JPH0149770B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) This specification describes a method for controlling the opening speed of a large bell at the top of a blast furnace for charging raw materials into a blast furnace. This paper describes the results of research and development of large bell opening speed control to adjust it according to the situation.

In general, the control of the distribution of raw materials in the blast furnace varies depending on the raw material properties and the amount of raw material charged, and is necessary to appropriately maintain stable gas composition distribution and temperature distribution (hereinafter collectively referred to as gas distribution) in the blast furnace. For example, if the gas flow at the center of the furnace is strong, the excessive gas flow at the center can be suppressed by charging ore toward the center of the furnace or by charging coke toward the furnace wall. Therefore, in a bell-type blast furnace, the movable armor notch and stock line are adjusted.

If the layer thickness distribution of coke and ore in the radial direction inside the furnace is appropriately managed through this adjustment, it becomes possible to improve the blast furnace gas utilization rate and operate at a low fuel ratio. However, it is difficult to finely adjust the appropriate charge distribution only by adjusting the movable armor notch and stock line, which are limited methods for adjusting the charge distribution in a bell type blast furnace. In other words, in a bell-type blast furnace, the charged material is discharged from the bell all at once, making it difficult to properly charge the ore in the radial direction within the furnace. Because they fall in the same position,
The drawback was that the gas distribution could not be finely adjusted.

Recently, as a means to eliminate these drawbacks, the charging amount and charging position of raw materials are controlled by adjusting the bell opening degree or bell opening speed. Control methods have been developed to improve the improper distribution of the charge in the furnace and to adjust the proper distribution of the charge in the radial direction within the furnace, and thus the gas distribution.

(Prior art) Unexamined Japanese Patent Publication No. 1983-1981- Regarding the control of gas distribution in a blast furnace
Publication No. 9109 states that when the bell opening is small, the raw material accumulates more toward the furnace core, when the bell opening is large, the raw material accumulates more toward the furnace wall, and when the bell opening speed is slow, the raw material accumulates closer to the furnace core. The amount of material to be charged is adjusted by adjusting the bell opening degree or opening speed based on the general tendency when charging raw materials: more material is deposited near the furnace core, and when the bell opening speed is fast, more material is deposited on the furnace wall side. A technique has been disclosed for controlling the distribution of gas in the furnace by optimizing the distribution of gas in the furnace.

(Problems to be Solved by the Invention) In the above control method, since the bell opening degree or opening speed is adjusted by hydraulic drive, the following problems (a) to (c) arise.

(a) The bell opening speed is always controlled at a variable speed based on the gas distribution state in the furnace, but it requires difficult technology to follow this control with hydraulic drive.

(b) Changes in the temperature, viscosity, and turbidity of oil in the hydraulic drive system, changes in the properties (particle size, weight, type, and mixing ratio) of the raw material on the bell, or changes in weight due to discharge of raw materials from the bell; As a result, the actual bell opening speed does not match the setting, making it difficult to strictly control the gas distribution in the furnace.

(c) The opening degree and opening speed of the bell are subject to frequent changes, and the operating time is short, so they must be controlled instantaneously, which is a severe condition.

This invention subdivides the opening-time characteristic curve of the large bell along the time axis, and performs strict speed management and correction control within each segment, thereby improving hydraulic pressure, which was previously considered difficult. The purpose of this invention is to enable opening speed control using a circuit, and to perform highly accurate and simple large bell opening speed control.

(Means for Solving the Problems) This invention provides a large bell opening-time characteristic curve along the time axis that brings about optimal operation by charging raw materials according to the composition distribution or temperature distribution of the gas in the blast furnace. In order to control the opening speed of the large bell to a constant speed that approximates the curve within each segment, the opening degree reached by the large bell at each time point corresponding to each of the above-mentioned division points is sequentially detected, The blast furnace is characterized in that the opening speed of the large bell is controlled to be approximated by a polygonal line to the opening-time characteristic curve by performing correction control by comparing the openings of division points on the degree-time characteristic curve. This is a method for controlling the opening speed of the large bell at the top of the furnace.

Further, the present invention will be specifically explained based on FIG. 1, which schematically shows a cross section of the top of a blast furnace.

First, the construction of the top of the furnace will be described. A large bell 2 located below a small bell 1 is driven by a hydraulic cylinder 6 via a bell rod 3 and a segment 4 under balance adjustment of a counterweight 5. This hydraulic cylinder 6 is driven up and down by pressure oil from a hydraulic unit 7 and by switching a solenoid valve 8 to open and close the large bell 2.

On the other hand, the raw material is temporarily deposited on the small bell 1 from the rotating chute 9, and then the raw material from the small bell 1 is deposited on the large bell 2 under equalization and discharge pressure adjustment by the two bells, the small bell 1 and the large bell 2. Then, by opening the large bell 2, the raw materials collide with the movable armor 10 to adjust the falling position, and are stacked on the surface layer (stock line) of the raw materials already charged.

Now, in the conventional general raw material charging method, the large bell 2 is simply controlled to open all at once to the fully open position by switching control of the solenoid valve 8, and then returns to the fully closed position again after the fully open position is detected.

On the other hand, in the method of this invention, the opening speed of the large bell is controlled according to the opening-time characteristic curve that can provide the optimum material charging according to the gas distribution in the furnace. It is possible to fine-tune the falling position and amount in the direction.

The opening speed of the large bell is controlled using this method. When the large bell 2 is opened, a flow control valve 1 is installed in the oil path that becomes the return piping and whose opening is adjusted by a servo motor M.
1 to control the oil flow rate and control the opening speed of the large bell.

Furthermore, appropriate opening commands are given to the flow control valve 11 one by one in accordance with the movement process of the large bell 2,
A large bell opening speed control device (hereinafter referred to as a control device) 12 having digital calculation and storage functions for controlling a predetermined speed is installed. The control device 12
A signal from a pulse oscillator 13 for detecting each movement of the large bell 2 during the opening operation is inputted to the control device 12 to perform opening speed feedback correction control.

On the other hand, the setting of the opening degree-time characteristic curve shown in FIG. ing.

Next, details of the large bell opening speed control will be explained.

First, in Figure 2, the horizontal axis is time T (S), the vertical axis is large bell opening P (mm), and the solid curve represents the desired opening speed pattern of large bell 2 based on the gas distribution at the top of the furnace. It shows.

Next, this opening speed pattern is changed to 5 along the time axis.
Each of the division points 1 to 5 is specified, and each division point is set in advance for each charging batch of the blast furnace using the setter 14. In this specific example, five division points can be set for each of eight batches of charging.

The set values of 8 batches x 5 division points are input to the control device 12, and the speed pattern storage circuit 1 in the device 12 is inputted.
5 and store it in memory. Next, the circuit 15 sequentially repeats the memory for eight batches in accordance with the progress of the charging batches in the blast furnace, and outputs the memory to the next speed conversion circuit 16. The speed conversion circuit 16 converts the five division points (position, time) of each batch outputted from the previous circuit 15 into a time (T) x speed (V) function as shown in FIG.

In Figure 3, the horizontal axis is time (T) and the vertical axis is velocity (V).
This is a conversion of the opening degree-time characteristic curve in FIG. 2, and the speed between each division point in FIG. 2 is processed to be constant. Returning to FIG. 2, the opening degree and time after this processing are approximated to straight lines as shown by the dotted lines between the division points in FIG.

This process divides the opening speed control of the large bell 2 into each section, and within each section, the speed control by the hydraulic circuit is simplified as constant speed processing to improve accuracy, and in effect, the solid line curve in Figure 2 is used. The control is made according to the following.

In addition, in this conversion, when stopping at the final point of the five division points, the speed V is not instantaneously reduced to zero, but the speed V is slowed down before the final point, and then the speed at which the speed V is set to zero and stopped is changed. It is a pattern. This is a measure to improve the accuracy of the stop position and to soften the mechanical shock of the large bell 2.

In addition, the above time (T) x speed (V) pattern is
In the next speed correction circuit 17, as shown in FIG. 4, correction is performed before and after each division point based on the time and position signals. Details of this control will be explained with reference to FIG. 5, which is an enlarged and detailed view of one division point in FIG. 2.

When the actual speed of the large bell 2 (solid line a) slightly deviates from the set speed pattern (dotted line) via (Tk, Pk) in Figure 5 and does not reach the specified position PK in the specified time TK. In this case, when the specified time TK is reached, the opening operation is performed at full speed up to the specified position PK, and thereafter, correction control is performed to move to the next dividing point in the original speed pattern.

Furthermore, if the specified position PK is reached before the specified time TK (actual b), when the specified position PK is reached, the opening speed is reduced to the minimum opening speed and maintained at a nearly stopped state, and when the specified time TK is reached, the opening speed is Correction control is performed to shift to the speed pattern of

In Fig. 4, this correction control is performed at division points 1 and 3.
5 shows an example in which the control indicated by the solid line a in FIG. 5 is performed at the division point 2, and the control indicated by the solid line b in FIG. 5 is performed.
Note that at division point 4, no correction control is required, and an example is shown in which the operation is performed as set.

In order to execute the above correction control, a time element and a position element are required. Regarding the time element, as shown in FIG.
The predetermined time at each division point is monitored and output to the speed correction circuit 17 one by one. On the other hand, regarding the position element, a position signal from a pulse oscillator 13 is input to a speed correction circuit 17, and this circuit 17 monitors the prescribed position of each division point.

(Function) The movement of the large bell under control compatible with the present invention will be described based on FIG. 6 in comparison with a conventional material charging method (comparative example) in which the large bell opening speed control is not performed. Figure 6 is a motion diagram of the large bell,
The horizontal axis is time T (S), and the vertical axis is large bell opening P (mm).

Here, the drive source for the large bell is generally a hydraulic cylinder, and the large bell is opened and closed by the opening and closing operation of a solenoid valve in the hydraulic circuit, but in the comparative example, the solenoid valve in the hydraulic circuit is simply fully opened or closed. Since it is fully closed, the large bell moves at full speed to the large bell fully open position Pμ, or conversely to the fully closed position Po, as shown by the solid line C in FIG. Therefore, there is a problem that the raw materials fall in the same place at the same time.

On the other hand, according to the control method of the present invention, it is possible to control the speed pattern according to the gas distribution state in the furnace, that is, as shown by the dotted line d or e in FIG. The opening degree can be set to any position of the large bell, and the moving time can be slowed down to allow the raw materials to fall slowly according to the opening degree of the large bell, and the moving speed is also variable.

In this control method, the final large bell opening position, time (Ti, Ri), and intermediate movement speed are determined by the curve d in Figure 6, depending on various process factors such as each type of raw material and each batch. Alternatively, as shown in e, it is possible to arbitrarily change the distribution of raw materials in the furnace to achieve an optimal distribution of raw materials in the furnace. For example, depending on the gas distribution state in the furnace, an operation can be performed to arbitrarily shift in the direction of the curve d or the direction of the curve C shown by the arrow in FIG.

(Effects of the Invention) According to the present invention, variable control of the opening speed of the large bell by hydraulic drive, which has been considered difficult in the past, is substantially possible, and thus optimal operation of the blast furnace can be realized.

In addition, changes in the temperature, viscosity, and turbidity of the oil in the hydraulic system, changes in the properties (particle size, weight, type, and blending ratio) of the raw materials on the large bell, and changes in weight due to the discharge of raw materials from the large bell. On the other hand, by minutely managing and correcting the opening speed of the large bell, it is possible to control the opening speed of the large bell with high accuracy, and it is also possible to cope with frequent setting changes or short-term control.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing the top of the blast furnace and the control circuit, Fig. 2 is a graph showing the opening degree-time characteristic curve,
Figure 3 is a graph showing the set opening speed, Figure 4 is a graph explaining correction control, Figure 5 is a graph explaining correction control at one division point, and Figure 6 is a graph explaining the movement of the large bell. The graph is 1...Small bell, 2...Large bell, 3...Bell rod, 4...Segment, 5...Counterweight, 6...Hydraulic cylinder, 7...Hydraulic unit, 8...Solenoid valve, 9 ...Turning shoot, 10...
...Movable armor, 11...Flow control valve, 12...Large bell speed control device, 13...
Pulse transmitter, 14...Speed pattern setter, 1
5...Speed pattern storage circuit, 16...Speed conversion circuit, 17...Speed correction circuit, 18...Timer count circuit.

Claims (1)

[Scope of Claims] 1. The opening degree-time characteristic curve of the large bell that provides optimal operation by charging material according to the composition distribution or temperature distribution of the gas in the blast furnace is divided into several sections along the time axis, and within each section. In order to control the opening speed of the large bell to a constant speed that approximates the curve of The large bell opening at the top of the blast furnace is characterized by controlling the opening speed of the large bell that approximates the opening-time characteristic curve to the polygonal line by performing correction control by comparing the opening of the dividing point. Speed control method.