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Ethanol from sawdust. Production of ethyl alcohol from sawdust

Sawdust is a valuable raw material for the production of various alcohols that can be use as fuel.

Such biofuels can run:

automobile and motorcycle gasoline engines;
power generators;
household gasoline equipment.

Main problem one that has to be overcome in the manufacture of biofuels from sawdust is hydrolysis, that is, the conversion of cellulose into glucose.

Cellulose and glucose have the same basis - hydrocarbons. But for the transformation of one substance into another, various physical and chemical processes are necessary.

The main technologies for converting sawdust into glucose can be divided into two types:

industrial requiring sophisticated equipment and expensive ingredients;
homemade that do not require any sophisticated equipment.

Regardless of the method of hydrolysis, sawdust must be crushed as much as possible. For this, various crushers are used.

How smaller size sawdust, topics more efficient there will be a decomposition of wood into sugar and other components.

Find more detailed information about sawdust grinding equipment you can here:. No other preparation of sawdust is required.

industrial way

Sawdust is poured into a vertical hopper, then filled with sulfuric acid solution(40%) in a ratio of 1:1 by weight and, having closed hermetically, is heated to a temperature of 200–250 degrees.

In this state, sawdust is kept for 60–80 minutes, constantly stirring.

During this time, the process of hydrolysis takes place and cellulose, absorbing water, breaks down into glucose and other components.

The substance obtained as a result of this operation filter, obtaining a mixture of glucose solution with sulfuric acid.

The purified liquid is poured into a separate container and mixed with a solution of chalk, which neutralizes acid.

Then everything is filtered and get:

toxic waste;
glucose solution.

Flaw this method in:

high requirements for the material from which the equipment is made;
high costs for acid regeneration,

therefore it was not widely used.

There is also a less expensive method., in which a solution of sulfuric acid with a strength of 0.5–1% is used.

However, effective hydrolysis requires:

high pressure (10–15 atmospheres);
heating up to 160-190 degrees.

The process time is 70–90 minutes.

Equipment for such a process can be made from less expensive materials, because such a dilute acid solution is less aggressive than that used in the method described above.

BUT pressure of 15 atmospheres is not dangerous even for conventional chemical equipment, because many processes also take place at high pressure.

For both methods use steel, hermetically sealed containers up to 70 m³, lined with acid-resistant bricks or tiles from the inside.

This lining protects the metal from contact with acid.

The contents of the containers are heated by supplying hot steam into them.

A drain valve is installed on top, which is adjusted to the required pressure. Therefore, excess steam escapes into the atmosphere. The rest of the steam creates the necessary pressure.

Both methods involve the same chemical process.. Under the influence of sulfuric acid, cellulose (C6H10O5)n absorbs water H2O and turns into glucose nC6H12O6, that is, a mixture of various sugars.

After purification, this glucose is used not only to obtain biofuels, but also for the production of:

drinking and technical alcohol;
Sahara;
methanol.

Both methods allow you to process wood of any species, therefore they are universal.

As a by-product of processing sawdust into alcohol, lignin is obtained - a substance that sticks together:

pellets;
briquettes.

Therefore, lignin can be sold to enterprises and entrepreneurs who are engaged in the production of pellets and briquettes from wood waste.

Another a by-product of hydrolysis is furfural. It is an oily liquid, an effective wood preservative.

Furfural is also used for:

oil refining;
purification of vegetable oil;
plastics production;
development of antifungal drugs.

In the process of processing sawdust with acid toxic gases are released, that's why:

all equipment must be installed in a ventilated workshop;
workers must wear safety goggles and respirators.

The yield of glucose by weight is 40–60% of the weight of sawdust, but taking into account the large amount of water and impurities the weight of the product is several times greater than the initial weight of the raw material.

Excess water will be removed during the distillation process.

In addition to lignin, the by-products of both processes are:

alabaster;
turpentine,

which can be sold for some profit.

Purification of glucose solution

Cleaning is carried out in several stages:

Mechanical cleaning using a separator removes lignin from the solution.
Treatment chalky milk neutralizes the acid.
settling separates the product into a liquid solution of glucose and carbonates, which are then used to obtain alabaster.

Here is a description of the technological cycle of wood processing at a hydrolysis plant in the city of Tavda (Sverdlovsk Region).

home method

This method is easier but takes an average of 2 years. Sawdust is poured in a large pile and watered abundantly with water, after which:

cover with something
leave spitting.

The temperature inside the heap rises and the process of hydrolysis begins, as a result of which cellulose is converted to glucose which can be used for fermentation.

The disadvantage of this method The fact is that at a low temperature the activity of the hydrolysis process decreases, and at a negative temperature it completely stops.

Therefore, this method is effective only in warm regions.

Besides, there is a high probability of degeneration of the hydrolysis process into decay, because of which it will turn out not glucose, but sludge, and all cellulose will turn into:

carbon dioxide;
not a large number of methane.

Sometimes in houses they build installations similar to industrial ones. . They are made of stainless steel, which can withstand the effects of a weak solution of sulfuric acid without consequences.

Heat up the contents such devices with:

open fire (bonfire);
stainless steel coil with hot air or steam circulating through it.

By pumping steam or air into the container and monitoring the readings of the pressure gauge, the pressure in the container is regulated. The hydrolysis process starts at a pressure of 5 atmospheres, but proceeds most efficiently at a pressure of 7–10 atmospheres.

Then, just as in industrial production:

purify the solution from lignin;
processed with a solution of chalk.

After that, the glucose solution is settled and fermented with the addition of yeast.

Fermentation and distillation

For fermentation into glucose solution add regular yeast that activate the fermentation process.

This technology is used both in enterprises and in the production of alcohol from sawdust at home.

Fermentation time 5–15 days, depending on the:

air temperature;
types of wood.

The fermentation process is controlled by the amount of formation of carbon dioxide bubbles.

During fermentation, such a chemical process occurs - glucose nC6H12O6 breaks down into:

carbon dioxide (2CO2);
alcohol (2C2H5OH).

After the end of fermentation material is distilled- heating to a temperature of 70–80 degrees and cooling the exhaust steam.

At this temperature evaporate from the solution:

alcohols;
ethers,

while water and water-soluble impurities remain.

steam cooling;
alcohol condensation

use a coil immersed in cold water or cooled by cold air.

For strength increase the finished product is distilled 2-4 more times, gradually lowering the temperature to a value of 50-55 degrees.

The strength of the resulting product determined with an alcohol meter which estimates the specific gravity of a substance.

The product of distillation can be used as a biofuel with a strength of at least 80%. A less strong product has too much water, so the technique will work inefficiently on it.

Although the alcohol obtained from sawdust is very similar to moonshine, its cannot be used for drinking due to the high content of methanol, which is a strong poison. In addition, a large amount of fusel oils spoils the taste of the finished product.

To clean from methanol, you must:

the first distillation is carried out at a temperature of 60 degrees;
drain the first 10% of the resulting product.

After distillation remain:

heavy turpentine fractions;
yeast mass, which can be used both for the fermentation of the next batch of glucose, and for the production of fodder yeast.

They are more nutritious and healthy than the grain of any cereal crops, so they are readily bought by farms that breed large and small livestock.

Biofuel application

Compared to gasoline, biofuels (alcohol made from recycled waste) have both advantages and disadvantages.

Here Main advantages:

high (105-113) octane number;
lower combustion temperature;
lack of sulfur;
lower price.

Due to the high octane number, increase compression ratio, increasing the power and efficiency of the motor.

Lower combustion temperature:

increases service life valves and pistons;
reduces engine heat in maximum power mode.

Due to the absence of sulfur, biofuels does not pollute the air and does not reduce service life engine oil , because sulfur oxide oxidizes the oil, worsening its characteristics and reducing the resource.

Due to the significantly lower price (except for excises), biofuel saves the family budget.

Biofuels have limitations:

aggressiveness towards rubber parts;
low fuel/air mass ratio (1:9);
weak evaporation.

biofuel damage rubber seals, therefore, during the conversion of the motor to run on alcohol, all rubber seals are changed to polyurethane parts.

Due to the lower fuel-to-air ratio, normal biofuel operation requires reconfiguration of the fuel system, that is, installing larger jets in the carburetor or flashing the injector controller.

Due to low evaporation Difficulty starting a cold engine at temperatures below plus 10 degrees.

To solve this problem, biofuels are diluted with gasoline in a ratio of 7:1 or 8:1.

To run on a mixture of gasoline and biofuel in a ratio of 1: 1, no engine modification is required.

If there is more alcohol, then it is desirable:

replace all rubber seals with polyurethane;
grind the cylinder head.

Grinding is necessary to increase the compression ratio, which will allow realize higher octane. Without such alteration, the engine will lose power when alcohol is added to gasoline.

If biofuels are used for electric generators or household gasoline appliances, then it is desirable to replace rubber parts with polyurethane ones.

In such devices, head grinding can be dispensed with, because a small loss of power is compensated by an increase in fuel supply. Besides, need to reconfigure the carburetor or injector, any specialist in fuel systems can do this.

For more information about the use of biofuel and the alteration of motors to work on it, read this article (Application of biofuel).

conclusions

Production of alcohol from sawdust - difficult process, which includes a lot of operations.

If there are cheap or free sawdust, then by pouring biofuel into the tank of your car, you will save a lot, because its production is much cheaper than gasoline.

Now you know how to get alcohol from sawdust used as biofuel and how you can do it at home.

Also, did you know about by-products that arise during the processing of sawdust into biofuels. These products can also be sold for a small but still profit.

Thanks to this, the biofuel business from sawdust is becoming highly beneficial, especially if you use fuel for your own transport and do not pay excise duty on the sale of alcohol.

In contact with

Production ethyl alcohol from sawdust biomass or cereal straw is sold in three ways:

acid or enzymatic hydrolysis of wood sawdust followed by fermentation of the hydrolyzate with appropriate yeast into ethanol,

pyrolysis (thermal decomposition) of wood sawdust and other municipal solid waste with the formation of synthesis gas (CO + H2) and subsequent fermentation of synthesis gas by the corresponding bacteria into ethanol,

pyrolysis decomposition of wood sawdust and MSW with the formation of synthesis gas, production of methyl alcohol from synthesis gas and subsequent catalytic conversion of methanol to ethanol (homogenization reaction).

With the hydrolysis method of production, the yield of alcohol will be only 200 liters from 1 ton of sawdust. But with the pyrolysis method of production, the yield of alcohol will already be 400 liters from 1 ton of sawdust. And the cost of alcohol production in the second case is 10 rubles / liter and depends on the scale of production and the cost of sawdust or straw.

Production of alcohol from sawdust by enzymatic hydrolysis. Fossil scarcity, energy security, climate change, protection environment- these are the problems that concern us today in the energy sector. Alternative energy sources must be found to reduce our dependence on oil, and nowhere is this more evident than in the transport sector. In the European Union, the United States and other major economic areas, policymakers have developed a basic framework to promote the use of sustainable biofuels

For some time now, many companies have shown a growing interest in the production of ethanol from renewable lignocellulosic resources such as agricultural waste. These resources do not compete with food and feed crops, but are created in sufficient quantities throughout the world as a by-product of modern agricultural practices, such as straw from cereal production.

The sunliquid® process, developed by Clariant, meets all the requirements of a technically and cost-effective, innovative process for converting agricultural waste into environmentally friendly biofuel - ethanol. Using process-integrated enzyme production, optimized enzymes, simultaneous conversion of cellulose and hemicellulose to alcohol (ethanol), and an energy-saving process design, it was possible to overcome technological problems and significantly reduce production costs in order to obtain a commercially viable alcohol.

Since 2009, Clariant has successfully operated the first pilot distillery at its research facility in Munich. This pilot plant is capable of producing up to two tons of alcohol per year. In July 2012, the largest Straubing distillery to date, a demonstration project with an annual capacity of up to 1,000 tons of alcohol, began operation in Straubing.

Various raw materials are converted into cellulose alcohol after pre-treatment, enzymatic hydrolysis and fermentation. The production of enzymes built into the process gives the lowest possible cost of alcohol.

Benefits of the sunliquid® process

Integrated process with the latest climate-friendly technologies

Low enzyme costs due to in-house enzyme production

Simultaneous fermentation of sugars C5 and C6 into ethanol in one vessel

Energy and water saving process

Generation of process energy from by-products

Flexible for various lignocellulosic raw materials

Sunliquid® Process

Preliminary processing cellulose residues

Pre-treatment of pulp without the use of chemicals reduces the production and investment costs of alcohol production. At the same time, environmental, health and safety risks are minimized.

Enzyme production

A small percentage of pre-treated cellulosic raw materials are used to produce their own enzymes directly at the plant, and are an integral part of the alcohol production process. This makes a significant contribution to the economic efficiency of the entire production process, resulting in a significant reduction in production costs and independence from supply shortages and enzyme price volatility.

Enzymatic hydrolysis

A special mixture of enzymes hydrolyses cellulose and hemicellulose chains to form sugar monomers. This stage is also called saccharification. Enzymes are highly optimized based on feedstock and process parameters, resulting in maximum yields and short reaction times under optimal conditions.

Fermentation / Fermentation

Using optimized microorganisms, the sunliquid® process ensures efficient fermentation, ensuring maximum ethanol yield. This highly optimized single tank system converts both C5 and C6 sugars to ethanol at the same time, providing up to 50% more ethanol than conventional processes that convert only C6 sugars.

Distillation and rectification of alcohol

The innovative and very energy-saving method of alcohol distillation and rectification reduces the energy requirement by up to 50% compared to conventional distillation. It is based on careful process planning and energy integration, resulting in a fully energy self-sustaining process.

next, no less interesting way sawdust wood processing - pyrolysis (thermal decomposition of cellulose), production of synthesis gas (a mixture of CO and H2) and the subsequent production of alcohols, synthetic gasoline, diesel fuel and others from synthesis gas.

Success in the qualitative development of this area was achieved by scientists from the Institute of Petrochemical Synthesis named after V.I. A.V. Topchiev of the Russian Academy of Sciences, who developed a technology that provides for the production of high-octane environmentally friendly synthetic gasoline with a good yield of the final product that meets the promising requirements of the Euro-4 standard using the simplest and most economical scheme for processing wood pulp.

The essence of their method for producing synthetic gasoline from wood pulp is as follows.
First, synthesis gas is obtained from wood cellulose at elevated pressure, containing hydrogen, carbon oxides, water, unreacted hydrocarbon remaining after its production, and also containing or not containing ballast nitrogen. Then, by condensation, water is isolated and removed from the synthesis gas, and then a gas-phase, one-stage catalytic synthesis of dimethyl ether is carried out. The gas mixture thus obtained is passed under pressure over a catalyst - a modified high-silicon zeolite - to produce gasoline, and the gas stream is cooled to separate synthetic gasoline.

The production of synthesis gas from wood pulp is carried out in various ways, for example, in the process of partial oxidation of hydrocarbon raw materials under pressure, which makes it possible to process it catalytically without additional compression (compression). Or it is obtained by catalytic reforming of hydrocarbon feedstock with steam or by autothermal reforming. In this case, the process is carried out with the supply of air, or oxygen-enriched air, or pure oxygen. Other options have been tweaked as well. At the third stage, the Fischer–Tropsch process itself is carried out, in which liquid hydrocarbons are synthesized on the basis of synthesis gas components. For example, when syngas (a mixture of carbon monoxide CO and hydrogen H2) is passed over a catalyst containing reduced iron (pure iron Fe) heated to 200°C, mixtures of predominantly saturated hydrocarbons (synthetic gasolines) are formed.

For the first time, synthetic liquid fuel GTL was produced in significant quantities in Germany during the 2nd World War 1939-45, which was due to a lack of oil. Synthesis was carried out at 170–200°C, pressure 0.1–1 MN/m2 (1–10 am) with a Co-based catalyst; as a result, gasoline (kogazin 1, or syntin) with an octane number of 40-55, high-quality diesel fuel (kogazin II) with a cetane number of 80-100 and solid paraffin were obtained. The addition of 0.8 ml of tetraethyl lead per 1 liter of synthetic gasoline increased its octane number from 55 to 74. Synthesis using an Fe-based catalyst was carried out at 220 °C and above, under a pressure of 1–3 MN/m2 (10–30 am). Synthetic gasoline obtained under these conditions contained 60-70% of olefinic hydrocarbons of normal and branched structure; its octane number is 75-78. Subsequently, the production of synthetic liquid fuel GTL from CO and H2 has not been widely developed due to its high cost and the low efficiency of the catalysts used. In addition to synthetic gasoline and diesel fuel, high-octane fuel components are synthetically produced, which are added to them to improve anti-knock properties. These include: isooctane obtained by catalytic alkylation of isobutane with butylenes; polymer gasoline is a product of catalytic polymerization of the propane-propylene fraction, etc. See Lit .: Rapoport IB, Artificial liquid fuel, 2nd ed., M., 1955; Petrov A. D., Chemistry of motor fuels, M., 1953; Lebedev N. N., Chemistry and technology of basic organic and petrochemical synthesis, M., 1971.).

synthetic gasoline , obtained by catalytic hydrogenation of carbon monoxide, has a low octane number; to obtain a high-grade fuel for internal combustion engines, it must be subjected to additional processing.

Methyl alcohol (methanol) in industry is mainly obtained from synthesis gas resulting from the conversion of natural gas methane. The reaction is carried out at a temperature of 300-600 °C and a pressure of 200-250 kgf/cm in the presence of zinc oxide and other catalysts: CO + H2 -----> CH3OH

The production of methyl alcohol (methanol) from synthesis gas is shown in a simplified schematic diagram

Homologation of methanol to ethanol. Homologization is a reaction in which an organic compound is converted into its homologue by introducing a methylene group CH2. In 1940, the reaction of methanol with synthesis gas catalyzed by cobalt oxide at a pressure of 600 atm was carried out for the first time with the formation of ethanol as the main product:

The use of cobalt carbonyl Co2(CO)8 as catalysts made it possible to lower the reaction pressure to 250 atm, while the degree of conversion of methanol to ethanol was 70%, and the main product, ethanol, was formed with a selectivity of 40%. By-products of the reaction are acetaldehyde and esters of acetic acid. Subsequently, more selective catalysts based on cobalt and ruthenium compounds with additions of phosphine ligands were proposed, and it was found that the reaction can be accelerated by introducing promoters - iodide ions. At present, a selectivity of 90% for ethanol has been achieved. Although the mechanism of homologation has not been fully established, it can be considered that it is close to the mechanism of methanol carbonylation.

Isobutyl alcohol is used to produce isobutylene, as a solvent, and also as a raw material for the production of some flotation reagents and vulcanization accelerators in the rubber industry.

In industry, isobutyl alcohol is obtained from carbon monoxide CO and hydrogen H2, similarly to the synthesis of methanol. The reaction mechanism consists in the following transformations:

The dehydration of isobutyl alcohol to isobutylene is a catalytic reaction. The splitting of water from the molecules of isobutyl alcohol occurs at 370 ° C and a pressure of 3-4 atm. Alcohol vapor is passed over a catalyst - purified alumina (active alumina).

One of the common technological schemes isobutylene production by dehydration of isobutyl alcohol is presented below.

Subsequent esterification of isobutylene with ethyl alcohol produces an oxygen-containing gasoline additive - environmentally friendly ethyl tert-butyl ether (ETBE), having an octane rating of 112 points (Research method).

Ethyl tert-butyl ether ETBE is a product of the synthesis of isobutylene with ethanol:

The technological scheme is very simple: the raw materials components, heated in the heat exchanger, pass through the reactor, where excess heat is removed (the reaction is very exothermic) and are separated in two columns.

In the first distillation column, n-butane and butylenes are separated from the reaction mixture, which are then used for alkylation (isomerization), and in the second - ready-made ETBE from above, and excess methanol from below, which is returned to the feed mixture.

The catalyst is an ion-exchange resin (sulfonic cation exchangers), the degree of conversion is 94% (by isobutylene), the purity of the resulting ETBE is 99%.

For 1 ton of ETBE, 360 kg of ethanol (100% ethyl alcohol) and 690 kg of 100% isobutylene are consumed.

Rice. Scheme for obtaining ETBE:

1 - reactor; 2, 3 - distillation columns; Threads: I - isobutylene; II - ethanol; III - butane and butylenes; IV - ETBE; V - ethanol recycle.

The calorific value of ETBE is lower than that of gasolines, ETBEs are used as high-octane additives to gasolines, increasing their DNP and improving the distribution of octane numbers in low-boiling fractions of catalytic reforming gasoline. The optimal effect is obtained by adding 11% ETBE mixture to 89-90% base gasoline with OC and /OC and = 85/91, after which AI-93 gasoline is obtained, however, its calorific value decreases from 42.70 MJ / kg (without additive) up to 41.95 MJ/kg.

Acetic acid is an organic compound with the molecular formula CH3COOH, and is a precursor for the manufacture of various other chemicals that serve various end-user industries such as textiles, paints, rubber, plastics and others. Its main application segments include the manufacture of vinyl acetate monomer (VAM), purified terephthalic acid (PTA), acetic anhydride, and ester solvents (ethyl acetate and butyl acetate).

Competence of acetic acid manufacturers: BP Plc (UK), Celanese Corporation (USA), Eastman Chemical Company (USA), Daicel Corporation (Japan), Jiangsu Sopho (Group) Co. Ltd. (China), LyondellBasell Industries NV (Netherlands), Shandong Hualu-Hengsheng Chemical Co. Ltd. (China), Shanghai Huayi (Group) Company (China), Yankuang Cathay Coal Chemicals Co. Ltd. (China), and Kingboard Chemical Holdings Ltd. (Hong Kong).

Celanese is one of the world's largest manufacturers of acetyl products (chemical intermediates such as acetic acid for virtually all major industries); acetyl intermediates account for about 45% of total sales. Celanese uses the methanol carbonylation process (the reaction of methanol and carbon monoxide); the catalyst used in the reaction and the resulting product (acetic acid) are purified by distillation.

In January 2013, Celanese received a US Patent (#7863489) for a direct and selective process for producing ethanol from acetic acid using a platinum/tin catalyst. The patent covers a process for the selective production of ethanol using a headspace reaction of acetic acid during hydrogenation on a catalyst composition to form ethanol. In one embodiment of the present invention, the reaction of acetic acid and hydrogen over a platinum/tin catalyst supported on silica, graphite, calcium silicate, or aluminosilicate selectively produces ethanol in the vapor phase at a temperature of about 250°C.

Production cost of ethyl alcohol through acetic acid and quality advantages

Price for acetic acid, acetic anhydride, vinyl acetate monomer in the US

Prices for acetic acid, acetic anhydride, vinyl acetate monomer in Europe

Prices for acetic acid, acetic anhydride, vinyl acetate monomer in Asia

Hydrolysis of plant tissue polysaccharides into cold water practically not observed. When the water temperature rises above 100°C, the hydrolysis of polysaccharides proceeds, but so slowly that such a process is of no practical importance. Satisfactory results are obtained only with the use of catalysts, of which only strong mineral acids are of industrial importance: sulfuric and, more rarely, hydrochloric. The higher the concentration of a strong acid in the solution and the reaction temperature, the faster the hydrolysis of polysaccharides to monosaccharides. However, the presence of such catalysts also has a negative side, since they, simultaneously with the reaction of hydrolysis of polysaccharides, also accelerate the reactions of decomposition of monosaccharides, thereby reducing their yield.

During the decomposition of hexoses under these conditions, oxy-methylfurfural is first formed, which quickly decomposes further to form the final products: levulinic and formic acids. Under these conditions, pentoses are converted into furfural.

In this regard, in order to obtain monosaccharides from plant tissue polysaccharides, it is necessary to provide the most favorable conditions for the hydrolysis reaction and minimize the possibility of further decomposition of the resulting monosaccharides.

This is the problem that researchers and production workers solve when choosing the optimal hydrolysis regimes.

Of the large number of possible options for acid concentration and reaction temperature, only two are currently used in practice: hydrolysis with dilute acids and hydrolysis with concentrated acids. During hydrolysis with dilute acids, the reaction temperature is usually 160-190°C and the concentration of the catalyst in aqueous solution ranges from 0.3 to 0.7% (H2SO4, HC1).

The reaction is carried out in autoclaves at a pressure of 10-15 atm. During hydrolysis with concentrated acids, the concentration of sulfuric acid is usually 70-80%, and hydrochloric 37-42%. The reaction temperature under these conditions is 15-40°.

It is easier to reduce the loss of monosaccharides during hydrolysis with concentrated acids, as a result of which the yield of sugar with this method can reach almost theoretically possible, i.e. 650-750 kg from 1 t absolutely dry vegetable raw materials.

During hydrolysis with dilute acids, it is much more difficult to reduce the loss of monosaccharides due to their decomposition, and therefore, in practice, the yield of monosaccharides in this case usually does not exceed 450–500 kg per 1 g of dry raw material.

Due to the low loss of sugar during hydrolysis with concentrated acids, the resulting aqueous solutions of monosaccharides - hydrolysates are distinguished by increased purity, which is of great importance in their subsequent processing.

Until recently, a serious shortcoming of hydrolysis methods with concentrated acids was the high consumption of mineral acid per ton of sugar produced, which led to the need to regenerate part of the acid or use it in other industries; this complicated and increased the cost of building and operating such plants.

Great difficulties also arose in the selection of materials for the equipment that are resistant to aggressive media. For this reason, most of the hydrolysis plants currently in operation were built using the dilute sulfuric acid hydrolysis method.

The first experimental hydrolysis-alcohol plant in the USSR was launched in January 1934 in the city of Cherepovets. The initial indicators and the technical design of this plant were developed by the Department of Hydrolysis Production of the Leningrad Forestry Academy in 1931-1933. On the basis of data from the operation of a pilot plant, construction began in the USSR of industrial hydrolysis and alcohol plants. The first industrial hydrolysis - alcohol plant was launched in Leningrad in December 1935. Following this plant in the period 1936-1938. Bobruisk, Khorsky and Arkhangelsk hydrolysis-alcohol plants were put into operation. During the Second World War and after it, many large factories were built in Siberia and the Urals. At present, the design capacity of these plants has been exceeded by 1.5-2 times as a result of improved technology.

The main raw material for these plants is softwood in the form of sawdust and chips coming from neighboring sawmills, where it is obtained by grinding sawmill waste - slabs and laths - in chippers. In some cases, coniferous firewood is also crushed.

The scheme for obtaining monosaccharides at such plants is shown in fig. 76.

Chopped coniferous wood from the warehouse of raw materials through conveyor 1 enters the guide funnel 2 and further down the throat

The fault of the hydrolysis apparatus 3. This is a vertical steel cylinder with upper and lower cones and necks. The inner surface of such hydrolysis apparatus cover with acid-resistant ceramic or graphite tiles or bricks, reinforced on a concrete layer 80-100 thick mm. The seams between the tiles are filled with acid-resistant putty. The upper and lower necks of the hydrolysis apparatus are protected from the action of hot dilute sulfuric acid by a layer of acid-resistant bronze from the inside. The useful volume of such hydrolysis apparatuses is usually 30-37 At3, but sometimes hydrolysis apparatuses with a volume of 18, 50 and 70 m3. The inner diameter of such hydrolysis apparatus is about 1.5, and the height is 7-13 m. In the upper cone of the hydrolysis apparatus during hydrolysis through the pipe 5 heated to 160-200 ° dilute sulfuric acid is supplied.

A filter is installed in the lower cone 4 for the selection of the obtained hydrolyzate. Hydrolysis in such devices is carried out periodically.

As mentioned above, the hydrolysis apparatus is loaded with crushed raw materials through a guide funnel. When loading raw materials through a pipe 5 dilute sulfuric acid heated to 70-90 ° is supplied, which wets the raw material, contributing to its compaction. With this method of loading in 1 m3 hydrolysis apparatus is placed about 135 kg sawdust or 145-155 kg Chips, in terms of absolutely dry wood. At the end of the loading, the contents of the hydrolysis apparatus are heated by live steam entering its lower cone. As soon as the temperature of 150-170°C is reached, 0.5-0.7%-share sulfuric acid, heated to 170-200°C, begins to flow into the hydrolysis apparatus through pipe 5. Simultaneously formed hydrolyzate through the filter 4 begins to be discharged to the evaporator b. The hydrolysis reaction in the hydrolysis apparatus lasts from 1 to 3 hours. The shorter the hydrolysis time, the higher the temperature and pressure in the hydrolysis apparatus.

In the process of hydrolysis, wood polysaccharides are converted into the corresponding monosaccharides, which dissolve in hot dilute acid. To protect these monosaccharides from decomposition at high temperatures, the hydrolyzate containing them is continuously removed through the filter throughout the cooking. 4 And quickly cooled in the evaporator 6. Since, according to the process conditions, hydrolyzable plant materials. into the hydrolysis apparatus" must be filled with liquid all the time, the set level e is maintained by hot acid flowing through pipe 5,

This method of operation is called percolation. The faster the percolation occurs, i.e., the faster the hot acid flows through the hydrolysis apparatus, the faster the resulting sugar is removed from the reaction space and the less it decomposes. On the other hand, the faster the percolation proceeds, the more hot acid is consumed for cooking and the lower the concentration of sugar in the hydrolyzate is obtained and, accordingly, the steam and acid consumption for cooking is greater.

In practice, to obtain sufficiently high yields of sugar (at an economically acceptable concentration in the hydrolyzate), one has to choose some average percolation conditions. Usually they stop at a sugar yield of 45-50% of the weight of absolutely dry wood with a sugar concentration in the hydrolyzate of 3.5-3.7% - These optimal reaction conditions correspond to the selection through the lower filter from the hydrolyzer - that 12-15 m3 hydrolyzate per 1 t absolutely dry wood loaded into the hydrolysis apparatus. The amount of hydrolyzate withdrawn per brew for each tonne of hydrolyzable raw material is called the flowout hydro-modulus, and it is one of the main indicators of the hydrolysis regime applied at the plant.

During percolation, a certain pressure difference arises between the upper and lower necks of the hydrolysis apparatus, which contributes to the compression of the raw material as the polysaccharides contained in it dissolve.

Compression of the raw material leads to the fact that at the end of the cooking, the remaining undissolved lignin occupies a volume of about 25% of the initial volume of the raw material. Since, according to the reaction conditions, the liquid should cover the raw material, its level decreases accordingly during the cooking process. Control of the liquid level during the cooking process is carried out using a weigher 30, showing the change in the total weight of raw materials and liquid in the hydrolysis apparatus.

At the end of cooking, lignin remains in the apparatus, containing 1 kg dry matter 3 kg dilute sulfuric acid, heated to 180-190 °.

Lignin is discharged from the hydrolysis apparatus into a cyclone 22 according to the pipe 21. For this purpose, the valve is quickly opened 20, connecting the interior of the hydrolysis apparatus with the cyclone 22. Due to the rapid decrease in pressure between the pieces of lignin, the superheated water contained in it instantly boils, forming large volumes of steam. The latter tears the lignin and carries it away in the form of a suspension through the pipe 21 into a cyclone 22. Pipe 21 approaches the cyclone tangentially, due to which the jet of steam with lignin, breaking into the cyclone, moves along the walls, making a rotational motion. Lignin is thrown to the side walls by centrifugal force and, losing speed, falls to the bottom of the cyclone. Lignin-free steam through the central tube 23 is released into the atmosphere.

Cyclone 22 usually a vertical steel cylinder with a volume of about 100 m3, with side door 31 and rotating agitator 25, which helps in unloading lignin from the bottom of the cyclone onto a belt or scraper conveyor 24.

To protect against corrosion, the inner surface of the cyclones is sometimes protected by a layer of acid-resistant concrete. As already mentioned above, during the percolation process, heated dilute sulfuric acid is fed into the upper cone of the hydrolysis apparatus. It is prepared by mixing in an acid-resistant mixer. 17 superheated water supplied through a pipe 28, with cold concentrated sulfuric acid coming from a measuring tank 19 through a piston acid pump 18.

Since cold concentrated sulfuric acid slightly corrodes iron and cast iron, these metals are widely used for the manufacture of tanks, pumps and pipelines intended for its storage and transportation to the mixer. Similar materials are also used to supply superheated iodine to the mixer. To protect the walls of the mixer from corrosion Apply phosphor bronze, graphite or plastic mass - fluoroplast 4. The last two are used for the internal lining of mixers and give the best results.

The finished hydrolyzate from the hydrolysis apparatus enters the evaporator 6 high pressure. It is a steel vessel, working under pressure and lined inside with ceramic tiles, like the hydrolyzer. In the upper part of the evaporator with a capacity of 6-8 l3 there is a cover. The evaporator is pressurized at 4-5 atm lower than in the hydrolysis apparatus. Due to this, the hydrolyzate entering it instantly boils, partially evaporating, and cools down to 130-140 °. The resulting steam is separated from the drops of the hydrolyzate and through the pipe 10 enters the reshofer (heat exchanger) 11, where it condenses. Partially cooled hydrolyzate from the evaporator 6 through pipe 7 enters the evaporator 8 low pressure, where it is cooled to 105-110 ° as a result of boiling at a lower pressure, usually not exceeding one atmosphere. The steam formed in this evaporator through the pipe 14 fed into the second reshofer 13, where it also condenses. Condensates from reshefers 11 and 13 contain 0.2-0.3% furfural and are used for its isolation in special installations, which will be discussed below.

The heat contained in the steam that exits the evaporators 6 and 8, used to heat the water entering the mixer 17. For this purpose, from the tank 16 circulating water pump 1b Warm water obtained from the distillation department of the hydrolysis plant is fed into the low pressure dryer 13, where it heats up from 60-80° to 100-110°. Then down the pipe 12 heated water passes through a high-pressure dryer 11, where steam at a temperature of 130-140° is heated to 120-130°. Further, the water temperature is increased to 180-200 ° in the hot water column 27. The latter is a vertical steel cylinder with a bottom and top cover designed for a working pressure of 13-15 atm.

Steam is supplied to the hot water column through a vertical pipe 26, at the end of which 30 horizontal disks are fixed 2b. Steam from a pipe 26 passes through the gaps between the individual discs into a column filled with water. The latter is continuously fed into the column through the lower fitting, mixed with steam, heated to a predetermined temperature and through the pipe 28 enters the mixer 17.

Hydrolyzers are installed on a special foundation in a row of 5-8 pcs. In large factories, they double the number and install them in two rows. Pipelines for the hydrolyzate are made of red copper or brass. Fittings, consisting of valves and valves, are made of phosphor bronze or certified bronze.

The hydrolysis process described above is batchwise. At the present time, new designs of hydrolpz are being tested - devices of continuous operation, into which, with the help of special feeders, chopped wood is continuously fed, lignin and hydrolyzate are continuously removed.

Work is also underway to automate batch hydrolysis apparatuses. This event allows you to more accurately observe the specified cooking mode and at the same time facilitates the work of cooks.

Acid hydrolyzate from low pressure evaporator 8 (fig. 76) along the pipe 9 fed into the equipment for its subsequent processing. The temperature of such a hydrolyzate is 95-98°. It contains (in%):

Sulfuric acid. . . ……………………………………………………………………………………………….. 0.5 -0.7:

Hexose (glucose, mannose, galactose)…………………………………………………………….. 2.5 -2.8;

Pentose (xylose, arabinose)……………………………………………………………………………. 0.8 -1.0;

Volatile organic acids (formic, acetic) …………………………….. 0.24-0.30;

Non-volatile organic acids (levulinic). . 0.2 -0.3;

Furfural………………………………………………………………………………………………………. 0.03-0.05;

Hydroxymethylfurfural………………………………………………………………………………………. 0.13-0.16;

methanol. ……………………………………………………………………………………………………….. 0.02-0.03

Hydrolysates also contain colloidal substances (lignin, dextrins), ash substances, terpenes, resins, etc. The content of monosaccharides in plant hydrolysates is determined by quantitative paper chromatography in precise chemical studies.

In factory laboratories, for mass express determinations of sugars, their ability in an alkaline medium to restore complex compounds of copper oxide with the formation of copper oxide is used:

2 Cu (OH) 2 Cu5 O + 2 H2 O + 02.

According to the amount of copper oxide formed, co - i-feeding of monosaccharides in solution is calculated.

This method for determining sugars is conditional, so As well as simultaneously with monosaccharides, copper oxide is reduced to oxide also furfural, hydroxymethylfurfural, dextrins, colloidal lignin. These impurities interfere with the determination of the true sugar content of hydrolysates. The total error here reaches 5-8%. Since the correction for these impurities requires a lot of labor, it is usually not done, and the resulting sugars, in contrast to monosaccharides, are called reducing substances or RV for short. In the factory, the amount of sugar produced in the hydrolyzate is taken into account in tons of RS.

To obtain ethyl alcohol, hexoses (glucose, mannose and galactose) are fermented by alcohol-forming yeasts - saccharomycetes or schizosaccharomycetes.

Summary equation of alcoholic fermentation of hexoses

C(i Hf, 06 - 2 C2 NG) OH + 2 CO2 Hexose ethanol

Shows that in this process, theoretically, for every 100 kg sugar should be 51.14 kg, or about 64 l 100% ethyl alcohol and about 49 kg carbon dioxide.

Thus, during alcoholic fermentation of hexose, two main products are obtained in almost equal amounts: ethanol and carbon dioxide. To carry out this process, the hot acidic hydrolyzate must be subjected to the following treatment:

1) neutralization; 2) release from suspended solids; 3) cooling down to 30°; 4) enrichment of the hydrolyzate with nutrients necessary for the vital activity of yeast.

The acid hydrolyzate has pH=1-1.2. An environment suitable for fermentation should have a pH of 4.6-5.2. To give the hydro-lysate the necessary acidity, the free sulfuric and a significant part of the organic acids contained in it must be neutralized. If all the acids contained in the hydrolyzate are conditionally expressed in sulfuric acid, then its concentration will be about 1%. The residual acidity of the hydrolyzate at pH = 4.6-5.2 is about 0.15%.

Therefore, to obtain the required concentration of hydrogen ions in the hydrolyzate, 0.85% of acids must be neutralized in it. In this case, free sulfuric, formic and part of acetic are completely neutralized. Levulinic acid and a small part of acetic acid remain free.

The hydrolyzate is neutralized with milk of lime, i.e., with a suspension of calcium oxide hydrate in water with a concentration of 150-200 g of CaO per liter.

The scheme for the preparation of milk of lime is shown in fig. 77.

Quicklime CaO is continuously fed into the feed funnel of the rotating lime-dumping drum. 34. At the same time, the required amount of water is fed into the drum. When the drum rotates, quicklime, binding water, passes into calcium oxide hydrate. The latter is dispersed in water, forming a suspension. Unreacted pieces of lime are separated at the end of the drum from lime milk and dumped into the trolley. Lime milk together with sand flows through the pipe to the sand separator 35. The latter is a horizontally located iron trough with transverse partitions and a longitudinal shaft with blades.

Lime milk in this apparatus slowly flows from right to left and further along the pipe 36 merges into collection 2.

Sand slowly settles between the partitions of the sand separator and is removed from the apparatus with the help of slowly rotating blades. Before the milk of lime enters the neutralizer, it is mixed with a given amount of ammonium sulphate, the solution of which comes from the tank 37. When milk of lime is mixed with ammonium sulphate, the reaction proceeds

Ca (OH) 3 + (NH4) 2 S04 -> CaS04 + 2 NH, OH, as a result of which part of the lime is bound by sulfuric acid of ammonium sulfate and crystals of poorly soluble calcium sulfate dihydrate CaS04-2H20 are formed. At the same time, ammonia is formed, which remains in the lime milk in a dissolved state.

Small crystals of gypsum present in milk of lime during subsequent neutralization are the centers of crystallization of the resulting gypsum and prevent the formation of supersaturated solutions of it in the neutralized hydrolyzate. This event is important in the subsequent distillation of alcohol from the mash, since supersaturated solutions of gypsum in the mash cause gypsum of the mash columns and quickly put them out of action. This method of work is called neutralization with directed crystallization of gypsum.

Simultaneously with lime milk into the neutralizer 5 Slightly acidic aqueous extract of superphosphate is supplied from a measuring tank 38.

Salts are given to the neutralizer at the rate of 0.3 kg ammonium sulfate and 0.3 kg superphosphate for 1 m3 hydrolyzate.

Converter 5 (capacity 35-40 m 3) is a steel tank lined with acid-resistant ceramic tiles and equipped with vertical agitators and brake vanes fixed to the tank walls. Neutralization at hydrolysis plants was previously carried out periodically. At present, it is being supplanted by more perfect continuous neutralization. On fig. 77 shows the last diagram. The process is carried out in two serially connected neutralizers 5 and 6, having the same device. Acid hydrolyzate through pipe 1 is continuously fed into the first neutralizer, where milk of lime and nutrient salts simultaneously enter. Control over the completeness of neutralization is carried out by measuring the concentration of hydrogen ions using a potentiometer 3 with an antimony or glass electrode 4. The potentiometer continuously records the pH of the hydrolyzate and automatically adjusts it within the specified limits by sending electrical impulses to a reversible motor connected to a shut-off valve on the pipe supplying milk of lime to the first neutralizer. In neutralizers, the neutralization reaction proceeds relatively quickly and the process of crystallization of gypsum from a supersaturated solution proceeds relatively slowly.

Therefore, the rate of liquid flow through the neutralization plant is due to the second process, which requires 30-40 min.

After this time, the neutralized hydrolyzate, called "neutralizate", enters the sump 7 semi-continuous or continuous action.

The semi-continuous process consists in the fact that the neutralizate flows continuously through the sump, and the gypsum settling to the bottom of it is removed periodically, as it accumulates.

With continuous operation of the sump, all operations are performed continuously. Before descending into the sewer, the sludge 8 in the receiver is additionally washed with water. The latter method, due to some production difficulties, has not yet become widespread.

The gypsum sludge from the settling tank usually consists of half calcium sulfate dihydrate and half lignin and humic substances settled from the hydrolyzate. In some hydrolysis plants, gypsum sludge is dehydrated, dried and fired, turning it into building alabaster. They are dehydrated on drum vacuum filters, and dried and fired in rotary drum kilns heated by flue gases.

The neutralizate, freed from suspended particles, is cooled in a refrigerator before fermentation 10 (Fig. 77) from 85 to 30°. For this purpose, spiral or plate heat exchangers are usually used, which are characterized by a high heat transfer coefficient and small dimensions. During cooling, resinous substances are released from the neutralizate, which settle on the walls of the heat exchangers and gradually pollute them. For cleaning, the heat exchangers are periodically turned off and washed with a 2-4% hot aqueous solution of caustic soda, which dissolves resinous and humic substances.

Neutralized, purified and chilled hydrolyzate.

The wood must is fermented with special spin-forming yeast acclimatized in this environment. Fermentation proceeds according to a continuous method in a battery of serially connected fermentation tanks 11 and 12.

Yeast slurry containing about 80-100 g of pressed yeast per liter is fed continuously through a pipe 15 into yeast 44 and then to the top of the first, or head, fermentation tank 11. Chilled wood must is fed into the yeast at the same time as the yeast suspension. For each cubic meter of yeast suspension, 8-10 m3 of wort enters the fermentation tank.

Yeast contained in the medium of hexose Sakharov, using a system of enzymes, they break down sugars, forming ethyl alcohol and carbon dioxide. Ethyl alcohol passes into the surrounding liquid, and carbon dioxide is released on the surface of the yeast in the form of small bubbles, which gradually increase in volume, then gradually float to the surface of the vat, entraining the yeast that has stuck to them.

Upon contact with the surface, the bubbles of carbon dioxide burst, and the yeast, having a specific gravity of 1.1, i.e., greater than that of the wort (1.025), sinks down until they are again raised by carbon dioxide to the surface. The continuous up and down movement of the yeast promotes the movement of liquid flows in the fermentation tank, creating agitation or "fermentation" of the liquid. Carbon dioxide released on the surface of the liquid from the fermentation tanks through the pipe 13 enters the plant for the production of liquid or solid carbon dioxide, is used to obtain chemical products(e.g. urea) or released into the atmosphere.

Partially fermented wood must, together with yeast, is transferred from the head fermentation tank to the tail tank 12, Where fermentation ends. Since the concentration of sugars in the tail vat is low, fermentation in it is less intense, and part of the yeast, not having time to form carbon dioxide bubbles, settles to the bottom of the vat. To prevent this, forced mixing of the liquid is often arranged in the tail tank with agitators or centrifugal pumps.

Fermented or fermented liquid is called mash. At the end of fermentation, the mash is transferred to the separator 14, operating on the principle of a centrifuge. The mash entering it, together with the yeast suspended in it, begins to rotate at a speed of 4500-6000 rpm. Centrifugal force due to the difference in specific gravity of the mash and yeast separates them. The separator divides the liquid into two streams: the larger one, containing no yeast, enters the funnel 16 and the smaller one, containing yeast, enters through the funnel into the pipe 15. Usually the first stream is 8-10 times larger than the second one. By pipe 15 the yeast slurry is returned to the head fermenter 11 Through yeast 44. The wort discarded and freed from yeast is collected in an intermediate collection of mash 17.

With the help of separators, the yeast is constantly circulated in a closed fermentation system. Productivity of separators 10- 35 m3/hour.

During fermentation and especially during separation, part of the humic colloids contained in the wood must coagulate, forming heavy flakes that slowly settle to the bottom of the fermentation tanks. Fittings are arranged in the bottoms of the vats, through which the sediment periodically descends into the sewer.

As mentioned above, the theoretical yield of alcohol from 100 kg fermented hexoses is 64 l. However, practically due to education through Sakharov by-products (glycerin, acetaldehyde, succinic acid, etc.), and also due to the presence of impurities harmful to yeast in the wort, the alcohol yield is 54-56 l.

To obtain good yields of alcohol, it is necessary to keep the yeast active all the time. To do this, it is necessary to carefully maintain the set fermentation temperature, the concentration of hydrogen ions, the necessary purity of the wort and leave a small amount of hexoses, the so-called “non-ferment” in the mash before it enters the separator (usually not more than 0.1% of sugar in solution). Due to the presence of non-fermentation, the yeast remains in an active form all the time.

Periodically, the hydrolysis plant is stopped for planned preventive or major repairs. At this time, the yeast should be kept alive. To do this, the yeast suspension is thickened with the help of separators and poured with cold wood must. At low temperatures, fermentation slows down dramatically and the yeast consumes significantly less sugar.

Fermentation tanks with a capacity of 100-200 m3 are usually made of sheet steel or, more rarely, of reinforced concrete. The duration of fermentation depends on the concentration of yeast and ranges from 6 to 10 hours. It is necessary to monitor the purity of the yeast production culture and protect it from infection by foreign harmful microorganisms. For this purpose, all equipment must be kept clean and sterilized periodically. The simplest method of sterilization is steaming all equipment and especially pipelines and pumps with live steam.

At the end of fermentation and separation of yeast, alcohol mash contains from 1.2 to 1.6% ethyl alcohol and about 1% pentose Sakharov.

Alcohol is isolated from the brew, purified and strengthened in a three-column brew distillation apparatus, consisting of a brew 18, distillation 22 and methanol 28 columns (Fig. 77).

Brazhka from the collection 17 pumped through a heat exchanger 41 on the feeding plate beer column 18. Flowing down on the plates of the exhaustive part of the mash column, the brew meets rising steam on its way. The latter, gradually enriched with alcohol, passes into the upper, strengthening part of the column. The mash flowing down is gradually freed from alcohol, and then from the bottom side of the column 18 along the pipe 21 goes to the heat exchanger 41, where it heats the mash entering the column to 60-70s. Next, the mash is heated to 105 ° in the column with live steam coming through the pipe 20. The brew freed from alcohol is called "vinasse". By pipe 42 Barda comes out of the bardy heat exchanger 41 and sent to the yeast workshop to obtain fodder yeast from pentose. This process will be discussed in detail later.

The mash column in the upper reinforcing part ends with a reflux condenser 19, in which vapors of iodine - alcohol mixture coming from the upper plate of the column are condensed.

About 1 m3 of carbon dioxide formed during fermentation dissolves in 1 m3 of mash at a temperature of 30 °. When heating the mash in the heat exchanger 41 and with live steam in the lower part of the beer column, dissolved carbon dioxide is released and, together with alcohol vapor, rises to the strengthening part of the column and further to the reflux condenser 19. Non-condensable gases are separated through air vents installed on the alcohol condensate pipelines after the refrigerators. Low-boiling fractions, consisting of alcohol, aldehydes and ethers, pass through the dephlegmator 19 and finally condensed in the refrigerator 39y From where, in the form of phlegm, they flow back into the column through a water seal 40. Non-condensable gases consisting of carbon dioxide before leaving the refrigerator 39 pass an additional condenser or are washed in a scrubber with water to trap the last traces of alcohol vapor.

On the upper plates of the beer column in the liquid phase contains 20-40% alcohol.

Condensate through the pipe 25 enters the feed tray of the distillation column 22. This column operates similarly to the beer column, but at higher alcohol concentrations. To the bottom of this column through a pipe 24 live steam is supplied, which gradually boils the alcohol out of the alcohol condensate flowing down to the bottom of the column. An alcohol-free liquid called luther through a pipe 23 goes down the drain. The alcohol content in stillage and luther is not more than 0.02%.

Above the top plate distillation column a dephlegmator is installed 26. Vapors not condensed in it are finally condensed in the condenser 26a and flow back into the column. Part of the low-boiling fractions is taken through the pipe 43 in the form of an etheraldehyde fraction, which is returned to the fermentation tanks if it has no use.

For the release of ethyl alcohol from volatile organic acids, the column is fed from a tank 45 10% sodium hydroxide solution, which neutralizes acids on the middle plates of the strengthening part of the column. In the middle part of the distillation column, where the alcohol strength is 45-50%, fusel oils accumulate, which are taken through a pipe 46. Fusel oils are a mixture of higher alcohols (butyl, propyl, amyl) formed from amino acids.

Ethyl alcohol, freed from esters and aldehydes, as well as fusel oils, is taken with a comb from the upper plates of the strengthening part of the distillation column and through the pipe 27 enters the feed tray of the methanol column 28. The raw alcohol coming from the distillation column contains about 0.7% of methyl alcohol, which was formed during the hydrolysis of plant materials and, together with monosaccharides, entered the wood must.

During fermentation, hexose methyl alcohol is not formed. According to the specifications for ethyl alcohol produced by hydrolysis plants, it should contain no more than 0.1% methyl alcohol. Studies have shown that methyl alcohol is most easily separated from raw alcohol with a minimum water content in it. For this reason, raw alcohol with a maximum strength (94-96% ethanol) is fed into the methanol column. Above 96% 'ethyl alcohol cannot be obtained on conventional distillation columns, since this concentration corresponds to the composition of a non-separately boiling water-alcohol mixture.

In the methanol column, the light-boiling fraction is methanol, which rises to the top of the column, strengthens in the dephlegmator 29 and through the pipe 30 merges into the collectors of the methanol fraction containing about 80% methanol. For the production of commercial 100% methanol, a second methanol column is installed, not shown in Fig. 77.

Ethyl alcohol, flowing down the plates, descends to the bottom of the methanol column 28 and through the pipe 33 merges into receivers of finished products. The methanol column is heated with deaf steam in an external heater 31, which is installed in such a way that, according to the principle of communicating vessels, its annulus is filled with alcohol. The water vapor entering the heater heats the alcohol to a boil, and the resulting alcohol vapors are used to heat the column. Steam entering the heater 31, condenses in it and in the form of condensate is supplied to clean water collectors or drained into the sewer.

The amount and strength of the resulting ethyl alcohol is measured in special equipment (lantern, control projectile, alcohol measuring stick). Ethyl alcohol is supplied from the measuring tank with a steam pump outside the main building - into stationary tanks located in the alcohol warehouse. From these tanks, as needed, commercial ethyl alcohol is poured into railway tanks, in which it is transported to places of consumption.

Described above technological process makes it possible to receive from 1 t absolutely dry softwood 150-180 l 100% ethyl alcohol. At the same time, for 1 dcl alcohol consumption

Absolutely dry wood in kg. . . . . 55-66;

TOC o "1-3" h z sulfuric acid - moaoidrate in kg … . 4,5;

Quicklime, 85% in kg…………………………………………………. 4,3;

A pair of technological 3- and 16-atmospheric

in megacalories. ………………………………………………………………………….. 0.17-0.26;

Water in m3……………………………………………………………………………………………. 3.6;

Electric Grossner in kWh…………………………………………………………………….. 4,18

The annual capacity of the medium-capacity hydrolysis-alcohol plant for alcohol is 1-1.5 million tons. gave. At these plants, the main product is ethyl alcohol. As already mentioned, at the same time, solid or liquid carbon dioxide, furfural, fodder yeast, and lignin processing products are produced from the main production waste at the hydrolysis-alcohol plant. These productions will be discussed further.

In some hydrolysis plants that receive furfural or xylitol as the main product, after the hydrolysis of hemicelluloses rich in pentoses, a hardly hydrolyzable residue consisting of cellulose and lignin and called cellolignin remains.

Cellolignin can be hydrolyzed by the percolation method as described above, and the resulting hexose hydrolyzate, usually containing 2-2.5% sugars, can be processed according to the method described above into technical ethyl alcohol or fodder yeast. According to this scheme, cotton husks, corn cobs, oak pods, sunflower husks, etc. are processed. Such a production process is economically profitable only with cheap raw materials and fuel.

At hydrolysis-alcohol plants, technical ethyl alcohol is usually obtained, which is used for subsequent chemical processing. However, if necessary, this alcohol
relatively easy to clean by additional distillation and oxidation with an alkaline solution of permanganate. After such purification, ethyl alcohol is quite suitable for food purposes.

Obtained using this description, the liquid is methanol. It is also known as methyl (wood) alcohol and has the formula - CH 3 OH.

Methanol in its pure form is used as a solvent and as a high-octane additive to motor fuel, as well as directly as a high-octane fuel (octane number => 115).

This is the same "gasoline" that fills the tanks of racing motorcycles and cars.

As foreign studies show, an engine running on methanol lasts many times longer than when using gasoline we are used to, and its power, with a constant working volume, increases by 20%.

The exhaust of an engine running on this fuel is environmentally friendly and when it is tested for toxicity, no harmful substances are detected.

A small-sized apparatus for obtaining this fuel is easy to manufacture, does not require special knowledge and scarce parts, and is trouble-free in operation. Its performance depends on various reasons, including dimensions.

The apparatus, the scheme and description of the assembly of which are given below, with a reactor diameter of only 75 mm, produces three liters of finished fuel per hour. In this case, the entire structure has a weight of about 20 kg and approximately the following dimensions: 20 cm in height, 50 cm in length and 30 cm in width.

Process Chemistry

We will not go deep into the variants of chemical processes and, for simplicity of calculations, we will assume that under normal conditions (20 ° C and 760 mm Hg) synthesis gas is obtained from methane according to the following formula:

2CH 4 + O 2 -> 2CO + 4H 2 + 16.1 kcal,

44.8 liters of carbon monoxide and 89.6 liters of hydrogen come out of 44.8 liters of methane and 22.4 liters of oxygen, then methanol is obtained from these gases according to the formula:

CO + 2H 2<=>CH 3 OH

from 22.4 l of carbon monoxide and 44.8 l of hydrogen it turns out: 12g (C) + 3g (H) + 16g (O) + 1g (H) \u003d 32 g of methanol.

This means that, according to the laws of arithmetic, 32 g of methanol comes out of 22.4 liters of methane, or approximately: from 1 cubic meter of methane, 1.5 kg 100% methanol(this is ~2 liters).

In reality, due to the low efficiency in domestic conditions, out of 1 cubic meter. natural gas will produce less than 1 liter of the final product (for this option, the limit is 1 l / h!).

For 2011, the price of 1 m3 household gas in Russia is 3.6-3.8 rubles and is constantly increasing. Given that the calorific value of methyl alcohol is half that of gasoline, we obtain an equivalent price of 7.5 rubles. and, finally, we round up to 8 rubles. for other expenses - el. energy, water, catalysts, gas purification - it still comes out much cheaper than gasoline and means that "the game is worth the candle" in any case!

The price of this fuel does not include the cost of installation (when switching to alternative fuels, a self-sufficiency period is always required), in this case the price will range from 5 to 50 thousand rubles, depending on productivity, automation of processes and whose forces will be manufactured.

With self-assembly, it will cost at least 2, and max. 10 thousand rubles. Basically, the money will be spent on turning and welding, as well as on the preparation of compressors (it can be from a faulty refrigerator, then it will be cheaper) and on the materials from which this unit is assembled.

Warning: methanol is a poison. It is a colorless liquid with a boiling point of 65°C, has an odor similar to ordinary drinking alcohol, and is miscible in all respects with water and many organic liquids. Remember that 50 milliliters of drunk methanol is fatal, in smaller quantities, poisoning with methanol decay products causes loss of vision!

The principle of operation and operation of the device

The functional diagram of the apparatus is shown in fig. one.

Tap water is connected to the “water inlet” (15) and, passing further, is divided into two streams: one stream (cleaned by a filter from harmful impurities) and through the faucet (14) and the hole (C) enters the mixer (1), and the other the flow through the faucet (4) and the hole (G) goes to the refrigerator (3), passing through which water, cooling the synthesis gas and methanol condensate, exits through the hole (Y).

Household natural gas, purified from impurities of sulfur and odorous odorants, is connected to the “Gas Inlet” pipeline (16). Further, the gas enters the mixer (1) through the hole (B), in which, having mixed with water vapor, it is heated on the burner (12) to a temperature of 100 - 120°C. Then, from the mixer (1) through the hole (D), the heated mixture of gas and water vapor enters through the hole (B) into the reactor (2).

The reactor (2) is filled with catalyst No. 1, mass fraction: 25% NiO (nickel oxide) and 60% Al 2 O 3 (alumina), the rest 15% CaO (quicklime) and other impurities, catalyst activity - residual volume fraction of methane during conversion with water vapor of hydrocarbon gas (methane) , completely purified from sulfur compounds, containing methane of at least 90%, with a volume ratio of steam: gas = 2: 1, not more than:

at 500°С - 37%
at 700°C - 5%.

In the reactor, synthesis gas is formed under the influence of a temperature of about 700°C, obtained by heating with a burner (13). Next, the heated synthesis gas enters through the hole (E) into the refrigerator (H), where it must be cooled to a temperature of 30-40°C or lower. Then the cooled synthesis gas leaves the refrigerator through the hole (I) and enters the compressor (5) through the hole (M), which can be used as a compressor from any domestic refrigerator.

Next, compressed synthesis gas with a pressure of 5-10 atm. through the hole (H) leaves the compressor and through the hole (O) enters the reactor (6). The reactor (6) is filled with catalyst No. 2, consisting of 80% copper and 20% zinc.

In this reactor, which is the most important unit of the apparatus, methanol vapor is formed. The temperature in the reactor should not exceed 270°C, which can be controlled with a thermometer (7) and adjusted with a faucet (4). It is desirable to maintain the temperature in the range of 200-250°C, or even lower.

Then, methanol vapor and unreacted synthesis gas exit the reactor (6) through the hole (P) and enter the refrigerator (H) through the hole (L), where the methanol vapor condenses and exits the refrigerator through the hole (K).

Further, the condensate and unreacted synthesis gas enter through the hole (U) into the condenser (8), where ready-made methanol is accumulated, which leaves the condenser through the hole (P) and the faucet (9) into some container.

The hole (T) in the condenser (8) serves to install a pressure gauge (10), which is necessary to control the pressure in the condenser. It is maintained within 5-10 atmospheres or more, mainly with the help of a faucet (11) and partially with a faucet (9).

The hole (X) and the cock (11) are necessary to exit the condenser of unreacted synthesis gas, which is recirculated back to the mixer (1) through the hole (A), but as practice has shown, the outlet gases must be burned in the wick, and not run back to the system. Yes, this reduces efficiency, but it greatly simplifies tuning.

The cock (9) is adjusted so that clean liquid methanol without gas constantly comes out.

It will be better if the level of methanol in the condenser will increase than decrease. But the most optimal case is when the methanol level is constant (which can be controlled by built-in glass or some other way).

The faucet (14) is adjusted so that there is no water in the methanol, and less steam is formed in the mixer, rather than more.

Starting the machine

Gas access is opened, water (14) is still closed, burners (12), (13) are working. Tap (4) is fully open, compressor (5) is on, tap (9) is closed, tap (11) is fully open.

Then the tap (14) for water access is slightly opened, and the required pressure in the condenser is regulated with the tap (11), controlling it with a pressure gauge (10). But in no case do not close the faucet (11) completely!!!

Then, after five minutes, the tap (14) and the ignited burner (21) bring the temperature in the reactor (6) to 200-250°C. After that, the burner (21) is extinguished, it is only needed for preheating, because. methanol is synthesized with the release of heat. Then the faucet (9) is slightly opened, from which a stream of methanol should come out. If it goes on constantly, open the faucet (9) a little more, if methanol flows in a mixture with gas, open the faucet (14) a little.

In general, the more performance you set up the device, the better.

This apparatus is preferably made of stainless steel or iron. All parts are made of pipes, copper pipes can be used as thin connecting pipes. In the refrigerator, it is necessary to maintain the ratio X:Y=4, that is, for example, if X+Y=300 mm, then X should be equal to 240 mm, and Y, respectively, 60 mm. 240/60=4. The more coils fit in the refrigerator on both sides, the better.

All faucets are used from gas welding burners. Instead of taps (9) and (11), pressure reducing valves from household gas cylinders or capillary tubes from household refrigerators can be used.

The mixer (1) and the reactor (2) are heated in a horizontal position (see drawing).

Well, perhaps that's all. In conclusion, I would like to add that a more progressive design for home-made auto fuel was published in several issues of Priority magazine in 1992-93:
№1-2 — general information on the production of methanol from natural gas.
No. 3-4 - drawings of a plant for processing methane into methanol.
No. 5-6 - installation, safety measures, control, instructions for turning on the equipment.

Figure 1 - Schematic diagram of the apparatus

Figure 2 - Mixer

Figure 3 - Reactor

Figure 4 - Refrigerator

Figure 5 - Capacitor

Figure 6 - Reactor

Additions from Igor Kvasnikov

I stumbled upon your post by chance in a search engine and was very interested in its content. After a brief introduction, inaccuracies made by the author immediately surfaced.

Information about "methanol" was published in the journal "Prioritet" for 1991, 92, 93. , but the fully finished project was never published (the promised catalysts for subscribers were clamped down).

In these issues there were drawings of the reactor with the electrical control circuit and the design of the cooler, after which Mr. Waks (the author of the article) politely apologized and said that further publication was stopped at the request of the power structures of the USSR and for those who want to repeat this installation, the field of creativity is unlimited. Figure 1(a) - Modified apparatus layout

1st stage - as mentioned earlier, gas and water should be cleaned (with a household filter, even better with a distiller) so as not to immediately poison the catalysts of 2 and 6 reactors. More precisely, adhere to the ratio of steam: gas, as 2: 1. There should be no return of unreacted products to the 1st stage.

2nd stage - methane conversion starts at t=~400°С, but at such a low t°С the percentage of converted gas is low, the most optimal temperature is t=700°С, it is desirable to control it with a thermocouple.

After the reactor and cooler, the unit has a pressure gauge (10) and a pressure reducing valve (11) set to a pressure of 25-35 atm (the choice of pressure depends on the degree of wear of the catalyst). It is better to use two compressors from the refrigerator to pressurize enough synthesis gas.

I advise you to make the condenser (8) not cylindrical, but conical (this is done in order to reduce the methanol evaporation area) and with a window to control the methanol level. The reacted products are supplied from the top of the cone using a tube (y) Ø 8 mm.

The tube is lowered into the conical vessel below the throttling outlet (P) by 10 mm.

The unreacted synthesis gas is discharged through a tube (x) Ø 5 mm, which is welded into the top of the cone, the outgoing gas through this tube is burned at its end, to prevent the flame from escaping into the cone vessel, the end of the tube is stuffed with copper wire.

The methanol level is maintained at 2/3 of the total height of the vessel, for this it is better to make a transparent window. To ensure 100% safety, it is possible to equip the outlet wick with a thermocouple, on the signal of which (in the absence of a flame) the gas supply to the installation is automatically shut off, any regulator from modern gas stoves is suitable for this purpose.

The catalytic method for producing methanol (wood alcohol) from natural gas is described in detail.