Method and apparatus for continuous freeze drying
First Claim
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1. A freeze drying apparatus, comprising:
- (A) A drying chamber means;
(B) At least two condenser means;
(C) A quantity of molecular sieve within each of said condenser means;
(D) A vacuum pump;
(E) Valving means for providing vacuum tight communication sequentially between each of said condenser means and said drying chamber means and said vacuum pump, and for opening each of said condenser means sequentially to atmospheric pressure; and
(F) Automatic control means for opening and closing valve positions in said valving means, so that during a first period of time when said vacuum pump is in operation said atmospheric pressure is reduced within said drying chamber means and the first of said condenser means, while a second condenser means is opened to said atmospheric pressure, said automatic control means further providing means for heating said molecular sieve within said second condenser means, so that vapors that have previously been adsorbed by said sieve within said second condenser means are driven out of said sieve in said second condenser means, and are expelled to the atmosphere through said opening to said atmospheric pressure in said second condenser means, said automatic control means further providing means for turning off said heating means for said sieve within said second condenser means in order to permit said sieve within said second condenser means to cool down, said automatic control means further providing, during a second period of time immediately following said first period of time, means for opening and closing valve positions in said valving means, so that when said vacuum pump is in operation, said pressure is continued to be reduced in said drying chamber, and said atmospheric pressure is reduced in said second condenser means, while said first condenser means is opened to said atmospheric pressure, said automatic control means further providing a means for heating said molecular sieve within said first condenser, so that condensable vapors that have previously been adsorbed by said sieve within said first condenser are driven out of said sieve within said first condenser, and are expelled to said atmosphere through said opening to said atmospheric pressure in said first condenser, said automatic control means further providing means for turning off said heating means for said sieve within said first condenser in order to permit said sieve within said first condenser to cool down, and then repeating, during a third period of time, the operations that occurred during said first period of time, and so on, so that adsorbable vapors diffusing from said drying chamber means are adsorbed by said molecular sieve in said condenser means on a continuous basis.
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Abstract
A method and apparatus for freeze drying heat sensitive aqueous products on a continuous basis, utilizing molecular sieves to sequester the sublimating water vapor, is described. At least two beds of sieve are used sequentially, one being heat regenerated while another is actively adsorbing condensable vapors. Exotherm is controlled during freeze drying, and bed regeneration may be accomplished without the use of a purge gas. The advantages of certain types and sizes of molecular sieves, in a continuous freeze drying procedure, is discussed.
21 Citations
28 Claims
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1. A freeze drying apparatus, comprising:
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(A) A drying chamber means; (B) At least two condenser means; (C) A quantity of molecular sieve within each of said condenser means; (D) A vacuum pump; (E) Valving means for providing vacuum tight communication sequentially between each of said condenser means and said drying chamber means and said vacuum pump, and for opening each of said condenser means sequentially to atmospheric pressure; and (F) Automatic control means for opening and closing valve positions in said valving means, so that during a first period of time when said vacuum pump is in operation said atmospheric pressure is reduced within said drying chamber means and the first of said condenser means, while a second condenser means is opened to said atmospheric pressure, said automatic control means further providing means for heating said molecular sieve within said second condenser means, so that vapors that have previously been adsorbed by said sieve within said second condenser means are driven out of said sieve in said second condenser means, and are expelled to the atmosphere through said opening to said atmospheric pressure in said second condenser means, said automatic control means further providing means for turning off said heating means for said sieve within said second condenser means in order to permit said sieve within said second condenser means to cool down, said automatic control means further providing, during a second period of time immediately following said first period of time, means for opening and closing valve positions in said valving means, so that when said vacuum pump is in operation, said pressure is continued to be reduced in said drying chamber, and said atmospheric pressure is reduced in said second condenser means, while said first condenser means is opened to said atmospheric pressure, said automatic control means further providing a means for heating said molecular sieve within said first condenser, so that condensable vapors that have previously been adsorbed by said sieve within said first condenser are driven out of said sieve within said first condenser, and are expelled to said atmosphere through said opening to said atmospheric pressure in said first condenser, said automatic control means further providing means for turning off said heating means for said sieve within said first condenser in order to permit said sieve within said first condenser to cool down, and then repeating, during a third period of time, the operations that occurred during said first period of time, and so on, so that adsorbable vapors diffusing from said drying chamber means are adsorbed by said molecular sieve in said condenser means on a continuous basis. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A method for freeze drying heat sensitive materials on a continuous basis, which comprises the steps of:
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(A) Placing frozen samples within a drying chamber means; (B) Filling a plurality of condensing means with molecular sieve; (C) Connecting said drying chamber means in vacuum tight engagement sequentially with said condensing means; (D) Providing a source of vacuum for said drying chamber means and said condensing means; (E) Reducing the pressure in said drying chamber means and in a first condensing means of said plurality of condensing means, while a second condensing means of said plurality of condensing means is at atmospheric pressure by means for opening a valve-to-atmosphere in said second condensing means; (F) Heating said molecular sieve in said second condensing means so that condensable vapors within said molecular sieve in said second condensing means are driven off and expelled to said atmosphere by said valve-to-atmosphere means in said second condensing means; (G) Turning off said heating of said molecular sieve in said second condensing means after said vapors in said molecular sieve in said second condensing means are expelled to said atmosphere; (H) Permitting said molecular sieve in said second condensing means to cool down; (I) Using means for closing said valve-to-atmosphere in said second condensing means; (J) Connecting said second condensing means to said drying chamber means and said source of vacuum, while simultaneously raising the pressure to said atmospheric pressure by means for opening a valve-to-atmosphere in said first condensing means; (K) Heating said molecular sieve is said first condensing means so that condensable vapors within said molecular sieve in said first condensing means are driven off and expelled to said atmosphere by means of said valve-to-atmosphere in said first condensing means; (L) Turning off said heating of said molecular sieve in said first condensing means after said vapors in said molecular sieve in said first condensing means are expelled to said atmosphere; (M) Permitting said molecular sieve in said first condensing means to cool down; (N) Using means for closing said valve-to-atmosphere in said first condensing means; (O) Connecting said first condensing means to said drying chamber means and said source of vacuum, while simultaneously raising the pressure to said atmospheric pressure by means for opening a valve-to-atmosphere in said second condensing means; and (P) Repeating the steps of (F), (G), (H), and (I), and so on, so that condensable vapors eminating from said frozen samples within said drying chamber means are sequestered by said molecular sieve in said condensing means on a continuous basis. - View Dependent Claims (25, 26, 27, 28)
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Specification