Dipartimento di Scienza dei Materiali e Ingegneria Chimica, Politecnico di Torino, Torino, Italy.
J Pharm Sci. 2011 Feb;100(2):732-42. doi: 10.1002/jps.22311. Epub 2010 Aug 26.
This paper is focused on the in-line monitoring of the secondary drying phase of a lyophilization process. An innovative software sensor is presented to estimate reliably the residual moisture in the product and the time required to complete secondary drying, that is, to reach the target value of the residual moisture or of the desorption rate. Such results are obtained by coupling a mathematical model of the process and the in-line measurement of the solvent desorption rate and by means of the pressure rise test or another sensors (e.g., windmills, laser sensors) that can measure the vapor flux in the drying chamber. The proposed method does not require extracting any vial during the operation or using expensive sensors to measure off-line the residual moisture. Moreover, it does not require any preliminary experiment to determine the relationship between the desorption rate and residual moisture in the product. The effectiveness of the proposed approach is demonstrated by means of experiments carried out in a pilot-scale apparatus: in this case, some vials were extracted from the drying chamber and the moisture content was measured to validate the estimations provided by the soft-sensor.
本文专注于冻干过程中二次干燥阶段的在线监测。提出了一种创新的软件传感器，能够可靠地估计产品中的残余水分和完成二次干燥所需的时间，即达到残余水分或解吸速率的目标值。通过耦合过程的数学模型和溶剂解吸速率的在线测量，并通过压力升高测试或其他传感器（例如风车、激光传感器）来测量干燥室内的蒸汽通量，获得了这样的结果，这些传感器可以测量干燥室内的蒸汽通量。所提出的方法在操作过程中不需要提取任何小瓶，也不需要使用昂贵的传感器来离线测量残余水分。此外，它不需要任何初步实验来确定产品中的解吸速率和残余水分之间的关系。通过在中试设备中进行的实验验证了所提出方法的有效性：在这种情况下，从小瓶中提取了一些小瓶，并测量了水分含量，以验证软传感器提供的估计值。
