Freeze Drying Technology and Equipment Introduction

The freeze-drying technique was applied as early as the beginning of the last century, and developed countries in Europe and America used it for food processing for several decades. The principle stems from the sublimation phenomenon of water. Using this phenomenon, the water-containing material can be frozen first and then placed in vacuum to sublimate the ice to achieve the purpose of drying.

Since this drying process is carried out in a frozen state and in an oxygen-deficient atmosphere, there will be no shrinkage, crusting, and component loss and deterioration due to migration of liquid water to the epidermis. Some heat-sensitive and easily oxidized brown Changes will not change. In this way, drying many products such as foods, medicines, and biological products can preserve their original characteristics and components, and can be stored at room temperature for a long period of time. The freeze-drying equipment is mainly composed of two parts: a vacuum drying chamber and a water trap. It is also equipped with a vacuum system, a refrigeration system, a heating system, a defrosting system, a cooling system, and a control system. The pharmaceutical equipment is also equipped with a hydraulic plugging system and Bacteria system, larger food equipment is equipped with quick-freezing warehouse and material conveying system.

According to different purposes, freeze-dried equipment can be divided into two types of pharmaceutical equipment and food equipment. The former is smaller in scale, strict in sterility control, precise in control of process parameters, higher in automation, and higher in cost. The latter has a larger amount of processing, higher efficiency, and more emphasis on the application of energy-saving technologies.

Since freeze-drying equipment is a kind of drying equipment with high energy consumption, it is necessary to consider reducing energy consumption and processing cost for dry foods. Therefore, the application of energy-saving technologies and measures should be considered when designing and manufacturing and choosing to use. First of all, in the manufacture should ensure that the vacuum chamber sealed well, the vacuum can quickly meet the requirements, and can be replaced by a low-power vacuum pump, and can be automatically alternated to achieve the purpose of energy conservation.

The energy consumption of the refrigeration system is relatively large. High-efficiency heat exchange equipment should be used to work and the insulation is reliable. At the same time, more advanced low-temperature refrigeration technologies and equipment should be used to increase the temperature difference between the material ice interface and the frost-removing surface to increase the catching speed and shorten the drying time.

The heating system should ensure that each tray is heated as evenly as possible, and the drying schedule is synchronized to reduce the invalid drying time. The control system should be able to play a role of comprehensive adjustment, monitoring and automatic control. After more than ten years of development, domestic food freeze-drying equipment has been relatively well-established and has basically reached the level of imported equipment. The DT series lyophilizer produced by Fushun is a more successful example of energy conservation. As technology advances, from the perspective of foreign countries, food lyophilizers are becoming larger, more continuous, and more automated.