When selecting a demister Pad (mist eliminator pad), the right choice depends on operating conditions, the type of mist to be removed, and the process design requirements. Here are the main points to consider:
1. Operating Environment
- Gas type & properties: corrosiveness, temperature, and pressure.
- Liquid type: whether it’s water, oil, chemicals, acids, or alkalis.
- Corrosion resistance: stainless steel (304, 316L) is common; PP, PTFE, or other plastics for strong acids/alkalis.
2. Droplet Characteristics
- Droplet size:
- Standard knitted wire mesh pads effectively remove droplets ≥ 3–5 μm.
- For very fine droplets (< 3 μm), fiber bed or vane-type demisters may be needed.
- Loading rate: gas velocity and droplet density determine pad thickness and density.
3. Design Parameters
- Gas velocity (capacity factor, K-value): must balance high efficiency with low pressure drop.
- Pressure drop: usually 1–10 mbar; higher pressure drop can cause flooding or energy loss.
- Pad thickness: standard is 100 mm; can be 150 mm or 200 mm for higher efficiency.
- Pad density (kg/m³):
- Low density (80–120) → low pressure drop, coarse mist removal.
- Medium density (120–160) → balanced performance.
- High density (160–200) → high efficiency, but higher pressure drop.
4. Material Selection
- Metallic: SS304, SS316L, Monel, Hastelloy – for high temperature and corrosive gases.
- Plastic: PP, PE, PTFE – for chemical resistance and lightweight construction.
- Others: fiberglass or custom materials depending on process.
5. Installation & Maintenance
- Shape & size: round, rectangular, or custom-made to fit vessel diameter.
- Ease of removal: consider if frequent cleaning or replacement is needed.
- Support grid: must withstand gas flow and liquid load.
✅ General rule:
- For general chemical, oil & gas, and petrochemical processes → stainless steel wire mesh demister pad.
- For acid/alkali scrubbing systems → PP or PTFE demister pad.
- For high-efficiency fine mist removal → multi-layer or high-density pad, or combine with vane/fiber demisters.