Method and system for steam cracking

Abstract

A steam cracking method using steam cracking by using a steam cracking system (100) is proposed, the steam cracking system (100) includes one first steam cracking furnace unit (1000) or a plurality of second steam cracking furnace units (2000) and one second steam cracking furnace unit (2000) or a plurality of second steam cracking furnace units (2000), and the one first steam cracking furnace unit (1000) or the plurality of first steam cracking furnace units (1000) Each comprises one or more combustion steam cracking furnaces (110), one or each of the second steam cracking furnace units (2000) comprises one or more electric steam cracking furnaces (210), and one or each of the first steam cracking furnace units (1000) comprises means for preheating at least a portion of the combustion air supplied to the one or more combustion steam cracking furnaces (110) to a temperature level of at least 100° C. The corresponding system (100) is also part of the invention.

Description

Technical Field

[0001] The present invention relates to a method and a system for steam cracking as described in the preamble of the independent claims.

Background Art

[0002] The present invention is based on steam cracking technology for producing olefins and other base chemicals, as described, for example, in the article "Ethylene" in Ullmann’s Encyclopedia of Industrial Chemistry, online publication on April 15, 2009, DOI: 10.1002 / 14356007.a10_045.pub2.

[0003] Currently, the thermal energy required to initiate and sustain the endothermic decomposition reaction in steam cracking is provided by burning fuel gas in a refractory furnace. The process gas, which initially contains the vapor and hydrocarbons to be decomposed, is passed through a so-called cracking coil placed inside a refractory enclosure, also called the radiant zone or section. In this flow path, the process gas is continuously heated, enabling the occurrence of the desired decomposition reaction inside the cracking coil. Thus, the process gas is continuously enriched in the cracking products. The typical inlet temperature of the process gas entering the cracking coil is between 550 and 750 °C, and the outlet temperature typically ranges between 800 and 900 °C.

[0004] In addition to the radiant area, a combustion cracking furnace comprises a so-called convection area or section and a so-called quench area or section. The convection area is usually located above the radiant area and consists of various pipe bundles that cross the flue gas duct from the radiant area. The main function of the convection area is to recover as much energy as possible from the hot flue gas leaving the radiant area. In fact, typically only 35 to 50% of the total combustion load in the radiant area is transferred to the process gas through the cracking coil. Thus, the convection area plays a central role in the energy management of steam cracking, as it is responsible for the beneficial use of approximately 40 to 60% of the heat input (i.e., combustion load) to the furnace. In fact, when the radiant and convection areas are used together, modern steam cracking facilities (fuel Lower heating amount Utilize 90 to 95% of the total combustion load (based on net calorific value). In the convection section, the flue gas is cooled to a temperature between 60 and 140°C before leaving the convection section and being released into the atmosphere through the chimney.

[0005] The heat of flue gas recovered within the convection chamber is typically used for process tasks such as preheating boiler feedwater and / or hydrocarbon feed, (partial) vaporization of liquid hydrocarbon feed (with or without prior process steam injection), and superheating of process steam and high-pressure steam.

[0006] The quench area is located downstream of the radiating area along the main process gas pathway. The quench area consists of one or more heat exchanger units, each having the main functions of rapidly cooling the process gas below the maximum temperature level to stop the cracking reaction, further cooling the process gas for downstream processing, and effectively recovering sensible heat from the process gas for further energy use. Further cooling or quenching can be achieved through the injection of liquid, for example, by oil quench cooling in the case of steam cracking liquid feedstocks.

[0007] The heat of process gases recovered within the quench section is typically used to vaporize high-pressure (HP) or super-high-pressure (SHP) boiler feedwater (typically in the pressure range between 30 and 130 bar absolute pressures) and to preheat the same boiler feedwater before supplying it to the steam drum. The saturated high-pressure or super-high-pressure steam generated accordingly is superheated within the convection section (see above) to produce superheated high-pressure or super-high-pressure steam, which is then distributed from the convection section to the facility's central steam system, providing heat and power to heat exchangers and steam turbines or other rotating equipment. A typical degree of steam superheating achieved within the convection section of a furnace is the saturation temperature (dew point). room ) Rather 150 to 250K high temperature Generally, steam cracking furnaces can operate with high-pressure steam (typically in the range of 30 to 60 bar) or very high-pressure steam (typically in the range of 60 to 130 bar). For clarity, in the description of this invention, high-pressure steam is used for the entire pressure range between 30 and 130 bar, but this upper limit is also exceeded as this invention uses steam at pressures up to 175 bar.

[0008] A crucial part of the treatment of process gas after quench cooling is compression, which is typically performed after further processing, such as the removal of heavy hydrocarbons and process water, to prepare the process gas for separation. This compression, also called process gas or cracked gas compression, is typically carried out in a multistage compressor driven by a steam turbine. In the steam turbine, steam at appropriate pressure from the central steam system of the facility described above can be used, and therefore steam containing steam generated using heat from the convection section and quench cooling can be used. Typically, in conventional steam cracking facilities, the heat of the flue gas (in the convection section) and the heat of the process gas (in the quench section) are well balanced with the heat demand to generate most of the amount of steam required for heating and driving the steam turbine. In other words, waste heat can be more or less fully utilized to generate the steam required within the facility. Further heat for generating steam can be provided in a (combustion) steam boiler.

[0009] For reference, and to further explain the background of the present invention, a simplified schematic diagram of a conventional combustion steam cracking device is shown in Figure 1, labeled 900.

[0010] The steam cracking apparatus 900 shown in Figure 1 comprises one or more cracking furnaces 90, as indicated by the highlighted lines. A typical steam cracking apparatus 900 may comprise multiple cracking furnaces 90 that can operate under the same or different conditions, but for the sake of brevity, we will refer to "one" cracking furnace 90 below. Furthermore, the cracking furnace 90 may comprise one or more of the components described below.

[0011] The cracking furnace 90 comprises a radiating zone 91 and a convection zone 92. In embodiments other than those shown in Figure 1, several radiating zones 91 can be linked to a single convection zone 92, etc.

[0012] In the illustrated example, several heat exchangers 921 to 925 are arranged within the convection area 92 in the illustrated configuration or sequence, or in a different configuration or sequence. These heat exchangers 921 to 925 are typically provided in the form of tube bundles passing through the convection area 92 and are located within the flue gas flow from the radiant area 91.

[0013] In the illustrated example, the radiant area 91 is heated by a plurality of burners 911, which are positioned on the floor and wall sides of the refractory material forming the radiant area 91, as is only partially shown. In other embodiments, the burners 911 may be provided only on the wall side or only on the floor side. Arrangement on the floor side only may be preferred, for example, when pure hydrogen is used for combustion.

[0014] In the illustrated example, a hydrocarbon-containing gas or liquid feed stream 901 is supplied to the steam cracking device 900. Several feed streams 901 may be used in the illustrated configuration or in a different configuration. The feed stream 901 is preheated in the heat exchanger 921 of the convection area 92.

[0015] Furthermore, the boiler feedwater flow 902 is passed through the convection zone 92, or more precisely, the heat exchanger 922, which preheats the boiler feedwater flow 902. The boiler feedwater flow 902 is then introduced into the steam drum 93. In the heat exchanger 923 within the convection zone 92, the process steam flow 903, typically supplied from a process steam generation system located outside the furnace system of the steam cracking unit 900, is further heated and, in the example shown in Figure 1, is then mixed with the feedwater flow 901.

[0016] The feed and steam flow 904 generated in response is passed through a further heat exchanger 925 in the convection area 92, and then through the radiation area 91, typically through several cracking coils 912, to generate a decomposition gas flow 905. The example in Figure 1 is considerably simplified. Typically, the corresponding flow 904 is evenly distributed across several cracking coils 912, and the decomposition gases generated within the cracking coils 912 are collected for the generation of the decomposition gas flow 905.

[0017] As further shown in Figure 1, the steam flow 906 may be recovered from the steam drum 93 and (super)heated in a further heat exchanger 924 within the convection area 92 to generate a high-pressure steam flow 907. The high-pressure steam flow 907 may be used within the steam cracking device 900 in any suitable location and for any suitable purpose not specifically illustrated.

[0018] The decomposition gas flow 905 from the radiation area 12 or cracking coil 912 is passed through one or more transfer lines to a quench exchanger 94, where the decomposition gas flow 905 is rapidly cooled for the reasons described above. The quench exchanger 94 illustrated herein represents a primary quench (heat) exchanger. In addition to such a primary quench exchanger 94, further quench exchangers may be present.

[0019] The cooled decomposition gas stream 907 is passed through further process units 95, which are shown here only in a very schematic manner. These further process units 95 may, in particular, be process units for removing impurities from the separated gas, compression and fractional distillation, as well as a compressor apparatus including a steam turbine, shown as 96, which can operate using steam from a steam drum 93.

[0020] In the illustrated example, the quench exchanger 94 operates with a water flow 908 from the steam drum 93. The steam flow 909 generated within the quench exchanger 94 is returned to the steam drum 93.

[0021] Objective of the present invention Ongoing efforts to reduce at least localized carbon dioxide emissions from industrial processes extend to the operation of steam cracking facilities. As in all technological fields, localized carbon dioxide emission reductions can be achieved, in particular, by electrifying some or all of the process units where possible.

[0022] As described in Patent Document 1 in relation to reforming furnaces, in addition to a burner, a voltage source can be used, and the voltage source is connected to the reaction tube so that the current generated by the voltage source heats the raw materials. Steam cracking furnaces in which electrically heated steam cracking furnaces are used have been proposed, for example, in Patent Documents 2, 3 and 4. Electric furnace technology has been disclosed in other situations or in a broader context, for example, in Patent Documents 5, 6, 7, 8 and 9, or in older documents such as Patent Documents 10, 11, 12 and 13.

[0023] Patent Document 14 discloses a hydrocarbon flow cracking process, which is carried out by: (a) burning fuel in the presence of compressed air in order to produce flue gas, the flue gas acting to drive the turbine and generate electricity in a connected generator or to power connected rotating equipment; (b) supplying a first portion of flue gas to a heat exchanger; (c) supplying ambient air to the heat exchanger heated by the first portion of flue gas to bring heated air; (d) supplying fuel and a mixture of the second portion of flue gas obtained in step (c) and heated air to a furnace; and (d) cracking the hydrocarbon flow in the furnace.

[0024] According to Patent Document 15, the combustion air for a steam cracking furnace is preheated by indirect heat exchange between intermediate-pressure steam and low-pressure steam, and the intermediate-pressure steam and low-pressure steam are expanded from high-pressure steam generated in the high-temperature section of an ethylene production facility via a steam turbine.

[0025] Completely or partially modifying the heating concept of a steam cracking facility, i.e., using heat generated by electrical energy, rather than heat generated by the combustion of fuel, is a fairly significant intervention. As an alternative, less invasive redesign options are often preferable, especially when modifying existing facilities. These may include, for example, replacing the steam turbine used to drive the process gas compressor or different compressors with at least partially electric drive. As mentioned above, such a steam turbine can operate partially with steam generated from waste heat recovered within the convection section of the cracking furnace, but typically, a combustion steam boiler must be added to supply a sufficient amount of steam. Therefore, replacing the steam turbine used to drive the aforementioned compressors with at least partially electric drive may be suitable for reducing or avoiding the load on the combustion boiler, thereby reducing localized carbon dioxide emissions. [Prior art documents] [Patent Documents]

[0026] [Patent Document 1] European Patent Application Publication No. 3075704 [Patent Document 2] International Publication No. 2020 / 150244 [Patent Document 3] International Publication No. 2020 / 150248 [Patent Document 4] International Publication No. 2020 / 150249 [Patent Document 5] International Publication No. 2020 / 035575 [Patent Document 6] International Publication No. 2015 / 197181 [Patent Document 7] European Patent Application Publication No. 3249028 [Patent Document 8] European Patent Application Publication No. 3249027 [Patent Document 9] International Publication No. 2014 / 090914 [Patent Document 10] German Patent Application Publication No. 2362628 [Patent Document 11] German Patent Application Publication No. 1615278 [Patent Document 12] German Patent No. 710185 [Patent Document 13] German Patent Application Publication No. 3334334 [Patent Document 14] International Publication No. 2018 / 020399 [Patent Document 15] US Patent No. 4,617,109 [Non-Patent Document]

[0027] [Non-Patent Document 1] Ullmann's Encyclopedia of Industrial Chemistry, April 15, 2009, online publication, DOI:10.1002 / 14356007.a10_045.pub2, entry "Ethylene" [Overview of the Initiative] [Problems that the invention aims to solve]

[0028] However, as will be further explained below, electrification of such parts of a facility has a significant impact on the thermal equilibrium of the entire facility. Specifically, if the steam turbine that drives the compressor is replaced with an electric drive, the waste heat generated within the facility that was previously used to drive the steam turbine can no longer be fully utilized. On the other hand, if the combustion furnace is replaced with an electric furnace, the waste heat from the flue gas that was previously used for steam supply, feed heating, etc., becomes unavailable.

[0029] In other words, replacing any carbon dioxide emission component in a steam cracking system has a significant impact on the overall operation of the facility and is not simply a matter of swapping one component for another. Therefore, the efficient and effective integration of such components into a steam cracking facility is of paramount importance for the overall facility design, particularly in terms of energy management. Thus, this is the objective of the present invention.

[0030] In connection therewith, the present invention relates in part to situations in which a combustion steam cracking furnace is partially replaced by an electrically heated steam cracking furnace, or in situations in which an electrically heated steam cracking furnace is provided in addition to a combustion steam cracking furnace, so that substantially less or no steam is produced from the electric furnace for steam consumers such as steam turbines or rotating machinery. Furthermore, in the context of the present invention, pumps, compressors or other rotating machinery may be driven at least partially by electric energy rather than by the use of a steam turbine. In detail, the present invention relates to situations in which the “fully electrified” steam cracking facility is achieved only partially, i.e., with respect to the electric combustion furnace, while other furnaces are “partially electrified” by the use of electrically driven rotating machinery. In such situations, as described above, an adapted mode of operation must be found, because the conventional well-balanced steam production and consumption situation is almost completely altered in the fully electrified portion, but the conventional well-balanced steam production and consumption situation is also lost in the partially electrified portion. [Means for solving the problem]

[0031] Against this backdrop, the present invention proposes a method and system for steam cracking having the features of the independent claims. Embodiments of the present invention are the subject of the dependent claims and the following description.

[0032] Before further describing the features and advantages of the present invention, some terms used herein will be further explained.

[0033] The term “process steam” refers to the steam added to a hydrocarbon feed before it undergoes steam cracking. In other terms, process steam is a part of the corresponding feed. Thus, process steam is involved in the steam cracking reaction, which is generally known. Process steam includes, in particular, steam from the vaporization of “process water,” where “process water” is water that has been previously separated from a mixed hydrocarbon / water stream, for example from process gas recovered from a steam cracking furnace, or from a fraction of process gas, in particular by gravity separation in a vessel / coalesser, deoxygenation unit, or by the use of a filter.

[0034] "Process gas" is a gas mixture that is passed through a steam cracking furnace and subsequently subjected to processing steps such as quenching, compression, cooling, and separation. When supplied to a steam cracking furnace, the process gas includes the steam and educt hydrocarbons subjected to steam cracking; i.e., the "feed stream" subjected to steam cracking is also referred to herein as process gas. Where identification is necessary, the process gas is indicated by phrases such as "process gas introduced into the steam cracking furnace" and "process gas efluent" or similar. Upon leaving the steam cracking furnace, the process gas is enriched with cracking products and, in particular, depleted with extractable hydrocarbons. During subsequent processing steps, the composition of the process gas may change further, for example, due to fractions separated from the process gas.

[0035] The term "high-purity steam" refers to steam produced from the vaporization of purification boiler feedwater, as opposed to process steam. High-purity steam is typically specified by standards commonly used in the art, such as VGB-S-010-T-00 or similar. High-purity steam typically does not include steam produced from process water, as process water typically contains several additional components from process gases.

[0036] The term "feed hydrocarbon" refers to at least one hydrocarbon that undergoes steam cracking in a process gas in a steam cracking furnace. When the term "gas feed" is used, feed hydrocarbons include hydrocarbons having 2 to 4 carbon atoms per molecule, predominantly or exclusively. In contrast, the term "liquid feed" refers to feed hydrocarbons including hydrocarbons having 4 to 40 carbon atoms per molecule, predominantly or exclusively, with "heavy feed" being at the upper end of this range.

[0037] The term “electric furnace” can generally be used for a steam cracking furnace in which the heat required to heat the process gas within the cracking coil is supplied predominantly or exclusively by electricity. Such a furnace may include one or more electric heating devices connected to a power supply system, either via wired connection and / or inductive transmission. Inside the heating device material, the applied current generates a volumetric heat source by Joule heating. When the cracking coil itself is used as an electric heating device, the released heat is transferred directly to the process gas by convection-conduction heat transfer. When individual electric heating devices are used, the heat released by Joule heating is transferred indirectly from the heating device to the process gas, first from the heating device to the cracking coil, preferably by radiation, and less on a smaller scale, by convection, and then from the cracking coil to the process gas, by convection-conduction heat transfer. The process gas may be preheated in various ways before being supplied to the cracking furnace.

[0038] The term "combustion furnace," in contrast, generally refers to a steam cracking furnace in which the heat required to heat the process gas within the cracking coil is supplied, predominantly or exclusively, by the combustion of fuel using one or more burners. The process gas may be preheated in various ways before being supplied to the cracking furnace.

[0039] The term "hybrid heating concept" can generally be used in steam cracking when a combination of an electric furnace and a combustion furnace is used. In the context of the present invention, it is preferably anticipated that a single cracking coil belongs strictly to one combustion furnace or one electric furnace. That is, each cracking coil is heated exclusively by electrical energy or exclusively by combustion.

[0040] In this specification, the term "dominantly" may mean a proportion or content of at least 50%, 60%, 70%, 80%, 90%, or 95%.

[0041] As used herein, the term “rotating machinery” may relate to one or more components selected from compressors, blowers, pumps, and generators, such rotating machinery being rotationally driven by a mechanical energy source such as an electric motor, steam turbine, or gas turbine.

[0042] A "multi-flow heat exchanger" is a heat exchanger in which the medium to be cooled passes through multiple passages, particularly in the case of a "transfer line exchanger (TLE)" described in Ullmann's paper mentioned earlier.

[0043] Advantages of the invention To the best of the inventors' knowledge, the interpretation described above did not contain any descriptions specifically optimized for steam cracker facilities (hereinafter also referred to as "steam cracking devices" or "systems") that house not only combustion furnaces but also electric furnaces, i.e., "hybrid" facilities. Existing literature on electric heating cracking furnaces is limited to the design and operation of the electric coil heating section itself. There is little available information on the concept of integrating it into a complete furnace configuration (including preheating and quenching sections), nor is there much available information on the concept of integrating it into a broader cracker facility configuration in which a combustion furnace exists. This is true with the exception of the recent publications mentioned above, namely Patent Documents 2, 3, and 4, but even these publications do not provide solutions adapted to the joint operation of electric furnaces and combustion furnaces.

[0044] Therefore, the present invention provides, for the first time, a concept that enables the equilibrium and distribution of heat in low-to-zero emission steam crackers, which feature an electric furnace in addition to a combustion furnace. The concepts and solutions provided by the present invention enable the design of facility configurations and furnace systems that satisfy the following tasks or requirements: - Pre-mixed hydrocarbons / vapors are heated in a combustion or electric heating cracking coil or furnace from an inlet temperature between 550 and 750°C to an outlet temperature between 800 and 900°C. The hydrocarbon feed stream is preheated to the aforementioned coil inlet temperature between 550 and 750°C, from a typical feed temperature between -20 and 150°C, and, in the case of a liquid feed, the hydrocarbon feed stream is vaporized. The preheating and vaporization of the hydrocarbon feed stream is performed with or without prior addition of process vapor, which is typically supplied to the furnace system at a temperature level between 130 and 200°C. - Within one or more multi-flow heat exchangers, the process gas downstream of the cracking coil is effectively and fairly rapidly cooled to a temperature of 300 to 450°C (liquid raw material) or 150 to 300°C (gas raw material), enabling heat recovery from the process gas. - To ensure safe, reliable, and efficient operation of the facility, maintain balance in the energy flow between the electric furnace and the combustion furnace, and between the furnace system and the rest of the steam cracker facility.

[0045] Previous publications may indicate that heat from process gas flows can be recovered and utilized, for example, for feed preheating or process steam generation, but they do not provide solutions for how to supply the available process heat to other process heat consumers in steam cracker facilities and adjacent chemical complexes. While there may have been suggestions to no longer use steam as a primary energy carrier, electricity is used for all heating tasks within the facility. UnlessThe aforementioned heat supply problem remains unresolved. The above is far from energy optimization, rather than merely a minor solution, because using electricity for heating at low temperatures results in significant exergy losses. In other embodiments of the prior art, the generated steam is intensely superheated for the purpose of generating electricity in a steam turbine coupled to a generator system. This, too, is a problematic solution, because generating electricity from steam originally produced in an electric heating reactor system also results in fairly high exergy losses and suboptimal resource management.

[0046] In addition to combustion furnaces, the electric cracking furnaces used in the present invention do not feature a convection zone and therefore produce only a small amount of steam suitable for driving a steam turbine, or no steam at all. Accordingly, according to the present invention, a steam turbine that recovers the mechanical energy required to drive the main gas compressor in the separated section of the facility, or a steam turbine that generates electricity, can be at least partially replaced by electric drive. According to the present invention, such a solution is preferable and therefore enables more efficient operation of the corresponding facility. According to the present invention, the driving of fully electrified large compressors and pumps is preferably associated with the aforementioned combination of electric furnace and combustion furnace, which continuously supplies high-purity steam to other process units, preferably including modifications of steam conditions that take into account the primarily dominant use of heat (rather than electricity) of the high-purity steam, as shown below.

[0047] The present invention proposes a novel solution to the process in terms of furnace and overall facility design, as well as the described installation work, namely, the installation work of adding an electric furnace to a combustion furnace. In summary, the present invention provides a solution to the problem of "how an integrated operating concept can be realized in a hybrid steam cracker facility that mixes an electric furnace and a combustion furnace, in which the steam generator and steam consumer are at least partially modified? How can heat equilibrium and heat distribution be achieved in such a low-to-zero emission hybrid steam cracking system?" As mentioned above, replacing the potentially carbon dioxide emitting parts of the steam cracking section has a strong impact on the overall operation of the facility, and it is not a matter of swapping one component for another.

[0048] Using the two types of furnaces according to the present invention means using two different primary energy sources (electricity or fuel gas) for the furnace, one of which (fuel gas) is easier to store than the other (electricity). Therefore, a key commonality among all utilized furnace subsystems is the ability to maintain a constant chemical product production rate while changing the primary energy demand of the furnace (i.e., the total heat load absorbed by the process in the preheater and coil is constant for a constant feed flow and composition). The changes can be made by various means, for example, by changing the setpoints of flow characteristics (temperature, pressure, flow rate), by (partially) opening / closing bypass pipelines, by changing process parameters specific to the equipment (heat load, operating pressure), or by other changes to process parameters.

[0049] In addition to balancing energy for constant production in each furnace, the present invention allows for greater modifications by further changing or modifying the rate of chemical product production within the furnace. The variable steam generation and the inherent thermal energy storage in the steam system provide maximum operational flexibility to accommodate related equipment both inside and outside the steam cracker facility. Such requirements might include, for example, temporarily minimizing the inflow of electricity due to the unavailability of renewable power sources, or maximizing heat output to facilitate the initiation of steam supply to adjacent facilities or process units.

[0050] As shown in Figure 2 below, the steam cracker facility or system according to the present invention may include one or more process units dedicated to the use, production, or storage of hydrogen-enriched fractions, such as a hydrogen separation unit, an electrolysis unit, an ammonia decomposition unit, a fuel cell, or a gas storage unit. The steam cracker facility or system according to the present invention differs significantly from conventional combustion steam crackers because, when buffering of the hydrogen-enriched fuel fraction is typically not required, the fuel gas equilibrium is achieved through the import of further natural gas. In the facility according to the present invention, depending on the number of combustion furnaces in operation and the set level of combustion air preheating, the fuel gas equilibrium of the facility may fluctuate from insufficiency (import, production, and loading / unloading of fuel gas) to surplus (export, consumption, and loading of fuel gas). In particular, the fuel gas equilibrium may fluctuate from insufficiency to surplus, and vice versa, during the operation of the facility, depending on the current operating requirements described above, for example, to stabilize the power grid.

[0051] In a steam cracking system with an electric furnace, hydrogen-enriched fractions can only be consumed in limited quantities, for example, as feed for a hydrogenation reactor; otherwise, they can only be stored or transported. This is because the facility cannot directly use hydrogen as a primary energy carrier. Indirect use of hydrogen-enriched fractions can be achieved by converting them into electricity within a fuel cell, but this results in significant energy loss. The present invention offers the benefit of using large quantities of hydrogen-enriched fractions directly as an energy carrier under conditions of relatively high fuel utilization, i.e., low energy loss.

[0052] Various patent documents describe the potential use of hybrid furnaces that combine combustion coils and electric coils heated within the same furnace system, i.e., particularly within the same furnace firebox. The present invention, with full knowledge of this, excludes this solution because this latest technology does not provide a viable technical solution for how to design such a hybrid furnace in a particular form, based on considerations of all relevant process, safety, system, operation, and material requirements.

[0053] Therefore, the essence of the present invention lies not in combining heating principles inside a furnace, but in incorporating multiple flexible measures within such a hybrid facility in a larger-scale facility configuration.

[0054] The steam system used in the present invention comprises several steam headers at different pressures and temperature levels, capable of delivering heat to each consumer at the appropriate temperature level. In contrast to conventional steam cracker facilities where steam is transferred from higher-pressure steam headers to lower-pressure steam headers via turbine stages and / or descent stations, along with further boiler feedwater injection, the intermediate steam superheating in the furnace provided by the present invention, and further described below, facilitates the transfer of steam and allows for a reduction in pressure levels through the use of valves and / or nozzles. Initial steam superheating within a selected range occurs during expansion. phaseTo avoid change, various combustion furnace and electric furnace topologies can be used and combined with each other according to the present invention.

[0055] As described above, in current steam cracker facilities, the steam removed from the furnace is consumed by both turbine drive (mechanical energy recovery) and heat exchanger (thermal energy recovery), resulting in a combined thermal and electrical system. By electrifying the compressor drive, it is possible to benefit from the input of renewable electricity and reduce exergy losses caused by steam-turbine driven compressors or generators, which can also be used in general. In exchange, the modified steam system is preferably reduced to a heat recovery system. According to a particularly preferred embodiment of the present invention, electrification of at least a portion of the compressor drive is achieved, as will be further described below and as described above.

[0056] In a particularly preferred embodiment, both types of furnaces (combustion furnace and electric furnace) discharge decomposition gas vapor, which is combined for further processing in a downstream separation sequence, preferably compressed together by the use of an electrically driven compressor. Furthermore, both types of furnaces generate, preferably discharge, moderately superheated steam, which is supplied to a central steam system, the central steam system which distributes the heat in the form of steam to various process heat consumers inside and outside the steam cracker facility.

[0057] Therefore, the present invention is particularly aimed at integration into steam cracker facilities that do not involve, or at least do not involve, large-scale mechanical energy recovery from the steam flow, and utilizes this modified use case to present the concept of a cracking furnace that optimizes the furnace operation in terms of emissions and energy efficiency.

[0058] Existing prior art does not include examples of how to solve these tasks, because known integrated combustion furnace concepts rely on the generation of steam, from which mechanical energy recovery is intended, since abundant waste heat is available in conventional cracking furnaces. Integrated combustion furnace concepts rely strictly on the presence of a convection zone from which heat is recovered from a high-temperature flue gas flow. Such a convection zone does not exist in electric furnaces used in this invention, except in combustion furnaces, and therefore, a simple known combination of a combustion furnace and an electric furnace would result in a situation where significant waste heat utilization is necessary and required in the case of a combustion furnace, but not necessary and required in the case of an electric furnace. This invention also provides solutions relating to this.

[0059] Some of the aforementioned documents present similar challenges, including embodiments that combine a combustion furnace with a partially electrified separation train. While feed-effluent exchangers have been provided, detailed information on the device design is not provided, and unresolved issues regarding practical implementation remain. Embodiments known from the prior art involve the generation of powerful superheated steam in a convection chamber, with conventional extrusion steam conditions suitable, for example, for use in a steam turbine driving a decomposition gas compressor. However, the solution provided by the present invention has not been proposed.

[0060] As mentioned above, the efficient and effective integration of the electric furnace into the steam cracker is of paramount importance for the overall facility design, particularly in terms of energy management. This is especially true when a combustion furnace is present and the electric furnace is provided in addition to it, as in the present invention. A major difficulty arises, as mentioned above, from the fact that the electric heating furnace does not feature a convection zone. This is important because, as already stated, in a combustion cracking furnace, 40 to 60% of the total heat input can be recovered in the convection zone and used for various purposes.

[0061] According to the present invention, a steam cracking method is proposed using a steam cracking apparatus or system, the apparatus or system comprising one first steam cracking furnace unit or a plurality of first steam cracking furnace units and one second steam cracking furnace unit or a plurality of second steam cracking furnace units. According to the present invention, each of the one first steam cracking furnace unit or a plurality of first steam cracking furnace units comprises one or more combustion steam cracking furnaces, and each of the one second steam cracking furnace unit or a plurality of second steam cracking furnace units comprises one or more electric steam cracking furnaces. Furthermore, according to the present invention, each of the one first steam cracking furnace unit or a plurality of first steam cracking furnace units comprises means adapted to preheat at least a portion of the combustion air supplied to one or more combustion steam cracking furnaces to a temperature of at least 100°C. For specific advantages of the solution provided by the present invention, please refer to the following description. On the other hand, further advantageous embodiments will be described below.

[0062] In the language used herein, the term “furnace unit” refers to an apparatus comprising at least one steam cracking furnace from which decomposition gases are recovered from the steam cracking furnace(s), at least one quench cooling row, and at least one steam generator thermally coupled to the quench cooling row(s). The term “furnace” is used for electrically operated steam cracking coil boxes and associated feed preheating and / or steam superheating equipment, and for combustion steam cracking coil boxes (radiation zone) and associated feed preheating and / or steam superheating equipment (convection zone) and / or combustion air preheating equipment. Thus, when referring to “coil boxes” of electric furnaces below, the coil box refers to the part of the furnace in which the cracking coils are located and only the process gases are heated to a considerable extent, up to the maximum temperature level, but not to preheating equipment for other flows.

[0063] In one embodiment of the method according to the present invention, to partially repeat what has just been described, in each of one first steam cracking furnace unit or a plurality of first steam cracking furnace units, in each of one second steam cracking furnace unit or a plurality of second steam cracking furnace units, one or more steam cracking furnaces are connected to at least one quench cooling row which is thermally coupled to at least one steam generator.

[0064] More specifically, in a first steam cracking unit, a first (combustion) steam cracking furnace is connected to a first quench cooling row, and in a second steam cracking unit, a second (electric) steam cracking furnace is connected to a second quench cooling row. When referring to "one" steam cracking furnace preferably provided together with further devices within a unit called a "steam cracking furnace unit," it should be noted that this does not exclude the possibility of further "first" or further "second" steam cracking furnaces or units, and that these may be connected individually or in groups to a common "first" or "second" quench cooling row, or individually to several "first" or "second" quench cooling rows. Hereafter, when any unit is referred to in the singular, the sole reason is to simplify the language describing the invention without limiting the scope of the invention.

[0065] In the process according to the present invention, in particular, multiple process gas flows are passed simultaneously through a first steam cracking furnace and a second steam cracking furnace, and then through quench cooling rows connected to the first and second steam cracking furnaces of the first and second steam cracking furnace units, respectively.

[0066] According to the present invention, the steam generator produces at least superheated high-pressure steam at a first pressure level and a first temperature level between 30 and 175 bar absolute pressures, and no steam is produced at temperature levels higher than the first temperature level. The superheated high-pressure steam at the first pressure level is at least partially adiabatic and equidistant, particularly in a common steam supply and distribution system. Enthalpi The steam is expanded to a second pressure level, which is below the first pressure level, and the temperature level of the superheated high-pressure steam drops to the second temperature level. The first temperature level is adiabatic and equidistant. Enthalpi During expansion, each intermediate temperature level that reaches an intermediate pressure level greater than 20 bar is adiabatic and equidistant. Enthalpi During expansion, the dew point of the vapor at each intermediate pressure level Rather 5 to 120K high temperature It is selected in such a way.

[0067] According to one embodiment of the present invention, the steam cracking furnaces (or more) of a first steam cracking furnace unit and a second steam cracking furnace unit operate simultaneously with one or more compressors and / or pumps as rotating equipment, and in particular can compress process gases or "decomposition gases" recovered from the cracking furnaces (or more) or gases and / or liquid flows discharged from the cracking furnaces (or more). According to such embodiments, the rotating equipment is at least partially driven by electrical energy. The rotating equipment may, in particular, form part of one or more separation rows of a steam cracking apparatus associated with the first and second steam cracking furnace units. Or the rotating equipment may be adapted for preparing one or more process gas flows separated within such one or more separation rows or one or more gas flows generated therefrom. The separation column can be implemented as is generally known from the literature and may include stages or equipment selected from demethane units, deethane units, depropane units, splitting units, hydrogenation units, absorption columns, rectification columns, refrigeration units, absorption devices, and heat exchangers.

[0068] Superheated high-pressure steam provides the aforementioned heat insulation and equivalents according to the present invention. Enthalpi The first temperature level at which expansion occurs is preferably adiabatic and equivalent. Enthalpi During expansion, each intermediate temperature level that reaches an intermediate pressure level greater than 20 bar is adiabatic and equidistant. Enthalpi During expansion, at each intermediate pressure level, the dew point of the vapor is 10 to 100 K higher. high temperature In particular, 20 to 80K It is a high temperature. It will be selected in that way.

[0069] In other words, in all cases, the expanding steam is kept at a moderately superheated level by selecting a first temperature level according to the present invention, while at the same time being kept at a sufficient distance from the boiling point curve throughout the entire expansion process for all intermediate pressure levels above 20 bar. The boiling point curve is particularly relevant in the case of expansion initiated from a first pressure level greater than 40 bar, such as when it can reach or at least temporarily pass through the two-phase region. This is avoided by the present invention. Furthermore, by limiting steam superheating according to the present invention, the heat exchange load at high temperatures in non-essential steam generation processes is reduced, thereby increasing the availability of high-temperature heating resources for essential process heating purposes, such as feed preheating.

[0070] At the first pressure and temperature levels, the superheated high-pressure steam preferably does not contain steam generated from process water, and preferably contains only steam generated from boiler feedwater. Therefore, the superheated high-pressure steam is preferably high-purity steam as defined by steam. The superheated high-pressure steam is preferably not used when generating one or more process gas flows. That is, the superheated high-pressure steam does not participate in the steam cracking reaction.

[0071] In other words, according to the present invention, a moderately superheated, high-purity steam stream is generated and discharged at a corresponding pressure level, i.e., a first pressure level, and the term “discharged” in this context refers to recovery from the steam generator and not, or not necessarily, recovery from the entire system. This steam may also be called “dry” steam because the steam superheating level is essentially selected to prevent condensation, for example, that could cause wear during steam transport. In some cases, adiabatic and equivalent processes are applied by reducing the pressure to a minimum pressure, i.e., a second pressure level. Enthalpi If expansion is present, the dew point of the vapor stream at any intermediate pressure level above 20 bar during expansion. room This falls within the scope already described above.

[0072] The present invention, together with the measures already described above and, in particular, further described below in relation to further embodiments, proposes a novel concept for redesigning a combustion steam cracker furnace in the context of a partially electrified "hybrid" steam cracker facility or system design.

[0073] The solution for limiting the superheating of high-pressure steam according to one embodiment of the present invention breaks with the current state of technology in steam cracker design based on conventional combustion furnaces and large turbine-driven rotating equipment. This technological choice represents the most efficient solution in the context of partially electrified steam cracker design, where "partially electrified" means that some, though not all, cracking furnaces and, according to embodiments, are related to rotating equipment, while some steam cracking furnaces are still provided as combustion furnaces according to the present invention.

[0074] In fact, in the furnace section (typically at the furnace outlet, the dew point is greater than 150K), roomThe current practice of generating highly superheated, high-pressure steam (as found in conventional systems) is due to the presence of a large amount of waste heat energy within the convection chamber, as well as the possibility of using steam to drive compressors and pumps or generators within the steam turbine. Reduced-pressure steam, taken from the turbine extraction section or turbine outlet, is further used to supply process heat at various levels. Therefore, flexibility regarding steam generation and use is limited in conventional systems.

[0075] More specifically, the electric cracking furnace(s) used in the present invention are configured without a convection zone. Where the “convection zone-less” electric cracking furnace is referred to herein, this relates to the absence of a zone from which a significant amount of process heat, typically more than 500 kW, is continuously recovered from the flue gas flow. In other words, a convection zone-less electric cracking furnace is a cracking furnace without carbon dioxide emissions from a flue gas flow that intentionally cools and continuously recovers a significant amount of process heat, typically more than 500 kW. However, the furnace system features carbon dioxide emission sources that are not intended for the process, such as safety-related pilot burners at the outlet of the gas exhaust chimney. However, these result in significantly low amounts of generally unrecoverable heat.

[0076] Therefore, generally speaking, in an electric furnace coil box (or more), during hydrocarbon cracking operations, preferably 1000 kW or less of heat is transferred as sensible heat to a flow other than the process gas flow, and this flow is passed through or recovered from the electric cracking furnace box (or more) according to the present invention. Such other flows may be, for example, high-purity vapor flows. In other words, the heat transferred to the flow other than the process gas within the coil box may be 5% or less or 3% or less of the heat transferred to the process gas within the same coil box. For the term "coil box," please refer to the explanation already given above.

[0077] In a partially electrified system, using an electric compressor drive instead of a steam turbine in the cracker separation column used for the cracking furnace according to the present invention results in a reduction of exergy losses. Therefore, after removing the steam turbine, there is no efficient use of highly superheated, high-pressure steam in the separation column. Thus, by reducing the superheating level, the present invention enables the use of most of the thermal energy recovered in the furnace's quench and convection sections for preheating required for the main process flow or its components, i.e., feed hydrocarbons and / or process steam. Furthermore, as will be further described below, such thermal energy can be used to preheat the combustion air in which the fuel is burned.

[0078] Accordingly, according to a particularly preferred embodiment of the present invention, one or more process flows before passing through one or more cracking furnace coil boxes of the cracking furnace(s) of the first and / or second cracking furnace unit, or feed hydrocarbons and / or process vapors used to generate one or more process flows, or air used for combustion, are at least partially heated using heat recovered from one or more process flows downstream of the coil box(s), i.e., heat recovered from “process gases” or “decomposition gases” generated from process gases.

[0079] The heat recovered from one or more process flows downstream of the cracking furnace coil box(s) is, in particular, at least partially recovered from one or more direct feed-effleurent exchangers, i.e., one or more process flows downstream of the coil box(s) in one or more heat exchangers that have direct thermal contact with one or more process flows before they pass through the coil box(s), or from feed hydrocarbons and / or process vapors used to generate one or more process flows. "Direct thermal contact" is understood herein to be achieved by heat transfer through one or more (metal) interface layers of one or more direct feed-effleurent heat exchangers, rather than by heat transfer through an intermediate heat exchange fluid.

[0080] Alternatively or additionally, the heat recovered from one or more process flows downstream of the cracking furnace coil box of the first and / or second cracking furnace unit(s) can be at least partially recovered from one or more process flows downstream of the coil box(s) using steam, which is then used to heat the one or more process flows before they pass through the coil box(s), or the feed hydrocarbons and / or process steam used to generate the one or more process flows.

[0081] In a particularly preferred embodiment of the present invention, feed preheating, i.e., at least a portion of the heating of one or more process flows, or feed hydrocarbons and / or process steam used to generate one or more process flows, before passing through the furnace coil box of the cracking furnace(s) of the first and / or second cracking furnace unit, may be carried out for saturated steam or moderately superheated high-pressure steam in the multi-flow heat exchanger of the steam generator.

[0082] In all embodiments of the present invention, within a given range, i.e., moderate superheating at a first temperature level, further enables a simple and flexible heat supply to process heat consumers. This is because the distribution to consumers at different temperature levels allows for the single-phase adiabatic and equal distribution of moderately superheated steam discharged by the furnace. Enthalpi This can be done simply by expansion, and in particular, it does not require a descent station for the entire steam level and / or a turbine stage like in conventional equipment, with additional boiler feedwater injection for superheat reduction. In conventional equipment, such measures are necessary because the steam parameters and steam expansion of the superheated steam are largely governed by the steam requirements of the rotating equipment driven by the steam.

[0083] The steam generator is used, in particular, for the generation of saturated steam and subsequent moderate superheating of saturated steam. According to the present invention, saturated steam generation can be carried out predominantly or entirely within one or more quench cooling rows located downstream of the cracker coil box of the cracker(s) of a first and / or second cracker unit, i.e., within one or more primary and / or secondary quench exchangers. Moderate steam superheating provided by preferred embodiments of the present invention can be carried out predominantly or entirely within one or more convection sections of a combustion cracker(s), particularly within a heat exchanger bundle located between feed preheating bundles, while in the case of a second (electric) cracker(s) unit(s), it can be carried out within the quench cooling rows(s). In each case, steam superheating can be carried out in one or more superheating stages, particularly when heating in a convection section, with or without intermediate boiler feedwater injection. Some preheating of the boiler feedwater may be performed within the economizer bundle (located within the convection zone of the combustion furnace) and / or within one or more secondary or tertiary quench exchangers (located within the quench cooling row of the furnace unit).

[0084] The terms "primary," "secondary," and "tertiary" are used in relation to quench exchangers and essentially refer to the position of the quench exchanger within the quench cooling train, although a fixed relationship in terms of process task may not exist. Current state-of-the-art technology for liquid-feed furnaces anticipates two quench exchangers, while three quench exchangers are typically provided for gas-feed furnaces. Earlier furnace designs commonly featured configurations with only one quench exchanger. In a standard furnace design, the primary exchanger is typically the vaporizer. do Secondary quench exchangers cool the boiler feedwater. Secondary quench exchangers (partially) vaporize or preheat the boiler feedwater. Tertiary quench exchangers typically preheat the boiler feedwater. A notable exception is when a quench exchanger is used for feedwater preheating.

[0085] According to the present invention, the quench cooling train operates to comprise, at least, preferably, at least two separate cooling stages, in the case of an electric furnace (or more), in a first cooling stage, at least a portion of the process gas flow recovered from the electric cracking furnace is cooled against vaporization boiler feedwater at an absolute pressure level between 30 and 175 bar, more specifically between 60 and 140 bar, and more specifically between 80 and 125 bar; and in a second cooling stage, at least a portion of the process gas flow recovered from the electric cracking furnace is cooled against a superheated mixture of feed hydrocarbons and process steam used to generate the process gas flow, thereby heating the process gas flow to a temperature between 350 and 750°C, more specifically between 400 and 720°C, and more specifically between 450 and 700°C, i.e., the typical inlet temperature level of the cracking furnace.

[0086] The present invention differs from all known combustion furnace integrated systems in that, at least insofar as it relates to electric furnaces, neither feed preheating nor steam superheating is performed on the flue gas (due to the absence of a convection zone). Contrary to previously proposed electric furnace integrated concepts, the present invention explicitly anticipates the use of steam as a primary energy carrier, and more specifically, as a heat carrier for process heat consumers at various temperature levels. Steam generation and discharge conditions are specifically designed to suit the intended purpose of heat dissipation within the steam cracker facility and adjacent chemical complexes.

[0087] Furthermore, saturation High pressure Steam and / or moderately superheated high-pressure steam 、 and Therefore The topology used in embodiments of the present invention, which preheats feed hydrocarbons, process steam, and boiler feedwater to a temperature of approximately 300°C using only the obtained condensate, represents a solution of the present invention for performing the tasks of these processes in an electric furnace, where, unlike a combustion furnace, further waste heat from flue gas is not available. These solutions have the advantage of using a heat transfer medium directly available in the furnace, thereby reducing the need for tubing, minimizing exergy loss by keeping the temperature difference within the heat exchanger small, and preferably performing supercooling of the generated condensate for maximum heat recovery.

[0088] In terms of dynamic behavior, the ability to balance and buffer changes in hydrogen or other fuel gas consumption by the steam system (see below for further details) facilitates the integration of such steam cracker facilities into industrial complexes, preferably supplied with renewable electricity.

[0089] According to corresponding embodiments of the present invention, by limiting the use of steam solely for process heat purposes and setting steam parameters accordingly, the steam system can operate flexibly (with respect to pressure and temperature) and can further be used as a temporary energy buffer by, for example, changing the steam superheating and / or pressure level during operation. This is facilitated by the fact that the generated steam is not used for power generation within a steam turbine, which is not as tolerant of fluctuations in steam conditions as a steam-based heat exchanger.

[0090] Modifications to the output of electrical energy to the electric furnace can be achieved in various ways in different embodiments, for example, by modifying the setpoint of the controlled outlet temperature of a particular heat exchanger. In one embodiment, such a modification is achieved by reducing the outlet temperature of the steam supply heat exchanger, thereby increasing the total output of electrical energy to other heat exchangers and / or heating coils, while maintaining the same chemical production load of the furnace. In embodiments involving electric steam superheating, the modification can be easily made by changing the load.

[0091] Therefore, according to the present invention, preferably, the steam produced by one or more steam generators is not used in a steam turbine drive unit that delivers a shaft force greater than 1 MW, and preferably, not used at all in a steam turbine or other rotating equipment as defined above. In other words, according to the present invention, steam turbines supplied with steam from steam generators (may be more than one) and steam turbines that deliver a shaft force greater than at least 1 MW are not used.

[0092] According to the present invention, a quench cooling train is preferably used that comprises a primary quench exchanger and a secondary quench exchanger, wherein the primary quench exchanger is used to carry out at least part of a first cooling stage, the secondary quench exchanger is used to carry out at least part of a second cooling stage, and vice versa. Corresponding embodiments of the present invention will be further described in detail with reference to the accompanying drawings.

[0093] According to the present invention, a multi-flow heat exchanger and / or an electric steam superheater can be used in a steam generator, in which heat transferred from the process gas flow recovered from the coil box(s) of an electric cracking furnace(s) is transferred to the boiler feedwater flow and / or the steam flow used to generate superheated high-pressure steam. Furthermore, at least a portion of the feed hydrocarbons used to generate the superheated mixture of feed hydrocarbons and process steam, i.e., the process flow to be subsequently decomposed, can be preheated in the multi-flow heat exchanger using at least a portion of the process gas flow recovered from the coil box(s). In this case, the multi-flow heat exchanger is called a feed-effluent exchanger.

[0094] The steam superheating levels provided by the present invention are quite suitable when the steam flow discharged from the furnace system is intended solely to supply process heat to the consumer. Enthalpi Due to expansion, the steam superheating level is phase Without alteration, the pressure and temperature can be reduced to the pressure and temperature levels required by the heat sink, i.e., the heat "consumer". Therefore, according to the present invention, preferably, the steam produced by one or more steam generators is not used in a steam turbine drive that delivers a shaft force greater than 1 MW, and preferably, not used at all in a steam turbine drive or other rotating equipment. In particular, according to the present invention, common steam expansion can be carried out for moderately superheated, high-pressure steam produced using heat from combustion furnaces and electric furnaces. However, the corresponding steam flow may, alternatively, be expanded in individual units.

[0095] In detail, preheating the combustion air used in the combustion of one or more combustion cracking furnaces provided by the present invention reduces fuel gas consumption and flue gas emissions. This preheating is considered more efficient than conventional methods of generating electricity using superheated steam from furnaces that do not preheat the air, and therefore, using any suitable means, as provided by one embodiment of the present invention, results in combustion air temperature levels above 100°C, preferably above 150°C, more preferably above 200°C, most preferably above 300°C, for example, up to 1000°C. Such preheating of combustion air may not be as advantageous in conventional devices that rely on large amounts of heat from the flue gas flow required for steam generation.

[0096] In one embodiment, the combustion air is preheated outside the flue gas path, also known as “external” combustion air preheating. In this embodiment, combustion air preheating is preferably carried out by the use of saturated steam produced in one or more quench cooling rows, and thus in one or more multi-flow heat exchangers that form part of the steam generator. Alternatively, moderately superheated steam may be used in combustion air preheating, either alone or in addition to saturated steam. Furthermore, external steam, for example, taken from one of the facility’s central steam headers, may also be used for at least part of the combustion air preheating process. At least part of the air preheating section may divert at least one fraction of the entire gas flow so that the combustion air preheating temperature obtained during operation can be modified.

[0097] In different embodiments, the combustion air is preheated within the flue gas path, also known as “internal” combustion air preheating. In this embodiment, the combustion air preheating system may comprise one or more multi-flow heat exchangers, with the flue gas as the high-temperature medium and the combustion air as the low-temperature medium. In the case of multi-stage combustion air preheating, it is also possible to recover heat from the flue gas between two combustion air preheating stages for purposes of other processes. As in the case of (external) combustion air preheating outside the flue gas path, at least a portion of the combustion air preheating section may divert at least one fraction of the entire gas flow so that the combustion air preheating temperature obtained during operation can be modified.

[0098] In the case of internal combustion air preheating and / or external combustion air preheating, a combustion air compression device can be provided, which is typically located upstream of the combustion air preheating section and compensates for the pressure drop in the combustion air preheating exchanger. The preferred pressure on the combustion side of the radiating section or coil box is typically within the range of slightly above atmospheric pressure, as in the case of a conventional cracking furnace without air preheating. Therefore, an additional flue gas blower / compression device may preferably be located downstream of the convection section outlet.

[0099] The apparatus or system provided by the present invention can preferably operate in an energy-flexible manner. That is, a given chemical product production load of the furnace can be realized with various total fuel gas or electricity consumption rates, in particular with the use of various amounts of gas supplied for steam cracking in the form of one or more process flows. The corresponding difference between chemical energy input or electrical energy input can be balanced by changing the energy output in the form of steam, thereby changing a first temperature level and / or steam output rate, i.e., the amount of superheated high-pressure steam produced. In other words, according to one embodiment of the present invention, the steam cracking apparatus or system is operated in various operating modes, using various total fuel gas consumption rates in the case of a combustion furnace, or using various amounts of electricity in the case of an electric furnace, in particular with various amounts of gas supplied in the form of one or more process flows.

[0100] The method according to the present invention may further include releasing hydrogen-enriched fuel gas at least temporarily from an electrolysis unit, an ammonia decomposition unit and / or a hydrogen storage unit (each of which may be part of a system or apparatus according to the present invention) to supply at least temporarily any additional fuel gas needed to one first steam cracking furnace unit or at least one of a plurality of first steam cracking furnace units and / or to other hydrogen consumers.

[0101] More specifically, if at least a temporary surplus of hydrogen-enriched fuel gas is generated from a hydrogen separation unit (which may be part of a system or apparatus according to the present invention) compared to the total consumption of hydrogen in one first steam cracking furnace unit or at least one of a plurality of first steam cracking furnace units and / or other hydrogen consumers, the surplus of hydrogen-enriched fuel gas is supplied at least temporarily to a fuel cell unit and / or a hydrogen storage unit (which may be part of a system or apparatus according to the present invention).

[0102] As described above, the present invention uses two different primary energy sources (electricity or fuel gas), one of which (fuel gas) is easier to store than the other (electricity). According to the present invention, the first (combustion) steam cracking furnace can operate with a higher energy input in the first operating mode compared to the second operating mode, while the second (electric) steam cracking furnace can operate with a lower energy input in the first operating mode compared to the second mode. This allows for a change in energy source and, in particular, enables adaptation of operation to changing supply conditions, such as the amount of electricity and fuel gas available and / or their respective costs.

[0103] According to a further embodiment of the present invention, the fuel gas used for combustion in one or more combustion cracking furnaces can be heated to a certain temperature level, which is changed during the operation of the furnace.

[0104] The fuel gas used for combustion in one or more combustion cracking furnaces preferably has a hydrogen content between 0 and 100 wt%, more preferably between 20 and 100 wt%, and more preferably between 50 and 100 wt%. In this embodiment, for higher hydrogen content, the fuel gas used for combustion in one or more combustion cracking furnaces may also be supplied at least partially using hydrogen produced in an electrolysis or ammonia decomposition unit, and the operation of the electrolysis or ammonia decomposition unit may also be part of the method provided by the present invention.

[0105] According to the present invention, greenhouse gas emissions from the combustion furnace unit(s) used can be reduced by 20% to 100%, preferably 30% to 100%, and more preferably 50% to 100%, compared to conventional combustion furnaces. In this context, a conventional combustion furnace is one that operates using the conventional removal of a fuel mixture of final gas (from the low-temperature section of the cracker) and natural gas, without preheating of the combustion air.

[0106] For further details relating to the steam cracking system provided by the present invention and its preferred embodiments, please refer to the above description relating to the method of the present invention and its preferred embodiments. Advantageously, the proposed apparatus is adapted to the implementation of at least one method of the embodiments described in more detail previously.

[0107] Before proceeding to a more detailed description of embodiments of the present invention with reference to the drawings, please refer again to some details and concepts of the present invention and some embodiments.

[0108] While the expansion of steam being discharged without mechanical energy recovery may appear counterproductive or inefficient, it must be taken into consideration that the primary energy supply of the requested furnace is significantly reduced compared to conventional combustion furnaces, and preferably, the energy is supplied from a renewable source, preferably in the form of hydrogen-enriched fractions or electricity. In this sense, the present invention provides a further policy of reconfiguring the energy equilibrium within the combustion furnace (with less steam generation and more feed preheating) and incorporating electricity. The present invention also goes beyond known concepts by strictly targeting the smallest primary energy consumption within the furnace section and adapting the furnace design / operation to a highly electrified separated-row topology.

[0109] In fact, an increase in steam superheating levels in such furnaces leads to an overall increase in primary energy demand, which cannot be fully compensated by the recovery of mechanical or electrical energy in downstream turbines. Therefore, considering the less-than-ideal process performance, the moderately heated steam required by process heat consumers should be adiabatically and equidistant from a system perspective (at a larger scale) and a process / energy perspective (at a smaller scale). Enthalpi Targeted expansion is more efficient. This is even more true for facilities that have additional loss generators during fuel gas supply, such as facilities where the hydrogen burned in the furnace is at least partially supplied by an electrolysis unit and / or an ammonia decomposition unit.

[0110] By limiting the use of steam for process heat purposes and setting steam parameters accordingly, the steam system can operate flexibly and, furthermore, can be used as a temporary energy buffer by, for example, changing the steam superheating and / or pressure levels during operation. This temporary energy buffer is facilitated by the fact that the generated steam is not used for power generation within a steam turbine, which is not as tolerant of fluctuations in steam conditions as a steam-based heat exchanger.

[0111] During facility operation, the present invention allows for modifications to the air preheating temperature, for example, by diverting specific fractions of the fuel air around one or more preheating exchangers. This affects fuel gas consumption and steam production and can be used to adapt the facility's temporary energy management. This can be of considerable importance when the furnace uses fuel gas partially produced from an electrolysis unit (or ammonia decomposition unit), or when the furnace is combined with an electric furnace in a hybrid facility configuration. Steam production and superheating can also be adapted by any change in boiler feedwater injection between the two superheating zones.

[0112] Generally, according to the present invention, changes in steam generation can be made by several different means, for example, by changing the setpoint of flow characteristics (temperature, pressure, flow rate), by (partially) opening / closing bypass pipelines, by changing equipment-specific process parameters (heat load, operating pressure), or by other changes to process parameters.

[0113] Furthermore, in embodiments of the present invention, the pressure level in the steam header system outside the furnace system can be changed during operation, which may provide additional buffering capacity in terms of the overall amount of steam. In fact, the overall heat storage capacity is the sum of the steam stock in the steam cracker and the corresponding heat capacity, i.e., the steam stock in the steam cracker includes all the steam header pipelines between the furnace and the steam consumer at different pressure levels.

[0114] To summarize again what has been stated above, the present invention proposes a novel concept that ensures all of the tasks or requirements listed above are performed for a steam cracker furnace in the context of a partially electrified "hybrid" steam cracker design.

[0115] The solution for limiting the superheating of superheated high-pressure steam provided by one embodiment of the present invention particularly breaks with the current state of steam cracker designs that are based on simple combustion furnaces and large turbine-driven rotating machinery. This technological choice represents a considerably efficient solution in the context of "hybrid" designs.

[0116] In fact, in the furnace section (typically at the furnace outlet, the dew point is greater than 150K), room The current practice of generating highly superheated, high-pressure steam (as found in [the system]) has been achieved due to the presence of a large amount of waste heat energy within the convection chamber, as well as the possibility of using the steam to drive compressors and pumps or generators within the steam turbine. The reduced-pressure steam, taken from the turbine extraction section or turbine outlet, is further used to supply process heat at various levels.

[0117] In an electrified cracker separation train, using an electric compressor drive instead of a steam turbine results in a reduction of exergy losses in the steam cracker facility. Furthermore, there is no more efficient use of highly superheated, high-pressure steam in the separation train. Thus, by reducing the superheat level, the present invention utilizes most of the thermal energy recovered in the quench section for the preheating required for the feed hydrocarbon / process steam mixture, either directly or indirectly in the feed-effleent exchanger, through the use of superheated, high-pressure steam generation and steam in the feed preheating stage.

[0118] By maximizing the use of quench heat for feed preheating, the total electrical energy input to the electric furnace is reduced, thereby lowering the operating costs of the furnace, facilitating the integration of the furnace into the power grid, and reducing overall exergy losses in the furnace section. Similarly, in the combustion furnace according to the present invention, the use of quench heat and flue gas heat in the convection section is also maximized for feed preheating and even combustion air preheating, thereby reducing the total fuel gas consumption in the combustion furnace.

[0119] Of the illustrated embodiments, the variant in which the primary quench exchanger is used for steam generation offers the advantage of cooling the decomposition gas most quickly and quenching the reaction (high heat transfer coefficient due to boiling), while the variant in which the primary quench exchanger is designed as a feed-effluent exchanger offers the advantage of minimizing the transfer of electrical energy.

[0120] A given range of moderate superheating according to one embodiment of the present invention further enables a simple and flexible heat supply to process heat consumers. This is because the distribution to consumers at different temperature levels allows for single-phase adiabatic and equal distribution of moderate superheated steam discharged by the furnace. Enthalpi This can be done simply by expansion and does not require a descent station and / or turbine stage for the entire steam level, along with further boiler feedwater injection to reduce superheating.

[0121] In terms of dynamic behavior, the ability to balance and buffer changes in electricity input by the steam system facilitates the integration of such furnace systems into industrial complexes, preferably supplied with renewable electricity.

[0122] Further features and embodiments of the present invention are listed below. All of these features and embodiments can be combined with the features and implementations described above, without limitation, to the extent that they are technically feasible or separate, and are included by the claims.

[0123] -The present invention is preferably combined with a separation train in which all gas compressors or pumps with a power load exceeding 1 MW are driven by electric motors.

[0124] -The superheated, high-pressure steam being discharged is most advantageously adiabatic and equivalent. Enthalpi The expansion element distributes the vapor pressure across various levels. A single heat consumer (e.g., with important fouling checks) may further include additional superheat reduction stages (which can be implemented by direct water injection or by the use of a saturated drum).

[0125] - The steam cracking apparatus may include other units that generate steam from electrical energy (e.g., electric heat pump systems and electric boilers).

[0126] - The discharged heated steam can be expanded to a pressure steam level below an absolute pressure of 20 bar for supply to, for example, intermediate-pressure and low-pressure steam consumers. As a lower limit, the dew point at the intermediate pressure level. room The choice of an absolute pressure of 20 bar to characterize the process is selected to facilitate the definition of the curve envelope of the initial vapor superheating, so that the aforementioned distance to the boiling point curve is shown for all intermediate or second pressure levels above 20 bar. Expansion to pressures below an absolute pressure of 20 bar results in higher dew point values, although this does not limit the scope of the present invention. room This can occur.

[0127] In addition to the inherent energy storage potential through hydrogen storage tanks and / or steam superheating / pressure modification, the present invention can be further combined with other dedicated energy storage systems, such as latent heat storage systems or similar.

[0128] -The present invention is preferably combined with a separation column including a hydrogen separation unit, in which all or most (typically 70, 75, or 80 to 100%) of the hydrogen available in the feed to the separation column is recovered in the form of a process flow predominantly composed of hydrogen and used for combustion in the furnace and / or for supply to other process units, such as a hydrogenation unit.

[0129] -The furnace system according to the present invention is preferably used in a steam cracker facility or system, which includes an electrolysis unit that produces hydrogen from electricity preferably generated by a regeneration means. Alternatively or additionally, the facility or system may feature an ammonia decomposition unit that produces hydrogen from ammonia (ammonia is preferably generated elsewhere using renewable electricity).

[0130] -An embodiment of the present invention also includes a feed-effluent primary quench exchanger and moderate steam superheating.

[0131] The present invention and embodiments thereof will be further described with reference to the accompanying drawings. [Brief explanation of the drawing]

[0132] [Figure 1] This is a diagram of one embodiment that does not form part of the present invention. [Figure 2] This is a schematic diagram of the entire system or facility configuration according to one embodiment of the present invention. [Figure 3] This diagram shows how a combustion steam cracking furnace unit and an electric steam cracking furnace unit are connected in a hybrid concept according to the present invention. [Figure 4]Figure 3 shows a combustion steam cracking furnace unit usable with the hybrid concept of the present invention. [Figure 5] Figure 3 shows a combustion steam cracking furnace unit usable with the hybrid concept of the present invention. [Figure 6] Figure 3 shows a combustion steam cracking furnace unit usable with the hybrid concept of the present invention. [Figure 7] Figure 3 shows a combustion steam cracking furnace unit usable with the hybrid concept of the present invention. [Figure 8] Figure 3 shows a combustion steam cracking furnace unit usable with the hybrid concept of the present invention. [Figure 9] Figure 3 shows a combustion steam cracking furnace unit usable with the hybrid concept of the present invention. [Figure 10] Figure 3 shows a combustion steam cracking furnace unit usable with the hybrid concept of the present invention. [Figure 11] Figure 3 shows a combustion steam cracking furnace unit usable with the hybrid concept of the present invention. [Figure 12] Figure 3 shows a combustion steam cracking furnace unit usable with the hybrid concept of the present invention. [Figure 13] Figure 3 shows a combustion steam cracking furnace unit usable with the hybrid concept of the present invention. [Figure 14] Figure 3 shows a combustion steam cracking furnace unit usable with the hybrid concept of the present invention. [Figure 15] Figure 3 shows a combustion steam cracking furnace unit usable with the hybrid concept of the present invention. [Figure 16] Figure 3 shows a combustion steam cracking furnace unit usable with the hybrid concept of the present invention. [Figure 17] This graph illustrates the advantages of the embodiments of the present invention. [Figure 18] This graph illustrates the advantages of the embodiments of the present invention. [Figure 19] This graph illustrates the advantages of the embodiments of the present invention. [Figure 20] Figure 3 shows a diagram of a further combustion steam cracking furnace unit usable in the hybrid concept of the present invention. [Modes for carrying out the invention]

[0133] Figure 1 is as explained earlier.

[0134] Figure 2 shows a schematic diagram of the entire system or facility configuration according to one embodiment of the present invention, System 100.

[0135] System 100 includes a first or combustion steam cracking furnace unit, herein denoted as 1000, and a second or electrified steam cracking furnace unit, herein denoted as 2000. Embodiments of furnace units 1000 and 2000 are shown in Figures 4 to 16 below, indicated by 1100 to 1500 and 2100 to 2800.

[0136] In Figure 2, double-line arrows indicate hydrocarbon feed flows, process gas flows, or decomposition gas flows, and flows generated from these, such as hydrocarbon fractions. Single-dotted arrows indicate fuel gas flows, air flows, flue gas flows, and exhaust flows. Fine-lined arrows indicate process vapor flows, while coarse-lined arrows indicate superheated vapor flows. Condensate flows are indicated by solid-line arrows.

[0137] The hydrocarbon feed 3001 is pre-treated and pre-heated in the pre-treatment and pre-heating unit 3100, which is also supplied with further flows as described below. From the pre-treatment and pre-heating unit 3100, the pre-treated feed flows 3002 and 3003 are supplied to the combustion steam cracking furnace unit 1000 and the electric steam cracking furnace unit 2000. The decomposition gas flow may be coupled to produce a flow 3004 which is passed through the decomposition gas cooling and process vapor generation unit 3200. A process vapor flow, produced from the process water separated therein and not individually labeled, may be passed from the decomposition gas cooling and process vapor generation unit 3200 to the combustion steam cracking furnace unit 1000 and the electric steam cracking furnace unit 2000.

[0138] After compression in a compression unit 3300, which can also function as a sour gas removal unit, the pre-cooled and mixed raw gas can be hydrogenated in the corresponding unit 3500, to which a hydrogen stream 4004 can be supplied. The process gas is then passed further to a de-ethane unit 3600 to produce the corresponding fraction, which is then passed, on the one hand, to a de-methane unit 3700 and the corresponding splitting unit 3800 to produce ethylene products 3006 and ethane regeneration stream 3007, and on the other hand, to a de-butanation stage 3900 to produce gasoline product stream 3008 and further regeneration stream 3009.

[0139] The separation sequence shown in Figure 2 presents only one of many possible options, depending on the type of feed and the range of preferred products. The present invention is not limited to the separation sequence shown in Figure 2 and includes all generally known separation sequences in steam cracker facilities. These include, for example, separation sequences for gas feed separators, and have separate C2, C3 and / or C4 hydrogenation units instead of a raw gas hydrogenation unit, separation rows with different process unit sequence orders (front-end demethane or front-end depropane), or separation rows for heavier gas and liquid feedstocks, typically including further process units for processing heavier hydrocarbon products.

[0140] The fuel gas system 4100 is associated with a first (combustion) cracking furnace unit 1000 and supplies a fuel gas flow 4001 to the first (combustion) cracking furnace unit 1000, which is also supplied with an air flow 4002. The flue gas flow 4003 may be released or the flue gas may be treated before being released into the atmosphere. The hydrogen flow 4004 can be supplied by an ammonia decomposition unit 4300 and / or an electrolysis unit 4400, which are supplied with ammonia and water respectively in the illustrated example, and the flows released from the ammonia decomposition unit 4300 and / or the electrolysis unit 4400 may be recovered. The hydrogen flow 4004 may also be supplied to a fuel cell unit 4500 operating on air or purified oxygen. The flue gas flow is recovered from the fuel cell unit 4500. A fuel gas or hydrogen storage unit 4600 may be provided. In the hydrogen separation unit 4700, the light gas mixture from the demethane unit 3700 is processed, yielding a hydrogen stream and the remaining methane fraction 4008.

[0141] A steam and boiler feedwater unit 5000 is provided, which is supplied with steam 5001 from furnace units 1000 and 2000, condensate 5002 from an internal process heat consumer, and boiler feedwater 5003. A condensate stream 5004 from the steam and boiler feedwater unit 5000 can be recovered and passed through a processing unit (not shown). Boiler feedwater 5005 can be supplied to furnace units 1000 and 2000. Steam for the internal process heat consumer is supplied as a steam stream 5006. Unit 5000 can exchange condensate 5007 and steam stream 5008 with an external unit.

[0142] Figure 3 shows a highly simplified diagram of the connection between the combustion steam cracking furnace unit 1000 and the electric steam cracking furnace unit 2000 in the hybrid concept according to the present invention, and illustrates the possibilities of steam cracking unit connections, which will be further shown in subsequent figures.

[0143] As described above, a first or combustion steam cracking furnace unit, indicated as 1000 in this specification, and a second or electrified steam cracking furnace unit, indicated as 2000 in this specification, are provided. Embodiments are shown in Figures 4 to 16 below.

[0144] In the (general) steam utilization apparatus shown in 50 for reference purposes only and described in more detail below, (moderately) superheated high-pressure steam SU is used for heating purposes, but preferably not substantially for driving rotating machinery. In this specification, superheated high-pressure steam SU is used, in particular, for adiabatic and equidistant purposes by the use of an expansion unit. Enthalpi It generates high-pressure steam (HP), medium-pressure steam (MP), and low-pressure steam (LP) that are expanded and can be supplied to heat consumers.

[0145] Figure 4 shows a combustion steam cracking furnace unit 1000, which can be used in a hybrid concept according to one embodiment of the present invention, as shown in Figure 3, as unit 1000, and is therefore adapted for use in carrying out a steam cracking method according to one embodiment of the present invention, and is optionally part of system 100 according to the present invention. As in the case of subsequent drawings showing a steam cracking furnace unit, the method steps of the method can be implemented by the corresponding process unit or device used, and therefore descriptions relating to the method steps may relate similarly to such process units and devices, and vice versa. Repetition of descriptions is omitted only for the sake of brevity, and combinations of phrasing describing units or systems and methods according to embodiments of the present invention are used for clarity. Where a component is described in the singular, this description does not exclude that such component is provided in the plural. The steam cracking furnace unit 1100, including other steam cracking furnace units shown below, can be part of a system 100 according to one embodiment of the present invention, which may include several further components as previously shown, and the possible boundaries of the system are only schematically shown in Figures 4 and 9.

[0146] In Figures 4 to 16 and 20, thick solid arrows indicate hydrocarbon feed flows, process vapor flows, process gas flows, or decomposition gas flows, and flows formed from these, such as hydrocarbon fractions. Thin solid arrows indicate fuel gas flows, air flows, flue gas flows, and discharge flows. Fine dotted arrows indicate liquid boiler feedwater flows, dashed arrows indicate saturated high-purity vapor flows, and dashed-dotted arrows indicate superheated high-purity vapor flows. Condensate flows are indicated by dashed-dotted arrows.

[0147] The steam furnace unit 1100 includes the use of a combustion steam cracking furnace 110, which is formed by or includes a combustion radiant area 11 and a convection area 12, as previously outlined. In the illustrated embodiment, in the convection area 12, a feed preheater 121, an economizer 122, a first high-temperature coil 123, a first steam superheater 125, an optional second steam superheater 125, and a second high-temperature coil 126 are located in a flue gas passage or duct. In particular, the second steam superheater may be omitted if boiler feedwater injection (see below) is not performed. The flue gas flow FL passes from the radiant area 11 through the convection area 12 and, in this embodiment, leaves the convection area 12 at a temperature of approximately 89°C. The radiation area 11 is combusted using a fuel gas flow FU and combustion air CA, which are preheated to a temperature of approximately 300°C in this illustrated example.

[0148] The primary quench exchanger 21, the secondary quench exchanger 22, and the tertiary quench exchanger 23 are located within the process gas path and form the quench cooling row 20 of the steam cracking furnace unit 1100.

[0149] A steam generator 30 is provided, which includes a steam drum 31 and other components used to generate steam. Generally, throughout this specification, when referring to a component or group of components belonging to one apparatus described primarily in conjunction with a particular function, this does not exclude that this component is not part of a further group of different apparatuses or components having additional or different functions, as is typical in facilities with interconnected parts. For example, the primary quench exchanger 21, secondary quench exchanger 22, and tertiary quench exchanger 23 are described herein as part of the quench cooling train 20, but they may also be integrated into the steam generator 30.

[0150] In the embodiment shown in Figure 4, the combustion air preheating unit 40, which is located outside the flue gas duct and therefore outside the convection section 12, is also part of the steam cracking furnace unit 1100.

[0151] In the method of using the steam cracking furnace unit 1100 within the corresponding system 100, process steam PS and feed hydrocarbon HC are supplied to the steam cracking furnace unit 1100. The feed hydrocarbon HC is heated in the feed preheater 121 before being combined with the process steam PS to produce a process flow PR, and the process flow PR is further heated in the high-temperature coils 123 and 126 before being supplied to the combustion radiation area 11. The process flow, also called decomposition gas or process gas and shown here as PE for clarity, is recovered from the radiation area 11 and quenched and cooled in the primary quench exchanger 21, secondary quench exchanger 22 and tertiary quench exchanger 23, which were outlined previously.

[0152] Subsequently, the process flow PE may undergo any kind of processing, including compression in a compressor 60, in particular a process gas compressor driven by an electric motor M, according to one embodiment of the present invention, as shown only in Figures 4 and 9. See the above description for further details. In particular, a separation column is provided in which all or essentially all compressors are electrically driven.

[0153] The boiler feedwater BF, also indicated by the dotted arrow, is heated in the tertiary quench exchanger 23 and economizer 122 before being supplied to the steam drum 31, and the boiler feedwater BF circuit is also formed through the secondary quench exchanger 22 and primary quench exchanger 21. The saturated steam SS recovered from the steam drum 31, also indicated by the dashed arrow, is partially superheated in the steam superheaters 124 and 125 to produce (moderately) superheated high-pressure steam SU, indicated by the dashed arrow, which is partially supplied to the combustion air preheating unit 40. The parameters of the superheated high-pressure steam SU have been described in detail previously. In the illustrated embodiment, these parameters may have a temperature of about 380°C and an absolute pressure of about 117 bar. Further boiler feedwater BF may be added between steam superheaters 124 and 125 (so-called boiler feedwater injection, as already described above), and the further boiler feedwater BF is preferably not preheated and is used in particular to control the overall thermal equilibrium within the convection zone 12, for example, to adapt to different operating points. If boiler feedwater is not injected, steam superheater 125 may be omitted as described above.

[0154] Combustion air CA to be preheated, and any external steam EX, are also supplied to the combustion air preheating unit 40. Condensate flow CO is recovered from the combustion air preheating unit 40, and condensate flow CO can be used as part of the boiler feedwater BF, which has already been described in detail.

[0155] In a steam utilization device shown in 50 for reference purposes only, and which is also connected to further steam cracking furnace units, such as a steam cracking furnace unit featuring an electric heating steam cracking furnace, superheated high-pressure steam SU is used for heating purposes, but preferably not substantially used for driving rotating machinery. In this specification, superheated high-pressure steam SU is used adiabatically and equidistantly with expansion units 51, 52, 53. EnthalpiThe steam is expanded to produce high-pressure steam HP, medium-pressure steam MP, and low-pressure steam LP, which are supplied to heat consumers 54, 55, and 56. All steam (high-pressure or ultra-high-pressure steam) discharged from the furnace can be collected in corresponding steam headers, i.e., large-capacity tubular systems that distribute the steam to various consumers on the facility. Supply connections to lower pressure steam headers are made from this highest pressure steam header. In conventional facilities, such steam headers operate at an approximately constant pressure, slightly below the steam discharge pressure at the furnace outlet. According to embodiments of the present invention, this highest pressure steam header can be more broadly modified to achieve a favorable buffering effect.

[0156] To summarize the above, in the steam cracking furnace unit 1100 shown in Figure 4, the combustion air CA is preheated outside the flue gas path ("external air preheating"). Saturated steam SS is generated entirely within the quench cooling row 20 (with primary and secondary quench exchangers 21 and 22), while moderate steam superheating occurs within the convection section 12 between the high-temperature coils 123 and 126. Steam superheating can be performed in one or more superheating stages, with or without intermediate boiler feedwater injection. Some boiler feedwater preheating can be performed in the economizer 122 and / or tertiary quench exchanger 23, as shown.

[0157] Preheating of the combustion air is preferably performed by using saturated steam SS generated in a quench section 20 in one or more multi-flow heat exchangers. Alternatively, moderately superheated steam may be used alone or in addition to saturated steam in an air preheating section (not shown in Figure 4). Furthermore, external steam EX, for example, taken from one of the facility's central steam headers, may also be used for at least part of the combustion air preheating process. At least part of the combustion air preheating unit 40 may be configured to divert at least one fraction of the entire gas flow so that the air preheating temperature obtained during operation can be modified.

[0158] Not shown is an air compression device, typically located upstream of the combustion air preheating unit 40, which compensates for the pressure drop in the combustion air preheating exchanger. Preferred pressures on the combustion side of the radiation section and further details have been previously described.

[0159] Figure 5 shows a further steam cracking furnace unit 1200 according to one embodiment of the present invention. Generally, the description relating to the steam cracking furnace unit 1100 in Figure 4 also applies to the steam cracking furnace unit 1200 in Figure 5, with only the differences being described below.

[0160] In the steam cracking furnace unit 1200 shown in Figure 5, the combustion air preheating unit 40 is integrated into the flue gas passage or duct, and saturated steam SS is not supplied as in the case of the steam cracking furnace unit 1100 shown in Figure 4. The economizer 122 is omitted in the convection section 12, and therefore the boiler feedwater BF is not heated by such an economizer in the convection section 12. Now the quench cooling section consists only of two exchangers 21 and 23, and the quench exchanger 22 is also omitted. The boiler feedwater BF is preheated in the secondary quench exchanger 23, and the steam drum 31 is connected to the primary quench exchanger 21.

[0161] From a position between the first steam superheater 124 and the first high-temperature coil 123, and from a position downstream of the feed preheater 121, at least a portion of the flue gas FG, shown as FG1 and FG2 in Figure 5, is passed through multiple stages of the combustion air preheating unit 40. Next, the flue gas return flow FG1R from the high-temperature stage of the combustion air preheating unit 40 is sent to the first high-temperature coil 123. After being used for heating purposes in the low-temperature stage of the combustion air preheating unit 40, the flue gas leaves the combustion air preheating unit 40 at a temperature of approximately 70°C in this example. Preferably, combustion air CA, rather than external steam EX, is supplied to the combustion air preheating unit 40, and therefore, preferably, no condensate flow CO is generated. The preheated combustion air CA is supplied to the radiating area 11 at a temperature of approximately 280°C in this illustrated example.

[0162] It should be noted that other configurations of the combustion air preheating unit 40 with multiple stages, and combinations with multiple heat exchanger bundles in the convection zone 12, can be anticipated without limiting the scope of the present invention. For example, the high-temperature stage of the combustion air preheating unit 40 may be inserted at different points between the exchanger bundles in the convection zone 12, either further upstream or further downstream than shown in Figure 5.

[0163] To summarize the above, in the steam cracking furnace unit 1200 shown in Figure 5, the combustion air CA is preheated inside the flue gas FG path ("internal air preheating"). Such an air preheating system may consist of one or more multi-flow heat exchangers with the flue gas FG as the high-temperature medium and the combustion air CA as the low-temperature medium. In the case of multi-stage air preheating, it is also possible to recover heat from the flue gas FG for other process purposes between two combustion air CA preheating stages. Regarding the preheating of external combustion air CA shown in relation to the steam cracking furnace unit 1100 shown in Figure 4, at least a portion of the combustion air CA preheating section may bypass at least one fraction of the entire gas flow so that the air preheating temperature obtained during operation can be modified.

[0164] In the steam cracking furnace unit 1200 shown in Figure 5, boilers can be used equally, and these boilers are implemented with a single primary quench exchanger 21, and (as shown in Figure 4) with a combination of a primary quench exchanger 21 and a secondary quench exchanger 22. Furthermore, this embodiment does not feature a boiler feedwater BF preheating stage in the convection section 12, thereby prioritizing the availability of flue gas FG heat for combustion air preheating, as described above.

[0165] Figure 6 shows a further steam cracking furnace unit 1300 according to one embodiment of the present invention. Generally, the description relating to the steam cracking furnace unit 1100 according to Figure 4 also applies to the steam cracking furnace unit 1300 according to Figure 6, with only the differences being described below. The steam cracking furnace unit 1300 according to Figure 6 is considered more typical for liquid feed cracking furnaces, while the steam cracking furnace units 1100 and 1200 according to Figures 2 and 3, respectively, exhibit typical design features for gas feed cracking furnaces.

[0166] Compared to the steam cracking furnace unit 1100 shown in Figure 4, the tertiary quench exchanger 23 is omitted in the steam cracking furnace unit 1300 shown in Figure 6. The boiler feedwater BF supplied to the steam drum 31 is preheated in the economizer 122 and then in the secondary quench exchanger 22. The steam drum 31 is connected to the primary quench exchanger 21.

[0167] In the case of a liquid feed furnace, a higher preheating load is required (further latent heat for feed vaporization), so the steam cracking furnace unit 1300 further includes an additional process steam superheater bundle 127 in which the process steam is superheated relative to the flue gas before being mixed with the hydrocarbon feed flow.

[0168] Figure 7 shows a further steam cracking furnace unit 1400 according to one embodiment of the present invention. Generally, the explanation relating to the steam cracking furnace unit 1200 according to Figure 5 and the steam cracking furnace unit 1300 according to Figure 6, based on the explanation for the steam cracking furnace unit 1100 according to Figure 4, also applies to the steam cracking furnace unit 1400 according to Figure 7, with only the differences being explained below. The steam cracking furnace unit 1400 according to Figure 7 combines, in particular, the features of the steam cracking furnace unit 1200 according to Figure 5 and the steam cracking furnace unit 1300 according to Figure 6.

[0169] Similarly, as in the case of the steam cracking furnace unit 1200 shown in Figure 5, the combustion air preheating unit 40 is integrated into the flue gas passage or duct in the steam cracking furnace unit 1400 shown in Figure 7, and saturated steam SS is not supplied as in the case of the steam cracking furnace unit 1100 shown in Figure 4. The economizer 122 is omitted in the convection section 12, and therefore the boiler feedwater BF is not heated in the convection section 12.

[0170] As in the case of the steam cracking furnace unit 1300 shown in Figure 6, the tertiary quench exchanger 23 is omitted in the steam cracking furnace unit 1100 shown in Figure 7, in particular when compared to the steam cracking furnace unit 1100 shown in Figure 4. Therefore, the boiler feedwater BF supplied to the steam drum 31 is not preheated in the economizer 122, but is simply preheated in the secondary quench exchanger 22. The steam drum 31 is connected to the primary quench exchanger 21.

[0171] In particular, compared to the steam cracking furnace unit 1200 shown in Figure 5, the flue gas FG is passed through the combustion air preheating unit 40 only from a position downstream of the feed preheater 121. After being used for heating purposes in the combustion air preheating unit 40, the flue gas FG leaves the combustion air preheating unit 40 at a temperature of approximately 90°C in this example.

[0172] The steam cracking furnace units 1300 and 1400 shown in Figures 6 and 7 can operate in particular with liquid feedstock. In such circumstances, and also in the steam cracking furnace units 1300 and 1400 shown in Figures 6 and 7, the tertiary quench exchanger 23 is typically omitted and considered to result in a higher decomposition gas temperature at the furnace outlet. This is advantageous in avoiding condensation of heavy condensate when further cooling the decomposition gas. Therefore, in a liquid feed cracker, decomposition gas cooling downstream of the primary quench exchanger is conventionally performed by direct contact cooling by injection of pyrolysis oil / gasoline and / or quench water. According to the illustrated embodiment of the present invention, the primary quench exchanger 21 and the secondary quench exchanger 22 are integrated as shown.

[0173] Since a higher preheating load is required in liquid feed furnaces (additional latent heat for feed vaporization), as in the steam cracking furnace unit 1300, the steam cracking furnace unit 1400 further includes an additional process steam superheater bundle 127, in which the process steam is superheated relative to the flue gas before being mixed with the hydrocarbon feed flow.

[0174] Figure 8 shows a further steam cracking furnace unit 1500 according to one embodiment of the present invention. Generally, the steam cracking furnace unit 1500 of Figure 8 shows some similarities to the steam cracking furnace unit 1400 of Figure 7, and therefore, the steam cracking furnace unit 1500 of Figure 8 will be described again by referring to the steam cracking furnace unit 1100 of Figure 4, the steam cracking furnace unit 1200 of Figure 5, and the steam cracking furnace unit 1300 of Figure 6, where applicable.

[0175] In contrast to the steam cracking furnace unit 1400 shown in Figure 7, for example, there is an economizer 122 described in relation to the steam cracking furnace unit 1100 shown in Figure 4, which preheats the boiler feedwater BF, but the first high-temperature coil 123 is omitted and does not preheat the process gas flow PR.

[0176] Like the steam cracking furnace units 1300 and 1400 shown in Figures 6 and 7, the steam cracking furnace unit 1500 shown in Figure 8 can also operate, in particular, with liquid feed. The preheating load in a liquid feed furnace is considerably larger than in a gas feed furnace due to the further vaporization enthalpy of the feed hydrocarbons HC. Furthermore, as mentioned above, less heat can be recovered in the multi-flow exchanger within the quench section (avoidance of heavy condensate). At the same time, it is important to maximize the preheating of the combustion air CA in order to reduce fuel gas FU consumption and flue gas FG emissions.

[0177] Like the steam cracking furnace units 1300 and 1400, the steam cracking furnace unit 1500 further includes an additional process steam superheater bundle 127, in which the process steam PS is superheated over flue gas before being mixed with hydrocarbon feed flow HC to produce process flow PR.

[0178] Therefore, the secondary quench exchanger 22 is located within the steam cracking furnace unit 1500, as shown in Figure 8, and is provided as a feed-effleent exchanger for preheating the process gas flow PR. The present invention proposes a preferred arrangement of this feed-effleent exchanger, located downstream of the further boiler primary quench exchanger 21 along the trajectory or flow path of the further decomposition gas flow PE, thereby enabling a considerably high heat transfer coefficient, and thus fast and effective quenching of the decomposition gas.

[0179] A feature particularly relevant to the present invention and its embodiments is the limitation of the steam superheating level inside the steam cracking furnace units 1100 to 1500. As shown below in Figure 17, such moderate superheating is quite suitable when the steam flow discharged from the furnace system is intended solely to supply process heat to the consumer.

[0180] Figure 9 shows a steam cracking furnace unit 2100 according to one embodiment of the present invention. The steam cracking furnace unit 2100, including other steam cracking furnace units shown below, can be part of a system 100 according to one embodiment of the present invention, which may include several further components previously shown and already described, and the possible boundaries of the system are only schematically shown in Figures 4 and 9.

[0181] The steam cracking furnace unit 2100 includes the use of the electric steam cracking furnace 210, including the "electric coil box" described above, as previously outlined. There is no convection zone.

[0182] In particular, process steam PS at a temperature of approximately 185°C is mixed in a mixing nozzle M with steam of feed hydrocarbons HC that are preheated in heat exchanger X1. The process flow PR thus produced is further heated in heat exchanger X2, particularly to a temperature of approximately 300°C. Heat exchangers X1 and X2 can also be coupled together, especially when process steam PS is added upstream of heat exchanger X1.

[0183] The four quench exchangers 21, 22, 22a, and 23 are arranged in a sequence within the process gas path downstream of the electric steam cracking furnace 210, forming the quench cooling row 20 of the steam cracking furnace unit 2100. As previously stated, for reference purposes only, this sequence of first quench exchangers 21 and second quench exchangers 22 may be referred to as the primary and secondary quench exchangers described above. The last quench exchanger in the sequence 23 may also be called a tertiary quench exchanger, and the second to last quench exchanger in the sequence 22a may also be called an intermediate quench exchanger. Alternatively, both quench exchangers 21 and 22a may be referred to as secondary quench exchangers.

[0184] The process flow PR is further heated in electric heater E1 to a temperature of approximately 660°C and preheated in quench exchanger 22 before being supplied as feed flow to electric steam cracking furnace 210. The process flow as a decomposition gas, indicated here as PE for clarity, is recovered from the cracking furnace 210 and passed through quench exchangers 21, 22, 22a and 23. The process flow PE efluent from the electric steam cracking furnace 210 is recovered from the electric steam cracking furnace 210 at a temperature of approximately 840°C, recovered from quench exchanger 21 at a temperature of approximately 550°C, recovered from quench exchanger 22 at a temperature of approximately 340°C, and recovered from quench exchanger 23 at a temperature of approximately 200°C.

[0185] Subsequently, the process flow PE can undergo any kind of processing, including compression in a compressor 60, in particular a process gas compressor driven by an electric motor M, according to one embodiment of the present invention, as shown only in Figure 9. Such a compressor 60 or compressor configuration may also be used to compress process flows from at least one further cracking furnace unit 1000 or 2000. See the above description for further details. In particular, a separation row is provided in which all or essentially all compressors are electrically driven.

[0186] A steam generator 30 is provided, which includes a steam drum 31 and other components used to generate steam. Generally, throughout this specification, when referring to a component or group of components belonging to one apparatus described primarily in conjunction with a particular function, this does not exclude that this component is not part of a further group of different apparatuses or components having additional or different functions, as is typical in facilities with interconnected parts. For example, quench exchangers 21, 22, and 23 are described herein as part of the quench cooling train 20, but they may also be integrated into the steam generator 30.

[0187] The boiler feedwater BF, also indicated by the dotted arrow, is heated to a temperature level of approximately 180°C in the heat exchanger X3 and to a temperature of approximately 290°C in the quench exchanger 23 before being supplied to the steam drum 31. From the steam drum 31, the boiler feedwater BF flow is also passed through the quench exchanger 21 and vaporized. Saturated steam SS, also indicated by the dashed arrow, is generated in the steam drum and can be supplied at a temperature of approximately 325°C and an absolute pressure of approximately 122 bar. This saturated steam SS can be used in part to operate the heat exchangers X2, X3 and X1, where condensate CO is generated, and the condensate CO is supercooled in the heat exchangers X3 and X1.

[0188] The remainder of the saturated steam SS is superheated in the quench exchanger 22a to produce (moderately) superheated high-pressure steam SU, also indicated by the dashed-dotted arrow. The parameters of the superheated high-pressure steam SU have been described in detail previously. In the illustrated embodiment, these parameters may have a temperature of about 375°C and an absolute pressure of about 121 bar. In the steam utilization apparatus shown in 50 for reference purposes only, the superheated high-pressure steam SU is used for heating purposes, but preferably not substantially for driving rotating machinery. In this specification, the superheated high-pressure steam SU is adiabatically and equidistantly heated using expansion units 51, 52, and 53. Enthalpi The steam is expanded to produce high-pressure steam HP, medium-pressure steam MP, and low-pressure steam LP, which are supplied to heat consumers 54, 55, and 56. All steam (high-pressure or ultra-high-pressure steam) discharged from the furnace can be collected in corresponding steam headers, i.e., large-capacity tubular systems that distribute the steam to various consumers on the facility. Supply connections to lower pressure steam headers are made from this highest pressure steam header. In conventional facilities, such steam headers operate at an approximately constant pressure (for turbine operation) slightly below the steam discharge pressure at the furnace outlet. According to embodiments of the present invention, the pressure level of this highest pressure steam header can be varied more broadly to achieve a favorable buffering effect.

[0189] To summarize the description of Figure 9 and the illustrated steam cracking furnace unit 2100, the process gas PE is rapidly and effectively cooled in the first stage (quench exchanger 21) relative to the vaporization boiler feedwater BF, similar to modern combustion furnaces. In the second stage (quench exchanger 22), the process gas PE is cooled in the feed-effluent exchanger relative to the process gas PR, which is preheated before being supplied to the electric cracking furnace 11. In the embodiment shown in Figure 9, the quench exchanger 22a is provided to cool the process gas PE while moderately superheating a portion of the saturated steam SS generated in the quench exchanger 21.

[0190] Figure 10 shows a further steam cracking furnace unit 2200 according to one embodiment of the present invention. Generally, the description relating to the steam cracking furnace unit 2100 in Figure 9 also applies to the steam cracking furnace unit 2200 in Figure 10, with only the differences being described below.

[0191] In the steam cracking furnace unit 2200 shown in Figure 10, the quench exchanger 22a is omitted, and an electric steam superheater E2 is provided instead. The process gas PE is recovered here from the quench exchanger 22, particularly at a temperature of about 340°C.

[0192] Figure 11 shows a further steam cracking furnace unit 2300 according to one embodiment of the present invention. Generally, the description relating to the steam cracking furnace unit 2200 in Figure 10, which is based on the description of the steam cracking furnace unit 2100, also applies to the steam cracking furnace unit 2300 in Figure 11, with only the differences being described below.

[0193] In the steam cracking furnace unit 2300 shown in Figure 11, the quench exchanger 22a is absent, and an electric steam superheater E2 is provided instead. In the steam cracking furnace unit 2300 shown in Figure 11, the electric heater E1 is also omitted. Furthermore, the process gas flow PR heated in the heat exchanger X2 is further heated in the quench exchanger 21, and the steam drum 31 is connected to the quench exchanger 22.

[0194] The process gas PE efluent from the electric steam cracking furnace 210 is recovered from the quench exchanger 22, particularly at a temperature of approximately 340°C. The process flow PE is recovered from the quench exchanger 21, particularly at a temperature of approximately 525°C.

[0195] Therefore, in the embodiment shown in Figure 11, the first two quench stages are reversed, meaning that the efluent of the process gas PE is first cooled against the preheated feed process gas PR, and then against the vaporization boiler feedwater BF. In such an embodiment, an electric feed preheater is not necessary because a sufficiently high preheating temperature can be reached in the quench exchanger 21. The discharged high-pressure steam is again moderately superheated, and both variations from Figures 9 and 10 can be used for steam superheating.

[0196] All three embodiments shown in Figures 9 to 11 are specifically designed for an electric cracking furnace 210 operating with a light (gasic) feedstock, most preferably consisting mostly of ethane. Accordingly, all these embodiments feature a quench exchanger 23, which, in accordance with modern industrial practice, further cools the decomposition gas to a temperature level of up to 200°C while specifically preheating the boiler feedwater supplied to the steam drum 31.

[0197] Furthermore, after mixing to generate a process flow, the hydrocarbon feed HC and process steam PS are initially preheated (at a temperature level below 300°C) by using saturated steam in the heat exchanger X2. The resulting high-pressure condensate CO can be further used in the other preheating stages described above.

[0198] Figure 12 shows a further steam cracking furnace unit 2400 according to one embodiment of the present invention. Generally, the explanation relating to the steam cracking furnace unit 2200 according to Figure 10, based on the explanation of the steam cracking furnace unit 2100 according to Figure 9, also applies to the steam cracking furnace unit 2400 according to Figure 12, with only the differences being explained below.

[0199] In the steam cracking furnace unit 2400 shown in Figure 12, there is no quench exchanger 22a, and instead an electric steam superheater E2 is provided. Here, a portion of the superheated steam SU, rather than a portion of the saturated steam SS, is supplied to the heat exchanger X3. Therefore, the process flow PR can be heated to a temperature of approximately 330°C, particularly within the heat exchanger X2, so less heat is recovered in the quench exchanger 22, and the efluent of the process flow PE cooled within the quench exchanger 22 is recovered from the quench exchanger 22 at a temperature of approximately 370°C.

[0200] The embodiment in Figure 12, as an alternative to the previously shown embodiments, specifically demonstrates that moderately superheated steam SU can be used to ensure initial preheating of the hydrocarbon feed HC and process steam PS after generating the process flow PR.

[0201] Figure 13 shows a further steam cracking furnace unit 2500 according to one embodiment of the present invention. Generally, the explanation relating to the main components of the steam cracking furnace unit 2100 shown in Figure 9 also applies to the steam cracking furnace unit 2500 shown in Figure 13, although there are some differences, which are described below.

[0202] In the steam cracking furnace unit 2500 shown in Figure 13, process steam PS, particularly at a temperature of about 185°C, is mixed with feed hydrocarbon HC in the mixing nozzle M as described above to produce process flow PR, particularly at a temperature of about 120°C. Process flow PR is further heated in the quench exchanger 23, particularly to a temperature of about 280°C, and in the quench exchanger 21, particularly to a temperature of about 660°C, before being supplied to the electric steam cracking furnace 210, as previously described. The efluent of process gas PE is recovered from the electric steam cracking furnace 210, particularly at a temperature of about 840°C, recovered from the quench exchanger 21, particularly at a temperature of about 510°C, recovered from the quench exchanger 22 (there is no further quench exchanger 22a), particularly at a temperature of about 340°C, and recovered from the quench exchanger 23, particularly at a temperature of 200°C.

[0203] The boiler feedwater BF is supplied to a steam drum 31 connected to a quench exchanger 22. Saturated steam SS can be produced at a pressure level of approximately 122 bar absolute pressure and a temperature of approximately 325°C. The saturated steam SS is superheated in an electric heater E2 to produce superheated steam SU having the above parameters.

[0204] The embodiment shown in Figure 13 includes further options to ensure initial preheating of the hydrocarbon feed HC and process vapor PS after generating the process flow PR, and the quench exchanger 23 is designed as a feed-effluent exchanger. This possibility can also be combined with embodiments shown, for example, in Figures 9, 10, and 12.

[0205] Figure 14 shows a further steam cracking furnace unit 2600 according to one embodiment of the present invention. Generally, the explanation relating to the steam cracking furnace unit 2200 according to Figure 10, based on the explanation of the steam cracking furnace unit 2100 according to Figure 9, also applies to the steam cracking furnace unit 2600 according to Figure 14, with only the differences being explained below.

[0206] In the steam cracking furnace unit 2600 shown in Figure 14, there is no quench exchanger 23, and an oil quench 25 is used instead. Thus, the boiler feedwater BF is heated to a temperature of approximately 260°C in heat exchanger X3 alone before being passed through the steam drum 31. A further heat exchanger X4 is provided to further heat the feed hydrocarbons before being mixed with process steam PS in the mixing nozzle M. The process steam PS is similarly preheated in a further heat exchanger X5. Heat exchangers X2, X4 and X5 operate with saturated steam SS, and the condensate flow is recovered before being used in heat exchangers X1 and X3, as previously described.

[0207] In the steam cracking furnace unit 2600 shown in Figure 14, process steam PS is initially supplied at a temperature of approximately 180°C. The temperature level of the process flow PR downstream of the heat exchanger X2 is approximately 300°C. Heating in the electric heater E1 is carried out to a temperature of approximately 630°C. The efferent process gas PE is recovered from the electric cracking furnace 210 at a temperature of approximately 870°C, recovered from the quench exchanger 21 at a temperature of approximately 600°C, recovered from the first quench exchanger 22 at a temperature of approximately 390°C, recovered from the quench exchanger 22a at a temperature of approximately 380°C, and recovered from the oil quench 25 at a further appropriate temperature level. The saturated steam SS generated in the steam drum 21 is supplied at a pressure level of approximately 122 bar absolute pressure and a temperature of approximately 325°C. The superheated high-pressure steam SU downstream of the quench exchanger 22a is supplied at a pressure level of approximately 121 bar absolute pressure, and at a temperature of approximately 380°C.

[0208] Figure 15 shows a further steam cracking furnace unit 2700 according to one embodiment of the present invention. Generally, the explanation relating to the steam cracking furnace unit 2600 according to Figure 14, based on the explanation of the steam cracking furnace unit 2100 according to Figure 9, also applies to the steam cracking furnace unit 2700 according to Figure 15, with only the differences being explained below.

[0209] In the steam cracking furnace unit 2700 shown in Figure 15, process steam PS is continuously mixed with feed hydrocarbon HC in the first mixing nozzle M1 and the second mixing nozzle M2, and the process steam PS mixed in the second mixing nozzle M2 is further heated in a further electric heater E3.

[0210] As alternative process variations, Figures 14 and 15 show exemplary embodiments of the present invention applied to an electric furnace 210 operating for liquid feed and heavy liquid feed, respectively. In such embodiments, as with the combustion liquid feed furnace, there is no quench exchanger 23. The feed preheating section is typically more complex and features, for example, further feed preheating stages (see Figures 14 and 15, including the use of an electric process steam superheater for heavy liquid feed) and / or one or more process steam superheating stages in a multi-flow heat exchanger. Nevertheless, the embodiments shown in Figures 14 and 15 are simple adaptations of the embodiments shown in Figure 9. Thus, the variations presented by the embodiments shown in Figures 10 to 12 can also be applied to the liquid feed furnace shown in Figures 14 and 15, since the liquid feed furnace shown in Figures 14 and 15 was applied to the gas feed furnace in Figure 9.

[0211] Figure 16 shows a further steam cracking furnace unit 2800 according to one embodiment of the present invention. Generally, the explanation relating to the steam cracking furnace unit 2700 in Figure 15, based on the explanation of the steam cracking furnace unit 2100 in Figure 9, also applies to the steam cracking furnace unit 2800 in Figure 16, with only the differences being explained below.

[0212] Similar to the steam cracking furnace unit 2200 shown in Figure 10, the quench exchanger 23 is omitted, and an electric steam superheater E2 is provided instead. As an exemplary variant, Figure 16 shows a process variant of a heavy liquid feed furnace similar to the gas feed variant shown in Figure 11 (the quench exchanger 21 is designed as a feed-effluent exchanger).

[0213] In Figure 17, a Molier (enthalpy / entropy) diagram for water is shown, where entropy s is displayed on the horizontal axis in kJ / (K×kg) units and enthalpy h is displayed on the vertical axis in kJ / kg units. Moderate superheating used in one embodiment of the present invention is indicated by point 71, while high superheating used in the prior art is indicated by point 72. Adiabatic or equivalent Enthalpi Expansion is carried out according to the present invention and embodiments thereof, and is characterized by a change in the state of a valve or reducer when the steam is intended to be used solely for heating purposes, and is indicated by an arrow starting from point 71, while polytrope expansion is carried out according to the prior art and not according to the present invention, and is characterized by a change in the state of a steam turbine when the steam is intended to be used first for mechanical purposes before being used for heating purposes, and is indicated by an arrow starting from point 72.

[0214] According to the present invention, a simple equivalent Enthalpi Due to expansion, the pressure increases. phase Without alteration, the pressure and temperature levels required by the heat consumer can be reduced to the required levels. (Such as a support point with an absolute pressure of 380°C and 120 bar.) Enthalpi An exemplary temperature evolution curve 81 of the phase change is shown in Figure 18, along with the corresponding most preferred curve envelopes 82 and 83 (with dew point margins of +20K and +80K) in the pressure range between absolute pressures of 20 to 160 bar. In Figure 18, absolute pressure in bar units is shown on the horizontal axis, and temperature in °C is shown on the vertical axis.

[0215] Same example, etc. Enthalpi Dew point corresponding to curve 81 room This is shown in Figure 19 for the same pressure range. In Figure 19, the absolute pressure in bar units is shown on the horizontal axis, while the temperature difference values ​​in kcal units are shown on the vertical axis.

[0216] Figure 20 shows a further combustion steam cracking furnace unit usable in the hybrid concept of the present invention shown in Figure 3.

[0217] For the components of the combustion steam cracking furnace unit shown in Figure 20, indicated by 1600, please refer to the description of Figures 4 to 8, and especially Figure 5. An essential aspect of the embodiment shown in Figure 20 is that it includes two-stage combustion air preheating to a temperature of about 610°C, the feed HC is preheated before and after combustion with process steam PS in the heat quench cooling heat exchangers 22 and 23, the boiler feedwater is not preheated, only three heat exchanger bundles 124, 125 and 126 are used in the convection section, and the flue gas discharge temperature is about 110°C.

Claims

1. A steam cracking method using a steam cracking system (100), wherein the steam cracking system (100) includes one first steam cracking furnace unit (1000) or a plurality of first steam cracking furnace units (1000) and one second steam cracking furnace unit (2000) or a plurality of second steam cracking furnace units (2000), each of the one first steam cracking furnace unit (1000) or the plurality of first steam cracking furnace units (1000) comprises one or more combustion steam A method comprising a combustion steam cracking furnace (110), wherein each of the one second steam cracking furnace unit (2000) or the plurality of second steam cracking furnace units (2000) comprises one or more electric steam cracking furnaces (210), and each of the one first steam cracking furnace unit (1000) or the plurality of first steam cracking furnace units (1000) comprises means for preheating at least a portion of the combustion air supplied to the one or more combustion steam cracking furnaces (110) to a temperature level of at least 100°C.

2. In each of the one first steam cracking furnace unit (1000) or a plurality of first steam cracking furnace units (1000), and in each of the one second steam cracking furnace unit (2000) or a plurality of second steam cracking furnace units (2000), the one or a plurality of steam cracking furnaces (110, 210) is connected to at least one quench cooling row (10, 20) which is thermally coupled to at least one steam generator (30), and in the at least one steam generator (30), at least superheated high-pressure steam is supplied to a first pressure level between 30 and 175 bar absolute pressures and The method according to claim 1, wherein no steam is produced at a temperature level higher than the first temperature level, the superheated high-pressure steam at the first pressure level is expanded adiabatically and isenthalpily at least partially to a second pressure level below the first pressure level such that the temperature level of the superheated high-pressure steam drops to a second temperature level, the first temperature level is selected such that, during the adiabatic and isenthalpi expansion, each intermediate temperature level reaching an intermediate pressure level greater than 20 bar is 5 to 120 K higher than the dew point of the steam at each of the intermediate pressure levels during the adiabatic and isenthalpi expansion.

3. The method according to claim 2, wherein the superheated high-pressure steam at the first pressure level and the first temperature level does not contain steam generated from process water and / or contains only steam generated from boiler feedwater, and for this reason the superheated high-pressure steam at the first pressure level and the first temperature level is supplied as high-purity superheated high-pressure steam.

4. The method according to claim 1 or 2, wherein one or more process flows before passing through one or more cracking furnace coil boxes of the cracking furnaces (or more) (110, 210) of the first cracking furnace unit (1000) and / or the second cracking furnace unit (2000), or feed hydrocarbons and / or process vapors or combustion air used to generate the at least one process flow, are at least partially heated using heat recovered from at least one of the process flows downstream of the coil box(s).

5. The method according to claim 4, wherein the heat recovered from the one or more process flows downstream of the coil box(s) is at least partially recovered from at least one process flow downstream of the coil box(s) in one or more direct feed-effluent exchangers.

6. The method according to claim 4, wherein the heat recovered from the one or more process flows downstream of the coil box(s) is at least partially transferred to steam subsequently used to heat the at least one process flow, or to feed hydrocarbons and / or process steam used to generate the at least one or more process flows, or to combustion air.

7. The method according to any one of claims 1 to 6, wherein the means for preheating at least a portion of the combustion air preheats the combustion air to a temperature level up to 1000°C, and the preheating temperature of the combustion air is changed during operation.

8. The method according to any one of claims 1 to 7, wherein the first steam cracking furnace unit (or more) (1000) and the second steam cracking furnace unit (or more) (2000) are operated in a plurality of operating modes using variable fuel gas consumption rates and power consumption rates, respectively, to achieve a variable rate between the total fuel gas consumption rate and the total power consumption rate, which are aggregated across all the first and second steam cracking furnace units, while maintaining a constant total cracking product yield from the furnace units.

9. The method according to any one of claims 1 to 8, wherein the hydrogen-enriched fuel gas is released at least temporarily from the electrolysis unit (4300), the ammonia decomposition unit (4400), and / or the hydrogen storage unit (4600) to supply at least temporarily any additional fuel gas needed to one of the first steam cracking furnace units (1000) or the plurality of first steam cracking furnace units (1000), and / or to other hydrogen consumers.

10. The method according to any one of claims 1 to 9, wherein at least a temporary surplus of hydrogen-enriched fuel gas produced from a hydrogen separation unit (4700), compared to the overall consumption of hydrogen in at least one of the one first steam cracking furnace unit (1000) or the plurality of first steam cracking furnace units (1000) and / or other hydrogen consumers, is supplied at least temporarily to a fuel cell unit (4500) and / or a hydrogen storage unit (4600).

11. The method according to any one of claims 1 to 10, wherein the fuel gas used for combustion of the steam cracking furnace(s)(110) of the first(s) steam cracking furnace unit(s) is heated to a certain temperature level, the temperature level is changed during operation.

12. The method according to any one of claims 1 to 11, wherein the fuel gas used for combustion of the steam cracking furnace (or more) (110) of the first steam cracking furnace unit (or more) (1000) has a hydrogen content between 0 and 100 wt%.

13. A system (100) for carrying out a steam cracking method, the system (100) comprising one first steam cracking furnace unit (1000) or a plurality of first steam cracking furnace units (1000) and one second steam cracking furnace unit (2000) or a plurality of second steam cracking furnace units (2000), each of the one first steam cracking furnace unit (1000) or the plurality of first steam cracking furnace units (1000) comprising one or more combustion steam cracking furnaces (110), and the A system (100) comprising one second steam cracking furnace unit (2000) or each of the plurality of second steam cracking furnace units (2000), each comprising one or more electric steam cracking furnaces (210), and each of the one first steam cracking furnace unit (1000) or each of the plurality of first steam cracking furnace units (1000), comprising means adapted to preheat at least a portion of the combustion air supplied to the one or more combustion steam cracking furnaces (110) to a temperature level of at least 100°C.

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