Wood is one of the main raw materials for the construction industry. China has a long history in the use of wood and has achieved certain results. The research and development of wood drying equipment has also gone through decades. While the drying equipment production industry has achieved certain results, there are also many problems. At any time, the introduction of Pengzhou microwave wood drying equipment technology has solved many problems for wood processing enterprises. It also achieves the goal of saving energy, high efficiency, and rapidly improving economic benefits. Based on years of technical experience and feedback from old customers, we summarize the following advantages of microwave drying equipment and share with you!
1) Fast speed: Microwave drying is extremely fast due to its unique advantages. According to the actual situation of customers using Pengzhou microwave equipment to dry wood, the results show that when the microwave power is about 60 kilowatts, from 8 mm thick thin wood board to 50 mm thick square material without causing drying defects. The moisture content is dried from 35 to 40% to about 20%, and the drying time is only 10 minutes to 26 minutes. If the microwave power is increased, a corresponding reasonable process must be adopted. Otherwise, although the drying speed is accelerated, the internal temperature of the wood rises sharply, the water vaporizes, and the air pressure increases sharply, exceeding the allowable extent of the wood fiber, causing cracking. Therefore, microwave drying of wood has a limited increase in output power density.
2) High efficiency: We use the "water-lifting rate" indicator to assess drying efficiency. The so-called "water-lifting rate" is defined as the kilowatt-hour of microwave power in 1 hour, and the kilograms per kilowatt-hour (kg/kwh). The high water extraction rate indicates that the equipment is highly efficient. We conducted tests on the materials of the four types of tree species under the same conditions. The results showed that the water extraction rate of all kinds of tree species was about 1kg/kwh or slightly exceeded. When the same type of wood has different thickness specifications, the water extraction rate is also approximately equal to 1 kg/kwh. The length of the same kind of wood along the fiber direction is different, the drying effect has obvious difference. We compare the eucalyptus with relatively tight fiber structure, the short water-lifting rate is high, and the water-lifting rate is low. It is well known that the heated wood undergoes a further cooling process as the gradual cooling process progresses. Therefore, proper drying after drying can improve the drying effect.
3) Good quality: The shape and crack of the wood during the conventional drying process are caused by the uneven fiber shrinkage after the wood loses water. In natural drying, on the one hand, since the evaporation speed of the surface of the wood is much larger than the diffusion degree of the internal moisture, the surface is wet inside the surface, and the drying of the surface causes the fiber to shrink, resulting in stress between the surface and the inside. On the one hand, the fiber pores of the wood at both ends in the fiber direction are much larger than other parts, so the shrinkage of the fiber greatly exceeds the rest, so in fact, the two ends of the wood are almost free from cracking and deformation in the natural drying, and the length of the crack is generally In the range of 10 to 30 cm, a severe crack or a few pieces of broken boards. At the same time, the wood is pushed on the drying field, and it is repeatedly eroded and deteriorated by the long-time wind, sun and rain, causing many wood molds. This deformation, cracking, mildew and deterioration have seriously affected the quality of the wood and caused a lot of scrapping. The drying is even and thorough, the product quality is improved, and the utilization rate of wood can be increased by about 5%. Such as the surface will not be knotted, improve the toughness, will not crack, deformation, discoloration, correction of bending, etc.;
4. When the microwave power density is too large, the internal pressure of the wood vaporization exceeds the allowable limit of the wood fiber, and the internal cracking of the wood may also occur. This is the principle that microwave drying of wood still requires a certain amount of time.
a) Saving wood: Wood is a kind of material in the country. Saving wood not only has economic benefits, but also can reduce forest harvesting and has significant environmental benefits. In natural drying, wood scrapping due to deformation, cracking, and mildew deterioration is quite serious. It has been proved that the microwave utilization can increase the utilization rate of wood by at least 5%, which accelerates the period of wood use: it takes a long time for the wood to dry naturally. In a year or even a few years, in order to maintain normal production, it is necessary to store a large amount of wood for turnover, not only occupying a large space but also frequently turning over the sun. After drying by microwave, the wet wood is dried in time, and the above phenomenon can be appropriately improved.
b) Killing wood mites: Most of the wood mites are hidden in the wood. When they become adult worms, they will destroy the appearance and use value of the Furniture. During the microwave process, the internal eggs and larvae are also killed. . According to the test, under the action of microwave energy of 2450MHz, if the temperature of the wood is 70-80 degrees, it takes only 3 minutes to completely kill the eggs and larvae.
In the microwave drying process, the situation is completely different. Because microwave drying has the advantages of strong permeability and selectivity, during the drying process, the shrinkage between the ends of the board and the ends and the intermediate fibers are basically the same, so Cracking and deformation are small. After actual investigation, it is agreed that the quality of the wood dried by the microwave drying equipment is better than that of the conventional equipment.
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