JPS58204113A - Method for controlling recovery of waste gas from converter - Google Patents

Abstract

PURPOSE:To improve the recovery rate of a waste gas and to enable the dealing with the rapid generation of the waste gas in a non-combustion type treatment method for waste gas by controlling the flow rate of the waste gas and giving priority to control of the pressure in a converter mouth when the change in the pressure in the converter port exceeds a standard. CONSTITUTION:The waste gas in a converter 1 is recovered through a hood 3 and a flue 2. The value PV1 of the pressure in the converter port measured with a pressure gage P0 and the value PV2 of the flow rate measured with a flowmeter R2 are fed to an arithmetic controller 6. The concn. values of CO, CO2, O2 measured with a gas analyzer W1 are fed to a process control computer 11, and the target values SV1, SV2 of the pressure in the converter port and flow rate calculated therein are fed to the controller 6. A deviation (x) is determined from the equation, and the manipulated variable MV for controlling the recovery of the waste gas is determined for each of control zones A and B wherein the (x) is above the prescribed value and below said value, respectively. The opening and closing of a flue 2 are controlled by opening and closing a damper 7 in accordance with said variable. The control in accordance with the flow rate of the gas is thus accomplished normally, and when the pressure in the converter port changes abruptly, the control in accordance with the pressure in the converter port is accomplished. Therefore, the variation in the combustion of the waste gas is maintained lower as small as possible in the normal time and the control is capable of dealing with the abnormal blowing out of the waste gas.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for recovering converter exhaust gas using non-combustion type exhaust gas treatment equipment, which suppresses the combustion of exhaust gas as much as possible to improve the exhaust gas recovery rate and rapidly This paper proposes a method for controlling the yield of converter exhaust gas that can deal with the generation of exhaust gas.0 The exhaust gas that is often generated during converter blowing is mainly high-temperature CO gas containing fine iron oxide powder. The methods for completely treating this exhaust gas are roughly divided into combustion type and non-combustion type.The combustion type exhaust gas treatment method blows sufficient air necessary for the combustion of CO gas into the exhaust gas. This is a method in which the waste is combusted and the combustion heat is recovered as steam in a boiler.On the other hand, in the non-combustion type exhaust gas treatment method, a skirt is installed between the converter mouth and the flue, and the air from the E furnace mouth is collected. This is a method of collecting exhaust gas unburned while blocking intrusion.
With the recent increase in converter capacity, it is also necessary to increase the size of the exhaust gas treatment equipment, so non-combustion type exhaust gas treatment equipment, which requires a relatively small overall device, is mainly used for large converters. 0 ' Now, in the non-combustion type exhaust gas treatment method, it is required to suppress the combustion of exhaust gas at the furnace mouth as much as possible and recover exhaust gas with a high calorific value. Various converter exhaust gas recovery control methods have been proposed and implemented.

For example, the furnace mouth pressure is detected at the furnace hood, and based on the deviation between the detected value and a preset target value, a damper installed at an appropriate position in the flue leading to the converter is opened or closed. A method using so-called furnace mouth pressure control, which controls the furnace mouth pressure to a predetermined value, has been proposed.This method can be put into practical use by detecting the intake and blowout amounts of exhaust gas at the furnace mouth. This method is ideal for detecting abnormal blowing of exhaust gas and dealing with the problem. However, since the distance between the furnace mouth and the f'Lfc skirt provided above it changes due to the influence of the base metal adhering during blowing, the responsiveness of the furnace mouth pressure and its absolute value fluctuate. However, there is a drawback that the amount of exhaust gas burned at the furnace mouth varies widely. Furthermore, after the damper is opened and closed, the response of the furnace mouth pressure to the operation is delayed, so that a hunting phenomenon occurs in the old furnace pressure.

In addition, the generated gas flow rate is calculated from the blowing pattern and exhaust gas analysis values regarding the blowing 0□ gas flow rate, lance position, auxiliary material input amount, etc., and based on the results, the damper is opened and closed to adjust the exhaust gas flow rate to the target. A method using so-called exhaust gas flow rate control has also been proposed. This method has the advantage of controlling the exhaust gas flow rate in accordance with the generated gas flow rate, reducing variations in exhaust gas combustion at the furnace mouth, and increasing the exhaust gas recovery rate. However, it is impossible to predict sudden changes in the reaction inside the furnace, and it is not possible to perform controls that can deal with abnormal exhaust gas blowouts, which can lead to the generation of black smoke due to abnormal blowouts from the furnace mouth. There is a drawback.

Furthermore, an adaptive control method (pattern control method) in which the above-mentioned furnace mouth pressure control method or exhaust gas flow rate control method is appropriately selected and controlled depending on the steel type to be blown and the blowing time period.
has also been proposed, but even this method cannot eliminate the drawbacks mentioned above. The present invention eliminates the drawbacks of both of these methods and recovers exhaust gas by suppressing combustion of exhaust gas as much as possible. It is an object of the present invention to provide a converter exhaust gas recovery method that can improve the conversion rate and cope with sudden generation of exhaust gas.

The converter exhaust gas recovery method according to the present invention is a method for recovering converter exhaust gas using non-combustion type exhaust gas treatment equipment, in which the exhaust gas flow rate of the exhaust gas recovery system and the furnace mouth pressure of the converter are monitored, and the exhaust gas %- means that control is performed so that R1k is the target value, and when the furnace mouth pressure changes beyond a predetermined standard, priority is given to controlling the furnace mouth pressure.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on drawings showing its implementation state. FIG. 1 is a schematic diagram showing the state of implementation of the present invention method. 1 is a converter furnace, and the flow rate of hot metal charged into the snow is measured by a flow meter R0 by a lance 5 inserted from the furnace mouth 1a. This is a device for blowing by blowing O2 gas.

A flue 2 is provided so that the opening is located above the furnace mouth 1a of the converter 1, and a flue 2 is installed at the opening. , a skirt number is provided so as to be able to move in the vertical direction.The skirt number closes the furnace 501a of the converter l and allows air to flow from the furnace opening 1a into the converter 1 and the flue 2. Used to completely block the intrusion of r:
? nru. The hood 3 includes an upper hood 3a and a lower hood 3b.
The upper hood 3a is equipped with a pressure gauge P to measure the furnace mouth pressure.

is installed. Then, the furnace 50 pressure measurement value PV, t'L, measured by the pressure gauge P, is transmitted to the arithmetic controller 6 consisting of a microcomputer.
The converter exhaust gas generated from the converter l is cooled in the radiation section 2a, and then subjected to dust treatment in the primary dust collector 2b and secondary dust collector 2C installed next. After going,
The converter exhaust gas is sucked by an induced exhaust fan 2d and a booster fan 2e and guided to the flue end 2f, and the converter exhaust gas is stored in a gas holder (not shown) via a recovery valve 9. When not being collected, exhaust gas that poses no risk of air pollution is discharged into the atmosphere through the chimney 10. 0 A pressure gauge P is installed in the radiant cap 2a, a gas analyzer Q1 is installed in the converter l measurement at the installation position of the primary dust collector 2b, and a gas analyzer Q1 is installed in the secondary dust collector 2.
From the above, a pressure gauge P2 is installed on the converter L side at the 0 installation position.
2 (There is a pressure gauge pst on the converter 1 side at the 1 installation position, and a pressure gauge P4 on the chimney 10 side at the booster fan 28 installation position.
These are used to obtain maintenance management information.

Furthermore, a flow meter R2 is attached to the flue end 2f, and information regarding the measured exhaust gas flow rate pv is corrected by the temperature and pressure corrector 12, and then calculated. It is transmitted to the controller 6.

The gas analyzer Q1 measures CO gas, CO, and gas in exhaust gas.

The concentration of the 0□ gas is measured, and information regarding these concentration measurements is transmitted to the process control computer 11. The flow meter R is connected to the process control computer 1.
02 Gas flow rate for blowing measured by 1, the flow meter R
Information regarding the exhaust gas flow rate measured by 2 and information regarding the input amount of auxiliary raw materials are also transmitted. Then, the process control computer 11 calculates the optimal conditions for the exhaust gas flow rate or the furnace mouth pressure at regular intervals based on these, and uses the results as the furnace mouth pressure target value SV1 or the exhaust gas flow rate target value SV for calculation control. The data is transmitted to device 6.

The arithmetic controller 6 calculates the deviation xf between the furnace mouth pressure measurement value pv1 and its target value SV1 using the following formula fl1.

x=PVl-SVI.-fll Based on the equation, the control variable MV for performing control zone division and exhaust gas recovery control for each control zone is determined, as will be described in detail later. A signal regarding the manipulated variable MV thus determined is transmitted to the hydraulic control section. The hydraulic control section 8
Is a damper installed at the installation position of the secondary dust collector 2c in the flue 2? This is for operating the hydraulic cylinder 8a to open and close the flue 2. The hydraulic cylinder 8a is operated based on the signal related to the operation amount MV, and its linear movement opens and closes the damper 7, thereby fully controlling the opening and closing of the flue 2. let

Next, the arithmetic processing in the arithmetic controller 6 will be explained in detail based on FIG. 2, which shows a flowchart thereof. First, the furnace pressure measurement value pv1. Analog data such as the furnace mouth pressure target value SV'1 and the exhaust gas flow rate measurement value pv2 are read and digital filtering is performed on these data. This digital filtering is performed, for example, by calculation as shown in equation (2) below.

Yn”=P”fp’-1+(1’P)In”
f121 However, Yn: Data after filtering xn: Data before filtering □ P: F, 7 coefficients (1/32 to 3□/32)・
1 Using the data f' digitized in this way, the deviation xf of the furnace outlet pressure is determined by the formula fi1, and the control zone is determined based on the deviation X. That is, when the deviation X is greater than or equal to a predetermined value (for example, when
In the case of fAq. (including negative values) are determined to be in the B zone.

When this control zone is the A zone, control is performed using the furnace mouth pressure, and the parameters xPi, Kpi, KDi (however, 1=1
)? is used to calculate the control amount mk. For example, by calculating the following equation (3), the control amount mk'jz can be calculated.
...(3) However, in θ, the difference between the two target values and the measured value (current = 2nd digit) θh-x: the previous data in θ Δt: control period (for example, 200 m5ec) KPi,
K Engineering 1sKDi*Dogs - Proportional control/integral control 1 Differential control parameters (t=1.Z...) Pvk: Furnace pressure measurement value (current = 2nd data) PVk-1: Pvk once Previous data Pvk-2: Data two times before Pvk Further, using this control amount mk, the manipulated variable MV is determined by the following equation (4).

MV = MVo+ mk-f41 However, MV. : Manipulated amount before control On the other hand, when the control zone is the B zone, control is performed based on the exhaust gas flow rate, and the parameters KPi, KIi are determined from P based on the exhaust gas flow rate control.

Using Kni (1=2), calculate the control amount mk”k,
Using this control 1m1(', the manipulated variable MV is determined by the following equation (5).

MV = MV(1-mk'-(5)
The manipulated variable MVi obtained in this way is continuously outputted while the converter operation is in progress.If the deviation X is particularly small (in actual operation, f'L is managed by the flow rate,
For example, at -30ONm'/H (in the case of X (30ONm/)!), the control amount mk/ is assumed to be zero as a dead zone.
゛No, the damper 7 will not be opened or closed.

When converter exhaust gas is recovered using equipment configured as described above, control is normally performed using the exhaust gas flow rate, and if the furnace mouth pressure changes rapidly, control is performed using the furnace mouth pressure. Therefore, normally, by controlling the flue gas flow rate, it is possible to keep the variation in flue gas combustion at the furnace mouth as small as possible and improve the exhaust gas recovery rate.In addition, when the furnace mouth pressure suddenly changes, it is possible to automatically switch to the furnace mouth pressure control. It is possible to deal with abnormal blowing of exhaust gas by switching the

Next, an example of the method of the present invention will be described.0 Exhaust gas generated from a small converter that melts a wide range of steels from low carbon steel to high carbon steel using non-combustion exhaust gas treatment equipment is recovered. The recovery rate was measured. When the theoretical exhaust gas recovery rate is assumed to be 100%, the exhaust gas recovery rate was 90.8% in the conventional method using only furnace mouth pressure control.
In the method of the present invention, the exhaust gas recovery rate was improved to 92.8%, and no accidents such as black smoke caused by abnormal exhaust gas blowout occurred. In this way, the advantages of the method of the present invention
The police were able to confirm the effect in an actual reactor.

As described in detail above, when performing recovery control of converter exhaust gas using non-combustion type exhaust gas treatment equipment, the present invention normally performs all exhaust gas flow rate control, and only when the furnace mouth pressure changes suddenly Since the mouth pressure is controlled, combustion of exhaust gas is suppressed as much as possible to improve the exhaust gas recovery rate, and it is also possible to deal with sudden generation of exhaust gas. Therefore, the present invention provides an extremely elegant method for efficiently recovering exhaust gas during converter operation, and for promoting automation while avoiding accidents caused by abnormal blowing of exhaust gas. .

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the implementation state of the method of the present invention, and FIG. 2 is a flowchart when the arithmetic processing according to the present invention is performed in an arithmetic controller. l... Converter 2... Flue 3... Hood 4...
・Skirt 5... Lance 6... Arithmetic controller 7.
...Damper 11...Process control computer P. ...Pressure gauge Q1...Gas analyzer R,,,R2,...
・Flow rate discussion patent applicant Sumitomo Metal Industries Co., Ltd. Agent Patent attorney Noboru Kono 2

Claims (1)

[Claims] 1. In a method of recovering converter exhaust gas using non-combustion type exhaust gas treatment equipment, the exhaust gas flow rate of the exhaust gas recovery system and the furnace mouth pressure of the converter are monitored, and the exhaust gas flow rate is mainly controlled to be the target value, 1. A converter exhaust gas recovery control method, characterized in that when the furnace mouth pressure changes beyond a predetermined standard, priority is given to controlling the furnace mouth pressure.