Drying chamber for lumber air. Overview of drying chambers for wood, which manufacturer to choose? Possible design options

Content:

All woodworking enterprises make a profit from the sale of manufactured products. And the deeper the wood processing, the more profitable the production. Before buying equipment, each entrepreneur asks questions: What are the drying chambers for wood, what devices are equipped with, and which one to choose for your production?

If you choose the wrong equipment, then the profitability, on the contrary, will fall. And the greater range of wood drying kilns on the market makes the selection task even more difficult.

The main types of drying chambers are:

1. Dielectric.
2. Convector
3. vacuum
4. Aerodynamic

The method of drying wood in various ways was invented back in the 60s, but due to the high costs of electricity and the complexity of the design, technologies have only recently begun to be used. Most often all over the world use convector-type dryers. Why is this happening? Other designs can be used with a number of restrictions and subtleties of use. The main disadvantages of using inductive, condensing and vacuum wood dryers are:

1. Aerodynamic chambers require more electricity;
2. Condensation structures are expensive, and drying in them lasts 2 times longer than in convector ones.
3. Vacuum dryers are expensive and also expensive to maintain.
4. Dielectric ones require high energy costs, although they are considered one of the best.

Convector dryers

Convectors are used for drying wood of various species and sizes. Due to the simplicity of the design, convector chambers are inexpensive to maintain, which indicates reliability. Therefore, in order to increase profitability, in 90 cases out of a hundred they are purchased.

Working principle of convector dryer

Heating occurs from a gaseous carrier (drying agent). When heated, the raw material is tapped. The drying agent can be steam, flue gas, air. The moisture released from the wood serves as an additional moistening of the agent, the excess is drawn into the atmosphere with the help of ventilation.

The exchange of air in a convector dryer is not higher than 2% of the total, so the energy efficiency is noticeable.

Complete set and equipment of the convector dryer

There are many configurations from various manufacturers, but there are basic options:

1. Equipment for an already built or under construction hangar of a drying structure.
2. Fully design with hardware.

Equipment case

The body is completely made of metal, assembled on a monolithic-pillar foundation. The metal used for manufacturing is carbon steel or aluminum with an anti-corrosion coating. Outside and inside the hangar is lined with aluminum sheets. Separate elements inside the structure (deflectors, false flows, amplifiers, etc.) are also made of aluminum. The chamber is insulated with mineral wool in the form of plates.

The structure is assembled in compliance with GOSTs and SNiPa. Options requiring additions and extensions are made according to an additionally developed scheme. The basic assembly is designed for an average snow load.

Convection chamber models

Convection drying chambers are produced by domestic and foreign companies. The most common are Helios: ASKM-7, ASKM-10, ASKM-15, ASKM-25. They are used for drying any type of wood of drying categories I, II, III and 0. According to reviews, these models work quickly, since German fans are used in the mechanism. And installation and maintenance of ASKM models is simple. The price is from 700,000 rubles, depending on the size and power.

Vacuum drying chambers

Designs are designed specifically for expensive raw materials (teak, wenge, rosewood, oak, anger, etc.). Vacuum dryers can also be used for any softwood or hardwood.

Working principle of vacuum dryer

The vacuum dryer works from convector heating of wood and vacuum removal of excess moisture. Temperature regime maximum +65 0С. But because of the vacuum, 0.09 MPa boils at 45.5 0C. This allows the drying process to be carried out without the aggressive effects of high temperatures, which does not create high internal stress, and the tree does not crack.

In the process of operation, the temperature rises by 65 0С, the automation is activated and the electric boiler is turned off. The upper part of the wood begins to cool, and moisture from the inside begins to flow to the drier parts. For the entire drying process, such processes can occur up to 250 times. So the moisture is evenly drawn out along the entire length and depth of the raw material. The maximum moisture difference in different parts of the tree can be 0.5-1.5%, and completely dried has a moisture content of 4-6%.

Models of popular vacuum designs

The most common model of vacuum chambers is Helios. Drying chambers for wood Helios differ in power, load volume and other technical specifications. More about TX Helios in the table:

Technical parameters, Helios Vacuum (GV)	GV-4	GV-6	GV-9	GV-12	GV-16
Possible volume of loaded raw materials, no more, m 3	4	6	9	12	16
Parameters of the working mechanism (length, width, height), cm: LSHV	430/192/192	630/192/192	650/230/230	850/230/230	1230/230/230
The maximum possible heating temperature, degrees. FROM	up to 65	up to 65	up to 65	up to 65	up to 65
Discharge kg/cm2	— 0,92	— 0,92	— 0,92	— 0,92	— 0,92
Drying time of various types and sections of wood to a moisture content of 4-5%, days:
Oak, section 5.2 cm, damp. fifty%	19 — 25	19 — 25	19 — 25	19 — 25	19 — 25
Oak, section 5.2 cm, humidity 30%	11 — 13	11 — 13	11 — 13	11 — 13	11 — 13
Oak, Section 2.5 cm, humidity 50%	10-11	10-11	10-11	10-11	10-11
Oak, section 2.5 cm, humidity 30%	8-9	8-9	8-9	8-9	8-9
Coniferous, section 5.5 cm, humidity 50%	7-8	7-8	7-8	7-8	7-8
Coniferous, section 5.5 cm, humidity 30%	6-5	6-5	6-5	6-5	6-5
Required mains voltage, V	380	380	380	380	380
Connected power, kW	15	18	30	36	72
Average used power, kW	8	10	17	20	35
Helios drying chamber size (length, width, height), m: LSHV	6,12,22,4	8,12,22,4	8,32,352,4	10,323,524,0	13,323,524,0
Weight, t	4	6,5	7,7	9,5	17,5

Aerodynamic chambers for wood drying

These drying chambers are reminiscent of a metal box finished with a professional aluminum deck. An aerodynamic chamber of various modifications is used for drying all types of wood, with a load of 3-25 m3. On request, you can purchase chambers of individual design with a load of up to 43 m3.

The aerodynamic chamber is good because the work is fully automated and a minimum number of workers is needed.

The frame of the aerodynamic chamber consists of a solid metal sewn onto a supporting frame. The chamber is made in the form of a quadrangular box, into which it is convenient to load wood by car or by rail. ways. The entire internal structure is equipped with automatic condensate collectors.

Principle of operation

Drying is carried out under the influence of aerodynamic energy. Heated air circulates in the chamber under the influence of a specially designed aerodynamic fan. The air in the chamber, due to compression, increases the temperature on the centrifugal fan, specifically on its blades. Thus, aerodynamic losses are converted into thermal energy.

Heat is forced into the chamber, depending on the design, in reverse or dead-end. The work of the aerodynamic chamber is started by one button “start” and opens only after the cycle is completed.

Models of aerodynamic dryers

The most common dryers of the aerodynamic type Gelos SKV-25F, SKV-50F, SKV-12TA, SKV-25TA, SKV-50TA, as well as Italian EPL 65.57.41, EPL 65.72.41, EPL 65.87.41, EPL 125.72.41, EPL 125.87.41. Developed by Helios, specifically for drying coniferous material. They cost from 1,500,000 rubles.

Dryers with microwave chamber

Microwave cameras have been invented quite recently. Such a dryer resembles a closed metal container. Operates under the influence of the reflective surface of microwave waves. Reminds me of how a microwave oven works. Using a microwave chamber, you can dry the material of any section and size. Microwave chambers have a simple design and you can adjust the wavelength to any length. This made it possible to dry any raw material using a microwave chamber. The attenuation mode of the microwave wave allows you to adjust the temperature inside the chamber. And reversible fans remove excess moisture from the system. Microwave drying is compared with dielectric drying, which is considered the most efficient, but is not used in Russia due to high electricity costs.

The main disadvantages of microwave chambers include wood moisture control and the high price of microwave dryers and electricity costs.

Models of microwave dryers

In Russia, this drying technology is offered by the engineering company in Moscow "Investstroy" - "SVCh-Les". Such an installation costs from 1,300,000 rubles. It is necessary to service the microwave forest once every half a year, at a price of 100,000 rubles.

Only half of the future profit depends on which camera the buyer chooses. Building and insulating a box is only part of all the work. It is important that the component equipment is of high quality.

Equipment for drying chambers

Equipment for dryers can be divided into types:

1. Thermal system.
2. Exhaust and humidification system.
3. Rail structure for loading and unloading

Ventilation equipment performs the role of uniform distribution of heated air. Installing a low-quality fan entails uneven drying of raw materials. According to GOST, the air movement inside the chamber should be optimally about 3 m / s. This can be achieved using high-quality and powerful fans. All fans have a rotary or axial connection system.

This equipment depends on the capacity and model of the drying chamber. The heat generator can be an electric heater or a heat exchanger. They are installed only by specialists, and they are used to pump and transfer thermal energy to wood. A system, such as a mini-boiler house for liquid, gaseous or solid fuel, can also act as a heat generator. It is convenient when work is carried out on waste wood production.

The electra heater has a design consisting of a pipe and a chrome spiral wound around it. This generator has a small advantage: a simplified process for controlling the temperature inside the chamber.

Humidification system

To ensure constant uniform air humidity in dryers, humidification and exhaust equipment is used. Humidification is carried out by a complex system of nozzles, pipelines, and a solenoid valve.

The hood is carried out using a fan (usually rotary). The equipment works according to the following technology: when the humidity drops, the fan automatically turns off and the hood does not function. At the same time, the humidification of the air takes place by offsetting the evaporation of the liquid, which enters the nozzle automatically when the valve is opened.

When the humidity rises, on the contrary, the valve closes and the fan turns on.

Rail loading and unloading system

This equipment is installed at the stage of camera assembly. The system is made of rails, which are installed thoroughly. On top of them, stacked carts are attached, which are needed for storing wood. Raw materials are laid on them, and placed in a chamber, after drying, the carts are rolled out into the street and packaged.

When choosing a chamber for drying wood, it is better to use the services of professionals, but do not neglect the information of specialists on the network.

There is not a single woodworking enterprise that can do without the wood drying procedure. To prevent the occurrence of 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 the wooden furniture that is in the room is made from too wet wood that has just been sawn down, then it will dry out over time, because the tree can shrink 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. According to traditional technologies, wood is 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 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 moisture 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%, making partial sterilization of wood and taking into account the uniformity of moisture throughout the tree, the preservation of the mechanical properties of the material, the absence of surface and internal cracks.

Wood drying modes

Depending on the requirements that apply to the quality of wood, lumber can be dried in different modes, which differ in temperature level. 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 lumber 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 transition can be carried out only after the material reaches certain level 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.

Drying chamber is a completely finished 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 system are located. automatic control all cameras. 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; a solid body, if contact is made with a heated surface; current that passes through wet wood; high-frequency electromagnetic field that penetrates wet wood.

Equipment for the drying chamber for wood is divided into basic and additional. The main system includes a fan system, a heat supply system, supply and exhaust ventilation and humidification, and an additional one includes a door insulated and psychrometric unit, stacking carts, and an electric fan drive 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 supplying the coolant to the heaters or by turning the electric heater on and off, and the humidity is controlled by using the supply and exhaust ventilation and humidification system.

The wood drying control system may provide for remote control of 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 can use independent heating modules and use 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 of periodic action are characterized by the fact that they can be loaded completely for simultaneous drying of all material, and the drying mode of wood varies in time, in this 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 humidifying pipes, with fans running, heaters turned on and 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. Coniferous species with a thickness of 60 millimeters or more and hardwoods with a thickness of 30 millimeters or more are subjected to moisture heat treatment. 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, it is necessary to use the appropriate thermometers in the working area - 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 comply with fire safety requirements. Therefore, in the immediate vicinity of the dryer in without fail install fire extinguishers.

And finally, remember that instead of a heating element at home, you can use a two-burner electric stove. 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.

On the domestic market a very wide choice of chambers for forced drying of wood, operating on various technologies, such as Russian production, and imported.

This puts the customer in front of a difficult choice problem.

In this article, I will talk about what I had to face in three decades of work related to various drying chambers. Perhaps the information provided here will help someone not to make a mistake in this matter.

Don't Underestimate the Importance of Drying

My experience of working in several companies involved in the drying of various woods, allows me to speak about the importance of this technological stage in the chain of production of finished sawn timber.

This is explained by the fact that it is a well-organized drying process that allows minimizing the number of defects, improving the quality of the final product and, accordingly, ensuring its sale at higher prices, and also contributes to an increase in the number of regular customers.

The approach to financing forced drying technology according to the residual principle is categorically wrong. The result of such a decision may be low profitability (up to bankruptcy) of a timber processing enterprise equipped with the most modern machine park.

And if this is superimposed on the manager’s erroneous ideas about how to dry the forest “correctly” and the priority of “saving” funds on the purchase of equipment, the result will be disastrous. The camera will. But you won’t wait for high-quality dry lumber at the exit.

I had to work under various bosses (owners). And it must be recognized that the personality of the leader plays a colossal role in right decision this issue.

One seeks by any means to "grab the ruble" here and now, without thinking about tomorrow at all. The other purposefully invests in the development and equipment of production, being content with minimal profits and, ultimately, gets a highly profitable company that occupies a stable position in the market for the provision of such services, demonstrating positive development dynamics even in the off-season and with a decline in consumer demand.

Buy or make your own

In order to get a quality product, you should use a high-quality tool, one of which is a drying chamber.

However, a number of novice wood processors tend, in order to save money, to make a drying chamber on their own.

I assume that this is possible. But only if there are specialists who are able to correctly and fully carry out preliminary calculations (and such, at woodworking enterprises, can be found infrequently). And when it is required to periodically dry small volumes of wood.

In all other cases, such decisions lead to unjustified financial losses, a significant amount of marriage and the loss of regular customers.

Industrial production of significant volumes requires the use of cameras made by professionals. Self-activity in this matter is tantamount to suicide.

To confirm this thesis, I want to cite a case that I witnessed in 2002-2003 (I don’t remember exactly). Then I just got a job in a company that is still called "sharashka" before and today. It positioned itself as a diversified enterprise producing garden furniture, gazebos, fences and lumber.

Hearing that the material of chamber drying can be sold more expensive, the owner appointed three "intelligent men" as developers and manufacturers of the convection-type chamber.

The "masterpiece" of design thought was sculpted in less than a month. And with huge amount flaws and gross violations, which were visible even with the naked eye (I already had some work experience then). I tried to bring this to the employer's attention. But the opinion of the "smerd" was not taken into account, but to insist, creating problems for himself out of the blue. I didn't.

Examples. There was no possibility of reverse rotation on the fans, many metal structural elements were “forgotten” to be grounded, the heaters were of different power. And a young Tajik was appointed responsible for the operation, who did not have the slightest idea about this. He also dealt with the issues of loading and unloading.

The creation worked for a little more than a week and ingloriously ended its short production biography with a powerful fire, which burned not only the property of our owner, but also the raw materials supplied by him, which he had to dry.

But that didn't teach him anything. This citizen continued to build his business on the principle: “There are only two points of view on the question, mine and the wrong one.” After working for a while, I thought it best to change jobs.

At the end of the section, a few wishes for those who decide to make a drying chamber on their own.

Before proceeding with the manufacture of a structure in a material, it is required to obtain at least minimal theoretical knowledge. Fortunately, today the Internet provides a huge opportunity for this. There are many very good teaching aids on this topic. Among them, I would like to mention the books of Krechetov and Tsarev (co-authored with Peich). It will not be superfluous to familiarize yourself with the provisions current regulations. For example, SP114.13330.2016, which sets fire safety standards for the storage of timber.

When creating a project for your own dryer, it is imperative to calculate:

• optimal material for its walls;
• achieve tight closing of the gate;
• determine the optimal method of loading materials for drying;
• choose the type and power of fans, calculate their installation locations and the required number;
• resolve the issue with the coolant and the implementation of the humidification system;
• be sure to install a psychrometer and humidity sensors in the chamber.

Ideally, there should be automation. As a last resort. Semi-automatic control of the drying process. But these are quite complex issues that require deep special knowledge.

Practice has shown that one of the most common mistakes committed by manufacturers of homemade drying devices, is the ingress of water, when it is dripping, onto the humidity sensor. as a result, automation receives distorted commands. The result is marriage.

The second, in terms of frequency of occurrence, is the fact of "forgetting" that the fans are powered by electric drives, which constantly have to be in conditions of high temperature and humidity. therefore, taking any suitable in power will not work here. Only special models are required.

Pros and cons of different types of drying kilns for wood

Small companies mainly use Russian-made cameras. In addition, Czech and Italian are quite often used, less often Finnish (mainly in the north-west of the European part of Russia). This preference is explained by the following factors:

• the optimal ratio of performance, performance, durability and cost;
• the ability to quickly purchase spare parts and the availability of after-sales service (the vast majority of dryer manufacturers have a wide network of representative offices in the CIS countries, including Russia);
• minimum delivery times, relatively low customs and delivery costs, the possibility of installation supervision and staff training.

Regardless of the principle implemented in the design, which is the basis of the drying technology (convective, condensing, vacuum, etc.), any design solves the same problem - it evaporates the moisture contained in it from the wood. That is why, when considering the quality of forced drying, first of all, they pay attention to such indicators as:

• drying time to a specified moisture content;
• the occurrence of internal stresses during the drying process and the possibility of its relief;
• the difference in humidity between the outer and inner layers of lumber after the drying process is completed.

I would like to say a few words about the specific drying technologies that I had to deal with.

1. Convection kilns for wood

Cameras of this type are most common in Russia, and in all regions. Therefore, the experience with such chambers forms the basis of my experience with the maintenance of products for the forced reduction of the percentage of moisture in lumber.

The technology underlying this drying principle is very simple. Moisture. Contained in the tree, it is removed from it by blowing it with a jet of hot air. The latter is heated by electric heaters (in the vast majority of models). The flow of the required strength and direction is formed by blocks of powerful fans, the number of which can reach ten or more units.

An important advantage of cameras of this type is the design envisaged possibility steaming wood. This allows you to minimize internal stresses (ideally, completely zero them).

For all cameras with which I had to work, the parameters internal environment, created inside, were measured by the installed psychrometer, and the built-in automation controlled the drying process.

The process is divided into several stages, at each of which the moisture content of the material and the magnitude of internal stresses are different.

The upper layers of lumber, when blown with hot air, dry faster than the inner ones. And the layers near the core part do not have time to give up moisture with the same intensity. The result of this imbalance is internal stresses that can induce cracks.

To compensate for this negative process, almost all convective chambers have an additional stage of moisture treatment, when moisture is sprayed onto the surface of the material undergoing drying. Further, the drying process by supplying hot air continues again.

If the alternation of these stages takes place in a timely manner, after processing is completed, a material is obtained that has approximately the same moisture content throughout the volume.

However, this is in theory. But in practice, a lot depends on who made the camera, its model and the notorious "human factor".

If the product is purchased from a reliable manufacturer, the installation is carried out in the presence of a company representative, and the operation is carried out strictly according to the manufacturer's recommendations, then in such devices it is possible to obtain finished lumber with negligible internal stresses, which eliminates its cracking, increases the yield finished products and as a result, the profit of the company.

To the advantages of the considered types of cameras, I would attributed:

• availability of models with a significant one-time capacity (about 1000 m 3), which is essential for large companies;
• availability of performance fine tuning control process, which involves changing the values ​​of essential parameters at any of the drying stages;
• process control in automatic or semi-automatic modes;
• minimization of production costs.

Among the shortcomings I can not but mention:

• sufficiently long drying time;
• the need to train trained personnel to service the device.

1. Condensation kilns for wood

The main difference between this technology and the one discussed above lies in the following technical features. Moisture from the wood undergoing drying, released into the air of the chamber, condenses on the special coolers available in the design, is collected in special drainage channels and removed from the chamber, and the air dried in this way continues the closed wood blowing cycle.

Coolers are charged with freon. Operating temperatures in these dryers are ≤ 45 °C. This significantly increases the drying time of one bookmark, even in comparison with convection chambers. Depending on the selected model of the device, it may or may not have a humidification option.

If available, wetting is carried out after the completion of the first stage of drying, which minimizes the internal stress that has arisen in the upper layers of lumber.

In models where humidification is not provided, this issue is solved by the presence of inverters on the fan motors, which allow you to change the speed of the supplied air flow (This is done in order to ensure a smoother and more uniform release of moisture from the wood). In other cases, it will not be possible to exclude cracking of products undergoing drying.

Chambers of this type are the best choice if it is necessary to dry mainly thick lumber, or products made from dense wood (for example, ash or oak).

If it is planned to dry the wood for subsequent use in carpentry, such a solution can hardly be called the best.

The advantages of the method include:

• low power consumption;
• almost 100% elimination of cases of warping of lumber.

There are quite a few shortcomings. Main:

• very long drying times, which are several times higher than those of convection-type chambers;
• the appearance of additional costs due to the use of freon;
• the quality of finished materials cannot be called ideal;
• wood treated in this way has low resistance to pathogenic microflora (low temperatures in the chamber do not allow blanks to be sterilized).

1. Aerodynamic kilns for wood

Twice I had to work on similar cameras. They have the simplest design compared to other types of products. This is an ordinary metal box with fans installed in it.

Air heating is carried out due to the heat generated by the operating fans (the mechanical energy of the rotating rotor is transformed into thermal energy).

When the required humidity is reached in the chamber, the fans stop. This is the easiest DIY solution. However, this drying technology has many disadvantages. Therefore, I would not recommend purchasing such cameras.

The main disadvantage is that fact. That blowing hot air dries the wood unevenly. While the upper layers are already almost dry, the inner ones still have a fairly high degree of moisture. The result of this imbalance is a significant internal stress in the finished products.

The use of such lumber in carpentry is categorically not recommended. When you try to "dry out" such material, it is guaranteed to burst (crack).

Of course, one can refer to the fact that the problems of the occurrence of internal stresses are inherent in any drying technology. But in the considered version, they are the most significant and expressed as clearly as possible.

There are advantages to be found in any method.

The advantages of aerodynamic drying can be considered:

• ease of installation and low cost of operation (it is enough to connect the unit to a 3-phase 380V network);
• drying is carried out with considerable intensity;
• the cost of such drying chambers can be considered low (compared to other types of products), if costs are not considered. Which entails subsequent operation.

The cons are:

• unsatisfactory drying quality;
• long drying time;
• very significant cost of electricity.

1. Infrared kilns for wood

The main difference of the drying technology under consideration is the absence of the requirement to create a closed volume room (the actual chamber). To remove moisture, special designs called infrared cassettes are used. When laying a stack for drying, they are placed between the layers of stacked wood. The infrared radiation created by them evaporates moisture from the tree to its entire depth.

In summer, drying in this way can be carried out under sheds in the open air, having previously protected the stack from direct rain.

I had to work with such devices privately, in my own workshop. I really like to test new technologies of wood drying and processing available to me.

The results obtained, in general, can be called satisfactory. But the technology didn't look good. And for industrial use, this solution is absolutely unacceptable, due to the duration and complexity. preparatory phase bookmarks and subsequent sampling of finished lumber.

Benefits include:

• autonomy and compactness of technology;
• ease of bringing into working condition;
• high economy.

As disadvantages, attention should be paid on the:

• significant difficulties in organizing control over drying parameters;
• the possibility of using on bookmarks with limited volumes, not exceeding 5 m 3.

1. microwave ovens for wood

The wood in them is dried due to the implementation of a process similar to what is happening in a household microwave oven. The difference is only in the size of the products.

High-frequency radiation does not damage the wood, contributing to the delicate and uniform removal of moisture over almost the entire depth of the workpiece. The terms for reaching a given degree of moisture content of the finished lumber are quite short.

For the sake of curiosity, I worked with friends on a similar installation (new knowledge is never superfluous). The results are good enough. However, the complexity of the device, the rather high cost, the high cost of components (the price of the same magnetrons starts from 300,000 rubles, and the service life, unfortunately, is not long) and, most importantly, small volumes of a single load make such a solution unprofitable either for large-scale production or for private traders.

The latter is especially relevant if you consider how much the maintenance of such cameras costs, especially if you have to replace a broken magnetron generator.

But, as they say, "the taste and color ...". The choice is yours.

The advantages of such installations are:

• high drying speed and excellent quality of the output material;
• economical use of electricity.

Of the shortcomings, I would, first of all, name:

• an insignificant one-time loading capacity not exceeding -7-10 cubic meters;
• very complex control behind the course of the process;
• high cost of magnetron generators.

I fell in love with these cameras. The structures are completely sealed (in the vast majority of models). During the drying process, a pressure below atmospheric pressure is created inside them. Therefore, drying can be carried out at relatively low temperatures (up to 65 °C).

This is explained by the fact that a decrease in pressure leads to boiling water at lower temperatures. Therefore, the desired drying effect can be achieved with "little blood" without using high temperatures.

This automatically reduces the heat loss in this type of chamber and allows for very little color change in the material being dried.

The design features of such products depend on who they are made by. For example, Italian WDE Maspell dryers and some domestic chambers, quite often used by Russian timber processors, have water heaters. Other domestic manufacturers prefer electric heating elements.

Home distinctive feature drying using vacuum technology is a curious situation when the temperature to which the board is heated, passing drying, exceeds the boiling point of water vapor (other name, saturation temperature). As a result, all processes taking place inside the board are significantly accelerated, and the latter dries faster.

This technology makes it possible not to use the aggressive effect of high temperatures on the material during the drying process.

But, praising this or that technology, I urge future users not to forget that the minimum number of defective blanks after drying is completed is determined not only by the chosen technology and type of drying chamber, but also by correctly selected technological modes that are laid down by manufacturers in each model and properly functioning automation.

In addition to this, an important factor is the choice of a conscientious manufacturer with the necessary technological developments and drying experience. The technology is complex and, unfortunately, I have not once encountered when the owner chose the manufacturer after superficially sorting out the issue. As a result, I received equipment with which more torment than work. The claimed characteristics did not correspond to reality. I had to either modify the camera myself and spend time and money on it, or dare to work on this equipment.

Despite the fact that in such chambers the impact on the wood is more gentle, there is a possibility of cracking of the material being dried. It is always there and in any drying mode. Since wood is a living material, in which various types of stresses can form simultaneously. These processes are influenced by the type of wood and the place of its harvesting, the technology of cutting logs and the age of the tree.

Well, in terms of drying, I can say that the pine board "fifty" in the chamber vacuum type(at the last workplace) from 50 to 8 percent we dry in just 2 days. I have not seen such a speed in any technology, perhaps only in microwave.

Advantages of vacuum chambers:

• excellent quality of dried materials;
• record fast speed drying;
• high performance;
• suitable for both small enterprises (models from 1-8 cubic meters), medium-sized enterprises (models from 8-18 cubic meters), large enterprises(models from 18-36 cu.)

Disadvantages (unfortunately, she also has them):

• manual loading and unloading;

The importance of reliable automation in drying chambers

I want to talk about this separately. Drying wood is a very complex process. Therefore, manufacturers automate high-quality modern cameras to the maximum. But no machine and automation can completely replace a person.

Therefore, an operator is needed in any case. And better, a competent operator. Since a mistake made at any stage of drying can turn into an irreparable marriage at the exit, or lead to an emergency.

As a rule, marriage is manifested in final stage once it's impossible to fix anything.

Therefore, it is required to approach the choice of the purchased camera, as well as the training of personnel, thoroughly.

Automation allows you to get rid of a significant number of problems, so I consider this component in the design of the drying chamber to be very important. Especially if drying is planned to be carried out on an industrial scale.

When choosing a camera, be sure to pay attention to the following:

• is it possible to organize automatic control, which provides for setting various drying modes and the possibility of loading new templates (user programs that you create for your production);
• whether it is possible for the operator to intervene in the operation of automation, which allows you to quickly adjust the drying process at any time;
• it is highly desirable to have a digital display on the automation, on which the main characteristics of the process (humidity, temperature, etc.) are displayed in real time;
• whether manufacturers provide for the possibility of recording the course of the chamber drying process with fixing all the parameters and then displaying it in the form of a graph (this allows for subsequent analysis, if necessary);
• built-in automation should be "smart", that is, exclude the possibility of making "wrong" decisions. For example, do not give a humidification command when the ventilation shutters are open;
• whether it is possible to control the camera remotely;
• the presence of light and sound indication and malfunctions.

When the automation is set and works correctly, an environment is formed and maintained in the chamber that is optimal for a particular drying stage.

AT right time, taking into account the readings of control devices, humidity, temperature, and the level of air conditioning in the internal volume of the chamber should change. All this will positively affect the quality of the finished product.

When choosing automation, the main thing is not to overdo it. Do not make "butter oil". Automation installation required. But only when certain conditions. On cameras, for example, of a convective type, with a volume of less than 20 cubic meters of a single load, its installation is economically unprofitable, since it will pay off for a very long time. On such cameras, the best solution is to use semi-automatic devices.

14 Points to Consider When Buying a Dryer

It is possible to distinguish a good camera from a bad one, in each specific situation, not only by its type, but also by who it was made by. Without naming any brands here, I will focus on the main issues of choosing this product using the example of a vacuum chamber. There are not many of them:

• heating elements must be structurally calculated and have an optimal design for heat transfer to wood;
• also the heating plates must be made of steel stainless grades or aluminum, which has a higher resistance to corrosion;
• registers connecting elements must be coated with anti-corrosion compounds;
• the gates in the chamber and its enclosing surfaces must ensure maximum tightness of the internal volume. Contact with the air of the external environment and atmospheric moisture must be guaranteed excluded;
• the existing heat and vapor barrier must be of high quality and installed correctly;
• removal of steam from the chamber should be carried out as efficiently as possible;
• work from a solid fuel or gas boiler.

Otherwise, an increase in heat loss and, automatically, electricity consumption is inevitable. And, most importantly, the drying technology is violated. And the most intelligent automation will not be able to cope with violations caused by the presence of such defects. As a result, an increase in the volume of marriage and a decrease in profits.

• The installed automated control system should make it possible to reduce the operator's participation in the process to a minimum, and the existing SDUK should make the drying process easier and more predictable;
• The whole drying process must be displayed on a PC in the form of graphs for analysis in case of a malfunction;
• There should be online monitoring 24/7 by the manufacturer.

Ideal, in my opinion, the camera must necessarily meet the following fundamental criteria:

• ensure maximum high quality finished products (dried lumber);
• require insignificant expenses for its construction, equipment and commissioning;
• have a low cost of drying one cubic meter of wood (in terms of);
• the entire drying process should not adversely affect the environment;

Important: long service life (the case and components must be designed and made from high-quality materials), in the case of vacuum chambers this is especially important, more than once I have seen how the chamber rusted after 2 years under the influence of aggressive media inside and the case began to “siphon”, each I had to weld it for a month and make metal patches. After 5 years, such a building looked like a colander. In the Rostov region, there was a case when, after 3 years, in the process of creating a vacuum, the chamber “collapsed like a tin can” under the influence of corrosion. The camera amplification ribs failed. The manufacturer simply incorrectly made the calculations.;

The surest decision for a person who decides to purchase a drying chamber is a preliminary stage of thorough preparation, during which:

• needs to be determined annual volume drying (today and in the future);
• study the issue of the presence and quantity of wood waste in production, and the possibility of their use in order to heat the coolant for the chamber (installation of an autonomous solid fuel boiler);
• analyze the possibility of atmospheric (open) drying;
• to develop a layout of chambers, places of storage of raw materials and finished products.

Remember. Far from everything depends on the equipment, even the most high-quality and expensive. Not less than half of the success is the merit of the operators and repairmen serving the camera (their qualifications directly affect the result). For example, how they organize the storage of raw materials and finished lumber.

Lumber rejects due to incorrect drying conditions

Some leaders. Due to lack of awareness. Drying processes are considered quite simple and do not deserve special attention. He put down the board, turned on the airflow and heating for a certain time, took out the finished product.

In this case, I want to cite the wise thought of my grandson: “The taste and color ... all felt-tip pens are different.” If it were that simple, then the problem with choosing a camera would not exist in principle.

In fact, for "incomprehensible" reasons, there is almost no marriage in one cell, and in the second, its percentage goes off scale beyond the permissible limit. To understand why this happens, sometimes it takes a considerable amount of time (and the marriage goes on). And anything can affect the quality, from design defects to improper loading.

The main task that you have to solve when choosing a camera is not only and not so much saving money on the purchase and choosing the optimal cost / performance ratio, and even the possible prospects for its operation. The main thing is to understand whether the drying room is able to bring the moisture in the lumber to the required levels in short term throughout the depth of the wood evenly, whether it is able to stabilize the geometry (in size and shape).

Any wooden product made from poorly dried material will fail very quickly. Moreover, hidden defects become noticeable only after a certain time. About what they were. You will recognize by warping and cracking, peeling paint and other "charms".

It is considered on average. That a cubic meter of freshly harvested wood contains about 300 liters of liquid, which the chamber should evaporate. But in such a way as not to damage the material. Most of this volume is in the capillaries, a smaller part, in the cells of the wood tissue, which these capillaries form. Removing moisture at the cellular level is the most difficult task. It is the violation of technology at this stage that leads to cracking of lumber.

Hard rocks (oak, ash, beech) are the most difficult to dry. Their top layer dries much faster and forms a crust that does not allow moisture to pass through from the inner layers. As a result, the probability of marriage is high.

That is why it is extremely important to comply with the standard technological modes of drying (for example, timely leveling of humidity). This process is very complicated. Even the same board dries unevenly in length and volume with a spread of up to 2%.

If the stack is not properly stacked, buckling can be added to the cracks.

What are the most common problems faced by modern drying chambers?

For my long enough practice on various industries, had to deal with various nuances of operation.

Problems can arise when working with any camera. Even produced famous brand and quite expensive. Most often, these are leaks in various pipes due to corrosion, downtime caused by a malfunction and lack of necessary spare parts (for imported cameras, this problem is very relevant) or waiting for a specialist. Quite often there are problems with fans.

But the main problem, in my opinion, is the uniform heating of the stacked stack to the full depth and the effective extraction of moisture:

• Wood is heated in different chambers of different manufacturers by different agents (water, air, radiation waves, etc.), heating structures of various types, as a result, lumber dries in different ways.
• The intake of moisture evaporated in the wood should occur as efficiently as possible at the right time.

These 2 problems had to be solved more often than others, since it is inherent in almost all types of cameras (to varying degrees).

The reasons can be listed long enough. But most of the time it's:

• under-dried material at the end of the stack and over-dried at its beginning, or at the top of the stack and in the middle.
• the drying agent between the rows of the stack can practically not penetrate or differ significantly in temperature, which reduces the process to the level of natural drying in terms of time and quality.

To solve the problem, in the first case, the installation of fans with reverse rotation often helps. You can "play" with their placement and total number to determine the optimal solution. But this cannot be called a panacea. The desired result is not always achieved.

In vacuum chambers, everything is much more complicated; the design of the heating elements and the moisture removal system will have to be redone. Only a professionally performed calculation and competent design (camera alteration) can help. This is in my experience a lot of time and money wasted.

The main thing to understand is

Completely solve ALL problems of drying uniformity and quality finished products so far NOBODY succeeded!

And, in the foreseeable future, a solution to this problem is not expected. Therefore, the main goal, which every manufacturer strives to achieve, is to minimize the percentage of rejects and to bring the parameters as close as possible to ideal ones.

In the case of convection chambers, make sure that the fans inside are not remote. They have a long shaft, which breaks much more often. These products are less efficient and require more thorough and frequent maintenance.

Moisture protection of fan motors must be of class "H" (at internal temperatures in the chamber ≤ 130 ° C) or "F" (at temperatures below 85 degrees).

It is obligatory to have a reverse with an efficiency of about 90%.

TOTAL

At the close of my story, I decided to violate the obligation not to name specific models and manufacturers. With a clear conscience, I can recommend FALCON vacuum chambers (practically any models) to small and medium-sized and even large manufacturers. With these Russian products, there were the least problems.

According to performance characteristics. In terms of performance and durability, they are comparable to models of international giants in this market segment. Unlike them, they have a whole set of additional advantages:

Related articles:

The drying chamber is the most important equipment at woodworking enterprises, as it allows you to remove moisture from lumber, heat-treat wood to prevent biological destruction, give resistance to decay, maintain mechanical strength at the lowest density, create minimal thermal and electrical conductivity in wood.

What are drying chambers and complexes?

Drying kilns are industrial equipment used for drying various types of lumber and wood species, hardwood or softwood, for pallet fumigation. To process large volumes of wood, modular chambers are combined to create large-sized drying complexes.

Types of drying chambers and drying modes

LLC "MAKIL PLUS" offers drying chambers for sawn timber, with boilers (heating units) burning (utilizing) wood waste, which are divided into two types, depending on the heat carrier used:

1. Heat carrier - water. These installations consist of a boiler and water heaters, circulation pumps, automation adapted for use in cold weather (anti-freeze system), water treatment system. The system copes well with water softening, and the boiler power is selected based on the volume of drying chambers and additional consumers. Based on the foregoing, a drying complex for drying water-type lumber has a large initial cost of the project, as it includes many expensive elements and requires specialized installation.
2. Heat carrier - air. The system includes a 100-500 kW air heater, a centrifugal fan and an air duct system. The initial cost of this equipment is included in the cost of the camera, the customer receives a turnkey solution without additional capital investment. The universal air heater has a higher efficiency than a water boiler and is capable of delivering both minimum and higher temperatures than a water-type wood dryer.

For processing wood in drying complexes, three main modes can be used: soft, medium and forced. While maintaining a soft mode with a temperature of up to 55 ° C, during the drying process, the wood retains all its properties, without changing its strength and color. When using the medium (normal) mode with temperatures up to 67-70°C, the shade of the wood changes slightly. For high temperatures up to 85-90°C in forced mode, fast drying is typical, but with darkening of the wood.

Technologies used by the company in the manufacture of cameras

The main advantage of drying chambers for the forest is:

1. Autonomous mode of operation of the system in the absence of heating networks
2. Minimum fuel costs with simultaneous disposal of waste
3. Compactness of placement of the main and auxiliary equipment
4. The possibility of dismantling the equipment and moving it to the prepared foundation
5. High degree of thermal insulation of the chamber as a whole, tightness and insulation of sliding gates
6. Fast heating up to the required temperature
7. Minimum heat loss through structures
8. Drying agent and heat carrier both air and water.
9. Possibility of fast re-equipment under the heat carrier.
10. Ease of maintenance, ease of management.
11. Possibility of drying at any modes.
12. Drying complexes are made of 80% of Russian materials that do not require a long wait for replacement.
13. The modular design allows new drying chambers to be added without stopping the existing chambers.
14. Thermally protected reversible axial fans with Siemens motors/
15. Litouch drying process control system from world leader Logika concern
16. The ability to program the controller up to 16 phases of lumber drying, which allows you to create special climatic conditions inside the chamber for the drying process.
17. High maintainability during operation

These technologies not only make it possible to dry lumber without discoloration and cracking, but also ensure trouble-free operation of the equipment.

Economic payback of chambers on wood waste

Economic payback is one of the benefits of MAKIL PLUS equipment. The drying complex for wood, on average, pays off within a year, since the cost of drying 1 cubic meter, including the cost of servicing the device, is about 450 rubles. In addition, purchasing a plant that is completely ready for operation solves the problem of wood waste disposal. At the same time, mixed waste, even with a high percentage of moisture, is suitable for work.

The company "MAKIL PLUS" puts on sale drying equipment with chambers from 10 to 140 m 3, which are manufactured according to finished projects as well as individual customer requirements. MAKIL PLUS wood drying complexes are already operating in every region of Russia and are becoming more in demand every day.

More detailed information on this equipment and its purchase can be obtained by contacting the managers of our company.

The lumber kiln is an industrial equipment that is used to dry raw timber for further processing. Today, wood drying in drying chambers is carried out by several types of such devices, each of which has its own specific characteristics. functional features. However, in fact, they are all universal. With their help, you can dry any kind of timber. With the help of the latest drying chambers, even the most exotic and expensive varieties of wood, such as rosewood, beech, wenge or teak, are dried with high quality. There is no cracking or other flaws.

Types of drying chambers

A large number of woodworking industries process almost 10,000 m³ of lumber every year. The wood drying kiln is a decisive link in the process chain for quality assurance. The volume of a single load of timber in the drying chamber is very different. Sometimes you need to dry 6 m³, and there are needs up to 100 m³. The main factor during the selection of the size of the drying chamber can be called the production capacity.

Drying methods are classified according to the features of heat transfer to the dried raw material, therefore, the following types of chambers are distinguished:

• dielectric - need high energy costs
• convector
• vacuum. These devices are expensive and expensive to maintain.
• aerodynamic. Such devices need a lot of energy.

Chamber drying of wood by various methods was invented in the 60s of the last century, however, due to high energy costs and the complexity of the design, drying has become popular only in the last decade. Convector-type chambers are the most popular all over the world.

Convector dryers

The convector type wood drying chamber is used for various types of timber. Such devices have a simple design, they are inexpensive to maintain and reliable. That is why they are the most popular in production.

The work is carried out by heating from a gaseous carrier (drying agent). When heated, the material dries out. The drying agent can be steam, flue gas or air. The moisture that is released from the timber serves to additionally moisten the agent, and the excess is sucked out with the help of ventilation.

The air exchange rate in the convector dryer does not exceed 2% of the total amount, therefore, energy savings are felt.

The body of the chamber is metal, placed on a monolithic-columnar foundation. The metal that is used for the body is carbon steel or aluminum with an anti-corrosion coating. On both sides, the body is sheathed with sheets of aluminum. The chamber is insulated with mineral wool in the form of plates. You can buy a convector chamber of both domestic and foreign production.

vacuum drying

Vacuum drying chamber for wood is designed for high-value timber such as teak, wenge, rosewood and others. Such a unit functions from convector heating of wood and vacuum removal of excess moisture. The process takes place at a maximum temperature of +65. However, due to the vacuum pressure of 0.09 MPa, boiling occurs at 45.5. Such conditions make it possible to dry the wood without the aggressive effects of high temperatures. Thus, there is no high internal stress, and the wood is not subject to cracking.

During drying, when the temperature rises to 65 degrees, the automation turns on and the electric boiler turns off. The top layers of timber slowly cool down, and moisture from the inside goes to drier areas. During the period of one drying, about 250 such cycles occur. Under such conditions, moisture is evenly drawn out along the length and depth of the material. After drying, the material is characterized by a moisture level in the range of 4-6%.

Aerodynamic drying

Chamber drying of sawn timber under aerodynamic conditions has become widespread due to the rather low price, uncomplicated design. In addition, specific knowledge is not required to work on such a device. service personnel. Profitability is achieved when drying up to 2000 m³ per year of coniferous timber.

Among the shortcomings can be identified:

• high level of energy intensity of the drying process. In order to dry freshly sawn wood, 1.15-1.3 kWh is needed to evaporate 1 liter of moisture. Electricity, approx. 240-290kWh/m³
• there is no way to regulate the temperature. There is only the possibility to slow down the rate of its increase by changing the cross section of the centrifugal fan
• there is no way to organize technological drying according to the schedule of the "Guiding technical materials on the technology of chamber drying of wood".

Such a chamber is a quadrangular box. It is convenient to load wood into it by car or by rail. Drying occurs under the action of aerodynamic energy. Warm air moves in the chamber under the action of a special aerodynamic fan. Due to the compression of air in the chamber, the temperature on the centrifugal fan, namely on its blades, increases. Consequently, aerodynamic losses become thermal energy. Heat can be driven into the chamber in reverse or dead-end, it all depends on the design features. The opening of the chamber occurs only at the end of the drying cycle.

Drying in a microwave chamber

Such devices have been invented recently. They look like a closed metal container. The work is carried out under the action of the reflective surface of microwave waves. The principle of operation is similar to the operation of a conventional microwave. With the help of a microwave chamber, raw materials of any section and dimensions are dried. Microwave chambers are distinguished by a simple design, the settings allow you to select any wavelength.
Therefore, you can dry a wide variety of timber. The attenuation mode of microwave waves guarantees the regulation of the temperature inside the chamber. With the help of reversible fans, excess moisture is removed from the system. Microwave drying is compared with dielectric drying, which is considered the most efficient, but is not used in Russia due to high electricity costs.