Author
Summary of research and developments
Content
Introduction
The urgency of the problem
1. The problem in Ukraine
2. The formation and accumulation of waste in the Donetsk region
3. Existing methods for processing solid waste
3.1 Pre-sorting
3.2 Combustion.
3.3 Processing of rotting waste.
3.4 Processing of combustible waste
4. Technology circulating fluidized bed
Findings
INTRODUCTION
At present, the majority of countries there is a problem not so much a simple burial or disposal of waste, as the development of technologies that utilize contained in waste materials and energy.
Waste from industrial facilities (sludge, mud, etc.) have stable properties and composition, but their processing involves difficulties caused by the formation of toxic substances, the need for neutralization of which entails a complication of the construction unit and additional costs.
The urgency of the problem
The problem of recycling waste heat is very important, because household waste by 40-50% is composed of combustible materials, and its energy value is 7-8 thousand kJ / kg, which is higher than the caloric content of oil shale. Getting thermal energy, usually by direct combustion or gasification of waste. An obstacle for the development of equipment for better use of their potential is the instability properties of household waste.
There are a large number of units for thermal processing of waste. The main task is to select the optimal unit of the existing or the creation of new equipment, free of drawbacks of existing structures.
1. Status of the problems in Ukraine
In the static estimates the average number of MSW per capita in Ukraine is 225 - 250 kg per year, or about 10 million tonnes or almost 30 million m2. But at the same time landill contains many valuable components that can and should be used for further processing to obtain useful products and socio-economic benefits. Structure and properties of waste are extremely varied and depend not only on the level of consumption of the country and locality, season and on many other factors (Fig. 1).
Quantity of municipal waste in Ukraine is increasing, and their composition, especially in big cities (Kyiv, Kharkiv, Donetsk, Dnipropetrovsk, Odesa) approaches that of TBT developed countries with a relatively large proportion of waste paper and plastic (Fig. 1).
(8 frames, the delay to 0.6., An infinite number of repetitions).
The processes taking place in Ukraine at present, lead to a sharp increase in the number and diversity of household waste. Responsibility for their disposal is shifted to local authorities, and this leads to the fact that the company recycling household waste is virtually impossible to put on administrative "foreign" territory - nobody wants to be responsible for "waste" problem.
2. The formation and accumulation of waste in the Donetsk region
Donetsk Region is the largest industry (about 2000 industrial enterprises, 300 deposits of mineral resources) and densely populated region, therefore there has accumulated a huge number of industrial and household waste [1]. Donetsk region steadily become a dumping ground for household and industrial waste. Occupying 4.4% of Ukraine, he became a sanctuary for more than one third of all accumulated waste in a country. In connection with some increase in production since 1999 in the Donetsk region increased industrial waste, amounting in 2000, 52 million tons (24.6 million tons of them toxic). In addition, the still low level of use of waste as secondary resources. The dynamics of the movement of industrial waste in the area shows that despite the apparent growing proportion of the latter, their number is not decreasing, but rather is constantly growing. As a result, there are already more than 1000 sites of accumulation of waste in the form of heaps, dumps, slurry tanks and landfills.
3. Existing methods for processing solid waste
Natural Resources, which consumes humanity can be divided into two parts: renewable and nonrenewable. For renewable resources include all resources that can be recovered by photosynthesis in the foreseeable period of time. It is primarily on all types of vegetation and the resources that you can get out of it. To include non-renewable mineral resources, which in the foreseeable geological time is not restored [3].
3.1 Pre-sorting
This process provides for the separation of municipal solid waste fraction at waste plants by hand or by automated conveyors. This includes the process of reducing the size of garbage components by their crushing and sieving, and extraction of more or less large metal objects such as cans. The selection of the most valuable secondary raw materials is preceded by recycling solid waste (eg incineration). Since the sorting of household waste - one of the components of waste management, there are special factories to solve this problem, ie the allocation of waste fractions of different materials: metals, plastics, glass, bone, paper and other materials to further their separate treatment [4].
3.2 Combustion
This is a widespread method of destruction of municipal solid waste, which is widely used since the late XIX century. The complexity of the direct disposal of solid waste is caused, on the one hand, their exclusive multi-component, on the other - higher sanitary requirements in the process of recycling. In this regard, the burning is still the most common method of primary processing of household waste.
Method of disposal of household waste by pyrolysis is known quite small, especially in our country, because of its high cost. It can be cheap and not poison the environment receiving decontamination wastes. Pyrolysis technology is an irreversible chemical change under the influence of temperature waste without oxygen. By degrees the temperature of exposure of waste pyrolysis as a process conventionally divided into low-temperature (up to 900 ° C) and high temperature (above 900 ° C).
Low-temperature pyrolysis - a process in which crushed material is subjected to thermal decomposition of garbage. In this process the pyrolysis waste has several options: pyrolysis of organic wastes under the influence of temperature in the absence of air, pyrolysis in the presence of air, providing the incomplete combustion of waste at a temperature of 760 ° C pyrolysis using oxygen instead of air to obtain a higher calorific value of gas; pyrolysis without waste separation at the organic and inorganic fractions at 850 ° C, etc.
High-temperature pyrolysis. This method of disposal of solid waste, in essence, is nothing like gasification of garbage. Technological scheme of this method involves obtaining a biological component (biomass) waste recycled synthesis gas in order to use it to produce steam, hot water, electricity. Part of the high-temperature pyrolysis process are solid products in the form of slag, ie nepirolizuemye residues.
3.3 Processing of rotting waste
Organic fraction MSW, resulting from sorting, as well as farm waste and sewage treatment plants may be subjected to anaerobic digestion to obtain methane and compost suitable for agricultural and horticultural work [8]. The final product, humus, completely redesigned, stable and suitable for landscaping, horticulture and agriculture. Methane can be used for the production of heat / electricity.
4. Technology circulating fluidized bed
Fluidized bed, fluidized bed, state of the granular layer of granular material, which under the influence of passing through a stream of gas or liquid (liquefied agents) particles of solid material rapidly moving relative to each other. In this state, like boiling liquid layer, acquiring some of its properties, and its behavior obeys the laws of hydrostatics. In K. pp. achieved by close contact between the granular material and liquefied agent that makes effective use of the fluidized bed apparatus in the chemical industry, where there is interaction between the solid and fluid phases (diffusion, catalytic processes, etc.) [9].
The transition of the stationary layer in the boiling occurs at such a speed fluidize agent, when the hydrodynamic flow pressure balances the gravitational force F G, acting on the particle. With further increase in speed Layer initially expands at a constant hydraulic resistance, while achieving the conditions P> G particles begin imposed from the layer. Figure 1 shows a diagram that characterizes the dependence of pressure drop in the layer ΔP on the velocity of liquefied agent Wo. While the layer is fixed, P increases with Wo (section AB). After point B, corresponding to the transition layer in the boiling state, the resistance of the layer does not change with increasing speed (section XB). After point C, corresponding to the onset of ablation of solid particles, the resistance of the layer decreases. Speed fluidize agent corresponding to points B and C, are called fluidization velocity (W'o) and the rate of ablation (W»0). The ratio of W=W"o/W'o called the number of fluidization. It characterizes the intensity of mixing of particles in a fluidized bed. The most intensive mixing corresponds to W = 2, with further increase of W layer becomes uneven: there is a breakthrough of large gas bubbles through it and begins an intensive ejection of particles in the space above its surface. It is also possible the formation of gas caps. Fluidized bed is characterized by the constancy of temperature on the height and cross section, even if it processes take place with great heat, as well as high values of the coefficient of heat transfer to heat transfer surfaces.
Fluidized bed technology in power plants (installed thermal capacity of 50 MW and more) have been widely used since the mid 70-ies under the influence of introducing stricter regulations on emissions [10].
Findings
1. One of the most effective and modern technologies of local coal burning is a way of burning low-grade fuel and its waste in a circulating fluidized bed (CFB), also possible to replace coal sorted municipal solid waste.
2. Technology bubbling and circulating fluidized bed is widely used in many foreign industrial and power plants, ensuring efficient combustion of a wide range of fuels with minimal emissions of harmful substances, the most stringent standards.
3. CCS provides the possibility of burning fuels of different quality in the same pot, simplified fuel preparation (crushing), good dynamic performance, fast start-up of "hot" state, compact boiler plant, stems from the lack of sulfur-and nitrogen removal, which can accommodate CFB boilers in existing boiler cells.
4. Capital expenditures for the reconstruction of existing thermal power plant circulating fluidized bed technology in 2,5-3 times lower than for new construction and make up, according to various sources, 400-600 USD / kW.
Literature
Куруленко Р.М. Земля тривоги нашої. За матеріалами національної доповіді про стан навколишнього середовища в Донецькій області / /Донецьк: НПП «Віза - Про», 1999 р. – с. 107.
Эскин Н.Б. Анализ различных технологий термической переработки твердых бытовых отходов / Тугов А.Н. // Энергетик, 1994г. – с.6-9.
Куруленко Р.М. Земля тривоги нашої. За матеріалами національної доповіді про стан навколишнього середовища в Донецькій області // Донецьк: НПП «Новий мир», 2001 р. – с. 136.
Ксинтариса В.П. Использование вторичного сырья и отходов в производстве. // М.: Экономика, 1983г. – с.186.
Алексеев Г.М. Индустриальные методы санитарной очистки городов. / Петров В.Н. // Л.: Стройиздат, 1983г. – с.96.
Обезвреживание, переработка и использование ТБО//Москва, 1975г. – с. 140.
Белосельский Б.С. / Низкосортные энергетические топлива: Особенности подготовки и сжигания. // М.: Энергоатомиздат, 1989г. – с. 136.
Тихотская М.Р. / Проблемы утилизации отходов // М.: Наука, 1992г.
Котлер В.Р. / Использование горючих отходов в качестве топлива. // М.: ВИНИТИ, 1983г. – с. 290.
Вискин И.Л. / Сжигание угля в кипящем слое и утилизация его отходов//Д.: «Новый мир», 1997г. – с. 284.
Романов В.И. Газотурбинные технологии. / Межибовский В.Н. // ГТД —110 — от проекта к реальности 2000г. - № 6. с. 8—12.
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