Gas injection for de-agglomeration in particle coating reactor
A method of coating particles includes dispensing particles into a vacuum chamber to form a particle bed in at least a lower portion of the chamber that forms a half-cylinder, evacuating the chamber through a vacuum port in an upper portion of the chamber, rotating a paddle assembly such that a plurality of paddles orbit a drive shaft to stir the particles in the particle bed, injecting a reactant or precursor gas through a plurality of channels into the lower portion of the chamber as the paddle assembly rotates to coat the particles, and injecting the reactant or precursor gas or a purge gas through the plurality of channels at a sufficiently high velocity such that the reactant or precursor a purge gas de-agglomerates particles in the particle bed.
1. A method of coating particles, comprising:
dispensing particles into a vacuum chamber to form a particle bed in at least a lower portion of the vacuum chamber that forms a half-cylinder;
evacuating the vacuum chamber through a vacuum port in an upper portion of the vacuum chamber;
rotating a paddle assembly such that a plurality of paddles orbit a drive shaft to stir the particles in the particle bed;
injecting a reactant or precursor gas through a plurality of channels into the lower portion of the vacuum chamber as the paddle assembly rotates to coat the particles; and
injecting the reactant or precursor gas or a purge gas through the plurality of channels at a sufficiently high velocity such that the reactant or precursor or purge gas de-agglomerates particles in the particle bed,
wherein the particles substantially stay in the particle bed during the injecting of the reactant or precursor or purge gas through the plurality of channels and the rotating of the paddle assembly such that the plurality of paddles orbit the drive shaft to stir the particles in the particle bed.
2. The method of claim 1 , comprising injecting the reactant or precursor gas at a sufficiently high velocity such that the reactant or precursor gas de-agglomerates particles.
3. The method of claim 2 , comprising injecting the reactant or precursor gas at a velocity less than 10 m/s.
4. The method of claim 1 , comprising injecting the purge gas at a sufficiently high velocity such that the purge gas de-agglomerates particles.
5. The method of claim 4 , comprising injecting the purge gas at a greater velocity than the reactant or precursor gas is injected.
6. The method of claim 5 , comprising injecting the purge gas at a velocity of 30-200 m/s.
7. The method of claim 5 , comprising injecting the purge gas at a velocity greater than 50 m/s.
8. The method of claim 1 , comprising injecting the reactant or precursor or purge gas at sufficient low velocity to avoid formation of rat-holes.
9. The method of claim 1 , comprising injecting the reactant or precursor or purge gas at sufficient low velocity to avoid blowing of powder off of the powder particle bed.
10. The method of claim 1 , comprising injecting the reactant or precursor or purge gas at sufficient low velocity to avoid jet milling of the particles.
11. The method of claim 1 , wherein the particles comprise an active pharmaceutical ingredient.
12. The method of claim 11 , wherein the particles have an average particle size of 1-30 μm.
13. The method of claim 1 , comprising re-agglomerating the particles before removal of the particles from the vacuum chamber.
14. The method of claim 13 , comprising multiple cycles of de-agglomeration and deposition.
15. A reactor for coating particles, comprising:
a stationary vacuum chamber to hold particles in a particle bed to be coated;
a paddle assembly including a rotatable drive shaft and one or more paddles in the vacuum chamber, the paddles connected to the drive shaft such that rotation of the drive shaft by a motor stirs the particles in the particle bed;
a chemical delivery system including a gas injection assembly to a deliver a precursor or reactant gas and a purge gas into a lower portion of the vacuum chamber;
at least one flow regulator to control a flow rate of the precursor or reactant gas and the purge gas;
a controller configured to
cause the chemical delivery system to inject the reactant or precursor gas into the lower portion of the vacuum chamber as the paddle assembly rotates to coat the particles; and
cause the chemical delivery system and the at least one flow regulator to inject the reactant or precursor gas or the purge gas into the vacuum chamber at a sufficiently high velocity such that the reactant or precursor or purge gas de-agglomerates particles in the particle bed,
wherein the particles substantially stay in the particle bed during the injecting of the reactant or precursor or purge gas through the lower portion of the vacuum chamber and during the rotating of the paddle assembly such that the one or more paddles stir the particles in the particle bed.
16. The reactor of claim 15 , wherein the controller is configured to cause the at least one flow regulator to flow the reactant or precursor gas into the vacuum chamber at a sufficiently high velocity such that the reactant or precursor gas de-agglomerates particles.
17. The reactor of claim 16 , wherein the controller is configure to cause the at least one flow regulator to flow the reactant or precursor gas into the vacuum chamber at a velocity less than 10 m/s.
18. The reactor of claim 15 , wherein the controller is configured to cause the at least one flow regulator to flow the purge gas into the vacuum chamber at a sufficiently high velocity such that the purge gas de-agglomerates particles.
19. The reactor of claim 18 , wherein the controller is configured to cause the at least one flow regulator to flow the purge gas into the vacuum chamber at a greater velocity than the reactant or precursor gas.
20. The reactor of claim 19 , wherein the controller is configured to cause the at least one flow regulator to flow the purge gas into the vacuum chamber at a velocity of 30-200 m/s.