Introduction

Modern energy causes significant damage to the environment, worsening the living conditions of people. The basis of modern energy – various types of power plants. The technology of electric power production at TPPs is associated with the formation of a large amount of waste.

When fuel is burned at TPP, combustion products are formed, which contain: fly ash, particles of unburnt pulverized fuel, sulfuric and sulfur dioxide, nitrogen oxide, gaseous products of incomplete combustion. When burning fuel oil, vanadium compounds, coke, sodium salts, soot particles are formed. In the ash of some fuels there is arsenic, free calcium dioxide, free silicon dioxide.

Another burning issue related to coal-fired power plants is ash dumps, not only do they require significant areas for their development, they are also a source of environmental pollution, hotbeds of heavy metals and have increased radioactivity. One of the possible ways to solve this problem is the utilization of waste, that is, their return to the material circulation, which has an important ecological, economic and energy–saving significance.

1. Relevance of the topic

One of the main environmental problems in the combustion of coal is the formation of a significant amount of ash and slag waste. At the thermal power plant of Zuevskaya TPP, 400 to 800 thousand tons of ash and slag are generated annually, from which it is used for own needs and is transferred to outside consumers on average up to 5%. At the thermal power plant, all ash and slag wastes are stored at the ash dump with the use of a hydraulic ash removal system. Wet ash–and–slag falling into the ash–and–slag digs quickly cracks and largely lose their consumer properties.

As the world shows, and domestic experience ash and slag wastes are valuable mineral raw materials – ash and slag materials for replacing natural mineral raw materials in the construction complex, cement industry, road construction.

The accumulation of a huge mass of industrial wastes is an urgent environmental problem requiring urgent solution.

2. Purpose, tasks and object of research

Purpose: to determine the technical feasibility of the implementation of ash, slag and ash and slag Zuevskaya TPP, the search for optimal ways of utilization of ash and slag waste.

Objectives of the study:

1 – Study of the composition and properties of waste at Zuevskaya TPP.

2 – Show the effect of ash and slag wastes on the environment.

3 – Analyze the methods of utilization of ash and slag, which exist in the world practice and determine the optimal methods of utilization of ash and slag Zuevskaya TPP.

4 – Identify weaknesses in the process of waste generation and propose possible circuit–technological solutions oriented towards solving this problem.

5 – To carry out ecological and economic evaluation of the developed measures.

The object of investigation is ash and slag (ash, slag, ash and slag mixture) of Zuevskaya TPP.

3. The process of formation of ash and slag wastes at TPP

When burning solid fuel in furnaces of thermal power plants, many–tonnage solid mineral waste is formed, represented by slag and fly ash.

At modern TPP, coal is burned in a pulverized state. Ash – non–combustible residue with grains smaller than 0.16 mm, formed from the mineral impurities of the fuel when it is completely burned and deposited from the flue gases with ash–collecting devices. Fuel slag is a material that accumulates in the lower part of the combustion chamber of heat aggregates and is removed in a liquid or sintered state. With the joint removal of ash and slag by hydrotransport, a ash–slag mixture is formed at thermal power stations.

One medium–power TPP annually releases up to 1 million tons of ash and slag into dumps. Warehousing and storage of such a mass of material requires significant capital investment. Ash dump, occupies very large land areas, is a source of unfavorable ecological situation in the area[1].

4. The impact of ash dump on the environment

The accumulation of a huge mass of industrial wastes is an urgent environmental problem requiring urgent solution. Dumps of ash and slag materials occupy large areas, caring for them requires significant operating costs. The location of ash and slag at the ash dump is associated with a certain impact on the environment and significant costs. The service life of the ash dump is limited by the technical capability, the condition of reliability and environmental safety.

Ash dumps are objects of increased ecological danger due to:

– dusting of beaches, especially in the summer;

– filtration into underground horizons of waste water enriched with soluble ash components;

– inevitable discharge of excess clarified water into surface water sources;

– alienation of land;

– surface deformation;

– pollution by toxic elements, heavy metals;

– decrease in soil fertility and crop yields;

– flue gas pollution;

– dusting ash dumps during transportation, storage and wind erosion;

– reduction in the number of forest, vegetation, animal, and biota species; biodiversity change;

– deterioration of the ecological and aesthetic state of surface watercourses [3].

5. Chemical and phase-mineralogical composition of ash and slag

The ashes in this paper are investigated as a material suitable for the preparation of building materials and, above all, as an additive to cement. From this point of view, the most important physical properties of the ashes are: true, average, and also bulk density, granulometric composition, specific surface area. The granulometric composition of the ash is studied by the sieve analysis method with screening into fractions: +0,2; –0,2 + 0,08; –0,08.

Based on the sum of the ash properties of the thermoelectric power station under investigation and the nature of the composition variation, an opinion is made on the suitability of ash from TPPs for use as a building material.

Conclusion

In the course of the work, the composition of ash–and–slag Zuevskaya TPP was reviewed, the influence of the ash dump on the environment was shown, the optimal methods for utilization of ash–and–slag was analyzed, and the program for processing and use of ash–and–slag was developed, the main directions for increasing the use of ash and slag wastes were identified.

Commercial characteristics of ash and slag are worsened by their joint hydraulic removal and storage on dumps. That is, in the long term it is necessary to focus on separate removal of ash and slag. Separation of ash and slag flows of Zuevskaya TPP at the first stage should be carried out at the expense of the cheapest and most effective measure – introduction of pneumatic ash removal and dry ash removal systems.

References

1. Классификация отходов ТЭС. – Глобальная сеть рефератов Олбест [Электронный ресурс] – Режим доступа: http://otherreferats.allbest.ru/manufacture/00093796_0.html
2. Мелентьев В.А., Нагли Е.З. Гидрозолоудаление и золоотвалы. – Ленинград, Энергия, (Ленинградское отделение), 1968.
3. Малый Э.А., Дорфман М.Л. Справочник по утилизации отходов ТЭС. – М., 1995. – 158 с.
4. Карпенко И.С., Попов В.В. и др. Поризованный бетон из золошлаковых смесей. Сб. Современные проблемы строительства. Д., 2001, стр. 147–150.
5. Рекомендации по применению золы, шлака и золошлаковой смеси тепловых электростанций в тяжелых бетонах и строительных растворах. М., Стройиздат, 1977.
6. Рекомендации по применению в бетонах золы, шлака и золошлаковой смеси тепловых электростанций. – М., Стройиздат, 1986 – 80 с.
7. Рекомендации по комплексному укреплению грунтов золошлаковыми смесями ТЭС и известью. – Киев, Госдор НИИ, 1973 – 51 с.
8. Анализ технологий и методов утилизации твёрдых продуктов десульфуризации и частиц золы. – Украинский финансово-промышленный концерн УФПК [Электронный ресурс] – Режим доступа: http://www.ufpk.com.ua/files/p3/analiz.html
9. ДСТУ Б В.2.7–72–98 Щебень и гравий из плотных пород и отходов промышленного производства для строительных работ. Методы химического анализа.
10. ДСТУ Б В.2.7–205:2009 Золы уноса тепловых электростанций для бетонов. Технические условия