Desorption of CO 2 , SO 2 , and NH 3 in the vacuum evaporation of desulfurization wastewater
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RESEARCH ARTICLE
Desorption of CO2, SO2, and NH3 in the vacuum evaporation of desulfurization wastewater Guifang Chen 1 & Xiaofei Sun 1 & Yunqi Feng 1 & Zhanlong Song 1 & Lin Cui 1 & Yanpeng Mao 1 & Chunyuan Ma 1 & Shouyan Chen 1 Received: 14 February 2020 / Accepted: 2 September 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Mechanical vapor compression and multi-effect evaporation have been widely used in achieving zero discharge of desulfurization wastewater as they are energy-saving and efficient technologies. Solubilized weak ions, such as CO32-, SO32-, and NH4+, in the desulfurization wastewater are partly converted into CO2, SO2, and NH3, respectively, during the vacuum evaporation process, thus affecting the heat exchange and compressor performance. In this study, the migration and coupling mechanism of CO2, SO2, and NH3 desorption in desulfurized wastewater under vacuum evaporation were analyzed. The effects of temperature, pressure, reaction time, and other factors on the migration process were discussed. The hydrolysis and electrolytic equilibrium constants of the related ions were obtained for temperatures between 70 and 90 °C. The results demonstrate the relationship between the desorption capacities of CO2, SO2, and NH3 and the hydrolysis constants of their respective ions. The desorption of CO2 and NH3 increased significantly when CO32− and NH4+ coexisted, whereas the SO2 desorption capacity remained low under the same experimental conditions. The experimental results indicate that the desorption of CO2, SO2, and NH3 is controlled by chemical reactions and can be described by first-order reaction kinetics. Keywords Vacuum evaporation . Desulfurization wastewater . Hydrolysis . Desorption . CO2 . SO2 . NH3
Introduction Zero discharge of desulfurization wastewater is getting more attention as environmental protection policies become
Highlights 1. The desorption capacity of CO2, SO2, and NH3 was related to the hydrolysis and ionization constants of related ions. 2. CO2, SO2, and NH3 desorption was controlled by chemical reactions and was described by first-order reaction kinetics. 3. The desorption of CO2 and NH3 increased significantly when CO32and NH4 + coexisted, whereas the SO2 desorption capacity remained low under the same experimental conditions. Responsible Editor: Philippe Garrigues * Shouyan Chen [email protected] 1
National Engineering Laboratory for Reducing Emissions from Coal Combustion, Engineering Research Center of Environmental Thermal Technology of Ministry of Education, Shandong Key Laboratory of Energy Carbon Reduction and Resource Utilization, School of Energy and Power Engineering, Shandong University, Jinan 250061, Shandong, China
stringent in recent years. Mechanical vapor compression and multi-effect evaporation, which are energy-saving and efficient vacuum evaporation technologies (Han 2015; Jiao and Wang 2009; Onishi et al. 2017), have been widely used for achieving zero discharge of desulfurization wastewater. The ionization balance of
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