JP3947609B2 - Operation control method and apparatus for rotary kiln - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rotary kiln operation control method and apparatus, and more particularly, to a control method and apparatus capable of performing a stable continuous firing operation by removing deposits on the inner wall surface of a rotary kiln.
[0002]
[Prior art]
In rotary kilns in which raw materials to be fired such as cement raw materials are fed and fired, a part of the raw materials adheres and grows on the inner wall surface of the rotary kiln as an adhering substance. It causes obstacles and makes it difficult to operate the rotary kiln stably.
When deposits are formed on the inner wall surface of the rotary kiln, the deposits act as a heat insulating material, so that the shell temperature of the rotary kiln is lowered. Therefore, conventionally, the overall shell temperature of the rotary kiln that is in operation is measured, the formation state of deposits is estimated from the shell temperature, and if it is determined that deposits exceeding the allowable value have been generated, the rotary kiln is temporarily The operation was stopped to remove deposits.
[0003]
[Problems to be solved by the invention]
However, from the overall shell temperature of the rotary kiln, the amount of deposits could not be accurately grasped, and it was difficult to efficiently remove the deposits.
There is also a method of visually observing the state of deposit formation from the inspection window provided at the mouth of the rotary kiln, that is, the discharge side end of the baked product, but the view inside the rotary kiln is limited by the frame from the burner and scattered dust. Therefore, it is difficult to accurately grasp the amount of deposits.
Further, Japanese Patent Laid-Open No. 56-137106 discloses a method for detecting the thickness of deposits in an operating rotary kiln by measuring the atmospheric temperature, the gas temperature in the furnace of the rotary kiln, and the outer skin surface temperature of the rotary kiln. However, it is difficult to accurately measure the furnace gas temperature throughout the kiln, and it is impractical to apply this method to an actual production kiln in operation.
[0004]
The present invention was made to solve such problems, and by detecting the formation / growth of deposits on the inner wall surface of the rotary kiln during operation and removing it, a stable continuous firing operation can be achieved. An object of the present invention is to provide an operation control method and apparatus for a rotary kiln that can be performed.
[0005]
[Means for Solving the Problems]
The operation control method of the rotary kiln according to the present invention continuously measures the shell temperature at a plurality of measurement points distributed over the entire outer peripheral surface of the rotary kiln in operation, and each measurement point within a predetermined area on the outer peripheral surface of the rotary kiln. When the evaluation value for evaluating the generation state of the deposit on the inner wall surface of the kiln is calculated based on the shell temperature at, and when the calculated evaluation value falls below the preset deposit removal operation start reference value, normal operation is performed. After increasing the thermal load in the rotary kiln to melt and peel the deposit on the inner wall of the kiln, the thermal load in the rotary kiln is sharply decreased to cool and harden the surface of the peeled deposit and use this as a clinker to remove it from the rotary kiln. There rows deposit removal operation which, as an evaluation value, (a) a specific length direction position odor rotary kilns The minimum value of the shell temperature at a plurality of measurement points distributed along the circumferential direction, and (b) the minimum value of the shell temperature at the plurality of measurement points distributed along the circumferential direction at a specific longitudinal position of the rotary kiln. This is a method using any one of a time average value obtained by dividing by a maximum value and (c) a product of a weighted average value of shell temperature at each measurement point and a surface area of the area in a predetermined area .
[0006]
Furthermore, after starting the deposit removal operation, if the calculated evaluation value exceeds the preset reference value for the deposit removal operation, it is determined that all deposits have been discharged and removed from the rotary kiln as a clinker. It is also possible to end the operation and return to normal operation.
[0008]
Further, the operation control device for a rotary kiln according to the present invention is supplied to a thermometer for continuously measuring the shell temperature at each of a plurality of measurement points distributed over the entire outer peripheral surface of the rotary kiln in operation, and a firing burner. Flow rate adjustment valve that adjusts the amount of fuel to be produced, raw material metering machine that feeds raw material into the rotary kiln, kiln motor that rotates the rotary kiln, and the generation status of deposits on the inner wall surface of the kiln from the shell temperature measured by the thermometer When the calculated evaluation value falls below a predetermined deposit removal operation start reference value, the heat in the rotary kiln is controlled by controlling the flow rate adjusting valve, the raw material metering machine, and the kiln motor. Heat load in the rotary kiln after increasing the load and fusing and peeling the deposits on the inner wall of the kiln To chill the surface of the peeled rapidly reduced deposits and a controller for discharging removed from rotary kiln this as clinker, as an evaluation value, along the circumferential direction in a specific longitudinal position of (a) a rotary kiln The lowest value of the shell temperature at a plurality of measurement points distributed, (b) the lowest value of the shell temperature at a plurality of measurement points distributed along the circumferential direction at a specific longitudinal position of the rotary kiln divided by the highest value. Any one of the time average value of the values and (c) the product of the weighted average value of the shell temperature at each measurement point in the predetermined area and the surface area of the area is used .
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings.
Embodiment 1 FIG.
FIG. 1 shows the configuration of an operation control device for a rotary kiln according to Embodiment 1 of the present invention. A rotary kiln 1 for firing a raw material to be fired such as a cement raw material is provided by a kiln motor 2 so as to be rotatable around its central axis. A preheater 3 is connected to the kiln bottom of the rotary kiln 1, and the raw material to be fired is supplied from the raw material metering machine 4 into the rotary kiln 1 via the preheater 3. A firing burner 5 is provided at the end of the rotary kiln 1 on the clinker outlet side, and a heavy oil tank 7 is connected to the burner 5 via a flow rate adjusting valve 6. Further, a cooler 8 for cooling the clinker generated in the rotary kiln 1 is provided on the clinker outlet side of the rotary kiln 1.
[0010]
A thermometer 9 capable of monitoring the entire outer peripheral surface of the rotary kiln 1 is disposed on the side of the rotary kiln 1, and a controller 10 that controls the kiln motor 2, the raw material metering machine 4 and the flow rate adjusting valve 6 is provided with this thermometer 9. It is connected to the. In addition, a kiln bottom thermometer 11 and a kiln bottom draft 13 are disposed near the kiln bottom of the rotary kiln 1, and a burning point thermometer 12 is disposed near the clinker exit, respectively. A drop clinker thermometer 14 is connected to the controller 10.
[0011]
As shown in FIG. 2, the controller 10 calculates the kiln shell temperature, the kiln bottom temperature, the burning point temperature, and the falling clinker temperature from the thermometers 9, 11, 12 and 14, respectively, to the A / D converter 21. The device 22, the comparator 23, and the determination device 24 are sequentially connected, and the operation device 25 for operating the kiln motor 2, the raw material metering device 4 and the flow rate adjusting valve 6 is connected to the determination device 24. Yes.
[0012]
The thermometer 9 can measure the shell temperature of the kiln at a plurality of measurement points distributed along the entire outer peripheral surface of the rotary kiln 1, that is, along the length direction and the circumferential direction of the kiln. The shell temperature at a certain point of the rotary kiln 1 in operation has a specific distribution not only in the length direction of the kiln but also in the circumferential direction depending on the structure of the kiln, but the shell temperature at a specific measurement point is also As shown in FIG. 3, it fluctuates greatly with the passage of operation time. This is because a part of the raw material adheres to the inner wall surface of the rotary kiln 1 as a deposit as the raw material to be fired is fired, and gradually grows and thickens, so that the layer of the deposit acts as a heat insulating material. is there. Deposit growth of deposits appears as a decrease in shell temperature. If the growth of this deposit is left as it is, the transfer and ventilation of the raw material in the rotary kiln 1 are hindered, and the stable operation of the rotary kiln 1 becomes difficult.
[0013]
Thus, for example, the lower limit Tmin = 150 ° C. with respect to the shell temperature at a plurality of measurement points distributed along the circumferential direction at a specific longitudinal position of the rotary kiln 1 has caused the need to remove the deposit. When it is determined that the shell temperature at a specific measurement point measured by the thermometer 9 from the operating rotary kiln 1 has become lower than the lower limit value Tmin, it is stored in advance in the controller 10 as a start reference value. While the rotary kiln 1 is in operation, the deposit removal operation is performed. Hereinafter, the operation of the operation control device for the rotary kiln according to the first embodiment will be described in detail.
[0014]
Usually, the controller 10 controls the kiln motor 2, the raw material metering machine 4, and the flow rate adjusting valve 6, the rotary kiln 1 rotates at a predetermined rotational speed, a predetermined amount of raw material is supplied into the rotary kiln 1, and the burning burner 5 A predetermined amount of heavy oil is supplied to the rotary kiln 1 and the raw material is fired. The fired raw material becomes a clinker and is discharged from the rotary kiln 1 and cooled by a cooler 8.
In such a firing process, the shell temperature at a plurality of measurement points distributed along the circumferential direction at a specific longitudinal position of the rotary kiln 1 is continuously measured by the thermometer 9 and input to the controller 10. In step S1 of the flowchart shown in FIG. 4, the controller 10 performs A / D conversion on the shell temperature at each measurement point input from the thermometer 9 with the A / D converter 21, and then calculates these temperatures with the calculator 22. The lowest value is calculated as the evaluation value D, and in step S2, the evaluation value D is compared with the preset adhering substance removal operation start reference value, that is, the lower limit value Tmin by the comparator 23. If the evaluation value D is determined to be greater than or equal to the reference value by the determiner 24, it is determined that the deposits attached to the inner wall surface of the rotary kiln 1 have not yet grown so as to hinder the operation, and the baking process is performed as it is. To continue. Then, as long as the evaluation value D is equal to or higher than the lower limit value Tmin, steps S1 to S2 are repeated.
[0015]
If the evaluation value D falls below the lower limit value Tmin, for example, at times t1 and t2 in FIG. 3 as a result of the determination by the determiner 24, deposits are removed from the inner wall surface of the rotary kiln 1 in order to perform stable operation. It is determined that it is necessary to remove, and the process proceeds to step S3, where the operation device 25 performs the deposit removal operation. That is, the heat load in the rotary kiln 1 is increased by controlling the kiln motor 2, the raw material metering machine 4 and the flow rate adjusting valve 6 to melt and peel the deposits on the inner wall surface of the kiln, and then the heat load in the rotary kiln 1 is rapidly increased. The surface of the deposit that has been reduced and peeled off from the inner wall surface of the kiln is cooled and cured, and this is discharged from the rotary kiln 1 to the cooler 8 as a clinker.
[0016]
After starting the deposit removal operation in this way, in step S4, the comparator 23 compares the evaluation value D calculated by the calculator 22 with a preset deposit removal operation end reference value Tend. . If the determination unit 24 determines that the evaluation value D is less than or equal to the reference value Tend for the deposit removal operation, it is determined that the deposit attached to the inner wall surface of the rotary kiln 1 has not been completely removed and is attached as it is. Continue the kimono removal operation. Then, when it is determined that the evaluation value D exceeds the adhering substance removal operation end reference value Tend, it is determined that the adhering substance has been completely removed, and in step S5, the amount of heavy oil supplied to the firing burner 5 by the operating unit 25, The number of rotations of the rotary kiln 1 and the amount of raw material fed into the rotary kiln 1 are returned to the normal firing state.
As described above, while the rotary kiln 1 is in operation, it is possible to detect the formation / growth of deposits on the inner wall surface of the kiln and remove them, thereby enabling a stable and continuous firing operation.
[0017]
In addition, although the controller 10 judged that it was necessary to remove the deposit from the inner wall surface of the kiln when the evaluation value D was lower than the reference value for starting the deposit removal operation, the controller 10 automatically performed the deposit removal operation. However, the present invention is not limited to this. When the evaluation value D is lower than the reference value for starting the deposit removal operation, an alarm is issued first, and the operator performs an operation necessary for removing the deposit based on this warning. May be.
[0018]
Embodiment 2. FIG.
In the first embodiment described above, shells at a plurality of measurement points distributed along the circumferential direction at specific longitudinal positions of the rotary kiln 1 are used as evaluation values for evaluating the state of formation of deposits on the inner wall surface of the kiln. Although the lowest value of temperature was used and this evaluation value was compared with a preset lower limit value Tmin, it is not limited to this. In the second embodiment, a time average value obtained by dividing the lowest value among the shell temperatures at a plurality of measurement points distributed along the circumferential direction at a specific longitudinal position of the rotary kiln 1 by the highest value. Evaluation value. Specifically, the highest value of the shell temperature at a plurality of measurement points is Ta, the lowest value is Tb, and the average value for a predetermined time of Tb / Ta, for example, 60 minutes or 30 minutes, is taken as the evaluation value E. This is because the evaluation value E can be evaluated without being affected by disturbances such as weather, temperature, and wind.
[0019]
The controller 10 stores in advance 0.5, for example, as the deposit removal operation start reference value Est, calculates the evaluation value E in step S11 of FIG. 5, and uses the evaluation value E as the deposit removal operation start reference in step S12. Compared with the value Est, when the evaluation value E is lower than the reference value Est, it is determined that it is necessary to remove the deposit from the inner wall surface of the kiln, and the rotary kiln 1 is set in step S13 as in the first embodiment. The deposit removal operation is performed while operating. Further, if it is determined in step S14 that the evaluation value E exceeds the preset adhering substance removal operation end reference value Eend, the amount of heavy oil supplied to the firing burner 5 in step S15, the rotational speed of the rotary kiln 1, and the rotary kiln The raw material feed amount to 1 is returned to the normal firing state. As a result, a stable continuous firing operation is possible.
[0020]
Embodiment 3 FIG.
In the third embodiment, the product of the weighted average value of the shell temperature at each measurement point existing in a predetermined area on the outer peripheral surface of the rotary kiln 1 and the surface area of the area is used as the evaluation value. The shell temperature at a certain point of the rotary kiln 1 in operation generally has a specific distribution not only in the length direction of the kiln but also in the circumferential direction according to the structure of the kiln. Therefore, taking into consideration its unique distribution, each of the measurement points existing in a given area is weighted, and the weighted average of the shell temperatures at these measurement points is taken. The weighted average shell temperature and the surface area of the area are taken. By calculating the product and using this as the evaluation value F, it is possible to accurately grasp the generation state of the deposit.
[0021]
The controller 10 stores the deposit removal operation start reference value Fst in advance, calculates the evaluation value F in step S21 of FIG. 6, and compares the evaluation value F with the deposit removal operation start reference value Fst in step S22. When the evaluation value F is lower than the reference value Fst, it is determined that it is necessary to remove the deposit from the inner wall surface of the kiln, and the deposit is operated while operating the rotary kiln 1 in the same manner as in the first embodiment in step S23. Perform the removal operation. Furthermore, if it is determined in step S24 that the evaluation value F exceeds the preset adhering substance removal operation end reference value Fend, the amount of heavy oil to be supplied to the firing burner 5 in step S25, the rotational speed of the rotary kiln 1, and the rotary kiln The raw material feed amount to 1 is returned to the normal firing state. As a result, a stable continuous firing operation is possible.
[0022]
Embodiment 4 FIG.
In the fourth embodiment, the controller 10 detects the highest value T among the shell temperatures at a plurality of measurement points distributed along the circumferential direction at a specific longitudinal position of the rotary kiln 1 in step S31 of FIG. In step S32, the maximum value T is compared with a preset upper limit value Tmax. When the maximum value T exceeds the upper limit value Tmax, it can be determined in step S33 that some abnormality has occurred in the refractory material constituting the inner wall surface of the rotary kiln 1.
[0023]
【The invention's effect】
As described above, according to the present invention, it is possible to detect the formation / growth of deposits on the inner wall surface of the kiln without removing the rotary kiln that is in operation, and to remove this, and stable continuous firing. Operation becomes possible.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an operation control device for a rotary kiln according to Embodiment 1 of the present invention.
FIG. 2 is a block diagram showing a configuration of a controller used in the operation control apparatus according to the first embodiment.
FIG. 3 is a diagram showing a temporal change in shell temperature measured by the thermometer in the first embodiment.
FIG. 4 is a flowchart showing the operation of the controller in the first embodiment.
FIG. 5 is a flowchart showing the operation of the controller in the second embodiment.
FIG. 6 is a flowchart showing the operation of the controller in the third embodiment.
FIG. 7 is a flowchart showing an operation of a controller in the fourth embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Rotary kiln 2 Kiln motor 3 Preheater 4 Raw material metering machine 5 Baking burner 6 Flow control valve 7 Heavy oil tank 8 Cooler 9 Thermometer 10 Controller 11 Kiln bottom thermometer 12 Burning point thermometer 13 Kiln bottom draft 14 Dropper clinker thermometer 21 A / D converter 22 Calculator 23 Comparator 24 Judger 25 Controller

Claims (3)

Continuously measure the shell temperature at each of a plurality of measurement points distributed over the entire outer peripheral surface of the rotary kiln in operation,
Based on the shell temperature at each measurement point in the predetermined area of the outer peripheral surface of the rotary kiln, the evaluation value for evaluating the production status of the deposit on the inner surface of the kiln is calculated,
When the calculated evaluation value falls below the preset reference value for starting the deposit removal operation, the heat load in the rotary kiln is increased from the normal operation, and the deposit on the inner wall surface of the kiln is melted and peeled off. rapidly reducing the surface of the peeled deposit to cool cured have rows deposit removal operation for discharging removed from rotary kiln this as clinker,
As the evaluation value,
(A) the minimum value of the shell temperature at a plurality of measurement points distributed along the circumferential direction at a specific longitudinal position of the rotary kiln;
(B) a time average value of a value obtained by dividing the minimum value of the shell temperature at a plurality of measurement points distributed along the circumferential direction at a specific longitudinal position of the rotary kiln by the maximum value; and
(C) The product of the weighted average value of the shell temperature at each measurement point in the predetermined area and the surface area of the area,
Any one of these is used , The operation control method of the rotary kiln characterized by the above-mentioned.   After starting the deposit removal operation, if the calculated evaluation value exceeds the preset reference value for the deposit removal operation, it is determined that all deposits have been discharged and removed from the rotary kiln as a clinker. The method of claim 1, wherein the method ends and returns to normal operation. A thermometer for continuously measuring the shell temperature at each of a plurality of measurement points distributed over the entire outer peripheral surface of the rotary kiln in operation;
A flow rate adjusting valve for adjusting the amount of fuel supplied to the burning burner;
A raw material metering machine for supplying raw materials into the rotary kiln;
A kiln motor that rotates the rotary kiln;
When calculating the evaluation value for evaluating the generation state of the deposit on the inner wall surface of the kiln from the shell temperature measured by the thermometer, and the calculated evaluation value is below a preset deposit removal operation start reference value By controlling the flow rate adjusting valve, the raw material metering machine and the kiln motor, the thermal load in the rotary kiln is increased and the deposit on the inner wall surface of the kiln is melted and peeled. A controller that cools and hardens the surface of the kimono and discharges it from the rotary kiln as a clinker, and the evaluation value is as follows :
(A) the minimum value of the shell temperature at a plurality of measurement points distributed along the circumferential direction at a specific longitudinal position of the rotary kiln;
(B) a time average value of a value obtained by dividing the minimum value of the shell temperature at a plurality of measurement points distributed along the circumferential direction at a specific longitudinal position of the rotary kiln by the maximum value; and
(C) The product of the weighted average value of the shell temperature at each measurement point in the predetermined area and the surface area of the area,
An operation control device for a rotary kiln characterized by using any of the above .

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