JPS62151506A - Method for controlling throat pressure of converter exhaust gas treatment device - Google Patents

Abstract

PURPOSE:To stably control a throat pressure with high accuracy by calculating the disturbance quantity from the output of a converter throat detector and the input of the controlled variable of an exhaust gas flow rate control valve and adding the compensation quantity calculated in accordance therewith to the controlled variable. CONSTITUTION:A molten steel 2 is refined in a converter 1 having lance 3 and the throat pressure thereof is detected by a throat pressure detector 10 provided to a hood 5. The detected throat pressure output (y) is compared with a set throat pressure value (r) by a controller 11 and the controlled variable (u) of the exhaust gas flow rate control valve 7 disposed in a converter exhaust gas induction path having an induced draft fan 8 is calculated. The above-mentioned throat pressure is subjected to constant feedback control in accordance with the controlled variable (u). The disturbance quantity to the exhaust gas treatment process is calculated by an arithmetic processing unit 12 with the above-mentioned throat pressure output (y) and the controlled variable (u) as the arithmetic input and further the controlled variable DELTAu for the disturbance compensation is calculated in the above-mentioned method for controlling the throat pressure of a converter exhaust gas treatment device. Such controlled variable DELTAu for the disturbance compensation is added to the controlled variable (u) in an adder 13 and the above-mentioned control valve 7 is thereby controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for controlling the furnace port pressure in an exhaust gas treatment device for a converter such as an oxygen converter.

[Conventional technology]

The exhaust gas from this type of converter is useful as fuel, so it is collected in a gas holder etc. for reuse, but in order to stabilize the exhaust gas recovery rate,
It is necessary to suppress fluctuations in the furnace mouth pressure of the converter.

For this reason, in the past, as shown in Japanese Patent Publication No. 58-46527, for example, the furnace mouth pressure was detected, this detected value was compared with the set furnace mouth pressure, and the deviation was made to be zero. The furnace mouth pressure is maintained constant through feedback control.

[Problem that the invention seeks to solve]

However, although this conventional control method compensates for detection delays, signal transmission delays, damper operation delays, and measurement errors in the control system, it does not take into account compensation for disturbances added to the exhaust gas treatment process. However, there is a problem in that control accuracy inevitably deteriorates due to disturbances such as fluctuations in the amount of gas generated in the furnace, and stable and sufficiently accurate furnace mouth pressure control cannot be achieved.

In addition, a method has been proposed in which the amount of gas generated is predicted using a model (a set of mathematical formulas) inside the converter and the control valve for the exhaust gas flow rate is controlled, but this requires the creation of a highly accurate furnace interior model. Since it is practically difficult to model even the disturbance, the above-mentioned problem cannot be solved even with this method.

This invention was made to solve the above problem.
The object of the present invention is to obtain a furnace mouth pressure control method in a converter exhaust gas treatment device that can detect and compensate for disturbances added to the exhaust gas treatment process and control the furnace mouth pressure more stably and with higher precision than in the past.

[Means to solve the problem]

In order to achieve the above object, the present invention calculates the amount of disturbance added to the exhaust gas treatment process using the output of the furnace mouth pressure detector and the control amount of the flow rate control valve in the conventional feedback control system as calculation input, and then calculates the amount of disturbance applied to the exhaust gas treatment process. An arithmetic processing device is provided to calculate a disturbance compensation control amount based on the above, and the disturbance compensation control amount is added to the control amount.

[Embodiments of the invention]

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

In the figure, 1 is a converter, 2 is molten steel, 3 is a lance, 4 is a skirt, and 5 is a hood. 6 is a cooler, and 7 is an exhaust gas flow rate control valve (damper), which are disposed in an exhaust gas guide path including the hood 5. 8 is an induced blower, and 9 is an exhaust gas.

10 is a furnace mouth pressure detector, which measures the furnace pressure inside the hood 5, that is,
The furnace mouth pressure y of the converter l is detected and a furnace mouth pressure detection signal is sent. 1) is a controller for PI control or optimal control, which calculates the control amount (valve opening degree) U of the damper 6 from the set furnace mouth pressure r and the output y of the furnace mouth pressure detector 10, and generates a valve opening signal. Output. 12 is an arithmetic processing unit for disturbance compensation detection/compensation (
As shown in Fig. 2, the CPU has 1 for the controlled object behavior model block, 2 for the disturbance estimation block, and 3 for the disturbance compensation amount calculation block, and has a valve opening degree signal U and a furnace mouth pressure detection signal y. A disturbance compensation signal ΔU is created using the calculation input. 13 is an adder that adds the disturbance compensation signal ΔU and the valve opening degree signal U, and supplies the added value (U+ΔU) to the damper 7 as the valve opening degree control signal U.

In Fig. 2, P is the exhaust gas treatment process (hood 5-
It represents the transmission characteristic between the dampers 7, that is, (between the input point of the valve opening signal U and the furnace mouth pressure detection point), and δ represents the disturbance added to this exhaust gas treatment process.

The behavior X of the controlled object in this exhaust gas treatment process can be approximately described by the following equation of state.

(d/d t)X(t)=AX(t)+B(u)(t-
L) ・(1)y (t) = CX (t) + δ(
tl・ ・ ・ ・ ・ ・(2) Here, X (t)
is a vector of appropriate dimensions called a state variable, which may be a quantity that cannot be directly measured. t is time and L is dead time of the system.

A, B and C are constant matrices of appropriate size.

In the system expressed by the above equations (1) and (2),
The behavior of the controlled object It can be regarded as a disturbance in the system defined by Equation and Equation (2), and fluctuations in the amount of gas generated in the converter l correspond to this.

In this invention, the above disturbance δ(1) is calculated by the arithmetic processing unit 12.
This is estimated by calculation and compensated for.

The controlled object behavior model block has the same structure as the observer in modern control h■ theory, and uses the valve opening signal U and the reactor mouth pressure detection signal y as input, and the above-mentioned signal expressed by the transfer function P. It has a structure that simulates or estimates the behavior of a controlled object in an exhaust gas treatment process by calculation, and is designed so that the following formula holds true.

(d / d t ) Z(tl=h Z(tl +F
2y(t)+F3(ul(t-L)...
...(3) Here, Z (
t) is a vector with the same dimension as X (t) in the above equation (1), and Fl, F2, and F3 are the vectors in the above equation (1) and (2).
It is determined as follows based on the constant matrices A, B, and C of the equation.

(alFi = B (bl F + is a matrix fc in which the real part of the eigenvalue is negative) F
2 is a matrix that satisfies A-F YuC=F1, and Fl and F2
is not uniquely determined, but is appropriately selected within a range where both conditions (the above mountain) and (C1) are compatible.

In the disturbance estimation block, λ calculates the estimated amount of disturbance δ(1) from the behavior model Z (t) and the reactor mouth pressure detection signal y, and executes the calculation of the following equation (8).

Now, let us define the error vector between the behavior model Z (t) of the controlled object and the actual behavior, X (tl) of equation (1), as ε(t
) = X (tl −Z (t)・・・・・・・・・
When defined as (4), the following relationship holds true between the error ε and the disturbance δ in equation (2) above.

ε(S)=(S I Fl) F1a(S)...
...(5) Here, ε(S), δ (31 is ε
(tl, represents the Laplace transform of δft+.

On the other hand, from equation (2) above, the Laplace transform of y and X is expressed as y(
S), X (S), then Y (31= CX (S) + δ(S) = C(Z(S)
+ε(S))+δ(S)...(6) is obtained, and by substituting equation (5) into ε(31) of this equation, (I C(sl Fl)Fz) δ(s) =
y (sl-Cz (s)...(7) is obtained. Therefore, δ(1) is δ(s)=(y(sl-CZ(sl) x G(s
l・・・・・・(8) However, G(s)=1/(1-
C(s I −F+) Fyu) (9) It is given by: That is, in the disturbance estimation block, λ is the above (9
) has a transfer function G (81), and sends out the estimated value of the disturbance δ, that is, the estimated amount of disturbance η, as a signal.Equation (9) is based on the assumption that the real part of the constant matrix A is negative. It is possible when .

The disturbance compensation amount calculation block calculates a disturbance compensation control amount ΔU based on the estimated disturbance amount η and outputs it as a disturbance compensation signal (valve opening degree compensation signal). This ΔU is the above U and adder 1
3 is added.

The above-mentioned disturbance δ, disturbance amount estimated value η, and disturbance compensation amount ΔU hold the following relationship: η=-PΔU+δ・・・・・・・・・αψ Therefore, for example, ΔU is Proportional quantity, i.e. Δ
u = η, or proportionality of η + integral amount, that is, Δu =
Co (1+C+ (1/s)) is a constant.

In this example, the behavior of the controlled object to be feedback-controlled is simulated or estimated using the state equation using the input and output of nine exhaust gas treatment processes, and the disturbance value is detected based on the difference between this estimated value and the measured value of the furnace mouth pressure. Therefore, disturbances can be easily detected using simple means and their effects on the furnace mouth pressure can be compensated for with high accuracy.

FIG. 3 shows the furnace mouth pressure control characteristics (thick line) when the present invention is implemented in comparison with the furnace mouth pressure control characteristics (thin line) when the conventional method is used. As is clear from this figure, when the disturbance compensation according to the present invention is performed, the furnace mouth pressure fluctuation is greatly improved compared to the conventional method.

In addition, the transfer function of 2 in the disturbance amount estimation block in the above embodiment is as follows, when the DC gain in the above equation (9) is set as g.
It may be given as gα(S) (where α(S) is a transfer function with a DC gain of 1).

〔Effect of the invention〕

As explained above, this invention is configured to estimate the disturbance in the furnace mouth pressure control system by calculation and compensate for the influence of the disturbance on the furnace mouth pressure fluctuation. can be significantly improved compared to .

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention. FIG. 2 is a detailed block diagram of the arithmetic processing device in the above embodiment;
FIG. 3 is a diagram showing the furnace mouth pressure control characteristics. 1--Converter, 10-Furnace pressure detector, 1)-Controller, 12-Arithmetic processing unit, 13-Adder, K1--Controlled object behavior model block, K2--Disturbance amount estimation block, K3-disturbance compensation amount calculation block, P.-transfer function of exhaust gas treatment process.

Claims (2)

[Claims] (1) By comparing the output of the furnace mouth pressure detector that detects the furnace mouth pressure of the converter with the furnace mouth pressure set value, the control amount of the exhaust gas flow control valve installed in the converter exhaust gas induction path is calculated. In the furnace mouth pressure control method in a converter exhaust gas treatment device that performs feedback control to keep the furnace mouth pressure constant, the arithmetic processing device:
Using the output of the furnace mouth pressure detector and the control amount as calculation inputs, the amount of disturbance applied to the exhaust gas treatment process is calculated, and then a disturbance compensation control amount is calculated based on the disturbance amount, and this disturbance compensation control amount is A method for controlling furnace port pressure in a converter waste gas treatment device, characterized by adding the pressure to a control amount. (2) A controlled object behavior model block in which the arithmetic processing unit estimates the state within the exhaust gas treatment process by calculation using the output of the furnace mouth pressure detector and the control amount as input, and the output of the controlled object behavior model block is A patent characterized in that it has a disturbance estimation block that calculates an estimated amount of disturbance by comparing it with the output of a furnace mouth pressure detector, and a disturbance compensation amount calculation block that calculates a disturbance compensation control amount based on the estimated amount of disturbance. A furnace port pressure control method in a converter exhaust gas treatment apparatus according to claim 1.