JPH0818684B2 - Pneumatic transportation of powder - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a transportation tank whose lower discharge port is not equipped with a discharge valve, and the powder or granular material stored in the transportation tank is passed through the transportation pipe from the lower discharge port to the next step by air. Is a method of low-concentration high-concentration transportation in a plug state, which can perform stable plug transportation, and can prevent contamination of powder and granules due to metal pieces caused by a metal seal member. The present invention relates to a method capable of preventing crushing of powder and granular material and abrasion of a transport pipe due to high-speed blow-through of powder and granular material at the end.

[0002]

2. Description of the Related Art In general, an inlet valve is provided at the upper inlet of a transportation tank and an outlet valve is provided at the lower outlet, and a ball valve is often used as the outlet valve. In this ball valve, a seal member made of, for example, Teflon, which is in sliding contact with the peripheral surface of the valve main body, is generally provided on the peripheral wall of the space for accommodating the valve main body. However, since the sealing member of Teflon is soft, there is a problem in that when the valve is opened or closed, the powder or granules are bitten and damaged.

Therefore, in order to prevent damage to the seal member, it has been proposed to use a metal seal member. However, in this case, a minute metal piece is generated due to the sliding contact between the valve body and the seal member, and this metal piece is mixed into the powder or granular material, for example, when the powder or granular material is used as a coating material for electric wires. However, there is a problem in that the metal pieces mixed therein tend to cause a leak. That is, there has been a problem of contamination of powder and granules due to mixing of metal pieces (so-called “metal contamination”).

Further, when the particles are discharged until the transportation tank becomes empty, the air accumulated in the tank causes the particles to blow through the transportation pipe at a high speed at the end of transportation, so that the particles are crushed and transported. Wear occurs. In order to avoid this, it has been proposed to close the discharge valve and stop the transportation while leaving a small amount of the granular material in the tank. However, if this method is adopted in the case of a ball valve using a soft seal member such as Teflon, the seal member will be significantly damaged due to the entrainment of powder particles. Therefore, if a metal seal member is used to prevent damage to the seal member, the metal contamination as described above occurs.

[0005]

It is an object of the present invention to use a transport tank whose lower discharge port is not equipped with a discharge valve, and to transfer the powder or granular material stored in the transport tank from the lower discharge port to the next step through a transportation pipe by air. It is a method of high-concentration and low-speed transportation in a plug state, which enables stable plug transportation.
Provided is a method capable of preventing contamination of a powder or granular material due to a metal piece due to a metal seal member, and further preventing crushing of the powder or granular material due to high-speed blow-through of the powder or granular material or abrasion of a transport pipe at the end of transportation. The purpose is to

[0006]

The present invention uses a transport tank whose lower discharge port is not equipped with a discharge valve, and the powder or granular material stored in the transport tank is passed by air from the lower discharge port through a transport pipe. A method of low-concentration high-concentration transportation in the plug state to the next step, in which a primary air supply valve for controlling primary air supplied to apply pressure to the transportation tank and a lower discharge port are provided in the transportation tank. A secondary air supply valve that controls the secondary air that is supplied to flow the coming powder and granules into the transport pipe, and an exhaust valve that controls the exhaust to release the pressure in the transport tank are
Each of them is independently connected, and at the same time as the secondary air is supplied at the start of transportation, the primary air is supplied at a first predetermined speed, and the first predetermined speed is at least 1 to 3 kg /
cm ² G / min, and at the end of transportation, in a state in which powder particles remain in the transportation tank, the primary air is stopped while the secondary air is still flowing, and at the same time the exhaust valve is opened to
The air is transported at a predetermined speed, and the second predetermined speed is set to the same speed as the first predetermined speed.

[0007]

When the secondary air is supplied at the start of transportation, the powder particles coming to the lower discharge port are pushed out to the transportation pipe by the secondary air. At this time, if the pressure increase rate of the transport tank pressure due to the supplied primary air is small, the powder particles extruded from the transport tank to the transport pipe are connected to form a long plug, which blocks the transport pipe. However, in the present invention,
Since the primary air is supplied at a first predetermined speed, and the first predetermined speed is set to at least 1 to 3 kg / cm ² G / min, before the long plugs are continuously formed, Quickly move to stable high-concentration low-speed transportation. Note that short plugs are formed during stable high-concentration low-speed transportation.

At the end of transportation, if the exhaust speed from the exhaust valve is low, the powder and granules pushed out into the transport pipe by the air accumulated in the transport tank become a long plug and remain in the transport pipe. This will hinder the transportation of the next powder or granular material into the transportation tank. However, in the present invention, the exhaust from the exhaust valve is performed at the second predetermined speed, and the second predetermined speed is set to the same speed as the first predetermined speed, so that the plug is stably transported. The transportation ends in a short, broken state, and the transportation pipe is not blocked.

In addition, in a state where the powdery particles remain in the transport tank, the primary air is stopped and at the same time, the exhaust valve exhausts air to end the transportation. It never happens.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic partial view showing a transportation device adopting the pneumatic transportation method of the present invention. In the figure, reference numeral 1 is a transportation tank for storing the powdered or granular material 5 to be transported, and 2 is a charging valve provided at a charging port of the tank 1, for example, a butterfly valve having a non-metallic sealing surface. Reference numeral 3 denotes a lower discharge port of the tank 1, which is formed in a thin tubular shape by narrowing the lower part of the tank 1 and communicates with a transportation pipe 4. This transportation device transports the powdery or granular material 5 which is intermittently supplied into the tank 1.

The tank 1 has a primary air supply valve 11 for controlling the primary air supplied to apply pressure to the tank 1.
And a secondary air supply valve 12 that controls the secondary air supplied to flow the granular material 5 coming to the lower discharge port 3 to the transport pipe 4.
And an exhaust valve 13 for controlling exhaust for releasing the pressure in the tank 1 are connected. Reference numeral 14 is a supply source of primary air and secondary air. A discharge valve is not provided at the lower discharge port 3 of the tank 1.

The method of the present invention is carried out as follows. First, the valve 2 is opened with the valves 11, 12, and 13 closed, and a predetermined amount of the granular material 5 to be transported is charged into the tank 1 from the charging port, and the valve 2 is closed. Since there is no discharge valve at the lower discharge port 3, the charged granular material 5 stops at the place from the lower discharge port 3 to the transport pipe 4 and is stored in the tank 1 as shown in FIG. Next, the valve 12 is opened to supply the secondary air to the lower outlet port 3, and at the same time, the valve 11 is opened to supply the primary air at the first predetermined speed. The first predetermined speed is at least 1
Set to 3 kg / cm ² G / min. When the secondary air is supplied, the granular material 5 coming to the lower outlet 3 is pushed out to the transportation pipe 4 by the secondary air. At this time, if the pressure increase rate of the pressure in the tank 1 due to the supplied primary air is small,
The granular material 5 pushed out to the transport pipe 4 by the secondary air is shown in FIG.
As shown in FIG. 5, the plug 5a becomes long, and the transport pipe 4 is closed. However, the primary air is supplied at the above-mentioned first predetermined speed, and the state of stable transportation is rapidly changed.
As shown in, the plug is shortly interrupted, and short plugs 5b are continuously formed, so that stable high-concentration low-speed transportation is performed without blocking the transportation pipe 4. After reaching the state of stable transportation, the supply amount of primary air is reduced to keep the pressure in the tank 1 constant.

When stable transportation is carried out for a while and the remaining amount of the powder / granular material 5 in the tank 1 becomes small, the secondary air is discharged in a state where the powder / granular material 5 remains in the tank 1. While still flowing, the valve 11 is closed to stop the primary air, and at the same time, the exhaust valve 13 is opened to exhaust gas at the second predetermined speed.
The second predetermined speed is set to the same speed as the first predetermined speed. When the exhaust speed from the exhaust valve 13 is small, the powder particles 5 pushed out to the transport pipe 4 by the secondary air become a long plug 5a as shown in FIG.
Since it remains in the transport pipe 4 as it is, it becomes an obstacle when the next powder or granular material is put into the tank 1 for transportation. However, since the exhaust from the exhaust valve 13 is performed at the second predetermined speed, the plug remains shortly interrupted during stable transportation, that is, the transportation ends while the state of the plug 5b in FIG. 3 is maintained.

Moreover, in a state in which the powder particles 5 remain in the tank 1, the primary air is stopped and at the same time the exhaust valve 1
Since the exhaust is carried out from 3 to end the transportation, the high-speed blow-through of the granular material 5 does not occur at the end of the transportation.

As described above, in the above method, at the start of transportation,
Since the primary air is supplied at the first predetermined speed at the same time as the secondary air is supplied, it is possible to prevent the transportation pipe 4 from being blocked due to the long plug 5a formed in the transportation pipe 4,
Further, the short plugs 5b can be continuously formed, and a stable high-concentration low-speed transportation can be quickly performed.

Further, in the above method, at the end of transportation, the primary air is stopped while the secondary air is still flowing while the powder 5 remains in the tank 1, and at the same time the exhaust valve 13 is opened to open the first valve. Since evacuation is performed at a predetermined speed of 2, it is possible to prevent a long plug 5a from being formed in the transport pipe 4 and hindering the transport of the next granular material into the tank 1. That is, the state of the plug 5b in FIG. 3 can be maintained.

Moreover, since the transportation is completed in the state where the granular material 5 remains in the tank 1, the granular material 5 does not blow through at high speed at the end of the transportation, and the granular material 5 is not blown out.
It is possible to prevent the crushing and the abrasion of the transport pipe 4.

Moreover, according to the above method, the powdery particles can be pneumatically transported in the apparatus shown in FIG. 1 in which the lower discharge port 3 has no discharge valve. Therefore, there is no problem of contamination that the metal pieces generated by opening and closing the discharge valve of the lower discharge port 3 are mixed into the powder particles, and the quality of the powder particles 5 to be transported can be maintained. Further, as a matter of course, the lower discharge port 3 is not caught in the discharge valve at all.

[0019]

[Embodiment] FIG. 1 shows an apparatus in which the powder particles 5 are intermittently supplied to the tank 1, but the method of the present invention is such that the powder particles 5 are continuously supplied to the tank 1 as shown in FIG. It can also be used in the equipment supplied. 4, the same symbols as those in FIG. 1 indicate the same things. 6 is a buffer tank for continuously supplying the granular material 5 to the tank 1, and 7 is a shut-off valve for shutting off the supply of the granular material 5 from the tank 6. The shutoff valve 7 is not required to have pressure resistance and airtightness as long as it does not cause the powdery particles 5 to be caught or come into contact with metal.

In this apparatus, the shut-off valve 7 and the make-up valve 2 are opened to supply the granular material 5 in the tank 6 to the tank 1, the shut-off valve 7 is closed immediately before the tank 1 becomes full, and the make-up valve 2 Close. When the transportation of the powder or granular material 5 in the tank 1 is completed, the closing valve 2 and the shutoff valve 7 are opened, and the powder or granular material 5 is supplied from the tank 6 to the tank 1 again. Other operations are the same as in the case of FIG.

Further, the method of the present invention can of course be applied to the case of transportation by a fluid other than air, such as nitrogen.

[0022]

As described above, the pneumatic transportation method of the present invention has the following advantages. (1) Since the tank 1 having no discharge valve at the lower discharge port 3 as shown in FIG. 1 is used, the problem of powder particles getting caught due to the opening and closing of the discharge valve at the lower discharge port 3 and metal fragments It is possible to completely eliminate the problem of contamination that is mixed in the particles, and it is possible to perform stable plug transportation without closing the transportation pipe 4. (2) It is possible to reliably prevent high-speed blow-through of the granular material 5 at the end of transportation. Therefore, it is possible to prevent the crushing of the granular material 5 and the abrasion of the transport pipe 4. (3) Since the speeds of the primary air and the secondary air are set at the start of transportation and the primary air is stopped and the exhaust valve 13 is set at the end of transportation, the operation is simple and labor-free. No, and therefore very practical. (4) At least 1 supply rate of primary air at the start of transportation
Since it is set to ~ 3 kg / cm ² G / min, it is possible to quickly shift to a stable transportation state. Further, since the transportation is ended in a state where the powdery particles 5 are left in the tank 1, the transportation can be restarted by restarting in a short time. Therefore, the transportation efficiency is good.

[Brief description of drawings]

FIG. 1 is a schematic partial view showing a transportation device adopting the pneumatic transportation method of the present invention.

FIG. 2 is a schematic cross-sectional view showing a state in which a long plug is formed on a transportation pipe.

FIG. 3 is a schematic cross-sectional view showing a state where stable high-concentration low-speed transportation is performed.

FIG. 4 is a schematic partial view showing another transportation device adopting the pneumatic transportation method of the present invention.

[Explanation of symbols]

 1 Tank 3 Lower Discharge Port 4 Transport Pipe 5 Granules 11 Primary Air Supply Valve 12 Secondary Air Supply Valve 13 Exhaust Valve

Claims (1)

[Claims] 1. A transport tank having a lower discharge port not equipped with a discharge valve is used, and the granular material stored in the transport tank is
This is a method of low-concentration, high-concentration transportation in the plug state from the lower outlet through the transportation pipe to the next process by air. The transportation tank controls the primary air supplied to apply pressure to the transportation tank. An air supply valve, a secondary air supply valve for controlling the secondary air supplied to flow the powder or granular material coming to the lower discharge port to the transportation pipe, and an exhaust for releasing the pressure in the transportation tank. Exhaust valves are independently connected to each other, and at the start of transportation, secondary air is supplied at the same time as primary air is supplied at a first predetermined speed, and the first predetermined speed is at least 1 to Set to 3 kg / cm ² G / min, and at the end of transportation, with the powder particles remaining in the transportation tank, stop the primary air while keeping the secondary air flowing, and at the same time open the exhaust valve to open the second Exhaust at a predetermined speed Predetermined speed, the first air transportation method of granular material, characterized in that set to the same speed as a predetermined speed of.