What Is a Spiral Freezer?
A spiral freezer is a device that freezes objects on a conveyor arranged in a spiral shape.
Compared to a linear conveyor, the spiral freezer saves space and extends the overall length of the conveyor. This makes it possible to freeze large quantities of products, leading to cost reductions. It also reduces the number of manual processes and prevents foreign matter from mixing with the product, which is beneficial for quality control.
Uses of Spiral Freezers
Spiral freezers are mainly used in the food industry. Its main use is for freezing food and temporarily cooling chilled products.
It is used in conjunction with refrigerators to rapidly freeze food products. By freezing food, it is possible to maintain quality and taste for a long period of time. This equipment is indispensable for the production of many food products, such as frozen foods and frozen fruits.
It is also used for temporary cooling of chilled products. By chilling food before placing it in the chilled room (cold storage room), food quality is preserved.
Other uses include cooling cosmetics and bottled beverages. Gel skin care products and eye shadow may be stored in a low-temperature environment to prevent deterioration and alteration. It may also be used to cool baked goods and bread.
Principle of the Spiral Freezers
In a spiral freezer, objects are placed on a conveyor and placed in a cooling chamber. Inside the cooling chamber, a built-in refrigerant circulation tube lowers the temperature in the cooling chamber. The conveyor rotates the object as it passes through the cooling chamber, where the object is rapidly cooled.
There are different types of belts used for conveyors. The type of belt used depends on the type of object.
1. Plastic Belt
Plastic belts are made of plastic and have a modular structure like bricks. They are easy to remove and clean, and lighter and more portable than metal belts. They are used in the production of frozen vegetables such as spinach.
2. Mesh Belt
Mesh belts are metal mesh belts, often made of stainless steel, that can be used in a wide range of temperatures from 0°C or lower to 200°C or higher. It is used for freezing food products manufactured at very high temperatures, such as fish paste products.
The fine mesh can also be used for small items such as rice grains. Because it can be handled at high temperatures, steam sterilization and disinfection can be performed to keep the conveyor hygienic. The spiral freezer uses a mesh belt.
Types of Spiral Freezers
There are several types of spiral freezers, depending on the refrigerant used.
1. Liquid Refrigerant Type
This type of spiral freezer cools an object by circulating liquid refrigerant. The cooling speed is fast and the object can be cooled rapidly. The feature of this type of freezer is that the refrigerant can be reused because the liquid refrigerant is vaporized or liquefied by electric power.
However, liquid refrigerants sometimes contain environmentally harmful substances such as chlorofluorocarbons (CFC) gas, which poses environmental and other challenges. In recent years, environmentally friendly refrigerants are increasingly being used.
2. Liquid Nitrogen Type
This type of spiral freezer uses liquid nitrogen to rapidly cool food. Liquid nitrogen is extremely low in temperature and boils at -196°C, providing an extremely high cooling effect. The feature of this type of freezer is that it does not adversely affect the environment because liquid nitrogen rapidly evaporates to become nitrogen.
The cooling process of the liquid nitrogen spiral freezer is accomplished by spraying liquid nitrogen onto the food through a spray or nozzle. The liquid nitrogen adheres to the surface of the food and rapidly evaporates, lowering the temperature of the food. By repeating this process, it is possible to rapidly send cold air into the interior of the food.
However, liquid nitrogen spiral freezers have several drawbacks. First, handling liquid nitrogen requires specialized knowledge, and installation and operation require advanced skills. In addition, since a large amount of expensive liquid nitrogen is required for operation, running costs tend to be high.