RU2707561C1 - Tubular channel for removal of water, steam and gases from concrete filler - Google Patents

Abstract

FIELD: nuclear equipment.

SUBSTANCE: invention relates to nuclear engineering and can be used in design of metal-concrete (reinforced concrete) shaft of reactor, for example, in power plants with reactor on fast neutrons with heat carrier in form of lead or its alloys. Tubular channel contains a tubular element which is put into the metal-concrete structure. Tubular element represents an untight flexible corrugated metal sleeve, on the outer side of which protective-filtering coating is applied in the form of spiral-wound woven asbestos tape impregnated with solution slowing hardening of cement stone.

EFFECT: invention makes it possible to minimize possibility of tubular channel clogging during concreting and provides the possibility of efficient removal of water, steam and gases from concrete filler at high-temperature drying of heat-resistant concrete mass, which ultimately improves reliability of metal-concrete structures operating at high temperatures.

3 cl, 3 dwg

Description

The invention relates to nuclear engineering and can be used in the construction of a metal-concrete (reinforced concrete) reactor shaft, for example, in power plants with a fast neutron reactor with a coolant in the form of lead or its alloys.

In the production of concrete structures operating at high temperatures, during high-temperature drying of concrete masses enclosed in a confined space, a threat to the integrity of the structure is an increase in the pressure of water vapor (vapor-gas mixture) formed during the drying of the concrete aggregate. To prevent an uncontrolled increase in the pressure of the vapor-gas mixture and the appearance of internal stresses in concrete, leading to a violation of its structure and strength properties, it is necessary to remove water, steam and gases from the concrete filler.

It is known to use flexible metal unpressurized sleeves from a spiral-wound (spiral-wound) pipe from a pre-S-shaped profiled flat metal strip as tubular slotted drainage of filter systems for water treatment (RU 2178329, B01D 24/38, F16L 11/36, E03B 3 / 40, 2002). When forming a spiral-wound pipe from a pre-S-shaped profiled flat metal strip, a radial clearance between adjacent turns is obtained naturally. Since the tape, as the structural basis of the pipe, is rolled into a spiral, the gap between the turns is a spiral. Due to the central symmetry of the S-shaped profile, two spiral slots are actually obtained - one external, the other internal, through which the internal cavity of the pipe can communicate with the surrounding space.

The disadvantages of the known technical solution include the fact that, in the case of using a flexible metal leakproof sleeve as a channel for drying a concrete filler of a metal concrete structure, particles of cement paste may get stuck in cracks during concreting and also fall into a sleeve (i.e. - may clog the channel).

Known protective filter coating of the drainage pipe according to auth. SU 763518 (ЕВВ 11/00, 1980), made in the form of a permeable porous or perforated tape made of synthetic material.

However, the known solution relates to the field of land reclamation, that is, has a limited scope. However, its specific characteristics do not meet the requirements for tubular channels, monolithic in a metal concrete structure.

Known metal-concrete construction according to patent RU 2089948 (G21F 5/008, 1997), containing gas pipelines connected by an annular collector placed inside a concrete filler. In this case, the gas pipelines and the collector are made in the form of metal cables, and the collector is in communication with the channel, which through the hydrogen-permeable membrane that overlaps it has an outlet to the atmosphere. Thanks to gas pipelines, the metal concrete structure is protected from destruction due to increased hydrogen pressure inside the concrete mass as a result of radiolysis and metal corrosion.

However, the known gas pipelines in the form of metal cables do not imply the possibility of ensuring the effective removal of water and steam from the concrete filler during the drying of concrete.

The closest in technical essence to the claimed invention is a tubular channel for removing gases from a concrete filler, described in the description of the invention according to patent RU 2082232 C1 (G21F 5/008, 1997). Known tubular channel contains a perforated tubular element, monolithic in a metal concrete (reinforced concrete) structure. In the known technical solution, the tubular channels monolithic in the metal concrete structure are combined into a prefabricated collector, which through the bursting safety membrane has an outlet to the atmosphere to remove gas and vapors from the concrete filling when the metal concrete structure enters the fire. In this way, concrete is protected from destruction upon rapid exposure to high temperatures.

The disadvantages of the known tubular channel include the possibility of clogging the tubular element with cement paste through perforation in the process of concreting a metal-concrete structure.

The problem solved by the present invention is to create a tool that would allow high-temperature drying of heat-resistant concrete masses enclosed in a confined space, where the greatest threat to the integrity of the structure is an increase in the pressure of water vapor (vapor-gas mixture) generated during the drying of the concrete aggregate.

This technical problem is solved by the fact that the known tubular channel for removing water, steam and gases from the concrete filler, containing a tubular element monolithic in a metal concrete structure, according to the invention as a tubular element contains an unpressurized flexible corrugated metal sleeve, on the outside of which a protective filter coating in the form of a spiral-woven woven asbestos tape, which is impregnated with a solution that slows down the hardening of cement stone.

In an embodiment, the cement stone hardening solution is a dextrin solution.

Along with this, the tubular element can be made perforated.

The technical result of using the invention is to enable the effective removal of water, steam and gases from the concrete filler during high-temperature drying of the heat-resistant concrete mass, which ultimately improves the reliability of metal-concrete (reinforced concrete) structures operating at high temperatures.

In FIG. 1 schematically shows a flexible corrugated metal sleeve with a protective filtering coating, general view, longitudinal section; in FIG. 2 is the same, cross-section along AA in FIG. one; in FIG. 3 - clearance in the pair of corrugations of the metal sleeve, element B in FIG. one.

In an embodiment of the invention, the proposed tubular channel is used in a system for removing water, steam and gases from a concrete filler, for example, a metal concrete case of a nuclear power plant (NPP). Using a tubular channel, water and steam are removed to eliminate excess pressure that occurs at elevated temperatures during the drying of the concrete mass.

The tubular channel contains a tubular element 1, monolithic in the metal-concrete structure of the NPP housing (not shown in the drawing). The tubular element 1 is an unpressurized flexible corrugated metal sleeve, on the outside of which a protective filtering coating is applied 2. The latter is made in the form of a spiral-wound woven asbestos tape, which is impregnated with a solution of dextrin. In an embodiment of the invention, the asbestos tape is impregnated and dried after winding the corrugated metal sleeve 1 onto the metal sleeve from particles of cement paste falling into the sleeve during the concreting of the NPP case. Impregnation of a woven asbestos tape with a dextrin solution eliminates the hardening of cement paste when it is impregnated with asbestos filaments. As a woven asbestos tape, for example, a woven asbestos tape with a thickness of 0.5 mm (LAT 05X30 GOST 14256-2000, temperature resistance up to + 400 ° C), impregnated with a 20% dextrin solution (GOST 6034-74) can be used. As a metal sleeve 1 can be used, for example, a flexible metal leak-proof sleeve P3-C according to TU 4833-019-29124208-00. The metal sleeve 1 can be made of a thin steel strip with a thickness of, for example, 0.2 mm by corrugating it and spiral winding on a mandrel on a rolling mill. In an embodiment of the invention, the sleeve is made in the form of a spiral-wound pipe from a pre-U-shaped profiled metal strip. Since a sufficiently thin tape is used for the manufacture of the metal sleeve, the profile of the tubular channel has considerable flexibility, both in axial and radial directions. A characteristic design feature of an unpressurized flexible corrugated metal sleeve is a spiral vertical gap between adjacent corrugations (in an embodiment of the invention, for example, with a pitch of 3.75 mm for a sleeve with a conditional passage D _y = 15 mm). Through this gap, the passage of water and steam is provided in the amount necessary for drying the concrete filler of the metal-concrete housing of the nuclear power plant. The winding step of flexible metal unsealed sleeves can be made sufficiently small, which ensures high uniformity in the distribution of the living cross section of the spiral gap along the length of the tubular channel. This circumstance ensures the uniformity of removal of the vapor-gas mixture from the protective and filtering coating 2.

In an embodiment (not shown), the corrugated metal sleeve 1 is perforated with holes (for example, 2 mm in diameter) made in the hollows of the sleeve.

In an embodiment of the invention, the proposed tubular channel is used to remove water, steam and gas from a concrete filler, for example, a metal concrete housing of a nuclear power plant (i.e., from a concrete array enclosed in metal shells) and works as follows.

Concreting of the metal-concrete housing of the nuclear power plant is carried out sequentially with layers of various thicknesses (for example, from 400 mm to 2000 mm), onto which the tubular channels 1 of the drying system (not shown) are laid. Tubular channels are removed from each of these layers and are collected in a corresponding annular collector. The annular collector of the lower concrete layer is prefabricated (common) for all concrete layers. With the upstream annular manifolds, the prefabricated annular manifold is communicated through risers, through which the vapor-gas mixture enters the lower annular manifold. Ring collectors and risers are structurally similar to horizontally located tubular channels. Thus, all tubular channels communicate with each other. The position of the flexible metal hoses is fixed using appropriate fasteners, for example, to reinforcing bars located at a given pitch in a concrete massif, or to an already hardened concrete layer. After concreting, tubular channels, monolithic in the metal structure of the nuclear power unit housing, form a system that provides for the collection and removal of moisture released during the drying of the concrete mass.

Drying of the entire concrete mass is carried out in a single heating cycle after 28 days of exposure after the last concreting (after reaching the brand strength with the last concrete layer). The drying of a concrete filler in a metal-concrete case is a combination of two simultaneously proceeding processes:

- heating of the metal-concrete case with the help of a heating pipe system according to a given program to a temperature, for example, 420 ° C;

- removal of concrete, water, steam and gases generated during the drying process.

The concrete mass is heated by supplying hot air through the pipelines of the case heating system (not shown in the drawing) with stepwise heating of the case to a predetermined temperature and prolonged exposure of the heated concrete aggregate at each stage of its heating. At the same time, free and adsorption water turns into saturated steam in the pores of concrete. Steam and associated gases, under the influence of the resulting pressure gradient, diffuse in the direction of the protective and filtering coating of 2 tubular channels (i.e. towards lower pressure), placed in the concrete mass. Then, water, steam and gases through spiral vertical gaps between adjacent corrugations of metal sleeves 1 enter the latter and then through tubular channels to the corresponding collectors, they are collected in a prefabricated collector, from where they are removed using, for example, vacuum pumps (not shown in the drawing).

Thus, due to the peculiarities of the execution of the tubular channel, monolithic in the metal concrete structure, the invention provides the ability to effectively remove water, steam and gases from the concrete filler during high-temperature drying of the heat-resistant concrete mass, which ultimately improves the reliability of metal-concrete structures operating at high temperatures.

Claims (3)

1. A tubular channel for removing water, steam and gases from a concrete filler, comprising a tubular element monolithic in a metal concrete structure, characterized in that the tubular element contains an unpressurized flexible corrugated metal sleeve, on the outside of which a protective filtering coating is applied in the form spiral wound asbestos tape, which is impregnated with a solution that slows down the hardening of cement stone. 2. The tubular channel according to claim 1, characterized in that the solution that slows down the hardening of the cement stone is a dextrin solution. 3. The tubular channel according to claim 1, characterized in that the tubular element is perforated.

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