This
paper presented a novel technology for the desorption of SO2 in the basic aluminum sulfate solution (BASS) by falling
film evaporator with spring tube. The liquid film falling along the
internal surface of the evaporation tube was heated by the steam outside.
The desorption performances of the vertical single falling film evaporators
with spring tube and smooth tube were comparatively investigated.
The film distribution on the inner surface of the two tubes were also
analyzed through visualization experiments. Compared with the smooth
tube, the spring tube was found to be much better in heat transfer
and mass transfer. Thus, analysis on the operating parameters for
the desorption of SO2 was performed only in the spring
tube. The results showed that the flow rate of BASS rich in SO2, heating steam temperature, vacuum of the system, and initial
concentration of SO3
2– played important
roles in the desorption performance.