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• A new corrosion-resistant experimental system was designed to study SOx absorption reaction with alkaline sorbents. • The SO 3 absorption performance of the three alkaline sorbents was Na 2 CO 3 > Ca(OH) 2 ≈ Mg(OH) 2. • The influence of operating parameters on SO 3 removal had been deeply studied. • The SO 3 absorption variation above 300 °C was similar to the condition without vapor. • The external diffusion control model was established for SO 3 absorption rate. Selective Catalytic Reduction (SCR) system can efficiently remove NOx in coal-fired power plant, while raise SO 3 concentration in the flue gas. Alkaline sorbent injection is a major approach to remove SO 3. Experiments were conducted to study the SO 3 absorption performance of alkaline sorbent. The SO 3 absorption performance of the three alkaline sorbents was Na 2 CO 3 > Ca(OH) 2 ≈ Mg(OH) 2. The ratio of SO 3 absorption rate to SO 2 absorption rate for Na 2 CO 3 increased with the increasing temperature. The key parameters on the SO 3 absorption performance of Na 2 CO 3 were studied. The SO 3 absorption by Na 2 CO 3 was increased by 72.7% with increasing temperature from 150 °C to 300 °C, and the temperature had little influence on SO 3 absorption above 300 °C. The increasing SO 3 concentration and decreasing particle size of Na 2 CO 3 enhanced SO 3 absorption. However, when the average particle diameter was less than 50 μm, the SO 3 absorption was no longer significantly increased. The increasing CO 2 concentration slightly reduced the SO 3 absorption. After adding vapor into the flue gas, the SO 3 absorption was obviously increased below 300 °C. The SO 3 absorption variation above 300 °C was similar to the condition without vapor. When reaction temperature was 300 °C or above and reaction time was less than 20 min, external diffusion became the control step for SO 3 absorption. On the basis of external diffusion control model, the mass transfer coefficient slightly increased from 1.68 × 10−3 m/s to 1.75 × 10−3 m/s when the reaction temperature increased from 300 °C to 400 °C. [ABSTRACT FROM AUTHOR]

The life cycle environmental impacts of widely used flue-gas cleaning processes, including limestone-gypsum wet flue-gas desulfurization (FGD), selective catalytic reduction denitration (SCR) and electrostatic precipitators (ESP), are compared. The abbreviations FGD, SCR and ESP in this article refer in particular to the above listed processes. Energy consumption, resource consumption and emission inventories of each life cycle phase are established. The potentials of five environmental impact categories, namely, global warming, acidification, nutrient enrichment, photochemical ozone formation, soot and ashes are finally obtained. The current paper reveals that the total energy consumption and resource consumption are dominated by the process operation. The three processes are compared and it is found that to achieve equal environmental burden reductions, the SCR process consumes more energy and approximately the same amount of air and inert rock as the FGD. But the water consumption of the FGD is much higher than the SCR. The ESP process consumes both the least energy and the least resource in general. The economic assessment indicates that the performance of the ESP process tends to be the best and the FGD follows when equally invested. [ABSTRACT FROM AUTHOR]

• Established a dual-layer monolith model coupling reaction and mass transfer. • Gave suggestions on design of active layer thickness by analyzing over 175 cases. • Analyzed the influences of average pore size of catalyst on SCR and SO 2 Oxidation. Nitrogen oxides (NOx) and sulfur dioxide (SO 2) are common gaseous pollutants in the flue gas of stationary resources, such as thermal power plants. The undesired oxidation of SO 2 on the catalytic monolith for Selective Catalytic Reduction (SCR) with ammonia will cause deposition of ammonium bisulfate, corrosion and extra pressure drop to downstream devices. A dual-layer model of catalytic monolith was established in this work to thoroughly investigate the effects of active layer thickness on SCR reaction and SO 2 oxidation under various operating parameters. Besides, the influences of different sizes of nanopore in catalyst on both reactions are discussed. Thus, optimal parameters and suggestions were given for the design of SCR catalytic monolith with low SO 2 oxidation. [ABSTRACT FROM AUTHOR]