JPH0146789B2 - - Google Patents

Description

Detailed Description of the Invention The present invention is an operation in which powder or pellet-like granular material (hereinafter referred to as powder) is indirectly heated under reduced pressure or high vacuum to dry or react (hereinafter referred to as drying). This invention relates to a vacuum dryer that continuously performs drying.

Traditionally, this type of powder is dried using (A) a double cone shape;
(B) A heating jacket is attached to the outer surface of a fixed oblong cylindrical container, and a ribbon-shaped container is placed inside the container. (C) A type with a rotating inner cylinder that penetrates the end wall of a fixed horizontally cylindrical container, and the gap between the container and the inner cylinder is used as a heating jacket. It is being

However, in the type (A) dryer, since the entire container rotates, the powder inlet and outlet also rotate, so the operation must be batch-wise.
Therefore, productivity is low and labor saving is difficult. Furthermore, since it is a batch method, heating and cooling operations are required for each batch, resulting in relatively high energy costs. Type (B) type dryers can be made continuous by using a screw blade-shaped rotary agitator inside the fixed container to provide the function of transferring the powder from one end of the container to the other. A gap is created between the stirrer and the stirring blade. This gap is
In terms of manufacturing, miniaturization requires precision machining, which increases costs. Also, since deflection occurs in the screw blade, a gap must be provided to accommodate the amount of displacement.
For powder, this gap causes the powder to stagnate during transfer, which has an adverse effect on the type of powder, making it difficult to completely switch when changing the type of powder. In addition, the powder is broken and pulverized by the relative movement in this gap, and abrasion powder is generated.

Type (C) type dryers are able to transfer powder by providing a guide plate on the inner surface of the rotating inner cylinder, which solves the gap problem of type (B), but it is difficult to maintain a high vacuum inside the rotating cylinder. There is great difficulty. Furthermore, the sealing performance of sealing the internal pressure of the envelope at the edge of the container was poor.
For example, in the case of high temperature heating of about 300°C, there is no suitable sealing method.

The present invention not only solves the drawbacks of the prior art powder dryers, but also solves the requirement of being able to maintain a high vacuum of, for example, 0.1 to several Torr, which is required for a high-performance industrial vacuum dryer. , for example, to simultaneously satisfy the requirements of being able to heat at a high temperature of 200° C. to 350° C. and the requirement of being able to continuously process powder.

In other words, the vacuum dryer of the present invention has a fixed, airtight, horizontally long outer enclosure that is evacuated through an exhaust port to evacuate the inside of the container, and the powder and granules are kept in an airtight manner using a rotary valve or the like. The container is supplied through a supply port and a discharge port having a discharge means, and an inner cylinder is provided in the container so as to be rotatable by a shaft at the center end of the seal, and the inner cylinder has openings at both ends. A guide plate such as a helical ribbon is provided on the inner surface of the rotating inner cylinder to transfer the powder and granules from one end of the inner cylinder to the other. The heat medium is transferred in a piston flow shape while receiving repeated rotations, and the inner cylinder is provided with an indirect heat transfer surface consisting of a jacket, tube group, corrugation, etc., and the heat medium is supplied and discharged via the central rotating shaft. Heat is applied to the powder or granular material during transport.

Hereinafter, the present invention will be explained specifically and in detail with reference to embodiments shown in the accompanying drawings.

The enclosing container 1 has a horizontally long body 2 with end walls 3 and 4 sealed at both ends to form a hermetically sealed container, and is fixed by legs 5. The container 1 is provided with a vacuum suction port 6 connected to an evacuation stage such as a vacuum pump, and a supply port 7 at each end through which powder is supplied and discharged through an airtight supply and discharge means such as a rotary valve. A discharge port 8 is provided. The outlet 8 can be connected to a rotary valve via a powder reservoir for receiving continuously discharged dry powder.

Inside the container 1 and spaced apart by a small distance is an inner cylinder 9 having a central end shaft 10, 1 which passes through the container end walls 3, 4 so as to be rotatable about the longitudinal transverse axis of the container.
1, and the penetrating portion is equipped with shaft sealing devices 12, 13.
sealed by. The central shafts 10 and 11 are rotatably supported by bearings 14 and 15 outside the shaft sealing devices 12 and 13, and the central shaft 10 is supported by a motor 16 and a speed reducer 17.
is connected to and driven to rotate.

The inner cylinder 9 has openings 18 and 19 at each end, and a nozzle 20 extending from the powder supply port 7 into the container 1 is directed into the inner cylinder 9 through the opening 18 at one end, and through the opening 19 at the other end. It is positioned above the discharge port 8. That is, the powder is delivered by gravity between the powder supply port 7 and the powder discharge port 8 of the fixed container 1 and the opening 18 at one end and the opening 19 at the other end of the rotating inner cylinder 9, respectively. It is visible in the inner cylinder 9.

On the inner surface of the inner cylinder 9, in this example, a helical ribbon-shaped guide plate 21 is provided integrally with the inner cylinder.
The powder is transferred from the opening 18 at one end to the opening 19 at the other end by the guide plate 21 as the inner cylinder rotates. This transfer is in the form of a piston flow because the powder does not move toward the opposite end, and the powder is repeatedly lifted and dropped as the inner cylinder rotates, so it is repeated over and over again. It will be done.

The inner cylinder 9 is provided with a jacket 22 for indirect heat exchange and a group of heat transfer tubes 23 arranged in a circular row along the inner side of the inner cylinder wall, and a heat medium is introduced from the inlet 24 and the central axis 1
1, passes through the inner passage 25 of the central shaft 11, passes through the connecting pipe 26, flows inside the mantle 22 in the direction of the open end 18, then flows inside the heat transfer tube group 23 in the opposite direction, passes through the connecting pipe 27, passes through the inner passage 28 of the central shaft 11, and is led out from the outlet 29. be done.

As the indirect heat exchange means, in addition to the above-mentioned mantle and heat exchanger tube group, various types of indirect heating means such as a corrugated corrugation tube array and other half-split pipes can be arbitrarily adopted.

In the vacuum dryer of the present invention, the fixed container 1 is evacuated by evacuation from the vacuum suction port 6, and at this time, the powder is supplied and discharged from the supply port 7 and the discharge port 8, which have fixed exhaust means. Since air is sealed on the central shafts 10 and 11 by shaft sealing devices 12 and 13, it is easy to maintain a high vacuum inside the container.

Since heating in vacuum drying of powder is performed only by contact heat transfer between the powder and the heating surface, it is important to increase the heat transfer area and update the powder that comes into contact with the heat transfer surface.

In the present invention, the powder supplied and discharged through the fixed supply port 7 and discharge port 8 is turned around in a piston flow form from one end to the other end by a rotating inner cylinder 9 having an indirect heating means in the vacuum atmosphere inside the machine. The contact heat transfer opportunities are increased and equalized as the heat is transported and comes into contact with the heated surface. In this regard, the heat transfer area can be easily expanded by using a heat transfer surface with an uneven surface, protruding strips, etc., in addition to a simple jacket structure. The guide plate 21 also serves as a means for increasing the heat transfer surface. Moreover, since the indirect heat transfer means can employ a highly pressure-resistant structure such as the heat transfer tube group 23, it can be adapted to high-temperature heating by using a high-pressure, high-temperature heating medium.

As described above, according to the present invention, it is not only possible to achieve high vacuum and high temperature heating as a vacuum dryer, but also to increase the chances of contact between the entire area of the continuously transferred powder and the heat transfer surface, and to ensure continuous contact with the heat transfer surface. The drying operation is carried out efficiently, and powder retention in the machine and mechanical crushing of the powder are less likely to occur, the properties of the dry powder are good, and there is no energy loss due to repeated heating and cooling as in the case of batch type operation. It is relatively easy to manufacture, does not increase equipment costs, and has various effects such as excellent drying of nylon, polyester, and various other powders.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional side view of a vacuum dryer according to an embodiment of the present invention, and FIG. 2 is a longitudinal sectional front view taken along the line - - in FIG. 1. 1... Container, 2... Body, 3, 4... End wall,
5... Legs, 6... Vacuum suction port, 7... Supply port,
8... Discharge port, 9... Inner cylinder, 10, 11... Center end shaft, 12, 13... Shaft sealing device, 14, 15...
...Bearing, 16...Motor, 17...Feed reducer, 1
8, 19... Opening, 20... Nozzle, 21... Guide plate, 22... Mantle, 23... Heat exchanger tube group, 24...
...heat medium inlet, 25, 28... passage, 26, 27...
...Connection pipe, 29...exit.

Claims (1)

[Claims] 1 Fixed oblong closed container 1 having a vacuum suction port 6 connected to a vacuuming means, a supply port 7 and a discharge port 8 through which raw material powder is supplied and discharged via an airtight supply and discharge means.
Inside the outer enclosure, an inner cylinder 9 having a cylindrical shape along its horizontal axis is penetrated through the end walls 3 and 4 of the fixed oblong closed container by central end shafts 10 and 11 protruding from both ends thereof, and is rotatable while maintaining a shaft seal. The inner cylinder 9 is rotatably supported, and one center end shaft is used as a rotational drive side, and the other center end shaft is used as a heat medium supply/discharge side, and the inner cylinder 9 has indirect heat on its outer surface side over its entire length. A replacement jacket 22 is attached, and a helical ribbon-shaped raw material transfer guide plate 21 is integrated with it on its inner circumferential side over its entire length, and the heat transfer tube group 23 is separated from the inner surface of the inner cylinder and arranged along it. are arranged in a circular row to communicate with the heat exchange jacket at one end close to the drive side, and in the center end shaft 11 opposite to the drive side are connected to an external heat medium supply and exhaust source. Heat medium passages 25 and 28 are rotatably connected and are connected to the other end of the heat exchange jacket and the other end of the heat transfer tube group, respectively, and a nozzle 20 extending from the powder supply port 7 through the opening 18 at one end of the inner cylinder is provided. A vacuum dryer characterized in that the powder is guided into an inner cylinder, and the other end opening 19 is positioned above the powder discharge port 8.