Classification According to the performance and application of the product, carbonized wood can be divided into two categories: indoor use and outdoor use. In addition to the requirements for appearance quality, the former mainly requires dimensional stability. The tangential swelling and drying shrinkage of the wood is required to be 6-8%, and its corrosion resistance level is required to be grade Ⅲ—slight corrosion resistance; the latter, in addition to In addition to the requirements for appearance quality, the main performance requirement is biological corrosion resistance, and its corrosion resistance level is required to be level II—corrosion resistance. In addition, the chordwise swelling and drying shrinkage of wood are required to be 5-6%.

The industrial production of "carbonized wood" originated in Europe in the 1990s. Its typical production processes include: Thermal-wood, Retification, PLATO-process and oil-Treatment, etc. Carbonized wood production equipment at home and abroad can be divided into two categories: kiln type and tank type. Each has its own characteristics, but it has common requirements, and its process also has common characteristics.

When wood is carbonized, if the process or operation is improper, many defects will occur, mainly including cracking, deformation, uneven color, knot falling off, and even fire. However, if the causes of these defects are mastered, basically these defects can be prevented.

Wood drying rooms are generally classified according to the following main features.

The brick-concrete structure of the traditional drying room shell is low in cost and easy to build. However, there are some problems in the use of brick-concrete structure shells, such as poor corrosion resistance and cracking of the shell. In particular, the cracking of the shell not only increases the heat loss of the drying chamber, reduces the airtightness, and accelerates the destruction of the shell due to the intrusion of corrosive gases, but also seriously affects the normal use of the drying chamber. Therefore, precautions must be taken in the design and construction of the shell.

Fundamentals of Wood Drying Through the above introduction, we already know that the moisture in wood is mainly composed of two kinds of moisture, that is, free water and absorbed water. The moisture existing in the large capillary system composed of cell lumens is called free water, and its increase or decrease only affects the weight of wood, but not the properties of wood; the moisture existing in the microcapillary system composed of cell walls is called absorbed water. Its changes not only cause the wood to shrink and expand, but also affect other physical and mechanical properties of the wood.

The combined use of atmospheric drying and other drying methods can give full play to the advantages of low cost and simple operation of atmospheric drying, combined with the advantages of fast speed of other drying methods, and can achieve very satisfactory economic results. The two-stage drying that is often used in production is an example of combined drying. The so-called two-stage drying means that the sawn timber is dried to a moisture content of 20% in the first stage in the lumber mill; Process drying to the desired final moisture content.

The control of the wood drying process is a very important part of the drying process. It is directly related to the quality of the wood drying. Good control is the organic combination of the operator and the control equipment. Otherwise, no matter how advanced the control system is without the correct operation of the operator, it will be No practical effect.

The most important thing in the wood drying process is to make the parameters in the drying equipment as close as possible to the drying benchmark. The most important parameters in the wood drying benchmark are wood moisture content, air temperature and humidity.

The factors affecting the temperature and humidity stability of humid air are as follows. (1) Factors affecting the stability of humid air temperature control during the drying process. By controlling the steam in the heater to control the humidity of the humid air, the stability of temperature control mainly depends on whether the area of ​​the heater configured in the wood drying chamber matches the volume of the wood to be dried.