FORM 2
THE PATENT ACT 1970
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10 and Rule 13)
1. TITLE OF THE INVENTION
IMPROVED RECOVERY OF POTABLE ALCOHOL
2. APPLICANT
(a) NAME: PRAJ INDUSTRIES LIMITED
(b) NATIONALITY: Indian Company
(c) ADDRESS: PRAJ House, Bavdhan, Pune-411021, INDIA
3. PREAMBLE TO THE DESCRIPTION
The following specification describes the invention and the manner in which
it is to be performed.

4. DESCRIPTION
FIELD OF THE INVENTION
The invention relates to a process and apparatus for the improved recovery of potable alcohol and more particularly to an add-on apparatus that is used in conventional ethanol distillation plant, wherein different technical ethanol cuts obtained at different steps of ethanol distillation are collected and subjected to a process of purification as per the disclosed invention, and further recycling to said ethanol distillation plant increasing the overall recovery of potable alcohol of said plant.
BACKGROUND
Many alcoholic beverages are produced comprising one or more of the steps of [1] producing ethanol by fermentation of a carbohydrate-rich feedstock to produce a fermented wash having concentration of about 2 to 23% alcohol by volume [ABV]; [2] distilling the product of fermentation at elevated temperatures to produce ethanol products like rectified spirit, neutral spirit or absolute alcohol and; [3] aging the ethanol spirits until it possesses desired flavour, aroma, and colour characteristics. The commercial production of alcohol by distillation has been in widespread operation for many centuries.
The distillation is a known technique for purification of a liquid substance and involves vaporizing the substance at its boiling point, condensing the vapour and collecting the purified form as a condensate. Distillation is useful for separating a mixture when the components have different boiling points. Several kinds of distillation techniques for binary or multi-component mixtures are described and practiced in the art, for example: (1) simple, (2) vacuum or reduced pressure, (3) fractional and (4) steam distillation.

To produce rectified spirit from a fermented wash, the wash is distilled in the one or multiple distillation columns to produce a product with ethanol content of about 93% ABV. This spirit contains various congeners like fusel oils, higher alcohols, acids, etc which are carried over during the distillation process. The complete removal of water from ethanol gives anhydrous alcohol. To make anhydrous ethanol, the azeotrope of ethanol-water is broken to achieve the desired strength of more than 99% ABV by using one of the dehydration methods like: 1] molecular sieve dehydration, 2] azeotropic distillation, or 3] membrane dehydration.
During conventional distillation processes as described in the art, to remove the congeners several steps of distillation and re-distillation are disclosed. However, though these methods are effective in removing congeners they all lead to formation of many technical ethanol fractions [also call technical alcohol cuts] that contain in large amount the congeners present in ethanol and not desired in potable alcohol [also called high quality ethanol (HQE)] obtained at the end. These technical fractions may constitute about 10% of final potable alcohol production and have less economic value.
The main object of this invention is recovery of ethanol present in said technical alcohol fractions and recycling such ethanol in said conventional ethanol distillation process leading to improvement the final recovery of potable ethanol and substantial reductions in by-products like various technical alcohol cuts [fractions with unwanted congeners].
BRIEF DESCRIPTION OF THE DRAWINGS
Particular examples of methods in accordance with this invention will now be described with reference to accompanying drawings, in which:

FIGURE 1 is a block diagram of the mass flow in the disclosed process. A fermented wash is fed to a distillation unit to recover ethanol [potable alcohol - HQE], during this process various technical grade alcohol fractions [cuts] are formed having higher amounts of various congeners. These cuts are collected and then dehydrated in a dehydration unit to remove any water present to get an anhydrous stream. Then said anhydrous stream is fed to a series of a high boiler column and a low boiler column. These columns remove the high boiling congeners [low feints] and low boiling congeners [high feints], respectively, from said anhydrous stream neutral spirit of desired quality, which is recycled in said distillation unit or optionally used as such [HQE].
FIGURE 2 is an exemplary setup of the apparatus of the invention showing several features that control the process of distillation of ethanol from a fermented wash, separation of technical grade fractions and anhydrous distillation of various technical grade fractions to obtain ethanol for recycling or for use as such. The whole.system may be divided into five units, namely: 1] existing distillation unit, 2] collection unit for technical grade fractions, 3] dehydration unit, 4] high boiler distillation unit, and 5] low boiler distillation unit. It also depicts the efficient energy utilization achieved by heat integrations in subsequent steps. The unused energy left in the form of vapours from said dehydration unit is integrated to run said high boiler column unit. Further, the unused energy left in the form of vapours from said high boiler distillation unit is integrated with said low boiler distillation unit.
DETAILED DESCRIPTION OF THE INVENTION
In one embodiment of the present invention, fermented wash is subjected to existing alcohol distillation plant and said plant not producing any anhydrous ethanol in its setup. During the process of potable alcohol or

high quality ethanol [HQE] production, about 7% of the total ethanol produced forms the various technical cuts. Technical cut is an waste alcohol obtained in a distillation step that contains high amounts of congeners, which removed from the fermented wash to get said potable alcohol. These technical cuts are either used as solvent or burnt as fuel with not added economic value. However, if recovered may lead to overall increase in the production of potable ethanol. The separation of congeners from hydrous alcohol is difficult due to azeotropic nature of the mixture. Normally technical cuts consist of about 7 - 10 % water by volume. The level of various congeners is also high as depicted in Example 2. However, removing these congeners become easy if anhydrous conditions are created. If water is completely removed from technical cuts, then it is subject to high boiler and low boiler distillations, the congeners are easily removed to high degree leading to formation of HQE or ethanol for recycling that can be further treated in said existing ethanol plant to increase the recovery of the potable alcohol or ethanol. .
In another embodiment, all technical cuts are collected to form a technical ethanol fraction; this is then subjected to dehydration to remove water forming an anhydrous stream. This anhydrous stream is then further subjected to high boiler separation and low boiler separation removes the feints containing the most of congeners, leading to formation of ethanol for recycling to the existing distillation process to increase the recovery of the HQE or optionally using it as HQE as such, as depicted in FIGURE 1. The dehydration is achieved using one or more of methods like: 1] molecular sieve dehydration, 2] azeotropic distillation, or 3] membrane dehydration.
- In further embodiment of the disclosed invention as illustrated in FIGURE 2, according to said process a fermented wash (11) is fed to a main distillation plant (1), wherein the main product potable ethanol or high quality ethanol is obtained (12) with desired profile of congeners. This processing also generates various types of technical cuts that collectively form a technical

ethanol fraction (13), which is collected in a tank (2) and then fed a dehydration unit (3). In said dehydration unit complete water removal is achieve leading to the formation of an anhydrous stream (14). Next, said anhydrous stream (14) is subjected to a high boiler distillation column (5) to remove all the congeners having boiling points greater than ethanol leading to the formation of a first distilled stream (15), the removed congeners are collected are low feints. Next, said first distilled stream (15) is subjected to a low boiler distillation column (6) to remove all the congeners having boiling points lower than ethanol leading to the formation of ethanol for recycling (17), the removed congeners are collected are high feints. Optionally, depending upon the profile of congeners said ethanol for recycling (17) is used as such as HQE (18) or send to main distillation plant (1) to be processed to obtain potable ethanol (12).
Examples provided below give wider utility of the invention without any limitations as to the variations that may be appreciated by a person skilled in the art. A non-limiting summary of various embodiments is given in the examples and tables, which demonstrate the advantageous and novel aspects of the process disclosed herein. Particular examples of processes in accordance with this invention will now be described with reference to the accompanying drawings
EXAMPLE 1
In one example of the present invention an ethanol distillation plant for about 100 KLPD of potable ethanol was operated. During the process to obtain potable ethanol [HQE], about 5% to 7% by volume of various technical cuts are formed depending upon the congeners profile required in the final high quality ethanol. Here operating a 100 KLPD setup generated about 6.5 KLPD of technical ethanol fraction. This fraction contained about 93% ethanol by volume with most of the congeners accumulating at less than 1% amount and rest being water. Removing these congeners from

this fraction without removing water was difficult due to the changes in physical properties of congeners in the presence of water. To overcome this problem said technical ethanol fraction was subjected to a dehydration process to remove water completely using a molecular sieve dehydration apparatus. Then the anhydrous stream so obtained was subject to a series of distilling units in which in first instance high boiling congeners were removed from said stream using a high boiler distillation column. At second instance low boiling congeners were removed from said stream using a low boiler distillation column. This processing afforded about 5.5 KLPD of about 99% dehydrated ethanol with negligible amount of congeners. This ethanol was recycled to the main ethanol distillation plant that used fermented wash to achieve the volumetric increase in the potable ethanol produced in that plant. This recovery and recycling of ethanol from technical cuts afforded about 5% increase in the final potable ethanol production in said main ethanol distillation plant.
EXAMPLE 2
By the process of present invention, different types and grades of technical ethanol cuts were collected giving technical ethanol fraction, which was converted to HQE or recycled. A typical chemical composition of said technical ethanol fraction and ethanol for recycling obtained are listed in the table below. The amounts of different congeners is given in parts'per million by volume or not detected. The method of analysis was: gas-chromatographic detection against a standard test sample prepared using known amounts of different congener components. After the treatment of technical ethanol fraction with the disclosed process, most of the congeners were not detected in said ethanol for recycling or HQE recovered from the system.

No Congener [in PPM] Technical Ethanol Fraction Ethanol For Recycling
1 Acetaldehyde ND ND
2 Acetone 1.53 ND
3 Methyl acetate ND ND
4 Ethyl acetate 265 ND
5 Methanol 74 ND
6 2-Butanol ND ND
7 n-Propanol 663 0.9
8 Iso-butanol 356 ND
9 Iso-amyl alcohol 1185 0.9
10 n-Amyl Alcohol 0.5 ND
11 Acetic acid ND ND
12 Furfural ND ND
13 Diacetal 0.65 ND
14 2,3 Pentanedione 0.069 ND
15 Acetal 3.79 ND
16 Isopropanol 0.74 0.33
While the invention has been particularly shown and described with reference to embodiments and examples, it will be appreciated that several of the above disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Also that various presently unforeseen and unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims. Although the invention has been described with reference to specific preferred embodiments, it is not intended to be limited thereto, rather those having ordinary skill in the art will recognize that variations and modifications may be made therein which are within the frame of invention and within the scope of claims.

5. CLAIMS
WE CLAIM:
A process for the improved recovery of potable alcohol comprising:
(a) collecting technical ethanol fractions generated in an ethanol distillation process forming a first stream;
(b) dehydrating said first stream to obtain an anhydrous stream;
(c) separating high boiling impurities present in said anhydrous stream to obtain a first distilled stream;
(d) separating low boiling impurities present in said first distilled stream to obtain a second distilled stream; and
(e) integrating said second distilled stream in said ethanol distillation process to increase overall recovery of potable alcohol.

2. The method of claim 1, wherein said first stream comprises at least 90% ethanol by volume.
3. The method of claim 1, wherein said anhydrous stream comprises at least 99% ethanol by volume.
4. The method of claim 1, wherein said high boiling impurities present in said anhydrous stream are separated with efficiency of at least 99% of initial amount of impurities .
5. The method of claim 1, wherein said low boiling impurities present in said first distilled stream are separated with efficiency of at least 99% of initial amount of impurities.

6. The method of claim 1, wherein said dehydration of said first stream is achieved by means of a membrane, molecular sieve, azeotropic distillation or adsorption separation of water or a combination thereof.
7. The method of claim 1, wherein said overall recovery of potable alcohol is increase by at least 4% ethanol by volume.
8. An apparatus for improving the recovery of ethanol in a potable alcohol distillation plant comprising:

(a) a provision for collection of technical ethanol fractions generated at different steps in a process for distillation of ethanol forming a first stream;
(b) a provision for dehydrating said first stream in a dehydration unit forming an anhydrous stream;
(c) a provision for separating high boiling impurities present in said anhydrous stream using a high boiler column forming a first distilled stream;
(d) a provision for separating low boiling impurities present in said first distilled stream using a low boiler column forming a second distilled stream; and
(e) a provision for integrating said second distilled stream with said process for distillation of ethanol to increase the overall recovery of potable alcohol.

9. The apparatus of claim 8, wherein heat left unused in said dehydration unit is supplied to said high boiler column or said low boiler column.
10. The apparatus of claim 8, wherein heat left unused in said high boiler column is supplied to said low boiler column.

11. The apparatus of claim 8, wherein said high boiler column removes impurities with efficiency of at least 99%.
12. The apparatus of claim 8, wherein said low boiler column removes impurities with efficiency of at least 99%.
13. The apparatus of claim 8, wherein said dehydration unit is one or more of a membrane separation unit, a molecular sieve unit, an adsorption unit or an azeotropic distillation unit.
14. An apparatus for improving the recovery of ethanol in a potable alcohol distillation plant according to FIGURE 2.