JPH0288724A - Method for operating sintering machine - Google Patents

Abstract

PURPOSE:To prevent insufficient sintered part in sintered ore by measuring dust concn. at the sintered ore discharging part in a sintering machine at the time of operating the DL type sintering machine and executing positional control of sintering completing point in accordance with the change of the measuring value. CONSTITUTION:In the sintered ore discharging part, a crusher 4 is set, and the sintered ore is primarily crushed. Therefore, in the sintering machine operation remaining the insufficient sintered part in the sintered ore, at the time of crushing in the sintered ore discharging part, this insufficient sintered part is powderized and the dust concn. is increased and this change is detected with a dust concn. meter 5 and the sintered condition in a pallet in the sintering machine can be judged. Therefore, in the case the dust concn. increases, by reducing the pallet 1 speed so that the detected BTP(Burn Through Point) shifts toward ignition furnace side, even if the detection of the true BTP is difficult, as the BTP can be controlled under correcting in accordance with the dust concn., the optimum BTP can be decided.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for operating a sintering machine, and more particularly, in a sintering operation using a Dwight Lloyd (D[) type sintering machine, a method for operating a sintering machine based on the exhaust gas temperature of a wind box is used. to detect the firing completion point,
The present invention relates to a method of operating a sintering machine that enables stable sintering operation by measuring the dust concentration in the ore discharge section of the sintering machine and controlling the position of the sintering completion point according to changes in the measured value.

Conventional technology Burn Through Po in DL type sintering machine
1 nt (BTP: calcination completion point) is considered to be an important index that affects the quality and production amount of sintered ore.

Conventionally, BTP was calculated from the exhaust gas temperature of the windbox,
The value was controlled by pallet speed or other ventilation adjustment means, such as raw material packing density, raw material moisture, and raw material layer thickness, so that the value was within the control range determined empirically. The reality is that true BTP control is not performed because it is affected by the leak rate.

In general, what is important in the operation of a DL type sintering machine is to maintain a constant degree of sintering after ignition between the sintering raw materials charged on the pallet.

Conventionally, for this purpose, the BTP is detected from the exhaust gas temperature pattern in the ore discharge portion, and the BTP is controlled to be at a predetermined position on the sintering machine.

That is, for the sintering process to be satisfactory, it is necessary to maintain the BTP of the charge at a constant location in the direction of pallet travel as precisely as possible. BTP force = m If the material is too close to the end of the pallet, which corresponds to the point at which the material is taken out, or if it is delayed even further, the resulting material may be unburned fuel or unburnt material. It will partially contain the mixture, resulting in poor quality. Conversely, if the BTP is too far from this end and closer to the ignition furnace, the capacity of the system will not be fully utilized. As a result, an unstable phenomenon occurs that is inconvenient for producing sintered ore of a certain quantity and quality.

It is therefore desirable to maintain the position of the BTP of the charge along the pallet at a predetermined location, usually close to the discharge end of the sintered material, and this position control is usually provided below the pallet. A common method was to measure the temperature of the exhaust gas sucked into 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 carrying the charge remains constant during most of the early part of the firing process;
It then increases to a maximum value and then decreases until it reaches the downstream end of the pallet. The appearance of this change is that the gas temperature remains almost constant while the material in contact with the pallet contains moisture, and after drying, the gas temperature rises to a maximum value, and in principle, BTP is reached at this point. This can be explained by the mechanism in which the gas temperature decreases as the fuel reaches the pallet floor (grate) and then burns out.

Conventionally, in response to such knowledge, when the temperature values corresponding to the positions of each measurement point are represented in a diagram and a temperature curve is created, the line is almost straight at the beginning, but becomes positive towards the end. It can be seen that the curve has a gradient curve, a maximum value, and a negative gradient curve. 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 sintering machine strand. In fact, other things being equal, increasing the pallet travel speed will bring the firing point closer to the downstream end of the pallet, while decreasing the speed will have the opposite effect.

Therefore, as a method for conducting sintering operations based on the above phenomenon, for example, as described in JP-A-51-139502, the permeability of the ore feeding section is measured, and the combustion front is determined based on the permeability measurement value. A method of predicting the descending speed of the pallet, calculating the pallet speed at which the raw material in the permeability measurement part should be transported from the predicted descending speed value and the material layer thickness, and outputting this pallet speed to a control device as the pallet speed, Japanese Unexamined Patent Publication No. 52-
As described in Publication No. 117203, the ore discharge temperature gradient in the ore discharge section is predicted based on the permeability of the ore feed section, the exhaust III temperature, and the preceding actual exhaust air temperature gradient in the exhaust section, and the passing air volume in the raw material packed bed is calculated. There are proposals for methods of adjusting the temperature gradient to minimize the deviation between the actual exhaust air temperature gradient of the ore discharge section and the set exhaust air temperature gradient of the ore discharge section.

In addition, in recent years, as a method of controlling this firing point in the width direction, for example, the method described in Japanese Patent Application Laid-open No. 13032/1983 (
, the discharge JI of each wind box measured in the width direction as the raw material moves
I A method of detecting firing points in each width direction based on temperature changes, calculating an average burning point in the width direction from this detected value, and adjusting the pallet speed so that this calculated value becomes a predetermined target value. As described in Publication No. 60-13033, the baking point is detected in each width direction based on the change in exhaust air temperature of each wind box measured in each width direction as the raw material moves, and the average baking point in the width direction is calculated from this detected value. From this width direction average firing point, pallet speed and material layer thickness, the width direction and layer thickness direction average burning speeds are calculated, and ore is fed onto the pallet grate bar so that this calculated value becomes a predetermined target value. There are ways to adjust raw materials, etc.

However, such conventional control based on TP detection is not satisfactory for the following reasons.

Since the temperature occurring along the sintering machine pallet depends on the composition of the various charges, the trajectory of the temperature curve is susceptible to uncontrollable factors such as the permeability and composition of the charges. In addition, the maximum region of the locus curve of the crystallinity of the gas to be measured is delayed due to the large heat capacity of the grate and the temperature is smoothed, making it very vague. Have difficulty.

This holds true even when the number of measurement points is increased.

Since it is also affected by the leakage rate of the wind box, the above-mentioned disadvantage has a significant disadvantage in that the position of the ambiguous maximum part changes more and more.

Furthermore, in the current sintering operation, there is no means to measure the true BTP, and the BTP determined from the exhaust gas temperature of the wind box is controlled empirically. Therefore, the control value of BTP needs to be changed depending on the influence of equipment, for example, deterioration of the air seal in the ore discharge section, air leakage due to holes in the wind box, etc. However, this control value is determined empirically by an operator who observes the baking state of the cake during ore discharge or analyzes the sintering quality once every 2 to 4 hours. Therefore, when considering the fluctuation of BTP, it cannot be said that it is always the correct BTP. In addition, if the BTP changes within a certain range due to changes in the air permeability of the raw materials, and if the BTP changes significantly toward the discharge side, the sintered cake on the pallet will be discharged unbaked, reducing the product yield. was there.

Problems to be Solved by the Invention The present invention aims to solve the above-mentioned problems, and specifically provides a method for controlling BTP determined from the exhaust gas temperature of a wind box in a sintering operation of a D[ type sintering machine. This solves problems such as the fact that the cake on the pallet is discharged unbaked, reducing the product yield, and that operating methods suitable for this type of sintering have not been sufficiently researched and developed. The purpose is to

Means for Solving the Problems and Their Effects That is, the present invention detects the firing completion point based on the exhaust gas temperature of the wind box during operation of the DL type sintering machine, and
The present invention is characterized in that the dust concentration in the ore discharge section of the sintering machine is measured, and the position of the sintering completion point is controlled in accordance with changes in this measured value.

Therefore, the structure of these means and their operation will be explained in more detail as follows.

The inventors of the present invention investigated the causes of the decrease in product yield, and found that the concentration of dust generated when unbaked cakes are discharged and crushed was significantly higher than in normal cases, and that unbaked cakes, i.e. , sintering was found to increase the occurrence of residual ore return. This is because, as shown in the graph showing the relationship between the dust concentration index (%) and the return ore generation ratio in Figure 4, the dust concentration index (%) at the discharged part increases with the increase in the generation of residual ore. Therefore, it is clear that the return generation ratio (%) is increasing with the increase.

Therefore, if the BTP is maintained properly, the dust will only be generated when the sintered ore is crushed by the crusher, the dust concentration will remain low and stable, and the amount of returned ore will be within a certain range. Presumed. Further research was conducted on operating conditions that satisfy these conditions, and the present invention was established based on this research.

Next, the configuration of the present invention will be explained in more detail as follows.

A sensor is installed to continuously measure the dust generated during the crushing of baked cakes, and if the dust concentration suddenly rises in a short period of time, it is determined that there is no baking remaining, and the pallet speed is reduced and the temperature is calculated from the exhaust gas temperature of the wind box at that time. The firing point (BTP) obtained by
This is a system that controls P.

Further, the present invention will be described in detail with reference to the drawings.

In addition, FIG. 1 is an explanatory diagram of the ore discharge section of the sintering machine used when carrying out the method of the present invention, and FIGS. 2 and 3 respectively show the operating time, BTP index, and dust concentration of one example. It is a graph showing the relationship between the index and the return ore generation ratio, and FIG. 4 is a graph showing the relationship between the dust concentration index and the return ore generation ratio in another example.

In FIG. 1, reference numeral 1 indicates a pallet, 2 a main duct, 3 a wind box, 4 a crusher, 5 a dust concentration meter, 6 an ore discharge hood, and 7 an air seal.

A crusher 4 is installed in the sintering ore discharge section of FIG. 1, and the sintered ore that has been fired is primarily crushed. Therefore,
During the sintering operation in which sintered ore remains in the sintered ore, when the sintered ore is crushed in the ore discharge section, the remaining part of the sintered ore is pulverized and the dust concentration increases, and this change is detected by the dust concentration meter 5. . Here, as the dust concentration meter 5, for example, a known detector consisting of a light emitter and a light receiver is used. This detector is installed in the ore discharge section or in the ore discharge section with a light emitter and a light receiver facing each other, and the amount of attenuation of the emitted light that changes depending on the dust concentration during this time is measured. Based on this measurement value, Dust concentration can be detected. The remaining sinter in the sintered ore results in an increase in the generation ratio of return ore.

Therefore, if the completion of calcination is maintained properly, dust will be generated only in the part that is generated during the primary crushing of the sintered ore by the crusher, and the concentration of dust 1 will remain low and stable, and the return ore will also be generated. It will stay within a certain amount. In other words, no 6
The firing state inside the pallet of the sintering machine can be determined by a single change.

Therefore, if the damage 61 degree increases, the detected BT
By reducing the pallet speed so that P moves toward the ignition furnace, even if it is difficult to detect the true BTP, corrective control can be performed according to the dust concentration as described above, so the optimal BTP can be determined.

In addition, as described in the prior art, BTP control is
If the BTP is moved too far toward the ignition furnace side, firing can be controlled to ensure completion, but the sintering function cannot be fully utilized.If the amount of BTP movement becomes large, adjust the pallet speed. Control may be performed in combination with changing the mixing ratio of coke.

Additionally, this method can also be used to detect changes in the sintering raw material and can be used to switch sintering operations in the event of a long-term change in dust concentration.

An example of this embodiment will be explained with reference to FIG. Figure 2 shows the BTP index (%) versus sintering time (1) in sintering operation.
), the dust concentration index (%), and the return ore generation ratio (%) are plotted on a graph, and the 8-hour moving average value (X) of the dust concentration index (X) and the concentration standard deviation (σ
) is calculated, and a line of this moving average value (X) and the 2σ control limit value of the dust concentration index is set on the graph of the dust concentration index (%). A state in which the measured value of the dust concentration index exceeds 2σ with respect to the moving average value (X) is determined to be abnormal, and if this abnormality is determined to be due to a change in the sintering raw material, the coke blending ratio is changed. , can be used as a method for performing the control.

According to Figure 2, it can be seen that the return ore generation ratio (%) increases by about 5% as the dust concentration index (%) rapidly increases.

In addition, the BTP index (%) at that time also increased, indicating that the sintering was due to an increase in return ore due to the discharge of unfired cakes due to residual sintering.

In Figure 2, the BTP index (%) indicates the position of the BTP measured by wind box temperature measurement.The length of the temperature measurement range in the direction of the aircraft captain is assumed to be 100%, and in which part of this range the BTP is located. It shows the location where the ore was located, and the end of the ore discharge side is shown as 100% in the measurement range.
As mentioned above, the change in the dust concentration index (%) in the figure shows that sintering has sufficient accuracy to detect the remaining B
When dealing with TP, it was found that BTP was also moving toward the ore discharge side as the dust concentration increased rapidly, and it was clearly detected that the calcination was delayed.

Therefore, by controlling the position of the BTP based on the dust concentration, it is possible to easily prevent burning from remaining.

Example 3 shows the measured values of BTP index (%), dust concentration index (%), and return ore generation ratio (%) plotted against the operating time when producing sintered ore using an OL type sintering machine. Shown in the figure. In addition, the control limit of the dust index (%) in FIG. 3 is based on the 8-hour moving average fl[(X) and its deviation value, 2σ. In step 1 of Fig. 3, a 2σ deviation of the dust concentration index (%) occurred, and the formation of a residual portion of charring was detected, so in step 2, the target value of the BTP index (%) was lowered by about 5% ( (moved to the ignition furnace side), the completion of sintering in the ore discharge area is strengthened, and the dust concentration index (%) is reduced to 2σ.
There is no longer any deviation from the limit value, and no abnormal occurrences of return ore occur.

<Effects of the Invention> As explained above, the present invention detects the completion point of sintering based on the exhaust gas temperature of the wind box when operating a DU type sintering machine, and also detects the dust concentration in the ore discharge section of the sintering machine. is measured, and the position of the firing completion point is controlled according to changes in this measured value.

Therefore, according to the method of the present invention, sintering remains in the sintered ore is prevented, abnormal occurrence of return ore is almost eliminated, and the yield of finished products can be improved by at least about 1%.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the ore discharge section of the sintering machine used when carrying out the method of the present invention, and Figs. 2 and 3 respectively show the operating time, BTP index, dust concentration index, and return ore of one embodiment. FIG. 4 is a graph showing the relationship between the dust concentration index and the return ore generation ratio in another example. Code 1... Pallet 2... Main duct 3... Wind box 4...
・Crusher 5... Dust concentration meter 6...
... Mine exhaust hood 7 ... Air seal

Claims (1)

[Claims] 1) When operating the DL type sintering machine, the sintering completion point is detected based on the exhaust gas temperature of the wind box, and the dust concentration in the ore discharge section of the sintering machine is measured, and the dust concentration is determined according to changes in this measured value. DL characterized in that the position of the firing completion point is controlled.
How to operate a type sintering machine.