RU2130482C1 - Method of treating aqueous ethanol solutions - Google Patents

Abstract

FIELD: alcoholic beverage industry. SUBSTANCE: method comprises passing air through solution and previously adding ozone to air. Treatment is carried out at 20-70 C till 15 to 200 mg of ozone are absorbed per 1 cubic dm of aqueous ethanol solution. EFFECT: improved quality of the product to be treated. 10 ex

Description

 The invention relates to the alcohol and alcoholic beverage industries and can be used at the stages of producing rectified food alcohol, as well as for processing sortings in vodka production.

 Almost all existing industrial technologies for the production of drinking ethyl alcohol include three main stages: distillation of the mash, distillation separation from the macerated distillate of the etheroaldehyde fraction (EAF) containing not less than 92% vol. Alcohol and epuret with a strength of 30-40% vol. other impurities by distillation. Sometimes additional purification is performed in the final columns using rectification techniques.

 Sorting processing is carried out mainly by adsorption methods using activated carbon (BAU) and other sorbents (for example, silica sand, zeolites, etc.).

 In the process of fermentation of the feedstock (especially low-quality), in addition to ethanol, a number of impurities are formed: other alcohols, aldehydes, ketones, acids, ethers and esters. Some of them (for example, acrolein, isobutyric and isovalerian esters) form complex azeotropic mixtures with ethanol and water, which greatly complicate its purification by rectification methods. So, if there are a lot of esters in the distillate, it is not possible to separate them in the epilation column.

 In industry, the task of improving the quality of rectified products is solved by increasing the number of columns, improving their design, optimizing temperature conditions and flow directions, etc. However, the use of these techniques is associated with a change in existing technology, requires significant costs and does not always lead to the desired effect.

 A known method of heat treatment of rectified in the liquid phase at elevated pressure (Ternovsky NS "Fermentation and alcohol industry" 1965, N 2). The method is time-consuming and, despite the positive results of semi-industrial tests, has not found practical application.

 There is also an oxidative method for purifying alcohol using solutions of alkali and potassium permanganate (ed. Certificate SU 412251, 1972), which consists in first breaking down or binding esters, acids, aldehyde-sulfur compounds and amines with alkali, and then oxidizing them in a strengthening column potassium permanganate unsaturated some sulfur compounds and aldehydes. The disadvantages of this method are the use of expensive auxiliary reagents and the need for disposal of manganese waste.

 A known method of cleaning sorts using ionized air, leading to an improvement in the organoleptic qualities of vodka. According to one of the options (SU 364667, 1973), a water-alcohol solution is first sprayed to an aerosol state and in countercurrent contact is made with ionized air. The aqueous-alcoholic solution at normal temperature is continuously supplied to the upper part of the sealed tank under an overpressure of about 0.5 atm and is sprayed, for example, by means of a nozzle to an aerosol state. Towards the stream of aerosol moving gravitationally from top to bottom, a stream of ionized air is directed, which is supplied by the fan to the lower part of the tank at the rate of 8-10 vol. air on 1 about. the processed solution. The aerosol is again transferred to the liquid state on the nozzles in the tank, which provide the development of the phase-contact surface. The treated solution from the bottom of the tank is diverted to subsequent technological operations. The reacted air is removed from the upper part of the tank, cleaned of alcohol and other volatile substances, and then sent for recycling in a closed loop.

 Closest to the proposed method for cleaning water-alcohol mixtures is a method for processing sortings by passing ionized air directly through a water-alcohol solution (SU 181592, 1966). Ionized air is supplied using a blower-compressor or a high-pressure fan through a gas meter and a bubbler into a sorting tank filled with an aqueous-alcohol solution. As a result of the passage of ionized air through a layer of an aqueous-alcoholic solution, the entire sorting mass is thoroughly mixed; the oxidizability of the sample (Lang test) increases by 2-7 minutes depending on the processing time and the amount of ionized air. The organoleptic qualities of the solution increase from 8.3 to 9 points. The alcohol vapors carried away by air are captured by known methods, and the processed sorting is sent to pressure vessels for subsequent operations.

 The disadvantage of this processing is the complexity of the technological implementation of the method. Reactive particles formed during ionization of the air are extremely unstable, and when the air stream is transported through the pipeline to the reactor, their activity drops sharply. This limits the scope of the method only to processing sortings containing trace elements by-products.

The present invention provides a technologically simple and effective way to improve the quality of water-alcohol mixtures of various compositions. In the process of processing the initial aqueous solution of ethanol (distillate distillate, epureate, sorting, an aqueous solution of the ether-aldehyde fraction, etc.) with an ozone-air stream, a decrease in the concentration of a number of organic impurities (aldehydes, ethers and esters) occurs. The use of ozone as a component of the gas stream passed through the solution dramatically increases the efficiency of the method and provides the required degree of purification of water-alcohol mixtures in a wide concentration range of impurities: from mg / l to tens of g / l. Processing is carried out mainly at temperatures of 20 - 60 ^o C, although ozone even at room temperature is able to interact with many organic compounds, including ordinary impurities formed in the alcohol industry. According to their physical properties, volatility, solubility in water, and others, the reaction products are more different from ethanol than the initial impurities, which makes it possible to more effectively remove them from a water-alcohol solution. The quality of processing depends on the amount of absorbed ozone, which for almost all aqueous solutions of alcohol found in production is in the range from 15 mg / l to 200 mg / l.

 The inventive method allows to practically quantitatively remove from water-alcohol mixtures such most undesirable impurities as crotonic aldehyde, acrolein and diacetyl, which worsen organoleptic and oxidation test results of vodka products. In addition, the oxidation of aldehydes to the corresponding acids can be carried out by adjusting the degree of this reaction. The latter is important, since aldehydes, when abundant, give alcohol a sharp burning taste and an acute unpleasant odor, but they are involved in small quantities in the formation of a bouquet of some finished products. The resulting fatty acids are typical tailings and at the final stage of rectification are easily removed with luther water. By varying the initial processing parameters, it is possible to almost completely eliminate the oxidation of ethanol by ozone and significantly reduce the concentration of all esters in the treated water-alcohol mixture (by 70 - 90%), and this applies not only to low-boiling (ethyl acetate), but also to high-boiling (butyl acetate) impurities.

Studies of the influence of the process parameters of purging water-alcohol mixtures with an ozone-air gas stream were carried out in glass and metal using a periodic thermostatically controlled bubbler reactor. As raw materials used model water-alcohol mixtures with a known content of the impurity component and real intermediate alcohol fractions obtained from various industries. Air flow was measured by a differential pressure gauge. The power of the ozonatra used is 3 g of ozone / h. The results of the analysis of the initial and final products were carried out according to titration methods approved by GOST for this industry for the content of alcohol, aldehydes, acids and ethers, and were confirmed in parallel with the known methods of gas-liquid chromatography on a Chrom-5 device. In each case, the effect of changes in the qualitative and quantitative composition of the initial mixture, as well as the conditions of ozonation: the time (or specific consumption of ozone) in the range from 5 to 30 minutes, the temperature from 20 to 70 ^o C and the feed rate of the ozone-air mixture from 1.7 to 5.1 l / min.

 Examples 1, 2, 3 show the results of processing industrial intermediate alcohol fractions. Examples 1 to 6 are given at the end of the description.

 The use of the proposed method for the purification of practically anhydrous alcohol does not lead to a positive effect, there is even an increase in the concentration of undesirable impurities (example 4).

 Example 7

When adding cretonic aldehyde (KA) to a 40% (wt.) Solution of ethanol in water (sample volume 40 ml, time 20 min, ozone-air mixture consumption 3.4 l / min; T 50 ^o C) regardless of the initial concentration of KA (changed in the range of 0.2-1.4 g / l) almost its complete removal from the solution was obtained. The final concentration did not exceed 3.1 • 10 ^-3 mol / L.

 Example 8

 Under conditions of experiment 7, similar results were obtained for the addition of acrolein.

 Example 9

Sorting of the following composition (in terms of alcohol) was used as a feedstock: oxidation test at 20 ^° C for 14 min. Concentration of aldehydes in terms of acetic 6 mg / l, ethers in terms of ethyl acetate 81 mg / l, acids 16 mg / l After treatment with an ozone-air stream at room temperature for 15 minutes (ozonizer capacity 1.1 g / h, flow rate 2.4 l / min). The above indicators became respectively 22 min, 2 mg / l, 23 mg / l and 11 mg / l, which, according to GOST 5962-67, corresponds to the class "extra". The bitter, astringent and sour-ethereal tones completely disappeared.

 Example 10

Synthetic ethanol with an alcohol content of 92% (everywhere percent by volume), with a concentration of oxidizing (in terms of isopropyl alcohol) 0.2%, aldehydes 1.1%, diethyl ether 1%, esters 280 mg / l and sulfur dioxide 3 mg / l was diluted with water to a concentration of 45% and treated with an ozone stream at T 50 ^o C for 15 minutes (sample volume 75 ml, ozonizer capacity 3 g / h). As a result, the following product was obtained (data are calculated in terms of alcohol), ethanol content 95%, oxidation test 46 min, concentration of esters 32 mg / l, diethyl ether 0.1%, aldehydes 0.2%, esters 32 mg / l no sulfur.

 To clean the sortings, according to example 9, it is possible to use periodic and continuous methods, but in both cases the ozone stream must be in contact with the liquid phase, without spraying the latter. For the continuous version, a column type apparatus can be used. You can use nozzles, plates, mixers and other equipment that increases the efficiency of mass transfer.

 Similarly, processing of EAF can be carried out. The amount of the etheroaldehyde fraction at each plant is on average 3–4 wt.% Of the resulting product. Processing EAF according to the present method allows under mild conditions to obtain an aqueous solution of alcohol, in all respects superior, for example, macerated distillate. The latter makes it possible to return 95% of EAF alcohol back to the cleaning process, that is, to make the process virtually waste-free.

 The inventive method can be used in the processing of sorts; at the stage of recuperative processing of EAF, in order to return the main amount of the etheroaldehyde fraction (up to 95%) to the production of rectification, as well as on the supply lines of distillate and / or epureate. The latter, simultaneously with improving the quality of the target product, will increase its yield by reducing the quantitative losses of alcohol with head and still fractions of both columns.

 It is possible to completely replace the epilation column with an apparatus operating according to the claimed method.

Claims (1)

A method of treating aqueous ethanol solutions, comprising passing through an air solution into which ozone is added before passing it, characterized in that the treatment is carried out at 20 ^° -70 ^° C. until 15 to 200 mg of ozone is absorbed per 1 dm ^{3 of an} aqueous ethanol solution.

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