Microwave vacuum device for drying and charring lumber

Abstract

The invention relates to a wood microwave vacuum drying and charring device and a drying and charring method thereof. The device comprises one charring tank (box) with a tank door (3), a tank door opener (2) and a charring chamber (1), a vacuum system, and one or more microwave sources (6) generating the microwave, a heat-conducting oil furnace system and a material preparation and feed system. The drying and charring method comprises the following steps: A. rising the temperature inside the tank to 30-50 DEG C, and then to 80-130 DEG C at the rate of 2-8 DEG C / h; B. preserving the temperature for 2-100 hours; C. vacuumizing the tank for 4-100 hours; D. starting a hot recycle pump to control the oil furnace temperature, the oil flow rate and the pressure inside the tank for 4-100 hours: E. turning off the microwave source and a heat source, opening an intake and exhaust valve (39) to discharge the pressure inside the tank to 0 and lower the temperature to 70-130 DEG C, and then closing the intake and exhaust valve (39); and F. starting a vacuum pump (22) to lower the temperature inside of the tank by air circulation and removing the wood from the tank when the temperature decreases to 30-70 DEG C. The device and the method help char the wood evenly, shorten the production cycle by 60% compared with the conventional method, and lower the energy consumption by 70%, thus greatly reducing the production cost.

Description

technical field [0001] The invention belongs to the field of wood drying and carbonization, and in particular relates to a wood microwave vacuum drying and carbonization device and a drying and carbonization method. Background technique [0002] Due to the different types of wood, the fibers are different, and the density and strength are also different. After drying, problems such as shrinkage, warping, moth-eaten, and rot often appear as the environment changes. Over the years, people have been conducting research on improving the properties of wood such as dimensional stability, moth resistance, corrosion resistance, and heat resistance, and great progress has been made. Especially in recent years, carbonized wood products are favored for their high dimensional stability, no shrinkage, no rot, no insects, non-toxic, and durable. However, there are still many problems to be solved in carbonized wood production equipment and production methods. [0003] Chinese patent 200...

AI Technical Summary

Problems solved by technology

[0007] In this method, it can be seen that: first, the temperature inside the wood is difficult to be consistent with the temperature of the medium air in the kiln, which will lead to poor overall carbonization uniformity of the wood, and the phenomenon of "burnt on the outside and tender on the inside"

Second, different degrees of carbonization will appear in the corners of the kiln, inside and outside the wood stack, and at the air outlet of the fan. The temperature at the position where the wind speed is too high is too high, resulting in surface cracking, and the temperature at the position where the wind speed is too low is too low to achieve carbonization.

Third, when the moisture content drops to 0 during the wood carbonization process, steaming and humidification will cause the carbonized wood to burst and increase wood loss

Fourth, it is only suitable for materials with a water content of ≤12%

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