A study and comparison of plate and tubular evaporators

Desalination processes based on multi effect are in wide use in the chemical industry for separation of ingredients from solution mixtures. However, seawater desalination using this process has not achieved the commercial importance compared to the multi stage flash process in terms of the total installed capacities. In view of recent technological advances there are a number of good indications that this situation may change in favor of the multi effect process. This paper reviews the different basic evaporators employed in distillation processes and their principle operations. The paper then provides an approximate comparative analysis of the horizontal tubular and plate type evaporators with respect to heat transfer area requirement, pressure drop, flow pattern and heat transfer coefficients.

Laminar region Nu (28) for 10<Re<2000. For the plate-coil evaporator shown in Fig. 1, the heat transfer coefficient can be approximated as a weighted average of the heat transfer coefficient on a vertical plate and that on a horizontal tube.