A novel technical route based on wet flue gas desulfurization process for flue gas dehumidification, water and heat recovery

Abstract

To recover the water and heat in industrial flue gas before discharging, a novel dehumidification system was proposed by combining the liquid-desiccant-based dehumidification (LDD) method with the existing wet flue gas desulfurization (WFGD) process in a single spraying tower. Calcium chloride (CaCl2) solution was used as a liquid desiccant. A flow pattern controlling (FPC) device was designed to further enhance the mass transfer in the dehumidification process. The effects of liquid-to-gas ratio (L/G), desiccant solution temperature (Tde), desiccant concentration (ω), and superficial flue gas velocity (vg) on the dehumidification performance were investigated. The water and heat recovery process of the LDD-WFGD system were analyzed theoretically in detail. Furthermore, the application potential of the proposed LDD-WFGD system for water and heat recovery for coal-fired power plants was discussed by conducting case studies. The recovered water from flue gas could supply 47.2% and 44.8% of the water demand for the WFGD systems in 660 MW and 330 MW power plants, respectively.