Flue gas purification from SO2 and NOx using molten mixture of alkali metal carbonates

ABSTRACT

Sulfur dioxide (SO₂) and nitrogen oxides (NO_x) in flue gas are a hazardous atmospheric pollutant associated with coal combustion and non-ferrous metal production. Here we report that laboratory pilot unit for scrubbing of industrial flue gas containing 80 ± 2 ppm SO₂ followed by melt regeneration with either CO or natural gas, verified that only 1.5–2.0 ppm SO₂ remained in the flue gas. The tests with the semi-industrial scale unit (271.26 kg of the eutectic carbonate melt and flue gas containing 0.15% SO₂, 13 ppm NO, 52 ppm NO₂) were received. In all tests, sulfur extraction from flue gas to the carbonate melt was >90–95% and nitrogen oxides extraction from flue gas to the carbonate melt was 60%. Sulfur and nitrogen oxides extraction from carbonate–sulfate–nitrite melt during regeneration stage was >99%. Carbonate melt-based SO₂ scrubbing therefore represents a practical and economical method for limiting sulfur and NO_x emission to the atmosphere from both coal-firing power stations and non-ferrous metallurgical processing plants.

KEYWORDS:

• SO₂ and NO_x emission
• environmental pollutant
• carbonate eutectic melt
• flue gas
• coal-firing power stations

Additional information

Funding

This work was supported by the Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan under Grant No. AP08856384;The Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan [AP08856384].