RU2479622C1 - Method to recycle solid domestic wastes into fuel for furnaces of high-temperature synthesis of cement clinker - Google Patents

Abstract

FIELD: power engineering.

SUBSTANCE: invention relates to the method of recycling solid domestic wastes (SDW) into fuel for furnaces of high-temperature synthesis of a cement clinker, including sorting of initial SDW so that at first such incombustible fractions such as batteries, stones, fragments of glass and faience, then secondary materials are extracted, including ferrous and non-ferrous metals. The remaining mass is previously ground to the fraction of 50-100 mm, dried to humidity of 5-10%, and then ground to the fraction of 8-10 mm. The ground raw materials are heated to 160-200°C and exposed to thermoplastic extrusion to produce fuel pellets.

EFFECT: method makes it possible to increase physical and mechanical strength of RDF fuel, to eliminate water absorption due to capsulation of granules in process of their manufacturing, to prevent possibility of rotting and self-ignition, to reduce costs during storage and transportation, to reduce energy intensity of its production, to improve environment, also to reduce volume of SDW removed to SDW landfills, to eliminate capital costs for construction of plants for wastes management in connection with usage of equipment of existing cement production facilities.

1 cl, 4 dwg

Description

The invention relates to the field of ecology, in particular to the processing of municipal solid waste (hereinafter - MSW) into fuel for furnaces for high-temperature synthesis of cement clinker, the combustion of which complies with environmental protection requirements, and can be used in the cement industry while solving environmental problems , saving of natural resources and disposal of solid waste. Also, such fuel can be used in other furnaces subject to certain requirements for the purification of flue gases (combustion products).

Today, in many countries of the world, including in our country, there is a critical situation with the accumulation and disposal of solid waste, which makes solving these problems an urgent vital necessity. The collection and storage of solid waste require ever new territories, transport, loading and unloading equipment, human resources. Existing landfills require additional investments to ensure environmental safety. The capacities of MSW incineration plants available in our country are insufficient, and most importantly, the technology used on them is technically very problematic, environmentally hazardous and economically inefficient.

There are various methods for producing molded, including extrusion, materials from various types of waste (see RU No. 2118256, B29B 17/00; B29B 7/42; B29C 47/00, B29C 47/76, 1998; RU No. 2397829, B09B 3/00, 2010; RU No. 2212287, B09B 3/00; C04B 12/00, 2003).

Known methods for producing building materials from polymeric waste used as a binder, and fillers (sand, wood dust or fine sawdust), for example, polymer sand tiles (http://www.openbusiness.rn/html/dop/polimer-cherepiza. htm) and the so-called wood plastic (http: //drevoplastic.m/ekstruzia-drevoplastika.html). In particular, the method for producing polymer sand tiles from polymer waste does not involve the purification and deep sorting of polymer raw materials. Even the presence of engine oil that comes in cans does not affect the quality of the tiles. After grinding, the components in a proportion of 70% filler - sand, 30% polymers are fed into an extrusion machine, where they are heated to a temperature of 170-190 ° C and pressed through spinnerets to obtain products of the desired configuration.

The above methods of processing various types of waste have a number of disadvantages, the main of which is their unsatisfactory environmental study, associated with the formation of secondary waste containing highly toxic organic compounds, and with a high cost of processing.

Known methods for the manufacture of solid waste fuel for cement kilns by grinding it and blowing it in a furnace (O.N. Kaigorodov. Grinding equipment for the preparation of alternative fuel, Cement and its application No. 1, 2009).

The disadvantages of these methods include the lack of heat treatment of solid waste at temperatures of 170-190 ° C and, as a result, the presence of pathogenic and pathogenic microorganisms and other biological hazards in this fuel, as well as the high energy costs of fine fraction grinding.

Known methods for the manufacture of solid waste fuel for cement kilns by drying, heat treatment at temperatures up to 230 degrees Celsius, briquetting it or grinding to a dust fraction and blowing in an oven.

The disadvantages of these methods include the possibility, when moistened with solid waste, the occurrence of foci of decay and spontaneous spontaneous combustion.

A known method of producing solid fuels made from industrial and household waste, which consists in the fact that at the first stage sorting of industrial and household waste and separation into three groups is carried out: the first group contains large-sized metal objects, cords and hazardous substances that are removed from the total mass source waste and subsequently disposed of; the second group contains bulky industrial and household waste; the third group contains waste that is less than 150 mm in overall dimensions; at the second stage, the first stage of processing industrial and household waste is carried out to reduce their overall dimensions less than 150 mm, while the waste of the second group is placed in a screw crusher; at the third stage, the second stage of processing industrial and household waste is carried out, during which the waste of the second and third groups is fed to a horizontal breaking plant to reduce their volume; at the fourth stage, lime is added to the waste obtained in a horizontal batching unit, then round briquettes are molded at high pressure and temperature, the obtained round briquettes are dried to form the final product with a diameter of 15-30 mm, a length of 30-150 mm, and calorific value over 6000 kcal / kg and a combustion temperature in excess of 1100 ° C. The resulting solid fuel is used for combustion in power plants (RU No. 2405027, C10L 5/48; C10L 5/46; 2010). Taken as a prototype.

The prototype also has several disadvantages. The method is energy intensive, since briquetting requires high pressures and temperatures. In addition, when moistened, hydration of lime will occur and possible destruction of briquettes, the final product.

The problem to which the claimed invention is directed, is to increase the strength and improve the operational properties of fuel from solid waste for furnaces for high-temperature synthesis of cement clinker, the combustion of which ensures environmental protection requirements.

The technical result consists in increasing the physical and mechanical strength of RDF fuel, eliminating water absorption due to encapsulation of granules during their manufacture, preventing the possibility of rotting and spontaneous combustion, reducing costs during storage and transportation, reducing the energy consumption of its production, improving the environmental situation, including reducing the volume solid waste disposed of at landfills, excluding capital costs for the construction of waste disposal facilities in connection with the use of equipment of existing cement production.

The essence of the invention lies in the fact that in the method of processing municipal solid waste into fuel for furnaces for high-temperature synthesis of cement clinker, which includes sorting the initial solid waste with the removal of various fractions, grinding the remaining mass, obtaining the final product and its subsequent burning, the feature is that first non-combustible fractions such as batteries, stones, fragments of glass and faience are sifted out, then secondary materials, including ferrous and non-ferrous metals, are extracted, and the remaining mass is preliminarily it is ground to a fraction of 50-100 mm, dried to a moisture content of 5-10%, and then crushed to a fraction of 8-10 mm, after which the crushed raw material is heated to 160-200 ° C and subjected to thermoplastic extrusion to obtain fuel granules that yield they are cooled from the extruder and sent as fuel to cement plants for subsequent combustion in high-temperature synthesis of cement clinker furnaces.

The combination of these essential features allows you to get the specified technical result.

According to the authors of studies of the morphological and component composition of the “tailings” of solid waste (see table 1 of figure 1), they contain a small amount of food waste, but the polymer fractions make up about 35% of the dry weight of solid waste. This circumstance suggests that the polymer fractions present can be used as a binder for briquetting. At the same time, their high calorific value will provide an acceptable energy potential of fuel briquettes.

The laboratory process for producing briquettes (see Fig. 2) from model MSW showed that the carbon-containing solid residue was impregnated with molten polymers and, during subsequent pressing, this ensured high briquette hardness, an almost uniform briquette cut structure, and low moisture capacity. The output of briquettes amounted to 43% of the working mass of solid waste.

This briquetted fuel can be used for further pyrolysis, which will prevent the need for storing untreated solid waste near cement plants, will not complicate the anthropogenic load on the location of enterprises and will avoid the risk of spontaneous combustion.

Properly organized sorting of solid waste provides a significant reduction in the amount of generated waste and a decrease in the negative impact of solid waste on the environment and allows you to extract useful components.

Heating the mass of raw materials before extrusion and during the extrusion process leads to the fact that the polymer component of the “tailings” of solid waste melts, impregnates the entire volume of the processed material and thus encapsulates the organic component present in it. Preheating in a certain temperature range is necessary for uniform heating of the material, which is not achieved simply with conventional extrusion, because studies have shown low thermal conductivity of solid waste. Because polyethylene and polypropylene are present in the “tailings” of solid waste, the melting temperature of which is different, then polyethylene does not melt below 160 ° C, and gasification occurs above 200 ° C.

Shredding of waste provides better preparation for encapsulation. Shredding also facilitates the transport and handling of waste during the recycling process.

Drying the mass of raw materials can reduce the specific gravity and increase the calorific value of the final product. An increase in moisture content to a level of more than 10% increases energy consumption and fuel consumption.

Encapsulation provides fuel with high physical and mechanical strength, eliminates water absorption, which reduces the cost of its storage, loading, unloading and transportation. Reducing energy consumption and increasing the strength of the fuel provides the possibility of its storage in the open. Low moisture saturation and the ability to store in open warehouses expand the functionality of fuel use and reduce the cost of its storage.

Cement enterprises have modern powerful technological equipment, and the cement kiln is currently the most environmentally friendly waste disposal unit, including those harmful to humans and the environment. Technological and heat engineering processes in it take place at temperatures up to 1700 ° C, which ensures the minimization of the content of harmful substances in the exhaust gases, as well as chemical bonding in clinker minerals of some harmful substances released from the waste during their processing at higher temperatures than , for example, in the furnaces of waste processing plants or in units of other industrial plants. In addition, the burning of fuel-containing waste in cement kilns can significantly reduce the consumption of expensive fuel (gas, fuel oil, coal) and reduce the cost of cement production.

The proposed method for the production of solid fuel from solid waste for furnaces for high-temperature synthesis of cement clinker can be implemented on the standard equipment of the waste sorting station, understaffed with the necessary equipment for its implementation.

Figure 1 presents table 1 - the morphological composition of solid waste after the sorting line of the Lipetsk waste sorting plant in terms of dry matter; figure 2 is a sample of fuel briquettes obtained from solid waste in the experiment; figure 3 presents the technological scheme of the installation; figure 4 presents table 2 - the data of the financial statements of ZAO EcoProm Lipetsk for 2011.

A method of processing solid waste into fuel for furnaces for high-temperature synthesis of cement clinker is as follows (see figure 3).

After the delivery of municipal solid waste to the sites, the storage bins of the waste sorting stations (plants) from them large-sized waste is preliminarily extracted with their further grinding in crushers. Plastic bags with MSW are destroyed (cut, torn), MSW is screened on drum or other separators, screens with the sieving of batteries, stones, glass fragments, earthenware, sand and other small-fraction waste. Solid waste sorting is carried out with the maximum extraction of secondary materials from them, including ferrous and non-ferrous metals. Ferrous metals are extracted by magnetic separation, non-ferrous metals are extracted using an alternating magnetic field or by crushing followed by pneumovibro-separation. An increase in the extraction of metal fractions leads to a decrease in the toxicity of the residue.

The remaining mass of solid waste - “tails” (in this case, raw materials) are discharged onto conveyor 1 and fed to them for preliminary grinding to a fraction of 50-100 mm into a crusher of type 2 shredder of the required capacity. After the crusher 2, the crushed raw material enters the dryer 3 to remove moisture from it up to 5-10%. Drying is carried out in dryers that exclude contact of the material, the “tailings” of solid waste, with a heating agent, flue gases. In this case, the drying temperature should be below 140 ° C. This heating method is necessary to prevent emissions of toxicants and pathogens present in the MSW with flue gases into the atmosphere, which is especially important for a countercurrent drying scheme. Drying is required only when the moisture content of the “tailings” of solid waste exceeds 15%. Further, the raw materials on the conveyor 4, equipped with a magnetic separator 5 for the extraction of possibly remaining ferrous metals and a container 6 for metal waste are fed into a knife, hammer, or shredder mill 7 for final grinding to a fraction of 8.0-10.0 mm. Grinding to smaller fractions is preferable, but not economically feasible. After grinding, the raw material enters the raw material heater 8, the design of which can be similar to that of the dryer 3, where it is heated to a temperature of 160-200 ° C. The heated raw material enters the press granulator 9 of a screw or other type, where fuel granules are obtained from it by thermoplastic extrusion, which are cooled by the exit from the extruder, loaded, for example, into Big Bags, or other containers, or in bulk and sent to cement plants for subsequent combustion in furnaces of high-temperature synthesis of cement clinker by loading the obtained granules into a kiln.

Example. The technological scheme of the pellet production line can be equipped as follows:

1. feed conveyor

2. GL series twin rotor crusher

3. multifunctional conveyor oven

4. receiving conveyor

5. magnetic separator

6. ferrous metal tray

7. HRS800 secondary crusher

8. multifunctional conveyor oven

9. extruder press EB 1000

10. finished product bin

11. portable firebox

12. burner.

The advantages of the proposed method are that when the solid waste is heated to a temperature of 160-200 ° C, all pathogenic and pathogenic microorganisms die, the polymers soften and melt, enveloping the ground solid waste, binding and encapsulating them, and the granules are convenient for transportation, for example, loaded into Big - Becks. They have no water absorption, they do not rot and do not ignite spontaneously.

In addition, it is possible to aggregate evaluate the economic efficiency of the disposal of solid waste by the proposed method in comparison with the existing technology for the disposal of “tailings” of solid waste at the landfill sold by ZAO EcoProm-Lipetsk, Lipetsk. The study of the effectiveness of the disposal of solid waste as fuel for cement clinker furnaces was carried out on the basis of the financial statements of EcoProm Lipetsk CJSC for 2011 (see table 2 of figure 4).

Thus, for pressing and burying 1 ton of solid waste “tailings”, the costs (landfill + energy) amounted to 466.7 rubles / ton.

One-time costs:

- the cost of the press company Imbed Iberica. C.A. "22.0 million rubles.

- The cost of constructing a plan card for a solid waste landfill is 11.0 million rubles. The one-time equipment costs in terms of a ton of processed solid waste were: 1413.22 rubles / t.

Other costs (for transportation, wages, etc.) are not considered, as they are saved in the proposed alternative technologies.

Getting fuel briquettes.

For the conditions of the city of Lipetsk, the annual volume of fuel briquettes produced, subject to the complete processing of solid waste tailings, is 14011.0 tons of briquettes with a calorific value of 28.63 MJ / kg.

25.0 × 10 ⁶ MJ of heat is required for heating and evaporating the moisture contained in the “tailings” of solid waste - 9340.4 tons, which is ensured by burning 2000 tons of briquettes, while the remaining 120,000 tons are a commercial product and can replace 10,200 thousand m ³ natural gas, which will save 27030 thousand rubles. at the price of natural gas 2650 rubles / 10003 m ³ without VAT.

The costs of processing the “tailings” of solid waste into fuel pellets, briquettes at a plant with a capacity of 1 t / h are added, including the cost of electricity to drive the units. And make up for the experimental sample:

feed conveyor, kW / h 1,5 receiving conveyor, kW / h 1,5 multifunctional conveyor furnace, kW / h 2.7 GL rotary crusher, kW / h 15 + 15 secondary crusher XFS800, kW / h 22.0 multifunctional conveyor furnace, kW / h 2.7 extruder press EB 1000, kW 15.0 remote firebox, kW / h 1,5 Total per process, kW / t 76.9 Total for the process, RUB / t 423.0

One-time equipment costs:

feed conveyor RUB 1.00 million GL series twin rotor crusher 2.10 million rubles. multifunctional conveyor oven 1.40 million rubles. receiving conveyor RUB 1.00 million magnetic separator 0.10 million rubles XFS800 secondary crusher 1.750 million rubles. multifunctional conveyor oven 1.40 million rubles. extruder press EB 1000 0.50 million rubles. fuel briquette hopper 0.05 million rubles. remote firebox 1.50 million rubles. metal structures 0.30 million rubles. Total equipment needed 11.10 million rubles

When the EA furnace is operating as part of a pellet production plant with a capacity of 1.0 t / h, the one-time costs for equipment in terms of a ton of processed solid waste will be: 1401.52 rubles / t for equipment.

Thus, the introduction of technology for producing fuel briquettes due to energy saving and refusal from landfills, according to a rough estimate, will reduce the cost of disposal of solid waste by 55.40 rubles per ton or for the city of Lipetsk 1.29 million rubles per year.

In addition, the savings due to the replacement of process fuel with fuel from solid waste will be 27030 thousand rubles. year at a price of natural gas 2650 rubles / 1000 m ³ without VAT.

The invention allows to simultaneously solve environmental issues, save natural resources, waste management and obtain fuel materials that can be used for burning in cement kilns high-temperature synthesis of clinker. The resulting fuel has high mechanical strength, which reduces the cost of its storage, loading, unloading and transportation.

The method allows for the secondary use of solid waste, increasing their value. Fuel is transportable and easy to use. It can be stored for a long time even in the open air and spent as needed, which will reduce the anthropogenic load on the territory surrounding the cement production.

The proposed integrated technological solutions for the processing of solid waste, designed to produce competitive commercial products, can today attract the attention of private investors to the waste recycling business.

Claims (1)

A method of processing municipal solid waste into fuel for high-temperature cement clinker synthesis furnaces, including sorting the initial solid waste with the removal of various fractions, grinding the remaining mass, obtaining the final product and its subsequent burning, characterized in that such non-combustible fractions as batteries, stones are first screened out fragments of glass and faience, then recycle secondary materials, including ferrous and non-ferrous metals, and the remaining mass is pre-crushed to a fraction of 50-100 mm, dried to moisture and 5-10% and then crushed to a fraction of 8-10 mm, after which the crushed raw material is heated to 160-200 ° C and subjected to thermoplastic extrusion to obtain fuel granules, which are cooled down upon leaving the extruder and sent to cement plants as fuel subsequent combustion in furnaces of high-temperature synthesis of cement clinker.

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