Fig. 4 Bilateral film flow. (a) The front side; (b) The reverse side;
(c) Diagram of BFF.
Fig. 4 shows the flow pattern of BFF. The operating conditions areF s = 0.8
(m/s*(kg/m3)0.5),L W = 26
m3/(m2*h). As shown in Fig. 4a, the
liquid phase flows to the upper edge of the blade unit under the
guidance of the guide blade. Affected by gravity, the liquid slowly wets
the surface of the blade unit under the guiding action and forms a thin
and stable liquid film. Because of the liquid-phase surface tension, the
sieve holes are covered with the liquid layer as well; however, with the
combined effect of gravity and the driving force of the gas phase, the
liquid film on the sieve hole will gradually sink and accumulate into
small droplets. The film at the sieve hole will be broken by the
airflow, creating a smaller gap. However, the kinetic energy factor is
relatively small; thus, the gas cannot break the liquid layer. The
droplets affected by the viscosity forces attach to the rear of the unit
sieve edge and form a dispersed liquid film flowing down the back of the
unit. At the same time, the sieve holes broken by the gas phase will be
covered by the liquid film again, repeatedly.
3.1.1.2. CPF