Effect Of Packing Density On Performance Of Novel Hollow Fiber Membrane Contactors

Hollow fiber contactor is a kind of new separation apparatus which has many advantages including wider operation range, higher separation efficiency, independent flow between liquid and gas. Many researches focused on membrane contactor's structural factors and mass transfer in recent years. Polypropylene hollow fiber membranes were used as novel structured packing in distillation of methanol-water solutions to investigate the effect of fiber packing density in this paper.Distillation experiments were carried out with three modules whose packing densities ranged from 4.7 % to 19 %. Results showed that all the contactors with different packing densities worked well above the limit where flooding normally occurs in conventional cases. Distillate concentration from membrane contactors with the packing density of 4.7% or 19% was bigger than that of 9.5%. Experimental Sherwood number was smaller than calculated Sherwood number at low packing density, but bigger at high packing density. It was also found that higher Reynolds number yielded better shell-side mass transfer. The Sherwood Numbers at high packing density were smaller than those at low packing density. The resistance of vapor decreased with the increasing of F factor. The higher the packing density was, the bigger the resistance of vapor would be. The resistance in the liquid was responsible for more than half of the total resistance. Overall mass transfer coefficients K_G decreased rapidly with increasing packing density and the maximal K_G value could reach as big as 391.84×10^-5 m/s.