JPH0820179B2 - Method and apparatus for drying powder - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for drying powder and granules and an apparatus therefor. More specifically, the present invention relates to a highly efficient drying method and an apparatus therefor for reducing the water content of powder particles such as ceramics, coal, organic crystals or polymers.

(Background of the Invention) Conventionally, in the case of drying a wettable or granular material containing surface moisture, it has been usual to heat and dry it by an apparatus of various systems.

However, in such a conventional drying method, the fuel cost for heating is large, and the apparatus for heating is inevitably large in scale. Furthermore, in this conventional method of heating and drying, there is a great limitation in the operation of heating and drying when drying a substance which is easily altered, decomposed or ignited by heat. Even in the case of a substance that easily emits a toxic gas, drying by heating has a great limitation in terms of safety measures.

Therefore, it has been strongly desired to realize a method for drying a powder or granular material which is lower in cost, highly efficient, and capable of easily handling a substance that has a large restriction on heating and drying.

(Object of the Invention) The present invention has been made in view of the above circumstances, and is a highly efficient, simple, heat-altering substance, and thermally decomposable without the drawbacks of the conventional heat drying method. It is an object of the present invention to provide a new method for drying powder and granules that can be applied to substances and the like, and an apparatus therefor.

DISCLOSURE OF THE INVENTION In order to achieve the above object, the drying method of the present invention has an annular slit for ejecting a pressurized fluid toward the outlet between the outlet and the inlet, and the slit. From the outlet to the outlet, and the powder is conveyed by the Coanda spiral flow generated by the Coanda spiral flow generation device in which the pressurized fluid is supplied from the outside to the slit, It is characterized by reducing the water content of the granules.

And the invention also provides an apparatus for the above method.

The Coanda spiral flow, which is an important feature of the present invention, was first discovered by the inventor of the present invention as a new fluid motion concept. That is, when a vector in the pipe radial direction is added to the vector of the fluid in the pipe direction, the fluid swirls and a dynamic boundary layer is formed near the inner wall of the pipe based on this swirling flow, and the fluid draws a spiral (spiral) while I found the fact that the road travels at high speed.
It was also revealed that this Coanda spiral flow is different from the so-called normal turbulence.

The inventor of the present invention has studied the application of this Coanda spiral flow, and this spiral flow is extremely effective for drying powder and granules. The present invention has been completed by finding that the collision with the wall and the adhesion of the powder or granular material to the inner wall of the tube are also suppressed.

The present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows an example of the drying method and apparatus of the present invention.

The granular material with a high water content is supplied from the supply device (1),
Supply to the inlet (3) of the Coanda spiral flow generator (2). A pressurized fluid is introduced through the introduction pipe (4) to generate a Coanda spiral flow in the pipe line (5),
By this spiral flow, the granular material is conveyed to the outlet of the pipeline (5). In this process, the granular material is dried with its water content reduced. A collection device (6) such as a drum is arranged at the outlet of the pipe (5).

FIG. 2 shows another example. In this example, the conduit (7) connected to the spiral flow generator (2) is arranged in a ring shape. The outlet of the conduit (7) faces the inlet (8) of the Coanda spiral flow generator (2). The fluid circulation can be terminated by moving the outlet of the line (7).

The Coanda spiral flow generator used for drying may be, for example, the one shown in FIG. 3, FIG. 4 or FIG. Of course, it is not limited to this example.

Air or an inert gas can be used as the pressurized fluid, for example. In addition, a heating device may be provided in the pipeline as required. Particularly in the case of a highly wettable powder or granule, it is also effective to use drying by heating together.

In the case of the example shown in FIG. 3, the Coanda spiral flow generator (2) is connected to the conduit (9) at its outlet. More specifically, the pipe line (9) is connected at the end face outlet of the cylindrical pipe (10).

The diameter of the cylindrical tube (10) gradually decreases toward the connecting surface. Then, a pressurized fluid such as air or an inert gas is laterally supplied to the cylindrical pipe (10) through the introduction pipe (11). This pressurized fluid is piped (9)
A slit (12) is provided for feeding in the direction of.
Further, a smoothly curved wall surface (13) is formed from the slit (12) toward the conduit (9).

A curved wall surface (14) bent at a right angle or an acute angle is provided on the side opposite to the curved side surface (13). The spacing of the slits (12) should be adjustable. Also, slit (12)
A distribution chamber (15) for uniformly supplying the pressurized fluid is provided in the.

The end face of the apparatus opposite to the pipe (9) is an inlet (16), and the powder or granular material to be dried is supplied from this inlet (16).

In the Coanda spiral flow generator having such a structure, the motion vector of the pressurized fluid from the slit (12) and the motion vector of the fluid from the inlet (16) are combined to generate a spiral motion (17). . At that time, the pressurized fluid at the outlet of the slit (12) moves by drawing the streamline of the arrow (α) by the Coanda effect, and forms a dynamic boundary layer near the inner wall surface of the conduit. In addition, a large negative pressure region is generated on the side of the narrow gap (12) opposite to the pipeline (9), and the inflow of the powder or granules from the inlet (16) is promoted.

The Coanda spiral flow ejected from this Coanda spiral flow generation device becomes a spiral flow with a very large free vortex region, and therefore the supplied powder and granular material is
Converging on the central axis of the Coanda spiral flow, the converged powder and granules are subjected to decompression dehydration due to the pressure reduction phenomenon near the central axis, and the water content is greatly reduced.

FIG. 4 and FIG. 5 show another example of the Coanda spiral flow generation device.

In the case of FIG. 4, the inlet (16) is replaced with the cone body (18).
Is formed by Further, in the case of FIG. 5, an introduction pipe (19) is further provided at the introduction port (16). This introducing pipe (19) is effective for introducing the powder or granular material, and the powder or granular material may be pressure-fed through the introducing pipe (19) or may be supplied by means such as a screw feeder. .

In the case of the apparatus shown in FIG. 3, for example, in the case of the apparatus of FIG. 3, the pressure of the pressurized fluid is ^{2 to} 10 kg / cm ² , and the inclination angle (θ) of the cylindrical tube (10) is such that tan θ is 1/4 to 1 It can be around / 8. The flow velocity by Coanda spiral flow can be as high as 100 to 200 m / sec. Moreover, even when a fluid of solid particles is used, the collision of particles with the inner wall of the tube is suppressed.

Next, the present invention will be specifically described with reference to examples.

Needless to say, the present invention is not limited to the following examples, and various other modes are possible.

Example Coal powder was dried using the apparatus shown in FIG.
Pulverized coal with a particle size of 0.5-5 mm was used. Pipe outlet diameter 80.7φ,
Drying was carried out at a pressurized air pressure of 3.3 kg / cm ² G using a device having a pipe length of 30 m. The temperature was 13 ° C and the humidity was 95%.

6.99% in one pass for pulverized coal with surface moisture of 9.55%
The water content has dropped to. Since the water content of pulverized coal is around 6%, the substantial surface water content is about 1%. Also, 14.9
In the case of pulverized coal with 2% water content, it decreased to 8.50% in one pass.

It is difficult to effectively dry these pulverized coals by ordinary heating and drying. However, according to the method of the present invention, the drying efficiency is extremely excellent. Moreover,
There was almost no collision of the pulverized coal with the inner wall of the pipeline.

[Brief description of drawings]

1 and 2 are schematic views showing an example of the method and apparatus of the present invention. FIG. 3, FIG. 4 and FIG. 5 are sectional views showing an example of the Coanda spiral flow generator. The numbers in the figure indicate the following. 1 ... Powder supply device, 2 ... Spiral flow generation device, 3 ... Inlet port, 4 ... Inlet pipe, 5 ... Pipe line, 6 ...
Recovery device, 7 ... Pipe line, 8 ... Inlet port.

Claims (3)

[Claims] 1. A slit having an annular slit for ejecting a pressurized fluid toward the outlet between the outlet and the inlet, and a gradually decreasing cylindrical tube extending from the slit toward the outlet. A granular material characterized by reducing the water content of the granular material while transporting the granular material by a Coanda spiral flow generated by a Coanda spiral flow generator in which a pressurized fluid is supplied from the outside. How to dry. 2. An annular slit for ejecting a pressurized fluid toward the outlet, and a gradually decreasing cylindrical tube extending from the slit to the outlet are provided between the outlet and the inlet. A Coanda spiral flow generator, to which pressurized fluid is supplied from the outside,
With a pipe line connected to the generator outlet, the granular material is introduced from the introduction port, the introduced granular material, while being transported by the Coanda spiral flow generated by the Coanda spiral flow generator A powdery or granular drying apparatus, characterized in that the water content is reduced and dried. 3. Drying the powder or granular material according to claim (2), wherein the powder or granular material is allowed to circulate through the pipeline by making the pipeline discharge port face the inlet of the Coanda spiral flow generator. apparatus.