JPS5938432Y2 - Double pipe tuyere flow control device for refining - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a device that improves the cooling effect of the side opening of a double tube for blowing gas into molten steel during steel melting.

In recent years, as a melting method for stainless steel, etc., a double pipe side port is installed at the bottom or side wall of a refining vessel containing molten steel, and an inert gas or a reactive gas is blown into the molten steel through the opening. 00 while lowering the partial pressure and suppressing the oxidation of chromium, etc.
A steelmaking method is used in which molten steel is stirred to promote decarburization reactions and other processes for refining.

However, the method of blowing gas using the double front panel is that a protective gas such as argon gas is blown into the outer tube for cooling the panel, and an inert gas such as oxygen, which is mainly used in the early stages of refining, is injected through the inner tube. As the decarburization reaction progresses, the ratio of inert gas is increased.At the final stage of refining, a mixture of reactive gas and mainly inert gas is blown into the refining process.

Fig. 1 shows an example of a conventional gas flow rate control device for a double front panel. In the figure, 1 is an inner pipe through which an inert gas or a reactive gas such as oxygen flows from the direction of the arrow, and 2 is an inner pipe. A flow meter measures the flow rate of gas flowing through the pipe, 3 is a flow rate display controller for displaying the measured flow rate and setting and adjusting the flow rate, and 4 is the controller 3 to adjust the inner pipe gas flow rate. This is a flow control valve for

On the other hand, 5 is an outer tube through which protective gas (argon gas, etc.) flows from the direction of the arrow, 6 is a pressure control valve that adjusts the pressure of the gas flowing through the outer tube 5, and 7 is a pressure gauge that displays the pressure. It is.

9 is a double front separate port for blowing gas into the molten steel.

In such a conventional device, the gas blowing is adjusted by adjusting the outer tube gas by pressure and the inner tube gas by flow rate so that the inner tube gas and the outer tube gas are balanced at the double tube side port 9.

However, as decarburization progresses, if the mixing ratio of oxygen and argon in the inner tube gas is changed from 3:1 to 1:2, for example, the outer tube becomes clogged, and almost no gas comes out from the outer tube. Cooling of the outer tube tuyere deteriorates and the tuyere becomes more susceptible to melting.

This is thought to be because the ratio of argon, which has a cooling effect, increases, which cools the molten steel near the tuyeres and deteriorates fluidity, and also because the molten steel solidifies and adheres to the tuyere 9.

Therefore, as a countermeasure in this case, there is a method of increasing the gas pressure in the clogged outer pipe, but increasing the gas pressure causes interference from the outer pipe gas to the inner pipe gas, resulting in a decrease in the flow rate of the inner pipe gas. occurs and the clogging of the outer tube tuyere cannot be solved.

In order to solve this problem, the present invention uses a flow control valve installed in the outer tube to control the blowing of gas into the outer tube, keeping the flow constant.
On the other hand, if the pressure is set slightly higher than the predetermined pressure and the flow rate is controlled to be constant, if the tuyere is clogged as described above, the flow control valve will open and the flow rate will be within the set pressure range. This increases the pressure, keeps the flow rate constant, and prevents a drop in flow rate due to clogging of the tuyeres.

The present invention will be explained in detail below with reference to an embodiment shown in FIG.

In FIG. 2, the same numbers as in FIG. 1 have the same names and functions as in FIG. 1, so the explanation thereof will be omitted.

10 is an outer pipe gas flow rate controller, 11 is a flow rate adjustment valve, 2'
1 is a flowmeter, and the flow rate measured by the flowmeter 2' is displayed on a flow rate controller 10, and the flow rate set in the flow rate controller 10 is regulated by a flow rate adjustment valve 11.

However, before the ratio of inner pipe gas changes, the flow rate controller 10
The outer tube gas is controlled by the flow rate set to .

Next, the outer pipe pressure control valve 6 is set higher than a predetermined pressure so that the outer pipe gas flow rate remains constant even when the inner pipe gas ratio changes and the outer pipe gas flow rate decreases as described above. put.

In this way, the ratio of oxygen and argon gas in the inner tube gas can be changed from 3=1 to 1:2 as in the case of Fig. 1, and the gas from the outer tube tuyeres can be adjusted as described above. When the blowing becomes weak, the pressure regulating valve 6 is set higher than a predetermined pressure, and the flow regulating valve 11 is operated to reach the set flow rate, so the outer pipe gas pressure increases.

In this case, the flow rate is set to be in balance with the inner pipe flow rate, so in the double front tuyeres, there is no interference between the outer pipe gas and the inner pipe gas, and the flow rate is constant and only the pressure increases, so the tuyeres pass through the tuyere. This makes it possible to strengthen the gas blowout from the outer tube tuyere without cooling, thereby eliminating clogging of the tuyeres.

As described above, the present invention has a simple structure that prevents clogging of the double front tuyeres, and is highly effective in melting steel.

[Brief explanation of the drawing]

Figure 1 shows an example of a conventional gas flow rate control device, Figure 2 shows an example of a conventional gas flow rate control device.
The figure shows an embodiment of the device of the present invention. 1.1'...inner pipe, 2,2'...flow meter, 3,3'
...Flow rate display controller, 4, 4'...Flow rate control valve, 5
, 5'...Outer pipe, 6.6'...Pressure control valve, 7,7
'...Pressure gauge, 9,9'...Double front panel, 10...
・Flow rate controller, 11...Flow rate control valve.

Claims (1)

[Scope of utility model registration request] A mixed gas of inert gas and reactive gas flows from the inner pipe of the double front tuyere for refining, and protective gas such as inert gas flows from the outer pipe, and the mixture ratio of inert gas and reactive gas in the inner pipe is increased. A pressure control valve 6 button and a flow rate control valve 11 are arranged on the outer pipe of the gas blowing device in which the gas flow rate changes, and the flow rate control valve 11 is used to adjust the flow rate to maintain the outer pipe gas flow rate at a set flow rate. A total of 10 double pipe side flow rate control devices for refining.