JP5585517B2 - Refining equipment for blowing powder into molten steel, leak detection method and program for powder blowing tank - Google Patents

Description

  The present invention relates to a refining facility for blowing powder into molten steel from a powder blowing tank with pressurized gas, a leak detection method for a powder blowing tank in the facility, and a program.

  In the secondary refining in the steel making process, which is one of the steel manufacturing processes, powder is blown into the molten steel to remove impurities. As one method for realizing this process, after charging powder into a powder blowing tank, it is sealed with a tank seal valve, and pressurized gas is supplied into the powder blowing tank to accumulate pressure, Powder is blown into the molten steel from the lance with the pressurized gas accumulated in the body blowing tank.

  As the tank seal valve, a highly airtight one such as a ball valve is selected. However, since the particle size of the powder is small, the powder may enter the tank seal valve during operation. If the powder enters the tank seal valve, the powder bites into the ball, and the airtightness of the tank seal valve cannot be maintained. In addition, the seal portion of the tank seal valve may be worn due to long-term use. When powder enters the tank seal valve or wear of the seal part in this way, the pressurized gas in the powder blowing tank leaks from there and the pressure in the powder blowing tank drops. End up. It is necessary to blow the powder at a pressure higher than the static pressure of the molten steel.When the pressure in the powder blowing tank drops, the molten steel enters the outlet of the tip of the lance immersed in the molten steel, If the lance is damaged, it becomes unusable and the operation cannot be continued.

  In the case of other systems in which powder is blown in while a pressurized gas is kept flowing and being pumped, even if there is a slight leak, there is no influence to stop the operation. For example, in Patent Document 1, in another method in which powder is blown in while continuing to feed under pressure by flowing a pressurized gas, the powder to the molten steel is judged as a tank-side leak when the tank internal pressure falls below the lance back pressure. A body blowing control method is disclosed. Further, in Patent Document 2, in order to detect a gas leak in a gas supply pipe connecting a gas consumption facility and a gas supply facility, it is close to the gas supply facility in a gas supply line connecting the gas consumption facility and the gas supply facility. Gas leak detection provided with a pressure gauge for detecting the pressure in the gas supply pipe provided in the part and a flow meter for detecting the gas flow rate in the gas supply pipe provided in a part near the gas consuming equipment of the gas supply pipe An alarm device is disclosed.

Japanese Unexamined Patent Publication No. 7-150218 JP 63-24493 A

  However, in the method of blowing powder after accumulating pressure in the powder blowing tank, the method of confirming leak by comparing the pressure in the tank and the lance back pressure cannot be used as disclosed in Patent Document 1. Further, as disclosed in Patent Document 2, it is expensive to provide a pressure gauge or a flow meter at a place where a leak is assumed.

  Conventionally, the pressure accumulated in the powder blowing tank has been designed to be higher than necessary so that the blowing can be continued even if the pressure in the powder blowing tank drops due to some leakage. there were. However, in this case, it is necessary to use a high-pressure container for the powder blowing tank or to increase the supply pressure of the pressurized gas, which increases the construction cost of the equipment.

  The present invention has been made in view of the above points, and an object of the present invention is to enable detection of leakage in a powder blowing tank with a simple configuration and low cost.

The refining equipment for injecting powder into the molten steel of the present invention is a refining equipment for injecting powder from a powder injection tank into the molten steel with pressurized gas, and the powder supplying the powder to the powder injection tank. Body supply means, pressurized gas supply means for supplying and accumulating pressurized gas to the powder blowing tank, load detection means for detecting the load of the powder blowing tank, and the powder supply means, coupled between said powder blow tank, and a telescopic tube which expands and contracts in the load detection direction of the load detecting means, further, the tank seal between the powder blow tank and the powder supply means A valve, the powder supply means is provided with a powder extraction valve, the expansion tube is disposed between the powder extraction valve and the tank seal valve, and further, a load measured by the load detection means on the basis of the load control value which is set in advance as the actual value, the powder cropping It comprising the determining control means leakage from the tank seal valve of the powder blow tank when the valve is closed.
Another feature of the refining equipment for injecting powder into the molten steel of the present invention is that the control means issues an alarm when the leakage of the powder injection tank is determined or the powder injection The point is to stop accumulating pressure in the tank.
Another feature of the refining equipment for blowing powder into the molten steel of the present invention is that the expansion tube is made of metal.
The leak detection method of the powder injection tank of the present invention is a leak detection method of the powder injection tank in the refining equipment for injecting powder into the molten steel of the present invention, and the actual load value measured by the load detection means And a load management value set in advance, and a procedure for determining leakage of the powder blowing tank.
The program of the present invention is a program for detecting a leakage of a powder blowing tank in a refining facility for blowing powder into the molten steel of the present invention, and is preset with a load actual value measured by the load detecting means. Based on the load management value, the computer is caused to execute processing for determining leakage of the powder blowing tank.

  According to the present invention, by using an expansion / contraction tube that expands and contracts in the load detection direction of the load detection means, the occurrence of leak is determined using the load detection means that has been installed so far for controlling the blowing of powder. It is possible to detect a leak in the powder blowing tank with a simple configuration and low cost.

It is a figure which shows schematic structure of the refining equipment which concerns on embodiment of this invention. It is a characteristic view which shows the example of the load actual value measured with a load detection sensor, (a) is a characteristic view at the time of normal, (b) is a characteristic view at the time of leak generation. It is a figure which shows the state around a tank seal valve at the time of the pressure accumulation to a powder blowing tank, (a) is a figure which shows the state at the time of normal, (b) is a figure which shows the state at the time of leak generation. It is a flowchart which shows the determination process of leak generation.

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.
In FIG. 1, the schematic structure of the refining equipment of the steel making process in the steel manufacturing industry based on embodiment of this invention is shown. This refining facility is a facility for blowing powder 4 from a powder blowing tank (hereinafter simply referred to as a tank) 1 into molten steel 3 in a pan 2, and as described in detail below, Has a leak detection system.

  Above the tank 1, there are provided a hopper 5 that is a powder supply source for supplying the powder 4 to the tank 1, and a powder cutting valve 6 that opens and closes a powder supply route from the hopper 5 to the tank 1. The powder supply means is constituted by the powder cutting valve 6. On the powder supply route from the hopper 5 to the tank 1, a tank seal valve 8 for sealing the tank 1 when the powder 4 is blown is disposed. And between the powder cutting valve 6 and the tank seal valve 8 is connected with a metal expansion and contraction tube 7.

  Further, below the tank 1, an outlet valve 9 for discharging the powder 4 charged in the tank 1 and a lance 10 connected to the outlet valve 9 by a flexible pipe are provided. The lance 10 is used to guide the powder 4 discharged from the outlet valve 9 into the molten steel 3 and is controlled to be raised and lowered by the drive motor 11.

  Further, on the side of the tank 1, a pressurized gas supply source 12 that supplies a pressurized gas in which argon gas, nitrogen gas, or the like is pressurized to the tank 1, and a pressurized gas from the pressurized gas supply source 12 to the tank 1. A pressurization valve 13 for opening and closing the supply route is provided, and the pressurization gas supply means is constituted by the pressurization gas supply source 12 and the pressurization valve 13. The pressurizing valve 13 and the tank 1 are connected by flexible piping having flexibility.

  The tank 1 and the hopper 5 are supported by a frame 14. In particular, the tank 1 is floatingly supported in the vertical direction, and the bottom surface of the tank 1 is supported by a load detection sensor 15 that detects the load of the tank 1. Here, a straight tube is selected as the expansion tube 7 disposed between the powder cutting valve 6 and the tank seal valve 8, and its mounting direction is the same axial direction as the load detection sensor 15 that supports the tank 1. To do. That is, the expansion tube 7 expands and contracts in the load detection direction of the load detection sensor 15, in the case of this embodiment, in the vertical direction, and does not substantially expand in other directions. The telescopic tube 7 can be composed of a telescopic tube having a so-called bellows structure.

  The refining equipment according to this embodiment includes a control device 16 that controls the blowing of the powder 4 into the molten steel 3. Although described in detail later, the control device 16 includes a comparison calculation unit 17 that performs various calculations, a command unit 18 that issues various commands, a valve drive circuit 19, and a filter 20. The valve drive circuit 19 controls the powder extraction valve 6, the tank seal valve 8, and the pressurization valve 13 based on a command from the command unit 18. Further, the outlet valve 9 and the drive motor 11 are connected to the motor drive circuit 22 of the motor control panel 21, and the valve drive circuit 19 is connected to the outlet via the motor drive circuit 22 based on a command from the command unit 18. The valve 9 and the drive motor 11 are controlled.

  Connected to the control device 16 are a management value setting unit 23 for setting various management values by an operator input and an operation unit 24 for performing various operations. The control device 16 is connected to an alarm device 25 that issues an alarm.

  In addition, the actual load value measured by the load detection sensor 15 is input to the comparison calculation unit 17 of the control device 16 via the filter 20. The filter 20 is for removing disturbances such as vibrations in the factory, and for example, a band pass filter for removing high frequency components is used.

Next, the processing operation of the refining equipment according to this embodiment will be described. FIG. 2A shows an example of the actual load value measured by the load detection sensor 15 at the normal time. First, the supply of the powder 4 to the tank 1 is started (timing t _{1 in} FIG. 2A). At this time, the powder cutting valve 6, the tank seal valve 8, the outlet valve 9, and the pressurizing valve 13 are all closed. When the supply of the powder 4 is started, the initial weight T ₀ of the tank 1 is measured by the load detection sensor 15. The control device 16 stores the initial weight T ₀ in the comparison calculation unit 17. The supply set amount T ₁ of the powder 4 set in advance by the management value setter 23 by the operation manager is stored in the comparison calculation unit 17, and the initial weight T ₀ of the tank 1 is measured by the load detection sensor 15. When stored in the comparison calculation unit 17, the target weight T ₂ = T ₀ + T _{1 for} completing the supply of the powder 4 is stored in the comparison calculation unit 17.

After the target weight T ₂ is stored in the comparison calculation unit 17, when an operation command from the operation manager is input from the operation unit 24, the command unit 18 outputs an opening command for the tank seal valve 8 to the valve drive circuit 19. To do. As a result, the tank seal valve 8 is opened. When the tank seal valve 8 is opened, the command unit 18 outputs a command for opening the powder extraction valve 6 to the valve drive circuit 19. As a result, the powder cutting valve 6 is also opened. In this state, the powder 4 of the hopper 5 is dropped and supplied from the powder cutting valve 6 to the tank 1 through the expansion tube 7 and the tank seal valve 8.

When the powder 4 is supplied to the tank 1, the actual load value measured by the load detection sensor 15 increases. When the measured value reaches the target weight T ₂ , the comparison calculation unit 17 sends a command to the command unit 18. Outputs a stop signal. When the command unit 18 receives the stop signal, it outputs a command to close the powder cutting valve 6 to the valve drive circuit 19. Thereby, the powder cutting valve 6 is closed. When the powder cutting valve 6 is closed, the command unit 18 outputs a closing command for the tank seal valve 8 to the valve drive circuit 19. As a result, the tank seal valve 8 is closed and the supply of the powder 4 to the tank 1 is completed (timing t _{2 in} FIG. 2A). When the measured value of the load detection sensor 15 reaches the target weight T ₂ , the powder cutting valve 6 and the tank seal valve 8 are closed. However, due to the time difference until the valves 6 and 8 are closed, the pressure to the tank 1 is actually increased. When the supply of the powder 4 is stopped, the measured value of the load detection sensor 15 is T ₃ (> T ₂ ).

When the supply of the powder 4 to the tank 1 is completed, the pressure accumulation to the tank 1 is started (timing t _{3 in} FIG. 2A). At this time, the powder cutting valve 6, the tank seal valve 8, the outlet valve 9, and the pressurizing valve 13 are all closed. The command unit 18 outputs a command to open the pressurizing valve 13 to the valve drive circuit 19. As a result, the pressurizing valve 13 is opened, and the pressurized gas is supplied to the tank 1. When the time t elapses after the pressurization valve 13 is opened, the pressure in the tank 1 becomes equal to the pressure of the pressurization gas from the pressurization gas supply source 12, and the command unit 18 closes the pressurization valve 13 to the valve drive circuit 19. Outputs a command. As a result, the pressurizing valve 13 is closed, and the pressure accumulation in the tank 1 is completed (timing t _{4 in} FIG. 2A).

When the pressure accumulation in the tank 1 is completed, the command unit 18 outputs an opening command for the outlet valve 9 to the valve drive circuit 19. As a result, the outlet valve 9 is opened, and the powder 4 is blown out from the blowing port at the tip of the lance 10 by the pressurized gas accumulated in the tank 1 (timing t _{5 in} FIG. 2A). In addition, the command unit 18 outputs a drive signal to the drive motor 11 via the motor drive circuit 22, lowers the lance 10, immerses the blowing port at the tip of the lance 10 in the molten steel 3, and the powder 4 blown into molten steel 3 (timing t ₆ in FIG. 2 (a)).

When the injection of the powder 4 into the molten steel 3 is completed or stopped, the command unit 18 outputs a drive signal to the drive motor 11 via the motor drive circuit 22 to raise the lance 10, and the tip of the lance 10. Is moved above the molten steel 3 (timing t _{7 in} FIG. 2A). Further, the command unit 18 outputs a closing command for the outlet valve 9 to the valve drive circuit 19. As a result, the outlet valve 9 is closed and the injection of the powder 4 into the molten steel 3 is completed (timing t _{8 in} FIG. 2A).

  Here, a state in which the powder 4 enters the tank seal valve 8 and the pressurized gas in the tank 1 leaks from the tank seal valve 8 will be described. FIG. 2B shows an example of the actual load value measured by the load detection sensor 15 when a leak occurs.

When a leak occurs, when the pressure accumulation in the tank 1 is started, the pressurized gas in the tank 1 leaks from the tank seal valve 8 and flows into the expansion and contraction tube 7. 3A and 3B are diagrams showing a state around the tank seal valve 8 when accumulating pressure in the tank 1, wherein FIG. 3A is a diagram showing a normal state, and FIG. 3B is a diagram showing a state when a leak occurs. . As shown in FIG. 3B, when the pressurized gas in the tank 1 leaks from the tank seal valve 8 and flows into the expansion / contraction tube 7, the powder extraction valve 6 is closed, so that the compression gas expands / contracts. Accumulate in the tube 7. Accordingly, the expansion tube 7 is filled with pressurized gas, and a force is generated in the direction in which the expansion tube 7 is extended. If the cross-sectional area of the expansion tube 7 is S and the pressure of the pressurized gas is P, the force N acting in the same axial direction as the load detection sensor 15 is
N = a × P × S
It becomes. The coefficient a represents a reduction due to the reason that the pressure acting on the expansion tube 7 is not equal to P because the powder cutting valve 6 is not a gas sealing valve and cannot be completely sealed. When this force N is generated, the measured value of the load detection sensor 15 increases in proportion to the force N. That is, the occurrence of leak can be determined based on the actual load value measured by the load detection sensor 15. As shown in FIG. 2B, there is a time delay τ from the start of pressure accumulation in the tank 1 until the occurrence of leak can be determined based on the measurement value of the load detection sensor 15.

With reference to FIG. 4, the leak occurrence determination process by the control device 16 will be described. A load management value ΔT previously set by the management value setter 23 by the operation manager is stored in the comparison calculation unit 17. The load management value ΔT is a numerical value obtained experimentally by flowing a pressurized gas through the expansion tube 7 in advance. Comparison operation unit 17 stores the measured value T ₃ of the load detection sensor 15 immediately before the start of the accumulator to the tank 1 (step S101).

Next, comparison operation unit 17, current measurement values T of the load detection sensor 15, the difference between the measured value T ₃ of the load detection sensor 15 immediately before the start of the accumulator to the tank 1 the load control value ΔT than the It is determined whether or not (step S102).

When T−T ₃ ≧ ΔT, it may be determined that a force is generated in the direction of extending the telescopic tube 7 at that time, that is, a leak is generated. In step S103, it is determined whether or not the state of T−T ₃ ≧ ΔT continues for a predetermined time. Since the expansion tube 7 is an elastic body having a predetermined spring constant, when a force is generated in the extending direction, the measurement value of the load detection sensor 15 appears in a gradually decreasing sine wave shape. Therefore, after full-wave rectification is performed on the measurement value of the load detection sensor 15 appearing in a sine wave shape, it is determined whether or not the state of T−T ₃ ≧ ΔT continues for a predetermined time. When the state of T−T ₃ ≧ ΔT continues for a predetermined time, the process proceeds to step S104, and it is determined that a force is generated in the direction in which the telescopic tube 7 is extended, that is, a leak is generated.

  When it is determined that a leak has occurred, the comparison calculation unit 17 issues an alarm via the alarm device 25 or outputs an abnormal stop signal to the command unit 18. When the command unit 18 receives the abnormal stop signal, it outputs a command to close the pressurizing valve 13 to the valve drive circuit 19. As a result, the pressurizing valve 13 is closed, and the pressure accumulation in the tank 1 is automatically stopped.

  In the case of No in steps S102 and S103, the monitoring in steps S102 and S103 is repeated until the pressure accumulation in the tank 1 is completed (step S105).

  As described above, it is detected at an early stage that the pressurized gas in the tank 1 has leaked from the tank seal valve 8 to alert the operation manager, or the pressure accumulation in the tank 1 is automatically stopped. As a result, damage to equipment such as the lance 10 can be prevented. In addition, since it is not necessary to increase the pressure accumulated in the tank 1 more than necessary, it is not necessary to use a high-pressure container for the tank 1 or to increase the supply pressure of the pressurized gas, thereby reducing the construction cost of the equipment. Can do.

  In addition, by using the telescopic tube 7 that expands and contracts in the load detection direction of the load detection sensor 15, the occurrence of leak is determined using the load detection sensor 15 that has been installed so far for controlling the blowing of powder. This makes it possible to detect leaks with a simple configuration and low cost.

  The control device 16 can be configured using a personal computer, a sequencer, or a hard relay circuit. For example, when a personal computer or a sequencer is used, a keyboard and mouse for inputting settings to the management value setter 23 as hardware, a display for displaying a screen, and an I / O for transmitting / receiving signals to / from the motor control panel 21. An O unit, a load conversion amplifier for taking a signal from the load detection sensor into the I / O unit, an external memory such as a DHD or HDD, and a main body including a CPU and a main memory may be used. In this case, each process executed by the comparison calculation unit 17, the command unit 18, and the management value setting unit 23 is executed by creating software, loading it in the personal computer or sequencer body.

  1: powder blowing tank, 2: pan, 3: molten steel, 4: powder, 5: hopper, 6: powder cutting valve, 7: expansion tube, 8: tank seal valve, 9: outlet valve, 10: Lance, 11: Drive motor, 12: Pressurized gas supply source, 13: Pressurized valve, 14: Frame, 15: Load detection sensor, 16: Control device, 17: Comparison operation unit, 18: Command unit, 19: Valve drive Circuit: 20: Filter, 21: Motor control panel, 22: Motor drive circuit, 23: Management value setter. 24: Controller, 25: Alarm

Claims (5)

A refining facility for blowing powder into molten steel from a powder blowing tank with pressurized gas,
Powder supply means for supplying powder to the powder blowing tank;
Pressurized gas supply means for supplying and storing pressurized gas to the powder blowing tank;
Load detecting means for detecting the load of the powder blowing tank;
An expansion tube that connects between the powder supply means and the powder blowing tank and expands and contracts in the load detection direction of the load detection means,
Furthermore, a tank seal valve is provided between the powder supply means and the powder blowing tank,
The powder supply means includes a powder cutting valve,
The telescopic tube is disposed between the powder cutting valve and the tank seal valve,
Furthermore, on the basis of the actual load value measured by the load detecting means and a preset load management value, when the powder cutting valve is closed, leakage from the tank seal valve of the powder blowing tank is detected. A refining facility for injecting powder into molten steel, characterized by comprising a control means for judging . Wherein if it is determined leakage of the powder blow tank, the powder molten steel according to claim 1, characterized in that stopping the accumulator to generate an alarm or the powder blow tank Refining equipment to blow. The refining equipment for blowing powder into molten steel according to claim 1 or 2 , wherein the expansion tube is made of metal. A leak detection method for a powder blowing tank in a refining facility for blowing powder into molten steel according to any one of claims 1 to 3 ,
A method for detecting leakage of a powder blowing tank, comprising a procedure for determining leakage of the powder blowing tank based on a load actual value measured by the load detecting means and a preset load management value . A program for detecting leakage of a powder blowing tank in a refining facility for blowing powder into molten steel according to any one of claims 1 to 3 ,
The program for making a computer perform the process which determines the leak of the said powder blowing tank based on the load actual value measured with the said load detection means, and the preset load management value.

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