关键词: 脱硫废水零排放, 烟气蒸发, 液滴蒸发特性, 数值模拟

Abstract:

Spraying flue gas desulfurization (FGD) wastewater into flue duct is an economical and feasible technology to achieve zero discharge in power plant. To deal with the scale and corrosion on flue walls that exist in the practical application of this technology, the physical and mathematical models are established based on a 300 MW power plant. The Eulerian-Lagrangian approach is used to describe the thermo-fluid behavior of FGD wastewater in flue gas, by which the turbulent flow heat transfer of flue gas is described by the Eulerian framework and the evaporation of water droplets is described using the Lagrangian framework. By numerical simulation the flow evaporation characteristics and influencing factors of FGD wastewater droplets sprayed in flue gas were studied. The diffusion range and trajectories of atomized droplets under different operating conditions were obtained. The following results were gained:higher flue gas temperature and smaller diameter of the atomized droplets contribute to shorter time and distance for complete evaporation. Besides, the arrangement of small-flow-multi nozzles can improve the evaporation of atomized droplets. The spray direction must ensure that the relative movement between atomized droplets and flue gas is enhanced, while the droplets can fully diffuse and contact with the flue gas within a specified distance and time, achieving maximum evaporation of the atomized droplets. However, the initial velocity of atomized droplets, the spray full cone angle of nozzles, and the velocity of flue gas have little influence on atomized droplets evaporation. These research results can provide process design and performance regulation of the FGD wastewater evaporation in flue duct of thermal power plants.

Key words: desulfurization wastewater zero discharge, flue gas evaporation, droplet evaporation characteristics, numerical simulation