Device and method for creating dry particles

• US 6,174,469 B1
• Filed: 11/13/1998
• Issued: 01/16/2001
• Est. Priority Date: 05/13/1996
• Status: Expired due to Term

• Current Assignee: Universidad de Sevilla
• Original Assignee: Universidad de Sevilla
• Inventors: Ganan-Calvo, Alfonso
• Primary Examiner(s): THEISEN, MARY LYNN F
• Application Number:
  US09/191,592
• Time in Patent Office: 795 Days
• Field of Search: 264/7, 264/11, 264/12
• US Class Current: 264/12
• CPC Class Codes: B05B 1/02 designed to produce a jet, spray, or other discharge of particular shape or nature, e.g. in single drops, or having an outlet of particular shapeB05B1/26, B05B1/28, B05B1/34 take precedence
• CPC Class Codes: B05B 7/0475 with means for deflecting the peripheral gas flow towards the central liquid flow B05B7/0458 takes precedence
• CPC Class Codes: B05B 7/061 with several liquid outlets discharging one or several liquids
• CPC Class Codes: B05B 7/065 an inner gas outlet being surrounded by an annular adjacent liquid outlet
• CPC Class Codes: B05B 7/066 with an inner liquid outlet surrounded by at least one annular gas outlet
• CPC Class Codes: B05B 7/0884 the outlet orifices for jets constituted by a liquid or a mixture containing a liquid being aligned
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: F02M 43/04 Injectors peculiar thereto
• CPC Class Codes: F02M 67/10 Injectors peculiar thereto, e.g. valve less type
• CPC Class Codes: F02M 69/047 injectors with air chambers, e.g. communicating with atmosphere for aerating the nozzles F02M69/325 takes precedence
• CPC Class Codes: F23D 11/106 medium and fuel meeting at the burner outlet

Abstract

Atomized particles within a desired size range (e.g., 1 micron to about 5 microns) are produced from two immiscible fluids, a first fluid source containing the formulation to be atomized, and a second fluid source which is contained in a pressure chamber surrounding at least the area where the first liquid is to be provided. Upon presentation of the first fluid source to the second, the second fluid is forced out of an opening positioned in front of the flow path of the formulation. The first and second fluids interact dynamically to form a stable capillary microjet, which in turn results in the formation of a focusing funnel at the opening. Formulation passing through this a focusing funnel will atomize upon exiting the opening of the pressurized chamber without physically contacting the perimeter of the opening.

Claims

1. A method for producing particles, comprising the steps of:

forcing a first fluid through a channel of a feeding source in a manner which causes the first fluid to be expelled from an exit opening;

forcing a second fluid through a pressure chamber in a manner which causes the second fluid to exit the pressure chamber from an exit orifice in front of a flow path of the first fluid expelled from the exit opening of the feeding source;

forming a stable fluid-fluid interface in a manner which allows the first fluid to form a stable capillary jet focused on the exit orifice of the pressure chamber by the second fluid; and

allowing the stable jet of first fluid to exit the pressure chamber and disassociate to produce particles.

2. The method of claim 1, wherein the feeding source is a cylindrical channel and the first fluid is expelled from an exit opening having a diameter in the range of from about 0.002 to about 2 mm and wherein the opening in the pressure chamber has a diameter in the range of about 0.002 to about 2 mm and is positioned directly in front of a flow path of the exit opening of the channel.

3. The method of claim 2, further comprising:

allowing the liquid to evaporate from particles formed.

4. The method of claim 2, wherein the first fluid is a liquid and the second fluid is a gas.

5. The method of claim 4, wherein the liquid has a viscosity in a range of from about 0.3×

10<sup>−

3</sup> to about 5×

10<sup>−

2</sup> kg/m/sec, and wherein the liquid is forced through the channel at a rate in a range of about 0.01 nl/sec to about 100 μ

l/sec and further wherein the gas is forced through the opening of the pressure chamber at a rate in the range of from about 50 m/sec to about 2000 m/sec.

6. The method of claim 5, wherein the liquid is forced through the channel at a rate in a range of about 1 nl/sec to about 10 μ

l/sec and further wherein the gas is forced through the opening of the pressure chamber at a rate in the range of from about 100 to 500 m/sec.

7. The method of claim 4, wherein the liquid has a viscosity in a range of from about 10⁻

4 to about 1 kg/m/sec and the gas is air.

8. The method of claim 7, wherein the exit opening has a diameter in the range of from about 0.005 mm to about 0.4 mm, and

wherein the exit opening of the feeding source is separated by a distance of from about 0.002 to about 2 mm from the exit opening in the pressure chamber.

9. The method of claim 4, wherein gas is forced into an area around the feeding source outlet at a pressure in the range of 10 to 50,000 mBar above atmospheric pressure and further wherein the liquid has a viscosity in the range of from 10⁻

4 to 1 kg/m/sec.

10. The method of claim 4, wherein gas is forced into an area around the feeding source outlet at a pressure in the range of 100-2000 mBar above atmospheric pressure.

11. The method of claim 4, wherein gas from the pressure chamber surrounds liquid exiting the feeding source outlet which liquid is drawn into the orifice concentrically being focused by the gas flowing out of the outlet, and further wherein the aerosolized particles formed are uniform in size to the extent of having a relative size standard deviation of 3 to 30%.