Vacuum induction furnace cooling system safety protection method

Abstract

The present application belongs to the technical field of metallurgical equipment safety control, and particularly relates to a safety protection method for a vacuum induction furnace cooling system. In view of the problem that the prior art only relies on water outlet pressure for protection, and there is a risk of false positives and false negatives, the present application installs flow meters on the water inlet main pipe and the water outlet main pipe of the cooling water system, and monitors the water inlet flow Qin and the water outlet flow Qout in real time. At the same time, branch flow meters are installed at the water outlets of the five cooling branches of the furnace body, the induction coil, the ladle, the furnace cover and the furnace door, and the water outlet flow of each branch is monitored. The control system calculates the flow difference AQ and the flow deviation degree di of each branch, and compares them with the preset threshold value, which can quickly locate the specific fault branch and develop a differentiated protection strategy, and can identify whether it is a gradual blockage or a sudden burst, significantly improving the sensitivity and accuracy of the vacuum induction furnace cooling system fault detection, and ensuring the safety of the equipment and production.

Description

Technical Field

[0001] This invention relates to the field of metallurgical equipment technology, specifically to a safety protection method for a vacuum induction furnace cooling system, particularly for the safety monitoring and protection technology of cooling systems for vacuum induction furnaces (especially medium and large-sized ones with a capacity of 200 kg or more). Background Technology

[0002] Vacuum induction furnaces are crucial equipment for smelting special alloys and high-temperature alloys. Key components such as the furnace body, coils, ladle, and furnace cover endure extreme temperatures during the smelting process, relying entirely on an internal circulating cooling water system for cooling. Failure of the cooling water system (such as insufficient flow, pipe blockage, or rupture) can cause critical components (especially the induction coil) to burn out within tens of seconds, resulting in significant economic losses and safety hazards.

[0003] Currently, the industry commonly uses a protection measure of installing a pressure sensor or pressure switch at the cooling water outlet. The protection logic is as follows: when the outlet pressure is lower than a set value, it is determined that there is a cooling water system malfunction, and the power supply is then cut off.

[0004] However, relying solely on outlet water pressure protection has obvious drawbacks: 1. Indirectness: Pressure is an indirect reflection of flow rate. When cooling pipes are partially blocked but not completely blocked due to scale or foreign objects, the flow rate has dropped significantly, but the pressure may not change much. The system cannot detect this, resulting in "missed detection" and the hidden danger persists.

[0005] 2. False alarm risk: Pressure fluctuations in the water supply network may cause changes in the outlet water pressure, triggering unnecessary shutdowns and resulting in "false alarms".

[0006] 3. Unable to locate: Abnormal pressure only indicates that there is a problem with the system, but it cannot determine whether it is a water pump failure, valve malfunction, pipeline leak or partial blockage.

[0007] 4. Response lag: For sudden pipeline ruptures, the response speed of pressure drop is not as direct as that of flow.

[0008] Therefore, existing technologies suffer from insufficient reliability and low level of intelligence, and there is an urgent need for a more direct and precise protection solution. Summary of the Invention

[0009] This invention aims to overcome the shortcomings of existing technologies and provide a safety protection method for a vacuum induction furnace cooling system. Addressing the problem that existing technologies rely solely on outlet water pressure for protection, which carries the risk of false alarms and missed alarms, this invention installs flow meters on the inlet and outlet main pipes of the cooling water system to monitor the inlet flow rate Qin and outlet flow rate Qout in real time. Simultaneously, branch flow meters are installed at the outlets of five cooling branches: the furnace body, induction coil, ladle, furnace cover, and furnace door, to monitor the outlet flow rate of each branch. The control system calculates the flow difference ΔQ and the flow deviation δi of each branch and compares them with preset thresholds. This allows for rapid location of the specific faulty branch and the development of differentiated protection strategies. Furthermore, it can distinguish between gradual blockage and sudden rupture, significantly improving the sensitivity and accuracy of fault detection in the vacuum induction furnace cooling system and ensuring equipment and production safety.

[0010] The technical problem to be solved by the present invention is achieved by the following technical solution: a safety protection method for a vacuum induction furnace cooling system, based on a safety protection device for a vacuum induction furnace cooling system, the safety protection device for a vacuum induction furnace cooling system includes a first flow meter installed on the main inlet water pipe, a second flow meter installed on the main return water pipe, a third flow meter installed at the outlet of the furnace body cooling branch, a fourth flow meter installed at the outlet of the induction coil cooling branch, a fifth flow meter installed at the outlet of the ladle cooling branch, a sixth flow meter installed at the outlet of the furnace cover cooling branch, a seventh flow meter installed at the outlet of the furnace door cooling branch, and a control unit; The two ends of the furnace body cooling branch, induction coil cooling branch, ladle cooling branch, furnace cover cooling branch, and furnace door cooling branch are respectively connected to the main water inlet pipe and the main water return pipe. The control unit is connected to the first flow meter, the second flow meter, the third flow meter, the fourth flow meter, the fifth flow meter, the sixth flow meter, and the seventh flow meter; The safety protection method for the cooling system of a vacuum induction furnace includes the following steps: S1. The control unit collects the inlet water flow rate Qin, outlet water flow rate Qout, and outlet water flow rates Q3, Q4, Q5, Q6, and Q7 of the cooling system in real time through the first flow meter, second flow meter, third flow meter, fourth flow meter, fifth flow meter, sixth flow meter, and seventh flow meter. S2. Calculate the real-time flow difference ΔQ=|Qin-Qout| or the flow change rate, and calculate the flow deviation of each branch δi=|Qi-Qibase| / Qibase, where i is 3, 4, 5, 6, 7, and Qibase is the flow baseline value of the corresponding branch. S3. Compare ΔQ with the preset alarm threshold Qa and protection threshold Qs, and compare the branch deviation δi with the preset deviation threshold δth, where Qa <Qs; If ΔQ>Qa and δi<δth, a level one warning is triggered, an audible and visual alarm is issued, and the message "Cooling system flow is abnormal, please check" is displayed on the human-machine interface. If ΔQ > Qs or δi > δth, secondary protection is triggered, and abnormal branch information is highlighted on the human-machine interface. Different response strategies are formulated based on the abnormal branch. (1) If the abnormal branch is an induction coil, the risk of coil overheating is the highest, so the main power supply should be cut off immediately; (2) If the abnormal branch is the furnace body or ladle, reduce the smelting power to 50% first, observe the changes in ΔQ and δi, and cut off the power if it does not recover within the preset time. (3) If the abnormal branch is the furnace cover or furnace door and the heat load is low, an audible and visual alarm will be issued and the system will continue to operate. Repairs will be arranged within 30 minutes. If ΔQ < Qa and δi < δth, and the average value of the outflow rate Qout decreases by more than 5 L / min / cycle for three consecutive sampling cycles, it is determined to be progressive filter clogging, triggering a maintenance warning of "Filter clogging risk, check within 30 hours" without shutting down the machine, and the touch screen displays a yellow warning message. Under normal operating conditions, the valve is in the open state and the pump power is constant. If ΔQ < Qa and δi < δth, it indicates that there is no blockage or leakage. When the flow rate of each branch decreases for three consecutive sampling cycles, it is determined that the pump performance has deteriorated. If the outflow rate Qout drops suddenly, and the decrease in outflow rate per unit time exceeds the preset threshold, the smelting power supply will be immediately cut off.

[0011] In this invention, the flow rate change rate refers to the change in flow rate per unit time (e.g., 1 second). The flow deviation δi of each branch reflects the degree of deviation between the actual outflow rate of that branch and the normal reference value. When a branch is blocked, the outflow rate of that branch will decrease significantly, causing δi to increase; when a branch leaks, the outflow rate of that branch may increase or decrease, which will also cause δi to be abnormal. By setting a deviation threshold δth (e.g., 30%), when δi exceeds this threshold, the abnormality of that branch can be determined. Combined with the abnormality of the main pipe ΔQ, the fault type can be further confirmed: if ΔQ increases and only a branch's δi exceeds the standard, it is determined that the branch is blocked or leaking; if ΔQ is normal but a branch's δi exceeds the standard, it may be a flow meter malfunction or a local problem in the branch.

[0012] When the outflow rate drops by more than 50% in a very short time (e.g., within 1 second), it is determined to be a sudden pipe rupture, immediately triggering an emergency shutdown without waiting for ΔQ calculation. This judgment is independent of the ΔQ threshold and is used to improve the response speed to sudden failures.

[0013] Preferably, in step S2 of this invention, it is further calculated whether the inlet water flow rate Qin is lower than the minimum required flow rate Qmin. If so, the control unit directly triggers the protection logic, triggering a "insufficient inlet water flow" warning and starting a delay timer. If Qin does not recover after the delay, the smelting power supply is immediately cut off. This protection logic is independent of ΔQ and δi and is used to deal with the overall failure of the water supply system.

[0014] Preferably, the protection threshold Qs of this invention is dynamically adjusted according to different melting stages of the vacuum induction furnace: Qs is set to 30 L / min for the preheating stage, 15 L / min for the melting / refining stage, and 25 L / min for the casting stage. The protection threshold can be flexibly set according to the furnace model and smelting process stage, demonstrating a high degree of intelligence.

[0015] Preferably, the first flow meter and the second flow meter are one of an electromagnetic flow meter, an ultrasonic flow meter, or a turbine flow meter.

[0016] Preferably, the control unit of this invention further includes a human-machine interface for real-time display of inlet water flow, outlet water flow, flow difference, alarm information, and historical data. The abnormal branch is displayed intuitively on the human-machine interface, guiding maintenance personnel to conduct targeted inspections and avoiding blind disassembly.

[0017] Preferably, when the flow difference reaches the secondary protection threshold, the corresponding measures are taken after a delay of 5 to 10 seconds; this avoids accidental shutdown due to instantaneous flow fluctuations (such as pump start-up and shutdown, valve adjustment); it provides time for operators to manually confirm and intervene; and it utilizes the thermal inertia of the furnace body (the vacuum induction furnace can still maintain safety for several seconds after power failure) for buffering.

[0018] Preferably, the flow reference value of each branch is determined by one of the following methods: The system records self-learning values ​​under normal operating conditions, manually set values ​​input according to the equipment parameter manual, and benchmark values ​​dynamically adjusted according to the current smelting process stage.

[0019] Preferably, the present invention further includes a flow total verification step: calculate the sum of flow rates ΣQ_branch of each branch and compare it with the flow rate Q_out of the main outlet pipe. If |ΣQ_branch-Q_out|>the allowable error, trigger the "flow measurement inconsistency, please check the sensor" warning, without stopping the machine, and prompt the operator to check whether each flow meter is working properly.

[0020] The core protection point of this invention lies in installing a flow meter on both the inlet and outlet main pipes of the cooling system. These two flow meters continuously monitor the total water flow entering and leaving the furnace cooling circuit. Branch flow meters are installed at the outlets of the five cooling branches: furnace body, induction coil, ladle, furnace cover, and furnace door. A dedicated control unit (such as a PLC) collects the flow signals and performs logical analysis and judgment. When the main pipe flow monitoring detects an anomaly, the control unit analyzes the deviation of each branch flow from a preset benchmark value to quickly locate the specific branch where the fault occurred. Then, different protection strategies are set based on the different branches, ensuring production safety while effectively reducing false alarms and missed alarms.

[0021] The core protection logic of this invention is as follows: 1. Flow Balance Judgment (Main Logic): In an ideal, leak-free, and blockage-free closed loop, the influent flow rate and the effluent flow rate should be approximately equal. By calculating the difference ΔQ, system anomalies can be readily detected. A continuous increase in ΔQ may indicate a leak in the pipeline (reduced outflow) or gas blockage (affecting measurement). A sudden and drastic change in ΔQ may indicate a pipeline rupture or severe blockage. ΔQ = |Qin - Qout|, with normal fluctuations ≤ 5 L / min. When ΔQ consistently exceeds 5 L / min and surpasses the alarm threshold Qa (e.g., 10 L / min), a Level 1 warning is triggered; when ΔQ > Qs (e.g., 20 L / min), a Level 2 protection is triggered.

[0022] 2. Absolute Flow Rate Judgment (Auxiliary Logic): Simultaneously monitor whether the inlet water flow rate reaches the minimum safe flow rate Qmin required for equipment cooling. Even if the flow rates are balanced, insufficient total inlet water flow rate can still lead to overheating risks.

[0023] 3. Trend Judgment (Advanced Logic): Analyzes the flow rate trend over time, sampling Qout every 10 seconds and calculating the moving average. If the average value drops by more than 5 L / min over three consecutive sampling periods without other abnormalities, a "Filter Clogging Warning" is triggered. For example, a slow but continuous decrease in water flow may be an early sign of filter clogging or pump performance degradation, triggering a maintenance warning for predictive maintenance.

[0024] 4. Branch Fault Location Logic: When the main pipe flow difference ΔQ exceeds the threshold, the control unit reads the flow meter data of each branch and calculates the deviation between the real-time flow and the reference flow of each branch. If the deviation of a certain branch significantly exceeds that of other branches and the preset threshold, the branch is determined to be an abnormal source, and the location is displayed on the human-machine interface.

[0025] When any of the above judgment logics exceeds the safety threshold, the control unit will execute different levels of protection actions, from "early warning" to "emergency shutdown," according to the preset program.

[0026] Compared with the prior art, the beneficial effects of the present invention are: 1. Direct and reliable: Directly monitors the physical quantity that determines the cooling effect - flow rate, which is more fundamental and accurate than monitoring pressure, greatly reducing false alarms and missed alarms.

[0027] 2. Early warning: It can detect potential problems by detecting small changes or abnormal trends in flow before the pipeline is completely blocked or burst, thus providing early warning protection and preventing the accident from escalating.

[0028] (1) Predictive maintenance capability: This invention continuously samples the outflow rate Qout and calculates the moving average value. When the flow rate shows a slow downward trend, it can trigger the "filter blockage warning" in advance. At this time, the flow rate is still within the normal range, thus realizing predictive maintenance before the failure occurs.

[0029] (2) Advantage of advance time: Existing technology has zero advance time; the present invention can detect fault signs several hours or even days in advance, which makes it easier to arrange planned downtime maintenance and avoid unplanned downtime losses.

[0030] (3) Distinguishing between gradual and sudden failures: Existing technologies cannot distinguish whether a decrease in flow rate is due to gradual blockage or sudden burst; the trend judgment logic of this invention can clearly distinguish: slow and continuous decrease → gradual blockage (early warning); sudden drop → sudden burst (emergency shutdown).

[0031] (3) Monitoring of water pump performance degradation: Existing technologies cannot monitor water pump performance degradation; This invention can predict water pump performance degradation by analyzing the historical trend of pump power or current required to achieve the same flow rate under constant valve opening.

[0032] 3. Powerful functions: It can not only realize protection shutdown, but also assist in diagnosing the cause of faults (such as by comparing the magnitude and sign of ΔQ to make a preliminary judgment on whether it is a leak or a blockage), and provide data support for equipment maintenance.

[0033] 4. Good adaptability: The protection threshold can be flexibly set according to the furnace model and smelting process stage, and the degree of intelligence is high.

[0034] 5. Rapid Fault Location: By using the four branch water flow meters, when the main pipe flow is abnormal, the specific faulty branch (furnace body, coil, ladle or furnace cover) can be quickly located, reducing the troubleshooting time from several hours to several minutes; accurate location avoids repeated downtime and unnecessary maintenance costs caused by "repairing the wrong place", reducing misjudgment and repeated maintenance; at the same time, it supports differentiated protection strategies. Attached Figure Description

[0035] Figure 1 Diagram of the water circulation system for a 200kg vacuum furnace; Figure 2This is a diagram showing the modification of the water circulation system for the 200kg vacuum furnace of this invention; In the diagram, 100 is the main inlet water pipe, 1 is the first flow meter, 200 is the main return water pipe, 2 is the second flow meter, 300 is the furnace body cooling branch, 3 is the third flow meter, 400 is the induction coil cooling branch, 4 is the fourth flow meter, 500 is the ladle cooling branch, 5 is the fifth flow meter, 600 is the furnace cover cooling branch, 6 is the sixth flow meter, 700 is the furnace door cooling branch, 7 is the seventh flow meter, and 8 is the control unit. Detailed Implementation

[0036] The technical solutions in the embodiments of the present invention will be clearly and completely described below.

[0037] like Figure 2 As shown, a safety protection method for a vacuum induction furnace cooling system is based on a safety protection device for the vacuum induction furnace cooling system. The safety protection device includes a first flow meter 1 installed on the main inlet water pipe 100, a second flow meter 2 installed on the main return water pipe 200, a third flow meter 3 installed at the outlet of the furnace body cooling branch 300, a fourth flow meter 4 installed at the outlet of the induction coil cooling branch 400, a fifth flow meter 5 installed at the outlet of the ladle cooling branch 500, a sixth flow meter 6 installed at the outlet of the furnace cover cooling branch 600, a seventh flow meter 7 installed at the outlet of the furnace door cooling branch 700, and a control unit 8.

[0038] 9. Touch screen: As a human-machine interface, it is used for parameter setting, real-time data display (including flow of each branch), alarm history query, and has a branch status monitoring area.

[0039] The two ends of the furnace body cooling branch 300, the induction coil cooling branch 400, the ladle cooling branch 500, the furnace cover cooling branch 600, and the furnace door cooling branch 700 are respectively connected to the main water inlet pipe 100 and the main water return pipe 200.

[0040] The control unit 8 is connected to the first flow meter 1, the second flow meter 2, the third flow meter 3, the fourth flow meter 4, the fifth flow meter 5, the sixth flow meter 6, and the seventh flow meter 7.

[0041] Refer to the attached diagram (with) Figure 1 The system schematic diagram is attached. Figure 2 (This is a schematic diagram of the system after the invention is used). A cooling system protection device for a 200 kg vacuum induction furnace includes: 1. First flow meter 1: Installed on the main water inlet pipe 100, to measure the total water inlet flow rate Qin.

[0042] 2. Second flow meter 2: Installed on the main return water pipe 200, to measure the total outflow rate Qout.

[0043] 3. Third flow meter 3: Installed at the outlet of the furnace cooling branch 300 to measure the flow rate Q3 of the furnace branch.

[0044] 4. Fourth flow meter 4: Installed at the outlet of the induction coil cooling branch 400 to measure the flow rate Q4 of the coil branch.

[0045] 5. Fifth flow meter 5: Installed at the outlet of the 500-meter cooling branch of the ladle to measure the flow rate Q5 of the ladle branch.

[0046] 6. Sixth flow meter 6: Installed at the outlet of the furnace cover cooling branch 600 to measure the flow rate Q6 of the furnace cover branch.

[0047] 7. Seventh flow meter 7: Installed at the outlet of the furnace door cooling branch 700 to measure the flow rate Q7 of the furnace door branch.

[0048] 8. PLC control cabinet, i.e., control unit 8: It contains a built-in CPU module, an analog input module (receiving 4-20mA flow signals), and a digital output module (connected to the power control circuit). The PLC has a pre-programmed control program.

[0049] The safety protection method for the cooling system of a vacuum induction furnace includes the following steps: S1, control unit 8 collects the inlet water flow rate Qin, outlet water flow rate Qout, and outlet water flow rates Q3, Q4, Q5, Q6, and Q7 of the cooling system in real time through the first flow meter 1, the second flow meter 2, the third flow meter 3, the fourth flow meter 4, the fifth flow meter 5, the sixth flow meter 6, and the seventh flow meter 7.

[0050] S2. Calculate the real-time flow difference ΔQ=|Qin-Qout| or the flow change rate, and calculate the flow deviation of each branch δi=|Qi-Qibase| / Qibase, where i is 3, 4, 5, 6, 7, and Qibase is the flow baseline value of the corresponding branch.

[0051] S3. Compare ΔQ with the preset alarm threshold Qa and protection threshold Qs, and compare the branch deviation δi with the preset deviation threshold δth, where Qa <Qs。

[0052] If ΔQ>Qa and δi<δth, a Level 1 warning is triggered, issuing an audible and visual alarm and displaying "Cooling system flow is abnormal, please check" on the human-machine interface.

[0053] If ΔQ > Qs or δi > δth, secondary protection is triggered, and abnormal branch information is highlighted on the human-machine interface. Different response strategies are formulated based on the abnormal branch. (1) If the abnormal branch is an induction coil, the main power supply should be cut off immediately.

[0054] (2) If the abnormal branch is the furnace body or ladle, reduce the smelting power to 50% and observe the changes in ΔQ and δi. If it does not recover within 10 seconds, cut off the power.

[0055] (3) If the abnormal branch is the furnace cover or furnace door, an audible and visual alarm will be issued and the system will continue to operate. Repairs will be arranged within 30 minutes.

[0056] If ΔQ < Qa and δi < δth, and the average value of the outflow rate Qout decreases by more than 5 L / min / cycle over three consecutive sampling periods, it is determined to be progressive filter clogging, triggering a maintenance warning of "Filter clogging risk, check within 30 hours recommended". Without shutting down the machine, a yellow warning message will be displayed on the touch screen.

[0057] If ΔQ < Qa and δi < δth, and the flow rate of each branch decreases for three consecutive sampling periods, it is determined that the pump performance has deteriorated. If the outflow rate Qout drops suddenly, and the decrease in outflow rate per unit time exceeds the preset threshold, the smelting power supply will be immediately cut off.

[0058] In step S2, it is also calculated whether the inlet flow rate Qin is lower than the minimum required flow rate Qmin. If so, the control unit 8 directly triggers the protection logic and triggers the "insufficient inlet flow rate" warning. At the same time, a delay timer is started. If Qin does not recover after the delay, the smelting power supply is immediately cut off.

[0059] The protection threshold Qs is dynamically adjusted according to different melting stages of the vacuum induction furnace: Qs is set to 30L / min for the preheating stage, 15L / min for the melting / refining stage, and 25L / min for the casting stage.

[0060] The first flow meter 1 and the second flow meter 2 are one of electromagnetic flow meters, ultrasonic flow meters or turbine flow meters.

[0061] The control unit 8 also includes a human-machine interface for real-time display of inlet flow rate, outlet flow rate, flow rate difference, alarm information and historical data.

[0062] When the flow difference reaches the secondary protection threshold, there will be a delay of 5 to 10 seconds before corresponding measures are taken.

[0063] The baseline flow rate for each branch is determined using one of the following methods: The system records self-learning values ​​under normal operating conditions, manually set values ​​input according to the equipment parameter manual, and benchmark values ​​dynamically adjusted according to the current smelting process stage.

[0064] The safety protection method for the vacuum induction furnace cooling system also includes a flow total verification step: calculate the sum of the flow rates of each branch ΣQ_branch and compare it with the flow rate Q_out of the main outlet pipe. If |ΣQ_branch-Q_out|> the allowable error, then a "flow measurement inconsistency" message will be displayed, triggering a sensor self-test warning and prompting the operator to check the sensor and pipeline.

[0065] Specific workflow: 1. After system startup or overhaul, run the learning mode for 30 minutes under normal operating conditions and automatically record the average flow rate of each branch as the baseline value: Q3_base, Q4_base, Q5_base, Q6_base, Q7_base.

[0066] 2. During normal smelting, the PLC continuously reads all flow signals and calculates ΔQ = |Qin - Qout| once per second. Simultaneously, it monitors whether Qin is greater than the minimum safe flow rate Qmin (e.g., 300 L / min).

[0067] 3. Scenario 1 (Main Pipe Abnormality, Branch Location): Assume a crack appears in a cooling water pipe somewhere in the furnace body. The Qout reading gradually decreases below Qin, and ΔQ continues to increase to 25L / min (exceeding the threshold). The PLC triggers a "Level 1 Alarm" and immediately starts troubleshooting the branch: reading the flow rate of each branch and calculating the deviation. If the deviation of each branch is less than δth, the touch screen displays "Main pipe flow is unbalanced, please check the system".

[0068] 4. Scenario 2 (Severe Branch Blockage): Assume the induction coil branch suddenly becomes severely blocked. Q4 drops sharply to 40L / min within 2 seconds, causing Qout to decrease accordingly, and ΔQ to increase rapidly to 80L / min (exceeding the protection threshold). The PLC immediately initiates branch troubleshooting, calculates the deviation, and finds that δ4 is much greater than δth, determining that the coil branch is abnormal. The touchscreen highlights "Abnormal induction coil branch flow" and records "Coil branch blocked, emergency shutdown." The PLC immediately cuts off the power to the vacuum induction furnace.

[0069] 5. Scenario 3 (Filter Clogging Warning): During normal smelting, the PLC detects that the average value of the outlet water flow rate Qout decreases from 300L / min to 290L / min, 282L / min, and 275L / min over three consecutive sampling cycles (sampling once every 10 seconds), with a decrease exceeding 5L / min / cycle. However, ΔQ and all δi values ​​remain within the normal range. The PLC determines this as progressive filter clogging, triggering a maintenance warning of "Filter clogging risk, check recommended within 30 hours." The system operates without shutdown, and a yellow warning message is displayed on the touchscreen.

[0070] 6. Scenario 4 (Sensor Fault Detection): The PLC calculates the sum of the flow rates of each branch, ΣQ_branch=Q3+Q4+Q5+Q6+Q7=80+118+58+42+20=318L / min, while the flow rate of the main outlet pipe, Q_out=300L / min, is 18L / min, exceeding the allowable error of 5L / min. The PLC triggers a "Flow measurement inconsistency, please check the sensor" warning without shutting down the system, prompting the operator to check whether each flow meter is working properly.

[0071] 7. Scenario 5 (Insufficient Water Supply): The PLC detects that the inlet water flow rate Qin drops from 350L / min to 250L / min (below Qmin=300L / min), triggering an "Insufficient Water Flow Rate" warning and initiating a 5-second delay. If Qin does not recover after 5 seconds, the smelting power supply is automatically cut off; if Qin recovers to above 300L / min within 5 seconds, the shutdown command is canceled. Since the flow rate in each branch decreases proportionally, the branch deviation may not exceed the threshold, therefore, the branch positioning alarm is not triggered.

[0072] Through the above methods, the present invention not only achieves highly sensitive safety monitoring of the vacuum induction furnace cooling system, but also has the ability to quickly locate faults, greatly improving maintenance efficiency.

Claims

1. A safety protection method for a vacuum induction furnace cooling system, based on a safety protection device for a vacuum induction furnace cooling system, characterized in that: The safety protection device for the vacuum induction furnace cooling system includes a first flow meter (1) installed on the main inlet pipe (100), a second flow meter (2) installed on the main return pipe (200), a third flow meter (3) installed at the outlet of the furnace body cooling branch (300), a fourth flow meter (4) installed at the outlet of the induction coil cooling branch (400), a fifth flow meter (5) installed at the outlet of the ladle cooling branch (500), a sixth flow meter (6) installed at the outlet of the furnace cover cooling branch (600), a seventh flow meter (7) installed at the outlet of the furnace door cooling branch (700), and a control unit (8). The two ends of the furnace body cooling branch (300), induction coil cooling branch (400), ladle cooling branch (500), furnace cover cooling branch (600), and furnace door cooling branch (700) are respectively connected to the main water inlet pipe (100) and the main water return pipe (200); The control unit (8) is connected to the first flow meter (1), the second flow meter (2), the third flow meter (3), the fourth flow meter (4), the fifth flow meter (5), the sixth flow meter (6), the seventh flow meter (7), and the water pump; The safety protection method for the cooling system of a vacuum induction furnace includes the following steps: S1, the control unit (8) collects the inlet water flow rate Qin, outlet water flow rate Qout, and outlet water flow rates Q3, Q4, Q5, Q6, and Q7 of the cooling system in real time through the first flow meter (1), the second flow meter (2), the third flow meter (3), the fourth flow meter (4), the fifth flow meter (5), the sixth flow meter (6), and the seventh flow meter (7); S2. Calculate the real-time flow difference ΔQ=|Qin-Qout| or the flow change rate, and calculate the flow deviation of each branch δi=|Qi-Qibase| / Qibase, where i is 3, 4, 5, 6, 7, and Qibase is the flow baseline value of the corresponding branch. S3. Compare ΔQ with the preset alarm threshold Qa and protection threshold Qs, and compare the branch deviation δi with the preset deviation threshold δth, where Qa <Qs; If ΔQ>Qa and δi<δth, a level one warning is triggered, an audible and visual alarm is issued, and the message "Cooling system flow is abnormal, please check" is displayed on the human-machine interface. If ΔQ > Qs or δi > δth, secondary protection is triggered, and abnormal branch information is highlighted on the human-machine interface. Different response strategies are formulated based on the abnormal branch. (1) If the abnormal branch is an induction coil, the main power supply should be cut off immediately; (2) If the abnormal branch is the furnace body or ladle, reduce the smelting power to 50% first, observe the changes in ΔQ and δi, and cut off the power if it does not recover within the preset time. (3) If the abnormal branch is the furnace cover or furnace door, an audible and visual alarm will be issued and the system will continue to operate. Repairs will be arranged within 30 minutes. If ΔQ < Qa and δi < δth, and the average value of the outflow rate Qout decreases by more than 5 L / min / cycle for three consecutive sampling cycles, it is determined to be progressive filter clogging, triggering a maintenance warning of "Filter clogging risk, check within 30 hours" without shutting down the machine, and the touch screen displays a yellow warning message. If ΔQ < Qa and δi < δth, and the flow rate of each branch decreases for three consecutive sampling periods, it is determined that the pump performance has deteriorated. If the outflow rate Qout drops suddenly, and the decrease in outflow rate per unit time exceeds the preset threshold, the smelting power supply will be immediately cut off.

2. The safety protection method for the cooling system of a vacuum induction furnace according to claim 1, characterized in that: In step S2, it is also calculated whether the inlet flow rate Qin is lower than the minimum required flow rate Qmin. If so, the control unit (8) directly triggers the "insufficient inlet flow rate" warning and starts a delay timer. If Qin does not recover after the delay, the smelting power supply is immediately cut off.

3. The safety protection method for the cooling system of a vacuum induction furnace according to claim 1, characterized in that, The protection threshold Qs is dynamically adjusted according to different melting stages of the vacuum induction furnace: Qs is set to 30L / min for the preheating stage, 15L / min for the melting / refining stage, and 25L / min for the casting stage.

4. The safety protection method for the cooling system of a vacuum induction furnace according to claim 1, characterized in that, The first flow meter (1), the second flow meter (2), the third flow meter (3), the fourth flow meter (4), the fifth flow meter (5), the sixth flow meter (6), and the seventh flow meter (7) are one of the following: electromagnetic flow meter, ultrasonic flow meter, or turbine flow meter.

5. The safety protection method for the cooling system of a vacuum induction furnace according to claim 1 or 2, characterized in that, The human-machine interface is used to display inflow rate, outflow rate, flow rate difference, alarm information and historical data in real time.

6. The safety protection method for the cooling system of a vacuum induction furnace according to claim 1 or 2, characterized in that: When the flow difference reaches the secondary protection threshold, delay for 5 to 10 seconds before taking corresponding measures.

7. The safety protection method for the cooling system of a vacuum induction furnace according to claim 1 or 2, characterized in that, The baseline flow rate for each branch is determined using one of the following methods: The system records self-learning values ​​under normal operating conditions, manually set values ​​input according to the equipment parameter manual, and benchmark values ​​dynamically adjusted according to the current smelting process stage.

8. The safety protection method for the cooling system of a vacuum induction furnace according to claim 1 or 2, characterized in that, It also includes a flow total verification step: calculate the sum of flow of each branch ΣQ_branch and compare it with the flow of the main outlet pipe Q_out. If |ΣQ_branch-Q_out|>the allowable error, a "flow measurement inconsistency, please check the sensor" warning is triggered without stopping the machine, prompting the operator to check whether each flow meter is working properly.

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