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Using traditional thermal evaporation to treat electroplating wastewater still consumes a lot of energy and it is impossible to completely separate salt and water. In order to separate salt and water with a high efficiency, a novel system combining air compression expansion cycle and spray drying tower is proposed for electroplating wastewater treatment. It is a good attempt to use the air compression expansion cycle as a component to provide service of heat and humidity treatment for the tower, and the feasibility of this combination is explored. In the paper, effects of compressor inlet parameters and pressure ratio on system performance are investigated, and the required pressure ratio is analyzed with different tower inlet temperatures. Meanwhile, the system efficiency ratio is compared with other systems. It is revealed that adjusting air compression expansion cycle to match spray drying tower is beneficial for the operation of the tower. The inlet air temperature of tower can realize to 159.6 °C, and its humidity is less than 6.37 g·kg−1. What’s more, increasing of inlet air humidity in compressor is proved advantageous for promoting system performance, and selecting appropriate inlet air temperature and pressure ratio of compressor can meet the demand of the spray drying tower and result in the improvement of system performance. Moreover, as the temperature difference between inlet of compressor and tower is increased, the pressure ratio required of system is increased. In addition, the system efficiency ratio can achieve 7.13 kg·kWh−1, and it is energy-efficient comparing with other systems.

Spray concentration tower, as an important system component, plays an indispensable role in solar energy air evaporating separation saline wastewater treatment system. In order to explore the best heating forms in the concentration process, the heat and mass transfer performance of the counter-flow spray concentration tower is investigated through CFD simulation and experiment. The results reveal that increasing the temperature of inlet wastewater is beneficial to accelerating the evaporation rate and evaporation efficiency. However, increasing the air inlet temperature increases the evaporation rate but decreases the evaporation efficiency. Meanwhile, when the heat carrier is wastewater, the heat and mass transfer performance of the tower is much better than that of heating supplied air, especially in dealing with the high concentration wastewater. According to the simulation, when the simultaneous heating type is utilized, there will be a phenomenon that the heat transfer direction will change, which leads to the situation that the air temperature decreases first and then increases through the direction of the tower height. It is found that this phenomenon is conducive to mass transfer. This is because heating wastewater solution not only increases the temperature difference but also increases the surface steam pressure. The performance of the experiment system in different heating modes is also compared. The simultaneous heating type spray concentration tower system has the highest GOR (up to 0.7162). Compared with the air heating type system, the GOR is increased by 22.5–27.2%, while the GOR is increased by 1.35–2.65% compared with the wastewater heating type system.