Leakage checking and leaking stoppage method

Abstract

The invention discloses a leakage checking and stopping method which is applied to a smelting reduction furnace and belongs to the technical field of water cooling wall leakage point searching and repairing. The leakage checking and leaking stoppage method comprises the steps that S1, the water loss of the water cooling wall system is calculated through the liquid level difference and temperature of the water supplementing tank; s2, calculating the Pearson correlation coefficient of the backwater flow value and the water loss of each water cooling panel, and judging whether a leakage point exists or not; s3, a water inlet branch and a water return branch of the water cooling panel with the leakage point are connected with a water inlet bypass pipeline and a water return bypass pipeline correspondingly, and corresponding valves are arranged; s4, temporary cooling water is introduced into a bypass water inlet pipeline, and a water inlet branch and a water return branch are closed; s5, a visual probe extends into the cooling pipeline, and a positioning leakage point is searched along the cooling pipeline; and S6, positioning a leakage point, and repairing the leakage point after damping down. The technical problem that the leakage detection of the water-cooling system of the smelting reduction furnace is not sensitive enough in the current leakage detection and leakage stoppage method is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of leak point detection and repair of water walls, and particularly to a method for leak detection and plugging. Background Art

[0002] The water cooling system of a smelting reduction furnace is a structure that protects the furnace shell of the smelting reduction furnace from being damaged by slag, flame, high-temperature gas erosion and thermal radiation. It includes a water wall and a makeup water tank. The water wall of the smelting reduction furnace is arranged in layers along the inner part of the furnace wall from the position of the hearth refractories upwards until the top gas chamber of the smelting reduction furnace and the connection part between the furnace body and the flue. Each layer of the water wall is composed of multiple water cooling panels, and each water cooling panel is provided with an independent inlet and return water pipeline and a water cooling panel pipeline, supported by the furnace shell. The supply water and the return water both pass through the furnace shell and are respectively connected to the water supply main pipe and the return water main pipe of the water wall.

[0003] During the operation of the smelting reduction furnace, the temperature inside the furnace is as high as 1600 degrees Celsius. As the high-temperature slag iron and corrosive gases generated during smelting erode the surface of the water wall, leak points are generated due to under-scale corrosion or pitting corrosion. In addition, the friction of particles such as pulverized coal on the water wall will also generate leak points due to wear, resulting in water leakage points in the middle and late stages of production smelting. The cooling circulating water enters the furnace through the leak points, seriously affecting the furnace condition control. Therefore, the leak points must be quickly and accurately detected.

[0004] In the current leak detection methods, flow meters are usually installed at both the inlet pipeline and the return pipeline to monitor the inlet water flow and the return water flow, and whether there is leakage is judged by the difference between the inlet water flow and the return water flow. However, there are errors in the measurement process of the flow meters. The base number of the water inflow of the water wall of the smelting reduction furnace is large, which can be as high as 6500 tons per hour, and the water inflow of a single water cooling panel is also about 60 t / h. When a leak point occurs, the water loss is less than 1 t / h. The water loss is relatively small compared to the water inflow, and the detection errors of the double flow meters will cover the water loss, resulting in the inability to quickly detect leakage. When the water loss reaches the level that can be detected by the flow meter, the leakage has occurred for some time and the leaked cooling medium has had a great impact on production. Therefore, the current leak detection and plugging methods have the technical problem of insufficient sensitivity in detecting the leakage of the water cooling system of the smelting reduction furnace. Summary of the Invention

[0005] The main object of the present invention is to provide a method for leak detection and plugging, which is applied to the water cooling system of a smelting reduction furnace, aiming to solve the technical problem that the current leak detection and plugging methods have insufficient sensitivity in detecting the leakage of the water cooling system of the smelting reduction furnace.

[0006] To achieve the above object, the method for detecting and plugging leaks proposed by the present invention is applied to the water-cooling system of a smelting reduction furnace. It is characterized in that the water-cooling system of the smelting reduction furnace includes a water-cooled wall and a make-up water tank. The water-cooled wall is composed of multiple water-cooling panels, and each water-cooling panel has independent inlet and return water branches and cooling pipes. A flow meter is arranged in the return water branch to record the return water volume. The make-up water tank is connected to the inlet and return water mains of the water-cooled wall respectively. The method includes: S1. Monitor the liquid level of the make-up water tank in real time, obtain the liquid level difference within a predetermined time period, and after eliminating abnormal liquid level difference data, calculate the water loss of the water-cooled wall system according to the temperature of the make-up water tank; S2. When the water loss of the water-cooled wall is greater than a preset value, retrieve multiple groups of return water flow values of each water-cooling panel within a predetermined time period, calculate the Pearson correlation coefficient between the return water flow value of each water-cooling panel and the water loss within this time period. If there is a water-cooling panel with a Pearson correlation coefficient < -0.9, it is determined that there is a leak point in this water-cooling panel; S3. Connect the inlet and return water branches of the water-cooling panel with the leak point to the inlet bypass pipeline and the return water bypass pipeline respectively, and set corresponding valves; S4. After the bypass inlet water pipeline is connected to the temporary cooling water, shut down the inlet and return water branches; S5. Reduce the water inflow of the inlet bypass pipeline, insert a visual probe from the inlet bypass pipeline or the return water bypass pipeline, and the visual probe travels along the cooling pipe to search for and locate the leak point; S6. After locating the leak point, adjust the furnace condition of the smelting reduction furnace to carry out a blast outage, and repair the leak point after the blast outage.

[0007] Optionally, in an embodiment of the present invention, the cooling medium in the make-up water tank is demineralized water. In step S1, to adapt to the change of the density of the cooling medium due to temperature, the calculation method of the water loss is:

[0008] where Q is the water loss, in t / h; is the liquid level of the make-up water tank n seconds ago, is the current liquid level of the make-up water tank, in %; n is the time, in s, and the value range of n is 30s - 60s; V is the effective volume within the measurement range of the make-up water tank liquid level gauge, in ; T is the circulating water temperature of the water-cooled wall system, in °C.

[0009] Optionally, in an embodiment of the present invention, in step S6, the furnace condition in the smelting reduction furnace is adjusted such that the binary basicity of the slag is 1.15 - 1.20, the tapping temperature of the forehearth is 1420 - 1440 °C, and the carbon content of the hot metal is 3.8% - 4.2%, and then the blast is stopped to adjust the furnace environment and avoid furnace shutdown. The blast stoppage under this furnace condition can form a repair time of 10 - 12 h.

[0010] Optionally, in an embodiment of the present invention, in step S5, the bypass water inlet flow rate is 90% - 95% of the original water inlet flow rate value of the water-cooled panel, and then the water inlet flow rate value is gradually reduced at a rate of 1 - 5 t / h per minute, while reducing the water inlet volume and ensuring that the return water temperature is within the range of 50 °C - 80 °C.

[0011] Optionally, in an embodiment of the present invention, when abnormal water loss data is excluded in step S1, negative liquid level difference data is excluded, and this data is abnormal water loss data formed due to water replenishment in the makeup water tank.

[0012] Optionally, in an embodiment of the present invention, the cooling pipes of the water-cooled panel are in a serpentine structure, and the cooling pipe structures of each water-cooled panel are the same. The leak point is found by turning the probe along the inside of the serpentine pipeline, and the specific position of the leak point is located by the number of turns and the length of the probe wire extending into the pipeline.

[0013] Optionally, in an embodiment of the present invention, in step S3, valves are respectively arranged on the inlet and return water branches and the inlet and return water bypass pipelines to control the opening and closing of the inlet and return water branches and the inlet and return water bypass pipelines.

[0014] Optionally, in an embodiment of the present invention, step S6 includes: S61. After adjusting the furnace condition of the smelting reduction furnace to meet the blast stoppage condition, organize the blast stoppage; S62. With the leak point as the center, cut and open the furnace shell of the smelting reduction furnace to form a first inspection hole; S63. Close the inlet and return water branches and the inlet and return water bypass pipelines. If the leak point is on the side close to the furnace shell, plug the leak through the first inspection hole. If the leak point is on the side away from the furnace shell, cut the water-cooled wall pipe to form a second inspection hole, and plug the leak through the second inspection hole; S64. Repair the inspection hole.

[0015] Optionally, in an embodiment of the present invention, in step S63, the width of the second inspection hole is d, and the diameter of the cooling pipe is l, d = ( )l.

[0016] Optionally, in one embodiment of the present invention, in step S63, if the water leakage point is located on the side away from the furnace shell, an arc-shaped spare pipe is cut, the diameter of the arc-shaped spare pipe is the same as the cooling pipe or 1-5 mm smaller than the cooling pipe, and it is welded to the inner wall of the water-cooling pipe at the leakage point along the outer seam of the spare pipe.

[0017] Compared with the prior art, the present invention can at least achieve the following beneficial effects.

[0018] Currently, one existing method involves installing flow meters on both the inlet and return lines of each water-cooled panel. The difference in flow rates between the two lines is used to determine if a leak has occurred. However, flow meters can produce errors when measuring flow rates, and the fluctuation range of these errors can mask the amount of water loss. The water flow rate in a water-cooled panel is approximately 60 t / h, while typical water loss is less than 1 t / h. The combined fluctuations of the errors in the two flow meters can mask the amount of water loss at the leak point, causing a leak to go undetected. The dual flow meter method can only detect a leak when the water loss exceeds the fluctuation range. Furthermore, because the two flow meters measure different temperatures for the media, and because the detection environment differs in addition to temperature, these factors further contribute to the errors, reducing the sensitivity of the dual flow meter method for leak detection.

[0019] In this solution, the water loss of the water-cooled wall system is first calculated by monitoring the liquid level difference in the water supply tank. After eliminating abnormal data, when the water loss exceeds the threshold, the system retrieves the return water volume of each water-cooled panel within a predetermined time period and uses the Pearson correlation coefficient to determine the strength of the correlation between the water loss and return water volume. If the Pearson correlation coefficient between the water loss and return water volume is less than -0.9, indicating a strong correlation between the two, the water loss is determined to be caused by a leak in the water-cooled panel.

[0020] After determining which water-cooling panel is leaking, a bypass line is set up to temporarily cool the water-cooling panel, and a visual probe is inserted into the bypass line to find and locate the leak point.

[0021] After the leakage point is determined, the furnace condition of the smelting reduction furnace is adjusted to shut down the furnace, and the leakage point is repaired after the shutdown.

[0022] Compared to existing solutions, this solution reduces the need for flow meters and has a simpler structure. It also quickly detects leaks in the cooling system after they occur, reducing the impact of leaks on product quality and improving production safety. By calculating correlations, it can avoid misjudgments of leak points, improve the accuracy of leak detection, and prevent unnecessary production cuts or even shutdowns caused by misjudgments. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0024] Figure 1 It is a flowchart of an embodiment of the method for detecting and plugging leaks in the present invention; Figure 2 It is a schematic diagram of the pipeline of the water-cooling system of the smelting reduction furnace in the present invention; Figure 3 It is a schematic diagram of the structure after the water-cooling panel is connected with the bypass pipeline in the present invention.

[0025] Explanation of the reference numerals in the drawings: 100, make-up water tank; 200, water-cooling panel; 210, inlet branch; 220, return water branch; 230, inlet bypass pipeline; 240, return water bypass pipeline; 250, cooling pipeline; 300, flowmeter; The realization, functional features and advantages of the object of the present invention will be further described in conjunction with the embodiments with reference to the accompanying drawings. Specific embodiments

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0027] It should be noted that all directional indications (such as up, down, left, right, front, back...) in the embodiments of the present invention are only used to explain the relative position relationship and movement conditions between components in a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0028] In the present invention, unless otherwise clearly defined and limited, terms such as "connection" and "fixation" should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two components or the interaction relationship between two components, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0029] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the meaning of "and / or" appearing throughout the text includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme in which A and B are satisfied at the same time. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0030] The smelting temperature in a smelting reduction furnace can reach as high as 1600°C. If a leak develops in the water-cooled wall, the cooling medium leaking into the high-temperature furnace chamber will instantly vaporize, increasing the pressure inside the furnace and, in severe cases, causing an explosion and equipment damage. This can also affect heat transfer from the upper combustion zone to the lower molten pool, leading to uncontrolled process conditions. Therefore, when a leak occurs, it is necessary to quickly detect, locate, and repair it.

[0031] It should be noted that the “inlet and return water” used in the text should be understood as inlet water and return water. For example, the inlet and return water branches refer to the inlet branch and the return water branch.

[0032] Reference Figures 1 to 3 The present invention provides a leak detection and plugging method, which is applied to a smelting reduction furnace.

[0033] The smelting reduction furnace features a water-cooled wall as a cooling structure. The wall is composed of multiple water-cooled panels 200, each with an independent water inlet branch 210 and return branch 220. Each return branch is equipped with a flowmeter 300, which records and monitors the return water volume of each water-cooled panel. Each water-cooled panel has independent inlet and return branches, which connect to the water-cooled wall's main inlet and return lines. A water makeup tank 100 is connected to each of these lines, providing both water supply to the entire water-cooled wall and receiving return water from the wall.

[0034] Monitor the liquid level in the make-up water tank. By monitoring the liquid level difference in the make-up water tank within a predetermined time period, determine whether there is a leakage in the water-cooled wall. In an ideal situation, when the water inlet and return water in the water-cooled wall form a stable circulation, the water output and return water in the make-up water tank are equal. Without a leakage point, there will be no liquid level difference in the make-up water tank within the predetermined time period. If there is a leakage point in the water-cooled wall and part of the cooling medium leaks outside the water-cooled wall during the circulation process, it will cause the water output in the make-up water tank to be greater than the return water, forming a liquid level difference.

[0035] At the same time, under actual operating conditions, due to high temperature, the water output and inlet water in the make-up water tank may be different due to evaporation. Therefore, when a liquid level difference is detected in the make-up water tank, it means that there is water loss in the water-cooling system. The reason for the water loss may be leakage or evaporation. Therefore, further judgment is required.

[0036] Since the water loss due to evaporation is small, to accurately determine whether the water loss phenomenon is caused by leakage, a threshold value is set. When the water loss exceeds the threshold value, retrieve multiple groups (preferably 10 groups or more) of return water volumes of each water-cooled panel within a predetermined time period, and calculate the Pearson correlation coefficient between the return water volume and the water loss. If the correlation coefficient value between the return water volume and the water loss of a certain water-cooled panel < -0.9, there is a strong correlation between the two, indicating that the water loss of this water-cooled panel is caused by leakage and there is a leakage point in this water-cooled panel. If the correlation coefficient between the two is not within the above range, the reason for the water loss may be evaporation or other reasons.

[0037] The threshold value of the water loss here needs to be determined according to the basic water inlet volume. In addition, it is also possible to choose to calculate the correlation coefficient immediately after the water loss occurs, and exclude the reason for the evaporation water loss through the calculation of the correlation coefficient, which is not limited here.

[0038] In addition, when calculating the Pearson correlation coefficient, in addition to the above method, another optional method is proposed: During the stable circulation process, the return water flow rate remains within a relatively stable numerical range. When there is a leakage point, the return water volume of the problematic water-cooled panel is lower than that of the normal water-cooled panel. Therefore, when calculating the correlation coefficient, the data of the water-cooled panel with a lower return water volume can be preferentially retrieved for calculation to determine whether there is a leakage point in this water-cooled panel. Whether there is a leakage point in this water-cooled panel or not, after the calculation is completed, then retrieve the return water volume data of all other water-cooled panels for correlation calculation to complete the comprehensive detection.

[0039] That is, the first method is to directly screen and judge all water-cooled panels, and the second method is to first judge the suspected water-cooled panel and then screen and judge other water-cooled panels.

[0040] After determining which water-cooled panel has a leak point, it is necessary to further locate the position of the leak point on the water-cooled panel. The water-cooled panel is located on the inner wall of the smelting reduction furnace, and the leak point cannot be directly observed. Therefore, a visual device needs to be used to enter the pipeline to find the leak point. It is difficult to control the visual device to enter the accurate water-cooled panel branch through the main pipeline. After entering, the movement path of the visual device is also long, and the leak point cannot be quickly located. At the same time, it affects the water replenishment pressure of the entire water-cooled wall system and the cooling effect of other water-cooled panels.

[0041] In addition, in order to avoid affecting production due to finding the leak point, during the process of discovering and finding the leak point, the smelting reduction furnace is in a normal working state. Therefore, in order to avoid overheating and deformation, the water-cooled panel with the leak point still needs to circulate the cooling medium. For this purpose, an inlet bypass pipeline 230 is respectively provided to connect with the inlet branch, and a return water bypass pipeline 240 is provided to connect with the return water branch. The visual probe is extended through the return water bypass pipeline or the inlet bypass pipeline to find and locate the leak point. Preferably, the visual probe enters through the return water bypass pipeline to reduce the influence of the visual probe on the inlet water.

[0042] To reduce the influence of the flowing cooling medium on the clarity of the picture transmitted back by the probe, before extending the visual probe, the water inflow of the inlet bypass pipeline is reduced. In addition, when the leak point is located, preparations are made to repair the leak point. Before repair, the smelting reduction furnace needs to be adjusted to a state where repair can be carried out. First, the furnace condition of the smelting reduction furnace is adjusted to meet the condition of blowing-off and blowing-off is carried out. After blowing-off, the leak point is repaired. It should be noted that in the blowing-off state, the air supply of the smelting reduction furnace is suspended, the temperature in the furnace is higher than 1300 °C, and the molten iron in the connecting channel between the pre-furnace and the furnace body will not solidify. There is no need to stop the furnace to discharge iron, and production can be quickly restored after air supply.

[0043] In addition, in step S1, when eliminating abnormal water loss data, in addition to leakage causing a liquid level difference, the automatic water replenishment function of the water replenishing tank will also cause a liquid level difference. The liquid level difference data generated by automatic water replenishment is abnormal liquid level difference data and needs to be eliminated. Different from the liquid level difference caused by leakage, the liquid level difference measured during automatic water replenishment is negative, that is, the liquid level at the nth second is higher than the liquid level n seconds ago. Eliminating the abnormal water loss data improves the accuracy of leak detection.

[0044] In the prior art, in addition to using the method of double flow meters, there is also a method of using a pressure gauge to judge whether there is a leak in the water-cooled pipeline. Although the accuracy of the pressure gauge method is improved compared with the double flow meter method, the valve of the detection section pipeline needs to be closed. In an environment where the smelting reduction reaches 1600 °C, there is a problem of water cut and burnout of the water-cooled panel, and the inspection volume is large and the time consumption is long. Therefore, the current double flow meter method and pressure gauge method cannot meet the requirements of quickly discovering and quickly locating the leak point.

[0045] In summary, compared with the existing solutions, the present solution proposes a leak detection and plugging method that does not require furnace shutdown, can quickly and accurately determine whether there are leaks in the water wall, and quickly locate the leak points, solving the technical problems of poor sensitivity and long detection time of the current leak detection and plugging methods for the leakage detection of the molten reduction furnace water cooling system.

[0046] Further, in one embodiment, the cooling medium in the water cooling system is demineralized water. Demineralized water removes dissolved salts such as calcium, magnesium, and chloride ions through processes such as ion exchange and reverse osmosis, avoiding the formation of scale by these ions at high temperatures, thereby reducing the effective flow diameter of the pipeline; in addition, chloride ions are the main inducement for metal corrosion. After removing chloride ions, the corrosion rate of the pipeline can be reduced; finally, in a high-temperature and high-pressure working environment, demineralized water is not easily decomposed to generate oxygen, which can slow down the oxidation of the pipeline.

[0047] However, at different temperatures, the density of demineralized water will change accordingly. The temperature of the cooling medium in the makeup water tank is usually in the range of 25°C - 50°C, and the temperature in the makeup water tank is in a dynamically changing state. Therefore, in order to accurately measure the water loss in the makeup water tank, the water loss in the makeup water tank is calculated according to the following formula.

[0048]

[0049] Where Q is the water loss, with the unit of t / h; is the makeup water tank liquid level n seconds ago, is the current makeup water tank liquid level, with the unit of %; n is the time, with the unit of s, and the value range of n is 30s - 60s; V is the effective volume within the measurement range of the makeup water tank liquid level gauge, with the unit of ; T is the circulating water temperature of the water wall system, with the unit of °C.

[0050] Among them, is the liquid level difference. Through unit conversion, the liquid level difference within a predetermined time period is converted to the liquid level difference within one hour, and combined with density and volume, the water loss per hour is calculated.

[0051] The density values of demineralized water at different temperatures satisfy , where T is the temperature in the makeup water tank during the liquid level detection period. The water loss in the makeup water tank at different temperatures is accurately measured through the aforementioned formula.

[0052] Optionally, the liquid level in the make-up water tank can be measured by an ultrasonic liquid level gauge, and the temperature can be measured by a thermometer. It is achievable for those skilled in the art to obtain the liquid level and temperature of the make-up water tank. An electromagnetic flowmeter can be selected in the return water branch to detect the amount of return water.

[0053] Furthermore, since the smelting reduction furnace is in normal operation during the process of performing steps S1 - S5, to avoid deformation and damage of the water-cooled panel caused by high temperature, during the process of leak point location, it is still necessary to ensure that a sufficient amount of cooling medium circulates in the problematic water-cooled panel.

[0054] Refer to Figure 3 , openings are made on the inlet and return water branches of the problematic water-cooled panel by means of pressure tapping. The inlet water branch 210 is connected to the inlet bypass pipeline 230, and the return water branch 220 is connected to the return water bypass pipeline 240. Valves are respectively arranged on the inlet and return water branches and the inlet and return water bypass pipelines. Among them, the inlet water branch valve is installed before the connection between the inlet water branch and the inlet bypass pipeline, and the return water branch valve is installed after the connection between the return water branch and the return water bypass pipeline; the inlet bypass valve is installed before the connection between the inlet water branch and the inlet bypass pipeline, and the return water bypass valve is installed after the connection between the return water pipeline and the return water bypass pipeline. The opening and closing of the inlet and return water branches and the inlet and return water bypass pipelines of the problematic water-cooled panel are controlled by the valves.

[0055] Specifically, the valve can be selected from one or more of globe valves, gate valves, ball valves and regulating valves, which is not limited herein as long as it can meet the entry of the visual probe and the control of pipeline opening and closing.

[0056] After the inlet and return water bypass pipelines and valves are set up, first introduce the cooling medium into the inlet bypass pipeline to form a cooling cycle for the inlet and return water bypass branches. Specifically, the cooling medium in the inlet bypass pipeline is the same as that in the original inlet water branch. After the cooling medium is introduced into the inlet bypass pipeline, the original inlet and return water branches are closed by the valves, and the inlet and return water bypass pipelines replace the inlet and return water branches, without shutting off the water supply to the inlet and return water main pipelines.

[0057] As mentioned above, in order to reduce the adverse impact of the flowing cooling medium on the visual probe to find the leak point, it is necessary to reduce the water inflow of the inlet bypass pipeline. However, the reduction of the water inflow needs to be carried out under certain conditions.

[0058] First, reduce the water inlet flow rate to 90%-95% of the original value, and then reduce the water inlet flow rate at a rate of 1-5 t / h at intervals of one minute. During the process of reducing the water inlet, it is necessary to always ensure that the return water temperature remains within the range of 50°C-80°C to avoid deformation of the water-cooled panel due to temperature stress caused by too low temperature or poor cooling effect due to too high temperature. It should be noted that during the process of leak point detection, in order to reduce interference, the water inlet flow rate can continue to decrease, but it is necessary to ensure that the return water temperature is within the range of 50°C-80°C. Of course, if the water inlet flow rate does not have a great adverse impact on the leak point detection, it can also be maintained at a certain value after the water inlet flow rate drops to a certain value.

[0059] Different from the blast furnace, the temperature in the hearth of the smelting reduction furnace is higher, so higher cooling requirements are put forward for its water-cooling system. For this reason, the structure of the cooling pipe 250 of the water-cooled panel of the smelting reduction furnace is usually a serpentine pipe to have a larger heat dissipation area.

[0060] After inserting the visual probe, the probe needs to travel inside the serpentine pipe. Since the turning action of the visual probe is very obvious, after the visual probe discovers a leak point, the position of the leak point can be quickly located through the number of turns of the visual probe and the length of the probe wire inserted into the pipe. In addition, scales can be marked on the probe wire to facilitate reading the length of the wire inserted.

[0061] After completing the leak point positioning, adjust the furnace condition to adjust the furnace condition of the smelting reduction furnace to a state where the leak point can be repaired.

[0062] In a preferred embodiment, when adjusting the furnace condition, control the binary basicity of the slag to be 1.15-1.20, the tapping temperature of the forehearth to be 1420-1440°C, and the carbon content of the hot metal to be 3.8%-4.2%, and then stop the blast. The three together ensure the physical and chemical stability of the slag and iron in the furnace during the blast stoppage. Among them, the basicity and tapping temperature promote the separation of slag and iron, improve the effect of the molten pool gushing spring, strengthen the slag coating protection of the water-cooled wall, and create conditions for stopping the cooling water of the leaky water-cooled panel to weld and repair the leak point. The carbon content and tapping temperature of the hot metal ensure that the carbon content in the hot metal is moderate, inhibit the oxidation of the hot metal, extend the temperature of the hot metal dropping to the solidification point without affecting the leak point welding repair. In addition, when restoring the blast, improve the stirring and splashing effect of the molten pool and accelerate the restoration of the furnace condition.

[0063] When the blast stoppage is completed under the above conditions, about 10-12 hours of repair time can be provided for leak point repair, and this time is sufficient to complete the leak point repair. This method solves the problem that the leak point of the water-cooled panel can only be repaired by shutting down the furnace under the condition that the intermittent maintenance time is limited during the production process of the smelting reduction process by adjusting the furnace condition before the blast stoppage.

[0064] Due to the serpentine structure of the cooling pipes, the pipe-through repair method and the copper cooling rod repair method currently used in blast furnaces cannot be applied.

[0065] Since the temperature inside the furnace hearth is still relatively high after the blast furnace is shut down, there is molten liquid slag and iron, and it is impossible to enter the furnace for leak repair. Therefore, an out-of-furnace leak repair method is proposed. Since there is no need to enter the furnace, the out-of-furnace repair is safer than the in-furnace repair and does not require shutting down the furnace. And in order to facilitate daily inspection, inspection scaffolds will be erected around the smelting reduction furnace. Therefore, the operator can approach the outside of the leak through the inspection scaffold and operate on the inspection scaffold, with a shorter processing time.

[0066] After the blast furnace is shut down, locate the out-of-furnace position of the leak point, and cut the furnace shell centered on the leak point to form a first inspection hole, so that the problematic water-cooled panel is exposed.

[0067] There are two situations for the leak point of the water-cooled panel. One is that the leak point is located on the side of the water-cooled pipe close to the furnace shell, that is, the leak point will be exposed after the first inspection hole is opened. At this time, directly weld and repair the leak point. After the repair is completed, repair the first inspection hole.

[0068] The other is that the leak point is located on the side of the water-cooled pipe away from the furnace shell. Since this side is closer to the furnace hearth, the phenomena of soot corrosion and particle erosion are more serious, so this situation accounts for a higher proportion. In this case, first cut the furnace shell to form a first inspection hole in the same way. However, after the first inspection hole is opened, the leak point is still not exposed, and it is necessary to cut the water-cooled pipe to form a second inspection hole. After the second inspection hole is opened, the leak point is exposed, and the leak point is repaired through the second inspection hole. After the repair is completed, repair the two inspection holes.

[0069] Furthermore, in the second case, according to the state of the leak point and the surrounding pipe wall, cut a section of arc-shaped pipe from the spare pipe material and weld the arc-shaped pipe to the water leakage point to repair the water leakage point. Specifically, the diameter of the spare pipe material is the same as that of the cooling pipe, or 1-5 mm smaller than the diameter of the cooling pipe. Select the spare pipe material under the foregoing conditions so that the repaired pipe material can better fit the inner wall of the cooling pipe.

[0070] Furthermore, when opening the second inspection hole, the width of the second inspection hole is d, and the diameter of the cooling pipe is l, d = ( )l. This inspection hole width can ensure that the edge of the second inspection hole is close to the maintenance personnel, and there is enough operating space at the edge to complete the repair of the second inspection hole with a welding torch. For the sake of understanding, when d = l, the edge of the second inspection hole is perpendicular to the horizontal line of sight direction of the maintenance personnel, and the cooling pipe is a serpentine pipe. At this time, there may be pipes above and below the edge of the second inspection hole, and the space is small, which is not convenient for opening the second inspection hole and repairing the second inspection hole.

[0071] In summary, the leak detection and plugging method proposed by the present invention can at least bring the following beneficial effects: Ⅰ. During the process of finding and repairing the leak point, there is no need to stop the furnace. After the leak point repair is completed, the air supply can be restored to quickly resume production, reducing the impact on the output. Ⅱ. Only one flow meter needs to be set in each return water branch, with a simpler structure and lower cost. Ⅲ. The leakage can be detected faster, with higher accuracy and the leak point can be quickly located. Ⅳ. It is safer to repair the leak point outside the furnace.

[0072] The above are only optional embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structural transformation made by using the description and drawings of the present invention under the inventive concept of the present invention, or any direct / indirect application in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A method for detecting and plugging leaks, applied to the water cooling system of a smelting reduction furnace, characterized in that, The water cooling system of the smelting reduction furnace includes a water-cooled wall and a water supply tank. The water-cooled wall is composed of multiple water-cooled panels. Each water-cooled panel has independent water inlet and return branches and cooling pipes. A flow meter is installed in the return branch to record the return water volume. The water supply tank is connected to the water inlet and return main lines of the water-cooled wall respectively. The method includes: S1. Real-time monitoring of the liquid level in the water supply tank, obtaining the liquid level difference within a predetermined time period, eliminating abnormal liquid level difference data, and calculating the water loss of the water-cooled wall system based on the water supply tank temperature; S2. When the water loss of the water-cooled wall is greater than a preset value, multiple sets of return water flow values of each water-cooled panel within a predetermined time period are retrieved, and the Pearson correlation coefficient between the return water flow value and the water loss of each water-cooled panel within the time period is calculated. If the Pearson correlation coefficient of any water-cooled panel is less than -0.9, it is determined that the water-cooled panel has a leak. S3. Connect the water inlet branch and return water branch of the water-cooling panel with the leak to the water inlet bypass pipe and return water bypass pipe respectively, and install corresponding valves; S4. After the bypass water inlet pipe is connected to temporary cooling water, the water inlet branch and the return water branch are shut down; S5. Reduce the water flow into the water inlet bypass pipe, insert a visual probe into the water inlet bypass pipe or the return water bypass pipe, and move the visual probe along the cooling pipe to locate the leak; S6. After locating the leak point, adjust the furnace condition of the molten reduction furnace to shut down the air, and then repair the leak point after shutting down the air.

2. The method for detecting and plugging leaks according to claim 1, characterized in that, The cooling medium in the water supply tank is desalted water. In step S1, in order to adapt to the change in cooling medium density due to temperature, the water loss is calculated as follows: Where Q is the water loss, unit is t / h; is the liquid level of the make-up water tank n seconds ago, is the current liquid level of the make-up water tank, in %. n is time, the unit is s, and the value range of n is 30s-60s; V is the effective volume within the measuring range of the make-up water tank level gauge, with the unit of ; T is the circulating water temperature of the water-cooled wall system, in °C.

3. The method for detecting and plugging leaks according to claim 1, characterized in that In step S6, the furnace conditions in the molten reduction furnace are adjusted to a slag binary basicity of 1.15-1.20, a pre-furnace iron tapping temperature of 1420-1440°C, and a molten iron carbon content of 3.8%-4.2%, and then the furnace is shut down to adjust the furnace environment and avoid shutdown. This furnace shutdown can result in a repair time of 10-12 hours.

4. The method for detecting and plugging leaks according to claim 1, characterized in that, In step S5, the bypass water inlet flow rate is 90%-95% of the original water inlet flow rate of the water-cooled panel, and then the water inlet flow rate is gradually reduced at a rate of 1-5 t / h per minute, reducing the water inlet volume while ensuring that the return water temperature is within the range of 50°C-80°C.

5. The method for detecting and plugging leaks as claimed in claim 1, wherein When eliminating abnormal water loss data in step S1, negative liquid level difference data is eliminated. This data is abnormal water loss data caused by water replenishment in the water replenishment tank.

6. The method for detecting and plugging leaks according to claim 1, characterized in that, The cooling pipes of the water-cooled panel are serpentine in structure. The cooling pipe structure of each water-cooled panel is the same. The probe is turned to search for leaks along the inside of the serpentine pipe. The specific location of the leak is determined by the number of turns and the length of the probe wire inserted into the pipe.

7. The method for detecting and plugging leaks as claimed in claim 1, characterized in that, In step S3, valves are respectively provided on the water inlet and return branches and the water inlet and return bypass pipelines to control the opening and closing of the water inlet and return branches and the water inlet and return bypass pipelines.

8. The method for detecting and plugging leaks according to claim 3, characterized in that Step S6 includes: S61. After adjusting the furnace conditions of the smelting reduction furnace to meet the wind-off conditions, organize the wind-off operation; S62, cutting and opening a hole in the shell of the smelting reduction furnace with the leak point as the center to form a first inspection hole; S63. Close the inlet and return water branch lines and the inlet and return water bypass pipelines. If the leakage point is on the side close to the furnace shell, plug the leak through the first inspection hole. If the leakage point is on the side away from the furnace shell, cut the water-cooled wall pipe to form a second inspection hole, and plug the leak through the second inspection hole. S64. Repair the inspection hole.

9. The method for detecting and plugging leaks according to claim 8, characterized in that, In step S63, the width of the second inspection hole is d, and the diameter of the cooling pipe is l, where d = ( ) l.

10. The leak detection and plugging method according to claim 8, characterized in that In step S63, if the leakage point is on the side away from the furnace shell, intercept an arc-shaped spare pipe. The diameter of the arc-shaped spare pipe is the same as or 1-5 mm smaller than that of the cooling pipe. Weld it to the inner wall of the water-cooled pipe at the leakage point along the outer edge seam of the spare pipe.

Images