Liquid substances freeze-drying systems and methods
First Claim
1. In a system for the spray-freeze-drying of a fluid substance having a substantial content of solids dissolved in a liquid that includes a vertically elongated vessel having top, bottom and central portions, atomizing means including a nozzle positioned centrally in said vessel adjacent said top portion to deliver atomized particles of said fluid substance into said vessel, fluidizing means in said bottom portion to fluidize particles of frozen product formed in said vessel by upward flow of process gas into said vessel including a bottom opening in said bottom portion, cooling means to cool gas circulating in said system, heating means to heat gas circulating in said system and gas circulation means for introducing and withdrawing process gas into and from said vessel, the improvement which comprises:
- a top opening in said top portion of said vessel,said gas circulation means comprising conduit means connecting said top opening to said bottom opening,pump means associated with said conduit means to move said process gas thorough said conduit means,a heat pump including a hot side and a cold side,a hot tank connected to said hot side,a cold tank connected to said cold side,first plumbing means connecting said hot tank to said heating means for circulation of heat exchange fluid between said hot tank and said heating means, andsecond plumbing means connecting said cold tank to said cooling means for circulation of heat exchange fluid between said cold tank and said cooling means.
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Accused Products
Abstract
Spray-freeze-drying systems and methods are disclosed for converting a wide variety of liquid substances into dry powder that may be reconstituted into the original substance by addition of water or other liquid that had been removed therefrom. Such systems and methods involve repetitive cycles of four operational steps, i.e., freezing, drying, defrosting and resetting and are characterized by: spraying the liquid substance downwardly in a vessel while surrounding the spray with a downward flow of process gas during the freezing step and by utilizing a heat pump for energy recapture to increase efficiency of operation.
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Citations
27 Claims
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1. In a system for the spray-freeze-drying of a fluid substance having a substantial content of solids dissolved in a liquid that includes a vertically elongated vessel having top, bottom and central portions, atomizing means including a nozzle positioned centrally in said vessel adjacent said top portion to deliver atomized particles of said fluid substance into said vessel, fluidizing means in said bottom portion to fluidize particles of frozen product formed in said vessel by upward flow of process gas into said vessel including a bottom opening in said bottom portion, cooling means to cool gas circulating in said system, heating means to heat gas circulating in said system and gas circulation means for introducing and withdrawing process gas into and from said vessel, the improvement which comprises:
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a top opening in said top portion of said vessel, said gas circulation means comprising conduit means connecting said top opening to said bottom opening, pump means associated with said conduit means to move said process gas thorough said conduit means, a heat pump including a hot side and a cold side, a hot tank connected to said hot side, a cold tank connected to said cold side, first plumbing means connecting said hot tank to said heating means for circulation of heat exchange fluid between said hot tank and said heating means, and second plumbing means connecting said cold tank to said cooling means for circulation of heat exchange fluid between said cold tank and said cooling means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. In a system for the spray-freeze-drying of a fluid substance having a substantial content of solids dissolved in a liquid that includes a vertically elongated vessel having top, bottom and central portions, atomizing means including a nozzle positioned centrally in said vessel adjacent said top portion to deliver atomized particles of said fluid substance into said vessel, fluidizing means in said bottom portion to fluidize particles of frozen product formed in said vessel by upward flow of process gas into said vessel including a bottom opening in said bottom portion, cooling means to cool gas circulating in said system, heating means to heat gas circulating in said system and gas circulation means for introducing and withdrawing process gas into and from said vessel, the improvement which comprises:
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a top opening in said top portion of said vessel, process gas flow control means to cause a portion of said process gas to pass downwardly in said vessel around said nozzle conduit means to remove process gas from said top opening and convey a first portion thereof to said bottom opening and a second portion thereof to said flow control means, and valve means associated with said conduit means to vary the volumes of said first and second portions of said process gas. - View Dependent Claims (16)
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17. In a method for the spray-freeze-drying of a fluid substance having a substantial content of solids dissolved in a liquid in a processing system including the steps of (a) spraying said fluid substance as a downwardly projected spray into a vertically elongated zone defined by boundary walls and including a top, central and bottom portions, (b) freezing said atomized particles by contact with chilled gas circulated within said zone, (c) fluidizing a bed of said frozen particles within said bottom portion by upward passage of gas through said bed, (d) drying said frozen particles in said fluidized bed by subliming said liquid therefrom to produce dried particles consisting essentially of said solids content and (e) removing said dried particles from said zone, the improvement which comprises:
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maintaining said system at essentially atmospheric pressure throughout the course of said method, exhausting gas from said top portion of said zone throughout the course of said method, injecting gas into said bottom portion of said zone throughout the course of said method, and during said spraying step, surrounding said projected spray with a downwardly flow of gas. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24)
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25. In a method for the spray-freeze-drying of a fluid substance having a substantial content of solids dissolved in a liquid including the steps of (a) spraying said fluid substance into a vertically elongated zone defined by boundary walls and including a top, central and bottom portions, (b) freezing sprayed particles of said fluid substance by contact with chilled process gas circulated within said zone, (c) fluidizing a bed of frozen particles of said substance within said bottom portion by upward passage of process gas through said bed, (d) drying said frozen particles in said fluidized bed at essentially atmospheric pressure by subliming said liquid therefrom to produce dried particles consisting essentially of said solids content and (e) removing said dried particles from said zone, the improvement which comprises:
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providing a first quantity and a second quantity of heat exchange liquid, withdrawing heat from said first quantity to reduce the temperature thereof to below the freezing point of said substance, heating said second quantity at least partially with heat withdrawn from said first quantity, during said freezing step, using said first quantity to chill said process gas and said zone and during said drying step, using said second quantity to heat said process gas. - View Dependent Claims (26, 27)
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Specification