Introduction of Fruit and Vegetable Juice Vacuum Concentration Equipment

Vacuum concentration equipment is the most important and widely used equipment for fruit and vegetable juice concentration. The purpose of the concentrated fruit and vegetable juice or protein drink is as follows:

• As a pretreatment of drying: For example, when producing fruit powder or milk powder, the material needs to be concentrated first, and then spray-dried to make a powdered product.
• Improve the preservation of the product: The solid content of fruit and vegetable juice concentrate is as high as 70%-80%, and the high concentration causes the sugar content and acidity to greatly increase, which can inhibit the spoilage caused by microorganisms and extend the shelf life of the product.
• Reduce the volume and quality of the product: Concentrated fruit and vegetable pulp (juice) can be concentrated to 3/1 to 6/1 of the original volume, thus facilitating international transportation and storage.
• Reduce the activity of water to increase the stability of the microorganisms and the chemistry of food.
• Extract the aromatic substances in fruit and vegetable juices: Since fruit and vegetable juices and protein beverages contain a large amount of water and a large number of nutritional components, and have strong heat sensitivity, they are often used to preserve their nutrients to the greatest extent, aromatic substances and prevent the product from discoloring the juice concentrate machine.

Heating chamber

The heating chamber is a component that transfers heat for the boiling and concentration of fruit and vegetable juice, and is commonly used as a heating tube or plate heat exchanger. The heating steam is used to indirectly heat the fruit and vegetable juice, so that the fruit and vegetable juice obtains heat to reach a boiling state, and the water in the fruit and vegetable juice is continuously vaporized, so that the concentration of the fruit and vegetable juice is continuously increased to a predetermined concentration.

Evaporation chamber

The fruit and vegetable juice in the heating chamber boils and vaporizes, so the secondary steam produced contains a large amount of liquid foam. After the fruit and vegetable juice enters the larger evaporation chamber space, separating the fruit and vegetable juice from the secondary steam through self-condensation.

Condenser

The final concentration of the vacuum concentration system is operated under a certain degree of vacuum, and the main equipment forming the vacuum is the condenser. The low-pressure steam of the negative pressure equipment is introduced into the condenser, and the steam is condensed with cold water to generate a vacuum.

Vacuum device

Vacuum pumps include dry or wet vacuum pumps, and water ring vacuum pumps, whose function is to remove the non-condensable gas in the fruit and vegetable juice and cooling water in the concentrated equipment, so that the equipment maintains a certain degree of vacuum, and at the same time improves the heat transfer coefficient of the equipment.

Single-effect juice concentrate machine: the fruit and vegetable juice is concentrated in the concentration tank, and the secondary steam generated is no longer used, and is directly condensed by the condenser and discarded. The heating steam consumption of this equipment is about 1.1- of the evaporation of water. 1.2 times, large consumption of heat energy and cooling water, low investment, large production capacity and long effective utilization time.

Multi-effect juice concentrate machine: The heat generated by the heating steam is used twice or more times, that is, the secondary steam generated in the concentration process is introduced into the secondary-effect heating chamber as the heat source. Multi-effect concentration equipment can save heat energy. The steam consumption of the two-effect evaporator is 1/2 of that of water evaporation, and the steam consumption of the three-effect evaporator is 1/3 of that of water evaporation. But in fact, the number of concentrated effects cannot be increased indefinitely, because every time an effect is added, the temperature difference cannot be less than 5-7℃. Therefore, if the number of effects is more, the temperature of the first effect chamber will be higher. The concentration of fruit and vegetable juice is not suitable.

Forced circulation evaporator: The heating chamber is outside, and the material is pumped into the main concentrator from the external steam separation chamber and heated. In the main separation chamber, the secondary steam is separated from the materials, the concentrate flows out from the outlet, the diluent continues to be added and circulated, and enters the concentration tank to continue heating and concentration. This type of concentration equipment uses centrifugal pumps to accelerate the circulation of fruit and vegetable juices to increase the heat transfer coefficient and speed up the concentration efficiency. Most of the multi-effect concentration equipment adopts forced circulation evaporation equipment.

Rising or falling film evaporator: The fruit and vegetable juice flows in a film on the inner wall of the heating tube of the natural circulating liquid film concentrating equipment for continuous heat transfer and rapid evaporation. The film flow is divided into rising film and falling film, and the heating steam can be used multiple times, it is divided into single-effect, double-effect, triple-effect and multi-effect vacuum concentration equipment. The falling film evaporator is suitable for materials that are prone to foaming, high concentration, high viscosity (0.05-0.45pa.s), and materials that are not suitable for crystallization and scaling.