Alcohol from sawdust at home. Production of ethyl alcohol from wood
Currently, many people are able to create methanol even with their own hands at home. Including engaged in the preparation of alcohol from sawdust. It is the production of alcohol from sawdust that is considered the simplest and most economical of all other methods known today. At the same time, it seems complicated and time-consuming only at first glance. In fact, repeating this process will be quite simple even for a beginner. The main thing is to know all the basic principles for the manufacture of methyl alcohol, as well as take into account some of the tricks of the procedure that professionals reveal to everyone. The standard technology for the production of the chemical under discussion at home usually consists of several basic steps at once. To begin with, malt is obtained from cereals, then a paste is brewed from slightly spoiled potatoes, as a result of which the starch is processed.
The next stage is fermentation. On it, yeast is already added to a pre-prepared mixture. The higher the ambient temperature, the faster it will be possible to overcome the discussed stage. But it is able to end on its own even under normal natural conditions. Of course, in the event that high-quality yeast was chosen. The penultimate stage is called "distillation". It can be called the most laborious and lengthy. For this stage, a special apparatus is always required, which, by the way, modern craftsmen easily make with their own hands. And finally, there is only cleaning. This is the last step in the production of alcohol at home. The product is almost ready, but it lacks the desired transparency. It will be possible to achieve it with the help of the most common potassium permanganate, with which the liquid is infused for 24 hours. In conclusion, it remains only to filter the product.
Since recently the amount of fossil raw materials that are suitable for the production of alcohol at home has begun to gradually decrease, it has become necessary to find new options. As you know, there is a shortage of grain, so it was necessary to find a worthy alternative to it. And it was quickly found - it's sawdust. This raw material is currently the most accessible to everyone. Finding him is not difficult. And last but not least, sawdust is inexpensive. And in some cases, they can even be found completely free of charge. It is not surprising that the raw materials under discussion are very popular among everyone involved in the production of alcohol at home. True, the manufacture of this substance requires certain skills from a person, as well as the acquisition of some additional equipment.
First of all, you need to prepare sawdust. For example, 1 kilogram of the original product. It is very important that the sawdust is thoroughly crushed. They will need to be thoroughly dried before proceeding with the production of methanol. It is best to refuse to use an oven and other similar options for this purpose. It will be enough to pour the sawdust in a thin layer on a clean newspaper in a dark, well-ventilated area and leave it in this form for several days. Of course, the raw materials also should not have been any impurities and dirt. Experts note that hardwood sawdust is best suited for this process. But it is better not to use raw materials from conifers.
Through the refrigerator, in which sublimation and electrolyte, which is perfect for sulfuric acid, will be carried out, carefully dried sawdust is sent to a convenient flask or other similar container. They must fill it to 2/3 of the total volume. Next, you need to heat the mass to 150 degrees. The finished liquid usually has a slight bluish tint. Of course, do not forget about the use of high-quality catalyst. For example, you can use aluminum oxide - parts of corundum. You can pour the next portion into the used vessel immediately after the liquid in it turns black. It is very important to protect your respiratory organs with a respirator or a special mask. It is also best to think about durable gloves. The room in which alcohol is made from sawdust should be spacious and well ventilated. You should not do this in the kitchen, as there are products around.
The finished substance can be used as a fuel and for any other similar purposes. But it is not recommended to use the resulting alcohol inside and use it for further preparation of alcoholic beverages from it. From just one kilogram of dried sawdust, you can get about half a liter (slightly less) of finished methanol.
There is a growing demand for biofuels - combustible liquids made from renewable biological resources. One of them is wood. Is it possible to obtain fuel from wood that is not inferior to oil?
The first thing to understand is that it is precisely gasoline or kerosene that cannot be made from wood. It does not decompose into straight chain hydrocarbons, of which petroleum products are mainly composed. However, this does not mean that substances that can replace petroleum products cannot be obtained from it.
Some people love the stool
First on the list, of course, is alcohol. Two different types of alcohol can be obtained from wood. The first, which is called woody, is scientifically methyl alcohol. This substance is very similar to the usual ethyl alcohol, both in combustibility and in smell and taste. However, methyl alcohol differs in that it is very poisonous, and ingestion of it can lead to fatal poisoning. At the same time, it is a high-quality motor fuel, its octane number is even higher than that of ethyl alcohol, and much higher than that of ordinary gasoline.
The technology for obtaining methyl alcohol from wood is very simple. It is obtained by dry distillation, or pyrolysis. More precisely, it is one of the components of the liquid - a mixture of oxygen-containing organic substances that are separated from freshly expelled wood resin. However, the yield of alcohol thus obtained is too low to be used as a fuel. This makes this technology of fuel production unpromising.
However, ethyl alcohol can also be obtained from wood, in much larger quantities. This alcohol - the so-called hydrolysis - is obtained by the decomposition of cellulose, the main component of wood, with the help of sulfuric acid. Rather, when cellulose decomposes, sugars are obtained, which in turn can be processed into alcohol in the usual way. This method of obtaining ethyl alcohol is very common in industry; it is the hydrolysis method that produces almost all technical alcohol used for non-food purposes.
Ethyl alcohol can be used both directly instead of gasoline and as an additive to gasoline. By means of such additives, various grades of biofuels are obtained, which are popular, in particular, in countries such as Brazil.
Obtaining ethyl alcohol by hydrolysis of wood is somewhat less economically profitable than obtaining it from various agricultural crops. However, the advantageous side of this method of obtaining biofuel is that it does not require the allocation of agricultural areas for "fuel" crops that do not provide food products, but allows the use of forestry areas for its production. This makes the production of biofuel ethanol from wood a rather practical technology.
And turpentine is good for anything
The disadvantage of ethanol as a fuel is its low calorific value. When used in engines in its pure form, it gives either less power or more consumption than gasoline. Mixing alcohol with substances with a high calorific value helps to solve this problem. And not necessarily these are products from oil: turpentine, or turpentine, is quite suitable as such an additive.
Turpentine is also a product of wood processing, and more specifically, coniferous: pines, firs, larches and others. It is widely used as a solvent, and its most purified varieties are used in medicine. However, the timber processing industry produces a large amount of the so-called sulfate turpentine as a by-product - the lowest grade containing toxic impurities, not only inapplicable in medicine, but also finds very limited use in the chemical and paint and varnish industries.
At the same time, turpentine of all wood processing products is most similar to an oil product, more precisely, to kerosene. It has a very high calorific value and can be used as fuel in kerosene stoves, lamps, and kerosene gases. It is also suitable as a motor fuel, however, for a short time: if it is poured into tanks in its pure form, the engines soon fail due to tarring.
However, turpentine can be used as a fuel not in its pure form, but as an additive to ethanol. Such an additive does not greatly reduce the octane number of ethyl alcohol, but increases the heat of combustion. Another positive side of this biofuel manufacturing technology is that turpentine denatures alcohol, making it unsuitable for ingestion as alcohol. And the social consequences of the widespread introduction of undenatured alcohol as a fuel can become very severe.
Lignin waste - into income!
Such a component of wood as lignin is considered of little use. Its use in industry is much less widespread than that of cellulose. Despite the fact that it finds application in the production of building materials and in the chemical industry, more often it is simply burned directly at the timber and chemical industry. However, as it turns out, more diverse products can be obtained from lignin pyrolysis than from cellulose pyrolysis.
Lignin consists mainly of aromatic rings and short straight hydrocarbon chains. Accordingly, during its pyrolysis, predominantly hydrocarbons are obtained. However, depending on the pyrolysis technology, it is possible to obtain both a product with a high content of phenol and related substances, and a liquid resembling petroleum products. This fluid is also suitable as an ethanol additive for biofuel production.
Technologies and installations for pyrolysis have been developed that can consume both lignin from dumps and wood waste not separated into lignin and cellulose. Better results are obtained when mixing lignin or wood waste with garbage consisting of discarded plastic or rubber: the pyrolysis liquid is more oily.
Peaceful atom and sawdust
Another technology for obtaining biofuel from wood was developed quite recently by Russian scientists. It belongs to the field of radiochemistry, that is, chemical processes occurring under the influence of radioactive radiation. In the experiments of scientists from the Institute of Chemistry. Frumkin's sawdust and other wood waste were subjected to simultaneous exposure to strong beta radiation and dry distillation, and the heating of the wood was carried out precisely with the help of super-strong radiation. Surprisingly, under the influence of radiation, the composition of the products obtained during pyrolysis has changed.
In the pyrolysis liquid obtained by the "radioactive" method, a high content of alkanes and cycloalkanes, that is, hydrocarbons contained mainly in oil, was found. This liquid turned out to be much lighter than oil, comparable, rather, with gas condensate. Moreover, the examination confirmed the suitability of this liquid for use as a motor fuel or processing into high-quality fuels, such as motor gasoline. We think that this does not deserve special mention, but let's clarify for the sake of calming the fears of radiophobes: beta radiation is not capable of causing induced radioactivity, therefore the fuel obtained in this way is safe and does not exhibit radioactive properties itself.
What to recycle
It is clear that it is preferable to use not whole tree trunks for biofuel production, but wood processing waste, such as sawdust, wood chips, twigs, bark, and even the same lignin that goes to dumps and furnaces. The output of these wastes per hectare of felled forest is, of course, lower than wood in general, but we should not forget that they are obtained as a by-product in the production processes that are already underway at many enterprises in the country, respectively, production wastes are cheap and for them there is no need to cut down or plant additional forest areas for felling.
In any case, wood is a renewable resource. Ways to restore forest areas have long been known, and in many regions of the country there is even an uncontrolled overgrowth of abandoned agricultural land with forests. One way or another, the Russian Federation is not one of the countries where forest conservation should be treated with all due diligence; the areas of our forest and its potential for self-restoration are quite enough to fully load the timber processing industry, the production of biofuels, and many other industries.
Hydrolysis of plant tissue polysaccharides in cold water is 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-methyl furfural is first formed, which quickly decomposes further with the formation of 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 formed 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 small 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
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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 hopper of the rotating lime slaking 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 operation.
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 (for example, urea) or is 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 feed plate of the 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 mash 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%.
A dephlegmator is installed above the upper plate of the distillation column. 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 the fermentation of 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.
The technological process described above makes it possible to obtain 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.
How to get alcohol or other liquid fuel from sawdust?
- in Germany at the end of World War II, all tanks went to synthetic. sawdust fuel. and cars in Brazil drive very much on alcohol, 20% of the cars there are on alcohol. so it’s true, you can use fermentation, overtake and get alcohol and you will have a car
maybe you can get methane with the help of bacteria? even better then - I'll share my experience, so be it! In general, you take 1KG. you dry wood sawdust or other things very carefully, then add electrolyte (sulfuric acid) 1/3 of the volume to the flask or something else through the refrigerator (there will be sublimation). you heat it up to a temperature of 150 degrees, and you get Methyl Alcohol, and in the same place its esters, etc. COMBUSTIBLE reaction products. liquid can be of different colors. but usually bluish, volatile. Yes, when you cook, do not forget to add pieces of Corundum (aluminum oxide) - this is a catalyst. as soon as the liquid in the vessel or flask turns black, to the point of being unrecognizable, change and fill in the next portion. with 1 kg you will get somewhere 470 ml. alcohol, but only 700 something. Do it in an open area, well ventilated and away from food. Yes, don't forget your mask and respirator. Strain the black (spent) liquid, and the top layer burns very well after drying. add it to the fuel too.
- From conifers - bad. Typically, hydrolysis alcohol is obtained from hardwoods. Here, in fact, there are two options, and both are practically not implemented at home. And stool vodka is by and large a joke, since production is inefficient and the use of the final product can be hazardous to health. First option. It is necessary to put the sawdust in a fairly large pile on the street, wet it with water and leave it for a couple of years (precisely two years or more). Anaerobic microorganisms will settle in the center of the heap, which will gradually carry out the breakdown of cellulose to monomers (sugars), which can already be fermented. Further - as usual moonshine. Or the second option, which is implemented in industry. Sawdust is boiled with a weak solution of sulfuric acid at elevated pressure. In this case, the hydrolysis of cellulose is carried out in a few hours. Next - distillation as usual.
If we consider not only ethyl alcohol, then we can go a different way, but, again, it is practically not realized at home. This is the dry distillation of sawdust. The raw material must be heated in a sealed container to 800-900 degrees. and collect escaping gases. When these gases are cooled, creosote (the main product), methanol and acetic acid condense. Gases are a mixture of various hydrocarbons. The rest is charcoal. It is this kind of coal in the industry that is called charcoal, and not from a fire. It used to be used in metallurgy instead of coke. After its additional processing, activated carbon is obtained. Creosote is the resin used to tar sleepers and telegraph poles. Gas can be used as ordinary natural gas. Now liquids. Methyl, or wood, alcohol is distilled off from the liquid at temperatures up to 75 degrees. It can pass for fuel, but the yield is small and it is very poisonous. Next is acetic acid. When neutralized with lime, calcium acetate is obtained, or, as it was previously called, gray wood acetic powder. When it is calcined, acetone is obtained - why not fuel? True, now acetone is obtained in a completely synthetic way.
Looks like I didn't forget anything. Well, when do we open a creosote shop? - "And if vodka was not driven from sawdust, then what would we have, from five bottles?" (V.S. Vysotsky)
- fermentation of sugary substances. such as cellulose. only for acceleration you need an enzyme-yeast. and about methyl alcohol .... well, in general, at low doses, it is deadly.
- Sublimation.
- It is necessary to ferment the cellulose, then overtake
In Soviet times, who still remembers, they joked a lot about alcohol made from sawdust. There were rumors that after the war, cheap vodka was made just on the basis of "sawdust" alcohol. In the people, this drink was called - "bitch".
In general, talk about the production of alcohol from sawdust arose, of course, not from scratch. Such a product was actually produced. It was called "hydrolytic alcohol". The raw material for its production was indeed sawdust, more precisely, cellulose extracted from the waste of the forestry industry. Speaking strictly scientifically - from non-food plant materials. According to rough calculations, about 200 liters of ethyl alcohol could be obtained from 1 ton of wood. This supposedly made it possible to replace 1.5 tons of potatoes or 0.7 tons of grain. Whether such alcohol was used in Soviet distilleries is unknown. It was produced, of course, for purely technical purposes.
It must be said that the production of technical ethanol from organic waste has long excited the imagination of scientists. You can find literature of the 19th century, where the possibilities of obtaining alcohol from a wide variety of raw materials, including non-food ones, are discussed. In the 20th century, this theme sounded with renewed vigor. In the 1920s, scientists in Soviet Russia even suggested making alcohol from… feces! There was even a playful poem by Demyan Bedny:
Well the time has come
Every day is a miracle:
Vodka is driven from shit -
Three liters per pood!
Russian mind will invent
To the envy of all Europe -
Soon the vodka will flow
Into the mouth from the very ass ...
However, the idea with feces remained at the level of a joke. But cellulose was taken seriously. Remember, in The Golden Calf, Ostap Bender tells foreigners about the recipe for "stool moonshine". The fact is that with cellulose they were already “chemizing” at that time. Moreover, it should be noted that it can be extracted not only from the waste of the forest industry. Domestic agriculture annually leaves huge mountains of straw - this is also an excellent source of cellulose. Do not waste good. Straw is a renewable source, one might say - free.
There is only one catch in this case. In addition to the necessary and useful cellulose, the lignified parts of plants (and straw is one of them) contain lignin, which complicates the whole process. Due to the presence of this very lignin in the solution, it is almost impossible to obtain a normal “mash”, since the raw material is not saccharified. Lignin inhibits the development of microorganisms. For this reason, “feeding” is required - the addition of normal food raw materials. Most often, this role is played by flour, starch or molasses.
Of course, you can get rid of lignin. In the pulp and paper industry, this is traditionally done chemically, such as by acid treatment. The only question is where to put it then? In principle, good solid fuel can be obtained from lignin. It burns well. Thus, the Institute of Thermal Physics of the Siberian Branch of the Russian Academy of Sciences has even developed an appropriate technology for burning lignin. But, unfortunately, the lignin that remains from our pulp and paper production is unsuitable as a fuel due to the sulfur it contains (the consequences of chemical processing). If we burn it, we get acid rain.
There are other ways - to process raw materials with superheated steam (lignin melts at high temperatures), to carry out extraction with organic solvents. In some places they do just that, but these methods are very costly. In a planned economy, where all costs were borne by the state, it was possible to work in this way. However, in a market economy, it turns out that the game, figuratively speaking, is not worth the candle. And when comparing costs, it turns out that the production of industrial alcohol (in modern terms, bioethanol) from traditional food raw materials is much cheaper. It all depends on how much you have such raw materials. Americans, for example, have an overproduction of corn. It is much easier and more profitable to use the surplus for the production of alcohol than to transport it to another continent. In Brazil, as we know, surplus sugarcane is also being used as feedstock for the production of bioethanol. In principle, there are not so few countries in the world where alcohol is poured not only into the stomach, but also into the tank of a car. And everything would be fine if some well-known world figures (in particular, the Cuban leader Fidel Castro) did not oppose such an “unfair” use of agricultural products in conditions when in some countries people suffer from malnutrition, or even die of hunger. .
In general, meeting philanthropic wishes, scientists working in the field of bioethanol production should look for some more rational, more advanced technologies for processing non-food raw materials. Approximately ten years ago, specialists from the Institute of Solid State Chemistry and Mechanochemistry of the Siberian Branch of the Russian Academy of Sciences decided to take a different path - to use the mechanochemical method for these purposes. Instead of the well-known chemical processing of raw materials or heating, they began to use special mechanical processing. Why special mills and activators were designed. The essence of the method is as follows. Due to mechanical activation, cellulose passes from the crystalline state to the amorphous state. This makes it easier for the enzymes to work. But the main thing here is that the raw material in the process of mechanical processing is divided into various particles - with different (higher or lower) lignin content. Then, thanks to the different aerodynamic characteristics of these particles, they can be easily separated from each other using special devices.
At first glance, everything is very simple: grind - and that's it. But only at first glance. If everything was really so simple, then in all countries they would grind straw and other plant waste. In fact, it is necessary to find the right intensity here so that the raw material is separated into individual tissues. Otherwise, you will end up with a monotonous mass. The task of scientists is just to find the necessary optimum here. And this optimum, as practice shows, is quite narrow. You can also overdo it. That, I must say, is the work of a scientist in order to reveal the golden mean. Moreover, here it is necessary to take into account economic aspects - namely, to work out the technology so that the costs of mechanochemical processing of the feedstock (however cheap it may be) do not affect the cost of production.
Dozens of liters of wonderful alcohol have already been obtained in laboratory conditions. The most impressive thing is that alcohol is obtained from ordinary straw. And - without the use of acids, alkalis and superheated steam. The main help here is the “miracle mills” designed by the specialists of the Institute. In principle, nothing prevents us from moving on to industrial designs. But that is another topic.
Here it is - the first domestic bioethanol from straw! Still in bottles. Will we wait until they start producing it in tanks?
