RU2507241C2 - Briquette based on pressed lignocellulose body saturated with liquid fuel - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: briquette consists of a pressed lignocellulose body, containing: (a) 60-90 wt % cuttings of grass stalks and (b) 10-40 wt % scutched lignocellulose binder with degree of scutching of 38-75°RS (Shopper-Rigler degrees), preferably 45 70°RS, (said percentages being expressed in dry weight relative the dry weight of the sum of (a) and (b)) and from fuel which is liquid at room temperature, having a flash point of 30-150°C, which saturates the pressed lignocellulose body, wherein said briquette has a substantially cylindrical shape and has a central smoke conduit with a star-shaped cross-section. The method of making the briquettes comprises the following steps: (1) mixing an aqueous suspension of lignocellulose binder (b) with cuttings of grass stalks (a) in such proportions that the ratio (per dry weight) of the lignocellulose binder (b) to the cuttings of the grass stalks (a) ranges from 10/90 to 40/60; (2) moulding the mixture obtained in a suitable unit of the mould (encircling part)-anti-mould (encircled part) type at temperature of 40-120°C at pressure of 3-12 bar, applied for 5-120 s; (3) removing the obtained pressed body from the press mould; and (4) saturating the pressed body removed from the press mould with fuel which is liquid at room temperature, having flash point of 30-150°C.

EFFECT: obtaining a solid fuel briquette with low weight and a shape which provides multiple points of ignition, concealed inside the central smoke conduit.

15 cl, 3 dwg

Description

The present invention relates to a briquette based on a compressed lignocellulosic material impregnated with liquid fuel of vegetable or animal origin, as well as to a method for manufacturing such a briquette and the use of such a briquette as fuel in portable or non-portable burners.

Fuel for burners, most preferably for portable burners, convenient for children or people to wear in crowds, must meet a large number of requirements, of which the following may be mentioned:

- high compactness and light weight,

- even combustion with a constant intensity flame during combustion,

- ease of ignition,

- low smoke emission,

- low formation of fly ash,

- high operational safety, most preferably due to the absence of compressed gaseous fuels.

Of course, as in many other areas, it would be desirable to be able to possess fuel that would not only meet all the above criteria, but come from renewable sources, i.e. not from fossil sources.

After lengthy research, the applicant was able to develop a fuel briquette that is solid at low weight and thanks to a new combination of solid lignocellulosic fuel and liquid fuel, as well as due to its geometry, which provides many ignition points covered inside the central chimney, it combines all the above advantages.

This briquette mainly consists of a compressed body of plant origin, impregnated with liquid fuel of plant or animal origin. The compressed body has a structure that is rigid and at the same time light and dense enough to ensure the mechanical strength of the briquette during its burning with the formation of a very limited amount of ash and while allowing the existence of sufficient space, due to which the spread of combustion occurs gradually and evenly.

In view of the foregoing, one of the objectives of the present invention is a briquette consisting essentially of

- from a compressed lignocellulosic body containing:

(a) from 60 to 90 weight. % trimmings of grass stems and

(b) from 10 to 40 weight. % trepidine lignocellulosic binder with a degree of fraying from 38 to 75 ° RS (degrees Schopper-Riegler), preferably from 45 to 70 ° RS,

where the percentages are expressed in dry weight relative to the dry weight of the sum (a) and (b), and

- from liquid fuel at room temperature, having a flash point of 30 to 150 ° C, impregnating a compressed lignocellulosic body,

moreover, the said briquette has a substantially cylindrical shape and has a central chimney with a star-shaped cross section.

Thus, the briquette according to the invention consists of two main components: a compressed body of plant origin and liquid fuel.

The compressed body, in turn, contains at least two components:

- the main component (a), formed by large scraps of grass stems and

- minor component (b) formed by a strongly battered lignocellulosic binder.

Component (a) can be obtained by dry grinding or crushing the grass stalks, also called “straw”, in a suitable mill or crusher. A hammer mill is preferably used. Fragments, or particles, forming said first component (a) are relatively large with an uneven size. Most of them have a length of several millimeters or even several centimeters.

Most preferably, the trimmings of the grass stems are preferably more than 60 weight. %, preferably more than 75 weight. % and, most preferably, more than 90 weight. % of fragments whose size is such that their larger size is from 3 to 20 mm, preferably from 5 to 15 mm. This, of course, does not exclude the presence of smaller, even very small particles, as well as the presence of much larger fragments or fibers.

In the compressed body of the present invention, these large straw fragments are interconnected using lignocellulosic fibers of the “binder”, or “lignocellulosic binder”.

Lignocellulose is a mixture of three types of natural water-insoluble polymers, most preferably cellulose, hemicellulose and lignin, present in different proportions depending on the origin of lignocellulose. Lignocellulose has a fibrous structure.

The lignocellulosic binder used in the present invention is obtained by flashing lignocellulosic materials. Friction is the mechanical processing of lignocellulosic material in the presence of water for the purpose of hydration, fibrillation or cutting of the fibers forming this material. Pulping is always used in the production of paper pulp.

The method commonly used to assess the amount of scrubbing or the degree of scuffing of lignocellulosic material is the Schopper-Riegler test (standard ISO 5267/1). It allows you to measure the draining ability of the material subjected to the scuffing operation. The more disheveled the material, the more individual its fibers are individualized, hydrated and shortened, and the more the material will retain water. Strongly battered material, respectively, has a low drainage ability and a high degree of scuffing according to Shopper-Riegler.

The lignocellulosic binder used in the present invention should have a Schopper-Riegler number of at least 38 ° SR, preferably 42 ° SR and, ideally, 45 ° SR.

The lignocellulosic binder used in the present invention can be obtained in principle from any woody plant material suitable for the use of lignocellulosic materials, including, naturally (but not limited to) herbal stems used for component (a). Along with these grass stalks, you can use, for example, wood shavings, hemp, and paper waste.

The beating process, which allows the production of a lignocellulosic binder (b), is described in detail in patent EP 0877646. At the end of this process, the battered lignocellulosic binder (b) takes the form of a pulp with a water content of from about 40 to 70% or, in other words, with a solids content from 30 to 60 weight. %, preferably from 35 to 55 weight. %

Trimming grass straws forming component (a) can, in principle, be trimming any herbs that have woody stems. Examples of such herbs include sugarcane, cereals such as maize, rice, wheat, barley, oats, rye and millet, bamboo and miscanthus.

A particularly preferred plant for the present invention is Miscanthus giganteus, a hybrid species obtained by crossing Miscanthus sinensis and Miscanthus sacchariflorus. More specifically, this plant is notable for its productivity, high lignocellulose content and low environmental impact due to, most preferably, its low water demand and the absence of depletion of the soil on which it grows, which, as a rule, makes fertilizer use unnecessary.

Miscanthus giganteus can be used as a source of scraps of grass stems of component (a) or as a source of lignocellulosic binder (b), or both simultaneously.

In one particularly preferred embodiment, component (a) and lignocellulosic binder (b) are obtained in part, and preferably in whole, from the stems of Miscanthus giganteus.

Before mixing them, components (a) and (b), or at least one of them, are first converted to a suspension in water. The amount of added water is preferably from 40 to 90% and preferably from 50 to 80% of the total dry weight (a) and (b).

In one preferred embodiment, 40 to 80 weight is added to component (a) before it is mixed with component (b). % water.

In one of the preferred embodiments, the compressed body along with components (a) and (b) of plant origin contains a mineral component (c) containing an alkali metal, the main role of which is to enhance the binding force of component (b). For example, it can be calcium oxide (CaO), also called quicklime, sodium hydroxide, potassium hydroxide or sodium carbonate. Calcium oxide is particularly preferred.

In case of its use, said component (c) is preferably contained in a proportion of 2 to 15 weight. %, most preferably in a proportion of 3 to 8 weight. % of the total dry weight of components (a) and (b). Calcium oxide can be added to either one or both of components (a) and (b) before mixing, or to an aqueous mixture of components (a) and (b) before the molding operation. Preferably, it is added to component (b).

After that, an aqueous suspension of components (a) and (b) and, possibly, (c) is formed at high temperature under pressure according to the method described in detail below.

The resulting compressed body, having lost most of its water content, is then impregnated with liquid fuel at room temperature. Impregnation of a compressed body does not require complete preliminary drying. During the impregnation, this compressed body may contain water in an amount of 5 to 20 weight. %

Fuel should not be too volatile, which is the case with liquids with a flash point above 30 ° C.

The flash point of the liquid fuel is preferably from 40 to 120 ° C., Most preferably from 50 to 70 ° C.

Liquid fuels can be vegetable oils such as microalgae oil, Pongamia pinnata oil (or karanja oil), linseed oil, jatropha oil, palm oil, sunflower oil, canola oil, almond oil, peanut oil, coconut oil, maize oil, olive oil or castor oil, animal oil such as whale oil, spermaceti oil, cod liver oil, beef tallow or beef fat, lard or pork fat, alkyl ester of such a vegetable or animal oil, or a mixture of these substances.

In one preferred embodiment, the liquid fuel is an alkyl ester, preferably a methyl ester of some vegetable oil, most preferably a coconut ester.

The compressed lignocellulosic body obtained by hot pressing has a density of preferably from 0.20 to 0.85 g / cm ³ , most preferably from 0.30 to 0.70 g / cm ³ .

This compressed body can be impregnated with liquid fuel using various known methods, such as immersion coating, vacuum immersion coating or spraying. Depending on the method of impregnation used, the operation of fuel penetration and / or drainage may be necessary in order to remove excess liquid and ensure uniform distribution of liquid fuel in the volume of the compressed body.

The amount of fuel introduced into the compressed body can be controlled by changing, for example, the time the pressed body is immersed in the fuel bath or the temperature of the immersion bath and the penetration of fuel into the core of the pressed body is even easier if its viscosity is low. It is also possible to cause fuel to enter the compressed body under pressure.

The Applicant has found that a compressed body is capable, as a rule, of absorbing fuel in an amount up to its own weight. However, in some cases it may be advantageous not to saturate the compressed body with liquid fuel and remain well below full impregnation. The applicant has obtained good results with regard to combustion efficiency with a weight ratio of liquid fuel to compressed lignocellulosic body from 3/10 to 10/10, preferably from 5/10 to 9/10, and most preferably from 6/10 to 9 / 10.

Another objective of the present invention is a method of manufacturing a briquette described in the present description. This method includes the following sequential steps:

(1) mixing the aqueous suspension of the lignocellulosic binder (b) with the crop stalks (a) in such a proportion that the ratio (on dry weight) of the lignocellulosic binder (b) to the crop stalks (a) is from 10/90 to 40/60 ;

(2) molding a mixture obtained in a suitable aggregate of the form type (female part) - anti-mold (male part) at a temperature of 40 to 120 ° C. under a pressure of 3 to 12 bar applied over a period of 5 to 120 s;

(3) extracting the obtained compressed body from the mold; and

(4) the impregnation of the extracted body from the compression mold with liquid fuel at room temperature having a flash point of from 30 to 150 ° C.

Stage (1) of mixing the two components (a) and (b) is preferably carried out in a mixer with sigma-shaped blades to obtain a homogeneous suspension in which the straw fragments are uniformly coated with a binder. Obtaining a homogeneous composition usually takes from 5 to 30 minutes.

This composition may certainly also contain a mineral component containing an alkali metal (optional component (c)) added before or after mixing components (a) and (b).

The ready-to-mold composition is fibrous and soft. It requires manual or automated mold filling through a funnel or through a vacuum filling system.

The mold consists of a male part and a female part. The female part placed at the bottom is a hollow cylinder, in the center of which a continuous section is placed having a star-shaped cross section. The male part has a shape complementary to the female part or, in other words, it is a continuous cylinder with a recess in its center corresponding to the star-shaped section of the female template. 2 is a photograph showing complementarity between the male part (left) and the female part (right).

The composition to be molded is introduced into the female part in a space bounded by the inner wall of the cylinder and the section. After filling the female part, the male template is gradually introduced into the female template using a thermal press.

The temperature of the mold as a whole (male and female parts) is brought to the molding temperature using a thermal press. This temperature, preferably in the range from 60 to 100 ° C, most preferably from 65 to 95 ° C, as well as the pressure developed, allow the binding force of component (b) to be activated in the composition. At the end of the hot pressing operation, the male template is lifted by means of pistons, thereby releasing the resulting briquette during double movement. The briquette is left for a period of 1 to 30 minutes in the open air for the purpose of spontaneous evaporation of a large part of the water.

After this drying step, the compressed body can be directly impregnated with liquid fuel.

The geometry of the solid cylinder of the enclosing part, as is easy to understand, directly determines the geometry of the central chimney. According to one preferred embodiment, the latter is in the form of a star having at least three rays, preferably from 4 to 20 rays and, most preferably, from 5 to 10 rays. The expression “star-shaped” also encompasses variants in which the tips and / or cavities of the rays of the star are rounded. The rounded shape of the tips of the star proved to be especially advantageous due to the ease of extraction from the mold while limiting the fiber detachment during the lifting of the briquette along the enclosing part.

The voids between the rays of the star are preferably not rounded. Indeed, these voids form after removing from the mold the tips of the elements that protrude from the wall in the direction of the center of the flue of the briquette. These tips form many ignition points and it is easy to understand that the ignition of briquettes is even easier when the tips of the protruding elements are narrow and pointed.

The advantage of the star shape of the central chimney is triple. Firstly, as noted above, the tips of the elements that protrude inside the central flue of the briquette and provide a very easy ignition. The second advantage, which directly follows from the first, is that the combustion surface is located inside the briquette and thus occupies a sheltered position protected by the briquette itself. Finally, the shape of the star creates a combustion surface, which remains largely constant during the combustion process, since a gradual decrease in the combustion surface due to the flow of protruding elements is compensated by a gradual increase in the diameter of the internal chimney as combustion proceeds. This change is illustrated in figure 1, which gives a schematic representation of the cross section of a briquette according to the invention. Different lines 1, 2, 3, and 4 show the combustion surface in successive stages of combustion.

The size of the briquettes can be freely selected depending on the intended application. The briquette height can be, for example, from 5 to 50 cm, and its outer diameter from 3 to 20 cm. If used as a solid fuel for portable burners, the briquette height is usually from 8 to 20 cm, and the outer diameter from 4 to 10 cm.

The ratio of the height of the cylindrical briquette to its outer diameter is preferably from 0.5 to 5, preferably from 1 to 4, and most preferably from 1.5 to 3.

In FIG. 3 (a) shows the compressed body before impregnation, and in FIG. 3 (b) is a batch of impregnated briquettes according to the present invention, in which the ratio of height to outer diameter is approximately 2.

The impregnation of the compressed body with liquid fuel preferably occurs when the compressed body is completely immersed in liquid fuel for a period of 2 to 60 seconds, preferably 10 to 40 seconds. After this dive, as a rule, a drainage stage follows. A drainage time of 15 seconds to 5 minutes is usually sufficient to remove all excess liquid fuel.

When used as fuel for burners, briquettes are placed in a hard case that is resistant to high temperatures. This case facilitates the handling and transportation of briquettes, protecting them from mechanical shocks that could damage them. The case also prevents the burning surface from approaching the burning surface to the outer cylindrical wall of the briquette.

To prevent evaporation of liquid fuel or its transfer to surfaces that are in contact with the impregnated briquette, the briquettes are preferably packaged in leak-proof bags or containers.

Finally, another objective of the invention is the use of this briquette as fuel in burners used for kindling or for generating heat, preferably for cooking or heating food.

Claims (15)

1. A briquette consisting of a compressed lignocellulosic body containing: (a) from 60 to 90 wt.% Scraps of grass stalks and (b) from 10 to 40 wt.% Of trepidated lignocellulosic binder with a degree of fraying from 38 to 75 ° RS (degrees Schopper-Riegler), preferably from 45 to 70 ° RS, (these percentages are expressed in dry weight relative to the dry weight of the sum (a) and (b)) and from liquid fuel at room temperature having a flash point of 30 to 150 ° C, impregnated compressed lignocellulosic body, wherein said briquette has an essentially cylindrical shaped and has a central chimney with a star-shaped cross section. 2. The briquette according to claim 1, in which the trimmings of grass stems consist of more than 60 wt.%, Preferably more than 75 wt.% And, most preferably, more than 90 wt.% Of fragments whose size is such that their larger size is from 3 to 20 mm, preferably 5 to 15 mm. 3. The briquette according to claim 1, in which the grass stems are the stems of Miscanthus giganteus. 4. The briquette according to claim 1, in which the compressed body further comprises from 2 to 15 wt.%, Preferably from 3 to 8 wt.%, Calculated on the dry weight of (a) and (b) a mineral component containing an alkali metal, ( component (c)), preferably calcium oxide. 5. The briquette according to claim 1, in which the central chimney has a star-shaped cross section, where the star has at least 3 rays, preferably from 4 to 20 rays and, most preferably, from 5 to 10 rays. 6. The briquette according to claim 1, in which the liquid fuel has a flash point of from 40 to 120 ° C., Most preferably from 50 to 70 ° C. 7. The briquette according to claim 1, in which the liquid fuel is a vegetable or animal oil, an alkyl ester of a vegetable or animal oil, or a mixture thereof. 8. The briquette according to claim 1, in which the liquid fuel is an alkyl ester of coconut oil. 9. The briquette according to claim 1, in which the trimmings (a) of the grass stalks are trimmed stalks of cereals or Miscanthus, preferably the trimmed stalks of Miscanthus giganteus. 10. The briquette according to claim 1, in which the density of one compressed body is from 0.20 to 0.85 g / cm ³ . 11. The briquette according to claim 1, in which the weight ratio of liquid fuel to the compressed body lies from 3/10 to 10/10, preferably from 5/10 to 9/10, and most preferably from 6/10 to 9/10. 12. The briquette according to claim 1, in which the ratio of the height of the cylindrical briquette to its diameter is from 0.5 to 5, preferably from 1 to 4, and most preferably from 1.5 to 3. 13. The method of manufacturing briquettes according to claim 1, comprising the following successive steps: (1) mixing an aqueous suspension of lignocellulosic binder (b) with crop scraps (a) in such proportions that the ratio (on dry weight) of lignocellulosic binder (b) to trimmings of the grass stem (a) lies from 10/90 to 40/60; (2) molding a mixture obtained in a suitable aggregate of the form type (female part) - anti-mold (male part) at a temperature of 40 to 120 ° C. under a pressure of 3 to 12 bar applied over a period of 5 to 120 s; (3) extracting the obtained compressed body from the mold; and (4) impregnating the extracted body from the compression mold with liquid fuel at room temperature having a flash point of from 30 to 150 ° C. 14. The method according to item 13, in which the impregnation of the compressed body with liquid fuel is carried out by completely immersing the compressed body in liquid fuel for a period of 2 to 60 seconds, followed by the stage of drainage. 15. The use of the briquette according to any one of claims 1 to 12 as fuel in burners used for kindling or for generating heat, preferably for cooking or heating food.

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