Bioethanol, alcohol plants

The production of ethyl alcohol (ethanol) is an important component in global industrial production. Produced from any raw material that contains polysaccharides, disaccharides and monosaccharides. Ethanol is divided into types depending on the final purpose of further use: rectified, dehydrated, raw alcohol, distillates. Rectified ethanol is used for the production of alcoholic beverages (vodka, tinctures), pharmaceuticals, perfumes. Dehydrated alcohol is used mainly for fuel production (E5-E85). Raw alcohol and distillates are used for the production of whiskey, cognac, brandy, cognac, tequila, rum, etc. The quality of ethanol (concentration of impurities and organoleptic assessment) is regulated by the relevant regulations (EN, GOST, DSTU, etc.)

The following is an example of technology for the production of ethanol from starch-containing raw materials.

Acceptance and preparation of grain for processing

The grain is taken to the unloading device. All raw materials that enter the enterprise are cleaned from organic and mineral impurities. This process is carried out on grain cleaning machines of various types.

Grain grinding

The efficiency of raw material processing during hydro-enzymatic processing depends on the degree of its destruction. For grain grinding, we recommend using devices (crushers) that guarantee 96...98% grinding — passage through a sieve with a hole diameter of 1 mm.

Preparing of the batch

This operation is performed by mixing the resulting grinding with water in a special device that is installed directly above the collector for preparing the batch. In this collection there is an active stirring of the medium by means of a stirring device (stirrer) of various designs and configurations. The mixing temperature is maintained by using distillery dreg filtrate and/or hot water for its preparation. At this stage, the process of swelling of starch grains and rarefaction of raw starch begins due to the action of a diluting enzyme preparation — alpha-amylase, containing a thermally stable α-amylase.

Hydrodynamic and enzymatic treatment of the batch

The main process of decomposition and dextrinization of starch is carried out in two sequentially connected devices equipped with devices for mixing. The temperature mode of the batch processing at this stage is maintained automatically by supplying steam to the bubbler of the hydro-dynamic treatment apparatus No. 1. From the hydro-dynamic treatment apparatus No. 1 unit, the wort enters the hydro-dynamic treatment apparatus No. 2 through an overflow pipeline and then into the fermentation department.

Yeast generation

This process consists of two stages:

  • breeding of pure culture (dry) yeast (laboratory stage);
  • the growing production of yeast

It is also possible to use dry yeast directly in the fermentation process.
The cultivation of production microorganisms lasts until the product accumulates in them in the range of 3.0-4.5% vol., which corresponds to the apparent density of production microorganisms-2/3-1/2 of the initial concentration of dry substances in the syrup.
Mixing the medium in production machines during growing - reduces the duration of the process by almost half.
Sowing, and the remaining volume is transferred to fermentation.

Fermentation

The main producers of alcohol in the processing of starch-containing raw materials are microorganisms Sacharomyces cerevisiae. For the cultivation of industrial microorganisms, a cooled boiled mass is used after hydrodynamic enzymatic treatment, an enzyme preparation of glucoamylase action is added.

Fermentation involves the process of accumulation of alcohol in the brew in special devices (fermenters) and is implemented in a battery of fermenters of periodic or continuous action.

Duration of fermentation depends on the method of its implementation, the type and quality of raw materials, concentration of wort, temperature, dosing enzyme and is 48...72 hours.

Distillation and rectification

After heating the brew in the brew heater and separating the carbon dioxide in the CO2 separator, the brew is sent to the feeding plate of the brew (distillation) column, then to the mash column.

In the mash column, the volatile part of the brew is separated from the non-volatile part. The brew, freed from the volatile part, is output from the lower part of the mash column in the form of the DDGS. It removes extractive substances, suspended, a significant amount of water and residual impurities. The volatile part of the brew containing ethyl alcohol, water, and accompanying volatile impurities, in the form of a brew distillate, is sent to the feeding tray of the epureation (hydroselection) column, then-EC.

In the Epuration Column, the main impurities are isolated in the form of the main fraction of ethyl alcohol and the epurate is removed from the lower part, which is fed to the feed plate of the rectification column, then to the RC.

In the Rectification Column, further purification occurs with the release of main and end impurities — in the form of unpasteurized alcohol, and intermediate impurities — in the form of fusel oil and strengthening (concentration) of ethanol to normalized values.. Luther water enriched with residual impurities is extracted from the lower part of the rectification column, and rectified alcohol is taken from the upper part

To obtain high-quality alcohol ("Lux"), rectified alcohol is sent to the final purification column's feed plate (methanol)– further to the column of final treatment. The final purification of alcohol from terminal impurities in the form of unpasteurized alcohol and neuter impurities in the form of part of the alcohol taken from the cube of the final treatment column, whereas this process is going. Rectified alcohol is taken from the upper part of the column of final treatment.

To increase the yield of alcohol, relative to the theoretical, the fusel fraction, the general fraction of ethyl alcohol , unpasteurized alcohol is sent to the collection and then to the feeding plate of the acceleration column-then to the accelerating column.

In the accelerating column, alcohol is extracted from a mixture of the fusel fraction and the general fraction of ethyl alcohol and the impurities are concentrated in the form of fusel-ether-aldehyde concentrate. Cubic residue of accelerating column (alcohol content 6 ... 12% vol.) are sent to the mash column.

Dehydration

To obtain dehydrated ethanol, the process of adsorption on molecular sieves is used. Raw alcohol is sent in turn to special containers filled with a special packing. Passing through the packing layer, ethanol is released from moisture and the final water content is reduced to 0.05% vol.

Membrane treatment of dried distillery dreg with solubles (DDGS)

All the distillery dreg from the mash column is successively sent to:

  • decanter installation, where it is divided into distillery dreg filtrate and cake
  • membrane unit where yeast-protein concentrate is extracted from the distillery dreg filtrate

Separated cake and yeast-protein concentrate are mixed with the preparation of protein-vitamin concentrate.
Protein-vitamin concentrate is then dried and sent to the warehouse in a dry form and sold, and the purified filtrate of bard after pH correction is used to prepare the batch.

Protein-vitamin concentrate drying

To dry protein-vitamin concentrate, use an air-drying unit that uses hot steam, natural gas, or solid fuel as a heat carrier.