RU2362798C1 - Production method of wood granulae (pellets) - Google Patents

Abstract

FIELD: wood processing.

SUBSTANCE: production method of wood granulae is based on use of furnace dead matter from low-grade wood as raw materials. The method involves pushing raw materials through an extrusion-type, perforated matrix in form of a plate with three-step shaped openings, in which there is division of raw materials into different parts, compaction and shaping of material in form of wood pellets. Whole timber is used as raw material, extruded under pressure of a hydraulic press. The openings of the plate are at peaks of regular triangles. Division of wood takes place at different hexagons using a system of parabolic teeth, the peaks of which at the corners of hexagons on the working surface of the matrix. The wood is compacted in conical channels with taper angle of 20°, shaping - by pushing wood through cylindrical openings.

EFFECT: method of making wood granulae (pellets) allows for doing away with laborious and expensive operations for preparation, chopping and drying raw materials, which significantly lowers production costs.

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Description

The invention relates to methods for the manufacture of wood pellets (pellets) and can be used in the manufacture of fuel from solid wood.

A known method for the production of wood pellets (pellets) by granulating wood flour obtained from waste wood processing. Fuel granule: Russia, Belarus, Ukraine. Directory. St. Petersburg, 2007. The basis of granulation is the rolling of wood flour by press rollers through a rotating matrix of round or flat shape with cylindrical holes. Their total area is less than the area of the matrix with a loaded layer of raw materials, which provides high granulation pressure at temperatures up to 100 ° C due to friction of the particles of raw materials. The result is the compression and sintering of wood flour in the form of cylindrical granules (pellets). This alternative type of fuel with respect to hydrocarbons, taking into account environmental cleanliness, efficiency, renewability and the possibility of use in automated furnace plants, is of great importance for the energy sector.

The disadvantages of this method, including the preparation, grinding, drying of raw materials, followed by pressing and cooling the products, are its energy intensity and high cost. Moreover, wood pellets (pellets) often do not withstand the requirements for abrasion, the presence of impurities and binders. Biofuel Portal: www.wood-pellets.com.

Many technical solutions are known from the prior art, where solid wood is used as raw material, for example, a device for uniaxial pressing of dry wood blanks SU 236749, class. B27M 1/00, 1969. Here, with the help of a matrix and a punch, under the action of a press, the workpieces are deformed to a given shape with a calculated wood compaction. Such production is long-term, expensive and piece, because require drying, processing to size, preheating and holding the workpieces after pressing. The proposed method for producing wood pellets (pellets) from whole wood by extrusion is free from these disadvantages, i.e. forming products by extruding material through a matrix with holes of the corresponding section.

A known method of molding fuel pellets from dispersed combustible materials RU 2129588, class. C10L 9/00, 1999, including forcing the raw material through an extrusion perforated matrix in the form of platinum with three-stage holes in which the material is densified and shaped, according to most of the similar essential features, is taken as the closest analogue of the claimed invention.

The main disadvantage of the analogue is the presence on the input working surface of the matrix of solid areas in the form of curved triangles, where during the process of punching, material accumulates that clogs the working channels. This is the main reason for the heterogeneity of the granules thus obtained, their low mechanical and physical properties.

The proposed method for the production of wood pellets (pellets) is free from the above disadvantages. Separation of a solid wood mass into equal hexagonal prisms occurs on parabolic teeth, providing simultaneous and complete capture of wood. The process of compression is fundamentally different from the analogue in that there is no interlayer movement of the material, and there is a decrease in intercellular space with increasing density and strength of wood. In contrast to the analogue, in the cylindrical part of the working channels of the matrix there is no compaction and hardening of the material, and the excess pressure of the intercellular vapor is released and the granules are calibrated.

The aim of the invention is to improve the quality and lower costs for the production of whole wood pellets (pellets).

This goal is achieved by the fact that in the method of production of wood pellets (pellets), whole wood is used as raw material, extruded under pressure of a hydraulic press through a matrix in the form of a plate with holes of a three-stage shape, in which a continuous volume of wood is divided into equal parts, compaction and shaping of the material in the form of wood pellets (pellets). The division of whole wood into strictly equal parts of a prismatic shape occurs at the first step of the holes - the sharp edges of the parabolic teeth with vertices at the corners of the hexagons shown in figure 1. The wood is densified in the second part of the holes - conical channels - with a taper angle of 20 °, and the granules are shaped in the third, cylindrical surface of the working channels.

In the proposed production method, trunks of low-grade hardwood, such as aspen, poplar, birch, etc., after bucking, are pressed through the matrix under the force of the hydraulic press piston. In the process of punching, solid wood is divided into equal parts, compacted to a predetermined value and acquires a cylindrical shape of the desired diameter. The resulting wood pellets (pellets) are compacted wood, which at an extremely high calorific value equal to the calorific value of wood, have a natural ash content of wood, are free from harmful impurities and have high mechanical strength, which ensures compliance with quality standards.

The present invention is confirmed by the example of the production of birch wood pellets (pellets). This method is illustrated using the drawings:

figure 1 is a top view of the working surface of the extrusion matrix, which shows a triangular network of holes (dies) and hexagonal contours of the division of wood;

figure 2 - section of the matrix aa (figure 1), where in the conical channels of depth L there is a reduction of wood;

Figure 3 - section B-matrix of B (1) showing a form of teeth Z height, which is a division of wood, conical and cylindrical crimping channel opening diameter d, where e al Vecino binding takes form.

Birch churaks were pressed by a hydraulic press through an extrusion matrix, which is a plate with a thickness of H = 15 mm, perforated by a system of holes (dies) with a diameter of d = 6 mm, located at the vertices of regular triangles with a side of S = 8 mm and forming a single network (Fig. 1). This is not the only way to arrange the dies. The network can be formed by other regular-shaped polygons with holes in the corners or in their center. The thickness of the matrix has a three-stage shape, shown in sections aa and bb (Fig.2, 3).

Punching is as follows. At the first stage, the continuous massif of the tree is divided into equal hexagons (Fig. 1) using the first stage of the extrusion matrix having a three-stage shape shown in sections A-A and B-B (Figs. 2, 3). The first stage of the matrix is formed by a system of trihedral parabolic teeth with a height Z of 3.6 mm and vertices located at the corners of regular hexagons on the working surface of the matrix (Fig. 1). The whole wood pushed by the piston is cut by the edges of the teeth into regular hexagons (Fig. 1) without significant shearing forces, since the areas of cut and wood coincide.

At the second stage, the wood is densified in conical channels to a depth L of 9.3 mm and a taper angle of 20 ° (Figs. 2, 3). Moreover, the compaction coefficient, which determines the ratio of the densities of raw materials and wood pellets (pellets), in the above example is 0.51. The process of compression of wood occurs by reducing the intercellular space without interlayer movement of the material. Further, almost twice as compacted wood enters the cylindrical channels.

At the third stage, the wood is forced through the cylindrical holes with a diameter of d = 6 mm. Here the overpressure of the intercellular vapor is released and the granules are calibrated.

Below are the main characteristics of wood pellets (pellets) obtained from waste wood and solid birch churak.

Type of fuel Ash,% mass Sulfur,% mass Calorific value Beats the weight Briquette dust Connection mat. Waste Pellets up to 0.9 until 03 16-18 550-700 up to 2.3% up to 2% Pellets, whole 0.29 0,03 19.3 1000 0 0

A comparison of the characteristics given in the table proves the qualitative advantage of wood pellets (pellets) obtained from solid wood. The proposed method for the production of wood pellets (pellets) does not require significant costs for the preparation of raw materials (grinding, drying, steaming, etc.), which significantly reduces the cost of producing a qualitatively new type of fuel - whole wood pellets (pellets).

Claims (1)

A method for the production of wood pellets (pellets), including forcing the raw material through an extrusion perforated matrix in the form of a plate with three-stage holes, in which the raw material is divided into equal parts, compaction and shaping of the material in the form of wood pellets, characterized in that the raw material is solid wood extruded under the pressure of a hydraulic press, while the holes of the plate are located at the tops of regular triangles, the wood is divided into equal hexagons using a system of trihedral parabolic teeth, the vertices of which are located at the corners of regular hexagons on the working surface of the matrix, the wood is densified in conical channels with a taper angle of 20 °, and shaping is performed by forcing the wood through cylindrical holes.

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