FR2461751A1 - Prodn. plant for anhydrous ethanol for motor fuel - from fermented wine must distilled via two columns in series - Google Patents

Abstract

The must contain 8% to 10% alcohol by vol. and the installation comprises only two distn. columns in series. Must is fed into the first column which operates at vacuum pressure and passes a head prod. rich in alcohol to the second column, which operates under positive pressure. Anhydrous ethanol is delivered as tail prod. of the second column which is heated by its own alcoholic vapour after compression in a mechanical turbo-compressor. Low pressure exhaust steam from the second column is used to heat the first column. Alcoholic mixt. of only medium concn. delivered at the head of the second column is recycled to feed the first column. The yield is not less than 97% of the alcohol contained in the must. Previous plants achieved about 90% yield. Energy savings compared with earlier plants are of about 50% steam and 40% cooling water.

Description

a) The present invention relates to installations for the production of dehydrated alcohol intended to be used as fuel.

 b) In known devices for the manufacture of anhydrous alcohol, dehydration is effected by; introduction of a entrainer into the dehydration column to form a ternary hetero-azeotrope: water-alcoholentrainer with low boiling point. The process necessarily requires the use of an alcohol already rectified because the presence of impurities hinders the separation of the coach body and seriously disrupts the functioning of the system.

This method therefore has the following consequences when operating directly from a fermented must:
aj Use of four columns,
b) Steam consumption of the order of 400 Kg per 100 L of dehydrated alcohol,
e) Coach consumption 0.2 Kg per 100 L of dehydrated alcohol,
d) Consumption of cooling water of the order of 5 m3 per 100 L of dehydrated alcohol,
e) Production of dehydrated alcohol representing only 90% of the alcohol present in the food must.

The device proposed by the present invention allows the following improvements:
a) No use of trainer,
b) Use of only two columns,
c) Steam consumption of less than 210 Kg / 100 L of deshy -drat alcohol,
d) Consumption of cooling water less than 2.9 m / la0 L of dehydrated alcohol,
e) Dehydrated alcohol produced greater than 97% of the alcohol present in the food must.

note: The consumption of electrical energy is substantially the same as in the conventional process.

 The process which is the subject of the nventSon uses the change in alcoholic richness of the azeotropic water-alcohol mixture as a function of pressure, @ ssociated with a system of mechanical recompression of alcoholic vapors.

The recompression is carried out using a turbo-compressor group whose exhaust vapors are fully reused.

The increase in azeotropic richness by lowering pre; on
is a characteristic of water-alcohol mixtures. The recovery of anhydrous alcohol by distillation under pressure of the "rich" mixture thus obtained is known. This method unfortunately leads to a very high consumption of steam and water. What makes the proposed device original is to associate it with mechanical compression of the vapors leaving in taste from the column under pressure. The description of the process which follows will refer to the block diagram annexed to this description.

- Food wine A after passing through the heat recovery units
E 145 and E 140 enters the column C 140 which operates under a residual pressure of 190 mm Hg at the head.

 - The amyl oils E are extracted thanks to an incorporated decanter and a slight outlet of heads F (2 of the total alcohol) is provided.

 - The concentrated alcohol at 97% by weight is taken from 2 trays below the top of C 40, and feeds column C 180 thanks to ~ the pump P 141, passing through the recuperator E 182.

 - This column C 180 operates under a pressure of 7 bars absolute.

Under this pressure, the richness of the alcohol-water azeotrope is 93.6 G by weight.

The feed of this column can therefore be considered as a "pseudo binary" mixture consisting of 40.6% by weight of azeotrope (most volatile body) and 59.4% of absolute alcohol (least volatile body)
- Absolute alcohol leaves in feet B and is cooled in E 181.

The azeotrope mixed with 10% absolute alcohol leaves the top and is recycled to C 140 by line G
The vapors emitted at the top of C 180 are compressed from 7 to 8 bars by the axial compressor P 180 driven by the steam turbine P 181.

The compressed and saturated alcohol vapors (by a slight injection of absolute alcohol) feed the condenser-boiler E 180 which heats the column C 180,
The exhaust vapors of P 181 are directly useful for the
heating of C 140,
The steam supplies are therefore only as follows:
1 C 140 backup heater
2 Feeding the P 181 trubine
3 C 180 backup heater
The cooling water supplies are:
4 Cooling of the additional condenser E 14
5 Cooling of the final refrigerant E 181.

Claims (1)

CLAIM  Device for producing ethyl alcohol  dehydrated directly from fermented musts. The object of the invention is to produce dehydrated alcohol from a fermented must containing 8 to 10% by volume of alcohol. The device is characterized by: The use of two columns, one operating under vacuum and the other under pressure instead of the three columns usually used in conventional methods.  The fermented wine feeds the first column operating under vacuum and produces at the top a mixture very rich in alcohol, this mixture feeds the second column which works under pressure, the dehydrated alcohol leaves through the bottom of this second column. The alcoholic vapors from column N02 are compressed by a mechanical turbo compressor and are used to heat this same column, the low-pressure exhaust water vapor is used to heat column N01 and the medium-concentration alcoholic mixture leaving the head from column N02 is recycled to the feed from column N0 I.