JPS62186184A - Air current drier - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a flash dryer, and in particular to a flash dryer, in which a spiral guide is attached to a pneumatic pipe to form a drying pipe, and hot air is swirled inside the pipe. It is characterized by the following.

(Conventional technology) A flash dryer is one type of dryer for powder and granular materials.

This dryer is a type of airflow tube dryer, and the main body consists of an inverted U-shaped drying tube. Hot air is blown from one end of the drying tube to create an airflow inside the tube, and the material to be dried is drawn into this. A certain powder or granule material is put in and dried while being transferred to the other end by air current.

This dryer has the advantage that the powder and granules hardly come into contact with each other during drying, so each powder and granule remains completely independent during drying, but on the other hand,
Since there is almost no difference between the flow velocity of hot air and the transport velocity of powder and granular material, there is a fire point with low drying efficiency, and furthermore, this dryer is a large structure with a drying pipe about 10 meters high. Despite this, the time the powder and granules are transported through this is short, at most two.

Since it takes about three seconds, it is limited to items that are extremely easy to dry.

In order to overcome these drawbacks, the present inventor invented a flash dryer with a longer drying tube, and has already filed an application for the same (Japanese Patent Application No. 184192/1982).

This type of drying tube has a spiral shape, and the height of the drying tube is much lower than that of conventional drying tubes, making cleaning, maintenance, and inspection inside the drying tube easier. The longer tube lengthened the time the powder and granules were in contact with the hot air, further improving drying efficiency.

However, this type of drying tube is simply a longer drying tube, and the powder and granules are still transported at almost the same speed as the hot air flow rate, so the drawback of low drying efficiency is It was unavoidable.

(Objective of the Invention) The object of the present invention is to downsize the device, facilitate internal cleaning, maintenance, and inspection, lengthen the hot air distribution path, and improve the balance between the flow rate of the hot air and the transfer speed of the powder and granular material. The point is to increase the drying efficiency by increasing the difference.

(Structure of the Invention) The present invention is a pneumatic tube having a diameter at least twice as large as that of the drying tube of the conventional flash dryer as described above, and a spiral guide is installed therein to form a drying tube. Furthermore, the guide is rotatable so that the actual length of the drying tube can be adjusted.

(Examples) Hereinafter, the present invention will be specifically described based on illustrated examples.

Reference numeral 1 in the figure is a pneumatic tube. This is the main body of the flash dryer, and corresponds to the drying tube of a conventional flash dryer, with a blower pipe 2 connected to one end a.
Furthermore, a hot air generator 3 is attached to this, and an input port 4 for powder and granular material to be dried is also attached, so that the powder and granular material are fed into the pneumatic pipe 1 together with the hot air.
A transfer pipe 5 is connected to the other end of the pneumatic pipe 1, and a powder collector 6 such as a cyclone dust collector is attached to the transfer pipe 5. The powder and granules that have been dried while passing through are sent to a collector 6 to collect the granules, and the hot air is released into the atmosphere. By the way, the pneumatic tube 1 is more than twice as thick as the drying tube of the conventional flash dryer described above, and is provided with a spiral guide 7 inside, which allows the pneumatic tube to The hot air sent into the tube circulates inside the tube in a spiral manner.

The guide 7 shown in FIG. 1 is of the screw type, and this one in particular is rotatable, and a motor 8 is carefully attached so that it can rotate at an appropriate speed in either the left or right direction. The guide 7 shown in FIG. 2 is formed into a fin shape. The former is suitable for processing granules that are large and difficult to flow, and the latter is suitable for processing powder and granules that have a small apparent specific gravity and are easy to flow.

In addition, although the pneumatic pipe 1 is shown as being vertical in the figure, it is not limited to this, and especially when processing free-flowing powder or granules, it may be horizontal as well. There is no problem.

(Function) When drying powder or granular materials, use the same method as a normal flash dryer.
Hot air is generated by a hot air generator 3, and while the hot air is sent into the pneumatic pipe 1, powder and granular material is introduced from the input port 4. Then, the powder and granules.

It gradually rises while swirling inside the pneumatic pipe 1 along with the hot air, and during this time it dries due to contact with the hot air, and eventually reaches the upper end, where it is discharged from the pneumatic pipe 1 and transferred to the transfer pipe 5. The powder is further fed into the powder collector 6, where it is separated from the hot air and collected as dry powder.

(Effects) As detailed above, the present invention attaches a spiral guide to a pneumatic pipe that is more than twice as thick as the pneumatic pipe of a conventional flash dryer, thereby forming a spiral flow path within the pipe. The length of the pneumatic pipe is reduced to several minutes compared to the drying pipe of a conventional flash dryer, making the device more compact and significantly reducing the installation area and equipment costs. At the same time, cleaning, maintenance, and inspection of the inside of the pneumatic pipe becomes easier.

In addition, in conventional flash dryers, the flow rate of hot air is limited; it must be at least as fast as possible to blow up the powder and granules, and even if the flow rate is increased, the drying time will be reduced accordingly. In addition, the difference between the powder transport speed and the flow speed of hot air is eliminated, so there is almost no increase in drying efficiency.On the other hand, the present invention has a spiral shape in the pneumatic pipe. Since a guide is installed inside the pipe to allow the hot air to circulate inside the pipe while swirling, the powder and granules transferred to this guide will inevitably move to the outside of the flow path due to centrifugal force, and the air will flow through the pneumatic pipe. Since the hot air contacts the inner wall surface of the hot air and slides or rolls along this surface, there is a considerable difference between the transport speed and the flow speed of the hot air. Therefore, the amount of hot air that comes into contact with the powder material increases significantly, and the drying efficiency is significantly increased.

The centrifugal force mentioned above acts more strongly on particles with a large particle size,
Since the particles come into strong contact with the inner wall surface of the pneumatic pipe, the transport speed of particles with a large particle size becomes slow and the drying time becomes long.

Therefore, when drying powders with different particle sizes, the drying time is longer for particles with larger particle sizes that are difficult to dry, and as a result, the difference in dryness between all powders and granules becomes smaller, and the overall drying time is longer. They are dried to the same extent.

In addition, in the present invention, a spiral guide is provided inside the pneumatic pipe to form a flow path for hot air, so that the permissible range of flow velocity of hot air is significantly expanded. That is, the speed need only be higher than the speed at which the powder can be blown up along the guide. Of course, under these conditions, the transport speed of the powder and granules is much slower than in the above case, so even powder and granules that are difficult to dry can be dried.

Furthermore, by rotating the guide in either the left or right direction, the transport speed of the powder blown up along the guide can be adjusted, so the combination of hot air flow rate and drying time can be selected as appropriate. So. Therefore, compared to conventional flash dryers, it is possible to use hot air with a much slower flow rate and to dry over a longer period of time. It is also possible to dry powder and granular materials that are susceptible to thermal changes by using low-temperature hot air, and even powder and granular materials that cannot be treated at the bottom with conventional flash dryers can be dried. It can be dried.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of the present invention. FIG. 2 is a longitudinal sectional view showing another example. 1; Air pipe 2; Air pipe

Claims (1)

[Claims] A spiral guide is provided inside the pneumatic pipe to form a hot air flow path, and the pneumatic pipe is connected to one end of the pneumatic pipe, and a hot air generator and powder/granular material are connected to the pneumatic pipe. What is claimed is: 1. A flash dryer characterized in that an inlet is attached to the inlet, a transfer pipe is connected to the other end, and a powder collector is attached to the transfer pipe.