JPS6036611A - Bottom blowing gas changer for converter - Google Patents

Abstract

PURPOSE:To provide a bottom blowing gas changer which can prevent generation of a tuyere trouble and change in the quality of a steel by constituting said changer in which the bottom blowing gas of a bottom blown converter is changed to the required gas without increasing the pressure in a piping prior to exposure of the tuyere in the stage of tilting the converter when changing said gas. CONSTITUTION:The time (t) required until a tuyere 3 is completely exposed above a molten steel 2 according to tilting of a converter 1 is preliminarily determined. The magnitude of the capacity V of the piping from a shut-off valve 10 in the position near the tuyere provided to a piping 13 up to the tuyere 3 is limited in order to complete the blowing of the preceding gas G1 remaining in the piping 13 into the converter within the above-mentioned time (t) in the stage of changing the gas to be blown to the converter 1 (for example, in the stage of changing O2 to N2). More specifically the piping capacity V from the valve 10 to the tuyere 3 is made substantially small to shut off the piping with the valve 10 and to decrease the amt. of the gas G1 remaining in the piping part so that the complete releasing of the gas G1 into the converter 1 is finished within the time (t). As a result, the failure, cracking, etc. of the tuyere mushroom, brick, etc. are prevented and the life of the tuyere is extended.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for shortening the replacement time when switching the bottom blowing gas of a converter, controlling fluctuations in the in-line pressure, and extending the life of the liner.

In general, bottom-blowing converters are operated by changing the type and amount of blown gas according to the operating conditions at each stage, such as charging, blowing, sedation, demolition, slag, and suspension. , Z, whose state is illustrated by the conceptual diagram of FIG.

In FIG. 1, 1 is a converter, 2 is molten steel, the third trunnion core, and the fourth trunnion core. The switching operation is not interrupted, and the gas switching command is issued.5. Status command 6. The tilting angle change command 7f is executed as a starting point, and is placed on the valve stand 9 via the controller 8. Also, the shutoff valves 10, 10', and the control valve 11 are
, 11', check valves 12, 12', the shutoff valve 10
, 10' to the tuyere 3 by replacing the preceding gas G1 in the pipe 13 with the trailing gas G2. The time required to complete the replacement varies depending on the equipment layout and operating conditions of the converter, but is approximately 20 to 120 times. On the other hand, the tilting of converter 1 is.

For example, in the direction of arrow F, the relative position between point A on the surface edge of molten steel 2 and tuyere 3 changes until the molten steel surface crosses the four extreme points of tuyere 3, that is, in the converter. The time t required for the tuyere 3 to begin to be exposed from the molten copper 2 due to the inclination of 1
(see) tJ is determined by the tilting angle 0 and the tilting speed ν (rpm) until the tuyere begins to be exposed, but normally the tilting angle A is 1.0 to 2. Orpm, and the required time tl is less than 20''.

In Fig. 1, 15 and 15' are flowmeters, 16°16
'U: Original pressure gauge, 17 is the immediate pressure gauge.

As mentioned above, since the replacement time between the leading gas G1 and the trailing gas G2 is approximately 20 to 120 sOc, the converter 1 has already been
Even if the tuyeres 3 at the bottom of the furnace are exposed above the molten steel 2, the gas replacement is still in line n and the preceding gas 01 is being blown into the furnace. Become. Therefore, at the end of the tilting period, gas that should not be blown in will be blown in and the tuyeres 3 will be affected as shown in Table 1, causing problems with the tuyeres.

As an example, we will explain the case where the refining stage progresses to collapse/sedation and the tapping stage begins. 0□ which was blown into the inner pipe during the refining period
However, the trailing gas and +t* do not reach completion.
When the tuyere 3 is sawed out and exits the molten steel 2, the pine mushroom of the protective layer of the tuyere [] is eroded. -Also, since the heat load is large in the outer tube during the refining stage, a strong cooling gas is blown into it.However, when the furnace is tilted and the siding is exposed outside the molten steel 2, another pipe cracks due to rapid supercooling. occurs.

Also, depending on the replacement time of the gas type, changes in the [0] (N] [H] [0) components in the steel, changes in temperature, etc. as shown in Table 1, the quality of the sword may change. There will be an impact.

Table 1: Gas switching method vc 1. ,t, There is a flow rate confirmation method and a valve opening confirmation method, but even in the case of , for the first few seconds at the time of switching, the flow rate of the trailing gas is added to the flow rate of the leading gas, increasing the pressure inside the pipe. I will let you do it. To suppress this pressure rise, increase the piping capacity.
That would be fine, but then the replacement time mentioned above would become even longer.
Even if you switch using the pressure control, flow 4 control, specified opening, and Idun gas switch method, the FE force inside the converter increases, raising the siding pressure and causing pine mushroom scattering, siding brick cracks, etc. This makes it impractical.

The entire purpose of the present invention is to provide a bottom-blown gas switching device that can solve these problems and prevent the occurrence of surface problems and changes in steel quality. The capacity of the piping from the shutoff valve closest to the mouth to the siding is determined by the time required for the converter body to tilt from a vertical position to a tilted position where the siding begins to be exposed above the molten steel surface. This is a bottom-blown gas switching device in which the cutoff valve is disposed at a position where gas switching and replacement is completed at a capacity below, and a two-stage controlled dispersion device is provided in the piping.

The details are described below.

First, the time t required for the tuyere 3 to finish being exposed above the molten steel 2 as the converter 1 tilts is the converter equipment q) li
The size is determined by oneself based on the structural conditions determined by drawings, operational conditions such as furnace tilting speed, etc. Due to the nature of the converter, there are certain conditions that must be considered in advance.

Therefore, in the present invention, in order to complete the injection of the preceding gas remaining in the pipe connected to the second pipe into the furnace within the above-mentioned required time at the time of switching, a pipe is provided in the pipe immediately adjacent to the pipe. The size of the pipe volume iV from the cutoff valve 10 to the tuyere 3 was limited. That is, the piping capacity V from the shutoff valve to the pipe is made sufficiently small, the amount of preceding gas remaining in the piping section is reduced by connecting the shutoff valve with This enabled the remaining leading gas to be discharged into the converter.

In the device of the present invention, the cutoff valve 10 closest to the tuyere ff is placed as close as possible to the tuyere 3. Specifically, at the design stage, the gas flow rate Q, the piping capacity ■, and the inside of the piping are determined. The position of the shutoff valve is determined and arranged so that the balance with the required time t in relation to the gas pressure P is t) PV/Q.

However, the balance between piping capacity V and required time t is ・172
If the condition is satisfied/ζ1~[7, the leading gas and the trailing gas are still limited to 7. Also, given the time period, pressure -1-sealing occurs due to the pressure added tangential line, and the 5th wing is damaged. Noso 7
In the present invention, this pressure rise is eliminated by the two-stage relief valve IIζ.

For example, a discharge valve 14 between the siding and the shutoff valve shown in FIG.
, 14' were provided. The reason for providing two of these relief valves is
As shown in FIG. 3, the pressure is adjusted step by step. That is, in the valve opening confirmation switching method in column (■), when the iL transition command satisfies the maintenance of the specified opening flow rate of the leading gas 01, the shutoff valve 101 of the trailing gas pipe opens and the trailing gas G
2 flows into the pipe 13 and 7. Flow meter 15' and source pressure set 1 ensured that the flow rate and source pressure were maintained.
Confirmed at 6'n.

After that, the preceding gas cutoff valve 1() closes. If there is no relief valve, the pressure inside the pipe 13 between the teeth (immediate pressure fi-
1-17 (n)): As shown in 1■, the preceding gas O
Trailing gas 0□ rides on L and it rises step by step and then descends. In order to prevent pressure fluctuations as shown by (2), in the device of the present invention, one of the relief valves 14 is opened at the point (2) shown in FIG.
At point , the other relief valve 14' is also opened, and at point ■, the relief valve 14' is closed, and at point ■, the relief valve 14 is also closed. Therefore, the pressure changes as shown by ■. Jf on pressure
− can be prevented.

In the flow confirmation method in column (2), the same phenomenon as in method (2) occurs because the specified flow rate value of the trailing gas 0□ is checked [7] and the shut-off valve 10 of the leading gas 01 is closed.

In the illustrated example, two diffusion valves are installed, but as shown in Fig. 5, it is also possible to perform control with one diffusion valve 14''. , Select a dissipation valve that satisfies the requirements, and place the circumferential valve adjustment valve orifice chair 18 fully in the bottom of the dissipation valve 14'', so as to eliminate the groove that is used to dissipate air into the air. , even if it is izuka 2
It is necessary to use a dispersion device that controls the release in stages.

Next, a practical example of the present invention will be shown.

In the piping shown in Figure 2, the main piping from the shutoff valve 10 &-J150 A, length 18 m1, followed by 6 branch pipes branching in the direction of the panel! J, so 1 f' L80 A length 8
, m, 1 more feather! Diameter at tip: 18 stages, length: 1.81
There are six 11s, A, Jt, Sfl, -r. Therefore, the shutoff valve 10 was disposed at a position where the internal volume from the shutoff valve 10 of these pipes to the tip of the blade []3 was 0.425y+/.

In addition, as a two-stage dissipation valve, an electromagnetic opening/closing valve tongue is installed (7) at a position of approximately 6111° toward the direction of the shutoff valve 1o (13).

In this example, the tilting angle θU of the converter furnace body was 689 degrees, and the time required for tilting was 8.8 seconds.

In this example, no tuyere trouble or deterioration of steel quality occurred due to gas switching.

As described above, in a converter equipped with the device of the present invention, n is the pressure in the piping of 1 - 1 - 200 nm before exposure to the gas required during bottom-blowing gas switching in a bottom-blowing converter when the furnace is tilted. Since it is possible to switch λ without h, there is no negative impact such as damage or cracks on the siding pine mushrooms and bricks, and there is no backflow of molten steel into the tuyere, and the tuyere An extension is planned.

[Brief explanation of drawings]

Fig. 1 is a conceptual diagram of a conventional gas switching device; Fig. 2 is a conceptual diagram of a gas switching device according to the present invention; FIG. 4 is an explanatory diagram of the state of two-stage dissipation according to the present invention, and FIG. 5 is a conceptual diagram in the case of one dispersion valve according to the present invention. 1... Converter, 2... Molten steel, 3... Column, 10.1
0'...Shutoff valve (A, V), 11, 11''=control valve (CV), 12°12'...Check valve, 13...Piping, 14, 14', 14''...・Discharge valve, 15,
15'...flow meter, 16, 16'...original pressure gauge,
17... Immediate pressure gauge, 18... Adjustment pulp or orifice. Agent: Patent Attorney Masaaki Akizawa Mitsugai 2nd Nai IM Hsu 2nd

Claims (1)

[Claims] (1) The capacity of the piping from the shutoff valve closest to the siding to the siding is required to tilt the converter body from an upright position to a tilted position where the siding begins to be exposed above the molten steel surface. Type II, where gas switching and replacement can be completed in less than 1 hour
The valve is disposed at position K, and
A bottom-blown gas switching device for a converter, characterized in that it is equipped with a C2-stage control diffusion device.