Pressure thermometering method during lyophilizing process

Abstract

The method is based on the basic rule that under equilibrium state, it is a single valued function between temperature of ice crystal and its saturated vapor pressure. In lyophilization process, water vapor flux from a freeze-dry room to a cold trap is stopped short. The invented method is an untouched temperature measurement method by measuring situation of pressure bounce back to calculate the temperature at sublimation interface. The technical scheme includes the mathematic model, data retrogressive method and design of freeze-dry system. The invention provides quick measuring and correct temperature for moving sublimation interface, and without need of positioning and calibrating procedure carried out by persons.

Description

technical field [0001] The invention relates to a non-contact temperature measurement method for measuring the temperature of a moving sublimation interface during the sublimation drying process in the freeze drying process, in particular to a pressure temperature measurement method during the freeze drying process. Background technique [0002] Freeze-drying technology is a new intersecting frontier discipline developed in recent decades, involving heat and mass transfer, refrigeration technology, vacuum science and technology, automatic control, biochemistry, pharmacy and other disciplines. The freeze-drying process is a complex heat and mass transfer process, a problem related to the physical parameters of the item itself and the process parameters in the freeze-drying process, and a processing process with high added value. Temperature measurement plays an extremely important role in the optimization and control of the freeze-drying process. For example, in the sublimati...

AI Technical Summary

Problems solved by technology

First, the contact temperature measurement method can only accurately reflect the temperature condition of the local location where the temperature measuring element is located. If the temperature measuring element cannot enter the inside of the freeze-dried item, it is impossible to measure the temperature inside the freeze-dried item. But when the temperature measuring element enters the inside of the freeze-dried item, the structure of the freeze-dried item near the temperature measuring element is destroyed, that is to say, the local structure of the temperature measuring element is different from the overall structure of the freeze-dried item, so the temperature measuring element The temperature conditions reflected cannot represent the overall temperature conditions of the freeze-dried items or the temperature conditions of other locations; The qualitative methods are quite different, and the frozen layer and the desiccated layer are both established as equations. The sublimation interface temperature is the most important boundary condition for solving the two equations. Accurate measurement of the sublimation interface temperature will greatly reduce the calculation equation and simulation. The calculation program can improve the accuracy of the calculation, but the sublimation interface is mobile, and the position of the contact temperature measuring element is fixed, so it is impossible to measure the temperature of the sublimation interface in real time; third, limited temperature measuring elements can only be placed in a few limited Among the samples, in mass production, a batch of samples often consists of tens of millions of samples, and it is difficult for a few limited samples to reflect the temperature conditions of the entire batch of samples; fourth, in the process of drug production Among them, the production process requires aseptic operation, and the production process tends to be continuous and automatic. The loading and unloading work of the freeze dryer is completed by the automatic canning production line. The manual operation process should be reduced as much as possible, and the placement of the temperature measuring element is a must. In the manual operation process, obviously, the contact temperature measurement method also brings a lot of inconvenience to the automatic continuous production

Therefore, the traditional contact temperature measurement method not only cannot measure the temperature of the moving sublimation interface, but also brings a lot of inconvenience to the research and production control of the freeze-drying process

The idea of ​​pressure temperature measurement has long been mentioned, but due to factors such as high requirements for equipment, complex data analysis and processing, and difficulty in realizing automatic control, no one has studied it in depth, and there is no literature that can be found so far. Be able to detail the specific plan for the implementation of pressure and temperature measurement technology

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