Sodium bicarbonate plays a significant role in the desulfurization (removal of sulfur oxides, SOₓ) and denitrification (removal of nitrogen oxides, NOₓ) processes in industrial flue gas treatment. The dry adsorption method, which utilizes sodium bicarbonate as an adsorbent, has emerged as an efficient and economical technology for flue gas purification.
When sodium bicarbonate is injected into a high-temperature flue gas stream, it thermally decomposes into sodium carbonate (Na₂CO₃), water, and carbon dioxide:
2NaHCO3→Na2CO3+H2O+CO2
Sodium carbonate then reacts with acidic pollutants like sulfur dioxide (SO₂) and nitrogen oxides (NOₓ) to form neutral salts (e.g., sodium sulfite or sodium sulfate):
Na2CO3+SO2→Na2SO3+CO2
Advantages of the Dry Adsorption Process:
High Efficiency: Achieves comparable results to traditional methods, such as the wet spray absorption using lime milk.
Broad Application: Effective in various industries, including:
Coal-fired power plants
Waste or alternative fuel incinerators
Industrial furnaces in glass, cement, and metallurgy
Economic Operation: Reduces water consumption and maintenance costs compared to wet systems.
Environmentally Friendly: Helps meet stringent flue gas emission standards while producing minimal secondary waste.
Comparison with Lime Milk Spray Adsorption:
Dry Process (Sodium Bicarbonate):
Requires no liquid-phase handling.
Easier to install and maintain in existing facilities.
Wet Process (Lime Milk):
Generates liquid effluents requiring treatment.
May be more suited for extremely high pollutant concentrations but at a higher operational cost.
Sodium bicarbonate-based dry adsorption is gaining popularity due to its cost-effectiveness, simplicity, and adaptability to diverse industrial applications.
