Vacuum dryer for wood. Drying chamber for wood with your own hands

For various products from wood (furniture, musical instruments, parquet, etc.), its drying temperature is used and a certain humidity is saved.

Tree, despite the development of modern technologies, still remains indispensable material In many branches of the economy. It surrounds us everywhere, used in the manufacture of furniture, in the construction industry, even in aviation, it still finds its application. Of course, various polymers, synthetic resins, steel and alloys various metals Actively replace wood even in traditional niches for her. But the full failure is impossible. Therefore, there will always be a need to prepare wood for use in different branches of human activity, in its drying. We will try to give answers to questions related to such necessary equipmentlike a dump for lumber, with their own hands made and debugged.

Why do you need to dry wood?

Drying for sawn timber is an extremely necessary process, without which the wood is simply impossible to use.

The quality of the tree depends on the correct drying.

If you have your own business related to the production of wood products, then you can't do without your drying chamber. But first, let's try to understand what this dryer is needed, for what you need to dry lumber. All business B. natural humidity Any tree. If you perform the product from unusted wood, it will eventually dry out, goes cracked, and it will only be left to throw it out. In addition, the properly dried tree improves its performance, becomes more durable, resistant to environmental impacts and less exposed to destructive mold. In the old days, to prepare the forest to use it was dried even without years, but decades. Often, under a special canopy laid logs, prepared for grandchildren. Imagine, not even for children, but for grandchildren.

To our happiness modern technologies Let us significantly speed up this process. And at least this process is still quite a lot and is complicated, it is still impossible to compare it with traditional technologiesand the result is even better.

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Humidity of sawn timber

It is important to understand that the tree is a living organism and in its cells contains moisture, while it is alive. In general, the moisture content of freshly chopped wood is equal from 30 and higher than percent. If we want to use wood, then we need to get rid of excess moisture. What kind of moisture is superfluous? It depends on what we are going to use the board or log, prepared for production. If the tree goes to the manufacture of products where it is required highest accuracy assembly (for example, for production musical instruments, sports equipment, parquet and some types of furniture), then its humidity needs to be reduced to 6-8 percent. If you simply prepare lumber to long-term transportation, for example, export, then humidity sufficiently reduce up to 20 percent.

This same wood will suit And for some types of buildings, for the production of containers and other goods. The remaining products require wood moisture between these two extremes. Floor boards, cash, the trim board may have humidity within 15 percent. BUT window Rama, doors, staircase elements or decorative products We will require wood from 8 to 15 percent of humidity.

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Making the dryer with your own hands

Consider finally the construction of the most drying chamber. First you need, in addition to the main building materials for the manufacture of the chamber, purchase a heating device, a fan and a good insulation.

Drying chamber diagram.

You can use the ready-made room for the construction of drying, and you can build it specifically. It is desirable that the ceiling and one wall are constructed from reinforced concrete, while the other walls are made of wood, which later need to hide heat insulating materials: First, they cover them with foam plates, we are cutting with clap and then cover all foil sheets. The next step must be installed any heating device, for example, a heating radiator in which water should heat up to 65-90 degrees. Since the continuity of heating is needed, it is better to immediately make a system of heating autonomous, with its oven and pump for the constant circulation of the coolant. It is absolutely necessary in the drying chamber and a fan that, overclocking the air around the room, should ensure the uniform of the warm-up of the entire drying space and laid wood.

In advance you need to think through the question of laying wood material for drying, how wood will be covered in it, whether it will lie in the middle of the camera or on special shelves etc. Good options For the loading of the tree is the trolley on the rails or a forklift. Take care of the presence of instruments for registering moisture and temperature in the drying chamber, without them it is impossible to effectively control over its operation.

Temperature diagram of the air and humidity in the drying chamber.

During construction, take into account some of the nuances. In the chamber, the drying should not sharply fluctuate the temperature, ensure everything possible to change smoothly. Otherwise, you risk to destroy all the stocks of the tree laid in the drying. It can go cracks and swallow. It is worth remembering about fire safety, because you are dealing with heating devices and large reserves of dry wood. To do this, keep the fire extinguisher in the immediate vicinity. Of course, something from the listed can be replaced by the analogues available in the house, in particular, the water heating radiator can be replaced with electric heating devices, up to the electric stove with a pair of enabled burners. Only again we remind you of fire safety, be careful. The walls of the dryer can be insulated not only by foam, but also by others suitable materials, up to the same wood chips, and foil can replace the foam, which is not bad to reflect heat radiation back to the chamber.

The main thing in construction is to achieve the creation of suitable conditions inside the chamber, and which material or technology you used, not critical. In such a domestic drying, sawn timber will dry about 1-2 weeks.

A vacuum dryer is another modern invention that allows you to quickly and high quality wood. But its applications are not so wide as the dryer infrared. Consider in more detail the properties of both devices.

One of the properties of wood is hygroscopicity, the ability to absorb moisture. Only the fired wood is half of the moisture, and the raw wood is unsuitable for the manufacture of furniture and creating building structures. It is strongly susceptible to biological lesions, warping and cracking.

For further use, freshly prepared lumber must be dried. Natural drying is a long process, so equipment was invented to speed up the drying of the wood.

Different dryers differ from each other by the principle of action and performance. Select optimal equipment for specific operating conditions, by comparing them. In this article we will dwell on infrared and vacuum dryers, we will deal with how they work, what volume of sawn timber and for what time they can dry, how much energy is spent, and what is their market price.

Principle of operation

IR dryer Infrared rays are produced, which warming wood dried to the required level of humidity. These rays have the same nature as visible light. They pass freely through the air. Nitrogen and oxygen molecules do not stroke the IR radiation, so all the energy is aimed at warming wood, and not air.

This method of drying does not imply the use of the coolant, which eliminates the need to follow its indicators and equip the equipment with complex automation.

Infrared heat acts on wood carefully, not leading to the occurrence of strong internal stresses and warping.

Vacuum dryers The market offers two main types: with cyclic and contact heating of the material. The principle of operation of the first is based on convective heat heating and vacuum removal of excess moisture. Working temperature It usually does not exceed 65 ° C, but the pressure of 0.09 MPa causes the moisture boiling already at 45.5 ° C. Vacuum allows you to dry lumber without the effects of high temperatures, thanks to which the tree is not cracking. During drying, when the temperature reaches 65 ° C, the boiler automatically turns off. The wood surface begins to cool, and the moisture from the inside to enter the dry plots. During the entire period of drying, the disconnection and re-launch occurs many times, and the moisture is pulled out evenly.

In the dryers with contact heating, the heat is transmitted by the material by means of thermoactive plates, which are stacked in the stack. Plates are warm or water or electricity.

Appearance

Infrared dryer - This is a set of thin thermoactive cassettes, which are stacked in the stack of lumber in a specific sequence and are connected to the power source. The stack prepared for drying is covered with a reflective layer material so that the condensate is glad outside the stack. The drying process is controlled by a thermostat responsible for maintaining a given temperature. Equipment is compact and convenient to use, if necessary, can be easily transported from place to place in the trunk of a passenger car


Vacuum dryer is a hermetic chamber from of stainless steel, made in the form of a cylinder or parallelepiped. The camera of the first type is tightly closed by the door, the second is covered with a rubber membrane in a metal frame.

In the dryers with contact heating, the board are stacked inside the chamber layers, alternating with heating plates. When used as a thermal agent hot waterHer circulation in the plates provides water pump. Water heating is produced by a boiler, and the vacuum is created by a liquid vacuum pump.

In cylindrical chambers of a large volume, the loading of the material is made along the rail path, which is mounted inside and outside.

Size and weight

Convenience infrared dryers There are their small dimensions and weight. One thermoactive cassette has a size of 1230x650x1.5 mm, that is, is a thin plate small square. The weight of the cassette is 5.7 kg. BUT standard set For drying 1 m³ of lumber includes 12 cassettes with a total weight of 69 kg. With a crate, control panel and cable wiring, the weight of the equipment does not exceed 130 kg. Its transport does not require the use of special equipment.


Vacuum press dryer even with a small loading volume has significantly larger and weight. Thus, the unit in the form of a parallelepiped with a loading volume of 4 m³ has dimensions 4800x1700x2005 mm and weighs without aluminum plates of 2300 kg. The size of the heating plate is 4000 × 1400 mm. For the transport of such equipment, a railway or automotive container will be required.

Autonomy of work

IR dryer Works completely offline. By installing and connecting the equipment correctly, you do not have to make additional monitoring of operating parameters. It will only be necessary to set drying mode, based on the quality of the source material, and in the future the thermostat will be followed by maintaining the specified temperature.

Drying process B. vacuum chamber also automated, but in this case A more complex automation is used, as it is necessary to monitor the parameters of the coolant (if available) and pressure. In some types of dryers, the process can be guided in manual mode. In most models, an emergency indication is provided, which is activated when the temperature is exceeded, reducing the degree of vacuum, changing the parameters of the coolant, etc.

Drying time

Drying time depends on the wood used and its initial level of humidity. Drying process pine board to the humidity of 8% using infrared Equipment can last from 3 to 7 days. The thinner the boards, the faster they dry.

IN different types vacuum dryer Temporary indicators are slightly different, but on average, the drying time of a pine board with an initial humidity of 50% to the total humidity of 8% lasts 16-18 hours.

Download volume

IR Cassette You can use for drying any number of sawn timber.

Vacuum chambers Offered from different loads: from 4 to 20 m³.

Power supply

Infrared cassettes Connect through the control shield to the 220 V network, the voltage is 380V.

Vacuum chambers Require a connection to a power supply with a voltage of 380 V.

Power and electricity consumption

Maximum power infrared dryer - 3.3 kW / m³. During the drying, 1 m³ of lumber is spent from 200 to 400 kW * h electricity.

Average power consumption vacuum chambers It is 15-37 kW. Unfortunately, there are often cameras in the market with truly fantastic electricity costs - from 50 kW / m³.

Price

Price - weighty argument when buying equipment.

Prices IR dryer Flexihite is highly available:

• set for drying 1 m³ three-meter board - 59 288 rub.;
• set for drying 1 m³ of four-meter board - 69 329 rubles;
• set for drying 1 m³ of six-meter board - 70 007 rub.

Prices vacuum chambers domestic production fluctuate within 500 thousand rubles, imported equipment is 3-4 times more expensive.

conclusions

IR dryer Easy to use can be used in production and in everyday life, suitable for drying any volume of lumber and have a democratic price.

In vacuum chambers Wood dries quickly and evenly, not deformed and even aligns, its color remains unchanged. But due to the high cost and large energy consumption, they are applied, it is advisable mainly for drying expensive wood.

February 19, 2017.

In the environment of Russian woodworking specialists, a method for drying sawn timber in vacuum has been discussed for quite a long time. Interest in the problem arose after the appearance of messages in the media on the installations of Italian production, and then the products of the WDE Maspell company in our market. After a while, the release of similar drying chambers was mastered by a number of domestic companies: "Energy-Stavropol", "MV-Impulse", etc.

Increased attention to such installations is due to the fact that their manufacturers announce the drying of the lumber into unprecedented short time: For 1-4 days, depending on the wood of wood and sawn thickness - and at the same time guarantee the high quality of the received boards or blanks. Such dates of drying caused distrust of those who had no opportunity in practice to check the quality of products dried in such chambers. Dispel these doubts does not allow extremely scarce information of equipment manufacturers for vacuum drying about the essence of the process. We will try to figure out.

Drying of sawn timber under reduced pressure (usually R abs \u003d 0.15-0.4 bar of absolute pressure or p separation \u003d 0.85-0.6 bar of permanent, which corresponds to the saturation temperature t us \u003d 54.0-75.9 ° C ) Refers to t. n. High-temperature drying process. This type of process takes place in the case when the temperature of the wood T dd exceeds the saturation temperature T of the water vapor at a given pressure. The flow of the high-temperature drying process is of greater intensity compared with the low-temperature process, when the temperature of the wood is below the saturation temperature (t us \u003d t of instrumentation, T KIP - boiling point). The velocity of the non-flowing vacuum drying in comparison with the regulatory stove mode of the convective chamber drying is 4-5 times higher. For example, for a group of hardening rocks (beech, cabin, ash, elm, etc.), the standard drying time for the low-temperature convective mode with a thickness of a 50 mm board is 12-14 days, the time of drying in press vacuum installations for the same assortments - Three or four days. The process of high-temperature drying is described in the domestic literature back in 1957. Below is information on wood and from the theory of high-temperature drying process.

"Water can be in two main structural elements Woods: In cavities of cells and blood vessels - free moisture, and in the walls of cell shells - hygroscopic, or related moisture. When drying the wet wood, first of all within the cell, free moisture is completely removed and only then below the hygroscopicity limit (W GHG), which is simultaneously the limit of the seniushka, begins to evaporate from her shell connected. With a decrease in the content of the knitted moisture, wood dries. "

"Consider the case of drying raw (W n\u003e W GHG) wood in the form of an unlimited plate in gas environment with temperature T C\u003e 100 ° C. At some intermediate stage of the process, all free moisture was removed from the outer zones of the plate. The humidity of these zones varies from equilibrium on the surface to saturation limit inside and has some mean werler. The inner zone thickness (S - 2X) at this stage remains raw, its humidity is close to the initial. The temperature of the internal zone is maintained at the level of boiling point of water T of instrumentation, and in the surface areas and the boundary layer gradually rises to T with. On the border of the zones there is a vaporation of free moisture, due to which this border is gradually plunged. "

Explain the possibility of preserving the impeccable quality of drying at such a significant intensity of high-temperature (even optionally using a vacuum) of the process, given the fact that when the saturation temperature is reached, we first on the surface, and then in the thickness of the lumber, there is an intensive evaporation of free water (pseudociament) and promotion of the resulting water vapor outwards. In the area of \u200b\u200bpseudociament in the steam medium, the relative humidity φ \u003d 100%, and the moisture content of the wood w tends to the equilibrium moisture content of W p \u003d 10.6 (φ / 100) (3,27-0,015t),% corresponding to the limit of hygroscopicity W p \u003d W PG (W GH \u003d 26.1% at T \u003d 54 ° C and W X \u003d 22.6% at T \u003d 75.9 ° C). The humidity W p g,% is the function of only temperature: W GHg \u003d (34.66-0.159t) - and is characterized by the fact that it is the boundary below which there is no free moisture in the cavities or in the walls of the wood cells. Under the condition of W.

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

The second condition: the temperature of the heaters should exceed the saturation temperature (boiling) with a pressure (resolution) created by definition.

The third condition (not mandatory for atmospheric plants): a reduced - relatively atmospheric - pressure is created in the chamber cavity. If the top cover of the chamber is made in the form of a flexible membrane (usually from silicone rubber), then due to the difference of pressure values, a pressing force is created between layers of lumber and heaters transmitted to layers on metal design The bottom of the camera. This pressing force provides the perfectly flat shape of the boards and the dense fit of the surface of the sawn timber to heaters, which is very important if the heat transfer between them is carried out by the conductive way. At the same time, accurate calibration in the thickness of the sawn timber is necessary to eliminate the lifting of the chalk of the boards to heaters.

To ensure the uniformity of heat transfer from heaters to the surface of the boards without their calibration, it is reasonable to organize heating with thermal radiation through a small gap between the plane of heaters and sawn timber, specially created due to the special protrusions of the heating plates (such projections are, for example, in the installations that the company "Energia produces -Tallolar "). The heat transfer radiation in the flat gap does not depend on its magnitude and from the inevitable lumber lumber in thickness.

As mentioned above, vacuuming for the high-temperature drying process is not mandatory conditionHowever, the press vacuum drying chambers have undoubted advantages, for example, the possibility of lowering pressure, and, consequently, saturation temperatures. First, the decrease in the temperature of the process helps to reduce heat losses in the installation and minimize the change in wood when drying. Secondly, the use of a membrane press helps to achieve perfect fixation of the plane of the dried boards and blanks. Thirdly, a dense clamp of heaters and sawdust layers ensures the uniformity of heat transfer during the drying process.

For the drying of thick assortments of the difficulty breeds (for example, oak), special modes are used at the stages of the wood moisture above and below the hygroscopicity limit. The use of these modes provides a low-spirited drying of a 50mm oak assortment for 6-8 days.

The process of press-vacuum drying wood is realized in installations with a single load from 0.5 to 10 m 3, providing 50 mm thick for the board (drying for four days) seven and a half of the chamber speeds (drying cycles) per month, and in case of drying sawn timber coniferous rocks (When drying for two days) - 15 camera speeds, for a boards with a thickness of 30 mm of hardening rocks (drying for two days) - 15 revolutions, coniferous rocks (drying during the day) - 30 speeds of the chamber per month.

Water evaporated with wood (about 250 l per 1 m 3 lumber), condensed on the metal walls of the chamber, as well as in the heat exchanger-capacitor (if it is provided by the design). Condensate merges into the sewer.

Briefly about some features of the structural design of installations for press-vacuum drying of wood "Energy" (producer - Energia-Stavropol LLC, Russia), as well as WDE Maspell (manufacturer - WDE Maspell SRL, Italy). Water flat heaters are used in these installations. In the chambers of other manufacturers, for example, MV-Impulse LLC and Voyager-East LLC (both companies are in Ufa), heaters are used with electrical ohmic heating elements. WDE Maspell cameras are equipped with electric water boilers, and the design of Energia-Stavropol companies allows you to use both electrical and gas water heating boilers as heating sources.

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

Text: Sergey Bondar

Drying is a mandatory stage of wood preparation before processing. To make the logs are not deformed, they dry them under certain conditions that are created in the drying chambers. For a home workshop, you can make wood dryer with your own hands.

The importance of drying

Ancient times during the manufacture of wood products, a forest was used, searched several years ago. Furniture made of raw or incorrectly dried board is swinging either fuse and go cracked. Hyd, the material is compressed, the raw beams from the tree will eventually behave, and the cracks will appear with the palm of the width. Mold starts in raw wood. But the porched boards are bad - the material begins to absorb moisture, swells.

The drying is carried out by hot air or steam, the process is long and expensive, but it gives wood extra strength, warns a change in shape and sizes, lumber is longer stored.

Drying modes

There are several sawn drying modes. In the chambers made independently, the temperature rises in stages, withdrawing moisture from raw material. The drying technology is chosen taking into account:

• wood breed;
• lumber dimensions;
• finite and starting moisture;
• features of the dryer;
• quality categories of raw materials.

The drying process can be high-temperature or low-temperature. In the second case, the primary processing is carried out at a temperature that does not reach 100 degrees.

Low-temperature modes are divided into categories:

• soft - in the drying process, sawn timber retain all their properties, the strength and painting does not change;
• normal - the color changes slightly, the strength is slightly reduced;
• forced - when they are frowning and splitting, brittleness is possible, the color is darkened.

Changing the temperature of the medium at low temperature mode is occurring in three stages. The transition to the next step is possible when the wood of a given humidity is achieved.

High temperature processing is produced in two steps. The second stage comes with a decrease in the moisture content of raw materials up to 20%. Such technology is used in the preparation of wood for the construction of secondary structures, allowing to make a change in color and reduce strength.

Types of drying chambers

Drying of wood B. industrial scale Performed in special chambers. The moisture is excreted from lumber with heated air and is taken out to the street. The device occurs full cycle Drying wood. The room may be:

• collectively metallic;
• erected from building materials.

The second are installed directly in the joinery shops or as the buildings standing apart. Walls are made of reinforced concrete or brick. In large enterprises, there are several cameras combined into a module with common system Control and loving communications. Air circulates in the dryer horizontally or vertically transversely. Wood in industrial dryers can be brought by rails on trolleys, laid out for forklifts.

Sources of heat in the dryer:

• hot couple;
• radiant heat from special devices;
• heated shelves of racks;
• electrotocks well passing through wet logs;
• high frequency electromagnetic field.

The camera is equipped with the main and additional equipment. The main consists of systems:

• supply-exhaust ventilation;
• heat supply;
• moisturizing.

Additional equipment is insulation of walls and doors, cartridges for laying material, psychometric equipment, electric drive.

Industrial dryers are automatically controlled, small homemade - manually. Humidity is regulated supply-exhaust ventilation and humidifiers. To measure humidity in the room there is a moisture meter that collects data simultaneously in several places.

As an energy source for air heating, it is possible to use: electricity, wood processing waste, liquid, solid fuel.

Types of dryers

According to the mode of air traffic, the camera is divided into:

• with natural;
• with forced air exchange.

Natural air exchange cameras are low, the process is not controlled in them. Therefore, they are still less.

According to the principle of operation, it is allocated:

• convective;
• condensation dryers.

In convective chambers, wood is blown by hot air flows, heat is transmitted by convection. They can be deep tunnel or chamber. In tunnel cameras, logs are loaded from one end and unloaded from the other, moving around the chamber, the material is gradually dried. The cycle duration ranges from 4 to 12 hours. Such cameras are installed on large sawmills. Chamber dryers are more compact, a single microclimate is supported throughout. Allowed to prepare any types of wood to the necessary condition. Therefore, most industrial chamber type dryers.

According to the technology of condensation drying, the moisture secreted from the material is deposited on the coolers, accumulates in the containers and merges the outside. The efficiency of such a device is very large, but the process is long, accompanied by high heat loss. The technology is good for the preparation of solid lumber with small batches. The price of equipment and the cost of condensation drying is lower than convective.

Arrangement of homemade dryer

In order to make the dryer with your own hands, you can do without drawings. It is necessary to provide:

• chamber room;
• insulation;
• heat source;
• fan.

The area of \u200b\u200bthe dryer, erected with their own hands, usually does not exceed 9 square meters. meters. In the square form, it is easier to ensure optimal movement warm air. It is desirable that one wall of the camera is made of concrete slabs, Other of wood. All walls are insulated from within two layers: expanded polystyrene foam and foil board. Beautiful and free insulation - wood shavings. And the foil can be replaced with foam, perfectly reflective heat.

A separate room of the dryer can be built of aluminum, such a structure will last long. Frame is performed from the profile, it is trimmed sheet metalwhich is instead outside. The thickness of the insulation is at least 15 cm. The floor is covered with rubberoid, a thick layer of chips pour over the thermal insulation.

It is necessary to take care of thorough sealing of the entrance door!

Heat emitter can be made in the form of pipes or heating radiators. The water temperature should be 65-95 degrees. It is heated by an electrical man, wood stove, gas boiler. For a small chamber, even two-component electric stoves. If the furnace is directly indoors, you need to put it with bricks. Brick will accumulate heat and gradually radiate it into the dryer. It is easy to equip a convective camera with your own hands, installing a fan heater as a heat source.

Having arranged the dryer for a domestic woodworking workshop, it is important to comply with fire safety. Near the building should always be a fire extinguisher.

The constant circulation of warm water is important, which is provided by the pump. So that the heat is evenly distributed on the room, the fan is installed. Work premises equipped with a wet and dry thermometer.

For the convenience of downloading the board to the camera, you can use the trolley on the rails. And to increase useful Square Racks are built on the walls.

Step-by-step instruction looks like this:

1. Construct the foundation.
2. We build a framework.
3. We are cutting with metal sheets.
4. Installation of thermal insulation.
5. We drag the floor with a film and sawdust.
6. Installation of supports from bars.
7. Installation of heaters and fans.

Design homemade chamber For drying sawn timber in the video:

Drying chambers for lumber are indispensable equipment in the production of wood-based billets. Before sending a tree to processing, it must be dried. Otherwise, the risk of deformation is significantly increasing, deterioration finished products. Drying is performed in special chambers under certain conditions. At the same time, many collect drying chambers with their own hands for use at home.

Not everyone knows exactly, why dry the tree before processing. Therefore, let's tell some nuances of this process.

1. For many centuries, wood acts as the main material in the manufacture of furniture.
2. The furniture was made from the forest, which was cut several years ago.
3. In the case of the use of raw, unpredied wood, the boards are rapidly succumbed, cracks are covered.
4. When drying, the tree is compressed, because the structures erected from the initially raw material can over time, lose the strength, geometry.
5. The raw tree is a great place to develop mold.
6. At the same time, excessively overwhelmed building materials are also bad, since such material actively absorbs moisture, increases in the amount due to swelling. Because to furniture, other structures there is an effect, reverse drying.

Drying is carried out in the drying chambers. At the same time, pairs are fed to the surface of the sawn hot air. This process occupies for a long time And costs the manufacturer quite expensive. In many ways, due to this, the furniture made on the basis natural wood, much more expensive MDF., Chipboard, etc.

The use of drying chambers allows to obtain the following lumber properties:

• Increased strength;
• Protection against the probability of change of forms;
• Preservation of primary sizes when applied;
• Increased service life, etc.

The task of the drying chambers is to increase the qualitative characteristics of the lumber. Therefore, drying is a mandatory stage of wood processing.

Features of the process

For drying sawn goods can be used various modes. In their own hands, the temperature increases the temperature occurs in stages, which makes it possible to gradually remove excess moisture from the material.

The mode and features of the drying process in the chambers are determined taking into account the analysis of the following parameters:

• The breed of dried wood;
• Sizes of materials;
• Initial humidity rate;
• The humidity indicator to be achieved;
• Constructive and technological features of drying chambers used for processing;
• The quality category of the treated lumber.

Types of drying

Drying with their own hands Wood inside the chamber is two types:

• Low temperature;
• High temperature.

The high-temperature processing process is performed in two stages. The transition to the second stage occurs when the moisture of the workpiece decreases to 20 percent. This technology Actual when applying wood as materials for the construction of secondary structures.

Low-temperature mode is divided into three categories.

1. Soft drying. Here lumber retain their characteristics, properties. Therefore, the color changes or the product strength parameters is not observed.
2. Normal drying. Color may vary, but slightly. Strength parameters are somewhat reduced.
3. Forced drying. Performing the splitting or rocking of raw materials dried in forced mode, it can become fragile. Also changing color, wood becomes dark.

Sources of heat

Drying chambers can use different sources of heat, whose task is to achieve the desired level of lumber humidity.

The following thermal sources are distinguished:

• Heated fertile;
• Radiant emitters;
• Heated racks;
• Electricity;
• High-frequency electromagnetic field.

The constructive chamber necessarily includes three components:

• Ventilation and exhaust system;
• Heat Salving Knot;
• Moisturizing system.

Dryers

Dryers differ in each other way of air traffic inside the chamber. Based on this parameter, the following varieties are distinguished:

• Systems with natural movement of air;
• Drying systems where the forced principle of air exchange is used.

Build your own hands easier the system where natural air exchange is used. In this case, the indicators of its effectiveness are significantly inferior to the forced circulation of air. For this reason, the chambers of a natural type are becoming more and less.

Dryers differ on the principle of their action. This is one of the main characteristics on which attention should be paid when choosing drying equipment or designing a drying chamber for its construction with your own hands.

1. Convective cameras. Inside them, lumber are blown by hot air flows. Heat transmission is carried out by convection method. Such dryers are divided into chamber and tunnels. The tunnel chamber assumes the loading of wood from one end and its unloading from the other. Gradually, moving on the dryer, the material acquires the necessary characteristics and parameters of humidity. The drying cycle in tunnel chambers is 4-12 hours, applied on large sawmills. The chamber of the dryer is characterized by compactness, an uniform microclimate is maintained within them throughout the chamber volume. Similar structures allow you to achieve of the desired characteristics lumber of different types. This led to the fact that the overwhelming majority of production, which are engaged in wood work, apply exactly chamber equipment.
2. Condensation chambers. Here moisture, which is distinguished from lumber, settles on the cooler, after which it accumulates inside a special container and is output. Such drying devices are distinguished by an increased efficiency. At the same time, the process of preparing wood occupies quite a long time and impressive thermal losses are observed. The best condensation technology shows itself when preparing small batches of wood, which is characterized by increased hardness. The cost of the equipment itself and the cost of operation of condensation chambers makes it preferable compared with convective aggregates.

Choosing equipment for drying wood - the question is quite serious, requiring a detailed study technical characteristics The chambers themselves and the characteristics of the processing of sawn timber to their further processing. Therefore, in case of questions, we recommend that you consult with experts.

Sometimes the manufacture of the dryer is preferable to buy factory equipment. But if you decide to assemble the device with your own hands, clearly adhere to the manufacturing technology. Violation of recommendations may entail unpleasant consequences For wood and invested in the manufacture of equipment equipment.