Simulation and experimental study on the desulfurization for smelter off-gas using a recycling Ca-based desulfurizer

摘要

In this paper, a novel desulfurization process was proposed to recover elemental sulfur from smelter off-gas with high-content sulfur dioxide (SO2) using calcium sulfate (CaS) as a new recycling Ca-based desulfurizer. Based on the simulation results, an optimum temperature range between 450 degrees C and 550 degrees C was determined. In that range a high SO2 removal efficiency was obtained for the smelter off-gas, indicating that all the SO2 gas was converted to elemental sulfur. To achieve autothermal operation of the whole process, a suitable range was identified for the circulating ratio of quartz sands used as the heat carriers. The practicality of Ca-based desulfurizer was tested through the multi-cycle desulfurization/regeneration tests. High temperature was favorable for the improvement of the SO2 removal efficiency, which was higher than 98.5% in the initial desulfurization period at the temperature above 500 degrees C. However, increasing the space velocity would reduce the SO2 removal efficiency, especially at the late period of desulfurization. The desulfurizer showed a good recyclability in the multi-cycle tests for both the off-gas with and without oxygen. Both the SEM images and energy dispersive X-ray analyses proved that the desulfurizer particles showed good multicycle stability and recyclability. Both the Raman spectroscopy and the EDS spectrum of the collected sulfur particles indicated that the sulfur particles were composed of the orthorhombic alpha-S-8 species and the amorphous mu-S species. The desulfurizer particles slightly agglomerated over the repeated cycles from both the particle surface area analysis and the particle size distribution analysis. (C) 2016 Elsevier B.V. All rights reserved.