Compressed air requirements for biological fermentation

Professional instructions on the quality requirements of the biological fermentation process for compressed air

in the biological fermentation process, compressed air is a key element of microbial metabolic activities, and its quality is directly related to fermentation efficiency and product quality. After systematically combing the technical specifications and industry practices, the core requirements and safeguard measures for compressed air are described as follows:

1. basic quality index system

1. sterility Assurance
   • A three-stage filtration system is used: pre-filter (filter particle size> 2μm particles), fine filter (filter particle size 0.01-1μm particles), and sterilization filter (filter efficiency up to 99.9999).
   • Regular filter integrity testing and challenging validation using aerosol generators ensure filtration efficiency meets HEPA standards.
2. Cleanliness control
   • refer to ISO 8573 standard, control the concentration of particles ≥ 0.1μm in compressed air <100,000/m & sup3;, oil content <0.01 mg/m & sup3;, water content corresponding to pressure dew point ≤-40 ℃.
   • The front section of the air filter in the fermentation workshop is equipped with PTFE filter medium to regularly detect the attenuation of filtration efficiency.
3. temperature and humidity management
   • the temperature of the compressed air before entering the fermentation tank needs to be 8-12 ℃ higher than the temperature of the fermentation liquid, and the precise temperature control is achieved through the plate heat exchanger.
   • The relative humidity is strictly controlled in the range of 60%-70%, the cold mirror humidity meter is used for online monitoring, and the automatic drain valve is configured to drain the condensed water in time.

2. dynamic parameter regulation mechanism

1. pressure Adaptability Design
   • the outlet pressure of the air compressor needs to cover the static head of the fermentation tank (usually 0.1-0.15MPa), the resistance loss of the pipeline (about 0.05-0.1MPa) and the pressure drop of the filter (0.02-0.05MPa), and the typical configuration pressure is 0.25-0.35MPa.
   • The pressure sensor array is configured to realize the closed-loop control of the air supply pressure, and the pressure fluctuation range is controlled within ± 0.02MPa.
2. flow dynamic matching
   • according to the change of oxygen demand in the fermentation stage, the variable frequency centrifugal air compressor is used with the buffer system of the gas storage tank to realize 0-100% stepless speed regulation.
   • Single 50m & sup3; The typical air demand of fermenter is 1.5-2.5m & sup3;/min, reserve 20% allowance for peak demand when configuring air compressor.

3. System Reliability Guarantee Measures

1. preprocessing system optimization
   • three-stage pre-filtering device is equipped: insect screen (filtering particle size> 10μm), bag filter (filtering efficiency F8) and self-cleaning filter (filtering efficiency H10) to ensure the cleanliness of air intake.
   • A temperature and humidity sensor is added to the inlet of the air compressor, and the preheating module is automatically started when the ambient humidity is> 80%.
2. Post-treatment process strengthening
   • two-stage cooling system is adopted: circulating cooling water is adopted for primary cooling (40 ℃ & rarr;26 ℃) and low-temperature chilled water is adopted for secondary cooling (26 ℃ & rarr;8 ℃) to ensure deep dehumidification of compressed air.
   • Equipped with an electric heating regenerative dryer, the heating temperature is controlled by a temperature sensor during the regeneration phase to prevent the filter medium from overheating.

4. energy efficiency optimization scheme

1. waste heat recovery and utilization
   • install the air compressor waste heat recovery device, and use the exhaust waste heat at 100-120 ℃:
     • preheat intake air (energy saving rate about 15%)
     • preparation of 60-65 ℃ process hot water (instead of steam heating)
   • configure the heat recovery efficiency monitoring module to ensure the system COP>3.5.
2. intelligent group control system
   • deployment of DCS control system, integrated pressure, flow, temperature and humidity and other more than 20 monitoring parameters, to achieve:
     • automatic sorting of air compressor start and stop
     • frequency converter dynamic speed regulation
     • fault warning and diagnosis
   • through the analysis of historical data to optimize the operation strategy, the typical energy saving effect can reach 20%-30%.

5. maintenance management specification

1. preventive maintenance system
   • implementation of three-level maintenance system:
     • daily inspection: operating parameters of air compressor, differential pressure of filter and drainage of air storage tank
     • weekly inspection: cooler heat exchange efficiency, pipeline leakage detection
     • monthly inspection: quality analysis of motor insulation and lubricating oil
   • establish equipment health records and use vibration analyzer for condition monitoring.
2. aseptic safeguard measures
   • filter sterilization: VHP space sterilization technology is adopted, the sterilization cycle is 121 ℃/30min, and the killing logarithm value of biological indicator (Bacillus stearothermophilus) is verified to be ≥ 6.
   • Disinfection of air pipeline: CIP on-line cleaning is carried out every month, peracetic acid solution is used for circulating flushing, and the concentration is monitored and controlled at 0.2-0.3 in real time.

Conclusion
the quality requirements of the biological fermentation process for compressed air are multi-dimensional and high-precision. Enterprises need to build a full-process quality control system from pre-treatment to post-treatment, through intelligent monitoring, energy efficiency optimization and preventive maintenance measures, while ensuring the stability of the fermentation process, to achieve the economic and efficient operation of the compressed air system. It is recommended to entrust a professional organization to conduct a system audit and customize the design of compressed air solutions that meet the requirements of GMP.