Process for separating alcohols from mixtures of alcohols, water and other compounds
AssigneeSnamprogetti S.p.A.
InventorsCarlo Rescalli, Flavio Cianci
Life of this patent
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Abstract
From a mixture containing methanol, ethanol, n-propanol, isobutanol water and other high-boiling and low-boiling compounds, the claimed process enables three separate streams to be obtained, one an anhydrous stream of methanol or methanol and ethanol (I), one containing most of the n-propanol present in the feed mixture (II), and one containing most of the isobutanol present in the feed mixture (III), by using three fractionating columns.
Claims12
A process for separating a feed mixture of from 1 to 70 wt % methanol, from 0.1 to 10 wt % ethanol, from 0.1 to 20 wt % n-propanol, from 2 to 80 wt % isobutanol, from 0.1 to 50 wt % water, and the remainder to 100 wt % of low-boiling organic compounds and high-boiling organic compounds;
- comprising
- (a) feeding to a first fractionating column via a side inlet said feed mixture so as to discharge (i) from the top of said first column, a gaseous stream consisting essentially of a portion of said low boiling organic compounds;
- (ii) from a side outlet located at a point above said side inlet, an anhydrous liquid stream consisting essentially of a portion of said methanol, ethanol or a mixture thereof;
- and (iii) from the bottom of said column, a liquid stream consisting essentially of substantially all of said n-propanol, isobutanol, water and height-boiling compounds and a portion of said methanol, ethanol or mixture thereof;
- (b) feeding said liquid stream of (a) (III) into a second fractionating column through a first side inlet so as to discharge (i) from the top of said second column, a stream comprising a portion of said n-propanol and a portion of said methanol, ethanol, isopropanol and water;
- (ii) from a side outlet below said side inlet, a liquid stream which, after cooling, is separated into an aqueous and an organic phase, said organic phase being recycled to a second side inlet immediately below said side outlet;
- and (iii) from the bottom of said column, a liquid stream comprising a portion of said isobutanol and high-boiling compounds;
- and
- (c) feeding said aqueous phase of (b) (ii) to a third fractionating column so as to discharge (i) from the top of said column, an organic stream consisting essentially of methanol, ethanol, n-propanol, isobutanol and high-boiling compounds, which is recycled by being added to said feed mixture before the latter is fed to said first fractionating column and (ii) from the bottom of said first fractionating column and (ii) from the bottom of said column, a stream consisting essentially of water;
- wherein said fractionating columns are operated in the range of 30 to 500K Pascal absolute.
Dependencies are inferred from the claim text.