JP3845591B2 - Limestone preheating device and control method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention preheats limestone supplied from a charge bin and stored in a rotating bed by supplying limestone to a lower calcined part by extruding limestone with a pusher while preheating with exhaust gas from the calcined part at the lower part. More particularly, the present invention relates to a limestone preheating device for obtaining quick lime or the like of uniform quality and a control method therefor.
[Prior art]
FIG. 4 schematically shows an example of a typical vertical preheating apparatus. The preheating device includes a charge bin 10, a conveyor 20, a rotating bed 30, a pusher 40, and an exhaust gas duct 50. The charge bin 10 temporarily stores the limestone L supplied from the conveyor 20. The amount of limestone supplied by the conveyor 20 is variable. For example, a vibration feeder provided at the exit of a rough stone silo (not shown) and a belt conveyor (not shown) that receives and transports the limestone L from the rough stone silo. The temporary storage amount of the limestone L in the charge bottle 10 is maintained almost constant. The rotating bed 30 stores the limestone L dropped from the charge bin 10 through a plurality of (six) chutes 12, and the stored limestone L is preheated by the exhaust gas G. Six pushers 40 are provided, and are provided near the center of the rotary bed 30 by pressing the limestone L stored on the rotary bed 30 by reciprocating intermittently along the direction toward the center of the rotary bed 30. The pre-heated limestone L is dropped into the limestone supply port 32 thus formed. The pusher 40 is driven by, for example, a hydraulic cylinder. The dropped limestone L is supplied from the chute 12. Six exhaust gas ducts 50 are provided for exhausting the exhaust gas heat exchanged with the limestone L stored on the rotating bed 30, and each of the plurality of pushers 40 corresponds to each of the plurality of pushers 40. Each is arranged above. Six sets including the chute 12, the pusher 40, and the exhaust gas duct 50 are provided. The preheated limestone L is supplied to the lower firing unit 60 to generate quick lime. The exhaust gas G is supplied from the firing unit 60. Each pusher 40 operates at a predetermined interval, and after the operation of the pusher 40, the rotary bed 30 rotates 1/32 around the vertical axis. Such a configuration is used as a pre-tropical part of a top-type baking furnace, a preheating device for a rotary kiln, or a reheating furnace.
[0002]
The limestone L stored in the rotating bed 30 is supplied to the lower firing unit 60 by the pusher 40, and it is assumed that the push-out amount of one pusher (one stroke) is constant. Was driving according to. However, in practice, the push-out amount for each pusher 40 (one stroke) varies, and the supply amount to the lower firing section 60 cannot be accurately controlled. This is due to differences in the shape and size of limestone and the temperature preheated on the rotating bed. As shown in the figure, the limestone L on the rotating bed 30 stays at the angle of repose, and the portion pushed out by the pusher 40 is replenished from the charge bin 10. Therefore, when the shape and size of the limestone L change, the angle of repose also changes, and the amount of drop in one operation of the pusher 40 and the time preheated on the rotating bed 30 for each limestone change. Further, depending on the degree of filling of the limestone L, even if the pusher 40 is operated, the limestone L is not dropped simply by increasing the packing density, or the limestone L in the portion where the temperature is excessively increased is sintered and bonded to each other. Sometimes it could not be supplied smoothly.
[0003]
As described above, in the configuration as shown in FIG. 4, there is a problem that quick lime of uniform quality is difficult to obtain because the amount of limestone supplied to the firing section is not stable.
[0004]
[Problems to be solved by the invention]
An object of the present invention is to provide a limestone preheating apparatus and a control method thereof that can maintain uniform heating conditions and obtain uniform quality quicklime by maintaining a constant amount of limestone supplied to the calcining section. It is to provide.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a charge bin in which limestone is temporarily stored, a limestone dropped from the charge bin through a chute, and a rotating bed on which the stored limestone is preheated by gas. And the limestone stored on the rotating bed by reciprocating intermittently along the direction toward the center of the rotating bed, and preheated to the limestone supply port provided near the center of the rotating bed. A limestone preheating device including at least one pusher for dropping limestone, wherein a substantially constant amount of limestone is continuously supplied to the charge bin every unit time, and the operation of the pusher is performed in the charge bin. The limestone preheating device was configured so that the temporary storage amount of limestone was controlled to be a substantially constant amount.
[0006]
In the limestone preheating device according to the first aspect of the invention, a substantially constant amount of limestone is continuously supplied to the charge bin every unit time, and the temporary storage amount of limestone in the charge bin is determined by the operation of the pusher. By controlling, a substantially constant amount is maintained. Therefore, the preheated limestone is almost constant per unit time compared to the conventional example in which the temporary storage amount of limestone in the charge bin is kept constant by adjusting the amount of limestone supplied to the charge bin. The quantity can be obtained, and thereby heating conditions can be appropriately maintained to produce quick lime of uniform quality. However, the amount of limestone continuously supplied to the charge bottle is not constant and can be adjusted in advance according to the reaction conditions such as the properties of the raw material and temperature, the quality of the limestone to be produced, etc. Needless to say, it may change.
[0007]
The operation of the pusher can also control the stroke amount and the pressing speed. Preferably, as in the invention described in claim 2, the pusher is operated at an operation interval when the temporary storage amount is larger than the substantially constant amount. Is controlled to be shorter, and when it is less, the operation interval is longer. As a result, when the amount of temporary storage is greater than a certain amount, more limestone is dropped into the limestone supply port, and when it is less, the amount of limestone dropped is reduced, and the amount of temporary storage of limestone in the charge bottle is constant. Can be held in.
[0008]
The invention according to claim 3 is a temporary storage amount measuring means for measuring a temporary storage amount of limestone temporarily stored in the charge bin, and a temporary storage amount signal is input from the temporary storage amount measurement means, The temporary storage amount based on the storage amount signal is compared with a predetermined reference temporary storage amount, and when the deviation between both exceeds a predetermined value, the operation interval of the pusher is increased or decreased so that the deviation decreases. A limestone preheating device according to claim 2 is provided. According to such a configuration, the temporary storage amount signal is input to the pusher control unit from the temporary storage amount measuring unit that measures the temporary storage amount of limestone temporarily stored in the charge bin. The pusher control means compares the temporary storage amount based on the temporary storage amount signal with a predetermined reference temporary storage amount, and if the deviation between the two exceeds a predetermined value, the deviation of the pusher operation interval is reduced. Increase or decrease. When a plurality of pushers are provided, the operation interval may be increased or decreased by selecting one or more of them, or the operation intervals may be increased or decreased for all the pushers. As the temporary storage amount measuring means, a capacitance type level sensor, a microwave type level sensor or the like can be used, but preferably an ultrasonic sensor for measuring the level of limestone in the charge bottle. It is obvious that the pusher control means can be constituted by an electronic circuit, a programmable controller, a microcomputer, a personal computer or the like.
[0009]
According to the invention of claim 4, a charge bin in which limestone is temporarily stored, a rotating bed on which limestone dropped from the charge bin through a chute is stored, and the stored limestone is preheated by gas, Limestone intermittently reciprocating along the direction toward the center of the rotating bed, pushing the limestone stored on the rotating bed, and preheated to the limestone supply port provided near the center of the rotating bed A method for controlling a limestone preheating device including at least one pusher for dropping a limestone, wherein temporary storage of limestone that is continuously supplied in a constant amount per unit time in the charge bin is measured at any time. A volume measurement process, a comparison process in which the temporary storage volume measured in the temporary storage volume measurement process is compared with a predetermined reference temporary storage volume to obtain a deviation between the two, A determination process for determining whether the deviation obtained in the comparison process exceeds a predetermined value, and when the deviation exceeds a predetermined value in the determination process, the operation interval of the pusher is determined by the deviation. The control method of the limestone preheating device is configured to include the operation interval adjustment process that increases or decreases to decrease.
[0010]
According to the invention described in claim 4, the temporary storage amount of limestone that is continuously supplied in a charge bin at a substantially constant amount every unit time is measured at any time, and the measured temporary storage amount is the reference temporary storage amount. The deviation is obtained by comparison, and when the deviation exceeds a predetermined value, the operation interval of the pusher is increased or decreased so that the deviation decreases. In other words, when the temporary storage amount is larger than the reference temporary storage amount, the temporary storage amount is decreased by shortening the operation interval and increasing the supply amount of limestone from the preheating device. Increase the temporary storage volume by lengthening. Thereby, the quantity of the limestone supplied from a preheating apparatus can be kept constant, and quick lime with more uniform quality can be obtained.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The following embodiments are for the purpose of understanding the invention more deeply and are not intended to limit the scope of the invention.
[0012]
FIG. 1 is a partially cutaway front view showing one embodiment of a limestone preheating apparatus according to the present invention. Members having the same functions as those in FIG. 4 are denoted by the same reference numerals.
[0013]
In FIG. 1, the charge bin 10 is provided with an ultrasonic sensor 70 for measuring the level of limestone L in the charge bin 10. The ultrasonic sensor 70 is connected to a pusher control device 90 described later.
[0014]
FIG. 2 is a block diagram showing the main configuration of the pusher control device that controls the operation of each pusher 40 of the limestone preheating device shown in FIG. In the figure, the pusher control device 90 includes a reference temporary storage amount storage unit 92, a calculation control unit 94, and an operation interval storage unit 96. The pusher control device 90 is connected to the ultrasonic sensor 70 and the belt scale 22 and receives detection signals from the respective sensors, and the driver 42 and the vibration feeder 24 of each of the six pushers 40 are connected to output drive signals. .
[0015]
The reference temporary storage amount storage unit 92 stores a reference temporary storage amount Sref. The calculation control unit 94 performs various calculations based on the value of the input detection signal to generate a drive signal. The operation interval storage unit 96 stores an interval t for performing drive output in the driver 42. The pusher control device 90 is a computer, and an input operation can be performed from the keyboard 98 while referring to a monitor (not shown). The input value is, for example, the reference temporary storage amount Sref, the reference value of the belt scale 22, or the like.
[0016]
The belt scale 22 measures the weight of the limestone L placed on the conveyor 20 and outputs a signal to the pusher control device 90. Based on the signal from the belt scale 22, the arithmetic control unit 94 adjusts the weight of the limestone L supplied from the rough stone silo (not shown) onto the conveyor 20, and the vibration provided at the outlet of the rough stone silo. The drive of the feeder 24 is controlled. Thereby, the quantity of the limestone L per unit time supplied to the charge bin 10 is maintained substantially constant. The weight to be maintained is determined by, for example, the performance of the firing furnace 60 and the activity of quicklime to be obtained, and is input from the keyboard 98. It is also possible to change the constant weight or stop the supply depending on the state of the firing furnace 60.
[0017]
As described above, the ultrasonic sensor 70 measures the level of the limestone L temporarily stored in the charge bin 10 and outputs a level signal to the pusher control device 90. The pusher control device 90 calculates the temporary storage amount S based on the level signal and compares it with the reference temporary storage amount Sref stored in the reference temporary storage amount storage unit 92.
[0018]
Each driver 42 drives each pusher 40 in accordance with a drive signal from the pusher control device 90. The pusher control device 90 intermittently outputs drive signals at intervals t. The initial value of the interval t is, for example, 30 seconds.
[0019]
Next, the operation of the embodiment shown in FIGS. 1 and 2 will be described with reference to FIG. FIG. 3 is a flowchart showing a control flow in the embodiment shown in FIGS.
[0020]
In FIG. 3, first, a level signal is inputted from the ultrasonic sensor 70 to the pusher control device 90, and the temporary storage amount S is calculated by the arithmetic control unit 94 (step S301). Next, the calculation control unit 94 reads the reference temporary storage amount Sref from the reference temporary storage amount storage unit 92 (step S302) and compares it with the temporary storage amount S (step S303).
[0021]
At this time, if the temporary storage amount S is larger than the value obtained by adding the allowable deviation d to the reference temporary storage amount Sref (step S304), the operation interval t is increased in order to increase the limestone L replenished from the charge bin 10 to the rotary floor 40. It is necessary to make the pusher 40 drop operation frequently by shortening the length. The arithmetic control unit 94 reads the interval t from the operation interval storage unit 96 (step S305), and stores the value obtained by subtracting 5 seconds from the interval t as the updated interval t in the operation interval storage unit 96 (step S306). For example, 5 seconds is subtracted from the interval t which was 30 seconds, and the interval t = 25 seconds is stored in the operation interval storage unit 96.
[0022]
On the other hand, if the temporary storage amount S is smaller than the value obtained by subtracting the allowable deviation d from the reference temporary storage amount Sref (step S307), the amount of limestone L supplied from the charge bin 10 to the rotating bed 40 is too large. The operation interval t is increased. The arithmetic control unit 94 reads the interval t from the operation interval storage unit 96 (step S308), adds 5 seconds to the interval t, and stores it in the operation interval storage unit 96 as a new interval t (step S309).
[0023]
When the temporary residual amount S is within the allowable deviation (Sref + d>S> Sref−d), the operation interval t is not increased or decreased. The above process is continuously repeated during the operation of the preheating device.
[0024]
According to the control as described above, the amount of preheated limestone L supplied from the preheating device to the firing furnace 60 can be maintained substantially constant. Therefore, the heating conditions in the baking furnace 60 can be stabilized, and quick lime of desired quality can be obtained.
[0025]
Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and it is needless to say that the present invention can be appropriately modified within the scope of the gist of the present invention.
[0026]
【The invention's effect】
As described above, according to the limestone preheating apparatus and the control method thereof according to the present invention, the supply amount of limestone which is a heating condition can be stabilized, and thus the calcining furnace supplied with limestone has a more uniform quality quicklime. Can be produced.
[Brief description of the drawings]
FIG. 1 is a partially cutaway front view showing one embodiment of a limestone preheating apparatus according to the present invention.
FIG. 2 is a block diagram illustrating a part of the control device according to the embodiment of FIG. 1;
FIG. 3 is a flowchart showing a control flow of the embodiment shown in FIGS.
FIG. 4 is a partially cutaway front view showing an example of a conventional limestone preheating apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Charge bin 12 Chute 20 Conveyor 30 Rotating floor 32 Limestone supply port 40 Pusher 50 Exhaust gas duct 60 Firing furnace 70 Ultrasonic sensor L Limestone G Exhaust gas

Claims (4)

A charge bin in which limestone is temporarily stored, a limestone dropped from the charge bin through a chute is stored thereon, a rotating bed in which the stored limestone is preheated by gas, and in a direction toward the center of the rotating bed Limestone including at least one pusher that pushes the limestone stored on the rotating bed intermittently reciprocating along the limestone supply port provided near the center of the rotating bed and drops the preheated limestone A preheating device for
The charge bottle is continuously supplied with a substantially constant amount of limestone per unit time,
The operation of the pusher is controlled so that a temporary storage amount of limestone in the charge bottle becomes a substantially constant amount. 2. The limestone preheating device according to claim 1, wherein the pusher is controlled to shorten the operation interval when the temporary storage amount is greater than the substantially constant amount, and to increase the operation interval when the amount is small. . Temporary storage amount measuring means for measuring the temporary storage amount of limestone temporarily stored in the charge bin;
A temporary storage amount signal is input from the temporary storage amount measuring means, the temporary storage amount based on the temporary storage amount signal is compared with a predetermined reference temporary storage amount, and a deviation between both exceeds a predetermined value 3. A limestone preheating apparatus according to claim 2, further comprising pusher control means for increasing or decreasing an operation interval of the pusher so that the deviation decreases. A charge bin in which limestone is temporarily stored, a limestone dropped from the charge bin through a chute is stored thereon, a rotating bed in which the stored limestone is preheated by gas, and in a direction toward the center of the rotating bed Limestone including at least one pusher that pushes the limestone stored on the rotating bed intermittently reciprocating along the limestone supply port provided near the center of the rotating bed and drops the preheated limestone A control method for a preheating device of
Temporary storage amount measurement process for measuring the temporary storage amount of limestone that is continuously supplied in a constant amount per unit time in the charge bin as needed,
A comparison process in which the temporary storage amount measured in the temporary storage amount measurement process is compared with a predetermined reference temporary storage amount to obtain a deviation between the two,
A determination step of determining whether the deviation obtained in the comparison step exceeds a predetermined value;
The control of the limestone preheating device, comprising: an operation interval adjustment step of increasing / decreasing the operation interval of the pusher so that the deviation decreases when the deviation exceeds a predetermined value in the determination process Method.

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