JPH0634532A - Method of measuring moisture of sinteref material - Google Patents

Abstract

(57) [Summary] [Purpose] In a method for measuring the moisture content of a sintering raw material, in which the moisture content is measured online by utilizing the absorption of infrared rays by water,
Improve the measurement accuracy by using a measurement method that takes advantage of the properties of mixed raw materials. [Structure] Immediately after each intermittent change of the composition of the sintering raw material, precise moisture measurement is performed by the absolute dry moisture meter 6, and this measured value and the relative moisture measured value by the infrared moisture meter 4 which is constantly measured. And are selected as the same time data by the memory operation, a new calibration curve of the relative moisture measurement value is created by performing a linear regression of the precision moisture measurement value and the relative moisture measurement value of the specified number of times, and this calibration curve is used. And obtain an accurate moisture value.

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 moisture content of a sintering raw material, which is capable of accurately and continuously measuring the moisture content of a sintering raw material, for example, a powder raw material of sinter ore.

[0002]

2. Description of the Related Art In the manufacturing process of sinter, the water content of a mixed raw material (which has been called a sintering raw material) that is a mixture of iron ore, limestone, etc., which is the raw material of the sinter, is It is an important factor for controlling the raw material and air permeability on the machine, and control is performed to keep this moisture constant.
So far, as the means for measuring the water content of this mixed raw material,
There is an absolute dry type. In this method, the water content value can be obtained very accurately by comparing the weight of the sampled mixed raw material with the weight after completely drying it. However, this method is disadvantageous in that it is performed after an intermittent operation of collecting raw materials, and that it takes a long time from the raw material collection to the complete drying of the sample to obtain the water content.

Therefore, as a method for rapidly measuring, for example, the water content of a powder raw material without the need for an operation such as drying, an infrared method disclosed in JP-A-59-72047 has been proposed. . This method guides the detected amount of infrared rays (more accurately, the amount of infrared rays absorbed by the infrared rays absorbed by water) to a converter, and uses a calibration curve showing the relationship between the preset infrared amount and water content It is converted into the moisture content and output. Further, a measuring method proposed by Japanese Patent Laid-Open No. 62-839 is disclosed as a method of removing a disturbance factor peculiar to the sintering raw material and improving the measurement accuracy while using the same infrared moisture meter. This method is intended to absorb an error that tends to occur particularly at the time of changing the composition by detecting the steady deviation in the water content control and adding the steady deviation.

[0004]

In the conventional method for measuring the moisture content of the sintering raw material as described above, first, the infrared moisture meter disclosed in JP-A-59-72047 is affected by atmospheric moisture. In principle, the optical property of the surface of the sample is to be measured, and it is also affected by the shape, particle size, color, etc. of the sample. In addition, when a sample sprinkled from the outer surface on a lump like a sintering raw material is targeted, there is a problem that the measurement target does not represent a true sample. Further, the method disclosed in Japanese Patent Laid-Open No. 62-839 is to calibrate for the first time when a steady-state deviation error in moisture control occurs, and the error caused by a specific event such as a combination change occurs. On the other hand, countermeasures may be delayed. In addition, disturbance factors that are not related to the moisture meter, such as abnormalities in the watering system, are automatically calibrated as if they were problems with the moisture meter, and treated as if they were properly controlled. Therefore, there is a problem that it is dangerous to apply it to an automatic control system.

The present invention has been made in order to solve the above-mentioned problems, and provides a method for measuring the moisture content of a sintering raw material, which is excellent in measurement accuracy, by adopting a measuring procedure that makes use of the properties of the sintering raw material. The purpose is to do.

[0006]

The method for measuring the moisture content of a sintering raw material according to the present invention is a method for measuring the moisture content of a sintering raw material, in which the moisture content of a specimen is measured online by utilizing the absorption of infrared rays irradiated by water. That is, each time the composition of the sintering raw material is changed intermittently, precise moisture content is measured by an absolute dry type moisture content measuring means immediately after that, and the precise moisture content and the infrared absorption which are constantly measured. The relative moisture measurement value is selected as the same time data by the memory operation, and the primary calibration of the precise moisture measurement value and the relative moisture measurement value for the specified number of times is performed to obtain a new calibration curve of the relative moisture measurement value. It is calculated and the accurate moisture value is obtained using this calibration curve.

[0007]

In the present invention, every time the sintering raw material is blended intermittently, immediately after that, precise moisture measurement is carried out by the absolute dry moisture measuring means, and the measurement is carried out at the same time. A calibration curve is automatically created by a calculation process that performs linear regression with the measurement value of the infrared moisture meter, and the moisture value of the sintering raw material is obtained using this calibration curve. When exposed, a calibration curve suitable for this formulation is obtained, and a highly accurate moisture value is obtained by the measurement value of the infrared moisture meter using this calibration curve.

The disturbance factors in the moisture measurement of the sintering raw material by the conventional technique, that is, the shape, particle size and color of the sample are
It largely depends on the raw material composition. Depending on the raw material situation, this change in composition is carried out in a cycle of about 7 days. It is considered that the above-mentioned disturbance factors are almost constant between the change of the composition and the change of the composition, and the calibration curve showing the relationship between the infrared ray amount and the water value is constant during the period.

[0009]

EXAMPLE FIG. 1 is a measurement flow chart that also serves as a configuration diagram of a measuring apparatus, schematically showing an example of the method for measuring the water content of a sintering raw material according to the present invention. In the figure, a sintering raw material (not shown) sent from a raw material mixing tank 1 is placed on a conveyor 2 that continuously moves in the arrow direction, mixed in a mixer drum 3, and conveyed as it is in the arrow direction. It An infrared moisture meter 4 is arranged above the conveyor 2 leaving the mixer drum 3 to measure relative moisture by infrared absorption. Then, the absolute sampling water content of the sample collected by the sample sampling means 5 installed in close proximity thereto is precisely measured by the moisture meter 6. Both the moisture value by the infrared moisture meter 4 and the moisture value by the absolute dry moisture meter 6 are stored and held in the process computer 7 having a measured value storage means and a calculation means. The calculated measurement result is displayed by the display device 8 of the display means. Reference numeral 9 is a water content control means for supplying and controlling water content to the sintering raw material according to a command from the process computer 7.

Next, a measuring procedure and a measuring method will be described. When the composition of the mixed raw material is changed, the calibration curve that has been used so far is once deleted after the performance information is taken in, and a new calibration curve is created. Immediately after the composition was changed, when the moisture was measured by an absolute dry moisture meter (hereinafter referred to as an absolute dry moisture meter) 6, the sampling time was notified to the process computer (hereinafter referred to as a process controller) 7, and the infrared moisture meter 4 at that time was notified. The measured or indicated value is recorded at the same time. It takes about one hour from the absolute dry moisture meter 6 to obtain the moisture value after the sample is dried and weighed, but the process controller 7 always stores the infrared moisture meter 4 continuously and continuously. Therefore, the indicated value one hour ago can be easily taken out. In this case, the moisture measurement by the absolute dry moisture meter 6 is performed a specified number of times (usually 5 to 6 times) after the composition is changed, and the infrared ray amount at the time of sampling is simultaneously stored each time. Once the specified number of measurements have been completed, the first-order regression of the precise measurement values and infrared measurement values by the absolute dry moisture meter 6
And a new calibration curve is created. After that, until the next composition change, the accurate moisture value can be obtained online from the indicated value of the infrared moisture meter 4 by this new calibration curve.

Although the conventional calibration curve is used immediately after the composition is changed, if the moisture content of the absolute dry moisture meter 6 is measured even once after the composition is changed, the moisture content of the infrared moisture meter 4 at the sampling time is compared with the indicated value. Therefore, the error from the moisture value obtained using the previous calibration curve is taken as the steady-state deviation, and the subsequent infrared moisture meter 4
Is corrected by adding it to the indicated value of.

Further, even after the moisture measurement by the absolute dry moisture meter 6 has been performed a prescribed number of times, the measurement by the absolute dry moisture meter is performed regularly (once a day), and the moisture value and the infrared ray amount by this measurement are measured. Is newly stored, and a new linear regression is performed each time together with the pair of data accumulated so far, and the calibration curve is finely corrected.

The calculation process of the measured value by the process control 7 as described above is carried out from a specific event information of the change of the mixture of the mixed raw materials as a starting point. It has become. By adopting this method, as pointed out as a problem of the above-mentioned conventional measurement method, for example, it is possible to make an erroneous measurement operation due to a disturbance irrelevant to the accuracy of the moisture meter that is caused by an operation such as sprinkling water. It becomes possible to measure water accurately with online measurement.

The contents of the arithmetic processing for creating the calibration curve will be described below. After the composition is changed, every time the absolute moisture meter 6 measures, an arithmetic process is performed by the following formula, and the calculated value is reflected in the subsequent handling of the indicated value of the infrared moisture meter 4. In this case, absolutely dry moisture meter 6
Let n be the number of times of water content measurement by, and let Y = aX + b be the regression equation of the calibration curve used before the composition change. That is, it shows a formula for obtaining the moisture value by obtaining the infrared ray amount X after changing the composition. In addition, including the general case, n = 0,0 <
The three cases of n <N and N ≦ n are shown respectively. Here, Y = aX + b: Formula of the calibration curve used before changing the composition Y: Moisture value X: Infrared amount n: Number of times of water measurement by the absolute dry moisture meter after changing composition i: Measurement order of the absolute dry moisture meter yi: i-th measurement value by the absolute dry moisture meter xi: indicated value of the infrared moisture meter corresponding to yi N: the specified number of measurements of the absolute dry moisture meter necessary to obtain a new calibration curve.

(B) When n = 0, the conventional calibration curve (1)
Calculate using an expression.

[0016]

## EQU1 ## Y = aX + b (1) (b) When 0 <n <N, calculation is performed using the equation (2) in which the error component is added to the conventional calibration curve as a bias component.

[0017]

[Equation 2] (C) When N ≦ n, instead of a and b of the conventional calibration curve, α and β obtained by the equations (3) and (4) using the least squares method, respectively, and by the equation (5), Calculate

[0018]

[Equation 3]

[0019]

[Equation 4]

[0020]

## EQU5 ## Y = αX + β (5)

FIG. 2 is a diagram showing an example of a calibration curve for calibration displayed on a CRT (not shown) of the display device 8 of the moisture display means shown in the apparatus of FIG. The vertical axis of the figure shows the moisture value (Y) by the absolute dry moisture meter, and the horizontal axis shows the moisture value (X) of the infrared moisture meter measured at the same point as this moisture value Y. This calibration curve shows the result obtained by calculation using the above-mentioned formula (2). The conditions in this case were N = 7 and n = 5.

[0022]

As described above, according to the present invention, the moisture content of an infrared moisture meter is measured with an absolute dry moisture meter immediately after each change of the composition of the sintering raw material, and the moisture content is measured at the same time as the precise moisture measurement value. Since a new calibration curve is created by performing a linear regression using the measured value of water and the disturbance factor in the conventional method of measuring moisture, that is, the shape, particle size, color, etc. of the sample, absolute drying is performed. It is possible to carry out on-line moisture measurement of the sintering raw material with a high degree of accuracy similar to the equation measurement.

[Brief description of drawings]

FIG. 1 is a measurement flow diagram that also serves as an apparatus block diagram for schematically explaining an embodiment of a water content measurement method according to the present invention.

FIG. 2 is a diagram showing an example of a calibration calibration curve used for moisture measurement according to the present invention.

[Explanation of symbols]

 1 Raw Material Mixing Tank 2 Conveyor 3 Mixer Drum 4 Infrared Moisture Meter 5 Sample Sampling Means 6 Absolute Dry Moisture Meter 7 Process Computer (Pro Computer) 8 Display Device 9 Moisture Control Means

Claims (1)

[Claims] 1. A method for measuring the moisture content of a sintering raw material, which uses absorption of irradiated infrared rays by water to online measure the moisture content of a specimen, wherein the mixing of the sintering raw material is intermittently changed. Immediately after that, precise moisture measurement is performed by absolute dry moisture measurement means, and this precise moisture measurement value and the constantly measured relative moisture measurement value by infrared absorption are selected as the same time data by the memory operation, and the specified number of times is determined. The above-mentioned precise moisture measurement value and the relative moisture measurement value are subjected to linear regression to calculate a new calibration curve of this relative moisture measurement value, and an accurate moisture value is obtained using this calibration curve. Method for measuring water content of sintering raw material.