RU2230658C1 - Method for manufacture of articles of antiseptic-treated wood, railroad sleepers inclusive - Google Patents

Abstract

FIELD: manufacture of antiseptic-treated wood: piles, railroad sleepers.

SUBSTANCE: the autoclave is charged with wood of disperse-vascular species of trees: asp, birch, alder, lime, etc., with a moisture content exceeding the limit of hydroscopicity, i.e. more than 25 to 30%. The antiseptic material heated to a temperature of 80 to 95C with the aid of a heater- heat exchanger is pumped through the autoclave providing circulation of the antiseptic material between the autoclave with articles charged in it and the antiseptic heater at a rate of passing around of the articles at least 0.01 ms. Vacuum processing and press rise cycles are accomplished in the autoclave. After the next in turn vacuum processing moisture is removed from the autoclave with the aid of a condensing device, and heated antiseptic material is added to the autoclave. The parameters of two-four initial "pressure-vacuum cycles are set as follows: seasoning - 240 to 300 min at a vacuum of 0.05 to 0.075 Mpa, seasoning - 15 to 20 min under a liquid pressure of 0.4 to 0.6 Mpa. The other parameters of the process: alternation of gas and hydraulic pressures, antiseptic temperature are set and adjusted depending on the necessary degree of impregnation of the articles and the properties of antiseptic. Hydrophobic liquid with a boiling point exceeding that of water is used as antiseptic.

EFFECT: expanded list of tree species from which treated-treated articles may be produced, excluded preliminary drying of wood.

3 cl, 1 dwg

Description

The invention relates to the manufacture of products from canned (antiseptic) wood: piles, bridge structures, mainly railway sleepers and can be used in wood and timber impregnation plants.

A known method of manufacturing railway sleepers and a device for its implementation, where substandard sleepers are crushed, then pressed with an adhesive mass and an atiseptic (RF patent No. 2045395, class. 27 M 3/14, 10/10/1995).

A known method of preservation of wood, in particular wooden sleepers, by wrapping with synthetic fabric (and.with. No. 338380, class. 27 M 3/14, 05/15/1972).

These technical solutions are expensive and due to technological difficulties are not widespread in the factory.

In the book of M.D. Former and N.I. Fedorov. Protective wood processing. M .: Forest industry, 1981, p. 11, 13, 83, 72, a combined drying-impregnation method is physically justified, based on the use of a hydrophobic liquid and as a coolant for the evaporation of water from wood under reduced pressure, and as an antiseptic when replacing it with water in wood at a pressure above atmospheric. However, the method did not find application in the factory due to a number of technical difficulties. Balance calculations and numerous experiments on factory equipment show that autoclave drying-impregnation, as it is proposed to carry out in the above, does not make it possible to efficiently heat and vacuum remove water from wood containing more than the hygroscopicity limit (25-30%) (Large Soviet Encyclopedia, article “Wood”, section “Physical Properties D”, Abs. 2, M., 1977).

In the factory, the method described in the documentation for Wooden sleepers for broad gauge railways was implemented. Technical conditions GOST 78-89. USSR State Committee for Standards. M., Protection of wood. Autoclave impregnation with oily protective agents. GOST 20022.5-93. Interstate Council for Standardization, Metrology and Certification, Minsk.

According to this technology, wood products are mechanically processed, stacked and subjected to atmospheric drying to a moisture content of no more than 25%. The dried products are placed in an autoclave with a heated oily antiseptic. Then, in an autoclave, depending on the requirements of the depth of impregnation, one of three modes is implemented: I - pressure-pressure-vacuum; II - pressure-vacuum; III - vacuum-pressure-vacuum.

The disadvantage of this method is the impossibility of its application for scattered-vascular tree species, in particular aspen, and the need for preliminary drying of wood of other tree species.

At the same time, it is known from the theory of wood science that dispersed-vascular tree species (aspen, alder, linden, poplar) are characterized by good permeability. However, in the process of drying, the wood is oxidized and secondary bioprocesses are activated in it (microfiltration). In the absence of natural protective resins, as in conifers, this leads to blockage of blood vessels in the wood and, as a result, to a sharp decrease in the permeability of these tree species. During chamber drying, for example, aspen billets acquire cracks that develop even more into the process of impregnation with an antiseptic when alternating pressure and vacuum. Aspen and the large willow tree family to which it belongs are subject to rapid decay; in this regard, such wood is of limited use: the manufacture of containers, matches, fuels, paper (Big Soviet Encyclopedia, article “Aspen”, M., 1977).

The closest prototype of the proposed method from among the known technical solutions is a method of processing wood, which consists in impregnating it with an oil antiseptic under pressure, followed by evacuation of the residual antiseptic by vacuum. When processing wood in this way, not only a liquid antiseptic is used, but also its fumes (RF patent No. 2026777, class. 27 K 3/08, 01.20.1995).

The disadvantage of this method is the possibility of its use only in the processing of wood with natural hygroscopicity, i.e. humidity less than 25-30%. With this humidity, a number of tree species (aspen, alder, poplar) lose their permeability properties and cannot be qualitatively saturated with an antiseptic. Before impregnation of coniferous products, it is necessary to dry them, which requires a lot of time and labor for overloading and stacking.

The proposed method is aimed at eliminating the noted drawbacks and the following result can be obtained from its use: the list of tree species will be expanded, from which antiseptic products can be produced using a high-tech way. When implementing the method there is no need for labor-intensive processes of atmospheric or chamber drying of wood.

This result is achieved due to the fact that wood is loaded into the autoclave, including scattered vascular tree species: aspen, birch, alder, linden, etc., with humidity exceeding the hygroscopicity limit, i.e. more than 25-30%. An antiseptic, heated with a heater-heat exchanger, is pumped through an autoclave, circulating the antiseptic between the autoclave with the products loaded in it and the antiseptic heater with a flow rate of at least 0.01 m / s. It has been found by calculation and experimentation that at such a speed effective heat-mass transfer occurs. In the autoclave, vacuum and pressure rise cycles are carried out. After the next evacuation, moisture from the autoclave is removed using a condenser device and the autoclave is replenished with a heated antiseptic. The parameters of two or four initial pressure-vacuum cycles are set according to the following scheme: holding 240-300 min at a vacuum of 0.05-0.075 MPa, holding 15-20 min at a liquid pressure of 0.4-0.6 MPa. Other process parameters: the alternation of gas and hydraulic pressures, the temperature of the antiseptic is set and regulated depending on the degree of impregnation of the product and the properties of the antiseptic. As an antiseptic, a hydrophobic liquid with a boiling point higher than that of water is used, for example, carbonates, paraffins, hydrocarbon oils (including coal).

The method can be implemented at the sleeper treatment plants (SHP) of Russia, where the autoclave equipment with minor modifications allows this combined drying-impregnation process. An example of the method is carried out at the Reshotinsky Shipyard of the Ministry of Railways (Krasnoyarsk Territory, Nizhneingashsky District). In the scheme of the device for implementing the proposed method, the positions in the drawing indicate: autoclave 1, aspen sleepers 2, vacuum pump 3, condenser 4, condensate drain valve 5, antiseptic tank 6, valve for antiseptic supply 7, heat exchanger (heater) for heating the antiseptic 8, antiseptic circulation pump 9, compressed air cylinder 10.

In the autoclave 1 loaded standard railway sleepers 2 wide gauge (type I), made from raw aspen, humidity 50-70%. The impregnation was carried out with coal oil, heated to 95 ° C in the heat exchanger 8. The pressure parameters in the autoclave are set: evacuation - vacuum pump 3 - up to 0.07 MPa; overpressure - with compressed air from a cylinder 10 - up to 1.2 MPa. 4 cycles of “vacuum pressure” were performed with a duration of 100 to 200 min exposure in each mode. In all cycles, after removing the vacuum from the vacuum collector (condenser) 4, moisture was removed through the tap 5, and the antiseptic was added to the initial level from the tank 6. In the combined drying-impregnation process, the antiseptic pump 9 was pumped between the sleepers in an autoclave along the circulation circuit “ autoclave-heat exchanger ”with a speed of 0.01-0.03 m / s. The condensate removed is cleaned. Dehydrated antiseptic is returned to container 6.

In the obtained sleepers there is no cracking, and the depth of impregnation with an antiseptic exceeds the impregnation requirements according to GOST 20022.0 for coniferous trees, i.e. makes more than 60 mm.

Thus, an analysis of the drying and impregnation of wood allowed us to create a method for the production of products, in particular railway sleepers, from antiseptic aspen, previously considered non-productive waste. When impregnating coniferous products, there is no need for a preliminary drying process.

Claims (3)

1. A method of manufacturing wood of antiseptic products, including railway sleepers, by mechanical processing of wood and its subsequent impregnation in an autoclave with a heated antiseptic with alternating pressure and vacuum of a liquid and gas medium, characterized in that the wood is loaded into the autoclave, including and scattered-vascular tree species, with humidity exceeding the hygroscopicity limit, i.e. more than 25-30%, while a hydrophobic antiseptic, heated to a temperature of 80-95 ° C, having a boiling point higher than that of water, is pumped through the autoclave, ensuring the circulation of the antiseptic between the autoclave with the products loaded in it and the antiseptic heater with a flow rate of products less than 0.01 m / s, while removing moisture from the autoclave using a condenser device after the next evacuation and replenishing the autoclave with a heated antiseptic, and the parameters of two or four initial pressure-vacuum cycles are set as follows the following scheme: holding 240-300 min at a vacuum of 0.05-0.075 MPa, holding 15-20 min under a liquid pressure of 0.4-0.6 MPa. 2. The method according to claim 1, characterized in that it also antiseptic products from scattered-vascular tree species: aspen, alder, birch, poplar, linden. 3. The method according to claim 1, characterized in that a hydrophobic liquid is used as an antiseptic: carbonates, paraffins, hydrocarbon oils, including coal.