OA11249A - Carbonization and briquetting of agricultural residues - Google Patents

Description

011249

The present invention relates to a method of manufacturing debriquettes used as fuel for the production of the energy ofomestic and industrial. This process is in the context of bioenergetics. Indeed, biomass or living mass, from plant waste, forest or agricultural residues, is a source of energy par excellence.

There are several processes for transforming this biomass for energy purposes:

By biodegradation, biogas can be obtained. The calorific value of biogas is quite high. For a gas with 70% methane per cubic meter, the calorific value can reach 6000 kcal / kg. The popularization of this fuel is, however, faced with a transportation problem.

Charcoal is the most used fuel in our country. It has a calorific value of the order of 7000 kcal / kg. But with the threat of deforestation, it is necessary to stop, if not limit, its production.

Densification briquetting is also a method of using biomass as a fuel. The calorific value of such a briquette can vary between 4300 and 4700 kcal / kg. Generally, by this process, the raw materials (agricultural or other residues) are collected, stored, cut if necessary, dried and mixed with one or more binders and then compressed into briquettes. The briquettes obtained by this process, however, retain green matter, a serious drawback especially for firing the wafers. In addition, briquettes obtained by densification release a lot of smoke that disturbs the user.

Another disadvantage results from the fact that the densified briquettes are not black unlike the charcoal commonly used by homeowners. Given the strong resistance to change found in the domestic sector, these drawbacks penalize the product and prevent it from constituting a valid substitute for charcoal. 40 Carbonization trials of raw materials have been attempted in several African countries. Some of these processes involve the carbonization of stems in whole form: shrubs, reeds, or others are collected, cut, dried and charred. Other processes then grind the carbonized materials to compress them into briquettes. Unfortunately, these briquettes can not keep their shape and crumble easily. These products, whole or crushed and compressed, thus obtained carbonization have the disadvantage of being unable to transport because too frail. In addition, the carbonization process is often poorly controlled: the products are too much or too little carbonized or are not carbonized homogeneously, which adversely affects the combustion of the product and reduces its calorific power.

The present invention overcomes all the disadvantages mentioned and allows the production of coal briquettes from any carbonizable plant residue. The briquettes obtained from the process are solid and resistant to shocks handling and transport. They are easy to ignite, their combustion is homogeneous and they emit little smoke. The invention relates to a process for the production of fuel briquettes which consists of carbonising the raw materials beforehand in order to obtain a substance composed essentially of carbon, cooling the carbonized residues, grinding them to make them more homogeneous, mixing them with a binder, compress them in molds of smooth surfaces to obtain briquettes which will then be dried. The invention differs from other processes of briquetting of residuscarbonized by prior carbonization, controlled and uniform raw materials, by the use of binders, by optimal compression of the mixture in molds and by drying of the finished product.

This process of manufacturing charcoal briquettes consists of several steps shown schematically at the end of the document (see technical drawings) and includes the following: 1. The carbonization of agricultural residues:

The principle of carbonization is based on the production of a solid containing mainly carbon with a few percentages (6 to 10%) of volatile matter in order to obtain a fuel that burns easily, without excessive clearance of smoke. The invention is characterized by the use of a carbonizer (Figure 1) provided with an air controller (1) to obtain the right degree of carbonization for each material used. It is also characterized by the possibility of charring not only woody materials but also any dry agricultural residues. These residues may include rice husks or straw, cotton, millet, sorghum or demai stalks, peanut or shea shell, typha, diga or wild rice (oryza longistaminata). The optimal degree of carbonization, aeration and filling of the carbonizer varies according to each material used. Carbonization is the first stage of manufacture. f

Figure 1: The residues are loaded from the top of the carbonization cylinder (2), then put to leu by the lower hatch (3). The two ends of the cylinder are then closed and the air controller (1) is adjusted to the required degree. The residues once charred are released by the opening hatch (3) and conveyed to the next stage on a conveyor (4). . 2, The cooling of carbonized residues:

The residues obtained from carbonization are, in view of their temperature, at the limit of the combustion. A gust of wind is enough for them to catch fire. Thus, it is necessary to let them cool in a closed container in this case, a cooling silo (Figure; 2). Cooling is the second step in the production chain.

Figure 2: The cooling silo is hermetically sealed until the carbonized materials have cooled. The time required for this operation depends on the residues used and the use of equipment or substance used to accelerate cooling. 011249 3 3. Grinding of carbonized residues:

The residues thus carbonized and cooled are milled with a hammer mill or other instrument (FIG. 3) in order to obtain charcoal powder. This operation is necessary because the briquetting (step 6) requires a homogeneous mixture of the products used in the confection. Residues of brown coal or lignite can also be used at this stage. The crushing is the object of the third stage of. the making of briquettes. Figure 3; The cooled carbonized materials are conveyed to the mill (6) by a conveyor (5). The residues, once crushed, turns into a fine and uniform powder, 4. The mixture:

The briquetting requires the addition of a binder (7) for bonding the particles of the powder. Molasses, cassava starch, potato starch or other binders may be used for this purpose. The mixing of the different components, the fourth step in the chain, is the most important phase of the briquette making process.

The proportion of the mixture varies according to the ingredients used and the targeted results (briquette more solid, less odorous etc.). The most commonly manufactured briquett consists of 500 grams of coal powder (single origin or mixture of coal powder of various residues) for 300 grams of binder (in this case, molasses) and 300 g; unites of water. Other proportions can also be used.

Mixing is carried out with a mixer or in a mixer (Figure 4). In the case of starch, it is also necessary to heat the assembly during the calibration process. Blending is the fourth step of the production line.

Figure 4: This mixer consists of a cylinder provided with a worm (S) for stirring homogeneously the coal powder,> 1 water and binder (7), all directly connected to the cylinder. S. Briquetting: The whole, coal powder, binder and water, is kneaded until it becomes a homogeneous mass. This homogeneous mass is then briquetted (FIG. 5) using molds placed in hydraulic presses or by means of a machine rotating two mold-packed wheels (11) or two compression-packed molders Ci). The dimensions and shape of the briquettes vary according to the molds used. The most common briquette is of "pillow" shape, weighs about 30 grams, is about 6 cm of lung, 1 cm wide and 2.5 cm high at the highest part (center). Briquettes of all shapes, sizes and weights can however be manufactured. The fifth stage of the production chain is the most mechanical part of production.

Figure 5: A feed system (10) located above the junction of the two mold halves drops the coal powder and the molds which compress the powder by joining. The compact masses (11) constituting the briquettes are released as a result of this compression and conveyed on a conveyor to the dryer.

Figure 5b: A brick-liner with molded wheels (14), compresses the powder in the molds (17) by means of a spring (15). The charcoal powder is fed by a funnel (16) located above the two wheelsgarnies briquette molds (14). This model of lighter activated by a pulley system (18) is powered by an electric motor (19) or diesel. 6. Drying:

The briquettes thus formed still contain a certain quantity of water. This moisture makes combustion difficult, they must be dried. Drying can be carried out using a drydryer in the case of small productions. In the case of an industrial unit, the dryer used (Figure 6) combines forced ventilation of hot air to reduce the required drying time. Drying is the seventh and last stage of manufacture.

Figure 6: The briquettes are conveyed in the dryer (12) by a convoyer. The dryer is provided with fans (13) forcing hot air over the briquettes. 011249 5

Product Description :

The briquette thus obtained is a light, black fuel with a continuous combustion point. The fuel thus manufactured has a heating value (PC) of 19638 kj / kg for deriz straw, 23996 kj / kg for peanut hull, 19948 kj / kg for millet stems 25750 kj / kg for ground stems. cotton. All combinations of raw materials are possible.

The calorific value of the briquette, in the case of straw is higher than that of the dry raw material which is 12600 kj / kg.

The calorific value thus determined is that of the dry fuel and therefore, like any fuel, depends on the degree of humidity of the latter.

The briquette burns until it is completely consumed, ie set in ashes. If necessary, it can be turned off for later use. This testifies to the compact manufacture of the book.

As mentioned above, the briquette can be of any shape, size or weight.

The briquette lights up like charcoal, with embers of paper, gasoline or other common method. Unlike coal, however, it is not necessary to ventilate the once-lit fuel. The ash mantle covering the briquette is less easily detached from the fuel and facilitates combustion.

The briquette is distinguished from North American briquettes by the composition of agricultural residues rather than wood. However, lignite as well as wood processing waste, sawdust chips, coal residues can also be recycled in the manufacture of this web.

Claims (5)

011249 6 Claims A method of making combustible briquettes from organic residues, including carbonization of organic residues, cooling of carbonaceous residues, grinding carbonized residues cooled to obtain coal powder which is. added with water and a binder and compressed into a densified fuel mass which is then dried. 2. The manufacturing method according to claim 1, characterized by the prior and optimal carbonization of the raw material using a controller provided with an air controller and a worm to deremute and aerate the raw material. 3. Manufacturing method according to claim 1, characterized bythe use of one or the other or any combination in any proportion of the following raw materials rather than by the exclusive use of the wood: rice straw, rice husk, rod cotton, millet stalk, desorgho stem, corn stalk, peanut shell, shea shell, typha, diga (oryzalongistaminata), sugar cane, bamboo, any wood processing residue (saw blade, chip, debris) coal, coal powder or other), lignite or any other vegetable or mineral matter. 4. The manufacturing method according to claim 1, characterized by adding to the carbonized raw materials a pure or added binder consisting of one or the other or any combination of the following materials as a binder. : molasses, cassava starch, maize, potato or any other source or any other organic or chemical source material that may be used to adhere the carbonaceous materials. 5. Manufacturing process according to claim 1, characterized bycompression of the carbonized raw material using hydraulic presses or using two wheels or compressor rollers each filled with half-molds for the production of briquettes round or shaped pillow whose weight varies between 20 and 40 grams.