Effects of different alkali-based materials on coal-fired flue gas dechlorination

Three common alkali-based materials, NaOH, Na₂CO₃ and NaHCO₃, were utilized to explore their dechlorination performance in a simulated coal-fired flue gas. The results show that the dechlorination efficiency increases along with the enhancement of alkaline intensity. As the Na/Cl molar ratio reaches 5.8, 7.1 and 8.7, respectively, the dechlorination efficiency of all the three alkalis (NaOH, Na₂CO₃ or NaHCO₃) exceeds 70%. The SO₂ of high concentration in flue gas has competitive effects on dechlorination. With the increase in SO₂ concentration, the dechlorination efficiency drops linearly. The influence of SO₂ concentration on the dechlorination efficiency is almost identical regardless of different alkali-based materials. For per 100 mg/m³ augment in SO₂ concentration, the dechlorination efficiency decreases by about 1.4%. NaOH is determined to be the most valuable alkali-based material for industrial application considering the cost and solubility.