Method for detecting water leakage in water-cooled structures in metal melting and refining furnaces

Abstract

This invention provides a method for detecting water leakage in water-cooled structures in metal melting and refining furnaces, which reduces the risk of malfunction or failure of moisture detection sensors. [Solution] A method for detecting water leakage from a water-cooled structure 10 in a metal melting and refining furnace 1 equipped with a water-cooled structure 10, wherein the metal melting and refining furnace 1 has a refractory material 11 positioned below the water-cooled structure 10 and an iron shell 12 positioned outside the refractory material 11, the iron shell 12 is provided with a through hole 120 positioned at the height of the refractory material 11, a moisture detection sensor 3 is connected to the through hole 120 through a pipe 2, the moisture detection sensor 3 is positioned at a distance of 1000 mm or more from the through hole 120 along the pipe 2, and the method includes determining whether or not there is water leakage from the water-cooled structure 10 based on the signal from the moisture detection sensor 3.

Description

Technical Field

[0001] The present invention relates to a method for detecting water leakage from a water-cooled structure in a metal melting and refining furnace equipped with a water-cooled structure.

Background Art

[0002] As a method of this type that has been conventionally used, the method shown in Patent Document 1 below can be cited. Patent Document 1 describes that "when detecting water leakage from a water-cooled structure in a metal melting and refining furnace provided with a water-cooled structure in a part of the furnace such as a furnace wall or a furnace lid, a moisture detection sensor is provided near the water-cooled structure, and water leakage from the water-cooled structure is detected by measuring the water vapor concentration in the ambient gas."

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the conventional method as described above, although a moisture detection sensor is provided near the water-cooled structure, for example, due to the high heat of the iron skin (furnace shell) of the metal melting and refining furnace, high-temperature gas or water vapor discharged from the inside of the iron skin, etc., the moisture detection sensor may be exposed to an atmosphere exceeding its heat-resistant temperature and malfunction or break.

[0005] The present invention has been made to solve the above problems, and one of its purposes is to provide a method for detecting water leakage from a water-cooled structure in a metal melting and refining furnace that can reduce the risk of malfunction or breakage of the moisture detection sensor.

Means for Solving the Problems

[0006] The present invention relates to a method for detecting water leakage from a water-cooled structure in a metal melting and refining furnace. In one embodiment, the method for detecting water leakage from a water-cooled structure in a metal melting and refining furnace equipped with a water-cooled structure comprises a refractory material positioned below the water-cooled structure and an iron shell positioned outside the refractory material, wherein the iron shell is provided with a through-hole positioned at the height of the refractory material, a moisture detection sensor is connected to the through-hole through a pipe, the moisture detection sensor is positioned at a distance of 1000 mm or more from the through-hole along the pipe, and the method includes determining whether or not there is water leakage from the water-cooled structure based on the signal from the moisture detection sensor. [Effects of the Invention]

[0007] According to one embodiment of the present invention's method for detecting water leakage in a water-cooled structure in a metal melting and refining furnace, the moisture detection sensor is connected to the through-hole through piping and positioned at a location at least 1000 mm away from the through-hole along the piping, thereby reducing the risk of the moisture detection sensor malfunctioning or breaking. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram illustrating a metal melting and refining furnace in which a method for detecting water leakage in a water-cooled structure in a metal melting and refining furnace according to Embodiment 1 of the present invention is implemented. [Figure 2] Figure 1 is a plan view of a metal melting and refining furnace. [Figure 3] This is an explanatory diagram showing area III in more detail. [Figure 4] This is an explanatory diagram showing the method of spraying protective gas. [Figure 5] This is a schematic diagram illustrating a metal melting and refining furnace in which a method for detecting water leakage in a water-cooled structure in a metal melting and refining furnace according to Embodiment 2 of the present invention is implemented. [Figure 6]This is a schematic diagram illustrating a metal melting and refining furnace in which a method for detecting water leakage in a water-cooled structure in a metal melting and refining furnace according to Embodiment 3 of the present invention is implemented. [Figure 7] This graph shows the temperature changes inside the piping at various positions from the through-hole in the embodiment. [Figure 8] This graph shows the maximum temperature inside the pipe at each location in Figure 7. [Figure 9] This graph shows the change in the amount of water vapor in the piping during the first 12 hours after the start of startup following repairs to a metal melting and refining furnace. [Figure 10] This graph shows the change in the amount of water vapor in the piping from the start of operation after repairs to a metal melting and refining furnace. [Modes for carrying out the invention]

[0009] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. The present invention is not limited to each embodiment, and can be materialized by modifying the components without departing from the spirit of the invention. Furthermore, various inventions can be formed by appropriately combining the multiple components disclosed in each embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, components from different embodiments may be appropriately combined.

[0010] Embodiment 1. Figure 1 is a schematic diagram illustrating a metal melting and refining furnace 1 in which a water leakage detection method for a water-cooled structure 10 in a metal melting and refining furnace 1 according to Embodiment 1 of the present invention is implemented. Figure 2 is a plan view of the metal melting and refining furnace 1 in Figure 1. Figure 3 is a diagram illustrating area III in Figure 1 in more detail.

[0011] The water leakage detection method according to an embodiment of the present invention is a method for detecting water leakage from a water-cooled structure 10 in a metal melting and refining furnace 1 equipped with a water-cooled structure 10.

[0012] The metal melting and refining furnace 1 is for melting and / or refining a metal 1a such as molten iron or steel. Examples of the metal melting and refining furnace 1 include an electric furnace and a ladle refining furnace. The water-cooled structure 10 is, for example, a water-cooled panel in which a pipe through which cooling water flows is provided inside. The water-cooled structure 10 is provided over the entire circumference of the metal melting and refining furnace 1 at the upper part of the metal melting and refining furnace 1.

[0013] The metal melting and refining furnace 1 has a refractory 11 disposed below the water-cooled structure 10 and an iron skin 12 disposed outside the refractory 11.

[0014] As shown in FIG. 3, the refractory 11 has a plurality of permanent bricks 110, a joint material 111, and wear bricks 112.

[0015] The permanent bricks 110 are made of a refractory material formed into a predetermined shape and are laid or stacked inside the iron skin 12. Examples of the refractory material constituting the permanent bricks 110 include magnesia bricks, MgO bricks, and high-alumina bricks.

[0016] The joint material 111 is made of an amorphous refractory material and is filled between the permanent bricks 110. Examples of the refractory material constituting the joint material 111 include refractory mortar.

[0017] The wear bricks 112 are made of a shaped refractory material and are provided inside the permanent bricks 110. Examples of the refractory material constituting the wear bricks 112 include ASC bricks, magnesia-chrome bricks, carbon bricks, ASC bricks, high-alumina bricks, MgO-C bricks, zircon bricks, alumina-spinel bricks, etc. The joint material 111 is also filled between the wear bricks 112.

[0018] As specifically shown in Figure 1, the steel shell 12 is provided with a through-hole 120 positioned at the same height as the refractory material 11. A moisture detection sensor 3 is connected to the through-hole 120 through a pipe 2. The moisture detection sensor 3 is positioned at a distance of 1000 mm or more from the through-hole 120 along the pipe 2.

[0019] As described above, the refractory material 11 is positioned below the water-cooling structure 10. Therefore, when water leaks from the water-cooling structure 10, water 10a from the water-cooling structure 10 may enter the gap between the steel shell 12 and the refractory material 11, and the gaps within the refractory material 11 (the gaps between the permer bricks 110 and the wear bricks 112, and the gaps between the permer bricks 110). If water 10a enters these gaps, the refractory material 11 may be extinguished, potentially reducing the heat resistance performance of the metal melting and refining furnace 1.

[0020] The water leak detection method according to an embodiment of the present invention includes determining whether or not there is a water leak from the water-cooled structure 10 based on a signal from a moisture detection sensor 3. When a water leak occurs from the water-cooled structure 10, the water 10a from the water-cooled structure 10 evaporates due to the heat of the metal 1a in the metal melting and refining furnace 1, generating water vapor 10b. As the water vapor 10b moves towards the pipe 2 through the through hole 120, the amount of water vapor in the pipe 2 increases. When the amount of water vapor per unit volume (absolute humidity) in the pipe 2 based on the signal from the moisture detection sensor 3 is above a predetermined threshold, it can be determined that there is a water leak from the water-cooled structure 10.

[0021] The moisture detection sensor 3 can measure the relative humidity (%) and temperature (°C) inside the pipe 2. Relative humidity is the ratio of the amount of water vapor contained in the sample to the saturated water vapor amount. When the saturated water vapor amount at temperature t (°C) is a(t), a(t) can be calculated using the following equation (1). a(t)=217×e(t) / (t+273.15)...Equation (1) Here, e(t) is the saturated water vapor pressure (hPa). e(t) can be expressed, for example, by Tetens' equation as follows: e(t) = 6.1078 × 10 7.5t / (t+237.3) The temperature inside pipe 2 at the location of the moisture detection sensor 3 is measured, and the saturated water vapor amount is calculated based on that measurement. From this saturated water vapor amount and relative humidity, the amount of water vapor per unit volume (g / m³) inside pipe 2 is calculated. 3 ) can be obtained. Let a(t) be the saturated water vapor amount, let RH(%) be the relative humidity, and let VH(g / m³) be the amount of water vapor per unit volume. 3 When this is the case, VH can be calculated using the following equation (2). VH={a(t)×RH} / 100...Equation (2)

[0022] In this case, if the moisture detection sensor 3 is placed near the water-cooled structure 10, there is a risk that the moisture detection sensor 3 may malfunction or break due to exposure to an atmosphere exceeding its heat resistance temperature, such as the high heat of the iron shell 12 of the metal melting and refining furnace 1, or high-temperature gases and steam discharged from inside the iron shell 12. As in this embodiment, by placing the moisture detection sensor 3 at a position 1000 mm or more away from the through-hole 120 along the piping 2, the risk of the moisture detection sensor 3 malfunctioning or breaking can be reduced.

[0023] Although not shown in the diagram, a space (gap) is formed between the refractory material 11 (permanent brick 110) and the steel shell 12, connecting to the circumferential and vertical (up and down) directions of the metal melting and refining furnace 1. This is because the permanent brick 110 is made of refractory material molded into a predetermined shape, creating a gap between the inner surface of the steel shell 12 and the outer surface of the permanent brick 110. Regardless of where water leakage occurs in the water-cooled structure 10, the steam 10b can travel through the space between the inner surface of the steel shell 12 and the outer surface of the permanent brick 110 towards the through-hole 120.

[0024] As shown in Figure 2, through holes 120 are provided in the iron shell 12 at multiple positions spaced apart from each other in the circumferential direction of the metal melting and refining furnace 1, and moisture detection sensors 3 are connected to each of these through holes 120 through piping 2.

[0025] The through-hole 120 is provided in the side wall of the metal melting and refining furnace 1. The diameter of the through-hole 120 may be about 10 to 15 mm. Preferably, the through-hole 120 is provided in the upper part of the side wall. This is because the water-cooling structure 10 is located at the top of the metal melting and refining furnace 1, and the through-hole 120 is provided to monitor for water leakage from there.

[0026] In this embodiment, the pipe 2 extends in a straight line. The inner diameter of the pipe 2 is, for example, 40 mm. The pipe 2 may be connected to the through hole 120 by any method. Although not limited thereto, the pipe 2 can be connected to the through hole 120 by welding a tubular connecting member 13 to the outer surface of the steel shell 12 at the location of the through hole 120 and screwing the end of the pipe 2 into the connecting member 13. Either the connecting member 13 or the end of the pipe 2 may be provided with a male thread and the other with a female thread.

[0027] As shown in Figure 1, the moisture detection sensor 3 has a sensing part 30 that detects relative humidity (%) and temperature (°C), and a sensor body 31 connected to the sensing part 30. The sensor body 31 can transmit the measured values ​​of relative humidity and temperature to a control device (not shown) via wireless communication. The control device then uses the transmitted relative humidity and temperature to calculate the amount of water vapor per unit volume (g / m³) based on the aforementioned equation (2). 3 ) is calculated. An example of such a moisture detection sensor 3 is the "RTR507B" manufactured by T&D Corporation. The sensing part 30 is located inside the pipe 2, and the sensor body 31 is located outside the pipe 2. The rear end 2a of the pipe 2, away from the metal shell 12, is open, and the sensing part 30 is connected to the sensor body 31 by a wire through this opening. The distance from the through hole 120 to the moisture detection sensor 3 is the distance inside the pipe between the outer surface position of the metal shell 12 at the location of the through hole 120 and the sensing part 30. Hereafter, the notation "moisture detection sensor 3" mainly refers to the sensing part 30 of the moisture detection sensor 3.

[0028] The distance from the through-hole 120 to the moisture detection sensor 3 is preferably 1300 mm or more, and more preferably 1500 mm or more. Setting the distance from the through-hole 120 to the moisture detection sensor 3 to these values ​​can more reliably reduce the risk of the moisture detection sensor 3 malfunctioning or breaking (e.g., burning out). From the viewpoint of water vapor diffusion, there is no particular upper limit for the distance from the through-hole 120 to the moisture detection sensor 3, but from the viewpoint of water vapor movement, an upper limit of 5000 mm can be given.

[0029] <Regarding the injection of purge gas 4> The water leak detection method according to an embodiment of the present invention further includes blowing purge gas 4 into the piping 2 during the operation of the metal melting and refining furnace 1 or during startup after repair, and determining that there is a water leak from the water-cooled structure 10 when the amount of water vapor in the piping 2 based on the signal from the moisture detection sensor 3 exceeds a threshold after stopping the blowing of purge gas 4 into the piping 2.

[0030] <Regarding the injection of purge gas 4: In operation> During the operation of the metal melting and refining furnace 1, the amount of water vapor in the piping 2 may increase due to condensation, even if there is no water leakage from the water-cooling structure 10. As described above, by blowing purge gas 4 into the piping 2 and drying the inside of the piping 2, the effects of condensation can be eliminated, and the misjudgment of whether or not there is water leakage from the water-cooling structure 10 can be reduced.

[0031] During the operation of the metal melting and refining furnace 1, if the amount of water vapor detected by the moisture detection sensor 3 exceeds a threshold, it is not necessary to immediately determine that water leakage has occurred from the water-cooled structure 10. Instead, purge gas 4 may be injected for a predetermined period of time. For example, purge gas 4 may be injected for a predetermined charge operation, such as 3 charges (approximately 3 hours). After the injection of purge gas 4 is stopped, if the amount of water vapor is still above the threshold, it may be determined that water leakage has occurred from the water-cooled structure 10. This prevents false detections due to the effects of condensation. Alternatively, the injection and stopping of purge gas 4 may be repeated multiple times (for example, 2 or 3 times), and it may be determined that water leakage has occurred from the water-cooled structure 10 only when the amount of water vapor exceeds the threshold multiple times.

[0032] <Regarding the injection of purge gas 4: During startup after repairs> The wear bricks 112, jointing material 111, and perma bricks 110 are melted away by the metal 1a in the metal melting and refining furnace 1. For this reason, the metal melting and refining furnace 1 is repaired as needed. Repairs to the metal melting and refining furnace 1 include, for example, replacing the melted perma bricks 110, filling the gaps between the perma bricks 110 caused by the melting with jointing material 111, and forming new wear bricks 112 on the surface of the perma bricks 110.

[0033] During the startup of the metal melting and refining furnace 1 after repairs, the amount of water vapor in the piping 2 may increase due to moisture originating from the refractory material 11 used in the repairs, even if there is no water leakage from the water-cooling structure 10. By blowing purge gas 4 into the piping 2 during the startup of the metal melting and refining furnace 1 after repairs and drying the inside of the piping 2, the influence of moisture originating from the repaired refractory material 11 can be eliminated, and the misjudgment of whether or not there is water leakage from the water-cooling structure 10 can be reduced.

[0034] When the start-up of the metal melting and refining furnace 1 after repairs begins, the injection of purge gas 4 can be started. After a predetermined period of time, such as 3 to 6 days, the injection of purge gas 4 can be stopped. During the period in which the injection of purge gas 4 is expected to be performed, the injection of purge gas 4 may be temporarily stopped, and if it is confirmed that the amount of water vapor is below a threshold, the injection of purge gas 4 may be stopped. On the other hand, if the amount of water vapor is above the threshold when the injection of purge gas 4 is temporarily stopped, the injection of purge gas 4 may be restarted. After the period in which the injection of purge gas 4 is expected to be performed has elapsed, the injection and stopping of purge gas 4 will be carried out as described above, during the operation of the metal melting and refining furnace 1.

[0035] As shown in Figure 1, the piping 2 is provided with a first inlet 21 for blowing in purge gas 4. The first inlet 21 is located closer to the through-hole 120 (upstream) than the moisture detection sensor 3. The first inlet 21 may be sealed when no purge gas 4 is being blown in. The purge gas 4 from the first inlet 21 passes over the moisture detection sensor 3 and is discharged outside the piping 2 from the rear end 2a of the piping 2.

[0036] For the purge gas 4, for example, compressed air can be used. Alternatively, for the purge gas 4, an inert gas such as nitrogen or carbon dioxide can be used. The pressure of the purge gas 4 can be set arbitrarily, but may be set to, for example, 1 kPa or higher. Although not shown in the figures, a common control valve may be connected to the first inlet 21 of multiple pipes 2 arranged spaced apart in the circumferential direction of the metal melting and refining furnace 1, and the injection of purge gas 4 from each first inlet 21 may be centrally controlled by opening and closing the control valve.

[0037] <Regarding the application of protective gas 5> The water leak detection method according to an embodiment of the present invention further includes blowing protective gas 5 onto a moisture detection sensor 3 when blowing purge gas 4 into the piping 2 during the startup of the metal melting and refining furnace 1 after repair. During the startup of the metal melting and refining furnace 1 after repair, organic gas is generated from the combustion of organic components contained in the refractory material 11 (especially the joint material 111). This organic gas, mainly generated from the joint material 111 during the startup after repair, increases the risk of damage to the moisture detection sensor 3. By blowing protective gas 5 onto the moisture detection sensor 3 during the startup of the metal melting and refining furnace 1 after repair, the contact of organic gas with the moisture detection sensor 3 (sensing portion 30) can be reduced, thereby reducing the risk of damage to the moisture detection sensor 3 due to organic gas. From the viewpoint of suppressing damage to the moisture detection sensor 3 due to organic gas, it is preferable to continue blowing purge gas 4 and blowing protective gas 5 for a period of about 72 hours from the start of the startup of the metal melting and refining furnace 1 after repair.

[0038] As shown in Figure 1, the piping 2 is provided with a second inlet 22 for blowing protective gas 5. The second inlet 22 is located closer to the moisture detection sensor 3 than the first inlet 21. The second inlet 22 is located at or near the moisture detection sensor 3. When the second inlet 22 is located near the moisture detection sensor 3, it is located closer to the through-hole 120 (upstream position) than the moisture detection sensor 3. When the distance between the second inlet 22 and the moisture detection sensor 3 is 10 mm or less, it can be understood that the second inlet 22 is located near the moisture detection sensor 3. The distance between the second inlet 22 and the moisture detection sensor 3 is defined as the shortest distance between the second inlet 22 and the moisture detection sensor 3. The second inlet 22 may be sealed when protective gas 5 cannot be blown. The protective gas 5 from the second inlet 22 is discharged out of the piping 2 from the rear end 2a of the piping 2 together with the purge gas 4.

[0039] As the protective gas 5, the same as the purge gas 4, for example, compressed air can be used. Alternatively, as the protective gas 5, an inert gas such as nitrogen or carbon dioxide can be used. The pressure of the protective gas 5 can be set arbitrarily, but it may be set to a pressure that does not cause backflow, for example, 0.7 kPa or higher. Although not shown in the figures, a common control valve may be connected to the second inlet 22 of multiple pipes 2 arranged spaced apart in the circumferential direction of the metal melting and refining furnace 1, and the blowing of protective gas 5 from each second inlet 22 may be centrally controlled by opening and closing the control valve.

[0040] Here, with further reference to Figure 4, the manner in which the protective gas 5 is sprayed onto the moisture detection sensor 3 will be explained in more detail.

[0041] Figure 4 is an explanatory diagram showing the manner in which the protective gas 5 is sprayed. As shown in Figure 4, the protective gas 5 may be sprayed directly and perpendicularly onto the moisture detection sensor 3. This spraying method can be achieved by providing a second inlet 22 extending radially from the piping 2 at the location of the moisture detection sensor 3.

[0042] It is preferable to inject purge gas 4 into piping 2 and protective gas 5 onto moisture detection sensor 3 for 3 days from the start of startup after repair of metal melting and refining furnace 1. This minimizes the risk of damage to moisture detection sensor 3 by organic gases and allows for early determination of whether or not there is a water leak. After 3 days have passed since the start of startup after repair of metal melting and refining furnace 1, the influence of organic gases from refractory material 11 is expected to decrease.

[0043] <Regarding temperature measurement of iron shell 12> The water leak detection method according to an embodiment of the present invention further includes measuring the temperature of the steel shell 12 near the through hole 120, and determines that there is a water leak from the water-cooled structure 10 when the amount of water vapor in the piping 2 based on the signal from the moisture detection sensor 3 is above a threshold and the amount of temperature decrease of the steel shell 12 within a predetermined period is above a predetermined amount. When a water leak occurs from the water-cooled structure 10, the temperature of the steel shell 12 decreases due to the latent heat of vaporization of water. By taking into account not only the amount of water vapor in the piping 2 based on the signal from the moisture detection sensor 3, but also whether or not there is a temperature decrease of the steel shell 12, the accuracy of determining whether or not there is a water leak from the water-cooled structure 10 can be improved.

[0044] Regarding the temperature measurement of the steel shell 12, the range of 1000 mm from the through hole 120 may be understood as the vicinity of the through hole 120. The temperature measurement of the steel shell 12 may be performed by any sensor, for example, by a thermocouple provided on the outer surface of the steel shell 12. When the amount of water vapor in the piping 2 based on the signal from the moisture detection sensor 3 is above a threshold, the recent temperature change trend of the steel shell 12 may be checked. In this case, for example, if the temperature of the steel shell 12 has dropped by 100°C in 12 hours, it may be determined that there is water leakage from the water-cooled structure 10.

[0045] <Regarding the measurement of relative humidity by the second moisture detection sensor 6> The water leakage detection method according to an embodiment of the present invention further includes measuring the relative humidity in the surrounding atmosphere of the metal melting and refining furnace 1 using a second moisture detection sensor 6. When the difference between the amount of water vapor calculated from the relative humidity inside the piping 2 measured by the moisture detection sensor 3 and the amount of water vapor calculated from the relative humidity in the surrounding atmosphere measured by the second moisture detection sensor 6 is greater than or equal to a threshold value, it is determined that there is water leakage from the water-cooled structure 10. By adopting such a configuration, the influence of water vapor in the surrounding atmosphere can be eliminated, and the accuracy of determining whether or not there is water leakage from the water-cooled structure 10 can be improved.

[0046] The second moisture detection sensor 6 is positioned in a location that is highly representative of the ambient environment. The second moisture detection sensor 6 is positioned in a location that is not affected by high temperatures such as molten steel or waste slag. The second moisture detection sensor 6 may be positioned near a specific moisture detection sensor 3, or near each of the moisture detection sensors 3. It may be determined that there is water leakage from the water-cooled structure 10 when the difference between the amount of water vapor calculated from the relative humidity inside the pipe 2 measured by the moisture detection sensor 3 and the amount of water vapor calculated from the relative humidity in the surrounding atmosphere measured by the second moisture detection sensor 6 is greater than or equal to a threshold, and the amount of temperature decrease of the steel shell 12 within a predetermined period is greater than or equal to a predetermined amount.

[0047] Embodiment 2. Figure 5 is a schematic diagram illustrating a metal melting and refining furnace 1 in which a water leakage detection method for a water-cooled structure 10 in a metal melting and refining furnace 1 according to Embodiment 2 of the present invention is implemented. In Embodiment 1, the piping 2 was described as extending in a straight line. However, the shape of the piping 2 may be changed.

[0048] For example, as shown in Figure 5, the pipe 2 may have a bent shape. The illustrated pipe 2 has a descending section 200 that extends from a height position of the through hole 120 to a lower position, and a downstream section 201 that extends horizontally from the lower end of the descending section 200.

[0049] The piping 2 further has a lead-out section 202 connected to the through-hole 120. The lead-out section 202 extends horizontally from the height of the through-hole 120. The descending section 200 is connected to the tip of the lead-out section 202. A first inlet 21 for blowing in purge gas 4 is provided at the upper end of the descending section 200. The descending section 200 penetrates the operating floor 8, and the downstream section 201 is located below the operating floor 8.

[0050] A drain port 201a is provided at the lower end of the downstream section 201. Condensed water 10c inside the pipe 2 can be discharged through the drain port 201a. The drain port 201a is sealed when measuring relative humidity and when blowing in purge gas 4.

[0051] The moisture detection sensor 3 is located in the downstream section 201. This reduces the risk of condensation water 10c accumulating at the location of the moisture detection sensor 3. The other configurations are the same as in Embodiment 1.

[0052] Embodiment 3. Figure 6 is a schematic diagram illustrating a metal melting and refining furnace 1 in which a water leakage detection method for a water-cooled structure 10 in a metal melting and refining furnace 1 according to Embodiment 3 of the present invention is implemented. In Embodiment 2, the downstream section 201 extends horizontally from the lower end of the descending section 200. However, as shown in Figure 6, the downstream section 201 may be raised from the lower end of the descending section 200. This makes it possible to more reliably collect the condensation water 10c of the downstream section 201 into the drain port 201a, and further reduces the risk of condensation water 10c accumulating at the position of the moisture detection sensor 3. The downstream section 201 is inclined at, for example, 0 to 5° with respect to the horizontal. The other configurations are the same as in Embodiments 1 and 2.

[0053] Although preferred embodiments of the present invention have been described in detail above with reference to the attached drawings, the present invention is not limited to these examples. It is clear to any person with ordinary skill in the art to which the present invention belongs that various modifications or alterations can be conceived within the scope of the technical idea described in the claims, and these are also understood to fall within the technical scope of the present invention.

[0054] For example, in Embodiments 1 to 3, the moisture detection sensor 3 is described as outputting the relative humidity inside the pipe 2, but the moisture detection sensor 3 may also output the amount of water vapor inside the pipe 2. Also, in Embodiments 1 to 3, the pipe 2 is described as being a straight or bent pipe, but a flexible pipe with flexibility may be used as the pipe 2. Furthermore, in Embodiments 1 to 3, the purge gas 4 and protective gas 5 are described as being blown into the pipe 2 when the metal melting and refining furnace 1 is started up after repairs, but for example, the moisture detection sensor 3 may be removed when the metal melting and refining furnace 1 is started up after repairs, and the blowing of purge gas 4 and protective gas 5 may be omitted. Even with such a method, damage to the moisture detection sensor 3 by organic gas can be avoided. [Examples]

[0055] The present invention will be described more specifically below with reference to examples. The present invention is not limited to these examples.

[0056] The inventors connected a flexible pipe 2 to a metal melting and refining furnace 1 and installed thermocouples inside the pipe 2 at positions of 300 mm, 1300 mm, and 3000 mm from the through hole 120. They then investigated the temperature changes at each position while the metal melting and refining furnace 1 was in operation.

[0057] Figure 7 shows a graph illustrating the temperature change inside the pipe 2 at various positions from the through-hole 120 in the embodiment, and Figure 8 shows a graph illustrating the maximum temperature inside the pipe 2 at each position in Figure 7. As shown in Figures 7 and 8, it was found that the temperature inside the pipe 2 tends to decrease as the distance from the through-hole 120 increases. It was also found that by moving the pipe 2 more than 1000 mm away from the through-hole 120, the temperature inside the pipe 2 falls below 100°C, which is the heat resistance temperature of the moisture detection sensor 3. In fact, when the moisture detection sensor 3 was placed 1000 mm from the through-hole 120, no burnout or malfunction of the moisture detection sensor 3 occurred during the operation of the metal melting and refining furnace 1.

[0058] Next, the inventors investigated the change in the amount of water vapor in the piping 2 during the startup of the metal melting and refining furnace 1 after repair. Figure 9 is a graph showing the change in the amount of water vapor in the piping 2 from the start of startup of the metal melting and refining furnace 1 after repair to 12 hours. Figure 9(a) shows the change in the amount of water vapor when purge gas 4 is blown into the piping 2 at a pressure of 3 kPa and protective gas 5 is blown onto the moisture detection sensor 3 at a pressure of 0.5 kPa. Figure 9(b) shows the change in the amount of water vapor when neither purge gas 4 nor protective gas 5 is blown.

[0059] As shown in Figure 9(b), when neither the purge gas 4 nor the protective gas 5 was injected, the amount of water vapor in the piping 2 remained at a high value. Specifically, the threshold amount of water vapor (40 g / m³) used to determine that there was water leakage from the water-cooled structure 10 was low. 3 A condition exceeding ) was observed. This was presumed to be due to moisture originating from the refractory material 11 used for repair, and there were concerns that if this condition continued, condensation water 10c would accumulate inside the pipe 2. Therefore, when purge gas 4 was blown into the pipe 2, it was confirmed that the amount of water vapor could be kept low, as shown in Figure 9(a), and the concern of condensation water 10c accumulating inside the pipe 2 could be reduced.

[0060] Next, Figure 10 is a graph showing the change in the amount of water vapor in piping 2 from the start of operation after repairs to metal melting and refining furnace 1. Although the ranges of the vertical and horizontal axes of Figure 10 are different from those of Figure 9, it shows the change in (a) of Figure 9 and the subsequent change. During period I (approximately 2 days), from the start of operation after repairs to metal melting and refining furnace 1 at 12:00 on February 7th to 9:00 on February 9th, purge gas 4 was injected into piping 2 at a pressure of 3 kPa, and protective gas 5 was injected onto the moisture detection sensor 3 at a pressure of 0.5 kPa. As a result, the amount of water vapor was kept low during period I.

[0061] During period II, from 9:00 on February 9th to 16:00 on February 13th, when the injection of purge gas 4 and protective gas 5 was stopped, it was confirmed that the amount of water vapor increased, and then gradually decreased.

[0062] During Period III, from 16:00 on February 13th to 16:00 on February 16th, the injection of purge gas 4 and protective gas 5 at low pressure was resumed. Specifically, purge gas 4 was injected into piping 2 at a pressure of 0.3 to 1.0 kPa, and protective gas 5 was injected onto moisture detection sensor 3 at a pressure of 0.2 to 0.1 kPa. As a result, the amount of water vapor was kept low during Period III.

[0063] During period IV, starting at 16:00 on February 16th, when the injection of purge gas 4 and protective gas 5 was stopped, it was confirmed that although there were occasional slightly elevated values, the water vapor levels remained generally low.

[0064] Figure 10 shows the change in water vapor content, confirming that during the six days from February 7th to 13th, an increase in water vapor content was observed due to moisture originating from the refractory material 11 used for repairs. Therefore, from the perspective of more reliably preventing condensation caused by this increase in water vapor content, it is advisable to inject purge gas 4 and spray protective gas 5 for six days from the start of the startup of the metal melting and refining furnace 1 after repairs.

[0065] On the other hand, even on February 10th, three days after the start of startup of the metal melting and refining furnace 1, the amount of water vapor was still below the threshold, and it was considered that injecting purge gas 4 and spraying protective gas 5 for three days from the start of startup after repairs to the metal melting and refining furnace 1 would be sufficient. However, since it is not possible to determine whether or not there is water leakage from the water-cooled structure 10 while injecting purge gas 4, etc., it is preferable to inject purge gas 4, etc. for three days from the viewpoint of starting to determine whether or not there is water leakage as early as possible.

[0066] The invention described herein may also be described as follows: [1] A method for detecting water leakage from a water-cooled structure in a metal melting and refining furnace equipped with a water-cooled structure, The metal melting and refining furnace has a refractory material positioned below the water-cooled structure and an iron shell positioned outside the refractory material. The steel shell is provided with a through-hole positioned at the height of the refractory material, and a moisture detection sensor is connected to the through-hole through a pipe, and the moisture detection sensor is positioned at a distance of 1000 mm or more from the through-hole along the pipe. This includes determining whether or not there is water leakage from the water-cooled structure based on the signal from the moisture detection sensor, A method for detecting water leakage in water-cooled structures in metal melting and refining furnaces. [2] The method further includes blowing purge gas into the piping during operation of the metal melting and refining furnace or during startup after repairs, After stopping the injection of the purge gas into the piping, if the amount of water vapor in the piping, based on the signal from the moisture detection sensor, exceeds a threshold, it is determined that there is a water leak from the water-cooled structure. A method for detecting water leakage in a water-cooled structure in a metal melting and refining furnace as described in paragraph 1. [3] When the purge gas is blown into the piping during the startup of the metal melting and refining furnace after repair, the method further includes blowing a protective gas onto the moisture detection sensor. A method for detecting water leakage in a water-cooled structure in a metal melting and refining furnace as described in paragraph 2. [4] The piping has a descending section that extends from a height position of the through-hole toward a lower position, and a downstream section that rises or extends horizontally from the lower end of the descending section. A drainage port is provided at the lower end of the downstream section. A method for detecting water leakage in a water-cooled structure in a metal melting and refining furnace as described in any one of items 1 to 3. [5] The moisture detection sensor is provided in the downstream section. A method for detecting water leakage in a water-cooled structure in a metal melting and refining furnace as described in paragraph 4. [6] The method further includes measuring the temperature of the metal shell near the through hole, When the amount of water vapor in the piping, based on the signal from the moisture detection sensor, is above a threshold, and the amount of temperature decrease of the steel shell within a predetermined period is above a predetermined amount, it is determined that there is water leakage from the water-cooled structure. A method for detecting water leakage in a water-cooled structure in a metal melting and refining furnace as described in any one of items 1 to 5. [7] The method further includes measuring the relative humidity in the surrounding atmosphere of the metal melting and refining furnace using a second moisture detection sensor. When the difference between the amount of water vapor calculated from the relative humidity inside the piping measured by the moisture detection sensor and the amount of water vapor calculated from the relative humidity in the surrounding atmosphere measured by the second moisture detection sensor is greater than or equal to a threshold value, it is determined that there is water leakage from the water-cooled structure. A method for detecting water leakage in a water-cooled structure in a metal melting and refining furnace as described in any one of items 1 to 6. [Explanation of Symbols]

[0067] 1: Metal melting and refining furnaces 1a: Metal 10:Water cooling structure 10a: Water 10b: Water vapor 11: Refractory 12: Iron skin 120: Through hole 2: Piping 200: Descent section 201: Downstream 201a: Drain port 3: Moisture detection sensor 4: Purge gas 5: Protective gas 6: Second moisture detection sensor

Claims

1. A method for detecting water leakage from a water-cooled structure in a metal melting and refining furnace equipped with a water-cooled structure, The metal melting and refining furnace has a refractory material positioned below the water-cooled structure and an iron shell positioned outside the refractory material. The steel shell is provided with a through-hole positioned at the height of the refractory material, and a moisture detection sensor is connected to the through-hole through a pipe, and the moisture detection sensor is positioned at a distance of 1000 mm or more from the through-hole along the pipe. This includes determining whether or not there is water leakage from the water-cooled structure based on the signal from the moisture detection sensor, A method for detecting water leakage in water-cooled structures in metal melting and refining furnaces.

2. The method further includes blowing purge gas into the piping during operation of the metal melting and refining furnace or during startup after repairs, After stopping the injection of the purge gas into the piping, if the amount of water vapor in the piping, based on the signal from the moisture detection sensor, exceeds a threshold, it is determined that there is a water leak from the water-cooled structure. A method for detecting water leakage in a water-cooled structure in a metal melting and refining furnace as described in claim 1.

3. When the purge gas is blown into the piping during the startup of the metal melting and refining furnace after repair, the method further includes blowing a protective gas onto the moisture detection sensor. A method for detecting water leakage in a water-cooled structure in a metal melting and refining furnace according to claim 2.

4. The piping has a descending section that extends from a height position of the through-hole toward a lower position, and a downstream section that rises or extends horizontally from the lower end of the descending section. A drainage port is provided at the lower end of the downstream section. A method for detecting water leakage in a water-cooled structure in a metal melting and refining furnace according to any one of claims 1 to 3.

5. The moisture detection sensor is provided in the downstream section. A method for detecting water leakage in a water-cooled structure in a metal melting and refining furnace according to claim 4.

6. The method further includes measuring the temperature of the metal shell near the through hole, When the amount of water vapor in the piping, based on the signal from the moisture detection sensor, is above a threshold, and the amount of temperature decrease of the steel shell within a predetermined period is above a predetermined amount, it is determined that there is water leakage from the water-cooled structure. A method for detecting water leakage in a water-cooled structure in a metal melting and refining furnace according to any one of claims 1 to 3.

7. The method further includes measuring the relative humidity in the surrounding atmosphere of the metal melting and refining furnace using a second moisture detection sensor. When the difference between the amount of water vapor calculated from the relative humidity inside the piping measured by the moisture detection sensor and the amount of water vapor calculated from the relative humidity in the surrounding atmosphere measured by the second moisture detection sensor is greater than or equal to a threshold value, it is determined that there is water leakage from the water-cooled structure. A method for detecting water leakage in a water-cooled structure in a metal melting and refining furnace according to any one of claims 1 to 3.

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