I/EC
Equipment
& Design
Economic Factors in Extraction Processes
txTRACTioN is a separation process with somewhat limited application. The process is inherently complex and equipment costly compared to separation by distillation. The big advantage of extraction over dis tillation is that operating costs are usually much less. One of the more common extrac tion processes is shown in Figure 1. This flow sheet is for the separation of a high-boiling product from an intermediate-boiling diluent using a low-boiling solvent. Recovery of acetic acid from water using ethyl acetate as a solvent is an example. The extractor replaces most of the diluent with a third component, the solvent. This produces a new problem—separation of product from a contaminant. In this case the contaminant is a solvent plus a small amount of diluent. It is ob vious that the distillation step must have become easier or extraction would not have been used. Separa tion is further complicated as some
Optimum design of an extraction proc ess depends on close attention to the distillation step, balancing capital and operating costs of the still vs. the value of the solvent loss
by G M. Oualline, Jr., Texas Instruments Inc.
C Acid
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