Drying chamber for wood. Homemade wood dryer DIY mini drying chamber for wood

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

Vacuum chambers for drying wood

In vacuum chambers, timber is dried under conditions high pressure 700 mmHg Art., but at a low temperature of 45 C. A 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
huge amount of electrical power for proper operation

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

Due to the high cost of the process, vacuum drying of wood is carried out mainly for expensive types of timber, such as oak, ash, beech, and cedar. In such cases, it is necessary to dry a large number of lumber. For mass production of lumber, convective drying chambers are used because they are more accessible and have a low cost.

Some examples of vacuum drying:

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

Under vacuum conditions, wood drys more gently. However, even with this drying method, cracking is possible. Wood is a living raw material. Wood is inherent different types stress. These stresses depend on the area in which the tree grew, on the cutting method, and on age. When drying wood, even in such chambers, not all stresses are relieved evenly.

How does vacuum drying of wood occur?

Injecting a vacuum inside the chamber where timber is dried significantly changes the physical nature of heat and mass transfer processes in wood. Drying is carried out by the action of a constant vacuum of 0.95 MPa and steam generated from the moisture of the timber. Since there is a natural movement of the drying agent at a speed of up to 0.3 m/sec, there is no need to use fans, lumber humidification systems, or install a dry/wet thermometer. Drying is controlled by lumber moisture sensors. For example, during the drying of oak lumber from an initial moisture level of 65% to a residual moisture level of 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, 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 you can dry different types of wood at the same time.

Drying quality:

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

DIY vacuum drying of wood

The drying process is very beneficial when done with your own hands. However, purchasing a factory-made vacuum chamber is quite expensive; in this section we will tell you how to make one yourself. Drying at home can be done in a special chamber, which requires a spacious room, a heat source, and a fan to distribute the heat inside the chamber.

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

In order to retain heat inside the chamber, the walls need to be insulated with foam plastic and lined with clapboard. In addition to polystyrene foam it will be suitable mineral wool and any other insulating material. 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 this, you can begin assembling the heating device. All heating system must be installed separately from other heating circuits; it must be constantly functioning. Will do heating radiator, which heats the water to 65-90 degrees. To distribute heat evenly in the chamber, it is worth purchasing a fan. Without it, drying will not occur evenly, and the final product will be of poor quality. Don't forget the rules fire safety during the creation of a vacuum dryer.

Another important point can be called the creation of a system for loading lumber into a chamber. For this purpose, you can use trolleys that move on rails or a forklift. Raw materials are placed on shelves or directly on the floor to dry. To monitor the drying process, you need to install special sensors - thermocouples and pressure sensors. If you approach this event wisely, you will end up with 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 top cells of the lumber absorb liquid from the cells located closer to the core. First, thin places dry out, then moisture from thick layers moves into already dry 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 workpieces.

Drying is a mandatory stage in preparing wood before processing. To prevent logs from becoming deformed, they are dried under certain conditions, which are created in drying chambers. For your home workshop, you can make a wood dryer with your own hands.

The importance of drying

Since ancient times, wood that was cut down several years ago was used to make wood products. Furniture made from damp or improperly dried boards will warp or dry out and crack. When drying, the material shrinks, raw wooden beams will begin to move over time, and cracks the width of a palm will appear in the walls of the log house. IN raw wood mold starts growing. But overdried boards are also bad - the material begins to absorb moisture and 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 increases in stages, removing moisture from the raw material. Drying technology is selected taking into account:

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

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

Low temperature regimes 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 ambient temperature at low temperature occurs in three stages. The transition to the next stage is possible when the wood reaches the specified moisture content.

High-temperature treatment 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 when preparing wood for the construction of secondary structures, allowing for color changes and a decrease in strength.

Types of drying chambers

Drying of wood on an industrial scale is carried out in special chambers. Moisture is removed from the lumber by heated air and carried outside. Happens in the device full cycle drying wood. The room can be:

prefabricated metal;
constructed from building materials.

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

Heat sources in the dryer:

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

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

supply and exhaust ventilation;
heat supply;
hydration.

Additional equipment includes insulation of walls and doors, trolleys for laying material, psychometric equipment, and electric drive.

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

The following energy sources can be used to heat air: electricity, wood processing waste, liquid and solid fuel.

Types of dryers

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

with natural;
with forced air exchange.

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

According to the principle of action, the following are distinguished:

convective;
condensation dryers.

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

Using condensation drying technology, moisture released from the material is deposited on coolers, accumulates in containers and is drained outside. The efficiency of such a device is very high, but the process is long and 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 are lower than convective drying.

Setting up 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 dryer built by yourself usually does not exceed 9 square meters. meters. In room square shape it is easier to ensure optimal movement warm air. It is advisable that one wall of the chamber be made of concrete slabs, others are made of wood. All walls are insulated from the inside in two layers: polystyrene foam and foil board. An excellent and free insulation material is wood shavings. And the foil can be replaced with penofol, which perfectly reflects heat.

You can build a separate drying room with your own hands 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 and poured on top as thermal insulation. thick layer shavings.

Care must be taken to thoroughly 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 stove, gas boiler. For a small chamber, even a two-burner electric stove is sufficient. If the stove is located directly in the room, you need to line it with bricks. The brick will accumulate heat and gradually radiate it into the dryer. It’s easy to equip a convection chamber with your own hands by installing a fan heater as a heat source.

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

Constant circulation of warm water, which is provided by the pump, is important. To ensure that heat is evenly distributed throughout the room, a fan is installed. Workroom Equipped with a wet and dry thermometer.

To make it easier to load the board into the chamber, you can use a trolley on rails. And to increase the usable area, shelving is built on the walls.

The step-by-step instructions are as follows:

We are building the foundation.
We are building the frame.
We cover the frame with sheets of metal.
Installation of thermal insulation.
Cover the floor with film and sawdust.
Installation of supports from bars.
Installation of heaters and fans.

The design of a homemade chamber for drying lumber in the video:

Friends!
Those who deal with wood, process it and use it in any way are forced to deal with the problem of drying it. Drying wood is always relevant and pays off, because “wet” wood is much cheaper, and dry, ready-made wood is very expensive. It is necessary to remove excess moisture from the wood so that the process of uneven evaporation of water and juices does not occur, which is associated with the heterogeneity of the wood structure along the longitudinal and transverse fibers. A wet wood is unsuitable for serious processing, and especially for construction, otherwise it will deform, crack, warp, and “lead.” How can you make a wood dryer with your own hands?

How to make a wood dryer with your own hands at home or in the country

If space permits, then it roughly looks like this:

First, we free up space in the kitchen near the stove or electric stove, fireplace, etc. You need to carefully calculate and measure how everything will function and look.
Partitions are installed from old doors and window frames, and other available materials; for tightness, everything needs to be adjusted and sealed. The size can be, for example, 2x2 or 3x3, depending on capabilities and needs.
Of course you have to leave it entrance doors and vents, and during drying keep them tightly closed so that there are no unnecessary drafts or simply excess air movement. Otherwise, this may lead to a less predictable drying process, loss of control over the process and loss of quality of the output wood.
The fenced-off area must be covered with insulation, all cracks must be sealed, plugged, caulked, etc. That is, to seal the space of the future dryer as much as possible to enclose the space and improve the quality of drying.
Since there is a high temperature near the stove or heating electrical appliance, then, if necessary, it is better to cover it with bricks that will accumulate heat and release it into a closed room. If the air does not circulate actively enough, a fan should be installed.
If you plan to dry a lot of wood or already finished products from it, you need to build strong metal shelves. It is better to secure it with anchors so that it can be loaded with serious weight.
To prevent the workpieces from bending, you need to fasten the edges of the material with pins. If the length of the wood is large, then several pairs of pins (3-4) are used. Of course, it is better to use wood of the same species, thickness, size and weight, otherwise drying will be very uneven. Be sure to lay out the material for drying with thin strips, bars, spacers for better ventilation. It is necessary to carefully monitor the uniformity of temperature and air flow, then drying will proceed more smoothly and the quality of the output material will be higher. Moreover, building several dryers is not very good big size more profitable than one larger one.

Do-it-yourself wood dryer, as a separate structure

First, a frame is constructed from aluminum profile, it will not rust, is lightweight and durable.
Then it also needs to be sheathed with aluminum sheets, and thermal insulation 10-15 cm thick must be fixed on top. This insulation must be fire-resistant, strong and flexible. Roofing felt should be laid on the floor and sawdust should be poured on top.
Next, you need to ensure the tightness of the building and seal everything possible ways outlet of heated air. The tightness of the structure is of great importance for high-quality drying.
The boards intended for drying should be laid out in narrow (1-1.5 m) stacks and spacers made of bars should be placed between the rows and boards. And the height of the stack can correspond to the height of the room.
Drying can be done using, for example, fan heaters, which should be installed across the air movement. Or choose another drying tool that suits your individual needs and capabilities.

A simple effective way of tubeless infrared drying of wood from 1 board

If you don’t want to build a dryer yourself or you don’t have the opportunity to do this, then you can use a ready-made solution.

There is a relatively recently used method of drying wood using infrared radiation. The process itself is as follows: the wood is heated with infrared rays using a tubeless cassette dryer. What is the design of such a dryer? It consists of several thermoactive cassettes 1.5 mm thick. The cassettes are stacked in a stack of wood prepared for drying, alternating with spacer bars. That is, the coolant is already among the lumber intended for drying. Therefore, there is no need for a separate heat source, ventilation, maintaining precise parameters, or complex electronics and automation. The drying is controlled by a thermostat, which sets the required temperature according to separate layers stacks. For more optimal performance drying design, the stack is covered with a material with a reflective layer so that the condensate drains outside the stack. It is important that the process can proceed as follows: outdoors(preferably under a canopy, to avoid possible precipitation), and indoors.

The advantages of this type of drying are

ease of maintenance,
equipment mobility,
high rates (8% humidity can be achieved).
high quality of the final material (no warping or internal stress),
speed (from 3 to 7 days),
variability, i.e. You can dry individual boards, or even just one, or entire large stacks.

You can watch a video about this technology here:

Drying wood from scrap materials. FlexiHIT.

Drying lumber in a tubeless cassette dryer

So, if you have a constant need for dry wood, then you can build a dryer, it’s not that difficult. Or buy a ready-made one and enjoy the finished dry lumber, which can be used to make various useful and interesting products.

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

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

For many centuries, wood has been the main material in the production of furniture.
The furniture was made from wood that was cut down several years ago.
If raw, undried wood is used, the boards quickly dry out and become covered with cracks.
When drying, wood shrinks, which is why structures built from initially raw material can become askew over time and lose strength and geometry.
Damp wood is a great place for mold to grow.
At the same time, excessively dry building material is also bad, since such material actively absorbs moisture and increases in volume due to swelling. Therefore, the opposite effect of drying occurs on furniture and other structures.

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

The use of drying chambers makes it possible to obtain the following properties of lumber:

Increased strength;
Protection against the possibility of shape changes;
Preservation of primary dimensions during use;
Increased service life, etc.

The purpose of drying chambers is to increase quality characteristics lumber. Therefore, drying is an essential stage of wood processing.

Process Features

Various modes can be used to dry lumber. In self-assembled chambers, the temperature increases in stages, which allows excess moisture to be gradually removed 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 wood being dried;
Dimensions of materials;
Initial humidity indicator;
Humidity indicator to be achieved;
Design and technological features of drying chambers used for processing;
Quality category of processed lumber.

Types of drying

There are two types of drying wood inside the chamber with your own hands:

Low temperature;
High temperature.

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

Low temperature conditions are divided into three categories.

Soft drying. Here the lumber retains its characteristics and properties. Therefore, no changes in color or strength parameters of the product are observed.
Normal drying. Color may vary, but only slightly. The strength parameters are slightly reduced.
Forced drying. When chopping or cleaving raw materials dried in a 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 up fell;
Radiant emitters;
Heated racks;
Electricity;
High frequency electromagnetic field.

The structural chamber necessarily includes three components:

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

Dryers

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

Systems with natural air movement;
Drying systems that use the forced air exchange principle.

Build it yourself simpler system where natural air exchange is used. At the same time, its effectiveness indicators are significantly inferior forced circulation air. For this reason, natural-type cameras are becoming increasingly rare.

Dryers are distinguished according to 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.

Convection chambers. Inside them, lumber is blown by hot air flows. Heat transfer is carried out by 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 through the dryer, the material acquires the necessary characteristics and humidity parameters. The drying cycle in tunnel chambers is 4-12 hours, used in large sawmills. Chamber type dryers are compact; inside they maintain a uniform microclimate throughout the entire volume of the chamber. Such designs make it possible to achieve required characteristics lumber various types. This has led to the fact that the vast majority of industries that work with wood use chamber equipment.
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 drying devices have a higher coefficient useful action. At the same time, the process of preparing wood takes a lot of time and significant heat losses are observed. Condensation technology works 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 makes it preferable compared to convective units.

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

Sometimes making a dryer yourself is preferable to buying factory equipment. But if you decide to assemble the device yourself, strictly adhere to the manufacturing technology. Violation of the recommendations can lead to unpleasant consequences for the wood and the funds invested in the manufacture of equipment.

For various wood products (furniture, musical instruments, parquet, etc.), their own drying temperature is used and a certain humidity is maintained.

Wood, despite the development of modern technologies, still remains an indispensable material in many sectors of the economy. It surrounds us everywhere, it is used in the production of furniture, in the construction industry, even in aviation it still finds its application. Of course, various polymers, synthetic resins, steels and alloys of various metals are actively replacing wood even in its traditional niches. But complete failure impossible. Therefore, there will always be a need to prepare wood for use in various branches of human activity, and to dry it. We will try to give answers to questions related to such necessary equipment as a lumber dryer, made and debugged with our own hands.

Why do you need to dry wood?

Drying lumber is an extremely necessary process, without which the wood simply cannot be used.

The quality of wood depends on proper drying.

If you have your own business related to the production of wood products, then you cannot do without your own drying chamber. But first, let’s try to understand why this dryer is needed, why we need to dry lumber. It's all about natural humidity any tree. If you make a product from undried wood, it will dry out over time, crack, and all you have to do is throw it away. In addition, properly dried wood improves its performance, becomes more durable, resistant to environmental influences and is less susceptible to destructive mold. In the old days, to prepare the forest for use, it was dried not even for years, but for decades. Often, logs prepared for grandchildren were laid under a special canopy. Imagine, not even for children, but for grandchildren.

Luckily for us modern technologies allow us to significantly speed up this process. And although this process is still quite long and complicated, it still cannot be compared with traditional technologies, and the result is even better.

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Moisture content of lumber

It is important to understand that a tree is a living organism and its cells contain moisture while it is alive. In general, the moisture content of a freshly cut tree is 30 percent or higher. If we want to use wood, then we need to get rid of excess moisture. What kind of moisture is excess? It depends on what we are going to use the board or log prepared for production for. If the tree is used for the manufacture of products where the highest precision of assembly is required (for example, for the production musical instruments, sports equipment, parquet and some types of furniture), then its humidity should be reduced to 6-8 percent. If you are simply preparing lumber for long-distance transportation, for example, for export, then it is enough to reduce the humidity to 20 percent.

This same wood will do and for some types of buildings, for the production of containers and other goods. Other products require wood moisture content between these two extremes. Floor boards, casing, and cladding boards can have a moisture content within 15 percent. A window frames, doors, staircase elements or decorative items will require wood from 8 to 15 percent moisture content.

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Making a dryer with your own hands

Let us finally consider the construction of the drying chamber itself. To begin with, you need, in addition to the basic building materials for making the chamber room, to purchase a heating device, a fan and good insulation.

Drying chamber diagram.

You can use a ready-made room for drying construction, or you can build it specially. It is advisable that the ceiling and one wall be constructed of reinforced concrete, while the remaining walls are made of wood, which must later be covered thermal insulation materials: first we cover them with foam plastic slabs, cover them with clapboard and then cover everything with sheets of foil. The next step is to install some kind of heating device, for example, a heating radiator, in which the water should be heated to 65-90 degrees. Since continuity of heating is necessary, it is better to immediately make the heating system autonomous, with its own stove and pump for constant circulation of the coolant. A fan is also absolutely necessary in the drying chamber, which, by dispersing the air throughout the room, should ensure uniform heating of the entire drying space and the stacked wood.

You need to think in advance about the placement of wood material for drying, how the wood will be brought into it, whether it will lie in the middle of the chamber or on special shelves, etc. Good options To load the wood, use a trolley on rails or a forklift. Make sure you have instruments for recording humidity and temperature in the drying chamber; without them it is impossible to effective control on her work.

Diagram of air temperature and wood humidity in the drying chamber.

During construction, consider some more nuances. The temperature in the drying chamber should not fluctuate sharply; make sure that it changes smoothly. Otherwise, you risk destroying all the wood reserves stored for drying. It may crack and warp. It is worth remembering about fire safety, because you are dealing with heating devices and large supplies of dry wood. To do this, keep a fire extinguisher nearby. Of course, some of the above can be replaced with analogues available in the house, in particular, a water heating radiator can be replaced with electric heating devices, up to an electric stove with a pair of burners turned on. Just remind you again about fire safety, be careful. The walls of the dryer can be insulated not only with polystyrene foam, but also with other suitable materials, up to the same wood shavings, and foil can be replaced by penofol, which is quite capable of reflecting thermal radiation back into the camera.

The main thing during construction is to achieve the creation suitable conditions inside the camera, and what material or technology you used is not critical. In such home drying, lumber will dry for about 1-2 weeks.