JP2005272044A - Operation method of belt conveyor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To convey a raw material with a belt conveyor, and to improve weighing accuracy of a facility for weighing and storing a hopper. <P>SOLUTION: The raw material 8 cut from a feeder 12 is fed to the weighing hopper 30 via the belt conveyor 20, the conveyance speed V3 of the belt conveyor at the completion of the weighing is set lower than the conveyance speed V1 in a normal conveyance, and the loading thickness T2 of the raw material in a discharge part of the belt conveyor at the completion of the weighing is set thinner than the loading thickness T1 in the normal conveyance. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an operation method of a belt conveyor for feeding a weighing object cut out from a feeder to a weighing device via a belt conveyor, and in particular, transports raw materials on a belt conveyor in a steelmaking factory, a steelmaking factory, etc. It is related with the operation method of the belt conveyor which can be used for the weighing and storage equipment, and can improve the weighing accuracy.

  In a steelmaking factory or a steelmaking factory, when a raw material such as coke or ore is transported to a blast furnace, a converter or the like, as illustrated in FIG. 1, the raw material 8 cut out from the cutting tank 10 using, for example, an electromagnetic feeder 12 is used. In general, a method is used in which a belt conveyor 20 is used to weigh and store, for example, a weighing hopper 30 provided with a load cell 32. Since the blending of raw materials is directly linked to the quality of hot metal and molten steel and the stable operation of blast furnaces and converters, it is very important to improve the weighing accuracy of the raw materials.

  Therefore, conventionally, in order to improve the weighing accuracy of the raw material, for example, as described in Patent Document 1, by setting the belt conveyor 20 at a low speed before setting the quantity, and slowly putting the raw material into the weighing hopper 30, Weighing accuracy was improved.

JP 61-47535 A

  However, when transporting materials on a belt conveyor, the layer thickness is increased to prevent the material from overflowing during transportation from the belt conveyor for the purpose of increasing transport efficiency. Even if the conveyor was slow, the amount of raw material flowing into the hopper per unit time was large, and there was a limit to improving the weighing accuracy, and the accuracy was not so good.

  Even if the belt conveyor is slow, the amount of raw material that flows into the hopper per unit time is large, so the hopper upper limit level must be set low for safety against hopper overflow, and the hopper capacity cannot be used effectively. It had the problem that.

  The present invention has been made to solve the above-described conventional problems, and an object thereof is to improve weighing accuracy.

  The present invention relates to a belt conveyor operating method in which a weighing object cut out from a feeder is sent to a weighing device via a belt conveyor, and the conveying speed of the belt conveyor at the time of completion of weighing is lower than that during normal conveyance, and weighing is performed. The above problem is solved by making the stacking thickness of the weighing objects in the discharge part of the belt conveyor at the time of completion thinner than that during normal conveyance.

  In addition, there is provided a method for operating a belt conveyor having a speed change function with a transfer speed of at least 3 steps, wherein a weighing object cut out through a feeder having a speed change function with a cut speed of at least 2 steps is supplied to the weighing device. During normal operation, the feeding speed of the feeder is set to a speed other than the lowest speed, the conveyor speed of the belt conveyor is operated at a speed other than the highest speed and a speed other than the lowest speed, and the weighing value in the weighing machine is a target weighing value. When the first predetermined value is subtracted from the value, the feeder cutting speed is reduced, the conveyor speed of the belt conveyor is accelerated, and the weighing value is subtracted from the target weighing value. When the above value is reached, the above problem is similarly solved by reducing the conveying speed of the belt conveyor to a lower speed than during normal operation.

  In the present invention, as illustrated in FIG. 2 (A) at the start of conveyance, and as illustrated in FIG. 2 (B) at the time of normal conveyance, at the time of normal conveyance, the raw material (weighing object) at the conveyance speed V1 and the normal raw material thickness T1. 8 is conveyed.

Then, as shown in FIG. 2 (C), when the amount of the raw material in the weighing hopper (weighing device) 30 reaches a predetermined amount and before the completion of weighing, for example, the electromagnetic feeder is lowered and the belt conveyor is moved faster. V2 (<< V1), and the raw material thickness T2 (<< T1) of the raw material ultrathin layer 9 is made on the belt conveyor 20.

  Further, as shown in FIG. 2 (D), the belt conveyor 20 is set to a low speed V3 (<V1) at the time of determination immediately before the weighing by the weighing hopper 30 reaches a predetermined amount.

  As a result, since the raw material ultrathin layer 9 is weighed at the belt conveyor low speed V3, the amount of raw material flowing into the weighing hopper 30 per unit time can be minimized, and the weighing accuracy is dramatically improved. In addition, since the amount of raw material flowing into the weighing hopper 30 per unit time can be minimized, it is possible to manage by setting the hopper capacity limit to the hopper upper limit HH, and the capacity of the weighing hopper 30 can be effectively utilized.

  In FIG. 2 (D), since the belt conveyor 20 is set to the low speed V3, the thickness of the raw material increases by T3 from T2 to T2, but it is sufficient to reach a fixed value within the extremely thin thickness T2.

  According to the present invention, the weighing object layer thickness on the belt conveyor is controlled, and the amount of raw material flowing into the weighing device per unit time at the end of weighing is minimized, so that weighing accuracy is greatly improved.

  Further, since the weighing objects flowing into the weighing machine per unit time can be minimized, the capacity limit of the weighing machine can be set to the upper limit level of the weighing machine, and the capacity of the weighing machine can be effectively utilized.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  As illustrated in FIG. 3, the control system for carrying out the present invention provides a speed command to the motor driving device 22 of the belt conveyor 20 according to the weighing value input from the load cell 32 of the weighing hopper 30, and cuts off. A control device 40 is provided that gives a speed command to a drive device (referred to as a feeder drive device) 14 of the electromagnetic feeder 12 provided in the discharge tank 10.

  As the feeder drive device 14, for example, a thyristor, an inverter, or the like is used, and the feeder 12 is variable speed.

  As the motor drive device 22, for example, an inverter, a pole change, or the like is used, and the belt conveyor 20 has a variable speed.

  For example, a programmable controller (PLC) or a sequencer is used as the control device 40.

  FIG. 4 shows an example of the relationship between the cutting speed of the electromagnetic feeder 12, the conveying speed of the belt conveyor 20, and the layer thickness of the raw material 8 on the conveyor in this embodiment. During normal operation from the start of weighing t0 to time t1 before quantification, the cutting speed of the electromagnetic feeder 12 is set to a speed other than the lowest speed, here, high speed, and the conveying speed of the belt conveyor 20 is neither the highest speed nor the lowest speed. Drive at medium speed V1. As a result, as shown in FIGS. 2A and 2B, the layer thickness of the raw material 8 on the belt conveyor 20 is in the thickest state T1.

  Next, at time t1 when the weighing value in the weighing hopper 30 is before the fixed value obtained by subtracting the first predetermined value from the target weighing value, the cutting speed of the electromagnetic feeder 12 is reduced from high speed to low speed, and the conveyor belt 20 is conveyed. The speed is accelerated from medium speed V1 to high speed V2. As a result, as shown in FIG. 2C, the layer thickness of the raw material 8 on the belt conveyor 20 becomes a state of ultrathin T2, and the raw material ultrathin layer 9 is formed.

  Next, at the time t2 immediately before the determination when the weighing value has reached the value obtained by subtracting the second predetermined value (smaller than the first predetermined value) from the target weighing value, the conveying speed of the belt conveyor 20 is decreased from the high speed V2. Reduce to V3. As a result, as shown in FIG. 2D, the state of the raw material can be weighed at a low speed on the belt conveyor, and the weighing accuracy is remarkably improved. By setting the belt conveyor 20 to a low speed V3, the layer thickness of the raw material 8 on the belt conveyor 20 is changed from an ultrathin T2 to an intermediate thickness T3. There is no problem if the weighing is set to be completed before reaching.

  Here, the first predetermined value and the second predetermined value are such that the layer thickness of the weighing object (8) at the discharge portion of the belt conveyor 20 is extremely thin when weighing in the weighing device 30 is completed, and It can be set in advance so that the speed of the belt conveyor 20 becomes low.

That is, the weighing target value in the weighing device 30 is A [t], the speed of the belt conveyor 20 in normal operation is V1 [m / min], the cutting speed of the feeder 12 is a [t / min], and the belt conveyor 20 is effective. When the length (distance from the feeder installation position to the discharge part) is L [m], the weighing value is A-a * L / V1.
When the weighing object (8) cut out from the feeder 12 is sent to the weighing device 30, the weighing is completed. Actually, since an error in the cutting speed of the feeder 12 can be considered, it is necessary to reduce the speed of the feeder 12 and increase the speed of the belt conveyor 20 at a slightly earlier time, so the first predetermined value is
A-a * L / V1-α
Can be set. Here, α can be determined by making adjustments in consideration of the cutting error of the feeder 12, the characteristics of the weighing instrument, the specific gravity of the weighing object (8), and the like.

  In addition, it is advantageous to shorten the weighing time when the second predetermined value is set immediately before completion of weighing. This may be determined by making adjustments in consideration of the characteristics of the weighing instrument 30 and the specific gravity of the weighing object (8).

  In the case of transporting minerals such as ore, coal, coke and the like to the weighing hopper 30 having a scale of about several t to 100 t using the normal electromagnetic feeder 12 and the belt conveyor 20, the above-described calculation for the first predetermined value is performed. Adjustment may be made by using about 0.2 to 1 t as α and about 1 t as the second predetermined value.

  In the present invention, the thickness of the raw material 8 on the belt conveyor 20 when the weighing is completed is reduced by controlling the conveying speed of the belt conveyor 20 and the raw material cutting speed of the feeder 12 as described above. Since the weighing speed can be increased by lowering the conveyor speed, even if the conveying speed and the raw material cutting speed are continuously variable and the speed is continuously variable, the raw material cutting speed of the feeder 12 The effect of the present invention can be obtained by controlling the conveying speed of the belt conveyor 20 based on the gist of the present invention at the time of normal operation and before completion of weighing.

  In order to weigh 30 tons of coke with the equipment shown in FIG. 1, conventionally, 10 t / min is cut out from the cutting tank 10 by the electromagnetic feeder 12 and 120 m / min (= V1) Conveyor speed was fed over 3 minutes, and the conveyor speed was reduced to 60 m / min before weighing and weighed. When the weighed value was stable after weighing, The accuracy was ± 1 t.

In order to apply the present invention to the same equipment, the first predetermined value and the second predetermined value were determined. If the first predetermined value is not equal to or greater than the amount of raw material placed on the belt conveyor 20 during normal operation, the layer thickness at the completion of weighing cannot be changed. In the case of this equipment, 10 t / min of raw material is cut out on a belt conveyor 20 having an effective length of 200 m and transported at a conveyor speed of 120 m / min.
200 [m] × 10 [t / min] / 120 [m / min] = 16.7 [t]
Therefore, the first predetermined value needs to be 16.7 t or more. If the first predetermined value is increased too much, the weighing time becomes longer. Therefore, in this embodiment, α is set to about 0.3 t, and the first predetermined value is set to 17 t.

  The second predetermined value was 1t.

  Based on these predetermined values, when the weighing value reaches 13 t, the cut amount of the electromagnetic feeder 12 is lowered to 5 t / min and the conveyor speed is increased to a high speed of 180 m / min (= V2). The upper coke layer thickness was reduced to about 0.3 times (= T2), and when the weighed value reached 29 t, the conveyor speed was lowered to 60 m / min (= V3). As a result, when the amount of coke was measured when the weighing value was stabilized after the weighing was completed, the accuracy was 30 t ± 0.2 t.

  In addition, the effective capacity of the weighing hopper 30 has been conventionally operated as 38 t. However, since the weighing accuracy has been improved as described above, the effective capacity has been operated as 39.5 t. However, there is a problem such as overflow. We were able to use without.

  In addition, in the said Example, although this invention was applied to the coke conveyor, the application object of this invention is not limited to this, It can apply to general conveyors other than an ore conveyor and a raw material. Further, the method of cutting out the weighing object is not limited to the electromagnetic feeder, and the type of the weighing instrument is not limited to the weighing hopper.

Process drawing showing an example of equipment to which the present invention is applied The figure for demonstrating the principle of this invention The block diagram which shows the structural example of the control system for implementing this invention The time chart which shows operation of each part of the embodiment of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 8 ... Raw material 9 ... Raw material thin layer 10 ... Cutting tank 12 ... Electromagnetic feeder 14 ... Feeder drive device 20 ... Belt conveyor 22 ... Motor drive device 30 ... Weighing hopper 32 ... Load cell 40 ... Control device

Claims (2)

In the operation method of the belt conveyor for sending the weighing object cut out from the feeder to the weighing device via the belt conveyor,
A belt characterized in that the conveying speed of the belt conveyor at the time of completion of weighing is lower than that at the time of normal conveyance, and the thickness of the object to be weighed at the discharge portion of the belt conveyor at the time of completion of weighing is made thinner than at the time of normal conveyance Conveyor operation method. An operation method of a belt conveyor having a speed change function with at least 3 steps of conveying speed, supplying a weighing object cut out through a feeder having a speed change function with at least 2 steps of cutting speed to a weighing device,
During normal operation, the feeder cutting speed is set to a speed other than the lowest speed, and the conveyor speed of the belt conveyor is operated at a speed other than the highest speed and at a speed other than the lowest speed,
When the weighing value in the weighing machine becomes a value obtained by subtracting the first predetermined value from the target weighing value, the feeder cutting speed is reduced, and the conveyor speed of the belt conveyor is accelerated.
A belt conveyor operating method, characterized in that when the weighing value reaches a value obtained by subtracting a second predetermined value from a target weighing value, the conveying speed of the belt conveyor is reduced to a lower speed than during normal operation.

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