VERFAHREN ZUR SELEKTIVEN AN- ODER ABREICHERUNG FLÜCHTIGER BESTANDTEILE EINES FLUIDGEMISCHES

In a fluid treatment unit in which transient materials are selectively removed or added, fluid flows past a membrane through which unwanted constituents permeate to the other side. The novelty is that a fluid flows past the second membrane face contg. the same concn. of the wanted fluid as exists on the first face of the membrane, resulting in an approximately equal flow of the wanted fluid in both directions. This process typically makes use of PTMSP polymer membranes, and copolymers such as PPO and PDMS (polydimethylsiloxane) which have enrichment factors of 15 at 5 wt. % ethanol and 20 wt. % respectively. These membranes facilitate enrichment of ethyl alcohol which is greater than that achievable by vacuum evapn. USE/ADVANTAGE - Unwanted ingredients are sepd. from the original fluid with little change in the content of the wanted ingredient. The process offers two further selectivity mechanisms, the selectivity due to the membrane and that due to the speed with which the fluid passes across the face of the membrane. These lead to better quality sepn. of constituents leading in turn to fewer downstream processes and their associated energy costs. An example of the use is the removal of alcohol from drinks without a loss of CO2.