RU87242U1 - REINFORCED CONCRETE SMOKE PIPE - Google Patents

Abstract

1. A chimney containing a foundation, a reinforced concrete barrel fixed to the foundation, a lining and thermal insulation, characterized in that the insulation is located outside the reinforced concrete barrel close to it, outside the insulation there is a protective screen fixed to the outer surface of the reinforced concrete barrel with an air gap between the insulation and a protective screen. ! 2. The chimney according to claim 1, characterized in that the thermal insulation is made of mineral wool boards. ! 3. The chimney according to claim 1, characterized in that the protective screen is made of fiberglass panels. ! 4. Smoke pipe according to claim 1, characterized in that the protective screen is made of profiled steel panels close to thermal insulation. ! 5. Smoke pipe according to claim 1, characterized in that the protective screen is made of corrugated sheets of metal or polymer composite materials close to thermal insulation. ! 6. Smoke pipe according to claim 1, characterized in that the protective screen is fixed to the elements of the crate, for example, from bent steel profiles, and the profiles are fixed on the outer surface of the barrel using anchors.

Description

The utility model relates to the field of construction of high-rise structures and can be used in the repair and reconstruction of reinforced concrete chimneys.

Known chimneys containing a foundation, reinforced concrete barrel, lining (brick or monolithic) and thermal insulation in the gap between the barrel and the lining [1]. Reinforced concrete barrel provides the bearing capacity of the structure, the lining protects the reinforced concrete barrel from the direct effects of flue gases, thermal insulation protects the barrel from the temperature effects of flue gases and allows for a "safe" level of temperature stresses in the barrel wall. Often during operation, thermal insulation is destroyed much earlier than the estimated (design) service life, set equal to 50 years. The main reason for the premature destruction of thermal insulation is the temperature and humidity effects of exhaust gases, which penetrate the lining and thermal insulation, condense on the “cold” inner surface of the reinforced concrete barrel, moisten the thermal insulation, which leads to its premature destruction.

The main factors determining the penetration of flue gases through the lining and thermal insulation into the barrel wall are:

- pressure gradient (rarefaction) of flue gases inside and atmospheric air outside the barrel;

- the temperature gradient along the wall of the barrel, which appears in the case of destruction of thermal insulation.

The main reason for the pressure gradient of flue gases inside and outside the outside of the barrel is that when a wind flows around the pipe around the pipe around the pipe, low pressure (rarefaction) zones form [2]. In this case, the rarefaction inside the trunk is less than the rarefaction of atmospheric air outside in areas perpendicular to the wind flow and from the leeward side.

In addition, the appearance of additional temperature stresses in the barrel wall is associated with exposure to solar radiation and wind. The temperature of the trunk sections from the sunny and shadow, from the windward and leeward sides can differ by 20 ... 25 ° С. This also causes additional temperature deformations (deviation from the vertical axis) of the barrel.

Under the influence of atmospheric factors, freezing and thawing of moisture occurs, penetrating the composition of gases and condensing from gases in the barrel wall. As a result, the surface layer of concrete is destroyed, the color-marking coating, the appearance of the pipe is deteriorating.

In the case of destruction of thermal insulation in the barrel wall, a significant temperature gradient appears along its thickness, which leads to a sharp increase in temperature stresses. Temperature stresses reach maximum values on the outer (tensile) and internal (compressive) surfaces of the barrel and cause its destruction. Initially, the destruction manifests itself in the form of cracks in the protective layer of concrete on the outer surface of the barrel, and then in its complete detachment.

After this, as a rule, a major overhaul and strengthening of the trunk, in particular reinforced concrete clips, are required. To prevent this, it is necessary to restore thermal insulation in the gap in a timely manner. Currently, widespread use has been gained in the method of restoring thermal insulation by backfilling into the gap through bulk windows that are specially arranged in the lining of bulk thermal insulation material [3].

The restoration of thermal insulation in this way only allows you to temporarily slow down the destruction processes, since this does not eliminate the reasons due to which the thermal insulation was destroyed before. In addition, to restore thermal insulation requires stopping the pipe for a long time. High complexity and difficult to control the quality of these works. Thermal insulation in the case of wetting for the above reasons largely loses its heat-insulating properties, it is almost impossible to dry it, as a result, the condition of the pipe will be worse than at the time of repair. It will require the removal of moistened thermal insulation from the gap, replacement with a new one.

The utility model solves the following problems:

- increase the operational reliability of existing reinforced concrete chimneys, in which the thermal insulation was destroyed during operation or its heat-shielding properties deteriorated significantly;

- reducing cost, labor, improving quality and ensuring the ability to perform work at any time of the year without stopping the operation of the pipe for a long time;

For this, according to a utility model, in a chimney containing a foundation, a reinforced concrete barrel, a lining and thermal insulation, it is proposed to carry out the thermal insulation on the outside of the barrel and protect it against atmospheric influences with a protective shield, while leaving a ventilated gap or ventilation between the protective shield and thermal insulation. Thermal insulation can be made of mineral wool, fixed to the surface of the barrel on adhesive compositions or other bonds. The protective screen can be made of steel or plastic facade plates and panels, steel profiled flooring, which are fixed to the crate, for example, of thin-walled profiles made of galvanized iron. The elements of the crate are attached to the outer surface of the barrel with anchors or dowels. Between the screen and thermal insulation there is an air gap or ventilation. For natural ventilation of the gap in the lower and upper part of the pipe in the protective screen provide vents that communicate with the atmosphere.

Thermal insulation outside the barrel provides: a decrease in the temperature gradient across the wall thickness, and, consequently, a decrease in the magnitude of thermal stresses; increasing the temperature of the inner surface of the barrel and eliminates or significantly reduces the possibility of formation of condensate on it.

The protective screen eliminates the pressure gradient (rarefaction) of gases inside the barrel and in the air gap between the thermal insulation and the protective screen, the direct influence of atmospheric factors (temperature, precipitation, wind, solar radiation) on the barrel, provides thermal insulation protection. The ventilated gap between the screen and thermal insulation provides favorable operating conditions and durability of thermal insulation.

Figure 1 shows a longitudinal section of a reinforced concrete chimney, figure 2 and figure 3 are fragments of transverse sections of a pipe wall with a protective screen made of flat and profiled panels or sheets, respectively, figure 4 is a fragment of a longitudinal section of a pipe wall.

The chimney (figure 1) is a bearing reinforced concrete, lined and insulated barrel, mounted on a foundation. The wall of the chimney (figure 2, 3, 4) contains: lining 1, made, for example, of brick or monolithic siliceous concrete; air gap 2 with destroyed thermal insulation between the lining 1 and the reinforced concrete barrel 3; bearing reinforced concrete pipe trunk 3; heat-insulating layer 4, made, for example, of mineral wool boards glued or fixed with anchors on the surface of the barrel; elements of the crate 7, made, for example, of galvanized bent profiles fixed to the barrel with anchors or dowels; a protective screen 6, made, for example, of steel or polymer flat or profiled sheets or panels fixed to the element of the crate 7, for example, using self-tapping screws; air gap or products 5, between the heat-insulating layer 4 and the protective screen 6. On the outer surface of the barrel, vapor barrier can be applied, for example, with vapor-permeable paints and varnishes, the heat-insulating layer can be covered with a protective layer of air- and vapor-permeable fabrics. The protective screen 6 can be made of galvanized steel, factory-painted flat and profiled panels and sheets, or fiberglass.

The chimney works on load and impact as follows.

Wind load acts on the protective screen 6 of the pipe. The elements of the crate 7, to which the protective shield 6 is fixed, transfer the wind load acting on the screen to the pipe trunk 3, and the pipe trunk 3 transfers this load to the foundation. When the air flows around the pipe, low pressure (rarefaction) zones are formed around the perimeter of the protective screen 6, and under the screen in the air gap 5 between the insulation 4 and the screen 6, the pressure changes slightly.

The temperature effects from the flue gas side are transmitted through the lining 1 and the gap 2 with damaged or damaged thermal insulation to the pipe barrel 3. At the initial stage, the lining 1 and the gap 2 provide gradual heating of the barrel 3 wall, avoiding the appearance of a dangerous temperature gradient in thickness, and , therefore, and temperature stresses. Thanks to thermal insulation from the outside 4, the barrel wall gradually and evenly warms up throughout the entire thickness. Owing to the available protection and limitation of heat transfer, the temperature along the wall thickness quickly equalizes, which eliminates the appearance of significant temperature stresses during starts, stops, and sudden changes in operating modes. The inner surface of the barrel 3 has a higher temperature than that of the prototype [1]. This eliminates the condensation of the vapors that make up the flue gases on the inner surface of the barrel and its moistening.

External thermal insulation 4 and a protective screen 6 with an air gap 5 protect the barrel 3 from atmospheric influences (temperature, solar radiation, precipitation), thereby eliminating the processes of wetting, erosion, freezing and thawing moisture in the barrel wall, eliminating the causes of differences in barrel temperatures in different its zones.

The ventilated gap 5 removes gases and vapors that penetrate through the wall and prevent the possibility of wetting the thermal insulation due to vapor condensation in the thermal insulation layer.

Work on thermal insulation and the installation of a protective screen can be performed at any time of the year without stopping the operation of the pipe. For this, well-developed and widely used systems of insulated ventilated building facades can be used. All this provides a guaranteed level of quality work. Compared with the prototype, the utility model is characterized by high maintainability, accessibility to inspections and ease of use. Factory painting of the elements of the protective screen ensures the durability and good appearance of the structure.

Thus, in comparison with the prototype [1], the proposed constructive solution to restore the thermal insulation of reinforced concrete chimneys allows you to: increase their operational reliability and durability by eliminating the causes of premature destruction of thermal insulation, reduce temperature stresses in the pipe trunks and more favorable working conditions; to simplify, reduce the cost and ensure a higher quality of repair work, perform work at any time of the year without stopping the work of pipes.

Information sources

1. A.M. Yelshin, M.N. Izhorin, V.S. Zholudov, E.G. Ovcharenko. Chimneys / Ed. S.V.Satyanova. - M .: Stroyizdat, 2001 .-- 296 p.: Ill.

2. E.V. Subbotin, V. A. Luzhkov V. A., V. A. Pazuschan. Taking into account the gradient of static pressures inside and outside the chimneys when assessing the causes of their destruction // Labor safety in industry. - 2006. - No. 6. - p.31-32.

3. M.G. Ladygichev, F.P. Duzhikh, V.P. Osolovsky. Industrial Chimneys and Ventilation Pipes: A Reference Guide. - M.: Heat engineer, 2004 .-- 484 p.

Claims (6)

1. A chimney containing a foundation, a reinforced concrete barrel fixed to the foundation, a lining and thermal insulation, characterized in that the insulation is located outside the reinforced concrete barrel close to it, outside the insulation there is a protective screen fixed to the outer surface of the reinforced concrete barrel with an air gap between the insulation and a protective screen. 2. The chimney according to claim 1, characterized in that the thermal insulation is made of mineral wool boards. 3. The chimney according to claim 1, characterized in that the protective screen is made of fiberglass panels. 4. Smoke pipe according to claim 1, characterized in that the protective screen is made of profiled steel panels close to thermal insulation. 5. Smoke pipe according to claim 1, characterized in that the protective screen is made of corrugated sheets of metal or polymer composite materials close to thermal insulation. 6. Smoke pipe according to claim 1, characterized in that the protective screen is fixed to the elements of the crate, for example, from bent steel profiles, and the profiles are fixed on the outer surface of the barrel using anchors.