The flow, heat, and mass transfer of falling-water films in a dip tube in an industrial-scale water-scrubbing cooling chamber was predicted using a 2D numerical simulation. The VOF model was adopted to describe the free surface between the gas and liquid. The Rosseland model was applied to solve the radiative heat transfer equation. The surface tension between the gas and liquid phases was also considered. The predicted axial-temperature distribution of the bench-scale results were in good agreement with the experimental data, validating the feasibility of the numerical models applied in this Article. The simulation results indicated that the thickness of the inlet water film and the velocity of the inlet falling-water film in the industrial-scale dip tube had a large influence on the mass, heat transfer, and flow patterns of the falling-water film. When the thickness of the inlet water film was increased to 0.004 m, the outlet hot-syngas temperature of the dip tube decreased to about 100 K. Furthermore, the results showed that the hot syngas was humidified sufficiently during the mass-transfer process.