JPS59211518A - Controlling method of cnverter waste gas - Google Patents

Abstract

PURPOSE:To prevent blowing out of gas from a converter port owing to a sharp increase in the amt. of the gas generated during charging of an auxiliary raw material by controlling an R damper in accordance with the increased amt. of said gas and the predicted value of a delay in reaction time in the treatment of converter waste gas. CONSTITUTION:An increased amt. DELTAF of generated gas and a delay in reaction time T1 are actually measured for each charging degree V(T/H) of the auxiliary raw material to be charged during refining, and the respective relations are obtd. as shown in the figure. Prescribed equations are obtd. with DELTAF, T1 and reaction time T2 from said relations and it is predicted by using these equations that the sharp increase in the generated gas begins after T1 time since the auxiliary raw material is charged and that the gas of DELTAF increases after T2 time. The DELTAF is converted to the opening of the R damper to be increased and the R damper is controlled according to the flow rate of the waste gas-the opening of the R damper characteristic. The automatic control of the R damper with good follow-up is thus made possible with a sharp increase in the amt. of the gas produced when the auxiliary raw material is charged.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the time from the start of the introduction of auxiliary raw materials to the start of reaction, which are introduced into the converters at arbitrary timing during refining, and the gas generated by the reaction in the furnace in converter exhaust gas treatment. This invention relates to converter exhaust gas control in which the amount and rate of increase in generated gas are predicted and exhaust gas control is performed based on the prediction.

First, with reference to FIG. 1, the basic configuration of conventional converter exhaust gas treatment will be explained. In Figure 1, 1 is a converter, 2 is a skirt that can vibrate up and down, and 3
is a hood, 4 is an R damper, 5 is a suction damper, 6 is a gas induced fan (IDF), 7 is molten steel, 8 is oxygen blown into the furnace, and 9 is a furnace.

Internally generated gas, IO is a furnace mouth pressure gauge, 11 is a skirt position detector, 12 is a gas analyzer, 13 is an induced gas flow meter, 14
is air, 15 is computer, 16 is PID controller, 17 is R
A damper driving device, 18 a predictive control unit, 19 an adder, and 20 an auxiliary raw material input signal detector.

The molten steel 7 in the converter 1 is refined by blowing oxygen 8 into it, but at that time, a large amount of exhaust gas (mainly Co gas) 9 is generated.
occurs. In order to process this exhaust gas 9 in a non-combustible state, the scars 1 and 2 are lowered during blowing, and the pressure gauge 10
．． Skirt position detector 11° gas analyzer 12. By controlling the opening degree of the R damper 4 using the various methods described below based on the information on the induced gas flow rate side 13, etc., the air 1
4 suppresses the combustion of Co gas as much as possible. A conventional exhaust gas control method will be explained below.

(1) Constant value control of furnace mouth pressure - m - In this method, the R damper 4 is controlled so that the furnace mouth pressure detected by the furnace mouth pressure gauge IO becomes a constant value.

(2) Control of the amount of air blown into the furnace mouth - m - This method uses the furnace mouth pressure gauge 10. The skirt position detector 11 and the converter gas analyzer 12 calculate the furnace intake air amount 14 sucked from between the converter 4 ports and the skirt 2 using a model formula in the calculator 15, and calculate the furnace entrance suction air amount. 14 is a constant value.

(3) Control of gas generated in the furnace - m - This method uses a model formula in the computer 15 to control the amount of oxygen 8 brought into the furnace from lances, auxiliary raw materials, etc. and the oxygen 8 taken out of the furnace determined by the converter gas analyzer 12. The amount of oxygen remaining in the furnace is calculated from the difference between the amount of oxygen generated in the furnace, the amount of gas generated in the furnace is estimated from the amount of oxygen, and the R damper 4 is controlled with respect to the amount of gas generated in the furnace. .

All of these conventional technologies use instrumentation or computer-based PI.
Using the D controller 16, PID calculation is performed within the controller so that each measured value (furnace mouth pressure, furnace mouth suction air amount, and furnace gas amount) becomes equal to each set value. The calculation result is sent as a control signal to the R damper drive device 1, which is the operating section.
Sent to 7.

In this way, conventional control is a feedback control that performs comparison calculations between each measured value (actual value) and a set value, but it cannot cope with the sudden increase in the amount of gas generated when adding auxiliary materials, and the gas from the furnace mouth is The blowout phenomenon was unavoidable.

An object of the present invention is to improve the ability of the R damper to follow the sudden increase in the amount of gas generated when auxiliary materials are introduced, and to prevent gas from blowing out from the furnace mouth.

In the present invention, the amount of increased gas generated and the reaction delay time are predicted from the degree of input of auxiliary materials to the M line in converter exhaust gas treatment, and the damper is controlled based on these predicted values. or,
At this time, the damper opening degree control is performed by direct control output to the adder 19 provided at the rear stage of the PID controller section, without going through the conventionally used instrumentation or computer-based PID controller section 16. The ability of the R damper 4 to follow the rapid increase in gas generated when raw materials are charged is improved, and gas blowing out from the furnace mouth is prevented.

The following is a method for predicting the amount of gas generated when adding auxiliary raw materials according to the present invention. A method of controlling I results will be explained.

First, a method for predicting an increase in the amount of generated gas when auxiliary raw materials are introduced will be explained with reference to FIGS. 2, 3, and 4.

In FIG. 2, the vertical axis represents the exhaust gas flow rate, and the horizontal axis represents time. tl is the timing of auxiliary raw material input, t2 is the timing at which the generated gas rapidly increases due to the reaction in the furnace, t3 is the timing at which the rapid increase in generated gas ends (90% completion), Fo is the exhaust gas meteor before the auxiliary raw material input, Fl indicates the exhaust gas flow rate when 90% of the rapid increase in generated gas is completed.

Here, ('12 tl) is the reaction delay I + @T15e
c, (t3 t2) is the reaction time T2sec, (Ft
3 and 4 are obtained by actually measuring the auxiliary raw material input degree vT/H, which is directly linked to the control amount, with Fo) as the generated gas increase amount ΔF Nm3/H. In Figure 3, the horizontal axis is the amount of auxiliary material input V T/H1, and the vertical axis is the amount of increase in generated gas ΔF
Nm'/H.

In FIG. 4, the horizontal axis is the auxiliary material input degree VT/H1, and the vertical axis is the reaction delay time and reaction time.

From FIGS. 3 and 4 above, the amount of increase in generated gas ΔF,
The following regression equation is obtained for the reaction delay time T1 and the reaction time T2.

ΔF = a ・V + a (α>O, a>ONm'
/lt...(1) T1=β-V+b (β<O,
b>O) 5Qc-・(2)T2=γ・V+c
(y<0.c)0) 5ee-=(3)■=Auxiliary raw material input degree T/H α, β, γ: Coefficients a, b, c: Constant auxiliary raw material input start and input degree signals are detected by a signal detector 20 in real time, input it to the predictive control section ]8, and perform the above (
Using equations 1) to (3), the amount of generated gas starts to increase rapidly at time t2, 11 seconds after time t1, and then ΔF increases for 12 seconds.
It is predicted that the amount of gas will increase.

Next, a control method for the prediction results will be explained using FIGS. 1 to 5 and equations (1) to (3).

First, the increase amount ΔF of the generated gas shown in FIG. 2 is determined by equation (1), and then ΔF is converted into the increase in the opening degree of the R damper 4 shown in FIG. At this time, as shown in Fig. 5, the flow rate-damper characteristic is non-linear and also changes depending on the opening degree of the suction damper 5 on the iDF inlet side. ) Calculate the increase in damper opening using the formula.

80 = ΔF (θ./FO) (4) Δθ:
Incremental damper opening degree θ0: Damper opening degree at time t2 Fo: Exhaust gas flow rate at time 12
Nm3/HΔF=Increase in generated gas due to input of auxiliary material Nm3/H θo/Fo in equation (4) represents the flow rate-damper characteristic at time 12, and this gives an approximate conversion coefficient between flow rate and damper opening. automatically becomes variable. Therefore, the flow rate-damper characteristic is non-linear and changes automatically depending on the opening degree of the suction damper 5 on the IDF inlet side.

Next, the damper opening degree increment Δθ determined by equation (4) is divided into N parts and output within a reaction time of 12 seconds, as shown by the broken line in FIG. At this time, a direct control output is provided to the adder 19 provided at the subsequent stage of the PID controller section 16 in FIG. 1, and the R damper 4 is controlled via the damper drive device 17.

As described above, by controlling the converter exhaust gas according to the present invention, a phenomenon that conventionally occurred where gas was blown out from the four ports of the converter when the amount of gas generated when auxiliary materials were inputted suddenly increased.
This can be prevented and the amount of gas recovered can be increased.

[Brief explanation of drawings]

Figure 1 is a schematic diagram showing an example of converter exhaust gas treatment equipment, Figure 2
The figure is a graph showing the characteristics of the amount of gas generated depending on the input auxiliary raw materials.
Figures 3 and 4 are actual measurement days. FIG. 5 is a graph showing the relationship among the auxiliary raw material input rate, the amount of gas generated, the reaction delay time, and the reaction time obtained from the above, and FIG. 5 is a graph showing the flow rate-damper characteristic. ■ = Converter 2 Nisker 1-3: Hood 4: R damper 5: Suction damper 6: Gas induced blower 7: Molten steel 8: Oxygen sucked into the furnace 9: Gas generated in the furnace 10: Furnace mouth pressure gauge 11 Nisker 1-position Detector 12: Converter gas analyzer 13 = Induced gas flow meter 14: Air
15: Computer 16: PID adjuster 17: R damper drive device 18: Predictive control unit 19: Adder 20: Sub-material input signal 2■ Fall 4 Waha 3V Foil 5F Oki force ゛ Sono 1

Claims (1)

[Claims] In converter exhaust gas treatment, the increase in generated gas and the reaction delay time from the time of input are predicted from the input degree V (T/H) of auxiliary materials input during refining, and the damper is controlled based on this predicted value. A method for controlling converter exhaust gas, characterized by: