Monitoring Freeze Drying With Gas Measurement On Vacuum Pump Exhaust
AssigneeIma Life North America Inc.
InventorsJozef A.W.M. Corver, Cario J.J.M. De Best, Francis W. DeMarco, David Debo
Life of this patent
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Abstract
Parameters of a freeze drying process are monitored by measuring trace materials in the vacuum pump exhaust. The measurements are made using techniques such as acousto-optic spectrometry, multipass cavity-enhanced absorption spectrometry (CEAS) and cavity ring-down spectrometry (CRDS). The technique may be used to diagnose problems such as leakage in the freeze drying shelves, leakage in the condensation coils, leaks from atmosphere in the chambers and the presence of residual cleaning materials. The technique may also be used to monitor the presence of water vapor in the exhaust of a secondary drying process.
Claims31
A method for analyzing a gas stream containing a solvent vapor, comprising the steps of:
- removing the solvent vapor from the gas stream to produce a non-condensable gas stream;
- compressing the non-condensable gas stream to produce a compressed gas stream;
- and
- measuring a concentration of a material in the compressed gas stream.
A method for freeze drying a product, the method comprising the steps of:
- removing heat from the product to freeze a solvent contained in the product;
- causing sublimation of the frozen solvent in the product to form a solvent vapor contained in a low-pressure gaseous effluent flowing away from the product;
- condensing at least some of the solvent vapor from the low-pressure gaseous effluent;
- compressing the gaseous effluent using a vacuum pump;
- and
- measuring a concentration of at least one trace material in the gaseous effluent on a high-pressure side of the vacuum pump.
A freeze dryer system, comprising:
- a freeze drying chamber for containing product during the freeze drying process;
- a condensation chamber in communication with the freeze drying chamber and comprising surfaces for condensing a solvent vapor from exhaust gas received from the freezer drying chamber;
- a vacuum pump having a low pressure inlet and a high pressure outlet, the low pressure end of the vacuum pump being in communication with the condensation chamber;
- and
- a testing apparatus connected for receiving exhaust gas from the high pressure outlet of the vacuum pump, the testing apparatus being for measuring a presence of a material contained in the exhaust gas.
A method for freeze drying a product, the method comprising the steps of:
- removing heat from the product in a freeze drying chamber to freeze a solvent contained in the product;
- causing sublimation of the frozen solvent in the product to form a solvent vapor contained in a low-pressure gaseous effluent flowing away from the product;
- compressing the gaseous effluent using a vacuum pump;
- monitoring the freeze drying by measuring a concentration of the solvent vapor in the gaseous effluent on the high-pressure side of the vacuum pump.
Dependencies are inferred from the claim text.