Model and experimental research on gas-solid phase partition of chloride ion in the process of desulfurization wastewater evaporation using flue gas

Since the promulgation of “water pollution control action plan” in China,a zero liquid discharge of desulfu- rization wastewater has become a new trend of water pollution control in power plant. Aiming at the core technical issue on the application of desulfurization wastewater evaporation technology using high temperature flue gas,the modeling and experimental research on the gas-phase conversion characteristics of chloride ion under different operation condi- tions were carried out in this paper. The traditional gas-liquid equilibrium theory was applied to the complex mixed salt system. Based on state equation,the model of chloride ion gas-solid phase partition coefficient in ideal system was calculated. The ideal model was validated and linearly corrected with complex water namely desulfurization wastewater by correction factor ε and correction constant φ. Then,experimental research was conducted using self-designed device. The interaction and significance of each factor were compared and analyzed. The order of influence significance on chloride ion gas-solid distribution coefficient is temperature>pH>Cl- concentration>Mg2+ concentration>Ca2+ concen- tration>Na+ concentration. The correction factor is determined using real desulfurization wastewater and orthogonal ex- perimental data ε = 1. 068. The correction constant φ contains key environmental parameter like temperature and water quality parameters that affect the gas phase conversion of chloride ion. MATLAB was used to calculate the models, three fitting forms were selected and the linear fitting had the highest correlation R2 = 0. 925 8 that meets with require- ment. Finally,the model of chlorine ion gas-solid phase partition coefficient suitable for the temperature range from 180 to 380 ℃ was obtained. The study provides key data for the application of high temperature flue gas evaporation tech- nology,obtains the quantification and prediction of chloride ion volatilization during desulfurization wastewater evapora- tion. The research results provide an important theoretical and practical reference for the application of this technology.