What is rectification? Description of the process and application in industry. Why is rectification needed and how does a distillation column work? Reason: the distillation column is clogged with soot

Dedicated to all homemade people.

Theoretical and practical retreat

Ideally, the column should be loaded with technological power at which maximum packing efficiency is achieved, and, accordingly, the best quality of alcohol. Those. the column must be designed so that the “weakest link” that determines the moment of its choking is the nozzle.

The correct column should start to choke at the nozzle!

And the “wrong” column can choke anywhere, fortunately there are plenty of these places in the column:

• on the mesh retainer of the bulk nozzle;
• on threaded connections;
• in attachment to the cube;
• in a reflux condenser with countercurrent steam condensation;
• in any other narrowing of column sections.

Do you think that no one needs to know this? You just can’t imagine how many “specialists” who bought only columns from us installed them on their cubes through an adapter like this.

What do you think, for example, did our RUM-1 with a technological power of 1 kW work for them using such a connection? That's right, it didn't work - it immediately choked on this lower ∅14mm hole (with the minimum allowable being at least ∅18). And then we get calls: “Your column is not working! It choke on one kilowatt! You sold me crap!”

And you can even “write fairy tales” about what is happening with the “homemade workers”. Especially for those who make columns themselves, and “specialists” who buy equipment from us in parts, we provide a table for reflection with a video recording of choking in different places in the column. All figures were obtained experimentally using alcohol.

Element throughput (specific flooding power) W/cm2

Now let's get back to the question at hand.

Choking on the mesh retainer of the nozzle (limiter) is one of the first “rakes” that stand for all “homemade workers” on the way to home rectification (they themselves almost stepped on them back in 1986.

If the nozzle is bulk, then the retainer is usually a mesh with a cell size smaller than the size of the nozzle element. But it must be used correctly.

As follows from the table, the throughput of a flat mesh is even slightly higher than that of S/P nozzles. But as soon as you pour a nozzle onto a flat mesh, the throughput of the S/P nozzle is reduced by almost half (by 43%). Obviously, this is due to significant cluttering of the mesh cross section with the nozzle. In this case, the column will choke on the grid and will be underloaded by almost half.

Imagine, some piece of incorrectly executed mesh can “gobble up” HALF of the possible productivity of your column. The problem can be solved simply - from the mesh you need to make a cone with a full angle at the apex of no more than 90° (a flat mesh is a “cone” - 180°).

The most common cause of cloudy moonshine and panic among novice distillers is when suddenly the moonshine still begins to “sneeze and spit,” then instead of the expected clear distillate, a cloudy or even yellow liquid begins to flow. All these are signs of spray drift, which is also called “the punishment of impatient moonshiners.”

Sprinkler (in moonshine)– foam and sometimes boiling mash getting into the refrigerator moonshine still(coil) followed by mixing these unwanted substances with alcohol vapor. From a practical point of view, spray drift makes the moonshine cloudy and smelly, and with very strong spray drift, the distillate is actually diluted with boiling mash.

The only reason for splashing is too much heating of the mash during distillation. Grain (malt) mash is more susceptible to this phenomenon than others, as it contains a high concentration of proteins. When the liquid boils, the proteins form a lot of foam on the surface, which escapes from the cube and enters the cooler through the tubes, at the same time “dragging” the uncleaned mash with it. No moonshine still design can completely eliminate splashing, but there are methods to reduce the likelihood of its occurrence to a minimum.

Attention! You should not leave the device running unattended; if splashing occurs and you do not turn off the heating in time, the hot mash from the cube will fill the receiving container and end up on the floor.

Prevention of splash drift

1. Fill alembic mash to a maximum of 70% of the volume, so that there is enough space for the foam in height, and it “does not reach” the steam exhaust pipes to the cooler.

2. Distill the maximum clarified and degassed mash, reducing foaming.

3. Monitor the intensity of heating of the mash using thermometers in the cube and (or) cooler. The correct distillation temperature depends on the design of the moonshine still; there are no universal values, so the optimal temperature is selected experimentally.

4. Install a steam trap in front of the coil as a barrier to foam (one is enough, two or more will not have an effect).

5. Monitor the condition of the moonshine still, regularly clean the distillation cube, connecting pipes and cooler.

6. Advanced moonshiners use a reflux condenser to combat splashing on mash columns. As a result, phlegm (steam condensed in the reflux condenser) flows back into the cube, “nailing” foam on its way, which tries to rise to the refrigerator of the apparatus.

What to do in case of splashing

1. Reduce heating intensity to a minimum. Wait until the foam disappears, then gradually, a few degrees at a time, increase the temperature until the first drops appear, and then a thin stream. When the distillate becomes more or less transparent, change the receiving container to a clean one.

2. Continue distilling the mash according to plan, for example, distill to a strength below 40% in a stream or “to dryness.”

3. It is advisable to clean the resulting moonshine with charcoal (if not fruit). Disassemble the device and wash it.

4. Make a second one fractional distillation(with cutting off the “heads” and “tails”).

5. Add the liquid formed as a result of splashing into a new portion of mash or, if there is a lot of it, distill it separately.

Provided that these instructions are followed, splashing will not affect the quality of the moonshine.

The information partner of the material is the online store of goods for home brewing "".

The topic of rectification is truly multifaceted. There have been, are and always will be questions regarding this important process in moonshine brewing.

We invite you to learn all the most important things from our article!

Only with the help of rectification is it possible to produce almost pure alcohol and moonshine at home.

Our distillation columns “Dachnik”, “Bee”, “Peach” can rightfully be called home mini-factories.

You can easily buy equipment for rectification from us, but you just need to decide on the requirements, how much moonshine you want to produce and how much space you are willing to allocate for this production.

You can also try to make a column yourself; the design of distillation columns is, of course, more complicated than a moonshine still, but it’s not impossible.

If you still decide to make the column yourself, then the requirements for materials for making the column are the same as for a moonshine still.

For the container - only food-grade stainless steel, for gaskets - natural silicone, it is better to weld the parts together, or solder them with food-grade solder.

If you bought an inexpensive distillation column and the result is bad alcohol with foreign odors, what should you do?

It often happens that sellers of such columns are disingenuous, saying that you can produce pure alcohol with them. Your expectations were not met, perhaps because the manufacturer greatly overestimated the capabilities of the column.

Or its dimensions are such that it is basically impossible to obtain pure alcohol from it, no matter how hard you try.

A good column cannot be cheap.

How does a distillation column work?

The column is installed strictly vertically in the tank, and raw alcohol is poured into the tank, then heating is applied. The liquid boils and steam rises into the column. At the top of the column there is a reflux condenser (refrigerator with a selection unit).

In other words, part of the condensed liquid in the refrigerator can be taken out, and the rest can be released back into the column.

This liquid flows down towards the steam and there interacts with it on many small elements.

These elements have a large developed surface (springs, balls, rings), which is called a nozzle. The liquid flowing down the column elements is called reflux.

Condensate forms in the column dephlegmator, part of which is taken to the outlet, and part falls back.

Returning part of the condensate to the column is the key to normal operation of the column. The ratio of the amount of condensate taken to the outlet and the amount of condensate returned to the column is called reflux ratio(FF). If you do not take the product from the column, then the reflux ratio will be equal to infinity.

Steam interacts with phlegm, giving it its energy and substances that boil at a higher temperature, while at the same time, substances with a lower boiling point are transferred to the top of the column.

After some time, all substances are distributed throughout the column from boiling at a high temperature (at the bottom), to boiling at a lower temperature at the top. That is, the lowest boiling substance will rise to the reflux condenser and can be easily selected.

In this way, liquids that are separate from each other can be easily collected.

Packing – internal elements of the column, usually free-flowing. The most accessible type of attachment is metal sponges for cleaning and washing dishes. Before using such sponges, you should make sure that they are made of stainless steel.

How can I check this? Just bring the magnet.

You'll probably ask why distillation column wrapped in insulation?

The fact is that thermal insulation allows you to minimize the influence of external factors on the rectification process. And since the operation of the column depends on the stability of the temperature distribution along its length, thermal insulation is more than justified.

Experienced moonshiners know what is hidden behind the phrase “the column choked.”

Let's tell you a secret. Column flooding is a phenomenon in which the liquid coming from the reflux condenser does not return to the cube, but accumulates.

The reasons for this may be excessive heating power (a large steam flow prevents the reflux from flowing down), and design errors (installation of grids that are difficult to pass for reflux, excessive packing compaction, bottlenecks in the column).

Column choking is manifested by violent squelching and noise during operation; the contents can even be thrown out through the upper hole of the reflux condenser!

If the cause of the choking was strong heating, then you need to reduce it and everything will go as expected.

But design errors most often occur in homemade columns; they can only be eliminated by remaking the column.

A high-quality column is one of the keys to success in moonshine brewing!

The material was prepared by online store experts Kupitalon.ru. When copying materials from the site, a hyperlink is required

Alcohols have become an integral part of our lives. And it's not just alcohol. It is obtained by fermentation followed by distillation. And often people mistakenly think that rectification is distillation a second time. In fact, this is repeated passing of alcohol-containing liquids in special columns. As a result of the meeting of two flows - liquid and vapor - pure alcohol is obtained. Let's look at what rectification is in more detail.

Alcohol and its properties

But first, let's figure out what alcohol is. The word was borrowed from Latin and means "spirit". If all normal conditions are met, it will be a colorless, transparent liquid with a pungent taste and characteristic aroma. Pure alcohol will range from 95.6 to 100% ABV.

Humanity has been familiar with alcoholic beverages for a long time, as with the fermented juice of natural berries and fruits. Back then these were drinks with low alcohol content. But with the development of chemical knowledge, people received more and more strong drinks. But only at the very end of the 18th century were they able to obtain 100% rectified alcohol. The author of the invention was the Russian chemist T. E. Lovitz.

What is rectification

The word came into our language from Latin and means correction, straightening. This is one of the methods used in industry, laboratories or at home to separate mixed liquids.

The rectification process is based on the difference in the distribution of mixed components between the vapor and liquid fractions. During this process, the vapor flow moves towards the liquid flow, they come into contact with each other, exchanging heat and mass until equilibrium in the system occurs. All this happens in a special device called a distillation column apparatus.

During the meeting of the flows, the ascending steam flow absorbs all the volatile components, and the flowing liquid absorbs the less volatile ones. As in the distillation process, another process for producing alcohol, the energy costs of rectification are the same, but the extraction of the desired component (in our case, alcohol) is much more efficient. This is what rectification is.

In order for liquid and steam to interact more successfully, the installations use contact elements - plates or nozzles. They increase the efficiency and area of ​​interaction between two oncoming flows. The principle of their operation is as follows: steam rising upward passes through the contact element and the liquid accumulated on it, exchanging mass and heat more intensively. The more elements are installed in the design, the faster equilibrium will be achieved between the vapor and the liquid fraction.

How rectification differs from the distillation process is discussed in the table below.

The difference between rectification and distillation

Equipment for rectification

Two types of equipment can be used for this process: continuous and batch units. The first type is used in industry, since automation is used to regulate the work - expensive and complex. For laboratories, the second, simpler and cheaper type of equipment is used. It contains basic means of adjusting the extraction - a thermometer and a manometric meter for pressure changes on the column.

Structure of a distillation column

The classic scheme looks like this. A vertical column (also called a drawer) and a reflux condenser with a limit switch are installed on the evaporation cube. This installation does not require complex mechanisms, just a tap, a sight glass, a thermometer, and sometimes a power regulator.

It should be remembered that the greater the height of the column, the more intense the mass and heat exchange between the two streams will be. And rectification of alcohol will be better.

Column operating principle

The cube is filled to a maximum of two-thirds of its volume with an alcohol-containing mixture, the tightness of the joints is checked, the tap is closed and a cooling element (most often water) is supplied. Only now can you turn on the heating.

It is important to know: you should never close two fittings (rectificate extraction and water supply) at the same time, as this may cause the column to simply explode under the influence of the resulting excess pressure!

The heater brings the liquid poured into the cube to a boil, and the resulting steam rises. Then, once in the reflux condenser, it condenses and flows down the walls, again coming into contact with new steam rising upward. It hits the heater again, becomes steam, and the process repeats.

After some time, the steam and liquid come into equilibrium, and a fraction with a low boiling point (methanol) accumulates in the upper part. At the bottom - with high (fusel oils). Now they can be selected.

Equilibrium is determined by maintaining temperature for 10 minutes. Until this moment, you do not need to touch the device.

Column selection unit

What is a selection node? Most often, this is a small side that slows down, preventing the phlegm (liquid condensed from steam) from draining. If you open the tap of the selection unit, the retained phlegm flows into the refrigerator, turning into rectified alcohol.

The same liquid that did not linger on the side flows further down to repeat the cycle again. In industrial installations, it is possible to set the ratio between the rectificate and the reflux, which is returned (reflux ratio) using a tap. The purity and percentage of alcohol depends on this number. The higher it is, the purer the alcohol.

It happens that such an unpleasant phenomenon occurs as the distillation column choking. Information that this happened is indicated by a strong gurgling noise inside the structure itself. There may be several reasons why the flooding occurred; let’s look at them.

When the column chokes

The maximum speed of steam movement in each design is different. When it is reached, phlegm slows down its movement in the cube, and then may stop altogether. Its accumulation in the rectification part causes the process of heat and mass transfer to stop. The result is a pressure drop (often very sharp) and the appearance of extraneous noise.

Reasons for choking:

• most often this is heating above the permissible level;
• the cube is overfilled or clogged with particles of an alcohol-containing composition;
• in the highlands the main reason is low atmospheric pressure;
• a voltage surge, due to which the power of the heating element increases;
• malfunctions and design errors.

Now you know what rectification is. The resulting alcohol from this process has a harsh taste (called industrial alcohol). It can be used for technical purposes, but for the food industry it will need to be further refined - diluted, filtered and infused.

For better purification, the resulting raw materials are subjected to a carbonization process (passing through activated carbon). As a result of this procedure, the alcohol will become “soft”, and (a small amount of them always ends up in the alcohol, even if you used a fractional selection process) will be bound by coal. In fact, this is the classic procedure for preparing the famous Russian vodka.

After carrying out the dilution and carbonization procedures, the drink should be given a rest. Just leave it in a glass container for a few days. The vodka will go smoother, and if you don’t overdo it, you won’t get a hangover.

The problem of flooding of the distillation column is pressing for many beginners and even professionals. The process of separating heavy and light fractions in rectifiers and distillers is somewhat different. With advantages and features come their own specific disadvantages.

Why does the column choke?

The principle of operation of the column is based on the settling of heavy fractions of fusel oils and the rise of light ones. Steam containing pure alcohols moves upward along the column at a certain speed. When the maximum values ​​are reached, the phlegm flows into the cube very slowly, and then stops moving altogether. As a result of the accumulation of these fractions, choking occurs.

It is possible to track this problem and identify it immediately, but you must be nearby throughout the entire distillation process. Extraneous noise appears, even a distinct gurgling sound, and the pressure changes sharply.

How to avoid and prevent column flooding?

The very first rule is to read the operating instructions before starting the equipment for the first time, and not after discovering problems. The normal speed of steam movement varies between 0.5-1.2 m/s. The maximum indicators determine the throughput of the column. 2000-7000 (kg/h)/m2 - throughput is expressed in the consumption of alcohol steam per unit cross-sectional area of ​​the rectifier. It turns out that the closer the moment of choking, the more productive the equipment is.

Reasons for column flooding at acceptable throughput

Even if the indicators do not exceed those indicated in the product data sheet, choking can occur due to:

• increasing voltage levels (more than 220V), in this case the power of the heating elements increases;
• the formation of foam inside the column, which is a consequence of overfilling the container with mash;
• a sharp drop in atmospheric pressure, often observed when using a column above sea level (in the mountains);
• strong heating, to prevent unpleasant consequences, you simply need to lower the temperature.

If we are talking about a homemade design, the reasons may be incorrect proportions. Therefore, it is recommended to purchase ready-made equipment or manufacture it according to verified drawings obtained from reliable sources.