Condensational Growth Activated By Cooling Method For Multi-Objective Treatment Of Desulfurized Flue Gas: A Full-Scale Study

The desulfurized flue gas from coal-fired power plants is discharged with pollutants and a lot of heat and water vapor into the environment. To synchronously reduce the pollutant emission and recover the heat and water, a novel technology was proposed and applied in a coal-fired power plant after experimental and pilot studies. The technology, referred to as phase transition agglomeration system (PTAS), was developed based on condensational growth and subsequently enhanced removal of particles and droplets under supersaturated conditions. Unlike existing research, the supersaturation here is produced by cooling the desulfurized flue gas through an appropriate approach, which is more feasible for industrial application. Meanwhile, heat and water are recovered. Field measurements were conducted to study its performance. Particle removal efficiencies of the full-scale PTAS were 53.05% and 71.11% at 90% and 75% loads, respectively, and the emission concentrations were reduced to below 5 mg/m(3). SO3 removal efficiency was nearly 20% at the initial concentration of similar to 2.9 mg/m(3). >87% of the heat released by the flue gas and over 83% of the condensate were recovered. The recovered heat was utilized directly to heat the feed water of boiler, and the recovered water could be used to replenish the desulfurization slurry after alkali treatment. The heat and water recovery rates were up to 3.59 MW and 4.32 t/h, respectively, which improved the economics of the power plant. The good performance of PTAS in particle and SO3 removal, together with heat and water recovery, was demonstrated in this full-scale study, and worthwhile data and experiences were provided for the development of such technologies for further treatment of coal-fired flue gases.