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Distillation column device. Distillation columns, their device and principle of operation

The operation of the distillation column is based on repeated evaporation of alcohol for its purification. The processing of this substance is an important task of modern industry. Alcohol has a wide range of uses, so its quality must meet the requirements of a technical and food nature.

1

The rectification process is the separation of mixtures containing alcohol into pure elements. For this, the boiling of substances is used, each of which has its own evaporation temperature. During this process, steam is generated, and each fraction is separated from its initial mixture. As a rule, aldehydes, water, ethyl and methyl alcohols, fusel oils and others are released during rectification. Such a device is most effective against secondary impurities.

Separation of mixtures containing alcohol into pure elements in a distillation column

Rectification is possible due to the different content ratio of individual components in the liquid base and in the state of vaporization. Since the system tends to equilibrium, it tries to equalize the temperature, pressure and concentration of the substance in each of the phases. When the vapor comes into contact with a liquid, it is enriched in the components of low-boiling "volatile" components, and the liquid absorbs high-boiling substances. This process is accompanied by heat exchange.

Distillation column parameters:

Dimensions and material. The design includes nozzles, cylinders, distillers and a cube. For the column, a stainless food alloy is used, which does not emit harmful substances in the liquid.
heating system. For a high-quality column, it is necessary to accurately control the heating power. by the most optimal way today is the use of heating elements, which are installed in lower part columns. It is not recommended to use the standard gas supply, as its features do not allow smooth adjustment of the heating power.
Performance. This parameter includes the heating power, which is responsible for the intensity of steam movement inside the structure.
Precise control. Each process has its own operating characteristics and allowable work values that must be followed.
Internal pressure affects the boiling point. For better rectification of alcohol, you need to keep the pressure in the range of 720-780 mm. rt. Art. If this is not controlled, the pressure will decrease, and this will reduce the vapor density, which will lead to the "flooding" of the column. A similar situation with high pressure, which is unacceptable for effective work equipment.

Distillation column includes nozzles, cylinders, distillers and cube. Stainless food grade alloy is used for the column

Companies are increasingly installing a distillation column, the principle of which is based on the flow of liquid and the rise of steam, which is necessary to achieve an equilibrium that allows the separation of pure components of substances (liquids with a low boiling point come first, then with a high one). The key to this process is a state of equilibrium.

2 Modern column design - how to understand it?

It has the form of a cylinder of variable or constant section with nozzles and plates located inside. Each drawing takes these elements into account when constructing the column. Auxiliary units are installed in each column for the receipt of raw alcohol, as well as for the control and selection of the final product.

Main characteristics:

raw alcohol is the result of distillation of mash after distillation (moonshine at 35 degrees);
phlegm - the resulting steam flowing down the column;
phlegm number - the ratio of steam to distiller.

The distillation column is used in industrial and laboratory processes. It has effectively proven itself in the petrochemical, gas, oil refining, brewing, chemical and other industries. The principle of operation of the design is based on the appearance of two counter flows in the form of steam and a flowing liquid. Between them there is contact in special plates, while the temperature of the vapor will be higher than that of the liquid.

The operating scheme of the distillation plant is based on continuous and periodic operation. In the first case, the raw material enters and leaves the plant in a cyclic process. In periodic work, substances are supplied in doses and undergo rectification until the desired result is achieved.

Classification of the internal volume of the column: evaporative, strengthening and exhaustive. The feed liquid evaporates and is transferred to the middle volume of the column. This mixture is heated and partially evaporated on a heated plate. In this process, light particles are mixed with phlegm, because of which they become heavier and flow down. In the upper part of the column there is a strengthening part, in the body of which the steam is enriched with light fractions. In the lower part there is an exhaustive stage, where phlegm flows and light fractions are discharged.

3 Operation of the distillation unit – how to achieve the best result?

Since the alcohol processing system works on the principles of condensation of incoming substances, it is required to comply with the rectification technology. This is necessary for the equilibrium of vapors and mixtures in order to ensure their effective purification. In the case of intermittent heating systems (used for low workloads), a heating element is located on the bottom of the fraction, which starts the process. Rectification can be carried out not only with condensate - vacuum can be used for this, action atmospheric pressure or low temperature.

The distillation column is effective tool alcohol purification. On its basis, home appliances are designed to clean alcohol-containing mixtures. During this process, the organoleptic qualities may deteriorate, but in this case, the lower fractions can be returned to the alcohol. A responsible approach to the process and compliance with the norms will allow you to get high-quality purified alcohol. Good luck with this!

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Do-it-yourself distillation column is made on the basis of the scheme. The diagram is needed in order not to make mistakes. It contains not large volumes when compared with other devices that reach 19 meters. A distillation column made at home, its design and the mechanism itself cannot be characterized as easy - it consists of many components. Initially, you should buy a metal tube - its length is ideally about 119-149 cm.

Instead of a reflux condenser, it is allowed to use an ordinary thermos. In addition, you will need:

adapters that will combine the tube with tanks;
Insulation and stainless steel sheet for the production of main washers;
A small reinforcing tube used to drain water;
cooling mechanism.

From the devices you will need a hammer, a drill with a drill, pliers, a file, hard paper, a soldering iron with solder or flux, a transitional device to a faucet, a rubber tube of small parameters and a temperature gauge.
Homemade apparatus is produced according to established scheme. The tube must have the desired length, and its tips must be polished. For the purpose of arranging the tube and the distillate unit, a euro adapter is used. The union of the pipe and the cube should be soldered, and part of the soldering later requires stripping.

Then you need to make metal nozzles that fill the pipe right up to the very top. Now the main washer is introduced into the pipe, a small end of the selection is introduced into it. The section of connecting points is soldered. The next step will be the thermal insulation of the pipe.

A thermos that will be used as a reflux condenser must be considered and removed from the bottom. The inner test tube must be removed from the outside and the vacuum cover of the thermos removed. A passage should be made in the test tube, in the central part of the very bottom of the part and in the main place of its rear edge.
Through the upper passage, you need to mount the pipe and seal it there. Then the base is placed on the cone.

In the outer flask, in addition, holes are made for the tubes for the entry and exit of water. They are located at the top and bottom of the tube. Zones must be fixed. In the distillate extraction unit, it is necessary to make a passage for the purpose of the temperature indicator bushing. The distillation column is created with special care so as not to harm your health.

In our generation, a small distillation column is quite relevant. This device is publicly available to absolutely everyone, and the device requires a little space. The drawing of the industrial production of a distillation column is a bit complicated for ordinary people. However, the manufacture of alcohol in living conditions happens quite often, and many people practice it.

The distillation column model needs a large number of trays in order to obtain the highest quality product. This greatly complicates the installation process. To make this kind of apparatus, like a distillation column, with my own hands at home, you will need some details. The cooling mechanism is made from a reddish-yellow tube. In order to do this, it is necessary to wrap the rectifier column with it.

Iron washcloths are made from stainless steel. The period of validity and their reserve of use in the distillation column is quite long. In existing 9.8 cm pipes, you need to take 1 washcloth. A good idea, use a medical clamp with a dropper, you can take it instead of a tap. The scheme of the distillation column, as a rule, is completed with a tube, in order to interconnect with environment.

The essence of the column

If we briefly discuss the system of alcohol production and rectification, then this is, in fact, the repeated distillation of the mash, which takes place in special plates. Instead, they usually use all sorts of components. In order to produce alcohol at home, a distillation column with a diameter of 3 to 5 cm, an iron sponge can be used as a connecting component. It is through it that the distillation column for moonshine still will be filled.

During the operation of the distillation column, the distillate smoothly descends to the bottom, and the evaporation rises upward. A rectifier is needed in order to raise degrees. Separate modifications of this device involve the use of a boiler and a cool fluid jet in order to cool. All elements of the device may well be combined with each other using an ordinary soldering tool. Slight differences in volumes in the production of a unit so necessary in the economy will not particularly affect the quality of the product.

However, in order to increase the amount of alcohol, it is necessary to significantly increase the volume of the distillation device, a 1.5 m column tube, guarantees up to 28 liters of alcohol element, in about two days. Upon completion of the production of the apparatus, it is necessary to coat all connections with a detergent. In a similar way, it is allowed to examine the extra holes, if there are bubbles appear. When a water-steam cooler is connected to a tube through which water enters and whether there are holes during operation, it is a column-type system.

All of the above makes it possible to realize what kind of homemade apparatus And why do people need it at all. With a distillation column, you have the opportunity to get pure alcohol. In addition, we can conclude that it is not at all difficult to create an apparatus with your own hands - you just need to carefully read the instructions. It is also enough to have a strong desire, and the necessary details to create it. Everyone decides for himself what is better - to buy alcohol or make it at home, because there will be no harmful additives in such moonshine, and its quality depends solely on the distillation structure.

Due to the special structure of the distillation column, it becomes possible to almost completely purify the final drink from fusel oils and impurities. Unlike distillation, the quality of the raw material itself does not play such a key role, since there is practically no organoleptic in the final drink. The result is alcohol with a strength of up to 96.6% with a poor organoleptic, but pure. It can be used for the production of vodka and various tinctures.

Consider the principle of distillation column device, and what parts it consists of.

Distillation column, drawing

Distillation column, principle of operation

Rectification is the separation of binary or multicomponent mixtures due to countercurrent mass and heat exchange between vapor and liquid. Parts of the distillation column provide a consistent process:

Evaporation cube - storage and heating of the bottom liquid
Column - heat and mass transfer inside the column itself due to packing
Dephlegmator - vapor condensation, phlegm formation
Selection node - selection of reflux and rectificate

Consider the work of each part separately.

Evaporation Cube

This is a container in which mash or distillate is stored and heated. It is also called bottom liquid. When heated, the liquid evaporates, and the vapor rises up the column, where it is separated into fractions. At the same time, the cube serves as the base for the column. The cube can be heated on a regular or. On induction - faster and safer.

Also used as a heat source in some models.

Usually, the mash is first distilled to get raw alcohol. The column must be switched to the distiller mode, that is, the selection tap should be opened as much as possible. After that, the raw alcohol is distilled again, this time slowly and with the selection of the food fraction.

A thermometer is located on the cube to control the temperature of the bottom liquid. Upon reaching 60-70 ° C in the cube, it is necessary to supply coolant so that the vapors can condense. Upon reaching 70°C, the power of the heating element must be reduced and left at this value until the rectification is completed.

Tsarga

The tsarga is the body of the column, its central part. Heat and mass transfer, which is the principle of operation of the distillation column, takes place here. It is she who makes the rectification process possible:

The liquid in the cube evaporates, and the vapor rises up the column
At the top is a reflux condenser (refrigerator), in which the steam condenses
The distillate flows down the reflux condenser and along the walls of the column
The liquid is in contact with the vapor on the walls of the packing with which the column is filled.
As a result of heat and mass transfer, the most light-boiling fraction accumulates in the upper part of the column
The low-boiling fraction is condensed in the refrigerator and enters the selection channel.

The column can be assembled from several kings. The higher the column, the more intense the heat and mass transfer takes place, and the cleaner the liquid is divided into fractions. Inside the column is filled with packing: SPN or RPN. Without a nozzle, heat and mass transfer is impossible.

To speed up the rectification process, you can use. The walls of the column are heated, so the phlegm, which is not in contact with the packing, evaporates from the walls. As a result, the process is accelerated, and the degree of purification is increased.

Additionally, they can be used with a column. Heat-mass-exchange between hot vapor and cold phlegm also takes place on its surface. The degree of purification is increasing.

Distillation nozzle

The distillation nozzle is a universal tool that consists of a sampling unit and a refrigerator. In the refrigerator, alcohol vapor condenses, which returns down in the form of phlegm. The selection node allows you to control the amount of alcohol that comes out of the column. By controlling this volume, you can change the quality of alcohol, that is, the degree of its purification. The slower the process, the purer the alcohol.

The nozzle can be bought ready-made or separately.

Alcohol selection unit

Used to improve the quality of cleaning

Automation for distillation column

Rectification requires constant monitoring so that the head and tail fractions do not get into the food part. This process can be facilitated by using the BUR - rectification control unit. The block will limit the selection of rectified product in accordance with the given program so that the tail part does not mix with the food. So you can move away from the column without fear that the tails will fall into clean rectificate.

BUR is an optional part of the distillation column, but it is much more convenient to work with it.

What's next

The resulting alcohol-rectified will have a harsh taste. Alcohol must be diluted, filtered and allowed to brew. You can use alcohol to clean it, it's called. As a result of carbonization, alcohol acquires a milder taste, coal binds the remains of fusel oils, which in a small amount penetrate into the drink even during fractional selection in a distillation column. This is how classic Russian vodka is prepared.

After sorting (dilution) and carbonization, alcohol should rest in a glass container for several days.

Read more about the device and operation of the distillation column in the corresponding product card.

Rectification- this is a method of separating the components of a mixture, based on the property of the components of this mixture to boil away at different temperatures.

Rectification is a process of separating binary, multicomponent or continuous mixtures into practically pure components or their mixtures (fractions) that differ in boiling points (for binary and multicomponent mixtures) or boiling ranges (for continuous mixtures).

The analysis of oil products for the content of individual hydrocarbons and their classes shows that oil and its fractions are a complex multicomponent mixture. The number of components in oil exceeds 2000. Due to the large number of components, oil is considered to be a continuous mixture and its composition is expressed by the true boiling point curve (TBC), which has a smooth, continuous character.

Therefore, the distillation process is a mass transfer that flows in both directions between the 2 phases of the mixture, one of which is liquid, and the other is steam. In other words, this is a repeatedly repeated contact interaction of non-equilibrium phases in the form of liquid oil, as well as steam.

The rectification process is carried out as a result of the contact of vapor and liquid flows. In this case, an indispensable condition is the movement of vapor and liquid towards each other along the height (length) of the distillation apparatus. The driving force of heat and mass transfer between vapor and liquid in the apparatus is the temperature difference along the height (length) of the apparatus.

Stripping columns, their classification and principle of operation

A distillation column is one of the central units of a process plant for the primary processing of oil or oil products. The use of this device is caused by the need to implement easy way separation of oil or its products into fractions depending on their boiling points. This method is called rectification, and the apparatus for carrying out this process is called a distillation column.

But one distillation column cannot cope with the tasks of fraction separation. At oil refineries, the column is closely connected with a variety of other equipment - pumping, heat exchange, furnace, separation.

It is most convenient to illustrate the principle of operation of a distillation apparatus using the example of a column with bubble caps.

distillation columns

Heat and mass transfer between countercurrently moving nonequilibrium vapor and liquid phases in distillation is carried out on contact devices (CD), which are often called “plates”.

In distillation columns, the steam reflux flow is created heating elements(furnace, input of superheated water vapor), and liquid - condensation devices (cold circulating irrigation).

As a result of the interaction between the vapor and liquid phases at the HPC, in accordance with the laws of thermodynamic vapor-liquid equilibrium, the vapor phase is enriched in light-boiling components, and the liquid phase is enriched in heavy-boiling components. Therefore, it is CA that largely determines the overall efficiency of the separation process.

For oil columns in general and for ABT columns, in particular, a number of characteristic features inherent in them can be distinguished:

very high raw material productivity (up to 1000 m 3 /h for atmospheric column);
heat supply to the separating system is carried out by fire heating of raw materials in a tubular furnace (main and vacuum columns AVT), introduction of superheated water vapor (practically all columns) and circulation of a “hot jet” (AT topping column);
the latter circumstance involves the use of special separation zones for separating the vapor and liquid phases;
The distillation scheme includes remote stripping sections, as well as circulating refluxes, which implies the possibility of organizing lateral liquid phase withdrawals and supplies of both vapor and liquid phases at several points along the height of the column.

By the way, read this article too: Liquid distributors

These features should be taken into account when choosing the designs of contact devices in the problems of designing oil separation units.

The principle of operation of the distillation column

The design of the distillation column is a vertical cylindrical container of various or constant cross section, which is used to physically separate a mixture of hydrocarbons and obtain the required oil products of a given quality as a result of rectification.

In the column, vapors move upward from tray to tray due to the pressure difference in the evaporative space and at the top of the column. The liquid flows down the trays and downcomers by gravity.

The distillation column can be divided into 3 functional parts:

Concentration section - located above the point of entry of raw materials into the apparatus
Feed section - in the center of the column, raw materials are fed to the feed plate
Stripping section - located below the input point of raw materials

Column feed section

concentration section

Stripping section

For the rectification process to proceed, the temperature of the oil must be lower than the temperature of the supplied steam. This consequence proceeds from the properties of an equilibrium system. If the oil temperature were equal to or lower than the steam temperature, the rectification process would be impossible.

The rectification process can only be carried out for mixtures with different boiling points to enable the diffusion separation process to be carried out. To do this, the liquid moves from top to bottom, and the vapor moves from bottom to top to provide best contact and phase interaction.

Classification of distillation columns

Column devices can be divided depending on the technological process:

Atmospheric and vacuum distillation (oil and fuel oil);
Secondary distillation of gasoline;
Stabilization of oil, gas condensate, unstable gasoline;
Fractionation of refinery, oil and natural gases;
Distillation of solvents during oil refining processes;
Separation of products of thermodestructive and catalytic processes of processing oil raw materials and gases, etc.;

By the way, read this article too: Packed and tray columns

Types of contact devices of distillation columns

To carry out the rectification process in column apparatuses, contact devices are necessarily used:

Packed;
Poppet ;
Rotary.

Rotary columns are not widely used, while tray and packed columns are very popular.

Plate with cap contact devices

Video: device and operation of the distillation column

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Sooner or later, almost every homemade alcohol lover thinks about purchasing or manufacturing a distillation column (RK) - a device for obtaining pure alcohol. You need to start with a comprehensive calculation of the basic parameters: power, height, drawer diameter, cube volume, etc. This information will be useful both for those who want to make all the elements with their own hands, and for those who are going to buy a ready-made distillation column (it will help you make a choice and check the seller). Without affecting design features individual nodes, we will consider general principles building a balanced system for rectification at home.

Column operation scheme

Characteristics of the pipe (tsargi) and nozzles

Material. The pipe largely determines the parameters of the distillation column and the requirements for all units of the apparatus. The material for the manufacture of the side is chromium-nickel stainless steel - "food" stainless steel.

Due to chemical neutrality, food grade stainless steel does not affect the composition of the product, which is required. Raw is distilled into alcohol from sugar mash or distillation waste (“heads” and “tails”), therefore the main purpose of rectification is to maximize the output of impurities, and not change the organoleptic properties of alcohol in one direction or another. It is inappropriate to use copper in classic distillation columns, since this material slightly changes chemical composition drink and is suitable for the production of a distiller (ordinary moonshine) or a beer column (a special case of rectification).

A disassembled column pipe with a nozzle installed in one of the drawers

Thickness. The drawer side is made of stainless steel pipe with a wall thickness of 1-1.5 mm. A thicker wall is not needed, as this will increase the cost and weight of the structure without obtaining any advantages.

Nozzle options. It is not correct to talk about the characteristics of the column without reference to the packing. When rectifying at home, nozzles with a contact surface area of 1.5 to 4 square meters are used. m/liter. With an increase in the area of the contact surface, the separating ability also increases, but the productivity decreases. Reducing the area leads to a decrease in the separating and strengthening ability.

The productivity of the column initially increases, but then, to maintain the strength of the output, the operator is forced to lower the selection rate. This means that there is some optimal size nozzles, which depends on the diameter of the column and will allow you to achieve the best combination of parameters.

The dimensions of the spiral prismatic packing (SPN) should be less than the inner diameter of the column by about 12-15 times. For a pipe diameter of 50 mm - 3.5x3.5x0.25 mm, for 40 - 3x3x0.25 mm, and for 32 and 28 - 2x2x0.25 mm.

Depending on the tasks, it is advisable to use different nozzles. For example, when obtaining fortified distillates, copper rings with a diameter and height of 10 mm are often used. It is clear that in this case the goal is not the separating and strengthening ability of the system, but a completely different criterion - the catalytic ability of copper to eliminate sulfur compounds from alcohol.

Variants of spiral prismatic nozzles

You should not limit your arsenal to one, even the best nozzle, there are simply no such ones. There are the most suitable for each specific task.

Even a small change in the column diameter seriously affects the parameters. To evaluate, it is enough to remember that the nominal power (W) and productivity (ml / h) are numerically equal to the area cross section columns (sq. mm), and therefore proportional to the square of the diameter. Pay attention to this when choosing a drawer, always consider the inner diameter and compare options using it.

Dependence of power on pipe diameter

Pipe height. To ensure good holding and separation capacity, regardless of the diameter, the height of the distillation column should be from 1 to 1.5 m. If it is less, there will not be enough space for the fusel oils accumulated during operation, as a result, the fusel oil will begin to break into the selection. Another drawback is that the heads will not be clearly divided into fractions. If the pipe height is greater, this will not lead to a significant improvement in the separating and holding capacity of the system, but will increase the driving time, as well as the number of "heads" and "headrests". decreases. The effect of increasing the pipe from 50 cm to 60 cm is an order of magnitude higher than from 140 cm to 150 cm.

The volume of the cube for the distillation column

In order to increase the yield of high-quality alcohol, but to prevent overfilling of the fusel column, the bulk (filling) of raw alcohol in the cube is limited in the range of 10-20 packing volumes. For columns 1.5 m high and 50 mm in diameter - 30-60 l, 40 mm - 17-34 l, 32 mm - 10-20 l, 28 mm - 7-14 l.

Taking into account the filling of the cube by 2/3 of the volume, a 40-80 liter container is suitable for a column with an inner diameter of a tsarga of 50 mm, a 30-50 liter container for 40 mm, a 20-30 liter cube for 32 mm, and a pressure cooker for 28 mm.

When using a cube with a volume closer to the lower limit of the recommended range, you can safely remove one drawer and reduce the height to 1-1.2 meters. As a result, there will be relatively little fuselage for a breakthrough in the selection, but the volume of “head restraints” will noticeably decrease.

Source and power of column heating

Plate type. The moonshine past haunts many beginners who believe that if they previously used a gas, induction or conventional electric stove to heat the moonshine, then you can leave this source for the column.

The rectification process is significantly different from distillation, everything is much more complicated and the fire will not work. It is necessary to ensure smooth adjustment and stability of the supplied heating power.

Electric stoves operating on a thermostat in start-stop mode are not used, because as soon as a short-term power outage occurs, the steam will stop going into the column, and the phlegm will collapse into a cube. In this case, you will have to start rectification again - with the work of the column for yourself and the selection of "heads".

An induction cooker is an extremely rough apparatus with a step change in power of 100-200 W, and during rectification, you need to change the power smoothly, literally by 5-10 W. Yes, and it is unlikely that it will be possible to stabilize the heating, regardless of the voltage fluctuation at the input.

A gas stove with 40% raw alcohol poured into a cube and a 96-degree product at the outlet is a mortal danger, not to mention fluctuations in the heating temperature.

The optimal solution is to embed a heating element of the required power into the cube, and use a relay with output voltage stabilization, for example, RM-2 16A, to adjust. You can take analogs. The main thing is to get a stabilized voltage at the output and the ability to smoothly change the heating temperature by 5-10 watts.

Power supplied. In order to heat the cube in an acceptable time, one must proceed from a power of 1 kW per 10 liters of raw alcohol. This means that for a 50 l cube filled with 40 liters, a minimum of 4 kW is required, 40 l - 3 kW, 30 l - 2-2.5 kW, 20 l - 1.5 kW.

With the same volume, cubes can be low and wide, narrow and high. When choosing a suitable container, it should be taken into account that the cube is often used not only for rectification, but also for distillation, therefore, they proceed from the most severe conditions so that the input power does not lead to rapid foaming with splashes from the cube into the steam pipeline.

It has been experimentally established that at a heating element placement depth of about 40-50 cm, normal boiling occurs if per 1 sq. cm bulk mirrors account for no more than 4-5 watts of power. With a decrease in depth, the allowable power increases, and with an increase, it decreases.

There are other factors that affect the nature of boiling: the density, viscosity and surface tension of the liquid. It happens that emissions occur at the end of the mash distillation, when the density increases. Therefore, conducting the rectification process at the border of the permitted range is always fraught with trouble.

Common cylindrical cubes have a diameter of 26, 32, 40 cm. Based on the allowable power for the surface area of the cube bulk mirror of 26 cm, the cube will work normally with a heating power of up to 2.5 kW, for 30 cm - 3.5 kW, 40 cm - 5 kW .

The third factor that determines the heating power is the use of one of the tsarg columns without a nozzle as a dry steamer to combat splashing. To do this, it is necessary that the steam velocity in the pipe does not exceed 1 m / s, at 2-3 m / s the protective effect weakens, and at large values the steam will drive the phlegm up the pipe and throw it into the selection.

Formula for calculating steam speed:

V \u003d N * 750 / S (m / s),

N – power, kW;
750 - vaporization (cub. cm / sec kW);
S is the cross-sectional area of the column (sq. mm).

A pipe with a diameter of 50 mm will cope with spray when heated up to 4 kW, 40-42 mm - up to 3 kW, 38 - up to 2 kW, 32 - up to 1.5 kW.

Based on the above considerations, we select the volume, cube dimensions, heating and distillation power. All these parameters are coordinated with the diameter and height of the column.

Calculation of the parameters of the dephlegmator of the distillation column

The power of the reflux condenser is determined depending on the type of distillation column. If we build a column with liquid extraction or steam below the dephlegmator, then required power must not be less than the nominal power of the column. Usually in these cases, a Dimroth refrigerator with a utilization power of 4-5 watts per 1 sq. see surface.

If the steam extraction column is higher than the reflux condenser, then the calculated capacity is 2/3 of the nominal one. In this case, you can use Dimroth or "shirt". The utilization power of the shirt is lower than that of the dimroth and is about 2 watts per square centimeter.

An example of a Dimroth cooler for a column

Further, everything is simple: we divide the rated power by the utilization one. For example, for a column with an inner diameter of 50 mm: 1950/5= 390 sq. cm area of Dimroth or 975 sq. see shirt. This means that the Dimrot refrigerator can be made from a 6x1 mm tube 487 / (0.6 * 3.14) = 2.58 cm long for the first option, taking into account the safety factor of 3 meters. For the second option, we multiply by two thirds: 258 * 2/3 = 172 cm, taking into account the safety factor of 2 meters.

Column shirt 52 x 1 - 975 / 5.2 / 3.14 \u003d 59 cm * 2/3 \u003d 39 cm. But this is for rooms with high ceilings.

"Shirtman"

Calculation of a once-through refrigerator

If the straight-through is used as an aftercooler in a distillation column with liquid withdrawal, then choose the smallest and most compact option. Enough power is 30-40% of the nominal power of the column.

A once-through cooler is made without a spiral in the gap between the jacket and the inner pipe, then the selection is started into the jacket, and the cooling water is supplied through the central pipe. In this case, the shirt is welded onto the water supply pipe to the dephlegmator. This is a small "pencil" about 30 cm long.

But if the same straight-through is used both for distillation and for rectification, being a universal unit, they do not proceed from the need of the Republic of Kazakhstan, but from the maximum heating power during distillation.

To create a turbulent steam flow in the refrigerator, which makes it possible to ensure a heat transfer rate of at least 10 watts / sq. cm, it is necessary to provide a steam speed of about 10-20 m / s.

The range of possible diameters is quite wide. The minimum diameter is determined from the conditions of not creating a large overpressure in the cube (no more than 50 mm of water column), but the maximum by calculating the Reynolds number, based on the minimum speed and maximum coefficient of kinematic viscosity of vapors.

Possible design of a once-through refrigerator

In order not to go into unnecessary details, here is the most common definition: “In order for the turbulent mode of steam movement to be maintained in the pipe, it is sufficient that the inner diameter (in millimeters) be no more than 6 times the heating power (in kilowatts).”

To prevent the water jacket from airing, it is necessary to maintain a linear water velocity of at least 11 cm / s, but an excessive increase in speed will require high pressure in the water supply. Therefore, the range from 12 to 20 cm/s is considered optimal.

To condense the steam and cool the condensate to an acceptable temperature, water must be supplied at 20°C at a rate of about 4.8 cc/s (17 liters per hour) for every kilowatt of power input. In this case, the water will heat up by 50 degrees - up to 70 ° C. Naturally, less water will be needed in winter, and when using autonomous cooling systems, about one and a half times more.

Based on the previous data, the annulus cross-sectional area and the inside diameter of the jacket can be calculated. It is necessary to take into account the available assortment of pipes. Calculations and practice have shown that a gap of 1-1.5 mm is quite sufficient to comply with all necessary conditions. This corresponds to pairs of pipes: 10x1 - 14x1, 12x1 - 16x1, 14x1 - 18x1, 16x1 - 20x1 and 20x1 - 25x1.5, which cover the entire power range used at home.

There is another important detail of the straight-through - a spiral wound on a steam pipe. Such a spiral is made of wire with a diameter that provides a gap of 0.2-0.3 mm to the inner surface of the shirt. It is wound with a step equal to 2-3 diameters of the steam pipe. The main purpose is to center the steam pipe, in which, during operation, the temperature is higher than in the jacket pipe. This means that as a result of thermal expansion, the steam pipe lengthens and bends, leaning against the jacket, dead zones appear that are not washed by cooling water, as a result, the efficiency of the refrigerator drops sharply. Additional advantages of spiral winding are the lengthening of the path and the creation of turbulence in the cooling water flow.

A well-made straight-through can utilize up to 15 watts / sq. cm of the heat exchange area, which is confirmed by experience. To determine the length of the cooled part of the direct flow, we use a rated power of 10 W / sq. cm (100 sq. cm / kW).

The required heat exchange area is equal to the heating power in kilowatts multiplied by 100:

S = P * 100 (sq. cm).

Steam pipe outer circumference:

Locr = 3.14 * D.

Cooling jacket height:

H = S / Len.

General calculation formula:

H = 3183 * P / D (power in kW, height and outer diameter of the steam pipe in millimeters).

An example of the calculation of a straight pipe

Heating power - 2 kW.

It is possible to use pipes 12x1 and 14x1.

Sectional areas - 78.5 and 113 square meters. mm.

Steam volume - 750 * 2 \u003d 1500 cubic meters. cm / s.

Steam velocities in pipes: 19.1 and 13.2 m/s.

The 14x1 pipe looks preferable, as it allows you to have a power margin, while remaining in the recommended steam speed range.

The steam pipe for the shirt is 18x1, the annular gap will be 1 mm.

Water supply rate: 4.8 * 2= 9.6 cm3/s.

Annular gap area - 3.14 / 4 * (16 * 16 - 14 * 14) = 47.1 sq. mm = 0.471 sq. cm.

Linear speed - 9.6 / 0.471 = 20 cm/s - the value remains within the recommended limits.

If the annular gap were 1.5 mm - 13 cm / s. If 2 mm, then the linear speed would drop to 9.6 cm / s and water would have to be supplied above the nominal volume, solely so that the refrigerator does not air up - a waste of money.

Shirt height - 3183 * 2 / 14 = 454 mm or 45 cm. The safety factor is not needed, everything is taken into account.

Result: 14x1-18x1 with a height of the cooled part 45 cm, nominal water flow - 9.6 cubic meters. cm/s or 34.5 liters per hour.

With a rated heating power of 2 kW, the refrigerator will produce 4 liters of alcohol per hour with a good margin.

An efficient and balanced straight-through distillation should have a ratio of extraction rate to heating power and water consumption for cooling 1 liter / hour - 0.5 kW - 10 liters / hour. If the power is higher, there will be large heat losses, if it is small, the useful heating power will decrease. If the water flow is higher, the direct flow is inefficiently designed.

The distillation column can be used as a wash column. Equipment for mash columns has its own characteristics, but the second distillation differs mainly in technology. For the first distillation, there are more features and individual nodes may not be applicable, but this is a topic for a separate discussion.

Based on real household needs and the existing range of pipes, we will calculate typical options for a distillation column using the above method.