General production technology of BIOETHANOL

The destination and source data

This technical and commercial offer (hereinafter referred to as the TCP) for the supply of ethanol production technology from grain raw materials was developed by BTS-ENGINEERING, LLC "BIOTECHSOYUZ" FOR:

  • familiarizing potential partners with their capabilities and approaches to the supply of technologies for the production of ethanol from grain raw materials;
  • assessment of the feasibility of implementing a project at a specific site for the production of ethanol from grain raw materials;
  • assessment of the possibility of producing livestock feed using ethanol production waste;
  • introduction of potential partners with the possibility of "superstructure" of the technology of ethanol production from grain raw materials in the production of complex processing of grain raw materials.

Brief description of the technological process

According to preliminary agreements, the TCP is formulated for the following conditions:

  • raw materials for the production of ethanol-grain corn that meets the requirements of the "Special conditions for the supply of bread products", approved by the decree of the state Arbitration of the USSR of 16.01.75, No. 102, the alcohol industry enterprises are supplied primarily with grain that is unsuitable for food and feed purposes, with the following characteristics:
    (1A) bulk density, g/l-680 ... 820;
    (1b) humidity, % - 13 ... 14;
    (1C) the content of impurities in commercial grain, % - 1.0 ... 2.0;
  • the main commercial product is ethyl alcohol (dehydrated, rectified) for the purpose of its further use for the production of biofuels or alcoholic beverages. The total production capacity for the production of ethyl alcohol is 10,000 dal per day;
  • complete utilization of distillery dreg and complex processing of grain raw materials to obtain a line of commercial products used in feed production and food production;
  • complete filtering of technical flows to return to the process.

The General technology of production

TCP offers a well-known technology for processing starch-containing grain raw materials into ethanol.

The proposed technology consists of the following elements of novelty:

  • complex processing of grain raw materials;
  • use of hydro-enzymatic technology for starch degradation;
  • use of column apparatuses operating under excessive pressure and under vacuum for distilling and rectification of alcohol brew;
  • use of membrane technology for ethanol dehydration;
  • use of membrane technology for thickening the separation products of distillery stillage;
  • use of membrane technology for filtering technical flows;
  • automatic production control and management system at all stages of production of all commodity products.

Utilization of fermentation gases is not considered due to the high energy intensity, but can be developed in detail if there is an interest of potential investors in the production of carbon dioxide at the subsequent stages of the project.

The technology of complex processing of grain raw materials is given only descriptively, but can be developed in detail if there is an interest of potential investors in the production of a line of food products and feed at the subsequent stages of the project.

Department 01-receiving department of grain from motor transport.
Department 02-grain warehouse with a part-time department

Department 01-receiving Department of grain from motor transport is used for receiving, weighing grain and transferring it to Department 02-grain warehouse with a part-time Department.
The hourly productivity of the equipment of Department 01 should ensure the acceptance of the required amount of grain, taking into account the coefficients of hourly and daily unevenness, and be AT LEAST 10.0 ... 15.0 tons, and Department 02 – cleaning and processing/drying of grain and its storage for 3 ... 12 months, depending on local conditions.
Car dumpers are used for unloading on-Board vehicles. Grain is unloaded from dump trucks by gravity to the receiving bins.
All grain arriving at the plant with more than normalized contamination should be cleaned on grain cleaning machines to the conditions that meet the intended purpose.
Grain is distributed to warehouses STRICTLY according to crops and quality characteristics.
The capacity of an Elevator or warehouse for floor storage of grain should be at LEAST 1.5 ... 2.0 thousand tons.

Department 03-grain processing Department

The main purpose of Department 03 is grain sub-processing:

  • storage of a 3-day supply of grain, which allows you to create a stock of grain for the weekend;
  • crushing of grain to form flour;
  • preparation of the batch.

Before entering the grain for cooking, it goes through the following part-time work: separation of metal impurities on a magnetic separator, weighing, and two-stage crushing.
To prepare the batch, flour with a degree of grinding OF at LEAST 98 ... 99% (passing through a sieve with round holes Ø1mm) is mixed with artesian water, permeate for microfiltration separation and thickening, as well as residue water filtrate. In the container for preparing the batch, enzyme preparations are set that destroy starch to dextrins.

The use of permeate and filtrate solves the following main problems:

  • reducing the intake of artesian water for technological needs;
  • elimination of permanent technological discharges into the sewer;
  • reduction of process heat consumption.

Department 04-Department of fermentation splitting of grain starch

The batch is pumped from the 03 Department to the 04 Department, where the batch is diluted with the formation of dextrins in the hydro-fermentation treatment apparatus (GDF) under the action of heat and enzyme preparations, both introduced into the batch and additionally introduced into the GDF. The resulting technological product is called wort.
The finished wort is sent for fermentation (alcoholic fermentation) in Department 05-yeast fermentation Department, part of the wort is sent for the cultivation of industrial yeast.

Department 05-yeast-fermentation Department

In the yeast-fermentation Department, an alcoholic mash is formed during the fermentation of the wort. The scheme of continuous-flow fermentation in a battery of 10 fermenters was adopted. Mature alcohol brew is transferred to the transfer fermenter, and then in distillation and rectification unit for the separation of formed in the fermentation process of ethanol and impurities.

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Department 06-yeast-fermentation Department

The process of ethanol separation( distillation), strengthening and purification of ethanol from impurities (epyuratsiy, rectification) is implemented on column apparatuses equipped with heat exchangers (dephlegmators, condensers). Column devices can operate under atmospheric pressure, as well as under excessive pressure or vacuum, which guarantees the most complete heat recovery of water-alcohol vapors.

At the exit of the Department, a line of commodity products is formed:

  • ethyl alcohol, rectified with a strength of 96.3% vol.;
  • fusel oil;
  • HFEA (head fraction of ethyl alcohol)

Main waste of the Department:

  • distillery stilage;
  • residue water.

Ethanol obtained in the Department 06 through the technological metering device is transferred either to the sprirtopriemnoe Department (Department 07), or bypassing the alcohol intake Department for dehydration (Department 09). The distillery dreg is sent to Department 10 for processing.

Department 07-alcohol intake Department

Rectified ethanol, fusel oil (CM) and FSES are delivered to the alcohol receiving Department (No. 07), where they are recorded and transferred to the alcohol storage (Department 08). From the alcohol storage, ethanol, SM AND FGPP are released to consumers.

Department 08-alcohol storage

Alcohol storage is a series of containers that store alcohol-containing products. The storage capacity for storage of rectified ethanol is recommended to take no more than 2000 m3, which ensures the storage of the product, with the passport production capacity, for 15 ... 250 days, depending on the type of product. The total volume of the factory warehouse of alcohol according to the requirements of VNTP 34-93 should not exceed 2000 m3, which is due to the high fire hazard of products.

Department 09-ethanol dehydration Department

The purpose of ethanol dehydration/absolutization is to produce ethanol with a strength of at least 99% by volume. The description of the dehydration/absolutization technology should be discussed in more detail. Currently, three technologies are most widely used on an industrial scale:

  • dehydration / absolutization using solid regenerated sorbents, such as silica gel or zeolites;
  • rectification of the triple mixture-ethanol-water-benzene;
  • separation of water-alcohol vapors on "molecular sieve" type membranes.

Dehydration / absolutization using solid regenerated sorbents

The dehydration process is carried out in a group of column devices – absorbers loaded with a water-absorbing sorbent. Periodically, each absorber is removed for regeneration. In the case of silica gel, regeneration is performed by purging the device with dried steam.

Dehydration/absolutization by rectification of an azeotropic three-component mixture

The technology of dehydration / absolutization is based on the phenomenon of formation of an azeotropic mixture of benzene-water-ethanol. This mixture has the lowest (64.9 oC) boiling point of the benzene-ethanol, ethanol-water, and benzene-water mixtures. During rectification, the three-component mixture evaporates and is removed from the rectification/absolutizing column, and the component with the highest boiling point - absolutized ethanol-remains in the cubic part of the column.

Dehydration/absolutization using membranes

The technology is based on the difference in the size of water and ethanol molecules. When a steam water-alcohol stream passes through the membrane, it passes into the transmembrane space water molecules that have smaller sizes in comparison with ethanol molecules, and ethanol molecules accumulate in front of the membrane. The process of separation and thickening is carried out in a steam stream. After thickening, the separated components condense.
The choice of dehydration/absolutization technology will be made based on a technical and economic comparison of options at the subsequent stages of the project. It should be noted only the increased environmental hazard of the dehydration/absolutization option with the rectification of an azeotropic three-component mixture associated with the use of benzene, which has toxic, carcinogenic properties and a high fire hazard, even in comparison with ethanol. The technology of dehydration/absolutization using solid regenerated sorbents is characterized by high energy consumption, and dehydration/absolutization using membranes is characterized by high cost.
The most" clean " is the use of membranes.
It should be noted that in any of the technologies under consideration, the selection of ethanol for dehydration / absolutization is performed from Department 06, bypassing Department 07. This is done in order to use the heat of rectified ethanol, since all the processes of dehydration/absolutization are carried out at high temperatures of water-alcohol solutions and vapors.
The dehydrated / absolutized ethanol is cooled and sent through compartment 07 to compartment 08.

Department 10- distillery dreg recycling Department

Distillery dreg contains about 6-9% of dry substances, which include: raw protein, nitrogen-free extractives, fat, fiber, ash, vitamins and trace elements. It is not always rational to use distillery dreg in liquid form due to storage problems, since the proteins that are included in its composition begin to decompose in a day and it is not economically profitable if its transportation distance is more than 5 ... 7 km.
In order to fully use distillery dreg as a highly nutritious feed, we offer its multi-stage processing to produce a whole line of commercial products used as feed for farm animals and additives to concentrated feeds.
Additionally, the implementation of the proposed technology allows you to return the liquid phase of distillery dreg and residue water to production, which significantly reduces the intake of fresh artesian water for technological needs. In addition, an environmental problem is being solved in parallel-the protection of soils, surface and ground water from contamination by the products of distillery dreg decomposition, which is the case with the standard method of disposal of distillery dreg – its storage in a distillery dreg storage facility.
The proposed recycling technology is as follows.
Distillery dreg from Department 06 is cooled in recuperative heat exchangers that heat the process media and intermediates, then goes to the decanters, where it is divided into a solid fraction – cake (40% of absolutely dry substances) and a liquid fraction - Fugate (5% of absolutely dry substances). Cake can be sold as a commercial product, but it is more effective to dry it in order to obtain a protein-vitamin concentrate. To improve its quality as a commercial product, the Fugate is condensed at the microfiltration unit until another commercial product is obtained – a concentrate (22 ... 25% of absolutely dry substances). It is possible to sell the concentrate as an independent commercial product, but in order to improve the nutritional qualities of protein vitamin concentrate, the concentrate is mixed with cake and dried. Waste from the thickening of Fugate-permeate (1,0 ... 1,5% of absolutely dry substances) after correction of its physical and chemical composition is returned to the Department, where it is used for preparing the batch.
Residue water from Department 06 is cooled in recuperative heat exchangers by heating process media and intermediates, then purified on osmotic membranes and after correcting the composition of the filtrate is also used to prepare the batch. After osmotic membranes, the concentrate is mixed with the Fugate and is separated and condensed in a microfiltration unit.
In full, the proposed technology for recycling distillery dreg was launched at the bioethanol plant of AO "BIOFUTURE" ( Shilute, Republic Of Lithuania).

Department 11-Department of complex processing of grain raw materials

The proposal to organize a Department for complex processing of grain raw materials is an option that can be implemented in order to significantly improve the technical and economic indicators of the project. Part of the technology, on the scale of pilot production, was implemented by our permanent partner - OOO "ORGANIKA" (Ukraine, Ternopil region, Chortkov).

The Department operates on corn and produces:

  • (1) corn oil;
  • (2) corn groats;
  • (3) corn flour.

Corn flour serves as a raw material for the production of starch. In turn, starch serves as a raw material for the production of ethanol, modified starches, and high-sugar syrups. Modified starches can serve as raw materials for highly liquid products-biopolymers. Biopolymers are biodegradable polymer materials used for packaging, disposable tableware, etc.
The Department's waste products are used as feed fortifiers. According to estimates, the technology guarantees the USEFUL use of about 99% of the mass of raw materials.

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