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Gas-washing and water injection are two commonly used methods in generating certain moisture content in gas flow stream, but the control accuracy of these methods remains uncertain. The purpose of the study is to investigate the characteristic of water vapor generation of the two methods. The temperature and humidity recorder and FTIR gas analyzer have been adopted to monitor the moisture content in tests. It has been revealed that, in gas-washing process, the moisture content in gas stream is well below saturation, and long time is required before moisture content stabilized after water bath temperature or carrier gas flow rate changed. Water injection pump could directly control the amount of water injected into gas stream. However, the moisture content generated in this way is not stable but oscillates in cycles, whose frequency and magnitude are closely related to water injection amount.

Wet limestone scrubbing is the most common flue gas desulfurization process (FGD) for control of sulfur dioxide emissions from the combustion of fossil fuels. Forced oxidation, which controls the overall reaction of the sulfur dioxide absorption, is the key path of the process. Manganese which comes from the coal is one of the catalysts during the forced oxidation process. In the present work, the two-film theory was used to analyze the sulfite forced oxidation reaction with an image boundary recognition technique, and the oxidation rate was experimentally studied by contacting pure oxygen with a sodium sulfite solution. There was a critical sulfite concentration 0.328 mol/L without catalyst or at a constant catalyst concentration value. The kinetics study focused on the active energy of the reaction and the reaction constant k; furthermore, we obtained the order with respect to the sulfite and Mn2+ concentrations. When the Mn2+ catalyst concentration was kept unchanged, the sulfite oxidation reaction rate was controlled by dual film and the reaction kinetics was first order with respect to sulfite while SO 3 2− concentration was below 0.328 mol/L; the sulfite oxidation reaction rate was controlled by gas film only and the reaction kinetics was zero order with respect to sulfite while SO 3 2− concentration over 0.328 mol/L. When SO 3 2− concentration was kept unchanged, the sulfite oxidation reaction rate depended on gas-liquid mass transfer and the reaction kinetics was different in various stages with respect to Mn2+ concentrations.