Used 24 TPD pharmaceutical-grade glycerin plant, built by CMB of Italy in 2002. This plant is double effect type allowing a combined process flexibility and steam saving in the water vapor distilling from the first effect being used for the spent-lye concentration in the second effect. The distillation column of this plant is composed of various sections including: (1) Bottom Section: the glycerin and water are evaporated by an external reboiler with forced circulation. (2) First Packing Layer: the rising vapor is countercurrenrly washed by a partial recycle of condensed glycerin. In this section, all heavy components are scrubbed from the vapor. (3) Second Packing Layer: the glycerin condensed in the third packing layer is dried by countercurrent washing of the vapor. (4) Third Packing Layer: most of the glycerin is condensed by an external pumparound. (5) Fourth Packing Layer: the second grade glycerin is condensed by another external pumparound. (6) Demister: the vapor passes through it for separation of any entrained droplet.