What Is the Complete Compressed Air Purification Process for Liquid Spawn Fermentation Tanks?

What Is the Complete Compressed Air Purification Process for Liquid Spawn Fermentation Tanks?

System Sequence:
Oil-free air compressor → Air receiver tank → Pre-cooler → Refrigerated dryer → Three-stage precision filters → Adsorption-type deep dryer → Terminal sterilization filter → Fermentation tank air inlet

Step-by-Step Breakdown:
1. Air Source
Selection of oil-free screw air compressor (Key point: Oil injection is strictly prohibited for edible fungus fermentation).
Prefer water-lubricated oil-free screw compressors or magnetic levitation oil-free compressors.
Advantages: No lubricating oil mixes into the compression process, eliminating the risk of oil contamination at the source.
Auxiliary equipment: Equip the compressor with a waste heat recovery unit to preheat the culture medium, reducing workshop energy consumption—ideal for large-scale spawn production facilities.

2. Primary Buffering
Air receiver tank + primary heat dissipation and water removal.
Function of the receiver tank: Stabilizes air pressure and allows for the initial settling of large amounts of liquid water and large particulate impurities. Operational standard: The automatic drain valve at the tank bottom must discharge condensate at scheduled times daily; use an electronic timer drain to prevent water accumulation caused by human oversight.

3. Secondary Drying
Refrigerated dryer: Removes the majority of water vapor by cooling compressed air to 3°C, condensing out over 85% of liquid water, and reducing the load on downstream filtration. Note for spawn facilities: A refrigerated dryer alone usually cannot meet fermentation dew-point requirements; it must be paired with an adsorption dryer for deep dehydration.

4. Three-Stage Gradient Precision Filtration (Sequential impurity interception)
1. Q (or C) Grade Coarse Filter: Intercepts rust, dust, and large liquid droplets.
2. P (or T) Grade Medium Filter: Intercepts aerosols and fine water mist.
3. S (or A) Grade Ultra-fine Filter: Removes trace oil mist; residual oil content in outlet air <0.001 mg/m³.

Reminder:

Replace filter elements every 3,000 hours or immediately if the pressure differential exceeds 0.08 MPa to prevent secondary contamination caused by element damage.

5. Deep Drying
After treatment by an adsorption dryer (a critical component for ensuring sterility), the compressed air achieves an atmospheric dew point of ≤-40°C, ensuring the entire piping system remains free of condensate. A heated-regeneration model is selected for lower energy consumption, making it suitable for supplying air to edible mushroom fermentation workshops that operate continuously 24 hours a day.

6. Critical Point of Use
A sterilization filter specifically designed for fermentation tanks is installed immediately upstream of the tank's air inlet. It features dual PTFE sterilization filter elements with a 0.01 μm pore size, ensuring the complete retention of bacteria and fungal spores. Operational protocols dictate that the sterilization filter and associated piping undergo steam sterilization at 121°C prior to each fermentation batch. Requirements for fermentation air specify that the sterilization filter must include a bypass sterilization line to facilitate in-line disinfection without the need for disassembly.

In summary, a well-designed compressed air purification system typically follows a four-stage filtration approach: primary filtration, precision filtration, high-efficiency oil removal, and activated carbon odor removal.