RU2298139C2 - Timber drying method, mainly beams or logs (variants) - Google Patents

Abstract

FIELD: wood working, namely wood drying processes, mainly drying beams or logs, possibly in wood working plants or in plants of other industry branches.

SUBSTANCE: method for drying wood material, mainly beams or logs comprises steps of heating beam or log from inside. It is realized due to forming slits along lengthwise axis of beam or log and placing in said slits heat source in the form of electrically conducting member. Then slits are filled with moisture-proof heat- insulating heat-resistant elastic material. According to first variant of invention one slit is formed with depth achieving geometry center of cross section of log or beam or its vicinity. According to second variant of invention at one side of beam or log along its lengthwise axis or symmetrically relative to it one or several slits are formed. According to third variant of invention at one side of beam or log along lengthwise axis or symmetrically relative to it one or several slits are formed and also at least one slit is formed between said slits at opposite side of beam or log. According to fourth variant of invention slits are formed along lengthwise axis of beam or log at one side and symmetrically at opposite side.

EFFECT: improved efficiency of drying process.

Description

The invention relates to woodworking, and in particular to a technology for drying wood, mainly logs or beams, and can be used in enterprises of woodworking and other industries.

A known method of drying wood and installation for its implementation (application No. 95114879, IPC F26B 5/04, F26B 3/20, publ. 1997.08.27). The method includes heating the wood with thermostatted heating elements to the required temperature, holding at each heating stage and periodically vacuum treating the wood in the drying process, while thermostatted heating elements are heated directly in several zones along the length of the dried material with gaps between the heating zones.

A known method of processing wood (RF patent No. 2129955, IPC B27K 5/00, B27K 3/34, publ. 1999.05.10), comprising impregnating wood with a saturated urea solution at room temperature to absorb at least 20% urea to the weight of absolutely dry wood, then exposure to air in an indoor environment for at least 24-72 hours and only then produce two-stage drying to a residual wood moisture of not more than 20%.

A known method of convective drying of wood, mainly logs or beams, (RF patent No. 2163328, IPC F26B 3/04, F26B 1/00, publ. 2001.02.20), according to which before drying along the longitudinal axis of the beam or log on its opposite sides perform grooves along which direct the flow of air. The invention is aimed at reducing the drying time and associated energy costs.

A known method of drying wood (RF patent No. 2047064, IPC F26B 7/00, publ. 1995.10.27), closest to the claimed and adopted for the prototype, which provides for the processing of piece of raw feedstock, for example logs with ends. The log is wrapped with elastic resilient material in the form of a tape, and sealing shells are installed at the ends, connected by nozzles to a source of pressure or vacuum. The tape also has nipples connected to a source of pressure or vacuum. The pressure or vacuum is applied depending on the selected drying technology of the log, if compressed superheated CO ₂ gas is supplied through the nozzles, then the nozzles are connected to the vacuum unit, if gas is pumped through the nozzles, then the outlet through the vacuum unit is carried out by nozzles. With a significant diameter of the log, a channel is formed along its axis and a perforated pipe is placed in it, through which gas is removed or pumped. This method is characterized by the complexity of the preparatory operations, the presence of sophisticated equipment for the content and heating of gas, which determines the lack of efficiency of the drying method.

The technical result, the solution of which the invention is directed, is to increase the efficiency of the drying process.

The technical result is achieved by the fact that in the method of drying wood, mainly timber or logs (option 1), including heating from the inside of a timber or log, it is new that a slot is made along the longitudinal axis of the timber or log in which a heat source is placed in the form of an electrically conductive heating element and fill it with a moisture-proof heat-insulating heat-resistant elastic material. In this case, the slot is made deep to the geometric center of the cross-section of the beam or log or close to it, and from the side opposite the side with the slot, longitudinal grooves are made in the beam or log to compensate for thermal expansion and stress relief during drying.

In the method of drying wood, mainly timber or logs (option 2), including heating from the inside of a timber or log, it is new that, on one side of the timber or log along the longitudinal axis and symmetrically relative to it, at least one slot is made in each of which place a heat source in the form of an electrically conductive heating element and fill it with a moisture-proof heat-insulating heat-resistant elastic material. In this case, the slots in the beam are made with the following ratios: а = L / 2-L / 5, Н / 4 <b≤Н / 2 and с = 2-3 mm, where L is the width of the beam, H is the height of the beam, and - the distance between the slots, b is the depth of the slot, s is the width of the slot, and for the log of the slot is performed with the following relationships: a = D / 2-D / 5, D / 4 <b≤D / 2 and c = 2-15 mm, where D is the diameter of the log, a is the distance between the slots, b is the depth of the slot, and c is the width of the slot. From the side opposite to the side of the timber or logs with slots, longitudinal grooves are made to compensate for thermal expansion and relieve stress during drying.

In the method of drying wood, mainly timber or logs (option 3), including heating from the inside of the timber or logs, it is new that at least one cut is made on each side of the timber or log along the longitudinal axis and symmetrically with respect to it sides from the axis and at least one slot between them on the opposite side of the beam or log, in each of which a heat source is placed in the form of an electrically conductive heating element and filled with a moisture-proof heat-insulating heat-resistant elastic gim material. The depth of each slot does not reach a plane perpendicular to the slots and passing through the longitudinal axis of the beam or log, while in the beam the slots are made with the following ratios: a = L / 2-L / 5, b <N / 2, b * <b, s = 2-15 mm, where L is the width of the beam, N is the height of the beam, a is the distance between the slots, b is the depth of the slots on one side of the beam, b * is the depth of the slot in the beam from the side opposite to the slots with depth b, c is the width of the slots, and for a log, the slots are performed with the following relationships: a = D / 2-D / 5, b <D / 2, b * <b, c = 2-15 mm, where D is the diameter of the log, and - distances e between the slots, b is the depth of the slit on one side of the timber, b * is the depth of the slit on the side opposite to the side with slots with a depth of b, and c is the width of the slots.

In the method of drying wood, mainly timber or logs (option 4), including heating from the inside of the timber or log, it is new that along the longitudinal axis of the timber or log, cuts are made on one side and symmetrically on the opposite side, in each of which a heat source is placed in the form of an electrically conductive heating element, after which the slots are filled with a moisture-proof heat-insulating heat-resistant elastic material. The slots are made with a depth less than half the height of the beam or half the diameter of the log with a distance g between the internal ends of the slots of at least 4 cm.Long grooves are made on both sides of the beam or log with slots to compensate for thermal expansion and stress relief during drying.

For all four options, drying is carried out at a temperature of an electrically conductive heating element of 90-150 ° C during the entire drying time at an ambient temperature of 30-50 ° C, a relative humidity of 60-70% and a blowing speed of 1-3 m / s until the residual humidity is reached wood no more than 20%, while in the drying process, thermal moisture treatment of timber or logs is carried out periodically for 1 hour at an ambient temperature of 90-95 ° C and a relative humidity of 95-100%.

The invention is presented in figures 1-7,

Where

figure 1 is a General view of the dried log according to option 1;

figure 2 is a cross section of a bar during drying according to option 2;

figure 3 is a transverse section of a log when drying according to option 2;

figure 4 is a cross section of a bar during drying according to option 3;

figure 5 is a transverse section of a log when drying according to option 3;

6 is a cross section of a log when drying according to option 4;

Fig.7 is a cross section of a bar during drying according to option 4.

Here: 1 - the assortment to be dried (timber or log); 2 - a longitudinal slot on one side of the assortment; 3 - a longitudinal groove for compensating for temperature stresses and stress relief during drying; 4 - a longitudinal slot on the other side of the assortment; 5 - electrically conductive heating element; 6 - moisture-proof heat-insulating heat-resistant elastic material; H is the height of the beam; L is the width of the beam; D is the diameter of the log; a - the distance between the slots on one side of the assortment; b is the depth of the slots on one side of the assortment; b * is the depth of the slot on the other side of the assortment; C is the width of the slots; g is the distance between the inner ends of the slots according to option 4.

Drying is as follows.

In assortment 1 (first option), mainly in a bar or log, a slot 2 is made along the longitudinal axis (Fig. 1), in which a heat source is placed - an electrically conductive heating element 5, while slot 2 is made to or close to the geometric center of the assortment cross section 1, after which the slot is filled with a moisture-proof heat-insulating heat-resistant elastic material, for example, isolon or foamed rubber. On the opposite side perform a longitudinal groove 3 to compensate for thermal expansion and stress relief during drying.

In assortment 1 (second option), mainly in a bar or log, on one side along the longitudinal axis and symmetrically relative to it, at least one slot 2 is made, in each of which a heat source is placed in the form of an electrically conductive heating element 5, after whereby the slot is filled with a moisture-proof heat-insulating heat-resistant elastic material. For a beam, slots 2 (Fig. 2) are performed with the following ratios: a = L / 2-L / 5, H / 4 <b <N / 2 and c = 2-15 mm, where L is the width of the beam, N is the height timber, a is the distance between the slots 2, b is the depth of the slot 2, c is the width of the slot 2, and for the logs of the slot 2 (Fig.3) is performed with the following ratios: a = D / 2-D / 5, D / 4 < b≤D / 2 and c = 2-15 mm, where: D is the diameter of the log, a is the distance between the slots 2, b is the depth of the slot 2, c is the width of the slot 2. On the opposite side, longitudinal grooves 3 are made to compensate for thermal expansion and stress relief during drying.

In assortment 1 (third option), mainly in a beam or log, on one side along the longitudinal axis and symmetrically relative to it, at least one slot 2 (Fig. 4) and one slot 4 between them are made on the opposite side of the timber or logs, in each of which a heat source is placed in the form of an electrically conductive heating element 5, after which the slot is filled with a moisture-proof heat-insulating heat-resistant elastic material. The depth of each slot does not reach a plane perpendicular to the slots and passing through the longitudinal axis of the beam or log, while in the beam of the slot 2 is performed with the following ratios: a = L / 2-L / 5, b <N / 2, b * <b, c = 2-15 mm, where L is the width of the beam, N is the height of the beam, a is the distance between the slots 2, b is the depth of the slots 2 on one side of the beam, b * is the depth of the slit 4 from the side opposite to the slots 2, c is the width of the slots 2 and 4, and for the log of the slot 2 is performed with the following ratios: a = D / 2-D / 5, b <D / 2, b * <b, c = 2-15 mm, where D is the diameter logs, and - the distance between n The Lake 2, b - the depth of the slots 2 from one side timber, b * - the depth of the slits 4 from the side opposite the side with the slots 2, with - the width of the slots 2 and 4.

In assortment 1 (the fourth option), along the longitudinal axis of the timber or log on one side and symmetrically on the opposite side, slots 2 are made, in each of which a heat source is placed in the form of an electrically conductive heating element 5, after which the slots 2 are filled with a moisture-proof heat-insulating heat-resistant elastic material. Slots 2 are made with a depth less than half the height of the beam or half the diameter of the log with a distance g between the inner ends of the slots 2 of at least 4 cm. On both sides of the beam or log with slots 2, longitudinal grooves 3 are made to compensate for thermal expansion and stress relief during drying.

The width of the slots 2 and 4 in the beam or in the log is set in the range c = 2-15 mm, while the slot of the minimum width is performed using 5 nichrome wire as the electric heating element, and the maximum width slot is used when using a heat-insulating element with insulation - TENA.

The predetermined depth range b and b * of the slots 2 and 4 in the timber or log and the predetermined range of the distance between them a and g in variants 2, 3 and 4, respectively, are determined experimentally from the condition of obtaining a uniform distribution of the final moisture content of the material over the cross section of the timber or log.

Drying is carried out at a temperature of an electrically conductive heating element of 90-150 ° C during the entire drying time at an ambient temperature of 30-50 ° C, a relative humidity of 60-70% and a blowing speed of 1-3 m / s until a residual wood moisture content of not more than 20 %, while in the drying process, thermal moisture treatment of timber or logs is carried out periodically for 1 hour at an ambient temperature of 90-95 ° C and a relative humidity of 95-100%.

When implementing this method of drying an assortment (timber or logs), the following occurs: when placing a heat source of an electrically conductive heating element 5 in the geometric center of the cross section of assortment 1 inside or near it, a single field is formed with the same directions of the temperature gradient, humidity gradient and pressure gradient of saturated water vapor. All three gradients are directed equally from the geometric center of the cross section of assortment 1 radially to the periphery, i.e. to the surface of assortment 1. Due to this, the rate of molecular movement of moisture from the center to the surface of assortment 1 increases several times in comparison with traditional drying methods, in which the directions of the temperature and humidity gradients are directed towards each other.

For example, a cylindrical assortment 1 was dried with a length of 4 meters and a diameter of 220 mm (pine) with an initial moisture content of 60-80%, which after drying for 3 days reached a moisture content of 20% on the surface and 7% in the central part of the cross section. With the help of the Termit-280U machine, slot 2 is milled in the direction from the edge of the log to the center with a width of c = 14 mm and a depth of b = 115 mm. On the opposite side of slot 2 (opposite it) using the same Termit-280U machine, groove 3, the so-called compensation groove, is used to reduce the number of cracks in the log. The log is placed in a conventional convection-type drying chamber and is installed with the slot 2 up. At the bottom of this slot 2, heat-electric heaters (TENs) connected in series (5 pcs. 1 meter, diameter 13 mm), operating from an alternating current network of 220 V, are installed, the power of each TENA is 1 kW. When connected to the network, they heat up in the temperature range from 90 to 150 ° C, depending on the heat transfer properties of the log, which depend, in particular, on the moisture content of the log. Slot 2 is sealed with a moisture-proof and at the same time heat-insulating material, for example, isolon or foamed rubber, which must be able to compress and expand depending on the change in the width of slot 2. The width of slot 2 at different stages of drying varies significantly, because depends on the length-changing properties of the log (knots, tar, initial humidity, etc.).

For drying assortments 1 (timber or logs) of large sections, it is most effective to use the second and third variants of the proposed method, in which the electrically conductive heating elements 5 are located around the geometric center of assortment 1 in two or more slots on one side of assortment 1 and / or in one or more the slots on the other side of assortment 1, due to which a more uniform distribution of the final moisture content of the material over the cross-section of the beam or log is achieved.

Electrically conductive heating elements 5 (nichrome wire or heat-insulated heating element - TEN), located in the center of assortment 1, are constantly on throughout the entire drying process. After the initial heating of the log for 2 hours at an air temperature in the drying chamber of 20-25 ° C, moist air (humidity 95-100%) is supplied to the drying chamber for 1 hour with closed ventilation valves, temperature 90-95 ° C and at a speed of blowing of 1-2 m / s. Then the air supply is stopped and within 2 hours drying is carried out only with the help of electric heating elements 5 and fully open ventilation dampers at the top and bottom of the drying chamber at an air temperature in this mode of 40-50 ° C. Then again, the supply of moist air with the above parameters for 1 hour is turned on, and the process is repeated. After 3 days from the start of drying, the electric heating elements 5 (heating elements) are turned off, the ventilation dampers open, and the logs cool down within 12-15 hours. For various materials (wood species, diameter, assortment size, etc.), the drying modes may differ by individual parameters. With this drying method, the central parts dry out and shrink earlier and to a greater extent than peripheral ones.

Due to this, cracks on the surface of assortments 1 are minimal in size and quantity, which was always difficult to achieve when drying logs and large-cross-section beams, since surface layers of materials usually dry first, and heat and moisture treatment with a significant thickness of the material is very energy-intensive, time-consuming and inefficient . After drying, the assortment (timber or logs) is kept indoors at a temperature of 20-25 ° C folded into a stack through gaskets with a distance between the assortments of 10-12 cm in conditioning mode for 7-8 days for relaxation and equalization of moisture over the cross section of the assortment.

Slots 2 and 4 along the longitudinal length of the assortment do not affect its quality. When using timber and logs dried in this way in construction as structural materials (for example, wall or beams, etc.), their bending strength in the vertical plane practically does not change with a vertical slot, the bending strength in the horizontal direction does not change much, and horizontal neither walls, nor beams are tested in the construction of the house. To eliminate the blowing of walls, technological slots 2 and 4 can be easily repaired using materials used to seal the interface of logs or timber (flax, tow, jute, etc.), or closed with wooden plugs of the appropriate section. These operations are possible both at the stage of factory production of wall materials and at the stage of construction of buildings from them.

After the drying process is completed, assortment 1 (timber or log) is milled (the geometric dimensions of the assortment deformed as a result of drying are adjusted, the slot is bored by 1-2 mm). An insert from the same wood species is inserted into the slots with a slight tightness on the glue. The result is a round, dry, rounded log. It makes technological grooves and holes for its assembly in the wall of the house, the log is ground, covered with antiseptics. A dry log packed in polyethylene can be stored in the warehouse as long as you want. The walls of the house made of dry material have minimal shrinkage (only 1%). In the house, you can start finishing work immediately after the installation of the log house, which reduces the construction time of the house from 1-2 years to 1-2 months.

Claims (22)

1. The method of drying wood, mainly beams or logs, including heating from the inside of the beams or logs, characterized in that along the longitudinal axis of the beams or logs, a slot is made in which a heat source is placed in the form of an electrically conductive heating element, after which the slot is filled with a moisture-proof heat-insulating heat-resistant elastic material. 2. The method according to claim 1, characterized in that the slot is performed in depth to or close to the geometric center of the cross section of the beam or log. 3. The method according to claim 1, characterized in that from the side opposite the side with a slot, longitudinal grooves are made to compensate for thermal expansion and stress relief during drying. 4. The method according to claim 1, characterized in that the drying is carried out at a temperature of an electrically conductive heating element of 90-150 ° C during the entire drying time at an ambient temperature of 30-50 ° C, relative humidity of 60-70% and a speed of blowing 1- 3 m / s until a residual moisture content of wood of not more than 20% is reached. 5. The method according to claim 1, characterized in that during the drying process, thermal moisture treatment of the timber or logs is carried out periodically for 1 hour at an ambient temperature of 90-95 ° C and a relative humidity of 95-100%. 6. The method of drying wood, mainly timber or logs, comprising heating from the inside of the timber or logs, characterized in that on one side of the timber or log along the longitudinal axis and symmetrically relative to it, at least one slot is made, in each of which is placed a heat source in the form of an electrically conductive heating element, after which the slots are filled with a moisture-proof heat-insulating heat-resistant elastic material. 7. The method according to claim 6, characterized in that the slots for the timber are performed with the following ratios a = L / 2-L / 5, H / 4 <b≤H / 2 and c = 2-3 mm, where L is the width timber, N - the height of the timber, a - the distance between the slots, b - the depth of the slot, c - the width of the slot. 8. The method according to claim 6, characterized in that for the logs of the slot is performed with the following ratios: a = D / 2-D / 5, D / 4 <b≤D / 2 and c = 2-15 mm, where D - the diameter of the log, a is the distance between the slots, b is the depth of the slot, c is the width of the slot. 9. The method according to claim 6, characterized in that from the side opposite to the side of the timber or logs with slots, longitudinal grooves are performed to compensate for thermal expansion and stress relief during drying. 10. The method according to claim 6, characterized in that the drying is carried out at a temperature of an electrically conductive heating element of 90-150 ° C during the entire drying time at an ambient temperature of 30-50 ° C, a relative humidity of 60-70% and at a speed of blowing 1 -3 m / s until the residual moisture content of wood is not more than 20%. 11. The method according to claim 6, characterized in that during the drying process, thermal moisture treatment of logs or timber is carried out periodically for 1 hour at an ambient temperature of 90-95 ° C and a relative humidity of 95-100%. 12. The method of drying wood, mainly timber or logs, comprising heating from the inside of the timber or logs, characterized in that on one side of the timber or log along the longitudinal axis and symmetrically relative to it, at least one slot and at least , one slot between them on the opposite side of the beam or log, in each of which a heat source is placed in the form of an electrically conductive heating element, after which the slot is filled with a moisture-proof heat-insulating heat-resistant elastic material. 13. The method according to p. 12, characterized in that the depth of each cut does not reach a plane perpendicular to the cuts and passing through the longitudinal axis of the beam or log. 14. The method according to p. 12, characterized in that for the slit beam is performed with the following ratios: a = L / 2-L / 5, b <H / 2, b * <b, c = 2-15 mm, where L is the width of the beam, N is the height of the beam, and is the distance between the slots, b is the depth of the slots on one side of the beam, b * is the depth of the slots from the side opposite to the slots with depth b, and c is the width of the slots b and b *. 15. The method according to p. 12, characterized in that for the logs of the slot is performed with the following ratios: a = D / 2-D / 5, b <D / 2, b * <b, c = 2-15 mm, where D is the diameter of the log, a is the distance between the slots, b is the depth of the slit on one side of the timber, b * is the depth of the slit from the side opposite to the slots with depth b, and c is the width of the slots b and b *. 16. The method according to p. 12, characterized in that the drying is carried out at a temperature of an electrically conductive heating element of 90-150 ° C during the entire drying time at an ambient temperature of 30-50 ° C, a relative humidity of 60-70% and a speed of blowing 1- 3 m / s until a residual moisture content of wood of not more than 20% is reached. 17. The method according to p. 12, characterized in that during the drying process, thermal moisture treatment of logs or timber is carried out periodically for 1 hour at an ambient temperature of 90-95 ° C and a relative humidity of 95-100%. 18. The method of drying wood, mainly timber or logs, comprising heating from the inside of a timber or logs, characterized in that along the longitudinal axis of the timber or logs on one side and symmetrically on the opposite side, cuts are made, in each of which a heat source in the form of an electrically conductive heating element, after which the slots are filled with a moisture-proof heat-insulating heat-resistant elastic material. 19. The method according to p. 18, characterized in that the depth of the slots is less than half the height of the beam or half the diameter of the log, and the distance between the inner ends of the slots is not less than 4 cm 20. The method according to p. 18, characterized in that on both sides of the timber or logs with slots perform longitudinal grooves to compensate for thermal expansion and stress relief during drying. 21. The method according to p. 18, characterized in that the drying is carried out at a temperature of an electrically conductive heating element of 90-150 ° C during the entire drying time at an ambient temperature of 30-50 ° C, relative humidity of 60-70% and a speed of blowing 1- 3 m / s until a residual moisture content of wood of not more than 20% is reached. 22. The method according to p. 18, characterized in that during the drying process periodically conduct thermal moisture treatment of timber or logs lasting 1 hour at an ambient temperature of 90-95 ° C and a relative humidity of 95-100%.

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