*3.3. Effect of Wastewater Flow Rate on The Evaporation Performance*

Figure 10 shows the turbulence kinetic energy under different wastewater flow rates. By increasing the wastewater flow rate, the turbulence kinetic energy in the mixing zone of flue gas and droplet changes slightly, which indicates the slight difference in the mixing intensity between flue gas and droplet. Figure 11 displays temperature under different wastewater flow rates. The larger wastewater flow rate corresponds with the lower temperature in the mixing zone of flue gas and droplets because the evaporation process of larger wastewater flow rate absorbs more heat.

**Figure 9.** Effect of flue gas temperature on evaporation performance.

**Figure 10.** Turbulence kinetic energy under different waste water flow rates (m2/s2).

**Figure 11.** Temperature under different wastewater flow rates (K).

Figure 12 shows the effect of wastewater flow rate on the droplet evaporation performance in the spray drying tower. With the increase of the wastewater flow rate, the droplet residence time in the spray drying tower becomes longer and the complete evaporation distance increases, thus, reducing the wastewater flow rate is beneficial to the evaporation performance of the wastewater. On the one hand, under the same flue gas flow rate, the input heat is constant. The larger wastewater that needs to be processed, the more time it takes to evaporate. On the other hand, the larger wastewater flow rate contains more large-diameter droplets. For these large-diameter droplets, more time is required for them to evaporate completely, and the complete evaporation distance is longer. Therefore, it is necessary to design the wastewater flow rate in a spray drying tower.
