Do-it-yourself drying chamber for lumber. Tubeless infrared dryer for wood drying from the manufacturer Drawing of the drying chamber

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

Wood drying method different ways was invented back in the 60s, but due to the high cost 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 require high costs for electricity, although they are considered among 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. Temperature regime maximum +65 0С. 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. Top part 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 vacuum chambers this 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 solid metal, sewn on load-bearing 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 how it works microwave oven. Using a microwave chamber, you can dry the material of any section and size. microwave chambers have 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 complex system nozzles, piping, 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, the humidification of the air takes place 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.

One of the mandatory stages in the production of wood materials is harvested wood, produced in the open air and in special chambers, which protects the lumber from fungus, prevents deformation and changes in parameters.

Drying kilns for lumber operate in a certain mode, which is selected depending on the initial humidity, wood species, board thickness, planned use, taking into account the design features of the dryer.

The unit can also dry firewood that is used in heating solid fuel boilers, fireplaces.

Drying modes

During the drying process, the oven can operate in low temperature, normal or high temperature mode.

Low temperature and normal mode

Processing wood in a low-temperature way is carried out at 45 °. This is the softest method, it preserves all the original properties of the tree to the smallest nuances and is considered a high quality technology. At the end of the process, the moisture content of the wood is about 20%, that is, such drying can be considered preliminary.

As for the normal mode, it proceeds at temperatures up to 90 °. After drying, the material does not change shape and size, slightly reduced color brightness, strength. This is the most common technology used for various types of wood.

High temperature mode

In this mode, drying occurs due to the action of superheated steam (temperature over 100 °) or hot air. The high-temperature drying process reduces the strength of the wood, gives it a darker shade, so the material is used to create secondary building and furniture components. At the same time, drying with superheated steam will be more gentle than with the use of air.

Types of drying chambers

The dryer for boards can be with natural and forced air exchange. At the same time, the first option is inefficient and unpredictable. Therefore, in order to avoid unjustified risks, chambers with natural drying are almost never used at present.

According to the principle of operation, the following types of dryers can be distinguished:

• convective;
• condensation;
• vacuum;
• aerodynamic;
• microwave cameras.

The difference between the chambers in wood dryers is what equipment is used to heat the air, circulate it and lower the pressure.

convective

Drying chamber convective (convection) type is a rectangular insulated container with powerful ventilation in the ceiling edge, due to which air is distributed through heaters and wood. As a result of heating, the moisture of the lumber turns into steam, then leaves the chamber through special valves. This process of heat energy exchange is called convection.

Convective dryers are produced in two types: tunnel and chamber. In the first design, the boards enter the chamber from one side and are unloaded from the opposite side. Such models are mobile and designed for operation in large sawmill companies.

Chamber dryers provide for the launch and unloading of lumber through one door.

Convection chambers have the following features:

• in one cycle, 20 cubic meters of wood can be processed, provided that the volume is completely filled;
• all types of lumber can be dried, stacked in stacks with gaps;
• after drying, it is possible to perform steaming, impregnation of products;
• when connecting a solid fuel boiler for heating, the process will be more economical;
• the design has big sizes, therefore it is intended for stationary work (without departure).

The advantages include the high quality of drying, but if the chamber is not filled to 100%, then there will be a high probability of obtaining poorly dried wood (with overheating or high humidity) due to the uneven passage of hot air flows through the products. Possible disadvantage can be called high power consumption.

Condensing

Drying chambers of condensation type are similar in design to convection ones, but differ in the principle of operation. Wet steam, which occurs during the drying of wood, turns into water (condenses), which is collected in special containers. This technology is achieved due to the tightness of the drying chamber. The produced water is used for space heating.

Despite the cost-effectiveness of condensing units, the drying process takes a long time (about 2-3 weeks), while in convective units it takes from 1 to 2 weeks. Another disadvantage is the high cost of the unit.

vacuum

The dryer works on the principle of vacuum removal of excess moisture, the drying process consists of three stages: heating (preparatory), drying (with humidification), cooling. For a complete drying period, about 250 identical cycles are performed. The presence of a vacuum softens the effects of high temperatures and prevents the wood from cracking.

Differences of the vacuum drying chamber are:

• fast drying of wood;
• saving energy costs as a result of increasing the temperature of the functional heating plates embedded between the lumber.

Vacuum chambers are expensive to purchase and maintain, so it is unprofitable to dry pine or spruce in them.

Aerodynamic

The installation is a metal box with high-quality thermal insulation. The moisture formed as a result of drying flows into a special collection. Heated air circulates in a closed space with the help of a special aerodynamic screw, which gives its energy to the drying process.

The chamber must be fully loaded with lumber, only then the quality of work will not suffer. Maintenance of an aerodynamic wood dryer does not require specific knowledge, the installation is fully automated.

The disadvantages are the relatively long drying process (about 20 days), high energy consumption, lack of temperature control.

microwave cameras

Microwave drying technology has been developed relatively recently. The unit is a closed metal container with a door in the end wall and operates on the principle of a microwave oven. Microwave radiation heats the wood, from which water molecules are squeezed out under pressure.

The camera is convenient in that it can be placed anywhere in the room. Thanks to the powerful effect electromagnetic waves drying wood takes no more than 6 days.

The advantage of the microwave installation is also in the high quality of drying with the right mode.

The dryer is expensive due to the high consumption of electricity and the need from time to time to change the main spare part - the magnetron (a device for emitting electromagnetic waves).

DIY manufacturing

Drying wood in a private way requires a special chamber, which you can make yourself. If you have to build a dryer for wood with your own hands, then on a plot of land you need to allocate an area of ​​\u200b\u200babout 10 m 2 for installation. You will need concrete for the foundation, material and thermal insulation for the walls, polyurethane foam, ventilation system, boiler and auxiliary equipment.

Stages of construction

The construction of a mini-dryer consists of successive stages:

• preparation of the foundation for installation;
• walling;
• thermal insulation;
• installation of the roof and doors;
• installation on the ceiling of radiators and fans;
• installation of the boiler in compliance with safety regulations, laying pipes.

Such work will be justified with regular use of the finished object. The drying chamber will need to be fully loaded and the drying technology strictly observed.

Foundation construction

The site is marked out taking into account the length of the lumber and the total width of the stacked stacks, plus a loading allowance of about 30 cm.

After marking the site, it must be concreted in such a way that the floor level of the chamber is about 10 cm higher than the ground level. A concrete platform is made with sides protruding half a meter. To prevent water from accumulating in the drying chamber, the foundation must be made with a certain slope. You should also provide for the filling of rails for the transport of carts with products.

Walling

As a material, you can use brick, sandwich panels, railway container. The most common material is wood. Three walls are made from it, and it is desirable to make the fourth from concrete.

The height of the wood drying chamber is the sum of the height of the stacks, the loading allowance of 30 cm and the height of the fans and radiators. When building a small chamber, the height is calculated taking into account the filling of the entire volume.

The heating of the installation provides for the presence of a source of thermal energy, therefore, when installing the walls, it is required to build an extension for the boiler and its auxiliary equipment.

Roof insulation and installation

Dry shavings or sawdust, which are applied to the walls in the form of a mixture with cement and an antiseptic, can serve as an effective and economical heat insulator material. To keep warm, the floor is covered with shavings.

The roof of a makeshift room is mounted with a slope so that the snow does not linger on it. Then the doors are installed by hanging on an I-beam or hinged.

Equipment installation

Fans should be positioned vertically across the width of the ceiling to distribute heat evenly. Next row will consist of radiators. To keep the heat in the drying chamber, you first need to seal the slots with mounting foam.

Heat is supplied to the radiators from a boiler that can run on electricity, liquid or solid fuel. Usually, a wood-burning boiler is chosen to heat the drying chamber. Pipes are brought to the boiler, then an anti-explosion valve is installed that regulates the operation of the equipment.

Mandatory and proper drying in a home-made or purchased drying chamber is a reliable guarantee of the quality of lumber.

Drying is an obligatory stage of wood preparation before processing. To prevent the logs from deforming, they are dried under certain conditions, which are created in the drying chambers. For a home workshop, you can make a wood dryer with your own hands.

The importance of drying

Since ancient times, in the manufacture of wood products, wood has been used, cut down several years ago. Furniture made from damp or improperly dried boards will warp or dry out and crack. Drying, the material shrinks, raw wooden beams will lead over time, and cracks with a palm width will appear in the walls of the log house. Mold grows in damp wood. But overdried boards are also bad - the material begins to absorb moisture, swells.

Drying is carried out with hot air or steam, the process is long and expensive, but it gives the wood additional strength, prevents changes in shape and size, and the lumber is stored longer.

Drying modes

There are several modes of drying lumber. In self-made chambers, the temperature rises in stages, removing moisture from the raw materials. Drying technology is selected taking into account:

• types of wood;
• lumber dimensions;
• final and starting humidity;
• features of the dryer;
• raw material quality categories.

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

Low temperature modes are divided into categories:

• soft - during the drying process, lumber retains all its properties, strength and color do not change;
• normal - color changes slightly, strength decreases slightly;
• forced - when chipping and splitting, brittleness is possible, the color darkens.

The change in the temperature of the medium in the low-temperature regime occurs in three stages. The transition to the next stage is possible when the wood reaches the specified moisture content.

High-temperature processing is carried out in two stages. The second stage occurs when the moisture content of the raw material decreases to 20%. This technology is used in the preparation of wood for the construction of secondary structures, allowing for a change in color and a decrease in strength.

Types of drying chambers

Drying wood in industrial scale produced in special chambers. Moisture is removed from the lumber by heated air and taken out into the street. The device is full cycle drying wood. The room can be:

• prefabricated metal;
• built from building materials.

The latter are installed directly in the carpentry shops or as separate buildings. The walls are made of reinforced concrete or brick. At large enterprises, several cameras are equipped, combined into a module with common system control and communications. The air circulates in the dryer horizontally or vertically transversely. Wood in industrial dryers can be transported on rails on trolleys, laid out by forklifts.

Heat sources in the dryer:

• hot steam;
• radiant heat from special devices;
• heated shelves of racks;
• electric current that passes well through wet logs;
• high frequency electromagnetic field.

The camera is equipped with basic and additional equipment. The main system consists of:

• ventilation of supply and exhaust type;
• heat supply;
• moisture.

Additional equipment is wall and door insulation, trolleys for laying material, psychometric equipment, electric drive.

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

As an energy carrier for air heating, you can use: electricity, wood processing waste, liquid, solid fuel.

Types of dryers

According to the method of air movement, the chambers are divided into:

• with natural;
• with forced air exchange.

Chambers with natural air exchange are inefficient, the process in them cannot be controlled. Therefore, they are used less and less.

According to the principle of action are distinguished:

• convective;
• condenser dryers.

In convection chambers, the wood is blown with hot air currents, heat is transferred by convection. They can be deep tunnel or chamber. Logs are loaded into the tunnel chambers from one end and unloaded from the other, moving along the chamber, the material is gradually dried. The duration of the cycle is from 4 to 12 hours. Such cameras are installed at large sawmills. Chamber dryers are more compact, a single microclimate is maintained throughout the volume. Allow to prepare any types of wood to the required condition. Therefore, most industrial dryers are of the chamber type.

According to the technology of condensation drying, the moisture released from the material is deposited on the coolers, accumulates in containers and drains to the outside. The efficiency of such a device is very high, but the process is long, accompanied by high heat losses. The technology is good for preparing hard lumber in small batches. The price of equipment and the cost of condensation drying is lower than that of convective drying.

Arrangement of a homemade dryer

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

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

The area of ​​a do-it-yourself dryer usually does not exceed 9 square meters. meters. In a square-shaped room, it is easier to ensure optimal movement of warm air. It is desirable that one wall of the chamber be made of concrete slabs, others made of wood. All walls are insulated from the inside in two layers: polystyrene foam and a foil board. Excellent and free insulation - wood shavings. And the foil can be replaced with penofol, which perfectly reflects heat.

A separate do-it-yourself dryer room can be built from aluminum, such a structure will last a long time. The frame is made from a profile, it is sheathed sheet metal which is insulated from the outside. The thickness of the insulation is at least 15 cm. The floor is covered with roofing felt, a thick layer of shavings is poured on top as thermal insulation.

Care must be taken to carefully seal the front door!

The 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 electric boiler, wood-burning stove, gas boiler. For a small chamber, even a two-burner electric stove is enough. If the stove is located directly in the room, you need to overlay it with bricks. The brick will accumulate heat and gradually radiate it into the dryer. It is easy to equip a convection chamber with your own hands by installing a fan heater as a heat source.

When equipping a dryer for a home woodworking workshop with your own hands, it is important to follow the measures fire safety. There should always be a fire extinguisher near the building.

The constant circulation of warm water, which is provided by the pump, is important. To distribute heat evenly throughout the room, a fan is installed. work space Equipped with a wet and dry thermometer.

For the convenience of loading the board into the chamber, you can use a trolley on rails. And to increase usable area racks are built on the walls.

The step-by-step instruction looks like this:

1. We are building a foundation.
2. We raise the frame.
3. Sheathe the frame with sheets of metal.
4. Installation of thermal insulation.
5. We cover the floor with foil and sawdust.
6. Installation of supports from the bars.
7. Installation of heaters and fans.

Design homemade camera for drying lumber in the video:

Drying kilns for lumber are indispensable equipment in the production of wood-based blanks. Before sending a tree for processing, it must be dried. Otherwise, the risk of deformation, deterioration in quality increases significantly. finished products. Drying is carried out in special chambers under certain conditions. At the same time, many people assemble drying chambers with their own hands for use at home.

Not everyone knows exactly why to dry a tree before processing. Therefore, we will tell you some of the nuances of this process.

1. For many centuries, wood has been the main material in the manufacture of furniture.
2. The furniture was made from wood that had been cut down a few years ago.
3. In the case of using raw, non-dried wood, the boards dry out quickly and become covered with cracks.
4. When dried, the tree shrinks, therefore, structures erected from initially raw material may squint over time, lose strength, and geometry.
5. Damp wood is a great place for mold to grow.
6. At the same time, an excessively overdried building material is also bad, since such material actively absorbs moisture, increases in volume due to swelling. Therefore, to furniture, other structures, an effect occurs that is the opposite of drying.

Drying is carried out in drying chambers. In this case, steam is supplied to the surface of the lumber or hot air. This process takes long time and is quite expensive for the manufacturer. Largely because of this, furniture made on the basis of natural wood, much more expensive than MDF, chipboard, etc.

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

• Increased strength;
• Protection against the likelihood of changing forms;
• Preservation of primary dimensions during application;
• Extended service life etc.

The task of drying chambers is to improve the quality characteristics of lumber. Therefore, drying is an obligatory stage of wood processing.

Process features

For drying lumber, various modes can be used. In do-it-yourself chambers, the temperature rises in stages, which allows you 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 type of dried wood;
• Dimensions of materials;
• Initial humidity indicator;
• Humidity index to be achieved;
• Design and technological features of drying chambers used for processing;
• Quality category of processed lumber.

Types of drying

Do-it-yourself drying of wood inside the chamber is of two types:

• Low temperature;
• High temperature.

The high temperature treatment process is carried out in two steps. The transition to the second stage occurs when the moisture content of the workpiece drops to 20 percent. This technology relevant when using wood as materials for the construction of secondary structures.

Low temperature mode is divided into three categories.

1. Soft dry. Here lumber retains its characteristics and properties. Therefore, changes in color or strength parameters of the product are not observed.
2. Normal drying. Color may vary, but only slightly. Strength parameters are somewhat reduced.
3. Forced drying. Performing splitting or chipping of raw materials dried in forced mode, it can become brittle. The color also changes, the wood becomes dark.

Heat sources

Drying chambers can use different heat sources, the task of which is to achieve the desired level of moisture in the lumber.

The following heat sources are distinguished:

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

A constructive chamber necessarily includes three components:

• Ventilation and exhaust system;
• Heat-saving unit;
• Humidification system.

Dryers

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

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

It is easier to build a system with your own hands that uses natural air exchange. At the same time, its efficiency indicators are significantly inferior to forced air circulation. For this reason, cameras of the natural type are becoming less and less common.

Dryers are distinguished by the principle of their operation. This is one of the main characteristics that you should pay attention to when choosing drying equipment or designing a drying chamber for building it yourself.

1. convection chambers. Inside them, the lumber is blown by hot air currents. Heat transfer is carried out by the convection method. Such dryers are divided into chamber and tunnel. The tunnel chamber involves loading wood from one end and unloading it from the other. Gradually, moving on the dryer, the material acquires the necessary characteristics and moisture parameters. The drying cycle in tunnel chambers is 4-12 hours, they are used in large sawmills. The chamber type of dryers is compact, inside they maintain a uniform microclimate throughout the entire volume of the chamber. Such structures make it possible to achieve desired characteristics lumber various types. This has led to the fact that the vast majority of industries that work with wood use chamber equipment.
2. condensation chambers. Here, the moisture that is released from the lumber settles on the cooler, after which it accumulates inside a special container and is discharged outside. Such dryers are characterized by an increased efficiency. At the same time, the process of preparing wood takes a lot of time and there are impressive heat losses. Condensation technology shows itself best when preparing small batches of wood, which is characterized by increased hardness. The cost of the equipment itself and the cost of operating condensation chambers make it preferable compared to convective units.

The choice of equipment for drying wood is a rather serious issue that requires detailed study. specifications the chambers themselves and the features of the process of preparing lumber for their further processing. Therefore, if you have any questions, we recommend consulting with specialists.

Sometimes making a dryer with your own hands is preferable to buying factory equipment. But if you decide to assemble the device with your own hands, strictly adhere to the manufacturing technology. Violation of the guidelines may result in backfire for wood and funds invested in the manufacture of equipment.

Any woodworking enterprise cannot do without such a procedure as wood drying. And so that no defects appear in the process, a special drying chamber for lumber should be used. Such a dryer will also be useful for those who are engaged in the production of wood products at home, in such cases it can be done by yourself.

Importance of drying for wood

Wood for the manufacture of various products must first be dried so that it is suitable for subsequent use. So, if your furniture is made on the basis of too wet wood, then it will quickly dry out and become unusable. And if the tree is too dry, then, for example, the door will quickly swell and will not close.

Also, drying a tree is useful for the following reasons:

• the material is protected from fungal attack;
• change in size and shape is prevented;
• improved mechanical and physical properties material.

Drying is a lengthy process, the wood is heated with hot air or superheated steam. After drying, the tree can be stored and transported longer, it will not be deformed.

Drying chamber for lumber

Kiln drying is a key way to dry wood. With the help of dryers, deciduous and conifers before different types quality. The most common and economical drying technique is as follows. Free and bound moisture is removed from the wood by supplying heat to the damp wood using hot air. Further, the removal of excess evaporated moisture occurs with the help of humidified and partially cooled air.

The drying chamber is the whole ready installation equipped with all necessary equipment for work. By their design, such chambers are prefabricated metal or assembled from building materials. The latter are made directly in the workshops or as free-standing buildings based on industrial materials.

The chamber can be entirely made on the basis of monolithic reinforced concrete, the walls can be made of solid red bricks, and the ceiling can be made of reinforced concrete.

If several chambers are used in production, they can be combined into one block, which has a corridor with heat supply wiring and a system automatic control. Depending on the volume of loaded wood, the air circulation can be horizontal-transverse or vertical-transverse.

Lumber can be loaded into the chamber on trolleys along the rail track or as packages using a forklift. Heat is transferred to wood in the following ways:

• through the air;
• through the products of combustion;
• using superheated steam;
• radiant warmth;
• solid body;
• through current;
• through an electromagnetic field.

The equipment for this device is basic and additional. The main includes the following:

• fan system;
• heating system;
• humidification and supply and exhaust ventilation.

To additional equipment relate:

• blocks (door, psychrometric and insulated);
• fan drive electric motor;
• stacked carts.

The drying control process can be automated, which helps to maintain the temperature and humidity inside the chamber at a certain level. The temperature is regulated by supplying the coolant to the heaters or by turning the electric heater on or off.

Humidity can be adjusted using a remote moisture meter, which allows you to check the condition of the material remotely at several points at once. If there are no external sources of heat supply, then autonomous heating means powered by electricity, coal, gas, lumber or diesel fuel can be used.

Structure classification

In convection-type chambers, energy enters the wood through the air cycle, and heat transfer occurs through convection. Such structures are tunnel or chamber.

Tunnel dryers have a greater depth, they push stacks of stacks from one end (wetter) to dry. They are obligatory filled from one end, and emptied from the other. Stacks are pushed one at a time every 4-12 hours. These dryers are used for large sawmills and help carry out transport drying.

Chamber dryers are shorter; during the drying process, the same parameters are maintained throughout the chamber. If the blowing depth is from 2 meters, then in order to equalize the drying conditions, the method of reversing the ventilation direction is used. The chamber is filled and emptied from one side if there is only one door. Lumber can be dried any to different indicators of humidity. It is these designs that are most often used in our country.

The condensation type of dryer is different in that the moisture that has arisen in the air begins to condense on special coolers, and then the liquid is removed. The efficiency here is high, but the cycle is long, since devices with a high temperature do not work and large heat losses are observed. These types of equipment are more suitable for processing small volumes of materials or drying wood of dense species - ash, beech or oak. But condensation chambers also have a number of advantages:

• no need for a boiler room;
• the cost of the camera and the cost of operation are low.

Drying chambers also differ in the way of circulation and the nature of the drying agent, the principle of operation and the type of fence.

For example, circulation can be natural or forced. The designs of the first type are outdated and inefficient, it is almost impossible to control the modes, and the uniformity of the drying of the material leaves much to be desired. At modern requirements it is better not to use such dryers.

By the nature of the drying agent, the chambers are:

• air;
• gas;
• high temperature.

Drying modes

Depending on the quality requirements, lumber drying in a special apparatus is carried out in different modes, which differ from each other in temperature. If it is a mini chamber, then in the process the temperature slowly rises and the relative humidity of the agent decreases.

One or another mode is selected taking into account the following factors:

There are modes of high-temperature and low-temperature process. In low temperature is used as an agent wet air, the initial temperature is less than 100 degrees. There are three categories of these types of modes:

• soft - drying is carried out without defects, the mechanical and physical properties of the wood are preserved, including its color and strength;
• normal - drying is also carried out without defects, strength is retained almost completely, color may vary slightly;
• forced - the strength for static bending, tension and compression is maintained, but the strength for chipping and splitting with darkening may decrease.

In high temperature conditions there is a two-stage change in the agent's indicators, it is possible to switch to the second stage from the first only when the wood reaches a transitional moisture content of 20 percent.

Such modes are assigned depending on the species and thickness of the wood, and are assigned for drying materials used in the production load-bearing structures buildings and those products where it is possible to use dark wood with reduced strength.

Before starting work on one or another mode, the lumber must be heated with steam supplied through the humidifying pipes with the fans running, closed exhaust ducts and heating appliances.

Be sure to calculate the chamber for lumber. The temperature of the drying agent at the beginning of heating should be 5 degrees higher than the first stage of the mode, but not higher than 100 degrees. The saturation level of the environment for a material with an initial moisture content of 25% is 0.98−1, and if the humidity is below this indicator, then 0.9−0.92, respectively.

Duration initial period depends on the type of tree. For conifers, it is up to 1.5 hours per centimeter of thickness. For soft hardwoods it will be 25 percent more, and for hard hardwoods it will be half as much compared to softwoods.

After preheating, it is necessary to bring the indicators of the drying agent to the first stage of the operating mode. Then drying is switched on directly in compliance with the selected mode. Humidity and temperature can be controlled using valves on the steam lines or dampers on the supply and exhaust ducts.

During the operation of an infrared dryer, residual stresses appear in the materials, which can be removed by intermediate and final moisture and heat treatment in an environment of high humidity and temperature. It is necessary to process those lumber that are dried to operational performance and then need to be machined.

Intermediate moisture heat treatment must be carried out during the transition from the second stage to the third, or from 1 to 2 when using a high temperature. Coniferous species 60 mm in thickness or hardwood with a thickness of 30 mm or more are subjected to such processing. The temperature of the medium should be 8 degrees higher compared to the second stage, but not more than 100 degrees, provided the saturation is 0.95-0.97.

When the final average moisture content of the material is reached, the final moisture heat treatment can be performed. It is carried out at a temperature of 8 degrees above the previous stage, but not higher than 100 degrees. Further, the tree must be kept in the chamber for another 2-3 hours at the parameters of the last stage of the mode and only then stop the operation.

Drying chamber manufacturing

If you are engaged in the manufacture of wood products at home, then you will need to dry the material yourself. You can also make your own dryer., but you must follow all the rules of work. For manufacturing you will need:

• camera;
• heating device;
• fan;
• insulation.

One wall and ceiling of the chamber should be made of concrete, and the remaining walls will be made of wood, they will need to be insulated. There will be several layers:

• Styrofoam;
• boards wrapped in foil.

Now you need to install a heating element, it can be in the form of batteries. Water can be supplied to them from the stove in a heated form at a temperature of 60 to 95 degrees. It is best to ensure a continuous process circulation of water by means of water pumps in the heating element. You will also need to install a fan in the chamber, with which warm air will be distributed throughout the room.

It is imperative to provide a method for loading wood into the chamber. For example, it can be a rail cart. To control the temperature and humidity in the work area, you need to install wet and dry thermometers. And also inside the dryer You need to put shelves to expand the workspace.

During processing, a sharp change in temperature should not be allowed, otherwise the wood may crack or warp.

The work on the construction of the chamber must be carried out subject to fire safety requirements so be sure to install fire extinguishers.

And instead of heating element can be applied electric stove from two burners. The walls of the chamber can be insulated with wood shavings, and instead of foil, you can take penofol, which can reflect heat well from the surface of the walls. Drying in such a chamber is carried out within 1-2 weeks.

Thus, there is a large number of various modifications of drying chambers for wood. One or another option should be chosen depending on the material itself and the expected results. And when it comes to the production of various wooden products at home, then the camera is easy to do with your own hands.