Fine particle production apparatus and fine particle production method

Patent metadata

Field	Value
Publication number	US-11986885-B2
Application number	US-202017615775-A
Country	US
Kind code	B2
Filing date	Jun 4, 2020
Priority date	Jun 5, 2019
Publication date	May 21, 2024
Grant date	May 21, 2024

Abstract

Provided are a fine particle production apparatus and a fine particle production method that can control the particle sizes of fine particles, and efficiently produce a large amount of fine particles having good particle size uniformity. The present invention comprises: a raw material supply unit which supplies raw materials for fine particle production into thermal plasma flame; a plasma torch in which the thermal plasma flame is generated, and which evaporates the raw material supplied by the raw material supply unit by means of the thermal plasma flame to form a mixture in a gas phase state; and a plasma generation unit which generates thermal plasma flame inside the plasma torch. The plasma generation unit includes: a first coil which surrounds the plasma torch, a second coil which is installed below the first coil in the longitudinal direction of the plasma torch and surrounds the circumference of the plasma torch; a first power supply unit which supplies an amplitude-modulated first high-frequency current to the first coil; and a second power supply unit which supplies an amplitude-modulated second high-frequency current to the second coil. The degree of modulation of the first high-frequency current is smaller than the degree of modulation of the second high-frequency current.

First claim

The invention claimed is:

1. A fine particle production method using a thermal plasma flame generated inside a plasma torch,
there being provided a first coil surrounding a periphery of the plasma torch, a second coil disposed under the first coil and surrounding the periphery of the plasma torch, a first power source section supplying the first coil with first high frequency current amplitude-modulated, and a second power source section supplying the second coil with second high frequency current amplitude-modulated, the first coil and the second coil being arranged side by side in a longitudinal direction of the plasma torch, and the thermal plasma flame being generated by the first power source section and the second power source section, the method comprising:
a first step of supplying feedstock for fine particle production to the thermal plasma flame generated inside the plasma torch; and
a second step of evaporating the feedstock by use of the thermal plasma flame to transform the feedstock into a mixture in a gas phase state and cooling the mixture, wherein in the first step and the second step, the first power source section supplies the first coil with the first high frequency current amplitude-modulated, the second power source section supplies the second coil with the second high frequency current amplitude-modulated, and a degree of modulation of the first high frequency current is smaller than that of the second high frequency current,
wherein the first high frequency current supplied to the first coil by the first power source section has a region where current amplitude of the first high frequency current is high and a region where a current amplitude of the first high frequency current is lower than that in the region where the current amplitude of the first high frequency current is high, and the second high frequency current supplied to the second coil by the second power source section has a region where a current amplitude of the second high frequency current is high and a region where the current amplitude of the second high frequency current is lower than that in the region where the current amplitude of the second high frequency current is high, and
wherein in the first step, the first high frequency current supplied to the first coil by the first power source section and the second high frequency current supplied to the second coil by the second power source section are supplied at a same timing, and an amount of supply of the feedstock is increased in each region where the current amplitude of the first high frequency current and the region where the current amplitude of the second high frequency current are high.

2. The fine particle production method according to claim 1 , wherein in the second step, quenching gas is supplied to the thermal plasma flame to cool the mixture in a gas phase state.

3. The fine particle production method according to claim 2 , wherein in the first step, the feedstock is supplied into the thermal plasma flame with the feedstock being dispersed in a particulate form.

4. The fine particle production method according to claim 2 , wherein in the first step, the feedstock is dispersed in liquid to obtain a slurry, the slurry is transformed into droplets, and the droplets are supplied into the thermal plasma flame.

5. The fine particle production method according to claim 1 , wherein a current value of the second high frequency current amplitude-modulated and supplied to the second coil is 0 ampere in the region where the current amplitude of the second high frequency current is lower than that in the region where the current amplitude of the second high frequency current is high.

6. The fine particle production method according to claim 1 , wherein in the first step, the feedstock is supplied into the thermal plasma flame with the feedstock being dispersed in a particulate form.

7. The fine particle production method according to claim 1 , wherein in the first step, the feedstock is dispersed in liquid to obtain a slurry, the slurry is transformed into droplets, and the droplets are supplied into the thermal plasma flame.

Assignees

• Univ Nat Corp Kanazawa
• Nisshin Seifun Group Inc

Inventors

• Tanaka Yasunori
• Kodama Naoto
• Onda Kazuki
• Watanabe Shu
• Nakamura Keitaro
• SUEYASU Shiori

Classifications

• B22F9/14 Primary

  using electric discharge · CPC title

• B22F9/12

  starting from gaseous material · CPC title

• H05H1/42 Primary

  with provisions for introducing materials into the plasma, e.g. powder or liquid {(arc stabilising or constricting arrangements H05H1/3405; coaxial protecting fluids H05H1/341)} · CPC title

• B22F2202/13

  Use of plasma · CPC title

• B01J19/087 Primary

  employing electric or magnetic energy · CPC title