Continuous SO2 absorption and desorption in regenerable flue gas desulfurization with ethylenediamine-phosphoric acid solution: A rate-based dynamic modeling

Abstract

The amine-based flue gas desulfurization (FGD) method is a competitive and promising technique to realize SO2 removal and sulfur recycling from flue gas. To study the steady and transient state behaviors of continuous SO2 absorption and desorption processes with ethylenediamine-phosphoric acid solution, a rate-based system model including main units for regenerable FGD was developed and validated with experimental data. The influence of main operating conditions on the dynamic characteristics of technological parameters was investigated, moreover, a comprehensive analysis was performed to reveal the mechanism behind the parameter evolution. The results indicate that simulation results agree well with experimental data and the absorption efficiency, desorption efficiency, lean loading, and rich loading are correctly predicted, respectively. Both absorber and desorber are driven by transfer properties, and the latter is operated in a lean-pinch mode. Either the rich-SO2 loading or the gas-liquid equilibrium significantly affects the desorption performance, and an increase in rich-SO2 loading is beneficial to lower the reboiler heat duty. The normal desulfurization operation could be maintained during load-reduction scenario by cooperating with reasonable reduction of reboiler duty and moderate solvent flowrate. This work could provide engineering guidance to design the control system of amine-based FGD process for upscale exploration and input for a deep processing of SO2 product subsequently.