JP2011075195A - Clogging detecting method and control method for rotary kiln - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a clogging detection method and a control method for a rotary kiln 1, which detect the clogging of the rotary kiln 1 and perform control to make the operating condition of the rotary kiln 1 appropriate based on the detection by a simple method. <P>SOLUTION: During the operation of the rotary kiln 1 for rotating a cylinder 11A and heating a material 71 while supplying the material 71 inside the cylinder 11A by a screw feeder 10, an electric current value of an electric motor M2 rotating and driving the screw feeder 10 is measured. When the electric current value exceeds a certain fixed value, the rotation of an electric motor M1 rotating and driving the cylinder 11A of the rotary kiln 1 is accelerated. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a clogging detection method and control method for a rotary kiln.

  A rotary kiln is an apparatus used for heating or baking or drying powdery or lump-like objects in a rotating cylinder.

  Patent Document 1 describes a rotary kiln 1 as shown in FIG. The screw feeder 10 rotates the inner cylinder 11 while supplying the raw material 71 toward the inside of the inner cylinder 11, and the high temperature for heating from the combustion furnace 2 through the supply pipe 20 between the outer cylinder 12 and the inner cylinder 11. Supply gas. Reference numeral 4 denotes a suction fan, which discharges the gas used for heating through the exhaust pipe 21 inserted through the flow rate adjusting valve 3 into the atmosphere. Then, the fired object 72 is discharged from the chute 15. At the same time, gas 73 and the like generated by thermal decomposition are also discharged. Reference numerals 13 and 14 denote support members that rotatably support the inner cylinder 11. The rotary kiln of the type described in Patent Document 1 that applies heat from the outside of the cylinder is called an external heating type. Steam or hot air is used to apply heat from outside the cylinder.

  On the other hand, as shown in, for example, Patent Document 2, there is a type called an internal heating type in which heat is applied from the inside of a cylinder as shown in FIG. 9 is a feeder, 11A is a cylinder, 22 is a burner flame, and 71 is a raw material.

  Now, during the operation of the rotary kiln, due to fluctuations in the nature and moisture of the raw material, the fluidity of the raw material decreases and stays in the cylinder, or the raw material being baked or dried adheres to the inner wall of the cylinder and accumulates. May become clogged with deposits, resulting in a situation in which a new raw material can no longer be supplied into the cylinder. Thus, a method has been sought that can prevent such a situation from occurring by optimizing operating conditions such as the rotational speed of the cylinder and the temperature at which the raw material is heated.

  In Patent Document 3, vibrations caused by deposits when the cylinder rotates are captured, and when the value exceeds a specified value, burner flames are injected to melt the deposits and prevent the cylinder from being blocked.

  In Patent Document 4, the amount of coaching (the dissolved raw material adheres to the inner wall of the cylinder) is computer-simulated so that the heat flux for heating does not exceed a certain value.

  In Patent Document 5, the temperature of the inner wall of the cylinder is locally captured, the thickness of the deposited layer is estimated, and adjustment such as reducing the supply of the raw material when the deposited layer becomes too thick is sufficient for the raw material. I try to spread the heat.

  In Patent Document 6, the temperature of the outer wall of the cylinder is continuously captured, the evaluation value of the state of deposit formation on the inner wall is calculated, and if the value falls below a certain value, the heating is weakened and the surface of the deposit is cooled and solidified. It is made to peel and remove.

JP 2008-180451 A JP 2001-289564 A JP 2008-215649 A JP 2009-103357 A JP-A-10-197157 Japanese Patent No. 3947609

  However, in the method of capturing vibration as in Patent Document 3, there is a problem that a burner flame is injected even when the cause of vibration is not an adhering substance. Requires a lot of time, labor, and cost, and there are problems that require time, labor, and cost for maintenance in later years, such as combining simulation results and results. The method of capturing the temperature of the inner wall or the outer wall locally or continuously also has the problem that the reliability or the reliability of the thermometer may be insufficient due to failure or breakage of the thermometer.

  The present invention was made to solve the above-described problems of the prior art, and can detect clogging of the rotary kiln with a simple method, and can be controlled to optimize the operating conditions of the rotary kiln based on the detection. It is an object of the present invention to provide a clogging detection method and control method for a rotary kiln.

That is, the present invention is as follows.
(1) During the operation of the rotary kiln that rotates the cylinder and heats the raw material while supplying the raw material to the inside of the cylinder by the screw feeder, the current value of the electric motor that rotationally drives the screw feeder is measured. A method of controlling a rotary kiln characterized by accelerating the rotation of an electric motor that rotationally drives the cylinder of the rotary kiln when a certain value is exceeded.
(2) During the operation of the rotary kiln that rotates the cylinder and heats the raw material while supplying the raw material toward the inside of the cylinder by the screw feeder, the current value of the electric motor that rotationally drives the screw feeder is measured. A method of controlling a rotary kiln characterized by accelerating the rotation of an electric motor that rotationally drives the cylinder of the rotary kiln and reducing the supply of the raw material to the screw feeder when a certain value is exceeded.
(3) During the operation of the rotary kiln that rotates the cylinder and heats the raw material while supplying the raw material to the inside of the cylinder by the screw feeder, the current value of the electric motor that rotationally drives the screw feeder is measured. A method of controlling a rotary kiln characterized by decelerating the rotation of an electric motor that rotationally drives the screw feeder when a certain value is exceeded.
(4) During the operation of the rotary kiln that rotates the cylinder and heats the raw material while supplying the raw material toward the inside of the cylinder by the screw feeder, the current value of the electric motor that rotationally drives the screw feeder is measured. A method for controlling a rotary kiln characterized by reducing the rotation of an electric motor that rotationally drives the screw feeder and reducing the supply of the raw material to the screw feeder when a certain value is exceeded.
(5) During the operation of the rotary kiln that rotates the cylinder and heats the raw material while supplying the raw material toward the inside of the cylinder by the screw feeder, the current value of the electric motor that rotationally drives the screw feeder is measured. A method for detecting clogging of a rotary kiln, wherein the clogging of the rotary kiln is detected when a certain value is exceeded.

  According to the present invention, the clogging of the rotary kiln can be detected by a simple method, and control can be performed to optimize the operating conditions of the rotary kiln based on the clogging.

Diagram for explaining an example of an embodiment of the present invention Diagram for explaining an example of an embodiment of the present invention Diagram for explaining an example of an embodiment of the present invention Diagram for explaining the prior art Diagram for explaining the prior art

  (First Embodiment) FIG. 1 shows an example of an embodiment of the present invention. 11A is a cylinder, and 16 is a raw material supply facility. Except that the cylinder 11A of the conventional rotary kiln 1 shown in FIG. The system configuration is followed in a broad manner. The support members 13 and 14 are not shown. M1 is an electric motor that rotationally drives the cylinder 11A, and M2 is an electric motor that rotationally drives the screw feeder 10.

  The control device 5 receives a raw material supply amount setting value per unit time. The raw material supply amount set value per unit time may be fixedly stored in a memory in the control device 5, or may be input for each type of raw material from another computer (not shown). Good. The raw material supply amount per unit time may be set by the raw material supply weight per unit time or by the raw material supply volume.

  In any case, in the control device 5, the rotational speed of the electric motor M1 that rotationally drives the cylinder 11A and the rotational speed of the electric motor M2 that rotationally drives the screw feeder 10 to realize the raw material supply amount set value per unit time. The operation speed of the raw material supply facility 16 is output, and the motor M1 that rotationally drives the cylinder 11A, the electric motor M2 that rotationally drives the screw feeder 10, and the raw material supply facility 16 are instructed. The case where the rotational speed of the electric motor M2 is linked to the commercial AC frequency corresponds to outputting the rotational speed referred to here.

  However, even if the material supply amount setting value per unit time is realized, the required critical value of the material supply amount per unit time is realized for the electric motor M2 that rotationally drives the screw feeder 10. On the other hand, for the electric motor M1 that rotationally drives the cylinder 11A, the rotational speed is set so as to realize a required raw material supply amount per unit time or a raw material supply amount exceeding it. It is better to control it to be 2% to 3% larger than the critical value. This is because it is easier to prevent clogging of the cylinder 11A in the first place when the rotational speed is controlled to be large so as to realize a raw material supply amount exceeding the critical value of the raw material supply amount per unit time.

  Although not shown, the motor M2 that rotationally drives the screw feeder 10 is such that once the rotation speed is commanded, the cylinder 11A is blocked by adhering matter, and the raw material can no longer be newly supplied into the cylinder 11A. Therefore, even if the load torque of the electric motor M2 rises, in order to maintain the commanded rotational speed, the current supplied to the electric motor M2 is increased to increase the output torque, and the increase in the load torque is resisted. The system is instructed by the control device 5.

  That is, the current supplied to the electric motor M <b> 2 that rotationally drives the screw feeder 10 is input to the control device 5. And in order to maintain the rotation speed of the electric motor M2 which rotationally drives the screw feeder 10, in the control apparatus 5, toward the electric motor M2 so that the electric current which should be supplied to the electric motor M2 is raised / lowered according to the magnitude of load torque. It is a mechanism to command.

  Now, in this embodiment, when the cylinder 11A is blocked by deposits and the raw material can no longer be newly supplied into the cylinder 11A, the electric motor M2 that rotationally drives the screw feeder 10 as described above is provided. In order to resist the increase of the load torque, as the current value increases, a certain value is set as the current value of the electric motor M2 for determining that the cylinder 11A is blocked, that is, the rotary kiln 1 is clogged. The data is input to the control device 5. Alternatively, the set value of the current value of the electric motor M2 for determining that the rotary kiln 1 is clogged may be stored in a memory in the control device 5 in a fixed manner.

  The set value of the current value of the electric motor M2 for determining that the rotary kiln 1 is clogged is preferably 1.6 to 2.0 times the average value of the current when there is no clogging.

  By adopting the configuration as described above, in the present invention, the screw feeder 10 is operated during the operation of the rotary kiln 1 that rotates the cylinder 11A and heats the raw material 71 while supplying the raw material 71 to the inside of the cylinder 11A by the screw feeder 10. The current value of the electric motor M2 that is driven to rotate is measured, and the clogging of the rotary kiln 1 is detected when the current value exceeds a certain value.

  When the clogging of the rotary kiln 1 is detected, the rotation of the electric motor M1 that rotationally drives the cylinder 11A of the rotary kiln 1 is accelerated. By doing so, the process of the raw material in baking or drying is accelerated in the cylinder 11A, and it goes to the side by which clogging is eliminated. The acceleration is preferably performed by an appropriate value within the range of 5 to 10% of the rotational speed up to that time.

  (Second Embodiment) In this embodiment, the supply of the raw material to the screw feeder 10 is further reduced in the first embodiment. By reducing the supply of the raw material to the screw feeder 10, the raw material newly input into the cylinder 11A is reduced, and clogging is eliminated more quickly. It is preferable that the rate of reduction is set to an appropriate value within a range of 10 to 20% of the raw material supply amount per unit time.

  In order to reduce the supply of the raw material to the screw feeder 10, the operation speed of the raw material supply facility 16 is lowered.

  In the first and second embodiments, as the rotation of the electric motor M1 that rotationally drives the cylinder 11A of the rotary kiln 1 is accelerated, the heating steam flow rate is increased by a value corresponding to the accelerated amount. You may make it reset. For example, when accelerating the rotation of the electric motor M1 that rotationally drives the cylinder 11A of the rotary kiln 1 by 5% or more, the steam flow rate for heating is also 5% for 1% of the acceleration of the rotation of the electric motor M1 that rotationally drives the cylinder 11A of the rotary kiln 1. It is a condition of making it up.

  (Third Embodiment) In the present embodiment, instead of accelerating the rotation of the cylinder of the rotary kiln in the first embodiment, the rotation of the electric motor M2 that rotationally drives the screw feeder 10 is decelerated. By doing so, the raw material newly input into the cylinder 11 </ b> A is reduced, and it is directed to the side where clogging is eliminated. The deceleration is preferably performed by an appropriate value within a range of 10 to 20% of the rotational speed up to that time. Of course, in this case, the electric motor M2 that rotationally drives the screw feeder 10 is not linked to the commercial AC frequency, and the rotation speed is variably controlled.

  In addition, if the supply of the raw material to the screw feeder 10 is not reduced while reducing the rotation of the electric motor M2 that rotationally drives the screw feeder 10, the raw material 71 is a bucket 17 between the raw material supply facility 16 and the screw feeder 10. There may be a suspicion that it may overflow, but there is no problem if the overflowing raw material 71 is collected manually and returned to the raw material supply facility 16 again. Within the scope of the invention.

  (Fourth Embodiment) In the present embodiment, instead of accelerating the rotation of the cylinder of the rotary kiln in the second embodiment, the rotation of the electric motor M2 that rotationally drives the screw feeder 10 is decelerated. That is, the rotation of the electric motor M2 that rotationally drives the screw feeder 10 is decelerated, and the supply of the raw material to the screw feeder 10 is reduced. By doing so, the raw material newly input into the cylinder 11A is reduced, and the point toward the side where clogging is eliminated earlier is the same as in the second embodiment.

  As can be seen from the description of each of the above embodiments, according to the present invention, there is a problem of injecting a burner flame even when the cause of vibration is not a deposit, such as a method of capturing vibration, or a method by computer simulation. In addition, there is no problem of time, labor and cost for maintenance such as software development and integration with actual results, and reliability problems of thermometers such as the method of capturing the temperature of the inner wall or outer wall of the cylinder, etc. The clogging of the rotary kiln can be detected by a simple and reliable method with high reliability, and based on this, it can be controlled to optimize the operating conditions of the rotary kiln.

  The electric motor M2 that rotationally drives the screw feeder 10 hardly breaks down (in the first place, the operation of the rotary kiln 1 must be stopped unless it breaks down and moves). And the electric current value supplied to an electric motor can be measured simply. In the first place, a standard electric motor is usually accompanied by a function of measuring and displaying a current value. Therefore, according to the present invention, as long as the operation of the rotary kiln 1 can be continued, the clogging of the rotary kiln can be detected by a simple and reliable method with little failure, and control is performed so as to optimize the operating conditions of the rotary kiln based on the clogging. It can be done.

  In addition, although each embodiment described above demonstrated the case of the external-heat-type rotary kiln as an example, this invention is not limited to this, Even if it is the case of an internal-heat-type rotary kiln, it can apply similarly. .

  FIG. 2 shows an example of the processing flow of the method of the present invention. The rotational speed setting value of the motor M1 that rotationally drives the cylinder 11A is R (rpm), the rotational speed setting value of the motor M2 that rotationally drives the screw feeder 10 is R '(rpm), and the operating speed of the raw material supply equipment 16 is v (T / hr) is set (Step 10), and the rotary kiln 1 is started to operate (Step 20). A heating steam flow rate Q (T / hr) corresponding to R (rpm) is set as a setting value of the rotational speed of the electric motor M1 that rotationally drives the cylinder 11A. Thereafter, the current value supplied to the electric motor M2 that rotationally drives the screw feeder 10 is checked (Step 30). If the current value exceeds the set value A of the current value of the electric motor M2 for determining that the rotary kiln 1 is clogged, it is determined that the rotary kiln 1 is clogged (Step 40).

  Then, the set value of the rotational speed of the electric motor M1 that rotationally drives the cylinder 11A is increased by ΔR (rpm) to accelerate the rotation of the electric motor M1 that rotationally drives the cylinder 11A of the rotary kiln 1 (Step 50) (first embodiment). ). It should be noted that the heating steam flow rate may be reset to a value that is large enough to match the acceleration.

  If the current value supplied to the electric motor M2 that rotationally drives the screw feeder 10 does not exceed the set value A of the electric current value of the electric motor M2 for determining that the rotary kiln 1 is clogged at Step 30, the cylinder 11A of the rotary kiln 1 Does not accelerate.

  If the fixed time T1 has elapsed (Step 60) and the operation stop input of the rotary kiln 1 has not been made by an operator or the like (Step 70), the set value of the rotational speed of the electric motor M1 that rotationally drives the cylinder 11A is set to R (rpm). It is set again (Step 80), and the processing after Step 30 is repeated. If the operation stop input of the rotary kiln 1 is input (Step 70), the operation of the rotary kiln 1 is stopped (Step 100).

  If it is determined in Step 40 that the rotary kiln 1 is clogged, the set value of the rotational speed of the electric motor M1 that rotationally drives the cylinder 11A is increased by ΔR (rpm), and the electric motor M1 that rotationally drives the cylinder 11A of the rotary kiln 1 (Step 50), the operation speed set value of the raw material supply facility 16 may be reduced by Δv (T / hr) to reduce the supply of the raw material to the screw feeder 10 (Step 90) (Step 90). Second embodiment).

  In addition, about 3rd embodiment, it replaces with accelerating the rotation of the electric motor M1 which rotationally drives the cylinder 11A of the rotary kiln 1 in Step50 of 1st embodiment, as shown in FIG. In addition to decelerating the rotation of the electric motor M2 that rotationally drives the screw, the screw feeder 10 is rotated at Step 80 instead of setting the rotational speed of the electric motor M1 that rotationally drives the cylinder 11A to R (rpm) again. Since only the setting value of the rotational speed of the electric motor M2 to be driven is set again to R ′ (rpm), the description is omitted.

  Further, in the first embodiment, when clogging is detected, the steam flow rate for heating is increased as much as the rotation of the electric motor M1 that rotates the cylinder 11A of the rotary kiln 1 is accelerated. However, in the third embodiment, if the rotation of the motor M1 that rotationally drives the cylinder 11A of the rotary kiln 1 is not accelerated, the heating steam flow rate is set to a larger value than before. There is no need to set it again.

  In the fourth embodiment, as shown in FIG. 3, instead of accelerating the rotation of the electric motor M <b> 1 that rotationally drives the cylinder 11 </ b> A of the rotary kiln 1 in Step 50 of the second embodiment, the screw feeder 10. In addition to decelerating the rotation of the electric motor M2 that rotationally drives the screw, the screw feeder 10 is rotated at Step 80 instead of setting the rotational speed of the electric motor M1 that rotationally drives the cylinder 11A to R (rpm) again. Since only the setting value of the rotational speed of the electric motor M2 to be driven is set again to R ′ (rpm), the description is omitted.

  In the first embodiment, when clogging is detected, as the rotation of the motor M1 that rotationally drives the cylinder 11A of the rotary kiln 1 is accelerated, the steam flow for heating is also large enough to meet the acceleration. However, in the fourth embodiment, if the rotation of the electric motor M1 that rotationally drives the cylinder 11A of the rotary kiln 1 is not accelerated, the heating steam flow rate is set to a larger value than before. There is no need to set it again. This is the same as in the third embodiment.

  Lastly, the above description has been given of the case where steam is used to heat the cylinder 11A, but it goes without saying that other media such as hot air may be used.

  In a tempered coal facility for drying coal, the feed rate per unit time is 340 T / hr in a rotary kiln with an inner diameter of 37.5 m, a length of 27.0 m, a slope of 8%, and a rotation speed of 4.4 rpm. When the first embodiment of the present invention described with reference to FIG. 1 is applied to the operating conditions in which the moisture is 8.5% by mass and dried to 6.0% by mass after drying, compared to the conventional case, Can reduce the steam unit consumption by 2%. At this time, the set value of the current value of the electric motor of the screw feeder for determining clogging is 41A, and the acceleration ΔR of the rotation of the electric motor M1 that rotationally drives the cylinder 11A is 5% of the number of rotations at the time of detecting clogging. is there.

  The reason for the reduction of the steam consumption rate is that, in the past, in order to prevent clogging regardless of the nature and moisture of the raw material, the rotation speed of the cylinder is set to a large value, and more steam for heating is used. This is because, according to the present invention, the heating steam can be set to an appropriate value.

DESCRIPTION OF SYMBOLS 1 Rotary kiln 2 Combustion furnace 3 Flow control valve 4 Suction fan 5 Control apparatus 9 Feeder 10 Screw feeder 11 Inner cylinder 11A Cylinder 12 Outer cylinder 13,14 Support member 15 Chute 16 Raw material supply equipment 17 Bucket 20 Supply pipe 21 Discharge pipe 22 Burner flame 71 Raw material 72 Firing object 73 Gas generated by pyrolysis M1, M2 Electric motor

Claims (5)

  During the operation of the rotary kiln that heats the raw material by rotating the cylinder while supplying the raw material to the inside of the cylinder by the screw feeder, the current value of the electric motor that rotationally drives the screw feeder is measured, and the current value is constant. A rotary kiln control method characterized by accelerating the rotation of an electric motor that rotationally drives the cylinder of the rotary kiln when a value is exceeded.   During the operation of the rotary kiln that heats the raw material by rotating the cylinder while supplying the raw material to the inside of the cylinder by the screw feeder, the current value of the electric motor that rotationally drives the screw feeder is measured, and the current value is constant. A rotary kiln control method characterized by accelerating the rotation of an electric motor that rotationally drives the cylinder of the rotary kiln and reducing the supply of the raw material to the screw feeder when the value is exceeded.   During the operation of the rotary kiln that heats the raw material by rotating the cylinder while supplying the raw material to the inside of the cylinder by the screw feeder, the current value of the electric motor that rotationally drives the screw feeder is measured, and the current value is constant. A rotary kiln control method characterized by decelerating the rotation of an electric motor that rotationally drives the screw feeder when a value is exceeded.   During the operation of the rotary kiln that heats the raw material by rotating the cylinder while supplying the raw material to the inside of the cylinder by the screw feeder, the current value of the electric motor that rotationally drives the screw feeder is measured, and the current value is constant. When the value is exceeded, the rotation of the electric motor that rotates the screw feeder is decelerated, and the supply of the raw material to the screw feeder is reduced.   During the operation of the rotary kiln that heats the raw material by rotating the cylinder while supplying the raw material to the inside of the cylinder by the screw feeder, the current value of the electric motor that rotationally drives the screw feeder is measured, and the current value is constant. A method for detecting clogging of a rotary kiln, wherein the clogging of the rotary kiln is detected when the value is exceeded.

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