JP7644960B2 - Powder and granular material processing device and powder and granular material processing method - Google Patents

Description

The present invention relates to an apparatus and method for processing powdered or granular materials such as resin materials.

For example, in the manufacturing process of plastic products, plastic pellets (resin pellets), which are the raw material for plastic products, are pre-dried to remove moisture from the plastic pellets before they are fed into a molding machine.

If plastic pellets contain a certain amount of moisture when they are melt-molded, this can cause unnecessary thermal decomposition and the generation of gas, so it is desirable to melt-molde the plastic pellets in a state where they are dried to an appropriate level. Before being fed into the molding machine, the plastic pellets can be dried using a dryer, but if the dried plastic pellets are exposed to a high humidity atmosphere during the process of being transported from the dryer to the molding machine, they may absorb moisture again.

Figure 6 is a diagram showing the configuration of a conventional plastic product manufacturing facility 201.

The manufacturing facility 201 includes a drying device 202 that dries the plastic pellets, a molding machine 203 that melts the plastic pellets to mold plastic products, and a transport system 204 that transports the plastic pellets from the drying device 202 to the molding machine 203.

The drying device 202 is equipped with a drying hopper 205. A discharge outlet is formed at the lower end of the drying hopper 205, and a gate shutter is provided to open and close the discharge outlet. When the gate shutter is closed and the discharge outlet is closed, plastic pellets can be stored in the drying hopper 205. When the gate shutter is opened and the discharge outlet is opened from a state in which plastic pellets are stored in the drying hopper 205, the plastic pellets in the drying hopper 205 are discharged through the discharge outlet.

An air circulation line 206 is connected to the drying hopper 205. The air circulation line 206 is connected to the inside of the drying hopper 205 at one end and the other end, and is routed around the outside of the drying hopper 205. A drying blower 207 and a dehumidification/heating mechanism 208 are provided on the air circulation line 206. When the drying blower 207 is driven, air is blown out from the drying blower 207 toward the dehumidification/heating mechanism 208. The air blown out from the drying blower 207 passes through the dehumidification/heating mechanism 208, at which time the moisture contained in the air is taken away by the dehumidification/heating mechanism 208, becoming low dew point dry air (dehumidified air), which is further heated by heating and supplied into the drying hopper 205 from one end of the air circulation line 206. The dry air supplied into the drying hopper 205 removes moisture from the plastic pellets stored in the drying hopper 205 and is discharged into the air circulation line 206 from the other end of the air circulation line 206. This dries the plastic pellets in the drying hopper 205.

A loader hopper 211 is disposed above the molding machine 203. Plastic pellets are fed into the molding machine 203 from the loader hopper 211.

The transport system 204 includes a closed loop transport line 212, a transport blower 213, a discharge line 214, and a dry air branch line 215. The closed loop transport line 212 is connected to the inside of the loader hopper 211 at one end and the other end, and is routed around the outside of the loader hopper 211. The transport blower 213 is provided on the closed loop transport line 212. When the transport blower 213 is driven, air circulates through the closed loop transport line 212, air is supplied from one end of the closed loop transport line 212 to the inside of the loader hopper 211, and air in the loader hopper 211 is sucked out from the other end of the closed loop transport line 212. The discharge line 214 has one end connected to the discharge port of the dry hopper 205, and the other end branched and connected to the discharge side of the transport blower 213 in the closed loop transport line 212. One end of the dry air branch line 215 is connected to a portion of the air circulation line 206 through which dry air flows from the dehumidification and heating mechanism 208, and is connected by branching to a portion of the closed loop transport line 212 on the discharge side of the transport blower 213. A dry air valve 216 is installed in the dry air branch line 215.

When the gate shutter of the drying hopper 205 is opened while the transport blower 213 is driven, the plastic pellets in the drying hopper 205 are sucked out through the discharge port of the drying hopper 205 and the discharge line 214 into the closed-loop transport line 212, and transported through the closed-loop transport line 212 toward the loader hopper 211. During the transport, the dry air valve 216 is opened, and dry air with a low dew point that has passed through the dehumidification and heating mechanism 208 is taken from the air circulation line 206 through the dry air branch line 215 into the closed-loop transport line 212. This keeps the closed-loop transport line 212 and the loader hopper 211 at a low humidity (low dew point), preventing the plastic pellets stored in the loader hopper 211 from absorbing moisture.

Japanese Utility Model Application Publication No. 2-34212

However, as the dry air branches off from the air circulation line 206 into the dry air branch line 215, the volume of dry air supplied from the air circulation line 206 to the drying hopper 205 temporarily changes during transportation.

The object of the present invention is to provide a powder/granular material processing device and a powder/granular material processing method that can stabilize the air volume in the storage section in which the powder/granular material is stored while lowering the dew point of the powder/granular material destination.

In order to achieve the above object, a powdered or granular material processing apparatus and a powdered or granular material processing method according to one aspect of the present invention include a storage section that stores powdered or granular material therein, a dry air supply section that supplies dehumidified and heated dry air into the storage section, a transport line that communicates with the storage section and extends through a destination of the powdered or granular material from the storage section to a downstream side of the destination in a transport direction from the storage section to the destination, a transport airflow generating section that generates a transport airflow in the transport direction on the transport line, and a control section that performs a dew point reduction process to reduce the dew point of the destination by generating a state in which the transport airflow generating section generates a transport airflow and transports the powdered or granular material stored in the storage section to the destination, and then generates a state in which the transport line is opened to the atmosphere downstream of the destination in the transport direction and the generation of the transport airflow by the transport airflow generating section is stopped.

According to this configuration, the dehumidified and heated dry air is supplied into the storage section, whereby the powder and granular material contained in the storage section is dried. The transport line for transporting the dried powder and granular material to the destination communicates with the storage section, passes through the destination, and extends downstream of the destination in the transport direction from the storage section to the destination. The powder and granular material contained in the storage section is transported to the destination by generating a transport airflow in the transport direction in the transport line. After the powder and granular material are transported, the transport line is opened to the atmosphere downstream of the destination in the transport direction, and the generation of the transport airflow is stopped. In this state, since dry air is supplied to the storage section, the static pressure in the storage section becomes higher than the static pressure at the destination. Due to the static pressure difference, dry air moves from the storage section through the transport line to the destination. As a result, the destination can have a low dew point. In addition, because the generation of the transport airflow is stopped, dry air is not actively sucked out of the storage section into the transport line, and there is no active fluctuation in the dry air inside the storage section, which helps prevent the air volume inside the storage section from becoming unstable.

This allows the dew point of the powder to be lowered, while preventing the air volume in the storage section where the powder is stored from becoming unstable.

The dry air supply unit may be configured to include a dry air line communicating with the inside of the storage unit, a dry airflow generating unit that generates an airflow in the dry air line toward the storage unit, a dehumidifying unit that dehumidifies the air flowing through the dry air line, and a heating unit that heats the air flowing through the dry air line.

This configuration allows dehumidified, heated, dry air to be supplied to the storage section.

The dehumidification section may have a drying area and a regeneration area, the drying air line may pass through the drying area, and the dehumidification section may be configured to include an adsorption tube formed in a cylindrical shape and arranged across the drying area and the regeneration area, a rotating section that rotates the adsorption tube around its center line, and a regeneration air supply section that supplies heated regeneration air to the regeneration area.

According to this configuration, the dry air line passes through the dry area, so that the air flowing through the dry air line passes through the dry area, and at that time, the moisture contained in the air passing through the dry area is adsorbed by the adsorption tube. As a result, the air that has passed through the dry area is dehumidified to become dry air with a low dew point, and flows through the dry air line toward the inside of the storage section. Since heated regeneration air is supplied to the regeneration area, the adsorption tube is rotated to move the portion of the adsorption tube that has adsorbed moisture from the air in the dry area to the regeneration area, so that the moisture can be desorbed from that portion, and that portion can be regenerated to a low humidity state.

The transport line may include a first transport pipeline having a downstream end in the transport direction connected to the transport destination, and a second transport pipeline having an upstream end in the transport direction connected to the transport destination, and the powder/granular material processing device may further include a switching valve that is connected to the upstream end in the transport direction of the first transport pipeline and the downstream end in the transport direction of the second transport pipeline and can be switched between a circulation position that connects the upstream end of the first transport pipeline to the downstream end of the second transport pipeline, and an open position that closes the upstream end of the first transport pipeline and opens the downstream end of the second transport pipeline to the atmosphere.

The powder/granular material processing device may further include a dew point meter that detects the dew point temperature at the destination.

The control unit may control the dry air supply unit so that the dew point temperature at the destination is below 0°C, preferably below -20°C.

If the dew point temperature at the destination is 0°C or below, preferably -20°C or below, moisture absorption by the powder or granules at the destination can be effectively prevented.

The powder/granular material processing device may further include an inert gas introduction section that introduces an inert gas into the storage section.

In this configuration, by introducing an inert gas into the processing section, the powder can be dried in an inert gas atmosphere. As a result, the powder can be prevented from containing oxidizing gases, and defects such as yellowing of plastic products caused by melt molding of powder containing oxidizing gases can be prevented.

Multiple transport destinations may be set, and the powder/granular material processing device may further include a destination switching unit that switches the destination through which the transport line passes among the multiple transport destinations.

A powdered or granular material processing method according to another aspect of the present invention is a method for processing powdered or granular material in an apparatus including a storage section that stores powdered or granular material inside, and a transport line that communicates with the inside of the storage section and extends downstream of the destination of the powdered or granular material from the storage section in a transport direction from the storage section to the destination, and includes a drying process in which dehumidified and heated dry air is supplied into the storage section that stores the powdered or granular material to dry the powdered or granular material, a transport process in which, after the drying process, a transport airflow in the transport direction is generated in the transport line to transport the powdered or granular material stored in the storage section to the destination, and a dew point reduction process in which, after the transport process, the transport line is opened to the atmosphere downstream of the destination in the transport direction and the generation of the transport airflow is stopped to reduce the dew point of the destination.

This method can achieve the same effects as those achieved by the powder and granular material processing device described above.

According to the present invention, it is possible to lower the dew point of the powder and granular material at the destination while stabilizing the air volume inside the storage section in which the powder and granular material is stored.

1 is a diagram illustrating a configuration of a manufacturing facility including a powder/granular material processing apparatus according to an embodiment of the present invention. FIG. 2 is a diagram showing the main configuration of the manufacturing equipment in a simplified manner compared to FIG. 1 . 10 is a flowchart showing the flow of processing performed after a drying process. FIG. 13 is a diagram showing a configuration of a powder/granular material processing apparatus according to another embodiment. FIG. 13 is a diagram showing a configuration of a powder/grain processing apparatus according to still another embodiment. FIG. 1 is a diagram illustrating the configuration of a conventional plastic product manufacturing facility.

The following describes in detail an embodiment of the present invention with reference to the attached drawings.

<Plastic product manufacturing equipment>
FIG. 1 is a diagram illustrating the configuration of a production facility 2 including a powder/granular material processing apparatus 1 according to an embodiment of the present invention.

The powder and granular material processing device 1 is included in the plastic product manufacturing equipment 2 and is a device that processes powder and granular material such as plastic pellets, which are the raw material for plastic products. Specifically, it is a device that dries the powder and granular material and transports the dried powder and granular material to the molding machine 3.

The powder and granular material processing device 1 is equipped with a drying hopper 11 and a loader hopper 12 arranged above the drying hopper 11. The powder and granular material that is the raw material for the plastic product is supplied from the loader hopper 12 to the drying hopper 11, dried while contained (stored) in the drying hopper 11, and then transported from the drying hopper 11 to the molding machine 3.

Dry air for drying the powder and granular material is supplied to the drying hopper 11 from the drying air line 13. One end of the drying air line 13 is disposed inside the drying hopper 11. The other end of the drying air line 13 is connected to an air exhaust pipe 14 that penetrates the side wall of the drying hopper 11, and communicates with the inside of the drying hopper 11 via the air exhaust pipe 14. The drying air line 13 is routed outside the drying hopper 11, and in the portion routed outside the drying hopper 11, a drying filter 15, an aftercooler 16, a drying blower 17, an adsorption section 18, and a drying heater 19 are interposed in that order from the other end side of the drying air line 13, i.e., the air exhaust pipe 14 side.

One end of the exhaust pipe 21 is connected to the suction port of the drying blower 17. The other end of the exhaust pipe 21 is connected to the air exhaust pipe 14. The drying filter 15 is interposed in the middle of the exhaust pipe 21 and removes foreign matter from the air flowing through the exhaust pipe 21. The exhaust pipe 21 passes through an aftercooler 16 between the drying filter 15 and the drying blower 17. One end of a first supply pipe 22 is connected to the outlet of the drying blower 17.

The adsorption section 18 includes an adsorbent 23. The adsorbent 23 is configured with a cover 25 provided on both ends of a substantially cylindrical adsorption tube 24. The adsorption tube 24 has a number of air flow paths extending in the direction of its center line. The inner surface of the air flow path (the surface in contact with air) is formed of an adsorbent material (e.g., zeolite) that adsorbs moisture. The area in which the adsorption tube 24 exists includes a first drying area, a second drying area, and a regeneration area, and the air flow path of the adsorption tube 24 includes an air flow path in the first drying area (hereinafter referred to as the "first drying flow path"), an air flow path in the second drying area (hereinafter referred to as the "second drying flow path"), and an air flow path in the regeneration area (hereinafter referred to as the "regeneration flow path"). The cover 25 at one end of the adsorbent 23 is provided with a port 26A communicating with the first drying flow path, a port 26B communicating with the second drying flow path, and a port 26C communicating with the regeneration flow path. The cover 25 at the other end of the adsorber 23 is provided with a port 27A that communicates with the first drying flow path, a port 27B that communicates with the second drying flow path, and a port 27C that communicates with the regeneration flow path. The adsorption unit 18 also includes a rotation mechanism 28 that rotates the adsorption tube 24 around its center line. The rotation mechanism 28 includes a motor 29 as a drive source.

The adsorption section 18 also includes a regeneration blower 31 and a regeneration heater 32. The suction port of the regeneration blower 31 is open to the atmosphere through a regeneration filter 33. One end of a regeneration line 34 is connected to the outlet of the regeneration blower 31. The regeneration line 34 passes through the aftercooler 16 and the regeneration heater 32 in order in the middle, and the other end is connected to port 27C of the adsorber 23. This allows the regeneration line 34 to communicate with the regeneration flow path of the adsorption tube 24. The other port 26C, which communicates with the regeneration flow path, is open to the atmosphere.

The other end of the first supply pipe 22 is connected to the port 26A of the adsorber 23 and communicates with the first drying flow path. On the other hand, one end of the second supply pipe 35 is connected to the port 27A that communicates with the first drying flow path. The second supply pipe 35 passes through the drying heater 19 in the middle, penetrates the side wall of the drying hopper 11, and the other end is disposed in the drying hopper 11. In the drying hopper 11, the other end of the second supply pipe 35 is bent downward and extends, and is formed into a cone shape that widens downward. In addition, the first return pipe 36 is branched and connected to the second supply pipe 35 between the adsorption section 18 and the drying heater 19. The first return pipe 36 is connected to the port 27B of the adsorber 23 and communicates with the second drying flow path of the adsorption tube 24. One end of the second return pipe 37 is connected to the other port 26B that communicates with the second drying flow path. The other end of the second return line 37 branches off and is connected to the exhaust line 21 between the aftercooler 16 and the drying blower 17.

When the drying blower 17 is driven, air is blown out from the blowing port of the drying blower 17 into the first supply pipe 22, and an airflow toward the adsorption section 18 is generated in the first supply pipe 22. The airflow flows from the port 26A of the adsorber 23 into the first drying flow path of the adsorption tube 24, passes through the first drying flow path, and flows out from the port 26B of the adsorber 23 into the second supply pipe 35. When the airflow passes through the first drying flow path, the moisture contained in the airflow is adsorbed by the adsorption tube 24, and the airflow that passed through the first drying flow path becomes a low dew point dry air airflow. A part of the airflow that flows out to the second supply pipe 35 flows into the first return pipe 36, flows into the second drying flow path from the port 27B of the adsorber 23, passes through the second drying flow path, and flows into the second return pipe 37 from the port 26B of the adsorber. When the airflow passes through the second drying passage, the moisture contained in the airflow is adsorbed by the adsorption tube 24, and the airflow that has passed through the second drying passage has a further lower dew point temperature and merges with the air flowing through the second return pipe 37 and exhaust pipe 21.

The dry air flowing through the second supply pipe 35 is heated by the drying heater 19, and becomes heated dry gas, which is supplied into the drying hopper 11. The temperature of the dry gas is, for example, 60 to 180°C. The dry gas blown out from the other end of the second supply pipe 35 passes between the powder and granules stored in the drying hopper 11 and escapes above the stored powder and granules. As a result, the dry gas removes moisture from the powder and granules, drying them. The gas that has removed moisture from the powder and granules is discharged through the air discharge pipe 14 to the discharge pipe 21, and flows through the discharge pipe 21 toward the drying blower 17.

Meanwhile, the regeneration blower 31 is driven. When the regeneration blower 31 is driven, outside air is sucked into the suction port of the regeneration blower 31 through the regeneration filter 33. Then, the outside air is blown out from the outlet of the regeneration blower 31 into the regeneration line 34, and an airflow toward the adsorption section 18 is generated in the regeneration line 34. The airflow (outside air) passes through the aftercooler 16 and the regeneration heater 32 in order, flows into the regeneration flow path of the adsorption tube 24 from the port 27C of the adsorber 23, passes through the regeneration flow path, and is released into the atmosphere from the port 26C of the adsorber 23. In the aftercooler 16, heat exchange is performed between the outside air flowing through the regeneration line 34 and the air flowing through the exhaust pipe 21, so that the outside air flowing through the regeneration line 34 is heated and the air flowing through the exhaust pipe 21 is cooled. The outside air flowing through the regeneration line 34 is further heated by the regeneration heater 32 to become regeneration gas, and the regeneration gas passes through the regeneration flow path of the adsorption tube 24. Meanwhile, the portion of the adsorption tube 24 that has adsorbed moisture from the air in the dry region moves to the regeneration region as the adsorption tube 24 rotates by the rotation mechanism 28. This causes the moisture adsorbed in the adsorption tube 24 to desorb from the adsorption tube 24, and the adsorption tube 24 is regenerated to a low-humidity state. The temperature of the regeneration gas is set to, for example, 180 to 250°C in order to desorb moisture from the adsorption tube 24.

The lower part of the drying hopper 11 is formed in a cone shape tapering downward, and a discharge outlet 41 is formed at its lower end. The drying hopper 11 is provided with a gate shutter 42 that opens and closes the discharge outlet 41. When the gate shutter 42 is closed and the discharge outlet 41 is closed, the powder and granular material supplied from the loader hopper 12 can be stored in the drying hopper 11. A discharge branch pipe 43 is connected to the discharge outlet 41. The discharge branch pipe 43 is interposed in a transport line 44. When the gate shutter 42 is opened and the discharge outlet 41 is opened from a state in which the powder and granular material is stored in the drying hopper 11, the powder and granular material in the drying hopper 11 is discharged from the discharge outlet 41 to the discharge branch pipe 43.

The transport line 44 includes a switching valve 45, a first transport pipeline 46, and a second transport pipeline 47.

The switching valve 45 has an input port 51, a circulation output port 52, and an atmosphere release port 53. The switching valve 45 is provided with valve bodies that open and close the circulation output port 52 and the atmosphere release port 53 individually. Depending on the positions of these valve bodies, the switching valve 45 can be switched between a circulation position in which the atmosphere release port 53 is closed and the circulation output port 52 is opened, thereby connecting the input port 51 and the circulation output port 52 within the valve box, and an open position in which the circulation output port 52 is closed and the atmosphere release port 53 is opened, thereby connecting the input port 51 and the atmosphere release port 53 within the valve box.

One end of the first transport pipeline 46 is connected to the circulation output port 52 of the switching valve 45. A destination hopper 54 is provided above the molding machine 3 to store the powder to be fed into the molding machine 3, and the other end of the first transport pipeline 46 is connected to the side wall of the destination hopper 54 and communicates with the inside of the destination hopper 54.

One end of the second transport pipeline 47 is connected to the upper wall of the destination hopper 54 and communicates with the inside of the destination hopper 54. The other end of the second transport pipeline 47 is connected to the input port 51 of the switching valve 45. A primary/secondary switching valve 55, a dust collection cyclone 56, a transport filter 57, and a transport blower 58 are interposed in the second transport pipeline 47 in this order from the destination hopper 54 side.

The primary-secondary switching valve 55 has a primary input port 61, a secondary input port 62, and an output port 63. The primary-secondary switching valve 55 is provided with valve bodies that open and close the primary input port 61 and the secondary input port 62 individually. Depending on the positions of the valve bodies, the primary-secondary switching valve 55 can be switched between a primary transport position in which the secondary input port 62 is closed and the primary input port 61 is opened, thereby connecting the primary input port 61 and the output port 63 within the valve box, and a secondary transport position in which the primary input port 61 is closed and the secondary input port 62 is opened, thereby connecting the secondary input port 62 and the output port 63 within the valve box.

The second transport pipeline 47 is further divided into a first pipeline section 71, a second pipeline section 72, a third pipeline section 73, a fourth pipeline section 74 and a fifth pipeline section 75. One end of the first pipeline section 71 is connected to the upper wall of the destination hopper 54 as one end of the second transport pipeline 47, and the other end of the first pipeline section 71 is connected to the secondary input port 62 of the primary-secondary switching valve 55. One end of the second pipeline section 72 is connected to the output port 63 of the primary-secondary switching valve 55, and the other end of the second pipeline section 72 is connected to the air introduction section 76 of the dust collection cyclone 56. One end of the third pipeline section 73 is connected to the intake section 77 of the dust collection cyclone 56, and the other end of the third pipeline section 73 is connected to the inlet 78 of the transport filter 57. One end of the fourth pipeline 74 is connected to the outlet 79 of the transport filter 57, and the other end of the fourth pipeline 74 is connected to the inlet of the transport blower 58. One end of the fifth pipeline 75 is connected to the outlet of the transport blower 58, and the other end of the fifth pipeline 75 is connected to the input port 51 of the switching valve 45.

One end of a primary suction line 81 is connected to the upper wall of the loader hopper 12, and the primary suction line 81 is connected to the inside of the loader hopper 12. The other end of the primary suction line 81 is connected to the primary input port 61 of the primary-secondary switching valve 55. One end of a powdered material supply line 82 is connected to the side wall of the loader hopper 12. The powdered material supply line 82 extends toward a raw material tank (not shown) that stores the powdered material, and the other end is connected to a suction pipe 83 arranged in the raw material tank.

When the powder is supplied from the raw material tank to the loader hopper 12, the switching valve 45 is set to the open position and the primary/secondary switching valve 55 is set to the primary transport position. When the transport blower 58 is driven, air is sucked from the fourth pipeline section 74 into the suction port of the transport blower 58, and the air is blown out from the outlet of the transport blower 58 to the fifth pipeline section 75. The air blown out to the fifth pipeline section 75 enters the valve box of the switching valve 45 from the input port 51 of the switching valve 45, and is released from the valve box to the atmosphere through the atmosphere release port 53. This generates negative pressure in the primary suction line 81, the second pipeline section 72, the third pipeline section 73, and the fourth pipeline section 74, and the powder in the raw material tank is sucked up into the suction pipe 83 by the negative pressure, and is supplied from the suction pipe 83 to the loader hopper 12 through the powder supply line 82.

<Transportation/low dew point treatment>
FIG. 2 is a diagram showing the main configuration of the manufacturing equipment 2 in a more simplified manner than FIG.

The destination hopper 54 is provided with a dew point meter 91 that detects the dew point temperature, which is a value corresponding to the amount of moisture contained in the air in the destination hopper 54.

The powder and granular material processing apparatus 1 also includes a control unit 92. The control unit 92 is provided with a microcomputer (microcontroller unit), which includes, for example, a CPU, a non-volatile memory such as a flash memory, and a volatile memory such as a dynamic random access memory (DRAM). A detection signal from a dew point meter 91 is input to the control unit 92. The control unit 92 controls the operation of each part of the powder and granular material processing apparatus 1 based on the dew point temperature detected by the dew point meter 91, etc.

Figure 3 is a flowchart showing the process that takes place after the drying process.

In the drying process, as described above, drying gas is supplied into the drying hopper 11 to dry the powder and granular material stored in the drying hopper 11.

After the drying process, the control unit 92 performs a closed circulation transport process (step S1).

In the closed circulation transport process, the switching valve 45 is set to the circulation position, and the primary-secondary switching valve 55 is set to the secondary transport position. Then, the transport blower 58 is driven. When the transport blower 58 is driven, air is sucked from the fourth pipeline section 74 into the suction port of the transport blower 58, and the fourth pipeline section 74 becomes negative pressure. Due to the negative pressure, the air in the transport destination hopper 54 is sucked into the first pipeline section 71, and an air flow is generated in the first pipeline section 71, the second pipeline section 72, the third pipeline section 73, and the fourth pipeline section 74. Meanwhile, the air blown out from the outlet of the transport blower 58 to the fifth pipeline section 75 enters the valve box of the switching valve 45 from the input port 51 of the switching valve 45, and flows out from the circulation output port 52 of the switching valve 45 to the first transport pipeline 46. This generates a transport airflow by circulating air through the transport line 44 consisting of the switching valve 45, the first transport pipeline 46, and the second transport pipeline 47. When the gate shutter 42 of the drying hopper 11 is opened and the discharge port 41 of the drying hopper 11 is opened, the powder and granular material in the drying hopper 11 is sucked out from the discharge port 41 into the transport line 44, and the powder and granular material rides on the transport airflow and is transported along the transport line 44 (first transport pipeline 46) toward the destination hopper 54.

Meanwhile, while the powder is being transported, dry air is supplied to the drying hopper 11. At this time, the drying blower 17, adsorption section 18 and drying heater 19 are controlled so that the dew point temperature detected by the dew point meter 91 is below 0°C, preferably below -20°C.

Dust and other foreign matter contained in the transport airflow is collected when the transport airflow passes through the dust collection cyclones 56 and 57. In the dust collection cyclone 56, air is sucked out from the intake section 77 of the dust collection cyclone 56 into the third duct section 73, creating a negative pressure inside the dust collection cyclone 56. This negative pressure causes air (the transport airflow) to be sucked into the dust collection cyclone 56 from the second duct section 72 through the air inlet section 76, and in the dust collection cyclone 56, the air swirls, and the air and foreign matter are separated by centrifugal force and gravity, and the foreign matter is stored in a collection box connected to the lower end of the dust collection cyclone 56.

By the closed circulation transport process, the powder and granular material in the drying hopper 11 is transported to the destination hopper 54, and when there is no more powder and granular material in the drying hopper 11, the control unit 92 performs a dew point reduction process (step S2).

In the dew point reduction process, the transport blower 58 is stopped. Then, the switching valve 45 is switched from the circulation position to the open position. As a result, the transport line 44 is opened to the atmosphere at the atmosphere release port 53 of the switching valve 45. The primary-secondary switching valve 55 remains in the secondary transport position. At this time, the supply of dry air to the drying hopper 11 continues, and the drying blower 17, adsorption section 18 and drying heater 19 are controlled so that the dew point temperature detected by the dew point meter 91 is below 0°C, preferably below -20°C.

Since dry air is supplied into the drying hopper 11, the static pressure inside the drying hopper 11 becomes higher than the static pressure inside the destination hopper 54. This static pressure difference causes dry air to move from inside the drying hopper 11 through the transport line 44 (first transport pipeline 46) to the destination hopper 54. As a result, the dew point inside the destination hopper 54 is lowered. At this time, only a very small amount of dry air can be branched off to the destination hopper 54 side.

The amount of dry air released by opening the door is replenished with outside air so that the pressure can be adjusted on the drying hopper 11 side. For example, outside air can be taken in through the primary powder and granular material supply line 82. Alternatively, a supply port for replenishing air (outside air) may be provided in one of the dry air lines 13, and in this case, it is preferable to provide the supply port upstream of the dehumidification section 18. Also, instead of being limited to outside air, previously dehumidified dry air may be used for replenishing.

＜Effects＞
As described above, the dew point inside the destination hopper 54 can be lowered. Lowering the dew point of the destination hopper 54 can prevent the powder or granule from absorbing moisture inside the destination hopper 54. By controlling the dew point temperature of the destination hopper 54 to 0° C. or lower, preferably −20° C. or lower, it is possible to effectively prevent the powder or granule from absorbing moisture inside the destination hopper 54. As a result, it is possible to prevent unnecessary thermal decomposition and gas generation during melt molding of the powder or granule by the molding machine 3.

In addition, since the generation of the transport airflow is stopped, dry air is not actively sucked out of the drying hopper 11 into the transport line 44, and no active fluctuations occur in the dry air inside the drying hopper 11, so the air volume inside the drying hopper 11 can be stabilized and the temperature control inside the drying hopper 11 can be prevented from becoming unstable.

This allows the dew point inside the destination hopper 54 to be lowered while preventing the air volume and temperature control inside the drying hopper 11 from becoming unstable.

<Other embodiments>
Fig. 4 is a diagram showing the configuration of a powder/grain processing apparatus 101 according to another embodiment. In Fig. 4, parts corresponding to those shown in Fig. 2 are given the same reference numerals as those of those parts. In the following, only the differences between the configuration shown in Fig. 4 and the configuration shown in Fig. 2 will be described.

As shown in FIG. 4, a nitrogen supply line 102 may be branched and connected to the dry air line 13, and nitrogen gas generated by a nitrogen gas generator 103 may be introduced through the nitrogen supply line 102. In the nitrogen gas generator 103, air compressed by an air compressor 104 is supplied to an adsorption tank 105, and the adsorption tank 105 adsorbs the oxygen and moisture contained in the compressed air, generating nitrogen gas containing a high concentration of nitrogen.

In this configuration, nitrogen gas is introduced into the drying air, creating a nitrogen gas atmosphere inside the drying hopper 11, and the powdered material can be dried in this inert gas atmosphere. As a result, the powdered material is prevented from containing oxidizing gases, and defects such as yellowing of plastic products caused by melt molding of powdered material containing oxidizing gases can be prevented.

Figure 5 is a diagram showing the configuration of a powder/granular material processing apparatus 111 according to yet another embodiment. In Figure 5, the parts corresponding to those shown in Figure 2 are given the same reference numerals as those parts, and the description of the parts given the same reference numerals is omitted.

In the configuration shown in FIG. 2, a switching valve 45 is interposed between the first transport pipeline 46 and the second transport pipeline 47. When the switching valve 45 is in the circulation position, the second transport pipeline 47 (fifth pipeline section 75) is connected to the first transport pipeline 46 via the switching valve 45, thereby making the transport line 44 a closed-loop transport line.

As shown in FIG. 5, the switching valve 45 is omitted, and an on-off valve 112 is provided at the downstream end of the second transport pipeline 47 in the direction in which the transport airflow flows (transport direction), and the on-off valve 112 is closed during the drying process, and may be opened during the process of transporting the powder and granular material from the drying hopper 11 to the destination hopper 54 after the drying process and the process of lowering the dew point inside the destination hopper 54.

The configuration of the powder/granular material processing device 111 can achieve the same effects as those achieved by the configuration of the powder/granular material processing device 1.

<Modification>
Although several embodiments of the present invention have been described above, the present invention can be embodied in other forms.

For example, in the configuration shown in FIG. 2, the operation of the powder/granular material processing device 1 is controlled based on the dew point measured using the dew point meter 91, but this is not limiting, and the dew point meter 91 may be omitted. In that case, for example, the time for switching the switching valve 41 to the open position may be predetermined within a range in which a low dew point can be achieved, and the time may be controlled alone.

A method of heating the destination hopper 54 may also be used. If the dew point can be reduced even without a heating mechanism, this is advantageous as it reduces equipment costs, but if the raw material is very susceptible to moisture absorption or if maintaining a low moisture content is strictly required, the effect of reducing the dew point can be enhanced by using this method in combination.

In addition, in the configuration shown in FIG. 5, a check valve that prevents outside air from being taken into the second transport pipeline 47 from the outside may be provided instead of the on-off valve 112.

The on-off valve 112 or a check valve replacing it may be installed upstream of the transport blower 58, provided that it is downstream of the destination hopper 54 in the direction in which the transport airflow flows.

The transport blower 58 is not limited to being installed in the second transport pipeline 47, but may also be installed in the first transport pipeline 46.

As shown by the dashed lines in FIG. 1, the manufacturing equipment 2 may include a plurality of molding machines 3. For example, in a configuration in which two molding machines 3 are included in the manufacturing equipment 2, a secondary input port 64 is additionally provided to the primary-secondary switching valve 55, a branch pipe 65 branched from the first transport pipeline 46 is connected to the side wall of the destination hopper 54 of the added molding machine 3, one end of the sixth pipeline section 66 is connected to the upper wall of the destination hopper 54, and the other end of the sixth pipeline section 66 is connected to the secondary input port 64. Then, when powdered material is transported to the added molding machine 3, the primary-secondary switching valve 55 is switched to a position in which the primary input port 61 and the secondary input port 62 are closed and the secondary input port 64 and the output port are communicated.

In addition, various design modifications may be made to the above-mentioned configuration within the scope of the claims.

1, 101, 111: Powder and granular material processing apparatus 11: Drying hopper (storage section)
13: Drying air line 17: Drying blower (drying airflow generating part)
18: Adsorption part (dehumidification part)
19: Drying heater (heating unit)
24: Adsorption tube 28: Rotation mechanism (rotating part)
31: Regenerative blower (regenerative air supply unit)
32: Regenerative heater (regenerative air supply unit)
34: Recycle line (recycled air supply section)
44: Transport line 45: Switching valve 46: First transport pipeline 47: Second transport pipeline 58: Transport blower (transport airflow generating section)
91: Dew point meter 92: Control unit

Claims (9)

A storage section for storing powder and granular material therein;
a dry air supply unit for supplying dehumidified and heated dry air into the storage unit;
a transport line that communicates with the inside of the storage unit, passes through a destination of the powder or granular material from the storage unit, and extends to a downstream side of the destination in a transport direction from the storage unit to the destination;
a transport airflow generating unit that generates a transport airflow in the transport direction on the transport line;
a control unit that generates the transport airflow generating unit, performs a transport process to transport the powder or granular material stored in the storage unit to the destination, and then creates a state in which the transport line is opened to the atmosphere downstream of the destination in the transport direction and generation of the transport airflow by the transport airflow generating unit is stopped , and in this state, supplies dry air into the storage unit by the dry air supply unit , thereby performing a dew point reduction process to reduce the dew point of the destination. The dry air supply unit includes:
A dry air line communicating with the inside of the storage section;
a drying airflow generating unit that generates an airflow in the drying air line in a direction toward the storage unit;
a dehumidifying unit that dehumidifies air flowing through the dry air line;
The powder/granular material processing apparatus according to claim 1 , further comprising: a heating unit that heats the air flowing through the drying air line. The dehumidification section includes a drying area and a regeneration area.
the drying air line passes through the drying area;
The dehumidifying unit includes:
an adsorption tube formed in a cylindrical shape and arranged across the drying area and the regeneration area;
a rotating part that rotates the adsorption cylinder about its center line;
The powder/granular material processing apparatus according to claim 2 , further comprising: a regeneration air supply unit that supplies heated regeneration air to the regeneration area. The transport line includes:
a first transport pipeline having a downstream end in the transport direction connected to the transport destination;
a second transport pipeline having an upstream end in the transport direction connected to the transport destination,
The powder or granular material processing apparatus according to any one of claims 1 to 3, further comprising a switching valve that connects an upstream end of the first transport pipeline in the transport direction and a downstream end of the second transport pipeline in the transport direction, and that is switchable between a circulation position that connects the upstream end of the first transport pipeline with the downstream end of the second transport pipeline, and an open position that closes the upstream end of the first transport pipeline and opens the downstream end of the second transport pipeline to the atmosphere. The powder/granular material processing device according to any one of claims 1 to 4, further comprising a dew point meter for detecting the dew point temperature at the transport destination. The powder/granular material processing device according to any one of claims 1 to 5, wherein the control unit controls the dry air supply unit so that the dew point temperature at the transport destination is 0°C or lower. The powder/granular material processing device according to any one of claims 1 to 6, further comprising an inert gas introduction section that introduces an inert gas into the storage section. A plurality of destinations are set,
The powder/granular material processing apparatus according to any one of claims 1 to 7, further comprising a transport destination switching unit that switches the transport destination through which the transport line passes among the plurality of transport destinations. A method for processing powdered or granular material in an apparatus including a storage section that stores powdered or granular material therein, and a transport line that communicates with the inside of the storage section, passes through a destination of the powdered or granular material from the storage section, and extends to a downstream side of the destination in a transport direction from the storage section to the destination, the method comprising:
a drying step of drying the powder or granule by supplying dehumidified and heated dry air into the storage section that stores the powder or granule;
a transport step of generating a transport airflow in the transport direction in the transport line after the drying step, and transporting the powder or granular material contained in the storage unit to the destination;
and a dew point reducing step of reducing the dew point of the destination by generating a state in which, after the transport step, the transport line is opened to the atmosphere downstream of the destination in the transport direction and generation of the transport airflow is stopped, and supplying the dry air into the storage section in this state .

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