Board dryer: creating and using a drying chamber. Homemade wood dryer Press vacuum drying chamber with your own hands

Process vacuum drying 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 in 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 costs electricity.

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 similar devices The 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 conformity European standards. In such devices you can dry simultaneously various varieties wood

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. Except Styrofoam will do mineral wool and any other insulation material. In order for heat to be reflected from the surface, it is necessary to lay 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, apply to lumber special mixture, which is made from chalk and drying oil. Most often, this mixture is applied to the end parts of the workpieces.

High-quality dried lumber has always been the key to quality, durability and reliability of any structure in which wood occupies a significant share. But it is difficult to obtain it under natural conditions without it spoiling. Drying time under normal atmospheric conditions can range from 6 to 12 months, depending on temperature and humidity environment. During natural heat treatment, the material is subject to unwanted deformation, warping and cracking.

To improve the quality of drying lumber, many equipment options have been invented; people often 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 yourself. Still, there are craftsmen who make them from old tank bodies or thickened sheet steel. These are mainly mini cameras with a loading volume of 5-10 cubic meters.

What is vacuum drying of wood with your own hands?

Vacuum drying of wood with your own hands is quite possible if you have a shell from a rocket, tank, or any other similar type of product from which you can make a shell for the equipment.

Main design elements:

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

You will need a pump to pump out air and create a vacuum. You can heat lumber using any known method, which can be the contact method, air-gas or water steam.

A do-it-yourself vacuum chamber is quite technically complicated, because it will be quite difficult to find many parts for its manufacture. And ordering them specifically is tantamount to ordering the camera itself. Therefore, before you start constructing vacuum drying chambers for wood with your own hands, you should consider whether it is advisable or whether it would be better to order it from a specialized company.

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

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

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

Wood processing occurs 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. If the conditions are incorrect, thermal drying takes place only on the surface of the wood, and the lumber may not acquire the desired properties:

full color change
fire resistance
increased resistance to rotting

Make a homemade chamber for thermowood, just like thermowood itself, at home difficult task. It is unlikely that you will be able to find competent specialists ready to share their experience on forums, videos, or somewhere on the Internet. If you have any questions, you can contact the manufacturers.

Vacuum dryers for wood: do it yourself or from professionals?

Our company has been producing high-quality and highly efficient vacuum-type drying chambers for several years, so we are ready to offer a truly reliable and practical option.

But if you need a vacuum dryer for small-sized wood for heat treatment of small parts and want to make it yourself, then you need a drawing. Drawings on this topic are quite a rare occurrence; of those that occur, it is unlikely that a camera capable of working in production conditions will be produced.

If you are still going to purchase ready-made equipment, then the most effective option are chambers with contact technology for heating lumber along the entire length, the percentage of defects is less than 1, and the drying time is up to 6-8% humidity pine boards 30mm thick will only take about 60 hours.

Wood drying methods

Exist different kinds drying wood, each of which has its own characteristics. Some of the types are obsolete and are currently practically not used.

The natural method of drying wood is the longest, and at the same time does not require financial costs. With this drying method, the bark is not removed from the tree; air access is ensured by cutting holes across the trunk. Drying using the natural method should be done in a dry, well-ventilated room, otherwise the wood inside will remain damp, which will subsequently lead to warping. Depending on the moisture content of the wood, it sometimes takes 2-3 years to dry naturally, which makes this method completely unnecessary in modern realities.
Paraffinization is also a type of drying that has been used for a long time. Wooden blanks in this case, they must be immersed in paraffin heated to 40 ° C. After several hours, the wood is removed and dried for 1-2 days. After this procedure, the wood acquires a pronounced texture pattern and an original tinted shade, and is not subject to cracking, warping or rotting.
Evaporation - here, in addition to wood, water and sawdust are needed. The workpiece is placed in water heated to 70 ° C and covered with sawdust so that the material is thoroughly steamed. Another known drying method is steaming in linseed oil. Here the technology is slightly different: the workpiece is placed in a special container, poured linseed oil and steamed required quantity time. This method was often used in past times - dishes made from steamed wood did not crack or deform for a very long time.
The process of drying wood in a specialized drying chamber takes place at a temperature of 40 to 90 °C, in some cases the temperature in the dryer reaches 115 °C. A dryer is a stationary structure equipped with a fan, a device that directs air currents and controls the humidity in the container. The heat source in such a chamber is steam, hot water or electricity.

At the moment, we are considering with you how to create a vacuum drying chamber, which allows you to make the wood drying process not only economical, but also significantly reduce it in time.

Drying wood at home

Drying wood at home, as noted earlier, can be done with a special conveyor. You will also need a fan, insulation and a heating device. To retain heat, your chamber must be insulated; for this, foam plastic or mineral wool can be used. You will also need to lay a special material to reflect heat - for this purpose, as a rule, foil or penofol is used.

The heating element can be installed in the form of a battery, into which water will be supplied from the stove, heated to 60-95 ° C. The system for loading wood into the chamber also deserves special attention. Rail carts or a forklift can be used for this. You will definitely need to monitor the drying process - for this you need to install specialized sensors.

When answering the question of how to dry boards at home, it is definitely worth mentioning that when building your own drying chamber, you must adhere to all fire safety rules. If you do everything correctly, you will be able to receive quality wood, having a good presentation.

Video of drying wood at home

The construction industry today is experiencing an active stage of technological development, which is reflected in the tools used, the methodology for performing repair and installation operations, and, of course, the materials. At the same time, due to availability and low cost, traditional materials, including wood, still remain in demand. Another thing is to use it in pure form is impossible, since even solid rocks no longer meet construction standards in protective properties. This barrier can be overcome by special preparation operations, including drying wood in drying chambers - a technology that improves a whole range of technical and physical characteristics of the material.

Chamber drying technology

The principle of drying in vacuum chambers is based on the laws of evaporation and water circulation. That is, the main objectives of the method come down to ensuring optimally rapid removal of moisture from the wood structure, but without negative consequences For performance qualities. The technology under consideration is aimed at performing this process. In practice, it is carried out using special installations that ensure water circulation through the wood structure in the direction from the core to the outer part. Next, water is removed from the surface through evaporation. But it is important to understand that getting rid of moisture is not the only task that drying wood in drying chambers accomplishes. The technology also allows you to eliminate physical defects, but for this it is used optional equipment like presses. As for the technical implementation of the process, it is usually performed by manually loading the material into the appropriate chamber. Then, due to the heating plates, the unit automatically warms up against the background of intense evaporation.

Features of the vacuum drying method

Compared to traditional drying chambers, new cylindrical vacuum drying technologies allow for a high process speed. This is connected not so much with the principle of influence on the material, but with the mechanics of loading and the location of the workpieces relative to the functional plates. But the thermal effect also has its own characteristics. Because the wood material is compressed between the plates under pressure, ensuring a high intensity of impact on the structure - accordingly, a larger amount of moisture is evaporated. In terms of energy consumption, vacuum drying of wood also has its differences. Features of the technology in this parameter are determined by increasing the temperature of the plates and optimizing the physical movement of the material inside the chamber. Therefore, to achieve the same alternative ways drying results, such chambers consume less energy.

Drying stages

Automated cameras allow you to implement standard set technological stages, which looks like this:

Warming up the material. Primary heat treatment, during which the wood structure is prepared for subsequent stages.
Direct drying. At this stage, a combined moistening-drying operation is performed, which allows the material to be softened as much as possible for further drying.
Cooling. In essence, this is the stage of crystallization of the structure, thanks to which the wood, which has become pliable due to heat treatment, regains its optimal characteristics hardness

As noted above, all stages of the drying process are controlled automatically, and the operator monitors the safety indicators. But even before the event starts, the user is required to install optimal mode drying. In particular, it sets pressure and temperature based on the characteristics of the material. For example, for coniferous blanks with a thickness of 2.5 cm, a pressure of 500 kg/m2 is required. Concerning temperature regime, then he's in in this case can be 80 °C.

Drying chamber device

Modern cameras are made in the form of a parallelepiped or cylinder. The output side of the structure is equipped with a lid, through which material loading/unloading operations are carried out. Moreover, the structure of the lid includes a rubber sheet fixed on a metal frame - this solution allows you to create an almost perfect vacuum with increased sealing. Each layer of lumber is lined with heating plates, which are usually made of thermally conductive aluminum alloys. To carry out movements, the plates are equipped with roller mechanisms. The movement of the heaters ensures balanced drying of the wood in the drying chambers. The chamber manufacturing technology also provides for the connection of circuits with circulating water. Boilers with liquid are located separately and provide their own heating. To maintain a stable vacuum, a special pump is placed inside the chamber.

Application of hydraulic press

It has already been said above that during the drying stages, the structure of the wood softens and becomes pliable. This condition is a side effect and redundant within the drying process. Actually, to eliminate these consequences, the final cooling stage is provided. However, the softened structure of the material can be exposed to hydraulic press, which will relieve the workpiece from physical defects - at least ensure its straightening. Such presses are included in the general complex of capacities at which wood is dried in drying chambers. The pressing technology, in turn, eliminates possible defects that were acquired by the material in the chamber. The final workpiece will be “correctly” deformed with the parameters needed for working lumber.

Drying methods

At the moment of technology development, there are three main methods of vacuum drying. The first two methods have already been discussed - direct drying and press-vacuum preparation of the material. But there is also a method of steam treatment in a vacuum chamber. Its relevance is due to the possibility of eliminating heating plates from the design of the chamber, since hot steam covers the entire space, without requiring a special direction of flows to separate areas blanks This approach provides many advantages that steam heating methods of wood drying provide. Drying chambers, for example, allow loading not only labor-intensive manually, but also with the help of forklifts.

What effect does drying provide?

Drying itself, as a process of optimizing the hygroscopic properties, gives the wood relatively high strength indicators. This is already enough for the material to meet the basic requirements of building regulations. But large woodworking plants use the above-described technologies and methods of drying wood only as preparatory stage for further processing of the material. In particular, for impregnations, which will additionally give the workpieces the qualities of fire resistance, moisture resistance, frost resistance, etc.

Do-it-yourself drying

To make your own dryer using affordable means, you will first need a separate room. In size it can correspond to a small utility room or utility room. It is advisable to make the structure from brick or concrete, and insulate and insulate the internal surfaces with layers of foam plastic coated with foil. The result will be, although not a vacuum, a sealed dryer for boards. How to make thermal elements? To do this, several convectors or radiators should be provided - their number will be determined by the structural capabilities of the room and the requirements for the drying itself. Heating equipment will provide the evaporation effect. For greater efficiency, you can add the function thermal effects fans.

Conclusion

During construction and renovation operations, the question of choosing between different materials. Limited financial resources often exclude metal alloys and high-strength plastics, leaving wood as the only option. But this decision also justifies itself in many cases. technical specifications, if a lumber drying chamber is used. You won’t be able to make such a chamber yourself without spending money on expensive radiators, but in the long run, its use will be worth the investment. As the practice of operating structures based on properly dried wood shows, the material can even harsh conditions serve for years without losing its primary properties. Another thing is that a lot will depend on the type of wood that is planned to be used for such purposes.

A vacuum dryer is another modern invention that allows you to dry wood quickly and efficiently. But its scope of application is not as wide as that of an infrared dryer. Let's take a closer look at the properties of both devices.

One of the properties of wood is hygroscopicity, the ability to absorb moisture. A freshly felled tree is saturated with moisture, and raw wood is unsuitable for making furniture and creating building structures. It is highly susceptible to biological damage, warping and cracking.

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

Different dryers differ from each other in their operating principle and performance characteristics. You can select the optimal equipment for specific operating conditions by comparing them. In this article we will focus on infrared and vacuum dryers, we will understand how they work, how much lumber they can dry and in what time, how much energy they consume, and what their market price is.

Principle of operation

IR dryers They produce infrared rays, which, by heating the wood, dry it to the required moisture level. These rays are of the same nature as visible light. They pass through the air unhindered. Nitrogen and oxygen molecules do not absorb infrared radiation, so all the energy is directed to heating the wood, not the air.

This drying method does not involve the use of a coolant, which eliminates the need to monitor its performance and equip the equipment with complex automation.

Infrared heat acts gently on wood, without leading to strong internal stresses and warping.

Vacuum dryers The market offers two main types: with cyclic and contact heating of the material. The operating principle of the former is based on convective heating of wood and vacuum removal of excess moisture. The operating temperature usually does not exceed 65°C, but a pressure of 0.09 MPa causes moisture to boil already at 45.5°C. Vacuum allows you to dry lumber without impact high temperatures, due to which the wood does not crack. During drying, when the temperature reaches 65°C, the boiler automatically turns off. The surface of the wood begins to cool, and moisture from inside flows to drier areas. During the entire drying period, shutdown and restart occur many times, while the moisture is drawn out evenly.

In contact heated dryers, heat is transferred to the material through thermoactive plates that are stacked. The plates are heated either by water or electricity.

Appearance

Infrared dryer is a set of thin thermoactive cassettes that are placed in a stack of lumber in a certain sequence and connected to a power source. A stack prepared for drying is covered with a material with a reflective layer so that condensation drains outside the stack. The drying process is controlled by a thermostat responsible for maintaining the set temperature. The equipment is compact and convenient to use; if necessary, it can be easily transported from place to place in the trunk of a car

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

In dryers with contact heating, boards are laid inside the chamber in layers, alternating with heating plates. When used as a heating agent hot water, its circulation in the plates is ensured water pump. The water is heated by a boiler, and the vacuum is created by a liquid vacuum pump.

Material is loaded into large-volume cylindrical chambers along a rail track, which is mounted inside and outside.

Size and weight

Convenience infrared dryers are their small dimensions and weight. One thermoactive cassette has a size of 1230x650x1.5 mm, that is, it is a thin plate small area. The weight of the cassette is 5.7 kg. A standard set for drying 1 m³ of lumber includes 12 cassettes with a total weight of 69 kg. With the sheathing, control panel and cabling, the weight of the equipment does not exceed 130 kg. Its transportation does not require the use of special equipment.

Vacuum a press dryer, even with a small loading volume, has a significantly larger size and weight. Thus, a parallelepiped-shaped unit with a loading volume of 4 m³ has dimensions of 4800x1700x2005 mm and weighs 2300 kg without aluminum plates. The size of the heating plate is 4000×1400 mm. To transport such equipment you will need a rail or road container.

Autonomy

IR dryer works completely offline. By installing and connecting the equipment correctly, you will not have to perform additional monitoring of operating parameters. You only need to set the drying mode based on the quality source material, and in the future the thermostat will monitor the maintenance of the set temperature.

Drying process in vacuum chamber is also automated, but in this case more complex automation is used, since it is necessary to monitor the parameters of the coolant (if any) and pressure. In some types of dryers, the process can be carried out manually. Most models have an indication emergency condition, which is activated when the temperature is exceeded, the degree of vacuum decreases, the parameters of the coolant change, etc.

Drying time

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

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

Load volume

IR cassettes can be used for drying any amount of lumber.

Vacuum chambers are offered with different loading volumes: from 4 to 20 m³.

Power supply

Infrared cassettes They are connected through the control panel to a 220 V network; a voltage of 380 V is also suitable.

Vacuum chambers require connection to a 380 V power supply.

Power and electricity consumption

Maximum power infrared dryer- 3.3 kW/m³. During drying 1 m³ of lumber, from 200 to 400 kWh of electricity is consumed.

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

Price

Price is a significant argument when purchasing equipment.

Prices IR dryers FlexiHIT is very affordable:

set for drying 1 m³ of three-meter boards - RUB 59,288;
set for drying 1 m³ of four-meter boards - RUB 69,329;
set for drying 1 m³ of six-meter boards - RUB 70,007.

Prices vacuum chambers domestic production range from 500 thousand to 1.5 million rubles, imported equipment costs 3-4 times more expensive.

conclusions

IR dryers They are easy to use, can be used in production and at home, are suitable for drying any volume of lumber and have an affordable price.

In vacuum chambers the wood dries quickly and evenly, does not deform and even levels out, its color remains unchanged. But in view high cost and high energy consumption, it is advisable to use them mainly for drying expensive types of wood.