JPH11201806A - Method for measuring molten pig level in ladle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To estimate molten pig level substantially accurately by predicting the level based on the variation rate of weight thereof when foaming takes place in the ladle and correcting the predicted level. SOLUTION: A microwave level gauge measures the pig level in the form of a continuous analog quantity which is then sampled at a constant time interval (t sec) and converted into a discrete time series data. It is smoothed through moving average processing in order to remove noise and a current pig level Lm(t) is determined at a time (t) after smoothing. Measurement of the weight of a received pig is also processed and a current weight Wm(t) is determined after the pig is smoothed at the time (t). The predicted value Lp(t+1) of pig level at a time (t+1) following to the time(t) is then determined based on the weight variation rate of Wm(5). It the current level Lm(t+1) of pig level measured by the microwave level gauge deviates significantly therefrom, a decision is made that foaming is generated and the Lp(t+1) is employed as the pig level in place of the Lm(t+1).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the level of hot metal in a receiving vessel when hot metal is received in a receiving vessel during tapping of a blast furnace, and more particularly to a method for measuring hot metal level using a microwave level meter. Regarding how to always measure accurately.

[0002]

2. Description of the Related Art In addition to a weight measurement method, a laser distance measurement method, a microwave distance measurement method, and a contact (sounding) wire method are used to measure the hot metal level in a receiving vessel during tapping of a blast furnace. Although a length measuring method and the like are known, a distance measuring method using a microwave, which is non-contact and can measure even in an atmosphere with much dust and dust, is mainly used.

[0003] However, as shown in FIG. 1, when de-siliconization of hot metal is performed in a cast-bed de-siliconization facility installed in front of a blast furnace, the de-siliconization introduced from the hot metal 4 and the desiliconizer inlet 6 is performed. The reaction with the agent proceeds even after the hot metal 4 is injected from the inclined pouring trough 5 into the pig iron receiving vessel 3, and forming may occur in the pig iron receiving vessel 3.

[0004] This phenomenon will be described in detail as follows. That is, since the desiliconization of the hot metal is performed by mixing an oxide such as iron oxide with the hot metal, a slag layer in which the desiliconizing agent is turned into a slag is formed above the hot metal in the pig iron receiving vessel. Since the silicon in the hot metal is oxidized by the oxygen in the iron oxide,
It is inevitable that a decarburization reaction occurs simultaneously with the desiliconization reaction, and a gas such as carbon monoxide is generated in the slag. Therefore, many fine bubbles are generated in such a slag. These bubbles rise in the slag and are discharged from the slag surface to the atmosphere. However, due to the influence of the temperature, viscosity, surface tension, and the like of the slag, the discharge of the bubbles is delayed, and large bubbles may be formed in the slag. In such a case, the entire slag increases its apparent thickness in the vertical direction. Forming refers to a state in which slag mainly composed of an oxide such as a desiliconizing agent is foamed by large bubbles on the hot metal poured into such an iron receiving container.

If the level of hot metal is to be measured by the microwave level meter 1 while such forming is occurring, the microwave is reflected on the surface (upper surface) of the forming layer. The lower surface cannot be measured, and as shown in FIG. 4, the upper surface 8 of the forming layer is measured as the hot metal level, resulting in an erroneous filling of the pig iron receiving container.

As a means for solving such a problem, Japanese Patent Application Laid-Open No. 5-125413 proposes a system for detecting a full amount by using a level meter and a load cell in combination and switching a slope gutter. . In addition, in addition to the microwave level meter 1 as shown in FIG.
Are often juxtaposed. Since the measured value of the weighing scale 2 is not affected by the forming, the tapping speed can be accurately measured by the attachment of the weighing scale 2. Since the weight varies depending on the adhesion of the metal, the weighing scale 1 cannot detect the full amount. Therefore, in the conventional method, the hot metal 4 cannot be received and transported to the full capacity in the receiving vessel 3,
In addition to the reduction in the hot metal transport efficiency, the processing efficiency of the next process such as the hot metal pre-treatment is lowered, and there are problems such as a large drop in the hot metal temperature.

[0007]

SUMMARY OF THE INVENTION The present invention overcomes the above-mentioned problems of the prior art and provides a means capable of almost accurately estimating the hot metal level in a pig iron receiving vessel even when forming occurs. It is an object of the present invention to enable hot metal to be always received to a full level and transported to the next process.

[0008]

In order to solve the above-mentioned problems of the microwave level meter, the present inventor uses a weighing scale attached to the blast furnace tapping facility to reduce the time period during which forming occurs. Knowing that it is possible to predict the level of hot metal and correct the measured value by the microwave level meter, the concrete means has been completed, and if forming cannot be measured by the microwave level meter, The hot metal level predicted based on the weight change rate by the meter is obtained, and the value is used as a correction value of the hot metal level in the receiving vessel.

More specifically, as a method for measuring the hot metal level in a pig iron receiving vessel, when the hot metal level in the pig iron receiving vessel is measured using a microwave level meter, when the forming occurs in the pig iron receiving vessel, In this method, a predicted value of the hot metal level is obtained based on the weight change rate of the hot metal in the pig iron receiving vessel, and the predicted value is used as a correction value of the hot metal level in the pig iron receiving vessel. At that time, the difference between the measured value of the hot metal level measured by the microwave level meter and the predicted value based on the rate of change in the weight of the hot metal in the hot metal container exceeds a certain value. Is to be determined by

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments. First, the measurement result of the hot metal level measured by the microwave level meter measured as a continuous analog quantity is sampled at fixed short time intervals (Tsec) and converted into time-series discrete data. At this time, since the data contains noise, an operation for smoothing and removing noise by moving average processing is performed.

The hot metal level at time t after smoothing as described above, that is, the current value of the hot metal level after smoothing (hereinafter simply referred to as the “current value of hot metal level”), Lm (t), is Lm (t) = ｛L (T) + L (t−1) +... + L (t−n + 1)｝ / nn: natural number (1)

The measurement result of the pig iron weight by the weighing scale is processed in the same manner as described above, and the current value of the smoothed pig iron weight at time t, Wm (t), is defined as follows. Wm (t) = {W (t) + W (t-1) +... + W (tm + 1)} / mm m: natural number (2) The receiving speed Ws (t) is Wm (t) ) Is obtained by differentiating equation (2). That is, Ws (t) = {W (t) −W (tk)} / k × T (3) T: sampling interval, k: natural number

Using the above equation (3), Ts following time t
predicted value L of hot metal level at time (t + 1) after ec
p is obtained as follows. Lp (t + 1) = Lm (t) + Ws (t) × T × α (4) where α is the weight W of the pig iron in the pig iron container shown in FIG.
It is a coefficient based on the relationship between (t) and the actual receiving level L (t), and its dimension is m / kg. In order to determine α, the relationship between L (t) and W (t) is preferably stored in advance in an arithmetic unit. However, the above relationship changes depending on the internal shape of the pig iron container (the amount of metal ingot, the amount of refractory consumed, etc.). Keep it updated.

In the present invention, the hot metal level Lp (t + 1) predicted by the above-mentioned hot metal weight rate and the current hot metal level Lm (t) measured by the microwave level meter are used.
+1), it is determined that the forming has not occurred if the two substantially match, and it is determined that the forming has occurred if the both are largely separated. When it is determined that the forming has occurred, the hot metal level predicted using the weight change rate, instead of the current hot metal level value Lm (t + 1) measured by the microwave level meter, That is, the hot metal level is determined using the predicted value Lp (t + 1) given by the equation (4).

That is, Lp (t + 1) <Lm (t + 1) -β (5) β: When β is a constant, it is determined that forming has occurred, and Lm (t
Instead of using +1), Lp (t + 1) is adopted as the hot metal level. In other words, the current value of the hot metal level is discarded and the predicted value is adopted. Here, the constant β is a swelling dimension of the hot metal level generated when the forming occurs, and is determined empirically. Usually, as β, 100 to
Set about 500 mm.

Time t + 2 after a lapse of 2 Tsec from time t
In equation (4), Lp (t + 2) = Lp (t + 1) + Ws (t + 1) × T × α (6), which is the current value (Lm
(T + 2)), and the same operation as above is performed. Thereafter, the same determination and operation as described above are repeated at each measurement time, and when the forming has disappeared, the process returns to adopting the level measured by the microwave level meter again.

The above steps will be described with reference to FIG.
At time t, forming has not occurred, and therefore the current hot metal level value Lm (t) is used as the hot metal level. However, at time (t + 1) after the lapse of Tsec, Lm (t + 1) ≫Lp (t + 1). Therefore, it is determined that the forming has started. 2 more
Since Lp (t + 2) 後 Lm (t + 2) at time (t + 2) after the lapse of Tsec, it is determined that the forming is being performed. However, 3T
At time (t + 3) after the lapse of sec, Lp (t + 3) ≒ Lm (t + 3), so that it is determined that the forming is completed.

Based on the determination of the start, the duration and the end of the forming, the hot metal level is set as follows: time t: Lm (t),... The present value by the microwave level meter Time (t + 1): Lp (t + 1). Corrected value based on received pig weight Time (t + 2): Lp (t + 2) ... Corrected value based on received pig weight Time (t + 3): Lm (t + 3) ... The current value obtained by the microwave level meter.

[0019]

According to the present invention, even when forming occurs while measuring the level of hot metal during iron receiving from a blast furnace with a microwave level meter, the estimated level estimated based on the weight change rate obtained by the weigh scale is used. The value is calculated every moment to detect the occurrence of forming, and if forming is occurring, the hot metal level is corrected using the value predicted based on the rate of change in the weight of the received iron, so that forming occurs. However, it is possible to always receive hot metal to the full level. As a result, in addition to improving hot metal transport efficiency,
The treatment efficiency in the next process such as hot metal pretreatment is improved, and energy saving effects such as prevention of hot metal temperature drop can be expected.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing an arrangement state of an iron receiving facility for implementing the present invention.

FIG. 2 is a diagram showing a relationship between a hot metal level L (t) and a hot metal weight W (t) in an iron receiving container.

FIG. 3 is a graph showing the relationship between the elapsed time during hot metal receiving and the hot metal level when the present invention is applied.

FIG. 4 is an explanatory diagram showing an operation state of a microwave level meter when forming has occurred.

[Explanation of symbols]

 1: microwave level meter 2: weighing scale 3: pig iron container 4: hot metal 5: inclined gutter 6: desiliconizer inlet 7: cast floor level 8: forming layer surface

Claims (2)

[Claims] When measuring the hot metal level in a pig iron receiving vessel using a microwave level meter, when the forming occurs in the pig iron receiving vessel, the weight change rate of the hot metal in the pig iron receiving vessel is also measured. A method for measuring a hot metal level in a pig iron receiving vessel, wherein a predicted value of the hot metal level is obtained and the predicted value is used as a correction value of the hot metal level in the pig iron receiving vessel. 2. The occurrence of forming in the pig iron receiving vessel is such that the difference between the actually measured value of the hot metal level measured by the microwave level meter and the predicted value based on the weight change rate of the hot metal in the pig receiving vessel exceeds a certain value. 2. The method for measuring the level of hot metal in an iron receiving container according to claim 1, wherein the determination is made by the following.