back and forth.

In the above, the fixing body 131 has a pair of long holes 131a on both sides so that the moving pin 138 can move, and the moving pin 138 is assembled and fixed on both sides of the forward and backward moving member 137. A fixing hole 137a is formed.

One side of the fixed body 131 is connected to the rotary arm 110, and the other side is connected to one side of the forward and backward movement support frame 120. That is, the rotating arm 110, the fixed body 131, and the forward/backward movable support frame 120 are installed in succession and rotated together.

A rotation angle measurement sensor 134a may be further installed on the fixed body 131 to measure the rotation angle of the fixed drive motor 134. The rotation angle measurement sensor 134a may be made of a rotary encoder.

The fixed drive motor 134 rotates the rotating cam cylinder 135 through gear driving. The gear drive may use an internal gear.

The elastic ring 133 is made of rubber, and as the rib 132 opens and expands due to the forward movement of the forward and backward moving member 137, one side comes into close contact with the inner wall of the heat transfer pipe 4 and the forward and backward moving member ( When the opening of the rib 132 is released due to the backward movement of 137), it is contracted to its original state and spaced apart from the inner wall of the heat transfer tube 4.

The second fixing part 160 can be implemented with the same configuration as the first fixing part except that the installation position is different.

That is, referring to FIGS. 16 to 19, the second fixing part 160 includes a fixing body 161 having a cylindrical shape and having a plurality of ribs 162 formed at regular intervals along the edge of one end, An expansion ring 163 coupled to the outside of the rib 162, a fixed drive motor 164 installed inside the fixed body 161 and capable of rotating forward and backward, and a cylindrical shape, the fixed drive motor ( A rotating cam cylinder 165 that is rotated by 164) and has a spiral cam hole 166 formed on the side, and is installed to be movable back and forth inside the rotating cam cylinder 165 and moves the plurality of ribs 162 to the outside when moving forward. A back-and-forth moving member 167 that expands the expansion ring 163 by opening to the side, one side of which is fixed to the back-and-forth moving member 167 and the other side is assembled into the cam hole 166 to rotate the rotating cam cylinder 165 forward and backward. The forward and backward moving member 167 includes a pair of moving pins 168 that move back and forth.

In the above, the fixing body 161 is provided with a pair of long holes 161a on both sides so that the moving pin 168 can move, and the moving pin 168 is assembled and fixed on both sides of the forward and backward moving member 167. A fixing hole 167a is formed.

One side of the fixed body 161 is connected to the forward and backward movable arm 126, and the other side is connected to the left and right movable support frame 140. That is, the forward and backward movable arm 126, the fixed body 161, and the left and right movable support frames 140 are installed in succession and move forward and backward together.

The device stand 100 according to an embodiment of the present invention configured as described above can be moved forward and backward as the first transfer roller 220 rotates forward and backward while holding the device table moving cable 200.

Inside the device base moving cable 200, wires connected to the electrodes 10 and the motors and sensors of the device base 100 may be installed.

Referring again to FIG. 3, the first transfer roller 220 bites the device moving cable 200 from both sides outside the steam generator 2 and rotates forward and backward by a motor (not shown), thereby moving the device moving cable (200). As 200) is moved back and forth, the device base 100 can be moved back and forth in the longitudinal direction of the heat pipe (4).

Here, the transfer amount (transfer length) of the device base moving cable 200 can be measured through the first movement amount measuring unit 240, and based on the measured transfer amount, the device base 100 is stored inside the heat pipe 4. It is possible to calculate the inserted position.

Referring to FIG. 20, the first movement amount measuring unit 240 includes a rotating roller 241 in rolling contact with the device moving cable 200, and a rotation angle measurement sensor that measures the rotation angle of the rotating roller 241. It is made including (242).

The rotation angle measurement sensor 242 may be made of a rotary encoder.

The first movement amount measuring unit 240 may further include a push roller 244 that brings the device-to-moving cable 200 into close contact with the rotating roller 241.

The first cable reel 260 winds the device cable 200 when the first transfer roller 220 pulls the device cable 200 and moves it backward, and the first transfer roller 220 moves the device cable 200 backward. When the cable 200 is pushed and moved forward, the device-to-moving cable 200 is unwinded.

The device stand 100 and the device table moving cable 200 are guided from the outside of the steam generator 2 into the heat transfer tube 4 through the first cable moving guide tube 230, and the discharge liquid supply cable 300 is guided from the outside of the steam generator (2) into the heat transfer tube (4) through the second cable movement guide tube (330).

Referring to FIG. 21, the discharge liquid supply cable 300 may include a discharge liquid transfer pipe 302 through which the discharge liquid is transferred, and a plurality of wires 304.

Ultrapure water may be used as the discharge liquid supplied through the discharge liquid supply cable 300.

Referring to Figures 22 and 23, a camera 312 is installed at the tip of the cable bear 310. The camera 312 is fixed to the camera head 313, which is elastically connected to the cable bear 310 and the elastic frame 314.

The elastic frame 314 may be in the form of a coil spring.

In the above, a nozzle 316 that is connected to the discharge liquid transfer pipe 302 and sprays discharge liquid may be installed on the camera head 313, and a light 317 may also be installed.

Referring to FIG. 24, the camera 312 photographs the electrode 10 in order to align the electrode 10 in the positive direction.

Here, the positive direction of the electrode 10 is a state in which the curved portion 12 is bent in the same direction as the bent pipe portion 4b.

A first line 14 is displayed horizontally in the shape of the letter "-(one)" on the electrode 10, and a second line 14 indicating the positive direction of the electrode 10 is displayed on the monitor 318 connected to the camera 312. Line 319 is displayed in the shape of a “+ (twelve)” character.

Here, the positive direction of the electrode 10 may be when the horizontal lines of the first line 14 and the second line 319 are parallel, and if the first line 14 is not in the positive direction, the device base 100 By driving the rotation drive motor 102 installed on the rotation support frame 101 to rotate the electrode 10, it is possible to place the electrode 10 in the forward direction.

Although the first line 14 is not shown in the drawing, it can be displayed vertically in the shape of the character "-(one)" or in the shape of the character "+(ten)".

In addition, the second line 319 may be displayed horizontally in the shape of the letter “-(one)” or vertically in the shape of the letter “-(one)” corresponding to the shape of the first line 14. .

Meanwhile, the discharge liquid supply cable 300 and the cable bear 310 move forward and backward in the longitudinal direction of the heat transfer tube 4 as the second transfer roller 340 rotates forward and backward while holding the discharge liquid supply cable 300. It can be.

Referring again to FIG. 4, the second transfer roller 340 bites the discharge liquid supply cable 300 from both sides outside the steam generator 2 and supplies the discharge liquid when rotating forward and backward by a motor (not shown). As the cable 300 is moved back and forth, the cable bear 310 and the camera head 313 can be moved back and forth along the longitudinal direction of the heat pipe 4.

Here, the transfer amount (transfer length) of the discharge liquid supply cable 300 can be measured through the second movement amount measuring unit 350, and based on the measured transfer amount, the camera head 313 is installed inside the heat pipe 4. It is possible to calculate the inserted position.

Referring to FIG. 25, the second movement amount measuring unit 350 includes a rotating roller 351 in rolling contact with the discharge liquid cable 300, and a rotation angle measurement sensor that measures the rotation angle of the rotating roller 351. It consists of (352).

The rotation angle measurement sensor 352 may be made of a rotary encoder.

The second movement amount measuring unit 350 may further include a push roller 354 that brings the discharge liquid supply cable 300 into close contact with the rotating roller 351.

The second cable reel 360 winds the discharge liquid supply cable 300 when the second transfer roller 340 pulls the discharge liquid supply cable 300 and moves it backward, and the second transfer roller 340 When the discharge liquid supply cable (300) is pushed and moved forward, the discharge liquid supply cable (300) is unwinded.

Meanwhile, the discharge liquid sprayed onto the electrical discharge machining area through the nozzle 316 flows through the first cable guide tube 230 and the second cable guide tube 330 connected to both ends of the heat transfer tube (4). It can be drained to the outside, and in this case, the drained discharge liquid is transferred to the discharge liquid circulation unit 400.

Referring to FIG. 26, the discharge liquid circulation unit 400 includes a first storage tank 410 that accommodates the discharge liquid discharged through the first cable movement guide pipe 230, and the second cable movement guide pipe ( A second storage tank 420 that accommodates the discharge liquid discharged through 330), a first pipe 430 through which the discharge liquid contained in the first storage tank 410 and the second storage tank 420 is transferred, and A settling tank 440 that accommodates the discharge liquid transferred through the first pipe 430, a first filter 450 that purifies the discharge liquid transferred through the first pipe 430, and the settling tank 440 A second pipe 460 through which the discharge liquid received is transferred, a discharge liquid storage tank 470 into which the discharge liquid transferred into the second pipe 460 is received, and a discharge liquid transferred through the second pipe 460. It includes a second filter 480 for purifying the discharge liquid, and a third pipe 490 connecting the discharge liquid storage tank 470 and the discharge liquid supply cable 480.

Next, a method of cutting the heat transfer tube of a steam generator using the electrical discharge machining system for the heat transfer tube of the steam generator configured as described above will be described with reference to the drawings.

Referring to FIG. 27, the method of cutting a heat transfer tube of a steam generator according to an embodiment of the present invention includes an electrode insertion step (S10), a discharge liquid supply preparation step (S20), an electrode direction alignment step (S30), and processing preparation. It includes a step (S40) and an electric discharge machining step (S50).

In the electrode insertion step (S10), the device base 100 is inserted into the heat transfer tube 4 through an opening at one end of the heat transfer tube 4, and the rear end of the electrode 10 is inserted into the heat transfer tube 4. This is the step of placing the straight pipe section (4a) at the end point (see Figures 1, 2, and 5).

That is, as the electrode 10 is mounted on the tip of the device stand 100, the device stand 100 is inserted into one straight pipe portion 4a of the “U” shaped heat transfer tube 4 of the steam generator. The rear end of the curved portion 12 of the electrode 10 is placed at the end of one straight pipe portion 4a of the heat transfer tube 4.

Here, the device base 100 moves forward in the pipe direction (longitudinal direction) of the heat transfer pipe 4 as the device base moving cable 200 connected to the rear end moves forward through the first transfer roller 220. (See Figures 3 and 7)

In the discharge liquid supply preparation step (S20), the discharging liquid supply cable 300 is inserted into the heat transfer tube 4 through an opening at the other end of the heat transfer tube 4, and the distal end is placed on the opposite side of the electrode 10. In this step, the discharge liquid supply cable 300 moves back and forth in the pipe direction (longitudinal direction) of the heat transfer tube 4 by moving the discharge liquid supply cable 300 back and forth through the second transfer roller 340. It is moved (see Figures 1, 2, and 4).

Here, the front part of the discharge liquid supply cable 300 is supported and moved by the cable bear 310, and a camera 312 for photographing the electrode 10 and a nozzle for spraying the discharge liquid are installed in front of the cable bear 310 ( Camera heads 313 on which 316) are respectively installed are provided.

The electrode direction alignment step (S30) is performed by checking whether the electrode 10 is in the positive direction using an image of the electrode 10 captured through the camera 312 installed at the tip of the discharge liquid supply cable 300. If the electrode 10 is not in the positive direction, the This is the step of rotating the electrode 10 using the device base 100 and placing it in the forward direction (see Figure 24).

Here, the positive direction of the electrode 10 is a direction in which the bent direction of the curved portion 12 of the electrode 10 coincides with the bent direction of the curved pipe portion 4b of the heat transfer tube 4.

In the electrode direction alignment step (S30), the camera 312 captures a first line 14 horizontally marked with a "-(one)" shape on the electrode 10 and displays it on the monitor. A second line 319 in the shape of a "+ (twelfth)" character indicating the positive direction of the electrode 10 is displayed, and the user can see that the horizontal lines of the first line 14 and the second line 319 are aligned with each other. After checking whether it is in the positive direction by checking whether it is parallel, etc., if it is not in the positive direction, rotate the electrode 10 to align it in the positive direction.

The rotation of the electrode 10 can be performed by driving the rotation drive motor 102 of the device base 100 to rotate the forward and backward movement support frame 120 (see FIGS. 7 and 8).

In the processing preparation step (S40), prior to discharge machining the heat transfer tube 4, one side of the device base 100 is fixed to the tube wall of the heat transfer tube 4 to prevent rotation or forward and backward movement of the electrode 10. It's a step.

Here, prevention of rotation of the device base 100 can be done by the first fixing part 130, and prevention of forward and backward movement can be done by operation of the second fixing part 160 (see FIGS. 18 and 19). )

That is, as the forward and backward moving member 137 of the first fixing part 130 moves forward to expand the expansion ring 133, the outer surface of the expansion ring 133 comes into close contact with the inner surface of the heat transfer tube 4 and the device base ( As one side of 100) is fixed to the inner surface of the heat pipe 4, rotation of the electrode 10 is prevented.

And as the forward and backward moving member 167 of the second fixing part 160 is moved forward to expand the expansion ring 163, the outer surface of the expansion ring 163 is in close contact with the inner surface of the heat pipe 4 and the device base ( The forward and backward movement of the electrode 10 (100) is prevented.

In the electric discharge machining step (S50), the discharge liquid is discharged through the nozzle 316 installed at the tip of the discharge liquid supply cable 300, and the device base 100 moves the electrode 10. This is the step in which the heat transfer tube (4) is cut through electrical discharge machining to form a window (6) in the heat transfer tube (4).

Referring to FIGS. 28 and 29, the electrode 10 is moved back and forth and left and right by the device base 100 to cut the heat pipe 4, thereby forming a window 6 in the heat pipe 4. .

In addition, the electrode 10 is rotated in the horizontal direction (circumferential direction of the heat pipe) by the device base 100, and then moves forward and backward and/or left and right as shown in FIGS. 28 and 29, thereby creating a wider window (as shown in FIG. 30). 6) It is possible to form.

Referring to FIG. 31, the device base 100 can be controlled so that the electrode 10 moves forward by the minimum movement distance required to cut the heat pipe 4 when the electrode moves forward and backward.

The minimum moving distance (Dmin) is the center of curvature of the bended pipe of the heat pipe (O), the radius of curvature of the out course pipe wall of the bent pipe of the heat pipe (RO), the thickness of the pipe wall of the heat pipe (T), and the distance from the center of curvature of the bended pipe of the heat pipe to the rear end of the front of the electrode. It is calculated by substituting (OE) into Equation 1 below.

In the above, a preferred embodiment of the electrical discharge machining system for a heat transfer tube of a steam generator according to the present invention and a method of cutting a heat transfer tube of a steam generator using the same has been described. However, the present invention is not limited thereto, and the claims, description of the invention, and accompanying drawings It is possible to implement various modifications within the scope of, and this also falls within the scope of the present invention.

2: steam generator 4: heat pipe
10: electrode 11: vertical part
12: curved portion 14: location indicator line
100: device stand 101: rotation support frame
102: rotation drive motor 104: rotation angle measurement sensor
110: Rotating arm 112: Hinge
120: forward and backward movement support frame 122: forward and backward drive motor
126: forward and backward moving arm 124: rotation angle measurement sensor
130: first fixing part 131, 161: fixing body
131a, 161a: long hole 132, 162: rib
133, 163: Expansion ring 134, 164: Fixed drive motor
134a, 164a: Rotation angle measurement sensor 135,165: Rotation cam cylinder
136, 166: Cam hole 137, 167: Forward and backward moving member
137a, 167a: fixing hole 138, 168: moving pin
140: Left and right moving support frame 142: Left and right driving motor
144: rotation angle measurement sensor 150: transfer screw
151: transfer shaft 152: transfer nut
160: first fixing part 170: left and right moving frame
180: Left and right moving mechanism 181: Transfer axis
184: transfer nut 185 protruding cam
186: Home cam 200: Device moving cable
210: first cable movement guide tube 220: first transfer roller
240: first movement amount measuring unit 260: first cable reel
300: discharge liquid supply cable 302: discharge liquid transfer pipe
310: Cable Bear 312: Camera
313: Camera head 314: Connection frame
316: nozzle 317: lighting
318: Monitor 319: Alignment baseline
330: Second cable movement guide tube 340: Second transfer roller
350: Second movement amount measuring unit 360: Second cable reel
400: Discharge liquid circulation unit 410: First storage tank
420: 2nd storage tank 430: 1st pipe
440: Sedimentation tank 450: First filter
460: Second pipe 470: Discharge liquid storage tank
480: 2nd filter 490: 3rd pipe

Claims (8)

An electrode on which electrical discharge processing of the heat transfer tube is performed by causing a spark discharge between the heat transfer tube and the heat transfer tube of the steam generator;
A device base that is inserted into the heat pipe and moves back and forth, has the electrode mounted on a tip, and is capable of moving the electrode back and forth, left and right, and rotationally;
A device table moving cable connected to the device table,
A first transfer roller installed outside the heat pipe to move the device base moving cable back and forth,
A discharge liquid supply cable that supplies discharge liquid between the electrode and the heat transfer tube while transporting the discharge liquid inside and discharging the discharge liquid from the tip,
It includes a second transfer roller installed outside the heat pipe to move the discharge liquid supply cable back and forth,
The device stand is,
A rotation support frame to which the device moving cable is connected on one side,
A rotation drive motor installed on the rotation support frame,
A forward and backward movement support frame rotated by the rotation drive motor,
A forward and backward drive motor installed on one side of the forward and backward movement support frame,
A left and right movable support frame that moves back and forth with the forward and backward drive motor,
a transfer screw that moves the left and right movable support frame back and forth using the driving force of the forward and backward drive motor;
A left and right movable frame installed to be movable left and right on one side of the left and right movable support frame and on which the electrode is mounted,
A left and right driving motor installed on the left and right moving support frame,
An electric discharge machining system for a heat pipe of a steam generator including a left and right moving mechanism that moves the left and right moving frame left and right with the left and right driving motor. delete An electrode on which electrical discharge processing of the heat transfer tube is performed by causing a spark discharge between the heat transfer tube and the heat transfer tube of the steam generator;
A device base that is inserted into the heat pipe and moves back and forth, has the electrode mounted on a tip, and is capable of moving the electrode back and forth, left and right, and rotationally;
A device table moving cable connected to the device table,
A first transfer roller installed outside the heat pipe to move the device base moving cable back and forth,
A discharge liquid supply cable that supplies discharge liquid between the electrode and the heat transfer tube while transporting the discharge liquid inside and discharging the discharge liquid from the tip,
a second transfer roller installed outside the heat pipe to move the discharge liquid supply cable back and forth;
a nozzle for spraying discharge liquid transported through the discharge liquid supply cable;
A camera that photographs the inside of the heat pipe,
An electrical discharge processing system for a heat transfer tube of a steam generator including a cable bear on which the discharge liquid supply cable is loaded and inserted and moved inside the heat transfer tube. In claim 3,
An electrical discharge processing system for a heat transfer tube of a steam generator further comprising a discharge liquid circulation unit that purifies the discharge liquid discharged from the heat transfer tube and supplies it to the discharge liquid supply cable. In claim 1,
An electrical discharge processing system for a heat transfer tube of a steam generator further comprising a discharge liquid circulation unit that purifies the discharge liquid discharged from the heat transfer tube and supplies it to the discharge liquid supply cable. In claim 5,
The discharge liquid circulation unit,
a first storage tank that accommodates the discharge liquid discharged from one side of the heat pipe;
a second storage tank that accommodates the discharge liquid discharged from the other side of the heat transfer tube;
A first pipe through which the discharge liquid contained in the first and second storage tanks is transferred,
a settling tank that accommodates the discharge liquid transported through the first pipe;
A first filter that purifies the discharge liquid transported through the first pipe,
a second pipe through which the discharge liquid contained in the settling tank is transported;
A discharge liquid storage tank that accommodates the discharge liquid transferred to the second pipe,
a second filter that purifies the discharge liquid transported through the second pipe;
An electrical discharge processing system for a heat transfer tube of a steam generator including a third pipe connecting the discharge liquid storage tank and the discharge liquid supply cable. As the rear part of the electrode, which has an arched front part and a "-(one)" shaped rear part, is mounted on the front end of the device base, the device base is connected to one straight pipe part of the "U" shaped heat pipe of the steam generator. An electrode insertion step of inserting the electrode into the interior and placing the rear end of the electrode at the end point of one straight pipe portion of the heat transfer pipe;
A discharge liquid supply preparation step of inserting a discharge liquid supply cable with a camera installed at the distal end into the interior through the other end of the heat transfer tube and placing the distal end of the discharge liquid supply cable opposite the electrode;
An electrode direction alignment step of checking whether the electrode is oriented correctly through the electrode image captured through the camera, and then rotating the electrode using the device base to place it in the positive direction if it is not oriented correctly;
A processing preparation step of tightly fixing one side of the device table to the inner tube wall of the heat transfer pipe to prevent rotation or forward and backward movement of the electrode;
A steam generator comprising a discharge machining step in which the heat transfer tube is cut by discharge machining to form a window in the heat transfer tube as the device table moves the electrode back and forth, left and right, and rotational while discharging the discharge liquid to the tip of the discharge liquid supply cable. Method of cutting the curved part of a heat transfer tube of a steam generator using an electric discharge machining system for heat transfer tubes. In claim 7,
In the electrode direction alignment step,
A first line horizontally displayed on the electrode is photographed through the camera,
The image captured by the camera is displayed on a monitor, and a second line is displayed horizontally on the monitor to guide the positive direction of the electrode,
The user checks whether the first line and the second line are parallel and then rotates the electrodes using a device base so that they are parallel to each other when they are not parallel. A method of cutting a curved pipe of a heat transfer pipe of a steam generator using an electrical discharge machining system for a heat transfer pipe of a steam generator.