Vacuum Drying Equipment Application

Vacuum drying has a series of advantages, such as low drying temperature, relative lack of oxygen in drying chamber, avoiding fat oxidation and pigment browning. It is suitable for drying heat-sensitive food materials. In addition, the cost of equipment and drying costs are relatively low. Vacuum drying plays an important role in food drying.

The saturated vapor pressure of water is closely related to temperature. Under vacuum condition, the boiling point of water decreases, that is to say, the operation under vacuum is also operated at low temperature, which can avoid the destruction of nutrients and vitamins at high temperature, and improve the drying speed. In addition, in the vacuum system, the air content per unit volume is lower than that in the atmosphere. In this relatively hypoxic environment, food drying can reduce or even avoid the chance of oxidation of fat, browning of pigments or other oxidative deterioration in food, so vacuum drying can obtain better food quality.

Vacuum drying is widely used in food, pharmaceutical, chemical and other industries. Various vacuum drying equipments have been developed and introduced in China, and their structures are various. In the food industry, the main forms are box type, double cone type vacuum dryer, belt type vacuum dryer and so on. These traditional vacuum drying devices mainly use hot air, steam or electric heating, heat transfer from the outside to the inside of the material using the principles of heat conduction, convection or radiation.

Combining vacuum drying with microwave heating or other drying methods, many new vacuum drying devices have emerged, which promotes the development of vacuum drying. Vacuum microwave drying, which absorbs the advantages of microwave heating and vacuum drying, is a promising drying technology. China Food Machinery Equipment Network recommends that China speed up the development of vacuum microwave drying equipment.

Vacuum-Freeze-Dryer-for-Sale

Vacuum-Freeze-Dryer-Manufacturer-in-China

Industrial-Vacuum-Freeze-Dryer-Price

Food-Freeze-Dryer-Machine-for-Sale

Vacuum Drying Equipment Main Pump

The selection of Roots pump in vacuum drying equipment mainly considers its pumping speed. Because VPD equipment does not require very strict pumping time to achieve working vacuum, the selection range of pumping speed of main pump is very wide. Generally, it can be obtained by dividing the total amount of leakage and exhaust gas in vacuum tank into the final working vacuum in high vacuum stage. In practice, it can generally be obtained by dividing the total amount of leakage and exhaust gas into the final working vacuum. The rated pumping speed (L/s) is about 1% of the vacuum tank volume (L).

Because the requirements of cold limit vacuum (1Pa) and final working vacuum (10Pa) of vacuum tank are not high, it is possible to use Roots pump to distribute the vacuum system of the front stage pump. However, in recent years, VPD equipment has adopted more two-stage Roots pump vacuum system, i.e. installing an intermediate Roots pump between the main stage Roots pump and the front stage pump, in order to further shorten the pumping time and improve the pumping efficiency. The working vacuum and the performance requirements of the main pump are reduced.

The pumping speed ratio of the primary and intermediate Roots pumps is in the range of (2:1) ~ (4:1). It can be handled according to the pumping law of the general vacuum system. The Roots pump used in VPD equipment is characterized by a small amount of kerosene vapor in the pumped gas and high temperature. When selecting pumps, it should be noted that the manufacturer should give special consideration to the determination of the rotor clearance of Roots pumps and the selection of sealing materials in pumps. In addition, Roots pump with bypass valve is usually selected.

China-Vacuum-Paddle-Dryer

Low-Temperature-Vacuum-Dryer-for-Food

Continuous-Belt-Vacuum-Dryer

China-Professional-Vacuum-Dryer-Manufacturer