JPH0413634Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a measuring device for a powder or granular material containing fine powder such as grain or coal powder.

[Prior Art] A conventional weighing device of this type is provided with a large upper buffer tank 2 and a lower buffer tank 3 above and below a weighing hopper 1, as shown schematically in FIG. The weighing hopper 1 is connected to a lower buffer tank 3 through a ventilation pipe 4, and an exhaust hole 5 is provided in the upper part of the weighing hopper 1, which is connected to a dust collector via a suction pipe 6. Here, the granular material to be weighed enters the weighing hopper 1 from the upper buffer tank 2 through the input gates 7 and 8, but at this time, air corresponding to the volume of the granular material is expelled. The expelled air passes through the exhaust hole 5 and is sucked in by the suction pipe 6.

Then, the powder and granular material weighed by the weighing hopper 1 is
The air is discharged to the lower buffer tank 3 through the discharge gate 9, but the rejected air at this time returns to the weighing hopper 1 through the ventilation pipe 4, and only the differential pressure where the pressure balance due to the air is broken is exhausted or discharged from the exhaust hole 5. It is starting to be inhaled. In this way, each time powder is put into the weighing hopper 1, the displaced air is ejected, and at the same time, the dust contained in the powder is also ejected. Depending on the type, there is a risk of causing a dust explosion.

As a countermeasure, conventionally the upper part of the weighing hopper 1 and the input section are covered with an airtight dustproof cover.
For complete sealing, the expelled air is compressed, resulting in a pressure difference between it and the outside air.
This causes errors in measurement values. In order to reduce this error, the exhaust hole 5 and the flexible cylinder 10 are used to ventilate air to reduce the differential pressure, and a dust collector is connected to the exhaust hole 5 to draw in a constant suction pressure. It is.

As described above, the conventional apparatus requires a dust collector, which requires large-scale equipment, and is expensive and disadvantageous in terms of space. Furthermore, even if suction is carried out at a constant suction pressure, the internal space volume of the weighing hopper 1 changes due to the movement of the powder and granules, so the differential pressure value due to the internal air constantly fluctuates, and this fluctuation affects the measured value. However, there remains the problem that this may lead to measurement errors.
Furthermore, since the joint between the exhaust hole 5 and the suction pipe 6 has an adjustable opening, there is also the drawback that it is difficult to completely prevent the ejection of fine powder.

[Purpose of the invention] The purpose of the invention is to create a powder and granule weighing device that does not emit dust to the outside, does not require dust collection equipment, is smaller and cheaper than conventional types, and has excellent weighing accuracy. It is about providing.

[Summary of the invention] The gist of the invention to achieve the above objectives is as follows:
In a weighing device equipped with a distribution chute into which powder and granular material to be weighed are input in a connected manner, a weighing hopper installed below the distribution chute, and a discharge chute further below the distribution chute, a discharge chute is provided between the distribution chute and the weighing hopper and between the weighing hopper and the weighing hopper. and the discharge chute by first and second dustproof covers, respectively, the inside of the weighing hopper and the upper part of the distribution chute are communicated by a ventilation pipe, and a first A second damper is provided at the bottom of the discharge chute for airtightly blocking the space between the discharge chute and the lower part thereof, and when a large amount of powder or granular material is charged from the distribution chute to the measuring hopper. When the first damper is opened and the second damper is closed, both the first and second dampers are closed during small injection, and when the powder and granular material is discharged from the measuring chute to the discharge chute. In this apparatus, both the first and second dampers are opened.

[Embodiment of the invention] The invention will be explained in detail based on the embodiment shown in FIG.

FIG. 1 shows an embodiment in which the present invention is applied to a measuring device for powder and granular material, which was previously filed by the present applicant in Utility Application No. 143383/1983. In FIG. 1, the powder and granules input from the input conveyor 11 enter the distribution chute 12, and after being rectified by a rectifying plate (not shown), are subjected to the stirring action of the stirring rotary blades 13, and are distributed from the center of the distribution chute 12, etc. It is distributed almost equally to a suitable number of supply hoppers 14, for example four, arranged at equal angles in distance.

A weighing hopper 15 is provided below each supply hopper 14, and powder particles are fed into each weighing hopper 15 through a large output gate 16 or a small output gate 17 provided at the lower end of each supply hopper 14. The body load is measured by a load converter (not shown) provided in the weighing hopper 15. The weighed powder and granules are dropped from the discharge gate 18 into the discharge chute 19 provided below each weighing hopper 15, and then discharged through the collective discharge chute 20 and transferred to a discharge conveyor or the like.

The above-mentioned configuration is almost the same as the powder weighing device of the aforementioned Utility Application No. 143383/1983, and the large output gate 1
6. The dispensing gate 17, the discharge gate 18, etc. are opened and closed by respective drive mechanisms based on commands from the control device.

The present invention is further provided with a differential pressure reduction mechanism as described below. That is, the same number of dustproof covers 21 as the weighing hoppers 15 are provided on the outer periphery of the distribution chute 12, and these dustproof covers 21 are connected to the upper part of each weighing hopper 15 by a flexible cylinder 22 that does not transmit force. ing. Further, the space inside the dustproof cover 21 is communicated with the upper part of the distribution chute 12 via the ventilation pipe 23.
An upper airtight damper 24 that can be opened and closed is provided at the upper end. Furthermore, a dustproof cover 25 is provided between each weighing hopper 15 and the discharge chute 19, and each of these dustproof covers 25 has a flexible cylinder 26, so that force is transmitted between the weighing hopper 15 and the discharge chute 19. It is becoming more and more difficult to do so.
Further, the internal space of the dustproof cover 25 communicates with the upper part of each weighing hopper 15 via a ventilation pipe 27. Further, lower airtight dampers 28 are provided at the lower ends of the discharge chute 19, respectively, and upper airtight dampers 24
A differential pressure reduction mechanism is constructed from the lower airtight damper 28 to the lower airtight damper 28.

The sequence of operations during weighing is such that the cycle of empty weighing → large loading → small loading → main weighing → discharging is repeated for each weighing hopper 15 based on commands from the control device.
In synchronization with this, the upper airtight damper 24 and the lower airtight damper 28 are opened and closed as follows. That is, during empty metering and large filling, the upper airtight damper 24 is opened and the lower airtight damper 28 is closed. Therefore,
The rejected air generated when the large discharge gate 16 is opened is returned to the distribution chute 12 through the ventilation pipe 23 and the upper airtight damper 24. Next, both the upper airtight damper 24 and the lower airtight damper 28 are closed at the time of small injection and main measurement. Since the amount of expelled air during small injection is small, it is transferred from the flexible cylinder 22 into the dustproof cover 21 or from the ventilation pipe 27 to the dustproof cover 2.
It can be discharged into 5. Furthermore, when discharging the weighed powder and granules by opening the discharge gate 18 and dropping them into the discharge chute 19, the upper airtight damper 2
4 and the lower airtight damper 28 are both opened, and the same cycle is repeated thereafter.

In this way, both the upper airtight damper 24 and the lower airtight damper 28 are closed at least once during measurement, and serve to reduce the differential pressure that occurs during measurement.

Note that since the four weighing hoppers 15 operate sequentially, almost continuous weighing is possible, but it goes without saying that the present invention can also be applied to a case where there is only one weighing hopper 15. Further, although the capacity of the weighing hopper 15 may be made different depending on the size of the measuring storage capacity per hour, the above-described differential pressure reduction mechanism can be applied regardless of the capacity of the weighing hopper 15. Furthermore, such a differential pressure reduction mechanism
It can also be attached to a conventional metering device such as the one illustrated in the figure.

[Effects of the invention] As explained above, the powder and granular material measuring device according to the invention does not require the conventionally required dust collection equipment, so it can be configured small and compact, and the equipment cost can be significantly reduced. can be reduced. Moreover, the negative influence of the suction pressure of the dust collector on the measured value is eliminated, and it is possible to significantly improve the measuring accuracy.

In particular, the present invention has a structure that prevents dust from spewing out to the outside, which eliminates the problem of pollution caused by dust and the risk of explosion.Furthermore, since the fine powder returns to the upper distribution chute, it is possible to eliminate the problem of dust pollution and the risk of explosion. No powder is lost, and for this reason the overall powder metering accuracy is also improved.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an embodiment of a measuring device for powder or granular material according to the present invention, and FIG. 2 is a cross-sectional view of a conventional device. Reference numeral 11 is a charging conveyor, 12 is a distribution chute, 13 is a stirring rotary blade, 14 is a supply hopper, 1
5 is a weighing hopper, 16 is a large output gate, 17 is a small output gate, 18 is a discharge gate, 19 is a discharge chute, 20 is a collective discharge chute, 21 and 25 are dust-proof covers, 22 and 26 are flexible tubes, 23, 27 is a ventilation pipe, 24 is an upper airtight damper, and 28 is a lower airtight damper.

Claims (1)

[Scope of Claim for Utility Model Registration] 1. A distribution chute into which powder and granular materials to be measured are continuously fed, a measuring hopper installed below the chute,
In the weighing device further provided with a discharge chute below the distribution chute, the distribution chute and the weighing hopper and the weighing hopper and the discharge chute are connected by first and second dustproof covers, respectively, and the inside of the weighing hopper is connected. and an upper part of the distribution chute through a ventilation pipe, a first damper is provided to airtightly block the ventilation pipe, and a first damper is provided at a lower part of the discharge chute to airtightly isolate the space between the discharge chute and the lower part thereof. A second damper is provided for the purpose of opening the first damper and closing the second damper when a large amount of powder or granular material is being charged from the distribution chute to the measuring hopper, and opening the first damper and closing the second damper when a small amount is being charged. The first and second dampers are both closed, and both of the first and second dampers are opened when the powder or granular material is discharged from the measuring chute to the discharge chute. Granule weighing device. 2. The powder and granular material weighing device according to claim 1, wherein a plurality of the weighing hoppers and discharge chute are each fixedly provided.