Out of the corner of my eye I saw on one of the forums another discussion on the topic “how to supply water to the refrigerator, towards steam or along the way,” in which they referred to my article on the construction of a boiler room. I have not touched on this topic before, so I decided to express my opinion separately in this article.
In the BC design I proposed, water is supplied to the apparatus from below and it turns out that it enters the reflux condenser along with the steam (forward flow), and into the refrigerator in the opposite direction (counterflow). Is it correct? The classical theory of heat exchangers states that counterflow heat exchangers are more efficient than direct flow ones. This can be illustrated with a picture.
Figure a shows a direct-flow heat exchanger, figure b shows a counter-flow heat exchanger. As can be seen from the temperature graphs, with counterflow, the temperature of hot coolant A at the outlet is lower (point Y), and cold coolant B is higher (point Z) than with forward flow. This fact is explained by the fact that in a direct-flow heat exchanger the temperatures of the coolant are leveled to some average value, and in a counter-flow heat exchanger the temperature of the hot coolant approaches the temperature of the cold one and vice versa. The temperature delta (heat flow) in the case of a counterflow heat exchanger is larger. Accordingly, the efficiency of the counterflow is higher; it can be made more compact (or it will be more effective with the same dimensions). Everything seems clear.
But, as always, from general rule there are exceptions. IN in this case this exception states that if the temperature of one of the coolants does not change continuously, but only up to a certain value (which happens during condensation or evaporation), then the heat flow at different options connection becomes the same. This is what happens in the case of a reflux condenser. Our task is to maintain a certain temperature of the steam (for steam extraction - the boiling point of alcohol, for liquid - the temperature of its condensation, in fact, this is practically the same temperature). In the case of a direct-flow refrigerator (in other articles, out of habit, I incorrectly call it direct-flow, although it can also be counter-flow), the task is somewhat different - to condense the product and then cool it to the temperature of the cooling water, i.e. classically “heat exchange”. It turns out that the reflux condenser BC does not matter how to connect it, but the refrigerator needs to be connected opposite.
There is one more point here. There is always a dissolved gas in water, which tends to be released when the temperature rises and “airing” forms in the system, even causing plugs. Therefore, it is more expedient to supply water to the jacket reflux condenser from below, eliminating airing - the flow of water removes air bubbles. With small flows through the reflux condenser, you can observe the formation of an air bubble at the very top of the outlet silicone tube in the midst of the process - this is it.
Thus , it is advisable to connect the water supply to the BC from below - simultaneously into the reflux condenser (forward flow) and towards the refrigerator (counterflow).
However, despite the widespread use of these names, if you analyze the numerous information on the Internet, then there is widespread confusion regarding the purpose of these devices. There are especially many discrepancies in the functions and essence of the operation of the reflux condenser and the steam boiler. Let's figure it out and start with the basics.
Rectification and distillation
Distillation- This is evaporation followed by condensation of vapor. This is exactly what happens when you use moonshine still the simplest type.
Rectification- separation of the mixture into fractions due to the countercurrent movement of steam and the same steam condensed into liquid (reflux).
Thus, it can be seen that during distillation, the steam formed during boiling of the liquid flows directly to the condenser. As a result, we get a homogeneous mixture containing alcohol, water, and fusel oils. The alcohol content increases due to the fact that it evaporates at higher temperatures. low temperatures and faster than water and other fractions.
During rectification, part of the condensed steam flows back towards the distillation tank, is heated by the newly formed steam and evaporates again many times. As a result of the process of re-evaporation, the distilled liquid is divided into its component parts. In the case of moonshine: fusel oils, water and the alcohol we need. The degree of separation depends on the design of the distillation column.
Looking ahead a little, let's say that a reflux condenser for a moonshine still is one of the elements included in the design of a distillation column.
Dry steamers and wet steamers
Actually, these are two names for the same element. They are also known as cubs. Both the steam steamer and the wet steamer are structurally a thin-walled closed container of small volume with two steam lines in the upper part: inlet and outlet.
A tap is embedded in the lower part of the diving board for discharging waste condensate. However, often the jugs are made from glass jars, then, naturally, there can be no talk of a tap. The accumulated liquid is drained through the neck and only after the distillation is completed.
A simple steamer from a can
There is one structural difference between a wet and dry steamer: in a wet steamer, the outlet of the inlet pipe is lowered to the very bottom, so that the steam from the distillation cube “gurgles” through the liquid poured into the container. Hence, a wet steamer is often called a bubbler.
How it works
- Steam enters the container and, due to the temperature difference, begins to condense on the walls and flow to the bottom.
- As the steam boiler body heats up with new steam, the intensity of condensation decreases, and part of the steam begins to escape.
- At the same time, the condensate begins to heat up and evaporate and also goes into extraction.
- At a certain point, due to re-evaporation, there is only “dirty” phlegm at the bottom, which is better to dump through the tap and start the cycle from the beginning.
- If there is no tap, then there is only one option - selection before flushing, i.e. At the exit we get a “dirty” product.
Both the “reset” and “selection to victory” options are not good - the output we will still get is not the highest quality product. In fact, the steamer performs only two useful functions:
- prevents mash pairs from being selected;
- due to re-evaporation, it slightly increases the strength of the product.
Is it possible to improve the efficiency of the bite? It is possible, but it is necessary to change its structure: the body should be located above the distillation cube, and the condensate should be discharged directly into the cube. Only this will no longer be a dry steam tank, but a quite decent uncontrolled reflux condenser.
How does a reflux condenser work?
The reflux condenser device in its simplest form is two welded tubes different diameters, installed vertically on the distillation cube. Coolant (water) circulates in the jacket between them, and a smaller diameter tube serves as a pipeline for the release of alcohol-containing steam.
To explain the operating principle of this device, let us conventionally assume that the distilled liquid has 2 components that have different boiling points. The division into fractions is carried out as follows:
- At the initial stage, the cooling starts at full power and until the distillation cube is heated, the apparatus works “on itself.” That is, the liquid evaporating from the container condenses, forms a thin film on the walls and flows towards the rising steam back into the cube. On its way, it is heated by the newly formed steam and partially evaporates - this is “re-evaporation”
- After the temperature in the container reaches a temperature sufficient for both fractions to boil, two areas form inside the structure:
- The upper one, where vapors of the fraction with a low boiling point condense.
- The lower one is the region of condensation of the second component.
- Nothing is still getting into the main refrigerator, that is, there is no selection yet.
- The evaporation and condensation temperatures of each fraction are known. Now you can change the cooling mode so that the evaporation point of the first fraction is at the upper edge of the reflux condenser.
- The selection of the first component of the mixture begins.
- After the low-temperature fraction is selected, the mode is changed again and the second part of the mixture is selected.
The method allows you to separate a liquid into any number of components having different boiling points. The process is inertial, and it is better to change the cooling mode very carefully, slowly and stepwise.
Dimroth reflux condenser
The separating ability of the reflux condenser depends on the size of the contact area between the reflux condenser and the steam and the accuracy of the adjustment. The principle of operation is the same for all types of these devices; they differ only in design.
The one that was described in previous section- direct-flow film-type refrigerator. The design is simple to manufacture and quite effective. But it has disadvantages - a small interaction area, which generally tends to zero when the structure deviates from the vertical. The second is the difficulty of adjusting the steam temperature. The Dimroth design is partially devoid of these shortcomings.
The Dimroth reflux condenser is a glass or metal flask with a spiral tube in the center. Water circulates through it and phlegm condenses on it.
The principle of operation is the same, but it is obvious that such a design, even by eye, has large area contact between vapor and liquid than a film apparatus. In addition, the interaction of phlegm and steam occurs in the center of the flask, where its temperature is maximum. Consequently, the resulting product will be cleaner and stronger.
Why is a Dimroth reflux condenser or a film reflux condenser for a moonshine still most often used in everyday life? This is due to the properties of the raw material - mash. If, when distilling it, you use the most effective packed column With large area filler, then after half an hour of work the filler will become so contaminated that any rectification will become impossible.
When making spirits, a home craftsman must correctly determine the desired end result. If speed and low cost of equipment are important to the master, the apparatus will be simple: a distillation cube and a refrigerator.
If he wants to get the highest quality product possible, purified from fusel oils and with a strength above 70 degrees, it is necessary to use various additional components: a steamer, a bubbler or a reflux condenser.
A reflux condenser is a device for additional purification of alcohol-containing steam. The steam that is formed in the distillation cube when the mash is heated contains not only alcohol, but also heavier impurities of fusel oils and water. If the steam is cooled, these heavy impurities condense, and this condensate is called reflux. The process of separating phlegm from steam is called reflux.
Definition from Explanatory dictionary foreign words edited by Krysina: “Dephlegmation [de], and, pl. no, w. [German Dephlegmation< лат. dē… от…, раз… + греч. phlegma мокрота, влага]. тех. Частичная конденсация смесей различных паров и газов с целью обогащения их низкокипящими компонентами.»
Phlegm also contains a certain amount of alcohol, so when various designs moonshine stills, it is possible to ensure the return of phlegm to the distillation cube.
Mechanism of operation (why is it needed)
The classic circuit of a moonshine still, a cube-refrigerator, turns into a circuit of a cube-reflux condenser-dry steamer-refrigerator. The operating procedure of the system is as follows:
- The mash is heated in the cube, light fractions evaporate from it - alcohol, fusel oils, water.
- The steam is cooled in the reflux condenser. installed on the cube. Phlegm enters the cube. where it evaporates again.
- Steamer - empty container, through which steam passes. It is needed to separate mash splashes and the heaviest condensate. The reflux condenser can be installed here too. then the phlegm will be collected and utilized.
- Bubbler by purpose and design similar to a steam bath, the difference is that it is designed so that vapor passes through water, cooling and purifying. If the reflux condenser is installed on a bubbler, then the steam bubbling will pass through the reflux. not clean water.
- Alcohol in the refrigerator is complete condenses and collects in liquid form in the receiver.
Video review of a glass refrigerator:
Where is it installed?
The reflux condenser can also be installed on a steam tank or bubbler tank. Then the phlegm will not be collected in the cube, which will provide a purer product at the outlet, but some of the alcohol will remain in the reflux. In some sources, a reflux condenser is confused with a steam boiler, but these are still different devices.
The reflux condenser is installed:
- On the still. In this case, we get something like a distillation column.
- On a dry steamer. In this case, it must be equipped with a tap to drain the accumulated liquid.
- On the bubbler. In this case, it is better to make it transparent so that you can observe the steam bubbles passing through the phlegm. and also monitor the level of accumulated phlegm.
Cooler device for moonshine still:
For example, consider the Dimroth reflux condenser. This is classic laboratory equipment, usually made of heat-resistant double laboratory glass. It is a main tube wrapped in a glass coil. This design is placed in a flask that protects from mechanical damage.
The main tube is installed vertically on a cube or steam tank so that the phlegm flows down due to gravity. The steam passes through the main tube and is cooled cold water from a coil. For supply and return water, the coil must be equipped with fittings. Such systems are also called shell-and-tube systems.
We make it ourselves
In home brewing, not everyone uses reflux. But this leads to a deterioration in the quality of the resulting alcohol, or to the use of double distillation. In addition, the reflux condenser is easy to make and will last for quite a long time.
A home craftsman can make both a shell-and-tube and a jacket reflux condenser. In a jacket dephlegmator, instead of a coil, a simple water jacket. In any case, to make a reflux condenser, you will need soldering or welding skills.
Note: When choosing a material for a reflux condenser, you need to know that the main tube must be made of glass, food grade of stainless steel or copper.
These materials do not oxidize and do not change the taste of the resulting alcohol. A shirt or coil can be made from any other materials.
Watch the video how to do it simple refrigerator for moonshine in 15 minutes:
- A shell-and-tube reflux condenser consists of a main tube and a coil wound on it. a simple stainless steel or copper tube can be used as the main tube.
- The length of the tube depends on the volume of production; for home brewing, an inch tube 25 cm long is enough.
- The diameter can be increased, the length can be decreased.
- The thinner and longer the tube, the longer the distillation will take, and the higher the degree of purification.
- But if the reflux condenser cools the steam too much, then you will not get any results at all - all the alcohols will flow back into the cube.
It is easy to make a shell-and-tube reflux condenser:
- A copper tube with a diameter of 6 mm is wound onto the main tube.
- Winding length - 15 - 20 cm.
- The tube is secured with plastic or clamp clamps; you can put a foam rubber or foam insulation of suitable diameter on this structure, which is used to insulate heating systems.
- On copper tube water is supplied for cooling.
- That's it - the reflux condenser is ready.
A more efficient reflux condenser can be made from several small diameter tubes placed in a jacket with running water.. In this design, the steam has a large area of contact with the cold walls, which makes the dephlegmator work more efficiently.
This is done like this:
- Small diameter tubes are assembled into a cassette that looks like a revolver drum.
- If we use this analogy, then steam flows through the cartridge cases, and coolant circulates in the drum body.
- This design is difficult to manufacture; to assemble such a structure you need to use stainless steel welding or copper soldering.
What to replace it with?
If making or purchasing a reflux condenser is problematic, you can replace it with a simple bubbler.
- For this we take a simple glass jar(preferably at least 1 liter) with a screw cap. Two holes are drilled in the lid - inlet and outlet.
- Tubes are inserted into the holes, while at the inlet the tube drops almost to the very bottom, and the outlet tube is located at the very lid.
- It is important to carefully seal the joint between the tubes and the lid. For this you can use cold welding or soldering.
- About one third is poured into the jar cold water. The mechanism of operation of a bubbler is simple: steam under pressure passes through a tube and passes through the water column. At the same time, it cools, fusel oils condense and dissolve in water.
- Some of the alcohol also dissolves in water, but this is not a problem: during operation, the water is heated by hot steam, and the alcohol re-evaporates from the surface of the jar. It should be noted that a reflux condenser has a number of advantages over a bubbler, for example, the ability to adjust the intensity of the reflux process.
Watch the video where a Chinese moonshine cooler is disassembled, it was always interesting what it is made from at the factory:
Industrial devices
In the alcohol industry, the use of reflux condensers is a prerequisite. At the same time there is different kinds- direct and reverse action.
- Direct action - phlegm enters a separate tank and is no longer involved in the process.
- The opposite is true - phlegm is fed into the distillation cube, evaporates again and again, evaporating the remaining alcohol. In this case, special alcohol traps and ventilation systems are used.
The main purpose of the reflux condenser is to reduce the time and quantity technological operations, improve the original quality of products. The reflux condenser separates the steam into several fractions. The steam, passing through the blades and radiators, is swirled and cooled. Control temperature conditions carried out automatically using sensors and a controller.
As a result, after the device, the steam contains mainly alcohol and a small part of water - the alcohol strength can reach 70-90 degrees.
Conclusion
So, the use of intermediate refrigerators - reflux condensers - is necessary if you need to obtain higher quality alcohol at minimal cost.
The use of this device is mandatory if the quality of the mash is low, there are foreign odors or a high content of fusel oils is felt. At the same time, the simplest structures can be easily made with your own hands, or ordered from argon welders.
