Vacuum dryer device. DIY wood dryer: drawings

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, is still an indispensable material in many sectors of the economy. It surrounds us everywhere, it is used in the manufacture 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 actively replace wood even in its traditional niches. But a complete rejection is not possible. Therefore, there will always be a need to prepare wood for use in various branches of human activity, in its drying. 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 dry wood?

Drying for lumber is extremely required process, without which 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 can not do without your own drying chamber. But first, let's try to understand why this dryer is needed, why lumber needs to be dried. It's all about natural humidity any tree. If you make a product from undried wood, then it will dry out over time, crack, and all that remains is to throw it away. In addition, a properly dried wood improves its working qualities, 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.

To our happiness 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, freshly cut wood has a moisture content of 30 percent or more. 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 for. If the tree is used for the manufacture of products where the highest assembly accuracy 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 just preparing lumber for long-distance transportation, for example, for export, then it is enough to reduce the humidity to 20 percent.

The same wood is also suitable for some types of buildings, for the production of containers and other goods. Other products require wood moisture between these two extremes. Floor boards, cashing, sheathing boards can have a moisture content in the range of 15 percent. BUT window frames, doors, stair elements or decorative items will require wood from 8 to 15 percent moisture.

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Making a dryer with your own hands

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

The scheme of the drying chamber.

You can use a ready-made room for the construction of drying, or you can build it specially. It is desirable that the ceiling and one wall be made of reinforced concrete, while the rest of the walls are made of wood, which later need to be covered. thermal insulation materials: first we cover them with foam plates, sheathe 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 continuous heating is necessary, it is better to immediately make the heating system autonomous, with its own furnace and pump for constant circulation of the coolant. Absolutely necessary in the drying chamber is a fan, which, dispersing the air around the room, should ensure uniform heating of the entire drying space and the laid wood.

In advance, you need to think over the issue of laying 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 for loading wood is a trolley on rails or a forklift. Take care of the availability of devices for recording humidity and temperature in the drying chamber, without which effective control over its operation is impossible.

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

When building, consider some more nuances. The temperature in the drying chamber should not fluctuate sharply, make sure that it changes smoothly. Otherwise, you run the risk of destroying all the stocks of wood laid in the drying. It can crack and warp. It is also worth remembering fire safety, because you are dealing with heating appliances and large stocks 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 heaters, up to an electric stove with a pair of burners on. Only again we remind you of fire safety, be careful. The walls of the dryer can be insulated not only with polystyrene, but also with others. suitable materials, up to the same wood shavings, and penofol can replace the foil, which is well able to reflect thermal radiation back into the camera.

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

Qualitatively dried lumber has always been a guarantee of quality, durability and reliability of any structure in which wood occupies a significant share. But get it in vivo difficult and at the same time, so that it does not deteriorate. Drying time under normal atmospheric conditions can be from 6 to 12 months, depending on temperature and humidity. environment. During natural heat treatment, the material undergoes unwanted deformations, warping and cracking.

To improve the quality of lumber drying, many equipment options were invented, often they try to make a vacuum drying chamber for wood with their own hands - because. this technology is considered one of the most effective. But the problem is that it is quite difficult to make such a unit on your own. Nevertheless, there are craftsmen who make them from old tank bodies or thickened sheet steel. Basically, these are mini cameras with a loading volume of 5-10 cubic meters.

What is vacuum drying wood with your own hands?

Do-it-yourself vacuum wood dryer is quite possible if you have a case from a rocket, a tank, or any other similar type of product from which you can make a shell for equipment.

Main structural elements:

frame
Vacuum pump
heating elements (heaters, plates, steam generator, microwave radiators, etc.)
trolley for loading lumber
automation

You will need a pump to pump out air and create a vacuum. You can warm up lumber with any known way, which can be a contact method, air-gas and water vapor.

A do-it-yourself vacuum chamber is quite complicated in the technical part, because it will be quite difficult to find many details for its manufacture. And ordering them specifically is tantamount to ordering the camera itself. Therefore, before starting to design vacuum drying chambers for wood with your own hands, you should consider whether it is expedient or if it might be better to order it from a specialized company.

Do-it-yourself thermal chamber for wood - thermowood production

Thermal vacuum chamber technology has been around since the last century. The thermo dryer has much in common with the vacuum kiln for drying lumber.

To make a vacuum chamber for thermal wood, you need to take into account the technical features:

Wood processing takes place at high temperatures
The chamber body must withstand high pressure

These 2 points are important to consider for the safety of personnel.

An important task is the choice of agent: oil or steam. Also technical modes. With incorrect modes, thermal drying takes place only on the surface of the wood, while lumber may not acquire the desired properties:

deep color change
fire resistance
increased resistance to decay

Make a homemade thermowood chamber just like thermowood itself at home difficult task. Competent specialists ready to share their experience are unlikely to be found on forums, videos, or somewhere on the net. If you have any questions, please contact the manufacturers.

Vacuum dryers for wood: do-it-yourself or professional?

Our company is engaged in the production of high-quality and highly efficient drying chambers vacuum type is not the first year, so I'm ready to offer a really reliable and practical option.

But if you need a wood vacuum dryer small sizes for heat treatment of small parts and you want to make it yourself, then there is a need for a drawing. Drawings on this topic are enough a rare thing, from those that are found with a low probability, a camera capable of working in a production environment will come out.

However, if you are going to buy finished equipment, then the most effective option are chambers with contact technology for heating lumber along the entire length, the rejection rate is less than 1, and the drying time is up to 6-8% moisture pine board 30 mm thick will only be about 60 hours.

Wood drying technology

vacuum drying

The wood drying process consists of several stages. First, it is evaporated from the surface of the material, and then from its inner part. Thin places dry first, then moisture moves to them from thicker layers. If the process is disturbed, then the thin layers begin to shift and the material is destroyed. To prevent this from happening, the blanks are treated with a special mixture. It is made from drying oil and chalk. The resulting composition is treated with the end parts of the blanks. They usually always have the form of an equilateral geometric figure.

The fast dry mode is distinguishing feature vacuum drying chamber. It is known that water begins to evaporate when it boils. Very low pressure is created in the chamber. As a result, water boils at low temperatures, than usual. Thus, the process time is significantly reduced.

Another significant plus is that vacuum drying significantly saves energy. Heating occurs by contact. temperature inside chambers and pressure are adjusted automatically. The chamber is maintained under vacuum at 0.95 MPa. It ensures the flow of the heat-mass transfer process. Moisture is released from the wood in the form of steam. After drying, raw materials are obtained with a given level of moisture. In the process, it completely retains its structure - it does not collapse.

Such drying eliminates the use of fans. Humidification systems are also not needed. Neither dry nor wet thermometers are used in the chambers. Humidity sensors are installed inside. They are controlled from outside. The entire control system is usually located in a separate vestibule.

Vacuum plants are often used to process expensive raw materials: wenge, oak, rosewood, teak, anger. They use a convector type heating element. Maximum air in the chamber is heated up to +65 degrees. However, the process of evaporation of moisture begins already at 45.5 degrees. The process completely eliminates the effect of high temperatures. The wood is virtually indestructible.

Inside the tree, all the structural changes that accompany drying occur. First, moisture evaporates from the surface, then from the inside it rises again to the surface, and so on, up to 250 times over the entire time. Over the entire surface of the raw material, a moisture index difference of 0.5-1.5% is allowed. Here are some indicators at which vacuum drying works:

We build a dryer with our own hands

It is not always possible for an entrepreneur to buy expensive equipment and use vacuum technology. For starters, there are more simple methods.Do-it-yourself drying of wood also takes place in drying chambers. For its arrangement, you will need the room itself, a good heater and a fan.

The design of the do-it-yourself drying chamber assumes that one wall and the ceiling will be made of reinforced concrete. The remaining elements can be made from wood. The walls are insulated with foam, lined with clapboard and covered with foil. Penofol can be used as a reflective material. It also reflects heat well and helps keep it inside the camera.

Mobile drying chamber.

Next, the heating device is mounted. The most commonly used heating radiator. Its power should allow heating water to 65-90 degrees. The whole system is mounted separately from others heating circuits. It should work constantly, regardless of the time of year. Often use electric and gas appliances. The fan is necessary for uniform distribution of air in the chamber. Without this, it is impossible to dry the material with your own hands evenly.

It will also be necessary to build a system for loading lumber into the chamber. Usually they have big sizes and a lot of weight. It is convenient to load boards on trolleys moving along rails or with a forklift. Inside the chamber, the material is placed on shelves or simply on the floor. It is also necessary to install control devices over the process, which will be carried out with your own hands. Without this, it is impossible to properly dry the wood so that it later has marketable condition and its inherent properties.

When building a drying chamber with your own hands, you must adhere to the following rules:

When building a dryer with your own hands, the main thing is to achieve the maintenance inside of it of the parameters required by the technology. The materials and equipment that will be used in this case do not matter. It will take from one to two weeks to dry the wood in such a do-it-yourself chamber.

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

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

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

The cost of vacuum drying is quite controversial issue, and it is very difficult to give an exact answer to it. The price of such a process directly depends on many factors, ranging from the material to be processed and ending with the vacuum equipment in which this process will take place. Not less than important aspect also is the time for which you need to do the vacuum drying process. All this plays a certain role, because of which, the price of such a process can be completely different. All these aspects play a big role, which means that in any case they must be taken into account if you want to get a specific answer to what the result of vacuum drying will be.

Vacuum Drying Technology

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

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

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

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

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

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

Vacuum drying chambers

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

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

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

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

Vacuum freeze drying

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

The important point is that dehydration does not in any way affect Chemical properties products that will continue to be just as useful. In addition, vitamin activity remains in the same form, chemical composition and anatomical structure. Vacuum freeze drying consists of three key steps:

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

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

Vacuum drying of wood

IN previous sections we took this type of drying as an example. Ultimately, we came to the conclusion that given type processing is very effective, but also has a certain number of nuances, which are also worth paying attention to.

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

There is not a single woodworking enterprise that can do without the wood drying procedure. To prevent the occurrence various defects, it is customary to use a special technology for drying wood in a drying chamber. If you yourself want to engage in the production of wood products, you will also need a drying chamber for drying wood. Today we will talk about how to do it right.

The need to dry wood

How to dry a board efficiently and quickly? This question has been of interest to every carpenter since ancient times. Since ancient times, people have been storing forests for many years in order to have time to evenly dry it. The grandfather prepared a tree for his grandson, using the very material that his grandfather had left him.

The importance of properly dried wood is enormous! For example, if wooden furniture, which is in the room, is made of too wet wood that has just been cut down, then it will dry out over time, because the tree can dry out and shrink in size, which means it will deteriorate!

If the door to the house is made of overly dry wood, then it will swell over time, and will not be able to close! If a door panel is assembled from blanks that are unevenly dried in volume, then it can burst or warp it! Therefore, it is recommended to dry all wood blanks. In addition, drying protects the material from damage by a wood-destroying fungus, prevents the size and shape of wood, and improves the physical and mechanical properties of wood.

Drying wood is a long, complicated and expensive procedure. tree by traditional technologies heated with superheated steam or hot air. Dried wood can be transported and stored longer. In addition, during operation, it is not deformed. Drying of boards is carried out in steam chambers, where the possibility of internal damage is excluded.

The concept of wood moisture

For a complete perception of the essence of the drying process, it is worth plunging into theory a little. The procedure for removing moisture from wood is not entirely simple, because there are two types of moisture in the material itself. Wood consists of elongated plant cells. Moisture can be in the walls of cells and in their cavities, filling the microcapillary system. Moisture that is present in the spaces between cells and in their cavities is called free intercellular, and moisture in the cell walls is called bound intracellular.

The content of bound moisture in wood is limited. The state when the cell walls are characterized by maximum moisture in contact with liquid moisture is called their saturation limit. It is generally accepted that the moisture content of the saturation limit does not depend on the rock and averages 30%. If the moisture content of a tree is above 30%, then it contains free intercellular moisture. The wood of a freshly cut or growing tree has a moisture content greater than the saturation limit, that is, it is raw.

Depending on the purpose of the wood blanks, it is customary to dry the wood in different ways. The wood is dried to a moisture content of 6 - 8% when the material is needed for mechanical processing and assembly of products for high-precision critical joints that affect performance (ski, parquet or musical instruments).

Transport humidity is 18 - 22%. It is with this water content that lumber is suitable for transportation over long distances in warm weather. Wood dried to such a moisture content is mainly used in standard housing construction, in the production of ordinary containers and when there is no need for interchangeability during assembly.

Carpentry moisture is divided into several subspecies. Molded products ( terrace board, sheathing, floor board, cashing) must have a moisture content of 15 ± 2%. Wood products (windows, doors, stairs and interior elements), made of solid or glued wood, withstand humidity fluctuations from 8 to 15%.

Furniture humidity, depending on the level of the product and the use of solid or glued wood, is 8 ± 2%, because it is at this humidity that wood shows the most optimal characteristics for processing, gluing and subsequent operation. But it is usually customary to lower the humidity to 7-10%, performing a partial sterilization of the wood and taking into account the uniformity of moisture throughout the tree, preserving mechanical properties material, the absence of surface and internal cracks.

Wood drying modes

Depending on the requirements that apply to the quality of the tree, lumber can be dried different regimes that differ in temperature. In the mini wood drying chamber, during the drying process, the air temperature gradually increases in stages and the relative humidity of the agent decreases. Drying modes are selected taking into account the thickness of the lumber, the type of wood, the final moisture content, the quality category of the dried wood and the design of the chamber.

There are modes of low- and high-temperature process. The first modes involve the use of moist air as a drying agent, the temperature of which in the initial stage is less than 100 degrees. There are three categories of these modes:

The soft mode is able to provide defect-free drying of the material while maintaining the natural physical and mechanical properties of wood, including color and strength, which is important for drying wood to the transport moisture content of export sawn timber.
Normal mode guarantees a defect-free drying of wood with almost complete preservation of the strength of the material with slight color changes, which is suitable for drying sawn timber to the final moisture content.
The forced mode retains strength for static bending, compression and tension, but some reduction in splitting or chipping strength with wood darkening is possible, which is intended for drying wood to operational moisture.

According to low-temperature regimes, a three-stage change in the parameters of the drying agent is assumed, and from each stage to the next one, the transition can be carried out only after the material reaches a certain level of humidity, which is provided for by the regime.

High-temperature regimes provide for a two-stage change in the indicators of the drying agent, and it is possible to switch from the first stage to the second after the wood reaches a transitional moisture content of 20%. The high-temperature regime is determined depending on the thickness and type of lumber. High-temperature regimes can be used for drying wood, which is used for the manufacture of non-load-bearing elements of buildings and structures in which darkening of wood and a decrease in strength are allowed.

The concept of a drying chamber

Chamber drying is the main method of wood drying. Drying chambers are required for drying softwood and hardwood to different quality categories. One of the most popular and economical methods of artificial dehydration of lumber is drying, when bound and free moisture is removed from the tree by supplying heat to the damp tree with hot air and carrying away the evaporated excess moisture by humidified and partially cooled air.

The drying chamber is completely ready installation, which is equipped with all the equipment necessary for drying wood. According to the device, drying chambers for wood are divided into prefabricated metal and made of building materials. The latter are built directly in workshops or as separate buildings from materials that are widely used in industry. The chamber can be completely made of monolithic reinforced concrete. Its walls can be laid out of solid red brick, and the ceiling - from monolithic reinforced concrete.

If several dryers are used, they are often combined into a single unit, constructing a common control corridor, where the heat supply wiring and the automatic control system for all chambers are located. Depending on the volume of wood loaded into the chamber, there can be horizontal or vertical transverse air circulation.

Loading lumber into the chamber can be carried out in the following ways: on trolleys in the form of stacks along a rail track, like packages with a forklift. Heat transfer to wood can be carried out: by air, combustion products or superheated steam; radiant heat that comes from special emitters; solid if you organize contact with a heated surface; current that passes through wet wood; high frequency electromagnetic field that permeates wet wood.

Equipment for the drying chamber for wood is divided into basic and additional. The main ones include a fan system, a heat supply system, supply and exhaust ventilation and humidification, additionally include a door insulated and psychrometric unit, stacking carts, a fan drive electric motor.

The process of controlling the drying of wood in the chamber can be automated. Automation is able to maintain the humidity and temperature of the environment in the dryer at a given level. The temperature is regulated by the supply of coolant to the heaters or by switching on and off electric heater, and humidity - through the use of supply and exhaust ventilation and a humidification system.

The wood drying control system may have options remote control humidity and temperature in the chamber. When drying lumber in a drying chamber, it becomes necessary to control the moisture content of the wood, for which a remote moisture meter is used, which allows you to check the moisture content of the wood at several points without entering the chamber. With absence external sources heat supply for the dryer, autonomous heating modules can be used and gas, coal, wood waste, electricity and diesel fuel.

Types of drying chambers

IN real life It is customary to use the following types of drying chambers. The necessary energy in convective kilns is transported to the material by means of the air cycle, and the heat transfer to the wood occurs through convection. Convection chambers are of two types - tunnel and chamber.

Tunnel convection kilns are deep kilns where stack stacks are pushed from the wet end to the dry end. These chambers must be filled from one end and emptied from the other. The pushing of the stacks (the process of filling the chambers and emptying) is done one by one with an interval of 4 - 12 hours. These chambers are designed for large sawmills and allow only transport drying of wood.

Chamber convection kilns are shorter than tunnel kilns and vacuum kilns for wood, the same parameters are maintained throughout the kiln during operation. With a blowing depth of more than 2 meters, the method of reversing the direction of ventilation is used to equalize the conditions for drying wood. Emptying and filling the chamber occurs on the one hand, if it has one door. Other loading systems are known, which are similar to the procedure for loading tunnel chambers. Any lumber can be dried to any final moisture content, so 90% of wood in Europe and Russia is dried in chamber dryers.

The condensation drying chamber differs from the previous ones in that the moisture that occurs in the air condenses on special coolers and water comes out of the drying process. The efficiency of such a process is large, but the cycle is long, because the devices do not operate at high temperatures, and the total heat loss is also significant. The condensation chamber is mainly suitable for drying small volumes of wood, or for drying dense woods such as oak, beech or ash. The big advantage of such chambers is that there is no need for a boiler room, the price of a drying chamber for wood and the cost of drying is less.

Drying chambers are also classified according to the method of circulation and the nature of the drying agent used, the type of enclosure and the principle of operation. Drying chambers periodical action are characterized by the fact that they can be loaded completely for simultaneous drying of all material, and the mode of drying of wood changes in time, at the moment remaining the same for the entire chamber.

According to the circulation method, there are chambers with incentive and natural circulation. Dryers with natural circulation are outdated, inefficient, the drying mode in them is almost uncontrollable, the uniformity of wood drying is unsatisfactory. For modern construction such devices are not recommended, and the existing ones must be upgraded. According to the nature of the drying agent, gas, air and high-temperature chambers are distinguished, which operate in an environment of superheated steam.

wood drying process

Prior to drying according to the selected mode, the wood is heated with steam, which is supplied through the humidifying pipes, with the fans running, the heaters turned on and the exhaust ducts closed. First you need to calculate the drying chamber for wood. The temperature of the agent at the beginning of wood heating should be 5 degrees higher than the first stage of the regime, but not more than 100 degrees Celsius. The saturation level of the environment should be 0.98 - 1 for material with an initial moisture content of more than 25%, and 0.9 - 0.92 for wood with a moisture content of less than 25%.

The duration of the initial warm-up depends on the type of wood and for conifers (pine, spruce, fir and cedar) is 1 - 1.5 hours per centimeter of thickness. The duration of heating of soft hardwoods (aspen, birch, linden, poplar and alder) increases by 25%, and for hard hardwoods (maple, oak, ash, hornbeam, beech) - by 50% compared to the duration of heating of softwoods.

After preheating, it is customary to bring the parameters of the drying agent to the first stage of the regime. Then you can start drying the lumber, subject to the established regime. Humidity and temperature are regulated by valves on steam pipelines and dampers of sugar-exhaust channels.

During the operation of the infrared drying chamber for wood, residual stresses arise in the wood, which can be eliminated by intermediate and final moisture heat treatment in an environment of increased temperature and humidity. It is customary to process sawn timber, which is dried to operational humidity and subject to mechanical processing in the future.

Intermediate moisture heat treatment takes place during the transition from the second stage to the third or from the first to the second in high-temperature conditions. Moisture heat treatment is subjected to conifers from 60 mm thick and hardwood from 30 mm thick. The temperature of the medium in the process of heat and moisture treatment should be 8 degrees higher than the temperature of the second stage, but not higher than 100 degrees, at a saturation level of 0.95 - 0.97.

When the wood reaches the final average moisture content, the final moisture heat treatment can be carried out. In this process, the temperature of the medium is maintained at 8 degrees above the last stage, but not higher than 100 degrees. At the end of the final moisture heat treatment, the dried wood must be kept in the chambers for 2-3 hours at the parameters that are provided for by the last stage of the regime. Then the drying chamber is stopped.

Drying chamber manufacturing

If you decide to make wood products with your own hands, then you simply need a drying chamber for wood. However, during the construction of the dryer, comply with all required standards. You will need a camera, a fan, a heater and a heater.

Build a dryer or allocate a separate room, one wall and ceiling of which will be made of concrete, and the other walls will be made of wood that need to be insulated. To do this, it is customary to create several layers: the first of them is a foam plastic, the second is wooden boards, which are usually wrapped in foil in advance.

After that, you should install a heating element, which can be made in the form of batteries. Water must be supplied to the batteries from the stove, in which it will heat up to 60-95 degrees Celsius. It is desirable to continuously circulate water by means of water pumps in the heating element. Also, a fan should be placed in a home-made drying chamber for wood, which contributes to the distribution of warm air throughout the room.

Think about how the wood will be loaded into the drying chamber. One of the loading options can be a rail trolley. To regulate the humidity and temperature in the room of the drying chamber, you need to use working area corresponding thermometers - wet and dry. Provide shelves inside the dryer to increase the working space.

In the process of drying lumber, a sharp change in temperature in the working room is not allowed, otherwise this will cause the wood to warp or cracks appear in it. When building a drying chamber, it is extremely important to observe fire safety requirements. Therefore, it is mandatory to install fire extinguishers in the immediate vicinity of the dryer.

And finally, remember that instead of heating element at home, you can use an electric stove with two burners. You can insulate the walls of the drying chamber with your own hands using wood shavings. It can be used instead of foil in the chamber with penofol, which is able to provide good reflection from the heat surface. In such a dryer, the wood is dried in advance for 1-2 weeks.