Round timber drying method
FIELD: woodworking industry.
SUBSTANCE: drying method of round timber involves convective chamber drying, with that, prior to drying, the timber is subject to autoclave soaking with a 16-18% water solution of a mixture of ammonium nitrate and carbamide or ammonium nitrate and calcium nitrate, which are taken in the ratio of 1:1, and drying is performed before the timber reaches equilibrium humidity considering future operating conditions.
EFFECT: method allows eliminating the formation of shrinkage cracks, improving the appearance, providing stable timber dimensions during operation, thus increasing the service life of round timber materials.
2 dwg, 3 tbl
The invention relates to woodworking industry, namely to wooden house construction, and can be used in the manufacture of houses from round, including round, timber.
Wood is a hygroscopic material. The humidity always tends to equilibrium with the surrounding air. Currently building a house from raw logs. After that, they endure throughout the year to ensure that the moisture content decreased and reached a stable value, i.e., the wood is purchased in equilibrium with the surrounding air humidity. This ensures dimensional stability and shape. Only after that start to fine finish. Pre-dried round assortments to an equilibrium moisture content, which they acquire during operation, eliminates long exposures and allows you to immediately after construction to begin finishing operations.
The known method of drying of roundwood, based on wave microwave (RU # 2250428 C2 F26B 3/347. Drying method microwave energy of roundwood, ed. Gareev F. H., published 20.04.20050). Drying is done in a special chamber. The drying process is fast enough.
The disadvantages of this method is that when drying this way in round timber necessarily cracks, in addition, the drying process requires large W�expenses of electrical energy, the high cost and limited lifetime of the microwave equipment, high qualification requirements for maintenance personnel.
Closest to the claimed method is the convective drying method of roundwood (Artemenkov A. M., Cerenkov S. I. Analysis of the drying of roundwood // Technology and equipment of woodworking production: interuniversity collection of scientific works (anniversary edition). - SPb.: Spbgma, 2003. Pp. 170-174.) - the prototype. Drying is performed in special chambers, equipped with heat exchangers, fans and air conditioning pipes. During the drying process, depending on the breed, size assortments, the required temperature and humidity in the chamber.
The disadvantage of this method of drying of roundwood is that the drying process be sure to appear exterior radial shrinkage cracks. As a rule, formed a deep (to the core) and a few small cracks. This is due to the anisotropic shrinkage of wood. Shrinkage in the tangential direction in 1,5...2 times higher than in the radial (Ugolev B. N., Wood science with the basics of forest commodity. - M: MSFU 20001, p. 89, PL.15). In other words, annual layers of wood around the perimeter shrink in 1,5...2 times greater than the thickness. The emergence of crack compensates for various�e usushechnye deformations (I. V. Krechetov, Drying of wood. - M.: Lesn. prom th, 1980, p. 107, Fig.39K). The size of the cracks depends on the final moisture content of the wood. The lower the humidity, the more usushechnye deformation and therefore more cracks. Due to the operating parameters of the drying process can only prevent the appearance of fine cracks, as they are due to moisture stress due to uneven distribution of moisture in the cross section of the assortment in the process of drying. To eliminate the appearance of deep radial cracks is impossible, since it is predetermined by the properties of the wood. This occurs regardless of the drying method. Cracks reduce the service life of buildings and structures, because they absorbs moisture in the form of rain, snow, leading to rotting. In addition, deteriorating the appearance and increase heat loss.
The object of this invention is to eliminate the occurrence of cracks in round timber during drying and to further ensure the stable dimensions of wood in the process of operation.
The technical result is to increase the magnitude of the equilibrium moisture content of wood by 8-10% from an initial moisture content of natural wood, which eliminates the formation of shrinkage cracks in round forest products, thereby increasing the lifetime of roundwood and improved appearance.
Said technical result in the implementation of Fig�plants is achieved by before convective drying chamber of roundwood them are subjected to autoclave impregnation 16-18% aqueous solution of a mixture of substances ammonium nitrate and urea or ammonium nitrate and calcium nitrate, taken in the ratio 1:1, and drying is carried out until the wood is the desired equilibrium moisture content is subject to the conditions of future operation.
Impregnation of round timber before drying autoclave method aqueous solutions of a mixture of two substances that enhance the absorption, allows for 8...10% increase in the value of the equilibrium moisture content of wood, which results in the elimination of cracks in the wood.
Substances that increase the hygroscopicity of the wood, quite a lot. In particular, these include some drugs used to impregnate the wood with the purpose of increasing its biostability and reducing Flammability (Maximenko N. And. The equilibrium moisture content of wood depending on the nature and content of protective equipment // Nauch.-tech. Ref. sat Mechanical processing of wood. - M.: Was, 1979. - vol.1. Pp. 4 - 5). But the equilibrium moisture content when using these drugs increases within 4%. It is not enough to prevent cracking of round timber. Effect provide only solutions consisting of a mixture of components taken in the ratio 1:1:
NH4NO3(nitrate am�onium) + CO(NH 2)2(urea);
NH4NO3(ammonium nitrate) + Ca(NO3)2×4H2O (calcium nitrate).
The proposed method is characterized in that the substances that are injected into the wood during impregnation, decreases the value of the partial pressure of steam, so the equilibrium with the surrounding air occurs at higher moisture content of the wood. Treated timber does not need to be dried to a low moisture content, because during operation it attains a higher value of humidity. And the humidity value will be stable and will not fall. Thus, the impregnated wood are provided with constant size and shape in the process of operation, but with a higher humidity than the untreated. The higher the humidity the wood to which it is necessary to dry, the less shrinkage deformation. This eliminates the appearance of cracks in round forest products. In this case, provided a dimensionally stable wood in the process of operation, which is one of the main tasks of drying. If drying is not impregnated wood to a higher humidity, cracking will not occur. But in the process of exploitation of this wood will acquire a lower equilibrium moisture content and in any case will crack, but only in the finished products.
Fig.1 shows a cross section of the round assortment, misuse�tion by a known method; Fig 2 - the claimed method.
Method of drying of roundwood is as follows. Roundwood placed in an autoclave is carried out impregnation 16-18% aqueous solution of drugs that increase water absorption (NH4NO3(ammonium nitrate) + CO(NH2)2(urea) or preparations NH4NO3(ammonium nitrate) + Ca(NO3)2×4H2O (calcium nitrate), taken in the ratio 1:1. The mode of impregnation, pressure 0.4 MPa, the duration of 120 min, the solution temperature of 20°C. thereafter, they are placed in an oven where they are dried at 60°C and a relative humidity of 40% within 120-130 hours. The drying process is done until the wood equilibrium moisture content.
Examples of specific applications.
Example 1. (according to the method of the prototype). From round timber (breed - larch) cut out the pattern with a diameter of 120 mm, length 300 mm, initial moisture content of 45%. Then the sample was placed in an oven where it was dried at 60°C and a relative humidity of 40%. In the process of drying was recorded the current weight samples. The drying process is ended upon stabilization of the mass of the samples, indicating the achievement of a wood equilibrium moisture content. The drying duration was 118 h. then the sample was inherited from the kilns�, produced cooling and determining the final moisture content by the gravimetric method in accordance with GOST 16483.7-71. As a result, the final moisture content of the sample was 8%. The sample had a deep crack to the core (Fig.1).
Examples 2-5 is similar to example 1.
In table 1 the data of examples 2-5 (prototype), timber - larch, initial moisture level of 45%.
Example 6. (the proposed method).
From roundwood (breed - larch, humidity - 45%) cut out the pattern with a diameter of 120 mm, a length of 300 mm. then the sample was placed in an autoclave, where it was used for the impregnation of a 16% aqueous solution of a mixture of products of NH4NO3(ammonium nitrate) + CO(NH2)2(urea), taken in the ratio 1:1. The mode of impregnation, pressure 0.4 MPa, the duration of 120 min, the solution temperature of 20°C. the absorbance, calculated on the dry residue amounted to 30 kg/m3. Then the sample was placed in an oven where it was dried at 60°C and a relative humidity of 40%. In the process of drying was recorded, the current mass of the sample. The drying process is ended in the stabilization of the mass of the sample, indicating the achievement of a wood equilibrium moisture content. The drying duration was 123 h. then the sample was inherited from the drying chamber was made of chilled�e and the determination of the final moisture content by the gravimetric method in accordance with GOST 16483.7-71. As a result, the final moisture content of the sample was 18%. Cracks in the sample does not appear (Fig.2).
Examples 7 to 9 is similar to example 6. In examples 7-9 were used timber - larch, initial moisture level of 45%, the sample length of 300 mm. as a solution for impregnation was used an aqueous solution of a mixture of products of ammonium nitrate and urea, taken in the ratio 1:1, the concentration of the solution of 16-18%. The mode of impregnation, pressure 0.4 MPa, the duration of 120 min, temperature 20°C. the drying Mode: temperature 60°C, relative humidity 40%. The results are shown in table 2.
Examples 10-12 analogously to example 6, the timber - larch, initial moisture level of 45%, as a solution for impregnation of an aqueous solution of a mixture of products of NH4NO3(ammonium nitrate) + Ca(NO3)2×4H2O (calcium nitrate), taken in the ratio 1:1, the concentration of the solution of 16-18%. The mode of impregnation, pressure 0.4 MPa, the duration of 120 min, temperature 20°C. the drying Mode: temperature 60°C, relative humidity 40%. The results are shown in table 3.
The method allows to eliminate the occurrence of shrinkage cracks, to improve appearance, provide a dimensionally stable wood in the process of operation, thereby increasing the lifetime of roundwood way� increasing equilibrium moisture content of wood by 8-10% compared to natural wood.
Method of drying of roundwood, including convective drying chamber, characterized in that before drying the wood is subjected to autoclave impregnation 16-18% aqueous solution of a mixture of ammonium nitrate and urea or ammonium nitrate and calcium nitrate, taken in the ratio 1:1, and drying is carried out until the wood equilibrium moisture content with the circumstances of future exploitation.
FIELD: process engineering.
SUBSTANCE: invention relates to drying of aerated cotton to be used in construction. Drying process is implemented in drying chamber. Said chamber can accommodate several lots of this material. Heat carrier is fed at drying chamber outlet while gas is discharged at its inlet at drying. Drying is performed in steps. For this first lot of this material is place at chamber inlet, in first drying zone. Heat carrier is continuously fed towards heat isolation material with discharge of used gases from drying chamber inlet zone outside, into exhaust ventilation. After first step drying, dried lot is displaced in steps towards outlet. Another lot is placed to drying zone inlet to repeat the process if required.
EFFECT: non-polluting process due to intensive removal of formaldehyde.
3 cl, 1 dwg
SUBSTANCE: method involves application of waterborne paint onto inner surfaces and outer surfaces of a container and supply of heated air under pressure via an open side of the container for the purpose of, at least partial, drying of the paint on the inner surfaces and outer surfaces of the container. The system comprises a drying chamber and standard superchargers and heaters and can be installed in transportation premises.
EFFECT: reduced expenses or the possibility to rearrange the premises for existing drying chambers.
24 cl, 1 ex, 4 dwg
FIELD: woodworking industry.
SUBSTANCE: method of drying and thermo-wet processing of large-sized wood is carried out by removing the free moisture by alternating the stage of heating the wood and vacuuming, the stage of creating air pressure for 10-15 minutes, and when removing the inherent moisture the stage of warming wood is carried out by radiation-contact method, in the heating process the wood is exposed to saturated water steam with the temperature of 150-180°C, at the stage of vacuuming the pressure in the device is lowered by law
EFFECT: invention enables to carry out simultaneous drying and thermo-wet processing of high-moisture large-sized wood.
1 dwg, 1 tbl
SUBSTANCE: method of drying includes regeneration of drying agent, which consists in fact, that drying agent is supplied into drying chamber towards subject of drying, with further drying and re-supply into drying chamber. Drying of drying agent is performed in tube of gasodynamic temperature stratification.
EFFECT: increased energy efficiency of drying process.
SUBSTANCE: in the drying method of woods, and namely logs of natural moisture content by arranging the latter in the drying chamber with refractory spiral-shaped contours, logs are dried by heat treatment by supplying the heat to logs in the form of a flame flow through refractory spiral-shaped contours; at that, first, end parts of logs are heated, then, middle parts are heated, and after that, heating is performed throughout the log length.
EFFECT: improving quality and reducing the drying time.
FIELD: process engineering.
SUBSTANCE: proposed invention relates to drying before processing and packing. In the case of food product, drying aims at ruling out whatever contact between said product and bacteria or other microorganisms. In usual conditions, general sterility can hardly be ensured between contact of food material and dry air. Besides, drying unavoidably involves some losses of volatile components caused by increased drying temperature. Proposed method comprises steps whereat gaseous medium with superheated steam is fed into envelope 2, food material is fed there inside to dry it therein. Dried food material is removed from said envelope 2. Said process is controlled on the basis of data on gas temperature and content of steam inside said envelope. Extracted gas medium is condensed to extract volatile matter from condensate. Proposed device comprises envelope 2 to keep gaseous medium with superheated steam. Note here that said envelope has inlet 40 and outlet 42. Device includes also the means 100 to generate said medium with superheated steam, first means 30 to displace food material via inlet 40 inside envelope 2, second means 30 to displace material through outlet 42 from envelope 2, and steam discharge pipeline 120 extending from outlet 122 to condenser 124, blower 128 arranged in steam discharge pipeline 120. Note here that said blower is controlled by control units on the basis of data on gas temperature and content of steam inside said envelope. Extracted gas medium is condensed to extract volatile matter from condensate.
EFFECT: efficient and sterile drying.
29 cl, 3 dwg
SUBSTANCE: invention may be used for drying loose (disperse) materials in construction (for instance, cement drying), in production of construction materials (for instance, sand and dolomite in production of glass), in agriculture (for instance, grain drying), in food industry (for instance, for flour drying) and to dry industrial wastes (for instance, wood chips) and in other similar industries. In the method to dry loose materials in a flow moving inside a rotary inclined cylinder, in which the material together with the cylinder is heated inside the cylinder, at the same time the cylinder is heated from outside at the bottom by directed infrared radiation along its entire length, placing an infrared heater under the cylinder, and the loose material is heated with the heated inner surface of the cylinder in contact by convection of air heated with this surface inside the cylinder and radiation penetrating through the cylinder simultaneously, at the same time the cylinder is equipped with a device to vary an angle of inclination relatively to horizon and height relative to the base, and a flow of loose materials is formed by one or several such or identical cylinders with infrared heaters, placing them one after the other without gaps into a single line with an identical angle of inclination to the horizon, or one after the other in a single axial vertical plane with minimum gaps between them and different angles of inclination to the horizon, besides, cylinders are made from stainless steel comprising at least 18% of chrome, the external surface of the cylinder is coated with a heat-resistant organosilicic paint of black colour, and the ratio of the cylinder wall thickness to its external diameter is set by the ratio of 1 to 500, at the same time lengths of cylinders in the flow is set as two and (or) three metres.
EFFECT: method implementation makes it possible to simultaneously expand functional capabilities of loose materials drying, to considerably reduce energy intensity of drying process and to provide for environmental purity of heating in process of drying.
FIELD: woodworking industry.
SUBSTANCE: temperature of the drying agent according to dry-bulb thermometer during the entire drying process is kept constant in the range of 38°C to 108°C depending on the characteristics of the dried material, and the wet-bulb thermometer temperature is maintained below the dry-bulb thermometer temperature in the range from 0°C to 36°C, and changes stepwise in the direction of its decreasing, while dispersed hot water is fed to the chamber.
EFFECT: reduced drying time.
2 tbl, 2 dwg
FIELD: power engineering.
SUBSTANCE: wood in the form of a wood pack is placed into a drying chamber closed relative to the environment, and where the water-containing atmosphere with moist temperature, dry temperature and a related psychrometric difference are maintained with the help of an injected drying air sent via wood. To optimise power consumption in process of drying, the speed of supplied drying air is controlled depending on current moisture in the wood or by registration of lower water release from the wood; at the same time control of current moisture or start of water release drop is carried out by measurements performed in process of drying.
EFFECT: reduced energy intensity of the process.
10 cl, 1 dwg
FIELD: machine building.
SUBSTANCE: in particular, this invention relates to a convection drying device of simplified design to harden coatings applied onto an item. The invention also relates to versions of the method to harden a coating applied onto an item placed inside a drying chamber casing. According to the first version, a drying device comprises a casing (32) of a drying chamber with a conveyor passing through it to move an item via the drying chamber, a fan to supply compressed air into the casing (32) of the drying chamber, an air duct comprising the first element protruding into the casing (32) of the drying chamber, and the second element connected to the fan for compressed air supply from the fan into the casing (32) of the drying chamber, a burner arranged substantially between the first and the second elements to heat compressed air. Besides, the first element is made with many air outlet holes distributed along the casing (32) of the drying chamber to direct the heated air to the item. According to the invention, the fan is made as capable to supply air to the casing (32) of the drying chamber in the volume of less than 25 stand. cub. feet/min, per foot of the drying chamber casing length (139 norm. m3/hr per metre of the drying chamber casing length). According to the second version, a drying device to harden a coating applied onto an item moved through a drying chamber comprises a casing (32) of a drying chamber with a conveyor passing through it to move an item via the drying chamber, a fan to supply compressed air into the casing (32) of the drying chamber, an air duct comprising the first element protruding into the casing (32) of the drying chamber, and the second element connected to the fan for compressed air supply from the fan into the casing (32) of the drying chamber, a burner arranged substantially between the first and the second elements to heat compressed air, besides, the first element is made with many air outlet holes distributed along the casing (32) of the drying chamber to direct the heated air to the item. According to the invention, distribution of the heated compressed air via air outlet holes is carried out with the ratio of air flow speed to the volume flow of air making approximately from 150 to 650 feet-2 (approximately from 1584 to 6950 m-2). According to the first version, the method to harden a coating applied onto an item placed inside the drying chamber casing includes supplying compressed air to the casing (32) of the drying chamber, heating of the compressed air near the casing (32) of the drying chamber to produce heated compressed air and distribution of the heated compressed air in the inner space of the casing (32) of the drying chamber in points distanced from each other via air outlet holes. Besides, supply of compressed air to the casing (32) of the drying chamber is carried out in the volume of less than approximately 25 stand. cub. feet/min, per foot of the drying chamber casing length (139 norm. m3/hr per metre of the drying chamber casing length). According to the second version, the method to harden a coating applied onto an item placed inside the drying chamber casing includes supplying compressed air to the casing (32) of the drying chamber, heating of the compressed air near the casing (32) of the drying chamber to produce heated compressed air and distribution of the heated compressed air in the inner space of the casing (32) of the drying chamber in points distanced from each other via air outlet holes. Besides, distribution of the heated compressed air in the inner space of the casing (32) of the drying chamber in points distanced from each other is carried out with the ratio of air flow speed to the volume flow of air making approximately from 150 to 650 feet-2 (approximately from 1584 to 6950 m-2).
EFFECT: reduced power inputs.
36 cl, 7 dwg
SUBSTANCE: method includes treatment of coal extracted from coal deposits for opening of its splices with rock. At the same time the coal is placed in layers at the intermediate storage, arranged on the southern slope of a knoll (mountain, hill) or a pit heap, the site of which has an angle of inclination 10-25°, exposed in spring-autumn periods to solar radiation with the number of "thawing-freezing" cycles with transition of temperature via 0°C equal to at least 7. Besides, the thickness of the coal layers is taken on the basis of the calculation sufficient for daily heating-cooling, and after thermal processing the coal is shipped from the warehouse for subsequent demineralisation.
EFFECT: increased opening of coal splices with rock.
FIELD: heating, drying.
SUBSTANCE: invention refers to accelerated drying of different kinds and cross sections of timber by means of equipment providing moisture transfer by action of relatively high temperatures, moisture content and alternating-sign pressure. A method for timber drying in a chamber isolated from atmosphere involves heating of a drying agent by means of heating devices connected in upper part of a shell as per a parallel scheme to main pipelines, devices for heating and circulation of high-temperature liquid heat carrier, reversible fans and flow dividers, which provide flow and distribution of the drying agent along a pile through diffuser channels, each of which is symmetrical to rows of gaskets of the pile, moisture levelling along the timber cross section by a moistening system with further exposure, removal of the drying agent from the chamber to a condensation device and control of a technological process by means of pressure, temperature and humidity control devices. A new feature of the proposed invention is that timber heat treatment is performed by hot recirculating water till average temperature of 35-45°C is achieved, which softens it, equalises humidity and quickly unfreezes it during winter season, by filling the chamber to upper pile level by means of an additionally introduced pipeline circuit provided with possibility of water return or transfer to the next chamber, and the heating process is continued by a steam-and-air drying agent till evaporation temperature is 100 to 120°C, thus maintaining the pressure of up to 1000 mm Hg; with that, the steam-and-air drying agent is removed from timber depending on timber type by constant or periodic vacuum pulses with further vacuum treatment by a vacuum pump till the pressure in the drying chamber is 100 to 150 mm Hg.
EFFECT: drying by evaporation at alternating-sign pressures of 1000 to 100 mm Hg using constant or periodic vacuum pulses considerably accelerates moisture evaporation speed and provides fault-free drying at inconsiderable change of bending, tensile and compression strength.
FIELD: drying solid materials.
SUBSTANCE: method comprises preliminary continuous piecemeal treatment of lumber. The lumber is dried and/or defrosted by heating, the surface of the lumber is cleaned, and surface moisture is removed by step by means of squeezing , e.g., with the use of roller step mechanism.
EFFECT: reduced labor consumption.
4 cl, 5 dwg
FIELD: methods of drying woods.
SUBSTANCE: method can be used at woodworking factories, for example for making furniture. Method of drying is based upon step-by-step change in parameters of drying agent depending on humidity of woods. Timber is preliminary subject to boiling at atmospheric pressure in 15-17% solution of sodium chloride during 2,5-3,0 hours. Then timber is subject to convective drying at four-step increase of temperature from 40° to 60°C and simultaneous four-step reduction of relative humidity of drying agent till achieving value which provides preset final humidity of wood species. Drying agent can have temperature of 40° and relative humidity of 90% at first step, temperature of 50° and relative humidity of 85% at the second step, temperature of 60° and relative humidity of 80% at the third step and temperature of 66° and relative humidity of 50% at the fourth step.
EFFECT: improved quality of drying; reduced time of procedure.
2 cl, 1 tbl
FIELD: wood treatment.
SUBSTANCE: method comprises supplying live steam to the drying chamber, leveling humidity over the cross-section of timbers, and heating timbers. The operations are performed with the use of sectional looped air ducts, fans, distributors, air heaters, and deflectors which provide uniform distribution of the flow over the height and length of the timber pile. The flow of the live steam and saturated air-steam mixture is distributed in two stages: in diffusers mounted between the fans and air heaters and through deflectors at least at two levels over the height of the pile.
EFFECT: improved method of drying.
3 cl, 3 dwg
FIELD: process engineering.
SUBSTANCE: invention relates to woodworking, particularly, to lumber processing. Lumber is impregnated in sealed container with modifying solution, dried and heat treated. Blanks are heated and compacted by heaters to be heated to 200°C. Said blanks are compacted by thermal-compression insert increasing smoothly of compaction force from 0 to 30 MPa depending upon heating temperature. Heating and deformation of initial lumber are started with impregnation stage. Proposed device comprises tight housing (1) of autoclave equipped with means for degassing and modifying agent solution feed. Said autoclave housing accommodates the car (6) whereat plies of wood blanks (7) are separated by heating compactors consisting of heater (2), pressure plates (4) and 3D element composed by resilient thermal-compression insert (3). Top limiter plate (5) can be secured at both autoclave housing and car bearing struts. Said heater consists of heating plate with heaters arranged thereon. Said heaters and compactors are arranged in layers over the lumber stack height. Said thermal-compression inserts are made of resilient material reinforced perpendicularly that features high linear expansion factor arranged on both side of said heating plate. Moving pressure plates are secured at said inserts from above and below.
EFFECT: higher quality of modified lumber and simplified design.
5 cl, 1 tbl, 1 dwg