Method and system for steam cracking

Abstract

A steam cracking method is proposed using a steam cracker (2100-2800), the steam cracker (2100-2800) comprising an electric cracking furnace (10) without a convection section (12) and further comprising a quench cooling train (20), and a process gas stream is passed through at least the electric cracking furnace (10) and the quench cooling train (20). The quench cooling train (20) is operative with at least two separate cooling stages arranged in any order, in which in a first of the cooling stages at least a portion of the process gas stream withdrawn from the electric cracking furnace (10) is cooled against a gasification boiler feed water at an absolute pressure level between 30 and 175 bar, and in a second of the cooling stages at least a portion of the process gas stream withdrawn from the electric cracking furnace (10) is cooled against a superheated mixture of feed hydrocarbons and process steam used to generate the process gas stream, whereby the process gas stream is heated to a temperature level between 350 and 750° C. Corresponding apparatuses (2100-2800) are 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 claim.

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, published online on April 15, 2009, DOI: 10.1002 / 14356007.a10_045.pub2.

[0003] A method and an apparatus for steam cracking of hydrocarbons are disclosed in Patent Document 1. This method involves heating a mixture of hydrocarbons and steam to a desired temperature sufficiently high for cracking the hydrocarbons and converting the mixture into olefins. The method is characterized in that the energy source required for heating the mixture is essentially supplied by co-generation using combustion of fuel, simultaneously generating both thermal energy and mechanical work that is converted into electricity by an alternator, and the mixture is first preheated using the thermal energy supplied by co-generation and then heated to the desired cracking temperature by electric heating using the electricity supplied by co-generation.

[0004] In Patent Document 2, there is a cracking furnace system for converting a hydrocarbon raw material into cracked gas, the cracking furnace system comprising a convection section, a radiation section, and a cooling section. The convection section includes a plurality of convection banks configured to receive and preheat the hydrocarbon raw material, the radiation section includes a firebox having at least one radiant coil configured to heat the raw material to a temperature enabling a pyrolysis reaction, and the cooling section includes at least one transfer line exchanger.

[0005] Currently, the thermal energy required to initiate and maintain the endothermic decomposition reaction in steam cracking is provided by burning fuel gas in a refractory furnace. The process gas, initially containing the vapors and hydrocarbons to be decomposed, is passed through a so-called cracking coil located inside the refractory enclosure, also called a radiating area or section. In this passage, the process gas is continuously heated, allowing the desired decomposition reaction to occur inside the cracking coil, and thus the process gas is continuously enriched with 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 is typically in the range of 800 to 900°C.

[0006] 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.

[0007] 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.

[0008] 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.

[0009] 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 ) 1 50 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.

[0010] A crucial part of the treatment of process gases 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 gases for separation. This compression, also called process gas or decomposition 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.

[0011] 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.

[0012] 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.

[0013] 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.

[0014] In the illustrated example, several heat exchangers 921 to 925 are arranged within the convection zone 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 a tubular bundle passing through the convection zone 92 and are located within the flue gas flow from the radiant zone 91.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] As described in Patent Document 3 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 4, 5 and 6. Electric furnace technology has been disclosed in other situations or in a broader context, for example, in Patent Documents 7, 8, 9, 10 and 11, or in older documents such as Patent Documents 12, 13, 14 and 15.

[0025] Patent Document 1 discloses a method and apparatus for steam cracking hydrocarbons, the method comprising heating a mixture of hydrocarbons and steam to a desired temperature sufficiently high for hydrocarbon cracking, thereby converting the mixture into olefins. The method is characterized in that the energy source required for heating the mixture is essentially supplied by cogeneration using the combustion of fuel, simultaneously producing both thermal energy and mechanical work that is converted into electricity by an alternator, and the mixture is first preheated using the thermal energy supplied by cogeneration, and then heated to a desired cracking temperature by electric heating using electricity supplied by cogeneration.

[0026] According to Patent Document 2, a cracking furnace system for converting a hydrocarbon raw material into a cracked gas includes a convection section, a radiation section, and a cooling section. The convection section includes a plurality of convection banks configured to receive and preheat the hydrocarbon raw material. The radiation section includes a firebox having at least one radiant coil configured to heat the raw material to a temperature enabling a pyrolysis reaction. The cooling section includes at least one transfer line exchanger.

[0027] Completely or partially modifying the heating concept of a steam cracking facility, i.e., completely or partially using heat generated by electrical energy instead of heat generated by fuel combustion, is a fairly substantial intervention. As an alternative, especially when retrofitting an existing facility, less invasive redesign options are often desirable. These may include, for example, replacing at least partially with an electric drive a process gas compressor or a steam turbine used to drive a different compressor. As described above, such a steam turbine can operate partially with steam generated by waste heat recovered within the convection section of the cracking furnace, but typically a combustion steam boiler must be further provided to supply a sufficient amount of steam. Therefore, replacing at least partially with an electric drive the steam turbine used to drive the compressor described above may be suitable for reducing or avoiding the load on the combustion boiler and thereby reducing local carbon dioxide emissions.

Prior Art Documents

Patent Documents

[0028]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

[0029] [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]

[0030] 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.

[0031] 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.

[0032] In connection therewith, the present invention relates particularly to a situation in which a combustion steam cracking furnace is replaced by an electrically heated steam cracking furnace, thereby substantially reducing or eliminating the amount of steam produced that can be used by steam consumers such as steam turbines or other rotating equipment. The present invention relates in detail to a situation in which the "total electrification" of a steam cracking facility is achieved. In such a situation, as described above, a suitable operating mode must be found, because the conventional good equilibrium of steam production and consumption is almost completely altered. [Means for solving the problem]

[0033] 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.

[0034] Before further describing the features and advantages of the present invention, some terms used herein will be further explained.

[0035] 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.

[0036] "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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] In this specification, the term "dominantly" may mean a proportion or content of at least 50%, 60%, 70%, 80%, 90%, or 95%.

[0043] 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.

[0044] 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.

[0045] Advantages of the invention To the best of our knowledge, existing literature on electric heating cracking furnaces is limited to the design and operation of the electric coil heating section itself. There is little information available regarding an integrated concept for a complete furnace configuration (including preheating and quenching sections), nor is there any information available regarding an integrated concept for a broader cracker facility configuration. This is true with the exception of the recent publications mentioned above, namely Patent Documents 4, 5, and 6.

[0046] As mentioned above, the efficient and effective integration of the electric furnace into the steam cracker (hereinafter referred to as the "steam cracking device") is of paramount importance for the overall facility design, particularly in terms of energy management. A major difficulty arises because, as stated above, the electric heating furnace does not feature a convection zone. This is important because, as already mentioned, in a combustion cracking furnace, 40 to 60 percent of the total heat input can be recovered within the convection zone and used for various purposes.

[0047] The concepts and solutions provided by the present invention are intended and suitable for performing the following tasks and requirements necessary for steam cracking apparatus, including electric furnace systems.

[0048] - In a cracking coil, a process gas flow pre-mixed with feed hydrocarbons and vapor is electrically heated from an inlet temperature of 550 to 750°C to an outlet temperature of 800 to 900°C, thereby achieving a cracking yield similar to or better than that obtained in a combustion cracking furnace.

[0049] The feed hydrocarbons are preheated from a typical supply temperature between -20 and 150°C to the aforementioned coil inlet temperature between 550 and 750°C, and, in the case of liquid feeds, the feed hydrocarbons are vaporized. The preheating and vaporization of the feed hydrocarbons are carried out with or without prior addition of process vapor, which is typically supplied to the steam cracking unit at a temperature between 130 and 200°C.

[0050] -In one or more multi-flow heat exchangers, the process gas downstream of the cracking coil is effectively and fairly rapidly cooled to a temperature between 300 and 450°C (for liquid feedstocks) or between 150 and 300°C (for gaseous feedstocks), enabling heat recovery from the process gas.

[0051] - To ensure safe, reliable, and efficient operation of the facility, the energy flow between the reactor system and the rest of the steam cracker facility is balanced.

[0052] The present invention proposes novel process solutions in terms of furnace design, equipment, and installation of such furnaces. In summary, the present invention provides a solution to the problem of "how to balance and distribute heat in low-to-zero emission steam crackers characterized by a partial, majority, or exclusive electric furnace."

[0053] Existing conventional technologies do not provide examples of how to solve these tasks simultaneously, because the integrated concept of all combustion furnaces relies strictly on the existence of a convective region where heat is recovered from the hot flue gas flow.

[0054] 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. Unless The 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.

[0055] The present invention provides a steam cracking method using a steam cracking apparatus, the steam cracking apparatus comprising an electric cracking furnace without a convection section, and further comprising a quench cooling row, the process gas flow passing through at least the electric cracking furnace and the quench cooling row. In the following description, apparatus, devices, flow, etc. will be referred to in the singular, but it should be noted that the present invention may also include embodiments in which each of these items can be provided in the plural. In this regard, the flow may be a combination of various components or dispersed in various components, as necessary.

[0056] In this specification, when referring to an electric cracking furnace "without a convection zone," this refers to an electric cracking furnace that lacks 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, an electric cracking furnace without a convection zone 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 the purpose of 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.

[0057] Therefore, generally speaking, in an electric cracking furnace, during hydrocarbon cracking operations, preferably less than 1000 kW 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 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 in the electric cracking furnace may be 5% or less or 3% or less of the heat transferred to the process gas.

[0058] According to the present invention, the quench cooling train operates to comprise at least two separate cooling stages, in the first stage of the cooling stages, at least a portion of the process gas flow recovered from the electric cracking furnace is vaporized 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. do Cooled against boiler feedwater, and in the second stage of the 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, The superheated mixture It is heated to a temperature between 350 and 750°C, more specifically between 400 and 720°C, and more specifically between 450 and 700°C.

[0059] According to a particularly preferred embodiment of the present invention, the steam generator operates in thermal coupling with a steam cracking device and may also form part of the steam cracking device, and the steam generator produces at least superheated high-pressure steam at a first pressure level and a first temperature level with an absolute pressure of 30 to 175 bar, and substantially no steam is produced at temperature levels higher than the first temperature level. The term “substantially no steam is produced” in this context refers, in particular, to less than 10% of the total amount of steam produced in the steam generator.

[0060] Furthermore, according to this embodiment, superheated high-pressure steam at a first pressure level and a first temperature level is adiabatically and equidistantly heated at least partially down to a second pressure level below the first pressure level. Enthalpi It expands in a specific way, and the second pressure level is such that the temperature level of the superheated high-pressure steam is adiabatic and equal. Enthalpi The temperature drops to the second temperature level solely by expansion, and in particular, not necessarily, exceeds an absolute pressure of 20 bar. 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, especially 10 to 100 K Furthermore, especially from 20 to 80 K The temperature is selected to be such that, in other words, the expanding vapor 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.

[0061] According to this embodiment, limiting the steam superheating level inside the furnace system, i.e., performing moderate superheating, is quite suitable when the steam flow discharged from the furnace system is intended solely for supplying process heat to the consumer. In this context, the term "discharge" refers to recovery from the steam generator and does not necessarily refer to recovery from the entire system. This steam is discharged when the steam superheating level is, for example, during steam transport. wear They can also be called "dry" vapors because they are inherently chosen to prevent condensation, which can result from simple adiabatic and equivalent processes. Enthalpi Due to expansion, the pressure of steam superheating is observed when the above temperature level is reached. phase Without alteration, the pressure and temperature levels required by the heat sink can be reduced. In some cases, the minimum pressure, i.e., the second pressure level, is reduced to apply adiabatic and equidistant heating. 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.

[0062] According to embodiments of the present invention, by avoiding strong steam superheating, the availability of quench heat for preheating the feed to higher temperatures (typically above 300°C) can be maximized. In embodiments comprising an electric steam superheater, as will be further described below, the transfer of electrical energy to the electric cracking furnace can be minimized.

[0063] 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.

[0064] 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.

[0065] By limiting the use of steam solely to 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 in a steam turbine, which is not as tolerant of fluctuations in steam conditions as a steam-based heat exchanger. Modifications to the output of electrical energy can be achieved in various ways in various embodiments, for example, by modifying the setpoint of the controlled outlet temperature of a particular heat exchanger. In the embodiment shown in Figure 2 and further described below, for example, such a modification is achieved by reducing the outlet temperature of the steam supply heat exchanger X2, 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.

[0066] 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.

[0067] 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.

[0068] In other words, according to the present invention, a moderately superheated high-purity vapor stream is generated as described above at the corresponding pressure level, i.e., the first pressure level, and any adiabatic and equivalent Enthalpi It is discharged for expansion, reduced to the minimum pressure, i.e., the second pressure level, and the dew point of the resulting expanded vapor flow. room This falls within the scope already described above.

[0069] 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 perform at least a portion of the first stage of the cooling stage, the secondary quench exchanger is used to perform at least a portion of the second stage of the cooling stage, and vice versa. Corresponding embodiments of the present invention will be further described in detail with reference to the accompanying drawings.

[0070] 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 a process gas flow recovered from an electric cracking furnace (maybe one or more) is transferred to a boiler feedwater flow and / or a steam flow used to generate superheated high-pressure steam. Furthermore, at least a portion of the feed hydrocarbons used to generate a superheated mixture of feed hydrocarbons and process steam, i.e., a 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 electric cracking furnace. In this case, the multi-flow heat exchanger is called a feed-effluent exchanger.

[0071] The present invention may utilize a quench cooling train comprising a device having three or four quench exchangers arranged in a series within the process gas flow. At least one of the quench cooling trains may be configured as the multi-flow heat exchanger described just hereafter. Of this series, the first and second quench exchangers may be the primary and secondary quench exchangers described previously. Heat may be transferred in the third quench exchanger of such a series of three or four quench exchangers, and in the fourth quench exchanger, if present, to the steam flow used to generate the boiler feedwater flow and / or superheated high-pressure steam. Alternatively, the last quench exchanger in a series of three or four quench exchangers may be used to preheat at least a portion of the feed hydrocarbons used to generate a superheated mixture of feed hydrocarbons and process steam, in particular, to generate a mixture already containing process steam when an electric steam superheater is provided within one embodiment of the present invention. The last quench switch in a series of three or four quench switches will hereafter be referred to as the “tertiary” quench switch, and the second to last quench switch in a series of three or four quench switches will hereafter be referred to as the “intermediate” quench switch. Note that this particular designation is implemented herein solely for ease of reference.

[0072] To partially repeat the above, the superheated high-pressure steam at the first pressure level and first temperature level preferably 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 first temperature level is provided as high-purity superheated high-pressure steam. Furthermore, as already stated above, preferably the steam generated by one or more steam generators is not used in a steam turbine drive unit that delivers a shaft force greater than 1 MW.

[0073] Furthermore, as described above, according to a particularly preferred embodiment of the present invention, the steam cracking apparatus operates in different operating modes using the flexibility of steam generation and the different amounts of electrical energy made possible as a result of using the present invention. Thus, the present invention can also be used for stabilizing power grids.

[0074] 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.

[0075] 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 in a steam cracker furnace, in the context of advanced electrified steam cracker design.

[0076] A solution for limiting the superheating of superheated high-pressure steam, provided by one embodiment of the present invention, particularly breaks through the current state of technology in steam cracker designs based on combustion furnaces and large turbine-driven rotating machinery. This technological choice represents a considerably efficient solution in the context of highly electrified steam cracker design.

[0077] 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.

[0078] In the separation row of an electrified cracker, 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 row. Therefore, 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 in the feed-effleent exchanger or indirectly through the use of superheated, high-pressure steam generation and steam in the feed preheating stage.

[0079] By maximizing the use of quench heat for feed preheating, the total electrical energy input to the 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 within the furnace section.

[0080] 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 minimal electrical energy transfer.

[0081] 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.

[0082] As mentioned above, preheating at lower temperatures reduces the amount of tubing required and allows for maximum heat recovery through the supercooling of the steam condensate.

[0083] 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.

[0084] 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.

[0085] -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.

[0086] -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).

[0087] - A steam cracking apparatus incorporating the features of the present invention may operate according to any possible electric heating principle, such as direct resistance coil heating, indirect radiant coil heating by an electric heating element, and coil heating using inductive power transmission. The steam cracking apparatus may include other units that generate steam from electrical energy (e.g., electric heat pump systems and electric boilers).

[0088] - 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. The choice of an absolute pressure of 20 bar for the second pressure level is selected to facilitate the definition of the curve envelope of the initial steam superheating. Expanding to a pressure below an absolute pressure of 20 bar may result in a higher dew point, although this does not limit the scope of the present invention. room This can occur.

[0089] - In addition to the inherent energy storage potential through steam superheating / pressure modification, the present invention can be further combined with dedicated energy storage systems, such as latent heat storage systems or similar.

[0090] The present invention and embodiments thereof will be further described with reference to the accompanying drawings. [Brief explanation of the drawing]

[0091] [Figure 1] This is a diagram of one embodiment that does not form part of the present invention. [Figure 2] This is a diagram of an embodiment of the present invention. [Figure 3] This is a diagram of an embodiment of the present invention. [Figure 4] This is a diagram of an embodiment of the present invention. [Figure 5] This is a diagram of an embodiment of the present invention. [Figure 6] This is a diagram of an embodiment of the present invention. [Figure 7] This is a diagram of an embodiment of the present invention. [Figure 8] This is a diagram of an embodiment of the present invention. [Figure 9] This is a diagram of an embodiment of the present invention. [Figure 10] This graph illustrates the advantages of the embodiments of the present invention. [Figure 11] This graph illustrates the advantages of the embodiments of the present invention. [Figure 12] This graph illustrates the advantages of the embodiments of the present invention. [Modes for carrying out the invention]

[0092] Figure 1 is as explained earlier.

[0093] Figure 2 shows a steam cracking apparatus 2100 according to one embodiment of the present invention, which is used to carry out a steam cracking method according to one embodiment of the present invention and is optionally part of a system according to the present invention. As in the case of subsequent drawings showing steam cracking apparatuses, method steps of a method can also be implemented by corresponding process units or devices used, and therefore descriptions relating to method steps may also relate 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 apparatuses 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 may be provided in multiple forms. The steam cracking apparatus 2100, such as other steam cracking apparatuses shown below, may be part of a system 200 according to one embodiment of the present invention, which may include multiple further components, and the possible boundaries of the system are shown only schematically in Figure 2.

[0094] In Figures 2 to 9, thick solid arrows indicate hydrocarbon feed flows, process vapor flows, process gas flows, or decomposition flows, and hydrocarbon fractions, etc., and flows formed from them. 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. Condensed liquid flows are indicated by dashed-dotted arrows.

[0095] The steam cracking apparatus 2100 includes the use of an electric steam cracking furnace 210, which is also called an "electric coil box," as previously outlined. There is no convection zone.

[0096] 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.

[0097] The four quench exchangers 21, 22, 22a, and 23 are arranged in a sequence in the process gas path downstream of the electric steam cracking furnace 210, forming the quench cooling row 20 of the steam cracking apparatus 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 the tertiary quench exchanger, and the second to last quench exchanger in the sequence 22a may also be called the intermediate quench exchanger. Alternatively, both quench exchangers 21 and 22a may be referred to as secondary quench exchangers.

[0098] 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 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.

[0099] 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 Figure 2. See the above description for further details. In particular, a separation column is provided in which all or essentially all compressors are electrically driven.

[0100] 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.

[0101] 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 produced 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 produced, and the condensate CO is supercooled in the heat exchangers X3 and X1.

[0102] 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.

[0103] To summarize the explanation and illustration of Figure 2 and the steam cracking apparatus 2100, the process gas PE is vaporized in the first stage (in the quench exchanger 21), similar to a state-of-the-art combustion furnace. do The boiler feedwater BF is rapidly and effectively cooled. In the second stage (in the quench exchanger 22), the process gas PE is cooled in the feed-effluent exchanger relative to the process gas PR, and the process gas PR is preheated before being supplied to the electric cracking furnace 11. In the embodiment shown in Figure 2, the quench exchanger 22a is provided to cool the process gas PE, while a portion of the saturated steam SS generated in the quench exchanger 21 may be moderately superheated.

[0104] Figure 3 shows a further steam cracking apparatus 2200 according to one embodiment of the present invention. Generally, the description relating to the steam cracking apparatus 2100 in Figure 1 also applies to the steam cracking apparatus 2200 in Figure 3, with only the differences being described below.

[0105] In the steam cracking apparatus 2200 shown in Figure 3, 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.

[0106] Figure 4 shows a further steam cracking apparatus 2300 according to one embodiment of the present invention. Generally, the explanation relating to the steam cracking apparatus 2200 according to Figure 3, based on the steam cracking apparatus 2100 according to Figure 2, applies to the steam cracking apparatus 2300 according to Figure 4, with only the differences being explained below.

[0107] In the steam cracking apparatus 2300 shown in Figure 4, the quench exchanger 22a is absent, and instead, an electric steam superheater E2 is provided. In the steam cracking apparatus 2300 shown in Figure 4, 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.

[0108] 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.

[0109] Therefore, in the embodiment shown in Figure 4, the first two quenching stages are reversed, meaning that the efferent process gas PE is first cooled relative to the preheated feed process gas PR, and then to the vaporized boiler feedwater BF. In such embodiments, an electric feed preheater is not necessary, as a sufficiently high preheating temperature can be reached within the quench exchanger 21. The discharged high-pressure steam is also moderately superheated, and both variations from Figures 2 and 3 can be used for steam superheating.

[0110] All three embodiments shown in Figures 2 to 4 are specifically designed for an electric cracking furnace 210 operating with a light (gasic) feedstock, most preferably consisting mostly of ethane. Accordingly, all three embodiments feature a quench exchanger 23, which, in accordance with modern industrial practice, further cools the decomposition gas to a temperature of 200°C, while in particular preheating the boiler feedwater to the steam drum 31.

[0111] 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.

[0112] Figure 5 shows a further steam cracking apparatus 2400 according to one embodiment of the present invention. Generally, the explanation relating to the steam cracking apparatus 2200 in Figure 3, which is based on the explanation of the steam cracking apparatus 2100 in Figure 2, also applies to the steam cracking apparatus 2400 in Figure 5, with only the differences being explained below.

[0113] In the steam cracking apparatus 2400 shown in Figure 5, there is no quench exchanger 22a, and instead an electric steam superheater E2 is provided. Here, a portion of the superheated steam SU is supplied to the heat exchanger X3 instead of a portion of the superheated steam SS. Therefore, the process flow PR can be heated in the heat exchanger X2 to a temperature of approximately 330°C, and thus less heat is recovered in the quench exchanger 22, and the process flow PE efluent cooled in the quench exchanger 22 is recovered from the quench exchanger 22 at a temperature of approximately 370°C.

[0114] The embodiment in Figure 5 specifically demonstrates that, as an alternative to the previously shown embodiments, moderately superheated steam SU can also be used to ensure the initial preheating of the hydrocarbon feed HC and process steam PS after the generation of the process flow PR.

[0115] Figure 6 shows a further steam cracking apparatus 2500 according to one embodiment of the present invention. Generally, the explanation relating to the main components of the steam cracking apparatus 2100 according to Figure 2 also applies to the steam cracking apparatus 2500 according to Figure 6, but there are some differences, which are described below.

[0116] In the steam cracking apparatus 2500 shown in Figure 6, 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. The 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, as previously, particularly to a temperature of about 660°C, before being supplied to the electric steam cracking furnace 210. The efluent of process gas PE is recovered from the electric steam cracking furnace 210, particularly at a temperature of about 840°C, particularly from the quench exchanger 21, particularly at a temperature of about 510°C, particularly from the quench exchanger 22 (there is no further quench exchanger 22a), particularly at a temperature of about 340°C, and particularly from the quench exchanger 23, particularly at a temperature of about 200°C.

[0117] 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.

[0118] The embodiment shown in Figure 6 includes a further option to ensure initial preheating of the hydrocarbon feed HC and process vapor PS after the generation of the process flow PR, and the quench exchanger 23 is designed as a feed-effleurent exchanger. This possibility can also be combined with embodiments shown, for example, in Figures 2, 3, and 5.

[0119] Figure 7 shows a further steam cracking apparatus 2600 according to one embodiment of the present invention. Generally, the explanation relating to the steam cracking apparatus 2200 in Figure 3, which is based on the explanation of the steam cracking apparatus 2100 in Figure 2, also applies to the steam cracking apparatus 2600 in Figure 7, with only the differences being explained below.

[0120] In the steam cracking apparatus 2600 shown in Figure 7, there is no quench exchanger 23, and an oil quench 25 is used instead. Thus, the boiler feedwater BF is heated only in the heat exchanger X3, particularly to a temperature of about 260°C, before being passed through the steam drum 31. A further heat exchanger X4 is provided to further heat the feed hydrocarbons before mixing with the 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 are operated by saturated steam SS, and the condensate flow is collected before being used in heat exchangers X1 and X3, as previously described.

[0121] In the steam cracking apparatus 2600 shown in Figure 7, process steam PS is initially supplied, particularly at a temperature of about 180°C. The temperature of the process flow PR downstream of the heat exchanger X2 is particularly about 300°C. Heating in the electric heater E1 is carried out, particularly up to a temperature of about 630°C. The efferent process gas PE is recovered from the electric cracking furnace 210, particularly at a temperature of about 870°C, from the quench exchanger 21, particularly at a temperature of about 600°C, from the first quench exchanger 22, particularly at a temperature of about 390°C, from the quench exchanger 22a, particularly at a temperature of about 380°C, and from the oil quench 25 at a further appropriate temperature. The saturated steam generated in the steam drum 21 is supplied, particularly at an absolute pressure level of about 122 bar and particularly at a temperature of about 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.

[0122] Figure 8 shows a further steam cracking apparatus 2700 according to one embodiment of the present invention. Generally, the description relating to the steam cracking apparatus 2600 according to Figure 7, based on the steam cracking apparatus 2100 according to Figure 2, applies to the steam cracking apparatus 2700 according to Figure 8, with only the differences being described below.

[0123] In the steam cracking apparatus 2700 shown in Figure 8, 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.

[0124] As alternative process variations, Figures 7 and 8 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 7 and 8, 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 7 and 8 are simple adaptations to the embodiments shown in Figure 2. Thus, the variations presented by the embodiments shown in Figures 3 to 5 can also be applied to the liquid feed furnaces shown in Figures 7 and 8, as the liquid feed furnaces shown in Figures 7 and 8 are applied to the gas feed furnaces in Figure 2.

[0125] Figure 9 shows a further steam cracking apparatus 2800 according to one embodiment of the present invention. Generally, the explanation relating to the steam cracking apparatus 2700 according to Figure 8, which is based on the explanation of the steam cracking apparatus 2100 according to Figure 2, also applies to the steam cracking apparatus 2800 according to Figure 9, with only the differences being explained below.

[0126] Similar to the steam cracking apparatus 2200 shown in Figure 3, the quench exchanger 22a is omitted, and an electric steam superheater E2 is provided instead. As an exemplary variant, Figure 9 shows a process variant for a heavy liquid feed furnace similar to the gas feed variant shown in Figure 4 (the quench exchanger 21 is designed as a feed-effluent exchanger).

[0127] In Figure 10, a Molyer (enthalpy / entropy) diagram for water is shown, where entropy s is displayed on the horizontal axis in units of kJ / (K×kg) and enthalpy h is displayed on the vertical axis in units of kJ / kg. 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 and equivalence EnthalpiExpansion 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.

[0128] According to the present invention, a simple equivalent Enthalpi Due to expansion, the pressure increases. phase Without alteration, the pressure and temperature required by the heat consumer can be reduced to the required level. (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 the pressure range between absolute pressures of 20 to 160 bar, with dew points of (+20K and +80K). room The corresponding most preferred curved envelopes 82 and 83 (which have the same characteristics) are shown in Figure 11. In Figure 11, absolute pressure in bar units is shown on the horizontal axis, and temperature in °C is shown on the vertical axis.

[0129] Same example, etc. Enthalpi Dew point corresponding to curve 81 room This is shown in Figure 12 for the same pressure range. In Figure 12, the absolute pressure in bar units is again shown on the horizontal axis, while the temperature difference values ​​in kcal units are shown on the vertical axis.

Claims

1. A steam cracking method using a steam cracking apparatus (2100-2800), wherein the steam cracking apparatus (2100-2800) includes an electric cracking furnace (10) without a convection area (12), and further includes a quench cooling row (20), and a process gas flow is passed through at least the electric cracking furnace (10) and the quench cooling row (20), wherein the quench cooling row (20) is operated to include at least two separate cooling stages arranged in any order, the first cooling of the cooling stage In a cooling stage, at least a portion of the process gas flow recovered from the electric cracking furnace (10) is cooled against boiler feedwater vaporized at an absolute pressure level between 30 and 175 bar; in a second cooling stage of the cooling stage, at least a portion of the process gas flow recovered from the electric cracking furnace (10) is cooled against a superheated mixture of feed hydrocarbons and process steam used to generate the process gas flow, thereby heating the superheated mixture to a temperature level between 350 and 750°C; a method.

2. The method according to claim 1, wherein, during the hydrocarbon cracking operation, a heat amount not exceeding 1000 kW is transferred as sensible heat within the electric cracking furnace (10) to the process gas flow passing through the electric cracking furnace (10) or to a flow other than the process gas flow recovered from the electric cracking furnace (10).

3. The method according to claim 1 or 2, wherein the quench cooling train (20) is a quench cooling train (20) comprising a primary quench exchanger (21) and a secondary quench exchanger (22), the primary quench exchanger (21) is used to carry out at least a portion of the first cooling stage of the cooling stage, the secondary quench exchanger (22) is used to carry out at least a portion of the second cooling stage of the cooling stage, or vice versa.

4. The method according to claim 3, wherein the steam generator (30) operates in thermal coupling with the steam cracking device (2100-2800), and the use of one or more steam generators (30) generates at least superheated high-pressure steam at a first pressure level and a first temperature level of absolute pressure from 30 to 175 bar, and no steam at a temperature level higher than the first temperature level is generated, and the superheated high-pressure steam at the first pressure level is expanded at least partially adiabatically and isenthalpily 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, and the first temperature level is selected such that the second temperature level is 5 to 120 K higher than the dew point of the steam at the second pressure level.

5. The method according to claim 4, wherein a multi-flow heat exchanger and / or an electric steam superheater are used in the steam generator (30), and when the multi-flow heat exchanger is used, the heat transferred in the multi-flow heat exchanger from the process gas flow recovered from the electric cracking furnace (10) is transferred to the steam flow used for boiler feedwater and / or the generation of the superheated high-pressure steam, and when the electric steam superheater is used, the superheated high-pressure steam is generated in the electric steam superheater.

6. The method according to any one of claims 3 to 5, wherein at least a portion of the feed hydrocarbon used to produce the superheated mixture of feed hydrocarbon and process vapor is preheated in a multi-flow heat exchanger using at least a portion of the process gas flow recovered from the electric cracking furnace (10).

7. The method according to claim 5 or 6, wherein the quench cooling train (20) is a quench cooling train (20) comprising a further secondary quench exchanger (22a) and / or a tertiary quench exchanger (23), and the further secondary quench exchanger (22a) and / or the tertiary quench exchanger (23) is provided as the multiple flow heat exchanger.

8. The method according to claim 4 or 5, 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.

9. The method according to any one of claims 1 to 8, wherein the steam cracking apparatus or at least one of the steam cracking apparatuses is operated using different power consumption rates due to various operating modes, while maintaining a constant total cracking product yield.

10. The method according to claim 4 or 5, wherein at least a portion of the feed hydrocarbon and / or process steam and / or boiler feedwater used to produce the superheated mixture of feed hydrocarbon and process steam is preheated using saturated steam produced in one or more steam generators (30).

11. The method according to any one of claims 4, 5, or 10, wherein at least a portion of the feed hydrocarbon and / or process steam and / or boiler feedwater used to produce the superheated mixture of feed hydrocarbon and process steam is preheated using a saturated condensate stream or a supercooled condensate stream obtained from saturated steam produced in one or more steam generators (30).

12. A system (200) for carrying out a steam cracking method, comprising a steam cracking apparatus (2100-2800), wherein the steam cracking apparatus (2100-2800) comprises an electric cracking furnace (10) without a convection area (12) and a quench cooling row (20), and the system is adapted to allow a process gas flow through at least the electric cracking furnace (10) and the quench cooling row (20), wherein the quench cooling row (20) comprises means (21, 22, 23) for carrying out at least two separate cooling stages, and The first cooling stage of the cooling stage is adapted to cool at least a portion of the process gas flow recovered from the electric cracking furnace (10) to boiler feedwater vaporizing at an absolute pressure level between 30 and 175 bar, and the second cooling stage of the cooling stage is adapted to cool at least a portion of the process gas flow recovered from the electric cracking furnace (10) to a superheated mixture of feed hydrocarbons and process steam used to generate the process gas flow, thereby heating the superheated mixture to a temperature level between 350 and 750°C, the system (200).

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