Enhancing aerosol emission reduction in an ammonia-based WFGD system with tray implementation

Abstract

Operating parameter optimization is a viable strategy to reduce aerosol emissions from an ammonia-based wet flue gas desulfurization (ammonia WFGD) system. But the optimization techniques typically cause SO2 removal efficiency reduction. Multi-hole trays can be installed in the scrubber to balance the aerosol emission control and the desulfurization efficiency. The experimental results show that the tray installation alone can barely enhance aerosol emission control. However, the tray installation can improve the SO2 removal efficiency to spare more space for operating parameter optimization. The smaller hole size favors the SO2 removal with a particular hole ratio. Optimizing the liquid-to-gas ratio (L/G) works well with tray installation to realize aerosol emission reduction, with the aerosol reduction rate over 50 %. The improvement brought about by the tray installation only works within a specific L/G range, beyond which the tray cannot make up for the desulfurization efficiency reduction caused by L/G optimization. The best aerosol emission reduction rate was achieved at L/G = 8 L/m3 with the tray installation of 35 % hole ratio and 10 mm diameter, with the desulfurization efficiency maintained above 90 %. The tray with 35 % hole ratio and 20 mm diameter can be employed at L/G = 8 L/m3 for better aerosol emission if the SO2 removal efficiency below 90 % is acceptable. The choice is due to desulfurization efficiency and aerosol emission control demand.