Simulation on Evaporation and Motion of Atomized Droplets in Spray Dry Flue Gas Desulfurization Tower

The evaporation and motion of atomized droplets have an essential effect on the safe and efficient long-term operation of the desulphurization tower. Therefore, the two-phase flow model is established and solved by three-dimensional steady Reynolds-averaged Navier-Stokes equations; the droplets are tracked by Eulerian-Lagrangian method. The three factors, including inlet swirling flow of flue gas, initial droplet diameter, and inlet flue gas temperature, are analyzed to show the effects on the evaporation and motion of atomized droplets, respectively. The results show that the swirling flow of flue gas and initial droplet diameter dominate the penetration length of the atomized droplets and the mixing characteristic of droplets and flue gas. With the increase of droplet diameter, the length of droplet penetrating flue gas increases. When droplet diameter is 200 mu m and inlet swirl number is 0.35, droplets completely penetrate the core area. Therefore, this is the maximum initial droplet diameter at the inlet swirl number of 0.35. The droplets evaporation time of initial 150 mu m diameter is 85.5% longer than that of 50 mu m droplets (0.35 of inlet swirl number). Increasing the inlet flue gas temperature can enhance the heat transfer. When inlet flue gas temperature rises from 483 K to 523 K, the evaporation time decreases by 33.8%. The results can be used to guide the optimization of droplets spray evaporation under practical operating conditions in the desulfurization tower.