How to configure the air compressor of the fermentation tank?

The air compressor of the fermentation tank should comprehensively consider the fermentation process requirements, air compressor performance parameters, system matching and safety and environmental protection requirements. The following are the specific configuration points:

1. identify fermentation process requirements

1. gas consumption calculation
   • the total air consumption is calculated based on the volume of the fermenter, the stirring power, the aeration rate (e. g. 0.5-2 VVM, I .e. the volume of air introduced per liter of fermentation broth per minute) and the dissolved oxygen demand.
   • For example: 1000L fermenter, ventilation rate 1 VVM, then the hourly gas demand = 1000L × 60min × 1=60,000L/h (I .e. 60m & sup3;/h).
   • Consider the total gas consumption when multiple tanks are connected in parallel, and reserve 10%-20% margin to cope with peak demand.
2. Pressure requirements
   • fermenters typically require a compressed air pressure of 0.2-0.4MPa to overcome pipeline resistance and meet dissolved oxygen demand.
   • If the height of the fermentation tank is high or the pipeline is long, the exhaust pressure of the air compressor should be appropriately increased (such as 0.5-0.7MPa).
3. Air Quality Standards
   • the fermentation process is sensitive to microbial contamination, and compressed air needs to be sterile, oil-free, dust-free standard.
   • Precision filter (such as 0.01μm sterilization filter) and dryer (such as freezing type or adsorption type dryer) shall be configured to ensure dew point ≤-40 ℃ and oil content ≤ 0.01 mg/m & sup3;.

2. selection of air compressor type

1. oil-free screw air compressor
   • advantage compact structure, stable operation, low maintenance cost, and can provide oil-free compressed air, suitable for most fermentation processes.
   • Applicable Scenarios: Medium and large fermentation tanks (≥ 1000L) or continuous production processes.
   • Attention post-treatment equipment (e. g. filters, dryers) is required to further purify the air.
2. Oil-free centrifugal air compressor
   • advantage: High energy efficiency, large exhaust volume, stable operation, suitable for large-scale fermentation production (such as pharmaceuticals, biofuels).
   • Applicable Scenarios: Very large fermenters (≥ 10,000L) or high purity gas requirements.
   • Attention: The initial investment is high and requires a professional maintenance team.
3. Diaphragm air compressor
   • advantage: It can provide absolutely oil-free and pollution-free compressed air, suitable for high value-added products (such as vaccines, antibiotics).
   • Applicable Scenarios: Small fermenters (≤ 500L) or laboratory scale.
   • Attention: The displacement is small, and multiple parallel connections are required to meet the demand for large flow.

3. key parameter matching

1. matching of displacement and pressure
   • the rated exhaust volume of the air compressor shall be slightly greater than the total air consumption of the fermentation tank (considering the margin), and the exhaust pressure shall meet the maximum working pressure requirements of the fermentation tank.
   • If multiple air compressors are connected in parallel, it is necessary to ensure that the displacement of each unit can independently meet the partial load demand.
2. Energy efficiency grade
   • choose a level of energy-efficient air compressor to reduce long-term operating costs.
   • Variable frequency speed regulation technology can further save energy, especially suitable for the scene of large fluctuations in gas consumption.
3. Noise control
   • the fermentation workshop shall maintain a low noise environment (≤ 85dB), and select a low noise air compressor or install a silencer.

4. System Configuration and Optimization

1. gas tank configuration
   • install the air storage tank at the outlet of the air compressor to buffer the fluctuation of air pressure and stabilize the air supply pressure.
   • The volume of the air storage tank is recommended to be 10%-20% of the air compressor exhaust volume, and it needs to be drained regularly to prevent corrosion.
2. Pipeline Design
   • use stainless steel or sanitary piping to reduce the risk of microbial growth.
   • The pipeline layout shall avoid dead corners, reduce pressure loss, and set up a drain valve for regular cleaning.
3. Post-processing equipment
   • precision filter: Step-by-step filtration (such as pre-filter, precision filter, sterilization filter) to ensure air quality.
   • Dryer: According to the dew point requirements, choose freezing or adsorption dryer to prevent moisture from affecting the fermentation process.
   • Automatic drainer: remove the condensed water in time to avoid secondary pollution.

5. safety and environmental protection requirements

1. explosion-proof design
   • if combustible gas (e. g. biogas) may be produced in the fermentation tank, the air compressor shall comply with explosion-proof standards (e. g. ExdI mark).
2. energy saving and emission reduction
   • configuration of waste heat recovery system, the use of air compressor waste heat heating fermentation tank or production water.
   • Regularly maintain the air compressor to ensure its operation in an efficient range and reduce energy waste.
3. Compliance
   • compressed air quality must comply with GMP (Good Manufacturing Practice) or relevant industry standards (e. g. ISO 8573-1).