"Dear Eugene.
Previously, we completed the devices with glass jars, very often the jars were broken during delivery and the devices arrived scratched, this caused great inconvenience to both parties. ...
I don’t think that finding a screw can is more difficult than fixing possible problems with unsuccessful delivery ...»
Administrator,
Ufa
“The Alcovar classic distiller is pictured with a can, but it comes without a can. Is it really so difficult to include a jar in the package so that buyers do not have to look for a screw jar? The device is not cheap, the bank m ...
can be provided in the kit, and so it creates inconvenience.
When pouring out the waste product, not everything is poured out of the apparatus, since the edges of the cube are rounded, you have to pervert, this is also a minus.»
Evgeniy,
Kirov
“Dear Ivanov Alexander, we apologize for the inconvenience.
We have been producing this copper apparatus for more than 4 years. For 4 years, several hundred such devices have been sold. For all the time we received only 2 under ...
general messages, one of them is yours. The first appeal was from a person who supplied 3 kW of heating to this apparatus. We assume that you are also heating at 3 kW. If you heat up to 1.5 - maximum 2 kW, everything should work properly.»
Administrator.,
Ufa
“Hello to everyone who laid eyes on (copper fafarit). Nice piece but nothing more. the reflux condenser is working, probably the coil is 12m vnem. 2l. - don't even dream about it. 200nu250gr. he will give you and not more ... her. So be patient. And the reason for the lack of a normal condenser (refrigerator)»
Ivanov Alexander Ivanovich,
Samara
“Good shop, I like it. And their products are okay. I want to try your molasses next time.”
Many experienced moonshiners perform the distillation process on homemade stills without any additional equipment such as a spirit meter or thermometer. And really, is a thermometer really necessary for a moonshine still? More likely yes than no, especially if a beginner is taken to distill the mash into moonshine.
The main task of the thermometer in the moonshine still is to control the process of fraction selection. This process is the key to the entire art of home brewing. Incorrectly selected fractions can produce a smaller amount of the finished product or, even worse, low-quality moonshine with a large amount of harmful impurities.
Bimetal thermometer on a still
From the theory of the mash distillation process, many people know that alcohol and water are inseparable substances and they boil together, but fractionally. That is, for the entire period when the product comes out of the moonshine still, both substances will be contained there, only in different proportions. But besides this, at temperatures below the boiling point of alcohol, acetone, methyl alcohol and other harmful substances begin to boil, and closer to the boiling point of water, fusel oils. Thus, during distillation, the first and last fraction are separated, and in order to do this correctly, a thermometer is needed.
What are thermometers?
All thermometers are divided into several categories, depending on the principle of operation in terms of physics. The device has a scale by which you can determine the temperature. But the main thing you need to know is that each of them differs in such parameters as price, installation method and reading accuracy. There are the following main types:
- Bimetallic - a bimetal tape or spiral acts as a measuring sensor.
- Electronic - the principle of their work is based on the phenomenon of a change in the resistance of substances with a change in temperature. The sensor can be made of metal or semiconductor.
- Digital - temperature is measured depending on pressure surges.
- Liquid - consist of a glass flask filled with a liquid, such as mercury or alcohol, which expands with increasing temperature.
- Infrared - measure the temperature by radiation, do not require direct contact with the emitted surface.
The most popular types among phone users are the first three. They have their own advantages and disadvantages. The bimetallic thermometer can be considered the most reliable and durable.
The principle of their operation is based on the fact that different metals have different coefficients of linear expansion depending on temperature. Usually the thermometer has a threaded connection, and in order to connect it, you need to solder a threaded fitting into the lid of the distillation cube. An electronic thermometer for a moonshine still, like a liquid one, requires only a hole in the lid, through which the sensor itself is inserted into a silicone tube and covered with sealant.
The main disadvantage of a bimetallic thermometer is that its indicators are not very accurate. It is recommended to use it for those people who already have some experience in moonshine brewing.
An electronic thermometer in a moonshine still, as a rule, shows a more accurate temperature. However, it is very fragile and can fail without the ability to repair it after the first even not too strong blow. In most cases, any damage leads to the purchase of a new thermometer.
Digital thermometers show the most accurate temperature. But their cost is very high, as well as the repair of such a device, since a highly qualified specialist is needed for this purpose.
Liquid thermometers are not used in high heat systems as there is a risk of mercury escaping. The main application of an infrared thermometer is distillation columns, since there is a high degree of heating of the liquid.
Mounting principles
How to install a thermometer? To install the device for measuring temperature on a moonshine still, you must perform a certain sequence of actions. Determine its location first. As practice shows, if we are talking about a home-made apparatus, the best place is the upper part of the distillation cube.
In order to install a thermometer, it is necessary to drill a hole in the cube. The diameter of such a hole must match the size of the setting cylinder, where the thermometer will subsequently be placed. Such a cylinder, as a rule, comes with the purchase of a specialized thermometer.
After you have made a hole, you will need to insert the cylinder inside, you will need a bolt to secure the structure to the outside of the alembic. Further, the structure is fastened with a nut, and the device itself is mounted in a cylinder.
Before you start the moonshine still, it must be checked. For this, ordinary water is best suited: first it must be poured into a cube, and then the distillation process should begin. In this case, it is important to monitor the performance of the device.
We note such parameters as the constancy of its readings, accuracy, stability of the structure. If the testing was completed successfully, and the outlet water temperature does not exceed 19-20 degrees, you can start distillation. A higher temperature may indicate a malfunction of the coil cooling system.
How to choose the right thermometer?
- The first thing you should pay attention to is the measurement range. Usually, this can be found by simply looking at the scale of the instrument; if the sensor shows numbers - in the instruction manual. As a rule, this range is 0-120 degrees.
- What other questions are important? For example, the material from which the thermometer is made: it is best that it be stainless steel. Such a thermometer is the least susceptible to damage and will last longer.
- Another factor is the mounting method. The most common is the installation of a thermometer with a nut and bolt. You should not buy devices whose type of fastening seems unreliable, for example, with Velcro. Most likely it won't last long. Also, the thermometer cannot be attached to glue, because it is usually afraid of high temperatures.
Do I need a thermometer: pros and cons
The main advantages of the thermometer are:
- the ability to precisely control the distillation process;
- over time, bring it to automatism so that you can rely only on the readings of the thermometer.
But it also has a number of disadvantages:
- when installing a thermometer, the tightness of the device can be broken;
- you can’t rely only on his testimony, you need to overtake the mash several times in order to understand the temperatures that are typical for a particular apparatus and mash;
- like any additional equipment, it costs money;
- not necessary, although useful.
Here are all the highlights regarding thermometers in a moonshine still. Which one to choose and whether to purchase at all is a personal matter for everyone. The quality of the product increases only with experience and a competent approach to business.
In modern distillation, a thermometer for moonshine has become a necessary measuring device, on which the quality of the final product largely depends.
Someone claims that our ancestors did without it for hundreds of years, so perhaps we are exaggerating its significance?
I would like to add that they also managed without air conditioners, telephones, the Internet, but this does not mean that it is necessary to abandon all the benefits of civilization.
Why in a thermometer:
- With his help easy to monitor temperature mash or raw alcohol during the secondary distillation and, accordingly, regulate the degree of heating of the cube.
- He helps to correctly separate the distillate into fractions and protect from getting into the final product of toxic compounds - fusel oils:
- when on a scale of 63-70°C, substances with a low boiling point evaporate. These are the "heads" - the most toxic of the possible impurities in moonshine. These include methyl alcohol, aldehydes, esters. Select the heads in a separate bowl and then dispose of;
Important. Upon reaching 63 ° C, lower the heating temperature sharply and gradually bring it up to 65 ° C, taking the heads only drop by drop, not allowing the distillate to turn into a stream. The number of heads is 10-12% of pure alcohol.
- 78.4 ° C is the boiling point of ethyl - drinking, which we need. This fraction is called the body or heart of moonshine. In fact, the evaporation of ethylene begins already at 72-74°C (similar to how the vapor from water rises long before it boils). The body is taken in a thin jet up to 85°C;
- followed by tails. Some of them are collected to add to the mash during the subsequent distillation and get a higher yield of raw alcohol. Others ignore this process and simply stop the haul, believing that the tails are not worth the time and energy spent on them.
- Not only the quality of the distillate, but also its taste depends on correct haul. Even a partial hit of heads and tails in the haul deteriorates the organoleptic properties of the product. Fusel notes of rustic moonshine appear in it. Therefore, it is impossible to focus in the separation of distillate only on “flair”.
Types of thermometers for home brewing
For home brewing, several types of household thermometers are suitable, which are used and when smoking, cooking, etc. Consider them as they become popular with distillers.
Bimetallic
It can be called the most popular and inexpensive. It is these that complete moonshine stills of industrial production of the economy class and the middle price segment.
And in home-made devices, this type of measuring instrument is most often used.
Their advantages:
- low price;
- ease of acquisition. The internet is a good choice. Moonshiners prefer devices with a large round dial and a short probe. There are models with a long thin probe, but it is more difficult to make a capsule under it;
- acceptable accuracy, although deviations of a couple of degrees are possible;
- strength. Case, scale, pointer are made of metal. Plus glass over the scale.
Such a thermometer is usually installed in the distillation cube using a welded-in capsule. In this case, before distillation, the device is simply inserted into the capsule.
At other times, it can be used for other purposes. Less commonly used without a capsule, using a threaded connection. But at the same time, such a possibility should be provided for in the design. It is believed that this way the readings are more accurate (the probe is in direct contact with the vapors without an "intermediary" in the form of a capsule).
Also, bimetallic thermometers are installed in drawers.
This type has its drawbacks:
- Given the fact that the main supplier of these products is China, the quality sometimes leaves much to be desired.
- low resource. After a couple of years, the accuracy of the readings drops.
Electronic
Advantages:
- Indication accuracy. Deviations are not more than 0.2 degrees.
- Durability and structural strength.
- Sensitivity to temperature changes. Electronic instantly responds even to tenths of a degree.
- The probe 15-20 cm long sensitively reacts to temperature changes in the cube and column (two thermometers are installed).
- It is better if the electronic thermometer is installed directly into the cube or into the column (threaded connection). But it is desirable to provide insulation from direct contact with the metal, then the steam temperature readings are almost ideal. When using the capsule, deviations of 1-2 degrees are possible.
There are almost no shortcomings. Compared to bimetallic - the best option.
Digital
This type is designed for accurate temperature measurement both on the surface and in the thickness of the product. Widely used in smoking, making various products.
Often equipped with a probe on a wire with a length of a meter or more: the display with readings is located at a distance from the device.
It's safer to place it in a closed sleeve recessed into a cube, perhaps directly into the liquid.
The device is extremely accurate for household appliances, but requires a power source.
Liquid
This is a well-known glass model. Gives accurate readings, responds quickly to temperature changes.
The main disadvantage is fragility. Requires careful handling. In the moonshine it is permissible to use alcohol thermometer only. When broken, it is not as dangerous as mercury.
Infrared
A very interesting view, but in moonshine brewing is ineffective.
It works on the principle of infrared radiation: the beam is directed to the object whose temperature is to be measured. Indicators appear on the electronic scoreboard.
But the fact is that the numbers will indicate, albeit accurately, the temperature of the cube wall, which differs by several degrees from the heating of the liquid (mash).
If you have this device, you can use it, but it’s not rational to buy it specifically for controlling the heating of the mash.
Which to choose?
Moonshiners prefer to have the most accurate and affordable device for measuring the heating temperature of an alcohol-containing liquid in a cube or column, the use of which does not cause difficulties. That is why we will arrange all the described devices by rating:
- Digital.
- Bimetallic.
- Electronic.
- Liquid.
- Infrared.
Do-it-yourself device installation
If you already have a distillation cube (column) in the design of which a thermometer is provided, its installation is not difficult. But with self-assembly, refinement is necessary:
- Purchase a suitable thermometer with a scale of at least 120°C.
- Pick up a stainless steel tube under the probe of your measuring device. It must match in length and width.
- Make a capsule out of the tube by brewing the bottom.
- Drill a hole in the top of the cube to match the diameter of the tube.
- Weld the capsule into the hole.
- Another option is to connect the capsule with threads and two nuts through silicone gaskets on both sides of the cube.
Important. Do not use rubber pads. When heated, they will transfer the unpleasant smell of burnt rubber to the distillate.
It remains to insert a thermometer into the capsule and use it during the haul.
As an option, insert the thermometer not into the capsule, but directly into the cube. To do this, it is necessary to provide a sealed connection: screw the device into a cube. Which is only possible if there is a thread at the top of the stylus (where it is connected to the scale).
Adjustment of indicators
As a rule, thermometers go on sale already in a calibrated form. But failures during operation and inaccuracy of indicators are also possible. In this case, the device can be adjusted. For example, in bimetallic it is usually possible to adjust with a bolt, using a screwdriver.
Sometimes it is necessary to calibrate an electronic or two instruments for installation in a cube and a column so that they show an accurate temperature. You need a container with cold water in which ice floats (conditionally - its temperature is 0 ° C). Immerse the probe in this water for at least 5 cm for 3 minutes.
Then press "CAL" (there is such a button for calibration) and hold for 3 seconds. The thermometer will adjust to zero temperature. After that, shake the probe in ice water. If readings change, recalibrate.
For digital and infrared thermometers, see instructions. As a rule, they do not need additional adjustment, and the error is no more than 0.2 degrees. Self-calibration can lead to even greater inaccuracies.
A thermometer is a necessary device for a distiller who strives to produce clean and tasty moonshine without foreign smell and taste. The choice depends on your capabilities and desire to improve your own skills in creating elite homemade strong alcohol.
The thermometer in the cube should give the most reliable information for a correct assessment of the course of the distillation process. At the same time, the main question is not where to put the thermometer, but why put it at all? What do we want to see or calculate from his testimony? If you deal with these issues, the rest of the points will become obvious.
So let's start with simple questions. The first of them: what is the bulk strength in a cube? To answer, it is enough to know the boiling point of the bulk at the current moment.
Designations:
- T1 – bottom bulk temperature;
- Т2 – steam temperature;
- T3 is the steam temperature at the column inlet.
Everyone is confused by the incorrect term - "cubic temperature". It is possible to measure directly the temperature T1 in the liquid zone or the steam temperature T2. It seems that in both cases this is the “cubic temperature”, but this is not so. If we measure the temperature of the liquid T1, then we get it. But having learned the steam temperature T2, in the future we can only assume that it is equal to T1.
At the moment of steam separation from the boiling surface, indeed, T1 = T2. But every moment the steam loses its temperature. At the exit from the cube to the column, it is much colder than the boiling bulk.
The degree of cooling of the alcohol vapor depends on the heat loss through the side walls and the lid of the cube. The relatively cold phlegm pouring from the column also makes a significant contribution. How big is this error? The measured steam temperature can range from the vaporization temperature to the condensation temperature.
The width of this corridor can be clearly seen with the help of the well-known “fish”.
Suppose that a 25% alcohol solution is boiling in a cube. Climbing along arrow 1 until it intersects with the graph of the boiling point of the liquid (red curve), then we turn along arrow 2 and determine the boiling point (vaporization) - 87 degrees. Following the arrows along the route 1-3-4-5, we determine the condensation temperature of the resulting steam - 80.5 degrees. This means that a temperature probe sticking out somewhere in the steam zone will show a temperature of 80.5 to 87 degrees.
The longer and closer to the boiling surface the probe is, the less cooled steam it will meet, and the closer the thermometer readings will be to 87 degrees, and vice versa, the shorter and closer to the flowing phlegm, as well as the lid of the cube, the probe will be, the closer its readings close to 80.5 degrees. If the thermometer is also inserted into a thick sleeve welded to the lid, then the sleeve, like a large radiator, will remove heat, and the thermometer readings will become even more unpredictable.
The measurement error will become negligible if you boil in a cube a liquid close in composition to pure alcohol or water. In this case, the difference between the condensation temperature and the vaporization temperature will tend to zero, along with a possible measurement error. But here's the problem - this range is not interesting for distillers.
The maximum difference and possible error falls on the distillation range - 93-98 degrees, and the error can be up to 12 degrees.
This is the corridor in which, depending on the heat loss, the steam temperature will be, that is, the maximum error value. In fact, this does not happen. The better the cube and its lid are insulated, the less heat loss, and the value of T2 is closer to T1.
But there is a price of error... Suppose the thermometer in the steam zone showed 98 degrees, we stopped the selection, thinking that only 2% alcohol was left in the cube. In fact, the temperature of the bulk was 97 degrees and the alcohol content was about 1.3% higher. With a cubic pile of 30 liters, this is 400 grams of lost 96% alcohol or 2 bottles of vodka. The premature transition to "tails" wrote off about the same amount for re-rectification. This is because the tip of the thermometer was not in the liquid zone and with an error of only 1 degree. If the cube is poorly insulated, the sting is far from the bulk surface and the error is much larger?
Determining the bulk temperature from the steam temperature has an error of an indeterminate value, the maximum error value is unacceptable, since the loss of alcohol will be very large.
Knowing the exact value of the temperature of the bulk, it is possible to determine its current strength and the alcohol content in vapors at the column inlet. Having the strength of the product at the outlet, it is realistic to estimate how many separation stages (theoretical plates) the column is currently working with.
This is a very important and necessary temperature, the only one of all, the absolute value of which must be determined with maximum accuracy.
The bottom temperature is the temperature of the bulk (liquid), it must be measured directly without the mediation of steam, by lowering the thermometer into the liquid zone.
Indeed, what benefit can be expected from an intermediary, except for corrupted information?
How to choose an alembic thermometer
Any thermometer has an accuracy class. This is an important parameter to pay attention to. Often unscrupulous manufacturers complete the sold cubes with bimetallic thermometers with an accuracy class of 2.5. This means that when measuring temperature, the maximum error will be 2.5% of the maximum value on the thermometer scale.
If the value is 120 degrees, then the error can be up to 3 degrees. For example, if we are going to cut off the “tails” at a temperature of 94 degrees, and finally see this temperature on a thermometer, then in fact the real temperature can be from 91 to 97 degrees. And this is in addition to the influence of other factors discussed above.
With an accuracy class of 1.5, the maximum error would be 1.8 degrees. With the same accuracy class, a thermometer with a lower maximum value of the measured temperature will be more accurate.
As a rule, electronic thermometers give a higher accuracy class. Even a household kitchen thermometer has an accuracy of plus or minus 1 degree with a division price of 0.1 degrees, but not everything is so simple. Absolute temperature measurement accuracy and resolution are two different things. Such thermometers are justifiably used in columns where it is not the temperature itself that is important, but its change. This is where 0.1 degrees comes into play. When measuring the bottom temperature, it will certainly give a more accurate temperature than a bimetal thermometer, but you should not expect miracles.
For a more accurate measurement of the temperature of the cubic pile, electronic thermometers of the T-0.36-DS-A type with an external temperature sensor are used, in which the resolution and measurement accuracy are 0.1 degrees. True, the measurement range is more modest: from -55 to 125 degrees, but for the purposes of distillation - just right. There is also a drawback - the DS18B20 temperature sensor requires a sleeve to be placed in a cube.
The simplest and most affordable option for placing a temperature sensor is in the heating element sleeve. When installing, it is enough to bend it a couple of centimeters to the side and up from the heating elements.
If a decision is made to install a sleeve, simple requirements must be observed: the temperature sensor tip must be at some distance from the heating element, the bottom and walls of the pan. At least a couple of centimeters. But you don’t need to get carried away either, the sleeve should not interfere with the installation of additional equipment, such as a false bottom. Also, the sleeve should not be massive, as this does not contribute to the accuracy of measurements. Well, if the inner diameter of the sleeve approaches the diameter of the thermal sensor, the use of thermal paste is welcome.
conclusions
- The bottom temperature thermometer should only be placed in the liquid zone.
- When choosing a thermometer, you need to pay attention to the accuracy class, measurement range and resolution.
This step-by-step instruction is just one of the methods of distillation on a distillation (RD) or mash (BK) column, having mastered which you can get a highly purified product. However, for fruit, berry and grain distillates there are technological nuances, without knowing which, instead of a flavored drink, there will be pure alcohol. Each type of nozzle has its own characteristics. Use the proposed method as a start for studying the operation of columns, training on sugar mash, or knowingly understanding that the result will be rectified alcohol or a drink close to it.
Initial conditions. Raw alcohol is available - sugar mash distilled on a conventional distiller (moonshine still) and - RK or BK. In this case, the procedure for working on different types of columns is almost identical, and the differences are described in appropriate places in the instructions.
Rectification scheme 
An example of a distillation column in assembled form with a description of the main structural elements Technology of home distillation on RK and distillation on BC
1. Fill the cube with raw alcohol no more than 3/4 of the height, leaving at least 10-12 cm of the vapor zone. However, it is also impossible to fill in too little, so that at the end of the distillation process, when there is almost no liquid left in the cube, the heating elements do not emerge (do not become bare).
The strength of the cubic bulk should be about 40%. This value is related to the minimum phlegm number required to achieve the selection of a given strength. With an increase in the strength of the bottom bulk, the minimum reflux ratio decreases non-linearly, reaching a minimum at a strength of about 45%. Therefore, if you start the process with a fortress of 60%, then you will have to reduce the phlegm number up to 45% of the fortress, and then increase it as the distillation residue is further depleted in alcohol. That is, first increase the selection from 60 to 45% of the cubic strength, and then reduce it. As a result, rectification will not only be more difficult to manage, but will also take longer.
2 Turn on the heater at maximum power and bring the raw alcohol to a boil. The optimal heating element power for overclocking is 1 kW per 10 liters of bulk, then the time to boil is 15 minutes for every 10 liters of bulk.
3. Shortly before the start of boiling, at a temperature of 75-80 ° C in the cube, turn on the water supply. After the start of boiling, reduce the heat to operating power. If the operating power is not yet known, reduce to a level below the rated power by 200-300 watts. Adjust the water supply so that the steam is completely condensed in the dephlegmator. The outlet water should be warm or hot. The column began to work for itself.
4. Monitor the values on the thermometers in the column, wait for the readings to stabilize.
5. Determine the operating power of the column. To do this, after stabilization of temperatures, check the pressure in the cube. You will need a pressure gauge up to 6000 Pa (0.06 kg / sq. cm, 400 mm water column), or a U-shaped differential pressure gauge, a pressure gauge from a tonometer will also work (if nothing else is found).
If the pressure is stable and does not increase, increase the heating power by 50-100W. The pressure in the cube should rise and after 5-10 minutes stabilize at a new value. Repeat this operation until the pressure ceases to stabilize and continues to increase, for example, after 20 minutes the increase continues. Remember the current readings - this is the power of the choke.
If there is a 50 mm column and a SPN 3.5 packing, then the last non-increasing pressure (in mm of water column) will be approximately equal to 20% of the column height in millimeters. If the pressure is 30-40% of the height of the column, this means that the phlegm has hung, and the choke process continues. With a less dense nozzle with less holding capacity, the power of the choke will be higher.
If there is no pressure gauge, they are guided by the sounds of the column - when choking, the column may begin to sway, gurgling, increased noise is heard, spontaneous emissions of alcohol through the communication tube with the atmosphere or into the refrigerator when steam is taken are also possible. For the first time without experience, it is difficult to determine the choking of the column, but it is possible.
After determining the power of the choke, turn off the heat and wait a few minutes for the phlegm to glass into a cube. Turn on the heating at a power 10% less than the choke. Wait for stabilization of temperatures and pressure in the cube. If everything is in order, then this will be the working capacity of the column.
If the operating power is much lower than the nominal, this means that the packing or packing support elements are not properly packed in the column: the packing is too overpacked, possibly a tangle, there are pockets of reflux concentration, where the steam stops it, flooding the column. In this case, you need to disassemble the column, pour the nozzle, straighten the tangle, then reassemble and repeat the setup process.
The operating power of the column is determined once. In the future, the obtained value is used constantly, occasionally making adjustments.
With a properly selected working power, the pressure in the cube will be the same every time. It does not depend on the diameter of the column and usually amounts to 3.5 - 150-200 mm of water for the SPN packing. Art. for each meter of nozzle height, for SPN 4 - 250-300 mm of water. Art., for other nozzles, the value will be different.
When looking for working power, you can also focus on the following practical data: for an etched heptagonal SPN 3.5, the working power in watts is approximately equal to 0.85-0.9 of the pipe cross-sectional area in millimeters. If SPN 4 is used, the coefficient increases to 1.05-1.1. For less dense nozzles, the coefficient will be higher.
6. After stabilization at operating power, let the column work for itself for 40-60 minutes.
7. Set the selection of "heads" at a rate of 50 ml/h for a 40 mm column, for 50 mm - 70 ml/h, for 60 mm - 100 ml/h, for 63 mm - 120 ml/h. Provided that SPN is used.
The time of selection of "heads" is determined based on the bulk volume: 12 minutes (0.2 hours) for each liter of 40% raw alcohol. It must be remembered that this is not distillation in a conventional apparatus with a coil - in the columns there is a separation into fractions and their sequential withdrawal to the selection in a concentrated form.
Recommendations such as 3-5% of absolute alcohol are average values, but no one has canceled them, and precise control of the end of the selection of “heads” is done, guided by the smell of the exit. It should be remembered that the time and speed of the selection of "heads" are not related quantities. If you select "heads" at twice the speed, they will simply turn out in a less concentrated form.
General principle: during the selection of any fraction, it is impossible to take more from the column than enters the selection zone. This will prevent violation of the separation of fractions along the height of the column.
8. Changing the rate of extraction is only possible by adjusting the water supply to the reflux condenser for columns with steam extraction upstream of the reflux condenser. If the column is with liquid extraction, then just a selection valve.
The heating power must always be constant, this ensures the stability of the amount of steam supplied to the column and the operation of the column as a whole.
9. Select headrests - this is second-class alcohol, slightly contaminated with head fractions. Its amount is equal to 1-2 volumes of alcohol held by the nozzle in the column (150-500 ml). In fact, the nozzle is washed from the remnants of the “heads” and the intermediate fractions accumulated in the column. To do this, the selection is set at 1/3 of the nominal (about 500 ml/hour). Alcohol of the second grade is suitable for re-distillation.
10. Go to the "body" sampling: set the initial sampling rate equal to the nominal or slightly higher. The rated speed (ml/h) is numerically approximately equal to the operating heating power (in W). For example, if the working power is 1800 W, then the initial rate of selection of the “body” is 1800 ml per hour. By the end of the selection, the power is reduced to 600 ml / hour,
11. Control the process according to the readings of thermometers and the pressure in the cube. There are several methods. The simplest is to navigate by the temperature difference between the lower (20 cm from the bottom of the nozzle) and the middle (at half or 2/3 of the column height) thermometers. After the start of the selection of the “body”, the difference in these readings should not change by more than 0.3 degrees. As soon as the difference increases by more than the accepted value, it is necessary to reduce the selection rate by 70-100 ml.
Special cases: if there is only one thermometer, proceed in the same way, focusing on the change in its readings. For the lower - a change of 0.3 degrees, for the upper - 0.1 degrees. This is a less accurate method, as it is sensitive to changes in atmospheric pressure.
If there are no thermometers in the column at all, they are guided by the change in temperature in the cube - they reduce the selection by 6-10% after the temperature in the cube rises by each degree. This is a good method that allows you to get ahead of the rises in the column in terms of temperature.
12. After the selection of half of the “body”, more and more often it is necessary to reduce the speed of selection. When the temperature in the cube rises above 90 °C, fusel and other intermediate impurities leave the cube and accumulate in the nozzle. To cut them off more clearly, you can let the column work for itself for several minutes before reducing the selection, then resume the selection after the temperature difference returns to its previous level, naturally, by reducing the selection rate. This will make it possible to more clearly cut off the "tails" by creating an alcohol buffer in the sampling zone.
13. When the selection is reduced by 2-2.5 times in relation to the initial one, the temperature regularly leaves the operating range, while the temperature in the cube is 92-93 °C. These are signals for the BC that it is time to move on to the selection of "tails". On the RC, due to the greater holding capacity, with a bulk of less than 20 nozzle volumes, the selection can be continued up to 94-95 ° C, but the process is often stopped, saving time and nerves.
Change the container, set the selection rate to about half or 2/3 of the nominal. Although these are "tails", but you need to try to take a minimum of impurities. Sample up to 98 °C cubed. "Tails" are suitable for the second distillation.
14. Rinse the column. After selecting the "tails", let the column work for itself for 20-30 minutes, during which time the remaining alcohol will collect at the top, then turn off the heating. Alcohol, flowing down, will wash the nozzle.
Also, periodically you need to steam the nozzle, removing the remnants of fusel oils. This can be done by driving the raw alcohol "dry", then continue the selection at a decent speed until an odorless distillate comes out. The second method is to pour clean water into the cube and steam the column.
