Rodolphe Vautherin, Hélène Métivier, Anne Reguer, Hassen Benbelkacem
Sulfur Dioxide (SO2) is an important pollutant in most industrial sectors, including waste incineration. It is necessary to control its emission into the atmosphere. When this gas is present in sufficiently large quantities in the flue gas, it can also be interesting to recover it.
The process studied here recovers sulfur dioxide in the form of a marketable solution of sodium bisulfite NaHSO3 from waste incineration flue gases. The process comprises two reactors. The flue gas passes through both reactors placed in series, and the SO2 is absorbed in each reactor, ensuring zero SO2 emissions at the outlet of the process. The liquid phase flows through the system in counter-current to the flue gas. The first reactor is regulated at acidic pH to form the sodium bisulfite solution, while the second reactor is regulated at basic pH to form the absorption solution of the first reactor, a sodium sulfite solution Na2SO3.
The process was studied in the laboratory using a synthetic gas under controlled conditions. The aim was to study the impact of operating conditions such as temperature and oxygen content on absorption reactions using batch tests. Subsequently, pH control tests were used to study more specifically the feasibility of the process, including the ability to concentrate the bisulfite solution. This step also enabled us to study the yields achievable in the two reactors at different control pHs.
