Abstract
Соntents
- Introduction
- 1. Theme urgency
- 2. Goal and tasks of the research
- 3. The species and composition of lining
- 4. Improvement of lining
- References
Introduction
Setting the steam boiler and serves to shield the combustion chamber and flues from the environment. Setting of steam and hot water boilers operating at sufficiently high temperatures and abrupt change them, as well as under the influence of chemical gases, fly ash and slag. The design of lining should ensure minimum loss of heat to the environment, be firm, to withstand prolonged exposure to high temperatures, chemical resistance of products of combustion, ash and slag, be mechanically strong, light, easy, cheap and affordable to repair, facilitate the implementation of the block installation of steam or hot water boiler.
1. Theme urgency
Analysis of the issue of safe working conditions for lining of boilers, showed the limitations of the work on the subject. Most research in this area mainly concerns the work of lining metallurgical furnaces. The most crucial period in the lining of the boiler is heating it, especially when cold. It was during this period of time there are maximum temperature differences and thermal stresses. Therefore, the question actually studying the characteristics and state of operation of lining the boiler during its heating in order to determine the actual heat loss to the environment. Based on the analysis determined the purpose of work and sets out the basic objectives of the study.
2. Goal and tasks of the research
The aim of this study is to determine the actual heat loss to the environment
Main tasks of the research:
- Identify and evaluate the actual heat loss to the environment through the settling of existing steam generators.
- To make analysis of the heat loss through boilers setting, output interpolation formula and evaluate the impact of various factors on the magnitude of the heat flux through the lining of the boiler.
- Perform pilot study to determine the coefficient of thermal conductivity.
- Identify and assess the impact of thermal stress status of lining on the heat loss to the environment.
- Develop a temperature modes of heating boiler brickwork in order to increase the efficiency of the unit.
Research object: settling boiler
Research subject: The subjects of the study are the heat flows through the settling boiler unit, and thermal stresses occurring in it due to significant temperature gradients.
3. The species and composition of lining
Steam and hot water boilers have a pretty diverse for bricking structure. However, regardless of the design of the unit and its power units and some elements are shared. These include: walls, arches, ceilings, arches, loopholes, pods, hot zone, place pipe penetrations through the lining and so on. e. boilers setting is conventionally divided into heavy, light weight and easy. Heavy settling used in steam generators and old designs currently used in steam generators has low power (Eg, steam generators DKVR). In new construction, steam generators and boilers used lightweight and light brickwork. The weight of 1 m3 heavy obmurovok comes to 1800 kg, and light - not more than 1000 kg. The destruction of the brickwork is primarily dependent on the temperature, in which it works. With increasing temperature, the intensity of the destruction of the lining of increases. The more irregularities on the brickwork, facing the interior of the duct, and the thicker its seams, the more it wears and wears. Chemical attack toxins leads to softening, Mr. melting violation bricking structure. Vertical wall lining of the combustion chamber and flues can be made of different materials: refractory, construction and thermal insulation bricks, refractories, fire-resistant and heat-insulating concrete, Temperature resistant insulation, etc. Setting usually consists of two layers: the inner, facing the gas duct, and outdoor. The inner liner layer is called, and the outer - the facing layer. The lining is made of fireproof material, a cladding material of low thermal conductivity. Heavy settling consists of two layers: an inner made of refractory bricks, and exterior of a building brick. For the stability of the liner and liner vperevyazku operate over the entire height of the wall. Heavy settling rests on the foundation and has a height of no more than 8-10 m. Significant influence pas reliability of the brickwork has a thickness of seams between the bricks. The thickness of the seams when the masonry of refractory bricks must not exceed 3 mm, and the red-brick - 5 mm. For a free expansion of lining (interior and exterior) always provided the device horizontal and vertical expansion joints in such a way that the columns and the frame does not hinder the free expansion of the facing masonry. When the heavy obmurovok widely used arches and vaults are designed to overlap the openings of the ceiling of the combustion chamber or flue. The vaults under its own weight and thermal expansion arise spacers efforts. The arches are made of special bricks klipovoy and rely on the heels, out of special shaped stones. Sometimes masonry arch perform thickness separate rings. The lower arch is basic, and the upper discharge.
4. Improvement of lining
After the use of heavy and lightweight masonry fences boilers improved in two ways: creating nakarkasnyh obmurovok shield using heat-resistant concrete and light-pipe obmurovok. The emergence of boilers with welded screens allowed go to the lungs insulating structures. This change was made possible because of the lack of contact with the lining of the torch. In the USSR, the first screen of the heating surface, made in the form of pipes with welded longitudinal ribs to them, appeared in the late 30s. For pipes with a diameter 83X4 mm welded longitudinal edges with the size of 30X6 mm. However, poor quality welding, and the wrong choice of sizes and shapes ribs led to cracks in the ribs and fistulas in pipes, so the screens were removed. In subsequent studies on the creation of gas-tight boilers Boiler-Making Works in conjunction with the institutions were designed and installed several boilers designed to operate under the supercharged with different structural design of gas-tight enclosures. Boilers have a steel casing through pipes welded gas-tight panel of smooth pipes with welding of strips between them. Experience of creation and development of these boilers revealed advantages and disadvantages of fences with wallboard and paneling dense gas. Considering the use of gas-tight screens should elaborate on their benefits, associated with the boilers setting.
- Considerably reduced weight characteristics of the fence, because in modern high capacity boilers mass bricking. It is so large that its effect on the carcass structure requires special consideration.
- Shortens the life and labor for installation and repair insulation works. Experience shows that when repairing the heating surfaces boilers with conventional bricking it accounts for 40-50% of all time spent on repairs.
- Dramatically reduced storage capacity enclosures, which increases the maneuverability of power, reducing the time starts and stops.
- It reduces the risk of moisture and destruction insulation gas-tight screens at blasting steam treatment for washing screens n water.
References
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- Воронков С.Т., Исэров Д.З. Тепловая изоляция энергетических установок. —М., 1982.
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- Воронков С. Т. Обмуровка парогенераторов электростанций/С. Т. Воронков, Д. З. Исэров. - 1970
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