EP2015935A1

EP2015935A1 - Pressure-resistant body that is supplied with fluid

Info

Publication number: EP2015935A1
Application number: EP07728989A
Authority: EP
Inventors: Karl Maile; Karl Berreth; Abram Lyutovich; Roland Weiss; Thorsten Scheibel; Marco Ebert; Martin Henrich; Andreas Lauer
Original assignee: Schunk Kohlenstofftechnik GmbH
Current assignee: Schunk Kohlenstofftechnik GmbH
Priority date: 2006-05-10
Filing date: 2007-05-10
Publication date: 2009-01-21
Also published as: KR20090019823A; CN101448636B; CN101448636A; CA2651100C; US20090101658A1; JP2009536297A; JP5249924B2; DE102006038713A1; CA2651100A1; WO2007128837A1

Abstract

The invention relates to a pressure-resistant body (10), such as a pressure pipe or pressure container, consisting of a steel base body (12), a first layer (14) of a ceramic fibre composite that surrounds the exterior of the base body and at least one second layer (16) of a fibre-reinforced plastic and/or a fibre-reinforced ceramic that is situated on the first layer.

Description

Pressure-resistant fluid-loaded body

The invention relates to a pressure-resistant fluidbeaufschlagbaren or -ten body such as pressure tube or pressure vessel.

For steam turbine processes, the efficiency depends on the process temperature. Therefore, one strives to set the process temperature as high as possible. According to the state of the art, pressure-resistant bodies, such as pressure pipes or pressure vessels, required for steam turbine processes, are produced from martensitic steels or high-alloy nickel base alloys. With these materials, process temperatures up to 650 ⁰ C and 700 ⁰ C can be achieved. However, for martensitic steels usually a temperature of more than 620 ⁰ C is not exceeded for safety reasons.

The used bodies of the aforementioned steels withstand pressures of up to 300 bar. Higher temperatures and pressures are not feasible, because of the required resistance to the material creep behavior, not feasible for safety and economy.

The present invention has the object, a pressure-resistant fluidbeaufschlagbaren or -ten body such as pressure tube or pressure vessel in such a way that an increase in the process temperatures compared to bodies, which consist of steels, is achieved. Also, the body should be acted upon with pressures that are greater than those previously used are usually used To achieve the object, the invention proposes essentially in front of a pressure-resistant fluidbeaufschlagbaren or -ten body such as pressure tube or pressure vessel consisting of a base body made of steel, a body surrounding the outside first layer of ceramic fiber composite material and one or more arranged on the first layer second layers made of fiber-reinforced ceramic and / or fiber-reinforced plastic.

Fluid-impingable bodies according to the invention, such as pressure pipes or pressure vessels, make it possible to increase the process temperatures in comparison to bodies which consist solely of steels. Also, the possibility of pressurization is given, which is larger than usual. This is done according to the invention by the function separation tightness and emergency property of the steel pipe on the one hand and the high temperature creep resistance of the fiber composite material on the other.

According to the invention, a multi-layer body is provided which, in particular in steam turbine processes, offers the possibility of increasing the process temperature by at least 200 ^° C. compared with the materials used hitherto, so that the thermal efficiency in power stations can be increased by approximately 7%. A corresponding composite tube shows good compressive and tensile stress in the axial and radial directions and a temperature resistance up to in the range between 900 ⁰ C and 1000 ⁰ C. The existing of fiber composite material first layer acts insofar thermo-insulating, ie generates a temperature gradient of the steel pipe in the outer layer so that it does not oxidize. Also, an economical production is possible.

Although it is known to use ceramic fiber composites (CMC) at high temperatures. Thus, CMC materials for gas turbines in the field of hot gases, so the turbine combustor, the static, the gas flow directing vanes and the actual turbine blades that drive the compressor of the gas turbine used. However, the corresponding components consist exclusively of CMC materials and do not have the layer structure according to the invention. However, this ensures that use at high temperatures up 1000 ⁰ C and pressures of 300 bar and more can be done easily, at the same time a creep resistance of the body is guaranteed by at least 30 years.

The thermal fiber composites are characterized by an embedded between ceramic fibers, especially long fibers, embedded matrix of ceramic, which is reinforced by the ceramic fibers. Therefore one speaks of fiber-reinforced ceramics, composite ceramics or simply fiber ceramics. In principle, matrix and fiber may consist of all known ceramic materials, in which context carbon is also treated as a ceramic material.

In particular, it is provided that the fibers of the ceramic composite material are alumina, mullite, silicon carbide, zirconia and / or carbon fibers. Mullite consists of mixed crystals of alumina and silica.

The ceramic fiber composite used is preferably SiC / SiC, C / C, C / SiC, Al ₂ O ₃ / Al ₂ O ₃ and / or mullite / mullite. In this case, the material before the slash designates the fiber type and the material after the slash designates the matrix type. As a matrix system for the ceramic fiber composite structure and siloxanes, Si precursors and various oxides, such as zirconia, can be used.

The first layer preferably has a thickness D _{1 of} 1 mm <D ₁ <20 mm and / or the second layer or layers has a total thickness D _{2 of} 0 mm <D ₂ ≦ 50 mm.

In order to achieve a desired reinforcement by the at least one second layer, the fibers of the fiber-reinforced carbon can be arranged radially encircling and / or crossing on the first layer. The fibers of the first layer can likewise be deposited radially on the base body and / or crossing each other. The main body preferably consists of martensitic steel or high-alloy nickel-based alloy material. In this case, wall thicknesses D ₃ with 2 mm <D ₃ <50 mm are to be specified as preferred values, without thereby restricting the teaching according to the invention.

The fiber volume Fv of the first layer should be 30% <F _v ≦ 70%. Preferably, the porosity P of the first layer is 5% <P <50%.

The ceramic fiber composite material can be produced by CVI (Chemical Vapor Infiltration) method, pyrolysis, in particular LPI (Liquid Polymer Infiltration) method or by chemical reaction such as LSI (Liquid Silicon Infiltration) method.

Preferably, an Si-based precursor is used as the matrix material, to then be converted into SiC by pyrolysis. Si-based precursors have the advantage that they are readily hardenable and pyrolyzable, so that problem-free production is ensured.

The invention is also characterized in a very general way by a pressure-resistant body which can be acted upon by fluid or pressure vessel or pressure vessel consisting of steel and a layer surrounding the basic body consisting of or containing fibers which at a temperature T with T> 500 ^° C. is no or show minimal creep strain.

It creep-resistant fibers are used, ie fibers in the creep - in the temperature range above 550 ⁰ C - show no or minimal increase in time of permanent deformation, so the creep, whereby the creep of the inner steel tube is stopped. Chemically, the fibers are characterized by a high creep strength to the effect that the strength is ensured in particular under atmospheric air at high operating temperatures. Suitable fibers are reinforcing fibers which fall into the classes oxide, carbide, nitridic fibers or C fibers and SiBCN fibers. Plastic fibers such as PAN fibers or polyacrylonitrile fibers are also referred to as reinforcing fibers.

Further details, advantages and features of the invention will become apparent not only from the claims, the features to be taken from them-alone and / or in combination-but also from the following description of preferred embodiments to be taken from the drawings.

Show it:

Fig. 1 is a schematic diagram of a pressure tube and

Fig. 2 is a schematic diagram of a container.

In Fig. 1, a pressure tube 10 is shown in sectional view, which is used in particular in the power plant area for steam turbine processes used. In order to let the pressure tube 10 of fluids flow under pressures of up to 300 bar or more at temperatures of 800 °, in particular 850 ° or more, the tube 10 is formed as a composite tube. The tube 10 consists of a base body 12 made of steel, on which at least two layers 14, 16 are applied. Here, the arranged on the base body 12 layer 14, which is referred to as the first layer, made of a ceramic fiber composite material and the at least one first layer 14 covering the second layer 16 of fiber-reinforced plastic and / or fiber-reinforced ceramic. The plastic content serves to increase the expansion compatibility.

The ceramic fiber composite material of the first layer 14 may consist of known ceramic materials, wherein preferably SiC / SiC, Al ₂ O ₃ / Al ₂ O ₃ or mullite / mullite are mentioned. The first layer 14 of the ceramic fiber composite material ensures that a thermal insulation between the main body 12 and the at least one second layer 16 of the fiber-reinforced plastic, be it fiber-reinforced plastic, be it fiberglass-reinforced plastic, is built up to such an extent that oxidation of the at least one second layer 16 is prevented. This ensures that the at least one second layer 16 provides the desired reinforcement, so that the composite pipe 10 can be acted upon by the desired high pressures. The second layer is also responsible for generating the bias on the pressure tube or pressure vessel, which increases with increasing application temperatures.

For prestressing, it should be noted that this arises during start-up with increasing pressure and temperature in the fiber casing and is degraded over time in part by the creep behavior of the inner jet pipe in a time-dependent manner.

The first layer 14 allows the composite pipe 10 to increase the efficiency with the required high temperatures of at least 800 ⁰ C - 850 ⁰ C, optionally applied to 1000 ⁰ C.

The fibers of the first layer 14 may be deposited according to the requirements. Thus, the fibers may be crossing and / or surrounding the main body 12 radially surrounding. The same applies with regard to the fibers of the at least one second layer 16.

In Fig. 2, a pressure vessel 18 is shown purely in principle, which is also composed of a base body 20 made of steel and arranged on the base body 20 first and second layers 24, 26, wherein the first layer 24 of a ceramic fiber composite material and the at least one second Layer 26 consists of fiber-reinforced plastic and / or fiber-reinforced ceramic. In this case, manufacturing methods and materials can be used, as they have been previously explained. By way of example, FIG. 2 shows fibers 28, 30 of the first layer 24, which are deposited radially on the base body 22 (long fibers 28) or intersecting (long fibers 30). Other fiber processes known from the prior art are also possible. In the embodiment of Fig. 1, the base body 12, for example, a clear diameter of 500 mm and a wall thickness of 40 mm. The existing of the ceramic fiber composite material first layer 14 has a thickness D ₁ - IO mm and the second made of fiber-reinforced carbon layer 16 has a thickness D ₂ - IO mm.

In the pressure vessel 20 according to FIG. 2, the base body 22 may have a diameter of 300 mm and a length of 500 mm and a wall thickness of 30 mm. The thickness D _{1 of} the first layer 24 may be D ₁ - IS mm and the thickness D _{2 of} the second layer 26 may be D ₂ - IO mm, to name numbers purely by way of example.

According to the invention, the thickness D of the fiber cladding should behave as the wall thickness d of the pressure vessel 20 as 0.4 d <D <0.6, in particular d / 2 = D.

Respective composite tubes 10 or composite container 20 can be acted upon by fluids at a temperature of about 850 °, so that a high-temperature use, especially in steam turbine processes can take place, which compared to pressure tubes or pressure bodies of conventional construction, the thermal efficiency can be significantly increased. At the same time corresponding composites show a damage tolerant good-natured failure and creep resistance. Compression and tension in both axial and radial directions are possible without damaging the body. Also, an economical production is possible.

Are the embodiments have been explained using a base body with applied on these first and second layers, the invention is also not leave, if only one layer is applied of reinforcing fibers on the base body with no or minimal increase over time in the temperature range above 550 ⁰ C. show the permanent deformation, so the creep, whereby the creep of the inner body is stopped. The corresponding fibers also have a high creep rupture strength, the strength in particular under atmospheric air is ensured at high operating temperatures. Corresponding fibers can be classified into the classes oxide, carbidic, nitridic or C-fibers or SiBCN-fibers. Also plastic fibers such as PAN or polyacrylonitrile fibers come into question.

In particular, the following fibers are mentioned: C-fibers, Nextel fibers, 3M fibers, Hi-Nicalon fibers, oxide fibers, SiO ₂ , Al ₂ O ₃ , SiC, SiBCN, PAN and Si ₃ N ₄ - fibers.

Application example of a corresponding body is z. Example, a boiler tube, which may consist of austenitic or martensitic steel (9% chromium steel), which for example has an outer diameter of about 42 mm and a wall thickness of about 6 mm. This may be wrapped with a layer of previously stated reinforcing fibers having a thickness in the range of 3 mm to 4 mm in order to achieve the desired properties.

Claims

Claims Pressure-resistant fluid-loaded body

1. Pressure-resistant fluidbeauf beatable or -ter body (10, 20) such as pressure tube or pressure vessel consisting of a base body (12, 22) made of steel, the outer body surrounding the outer first layer (14, 24) of ceramic fiber composite material and at least one on the first layer arranged second layer (16, 26) made of fiber-reinforced plastic and / or fiber-reinforced ceramic.

2. Body according to claim 1, characterized in that fibers of the ceramic composite material are alumina, mullite, silicon carbide, zirconia and / or carbon fibers.

3. Body according to claim 1 or 2, characterized in that the ceramic fiber composite material of SiC / SiC, C / C, C / SiC, Al ₂ O ₃ / Al ₂ O ₃ , C / siloxane, SiC / siloxane and / or mullite / Mullite exists.

4. Body according to at least one of the preceding claims, characterized in that the first layer (14) has a thickness D ₁ with 1 mm <D ₁ <20 mm.

5. Body according to at least one of the preceding claims, characterized in that the at least one second layer (16, 26) or the second layers has a total thickness D ₂ with 0 mm <D ₂ <50 mm.

6. Body according to at least one of the preceding claims, characterized in that the fibers (28, 30) of the first layer (14, 24) are radially circumferentially and / or intersecting on the base body (12, 22) are stored.

7. Body according to at least one of the preceding claims, characterized in that the fibers of the at least one second layer (16, 26) with respect to the base body (12, 22) are arranged radially encircling and / or crossing on the first layer.

8. Body according to at least one of the preceding claims, characterized in that the base body (12, 22) consists of martensitic steel.

9. Body according to at least one of the preceding claims, characterized in that the base body (12, 22) consists of high-alloy nickel-based alloy.

10. Body according to at least one of the preceding claims, characterized in that the base body (12, 22) has a wall thickness D with 1 mm <D <50 mm.

11. Pressure-resistant fluidbeauf beatable or -ter body such as pressure tube or pressure vessel consisting of a base made of steel and at least one surrounding the body layer consisting of or containing fibers that show no or minimal creep at a temperature with T with T> 500 ⁰ C. ,

Body according to at least claim 11, characterized in that the fibers are reinforcing fibers.

13. Body according to at least claim 11 or 12, characterized in that oxidic, carbidic, nitridic fibers, C-fibers, SiBCN fibers, PAN fibers and / or polyacrylonitrile fibers are the reinforcing fibers.

14. Body according to at least one of the preceding claims, characterized in that the fiber layer or fiber layers have a thickness D and the container has a material thickness d with 0.4 d <D <0.6 d, preferably d / 2 = D.