RU2654590C2 - Process for producing alcohol by fermentation of sugars - Google Patents

Abstract

FIELD: biochemistry.

SUBSTANCE: invention relates to a method for increasing the yield of alcohol during fermentation of sugars. This method comprises preparing a treatable broth containing a solution of sugars, preparing a container for said treated broth containing at least 2 electrodes. Container is filled with said treated broth in a batch or continuous manner, connect the electrodes to a direct current source to orient the sugar molecules in said treated broth before inoculation of the yeast. Yeasts are inoculated. Throughout the process the pH of the resulting fermentation broth is monitored to maintain its value in the range of 6 to 4.5 when applying a constant electric field.

EFFECT: invention provides an increase in the yield of alcohol.

5 cl, 1 ex

Description

Technical field

The invention relates to a physicochemical method for improving the production of alcohol by fermentation of sugars, which includes the creation of polarization in the enzymatic broth using an electric field.

State of the art

Alcohols are a class of chemical compounds characterized in that they contain at least one hydroxyl group (OH) and are widely used in industry. The best known compound of this class is ethanol or ethyl alcohol. It is found in alcoholic beverages, cleaning products and pharmaceuticals, and it is widely used as a chemical solvent; it also finds use as a fuel for vehicles, which is currently its most valuable and widespread use.

The method for producing ethanol, as a rule, is based on the use of sugar cane as a raw material, but it can also be implemented using various grains and sources of sugar, such as corn, cassava, other root crops, sorghum, wheat, barley and molasses, syrup, cane sugar bagasse, potatoes, whey, etc.

Ethanol production is usually divided into 4 stages: grinding, liquefaction, fermentation and distillation. Grinding involves the processing of sugar-containing raw materials using special equipment. At this stage, a broth with a high content of water and sugars is obtained.

The fermentation step involves the addition of certain types of yeast, which cause the conversion of the sugars contained in the solution into ethanol. This transformation is due to the action of enzymes. As a result of this stage, fermented wort is obtained, part of the total volume of which has already undergone conversion to ethanol.

Then, the fermented wort is subjected to the last stage, fractional distillation, and a solution containing ethanol and water is obtained.

The stage that has the greatest influence on the result of ethanol production and, therefore, is the most studied, is fermentation, also known as alcohol fermentation, which is the chemical process of converting sugars, mainly sucrose, glucose and fructose, to ethanol. At this stage, microorganisms are used to ensure the conversion of sugars to ethanol.

Since this method is well known in the art, various documents can be found describing methods for carrying out the steps described above. In general, the methods are aimed at finding the ideal types of microorganisms or their combinations to produce ethanol, while the methods used are characterized by significant losses of raw materials (sugars), which leads to a decrease in the effectiveness of the methods.

Various documents relating to various methods for producing ethanol can be found in the patent literature. In US patent No. 4451566 Donald B. Spencer (Donald B. Spencer) describes methods and equipment for producing ethanol from fermentable sugars using enzymes. Enzymes in the sequence necessary for the conversion of sugars to ethanol are located in certain zones. A solution of fermentable sugar is sequentially passed through these zones and alcohol is isolated in the last zone. In addition to providing greater reaction efficiency compared to conventional methods, this document proposes a solution that is time-consuming, complex and difficult to maintain.

In international patent application No. WO 2007/064545, Brian Burmaster describes a method for increasing ethanol yield, reducing fermentation time and reducing the formation of by-products by observing and controlling the redox potential in the fermenter. However, this method requires specific monitoring equipment and is difficult to maintain, which makes the method expensive, albeit more efficient.

In international patent application No. WO 2008/024331, Vladimir Vlad describes a method of fermentation in a magnetic field, which includes exposing a biological material to a constant magnetic field to ferment a biological material to produce a fermented product. The fermentation reaction can be carried out in an alkaline or acidic environment, and the magnetic field can be positive or negative. This paper proposes the use of a magnetic field to provide more favorable conditions for the propagation of cells of microorganisms. In addition to increasing the number of microorganisms in the process of alcoholic fermentation and, consequently, increasing the yield of the reaction, the method according to this document requires constant monitoring and full control over the reaction, which makes the method expensive.

Given the limitations of the prior art, the inventors of the present invention have developed a method for producing alcohol by sugar fermentation, which has advantages such as increasing the efficiency of the method using constant electric polarization during fermentation.

SUMMARY OF THE INVENTION

Methods for producing alcohol by sugar fermentation are already known to those skilled in the art. However, all methods used to obtain alcohol by alcoholic fermentation either have significant drawbacks in terms of the output of the fermentation reaction, leading to the loss of raw materials (sugars), or require equipment or procedures with a high cost of implementation or maintenance. Thus, the object of the present invention is to provide an improved, inexpensive physico-chemical method for producing alcohol by fermentation of sugars, characterized by a high level of use of raw materials (sugars) and their by-products and, consequently, an increase in the yield of the fermentation reaction.

Fermentation methods have already been well studied and include the use of expensive materials. Thus, one of the objectives of the present invention is to provide a method that can be easily implemented in existing plants with greater efficiency of the sugar fermentation process.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a physicochemical method for increasing and improving the yield of alcohol by changing and improving the fermentation stage of solutions containing sugar. Such improvements include the application of a direct current electric field, causing dynamic polarization of sugars, as well as electrolysis of the wort, which actually proceeds from the water contained in the wort, which is almost completely acidified.

The application of an electric field to the processed broth (a solution containing sugar) leads to the polarization of the sugar molecules contained in the processed broth. The formation of such electric polarizations increases the selectivity of sugar molecules, which leads to an increase in the yield of the process.

To ensure the required effectiveness of such selectivity, the fermentation process should begin only after applying an electric field to the treated broth. Fermentation can begin after the electrical orientation of all the molecules.

The electrodes described in the present invention are devices made of a conductive metal.

The method described in the present invention includes the following steps:

1. Preparation of containers for the processed broth containing at least 2 electrodes;

2. Connection of electrodes to a direct current source;

3. Preparation of the broth for fermentation;

4. Filling the tank in a batch or continuous manner;

5. Connecting electrodes to orient sugar molecules;

In one aspect of the present invention, the equipment is provided with devices for controlling and maintaining fermentation parameters, such as voltage and current.

To evaluate the effectiveness of applying electric current to the fermentation broth, several tests were performed. One example of a process that does not limit the scope of legal protection of the present invention is given below.

An example of a method for producing ethanol by fermentation of sugars

The method described below includes not only the application of an electric field to the resulting broth, but also all stages of ethanol production from sugar cane.

We consider a modern enterprise with 12 (twelve) tanks of 300,000 liters each, where the indicated volume contains sugarcane mass, soaking water and all chemical reagents, the total content of which is up to 6 × 10 ^-4 kg / l, or 180 kg per tank 300,000 liters.

After fermentation and distillation, this enterprise receives from 9 to 10% ethanol per 300,000 liters in each tank, i.e. from 27,000 to 30,000 liters of ethanol per tank load.

An electric field of direct current was applied to the medium in each of the tanks, which led to the dynamic polarization of sucrose, as well as to the electrolysis of the wort, which actually flows due to water, which is almost completely acidified. During the course of such fermentation in combination with electrolysis, two types of gases were formed:

- gas generated during fermentation, which is carbon dioxide bubbles;

- gases formed during electrolysis, in an acidic environment, they are mainly in the form of ions, and there is also a small amount of other gases formed by chemical elements contained in the wort at very low concentrations.

This means that there is an increase in the volume of gases in the tanks for fermentation. The dynamic polarization of sugars, as well as an increase in the volume of gases and their reactivity, leads to the formation of ethanol and other compounds in increased amounts compared to traditional alcoholic fermentation.

To illustrate the present invention, the term TRS is used to mean “total reducing sugars”. The term BRIX is also used to refer to the sugar content on the Brix scale, the areometric scale for measuring the concentration of sugars in a particular solution at a particular temperature. These terms are already used in the state of the art and are understood by those skilled in the art.

The pH in the tanks at the beginning of fermentation was approximately 4.5. BRIX wort during fermentation ranged from 18 to 22 with an alcohol content of approximately 8%. When fermentation began, the total content of reducing sugars, TRS, together with the BRIX value decreased, their concentrations decreased, and the pH of the wort, which became more acidic, decreased to 3.5 with increasing temperature. The temperature of the wort should not increase, as this leads to the growth of microorganisms consuming part of the TRS involved in the process.

Anodes and cathodes

Anodes and cathodes are geometrically identical. They are tubes bent into a spiral, with sheets between the turns, the dimensions of which are approximately equal to the diameter of the tubes and which should be made of copper of 99.9% purity. They are made in sizes corresponding to the available tanks, reach 10 (ten) meters in diameter and hold 1000 m ^{3 of} wort.

The tube-shaped ANODES and CATHODS functions include:

- conducting a constant cathode and anode current;

- providing wort cooling by means of a flow of demineralized and deionized water in a closed loop, maintaining the temperature of the wort not higher than 35 ° C due to water in the tubes of the cathode and anode.

The shape of the spirals depends on the shape of the tank where at least one pair of anode-cathode should be located. These spirals are coated with an insulating material that prevents electrical contact between the spirals and the walls of the tanks. The polarity of the current circulating in these spirals can be changed to prevent deposition of anode deposits on the anodes. The distance between the anode and cathode depends on the current strength and voltage and automatically changes in accordance with changes in pH.

As the pH of the wort becomes acidic, an automatic suspension of lime or other alkalis is carried out.

Process Gases

The gas generated during fermentation is CO ₂ (or carbon dioxide), the formation of which decreases during the course of the fermentation process. The almost complete cessation of CO ₂ formation means that almost all of the sugar has undergone conversion and the wort is ready for distillation. Reactive gases are mainly in the form of ions, capable of participating in the formation of ethanol and other products. They take various forms and maintain a pH of about 4.5 and a temperature below 35 ° C, their concentration remaining almost unchanged throughout the fermentation process, even after the cessation of CO ₂ formation at the end of fermentation. Thus, part of the alcohol is continuously withdrawn in the form of steam. Said alcohol vapors are preferably condensed and isolated without passing through the distillation step of the final wort. It also allows you to capture almost all of the CO ₂ currently released into the atmosphere. Thus, the emission of CO ₂ into the atmosphere, which is approximately 1 cubic meter for every cubic meter of ethanol, is significantly reduced.

Dynamic polarization of sucrose

Since sucrose molecules undergo dynamic polarization, they are in an oriented position, which facilitates their conversion.

Process automation

When automating the process, the pH must be maintained at the most appropriate level at each stage of fermentation. Such control is carried out using pumps that dispense a solution of lime or its equivalent, since during the process, the remaining fermented wort is acidified. Due to pH changes during fermentation, changes in the density of electric current occur, which are measured and controlled by an appropriate system mainly in a batch process.

Specialists in this field it is clear that the method described in the present invention is not limited to the specific features of the process for producing ethanol and this method can be extended to all fermentation processes known in the prior art, which will ensure efficiency, speed of production and increase the yield of alcohol.

Claims (11)

1. A method of increasing the yield of alcohol during sugar fermentation, characterized in that the method includes the preparation of the processed broth containing a solution of sugars, preparing a container for said processed broth containing at least 2 electrodes, filling the tank with the specified processed broth in a batch or continuous manner, connecting the electrodes to a direct current source to orient the sugar molecules in the specified processed broth before inoculation of yeast, inoculation of yeast and monitoring the pH of the obtained enzymatic broth throughout the process to maintain its value in the range from 6 to 4.5 when a constant electric field is applied. 2. The method according to claim 1, characterized in that the temperature of the specified enzymatic broth is maintained in the range from 30 to 35 ° C. 3. The method according to claim 1, characterized in that the pH of the enzymatic broth is maintained at about 4.5. 4. The method according to claim 2, characterized in that it comprises continuously maintaining a pH of about 4.5 and a temperature in the range from 30 to 35 ° C. 5. The method according to claim 1, characterized in that the pH control system is provided using a pump for supplying alkaline material, such as lime water, and a measuring system for a batch process.