Corrosion-resistant alloys for thermal cracking reactors

Abstract

The present disclosure provides reactor components formed using corrosion-resistant alloys having desired high-temperature mechanical strength. The corrosion-resistant components may include, but are not limited to, tubes, reactor walls, fittings, and / or other components having surfaces that can be exposed to a high-temperature reaction environment in the presence of hydrocarbons and / or can provide a pressure-containing function in a method for increasing the grade of hydrocarbons in a high-temperature reaction environment. The corrosion-resistant alloy used to form the corrosion-resistant component may include 42.0 to 46.0 wt. % nickel, 32.1 to 35.2 wt. % chromium, 0.5 to 2.9 wt. % carbon, 0 to 2.0 wt. % titanium, 0 to 4.0 wt. % tungsten, and iron, wherein at least one of titanium and tungsten is present in an amount of 1.0 wt. % or more. Iron may correspond to the balance of the composition. Optionally, the corrosion-resistant alloy may provide further improved performance based on the presence of at least one strengthening mechanism within the alloy, such as a carbide strengthening mechanism, a solid solution strengthening mechanism, a γ′ strengthening mechanism, or a combination thereof.

Description

[0001] priority

[0002] This application claims priority to and the benefit of U.S. Provisional Patent Application Serial No. 62 / 783,002, filed on December 20, 2018, and European Patent Application No. 19175303.7, filed on May 20, 2019, the disclosures of which are incorporated herein by reference in their entireties. Technical Field

[0003] The present application relates to high temperature alloys and their use in equipment for thermal cracking of hydrocarbon feeds, such as thermal cracking in a furnace. Background Art

[0004] Thermal cracking or pyrolysis of hydrocarbon feeds, such as thermal cracking of hydrocarbon feeds in the presence of steam ("steam cracking"), is a commercially important technology for producing light olefins such as ethylene, propylene and butadiene. Typical hydrocarbon feeds include, for example, one or more of ethane and propane, naphtha, heavy gas oil, crude oil, etc. Thermal cracking furnaces typically include a radiant section containing at least one heat transfer tube and at least one burner for heating the hydrocarbon feed. When the heat transfer tubes in the radiant section are arranged in a coil, the heat transfer tubes are typically referred to as "radiant coils".

[0005] In a conventional thermal cracking process, a mixture of hydrocarbons and steam is indirectly heated in at least one radiant section heat transfer tube ("radiant tube"), primarily by transferring heat from one or more burners to the outer surface of the radiant tube, such as radiant heat transfer from the flames and high temperature flue gases generated in the one or more burners, radiant heat transfer from the inner surface of the combustion chamber shell, convective heat transfer from the combustion gases passing through the radiant section, etc. The transferred heat rapidly raises the temperature of the hydrocarbon feed to the desired coil outlet temperature (COT), which is typically in the range of about 1450°F (788°C) to about 1650°F (899°C) for some very heavy gas oil feeds, or even in the range of about 1450°F (788°C) to 1700°F (927°C) for ethane or propane feeds.

[0006] Heat transferred to the hydrocarbon feed located in one or more radiant tubes causes thermal cracking of at least a portion of the hydrocarbons to produce a radiant coil effluent containing molecular hydrogen, light olefins, other hydrocarbon byproducts, unreacted steam (if the thermal cracking is steam cracking) and unreacted hydrocarbon feed. The radiant coil effluent is usually transported from the radiant section to the quenching section using a transfer line pipeline. Coke accumulation occurs during the thermal cracking process on the inner surface of the radiant tube. After an undesirable amount of coke has accumulated, the hydrocarbon + steam mixture is replaced with a decoking mixture (usually an air-steam mixture) flow to remove the accumulated coke. The decoking effluent is directed away. After the coke is removed, the hydrocarbon feed stream is resumed to be introduced into the decoking tube. The process continues in an alternating pyrolysis (thermal cracking) mode and a decoking mode. As the radiant tubes expand and contract between the alternating cracking and decoking process modes, they will be subjected to significant mechanical stresses. Several furnace components will be eroded during the decoking mode, and carbon particles are transported at a relatively high rate, resulting in metal loss over time.

[0007] Short contact time, high temperature and low hydrocarbon partial pressure are favorable for selectivity to light olefins during pyrolysis mode. For this reason, radiant tubes and / or other radiant components are typically operated at temperatures up to 2050°F (1121°C) (measured at the tube metal). Therefore, radiant components are made of alloys having the required properties at high temperatures, such as high creep strength and high fracture strength. This may limit the available manufacturing options because many commercial-grade corrosion-resistant alloys do not have sufficient strength in terms of temperature and / or weldability. Since the tubes are exposed to a carburizing environment during hydrocarbon pyrolysis, the alloys are also generally resistant to carburization. Moreover, since the tubes are exposed to an oxidizing environment during decoking, the alloys are also generally resistant to oxidation. Conventional heat transfer tube alloys include austenitic Fe-Cr-Ni heat resistant steels with variations based on compositions having 25 wt% chromium and 35 wt% nickel (referred to as "25Cr / 35Ni alloy") or compositions having 35 wt% chromium and 45 wt% nickel (referred to as "35Cr / 45Ni alloy"), both with about 0.1 to 0.5 wt% carbon. Minor alloying elements such as silicon are often employed in varying compositions to improve high temperature strength and / or carburization resistance. The carbon and other carbide forming elements of these alloys are controlled to provide creep strength and weldability.

[0008] In conventional steam cracker alloys, Cr is formed during aging under operating conditions. 3 C 2 Cr 7 C 3 and / or Cr 23 C 6This is mainly due to the large amounts of chromium and carbon in the alloy. The presence of such phases during aging leads to an increase in hardness and, depending on the carbon content, may lead to an increase in creep strength at temperature, but reduces weldability and thus leads to cracking. Therefore, the amount of carbon that can be introduced to improve hardness alone is limited.

[0009] To overcome this difficulty, parts susceptible to erosion can be made with thicker erosion allowances to extend service life. Another common approach to overcoming erosion problems is to use erosion-resistant alloys combined with materials subject to erosion. U.S. Pat. No. 3,816,081 discloses an example of a wear-resistant alloy using a mixture of tungsten, titanium, tantalum or pure titanium carbide. However, these carbides are embedded in a relatively soft matrix, which results in early loss of the wear-resistant cover at the temperatures of thermal cracking furnaces.

[0010] U.S. Patent No. 5,302,181 describes a chromium-based oxidation-resistant heat-resistant alloy made by sintering. By using a solid-state diffusion process like sintering that does not involve melting and solidification, the chemical composition of the alloy can be adjusted to incorporate large amounts of alloying elements. This can increase hardness at temperature, but may cause cracking during solidification in castings and welds.

[0011] U.S. Patent No. 6,268,067 B1 discloses improving the carburization resistance of a tube by a solid state fill diffusion surface treatment process using an alloy containing 5 to 15 weight percent aluminum. The reference discloses a tube structure in which a specific alloy content of one or more elements on the surface of a tubular member can be increased to a certain depth to improve carburization resistance. However, the enrichment depth construction of these components is economically demanding and has a limited erosion life because it is not monolithic.

[0012] U.S. Patent No. 10,041,152 describes a thermally stable and corrosion resistant cast nickel-chromium alloy. The alloy includes 0.5 to 13 weight percent iron, less than 0.8 weight percent carbon, and 1.5 to 7 weight percent aluminum. The alloy may also include up to 1 weight percent silicon, up to 0.2 weight percent manganese, 15 to 40 weight percent chromium, up to 2.5 weight percent niobium, up to 1.5 weight percent titanium, 0.01 to 0.4 weight percent zirconium, up to 0.06 weight percent nitrogen, up to 12 weight percent cobalt, up to 5 weight percent molybdenum, up to 6 weight percent tungsten, 0.01 to 0.1 weight percent yttrium, and the remainder corresponds to nickel.

[0013] Therefore, there remains a need for an integrally heat-resistant and corrosion-resistant alloy for use in thermal cracking environments.

[0014] Overview

[0015] In various aspects, reactor components formed using corrosion-resistant alloys having desired high temperature mechanical strength (heat resistance) are provided. The corrosion-resistant components may include, but are not limited to, tubes, reactor walls, fittings, and / or other components having surfaces that may be exposed to a high temperature reaction environment in the presence of hydrocarbons and / or that may provide a pressure containment function (and other functions, if any) in a method for upgrading hydrocarbon grades in a high temperature reaction environment. The corrosion-resistant alloy used to form the corrosion-resistant component may include 42.0 to 46.0 wt. % nickel, 32.1 to 35.2 wt. % chromium, 0.5 to 2.9 wt. % carbon, 0 to 2.0 wt. % titanium, 0 to 4.0 wt. % tungsten, and the balance iron, wherein at least one of titanium and tungsten is present in an amount of 1.0 wt. % or more. Optionally, the corrosion-resistant alloy may be substantially free of aluminum.

[0016] Optionally, the corrosion resistant alloy can provide further improved performance based on the presence of at least one strengthening mechanism within the alloy, such as a carbide strengthening mechanism, a solid solution strengthening mechanism, a γ′ strengthening mechanism, or a combination thereof. In some aspects, the strengthening mechanism can be formed in situ due to exposure to reaction conditions within a reactor, such as pyrolysis conditions within a steam cracking reaction system or another type of pyrolysis reaction system.

[0017] BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawing illustrates a schematic flow diagram of one type of pyrolysis furnace.

[0019] Detailed description

[0020] All numerical values ​​in this detailed description and claims are modified by "about" or "approximately" relative to the indicated value, and take into account experimental error and variations that would be expected by a person of ordinary skill in the art.

[0021] Overview

[0022] In various aspects, reactor components formed using corrosion-resistant alloys having desired high temperature mechanical strength (heat resistance) are provided. The corrosion-resistant components may include, but are not limited to, tubes, reactor walls, fittings, and / or other components having surfaces that may be exposed to a high temperature reaction environment in the presence of hydrocarbons and / or that may provide a pressure containment function (and other functions, if any) in a method for upgrading hydrocarbon grades in a high temperature reaction environment. This may include reaction environments in which carburization may occur, such as pipelines used to transport or convey hydrocarbon process streams that may be susceptible to coking. For example, the corrosion-resistant components may include, but are not limited to, any of the following pyrolysis furnace components: feed pipes; dilution steam pipes; steam cracking furnace tubes, such as convection tubes and / or radiant tubes, including those arranged in one or more coils; connecting pipes; transmission line exchangers; quench zone piping; and other components that may have one or more surfaces exposed to hydrocarbons at temperatures exceeding 500°C (930°F) during the pyrolysis process.

[0023] The corrosion-resistant alloy for forming the corrosion-resistant component may include 42.0 to 46.0 weight % nickel, 32.1 to 35.2 weight % chromium, 0.5 to 2.9 weight % carbon, 0 to 2.0 weight % titanium, 0 to 4.0 weight % tungsten and iron. Note that at least one of titanium and tungsten may be present in the alloy so that at least one of titanium and tungsten is present in an amount of 1.0 weight % or more. Iron may correspond to the balance of the composition. In some aspects, iron may correspond to 14.0 weight % or more of the composition, or 16.0 weight % or more, such as up to 24.5 weight %. In some aspects, the amount of carbon in the corrosion-resistant alloy may be 0.6 weight % to 2.9 weight %, or 0.8 weight % to 2.9 weight %, or 1.0 weight % to 2.9 weight %. Additionally or alternatively, the corrosion-resistant alloy may be substantially free of aluminum.

[0024] Optionally but preferably, the corrosion resistant alloy may provide further improved properties based on the presence of at least one strengthening mechanism within the alloy, such as a carbide strengthening mechanism, a solid solution strengthening mechanism, a gamma prime strengthening mechanism, or a combination thereof.

[0025] Traditionally, aluminum is added to alloys in various types of carburizing environments to serve as an anti-coking agent within the alloy. In contrast, due to the improved performance of the corrosion-resistant alloy, the corrosion-resistant alloy described herein can be substantially free of aluminum while still providing beneficial performance in a high temperature carburizing environment. "Substantially free of aluminum" can correspond to not including added aluminum in the alloy and / or having an aluminum content of less than 0.05 weight percent. With respect to not including added aluminum, some components used to form the alloy may potentially include aluminum impurities. It should be understood that when determining whether an alloy includes added aluminum, aluminum impurities within the desired components used to form the alloy are excluded.

[0026] Typically, many alloys used in high temperature environments where corrosion may occur may have limited amounts of carbon, such as less than 0.5 weight percent. The low carbon content in conventional alloys may be due in part to concerns about the formation of segregated carbon portions within the alloy. In contrast, in some aspects, the corrosion-resistant alloys described herein may utilize increased amounts of carbon to allow for increased strengthening due to carbide formation. In some aspects, the amount of segregated carbon phases formed within the alloy can be reduced or minimized by using a hot isostatic pressing method for forming components from the alloy.

[0027] In some aspects, the corrosion-resistant alloys can be advantageous in promoting the formation of metal carbides (M) throughout the thickness of the component during manufacturing and / or during aging. x C y ) formation. For example, carbides corresponding to the stoichiometric ratio of MC may be formed during manufacturing, while carbides corresponding to the stoichiometric ratio of M 3 C 2 、M 7 C 3 and / or M 23 C 6 Carbides of stoichiometric proportions may form during aging. These carbides can provide high strength and hardness at high temperatures. Additionally or alternatively, in aspects in which the alloy includes titanium, Ni in the alloy 3 The formation of Ti may provide a gamma prime strengthening mechanism.Also additionally or alternatively, one or more elements may be added to the alloy which, together with the Ni in the alloy, provide a solid solution strengthening mechanism for the corrosion resistant alloy.

[0028] Formation of corrosion-resistant components

[0029] The corrosion-resistant parts made of corrosion-resistant alloys can be formed by any convenient manufacturing method, including hot isostatic pressing, sintering, centrifugal casting, static casting, extrusion, forging, rolling, joining and / or machining. In some aspects, the method of manufacturing parts by corrosion-resistant alloys can correspond to hot isostatic pressing and equivalent methods. In such a method, a mixture of metal powders with a desired alloy composition can be formed into a certain shape by a hot isostatic pressing process. Hot isostatic pressing can potentially be beneficial for incorporating higher amounts of carbon into parts made of corrosion-resistant alloys while reducing or minimizing the formation of separated carbon parts in the alloy. Hot isostatic pressing is a commercially available method. Exemplary hot isostatic pressing equipment and corresponding methods are described in U.S. Patent No. 4,582,681, and the description of hot isostatic pressing for part manufacturing is incorporated herein by reference.

[0030] In some aspects, a manufacturing method such as hot isostatic pressing can be used to make the erosion-resistant component. In other aspects, a manufacturing method such as hot isostatic pressing can be used to make a billet of the erosion-resistant alloy, which can then be used to make the erosion-resistant component.

[0031] Corrosion Resistant Alloy

[0032] The heat-resistant and corrosion-resistant alloy may correspond to a chromium-nickel-iron alloy, which also includes significant amounts of carbon, chromium, iron, and at least one of titanium and tungsten. In some aspects, the corrosion-resistant alloy may contain sufficient metal carbides to increase the hardness of the material at high temperatures. For example, the alloy is capable of forming carbides under thermal cracking conditions. Such carbides can be beneficial in reducing corrosion while maintaining hardness at high temperatures. Additionally or alternatively, the corrosion-resistant alloy has at least one strengthening mechanism to provide desired high-temperature mechanical properties.

[0033] The corrosion-resistant alloy for forming the corrosion-resistant component may include 42.0 to 46.0 weight % nickel, 32.1 to 35.2 weight % chromium, 0.5 to 2.9 weight % carbon, 0 to 2.0 weight % titanium, 0 to 4.0 weight % tungsten and iron. Note that at least one of titanium and tungsten may be present in the alloy so that at least one of titanium and tungsten is present in an amount of 1.0 weight % or more. Iron may correspond to the balance of the composition. In some aspects, iron may correspond to 14.0 weight % or more of the composition, or 16.0 weight % or more, such as up to 24.5 weight %. In some aspects, the amount of carbon in the corrosion-resistant alloy may be 0.6 weight % to 2.9 weight %, or 0.8 weight % to 2.9 weight %, or 1.0 weight % to 2.9 weight %. Additionally or alternatively, the corrosion-resistant alloy may be substantially free of aluminum.

[0034] In some aspects, the alloy may include a reduced or minimal amount of silicon. Without being bound by any particular theory, it is believed that silicon reduces mechanical strength by acting as a deoxidizer. In some aspects, the corrosion-resistant alloy may include less than 1.0 wt % silicon, such as as low as substantially no silicon (i.e., less than 0.05 wt %) and / or no added silicon. In this discussion, when an alloy is substantially free of an element, it is understood that this corresponds to not intentionally adding the element to the alloy. However, there may be trace amounts of such an element to the extent that such trace amounts may typically be present in the material used to form the alloy.

[0035] Manganese may be present in the corrosion-resistant alloy to act as an oxygen and / or sulfur scavenger, for example, when the alloy is in a molten state. When such scavenging functions are desired, manganese may generally be present in a concentration of 1.5 wt % or less, or 1.0 wt % or less, or 0.5 wt % or less, such as down to substantially no manganese and / or no added manganese. In some aspects, the alloy may include 0.1 wt % to 1.5 wt % manganese, or 0.5 wt % to 1.5 wt % manganese, or 1.0 wt % to 1.5 wt % manganese.

[0036] Boron may be present in the corrosion resistant alloy, for example to improve grain boundary properties. Boron may typically be present in an amount of 0 to about 0.1 wt %, or 0 to 0.07 wt %, or 0 to 0.5 wt %, or 0.05 wt % to 0.1 wt %.

[0037] The corrosion-resistant alloy may also optionally include one or more rare earth elements, i.e., the 15 elements of the lanthanide series from lanthanum to lutetium in the periodic table, as well as yttrium and scandium, particularly cerium, lanthanum and neodymium. In these aspects, the one or more rare earth elements may be present in an amount of about 0.005 to about 0.4 weight percent. In aspects where rare earth elements are present, the total amount of cerium, lanthanum and neodymium may constitute 80 weight percent or more, or 90 weight percent or more of the total amount of rare earth elements. Without being bound by any particular theory, it is believed that the presence of rare earth elements may aid in the formation and stabilization of the alloy.

[0038] The high temperature corrosion resistant alloys described herein may also contain phosphorus, sulfur and other impurities, such as those incorporated into the alloy when the material is prepared. The amount of such impurities may be comparable to or less than the typical amount in conventional steam cracker alloys.

[0039] Strengthening Mechanism

[0040] The corrosion-resistant alloy constituting the corrosion-resistant component may include at least one strengthening mechanism to improve high temperature strength and hardness. An example of a suitable strengthening mechanism may be a carbide strengthening mechanism. The carbide strengthening mechanism may be composed of MC, M 6 C.M. 7 C 3 and M 23 C 6 The precipitation of M-type carbide phase is produced, where M is a metal carbide-forming element.

[0041] Usually, MC carbides tend to appear in the form of large carbides and are randomly distributed. 6 C carbides also tend to be massive. However, when formed as fine discrete precipitates at grain boundaries during metal working, MC and M 6 C can be used to control grain size and strengthen alloys. 7 C 3 Carbides (mainly (Ti, Cr, Fe) 7 C 3 ) can form at grain boundaries and may be beneficial if they precipitate as discrete particles because these carbides can reduce grain boundary sliding. 23 C 6 Carbides can also show a tendency to precipitate at grain boundaries. Discrete grain boundary precipitates can increase fracture strength.

[0042] In some aspects, the corrosion resistant alloy may include a carbide strengthening mechanism based on the presence of metal carbides formed from tungsten, titanium, chromium, or a combination thereof. The metal carbides formed in the carbide strengthening mechanism may contain an amount of carbon that depends on the specific metal present in the carbide. Desirable amounts of carbon in corrosion resistant alloys having a carbide strengthening mechanism may include 0.5 wt % to 2.9 wt % carbon, or 0.6 wt % to 2.9 wt % carbon, or 0.8 wt % to 2.9 wt % carbon, or 1.0 wt % to 2.9 wt % carbon.

[0043] Another suitable strengthening mechanism may correspond to the gamma-skim strengthening mechanism. The gamma-skim (γ') strengthening mechanism is composed of Ni 3 The precipitation of Ti-type gamma-skim phase, which can be formed during processing, involves alloys containing significant amounts of Ni and Ti. The gamma-skim phase present in corrosion resistant alloys acts as an obstacle to dislocation motion within the alloy crystal structure and thus increases the strength of the alloy due to its ordered nature and high adhesion to the austenitic alloy matrix. In some aspects, the anti-carburization alloy may include a Ni-based alloy containing 3 Gamma-skim (γ') strengthening mechanism of alloys of Ti and 0.5 wt% to 2.9 wt% or 0.6 wt% to 2.9 wt% or 0.8 wt% to 2.9 wt% or 1.0 wt% to 2.9 wt% carbon. In some aspects, the corrosion-resistant alloy comprises a) 42.0 to 46.0 wt% nickel (Ni); b) 32.1 to 35.2 wt% chromium (Cr); c) 0.5 to 2.9 wt% carbon (C); d) 0 to 2.0 wt% titanium (Ti); e) 0 to 4.0 wt% tungsten (W); f) the balance iron (Fe); and g) corresponding to Ni 3 Gamma skim (γ') strengthening mechanism of Ti and less than 2.9 wt% carbon, wherein at least one of Ti and W is present in an amount of 1.0 wt% or more.

[0044] Another suitable strengthening mechanism may correspond to a solid solution strengthening mechanism. The solid solution strengthening mechanism originates from the difference in atomic diameter. For example, it is known that Co, Fe, Cr, Mo, W, V, Ti and Al are solid solution strengtheners in Ni. In some aspects, Co, Fe, Cr, Mo, W, V or Ti may be used as solid solution strengtheners, and preferably the solid solution strengthener may be Ti or Cr. The atomic diameter of these elements differs from that of Ni by 1% to 13%. Therefore, the lattice expansion associated with the excessive atomic diameter is associated with hardening. At hot cracking operating temperatures in the high temperature creep range, strengthening is diffusion dependent. Therefore, larger and slowly diffusing elements such as Ti and Cr may be effective as hardeners. In some aspects, the corrosion-resistant alloy may include a solid solution strengthening mechanism based on at least one element selected from titanium, tungsten, iron and chromium.

[0045] In some aspects, the corrosion resistant alloy may include a combination of one or more of the above strengthening mechanisms. It should be noted that the carbide strengthening mechanism may be more effective in the alloys described herein relative to conventional alloys due to the increased amount of carbon in the alloy. In some aspects, the corrosion resistant alloy may include at least one (including combinations) of a carbide strengthening mechanism or gamma 'and solid solution strengthening mechanism components.

[0046] In some aspects, the formation of one or more strengthening mechanisms in the corrosion-resistant alloy can be achieved by exposing the component to an aging temperature. Suitable aging temperatures for controlled aging can be ≥ about 815°C, such as 815°C to 1200°C, or 600°C to 1100°C. The exposure time can be ≥ about 1 hour, such as 1 hour to 500 hours, or 1 hour to 300 hours, or 1 hour to 100 hours. Additionally or alternatively, the formation of some strengthening mechanisms may occur during exposure of the component to a steam cracking environment.

[0047] The corrosion-resistant alloy can be useful in reducing or minimizing the amount of material lost from a component due to exposure of one or more surfaces of the component to an environment that can cause corrosion, such as various locations within a steam cracking process system. Erosion is the process of removing material from a target surface by the action of streams and jets of solid particles or liquids. In most high-temperature erosive environments, the eroded surface undergoes corrosion as well as erosion. The erosion process is primarily controlled by impact variables such as etchant velocity, impact angle, etchant flux, and temperature. It is also affected by etchant particle variables (i.e., size, shape, hardness, toughness, and density) and target material variables (i.e., hardness, toughness, and elastic modulus). The transfer of kinetic energy from the etchant particles to the target surface can lead to degradation. The erosion rate of a general material can be represented by the following equation (1):

[0048] (1)

[0049] where ν p , D p and ρ p are the velocity, average diameter and density of the impacting particles, K 1C and H are the toughness and hardness of the target material. For a given system that is subject to erosion, the superscripts n, m, x, and y can be determined experimentally. Therefore, erosion resistance requires high hardness and toughness of the erosion-resistant alloy. Components made from erosion-resistant alloys can therefore be made from alloys with high hardness and / or toughness. In addition, in environments such as steam cracking environments, good resistance to carburization and oxidation may be beneficial due to exposure of the components to a highly carburizing environment during cracking and / or due to exposure of the components to a highly oxidizing environment during periodic required decoking operations.

[0050] Components made from the corrosion resistant alloys described herein may be monolithic. The corrosion resistance mentioned herein reduces the tendency of the component to lose metal during the decoking process. The term "corrosion resistant" in this context means that the alloy reduces the metal loss caused by coke particles impacting the component compared to other heat resistant alloys.

[0051] The wording "integral" describes the presence of the formation of corrosion resistant metal carbides and / or other strengthening mechanisms throughout the component, such as strengthening mechanisms distributed over more than 50% of the volume of the component, preferably over the entire volume of the component (i.e., distributed over more than 90% of the volume of the component). This can distinguish integral components made of corrosion resistant alloys from other systems that rely on layers and / or surface treatments to provide corrosion resistance.

[0052] Steam Cracking Furnace

[0053] High temperature components (tubes, fittings, nozzles) made from the corrosion resistant alloys can be used in various types of thermal cracking environments, such as steam cracking environments for producing ethylene, propylene and / or other light olefins. In some aspects, systems and methods for producing olefins based on pyrolysis of hydrocarbon feeds in heat transfer tubes composed of the corrosion resistant alloys described herein are provided.

[0054] A non-limiting example of a steam cracking furnace is depicted in the accompanying drawings. In the example shown in the accompanying drawings, the steam cracking furnace 1 includes a radiant combustion chamber 103, a convection section 104, and a flue gas exhaust port 105. Fuel gas is provided to a burner 102 via a conduit 130 and a control valve 101, which provides radiant heat to the hydrocarbon feed to produce the desired pyrolysis products by thermal cracking of the feed. The burner produces hot gases that flow upward through the convection section 104 and then leave the furnace through a conduit 105.

[0055] In the example shown in the accompanying drawings, the hydrocarbon feed is directed to at least one convection coil 13 via a pipe 10 and a valve 12. The hydrocarbon feed introduced into the convection coil 13 is preheated by indirect contact with hot flue gas. The valve 12 is used to adjust the amount of hydrocarbon feed introduced into the convection coil 13. The convection coil 13 is typically one of a plurality of convection coils arranged in a first coil group for parallel flow of hydrocarbon feedstock. Typically, a plurality of feed pipes 10 and 11 deliver the hydrocarbon feed to each parallel convection coil of the first coil group. Four feed pipes are shown in the accompanying drawings, but any convenient number of feed pipes may be used. For example, a convection section having 3, 4, 6, 8, 10, 12, 16 or 18 feed pipes may be used to deliver a portion of the total hydrocarbon feed (in parallel) to the same number of convection coils located in the first coil group. Although not shown, each of the plurality of feed pipes 11 may be provided with a valve (similar to valve 12). In other words, each of the plurality of ducts 11 may be in fluid communication with a convection coil (not shown) that is (i) located in the first coil group and (ii) operates in parallel with the convection coil 13. For simplicity, the description of the first convection coil group will focus on the convection coil 13. The other convection coils in the group may operate in a similar manner.

[0056] In the example shown in the accompanying drawings, dilution steam is provided to the convection coil 23 via the dilution steam duct 20 through the valve 22 for preheating by indirect heat transfer from the flue gas. The valve 22 is used to adjust the amount of dilution steam introduced into the convection coil 23. The convection coil 23 is typically one of a plurality of convection coils arranged in a second coil group for parallel dilution steam flow. Typically, a plurality of dilution steam ducts 20 and 21 deliver dilution steam to each parallel convection coil of the second coil group. Four dilution steam ducts are shown in the accompanying drawings, but any convenient number of dilution steam ducts may be used. For example, a convection section having 3, 4, 6, 8, 10, 12, 16 or 18 dilution steam ducts may be used to deliver a portion of a certain amount of total dilution steam (in parallel) to the same number of convection coils located in the second convection coil group. Although not shown, each of the plurality of dilution steam ducts 21 may be provided with a valve (similar to the valve 22). In other words, each of the plurality of tubes 21 is in fluid communication with a convection coil (not shown) that operates in parallel with the convection coil 23. For simplicity, the description of the second convection coil group will focus on the coil 23. The other convection coils in the group may operate in a similar manner.

[0057] In the example shown in the drawings, the preheated dilution steam and the preheated hydrocarbon feed are combined in or near the conduit 25. The hydrocarbon and steam mixture is reintroduced into the convection section 104 through the conduit 25 to preheat the hydrocarbon and steam mixture in the convection coil 30. The convection coil 30 is typically one of a plurality of convection coils arranged in a third coil group for parallel flow of the hydrocarbon and steam mixture during preheating. The drawings show one convection coil for preheating the hydrocarbon and steam mixture, but any convenient number of such convection coils may be used. For example, a third coil group having 3, 4, 6, 8, 10, 12, 16 or 18 hydrocarbon and steam mixture convection coils may be used to (parallel) convey a portion of the total hydrocarbon and steam mixture. For simplicity, the description of the third convection coil group will focus on the coil 30. The other convection coils in the group may operate in a similar manner. The hydrocarbon and steam mixture may be preheated in the convection coils 30 to a temperature in the range of, for example, about 750°F to about 1400°F (about 400°C to about 760°C).

[0058] Crossover line 31 is used to convey the preheated hydrocarbon and steam mixture to radiant coil 40 in radiant section 103 for thermal cracking of the hydrocarbons. Radiant coil 40 may be one of a plurality of radiant coils (others not shown) that together form a group of radiant coils in radiant section 103. The temperature of the heated mixture exiting line 30 is typically designed to be at or near the point where significant thermal cracking begins. Process conditions, such as the amount of feed preheated in convection coil 13, the amount of steam preheated in convection coil 23, the amount of hydrocarbon and steam mixture preheated in convection coil 30, the relative amounts of hydrocarbon feed and dilution steam, the temperature, pressure and residence time of the preheated hydrocarbon and steam mixture in radiant coil 40, and the duration of the first time interval (duration of the pyrolysis mode in coils 13, 23, 30 and 40) are typically dependent on the composition of the hydrocarbon feed, the yield of the desired product, and the amount of coke accumulation in the furnace (particularly in the radiant coils) that can be tolerated. Heat transfer tubes constructed from the corrosion-resistant alloys described herein may be used as the radiant coil 40 .

[0059] After reaching the desired degree of thermal cracking in the radiant section 103, the furnace effluent can be rapidly cooled in the cooling section 50. Any method of cooling the furnace effluent can be used. In one aspect, the cooling section 50 includes at least a primary transmission line exchanger (TLE). For hydrocarbon feeds containing liquid hydrocarbons such as heavy naphtha and all gas oil feeds, a direct oil quench connection can be used downstream of the primary TLE. The oil quench connection allows quench oil to be added to the pyrolysis product stream to provide heat transfer directly from the product stream to the injected quench oil. To this end, a quench medium such as quench oil can be injected into the effluent by at least one accessory suitable for this purpose. Additional quench sections can be used in the cooling section 50, and these sections can be operated in series, in parallel or in series and in parallel. The cooled furnace effluent leaves via pipeline 51 for further separation and / or processing, such as removing ethylene and / or propylene from the furnace effluent. In addition to being used in a steam cracking furnace, a specified weldment can be used for one or more TLEs or quench sections described in this way. More generally, any convenient method of cooling the furnace effluent may be used.

[0060] Hydrocarbon feed

[0061] Heat transfer tubes formed from corrosion-resistant alloys described herein can be used to transport essentially any hydrocarbon feedstock that can produce light olefins by steam cracking. In certain aspects, the hydrocarbon feedstock may correspond to a feedstock comprising relatively high molecular weight hydrocarbons ("heavy feedstocks"), such as those that produce relatively large amounts of SCT during steam cracking. Examples of heavy feedstocks include one or more of the following groups: steam cracked gas oils and residual oils, gas oils, heating oils, jet fuels, diesel, kerosene, coker naphtha, steam cracked naphtha, catalytic cracked naphtha, hydrocracked oils, reformate, residual oil reformate, Fischer-Tropsch liquids, Fischer-Tropsch gases, distillates, crude oils, atmospheric tubular still bottoms, vacuum tubular still streams including bottoms, wide boiling range naphtha to gas oil condensates, heavy non-original hydrocarbon streams from refineries, vacuum gas oils, heavy gas oils, naphthas contaminated with crude oil, atmospheric residue, heavy residue, C 4 The hydrocarbons may have a nominal final boiling point of at least about 600°F (315°C), generally greater than about 950°F (510°C), typically greater than about 1100°F (590°C), such as greater than about 1400°F (760°C). The nominal final boiling point refers to the temperature at which 99.5% by weight of a particular sample has reached its boiling point.

[0062] In another aspect, the hydrocarbon feed may contain naphtha as a major component (naphtha feedstock). The naphtha feedstock may include C 5 To C 10 Hydrocarbons such as C 5 To C 8 A mixture of aliphatic hydrocarbons.

[0063] In other aspects, the hydrocarbon feedstock may include one or more relatively low molecular weight hydrocarbons (light feedstocks), particularly C 2 Those aspects of unsaturates (ethylene and acetylene). Light feedstocks generally include substantially saturated hydrocarbon molecules having less than five carbon atoms, such as ethane, propane, and mixtures thereof. The heat transfer tubes of the present invention are particularly suitable for steam cracking of light feedstocks, and more particularly for use as radiant tubes for steam cracking of ethane.

[0064] Test Method

[0065] Chemical composition can be determined using an electron probe microanalyser (EPMA). EPMA is essentially the same as a scanning electron microscope (SEM), but with the added capability of chemical analysis. The main importance of EPMA is the ability to perform precise, quantitative elemental analysis via wavelength dispersive spectroscopy (WDS). The spatial scale of the analysis, and the ability to create detailed images of the sample, makes it possible to analyse materials in situ and resolve complex chemical variations within a single phase.

[0066] When multiple numerical lower limits and multiple numerical upper limits are listed in this article, the range from any lower limit to any upper limit is contemplated. Although the illustrative embodiments of the present disclosure have been particularly described, it should be understood that various other modifications are obvious to those skilled in the art and can be easily made by those skilled in the art without departing from the spirit and scope of the present disclosure. Therefore, it is not intended that the scope of the appended claims be limited to the examples and descriptions set forth herein, but the claims should be understood to include all features with patent novelty present in the present invention, including all features that will be regarded as equivalents by those skilled in the art to which the present invention belongs.

[0067] The present disclosure has been described above in conjunction with many embodiments and specific examples. Considering the above detailed description, many variations will be apparent to those skilled in the art. All such various variations are within the scope of the entire intent of the appended claims.

Claims

1. A hydrocarbon pyrolysis furnace component composed of a corrosion-resistant alloy, the corrosion-resistant alloy comprising a) 42.0 to 46.0 wt. % nickel (Ni); b) 32.1 to 35.2 wt. % chromium (Cr); c) 1.0 to 2.9 wt. % carbon (C); d) 0 to 2.0 wt. % titanium (Ti); e) 0 to 4.0 wt. % tungsten (W); f) 14.0 to 24.5 wt. % iron (Fe), wherein the corrosion-resistant alloy comprises 1.0 wt. % or more of at least one of Ti and W, wherein the hydrocarbon pyrolysis furnace component is formed by hot isostatic pressing, wherein the hydrocarbon pyrolysis furnace component is substantially free of silicon.

2. The hydrocarbon pyrolysis furnace component of claim 1, wherein the corrosion resistant alloy comprises a strengthening mechanism comprising: (i) a carbide strengthening mechanism, wherein the corrosion-resistant alloy comprises carbides of at least one of titanium, tungsten and chromium; (ii) a gamma-ray (γ') strengthening mechanism, wherein the corrosion resistant alloy comprises Ni3Ti; (iii) solid solution strengthening mechanism; or (iv) A combination of two or more of (i), (ii) and (iii).

3. The hydrocarbon pyrolysis furnace component of claim 1 or 2, wherein the corrosion-resistant alloy is substantially free of aluminum.

4. The hydrocarbon pyrolysis furnace component of claim 1 or 2, wherein the hydrocarbon pyrolysis furnace component comprises a tube, a transmission line exchanger, or a combination thereof.

5. The hydrocarbon pyrolysis furnace component of claim 1 or 2, wherein the hydrocarbon pyrolysis furnace component comprises a feed pipe, a dilution steam pipe, a convection tube, a radiant tube, a quench zone pipe, or a combination thereof.

6. The hydrocarbon pyrolysis furnace component of claim 1 or 2, wherein the hydrocarbon pyrolysis furnace component comprises a radiant coil.

7. The hydrocarbon pyrolysis furnace component of claim 1 or 2, wherein the hydrocarbon pyrolysis furnace component comprises a steam cracking furnace component.

8. The hydrocarbon pyrolysis furnace component of claim 1 or 2, wherein the hydrocarbon pyrolysis furnace component comprises a unitary structure.

9. A method for producing a hydrocarbon pyrolysis furnace component, the method comprising: Forming hydrocarbon pyrolysis furnace components comprising a corrosion-resistant alloy via hot isostatic pressing, wherein the corrosion resistant alloy comprises a) 42.0 to 46.0 wt. % nickel (Ni); b) 32.1 to 35.2 wt. % chromium (Cr); c) 1.0 to 2.9 wt. % carbon (C); d) 0 to 2.0 wt. % titanium (Ti); e) 0 to 4.0 wt. % tungsten (W); f) 14.0 to 24.5 wt. % iron (Fe), wherein the corrosion resistant alloy comprises 1.0 wt. % or more of at least one of Ti and W, wherein the hydrocarbon pyrolysis furnace component is substantially free of silicon.

10. The method of claim 9, wherein the corrosion resistant alloy comprises a strengthening mechanism comprising: (i) a carbide strengthening mechanism, wherein the corrosion-resistant alloy comprises carbides of at least one of titanium, tungsten and chromium; (ii) a gamma-ray (γ') strengthening mechanism, wherein the corrosion resistant alloy comprises Ni3Ti; (iii) solid solution strengthening mechanism; or (iv) A combination of two or more of (i), (ii) and (iii).

11. The method of claim 9 or 10, wherein the step of forming the hydrocarbon pyrolysis furnace component comprises: forming a billet comprising the corrosion-resistant alloy; and A hydrocarbon pyrolysis furnace component is formed from the billet.

12. The method of claim 9 or 10, wherein the corrosion-resistant alloy is substantially free of aluminum.

13. The method of claim 9 or 10, wherein the hydrocarbon pyrolysis furnace components comprise tubes, transmission line exchangers, or combinations thereof.

14. The method of claim 9 or 10, wherein the hydrocarbon pyrolysis furnace components comprise feed pipes, dilution steam pipes, convection tubes, radiant tubes, quench zone pipes, or combinations thereof.

15. The method of claim 9 or 10, wherein the hydrocarbon pyrolysis furnace component comprises a radiant coil.

16. The method of claim 9 or 10, wherein the hydrocarbon pyrolysis furnace component comprises a unitary structure.

17. A method for producing olefins, the method comprising pyrolyzing a hydrocarbon feed in a pyrolysis environment comprising hydrocarbon pyrolysis furnace components, the hydrocarbon pyrolysis furnace components comprising a corrosion resistant alloy, wherein the corrosion resistant alloy comprises a) 42.0 to 46.0 wt. % nickel (Ni); b) 32.1 to 35.2 wt. % chromium (Cr); c) 1.0 to 2.9 wt. % carbon (C); d) 0 to 2.0 wt. % titanium (Ti); e) 0 to 4.0 wt. % tungsten (W); f) 14.0 to 24.5 wt. % iron (Fe), wherein the corrosion resistant alloy comprises 1.0 wt. % or more of at least one of Ti and W, wherein the hydrocarbon pyrolysis furnace component is formed by hot isostatic pressing, wherein the hydrocarbon pyrolysis furnace component is substantially free of silicon.

18. The method of claim 17, wherein the corrosion resistant alloy comprises a strengthening mechanism comprising: (i) a carbide strengthening mechanism, wherein the corrosion-resistant alloy comprises carbides of at least one of titanium, tungsten and chromium; (ii) a gamma-ray (γ') strengthening mechanism, wherein the corrosion resistant alloy comprises Ni3Ti; (iii) solid solution strengthening mechanism; or (iv) A combination of two or more of (i), (ii) and (iii).

19. The method of claim 17 or 18, wherein the process for pyrolyzing the hydrocarbon feed comprises steam cracking, and / or wherein the pyrolysis environment comprises a steam cracking environment.

20. The method of claim 17 or 18, wherein the corrosion-resistant alloy is substantially free of aluminum.

21. The method of claim 17 or 18, wherein the hydrocarbon pyrolysis furnace components comprise tubes, transmission line exchangers, or combinations thereof.

22. The method of claim 17 or 18, wherein the hydrocarbon pyrolysis furnace components comprise feed conduits, dilution steam conduits, convection tubes, radiant tubes, quench zone conduits, or combinations thereof.

23. The method of claim 17 or 18, wherein the hydrocarbon pyrolysis furnace component comprises a radiant coil.

24. The method of claim 17 or 18, wherein the hydrocarbon pyrolysis furnace component comprises a unitary structure.

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