The models describing the mass transfer and chemical reaction of flue-gas-slurry drops in the deacidification tower of waste incineration plants are established. The internal dynamics are simulated and the effects of flue-gas inlet velocity, stoichiometric ratio, drop size and water spray rate, on deacidification performance, are evaluated. Results show that simulated desulphurisation and dechlorination rates are 58.97% and 99.99% and the removal rate of HCI is greater than SO2. A high-temperature zone is found in the upper part of central axis, whereas low-temperature zones are observed at the right wall and bottom. Flow field is characterized with complex recirculation zones, wherein the recirculation zone emerged on the upper-right entrains a small part of drops towards the right wall. Approximately 60% of the total removal amount of SO2 and 90% of HCI are absorbed in the upper part. Slurry drops completely evaporate in 5 s after entering the deacidification tower. The deacidification performance is improved with the increase in stoichiometric ratio and water spray rate, as well as the decrease in inlet gas velocity and drop size. Excellent deacidification performance is expected under flue-gas inlet velocity of 7.1 m/s, drop size of 50-70 mu m, and water spray rate of 600 L/h. (C) 2018 Elsevier Ltd. All rights reserved.