Enhanced oxidation of MgSO3 during desulfurization by a novel spray method in magnesium-based seawater exhaust gas clean system

摘要

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 (MgSO3), 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 MgSO3 during the desulfurization process. The effects of MgSO3 content, pH and temperature on the oxidation rate were investigated. The results showed that the spray oxidation rate of MgSO3 was 1.5 order with respect to the MgSO3 concentration under both unsaturated and saturated conditions of MgSO3 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 MgSO3 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 MgSO3 aeration oxidation process and the offprint of aeration tanks, thus is promising to be applied on ocean vessels.