The determination of plate efficiencies in unsteady-state plate-column models

Other investigations have shown the relationship between various plate efficiencies and the relationship between the Murphree plate efficiency and the point efficiency for steady-state conditions. So far there has been no work done on the relationship between the Murphree plate efficiency and the point efficiency for unsteady-state conditions. In unsteady-state distillation simulation, the Murphree plate efficiency has been held constant and it is thought that this may be the reason for the differences between experimental and theoretical liquid composition responses in some cases. Further, the liquid mixing models used to represent the mixing occurring on a distillation plate, do not include down-comer sections and the need for experimental investigation of the down-comer effect is required to produce a realistic model. Experimental conductivity impulse responses, using potassium chloride tracer, are obtained on a 7 ft. x 1.5 ft. sieve plate using the system air-water. The sieve trays, weir height and down-comer segmental area are variable, and the responses are compared with those obtained by the diffusion model. [Continues.]