| 摘要 |
Methods of removing a lower alkyl alcohol from a polyester mixture of polyol fatty acid polyester and lower alkyl alcohol comprise (a) contacting the polyester mixture with a stripping mixture comprising an inert stripping gas, up to about 10,000 ppm lower alkyl alcohol and up to about 2000 ppm oxygen, wherein at least a portion of the lower alkyl alcohol is transferred from the polyester mixture to the stripping mixture, thereby increasing the concentration of lower alkyl alcohol in the stripping mixture, and (b) separating the stripping mixture from the polyester mixture. The methods further comprise (c) compressing the stripping mixture to increase its pressure, (d) cooling the stripping mixture to reduce its temperature thereby condensing at least a first portion of the lower alkyl alcohol to a liquid, (e) separating condensed lower alkyl alcohol from the stripping mixture to reduce the amount of lower alkyl alcohol in the stripping mixture to a range of from about 1 ppm to about 10,000 ppm, and (f) directing the resulting stripping mixture to an expansion turbine in which the temperature and pressure of the stripping mixture are reduced. Energy resulting from the decrease in the stripping mixture temperature and pressure in the expansion turbine is used to compress the stripping mixture separated from the polyester mixture.
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