Study on Co-oxidation of Gaseous Elemental Mercury of Coal-fired Flue Gas by Wastewater Injection

The Hg⁰, Hg²⁺ and Hg_p distribution of coal-fired flue gas was investigated by the OHM and hydride generation-inductively coupled plasma atomic emission spectrometry (HG-ICP-AES) method. The impacts of chlorine and sodium content of wastewater and SO₂ and NO concentration of flue gas on Hg⁰ oxidation were tested on the coal-fired test furnace in hot state. The results showed that the ferrous and chlorine content in the test coal was low and the ratio of Hg⁰ to Hg_T was 68.3% and 80.6% for coal-fired flue gas 1^# and 2^# respectively, while Hg²⁺ ratio was only 22.2% and 13.1% respectively. When the sodium acrylate and naphthalene sulfonate wastewater liquid to flue gas ratio was 0.028 L/m³, the Hg²⁺ ratio reached higher than 80% and 75% in coal-fired flue gas 1^# and 2^# respectively. While, there were no significance variations for Hg_p ratio in flue gas. When the wastewater liquid to flue gas ratio was 0.028 L/m³, the SO₂ concentration decreased by 11.4%-15.7% and 12.2%-17.7% for coal-fired flue gas 1^# and 2^# respectively, which accelerated Hg⁰ oxidation. There was no significant effect of NO in flue gas on Hg⁰ oxidation.