RU2537649C1 - Method of timber drying - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to woodworking industry and may be used for timber drying. Timber drying consists in alternation of cycles. Said cycles comprises processing of wood in the chamber by heat carrier, heating and degassing with the help of receiver connected thereto. Note here that temperature in the chamber is increased to 60-80°C. Vacuum is created in receiver to equalise the pressure in chamber and receiver to 0.8 MPa. Pressure in chamber and receiver equalised, connection between said receiver and chamber is broken. Moisture condensed in receiver is drained therefrom. Then, dry air heated to 60-80°C is fed into the chamber. Chamber pressure stabilised, cycle is reiterated to target moisture content.

EFFECT: higher intensity of drying.

1 dwg, 1 tbl

Description

The invention relates to the woodworking industry and can be used for drying lumber from wood of various species.

A known method of drying wood by repeatedly alternating cycles, including purging the wood with a coolant with heating it to an average volume temperature of 80-100 ° C, pulse high-speed evacuation using a receiver, high-speed valves and pipelines, followed by exposure to vacuum, characterized in that the wood is purged with atmospheric pressure, and pulsed evacuation is carried out for up to 10 times with free moisture pressed from wood without phase transition of liquid water into steam with exposure to vacuum with the mind to a steady-state temperature of the wood, then vacuum is released to atmospheric pressure by supplying an air coolant, and wood is purged and vacuum is carried out by an air coolant with a temperature of 150-300 ° C, and at the beginning and at the end of the drying process, one or more drying cycles using steam with a temperature of 100-115 ° C at an overpressure of not higher than 0.07 MPa as a heat carrier (RF patent No. 2400684 publ. September 27, 2010)

The closest technical solution chosen by the applicant as a prototype is a method of drying wood by repeatedly alternating cycles, purging the wood with a coolant to vent the vapors released, heating the wood to an average volume temperature of 80-100 ° C, high-speed evacuation using a receiver, high-speed valves and pipelines with heating the wood in a drying chamber isolated from the atmosphere, and the wood is kept in the chamber to a pressure equal to the equilibrium pressure of the steam in free one volume of the drying chamber at a given temperature, characterized in that each heating cycle of wood after high-speed evacuation is carried out with the simultaneous injection of water with a temperature of 90-100 ° C or steam to a pressure equal to the equilibrium pressure of the steam in the free volume of the drying chamber at a given temperature (Patent for the invention of the Russian Federation No. 2304747, publ. July 20, 2008).

The disadvantage of this method is the low speed and intensity of drying wood.

An object of the invention is to increase the intensity of drying wood.

The technical problem is achieved by drying wood by alternating cycles, including processing in a wood chamber with a coolant and its heating and subsequent evacuation using a receiver connected to the chamber, characterized in that the wood is heated to a temperature of 60-80 ° C, a vacuum is created in the receiver and then leveled the pressure in the chamber and receiver is up to 0.8 MPa, after stabilization of the pressure in the chamber and receiver, the connection between the receiver and chamber is closed, and the moisture condensed in the receiver is drained from the receiver, then in the chamber Ru is supplied with dry air heated to a temperature of 60-80 ° C, after stabilization of the pressure in the chamber, the cycle is repeated until the final moisture content of the wood is reached. After reaching the final moisture content of the wood, it is possible to conduct several more cycles, lowering the temperature of the supplied dry air to the temperature of the air outside the chamber.

Comparison of the claimed technical solution with the prototype shows that it differs in the following features:

- wood is heated to a temperature of 60-80 ° C;

- create a vacuum in the receiver and then equalize the pressure in the chamber and receiver to 0.8 MPa;

- after stabilizing the pressure in the chamber and the receiver, the connection between the receiver and the camera is closed;

- Condensed moisture in the receiver is drained from the receiver;

- dry air heated to a temperature of 60-80 ° C is fed into the chamber;

- after pressure stabilization in the chamber, the cycle is repeated until the final moisture content of the wood is reached;

- after reaching the final moisture content of the wood, several more cycles are carried out with a decrease in the temperature of the supplied dry air to the temperature of the air outside the chamber.

Therefore, we can assume that the claimed invention meets the criterion of "novelty."

The invention can be implemented on standard equipment using well-known processes, therefore, it meets the criterion of "industrial applicability".

Features of the process:

1) we do not wait when all the wood in the chamber warms up to a temperature of 60-80 ° C,

2) moisture is removed from the chamber with each cycle,

3) maximum vaporization (maximum moisture saturation),

4) one cycle is 10 minutes,

5) the last cycles are carried out to reduce the temperature of the wood to ≈18 ° -20 ° C and increase the pressure inside it. This is done so that after removing the wood from the chamber, it would not gain moisture from the air.

In the process of conducting patent information research, the claimed combination of features has not been identified, therefore, the claimed invention meets the criterion of "inventive step".

The drawing schematically shows the installation for implementing the proposed method. The installation contains: 1 - a drying chamber, for example (SNVS-4,3.4,3.49 / 3-42), a receiver, 3 - a container for collecting condensate, 4 - a heater, 5 - a container with silica gel, 6 - a vacuum pump, 7, 8 , 9, shutoff valves.

The method is implemented as follows. Lumber is loaded into the drying chamber (see drawing) and the temperature in the chamber is adjusted to ≈60 ° -80 ° C. A vacuum is created in the container 2, such that when the valve 7 is opened in the drying chamber and the container 2, the pressure is ≈0.8 MPa. When valve 7 is opened, air saturated with moisture vapor enters container 2, the temperature of which is ≈18 ° -20 ° C, where moisture condensation occurs. Since the pressure in the drying chamber becomes less than inside the lumber, air saturated with moisture vapor leaves the lumber. As soon as the pressure in the drying chamber and tank 2 is stabilized, but remains less than atmospheric, the valve 7 closes and valve 8 opens. The moisture condensed in the tank 2 is drained into the tank 3. At the same time, the valve 9 opens and dry air passed through silica gel, heated by a heater to a temperature of ≈60 ° -80 ° C, enters the drying chamber. As a result of mixing dry air with moist, the percentage of moisture in the mixture becomes less than in the air inside the wood. Since the air pressure inside the wood is less than outside it, the air of the mixture enters the wood, where it is saturated with moisture. After the pressure stabilizes, the cycle repeats.

Thus, with each cycle, the moisture contained in the air inside the wood is carried out first to the drying chamber, and then to the reduced pressure tank, where it condenses and then merges into the condensate collection tank.

According to the specified method, oak samples were dried. The experimental results are shown in table 1

Table 1 one Breed Oak Oak Oak Oak Oak Oak Oak 2 Initial Mass (g) 90.39 135.95 141.84 140.28 136,235 136,235 134.7 3 The initial humidity (%) 27 28 thirty 29th 27 27 29th four Vacuum pressure (at) 0.3 0.5 0.5 0.5 0.5 0.5 0.5 5 Cycle time (min) 10 10 10 10 10 10 10 6 Chamber Temperature (° C) 60 80 75 75 75 75 75 7 Drying time (hour) eleven 7 8 8 7 8 8 8
Ultimate
humidity (%) 8-10 8-10 8-10 9-10 8-10 8 8 9 Final weight (g) 77.48 116,545 122.96 118.98 113,755 115,775 112,035

Claims (1)

 A method of drying wood by alternating cycles, including processing the wood in the chamber with a coolant and heating it, followed by evacuation using a receiver attached to the chamber, characterized in that the temperature in the chamber is raised to 60-80 ° C, a vacuum is created in the receiver and then the pressure is equalized to the chamber and the receiver to 0.8 MPa, after the pressure in the chamber and the receiver has stabilized, the connection between the receiver and the camera is closed, and the moisture condensed in the receiver is drained from the receiver, then a dry, heated to the temperament is fed into the chamber Aturi 60-80 ° C air pressure after stabilization of the cell cycle is repeated until the final moisture content of wood.