Abstract: A method to monitor a secondary drying phase of a freeze-drying process comprises initial steps in which is provided to perform pressure rise tests at different time and to calculate a respective value of experimental desorption rate of product (steps 1 to 3). Subsequently, the method provides to estimate initial conditions and kinetic constants of a kinetic model of the process (step 4) and to calculate at time t=t2 a respective residual moisture content and a respective desorption rate (step 5). The method can be performed in a freeze-dryer apparatus which includes a drying chamber that contains a product to be dried and can be isolated to perform pressure rise tests.

Abstract: A freeze-drying process includes a primary drying phase. Within this phase, a test is performed for causing a variation of partial pressure of solvent inside a drying chamber. At the beginning of the test, a product sublimation flux, a total pressure and a partial pressure of the solvent in the drying chamber are measured. A product temperature is estimated at the interface of sublimation at the beginning of the test. The solvent vapor pressure at the interface of sublimation is calculated as is a resistance of a dried layer of the product to the vapor flow of the solvent. Next, a thickness of a frozen layer of the product is calculated and a coefficient of heat transfer between heating surface and product is also calculated. An initial temperature profile of the frozen product is then calculated as is a total pressure in the drying chamber. A value of the product temperature at the interface of sublimation at the beginning of test is determined and a time constant of the freeze-drying process is calculated.

Abstract: A method for monitoring and/or controlling and a freeze drying process in a freeze dryer apparatus provided with a drying chamber having a temperature-controlled shelf supporting containers of a product to be dried, comprises during a primary drying phase of the freeze drying process the steps of: isolating the drying chamber closing an isolating valve thereof and sensing and collecting pressure values inside the drying chamber for a defined pressure collecting time and a shelf temperature of the temperature-controlled shelf (Step 1); calculating a product temperature of product and a plurality of process/product related parameters (Step 2); calculating a new shelf temperature and a sequence of shelf temperatures up to the end of the primary drying phase, that maximizes a sublimation rate of the product maintaining the product temperature below a maximum allowable product temperature.

Abstract: A freeze-drying process includes a primary drying phase. Within this phase, a test is performed for causing a variation of partial pressure of solvent inside a drying chamber. At the beginning of the test, a product sublimation flux, a total pressure and a partial pressure of the solvent in the drying chamber are measured. A product temperature is estimated at the interface of sublimation at the beginning of the test. The solvent vapor pressure at the interface of sublimation is calculated as is a resistance of a dried layer of the product to the vapor flow of the solvent. Next, a thickness of a frozen layer of the product is calculated and a coefficient of heat transfer between heating surface and product is also calculated. An initial temperature profile of the frozen product is then calculated as is a total pressure in the drying chamber. A value of the product temperature at the interface of sublimation at the beginning of test is determined and a time constant of the freeze-drying process is calculated.

Abstract: A system for monitoring the lyophilization process of a product in containers (4, 4a, 4b) arranged inside a lyophilization chamber, including a temperature measurement system (6) associated with each container housed inside (10) the lyophilization chamber, capable of surveying local temperature data for each container. The system includes a wireless communication system (8) for the surveyed temperature data and a processing module (16) for said data, located externally to the lyophilization chamber, programmed to determine at least one parameter indicative of the progress of the lyophilization process not measured by the measurement system, through the use of a predetermined representation model of the process, capable of correlating a local temperature value of the container with the parameter.

Abstract: A method for monitoring and/or controlling a freeze drying process is characterized by the use of an estimator algorithm. A product to be dried is arranged in at least one container on a temperature-controlled shelf in the drying chamber of a freeze dryer apparatus. During a primary drying phase, the drying chamber is isolated by closing an isolating valve. Pressure values inside the drying chamber are measured and collected for a defined pressure collecting time and a temperature of the temperature-controlled shelf. A product temperature for the product is calculated together with a plurality of process/product related parameters. A new shelf temperature is calculated with a sequence of shelf temperatures up to the end of the primary drying phase that maximizes a sublimation rate of the product in order to maintain the product temperature below a maximum allowable product temperature.

Abstract: A method to monitor a secondary drying phase of a freeze-drying process comprises initial steps in which is provided to perform pressure rise tests at different time and to calculate a respective value of experimental desorption rate of product (steps 1 to 3). Subsequently, the method provides to estimate initial conditions and kinetic constants of a kinetic model of the process (step 4) and to calculate at time t=t2 a respective residual moisture content and a respective desorption rate (step 5). The method can be performed in a freeze-dryer apparatus which includes a drying chamber that contains a product to be dried and can be isolated to perform pressure rise tests.

Abstract: A system is described for monitoring the lyophilisation process of a product in containers (4, 4a, 4b) arranged inside a lyophilisation chamber, comprising a temperature measurement system (6) associated with each container housed inside (10) said lyophilisation chamber, capable of surveying local temperature data for each container. The system includes: a wireless communication system (8) for the surveyed temperature data; and a processing module (16) for said data, located externally to the lyophilisation chamber, programmed to determine at least one parameter indicative of the progress of the lyophilisation process not measured by the measurement system, by means of a predetermined representation model of the process, capable of correlating a local temperature value of the container with said parameter.