Freeze-drying machine plate layer temperature control method and system

Abstract

The invention discloses a freeze-drying machine plate layer temperature control method and system. In a pre-freezing mode, a refrigerating compressor is controlled to work so that a plate layer can becooled, in the sublimation mode, a heater is controlled to work so that the temperature of the plate layer can be increased, in the pre-freezing mode and the sublimation mode, whether the refrigerating compressor needs to work or not and whether the heater needs to work or not are judged by comparing the sum of the plate layer outlet detection temperature T2 and the system temperature rise deltaT and the set reference temperature value, and the plate layer inlet detection temperature T1 is adjusted to be infinitely close to the set reference temperature value. A freeze-drying machine plate layer temperature control system comprises a plate layer heat exchange loop communicating with a freeze-drying machine plate layer, a circulation pump, the heater and a heat exchanger which are sequentially connected in series are arranged on the plate layer heat exchange loop to be connected with the refrigerating compressor, a first temperature detection part is located at the inlet position of the freeze-drying machine plate layer, and a second temperature detection part is located at the output position of the freeze-drying machine plate layer. The system is simple, high in efficiency, stable, reliable and high in control precision.

Description

technical field [0001] The invention relates to the fields of food and medicine production, in particular to a method and system for controlling the temperature of a freeze dryer plate. Background technique [0002] The physical essence of the freeze-drying process is the heat and mass transfer process at low temperature and low pressure. Temperature control is a crucial link, and the accuracy of temperature control directly affects the quality of the product. The temperature control system of the freeze dryer is generally composed of a compressor, a heat exchanger, a heater, a circulation pump and a heat exchange medium (silicone oil). Due to the use of silicone oil medium for cold and heat exchange, it has obvious hysteresis. The temperature control process in the prior art is as follows: when the detection value of the plate inlet temperature is greater than the set value, the compressor system is started, and the refrigerant is sent to the heat exchanger to exchange col...

AI Technical Summary

Problems solved by technology

This traditional PID control method realizes the control of the same target due to two independent control channels, but the temperature change in the freeze-dried plate layer is uncontrollable and has hysteresis, and it must be maintained after the heat exchange in the freeze-dried plate layer is realized. The stability of the detection value of the plate inlet temperature is likely to cause system oscillation, that is, the heating of the heater and the cooling of the compressor are carried out alternately, resulting in poor temperature control accuracy of the system, and even destroying the composition and appearance of the medicine; in addition, the compressor Frequent switching from cold trap cooling to plate layer temperature control may also easily cause a lack of cooling capacity in the freeze dryer cold trap, affecting the entire freeze-drying process

Images