RU2268914C2 - Fuel briquette - Google Patents

Abstract

FIELD: production of coal-containing fuel; preparation of briquettes (granules) for furnace units of minor and medium heat power engineering.

SUBSTANCE: fuel (briquette, granule) contains 47.5-52.5% of culm, 28.5-31.5% of coal screenings and 19-21% of sawdust. Fuel thus produced is cheaper than similar fuels due to utilization of coal output wastes and wood-working process wastes without binding materials; fuel possesses high heat of combustion of coal; slag forming is excluded; finely-dispersed ash may be used as mineral fertilizer.

EFFECT: enhanced efficiency.

Description

The invention relates to the field of carbon-containing fuel, in particular, to composite fuel formed from industrial waste:

- a mine - waste generated during coal mining and enrichment by the flotation method (a mixture of rock and fine coal dust);

- screening - waste generated in the process of separation of the commodity fraction of coal;

- wood sawdust - which is a waste of wood processing industries (instead of sawdust, any waste wood in a crushed form can be used).

The specified type of fuel in the form of a briquette (or pellets) is intended for domestic furnaces, furnaces of railway cars, boiler houses for household purposes, related to small and medium heat power engineering.

Composite fuel, as a rule, is a product in the form of a briquette of the correct geometric shape (rectangular) or in the form of cylindrical granules obtained by force (molding, pressing) a mixture of initial components that have undergone preliminary preparation.

The main parameters characterizing the quality of composite fuel include:

- calorific value

- humidity

- moisture absorption

- ash content

- density

- compressive strength,

- crumbling,

- fractional composition,

- content of toxic components.

A distinctive feature of composite fuel from natural fuel is guaranteed physicochemical characteristics, a uniform fractional composition, which ensures a stable, required mode of furnace units.

Composite fuel production technology provides the ability to control the required characteristics by changing the percentage of components used.

Existing technologies provide for the special preparation of the components used to ensure the optimum guaranteed low humidity.

In the production by pressing, the increased humidity of the components, as well as the weak adhesive effect of the compositions used, leads to a decrease in the strength characteristics of the composite fuel during storage.

Known fuel briquette, including crushed coal, crushed peat and cellulose nitrate in the following ratio of components, wt.%:

brown coal 27.5-32.5 peat 27.5-32.5 cellulose nitrate the rest is up to 100% of the mass of the briquette

With the specified composition of the components, a sufficiently high calorific value and strength are achieved, low ash content with a long combustion time, necessary to achieve the most efficient use of briquettes in the direct combustion method (see RF patent No. 2091446 with priority dated April 22, 1994).

The disadvantages of this briquette are:

- the use as a binder of cellulose nitrate, which is a purchased, imported component containing sulfur compounds, i.e. toxic substances;

- the use of enriched commercial coal, which must be crushed to prepare the composite mixture;

- low percentage of coal;

- the use of peat, deposits of which are not always found near the places of accumulation of coal mining waste (coal processing enterprises).

The combination of these disadvantages leads to a significant increase in the cost of fuel and to a decrease in quality indicators.

Also known is a fuel briquette containing components in the following ratio, wt.%:

peat 10-20 sawdust 5-10 organic binder 2-10 coal rest

A feature of this briquette is the use of pulp and paper and oil refining industry as an organic binder (for example, sulphite-distillery stillage, lignin, fibrous cellulose residues, residues of fuel oil, bitumen, etc.), as well as the presence of through holes of various diameters in the briquette (see RF patent No. 2119532 with priority of July 20, 1994).

The content of coal in the composition of this briquette is from 55 to 80%, and coal waste can be used (including high-ash waste in the form of slags, pits, and low-quality coals with grinding sizes up to 3 mm).

However, the presence of additional components in the form of peat, which requires special preparation, an organic binder, an oxidizing agent (nitric acid salt), as well as the need for heat treatment of the briquette at a temperature of 300-350 ° C for 1.0-3.0 hours, complicates the process , the amount of necessary equipment, which leads to a rise in the cost of the final product, which is not comparable with the achieved quality indicators.

The specified technical solution as the closest analogue can be taken as a prototype.

The tasks to which the proposed technical solution is directed are:

1. The ability to create composite fuels based on technogenic coal concentration wastes (pits, screenings) using the binder properties of natural minerals that make up the pits.

2. The possibility of developing the production of composite, environmentally friendly, high-quality types of fuels with the required parameters from various types of industrial waste on an industrial scale, as alternative types of fuel.

3. Rational utilization of waste from enrichment plants in the coal mining industry (shafts, screenings, dust from cyclones, etc.).

4. Increasing the profitability of coal mining enterprises in the framework of the widespread restructuring of the industry by creating new industries based on high-tech, environmentally friendly technologies to ensure employment of mining cities in connection with the closure of a number of mines.

5. The solution of regional problems in the fuel and energy complex by developing the production of composite fuel based on local industrial wastes in the context of solving economic, social problems and ensuring environmental safety.

Currently, there is a huge amount of coal-containing waste in the areas of coal processing plants in the form of lumps, sludge from sedimentation tanks after flotation of coal.

These wastes occupy vast territories, lie unused, due to wind erosion pollute the atmosphere and nearby land coverings, as well as water bodies, for which the guilty enterprises pay fines.

According to forecasts of the Union of Coal Industrialists, coal production in the Russian Federation should increase sharply. So, in 2000, 260 million tons of coal were produced, and by 2015 it is expected to increase production to 450 million tons (see UGOL magazine No. 2 for 2001, p. 19).

The need to develop coal production is also determined by the balance of prices for oil, oil products, gas taking shape on the world market, taking into account the reserves of explored deposits and political considerations.

Today, selling gas and oil on the foreign market is much more profitable than on the domestic one. According to the estimates of foreign and Russian experts, world-known oil and gas reserves at current production rates will last for a maximum of 50 years, coal will last for 500 years.

Therefore, literally in 10-15 years, when humanity will be faced with a shortage of oil and gas (and, consequently, with an unprecedented rise in prices for them), coal will become the cheapest type of fuel.

An increase in coal production will lead to an increase in waste, therefore, the disposal of coal-containing enrichment waste will become even more urgent.

According to the invention proposed in the application, the tasks are solved by a new composition of composite fuel, developed on the basis of using the binding properties of natural minerals that are part of the pits, which are technogenic waste of flotation enrichment of coal.

The composition of the proposed composite fuel in the form of a briquette (granules) suggests the following ratio of the components used, wt.%:

bayonet 47.5-52.5 coal screening 28.5-31.5 sawdust (shredded wood waste) 19-21

Shaft pits, in addition to coal dust, contain clay rocks formed as a result of compaction, dehydration and cementation of clays during the formation of coal seams.

The accompanying clay-like rock in mineralogical and chemical composition is very similar to clays, but is more hard and unable to soak in water. It is composed mainly of clay minerals with an admixture of particles of quartz, mica, and feldspars. Clay rocks associated with coal deposits form mechanical compounds with coal at the boundary of the coal seams.

The latter circumstance contributes to the fact that the accompanying clay formations are extracted from the bowels along with coal and are separated from it only during enrichment, i.e. are technogenic wastes, but at the same time, due to imperfections, the beneficiation technologies contain finely dispersed coal.

The proposed composition of the components of the fuel briquette, due to the presence of clay formations, has a high plasticity of the mass with a relatively low humidity of 22-24%, which creates the conditions for its manufacture by the most simple technology - the molding method with high density products.

In addition, the specified factor of high plasticity of the mass (mixture of components) makes it possible to organize the production of briquettes on standardized equipment, for example, on the equipment of brick plants and on proven technology.

The inclusion of coal screening provides increased heat of combustion of the fuel briquette (test results of industrial designs are given below).

The inclusion of sawdust helps to ensure the required kinetics of combustion of the briquette, eliminates the process of slag formation and, in addition, helps to regulate the required moisture content of the mixture of components in preparing the mass for molding.

The manufacture of a fuel briquette is as follows:

1. Preparation of source materials.

1.1. The coal mine, screenings of coal, as a rule, have a finely dispersed fraction and, in fact, do not require special preparation. But in the process of long-term storage, foreign inclusions can get in, so their preparation consists in sifting through a sieve with a mesh of not more than 3 mm and accumulating in hoppers to ensure a continuous production cycle.

1.2. Sawdust requires screening through a 5 mm sieve to separate it from coarse wood inclusions.

In the case of the use of coarse wood waste, they must be chopped to a size of not more than 5 mm on standardized wood shredders.

1.3. Preparation of raw materials for moisture is not required, because the molding process takes place at a mixture humidity of 20-24% and is provided by adjusting the amount of components used within the specified acceptable values.

2. Preparation of the mixture for molding.

2.1. The moisture content of each component is measured.

2.2. The components are dosed based on the required ratio by weight of dry matter, taking into account the total humidity, and fed to the mixer.

2.3. The components are mixed in a blade-type mixer for 10-15 minutes, after which the prepared mass is fed to the former.

The process of preparing the mixture can be carried out both in cyclic and continuous mode, depending on the type of mixer used.

3. Forming and drying.

3.1. Molding can practically be done on any type of shaper, depending on the tasks in terms of production volume and briquette density.

3.2. The geometric dimensions of briquettes (granules) are determined by the configuration of the installed die and the operating mode of the edger.

3.3. The formed briquettes enter the dryer, where they are dried at a temperature of + 50 ÷ 70 ° C for 3 hours.

3.4. After drying, the briquettes are subjected to a stabilization mode, i.e. holding at normal temperature (20 ÷ 25 ° C) with intensive air circulation.

Exposure under normal conditions provides the removal of gradients of internal stresses, stabilization of geometric dimensions and mechanical parameters.

The exposure time is determined by the geometric dimensions of the briquettes (granules), the intensity of the blowing and is established experimentally.

4. Control, packaging, shipment.

4.1. The briquettes are controlled by humidity (allowable value should not exceed 7-10%).

4.2. The requirements for packing (packaging) are determined by the requirement of the consumer, depending on the purpose of fuel use.

4.3. The supply of fuel in packaged and packaged form is provided for the following reasons:

- the need to ensure guaranteed humidity for a long time storage, transportation of products under various atmospheric conditions;

- the need to reduce mechanical stress during loading, unloading, transportation;

- the need to provide a modern service for the consumer when using products, including during storage.

4.4. Warehousing of products is carried out on pallets to ensure the possibility of mechanized loading in railway cars and motor vehicles.

Thus obtained fuel briquette of the proposed composition has the following advantages:

1. Cheap manufacturing, because all components are technogenic wastes, are located on almost the same administrative territory, for their delivery to the briquette production site minimal transport costs are required and unified technological equipment is used to organize production.

2. The selected composition and component ratios provide high plasticity of the mixture at minimum humidity and, as a consequence, the possibility of producing briquettes (granules) by molding, ie by the cheapest and energy-saving technology.

3. The calorific value of the fuel briquette according to the proposed invention is at the level of indicators for enriched coal of the same field from which the waste was taken.

4. According to the kinetics of combustion, the briquette has an increased indicator - the combustion time reaches 10 hours.

5. When briquette is burned, no slag formation occurs; complete combustion is ensured, therefore, the resulting ash can be used as a mineral fertilizer in agriculture without additional processing, as well as for the production of organic fertilizer based on peat.

The stated advantages of the briquette according to the invention are confirmed by the results of pilot production at Sibtekhmet M LLC (Novokuznetsk, Kemerovo Region) on the basis of unified technological equipment of a brick factory and the results of testing industrial samples of products at the Siberian Research Institute of Concentration "SIBNIIUGLEOGOCHASCHENIE" (quality certificate Ref. No. 38-435 of September 11, 2001).

Samples of briquettes made on the basis of the shafts of the Abashinsky Central Processing Plant, which enrich the DR grade coal of the Baibaevskoye deposit of OJSC Kuzbasugol, screenings of DR grade coal and coniferous sawdust in the above ratio have the following indicators:

higher calorific value MJ / kg 33.7 kcal / kg 8061 total moisture,% 4.2 maximum moisture absorption,% 3.8 analytical moisture,% 2,4 ash content,% 24.8 total sulfur,% 0.29 combustion time, hour 8-10

For comparison:

- the highest calorific value of coal of the DR grade of OJSC Kuzbasugol does not exceed 8490 kcal / kg.

- the highest calorific value of coal of grade SS of OJSC Kuzbasugol does not exceed 5700 kcal / kg.

Claims (1)

A fuel briquette containing coal waste in the form of screenings of coal, sawdust and a binder, characterized in that it contains a rod as a binder, which is a coal preparation waste, containing natural minerals with binding properties, in the following ratio, wt.%: Bayonet 47.5 - 52.5 Coal Screening 28.5 - 31.5 Sawdust 19 - 21