RU2243886C1 - Wood impregnation method - Google Patents

Abstract

FIELD: wood-working industry, in particular, volumetric impregnation of wood with water-soluble dyes.

SUBSTANCE: method involves placing wooden blank into chamber 1; filling chamber 1 with water-soluble dye supplied from dye tank 5, when vacuum in chamber 1 reaches required vacuum extent; increasing pressure in chamber 1 to P_max; closing valve 11 and switching off pump when pressure reaches P_max value; Pressure in chamber 1 is reduced owing to penetration of water-soluble dye into wood. When pressure alteration rate in chamber 1 is reduced to ≤ 1,400 Pa/s, valve 11 is opened and pump 4 is switched on. Pressure in chamber 1 is raised to P_max value. Process is repeated until pressure dropping rate of ≤ 1,400 Pa is within the range of from P_max to 0.9 P_max. Then impregnation process is stopped.

EFFECT: increased efficiency and precise determination of impregnation time.

2 dwg

Description

The invention relates to the field of bulk impregnation of wood with water-soluble dyes.

A known method of autoclave wood impregnation (RF patent No. 2144434, IPC B 27 K 3/08, publ. 10.01.99), in which the wood is placed in an autoclave. Impregnation is carried out by alternating static and variable pressure with an amplitude of 0.05-0.5 MPa and a frequency of 2-40 Hz.

The disadvantage of this method is the long term of the wood impregnation due to the complexity of determining the end of the impregnation process.

Closest to the proposed method by technical essence is the method of impregnation of porous materials that we have chosen for the prototype (RF patent No. 20111511, IPC B 27 K 3/02, publ. 04/30/94), including loading the material into the chamber, filling it with an impregnating liquid with subsequent sealing, spasmodic creation in the discharge chamber, supply of impregnating liquid under pressure, holding the material under pressure, pumping liquid, removing material.

The disadvantage of this method is the inaccurate determination of the impregnation time due to the complexity of determining the end of the impregnation process for various volumes of loading and for various physicochemical properties of wood. The time spent on the impregnation of 0.02 m ³ of birch wood by the above method was 20 minutes.

The main technical result of the proposed method is the precise determination of the impregnation time due to the fact that the moment of the end of the wood impregnation in this method is clearly defined, this eliminates unreasonable exposure of the material in the dye, which leads to an increase in the quality of impregnation. The time spent on impregnation of 0.02 m ³ of birch wood according to the claimed method was 15 minutes, which is 33% less than in the prototype.

The specified technical result is achieved by the fact that in the proposed method of impregnating wood, including loading material into the chamber, sealing the chamber, creating a vacuum in it, supplying a water-soluble dye and creating a varying pressure in the chamber, according to the proposed solution, the pressure in the chamber is increased by pulses to a predetermined value P _max = 1.2 MPa, and each subsequent pressure pulse is created after the pressure drop of the previous pulse decreases to a value of ≤1400 Pa / s, and the impregnation process is stopped when The drop rate of the pressure pulse ≤1400 Pa / s is in the pressure range from P _max to 0.9 P _max .

An example of a specific implementation. Figure 1 shows a diagram of the installation for implementing the proposed method, figure 2 is a graph of the pulse pressure.

The installation consists of a working chamber 1, an expansion tank 2, a vacuum pump 3, a high pressure pump 4, a container for impregnating liquid 5, a high pressure valve 6, a pressure gauge 7, valves 8-12 and pipelines. Controlling the impregnation process is possible using a computer.

In accordance with the proposed method, birch billets with a size of 20 × 100 × 700 mm were placed in chamber 1 (the chamber loading volume was 0.02 m ³ ). In chamber 1, a reduced pressure was created by vacuum pump 3 through valves 8, 9 and expansion tank 2. After reaching the required vacuum in the chamber, valve 8 was closed and chamber 1 was filled with water-soluble dye (water-soluble, red-brown No. 3 for wood) from tank 5 through the valve 10, then the valves 9, 10 were closed and the pressure in the chamber increased to the maximum value (1.2 MPa) (Fig. 2, section I) through valves 11, 12 by pump 4. When pressure reached 1.2 MPa, valve 11 was closed, and pump 4 was turned off. The pressure in the chamber was reduced due to the incorporation of a water-soluble dye into the wood. With a decrease in the rate of change of pressure in the chamber ≤1400 Pa / s (Fig. 2, section II), valve 11 opened and pump 4 turned on. The pressure in the chamber again rose to P _max (1.2 MPa). The process is repeated until the pressure drop rate ≤1400 Pa / s is in the range from P _max (Fig. 2, direct A) to 0.9P _max (Fig. 2, direct C). After that, the impregnation process was stopped. Acid, blue, and black dyes for fabrics were also used as a water-soluble dye, and similar results were obtained.

Figure 2 presents (with a gap along the t axis) a graph of the supply of pulsed pressure according to the proposed method, obtained by performing a specific example.

Zone I (see figure 1) shows the time of pressure increase to P _max = 1.2 MPa. After turning off the high-pressure pump, the pressure decreases along the decline curve for the time indicated in the graph by zone II. After reducing the decay rate of the pressure pulse ≤1400 Pa / s, the next pressure pulse is applied. The pressure drop rate is defined as the ratio ΔP / Δt. Curve B shows the degree of saturation of the wood with dye.

The measurement of the rate of pressure drop is carried out according to the following method: for example, consider the methodology for determining the rate of decline of the first pressure pulse (zone II, figure 2). We select the time interval for the change in the pressure of the pulse Δt = 10 s and with the help of a manometer, the value ΔР of the pressure decrease during this time is determined. The starting point of the time reference is the moment the pulse begins to decline (P _max = 1.2 MPa).

In the first 10 s (points a-b, Fig. 2) ΔР = 1.2-0.52 = 0.68 MPa, or the rate of pressure decrease V = 0.68 / 10 = 0.068 MPa / s.

In a similar way, the decay rate of the pressure pulse is determined at the subsequent selected time intervals (intervals b-c, c-d, d-d, d-e, Fig.2). In the interval d e ΔР = 0.22-0.21 = 0.01 MPa, then V = 0.01 / 10 = 0.001 MPa / s, or 1000 Pa / s. In these conditions, the next pressure impulse is supplied, because it is below a predetermined limit of the decay rate of the pressure pulse. The rate of decline of each subsequent pressure pulse is determined by the above methodology.

The impregnation process stops when the pressure pulse drop rate is ≤1400Pa / s in the pressure range from 1.2 MPa to 0.98 MPa (P _max -0.9P _max ). For example, when the impregnation time is less than that determined by the proposed method (the points of curve B (FIG. 2) are below straight line C (FIG. 2)), this indicates incomplete impregnation. When the impregnation time is more than determined by the proposed method (the points of curve B (Fig. 2) are above line C (Fig. 2)), unreasonable losses of funds and time are observed. Curve B (figure 2) in the pressure range from P _max to 0.9 P _max goes almost parallel to the abscissa axis, which indicates the complete impregnation of wood with dyes. The intersection point of curve B with line C is the criterion for determining when the impregnation process ends. As can be seen from the graph in figure 2, a deviation from the claimed mode leads to an unreasonable increase in the time of impregnation or lower product quality.

In the given specific example, the time spent on impregnation by the proposed method was 15 minutes, and when impregnated by the method of the prototype of the same volume of wood - 20 minutes, which is 33% more.

Thus, the proposed method of impregnation of wood eliminates the cost of impregnation time and to control the completeness of impregnation in the process, regardless of the volume of load and wood species. Similar results were obtained by impregnating aspen and poplar.

Claims (1)

A method of impregnating wood, including loading material into the chamber, sealing the chamber, creating a vacuum in it, supplying a water-soluble dye and creating a varying pressure in the chamber, characterized in that the pressure in the chamber is increased to a predetermined value by pulses, and each subsequent pressure pulse is created after speed reduction previous pulse pressure decay to a value ≤1400 Pa / s, and the impregnation process is stopped when the rate of pressure drop ≤1400Pa pulse / s is in the range of _Pmax to 0,9R _max.

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