Why is a distillation column needed? How to make a distillation column

After familiarizing myself with popular sites and forums on rectification topics, I decided to make my contribution to the common cause. Home craftsmen struggle with columns and attach a lot of automation to them. Pressure sensors, start-stop systems that disrupt the entire rectification process, etc.

The main problems lie in low altitude, incorrect calculations of installations, work at gas stove, focusing on the pressure in the column, and simply a banal misunderstanding of the essence of the rectification process. And what’s most important is that everyone completely forgets that the correct column does not require automation. Automation is only an assistant.

The given diagram of a distillation column is one of six options for solving the above problems. The “trick” is that you can make it low (super low) and get quite high-quality alcohol. Let me make a reservation... working on a gas stove is dangerous, the slightest mistake can lead to irreparable consequences - you have been warned. The stability of the operation of a specific circuit solution lies in the so-called. storage tank under the reflux condenser shifted to the side, by adjusting the power supply (heating) in the cube, cooling and reflux return, you can reach a stable alcohol shelf with a nozzle height of only 80 cm. There is no temperature saw in the column due to the impossibility of splashes getting on the thermometer sensor. The hydraulic level installed in the selection unit allows you to monitor the level of accumulated reflux, which allows you to more accurately stabilize the process at the beginning of rectification and eliminates column flooding during proper operation. The accumulative “glass” is borrowed from the well-known device of the same name (Soxhlet Extractor).. Franz von Soxhlet

While developing design ideas, you can also work with automation. Instead of a selection regulator, you can install an electronic valve by connecting it through a comparator that takes temperature readings. Thus, the column turns into an ultra-small batch column with fractional selection. The comparator is programmed to open the valve at a certain temperature, the valve opens, the accumulated reflux is drained into the receiving tank, after which the process in the column will break down and the temperature will rise, and the comparator will close the valve. Of course, you can open and close it by hand, but the process is tedious. Thus, on the column you can select all the substances in turn; the process is described in a little more detail

2.2. Design and operation of distillation columns,

Rectification of simple and complex mixtures is carried out in batch or continuous columns.

Batch columns are used in low-capacity installations when it is necessary to select a large number of fractions and have high separation clarity. Classic scheme such an installation is shown in Fig. 4. The raw material enters the distillation cube 1 to a height of about 2/3 of its diameter, where it is heated with deep steam. During the first period of operation of the distillation unit, the most volatile component of the mixture is selected, for example, benzene head, then, by increasing the distillation temperature, components with more high temperature boiling (benzene, toluene, etc.). The highest boiling components of the mixture remain in the cube, forming a bottom residue. At the end of the rectification process, this residue is cooled and pumped out. The cube is again filled with raw materials and rectification is resumed. The frequency of the process results in higher heat consumption and lower productivity of the installation. Further in the figure: 2 - distillation column, 3 - condenser-refrigerator, 4 - battery, 5 - refrigerator, 6 - pumps.

The continuous installation does not have many of these disadvantages. A schematic diagram of such an installation is shown in Fig. 5. The raw material goes through heat exchanger 1 to heater 2 and then to different levels distillation column 3. The lower fractions are heated in the boiler 4 and discharged back into distillation column. In this case, the heaviest part is removed from the boiler to the bottom of the column and, together with the liquid sediment, for further processing of heavy fractions. And the light fractions go from above to the condenser-refrigerator 5, and then from the battery 6, partly back to the column for irrigation, and partly to further processing of the light fractions.

Depending on the number of products obtained, simple and complex distillation columns are distinguished. In the first, rectification produces two products, for example gasoline and semi-fuel oil. The second ones are designed to produce three or more products. They are series-connected simple columns, each of which separates the mixture entering it into two components.

Each simple column has stripping and concentration sections. The stripping or stripping section is located below the raw material input. The plate on which the raw material is supplied for separation is called the feed plate. The target product of the stripping section is the liquid residue. The concentration, or strengthening, section is located above the food plate. The target product of this section is rectified vapor. For normal operation distillation column requires the supply of irrigation to the top of the concentration section of the column and the introduction of heat (through a boiler) or hot water vapor into the stripping section.

Depending on the internal device that ensures contact between rising vapors and descending liquid (reflux), distillation columns are divided into packed, plate, rotary, etc. Depending on the pressure, they are divided into distillation columns high pressure, atmospheric and vacuum. The former are used in the processes of stabilization of oil and gasoline, gas fractionation in cracking and hydrogenation plants. Atmospheric and vacuum distillation columns are mainly used in the distillation of oils, residual petroleum products and distillers.

For uniform distribution of vapors and liquids in packed columns akh - 1 (Fig. 6.) as a nozzle - 2 use balls, prisms, pyramids, cylinders from various materials(usually from compressed coal dust) with an outer diameter from 6 to 70 mm and a surface area to volume ratio of 500. The nozzle is placed in bulk on special plates - 4 with holes for the passage of vapors and drainage of reflux - 3. The purpose of using the nozzle is to increase the contact area phlegm and vapor for mutual enrichment. For proper operation of a packed column, it is very important that the flowing reflux and vapors be uniformly distributed over the entire cross-section of the column. This is favored by the homogeneity of the packing body, the maximum possible speed of the ascending vapor flow, evenly distributed packing layers and the strict verticality of the column. In practice, the uniform distribution of vapor and reflux initially achieved is violated, since the vapor tends to push the liquid toward the walls of the column and move through the center of the nozzle. In this regard, the nozzle is divided into several layers, and the plates on which the nozzle is placed have a special design that allows the flows to be evenly redistributed after each layer of the nozzle. The efficiency of using packed columns is very high, but there are also inconveniences: the packing periodically has to be removed from the column in order to clean it from resinous particles that cover the packing over time and impair its wettability, in addition, the use of packed columns puts forward a very strict requirement to maintain a certain steam pressure and the amount of incoming reflux . If the steam pressure in the column drops, the reflux flow accelerates and the area of contact between the steam and the liquid sharply decreases. If the steam pressure is exceeded, the flow of reflux slows down, which leads to its accumulation in the upper layers of the packing and trapping of vapor in the lower part of the column (“flooding” of the column). This leads to an even greater increase in steam pressure at the bottom of the column, and, at a critical moment, steam breakthrough through the reflux to the top of the column. The consequence of “flooding” of the column is also a sharp decrease in the area of contact between steam and liquid.

In tray columns 1 (Fig. 7), to increase the area of contact between steam and reflux flows, a large number of specially designed trays are used instead of packing. Reflux flows from plate to plate through drain pipes 3, and partitions 4 maintain a constant level of the liquid layer on the plate. This level allows you to constantly keep the edges of the caps 2 immersed in reflux. The partitions allow only excess incoming reflux to flow onto the next plate. The principle of operation of a tray column is the mutual enrichment of vapor and reflux due to the passage of vapor under pressure from the bottom up through a layer of reflux on each tray. Due to the fact that steam passes through reflux in the form of tiny bubbles, the contact area between steam and liquid is very high.

The designs of the plates are varied. Mesh, lattice, cascade, valve, injection and combination trays are used. The design of the plates is selected based on specific technological requirements(degree of clarity of fraction separation, requirement for work intensity, need to change the internal structure of the column, frequency of preventive and repair work, etc.)

In some oil refining processes (for example, refining with associated separation of water (vapor), refining with preliminary separation of the heaviest fractions of oil) rotary columns 1 (Fig. 8) with high productivity are used. The plates of such a column are conical shields with an inclination angle of 40°, with alternating plates attached to the walls of the column - 2 and plates attached to the central rotating shaft - 3. Thus, rotating plates alternate with stationary ones. The rotation of the plates occurs from the drive - 4 at a speed of 240 rpm. Phlegm descends from above 5 along a stationary plate and at the center flows onto the underlying rotating plate. Under the influence of centrifugal force, reflux moves along the rotating plate up to its periphery and, in the form of a continuous annular film, passes to the walls of the column body and further to the underlying plate. Then the process is repeated. Vapors move through the phlegm in a countercurrent manner. Besides a large number of phlegm is constantly in suspension, which leads to high evaporation of the phlegm itself. The distance between the plates is only 8 - 10 mm, which allows you to build a very compact column with high (over 85%) efficiency. Heated raw materials are introduced into the column, the required temperature of which is maintained by heater - 6. This design is very convenient to use, practically does not require repairs or maintenance work, is durable and not so sensitive to changes in temperature and pressure of the initial components.

Calculation of the amount of costs required to implement this project into production. Assess the change in the cost of products obtained in the workshop for primary oil refining and bitumen production. There are two furnaces installed in the workshop: for heating oil P-1 and for heating fuel oil and steam P-3; after reconstruction, a furnace should be installed that will completely replace both furnaces P-1 and P-3. Furnace performance...

Gasoline can be used as a raw material (to produce liquefied gas); kerosene-solar fractions and vacuum distillates (for the production of gasoline, jet and diesel fuels); residual products of oil refining (for the production of gasoline and jet and diesel fuel); slack and paraffins (for producing high-index oils); high-sulfur oils, sulfur and high-sulfur fuel oils (for...

Processes of separating oil into fractions, when its potential capabilities in terms of the range, quantity and quality of products and intermediates obtained are used - oil distillation; Secondary processes include processes of destructive oil refining and petroleum products purification, intended to change its chemical composition by thermal and catalytic action. Using these methods...

IN Lately quite a lot of people do not trust the quality of alcohol offered by stores, and the cost of such products is high. Therefore, you can often see a moonshine still in kitchens next to various household appliances. After all, homemade alcohol-containing drinks are environmentally friendly and less harmful to health in reasonable quantities. However, all distillers face a problem: purifying alcohol from harmful impurities and unpleasant odor. Experienced and economical owners use a distillation column for this. Well, for beginners, in order to keep up with more advanced distillers, you need to find out what a distillation column is in moonshine still.

The rectification column allows the production of alcohol-containing drinks, such as vodka, whiskey, highly purified liqueurs and high strength (up to 97%). The structure of a conventional distillation column is as follows:

Evaporation cube.
A column with a special nozzle in which heat and mass transfer processes take place (tsarga).
Dephlegmator.
Distillate collection unit.

Evaporation cube

The evaporation cube is a container in which the mash is heated. In the process, it evaporates and steam rises up the column. At the top of the rectifier, the liquid is divided into separate fractions.

The evaporation cube is heated on any type of plate. And some of its models require a heating device. A purchased cube must be equipped with a thermometer, which allows you to control the heating of the mash. The evaporation cube is absolutely sealed. During boiling, it is important that the liquid and steam remain inside. The cube cannot be filled with mash more than 2/3 of its volume, otherwise the liquid will splash out of the container.

Tsarga

The following processes occur in this part of the distillation column:

The mash in the cube evaporates under the influence of heat and rises up the column. There is a refrigerator installed there.
The reflux condenser ensures the condensation of alcohol vapor and the production of a distillate.
The distillate descends alcohol column. At this moment, it collides with steam - heat and mass transfer.
As a result of this process, the evaporated part of the fraction goes up the column. Here it condenses and then goes into the selection channel.

Do not forget that if you increase the height of the column, heat and mass transfer takes place more actively. This results in a more rectified alcohol output.

Rectifying nozzle

The rectification nozzle has two parts:

Alcohol selection unit. In an industrial distillation column, this part is equipped with a sight glass, which allows you to determine the rate of alcohol selection.
Dephlegmator. Sometimes this part is called the refrigerator. The reflux condenser is located at the top of the distillation column. It is needed to collect moonshine vapors and turn them into phlegm, which is released downwards. Here it is enriched with alcohol vapor. After the phlegm enters the selection unit, the evaporated part comes out.

The distillation column has a simple structure, so the principle of its operation can be easily explained. This mechanism acts as a filter in which fusel oils. In it there is a constant interaction of alcohol vapor and liquid, in other words, rectification. After the mash warms up to 70 degrees in the evaporation cube, the alcohol begins to evaporate. It rises through the pipe and ends up in the reflux condenser. In this part, re-condensation occurs with steam when cooled with water. The condensate (reflux) drains and meets the hot steam again. An exchange occurs between the two components - the process of saturation of phlegm with steam, and steam with liquid, which has low temperature boiling.

The final condensation of the steam occurs in the refrigerator. The output is purified alcohol, which flows into a receiving container. At the top of the distillation column there is an atmospheric valve. It is needed so that vapors that do not contain alcohol and are not subject to condensation leave the mechanism.

Continuous rectification occurs due to special contact elements - physical plates in purchased distillation columns and metal sponges or glass beads in hand-made samples. These parts are needed to increase the efficiency of interaction between steam and reflux.

Types of columns

There are the following types of distillation columns:

Disc type. Such units have plates inside that are installed at a certain distance. Heat and mass transfer is carried out on them. Distillation columns of this type are expensive and quite cumbersome. But they have the main advantage - factions are separated accurately.
Nozzle type. The mechanism has two types of copper attachment. The first is a scattering of small stainless steel elements filling the column. Their uneven placement complicates the passage of vapors and the outflow of phlegm. The second type is a Panchenkov nozzle, which performs effective heat and mass transfer.

Is it possible to make a full-fledged distillation column with your own hands?

There are convenient and high-quality moonshine stills with a distillation column on sale. But their cost is high. Therefore, men who know how to work with metals can make the unit themselves. To create a column, materials that do not enter into chemical reactions with alcohol and do not release various elements harmful to human health over time. To create the unit you will need:

A container of the required volume as a distillation cube. This can be any copper or enamel vessel. Stainless steel will also work. If there is a small yield of alcohol, then use a pressure cooker.
Column body in the form of a drawer or pipe. On store shelves you can quickly find a ready-made 15-centimeter drawer. Buy several pieces and connect them. Or you can easily make this part from a stainless pipe with a diameter of 0.5 centimeters and a wall thickness of 1.5–2 millimeters. A thread is made on both sides of it: the bottom is attached to the cube, and the top is connected to the reflux condenser. The drawer must be at least one meter in height, otherwise harmful fractions will not be removed, and fusel oils will end up in the distillate. The result will be a product Low quality. If you make a pipe longer than 1.5 meters, the time for rectification will increase, but the efficiency will remain the same.
Dephlegmator for cooling and condensing steam. It can be jacketed or straight-through. Made from two pipes between which water moves. The Dimroth reflux condenser is considered more efficient. The body becomes a pipe, inside of which there is a thin tube in the form of a spiral. It circulates in it cold water. Shell and tube reflux condenser - made of several pipes. In the largest one they attach the small ones. The steam condenses in them.
Nozzles for the drawer. They increase the surface area over which phlegm flows. This means that harmful impurities are deposited and do not enter homemade alcohol. Nozzles in the form of ceramic balls or cut stainless steel kitchen sponges should completely fill the drawer. A Panchenkov nozzle is also used. She is the best option.
Unit for distillate selection.
Fridge. This part is manufactured in the same way as a jacket reflux condenser. But tubes with a smaller diameter are taken. The refrigerator has passages for water. It enters the lower hole, and from the upper hole the liquid is directed through tubes to the dephlegmator.
Small parts to connect the parts.
Thermometer.

The rectification method has both supporters and opponents. It boasts the following positive aspects:

The output is strong alcohol High Quality, which does not contain impurities harmful to human health. He will become an excellent basis for any alcoholic drink.
You can prepare moonshine with the desired organoleptic properties.
The device is quite easy to construct yourself.

Distillers note the following disadvantages:

The entire rectification process takes a long time. Only one liter of distillate is obtained per hour.
Manufacturing designs are expensive.

However, given undoubted benefit columns, it is still worth purchasing. And then there will be no complaints about the quality of moonshine.

A special place among household moonshine stills is occupied by the rectification column, which allows you to create alcohol high level purification and strength (96-98%). When using such a device, in an hour you can produce from 300 to 1000 ml of vodka, absinthe, whiskey, flavored alcohol and various liqueurs.

Previously, this distiller was a multi-meter column, but for convenience, users developed an option with a lower multi-pass distillation rate. The small dimensions of the device allow it to be used both in the country and in a city apartment.

But there is an opinion that the height of the pipe affects the quality of rectification. However, calculate best option it is possible according to the following principle: the height of the column should be equal to 40-60 of its diameters.

Before using a distillation column, it is important to consider that in order to obtain pure product The device must be correctly assembled and adjusted. Despite the fact that the device requires only running water, and you can use a thermos or pressure cooker for assembly, creating a mini-distillery is not so easy. For this reason, many people purchase a ready-made distiller, but there are also those who undertake to build a distillation column with their own hands.

Operating principle of a distillation column

The column is created from materials that do not react with alcohol and do not emit toxic compounds. Inside the column there is a continuous process of exchange of vapor and liquid, which is called rectification.

In theory, the process looks like this: after the liquid boils at the bottom of the device (in the cube), intensive production of steam containing alcohol begins. It, lighter than liquid, rises through the pipe, enters the reflux condenser, undergoes re-condensation due to cooling with water, and then flows down. On its way, the condensate meets the next portion of hot steam and again enters into the exchange process. At this time, the flowing liquid (reflux) is saturated with steam, and the steam is saturated with a liquid with a lower boiling point.

During boiling and condensation, the top of the distillation column fills light steam with the most high concentration alcohol The final condensation of the vapor occurs in the refrigerator, from where the most purified alcohol then flows into the receiving container.

The process of continuous rectification occurs thanks to special contact elements - physical plates in industrial samples and metal sponges or glass balls for home versions of the distillation column. These elements increase the efficiency of interaction between steam and reflux, since they allow the two phases - vapor and liquid - to reach equilibrium in the shortest possible time.

A state of physical equilibrium is achieved immediately after the steam passes through the first contact element. For achievement best result it is important that the column has a diameter of 30 to 50 mm.

The distillation column operates at atmospheric pressure, so an open tube or atmospheric valve is placed at the top of the device. Vapors that did not have time to undergo condensation leave the column with virtually no alcohol in their composition.

What does a column consist of?

Touching on the topic of the industrial version of the distillation column, users note shortcomings of the device. Therefore, many resort to the option of assembling the device with their own hands.

The design of the distillation column is based on several connecting parts (tsargs), which are connected in series to each other:

Threaded elements are sometimes used for joining at the point of selection and connection with the distillation cube, but they create a risk of leakage. Some users suggest putting the elements on top of each other so that they fit as tightly as possible. Another option is to use a sealant, which, however, will not allow the structure to be cleaned in the future.

Assembly instructions

Each step when assembling a distillation column deserves special attention both for safety reasons and to achieve a quality result. Therefore, the points below include recommendations regarding individual column elements:

The distillation column diagram will help you understand the structure of the apparatus and visually represent the assembly process. Some users rely on ready-made diagrams and draw an additional drawing for the clearest execution and understanding of the essence of rectification.

Sequence of working with a column

To start using the device, you need to understand the distillation sequence of the distillate. This question also requires a precise and step-by-step description:

After preliminary distillation of the mash, dilute the raw alcohol with running water. Please note that the lower the alcohol strength, the higher the likelihood of fire.
Pour the alcohol into the still.
Assemble the distillation column and attach it to the cube. For getting quality product the column should be level with the vertical level.
Heat the contents of a thermos, pressure cooker or other container that serves as a distillation cube. Make sure that the distillate tap is in the closed position.
After increasing the temperature in the reflux condenser, reduce the power supplied to the distillation column.
Leave the column in this position for half an hour. This is necessary to start heat and mass transfer.
Turn on the water supply to the refrigerator, and then proceed to select the “heads” (they are not suitable for consumption). Continue until the temperature stabilizes and remains at 78°C. There should be an alcohol smell.
Then the time for condensation of the “bodies” will come - increase the power of the distillation column and set the temperature to 45-55°C.
The condensation process of the tailings (“tailings”) begins at a temperature of about 85°C. At this moment you will smell a fusel smell.
After the rectification process is completed, the tail condensates can be left for next use.

This is how the rectification process occurs, which allows you to obtain a pure commercial product without harmful impurities and foreign odors. After the first operation, you will be able to detect possible errors in the assembly or some elements of the distillation column.

If you have already gained experience in operating the device or do not want to constantly participate in the rectification process, an automation system will be useful to you. With its help, the possibility of “tails” getting into commercial alcohol will be excluded, and the “heads” will be collected in a separate container. The BUR (distillation control unit) will adjust the power, start supplying water for cooling and reduce the withdrawal at the end of the process, and then turn off the heating and water supply.

The simplest option for automation is a start-stop installation with a valve. To assemble such a system for a home mini-distillery, it is recommended to use Chinese-made components or refer to specialized forums.

More and more models of moonshine stills on the modern market are positioned as distillation columns. Some consumers boldly follow technology, while others invariably remain faithful to the good old “classics”. However (we recommend choosing a device from the brand) today it is possible from a number of manufacturers. Are they as effective as they say, and what is the purpose of a distillation column in a household distiller? We'll talk about this below.

What is a distillation column for?

To obtain pure alcohol using a conventional classic distiller, theoretically, eight to ten distillation cycles are required. Each distillation produces a gradual increase in strength. In fact, alcohol-containing liquids with an ethanol concentration of over 30% of the volume should be distilled into normal conditions unsafe and very energy-consuming. It’s not for nothing that knowledgeable craftsmen do not recommend cooking at home, for example, absinthe. - please, but it is not safe to distill them undiluted after infusion.

In a rectification column, on special contact elements located inside, all these 8-10 distillations take place along the entire height of the column simultaneously. Here, repeated condensation and evaporation of substances occurs, due to which the alcohol vapors are purified and strengthened, and unnecessary impurities flow back into the distillation cube with reflux. In other words, the distillation column is the element of the moonshine still in which the process of distillation, purification and strengthening takes place.

At the same time, it is in your power to get the drink that you need. It is enough to adjust correctly temperature regime distillation, and regardless of which you can get both pure alcohol, and a distillate that preserves the flavor and aromatic properties of the original raw material. Any distillation column requires careful preparation and some skills in working with it. To help novice distillers, you can read about small technological nuances that have been discovered experimentally.

Thus, it becomes clear why a distillation column is needed in a moonshine still. Only with its help is it possible to obtain pure rectified alcohol. Neither a classic apparatus with a steam chamber, nor a mash (film) column will give you alcohol with a strength of 96 degrees (the maximum possible strength under normal conditions). And you can read in more detail about what processes occur in the distillation column.