KR20070017941A - Metal dusting resistant product - Google Patents

Abstract

Products are disclosed that are resistant or unaffected to carburization, metal dusting, coking, oxidation, and that have sufficient mechanical strength for use at temperatures above 400 ° C. The product consists of a load-bearing member and a corrosion resistant member, which is a Cu-Al-alloy comprising Si. Also disclosed are uses of products in CO-containing atmospheres, and / or hydrocarbon containing atmospheres or solid carbon containing treatments, and methods for imparting resistance to carburization, metal dusting, coking and oxidation.

Description

Metal Dust Resistant Product {METAL DUSTING RESISTANT PRODUCT}

The present invention is resistant or unaffected to carburization, metal dusting and coking, is oxidation resistant, and has sufficient mechanical strength for use at temperatures and pressures higher than 400 ° C. The present invention relates to a product having the ability to be resistant to or unaffected by the corrosion mode even for a long time. The invention also relates to the use of said product in the production of components in a CO-containing atmosphere and / or a hydrocarbon-containing atmosphere or a solid-carbon-containing treatment.

Over the years, the development of reforming processes in the petrochemical industry has greatly improved the treatment efficiency. An example of this is the development of large pore zeolite catalysts doped with specific metals that impart high selectivity to the catalysts, making them suitable for accurate modification and / or synthesis. This has enabled more effective and economical production of a wide range of high demand commercial liquids based on hydrocarbon feedstocks. However, it was soon found that the catalyst was susceptible to sulfur poisoning. To overcome this drawback, techniques have been developed to desulfurize hydrocarbon feeds. Later, such catalysts were also found to be rapidly deactivated by water, so that corresponding protection techniques have been developed to lower the content of water in the process gas stream.

Conditions of small amounts of low-sulfur and small amounts of water include plugging and coke-forming in the reactor system; A severe form of disintegrating on construction metals, which subsequently severely negatively affects part of the device, such as tube piping in the furnace, reactor walls, for example by shortening the service time of the entire plant. induces an action that has been found to be related again. This metal deposition mechanism is known as "metal dusting" since the 1940s. Metal dusting is known to be prevented if sulfur is present in the carbon containing gas. Increasing environmental and environmental requirements for the newly developed catalysts have led to the need for small amounts of sulfur, which increased metal dusting related failures.

As mentioned above, metal dusting is a form of catastrophic carburization in which metal is rapidly broken down into coke and pure metal or other forms of metal rich reaction products. In this case, metal dusting means a treatment in which the metal or alloy is attacked by a carbon rich gas and eroded into a mixture of coke / carbon and metal rich particles. Metal dusting generally occurs in a gas that is initially supersaturated for carbon, i.e., has a carbon activity greater than unity. Corrosion products of metal dusting are metal rich and carbon rich compounds. Carbon rich compounds are generally in the form of coke, ie, solid carbonaceous precipitates which may include, for example, various concentrations of hydrogen, nitrogen, oxygen, and the like. Metal rich compounds may vary depending on, for example, the oxygen content and alloy composition of the system, and the operating temperature and pressure. Typical metal rich compounds are oxides of metal carbides, metal alloys in which carbon is dissolved, and component metals of the alloys.

Metal dusting occurs very generally when the carbon containing gas is cooled from high temperatures that are at or near equilibrium. Usually this equilibrium is reached with the aid of a catalyst, which means that at initial equilibrium, the gas phase reaction rate is low. During cooling, the gas will not be able to equilibrate due to slow kinetics, as a result of which the gas is strongly carburising. In most applications where metal dusting is a problem, such as for example in stream reforming applications, the gas is cooled to maintain the equilibrium obtained on the catalyst at high temperatures. Therefore, it is an indispensable characteristic of this treatment that metal dusting can occur, and it is impossible to design the treatment to completely avoid metal dusting, carburizing or coking. Thus, according to P. Szakalos, "Mechanisms of metal dusting on stinless steel", Licenciate thesis, 2002, ISBN 91-7283-260-6, metal dusting is a waste heat boiler, stream It is contemplated that this will occur in the components where the gas is cooled, such as superheaters, and in the heat exchange reformer unit. The temperature range in which metal dusting is most likely to occur is 400-800 ° C., but it can also occur at higher temperatures.

Atomized metal particles produced by metal dusting move with the process gas, accumulating downstream on various reactor parts and throughout the entire reactor system, and transition to catalysis coking that can form obstacles. Can be

Metal dusting is of great interest in the production of hydrogen and syngas (H ₂ / CO mixtures). In these plants, methane and various other high hydrocarbons are modified or partially oxidized to produce varying amounts of hydrogen and carbon monoxide for use in preparing other high molecular weight organic compounds. In conditions prone to metal dusting, when the reaction and heat-recovery efficiency of the treatment are increased, a work processing apparatus is required.

Due to the need for increased heat recovery in the ammonia-synthetic treatment, metal dusting problems arise in the heat-recovery section of the modified gas system and in the reformer itself.

Metal dusting is also a problem in direct iron-ore reduction plants where the modified methane is dried and reheated in order to increase the ore-reduction efficiency. Metal dusting occurs in the reformer, the reformed gas reheater, and the ore-reducing upstream piping.

Metal dusting also occurs in the apparatus for handling items to be treated (annealed, carburized) in the heat-treating industry. The gases used for the heat treatment are mixed with oil residues on the item to form a gas that is chemically vulnerable to metal dusting. In addition, the gas mixtures used for carburizing may cause metal dusting if the treatment chemistry is not controlled. Also in petroleum refineries, metal dusting occurs in treatments involving hydro-dealkylation and catalytic regeneration systems of "plat-former" units.

Other treatments in which metal dusting occurs are fired heaters, which treat hydrocarbons at elevated temperatures, in recycle-gas loops of coal-gasification units, and iron-making blast furnaces in steel mills. making blast furnaces), and in nuclear fuel cells using molten salts and hydrocarbons, a nuclear plant that uses carbon dioxide to cool the device.

In recent years, the development of reforming and synthesis techniques has been greatly emphasized to enable the commercialization of remotely located, “stranded gas reserves”. Synthetic steps based on further developments of Ficher-Tropsch treatment have led to the use of synthetic gas compositions with lower stream-to-carbon ratios and higher CO / CO ₂ ratios, leading to very severe metal dusting. Will require, which will cause severe metal dusting. However, there is no material with sufficient resistance to metal dusting, so only a few methods have been sought for development in this direction.

The solution used nowadays to provide protection against metal dusting and to reduce coke formation is to use advanced nickel- or iron-based alloys with a high content of certain adducts of chromium and aluminum. Several surface modification methods have been tested, based on diffusion coating techniques or coating by overlay welding, laser diffusion, chemical vapor deposition (CVD), physical vapor deposition (PVD) or sputtering. Many of these methods include elements based on transition metals, such as iron, nickel and cobalt, which are known for their catalysis properties in terms of promoting their coke formation.

There are metals such as Cu and Sn which are known to be resistant or unaffected to carburization and coke formation. Sn has a melting point that is too low to be used at temperatures higher than 300 ° C., and both Cu and Sn are insufficient in oxidation resistance for use in high temperature applications. This oxidation resistance is required when solid coke is periodically removed by oxidation in the stream and in the air. As a result, the metal surface in contact with the carburized gas must also have adequate oxidation resistance. In most applications, this excludes Sn alloys and pure Cu and low alloyed Cu as useful alternative carburizing-resistant materials. Although the decoking step may be excluded in some treatments, the start-up procedure after irradiation or other interruptions in operations that cause temperature and pressure changes will be easier by using alloys with specific oxidation resistance. . In addition, treatment variations in temperature and feedstock quality and the action of the upstream treatment apparatus can contaminate the treatment gas with, for example, sulfur, chlorine, alkali metal compounds, water vapor and / or oxygen. Copper alloys that are not protected by any oxide on the surface can thus be affected by significant corrosion and erosion. In addition, chromium-containing copper alloys protected by chromium oxide may be damaged by the compound, because oxidation resistance to chromium oxide is limited. Finally, copper, even at high tin, has a high vapor pressure at temperatures above 500 ° C. As a result, when these elements are present on the metal surface, the vapors of the elements are transferred into the treatment system, for example It can lead to contamination of the construction material, process fluid and catalyst and loss of thickness of the protective material.

There are existing techniques for coating construction materials with thin layers of resistant or unaffected metals such as Sn, Cu or coking-resistant metals and are described in US-A-5,863,418 and EP-A-09003424 and WO 03014263 A1. have. This thin layer of about <200 μm thickness will be consumed by metal loss due to wear and evaporation, and by reaction with the construction material, resulting in inadequate service life at temperatures above about 500 ° C. Periodic recoating of surfaces exposed to corrosive gas requires scrubbing the treatment apparatus to clean the surface to be coated and finally coat it or recoat it in the treatment apparatus. The first method requires a long shut-down period, and the second is the high cost of the method for in-situ cleaning and coating that does not exist today, and to confirm the integrity of the film produced. Requires redesign and development Therefore, periodic recoating of thin coatings will not be feasible technically and commercially.

"THE ALUMINIUM BRONZES", MACKEN, PJ, SMITH, AA, COPPER DEVELOPMENT ASSN., 55 SOUTH ARDLEY STREET, LONDON W.1, SECOND PUBLICATION 1966, CDA PUB.NO.31, 263 PP; 1966 Alternative methods of constructing solid Cu-based members are pressurized components, which, due to the low mechanical strength of copper alloys at temperatures above 400-500 ° C., must maintain their structural integrity in some other way throughout their entire service life. Or for the components, it is not an option at temperatures higher than about 500 ° C.

Thus, the use of such a temporary solution will not address the secondary damage associated with the uncertainty of the working concept, such as the foreseeable maintenance cost, and the occurrence of metal dusting attacks on the processing apparatus, which are currently prevalent.

Thus, the use of this temporary solution reduces the requirements for hydrocarbon feedstocks and consequently reduces greenhouse gas emissions, thereby lowering the operating costs and investments of emerging energy efficient reforming design solutions, namely petrochemical and chemical plants, and the environment. It is not believed to support the widespread industrial acceptance of designs that are set up to increase sustainability.

This solution, in particular characterized by a thin coating on the load-carrying component or construction material, is temporary and substantially different from this solution in this specific respect.

Accordingly, it is an object of the present invention to provide a CO-containing atmosphere, and / or a hydrocarbon containing atmosphere, or gasification of a solid carbonaceous material, pyrolysis and catalytic reforming of hydrocarbons, in particular small amounts of sulfur, and small amounts. It is to provide a copper-based alloy according to claim 1 for use in solid carbon containing treatments, such as catalytic reforming under conditions of sulfur and small amounts of water.

Another object of the present invention is to be resistant or not resistant to oxidation, in particular a CO-containing atmosphere, and / or a hydrocarbon containing atmosphere or a solid carbon containing treatment, ie vaporization of a solid carbonaceous material, pyrolysis and catalysis modification of hydrocarbons. To provide a product which is particularly resistant to treatments such as catalytic reforming under conditions of small amounts of sulfur and small amounts of sulfur and small amounts of water.

It is another object of the present invention to provide an article having a surface that is not capable of catalyzing the formation of solid coke.

Another object of the present invention is to provide a CO-containing atmosphere, and / or a hydrocarbon containing atmosphere, or vaporization of solid carbonaceous materials, pyrolysis and catalysis modification of hydrocarbons, in particular small amounts of sulfur, and small amounts of sulfur and small amounts of water. To provide a product that is resistant or unaffected to carburization, metal dusting and coking for use in solid carbon containing treatments, such as catalysis modifications under.

It is another object of the present invention to provide a product that is resistant to high gas velocities and material loss due to wear or abrasion due to suspended particles in the process gas stream.

Another object of the present invention is to provide a product in which a Cu-based alloy that is resistant or unaffected to carburization, metal dusting and coking, can be used at a temperature at which the copper-based alloy itself has a very low mechanical strength. It is.

Another object of the present invention is to provide a copper-based alloy as a component of the composite material, in order to use at a temperature of 450-650 ° C. in the composite formation with a minimum thickness of 0.5 mm or more of the corrosion resistant component, and the composite For use at temperatures above 650 ° C. in the formation, the minimum thickness of the corrosion resistant components is to be provided at least 0.1 mm.

It is a further object of the present invention to provide a load bearing structural member and to impart a long service life in commercial applications, in particular to articles produced accordingly.

 Another object of the present invention is to provide a product which is resistant to material loss due to copper evaporation.

These objects will be met by using products composed of two or more different alloys as described below. Different alloys have to meet different requirements: first is a load-bearing member, which provides the mechanical stability necessary for the temperature and pressure required for processing. Surfaces exposed to metal dusting, carburization and coking environments are applied with a sufficiently thick layer of corrosion resistant member.

 The corrosion resistant member is formed of a Cu—Al based alloy having the following composition (wt%): Al: 2-20 wt%, preferably 4-9 wt%.

The alloy may contain additional elements to optimize oxidation resistance or fabricability: Si:> 0-6% by weight, preferably 0.05-5% by weight, more preferably 0.5-3% by weight , Most preferably 0.5-2% by weight.

Total of Fe, Ni, Co, Mn: 0-20% by weight. In order to optimize resistance to metal dusting, the sum of Fe + Ni + Co + Mn should be 6.0 wt% or less and the amount of any individual element should be 4.0 wt% or less. Most preferably, the sum of Fe + Ni + Co + Mn should be 1.0 wt% or less. The action of the different alloy adducts is described in more detail below, specifically in the section on corrosion resistant Cu—Al based alloys.

The load-bearing member and the corrosion member can be mechanically coupled. However, in order to complete the entire product structurally and to ensure sufficient thermal conductivity across the walls of the product, different members must be joined with metallurgical bonds along the entire contact surface. The required thickness of the corrosion resistant member is determined by material loss due to evaporation, oxidation wear, and diffusion into the load bearing component and diffusion into the corrosion resistant alloy from the load bearing component. When the thickness of the corrosion resistant alloy is too thin, the diffusion treatment described in FIG. 1 subsequently degrades the corrosion resistance of the product. Therefore, if the product is to be used for a long time at a temperature higher than about 700 ° C, the corrosion resistant alloy should have a thickness of 1 mm or more. If there are additional degradation mechanisms such as copper evaporation and abrasion, even in the 450-700 ° C. temperature range, the minimum thickness is 1 mm. In the absence of such a mechanism, a thickness of 0.5 mm is available at temperatures below 650 ° C.

Load-supporting member

The load-bearing member is composed of an alloy having proven high temperature strength, for example, UNS N08810, UNS N08811, UNS N06600, NUS N06601, UNS 34709 and the like. The alloy used is a product's operating conditions in terms of temperature, pressure drop across the wall of the component, the total load of the product defined as the sum of the loads from the load-bearing member weight, and the weight of the corrosion-resistant Cu-based alloy. In order to have a sufficiently high mechanical strength. In addition, in its as-delivered condition, it is required to use alloys that meet the corresponding legal and standardization requirements (eg pressure vessel approval). In addition, if the surfaces of the load-bearing members are not all coated with a corrosion resistant alloy, the alloy itself is required to have sufficient corrosion resistance to the environment to which it is exposed.

Corrosion resistance

CO-containing atmosphere, and / or hydrocarbon containing atmosphere, or solid carbon such as gasification of solid carbonaceous materials, pyrolysis and catalytic reforming of hydrocarbons, in particular small amounts of sulfur, and catalytic reforming under small amounts of sulfur and small amounts of water For use in containing treatments, the surface of the product exposed to carburization, metal dusting and coking is coated with a Cu-Al alloy, which may contain additional elements to enhance its properties. In order to use the composite form as described herein at a temperature of 450-650 ° C., the minimum thickness of the corrosion resistant member should be at least 0.5 mm. For use at temperatures above 650 ° C, the minimum thickness of the corrosion resistant components must be at least 1.0 mm.

In the following, the action of the different alloying elements in the corrosion resistant alloy is described in detail.

aluminum

Aluminum is a necessary component in the alloy due to its ability to form a protective alumina layer on the alloy surface in the temperature range of 300 ° C to 1300 ° C, even in an environment containing only trace amounts of oxygen. Aluminum can be added in amounts up to about 9% by weight without significantly degrading the mechanical properties. This level is considered sufficient to achieve the required corrosion resistance for most of the applications considered. If necessary, a high Al level is used, in which case the ability to cold form the alloy is limited. However, this level is available for example in hot-extruded sections or hot-rolled rods or plates such as circular tubes. Aluminum should be added in an amount of up to 20% by weight, preferably up to 13% by weight, most preferably up to 9% by weight, and at least 2% by weight, preferably 4% by weight.

silicon

Silicon can be used to promote the protective effect of aluminum in this type of alloy by forming aluminum silicates. In this type of alloy, lower starting temperatures for the formation of protective oxides are preferred. Thus, silicon can be added to the alloy to promote oxide formation at low temperatures, especially when the content of Al is lower than about 8%. However, silicon has the effect of greatly reducing the melting point of the alloy. The substantial maximum content of silicon is 6%.

Therefore, the content of silicon in the alloy is> 0-6%, preferably 0.05-5%, more preferably 0.5-3%, most preferably 0.5-2%.

Nickel, iron, cobalt, manganese

Transition metals, in particular iron, nickel and cobalt, are known to have strong catalysis for coke formation. Due to the protective ability of the alumina layer to be formed on the surface of the alloy, proportionally high levels of these elements are possible, but the sum of iron, nickel and cobalt is up to 20% by weight.

Nickel and trace cobalt,

Increasing the maximum service temperature by increasing the melting point of the alloy to about 1100 ° C., followed by

Making a production method comprising the steps through a temperature above the melting point of the binary Cu—Al alloy, about 1030-1080 ° C.,

At elevated temperatures of about 800 ° C. to about 1100 ° C., to enhance the mechanical strength of the alloy.

Increasing the content of nickel, cobalt, iron and / or manganese improves carburization tendency and reduces resistance to metal dusting and coking. Therefore, the content of these elements should be kept as low as possible, but effective production methods should still be available. The maximum practical value expected to prevent corrosion deterioration is 20% by weight. Nickel in the alloy may be replaced in whole or in part with iron and / or cobalt.

Pure Cu—Al—alloys according to the invention have a melting point of 1030 ° C. to 1080 ° C., depending on the Al content. If optimum resistance to metal dusting and coking is required, the content of each of the elements in the Fe, Mn, Ni and Co groups should be no greater than 4.0% by weight per element. In this case the total content of these elements should not exceed 6.0% by weight, preferably not greater than 1.0% by weight.

Iron can be used to enhance the high temperature working properties of the Cu-Al alloy and therefore it can be added in amounts of up to 10% by weight, preferably up to 5% by weight and most preferably from 0.5-4% by weight. .

Reactive additives

To further increase the oxidation resistance at high temperatures, it is common to add certain amounts of reactive elements such as rare earth metals (REMs), for example yttrium, hafnium, zirconium, lanthanum and / or cerium. At least one of these elemental groups should be added in an amount of no greater than 1.0% by weight per element. The total content of these elements should not exceed 3.0% by weight, preferably should not exceed 0.5% by weight, most preferably 0.01-0.2% by weight.

Copper

The main component of the remainder of the alloy of the invention is copper. Copper is known to be resistant or not tolerant to catalytic activity and coking. To date, it has not been possible to use pure copper for these applications because of its high rate of oxidation upon contact with oxygen. The alloy comprises up to 98% by weight Cu, but at least 60% by weight Cu, preferably at least 74% by weight and most preferably at least 80% by weight Cu.

It will be apparent to those skilled in the art that replacing part of Cu with Zn will only slightly change the properties of the alloy.

In addition, the alloy comprises common alloy adducts and impurities. These are defined as follows:

Alloy adduct

For example, it is an element added for metallurgical reasons of treatment for melt purification from S or O, or to enhance the workability of cast material. Examples of such elements are B, Ca, Mg. In order that these elements do not have a deleterious effect on the alloy properties, the level of each individual element should be 0.1% or less.

In addition, several of the aforementioned elements, for example Al, Si, Ce, Fe and Mn, may be added for reasons of treatment metallurgy or high temperature workability.

Permissible concentrations of these elements are as defined in the previous section.

impurities

Impurity means that elements from contaminants in the scrap metal used for contamination or melting from the processing apparatus are undesirably added.

The products according to the invention can be machined or manufactured into composite construction materials in the form of tubes, pipes, plates, strips or wires by conventional metal working or metal forming treatments. It can also be prepared by depositing a corrosion resistant alloy on the surface or surfaces of a semi-finished load bearing alloy article using known deposition techniques.

FIG. 1 shows the theoretical diffusion profiles of Cu and Al after 5 years exposure of a Cu-8% Al film having an initial thickness of 200 μm at 750 ° C. FIG.

FIG. 2 shows the weight loss of some of the comparative samples and one embodiment of the present invention after exposure at 650 ° C. over a period of 1000 hours (4 cycles in RT) in 25CO + 3H ₂ O + H ₂ .

FIG. 3 shows the oxidation weight change during air exposure at 850 ° C. for seven different corrosion resistant CU-Al based alloys.

4 shows the partial pressures of CO molecules having different isotopic compositions in a furnace maintained at 650 ° C. containing alloy Q pieces.

FIG. 5 shows the partial pressures of CO molecules with different isotopic compositions in an empty furnace maintained at 650 ° C. FIG.

FIG. 6 shows the sections in the Cu-Ni-Al phase diagram calculated by Thermo-calc for a given Al-content of 8% by weight. 1-liquid, 2-AlNi, 3-FCC, 4-BCC.

FIG. 7 shows solubility (g carbon / g alloy) of carbon in alloys having 4 wt% Al and various Cu—Ni relationships at 750 ° C. FIG.

Examples 1 to 5 show the corrosion resistance of Cu-based alloys, in particular their ability to form protective oxides having their resistance to metal dusting, carburizing and coke formation and excellent self-healing ability It relates to the selection of the composition of the alloy.

Examples 6-9 relate to detailed designs of finished products that meet specific requirements in terms of mechanical properties and corrosion resistance.

Example 1

Static laboratory tests were conducted in an atmosphere tube furnace with a strong coking atmosphere. Metal dusting resistances of standard quality stainless steel and Cu-based alloys A to M according to the invention were measured and evaluated. Table 1 shows the chemical composition of the irradiation material, and Table 2 shows the compositions of Embodiments A to Q according to the present invention. All contents are given in weight percent.

Test samples were prepared by cutting a rectangular shape having a size of about 10 × 12 × 3 mm from a plate or rod and grinding to 600 mesh. Testing a portion of the sample was treated in 50 ℃ 8-40 bun dongan 1.8M HNO ₃ + 1.6M HF from standard pickling (pickling) work as the surface treatment, or electrical polishing (electro polishing) operation (50g CrO ₃ + 450 ml of orthophosphoric acid, 20 V). Samples were washed in acetone prior to testing and placed in a cold furnace. In order to reach a low oxygen partial pressure, pure hydrogen was flushed through the furnace for 3 hours before the reaction gas introduction and temperature heating. The gas flow rate was 250 ml / min, corresponding to the gas velocity on the sample of 9 mm / s. After heating for 20 minutes the temperature stabilized at 650 ° C. The introduction composition of the reaction gas was 25% CO + 3% H ₂ O + 72% H ₂ . Laboratory exposure at 650 ° C./1000 h in a 25 mm diameter quartz tube furnace. In order to increase carbon activity and promote metal dusting initiation, a temperature cycle of lowering to 100-200 ° C. and returning to 650 ° C. was conducted four times, each with a duration of about 4-5 h.

As shown in FIG. 2, after wash | cleaning a sample from coke and graphite, the result is shown as a weight loss measurement value, and this sample was as Table 3 showing.

Comparative example number alloy Product status Surface deformation One 304L rod Annealing 2 304L rod Electro-polishing 3 304L rod Grinding 4 304L rod Pickling 5 304L plate Annealing 6 304L Cold rolled plate Grinding 7 304L Cold rolled plate Electro-polishing 8 800 HT plate Grinding 9 800 HT plate Pickling 10 353 MA plate Overpickled 11 Alloy A plate Untreated

As shown in FIG. 2, all comparative steels (Examples 1-10) were metal dusted with the formation of pits and coke during 1000 h exposure as a function of measurable weight gain. However, the alloy of the present invention (Example 11) was substantially non-reactive in this atmosphere without weight change or coke formation. Example 11 was exposed for a total of 4000 / hour (4 × 1000 h at 650 ° C.) in a similar atmosphere without any measurable or visible change.

Example 2

The alloys according to Examples B-O having the composition according to Table 2 were prepared by melting and casting in argon protective gas atmosphere.

These alloys form protective alumina or mixed aluminum containing oxides when exposed to an oxidizing atmosphere in the temperature range of 300 to 1050 ° C., which inhibits further oxidation of the alloy and inhibits evaporation of copper from the alloy, Through this, the alloy has increased resistance to material loss due to copper evaporation. This is shown in Table 4, which shows the average weight change per hour (g / (m ² h)) after periodic oxidation in air for 7 different Cu based alloys for 48h to 454h and differs at 400 ° C and 550 ° C. It is visualized that there is little difference between the alloys.

Alloy D is clearly inferior to other alloys for oxidation at high temperatures. Oxides formed on Alloy E are susceptible to spattering during cooling from 850 ° C. The good oxidation resistance at 850 ° C. of alloys B, L and N is shown in FIG. 3. The results indicate that optimum oxidation resistance is obtained in an alloy comprising a combination of Al and Si in which at least 9% by weight of Al or Al + 2 * Si (% by weight) is 9 or more. In the latter case, alloy B shows that an Si-content of 1.7 wt% is sufficient to impart adequate oxidation resistance to the alloy with 5.6 wt% Al.

If the Co content of 5% by weight does not deteriorate the oxidation resistance, the oxidation resistance slightly deteriorates with the Co-content of 10% by weight. In addition, 6.3 weight% Mn makes an alloy easy to be oxide spun. Iron and nickel can be considered to have a similar effect to manganese and cobalt on oxidation resistance. Thus, for optimal oxidation resistance, it can be concluded that alloy compositions of 5-12% by weight of Al, 1-3% by weight of Si and less than 6% by weight of Fe + Mn + Ni + Co are preferred.

Example 3

The alloy according to Example Q, having a composition according to Table 2, was prepared by melting and casting in an argon protective gas atmosphere. The alloy was exposed to 23 mbar CO-gas at 600 ° C. for 465 h. CO-gas initially consisted of a mixture of CO molecules composed of ¹³ C and ¹⁸ O isotopes and CO molecules composed of ¹² C and ¹⁶ O isotopes. By measuring the conversion rates of ¹³ C ¹⁸ O and ¹² C ¹⁶ O to ¹³ C ¹⁶ O and ¹² C ¹⁸ O, the catalytic activity of alloy Q for breakdown and recombination of CO can be determined. The decomposition reaction is considered to be important as the first step of any metal dusting, carburizing or coking process.

The conversion of ¹³ C ¹⁸ O and ¹² C ¹⁶ O in the presence of alloy Q, measured by mass spectrometry, is shown in FIG. 4. As a comparison, FIG. 5 shows the conversion of the same gas in the bin. The material of the furnace is silica. There is no significant difference in catalytic activity between alloy Q and hollow silica furnace. The latter may in turn be considered as inert materials. That is, alloy Q can be considered as a material that is completely free of any catalytic activity with respect to CO and therefore highly resistant or unaffected to metal dusting, carburization and coking in CO containing gases.

Example 4

Laboratory exposure was carried out in a tube furnace of highly carburized atmosphere. The relative trend for coke formation at 1000 ° C. was evaluated between standard grade stainless steel and several Cu-based alloys having compositions according to Tables 1 and 2.

Test samples were prepared by cutting from a cast material into rectangular shapes having a size of about 10 × 15 × 3 mm and grinding to 600 mesh. Samples were washed in acetone prior to testing and placed in a cold furnace. In order to reach a low oxygen partial pressure, pure hydrogen was flushed through the furnace for 3 hours before the reaction gas introduction and temperature heating. The gas flow rate was 250 ml / min, corresponding to the gas velocity on the sample of 9 mm / s. The temperature is stabilized at 1000 ° C. after 30 min heating. The introduction composition of the reaction gas was 83% CO + 17% H ₂ . Laboratory exposure was performed at 1000 ° C./100 h in a 25 mm diameter quartz tube furnace.

The coking test results are shown in Table 5 as weight gain due to coke / graphite formation on the sample surface.

material Coke Formation at 100 ° C. [mg / cm ² / 100h] 5.2 1.0 0 0 0.5

It is clear that even relatively small amounts of Co, Ni and Fe are detrimental to the coking resistance of Cu-based alloys. Therefore, in order to obtain optimal properties, it is obvious that the total amount of Fe + Ni + Co + Mn should be less than 3% by weight. However, even with a total content of Fe + Ni + Co + Mn of up to 6% by weight, the alloy is superior to the standard material alloy 800HT.

Example 5

FIG. 6 shows a section of the Cu—Ni—Al phase diagram calculated using Thermo-calc for a given Al-content of 8 wt%. Graph 1 shows the solidus / liquidus temperature, graph 2 shows the stability region for phase NiAl, graph 3 shows the stability region for cubic dense solid solution of copper and nickel, It may also comprise a low content of aluminum for example. Graph 4 shows the stability region for the phase called β in the pure Cu-Al-system.

6 and Table 6 show the action of different amounts of copper, nickel and aluminum in an alloy of 92 wt% (Cu + Ni) and 8 wt% Al at solidus and liquidus temperatures. Figure 6 shows that only by increasing the content of nickel higher than 20% by weight can its melting point exceed 1100 ° C.

7 and Table 6 show the action of Ni, Cu and Al on the solidus temperature and carbon solubility in the Cu-Al-Ni alloy. The diagram shows that for nickel content higher than about 10% by weight, the solubility of carbon increases with increasing nickel content. The carburization rate of the alloy is largely measured by the solubility of carbon in the alloy, and metal dusting and coking are expected to increase with increasing carbon solubility. Therefore, the solubility of carbon in the alloy is preferably as low as possible, the conclusion of which is that the nickel content should be lower than 10% by weight, preferably 1%, in order to obtain optimum resistance to carburization, coking and metal dusting. It must be lower than%.

The reason why such low levels of Ni-content are required to obtain optimal properties is that nickel catalyzes coking in addition to the solubility of carbon, which is undesirable.

Example 6

One skilled in the art realizes that for a product according to the present invention, it needs to be designed to have a load carrier at elevated temperatures, ie higher than about 400 ° C. For this purpose, Cu based alloys can be machined into components in composite or bimetallic composite solutions, which will be used as different types of construction materials as described above. The latter is particularly effective when the alloy has a low content of iron and nickel.

The product is in the form of a tube or plate or strip or wire, wherein the inner load-carrying layer is coated on one or both surfaces with the Cu-based alloy specified in the above embodiment. Some methods available for producing composite solutions and load carriers of alloys include co-extrusion, cavitation of load-bearing components and one tube on one outer and / or inner tube of the alloy according to the invention. Co-welding or co-drawing and shrinking, possibly followed by heat treatment to obtain metallurgical bonds between the components. A similar method of making a plate or strip is to hot- or cold-roll two or more plates or strips together. Composite plates or -tubes can also be produced by explosion welding two or more different plates or tubes of the load carrier and alloy according to the invention. Outer-and / or intra-component addition, to a powder metallurgical technique, such as HIP (H ot I sosatic P ressing) or CIP (C old I sostatic ressing P) can be applied on a load carrier. In such a case, the load carrier may be in the form of a tube, pipe, plate, strip or wire or other suitable product form. After pressing, the formed composite will be further machined, for example by hot extrusion and / or welding, drawing and forging.

Another method for producing the composite material is electrolytic coating of copper and aluminum onto the load-bearing component, perhaps by evaporation, pack cementation, sputtering, chemical vapor deposition (CVD) or other methods, for example. In order to homogenize the vapor deposition or coating of copper and aluminum, annealing will follow.

Aluminum and copper may also be deposited on the load carrier, for example by dipping in the melt or overlay welding. These methods can be used to make all of the above product forms. Different coating methods can be used to feed copper and aluminum to the alloy. In this case, in order to homogenize the alloy for the purpose of maintaining its corrosion properties, a final heat-treatment is required.

Composite strips or composite plates made in accordance with the above description can be welded together to a composite tube longitudinally welded or spiral welded with a Cu-based alloy on the inside and / or outside of the tube.

Load carriers suitable for the above described product types are currently used for their mechanical strength and oxidation resistance in the actual temperature range, but insufficient metal dusting, carburizing, coking or nitriding for use in the context to which the present invention relates. ) It is a high temperature alloy with resistance. This can be achieved by using martensite or bainitic or ferrite (eg chromium, molybdenum, vanadium, niobium, tungsten, carbon and / or nitrogen added) at temperatures below 700 ° C. in order to obtain mechanical strength at high temperatures. ferritic) iron alloys. At temperatures higher than about 500 ° C., in many cases it is likely to use austenitic iron-chromium-nickel alloys which are mechanically strengthened as load carriers, for example by alloying with molybdenum, vanadium, niobium, tungsten, carbon and / or nitrogen. It is a common practice. In order to enhance the corrosion resistance of the load carriers, chromium and sometimes aluminum and / or silicon are used in all of these alloy groups. In this case, if the product according to the invention consists of a load carrier coated with a corrosion resistant Cu based alloy on both surfaces, the Cu based alloy according to the invention will exhibit the desired corrosion resistance. Alloys in which the maximum temperature of use is limited in other applications by corrosion resistance can be used in this way as load carriers at higher temperatures than in other cases. In this case, if the product according to the invention is coated with a corrosion resistant Cu based alloy only on one surface of the load carrier, the load carrier itself needs to have sufficient corrosion resistance in an environment where its free surface is exposed. .

Example 7

The finished tubular product is described below as an example of how a tubular product for use in metal dusting conditions is designed to meet different requirements on such a product.

Tubes for use in applications in which the corrosive gas exchanges heat with itself across the tube wall are formed of Cu-8.5 wt% Al-1.0 wt% Si-0.5 wt% Fe on both inner and outer surfaces. It consists of a load support component of alloy 800HT (UNS N08811) which has a protective layer of a base alloy. One example of such a tube is 60.3 mm in diameter and 3.91 mm in total thickness. In this finished product, it means that the outer corrosion resistant layer is 1.0 mm thick and the inner corrosion resistant layer is 0.7 mm thick, while the load bearing component is 2.2 mm thick. At 900 ° C., this is the maximum allowable pressure drop according to ASME boiler and pressure vessel code, section VIII, division I, approximately 5.5 bar. Since the gas exchanges heat with itself, the pressure drop across the tube wall is considered to be 5 bar or less, even in a process working at an absolute pressure of 10-100 bar. Thus, the products described in this section meet the requirements for use at high temperatures such as 900 ° C.

It will be apparent to those skilled in the art that tubular articles in which the corrosion resistant alloys apply only the inner surface or only the outer surface are also capable of a wide range of sizes and compositions of Cu based alloys and load bearing alloys.

Example 8

This embodiment is a tube whose interior has a carbon activity greater than the unit source in the temperature range of 450-700 ° C., and its outer surface is cooled by air having a temperature in the range of 200-700 ° C. For this reason, such a tube is applied with a metal dust resistant Cu-based alloy on its inner surface, but the outer surface must still have sufficient oxidation resistance against hot air. Using a proven alloy, such as alloy 600 (UNS N06600) with a wall thickness of 6 mm and a Cu-7Al-0.2Si-0.5 wt% Ni alloy of 2 mm thickness on the inner surface, over 10 years at an internal pressure of 10 bar Service life is possible.

Example 9

A further embodiment is a tube through which a stream passes and is heated from the outside by a gas having greater carbon activity than the unit source at 200-600 ° C. In this case, the outer surface is exposed to metal dusting conditions while the inner surface is not exposed to any carbon related corrosion. For this reason, such a tube is applied with a metal dust resistant Cu-based alloy on its outer surface, and an alloy having sufficient stream corrosion resistance and mechanical strength is used as the load supporting member. One alloy that meets these requirements is alloy 800HT (UNS N 08811). A 0.9 mm thick Cu-5.8 wt% Al-1.0 wt% Si layer is used on the outer tube surface, with a tube having an outer diameter of 50 mm and a wall thickness of 3.7 mm.

In this case, the alloy 800HT thickness is 2.8 mm, which means that the maximum allowable internal stream pressure is 100 mbar.

Claims (11)

The corrosion resistant member is provided with a minimum thickness of 0.5 mm and the following composition (% by weight): Al: 2-20 Si:> 0-6 At least one of rare earth metal (REM) groups such as yttrium, hafnium, zirconium, lanthanum and / or cerium:   Each element: 1.0 or less   Total: 3.0 or less At least one of elemental iron, nickel, cobalt and manganese:    Total: 20 or less Cu: rest And alloying additives and impurities generally present A tube, pipe, plate, consisting of a load-supporting member and a corrosion resistant member, characterized by being a copper-based alloy having a resistance to or without oxidation and resistance to carburization, metal dusting and coking; Products in the form of strips or wires. The method of claim 1, A product characterized in that the corrosion resistant member is provided with a minimum thickness of 1 mm. The method according to claim 1 or 2, A product characterized in that the copper-based alloy comprises 4-13% by weight Al, preferably 4-9% by weight Al. The method according to any one of claims 1 to 3, A product characterized in that the copper-based alloy comprises 5% by weight or less, preferably 0.05-5% by weight, more preferably 0.5-3% by weight of Si. The method according to any one of claims 1 to 4, Wherein the copper-based alloy comprises at least one of rare earth metals (REM), yttrium, hafnium, zirconium, lanthanum and / or cerium groups in a total content of at most 0.5% by weight, preferably 0.01-2% by weight Product. The method according to any one of claims 1 to 5, An article characterized in that the load-bearing member and the corrosion resistant member are metallurgically bonded, preferably along the entire contact surface. The corrosion resistant member is provided with a minimum thickness of 0.5 mm and the following composition (% by weight): Al: 2-20 Si:> 0-6 At least one of rare earth metal (REM) groups such as yttrium, hafnium, zirconium, lanthanum and / or cerium:   Each element: 1.0 or less   Total: 3.0 or less At least one of elemental iron, nickel, cobalt and manganese:    Total: 20 or less Cu: rest And alloying additives and impurities generally present It is characterized in that the copper-based alloy having, By providing a load-bearing member and a corrosion resistant member, carburizing, metal dusting, coking and oxidation in a CO-containing atmosphere, and / or vaporization of a hydrocarbon containing atmosphere or solid carbonaceous material, pyrolysis and catalysis of hydrocarbons A process for imparting resistance to solid carbon containing treatments, such as reforming (particularly small amounts of sulfur and catalysis reforming under conditions of small amounts of sulfur and small amounts of water). The method of claim 7, wherein Metallurgically bonding the load-bearing member with the corrosion resistant member, in particular along the entire contact surface. The method of claim 7, wherein And mechanically joining the load-bearing member with the corrosion resistant member. Solid carbon such as a CO-containing atmosphere and / or a hydrocarbon containing atmosphere or vaporization of a solid carbonaceous material, pyrolysis and catalysis modification of hydrocarbons (especially catalytic reforming under conditions of small amounts of sulfur and small amounts of sulfur and small amounts of water). Use of a product according to any one of claims 1 to 6 in a containing treatment. The method of claim 10, Use of products at temperatures above 1030 ° C.

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