JP2668070B2 - Weightless powder classification method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for carrying out a powder or a powder or granular material (hereinafter, simply referred to as a powder) by air flow for highly accurate classification.

[0002]

2. Description of the Related Art Cyclones and virtual impactors are known as conventional terrestrial wind classifiers (December 15, 1981, Nikkan Kogyo Shimbun, "Powder Engineering Glossary", p. 22, (See pages 118, 119).
In this cyclone and virtual impactor,
By transporting powdered particles in an air stream and changing the direction of the air stream, large particles have a large inertial force, so they do not change direction like air streams, but small particles use the same trajectory as the air stream. Classify. In the cyclone, centrifugal force is applied on top of the inertial force, and large-diameter particles are separated and move and fall to the lower part in the cyclone.

[0003]

Since gravitational acceleration exists on the earth, in order to convey a granular material in an air stream, an air flow at a speed equal to or higher than the terminal velocity at which the granular material is conveyed against gravity is required. Linear velocity is required. However, at the terminal velocity, the air flow itself becomes a turbulent state, causing turbulence in the granular material, and the granular material meanders. Further, under the influence of the gravitational acceleration, the powdery and granular materials in the gas phase have an unstable distribution and a drift, so that the classification efficiency is low and the classification accuracy is deteriorated.

[0004] The present invention has been made in view of the above points,
An object of the present invention is to put non-charged particles in a laminar fluid in zero gravity or under microgravity in order to eliminate the drift of the powder due to gravitational acceleration and the meandering flow of the powder due to a turbulent region, and further to apply an electric field or magnetic field. And to provide a method and an apparatus for accurately classifying the granules.

[0005]

In order to achieve the above object, a method for classifying weightless powder according to the present invention comprises the steps of: transporting a static-charged powder in a laminar flow under zero gravity or microgravity; An electric or magnetic field is applied to the laminar flow to classify the powder.

Further, in the weightless classification apparatus of the present invention, a powder airflow conveying pipe is arranged in a weightless chamber, and one end of the powder airflow conveying pipe is connected to an electrostatically charged powder supply means and a blower, and the powder airstream is connected. A powder classification means is provided at the other end in the transport pipe, and an electric field applying means or a magnetic field applying means is arranged in the middle of the powder air flow transport pipe.

Under zero gravity or microgravity, powder can be conveyed by laminar flow having a low superficial velocity. In the laminar flow, the powder particles travel in a straight line, so that the powder is charged beforehand, or the powder is charged while flowing into the powder flow carrier pipe (duct). When an electric or magnetic field is applied to the powder, an acceleration is generated that is inversely proportional to the mass of the powder, whereby the powder is classified.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings. However, the shapes of the components described in this embodiment, the relative arrangement thereof, and the like are not intended to limit the scope of the present invention to them only, unless otherwise specified, and are merely illustrative examples. It's just Embodiment 1 FIG. 1 shows an embodiment of a weightless powder classifier according to the present invention, in which an electric field is applied. Reference numeral 10 denotes a weightless room, which is a rocket, a falling tower, an aircraft that draws a parabola and flies. A powder air transport tube 12 (duct) is arranged in the zero-gravity chamber 10, and one end of the air flow transport tube 12 is connected to a static electricity supply device 14 and a blower 16. Examples of the charged powder supply means 14 include a powder storage tank 20 provided with a cut-out valve 18 at a lower portion and further provided with a high voltage application means 22. It is also possible to supply the powder in a laminar flow while applying a high voltage to the air flow carrier pipe 12 so that the powder is charged. In order to put the powder into the air flow carrier pipe 12, for example, the gas branched from the blower 16 is supplied into the powder storage tank 20.
Further, in order to create a preferable laminar flow, the distance from the gas inlet to the cut-off valve 18 is set to 1 of the inner diameter l of the air flow carrier pipe 12.
It is preferred to be about 0 times.

A powder classifying means 24 is provided at the other end of the air flow carrying tube 12, and an electric field applying means 26 is arranged in the middle of the air flow carrying tube 12. As the powder classification means 24,
For example, a filter formed by laminating a number of plates in a horizontal direction so as to form slits is used. 28 is a power supply.

Now, the inner diameter of the air flow carrier tube 12 is 1 [m], the velocity of the static charge powder is v [m / s], and the mass of one static charge powder is m.
[Kg] and the voltage as V [volt], E = V / l [V / m] or [N / C]. At time t = 0, the powder position x = 0, y = 0, and the powder acceleration x ″ = 0, y ″ = Eq / m. Therefore, after t seconds, x ′ = v, y ′ = Eqt / m (Eq /
m [m / s ² ]), x = vt, y = Eqt ² / 2m.
Here, q is the electric charge of the charged powder. x = x ^* and t = x ^* /
^{v, y = Eqx * 2 /} 2mv 2, i.e., in the dust collecting section AB plane has excursion Eqx ^{* 2} / 2mv 2. E, q, x ^* ,
Since v is constant, the deviation of the powder is inversely proportional to the mass m and inversely proportional to dp ³ . Note that x ^* is the distance in which the electric field exists in the flow direction, and dp is the diameter of the particle.

Therefore, as shown in FIG. 1, if the upper side of the air flow carrier tube 12 is a positive pole and the lower side is a negative pole, the powder that has been charged has an acceleration that is inversely proportional to the mass, and the powder that has a small diameter has a bottom. The large-sized powder moves a little to the lower side. These powders are separated by the classification means 24 (filter), whereby the powders are classified.

Embodiment 2 In this embodiment, as shown in FIGS. 2 and 3, the apparatus shown in FIG. 1 is provided with a magnetic field applying means 30 in place of the electric field applying means. As the magnetic field applying means 30, for example, one in which two magnets 32 and 34 are installed around the air flow carrier tube 12 can be mentioned. Other configurations are the same as those in the first embodiment.

Assuming now that the velocity of the non-charged powder is v and the mass is m, the time t = 0 and the powder position x = 0 and y = 0.
Then, x '= v, y' = vqBt / m, x = vt, y
= VqBt ² / 2m. B is the magnetic flux density [Wb / m
² ]. x = x ^* , y = vqB / 2mx × (x ^* /
v) ² , where v, q, B, x ^* are constant, so the acceleration of the powder is inversely proportional to the mass m.

Therefore, as shown in FIG. 2, when a magnetic field is applied from the other side (back side of the paper surface) of the air flow carrier tube 12 to this side, the accumulated powder moves at an acceleration inversely proportional to the mass and has a small diameter. The powder moves largely downward, and the large-diameter powder moves small downward. These powders are passed through a classification means 24 (filter) and classified.

[0015]

As described above, the present invention has the following effects. (1) Since powders are conveyed in a laminar flow in a gravitational flow in a weightless state or in a microgravity state, classification is performed with high accuracy without causing uneven distribution of powder due to gravitational acceleration and meandering flow of powder due to turbulent flow regions. be able to.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment (in the case of an electric field) of a weightless powder classifier of the present invention.

FIG. 2 is a schematic configuration diagram showing another embodiment (in the case of a magnetic field) of the apparatus of the present invention.

FIG. 3 is a plan view around a magnetic field applying unit in FIG. 2;

[Explanation of symbols]

 10 Zero Gravity Chamber 12 Powder Air Flow Conveying Pipe 14 Electrostatic Powder Supplying Means 16 Blower 18 Cutout Valve 20 Powder Storage Tank 22 High Voltage Applying Means 24 Powder Classifying Means 26 Electric Field Applying Means 28 Power Supply 30 Magnetic Field Applying Means 32 Magnets 34 Magnets

Claims (4)

(57) [Claims] 1. A gravity-free powder classification method, characterized in that an electrostatically charged powder is conveyed in a laminar flow in a gravitational flow under zero gravity or microgravity, and an electric field is applied to the laminar flow to classify the powder. 2. A weightless powder classification method, characterized in that an electrostatically charged powder is conveyed in a laminar flow in a gravitational flow under zero gravity or microgravity, and a magnetic field is applied to the laminar flow to classify the powder. 3. A powder air transport tube is disposed in a weightless chamber,
An electrostatically charged powder supply means and a blower are connected to one end of the powder airflow transfer tube, and a powder classification means is provided at the other end of the powder airflow transfer tube, and an electric field applying means is provided in the middle of the powder airflow transfer tube. A weightless powder classifier characterized by having a. 4. A powder air flow transfer pipe is disposed in a weightless chamber,
An electrostatically charged powder supply means and a blower are connected to one end of the powder airflow transfer tube, and a powder classification means is provided at the other end of the powder airflow transfer tube, and a magnetic field applying means is provided in the middle of the powder airflow transfer tube. A weightless powder classifier characterized by having a.