Sterilization pot (Also known as a sterilization retort or sterilizer) is a core piece of equipment used in the food, pharmaceutical, and related industries for commercial aseptic processing. It employs high temperature and high pressure to disrupt microbial cell structures, thereby extending product shelf life. The following are its key features:

I. Core Operating Principle

1. Confined pressurized environment : Heating with steam or hot water raises the pressure inside the vessel, increasing the boiling point of water to above 121°C (e.g., at a pressure of 0.1 MPa, the boiling point reaches 121°C), thereby creating conditions for high-temperature sterilization.

2. Hot medium circulation ：

• Water bath type : The food is fully immersed in hot water, with circulation enhanced by a pump to ensure uniform heat distribution, making it suitable for rigid packaging such as glass bottles and tin cans.

• Steam-type : Direct steam heating is employed, but cold spots may form within the vessel, resulting in poor uniformity of heat distribution.

• Spray-type : Hot water in a mist form is sprayed onto the food surface via nozzles or spray pipes, ensuring uniform temperature with no dead zones and rapid heating and cooling. This method is particularly well-suited for flexible packaging, such as vacuum bags and aluminum foil pouches.

• Steam/Air Mixed Type : Combining steam heating with air pressurization and using a high-speed blower to ensure uniform mixing, this system is suitable for specialized process requirements.

II. Equipment Type and Structure

1. According to the tank structure ：

• Single-tank sterilization pot : Basic model, suitable for small-scale production.

• Double-layer sterilization pot The upper tank is a hot-water tank, and the lower tank is a processing tank. Hot water is recirculated to conserve energy, making this system ideal for enterprises with a daily output exceeding 10 tons.

• Twin-pot parallel type : Two pots operate alternately, shortening the sterilization time and improving efficiency.

• Vertical sterilization pot : Vertical structure, space-saving, suitable for specific site requirements.

• Electric–Steam Dual-Use Sterilization Pot : No boiler is required; steam is generated via electric heating, making it suitable for small-scale applications or settings without a steam source.

• Rotary sterilization pot During the sterilization process, the food rotates slowly to ensure uniform heat transfer and prevent stratification of high-viscosity products (such as bagged porridge or eight-treasure porridge).

2. By control method ：

• Manual control type All operations—water addition, heating, holding at temperature, and cooling—are performed manually, resulting in poor temperature control accuracy, difficulty in achieving consistent food appearance, and a high bag‑breakage rate.

• Electrical semi-automatic control type Pressure is controlled by an electrical contact pressure gauge, while temperature is regulated by a sensor and a temperature controller (with an accuracy of ±1°C). Cooling requires manual operation.

• Computer semi-automatic control type : The system employs a PLC and a text display for signal processing, can store sterilization programs, achieves temperature control accuracy of ±0.3°C, and still requires manual intervention during the cooling phase.

• Computerized fully automatic control type : The entire process is controlled by a PLC and a touch screen, capable of storing multi-stage heating, holding, and cooling programs, with temperature control accuracy of ±0.1℃. It features simple operation and is well-suited for large-scale production.

III. Key Technical Parameters

1. Temperature and Pressure : The design temperature is typically 143°C, with a working pressure of 0.15 MPa and a design pressure of 0.3 MPa, ensuring safety under high-temperature and high-pressure conditions.

2. Material The vessel body and all components in contact with the material are made of high-quality stainless steel (such as 304 or 316L), offering excellent corrosion resistance and meeting food-grade hygiene standards.

3. Safety device Equipped with a pressure gauge, a safety valve, and safety interlock devices (such as door interlocks, pressure interlocks, and temperature interlocks) to prevent the lid from being opened under overpressure or when pressure has not been fully relieved, thereby ensuring the safety of both the equipment and operators.

IV. Key Points for Operation and Maintenance

1. Operating Procedures ：

• Before sterilization, the air inside the vessel must be removed to prevent cold spots from compromising the sterilization efficacy.

• During the heating-up phase, a holding section can be configured to ensure uniform and consistent temperature throughout the vessel.

• After sterilization, the temperature must be reduced slowly to prevent product breakage caused by thermal expansion and contraction.

2. Daily maintenance ：

• Regularly replace the water in the tank and clean the filter to prevent impurities from clogging the pipes.

• Inspect the sealing ring for signs of aging or damage, and replace it promptly to ensure a proper seal.

• Regularly calibrate pressure gauges and safety valves to ensure the safe operation of equipment.