Views: 39 Author: XICHENG EP LTD Publish Time: 2025-06-09 Origin: XICHENG EP LTD
SO₂ (sulfur dioxide) is a major air pollutant emitted from industries like power plants, metallurgy, chemical production, and cement manufacturing. An SO₂ exhaust gas treatment tower (wet scrubber) is the most common solution for efficient removal. Below is a detailed breakdown of its design, working principle, and applications.

| Technology | Mechanism | Efficiency | Pros | Cons |
|---|---|---|---|---|
| Wet Scrubber | Uses alkaline solution (NaOH, Ca(OH)₂) to absorb SO₂ → Forms sulfite/sulfate | 90-99% | High efficiency, cost-effective | Produces wastewater/sludge |
| Dry Scrubber | Injects dry sorbent (CaO, NaHCO₃) to react with SO₂ → Dry powder byproduct | 70-90% | No wastewater, simple operation | Higher chemical consumption |
| Adsorption | Uses activated carbon/zeolite to capture SO₂ → Regeneration required | 60-80% | Good for low-concentration SO₂ | High maintenance cost |
| Biological Method | Microorganisms oxidize SO₂ into sulfate | 50-70% | Eco-friendly, low energy use | Slow, requires large space |
| Component | Material | Function |
|---|---|---|
| Tower Body | PP, FRP, or 316L Stainless | Resists corrosion from acidic SO₂ and alkaline solutions |
| Spray Nozzles | Ceramic/SiC | Evenly distributes scrubbing liquid (NaOH/Ca(OH)₂) |
| Packing Material | PP/PVC Raschig Rings | Increases gas-liquid contact area for better absorption |
| Demister | PP/Stainless Steel | Removes liquid droplets from cleaned gas before emission |
| Circulation Tank | PP/FRP with Lining | Stores and recycles scrubbing solution |
SO2+2NaOH→Na2SO3+H2O(Sodium sulfite)SO2+2NaOH→Na2SO3+H2O(Sodium sulfite)Na2SO3+½O2→Na2SO4(Sodium sulfate, less harmful)Na2SO3+½O2→Na2SO4(Sodium sulfate, less harmful)
Alternative: Using limestone slurry (Ca(OH)₂) → Forms CaSO₃ (gypsum sludge).
| Parameter | Optimal Value | Notes |
|---|---|---|
| Liquid-to-Gas Ratio | 3-10 L/m³ | Higher ratio improves absorption but increases wastewater |
| pH of Scrubbing Liquid | 8-11 (Alkaline) | Maintained with NaOH/Ca(OH)₂ dosing |
| Residence Time | 2-5 seconds | Longer contact time = higher SO₂ removal |
| Pressure Drop | 500-2000 Pa | Depends on packing density and gas flow |

Method: Wet limestone scrubbing (produces gypsum for construction).
Efficiency: >95% SO₂ removal.
Method: NaOH wet scrubber (compact, high-efficiency).
Challenge: High SO₂ concentration (requires multi-stage scrubbing).
Method: Semi-dry spray absorption (Ca(OH)₂ + bag filter).
Advantage: No wastewater, but lower efficiency (~85%).
✅ Daily Checks
Monitor pH of scrubbing liquid (automated dosing preferred).
Inspect nozzles & packing material for clogging.
✅ Monthly Maintenance
Clean demister pads to prevent pressure buildup.
Check pump & piping for corrosion/leaks.
✅ Waste Management
Wet scrubbers: Treat wastewater (neutralize pH, remove solids).
Dry scrubbers: Dispose of or recycle spent sorbent.
Zero Liquid Discharge (ZLD): Recycling wastewater into reusable water.
AI-Based Control: Real-time adjustment of chemical dosing for optimal SO₂ removal.
Hybrid Systems: Combining wet + dry scrubbing for higher efficiency.
For high-efficiency SO₂ removal, wet scrubbers (NaOH/Ca(OH)₂) are the best choice in most industrial applications. Dry scrubbers are suitable where water usage is restricted. Always consider corrosion-resistant materials (PP/FRP/316L) and local environmental regulations when selecting a system.
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