Stainless steel fermentation tankThe principle mainly revolves around three core elements: mechanical stirring, ventilation and oxygen supply, and environmental control. Through the synergistic effect of physical and chemical means, it provides suitable growth and metabolic environment for microorganisms, thereby achieving efficient synthesis of target products. The following is a detailed explanation of the specific principles and points:
1、 Principles of Mechanical Stirring and Gas Liquid Mixing
Mixing blade function:
The fermentation tank is equipped with a top in mechanical stirring system, which disperses the air into tiny bubbles through the rotation of the stirring blade, making them evenly distributed in the fermentation broth. The design of agitator blades (such as straight impellers and inclined impellers) can produce different flow field characteristics. For example, straight impellers are suitable for high viscosity systems, while inclined impellers can enhance axial mixing effects.
Bubble crushing and oxygen transfer:
The rotation of the stirring blade generates centrifugal force, causing bubbles to form a strong mixed flow around the impeller. Bubbles are crushed into smaller sizes, significantly increasing the gas-liquid contact area, thereby improving the dissolution rate and mass transfer efficiency of oxygen. For example, in beer fermentation, yeast requires sufficient oxygen for respiration, and the stirring blade crushes bubbles to ensure that the dissolved oxygen level meets the demand.
Circulating flow formation:
The air lift fermentation tank sprays high-speed bubbles through air nozzles, forming a circulation by utilizing the density difference between the liquid on the ventilated side and the non ventilated side. This internal circulation method does not require mechanical stirring and can achieve sufficient mixing of liquid and gas, making it suitable for the cultivation of microorganisms sensitive to shear forces.
2、 Principles of Ventilation, Oxygen Supply, and Aseptic Control
Aseptic air supply:
Aerobic fermentation (such as antibiotic production) requires continuous introduction of a large amount of sterile air. Air enters the fermentation tank through a deep ventilation system, and the flow rate is displayed by a glass rotor flowmeter, while the pressure is monitored by a pressure gauge. The system is equipped with a high-efficiency sterilization filter with a stainless steel casing (filtration accuracy of 0.01 μ m) to ensure sterile air and prevent contamination by miscellaneous bacteria.
Optimization of oxygen transfer efficiency:
The coordinated control of ventilation rate and stirring speed is crucial. For example, by adjusting the ventilation rate (maximum 1.5VVM) and stirring speed (50-600rpm), the oxygen transfer coefficient (KLa) can be optimized to maintain the dissolved oxygen level (DO) within the target range (such as 0-100% or 0-200%). Some fermentation tanks are also equipped with mass flow controllers to achieve automatic adjustment of air flow.
Pressure control and safety:
The pressure inside the tank is jointly formed by the introduction of gas and the production of gas during fermentation. By adjusting the opening of the exhaust valve to control the tank pressure, a pointer pressure gauge is installed at the top exhaust port to display the pressure value. Optional imported pressure transmitters and automatic regulating valves are available to achieve precise control of tank pressure (such as 0.05MPa), ensuring the safety of the fermentation process.
3、 Principles of Environmental Control and Microbial Metabolism Regulation
Temperature control:
The fermentation tank is equipped with a jacket or coil heat exchange device, which adjusts the temperature of the fermentation broth by introducing cold or hot water. The temperature sensor monitors the temperature in real-time and feeds back the signal to the control system. When the temperature deviates from the set value (such as 40-45 ℃ for lactic acid bacteria fermentation), the system automatically adjusts the flow rate of the heat exchange medium to keep the temperature within the set range.
PH adjustment:
Microbial metabolic activity can cause changes in the pH value of fermentation broth. The fermentation tank is equipped with a pH sensor and an acid-base addition device to monitor and adjust the pH value in real time. For example, different stages of antibiotic fermentation require different pH values. When the pH deviates from the set range, the control system automatically starts the acid-base pump, adds an appropriate amount of acid or alkali, and restores the pH to the set value.
Dissolved oxygen (DO) control:
The level of dissolved oxygen directly affects microbial metabolism. The fermentation tank detects the dissolved oxygen value online through a DO electrode and controls it in conjunction with the speed and ventilation rate. For example, when the DO value is below the set threshold, the system automatically increases the stirring speed or ventilation volume to ensure the supply of dissolved oxygen.
Material replenishment control:
Nutrients need to be supplemented during the fermentation process to maintain microbial growth. The fermentation tank is equipped with multiple peristaltic pumps to achieve time proportional flow and feeding. The replenishment amount can be displayed and recorded cumulatively to ensure accurate supply of nutrients.
4Stainless steel fermentation tankPrinciples of Typical Application Scenarios
Aerobic fermentation:
The production of antibiotics and amino acids requires mechanical stirring and ventilation to meet the oxygen demand of microorganisms. The air lift fermentation tank utilizes bubble circulation to achieve efficient oxygen transfer and is suitable for large-scale production.
Anaerobic fermentation:
For the production of alcohol and solvents, the fermentation tank structure is relatively simple and does not require a complex ventilation system. Prevent oxygen from entering through a sealed design to ensure an anaerobic environment.
High temperature aerobic fermentation:
For the treatment of livestock and poultry manure, high-temperature microbial technology is used to promote the decomposition of organic matter through mechanical stirring and ventilation for oxygen supply. The fermentation tank is equipped with deodorization equipment to treat exhaust gas and meet emission standards.