JPS6173809A - Device for controlling pressure in converter of converter waste gas treating device - Google Patents

Abstract

PURPOSE:To control adequately the pressure of a converter waste gas in a device for recording and treating said waste gas by detecting the pressure in the converter with a detector consisting of plural oscillators according to the fluctuation of the gaseous pressure in the converter and adjusting the damper of a secondary dust collector. CONSTITUTION:The raw material 2 such as molten iron in the converter 1 is refined by top blowing of pure oxygen from a top blowing lance 3. The high-temp. waste gas contg. CO and iron oxide dust is generated in this stage and is recovered by a hood 6. The dust is recovered in a primary dust collector 9 and the secondary dust collector 10. The CO-contg. waste gas is fed by an induced draft fan 13 to a CO utilizing device. The gaseous pressure in the converter is considerably fluctuated by the degree of hermetic sealing between the lower skirt 4 of the hood 6 and the converter outlet and therefore said pressure is detected by plural oscillators 5-1-5-n having different ranges and is fed to a control device 7 for the pressure in the converter. The opening degree of the damper 11 of the collector 10 is controlled by an electro- hydraulic controller 12 in accordance with the command from the device 7 to control the gaseous pressure in the converter to an adequate value, by which the converter operation is stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to a furnace pressure control device in a converter waste gas treatment device.

[Prior art and its problems]

Conventional converter waste gas treatment equipment operates without bringing the skirt located above the furnace mouth into close contact with the furnace mouth. Therefore, the furnace pressure is approximately positive.

It is in the range of minus number + uHzO (water column), and the range of furnace pressure control there is plus and minus 20 mm.
This is done at about HzO. However, when operating with the skirt lowered and the furnace mouth in close contact or close to it, the furnace pressure increases to over 100 mmHzO, which leaves the problem that conventional control ranges alone cannot control the furnace pressure. ing.

[Purpose of the invention]

The present invention has been made in view of this point, and an object of the present invention is to improve the performance by controlling the control range by switching the control range depending on the operating state.

[Key points of the invention]

This invention provides a converter waste gas treatment system in which a desired one is selected from among a plurality of different range transmitters and a plurality of control gains depending on the range of furnace pressure to be controlled. By controlling the furnace pressure,
The control performance is improved.

[Embodiments of the invention]

FIG. 1 is a block diagram showing an embodiment of the present invention.

In the figure, 1 is a converter, 2 is hot metal and scrap,
3 is upper blowing lance, 4 is skirt, 5 (5-1 to 5-n
) is a furnace pressure transmitter, 6 is a hood, 7 is a furnace pressure control device, 8 is an upper safety valve, 9 is a primary dust collector, 10 is a secondary dust collector, 11 is a damper, 12 is an electro-hydraulic control device , 13 is an induced blower.

Scrap and hot metal 2 are charged as main raw materials into a converter 1, 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 the hot metal to generate waste gas mainly composed of CO 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/Nm 3 . Moreover, since this waste gas is at a high temperature, the hood section 6 is water-cooled with a water-cooled pipe to protect the main body of the apparatus. A primary dust collector 9 and a secondary dust collector 10 are provided to remove dust from this waste gas. Since these dust collectors use dust collecting water, the waste gas is rapidly cooled down to a temperature of about 70°C. In order to remove dust from the waste gas, it is necessary to pass the gas through the two dust collectors mentioned above at high speed, and each dust collector 9, 10 is equipped with a damper 11, which serves as a throttling mechanism. . Further, gas suction is performed by an induced fan 13.

The gas pressure at the furnace mouth is called the furnace pressure, and the furnace pressure detector 5
and is controlled by moving the damper 11 in the secondary precipitator 10 using the furnace internal pressure control device 7. Incidentally, a battery-operated control device 12 is normally used as a drive device for this damper.

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. Normally, if the gap between the skirt 4 and the furnace mouth is about 200n, the furnace pressure will be controlled between plus and minus numbers +n Hz 00, and the range of the control system will be between plus and minus 20 tm H.
It is about zo. However, when the skirt 4 is lowered to its lowest limit, there is almost no gap at the furnace mouth, and when operating in such a closed condition, the fluctuations in furnace pressure become large and positive.

Exceeds minus 100maH,O. The operation of a converter is like that of a converter, and the height of the skirt 4 is not constant during one operation (1 charge), and the fluctuation range of the furnace pressure also changes. Furnace pressure control in such operations is difficult because the control range is too wide for one range. Therefore, in the present invention, a plurality of control systems are provided and the control systems are switched depending on the operating state to improve controllability. That is, in the furnace pressure control system as described above, the process gain varies greatly depending on the effective distance between the skirt 4 and the furnace opening.

Due to this variation in process gain, the range of variation in furnace pressure changes even for the same disturbance, and the greater the process gain, the larger the range of variation in furnace pressure. Furthermore, when the process gain becomes large, it is necessary to reduce the control gain in order to maintain the same controllability in the same control system. The key point of this method is to select a plurality of detection ends and control gains in accordance with the process gain to improve controllability. This point will be explained below.

Figure 2 is a block diagram showing a specific example of the reactor pressure control device;
The figure is a flowchart for explaining the operation.

In FIG. 2, 7 is a regulator 71 gain adjustment F, 72 .
721, a changeover switch SW, etc., the regulator 71 is a well-known PID regulator that performs proportional, integral, and differential control calculations, and gain regulators 721 to 72. , for example, makes the gain of the proportional amplifier, which constitutes the cough regulator 71, variable. 14 is a process gain detection device, for example, the skirt 4 shown in FIG. 1 detects the gain of the process (waste gas treatment device) from the effective distance from the furnace mouth. Further, based on the output from the process gain detection device 14, the control device 7 selects a desired one of the transmitters 5-1 to 5-n and the gain adjusters 72□ to 72 via the switch SW.

Therefore, if the process gain of the furnace pressure control system is classified into 1 to n depending on its range, n transmitters and gain adjusters are provided correspondingly. For example, if the process gain is "l", the oscillator is set to 5-1, and the control gain adjuster is set to 72.
By making 1 correspond to...
Depending on the magnitude of the process gain detected via the detection device 14, switching between n types of oscillators and control gains is performed.

Note that if only the process gain is detected, the fluctuation range of the furnace pressure will vary depending on the state of the control system at that time, and may exceed the range (operating range) of the detection end (transmitter).

Therefore, as a condition for switching to prevent this, the furnace pressure fluctuation is within the range to be switched, and if it is within that range, switching is performed. . In other words, as shown in Figure 3, ■
Determine whether the process gain is 1″ at
If YES, judge whether the furnace pressure fluctuation is within range "1" as shown in ◎.
If YES, first, as in ■, the detection end (transmitter) 5-1
and control gain (gain adjuster) 72.

Note that this is done in exactly the same way when the process gain is "2" or more.

〔Effect of the invention〕

According to this invention, each one of the plurality of furnace pressure transmitters and the plurality of control gains is appropriately selected and controlled according to the operating state of the process (converter waste gas treatment equipment). This provides the advantage of enabling good control over a wide range.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing a specific example of a reactor pressure control device, and FIG. 3 is a flow chart for explaining its operation. Code explanation 1... Converter, 2... Hot metal and scrap, 3...
・Upskirt lance, 4...Skirt, 5 (5-1 to 5-n
)...furnace pressure transmitter, 6...hood section, 7...furnace pressure control device, 8...upper safety valve, 9...primary dust collector, 1o...secondary dust collector Container, 11...Damper, 12.
... Electrohydraulic control machine, 13 ... Induced blower, 14 ... Process gain detection device, 71 ... Adjuster, 72. ~7
2. ．． ...Gain adjuster.

Claims (1)

[Claims] In a converter waste gas treatment system that collects and processes waste gas from a converter by keeping the converter mouth and skirt sealed or in a substantially equivalent state, a plurality of A furnace pressure detection means, a process gain detection means for detecting a process gain from at least an effective distance between the skirt and the furnace mouth, and an adjustment means capable of changing the gain of the control operation according to the magnitude of the gain are provided. 1. A furnace pressure control device for a converter waste gas processing apparatus, characterized in that the furnace pressure is controlled by selecting a furnace pressure detection means and a predetermined control gain according to a detected process gain.