Enhanced oxidation of MgSO 3 during desulfurization by a novel spray method in magnesium-based seawater exhaust gas clean system

The magnesium-based seawater exhaust gas clean system is effective in reducing sulfur dioxide emission from marine diesel engines. Oxidation of the desulfurization by-product, magnesium sulfite (MgSO 3 ), is required for recycling. However, the oxidation efficiency is generally low in the aeration tank after the desulfurization process, making the tank volume too large for practical use on ocean vessels. In this article, we propose a novel spray oxidation method to enhance the oxidation of MgSO 3 during the desulfurization process. The effects of MgSO 3 content, pH and temperature on the oxidation rate were investigated. The results showed that the spray oxidation rate of MgSO 3 was 1.5 order with respect to the MgSO 3 concentration under both unsaturated and saturated conditions of MgSO 3 solution, which is different from the aeration oxidation researches. The spray oxidation rate decreased with the increase in pH and raised slowly as the temperature increased. The MgSO 3 oxidation mechanism of the spray oxidation method was analyzed and discussed in comparison with the traditional bubble aeration method. The novel spray oxidation method is effective in reducing the cost of the subsequent MgSO 3 aeration oxidation process and the offprint of aeration tanks, thus is promising to be applied on ocean vessels.