Ammonia Desulfurization (DeSOx)

Technology Introduction

Ammonia desulfurization is a highly efficient wet flue gas desulfurization technology that uses ammonia (NH₃) or ammonia water as an absorbent to remove sulfur dioxide (SO₂) from flue gas through a chemical reaction. Its process principle and characteristics are as follows:

Working Principle

Absorption reaction

SO₂ in flue gas reacts with ammonia or ammonia gas in the absorption tower to form ammonium sulfite ((NH₄)₂SO₃) or ammonium bisulfite (NH₄HSO₃):

SO₂+2NH₃+H₂O→(NH₄)₂SO₃
SO₂+2NH₃+H₂O→(NH₄)₂SO₃
SO₂+NH₃+H₂O→NH₄HSO₃
SO₂+NH₃+H₂O→NH₄HSO₃

Oxidation reaction

Under forced oxidation (air) conditions, sulfites are oxidized to ammonium sulfate ((NH₄)₂SO₄), which can be used as a fertilizer by-product:

(NH₄)₂SO₃+½O₂→(NH₄)₂SO₄

(NH₄)₂SO₃+½O₂→(NH₄)₂SO₄

Crystallization recovery

Ammonium sulfate solution is obtained through evaporation and concentration, crystallization, centrifugation and separation to obtain solid ammonium sulfate fertilizer.

Key process parameters

Absorption tower pH: usually controlled at 5.0~6.0 (too high increases ammonia escape, too low reduces desulfurization efficiency).

Liquid-gas ratio (L/G): about 3~5 L/m³.

Oxidation air volume: It is necessary to ensure that the ammonium sulfite is fully oxidized to ammonium sulfate.

Technical advantages

High desulfurization efficiency: up to 95%~99%, suitable for high-sulfur coal flue gas treatment.

Resource utilization: The by-product ammonium sulfate (fertilizer) has economic value and no secondary pollution.

Strong adaptability: Good adaptability to flue gas load and SO₂ concentration fluctuations.

No wastewater discharge: The system operates in a closed loop, and the wastewater can be reused in the process.

Lower energy consumption: Compared with the limestone-gypsum method, the energy consumption is reduced by about 20%~30%.

Applicable Areas

It is suitable for power plants, steel, chemical industries and other industries, especially for enterprises with nearby ammonia sources (such as fertilizer plants) or need by-product fertilizers.

It is more suitable for flue gas treatment of medium and high sulfur coal (SO₂ concentration > 2000 mg/Nm³).