Abstract: Desulfurization wastewater is difficult to be reused due to its complex composition. Therefore the flue atomization evaporation technology has been applied in the wastewater treatment at some power plants. However, the direct injection of desulfurization wastewater into the flue will cause problems such as corrosion, ash accumulation and clogging. A better option is offered by setting the bypass evaporation tower to dry the desulfurization wastewater. In order to study this technology, taking a 330 MW unit as an example, the flue gas extraction amount was determined by calculating the thermal mass balance between the desulfurization wastewater and the flue gas. Then the physical model was established, and the smoke flow field was optimized by numerical simulation. The steady state simulation was carried out for the nozzle arrangement, droplet diameter and flue gas temperature. The results show that even though the amount of flue gas extracted only accounts for 2.27% of the total flue gas volume, the flue gas flow field is enough to fill the entire evaporation tower. As a result of the atomization evaporation effect from the three nozzles, the evaporating tower outlet temperature can reach reach the designed value of 120 ℃. If the droplet diameter under 80 μm, the droplet particles will not stick to the wall. In particular the desirable evaporation effect is achieved when the droplet diameter is 60 μm. In summary, to prolong the residence time of the particles and make the particles non-adherent and less agglomerated, the flue gas swirling method is preferable with the selection of three nozzles, the atomized particle size of 60 μm and the inlet flue gas temperature of 600 K.

Key words: power plant, desulfurization wastewater, evaporation tower, atomization, thermal mass balance, numerical simulation