Wiped film evaporators induce a mechanically agitated thin (wiped) film with a high surface renewal rate against the interior heat transfer surface while the evaporator is operating under vacuum, so that the product sees primarily the equilibrium conditions inside the evaporator. Feed material is tangentially distributed onto the interior wall of the evaporator, and the wiping blades smear this liquid against the heated surface in a rapidly renewed thin film surface with heat on one side and the vacuum conditions on the other side of the film. The residence time of this material inside the wiped film evaporator is a few seconds before the concentrated bottoms exit the evaporator. Evaporated volatile components exit the wiped film evaporator and are condensed in a separate chamber (unless micron vacuum levels are required to reduce heating conditions further; for more information regarding this alternative, please see our molecular distillation section).
Applications of Wiped Film Evaporator
Hopefully, the above comments have demonstrated the value of molecular separation in the hemp oil processing field, but there are additional processing areas in this industry where more conventional wiped film evaporators, with external condensers, operating at moderate vacuum levels (e.g., 0.5 to 5.0 mm Hg absolute pressure) will establish their value. For example, ethanol extraction is perhaps becoming more commonplace as an alternative to CO2 or Hydrocarbon extraction. Further, there are still many producers who prefer winterization methods applied either before or after molecular separation distillation which also utilizes ethanol as the preferred solution. Based upon current industry practice, organizations using ethanol are typically using rotary evaporation techniques to separate the ethanol from the hemp oil product.
Rotary evaporators have historically been used in many laboratory applications and the relative simplicity of the operation of these systems has resulted in a strong market sector. However, rotary evaporators have size and processing rate limitations which limit their growth in the hemp oil processing sector. In addition, as processing requirements increase, the rotary evaporator will have to surmount the inherent safety issues associated with processing large quantities of ethanol.
Wiped Film Evaporator have historically occupied a large segment of the industrial market related to processing or stripping flammable solvents from other constituents. Wiped Film Evaporator technology is already being applied in the hemp oil sector in relation to separating ethanol from hemp oil constituents, in a fashion which complies with NFPA (National Fire Protection Association) and subordinate NEC (National Electrical Code) requirements to provide for the flammability hazards associated with processing ethanol solutions. In many states regulatory agencies are placing more emphasis on compliance with NFPA standards associated with handling and processing flammable liquids and these efforts will likely expand.
Typical System configurations for Short Path Distillation Systems
Although the general principles related to Short Path Distillation systems have been discussed and illustrations have been presented to facilitate the comprehension of molecular separation concepts pictures of Short Path Distillation Units may provide a better grasp of the technology. Indicated below are a number of photographs related to Distillation systems devoted to hemp oil processing.