SEPARATION OF FLUID MIXTURES IN MULTIPLE DISTILLATION COLUMNS

摘要

The present invention relates to a method for the separation of a fluid mixture containing at least one more volatile component and at least one less volatile component. The fluid mixture is introduced at a first pressure as a first feed stream into a first distillation column having at least one separation stage above the feed point and a first overhead vapor and a first bottoms liquid is withdrawn therefrom. The first bottoms liquid is flashed to a second pressure and the resulting flashed first bottoms stream is fed to a second distillation column. A second overhead vapor enriched in the more volatile component and a second bottoms liquid enriched in the less volatile component are withdrawing from the second distillation column. At least a portion of the first overhead vapor is condensed and at least a portion of the resulting first condensate is returned to the first column as reflux. The cooling duty for condensing the first overhead vapor i provided by indirect heat exchange with either (1) fluid at an intermediate point in the second column or (2) at least a portion of the resulting flashed first bottoms stream prior to the second distillation column. The temperature at the bottom of the first column is equal to the temperature at the bottom of the second column and the temperature at any other point in the first column is between the highest and lowest temperatures in the second column; or the temperature at any point in the first column is between the highest and lowest temperatures in the second column.