Device for granulating powders by cryogenic atomisation

Patent metadata

Field	Value
Publication number	US-11260397-B2
Application number	US-201615770915-A
Country	US
Kind code	B2
Filing date	Nov 3, 2016
Priority date	Nov 4, 2015
Publication date	Mar 1, 2022
Grant date	Mar 1, 2022

Abstract

A device for granulating powders by cryogenic atomisation, characterised in that it comprises: a device for mixing powders by cryogenic fluid, comprising at least one chamber for mixing powders, comprising a cryogenic fluid; and a device for atomising a suspension of powders mixed by the device for mixing powders in order to allow a granulation of the powders, comprising a way of fractionating the suspension of powders making it possible to adjust the size of the droplets of powders to be atomised, and a method for adjusting the moisture of the mixed powders and/or the moisture of the atomisation atmosphere.

First claim

The invention claimed is:

1. A device for granulating powders by cryogenic atomisation, comprising:
a device for mixing powders by a cryogenic fluid, comprising at least one chamber for mixing powders, comprising the cryogenic fluid, wherein the cryogenic fluid is a liquified gas and chemically inert; and
a device for atomising a suspension of powders mixed by the device for mixing powders in order to allow for a granulation of the powders, wherein the device fractionates the suspension of powders making it possible to adjust the size of droplets of the powders and adjusts the moisture of the mixed powders and/or moisture of the atomisation atmosphere and wherein for fractionating the suspension of powders, the device is configured to allow for the adjusting of the diameter of the droplets of powders to be atomised, in such a way that the diameter of the droplets of powders is defined according to the following relationship:

d
o

D

=

G
⁢

{

fD
v

,

1
We

,

1
Re

,

A
D

}

with We=ρν 2 ·(d o )/σ and Re=ρd o ν/μ,
where:
f represents the vibration frequency of the device for atomising,
ν represents the speed of the suspension of powders,
ρ represents the density of the suspension of powders to be fractionated,
μ represents the viscosity of the suspension of powders to be fractionated,
σ represents the surface tension of the suspension of powders to be fractionated,
A represents the oscillation amplitude of an atomisation nozzle of the device for atomising,
d 0 represents the diameter of the droplets, and
D represents the diameter of an atomisation nozzle of the device for atomising.

2. The device according to claim 1 , wherein the powders to be mixed are actinide powders.

3. The device according to claim 1 , wherein the cryogenic fluid comprises a slightly hydrogenated liquid, which is a liquid comprising at most one hydrogen atom per molecule of liquid, having a boiling temperature less than that of water, and wherein the cryogenic fluid is a gas at room temperature and a liquid at a temperature lower than room temperature.

4. The device as claimed in claim 1 , wherein the device for mixing further comprises:
a chamber for supplying powders in order to allow the powders to be introduced into the at least one chamber for mixing,
means for agitation in the mixing chamber so as to allow the mixing of the powders placed in suspension in the cryogenic fluid.

5. The device according to claim 4 , wherein the device for mixing comprises means for mixing of the at least one chamber for mixing according to a gyroscopic movement.

6. The device according to claim 4 , wherein the device for mixing comprises:
a plurality of mixing chambers of the powders, arranged successively in series one after the other, the chamber for supplying powders allowing for the introduction of powders into at least the first mixing chamber,
a plurality of systems for restricting passage of the powders, with each system for restricting the passage being located between two successive mixing chamber, in order to constrain the distribution of powders from one mixing chamber to the next, with each mixing chamber comprising the cryogenic fluid and means for agitation so as to allow the mixing of the powders placed in suspension in the cryogenic fluid.

7. The device according to claim 6 , wherein the systems for restricting the passage comprise screens and/or diaphragms.

8. The device according to claim 4 , wherein the means for agitation comprise mobile mixing devices.

9. The device according to claim 4 , wherein the means for agitation comprise means for generating vibrations.

10. The device according to claim 4 , wherein the device for mixing comprises a system of electrostatic charge of the powders intended to be introduced into the mixing chamber or chambers.

11. The device according to claim 10 , wherein a portion of the powders is put into contact with a portion of the electrostatic charge system in order to be positively electrostatically charged and wherein the other portion of the powders is put into contact with the other portion of the electrostatic charge system in order to be negatively electrostatically charged, in order to allow for a differentiated local agglomeration.

12. The device as claimed in claim 1 , wherein the cryogenic fluid is liquefied nitrogen.

13. Method for granulating powders by cryogenic atomisation using the device claim 1 , and comprising the following steps:
a) introducing powders and cryogenic fluid into at least one chamber of the device for mixing powders by a cryogenic fluid in order to obtain a suspension of powders and of cryogenic fluid,
b) atomising of the suspension of powders and of cryogenic fluid through the device for atomising in order to allow for a granulation of the powders, wherein the suspension of powders are fractionated making it possible to adjust the size of droplets of the powders and adjusts the moisture of the mixed powders and/or moisture of the atomisation atmosphere and wherein the diameter of the droplets of powders to be atomised are adjustable in such a way that the diameter of the droplets of powders is defined according to the following relationship:

d
o

D

=

G
⁢

{

fD
v

,

1
We

,

1
Re

,

A
D

}

with We=ρν 2 ·(d o )/σ and Re=ρd o ν/μ,
where:
f represents the vibration frequency of the device for atomising,
ν represents the speed of the suspension of powders,
ρ represents the density of the suspension of powders to be fractionated,
μ represents the viscosity of the suspension of powders to be fractionated,
α represents the surface tension of the suspension of powders to be fractionated,
A represents the oscillation amplitude of an atomisation nozzle of the device for atomising,
d 0 represents the diameter of the droplets, and
D represents the diameter of an atomisation nozzle of the device for atomising, and
c) obtaining of granu

Assignees

• Commissariat Energie Atomique

Inventors

• Brothier Méryl
• Vaudez Stéphane

Classifications

• B22F9/082

  atomising using a fluid (using centrifugal force B22F9/10) · CPC title

• B01J2/04 Primary

  in a gaseous medium {(if combined with suspending the material in a gas, e.g. fluidised beds B01J2/16)} · CPC title

• B02C19/186 Primary

  Use of cold or heat for disintegrating (B02C4/44, B02C7/17, B02C11/08 take precedence) · CPC title

• B01J2/18

  using a vibrating apparatus · CPC title

• B02C23/38

  in apparatus having multiple crushing or disintegrating zones · CPC title