The vacuum drying process is attractive, first of all, because it has a real opportunity to significantly reduce the drying time, while maintaining the high quality of the dried lumber, and in some cases even increasing it.

Vacuum chambers for wood drying

In vacuum chambers, timber is dried under high pressure of 700 mm Hg. Art., but at a low temperature of 45 C. Vacuum is specially created in these devices, which entails high energy costs.

Vacuum drying is an extremely expensive method of drying timber for a number of reasons:

• expensive vacuum chambers
• a huge amount of electricity power for proper operation

In such devices, timber is dried for one to two days. For example, to dry 40 m 3 boards, it will take approximately 8-16 days. And if vacuum drying of the timber is carried out, then even more time will be needed.

Due to the high cost of the process, vacuum drying of wood is carried out mainly for expensive varieties of timber, such as oak, ash, beech, and cedar. In such cases, it is required to dry a small amount of lumber. For the mass production of lumber, convective drying kilns are used, because they are more affordable and have a low cost.

Some examples of vacuum drying:

• oak planks 52 mm thick with a moisture level of 50% will dry to a moisture level of 4-5% in about 28 - 35 days
• oak boards 52 mm thick with a moisture level of 30% will dry to a moisture level of 4-5% in 16 - 18 days
• oak planks 25 mm thick with a moisture level of 50% will dry to a moisture level of 4-5% in about 15 days
• oak boards 25 mm thick with a moisture level of 30% will dry to a moisture level of 4-5% in 9 days
• 55 mm thick pine boards with a moisture level of 50% will dry to a moisture level of 5-6% in about 8 days
• pine boards 55 mm thick with a moisture level of 30% will dry to a moisture level of 5-6% in 6 days
• building timber 100 x 100 mm and 150 x 200 mm with a moisture level of 65% will dry to a moisture level of 6% within 8 - 12 days. A beam of 200 x 300 mm will take 22 days to achieve the same parameters.

Under vacuum conditions, wood drying occurs more gently. However, even with this method of drying, cracking is possible. Wood is a living raw material. Wood has different types of stresses. These stresses depend on the area in which the tree has grown, on the sawing method, and on age. During the drying of wood, even in such chambers, not all stresses are removed evenly.

How does wood vacuum drying work?

Injection of vacuum inside the chamber, where the timber is dried, to a large extent changes the physical nature of the heat and mass transfer processes in the wood. Drying is carried out under the action of a constant vacuum of 0.95 MPa and steam generated from the moisture of timber. Since there is a natural movement of the drying agent at a speed of up to 0.3 m / s, there is no need to use fans, systems for moistening the lumber, install a dry / wet thermometer. Drying is controlled by lumber moisture sensors. For example, during the drying of oak lumber from the initial moisture level of 65% to the residual - 6%, about 450 liters of moisture are released. If you load a maximum of 12 m 3 of oak with a thickness of 55 mm into the chamber, then the total amount of moisture will reach 5,400 liters.

Today, all companies producing vacuum drying chambers have certificates of compliance with European standards. In such devices, different types of wood can be dried at the same time.

Drying quality:

• the residual level of importance is from 6 to 0.5%
• humidity level difference across the stack does not exceed 1%
• the difference in moisture level across the thickness and length of the board does not exceed 0.9%.

Do-it-yourself vacuum drying of wood

The drying process is very beneficial when done by hand. However, it is expensive to purchase a factory vacuum chamber, in this section we will tell you how to make it yourself. Drying at home can be done in a special chamber, which requires a spacious room, a heat source, and a fan to distribute heat inside the chamber.

The best option for creating a camera is an iron conveyor. You don't have to buy new, you can find used ones. In addition, you can weld the camera yourself from old iron.

In order to keep the heat inside the chamber, the walls need to be insulated with foam and lined with clapboard. In addition to polystyrene, mineral wool and any other insulating material is suitable. In order for heat to be reflected from the surface, it is necessary to lay a special material. You can use foil or penofol. By the way, the heat-reflecting and preserving qualities of penofol are much higher.

After that, you can begin to assemble the heating device. The entire heating system must be installed separately from other heating circuits, it must constantly function. Suitable heating radiator, which heats the water to 65-90 degrees. To evenly distribute heat in the chamber, you should purchase a fan. Without it, drying will not occur evenly, and the final product will be of poor quality. Do not forget about fire safety rules when creating a vacuum dryer.

Another important point can be called the creation of a system for loading lumber into the chamber. For this purpose, you can use carts that move along rails or a forklift. Raw materials for drying are stacked on shelves or directly on the floor. To control the drying process, you need to install special sensors - thermocouples and pressure sensors. If you correctly approach this event, then you will get a chamber for drying high-quality lumber.

After loading the raw materials into the chamber, the door closes tightly and the drying process begins. Under such conditions, bound and free liquid will move smoothly from the center to the periphery, which guarantees high-quality and uniform drying of the material. The dry upper cells of the lumber absorb fluid from the cells closer to the core. First, thin places dry out, then moisture from thick layers moves to already dried ones, making them wet.

To prevent displacement, a special mixture is applied to the lumber, which is made from chalk and drying oil. Most often, this mixture is applied to the end parts of the blanks.

February 19, 2017

Among Russian woodworking specialists, a method of drying lumber in a vacuum has been discussed for a long time. Interest in the problem arose after the appearance of media reports about Italian-made units, and then WDE Maspell products on our market. After some time, a number of domestic companies mastered the production of similar drying chambers: Energia-Stavropol, MV-Impulse, etc.

The increased attention to such installations is explained by the fact that their manufacturers announce the drying of lumber in an unprecedentedly short time: within 1-4 days, depending on the type of wood and the thickness of lumber - and at the same time guarantee the high quality of the resulting boards or blanks. Such drying periods aroused distrust among those who did not have the opportunity in practice to check the quality of products dried in such chambers. To dispel these doubts does not allow the extremely scarce information of manufacturers of equipment for vacuum drying about the essence of the process. Let's try to figure it out.

Drying lumber under reduced pressure (usually p abs = 0.15-0.4 bar absolute pressure or p def = 0.85-0.6 bar vacuum, which corresponds to saturation temperature t sat = 54.0-75.9 ° C ) refers to the so-called. high temperature drying process. This type of process takes place when the wood temperature t dr exceeds the saturation temperature t us of water vapor at a given pressure. The course of the high-temperature drying process is more intense compared to the low-temperature process, when the wood temperature is below the saturation temperature (t sat = t bale, t bale is the boiling point). The speed of defect-free vacuum drying is 4–5 times higher in comparison with the normative GO STov mode of convective chamber drying. So, for example, for a group of hardwood species (beech, maple, ash, elm, etc.), the standard drying time for low-temperature convective mode with a board thickness of 50 mm is 12–14 days, while the drying time in press-vacuum installations for the same assortments - three to four days. The process of high-temperature drying was described in domestic literature as early as 1957. Below is information on wood science and from the theory of the high temperature drying process.

“Water can be found in two main structural elements of wood: in the cavities of cells and vessels - free moisture, and in the walls of cell membranes - hygroscopic, or bound moisture. When drying wet wood, first of all, free moisture is completely removed within the cell, and only then, below the hygroscopicity limit (w pg), which is also the shrinkage limit, does the bound moisture begin to evaporate from its shell. With a decrease in the content of bound moisture in wood, the wood dries out.

“Let's consider the case of drying raw (w n > w pg) wood in the form of an unlimited plate in a gaseous medium with a temperature t c > 100 °C. At some intermediate stage of the process, all free moisture is removed from the outer zones of the X-thick plate. The humidity of these zones varies from equilibrium on the surface to the saturation limit inside and has some average value wper. The inner zone of thickness (S - 2x) at this stage remains damp, its humidity is close to the initial one. The temperature of the inner zone is maintained at the level of the boiling point of water t bp, and in the surface zones and the boundary layer it gradually rises to t c. Evaporation of free moisture occurs at the boundary of the zones, due to which this boundary gradually deepens.

It is possible to explain the possibility of maintaining the impeccable quality of drying at such a significant intensity of the high-temperature (even not necessarily using a vacuum) process, given the fact that when the saturation temperature t is reached, first on the surface and then in the thickness of the lumber, intensive evaporation of free water occurs (pseudo-boiling) and the movement of the formed water vapor outward. In the pseudo-boiling zone near the steam medium, the relative humidity φ steam = 100%, and the moisture content of wood w tends to the equilibrium moisture content w р = 10.6 (φ / 100) (3.27-0.015t),%, corresponding to the limit of hygroscopicity w р = w pg (w pg = 26.1% at t = 54 °C and w pg = 22.6% at t = 75.9 °C). Humidity w p g,%, is a function of temperature only: w pg \u003d (34.66-0.159t) - and is characterized by the fact that it is the boundary below which there is no free moisture either in the cavities or in the walls of wood cells. Under the condition w

The first is that lumber is loaded into the chamber in layers with flat heaters - heating plates, which ensures uniform and intense heat transfer.

The second condition: the surface temperature of the heaters must exceed the saturation (boiling) temperature at the pressure (vacuum) created in the installation, by definition.

The third condition (which is not obligatory for atmospheric installations): in the cavity of the chamber, a reduced - relative to atmospheric - pressure is created. If the upper cover of the chamber is made in the form of a flexible membrane (usually made of silicone rubber), then due to the difference in pressure values, a pressing force is created between the layers of lumber and the heaters, which is transferred layer by layer to the metal structure of the bottom of the chamber. This pressing force ensures that the boards are perfectly flat and that the surface of the lumber is firmly attached to the heaters, which is very important if the heat transfer between them is carried out in a conductive way. With this option, an accurate calibration according to the thickness of the lumber is necessary to eliminate the looseness of the fit of the boards to the heaters.

To ensure the uniformity of heat transfer from the heaters to the surface of the boards without their calibration, it is reasonable to organize heating by thermal radiation through a small gap between the plane of the heaters and the lumber, specially created due to special protrusions of the heating plates (such protrusions are, for example, in installations manufactured by Energia -Stavropol"). Heat transfer by radiation in a flat gap does not depend on its size and on the inevitable run-up of lumber in thickness.

As mentioned above, evacuation for a high-temperature drying process is not a prerequisite, however, press-vacuum drying chambers have undoubted advantages, for example, the possibility of lowering the pressure, and, consequently, the saturation temperature. Firstly, lowering the process temperature helps to reduce heat losses in the plant and minimize the color change of the wood during drying. Secondly, the use of a membrane press helps to achieve perfect fixation of the plane of the dried boards and blanks. Thirdly, the dense pressing of the layers of heaters and layers of lumber ensures the uniformity of heat transfer during the drying process.

For drying thick assortments of difficult-to-dry species (for example, oak), special modes are used at stages of wood moisture content above and below the hygroscopicity limit. The use of these modes provides defect-free drying of 50 mm oak assortment within 6-8 days.

The process of press-vacuum drying of wood is implemented in installations with a single load of 0.5 to 10 m in the case of drying lumber of softwood (when drying for two days) - 15 revolutions of the chamber, for a board with a thickness of 30 mm of hardwood (during drying for two days) - 15 revolutions, coniferous species (during drying during the day) - 30 revolutions cameras per month.

Water evaporating from wood (about 250 liters per 1 m 3 of lumber) condenses on the metal walls of the chamber, as well as in a heat exchanger-condenser (if such is provided for by the design). The condensate is drained into the sewer.

Briefly about some features of the design of installations for press-vacuum drying of wood "Energia" (manufacturer - Energia-Stavropol LLC, Russia), as well as WDE Maspell (manufacturer - WDE Maspell srl, Italy). In these installations water flat heaters are used. Chambers from other manufacturers, such as OOO MV-Impulse and OOO Voyager-Vostok (both companies based in Ufa), use heaters with electric ohmic heating elements. WDE Maspell chambers are equipped with electric water boilers, and the design of Energia-Stavropol chambers allows the use of both electric and gas water heating boilers as heating sources.

The ratio of the cost of 1 MJ of thermal energy obtained using electricity, propane and natural gas is now 15:7:1, respectively, so it is most advantageous to use natural gas boilers for drying wood. It is clear that the quality of dried lumber does not depend on the type of energy carrier used, but is determined by the technological modes of drying and the correct operation of automation.

Text: Sergey Bondar

Vacuum drying is the processing of various materials, which at the moment has become very popular in many areas. This type of processing is used in food, industrial and similar industries that need equipment to carry out such processes.

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If we talk about the industry where vacuum drying has become an integral part, then, of course, this is the furniture industry, where without such a process, high-quality furniture cannot be created. This type of processing is used in the furniture industry during the primary processing of wood. After passing through the process of vacuum drying, the tree acquires its characteristic properties. Firstly, it becomes better, secondly, more practical, and most importantly, furniture made from such wood looks simply incredibly beautiful. In other industries, vacuum drying has a completely different working principle. In addition to the furniture industry, this process is also very popular in the food industry, but there the principle of operation is completely different. Vacuum drying is a labor-intensive process that has a huge number of nuances that you should never forget about:

1. The first point is the presence of a large number of high-quality equipment, which is an integral part of such a process.
2. The second point is the high performance of the equipment, without which it will be quite problematic to achieve high efficiency results.
3. The third point is the place where the vacuum drying process will take place. In order for everything to happen qualitatively, it is necessary to have a place that will meet the standards of humidity, air, light, and similar criteria that play a huge role in this matter.

The cost of vacuum drying is a rather controversial issue, and it is very problematic to give an exact answer to it. The price of such a process directly depends on many factors, ranging from the material to be processed and ending with the vacuum equipment in which this process will take place. An equally important aspect is also the time for which you need to do the vacuum drying process. All this plays a certain role, because of which, the price of such a process can be completely different. All these aspects play a big role, which means that they must be taken into account in any case if you want to get a specific answer to what the result of vacuum drying will be.

Vacuum Drying Technology

Vacuum drying technology also boasts a lot of interesting points. Now we will try to analyze the principle of vacuum drying, taking as an example the processing of wood, since this is the material most often amenable to vacuum drying.

Earlier, we have already said that before creating furniture, the wood must necessarily undergo a vacuum drying process, which will allow all excess liquid to be extracted from it and the wood to be significantly reduced in size. The main processes of vacuum drying:

• Removal of excess liquid from wood by evaporation method
• Water circulation through wood

First, circulation takes place in the system, since this process takes much longer. The speed of wood processing by vacuum drying directly depends on the rate of water circulation in the wood. The main part of the vacuum drying process is the complete drying of wood, and this is done so that the wood loses its extra dimensions and has only its own mass, which will later be used to create furniture. It's no secret that in this industry there is a rule that says that before creating wood products, its surface must be completely free of wood. Since only in this case, it will be possible to extract moisture from the core of the tree, which will come out by circulation. But it is worth noting that in addition to vacuum drying of wood, this technology is also actively used in other areas, which we will now tell you about:

• Vacuum drying of meat
• Vacuum drying of cheese
• Vacuum drying of powders
• Vacuum drying of liquid-viscous products
• Vacuum drying of milk

This is only part of the list of areas where the vacuum drying process is actively used. This technology has already managed to gain immense popularity, which is only growing every day. This technology is really unique, which is why it began to be used in many enterprises, which now simply cannot fully function without this process. And this means that there is a possibility of further spread of vacuum drying. Perhaps soon this process will be applied in all areas without exception, giving the opportunity to increase the productivity of many enterprises.

Vacuum drying chambers

Vacuum drying chambers are mechanisms that are designed to carry out a huge number of labor-intensive tasks. We have previously talked about how useful the vacuum drying process is. As for the chambers for vacuum drying, this is something without which such a process simply cannot be carried out. Vacuum drying chambers in this regard simply play a huge role, and without them, you can completely forget about some performance indicators.

The price segment of vacuum chambers for drying is currently far from the lowest. If you wish, you can find already supported installations, which will be quite average in terms of price. But it is best to buy new units, as only they can provide you with all possible quality guarantees. On the modern market, you can see a huge number of types of vacuum drying chambers, which can have completely different purposes. All these cameras have their own functional features, as they are used in a particular industry. Now we will consider the main types of drying chambers:

• Vacuum oven
• Vacuum chamber for drying fruits
• Drying chamber for drying food products
• Drying chamber for wood

The principle of operation of each camera is individual, as it is designed to work in a particular industry. But in any case, we can say that such equipment at the moment is really very effective.

Vacuum freeze drying

Freeze drying is a process based on the constant sublimation of ice crystals from frozen products. Such a process, in a short period of time, produces high-quality dehydration of products, and it does it really well.

The important point is that dehydration in no way affects the chemical properties of the products, which in the future remain all the same useful. In addition, vitamin activity, chemical composition and anatomical structure also remain in the same form. Vacuum freeze drying consists of three key steps:

• Primary freezing of the product
• Sublimation of ice without heat inside the system
• Final dosushka in spec. heated chamber

Based on this, we can conclude that the efficiency of freeze drying is at a high level and this process is really worth the money invested.

Vacuum drying of wood

In the previous sections, we took this type of drying as an example. As a result, we came to the conclusion that this type of processing is very effective, but also has a certain number of nuances that you should also pay attention to.

The process of vacuum drying can be effective only if the environment in which it takes place fully complies with all standards of humidity, temperature, light and similar aspects. The cost of vacuum drying currently fluctuates within the average price segment. If you wish, you can find a place where such a process will cost you a few pennies, but in this case, you will not receive any guarantees of quality. It is best to overpay a little, but in the end to get a high-quality result of work, which can be used in the future in the production of reliable and beautiful furniture.

One of the commonly used drying methods in production is vacuum drying of wood.

Why vacuum drying of wood has earned its popularity?

Vacuum drying of wood began to be widely used as early as 1964 and has not lost its position since then.

Pros and cons of vacuum drying wood

Like other drying methods, it has its pros and cons. Let's consider them in more detail.

Advantages of vacuum drying:

Excellent quality of the received material. Drying wood with a vacuum helps to protect lumber from breaking, cracking, warping and other defects.

Even drying. During vacuum drying, the wood dries evenly throughout its thickness and length.

The shortest drying time. Thanks to the use of vacuum, the entire evaporation process is much faster than with other drying methods.

Ease of installation and use of installations for vacuum drying. This allows them to be used everywhere, for example, directly at the place where a tree is cut down.

Vacuum drying - disadvantages:

The main disadvantage of vacuum drying is the high cost of equipment. This makes the use of this method almost impossible for small businesses and households.

Installation for vacuum drying of wood includes a chamber, which is made of stainless steel. The chamber must be completely sealed. At the top of the chamber is a cover made of elastic rubber, framed in a metal frame.

Inside the chamber, sensors are installed that measure humidity.

The chamber is controlled from the outside, usually the equipment for controlling the vacuum chamber is installed in a separate vestibule.

The chamber must also be equipped with a vacuum pump that will pump out air and accumulated moisture.

For heating in the chamber, aluminum plates filled with water are used.

Water is heated using a boiler, which is installed outside the chamber.

As you can see, the installation for vacuum drying does not have any very complex elements; it is as easy as shelling pears to operate such a chamber.

Vacuum drying - process features

Consists of a set of successive stages. Let's consider each of them in more detail.

Drying wood with a vacuum begins with loading this very wood into the chamber. Lumber is stacked in layers, aluminum heater plates are placed on top of each layer, then wood again, etc.

Next, the person who manages the chamber sets the drying parameters (temperature and pressure level) and starts the process. It is important to take into account the fact that the level of pressure is different for different types of wood. During drying, the pressure level in the chamber remains unchanged, only the temperature changes.

The next stage of drying is heating. At this stage, the wood in the chamber is heated at normal pressure, that is, the vacuum is not turned on. This is done to avoid material defects.

After warming up, drying comes directly. When the wood is warm enough, the vacuum pump starts, it completely removes air from the chamber and creates the necessary pressure inside. At the same time, moisture from the inner layers of the tree moves to the upper layers, thus moisturizing the material. That is why vacuum drying of wood does not require the use of additional humidifiers. Also, such a gradual movement of moisture helps protect the tree from damage. Moisture released to the surface of the wood under the influence of temperature evaporates, settles on the walls of the chamber as condensate and is pumped out by a pump. Evaporation of a liquid in a vacuum environment occurs much faster than at normal atmospheric pressure, since the boiling point of a liquid decreases. Evaporation of the liquid during vacuum drying begins when the tree warms up to 40-45 degrees. The maximum temperature in the chamber does not exceed 70 degrees.

During the pumping out of air, the upper rubber coating of the chamber is, as it were, "sucked" inward and begins to put pressure on the boards, they are dried under pressure.

Finished with conditioning. This way begins when the wood reaches the required moisture level. Heating in the chamber stops, but the vacuum remains. The tree begins to cool down, remaining under pressure. This also avoids unwanted changes in the shape of the lumber. After complete cooling, the vacuum is turned off, the tree is taken out of the chamber.

Vacuum drying of wood in more detail in the next video.

Irina Zheleznyak, Correspondent of the online publication "AtmWood. Wood-Industrial Bulletin"

How useful was the information for you?

All woodworking enterprises make a profit from the sale of manufactured products. And the deeper the wood processing, the more profitable the production. Before buying equipment, each entrepreneur asks questions: What are the drying chambers for wood, what devices are equipped with, and which one to choose for your production?

If you choose the wrong equipment, then the profitability, on the contrary, will fall. And the greater range of wood drying kilns on the market makes the selection task even more difficult.

The main types of drying chambers are:

1. Dielectric.
2. Convector
3. vacuum
4. Aerodynamic

The method of drying wood in various ways was invented back in the 60s, but due to the high costs of electricity and the complexity of the design, technologies have only recently begun to be used. Most often all over the world use convector-type dryers. Why is this happening? Other designs can be used with a number of restrictions and subtleties of use. The main disadvantages of using inductive, condensing and vacuum wood dryers are:

1. Aerodynamic chambers require more electricity;
2. Condensation structures are expensive, and drying in them lasts 2 times longer than in convector ones.
3. Vacuum dryers are expensive and also expensive to maintain.
4. Dielectric ones require high energy costs, although they are considered one of the best.

Convector dryers

Convectors are used for drying wood of various species and sizes. Due to the simplicity of the design, convector chambers are inexpensive to maintain, which indicates reliability. Therefore, in order to increase profitability, in 90 cases out of a hundred they are purchased.

Working principle of convector dryer

Heating occurs from a gaseous carrier (drying agent). When heated, the raw material is tapped. The drying agent can be steam, flue gas, air. The moisture released from the wood serves as an additional moistening of the agent, the excess is drawn into the atmosphere with the help of ventilation.

The exchange of air in a convector dryer is not higher than 2% of the total, so the energy efficiency is noticeable.

Complete set and equipment of the convector dryer

There are many configurations from various manufacturers, but there are basic options:

1. Equipment for an already built or under construction hangar of a drying structure.
2. Fully design with hardware.

Equipment case

The body is completely made of metal, assembled on a monolithic-pillar foundation. The metal used for manufacturing is carbon steel or aluminum with an anti-corrosion coating. Outside and inside the hangar is lined with aluminum sheets. Separate elements inside the structure (deflectors, false flows, amplifiers, etc.) are also made of aluminum. The chamber is insulated with mineral wool in the form of plates.

The structure is assembled in compliance with GOSTs and SNiPa. Options requiring additions and extensions are made according to an additionally developed scheme. The basic assembly is designed for an average snow load.

Convection chamber models

Convection drying chambers are produced by domestic and foreign companies. The most common are Helios: ASKM-7, ASKM-10, ASKM-15, ASKM-25. They are used for drying any type of wood of drying categories I, II, III and 0. According to reviews, these models work quickly, since German fans are used in the mechanism. And installation and maintenance of ASKM models is simple. The price is from 700,000 rubles, depending on the size and power.

Vacuum drying chambers

Designs are designed specifically for expensive raw materials (teak, wenge, rosewood, oak, anger, etc.). Vacuum dryers can also be used for any softwood or hardwood.

Working principle of vacuum dryer

The vacuum dryer works from convector heating of wood and vacuum removal of excess moisture. The temperature regime is maximum +65 0C. But because of the vacuum, 0.09 MPa boils at 45.5 0C. This allows the drying process to be carried out without the aggressive effects of high temperatures, which does not create high internal stress, and the tree does not crack.

In the process of operation, the temperature rises by 65 0С, the automation is activated and the electric boiler is turned off. The upper part of the wood begins to cool, and moisture from the inside begins to flow to the drier parts. For the entire drying process, such processes can occur up to 250 times. So the moisture is evenly drawn out along the entire length and depth of the raw material. The maximum moisture difference in different parts of the tree can be 0.5-1.5%, and completely dried has a moisture content of 4-6%.

Models of popular vacuum designs

The most common model of vacuum chambers is Helios. Drying chambers for Helios wood differ in power, loading volume and other technical characteristics. More about TX Helios in the table:

Aerodynamic chambers for wood drying

These drying chambers are reminiscent of a metal box finished with a professional aluminum deck. An aerodynamic chamber of various modifications is used for drying all types of wood, with a load of 3-25 m3. On request, you can purchase chambers of individual design with a load of up to 43 m3.

The aerodynamic chamber is good because the work is fully automated and a minimum number of workers is needed.

The frame of the aerodynamic chamber consists of a solid metal sewn onto a supporting frame. The chamber is made in the form of a quadrangular box, into which it is convenient to load wood by car or by rail. ways. The entire internal structure is equipped with automatic condensate collectors.

Principle of operation

Drying is carried out under the influence of aerodynamic energy. Heated air circulates in the chamber under the influence of a specially designed aerodynamic fan. The air in the chamber, due to compression, increases the temperature on the centrifugal fan, specifically on its blades. Thus, aerodynamic losses are converted into thermal energy.

Heat is forced into the chamber, depending on the design, in reverse or dead-end. The work of the aerodynamic chamber is started by one button “start” and opens only after the cycle is completed.

Models of aerodynamic dryers

The most common dryers of the aerodynamic type Gelos SKV-25F, SKV-50F, SKV-12TA, SKV-25TA, SKV-50TA, as well as Italian EPL 65.57.41, EPL 65.72.41, EPL 65.87.41, EPL 125.72.41, EPL 125.87.41. Developed by Helios, specifically for drying coniferous material. They cost from 1,500,000 rubles.

Dryers with microwave chamber

Microwave cameras have been invented quite recently. Such a dryer resembles a closed metal container. Operates under the influence of the reflective surface of microwave waves. Reminds me of how a microwave oven works. Using a microwave chamber, you can dry the material of any section and size. Microwave chambers have a simple design and you can adjust the wavelength to any length. This made it possible to dry any raw material using a microwave chamber. The attenuation mode of the microwave wave allows you to adjust the temperature inside the chamber. And reversible fans remove excess moisture from the system. Microwave drying is compared with dielectric drying, which is considered the most efficient, but is not used in Russia due to high electricity costs.

The main disadvantages of microwave chambers include wood moisture control and the high price of microwave dryers and electricity costs.

Models of microwave dryers

In Russia, this drying technology is offered by the engineering company in Moscow "Investstroy" - "SVCh-Les". Such an installation costs from 1,300,000 rubles. It is necessary to service the microwave forest once every half a year, at a price of 100,000 rubles.

Only half of the future profit depends on which camera the buyer chooses. Building and insulating a box is only part of all the work. It is important that the component equipment is of high quality.

Equipment for drying chambers

Equipment for dryers can be divided into types:

1. Thermal system.
2. Exhaust and humidification system.
3. Rail structure for loading and unloading

Ventilation equipment performs the role of uniform distribution of heated air. Installing a low-quality fan entails uneven drying of raw materials. According to GOST, the air movement inside the chamber should be optimally about 3 m / s. This can be achieved using high-quality and powerful fans. All fans have a rotary or axial connection system.

This equipment depends on the capacity and model of the drying chamber. The heat generator can be an electric heater or a heat exchanger. They are installed only by specialists, and they are used to pump and transfer thermal energy to wood. A system, such as a mini-boiler house for liquid, gaseous or solid fuel, can also act as a heat generator. It is convenient when work is carried out on waste wood production.

The electra heater has a design consisting of a pipe and a chrome spiral wound around it. This generator has a small advantage: a simplified process for controlling the temperature inside the chamber.

Humidification system

To ensure constant uniform air humidity in dryers, humidification and exhaust equipment is used. Humidification is carried out by a complex system of nozzles, pipelines, and a solenoid valve.

The hood is carried out using a fan (usually rotary). The equipment works according to the following technology: when the humidity drops, the fan automatically turns off and the hood does not function. At the same time, air humidification occurs by offsetting the evaporation of the liquid, which enters the nozzle automatically when the valve is opened.

When the humidity rises, on the contrary, the valve closes and the fan turns on.

Rail loading and unloading system

This equipment is installed at the stage of camera assembly. The system is made of rails, which are installed thoroughly. On top of them, stacked carts are attached, which are needed for storing wood. Raw materials are laid on them, and placed in a chamber, after drying, the carts are rolled out into the street and packaged.

When choosing a chamber for drying wood, it is better to use the services of professionals, but do not neglect the information of specialists on the network.