RU2568471C2 - Method for improving of wood strength, hardness and fire resistance - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to woodworking, particularly, to lumber processing. Claimed process comprises timber dressing, degassing and impregnation of blanks in sealed chamber. Impregnation solution represents a liquid phase of natural wastes of cattle. Preliminary degassing of wood blanks is performed in the chamber at 60-62 mm Hg, 70-80°C for 18-20 minutes. After chamber unsealing, impregnation solution is fed to impregnate the wood without outer pressure for 15-20 minutes.

EFFECT: higher efficiency of wood protective processing.

1 dwg, 2 tbl

Description

The invention relates to the woodworking industry and can be used to increase the stability, strength and fire resistance of wood products and structures.

A known method of producing products from modified wood (see SU No. 1248802, B27K 5/06, publ. 07/08/1986), comprising treating wood waste with urea, divided in the axial plane into two equal half cylinders, and drying under pressure in a rectangular matrix. However, the main purpose of the invention is to give plastic properties and a new shape in order to reduce waste during subsequent machining. At the same time, there are no data on the acquisition of modified properties by modified wood in terms of strength, fire resistance, and moisture resistance.

A known method of producing a material with improved decorative and antibacterial properties (see application RU No. 95108649, B27K 5/02, publ. 08/20/1996), when ammonium carbonate or aqueous ammonia solution is introduced into the wood processing vessel, and then the wood is sequentially processed a mixture of gaseous ammonia and gaseous oxygen at various indicators of pressure and temperature. The disadvantage of this method is the need for the use of chemical preparations of the modifying mixture and the use of special equipment of complex design, which significantly increases the cost of production as a whole.

A known method of processing low-value wood (see RU No. 2142876, B27K 5/06, publ. 12/20/1999), increasing its physico-mechanical properties, which is based on the processing of wood in an autoclave in the presence of gaseous ammonia at various pressure and temperature, five times cycles of heating, evacuation, and then processing the material with mechanical pressure. The method is intended mainly for the treatment of wood particles and is characterized by significant energy consumption.

Closest to the proposed invention is a method that improves the quality of wood processing, which reduces the duration of the impregnation of cylindrical billets with an oily antiseptic (up to 6 m long) and includes sonication and variable pressure (see RU No. 2378106, B27K 3/02, B27K 3 / 08, published January 10, 2010). However, the need for additional acquisition of ingredients for the impregnation composition, as well as the purchase of specialized equipment for ultrasonic processing of wood, do not contribute to the reduction of the cost of production in general.

The problem to which the claimed invention is directed, is expressed in increasing the efficiency and cheaper processes of giving wood stability, strength and fire resistance.

The technical effect obtained by solving the problem is expressed in obtaining a method of increasing the stability, strength and fire resistance of wood using natural waste from livestock complexes.

To solve this problem, a method of increasing the stability, strength and fire resistance of wood, including cutting wood along the fibers, evacuating and impregnating the workpieces in a sealed chamber, is characterized in that the liquid phase of natural cattle waste (cattle) is used for the impregnating solution, with preliminary evacuation wood preforms are carried out in a chamber at a pressure of 60-62 mm Hg, a temperature of 70-80 ° C for 18-20 minutes, then after depressurization of the chamber, an impregnating solution is fed and carried out ropitku wood without external pressure for 15-20 min.

A comparative analysis of the features of the claimed solution with the features of the prototype indicates the compliance of the claimed solution with the criterion of "novelty."

The features of the distinctive part of the claims provide an increase in the effectiveness of protective treatment of wood by using natural waste products of cattle, which significantly reduces the cost of the work.

As a result of the protective treatment of wood by the claimed method, the workpieces are compacted, the porosity decreases and the hardness increases. Wood gains resistance to temperature and humidity, due to low porosity in the material increases fire resistance, in addition, wood is not exposed to the destructive effects of biohazards (fungi, insects).

The claimed invention is illustrated by drawings, where the drawing shows a flow diagram of the collection of the liquid phase of natural waste cattle and wood processing.

The technological process of protective wood processing includes the use of the following equipment: cutting equipment 1 with wood feed mechanisms 2, a vacuum impregnation chamber 3 with a drain pipe 12, a vacuum pump 4 and an airtight hatch 13, a loading and unloading trolley 14, a storage tank for collecting the natural liquid phase livestock waste cattle 5 with an insulated wall 6 to maintain a constant temperature in the chamber and the electric motor 8 of the vibrator 15, the wing elevator for cleaning manure 9 from the can ohm for collecting manure 7 mesh flooring 10 for drainage of the liquid phase (urine), aft cell 16 in RNC 11 camp.

In this case, the vacuum pump 4 is equipped with a safety valve for compressed air, with which the pressure in the impregnation tank is regulated.

In the impregnation chamber 3, a technological mode for processing wood is provided, examples of which are shown in Table 1, based on which the optimal processing conditions are determined, for example, at a vacuum pressure of not more than 62 mm Hg, wood temperature 40 ° C, the circulation coefficient is 1.315 cm / sec

The method of processing wood is as follows.

The method can be carried out, for example, in livestock complexes. In this case, at the initial stage, the separation and accumulation of cattle liquid phase in separate tanks is carried out. The device also contains a vacuum chamber, heated and filled with natural waste from a separate tank under a certain pressure.

Wood raw materials, for example, in the form of round wood, pre-sorted by size, species, etc., are sent for processing. At the same time, assortments can be trimmed in length to the desired size and forced drying is not required.

Thus, round wood, for example, atmospheric drying, is cut along the fibers onto the boards. Next, the resulting blanks are placed in a sealed chamber, which can be used, for example, special autoclaves for impregnation of long wood. For loading and unloading stacks, auxiliary in-shop transport equipment is used (for example, trolleys on rails).

After loading the wood, a reduced pressure of 60-62 mm Hg is created in the chamber. at a temperature of 70-80C °, the exposure time under these conditions is 18-20 minutes. It is believed that as a result of changes in temperature and pressure in the chamber, the moisture contained inside the wood undergoes strong evaporation, causing tearing of the cell walls. This creates a vacuum to increase the permeability of the material.

Then, in the process of gradual depressurization of the chamber, an impregnating solution is fed on the natural waste products of cattle, the exposure time of wood in the chamber with the solution is 15-20 minutes. The impregnated wood is unloaded from the chamber and placed in a warehouse for drying in natural conditions in the open air.

The content in the impregnating solution is: nitrogen - 0.50 g / l, ammonia - 14.73 units, ash 2.80 units.

Table 2 shows the comparative test results of wood treated and untreated with a protective composition.

Tests for the fire resistance of wood were carried out according to the method of calculating fire resistance, which is based on determining the time after which, under conditions of high-temperature exposure, in a fire one of the limiting states occurs. The main criterion for the fire resistance assessment methodology is the section burnup depth (Z), which depends on the section burnup rate, burning time, ambient temperature (T), humidity (W0) and many other parameters. In the calculations, the values of T, W0 remain constant, therefore, the main characteristics are the burning rate of the cross section, the burning time, and also the calculated value of the wood resistance in case of fire, taking into account the decrease in the working cross section of the material as a result of carbonization and, accordingly, the increase in stress in the wood.

According to the requirements of SNiP II-2-80 and STO 36554501-066-2006 "Rules for ensuring fire resistance and fire protection of reinforced concrete structures" the carbonization rate for solid wood is accepted within 1 mm / min for elements with dimensions in the cross section of less than 120 mm and 0.7 -0.8 mm / min - more than 120 mm.

The effectiveness of the impact of cattle waste on wood is also confirmed by the test results of the samples for strength and fire resistance, for example, from the flooring parts of dismantled utility rooms of livestock complexes, where cattle were kept for a long time.

A comparative analysis of the experimental and control wood samples showed the following results. Cracks from 0.2 to 1.1 cm wide, 8 to 15 cm long, and 0.5 to 2.3 cm deep were formed on control samples. Cracks up to 0.5 cm wide and up to 7 in length were detected on experimental samples. cm, depth - not more than 0.7 cm.

Fire tests of experimental and untreated wood samples were carried out by exposure to open fire for 3 minutes. As a result of this, rapid ignition of the untreated sample was observed, characterized by flame propagation. In the samples of the experimental group, under the same test conditions, no open fire was observed, while the wood smoldered, and the carbonization depth after self-extinguishing was an average of 1.2 cm, which can also indicate a low temperature of the exhaust gases.

Thus, in wood after protective treatment by the present method are observed:

- increase in density up to 30-35% due to, most of all, a decrease in porosity as a result of salting of the impregnating substance in the pores of the wood;

- increase in strength properties up to 10-15% as a result of wood compaction;

- improves the resistance of wood to temperature and humidity, which is characterized by the stability of its shape and linear dimensions, as well as a significant reduction in water and gas permeability and water absorption;

- increases fire resistance by preventing the free flow of oxygen into the internal cavity of the wood.

Claims (1)

A method of increasing the stability, strength and fire resistance of wood, including cutting wood, evacuating and impregnating the workpieces in an airtight chamber, characterized in that the liquid phase of the natural waste of cattle is used as an impregnating solution, while preliminary evacuation of the wood blanks is carried out in a chamber at a pressure of 60 -62 mmHg, temperature 70-80 ° C for 18-20 minutes, then after depressurization of the chamber, an impregnating solution is supplied and the wood is impregnated without external pressure in within 15-20 minutes

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