JPS60251206A - Method for controlling blast furnace heat - Google Patents

Abstract

PURPOSE:To enable control of blast furnace heat when said heat fluctuates in short time by predicting continuously the change of the furnace heat and adjusting conditions in front of tuyeres so as to maintain the specified heat. CONSTITUTION:A laser light emission analyzer 10 is installed to the flow behind a skimmer 6 for a molten iron 4 which is tapped from a tap hole 1 and flows in a tapping spout 2. A laser is then projected on the surface of the molten iron 4 through the inside of a pipe 7 in which clean N2 is passed from an introducing pipe 9. The analyzer 10 measures continuously the components in the molten iron 4 by an emission spectrochemical analysis method. When the measured value is transmitted to a microcomputer 11, the microcomputer 11 predicts the furnace heat after specified time from the continuously obtd. components of the molten iron 4 and adjust the conditions in front of the tuyere so as to maintain the specified furnace heat which is predicted.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for controlling the furnace heat of a blast furnace. More specifically, the present invention relates to a method for controlling the furnace heat of a blast furnace, and more specifically, a method for predicting the furnace heat after a certain period of time by continuous analysis of hot metal components, and controlling the furnace heat. Regarding how to.

[Conventional technology]

Conventionally, (Si) in hot metal has been used as an index representing furnace heat, and furnace heat control has been performed to keep it above a certain value.

However, recently, in response to changes in the requirements of the steelmaking process,
The hot metal temperature is high, and it is necessary to produce hot metal with a low (Si) concentration.

In daily operations, various operational actions and changes in the furnace such as slip occur dynamically, resulting in changes in the hot metal temperature and (
S i) Concentration also varies within the mouth and from day to day. Controlling this type of variation is also an important point in low (Si) manufacturing.

Recently, blast furnaces have also played an important role as gas supply equipment in steel plants. For this reason, blast furnace production volume may be changed significantly within the day depending on the gas balance within the plant. For example, if the unit price of electricity purchased from outside differs between day and night, it is possible to operate at a high coke ratio during the day when the unit price of electricity is high to increase the amount of in-house power generation, and at night to operate at a low coke ratio. There is.

Conventional furnace heat control systems often find it difficult to control such large changes in operating factors over a short period of time. The conventional furnace heat control system analyzes the pig iron sampled several times during one tapping cycle, and
) and other ingredients.

On the other hand, from the changes in (Si) over the past several tens of hours and the contribution of each factor to (St) from the sensor information,
The change in (S i) after a certain period of time is predicted from the recent changes in each factor. In the conventional technology, although (Si), which is the most important information, is included in the autoregressive equation, 1
There is one to several data within one tapping cycle, and it is discontinuous in time. In addition, the latest analysis values are based on the sampling time,
Considering the time required for instrumental analysis, there is a time delay of at least 20 minutes. For this reason, with conventional technology, although it is possible to prevent slow fluctuations in (Si) over a period of 1 hour, it does not have a (Si) fluctuation prevention function against large fluctuations in operating factors within a day. This is the current situation.

[Problem that the invention seeks to solve]

The present invention aims at predictively controlling (S i ) fluctuations in short-term changes in blast furnace operating factors in order to overcome the drawbacks of the prior art.

[Means for solving problems]

In order to achieve the object stated in -1-, the present invention installs a laser emission spectrometer in the tapping trough-L, continuously measures (S i) of the hot metal flowing in the trough, and calculates the measured value. The operating factors can be adjusted by predicting [Si] after a certain period of time using This is a furnace heat control method that prevents furnace heat fluctuations due to changes.

FIG. 1 is an explanatory diagram of the present invention, and to explain this diagram, a laser emission spectrometer 10 is installed downstream of the skin mallow with respect to hot metal 4 that is tapped from the taphole 1 and flows through the taphole 2. This laser emission spectrometer and the microcomputer 11 connected thereto constitute an analysis system, and such an analysis system is utilized. The analyzer 10 may be installed anywhere as long as the surface of the hot metal after the slag 5 has been removed by the skin mallow is exposed.For example, the analyzer 10 may be installed on the inclined trough 3.

A laser beam is emitted onto the hot metal from an optical emission spectrometer lO shielded by a heat shield plate 8. Signal-to-noise ratio (S/N ratio) due to laser scattering and emission due to dust in the atmosphere
In order to prevent a drop in the temperature, clean N2 is passed through the pipe 7 from the introduction pipe 9 and projected onto the surface of the hot metal 4.

The N2 from the N2 introduction pipe 9 also serves to simultaneously blow away the scum and the like on the top surface of the hot metal 4, thereby keeping the surface of the hot metal exposed at all times.

The signal measured by the analyzer IO is transmitted to the microcomputer 1.
1 and converted to (St) concentration using a calibration curve,
Furthermore, the data is averaged for 1 minute, and the central computer 1
7. FIG. 2 is a system configuration diagram of the arithmetic system of the present invention. The data transmitted from the microcomputer 11 is stored in a temporary database 14 in the central computer 17 along with data from other sensors 13 (temperature, pressure, gas components, etc.). In the central computer 17,
Once every 5 minutes, database 14, latest (St) value,
From the data regarding future operational change plans input from the typewriter 18, the following method is used to calculate (S) for two days.
i) The predicted value is displayed on the CRT display 15 or the form 16.
Output to.

(Si) is predicted as follows. The prediction coefficient is calculated using the difference in the transfer index smoothed values of various furnace heat-related information over the past several tens of hours, and according to the basic formula below, the (S
Calculate the θ-order side of i).

Basic prediction formula: % formula% Δ(Si): Change in (Si) after time KI: Sensor i
(St) prediction coefficient (i includes the output value of the laser analyzer) ΔXi: Change in the exponentially smoothed information value. By changing the operating factors and the response characteristics of each factor to (Si), the first-order measurement of (St) after time t is performed using the following formula.

Sentence Δ(S i) 1-, Σ Rj(-τj)・AjJ=
1 Here, Aj: Width Rj of action j (-τj): (Si
) Response τj: Operation change time Based on the primary side of (Si)1 output on the CRT display 15, the operator inputs the width and time of the most recent action from a typewriter. In many cases, responsive immediate conditions are used as corrective actions.

The (Si)2 prediction is recalculated, also taking into account the correction action, and output to the CRT display 15.

[Effect]

In the present invention, (Si) in hot metal is continuously measured, and from these continuous measurement values, the furnace heat after a certain period of time is predicted using a statistical method using the above formula. For this reason, laser spectroscopy is used as the most preferred measurement method.

A laser analyzer is an indispensable piece of equipment for improving accuracy on the O-order side. In addition, with this system, the operator can interactively determine the width and time of the action while looking at the CRT display, thereby achieving stable low (Si) operation.

〔Example〕

FIG. 3 shows a comparison between the measurement results of laser emission spectrometry and normal analysis using sampling.

The analytical values at corresponding times correspond well to each other. In addition, with the laser emission spectrometer, at the start of the second tap, the pig iron (
A change in Si) is clearly recognized. When sampling is used, it is difficult to distinguish this change from the actual furnace heat change.

FIG. 4 shows an example of (Si) control according to the present invention.

The operator set the air blowing temperature based on the prediction of (St)+, and changed the actual air blowing temperature so that the fluctuation of (St) would be small in the (S i)2 prediction. It can be seen that the variation in the measured value of (S i) is very small despite the short-term change in coke ratio.

Figure 5 shows an example of the effects of the furnace heat control system of the present invention.
It is shown by the tendency of daily (Si) fluctuation σ[5□]. The conventional model has functioned satisfactorily when operating at a certain level. However, when the day and night Besbukibun starts operation, σ(Si
) rose from around 0.1 to about 0.4, and the fluctuations in furnace heat became remarkable.

When the model of the present invention was applied to actual operation from September, σ
8i] decreased to about 0.1 again, making stable furnace heat control possible.

〔Effect of the invention〕

According to the present invention, changes in blast furnace furnace heat are continuously predicted and immediate conditions are adjusted to keep this preheating constant, making it possible to control furnace heat during short-term fluctuations.

[Brief explanation of the drawing]

Fig. 1 is an analyzer layout diagram explaining the method of the present invention, Fig. 2 is a system configuration diagram, Fig. 3 is a graph showing the transition of analysis results, Fig. 4 is a graph showing an application example of the furnace heat control method, FIG. 5 is a graph showing the difference in effect between the conventional system and the present invention. l...Tackle port 2...Tackle trough 3...Slanted trough 4...Hot metal 5...Slag 6...Skipperpuff...Pipe 8...Heat shield plate 9...N2 Introductory tube 10...Laser emission spectrometer 11...Microcomputer 12...Sensor terminal l3...Sensor 14...Database 15...
CRT display 16...Form 17...Central computer 18...Input typewriter Applicant Kawasaki Steel Co., Ltd. Agent Patent attorney Yoshi Kosugi Male patent attorney Sai Raw materials Rule 1 -1゛彎1

Claims (1)

[Claims] l Project a laser beam onto the surface of the tapped hot metal, continuously measure the components in the hot metal using emission spectrometry, predict the furnace heat after a certain period of time from the continuously obtained hot metal components, and A blast furnace furnace heat control method characterized by adjusting immediate conditions so as to keep predicted furnace heat constant.