RU2800946C1 - Fuel briquette and method for producing a fuel briquette - Google Patents

Abstract

FIELD: production of fuel briquettes based on charcoal.

SUBSTANCE: method for producing a fuel briquette is proposed, which consists in preparing a binder from starch and water, mixing the binder with crushed charcoal, forming and drying briquettes from the resulting briquette mass, characterized in that when preparing the binder, potassium chlorate or sodium chlorate is additionally added to it, or potassium perchlorate, or sodium perchlorate, borax, magnesium oxide or silicon oxide, the resulting mass is mixed with crushed charcoal with a fraction of not more than 2 mm in the following ratio, wt.%: charcoal - 49-53, starch - 2-3, borax - 0.1-0.15, potassium chlorate, or sodium chlorate, or potassium perchlorate, or sodium perchlorate - 0.25-1.0, magnesium oxide or silicon oxide - 0.15-0.5, water - the rest, then plasticization of the resulting briquette mass is carried out using a screw extruder, after which the briquette mass is reshaped by passing the briquette mass through the extruder with a die, while at the exit of the extruder in front of the die, the briquette mass is cooled, passed through the die, the briquette mass coming out of the holes of the die is cut into briquettes and dried in a drying chamber for at least 40 hours with gradual heating to a maximum temperature of 70-80° C and gradually cooled to 35-40° C and humidity of briquettes of 2-3%.

EFFECT: improving the quality of the resulting fuel briquette, in particular, an increase in the uniformity of combustion and completeness of burn-out, stability of the form during combustion, and a decrease in the formation of cracks.

3 cl, 1 tbl, 2 ex

Description

The invention relates to the production of fuel briquettes based on charcoal and can be used in hookahs, for heating tobacco products, and also for heating foodstuffs.

A fuel briquette is known according to the RF patent for utility model No. 43870, C10L 5/02, 2005, containing crushed charcoal - 65-75%, a binder in the form of starch in an amount of 2-5%, brewed with boiling water in an amount of 23-30%. Crushed charcoal with a fraction of 0.1-3.0 mm is loaded into the main mixer. The production method consists in that starch is loaded into the mixer for the binder and water heated to a boiling state is poured. The prepared binder in the form of boiled starch is fed into the main mixer, where the charcoal is mixed with a viscous binder. The resulting mixture is fed to pressing, which is carried out using a cylindrical mold. Compressed briquettes enter the drying cabinet, where they are dried for 12 hours at a temperature of 40-80 ℃.

The disadvantage of the known fuel briquettes is the low quality of the fuel briquettes. Mixing of fuel briquette components takes place in starch brewed with boiling water, i.e. in a viscous medium, which complicates the mixing of the mixture, reduces the uniformity of the briquette mass and ultimately leads to uneven combustion and incomplete burnout of the fuel briquette. In addition, the fast drying mode of the briquettes contributes to the formation of cracks and loss of shape of the briquette during combustion.

Known fuel briquette according to the RF patent for invention No. 2378325, C10L 5/10, 2010, including, wt.%: crushed charcoal with a particle size of about 0.1 mm - 92; binder in the form of starch - 6 and water - 2. The method of obtaining a fuel briquette is that crushed charcoal to a fraction of 0.05-5.0 mm and starch are mixed with water, thoroughly mixed with a stirrer at room temperature and kept up to starch swelling. The prepared mixture is briquetted using a hydraulic press and dried with forced air convection at a temperature of 120°C until the residual moisture content of the fuel briquette is less than 3%.

The disadvantage of the known fuel briquette is insufficiently high quality associated with a high content of solid fraction, a small amount of binder and its low properties, which leads to heterogeneity of the briquette mass and, as a result, to cracking, uneven and incomplete burning of the fuel briquette.

Known fuel briquette and method for its manufacture according to the RF patent for invention No. 2187542, C10L 5/10, 2002, selected by the totality of essential features as the closest analogue for the group of inventions. The fuel briquette contains, in wt.%: crushed charcoal -50-93, starch -3-45, water - the rest. The method for producing a fuel briquette consists in mixing pulverized crumbs of high-quality charcoal with a particle size distribution of 3-6 mm with a binder in the form of potato or corn starch and water, thoroughly mixing in a mixer until a homogeneous state, and keeping the binder for swelling. The resulting mixture is loaded into the extruder for pressing and shaping, the cords coming out of the extruder are cut into briquettes, then the briquettes are dried, bringing the humidity to the standard.

The disadvantage of the closest analogue is the insufficiently high quality of the fuel briquette due to the low properties of the binder composition, the drying mode, the use of a very large fraction of charcoal. All this reduces the uniformity and strength of the fuel briquette, the stability of its shape during combustion, leads to cracking and a large volume of non-burning areas in the volume of the briquette.

The technical result of the claimed invention is to improve the quality of the resulting fuel briquette, namely: increasing the uniformity of combustion and completeness of burning, stability of the form during combustion, reducing the formation of cracks.

The technical result is achieved by the fact that in the method for producing a fuel briquette, which consists in preparing a binder from starch and water, mixing the binder with crushed charcoal, forming and drying briquettes from the resulting briquette mass, according to the invention, when preparing the binder, potassium chlorate is additionally added to it, or sodium chlorate, or potassium perchlorate, or sodium perchlorate, borax, magnesium oxide or silicon oxide, the resulting mass is mixed with crushed charcoal with a fraction of not more than 2 mm, in the following ratio, wt.%: charcoal - 49-53, starch - 2-3, borax - 0.1-0.15, potassium chlorate, or sodium chlorate, or potassium perchlorate, or sodium perchlorate - 0.25-1.0, magnesium oxide or silicon oxide - 0.15-0 ,5, water - the rest, then plasticization of the resulting briquette mass is carried out using a screw extruder, after which the briquette mass is reshaped by passing the briquette mass through the extruder with a die, while at the exit from the extruder in front of the die the briquette mass is cooled, passed through the die coming out of the holes briquette mass is cut into briquettes and dried in a drying chamber for at least 40 hours with gradual heating to a maximum temperature of 70-80°C and gradual cooling to 35-40°C and achieving a moisture content of briquettes of 2-3%. In addition, heating of the briquettes in the drying chamber can be carried out at a rate of about 1°C per hour, and cooling at a rate of about 2°C per hour. In addition, with an increase in air humidity in the drying chamber above 60%, forced convection with warm dry air can be carried out.

The technical result is achieved due to the fact that the briquette mixture, in addition to mixing the components in the mixer, is subjected to additional mixing during double passage through the screw extruder for plasticizing the briquette mass and molding, which increases the uniformity of the briquette mass and contributes to an increase in the uniformity of combustion and more complete burnout of the briquette, and also reduces cracking. In the process of extrusion plasticization and extrusion molding, the moisture content of the output briquettes is reduced, which reduces the risk of cracking of the briquettes during drying. A long drying process of the resulting briquettes, at least 40 hours, with maximum heating to a temperature of 70-80°C, with gradual heating and cooling without temperature drops until the briquette moisture content reaches 2-3%, also helps to prevent cracking of the briquettes. Due to the fact that the fuel briquette, in addition to charcoal, starch and water, contains potassium chlorate, or sodium chlorate, or potassium perchlorate, or sodium perchlorate in the amount of 0.25-1.0 wt.h., improved combustion of the briquette mixture and the completeness of burnout of the briquette, since potassium chlorate, or sodium chlorate, or potassium perchlorate, or sodium perchlorate, during thermal decomposition, release oxygen, which is inside the volume of the fuel briquette and penetrates into those parts of the briquette that are inaccessible to atmospheric oxygen, for example, to the surface of the briquette in contact with the support. With a smaller amount of potassium chlorate, or sodium chlorate, or potassium perchlorate, or sodium perchlorate in the inventive composition of the fuel briquette, the volume of fireproof areas increases, and a larger amount is impractical. The borax contained in the fuel briquette (sodium tetraborate) in the amount of 0.1-0.15 wt.h. the final result affects the completeness of the burnout of the briquette. The fuel briquette may also contain metal chloride from the range: calcium, sodium, magnesium, lithium, barium, potassium, in the amount of 0.15-0.5 parts by weight, which also has some effect on the completeness of burnout and the burning rate of the briquette mass.

To obtain a fuel briquette, any known charcoal is used as a feedstock, mainly grade A according to GOST 7657-84. Charcoal is used with a fraction of not more than 2 mm. As a binder, potato starch is used, for example, according to GOST 53876-2010 or corn starch, for example, according to GOST 32159-2013. Sodium chlorate (NaClO ₃ ), GOST 12257-93, or potassium chlorate (KClO ₃ ), GOST 2713-74, or potassium perchlorate (KClO ₄ ), GOST 20490-75 or sodium perchlorate (NaClO ₄ ), GB standard are used as oxidizing agents /T23850-2009. Borax (sodium tetraborate Na ₂ BO ₄ ) is used to harden the briquette. GOST 8429-77. Magnesium oxide (MgO), GOST 4526-75, or silicon oxide (SiO), GOST 9428-73, are added to the briquette for decorative purposes, which are inert fillers that do not participate in combustion, but give the briquette and ash a light shade during combustion.

Fuel briquette is obtained as follows.

Charcoal is crushed in a crushing plant to a fraction of not more than 2 mm.

Prepare a binder. To do this, gradually add an appropriate amount of starch, borax, potassium or sodium chlorate or potassium or sodium perchlorate, magnesium oxide or silicon to a container with a calculated amount of water. The optimum water temperature is 30°C. Borax is added to the composition to increase the strength and maintain the shape of the briquette during combustion, which ensures more uniform combustion and more complete burnout of the briquette. To enhance the strength of the briquette in its composition, metal chloride from the series can also be used: calcium, potassium, sodium, magnesium, lithium, barium. Potassium or sodium chlorate or potassium or sodium perchlorate is used as the oxidizing agent. Potassium or sodium chlorate or perchlorate is used to better burn through the briquette, to reduce unburned areas in the volume of the briquette due to the lack of oxygen in these areas, which is necessary to maintain the combustion process. Potassium or sodium chlorate or perchlorate releases oxygen during thermal decomposition, which makes it possible to burn in the entire volume of the briquette without the appearance of unburned areas. Instead of these oxidizing agents, chlorate or perchlorate of a metal from the series: magnesium, lithium, barium, calcium can be used. Magnesium oxide or silicon oxide are used as substances that increase the decorative properties of the fuel briquette, which give the briquette and ash a light shade during the combustion of the briquette. The mixture is continuously stirred by any known mixing device, for example, a construction mixer until a homogeneous state.

Crushed charcoal in the estimated amount from the supply hopper is fed into the mixer. The calculated amount of the prepared binder is fed into the same mixer using a dosing pump. In the mixer, all components are mixed. The finished briquette mixture is sent for plasticization.

Plasticization of the briquette mixture is carried out in an extruder. The briquette mixture is fed into the extruder in equal portions. The composition passes through the extruder at a pressure of 190-200 kgf/cm ² . In this case, the composition is heated to a temperature of 60-75°C. Heating occurs spontaneously due to the friction of the material on the inner surfaces of the extruder and the particles of the mixture against each other. In the process of plasticization, under the influence of water, temperature and pressure, starch changes its properties, passes into a colloidal state. The particles of the composition are additionally crushed and mixed. The briquette mixture is homogenized and becomes more homogeneous.

Next, briquettes are molded, for which the second mixture is passed through an extruder equipped with a spinneret at the exit. The molding process is carried out under the same pressure characteristics as the plasticizing process. The temperature of the briquette mass is 40-50°C, since the friction of the plasticized briquette mixture against the walls and the extruder screw is less than the initial one. In the process of molding, the humidity of the briquette mass decreases and its homogeneity increases. The briquette mixture advanced by the extruder screw passes through the die. Before exiting through the die, the briquette mixture is cooled by any known means, for example, by external water cooling of the extruder body. Cooling the mixture is necessary to keep the shape of the briquette. The die has holes of the desired shape, such as square ones. From the die, the briquette mass in the form of continuous "cords" moves to a conveyor belt with automatic molding knives, where the briquette mass is cut into many briquettes, prismatic, cubic or other shape, depending on the shape of the holes in the die, for example, into cubes 22-25 mm in size.

Humidity of briquettes after molding and cutting is ~ 40%. Therefore, immediately after cutting, the resulting briquettes are dried in a drying chamber. To avoid the formation of cracks, drying of the briquettes is carried out with a gradual slow heating of the temperature to 70-80°C at a heating rate of ~1°C per 1 hour and the same gradual cooling at a rate of ~2°C per hour to a temperature of briquettes of about 40°C at humidity briquettes no more than 2-3%.

If during the drying process the air humidity in the drying chamber exceeds 60%, then forced supply of warm dry air is carried out to reduce the humidity to 40%.

The table shows examples of the composition of the fuel briquette

Table

Components of the briquette mixture Composition 1 Composition 2 Composition 3 Composition 4 Composition 5 Composition 6 Composition 7 Composition 8 Composition 9 Composition 10 Dry charcoal, wt.% 50 49 53 51 51 51 51 51 51 51 Potato starch, wt.% 2.5 2.0 3.0 2.5 2.5 2.5 2.5 2.5 - - Corn starch, wt. % - - - - - - - - 2.5 2.5 Borax, wt% 0.125 0.1 0.15 0.127 0.124 0.127 0.128 0.13 0.13 0.135 potassium chlorate - - - - - - 0.3 0.3 sodium chlorate - - - - - - - - 0.4 0.4 Potassium perchlorate 0.3 0.2 1.0 0.3 - - - - - - Sodium perchlorate - - - 0.3 0.3 - - - - magnesium oxide 0.3 0.25 0.5 - - 0.3 0.3 - 0.3 - silicon oxide - 0.3 0.3 0.3 0.3 Water Rest Rest Rest Rest Rest Rest Rest Rest Rest Rest

Example.

Charcoal grade A according to GOST 7657-84 was crushed in a crushing plant to a fraction of 1-2 mm. From the crushing plant, charcoal was dumped into a supply hopper. Water with a temperature of 30°C was poured into the container for preparing the binder. Potato starch according to GOST 53876-2010, borax according to GOST 8429-77, potassium perchlorate according to GOST 20490-75, and magnesium oxide according to GOST 4526-75 were gradually added to the water. All components were used in proportions corresponding to composition 1 from Table 1. The components were added to water in dry form with constant stirring with a construction mixer.

The binder with the help of a dosing pump and the charcoal with the help of a conveyor belt were fed into the mixer, from which the resulting mass was loaded in equal portions into the extruder for plasticization. The composition passed through the extruder at a pressure of 200 kgf/cm ² . During plasticization at the outlet of the extruder, the die disk was installed at a distance of 75 mm from the screw feather. At the outlet of the extruder, the plasticized mixture was collected in a container. From the container, the plasticized briquette mixture was re-loaded in equal portions into the extruder for molding. At the exit from the extruder in front of the die disk, the briquette mixture was cooled by external water cooling of the extruder body, then it was passed through the forming holes of the die. The briquette mass emerging from the die holes was cut into cubes with a side of 25 mm. The temperature of the obtained briquettes was 35°C, humidity - 40%. The briquettes were dried in an oven with periodic convection with warm dry air when the air humidity in the oven reached 60%. Briquettes were dried by gradual heating to 80°C at a heating rate of 1°C/hour, then to the initial temperature at a rate of 2°C/hour. After drying, the moisture content of the obtained briquettes was 2%.

The manufacturing technology of fuel briquettes with compositions 2-10 is similar to the above example. But fuel briquettes with compositions 7-10 were dried with gradual heating to a maximum temperature of 70°C with the same heating rate as in the above example. After drying, the moisture content of the resulting briquettes was about 3%.

The implementation of the technical result is confirmed by the experiments.

Test specimens were made in the form of cubes with a side of 25 mm with compositions 1-10 indicated in Table 1. Three samples of each composition were taken for testing.

The briquettes obtained by the claimed method were visually checked for cracks, then set on fire and checked for uniformity of combustion and stability of the shape during combustion, after combustion of the briquettes, the presence and volume of unburned areas were determined.

Tests of samples of fuel briquettes obtained by the claimed method showed that the combustion of all samples is uniform, all samples hold their shape well, unburned areas are mostly absent or present in a small volume, not more than 0.5-1% (samples with compositions 1 and 5) samples with composition 2 with a minimum amount of borax and potassium perchlorate, the volume of unburned areas is about 3%. However, this amount is insignificant and has little effect on the quality of the fuel briquette. The resulting samples do not crack. Some of the samples with compositions 1 and 2 have an insignificant number of cracks with a total area of 3 mm ² to 10 mm ² , respectively, which practically does not affect the quality of the fuel briquette.

Thus, the invention makes it possible to increase the homogeneity of the briquette mass, the uniformity of combustion and the stability of the shape of the briquettes during combustion, the completeness of its burning and reduce cracking, therefore, to improve the quality of fuel briquettes.

Claims (3)

1. A method for producing a fuel briquette, which consists in preparing a binder from starch and water, mixing the binder with crushed charcoal, forming and drying briquettes from the resulting briquette mass, characterized in that when preparing the binder, potassium chlorate or sodium chlorate is additionally added to it, or potassium perchlorate, or sodium perchlorate, borax, magnesium oxide or silicon oxide, the resulting mass is mixed with crushed charcoal with a fraction of not more than 2 mm in the following ratio, wt.%: charcoal - 49-53, starch - 2-3 , borax - 0.1-0.15, potassium chlorate, or sodium chlorate, or potassium perchlorate, or sodium perchlorate - 0.25-1.0, magnesium oxide or silicon oxide - 0.15-0.5, water - the rest, then plasticization of the resulting briquette mass is carried out using a screw extruder, after which the briquette mass is reshaped by passing the briquette mass through the extruder with a die, while at the exit of the extruder in front of the die, the briquette mass is cooled, passed through the die, the briquette mass coming out of the holes of the die is cut into briquettes and dried in a drying chamber for at least 40 hours with gradual heating to a maximum temperature of 70-80°C and gradual cooling to 35-40°C and achieving a moisture content of briquettes of 2-3%. 2. The method according to claim 1, characterized in that the heating of the briquettes in the drying chamber is carried out at a rate of about 1°C per hour, and cooling at a rate of about 2°C per hour. 3. The method according to claim 1, characterized in that when the air humidity in the drying chamber rises above 60%, forced convection with warm dry air is carried out.