JPH037383Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a powder injection device for injecting various powdery scouring agents, such as deoxidizers, etc. into molten metal carried out from a melting furnace. The present invention relates to a powder blowing device that can prevent a large amount of carrier gas from flowing into a blowing lance at the end of powder blowing, thereby preventing molten metal from blowing up or boiling over.

[Prior art] Before molten steel produced in a converter, electric furnace, etc. is ingot-formed in a continuous casting device or a mold, it is necessary to (a) equalize and optimize the temperature of the molten steel in the ladle; b) Cleaning of molten steel;
(c) The molten steel undergoes various treatments in a ladle for the purpose of adjusting the molten steel composition.

Methods for treating molten steel in a ladle include the bubbling method, in which inert gas such as Ar gas is blown into the molten steel in the ladle through a bottom blow hole or lance, and the vacuum degassing method, in which molten steel is drawn up into a vacuum chamber and brought into contact with the vacuum section. The law is mainly used.

FIG. 2 shows an example of a bubbling device (hereinafter referred to as a blowing device) that uses a blowing lance.
The tip of the blowing lance 15 is immersed in the molten metal 16 in the ladle 17, and the powder blowing line 14 is connected to the rear end of the blowing lance 15. Powder injection line 14
A blow circuit 4 and a blow tank 10 are connected to each other, and a blow outlet valve 13 and a powder cutting device 12 are disposed between the powder blow line 14 and the blow tank 10. In addition, the powder cutting device 12 and the blowing outlet valve 1
A pressure equalizing pipe 8 that leads to the upper part of the blowing tank 10 is branched from between 3 and a pressure equalizing pipe 8 is connected to a part of the pressure equalizing pipe 8, which is connected to a carrier gas supply source 1.
Note that 2 is a blow pressure reducing valve, 3 is a blow source valve, and 5 is a blow pressure reducing valve.
6 indicates a blowing source valve, and 6 indicates a pressurizing source valve. Powder injection and injection stop using the above device are performed in the following order. First, it is supplied from carrier gas supply source 1.
The pressurized carrier gas such as Ar reaches the pressurizing circuit 7 via the pressurizing source valve 6, and is introduced into the blowing tank 10 via the check valve 20a and the pressure equalizing pipe 8. When the pressure inside the blowing tank 10 becomes equal to the pressure of the carrier gas, the powder cutting device 12 is operated, the blowing outlet valve 13 is opened, and the carrier gas is pumped from the blowing source valve 5 to the lower part of the powder cutting device 12. The powder is sent to the blowing lance 15 through the powder blowing line 14 together with the powder 11 falling from the blowing tank 10, and is blown into the molten metal 16 in the ladle 17.

When stopping powder blowing, first stop the powder cutting device 12 to stop the powder supply, and after allowing only the carrier gas to flow for a very short time, close the blowing outlet valve 13 to completely stop the carrier gas supply. make it stop. The circumstances during this time will be detailed later. Thereafter, in order to remove the powder remaining in the piping, a carrier gas having a lower pressure than the carrier gas passing through the pressurizing circuit 7 is passed from the blow circuit 4 to the powder blowing line 14 to remove the powder remaining in the line 14. Blow into molten metal 16. The reason why the pressure of the carrier gas in the blow circuit 4 is lower than that in the pressure circuit 7 is that when the powder cutting device 12 is stopped, the amount of powder in the powder blowing line 14 decreases and the resistance to pumping the powder increases. This is because if a carrier gas having a pressure comparable to that on the pressure circuit 7 side is used, a large amount of carrier gas may flow due to a decrease in powder pumping resistance.

[Problems to be solved by the invention] Among the above-mentioned operations performed upon completion of powder blowing, from stopping the powder cutting device 12 to closing the blowing outlet valve 13.
The reason for setting a slight time delay before the closure is as follows. That is, if an attempt is made to close the blow-in outlet valve 13 at the same time as the powder extraction device 12 is stopped, the powder will get caught in the seal between the valve seat and the valve body of the blow-in outlet valve 13, making it impossible to close the valve reliably. This is because not only will it disappear, but it will also cause damage to the sealing part, making it impossible to maintain complete gas-tightness.

However, the cutting device 12 stopped and the blow-in outlet valve 13 stopped.
Due to the time difference in closing, the pressure equalizing gas introduced into the blowing tank 10 passes through the pressure equalizing pipe 8 and the blowing outlet valve 13 to the molten metal 16.
The problem is that the molten metal 16 flows into the interior all at once, and as a result, the molten metal 16 blows up or spills over, causing personal injury or the like, or lowering the yield of the product. In other words, when powder is injected, the pressure of the carrier gas is kept in balance with the pumping resistance of the powder, so no boiling over occurs, but the powder cutting device 12 is stopped and the amount of powder in the blowing line 14 is reduced. As a result, the pressure in the blowing line 14 decreases as the resistance to pumping the powder decreases, and as a result, the pressure on the blowing tank 10 side and the pressure inside the blowing line 14 are no longer balanced, and a larger amount of carrier gas flows out from the blowing tank 10 side. This is because the water will flow to the lance 15 side.

Therefore, the present inventors made various efforts to complete a powder blowing device that would prevent molten metal from scattering, and as a result, they completed the present invention.

[Means for solving the problems] The powder blowing device of the present invention, which has achieved the above objectives, has the following features:
A powder cutting device is provided at the lower part of the blowing tank, and a blowing outlet valve is further connected to the downstream side thereof, and an equalizer is connected to the upper space of the blowing tank from between the powder cutting device and the blowing outlet valve. A pressure pipe is provided, a pressure circuit is connected to the pressure equalization pipe, and the powder that has passed through the blow outlet valve from inside the blow tank maintained at high pressure is passed through the pressure circuit and the pressure equalization pipe to the blow outlet valve. In a powder blowing device in which a carrier gas supplied from the upstream side is supplied to a blowing lance via a powder blowing line and blown into molten metal, the pressure equalizing pipe is connected to a blowing tank from a connection position with a pressurizing circuit. The gist is that a shutoff valve is disposed on the upper space side and is closed simultaneously when the powder cutting device is stopped.

[Operation] Stopping operation of powder cutting device 12 and blowing outlet valve 13
The time lag in the closing operation is an unavoidable process operation procedure for protecting the seal portion of the valve 13 and ensuring complete airtightness, and cannot be omitted or changed.
Therefore, in order to prevent the gas in the blowing tank 10 from flowing out all at once to the powder blowing line 14 side, a cutoff valve is provided in a part of the pressure equalizing pipe 8, and the cutoff valve is closed at the same time as the powder cutting device 12 is stopped. We came to the conclusion that it would be best to close it down. However, when the shutoff valve is closed, the gas supply from the carrier gas supply source will be stopped at the same time, and there is a risk that powder removal at the blow-in outlet valve 13 will become impossible. It is necessary to install a shutoff valve closer to the blow tank than the location where it is connected.

The pressurized carrier gas trapped in the blow tank by closing the shutoff valve can be disposed of into the atmosphere by providing a separate pressure relief valve in the blow tank, or it can be gradually released as pipe blowing gas. It can also be discharged from the blow line.

[Embodiment] FIG. 1 is an explanatory diagram showing a typical embodiment of the present invention. The difference in structure from the conventional example shown in FIG. 2 is that a cutoff valve 9 is provided in the pressure equalizing pipe 8. The cutoff valve 9 is disposed closer to the upper space of the blow tank 10 than the joining position of the pressure circuit 7 and the pressure equalization pipe 8.

Next, a procedure for stopping powder injection using a powder injection device equipped with a shutoff valve 9 will be described. First, the powder cutting device 12 is stopped and the cutoff valve 9 is closed almost simultaneously, and after only the carrier gas is allowed to flow for a very short time, the blowing outlet valve 13 is closed. Then, the residual powder in the powder blowing line 14 is removed by passing the carrier gas reduced in pressure from the blow circuit 4, or the pressurized gas in the blowing tank 10 is removed by opening the blowing outlet valve 13 and slightly opening the shutoff valve 9. is gradually introduced into the powder blowing line 14 to perform piping blowing. If the carrier gas in the blowing tank 10 is used for piping blowing, the carrier gas can be saved.

FIG. 3 is an explanatory diagram showing another embodiment of the present invention, and in this embodiment, in addition to the cutoff valve 9, a blow tank 10 is
An exhaust valve 19 is provided at the top, and a differential pressure gauge 18 is further provided between the powder blowing line 14 and the blowing tank 10. The operation at the end of powder injection is as described in step 1 above.
The pressurized carrier gas remaining in the blowing tank is released by opening the exhaust valve 19, and the pressure difference between the pressurized carrier gas and the depressurized carrier gas sent for piping blowing is carried out in accordance with the same procedure as in the example shown in the figure. is read by the differential pressure gauge 18, and the display of the differential pressure gauge 18 is
When the temperature falls below 0.5Kg/cm ² , the exhaust valve 19 is closed, and the cutoff valve 9 is then opened to open the blow tank 10.
The remaining carrier gas will be used as pipe blowing gas.

[Effect of the invention] By providing a cutoff valve for the pressure equalization pipe and closing the valve at the end of blowing, the pressurized carrier gas used for equalizing the pressure in the blowing tank is prevented from flowing out from the blowing lance into the molten metal all at once. , molten metal is prevented from scattering, and a reduction in product yield and the risk of personal injury are avoided.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing a typical embodiment of the present invention, Fig. 2 is an explanatory diagram showing an example of a conventional powder blowing device, and Fig. 3 is an explanatory diagram showing another embodiment of the present invention. be. 1...Carrier gas supply source, 2...Blow pressure reducing valve, 3...Blow source valve, 4...Blow circuit, 5
...Blowing source valve, 6... Pressurizing source valve, 7... Pressurizing circuit, 8... Pressure equalizing pipe, 10... Blowing tank, 11...
... powder, 12 ... powder cutting device, 13 ... blowing outlet valve, 14 ... powder blowing line, 15 ... blowing lance, 16 ... molten metal, 17 ... ladle, 18 ...
Differential pressure gauge, 19...exhaust valve, 20a, 20b...
non-return valve.

Claims (1)

[Scope of utility model registration request] A powder cutting device is provided at the lower part of the blowing tank, and a blowing outlet valve is further connected to the downstream side of the blowing tank. A pressure pipe is provided, and a pressurizing circuit is connected to the pressure equalizing pipe, and the powder that has passed through the blowing outlet valve from inside the blowing tank maintained at high pressure is transferred to the blowing outlet valve through the pressurizing circuit and the pressure equalizing pipe. Carrier gas supplied from the upstream side allows
In a powder blowing device that supplies powder to a blowing lance via a powder blowing line and blows it into molten metal, the pressure equalizing pipe has the powder cutter connected to the upper space side of the blowing tank from the connection position with the pressurizing circuit. A powder blowing device characterized in that it is equipped with a shutoff valve that is closed at the same time as the pumping device is stopped.