Pre cooking machine (also known as pre cooking equipment or preheating machine) is a device used in industries such as food processing, chemical, pharmaceutical, etc. It is mainly used to preheat or cook materials for a short period of time, preparing for subsequent processes such as sterilization, drying, peeling, etc. Its working principle is mainly based on heat conduction, heat convection, or heat radiation, and the specific design varies depending on the application scenario. The following is a detailed explanation of its core principles and common types:
1. Core principles
Heat transfer method:
Direct heating: Steam or hot water comes into direct contact with the material (such as hot water pre cooking, steam spraying).
Indirect heating: Heat is transferred to the material through a heat exchanger (such as a jacket or coil) to avoid direct contact.
Temperature control: Maintain a constant water or steam temperature through a temperature control system (such as a PID controller) to ensure uniform heating of the material.
Time control: The residence time of materials in the pre cooking machine is adjusted by the conveying speed (such as conveyor belt) or timing device to avoid excessive heating.
2. Common types and working principles
(1) Hot water pre boiling machine
Structure: Tank body (stainless steel material), heating tube (electric/steam), conveyor belt (mesh belt or chain plate), circulating pump.
workflow
The heating tube heats the water in the sink to the set temperature (usually 60-100 ℃).
The material is slowly immersed in hot water through a conveyor belt, and the residence time is controlled by the conveying speed.
Hot water flows through a circulation pump to ensure uniform temperature.
Application: Blanching vegetables (such as carrots and peas), thawing meat.
(2) Steam pre boiling machine
Structure: Closed tunnel, steam jet pipe, conveyor belt, exhaust system.
workflow
Steam is directly sprayed onto the surface of the material or indirectly heated through a jacket.
High temperature steam (100-120 ℃) quickly heats the surface of the material, making it suitable for heat sensitive materials.
Application: Pre treatment of dairy products before preheating and canning sterilization.
(3) Spiral pre cooking machine
Structure: Spiral propeller, heating jacket, temperature control system.
workflow
The material is pushed by spiral blades and slowly advances inside the heated cylinder.
Steam or hot water is introduced into the cylinder jacket to indirectly heat the material.
Advantages: Suitable for paste like or small granular materials (such as sauces, grains).
(4) Microwave pre cooking machine
Principle: Using microwaves to penetrate materials, causing internal molecules to vibrate and generate heat.
Features: Fast heating speed, but high equipment cost, suitable for high value-added products.