Process for drying a material from solution
First Claim
1. A process for obtaining a solid or semi-solid material by drying a solution thereof, comprising the steps of:
- (a) subjecting the solution to vacuum-assisted freezing by introducing the solution into an evacuated chamber in the form of a uniform spray, the droplets of which are at a sufficiently low temperature to ensure that they freeze at the vacuum pressure inside the chamber; and
(b) collecting the frozen droplets of solution on a collecting surface which is positioned in the chamber such that it collects the frozen solution and which is adapted to retain the droplets until they have been dried by sublimation, and controlling the temperature of the collecting surface and the pressure within the chamber so that the frozen solvent sublimes from the collected and retained frozen droplets, the collecting surface having been prepared by being brought to an initial temperature which is not greater than the melting point of the frozen solution at the initial pressure, which is the pressure within the chamber when the spray is introduced thereto, the temperature of the collecting surface and the pressure within the chamber being maintained throughout the sublimation process so as to prevent partial remelting of the frozen droplets as sublimation occurs.
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Accused Products
Abstract
A process for drying a solution containing the material. The process includes the following steps: (1) subjecting the solution to vacuum-assisted freezing by introducing the solution into an evacuated chamber in the form of a spray, the droplets of which are at a sufficiently low temperature to ensure that they freeze at the vacuum pressure inside the chamber; (2) collecting the frozen droplets of the solution on a collecting surface of the chamber and controlling the temperature of the collecting surface and the pressure within the chamber so that the frozen solvent sublimes from the collected frozen droplets. The collecting surface is prepared by being brought to an initial temperature which is not greater than the melting point of the frozen solution at the initial pressure, which is the pressure within the chamber when the spray is introduced, the temperature of the collecting surface and the pressure within the chamber being maintained throughout the sublimation process so as to prevent partial remelting of the frozen droplets as sublimation occurs
144 Citations
20 Claims
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1. A process for obtaining a solid or semi-solid material by drying a solution thereof, comprising the steps of:
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(a) subjecting the solution to vacuum-assisted freezing by introducing the solution into an evacuated chamber in the form of a uniform spray, the droplets of which are at a sufficiently low temperature to ensure that they freeze at the vacuum pressure inside the chamber; and (b) collecting the frozen droplets of solution on a collecting surface which is positioned in the chamber such that it collects the frozen solution and which is adapted to retain the droplets until they have been dried by sublimation, and controlling the temperature of the collecting surface and the pressure within the chamber so that the frozen solvent sublimes from the collected and retained frozen droplets, the collecting surface having been prepared by being brought to an initial temperature which is not greater than the melting point of the frozen solution at the initial pressure, which is the pressure within the chamber when the spray is introduced thereto, the temperature of the collecting surface and the pressure within the chamber being maintained throughout the sublimation process so as to prevent partial remelting of the frozen droplets as sublimation occurs. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A drying apparatus for obtaining a solid or semi-solid material by drying a solution thereof, comprising:
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a) a vacuum chamber into which a solution is introduced in the form of a spray; b) means for evacuating the chamber to a sufficiently low pressure to cause the droplets of spray to undergo vacuum-assisted freezing upon introduction to the chamber; c) a collecting surface positioned in the chamber such that it collects the frozen solution and a first temperature control means for controlling the temperature of the collecting surface, the collecting surface being adapted to retain the frozen droplets thereon until they have been dried by sublimation; and d) means for controlling the vacuum pressure such that sublimation of the frozen solvent takes place from the frozen solution. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
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Specification