JPS6017007B2 - Method for detecting firing completion point in DL type sintering machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for detecting the firing completion point in a DL type sintering machine, and in particular, proposes a method for accurately detecting the position of the firing completion point from changes in the thickness of the phosphor layer.

In general, what is important in a DL type carcasses is to maintain a constant degree of sintering after ignition of a layer of sintered raw material charged onto a pallet.

Conventionally, for this purpose, a BmnThrough point (B.T.P.: sintering completion point) was detected from the exhaust gas temperature pattern in the ore discharge section, and the sintering completion point was controlled to be at a predetermined position on the sintering machine. There is. That is, for the sintering process to be satisfactory, it is necessary to maintain the firing completion point of the charge at a constant location in the direction of pallet movement as precisely as possible.

If the firing completion point is too close to the end of the pallet, which corresponds to the point at which material is taken out, or if it is delayed even further and reaches the position after taking out, the product will be contaminated with unburned fuel or unburned material. It will partially contain the baked mixture, resulting in poor quality. Conversely, if the firing completion point is too far from this end and closer to the ignition furnace, equipment and capacity will be underutilized. As a result, an unstable phenomenon occurs which is inconvenient for production of constant quality. Therefore, it is desirable to maintain the position of the completion point of the charge along the pallet at a predetermined location, often close to the discharge end of the sintered material, and this position control is usually carried out under the pallet. A common method was to measure the temperature of the suction gas in a wind box installed in a wind box, and adjust the pallet movement speed according to changes in the temperature distribution. In fact, the temperature of the gas in the windbox below the pallet containing the charges remains constant for most of the initial part of the firing process, then rises to a maximum value and then reaches the downstream end of the pallet. Decrease.

The reason for this change is that the temperature of the gas remains almost constant while the material in contact with the pallet contains moisture, and after drying, the temperature rises to its maximum value, and in principle, this is the point at which firing is completed. This can be explained by the mechanism in which the fuel reaches the pallet floor (grate) and then the temperature decreases as the fuel burns out. In response to this knowledge, if we plot the temperature values corresponding to the positions of each measurement point and create a temperature curve, the line will be almost straight at the beginning, but it will be straight towards the end. It can be seen that it has a curve with a slope of , a maximum, and a curve with a negative slope. Therefore, by measuring the position of this maximum value, it is possible to manipulate the moving speed of the pallet so as to maintain the maximum value at a predetermined position on the pallet. In fact, other things being equal, increasing this speed will move the firing point closer to the downstream end of the pallet, while decreasing the speed will have the opposite effect. However, such control based on the detection of the completion point of a subordinate follower is not satisfactory for the following reasons.

Since the temperature occurring along the pouch is dependent on the composition of the various pouches, the trajectory of the temperature curve is susceptible to uncontrollable factors such as the permeability and composition of the pouches. In addition, the maximum area of the measured gas temperature trajectory curve is delayed due to the large heat capacity of the grate, and the temperature is smoothed out, making it very difficult to find the maximum area. It is.

This holds true even when the number of measurement points is increased. Moreover, the previously mentioned disadvantages had the notable disadvantage that they led to increasingly large changes in the position of the ambiguous local maximum. This invention was devised to advantageously overcome the drawbacks of the above-mentioned secondary kiln technology.According to research, changes in the thickness of the sintered layer after the ignition furnace during the sintering process have been made. When measured with high precision, there was a bending point where the amount of change in the measured layer thickness changed noticeably, and it was found that this bending point corresponded well to the firing completion point (B.T.P.). Based on this knowledge, a method for detecting the firing completion point was completed.

The gist of its configuration is that during operation of a DL type sintering machine, the thickness of the firing layer in the longitudinal direction of the machine, which changes as the sintering machine pallet moves, is measured, and the decrease in the measured layer thickness per hour is measured. A method for detecting a firing completion point in a DL type sintering machine, which is characterized by determining the firing completion position from a bending point where the amount jumps. The details of the configuration will be explained below with reference to the drawings. The present invention has taken the following measures regarding this gist and configuration.

The first point is to measure the layer thickness change ○ of the sintered layer 4 after leaving the ignition furnace 3 in the longitudinal direction of the sintering machine pallet 2, that is, in the machine length direction, using the layer thickness measuring device 1. Then, the layer thickness reduction amount Di is calculated.

A specific method for calculating the amount of decrease in layer thickness Di will be explained based on Fig. 2. Di = Li - Lo where, Mountain: Level at the feed scale side end of the scanning range of the layer thickness measuring device (reference level) Li: Layer However, in this case, after measuring Lo, the layer thickness measuring device travels to position i at a speed V, and the layer itself also moves at a pallet speed PS. Therefore, the distance X' from the reference point at position i needs to be corrected based on the following equation: X'=x-X/VxPS.

Second, the firing completion point is detected from the measured value of the layer thickness reduction amount Di.

As shown in FIG. 1, it is generally known that the cross section of the Sunkei layer can be broadly classified into a raw material 1, a red-hot layer 2, and a dawning layer 3.

In the operation of a bidding machine, it is particularly important to set the red hot layer (zone) 2 to an appropriate size and position, and the shape of the red hot layer 2 can be estimated by various methods (such as the above-mentioned exhaust gas temperature measurement). However, the present invention aims to improve the red tropical 2
The shape, especially the firing completion point (B.T.P.), was detected. Figure 1b shows how the layer thickness reduction Di due to shrinkage changes in the longitudinal direction. It is clearly seen that at the firing completion position, the curve of the layer thickness reduction amount Di forms a bending point X that changes noticeably, and that position becomes the firing completion point. and,
Since the curve becomes gentler toward the ore discharge area with this point X as a boundary, detection of this point X is easy and accurate. Generally, according to the embodiment, the degree of the layer thickness reduction amount Di is 1.0 to 2. Now is the time to draw the G/min curve. In short, the inflection point x of the amount of layer thickness reduction as described above is the point where the shrinkage of the initial raw material layer 1 is accompanied by volume reduction due to coke combustion and welding and partial melting in the red zone 2. B. T. P. In other words, after the firing completion point X, only thermal shrinkage occurs due to cooling, so the shrinkage rate decreases by 4.0%, creating a clear bending point x.

The above-mentioned layer thickness reduction amount Di is measured using an ultrasonic distance meter 5 that can scan the surface of the raw material on the pallet by reciprocating in the same direction as the moving direction, or a microwave, infrared, or laser distance meter. , is calculated by measuring the changes in the levels Lo and Li of the surface layer of the competitive mackerel layer.

An example of actual measurement of Di will be explained below.

[1- Di was obtained by running the ultrasonic level meter and measuring the level transition on the surface of the competitive layer in the longitudinal direction. (2}
To facilitate correction of the measurement position, the ultrasonic level meter was run at the same speed as the pallet speed.

That is, according to this method, it is possible to measure changes over time in the same raw material layer, so there is no need to correct the measurement position. Figure 3 shows the measurement results in that case. True B. T. P.
The position was determined by embedding a thermocouple thermometer in the lower part of the material bed and measuring the actual temperature.

B. obtained by this actual measurement method. T. P. When the position of B. T. P. The position corresponds to the position where the rate of decrease Di is significantly changed to less than 1.5 skins/min, and B. T
．． P. It has been proven that it can be estimated with high accuracy. As explained above, according to the present invention, the firing completion point can be accurately detected and the remarkable effect of stabilizing the operation of the Akatsuki Silk Machine can be obtained.

[Brief explanation of the drawing]

In Figure 1, a is a diagram showing the relationship between layer thickness and distance in the sintered layer, b is a diagram showing the relationship between layer thickness reduction and distance, Figure 2 is a schematic diagram of Akatsuki Seiki, and Figure 3 is a diagram showing the relationship between layer thickness and distance. FIG. 3 is a diagram showing changes in the amount of thickness reduction. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. When operating a DL type sintering machine, the thickness of the sintered layer in the machine length direction, which changes as the sintering machine pallet moves, is measured, and the sintering is started from the bending point where the amount of decrease in the measured layer thickness per hour increases dramatically. A method for detecting a firing completion point in a DL type sintering machine, the method comprising determining the firing completion position.