JPS60197805A - Method for controlling pressure in converter of converter waste gas treating device - Google Patents

Abstract

PURPOSE:To decrease the pressure in a converter and to prevent the abnormal increase of said pressure by operating the converter while maintaining nearly the hermetic state between the port and skirt part thereof and increasing the sectional area of the route for recovering the waste gas when the pressure in the converter exceeds a prescribed value. CONSTITUTION:A molten iron 2 is subjected to blowing while the port of a converter 1 and the skit part 4 of the hood part 6 thereof are kept nearly hermetic. The waste gas generated by the blowing is sucked by an induced draft fan 11. The pressure in the converter is detected by a transmitter 5 and is controlled by using a control device 7 for the pressure in the converter which opens and closes the damper 9 in a secondary dust collector 82 by using an electro-hydraulic manoeuvering machine 10. The quick restoration of the normal gaseous pressure with a large increase in the pressure in the converter is executed by opening a shut-off valve S1 provided to a bypass duct 12 by a control device 13 for the bypass shut-off valve to increase substantially the sectional area of the flow passage for the waste gas thereby increasing the pressure in the converter when the detected pressure by the transmitter 5 exceeds a prescribed value.

Description

[Detailed Description of the Invention] [Technical field to which the invention pertains] This invention relates to a method for controlling the pressure inside a converter in a so-called converter waste gas processing apparatus, in which waste gas generated from a converter is subjected to predetermined treatment and recovered, and in particular to a converter pressure control method. The present invention relates to a method for controlling the pressure inside a furnace when the furnace is operated in a sealed or equivalent state between the furnace mouth and the hood (skirt) that guides waste gas generated from the converter.

[Prior art and its problems]

Generally, such converter waste gas treatment equipment is operated with a skirt located above the furnace mouth not in close contact with the furnace mouth, but with a predetermined gap. Therefore, even if the furnace internal pressure fluctuates as the operation progresses, air can flow into the furnace through the gap, or gas can flow out from the furnace to the outside, so the difference between the furnace internal pressure and atmospheric pressure is approximately Plus, minus number irises I
]20, which was well within the allowable range. However, in the operation of converter waste gas treatment equipment, especially during the recovery period of Co (-carbon oxide) gas, excluding the initial and final stages of blowing,
It is not necessarily appropriate to operate with such a gap. This is because when the furnace pressure is high, CO gas flows out through this gap, causing a loss of calories that could otherwise be recovered and causing environmental pollution, while when the furnace pressure is low, air flows through this gap. 02 (oxygen) gas and CO gas react to form C07 (
carbon dioxide) gas, resulting in valuable C
This is because O gas will be lost. By the way, conventionally, even if an attempt was made to bring the skirt and the furnace mouth into close contact, the slag blown out from the inside of the furnace during blowing would adhere to the furnace mouth in an uneven manner, so the skirt would not fit properly. However, recently, some suitable methods have been used to remove the slag, and the gap between the skirt and the furnace mouth is sealed or almost sealed. Attempts are being made to operate it. However, when operating under such conditions, pressure fluctuations occur in the furnace, and if this is added as a disturbance to the furnace pressure control system, the furnace internal pressure will increase, even temporarily, by several hundred degrees of H, O. varies widely over a range of At this time, if the internal pressure of the furnace changes significantly in the negative direction, areas with weak mechanical strength, such as the foot section that guides the waste gas, may dent and be damaged. Further, there is a risk that a seal may break in one gas seal device installed in the middle of a pipe (duct) for guiding waste gas, or excessive stress may be applied to the duct body, leading to damage to the device.

[Purpose of the invention]

This invention was made under these circumstances, and even when the converter waste gas treatment equipment is operated with the mouth and skirt of the converter sealed or in a substantially equivalent condition, safe operation can be achieved. The purpose of the present invention is to provide a method for controlling the pressure inside the reactor that makes it possible to protect the reactor pressure.

[Key points of the invention]

The main point is that the primary precipitator or secondary dust collector of the converter waste gas treatment equipment
Next, a duct is provided to bypass one side of the precipitator, and a shutoff valve is installed in the middle of the duct, and when the pressure inside the furnace exceeds a predetermined pressure, the shutoff valve is opened to substantially expand the cross-sectional area of the waste gas flow path. The key point is that the pressure inside the furnace is lowered by reducing the resistance. Further, this bypass duct is purged with N2 (nitrogen) gas at the start of blowing and at the end of blowing to perform explosion prevention control.

[Embodiments of the invention]

FIG. 1 is a block diagram showing a converter waste gas treatment apparatus for explaining the present invention in detail. In the figure, 1 is a converter;
2 is scrap and hot metal; 3 is a top blowing lance; 4 is a skirt; 5 is a furnace pressure transmitter; 6 is a hood; 7 is a furnace pressure control device; 8. ．． 8□ is the primary and secondary dust collector, 9 is the damper, 10
is an electrohydraulic control device, 11 is an induced blower, 12 is a bypass duct, 13 is a bypass shutoff valve control device, and 31 to S3 are shutoff valves. In this embodiment, the duct 12 that bypasses the secondary precipitator 8□ The feature is that it has been provided. First, a general method of operating a converter waste gas treatment device will be explained.

Scrap and hot metal 2 are charged as main raw materials into a converter l, and high pressure oxygen is blown into the converter using a lance 3 from the upper part of the converter to refine the hot metal into molten steel. This is called blowing. During blowing, oxygen combines with carbon in hot metal, forming Co (-carbon oxide)
Generates waste gas whose main component is gas. This waste gas has a high temperature of about 1200° C. and contains a large amount of iron oxide dust of about 150 g/N. Equipment that cools this high-temperature, high-humidity waste gas, removes dust, and collects it in a gas holder (not shown) is a so-called converter waste gas treatment device.

During blowing, the skirt 4, which can be raised and lowered up and down, is lowered close to the furnace, and the operation is performed with the gap between the furnace mouth and the skirt narrowed.Since this waste gas is high temperature, in order to protect the main body of the equipment, The hood part 6 is water-cooled by a water-cooled pipe.A primary dust collector 8I and a secondary dust collector 8□ are provided to remove dust from this waste gas.These dust collectors Since this method uses dust collecting water, the waste gas is rapidly cooled and the temperature drops to approximately 70°C.In order to remove dust from the waste gas, the two dust collectors 8.. Since it is necessary to pass the gas at high speed, each dust collector is equipped with a damper 9, which acts as a throttling mechanism.
It is carried out by The gas pressure at the furnace mouth, that is, the furnace pressure is detected by a furnace pressure detector 5, and controlled by opening and closing a damper 9 in a secondary precipitator using a furnace pressure control device 7.

Incidentally, as a driving device for this damper, a battery-operated control device 10 is normally used. The pressure inside the furnace is usually controlled to be close to atmospheric pressure, so that the amount of gas blown out from the gap between the furnace mouth and the skirt 4 and the amount of air sucked in are minimized. Usually, the gap between skirt 4 and furnace mouth is 2
If it is 00 dragon rank, the pressure inside the furnace is plus or minus several meters.
It is possible to control between HZ O(7). For example, the gas pressure at the inlet of the primary precipitator 81 is normally O to -50 mmHz.
and the gas pressure at the outlet is -300 to 8001111
It is HtO. The gas pressure at the inlet of the secondary precipitator 8□ is
Almost equal to the gas pressure at the outlet of the primary precipitator 81, -30
0 to -800+u H20, and the gas pressure at the outlet is -1500 to -2500 H20. On the other hand, if the skirt is lowered so that there is almost no gap between the furnace and the furnace mouth, in other words, if the furnace is operated in a closed state, the amplitude of vibration inside the furnace will increase, and in the event of an abnormality, it can be plus or minus several hundred dragons H20. For this reason, various measures have been taken to improve the controllability of the furnace internal pressure control device 7, but as mentioned above, if there is a very large disturbance, such as a sudden increase or decrease in the amount of gas generated in the furnace, , the furnace pressure increases or decreases rapidly. In order to quickly bring the gas pressure into a normal range when the furnace internal pressure increases, this embodiment provides a duct 12 that bypasses the secondary precipitator 8□, and a shutoff valve Sl is provided therein.

Here, the secondary dust collector 8. The control operation of the bypass duct cutoff valve S will be explained.

When the furnace pressure exceeds a certain value, for example, plus 40 wm H20, the shutoff valve SI in the bypass duct 12 is opened. As mentioned earlier, the pressure before and after the shutoff valve S1 is about 150
Since there is about 0 mm Ht 2 O, the gas easily flows when the shutoff valve is opened. As a result, the gas pressure in front of the secondary dust collector 8□ decreases, and the gas pressure in front of the primary dust collector 81 also decreases. Therefore, the pressure inside the furnace is reduced and an abnormally high pressure is prevented. In other words, by opening the bypass duct,
The cross-sectional area of the waste gas recovery path is substantially expanded to prevent abnormal increases in gas pressure. The bypass shutoff valve control device 13 determines the opening/closing timing of this shutoff valve.
However, the control device 13 opens the shutoff valve S when the pressure inside the furnace detected via the transmitter 5 exceeds, for example, plus 40 m@Hgo.

After opening, the shutoff valve is controlled so as to close when the pressure returns to plus 30m1H20. In addition, at the beginning or end of blowing, it is desirable to purge the inside of the duct before and after the shutoff valve S+ during this bypass with N2 gas to prevent explosion.

Although the case where the secondary dust collector is bypassed has been described above, it is also possible to bypass the primary dust collector 81. FIG. 2 is a block diagram showing such an embodiment, but since it is almost the same as the previous embodiment except for the position of the bypass duct, detailed explanation will be omitted.

〔Effect of the invention〕

According to this invention, since the bypass duct can compensate for the increase in the amount of gas generated in the furnace due to disturbance when the pressure inside the furnace increases abnormally, it is possible to bring about the effect that the gas pressure can be quickly restored. It is. Furthermore, by purging the bypass duct at the beginning and end of blowing, the safety of the plant can be fully guaranteed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a converter waste gas treatment apparatus for explaining the present invention in detail, and FIG. 2 is a block diagram showing another embodiment of the present invention. Symbol explanation■... Converter, 2... Scrap, hot metal, 3... Top blowing lance, 4... Skirt, 5... Furnace pressure transmitter,
6...Hood part, 7...Furnace internal pressure control device, 8I...
・Primary dust collector, 82... Secondary dust collector, 9... Damper, 10... Electro-hydraulic control machine, 11... Induced blower, 12
...Bypass duct, S+, S+'...Shutoff valve, 1
3... Bypass cutoff valve control device, S2. S3...N
2 Purge Shutoff Valve Agent Patent Attorney Akio Namiki Attorney Patent Attorney Kiyoshi Matsuzaki Figure 1 Figure 2

Claims (1)

[Claims] During blowing of a converter, the furnace internal pressure is monitored in a converter waste gas treatment equipment that is operated with the furnace mouth section and the hood section that guides the waste gas generated from the furnace closed closed or in a similar state. However, when the furnace internal pressure exceeds a predetermined value, the cross-sectional area of the path for collecting waste gas is substantially expanded. 1. A method for controlling furnace pressure in a converter waste gas treatment apparatus, characterized in that the furnace pressure is lowered by reducing the furnace pressure.