Method and apparatus for producing reaction products using a heated reactor

Abstract

A method for producing reaction products using equipment (100, 200, 300) including a heated reactor (F) is proposed, wherein a reaction feed (5) is supplied to the reactor and a reactor effluent (1) is discharged from the reactor (F), wherein the heat of the reactor effluent (1) is transferred to a heat carrier medium (2), wherein the heat of the heat carrier medium (2) is transferred to a heat sink, and wherein the heat carrier medium (2) is provided in a cycle in which the heat carrier medium (2) is compressed using a circulating compressor (C1), wherein the heat of the reactor effluent (1) is transferred to the heat carrier medium (2) after the heat carrier medium (2) has been compressed using the circulating compressor (C1) and before the heat of the heat carrier medium (2) is transferred to the heat sink. The heat sink is the reaction feed and / or one or more components thereof. A corresponding equipment (100, 200, 300) for performing this method is also proposed herein.

Description

Technical Field

[0001] This invention relates to a method and apparatus for producing reaction products using a heated reactor. Background Technology

[0002] Steam cracking technology for the production of olefins and other basic chemicals is well-known. Currently, the heat energy required to operate an endothermic steam cracking reaction is typically provided by the combustion of fuel gas in the furnace. The actual process gas flows through so-called cracking coils located inside the furnace (also known as the radiant zone). In addition to the radiant zone, combustion cracking furnaces also include convection sections and quench sections.

[0003] As discussed further below, recent efforts to reduce CO2 emissions from steam cracking furnaces include replacing at least a portion of the fuel gas with electricity. See expert literature, such as MEH Tijiani et al., “Review of ElectricCracking of Hydrocarbons,” ACS Sustainable Chem. Eng. 2022, 10, 49, 16070–16089. However, as also discussed below, using electricity as the heat source for steam cracking may require substantial redesign of the reactor or furnace peripherals, particularly since heat from the convection section is no longer available for process tasks such as preheating boiler feedwater and / or hydrocarbon feed, (partial) vaporization of liquid hydrocarbon feed (with or without process steam injection), and superheating of process steam and high-pressure steam.

[0004] The aspects disclosed herein are not limited to steam cracking, but can also be applied to other chemical reactions using heated furnaces, particularly endothermic reactions discussed below. Furthermore, the aspects disclosed herein are not limited to electrically heated reactors, but are equally applicable to combustion reactors.

[0005] European patent application EP 4 269 758 A1 discloses an energy recovery method in which heat is transferred to a first heat transfer fluid, the heated first heat transfer fluid is compressed, and the compressed heat transfer fluid is used to vaporize aqueous condensate into steam, which can be used for heat recovery.

[0006] Chinese patent CN 106438043 B discloses a coal-based chemical looping combustion power generation system and method based on supercritical carbon dioxide. It is claimed that the system not only has high power generation efficiency, low nitrogen oxide emissions and easy carbon dioxide capture, but also organically combines chemical looping combustion technology with supercritical carbon dioxide cycle power generation.

[0007] For processes that use heated reactors, especially those that use electricity as a heat source, improved methods and equipment are needed. Summary of the Invention

[0008] Against this backdrop, methods and apparatus incorporating the features of the independent claims are proposed. Embodiments are the subject of the independent claims and the following description.

[0009] The method for producing reaction products proposed herein includes using equipment comprising a heated reactor, wherein a reaction feed is supplied to the reactor and a reactor effluent is removed from the reactor, wherein heat of the reactor effluent is transferred to a heat carrier medium, wherein heat of the heat carrier medium is transferred to a heat sink, and wherein the heat carrier medium is provided in a circulation, wherein the heat carrier medium is compressed using a circulating compressor, and wherein heat of the reactor effluent is transferred to the heat carrier medium after the heat carrier medium has been compressed using the circulating compressor and before the heat of the heat carrier medium is transferred to the heat sink. The heat sink is the reaction feed or a portion or component thereof, such as a mixture and / or separate hydrocarbons and / or vapors, and / or a portion of such a stream.

[0010] The method presented in this paper offers numerous advantages, which are discussed in detail below, including the efficient transfer of heat from reactor effluent to the heat sink without the substantial fouling hazard that may be observed with other methods, such as feed effluent heat exchangers.

[0011] According to certain embodiments, the heat of compression generated when the heat carrier medium is compressed using a circulating compressor is at least partially transferred to the heat sink along with the heat carrier medium. Such embodiments include the advantageous use of the heat carrier medium as part of a heat pump, as explained further below. In short, such embodiments allow the gap between available heat (from reactor effluent) and required heat (for the heat sink, such as reaction feed or its components) to be bridged by the heat of compression. This advantage is particularly accompanied by the benefit of improved heat transfer to denser, compressed media.

[0012] According to some embodiments, the reactor is used to carry out endothermic reaction processes to produce reaction products. The embodiments disclosed herein are generally applicable to various reactions and provide an effective solution, particularly for performing heat transfer from effluent to heat sink.

[0013] According to some embodiments, the reaction process is selected from steam cracking, autothermal reforming, steam methane reforming, ammonia cracking, or combinations thereof. These reactions particularly benefit from the methods presented herein.

[0014] According to some embodiments, the reactor is a combustion reactor in which flue gas is produced, and the heat of the flue gas is used for at least one of process and boiler feedwater / steam heating and combustion air preheating. That is, according to such embodiments, the heat of the flue gas can be used for other advantageous purposes while still achieving proper heating of the feed as a heat sink.

[0015] According to some other embodiments, the reactor is an electrically heated reactor that does not produce flue gas. The reactor can also be partially electrically heated, thus reducing the amount of available flue gas. The methods proposed herein enable effective heating of the feed as a heat sink even in these cases.

[0016] According to certain embodiments, the heat transfer medium is provided in a dense-phase gaseous state or a supercritical state (these terms are used as they are conventionally understood in the art) during circulation and does not undergo a phase change during thermal cycling. Therefore, more efficient heat transfer from reactor effluent to the heat transfer medium can be achieved compared to the lower-density gaseous medium proposed herein.

[0017] In some embodiments, a temperature distribution of the heat transfer medium during circulation is provided such that the temperature of the heat transfer medium in the heat exchanger used to transfer heat from the reactor effluent to the heat transfer medium does not exceed a predetermined temperature value. In particular, this avoids exceeding certain surface temperatures in the heat exchanger and reduces fouling.

[0018] According to some embodiments, the heat transfer medium includes, but is not limited to, at least one of argon, helium, nitrogen, air, and hydrocarbons. These components are particularly advantageous because they can withstand the high temperatures typically involved in the methods disclosed herein.

[0019] According to some embodiments, further heat from the reactor effluent is transferred to another medium. That is, if the heat from the reactor effluent is available in an amount exceeding a specific requirement (e.g., for heating the feed), a portion may be transferred to other media, particularly in a heat exchanger downstream of the heat exchanger used to transfer heat to the original heat transfer medium.

[0020] According to some embodiments, the pressure drop of the heat transfer medium in circulation is 5 to 20 bar. This allows certain configurations of heat transfer devices to have enhanced heat transfer characteristics, such as impingement coolers, in which a jet of cooling medium (i.e., heat transfer medium) is formed and impinged on a structure that guides the medium to be cooled (in the case of this disclosure, reactor effluent).

[0021] According to certain embodiments, heat transfer from reactor effluent to the heat transfer medium is carried out using a heat exchanger in which the reactor effluent is supplied to an inner tube and cooled therein, and the heat transfer medium is supplied to an outer tube disposed around the inner tube and heated therein to form an annular gap surrounding the inner tube, the annular gap including features for enhancing heat transfer. This allows for efficient heat transfer even when the heat transfer medium discussed herein is in a non-liquid state.

[0022] According to some embodiments, features for enhancing heat transfer include features for fluid impingement, turbulence promotion, high shear-induced geometry, or increased surface area. In particular, impingement coolers, including so-called piccolo or plate impingement structures, commonly known in the art, can be used.

[0023] According to some embodiments, the heat from the heat transfer medium is transferred to an organic Rankine cycle that uses an expander to drive the cycle compressor, particularly in conjunction with an electric motor. This allows for efficient utilization of waste heat and reduces the (electrical) energy required to drive the cycle compressor.

[0024] The apparatus proposed herein for production includes a heated reactor, wherein the apparatus is configured to supply a reaction feed to the reactor and remove a reactor effluent from the reactor. The apparatus includes a first heat exchanger configured to transfer heat from the reactor effluent to a heat carrier medium. The apparatus includes a second heat exchanger configured to transfer heat from the heat carrier medium to a heat sink. The apparatus includes means for providing the heat carrier medium in a cycle, wherein the first heat exchanger, the second heat exchanger, and a circulating compressor configured to compress the heat carrier medium are arranged in the cycle. The first heat exchanger is arranged downstream of the circulating compressor in the cycle, and the second heat exchanger is arranged downstream of the first heat exchanger in the cycle. The second heat exchanger is configured to transfer heat from the heat carrier medium to the reaction feed, which serves as a heat sink. The apparatus proposed herein is particularly configured to transfer heat from the reactor effluent to the heat carrier medium after the heat carrier medium has been compressed using the circulating compressor and before the heat from the heat carrier medium has been transferred to the heat sink.

[0025] For further details and advantages of such a device, refer above to the description of the methods presented herein and their various embodiments. In particular, such a device, in the embodiments presented herein, may include means adapted to perform the methods according to any of the embodiments discussed herein. Attached Figure Description

[0026] The embodiments disclosed herein will now be described by way of example only with reference to the accompanying drawings, in which:

[0027] Figure 1 A device according to one embodiment is shown;

[0028] Figure 2 A device according to one embodiment is shown; and

[0029] Figure 3 A device according to one embodiment is shown. Detailed Implementation

[0030] In the accompanying drawings, elements having the same, substantially the same, comparable, or technically compatible functions and / or purposes may be identified using the same reference numerals, and repeated explanations may be omitted for brevity. The descriptions herein of devices, apparatuses, arrangements, systems, etc., according to certain disclosed embodiments also apply to methods, processes, procedures, etc., according to corresponding embodiments.

[0031] The various embodiments described herein are presented merely to aid in understanding and teaching the claimed features. These embodiments are provided as representative examples only and are not exhaustive or exclusive. It should be understood that the advantages, embodiments, examples, functions, features, structures and / or other aspects described herein should not be considered as limitations on the scope of the invention as defined by the claims or on the equivalents of the claims, and other embodiments and modifications may be utilized without departing from the scope of the claimed invention.

[0032] The various embodiments disclosed herein may suitably include, consist of, or substantially consist of suitable and technically reasonable combinations of the disclosed elements, components, features, parts, steps, means, etc., other than those specifically described herein. Furthermore, this disclosure may include other inventions not currently claimed but which may be claimed in the future, particularly within the scope of the independent claims.

[0033] Methods and equipment for steam cracking are described in expert literature, for example, in Ullmann's Encyclopedia of Industrial Chemistry, article "Ethylene," published online April 15, 2009, DOI:10.1002 / 14356007.a10_045.pub2, in the article by Tijiani et al. cited at the beginning, and in the applicant's EP 4 305 344 A1. Certain terms used herein for steam cracking equipment components and corresponding method steps should have their conventional meaning.

[0034] In the radiant section of a combustion-type steam pyrolysis furnace, the process gas is continuously heated along its path through the coils inside the furnace, allowing the desired pyrolysis reaction to occur within the coils. Typical inlet temperatures for the process gas entering the coils are between 550 and 750°C, while coil outlet temperatures are typically in the range of 800 to 900°C.

[0035] In a combustion-type steam cracker, the convection section is typically located above the radiant section and comprises various tube bundles that pass through the flue gas passages. The function of the convection section is to recover as much energy as possible from the hot flue gas leaving the radiant section. In practice, only 35% to 50% of the total combustion load is typically transferred to the process gas flowing through the cracking coils. Therefore, the convection section plays a central role in the energy management of a combustion-type steam cracker, as it is responsible for efficiently utilizing approximately 40% to 60% of the furnace heat input (i.e., the combustion load).

[0036] In practice, when the radiant and convective sections are considered together, modern combustion-type steam cracking furnaces can utilize 90% to 95% of the total combustion load (based on the low calorific value of the combustion fuel gas). Therefore, the flue gas is typically cooled to a temperature level between 120 and 160°C before leaving the convective section and being discharged into the atmosphere through the chimney.

[0037] As mentioned at the beginning, the heat recovered from the flue gas in the convection section of a combustion-type steam cracker is typically used for process tasks such as preheating boiler feedwater and / or hydrocarbon feeds, (partial) vaporization of liquid hydrocarbon feeds (with or without process steam injection), and superheating of process steam and high-pressure steam. In the convection section of a low-emission furnace with combustion air preheating, the energy recovered from the flue gas can also be used directly or indirectly to preheat the combustion air before it enters the burners arranged in the radiant section.

[0038] In the process flow, the quench section is located downstream of the radiant section along the main process gas route. It includes one or more heat exchanger units whose function is to rapidly cool the process gas to below the maximum temperature level to stop the pyrolysis reaction, further cool the process gas for downstream processing, and effectively recover the sensible heat of the process gas for further energy utilization. Furthermore, further cooling / quenching can be achieved by injecting liquid, such as oil quenching in a liquid-feed pyrolysis furnace.

[0039] The heat recovered from the process gases in the quench section is typically used to vaporize (ultra) high-pressure boiler feedwater (typically ranging from 30 to 125 bar absolute pressure) and preheat the same feedwater before it is fed into the steam drum. The resulting high-purity (ultra) high-pressure steam is then superheated in the convection section (see above) and distributed from there to the central steam system of the cracking furnace unit to provide heat and power to the heat exchangers and steam turbines. Typical steam superheating achieved in the furnace convection section is between 150 and 250 K above the saturation temperature (dew point margin).

[0040] In EP 3 415 587 A1, an improved convection and quench section arrangement for a combustion-type furnace with air preheating is proposed, wherein a mixture of hydrocarbon feed and process steam is heated directly relative to the process gas in a quench exchanger. However, these concepts are strictly dependent on the presence of a convection section and are explicitly limited to combustion-type furnaces.

[0041] With the prospect of shifting from fossil fuel combustion to renewable energy use, new developments have emerged regarding the replacement of combustion-type pyrolysis furnaces with electrically heated furnaces. As mentioned at the beginning, this may require a substantial redesign of the steam pyrolysis furnace unit and solutions to address the significantly different heat balance and available waste heat in electrically heated steam pyrolysis.

[0042] The method presented in this paper provides a favorable concept for energy integration into the complete furnace architecture, including preheating and quenching sections, and thus into a broader pyrolysis furnace unit architecture. The efficient and effective integration of electrically heated furnaces into steam pyrolysis furnaces, as proposed in this paper, is crucial for the overall plant design, particularly in terms of energy management. The method presented in this paper addresses a major challenge arising from the lack of a convection section in electrically heated furnaces. This is significant because it has been mentioned that 40% to 60% of the total heat input in combustion pyrolysis furnaces is recovered in the convection section and used for various purposes.

[0043] According to this disclosure, a solution is provided for balancing and distributing heat in low-to-zero emission steam cracking furnaces using some, most, or all of the electrically heated furnaces. The concepts and solutions presented herein are applicable to the design of electrically heated furnace systems to meet requirements or needs including electrically heating a premixed feed of hydrocarbons and steam to the cracking coil from an inlet temperature of 550 to 750°C to an outlet temperature of 800 to 900°C, thereby achieving similar or better cracking yields to combustion cracking furnaces, and preheating the hydrocarbon feed stream from a typical supply temperature of 20 to 150°C and vaporizing it to the aforementioned coil inlet temperature of 550 to 750°C in the case of a liquid feed.

[0044] The preheating and vaporization of hydrocarbon feedstocks must be carried out with or without the addition of superheated process steam, which is typically supplied to the furnace system at a temperature level between 130 and 200°C. Furthermore, the requirement or demand is that the process gas downstream of the cracking coil be effectively and very rapidly cooled to a temperature level of 300 to 450°C (liquid feedstock) or 150 to 300°C (gaseous feedstock) in one or more multi-stream heat exchangers, allowing heat recovery from the process gas and balancing the energy flow between the furnace system and its peripheral equipment to ensure safe, reliable, and efficient operation.

[0045] There are no examples in the current state of technology of how to solve these tasks simultaneously, because all integrated combustion furnace concepts rely heavily on the presence of a convection section, in which heat is recovered from hot flue gas and typically transferred to hydrocarbon feedstocks, process steam, boiler feedwater and (ultra) high-pressure steam.

[0046] Another aspect to consider is that the electric drive of rotating equipment typically boasts superior efficiency exceeding 90%, while conventional steam turbines generally only achieve 30% to 40%. The lack of excess heat from the convection section and the availability of electricity from renewable energy sources increase the need to utilize energy recovered from cracked gas cooling for process heating rather than driving pumps and compressors. Therefore, conventional cracked gas quenching based on steam production cannot be considered a preferred method. A more efficient heat integration approach needs to be determined.

[0047] Previous disclosures have not addressed how available process heat is supplied to the steam cracking furnace unit and the numerous other process heat users in adjacent chemical complexes. For example, some embodiments disclosed in WO 2020 / 150244 A1 specifically mention that steam should not be used as the primary energy carrier, and that heat should either be exchanged directly between the cracked gas and the feed stream, or indirectly via a heat transfer fluid. One embodiment in that publication explicitly mentions the use of nitrogen, methane, or carbon dioxide for primary quenching of the cracked gas in the pyrolysis reaction section.

[0048] Transferring heat from the cracked gas, either indirectly or directly, to the furnace feed is indeed a very promising approach, characterized by reduced energy consumption in electrically heated ethylene plants. This has been disclosed, for example, in the thermal integration concept of EP 4 056 894 A1, which relies on direct heat exchange (at least partially) between the cracked gas and the feed stream.

[0049] However, energy recovery units used for pyrolysis gas cooling need to meet specific requirements to ensure product yield and furnace operating cycle. Rapid quenching of pyrolysis gas with short residence time and low pressure drop is typically achieved in "transfer line exchangers" that use boiling water as a coolant and have a high heat transfer coefficient.

[0050] When the cooling fluid becomes a gaseous feed stream or any other heat transfer fluid (such as nitrogen or methane) with a poor heat transfer coefficient, the aforementioned literature does not answer how to meet these requirements using existing technologies. Compensating for a poor heat transfer coefficient by relying on a large temperature difference between the furnace effluent and the cooling fluid cannot be considered an option, as it would cause heavy hydrocarbon condensation on the cracked gas side and lead to fouling of the quench system. This results in poor quench performance and consequently, product yield losses. In addition to poor process performance, the small heat transfer coefficient necessitates very large exchanger units, making their constructability highly questionable.

[0051] Another unresolved issue is how to utilize existing technology to preheat the feed using the heat from the cracked gas at temperatures above 800°C, while simultaneously controlling the risk of pre-cracking of hydrocarbon feed before it enters the furnace cracking coil.

[0052] Another aspect that needs to be addressed is the imbalance between the available heat from the cracked gas and the heat required for feed preheating. Previous publications relied on a combination of feed-effect cracked gas quench exchangers (“FEX”), additional balancing quench exchangers (for steam generation), and electric feed preheating to achieve this balance. However, current electric heating technologies above 450°C rely on low-voltage process heating, which in turn means more transformer losses and less efficient processes. As for quench exchangers for steam generation, not every plant has a steam requirement.

[0053] Therefore, alternatives that do not require the generation of steam must be provided, and these alternatives are provided in accordance with this disclosure.

[0054] The embodiments disclosed herein relate to a novel thermal integration concept that uses an intermediate heat carrier medium to transfer heat from the thermal reactor effluent to the reactor feed stream for preheating. The negative difference between the available heat (from the heat source) and the required heat (in the heat sink) is compensated by the compressive heat introduced into the heat carrier medium during the circulation driven by the circulating compressor.

[0055] The heat transfer medium can be a dense-phase medium that does not undergo a phase change during circulation (e.g., nitrogen at approximately 60 bar absolute pressure). The heat transfer medium can be pumped by a compressor, which can be driven by a medium-pressure electric motor, through a cycle that includes a cracked gas heat recovery unit (where cracked gas quenching can be based on a shock cooling concept such as that disclosed in European Patent Application 23165609.1) and multiple feed and dilution steam preheating units (e.g., including tubular heat exchangers).

[0056] The embodiments presented herein include the following features, which may be optionally or mandatory as part of the invention, depending on whether they are specifically claimed, and may include:

[0057] 1. Heat at high temperatures is recovered from a heat source (e.g., thermal reactor effluent such as cracked gas from a steam cracking coil) via an intermediate heat carrier medium and transferred to a heat sink (e.g., hydrocarbon feed stream to a steam cracking furnace).

[0058] 2. An intermediate heat carrier is circulated and applied to endothermic reaction processes, such as steam cracking processes, characterized in that...

[0059] a) Utilizing the heat from the flue gas in a combustion reactor not only for process and boiler feedwater / steam heating, but also for preheating combustion air as an energy-saving measure, or b) where there is no flue gas heat due to the electric heating mechanism of the reactor, such as in an electrically heated steam cracker.

[0060] 3. 100% or only a portion of the heat in the reactor effluent (in steam cracking: from the cracking coil outlet temperature to the quench fitting or quench tower inlet temperature) can be transferred to the intermediate heat carrier medium. If only a portion of the cracked gas heat is transferred to the intermediate heat carrier, heat recovery is achieved in a two-stage heat exchanger arrangement, where the primary heat exchanger is cooled with the intermediate heat carrier medium, and the secondary heat exchanger is cooled with a separate medium (e.g., boiler feedwater) for generating steam or heating only the boiler feedwater.

[0061] 4. The intermediate heat carrier medium can be in a dense gaseous state or a supercritical state, as mentioned above, and does not undergo any phase change during the thermal integration cycle.

[0062] 5. The heat transfer medium can be thermally stable and can have a high volumetric specific heat capacity, which can be achieved by utilizing dense phase or even supercritical fluids, such as argon, helium, nitrogen or hydrocarbons such as methane or combinations thereof.

[0063] 6. The heat transfer medium compressor can not only provide driving force (head) to overcome the pressure drop in the heat transfer medium cycle, but also act as a heat pump to balance the difference between the available heat from the heat source and the heat required by the heat sink.

[0064] 7. Allowing a high pressure drop of 5 to 20 bar in the heat transfer fluid circulation enables the application of special heat transfer enhancement features to achieve high heat transfer coefficients, particularly in the heat exchanger of the circulation, as explained in the following point.

[0065] 8. According to the process applied in this invention, the cooling performance of the heat recovery assembly may need to be similar to the known behavior of conventional steam generator quench exchanger designs. One example may include the need for rapid cooling rates (e.g., 2 K / ms or more) and high heat transfer rates, short residence times (e.g., 100 ms or less), and small pressure drops (e.g., 350 mbar or less) for quenching pyrolysis gas from a steam pyrolysis furnace. In conjunction with further aspects disclosed herein, this can be achieved in an energy recovery device in which the effluent from the thermal reactor is supplied to and cooled in an inner tube of the device, and a heat carrier medium is supplied to and heated in an outer tube disposed around the inner tube to surround an annular gap around the inner tube. This annular gap includes features for enhancing heat transfer to improve heat transfer from the inner tube to the annular gap. These features may be fluid impingement, turbulence promotion, high shear-induced geometry, or increased surface area. For further details on how such a device can be implemented, refer to the already mentioned European patent application 23165609.1. The proposed concept deviates in such a way that an intermediate heat carrier medium replaces the hydrocarbon feed on the outer tube side of the device.

[0066] 9. For naphtha steam cracking, the available heat in the intermediate heat carrier cycle covers the tasks of hydrocarbon feed vaporization, dilution steam superheating, and further superheating of the hydrocarbon / steam mixture to the inlet temperature required for the cracking coil.

[0067] 10. The temperature distribution of the intermediate heat carrier circulation and the tube wall temperature of the subsequent quench exchanger are selected in such a way that the risk of heavy hydrocarbon condensation at the cold end of the heat recovery unit and hydrocarbon feed pre-cracking at the hot end of the feed pre-heat exchanger is reduced or eliminated.

[0068] 11. The heat transfer fluid compressor can be a reciprocating or turbine compressor, driven by a steam turbine, electric motor or gas turbine.

[0069] 12. If the available reactor effluent heat transferred to the heat carrier cycle exceeds the required feed or process heat, the waste heat can be transferred to the Organic Rankine Cycle (ORC). The ORC's expansion turbine can then be combined with a circulating compressor and an electric motor drive to form a compression expander. Thus, the excess heat is directly converted into power, reducing the system's overall power consumption. This is particularly an option for gaseous feedstocks such as ethane or propane.

[0070] The embodiments presented herein will now be discussed in conjunction with the accompanying drawings, wherein... Figure 2 An apparatus 100 according to one embodiment is shown, which can be configured for naphtha vapor cracking in an electrically heated cracking furnace, exemplified as a heated reactor F.

[0071] The effluent 1 from the thermal reactor, namely the cracked gas from the cracking of naphtha vapor from the electrically heated cracking furnace or the heated reactor F, is rapidly and efficiently cooled to 360 to 420°C on the tube side of the gas / gas quench exchanger E1, relative to the intermediate heat carrier medium 2 (in this case, nitrogen, for example).

[0072] The flow characteristics (pressure drop, turbulence state, residence time, etc.) of the reactor effluent 1 on the tube side of the quench exchanger E1 are comparable to those of a conventional linear quench exchanger. On the heat carrier medium 2 side, the quench exchanger E1 can be equipped with features to enhance heat transfer, such as impingement cooling nozzles, which allows for a pressure drop of 4 to 15 bar on the heat carrier medium side.

[0073] The heat transfer medium 2 is supplied to the quench heat exchanger E1 by the circulating compressor C1 at elevated pressure and elevated temperature (e.g., at approximately 60 bar absolute pressure and 280°C), and is heated to approximately 700°C by the reactor effluent 1. The inlet and outlet temperatures of the heat transfer medium 2 entering and leaving the quench heat exchanger E1 are selected in such a way that the tube wall temperature on the reactor effluent 1 side does not exceed the critical temperature at the hot end and does not fall below the critical temperature at the cold end, to prevent fouling of the over-exchanger due to coking or heavy hydrocarbon condensation.

[0074] Downstream of the quench heat exchanger E1, the heat transfer medium (represented as 2 throughout the cycle) is directed to the feed / steam superheater E2, where it is cooled to approximately 380°C by superheating a mixture 5 of hydrocarbon feed 3 and dilution steam 4 (which are mixed in mixing unit M1) from approximately 180°C to a coil inlet temperature of approximately 600°C required to heat reactor F. The feed / steam superheater E2 may (but must) be equipped with features for enhanced heat transfer on the heat transfer medium 2 side, similar to the quench heat exchanger E1. Further downstream, the heat transfer medium 2 passes through another heat exchanger E3, where steam 4 is superheated from approximately 180°C to approximately 300°C, and the heat transfer medium 2 is cooled to approximately 360°C.

[0075] In other words, the heat of reactor effluent 1 is transferred to heat carrier medium 2 after the heat carrier medium has been compressed by circulating compressor C1 and before the heat of the heat carrier medium is transferred to the superheater E2 as a heat sink in the form of feed or steam.

[0076] The residual sensible heat of heat transfer medium 2 is sufficient to partially vaporize hydrocarbon feedstock 3, such as naphtha, in the fourth heat exchanger E4, with a gas phase fraction of approximately 0.75 at the outlet. In this exchanger, heat transfer medium 2 is further cooled to approximately 240°C and directed to the inlet of the circulating compressor C1, where its suction pressure p... s The discharge pressure p of the circulating compressor C1 d Pressure drop dp at heat exchangers E1 to E4 x and control device ( Figure 1 The pressure drop dp at (not shown in the image) c Determined as p s = p d - dp x - dp c .

[0077] The heat transfer medium 2 is recompressed in the circulating compressor C1, and the cycle restarts. Valve V1 is set for flow control and / or expansion.

[0078] The circulating compressor C1 in the heat transfer medium 2 loop can be a turbine compressor type machine, driven by an electric motor (medium pressure class), steam turbine, or expander, or a combination of expander and electric motor (compressor-expander), considering the large circulating mass and volumetric flow rate. Heating and vaporization of feed 3 can be achieved in a conventional tubular heat exchanger, while cooling of the cracked gas 1 requires a special heat exchanger with an exceptionally high heat transfer coefficient, considering that heat is exchanged between the two gas streams. This is particularly feasible in designs that rely on the aforementioned special heat transfer enhancement features.

[0079] This cycle can be operated using any kind of heat transfer medium 2 that does not undergo a phase change (i.e., remains gaseous or supercritical) and whose molecules are thermally stable over the operating temperature and pressure range. Ideally, the medium has a high specific heat capacity and a high molecular weight to facilitate technical compression in a turbine compressor. Gases such as nitrogen, argon, helium, and air (if leakage into the process can be mitigated) are considered suitable for the embodiments disclosed herein.

[0080] Specific liquid hydrocarbon feedstocks 3, such as naphtha or crude diesel, require more heat upstream of the cracking reaction in reactor F than the available heat in the cracked gas at the cracking coil outlet for preheating. For example, 110% of the available heat is required. Current thermal integration concepts limit cracked gas heat utilization to a maximum of 80% (in so-called FEX-SQE or sandwich FEX, where the abbreviations FEX and SQE represent the feed-effect heat exchanger and the secondary quench heat exchanger, respectively) or a maximum of 90% (in so-called FEX-PQE, where the abbreviation PQE represents the primary quench exchanger), and balance this through low-voltage electric heating, which comes with all the disadvantages of low-voltage systems, including transformer and copper losses.

[0081] Electric feed preheating is technically feasible, but operational experience is limited and it has not yet been applied on a large industrial scale. The embodiments presented in this paper enable the efficient utilization of all the heat from the pyrolysis gas for feed preheating, and the bridging of the heat gap between the heat source and the heat sink via a heat pump mechanism, without the need for low-voltage powered heaters for electric feed preheating. This is particularly relevant for liquid feedstocks such as naphtha and heavier components.

[0082] By placing the motor of the circulating compressor on a medium-voltage power supply, the installation of a low-voltage transformer and associated copper losses can be avoided. Furthermore, for naphtha cracking, total power consumption is significantly reduced by approximately 50% compared to the FEX-PQE-based thermal integration. For ethane or propane cracking, power consumption can be further reduced (approximately 85%) because the excess cracked gas heat that does not need to be used to preheat feed 3 can be converted into shaft power in the aforementioned compressor expander within the Organic Rankine Cycle (ORC). This improvement in unit efficiency can only be achieved by eliminating any heat output from the furnace system.

[0083] The highly integrated concept relies primarily on direct heat exchange between cracked gas 1 and feed 5 (feed / effluent quench exchanger, located at the primary or secondary quench position), which carries the risk of pre-cracking of hydrocarbon feed 5 in the heat exchanger used. The novel concept proposed in this paper avoids direct heat transfer from cracked gas 1 to feed 5, which adds additional operational safety by utilizing compressor control to prevent pre-cracking or fouling on the shell side of the quench heat exchanger E1. This ensures continuous and safe effluent quenching, which plays a crucial role in product selectivity during steam cracking.

[0084] The prototype quench heat exchanger (FEX-PQE) currently under discussion by experts for the primary quench location must be equipped with heat transfer enhancement features, such as fluid impingement, turbulence promotion, high shear-induced geometry, or increased surface area. These features result in a high pressure drop on their respective sides. To maintain a high level of product selectivity, these features must not be located on the reactor effluent 1 side (inside the tubes), but rather on the feed 5 side (shell side). However, the supply pressures of the feed and dilution steam are typically limited, thus limiting the permissible pressure drop in the feed preheating path, especially in retrofits of existing plants. Retrofits using primary feed / effluent quench exchangers can only be achieved with extensive measures, such as installing a “vapor compression” step in the dilution steam path. The new concept avoids these accompanying measures and allows operation on both the feed and effluent sides under conventional process parameters.

[0085] A key advantage of the embodiments presented herein is the full utilization of the high-temperature heat of the reactor effluent, as the intermediate heat carrier medium does not undergo a phase change in the heat recovery unit, unlike conventional quench designs. Conventional quench exchangers generate steam, and when used as a heating medium, the achievable temperature levels are limited. For steam cracking, this temperature limitation is approximately 300 to 320°C, depending on the steam pressure level (up to approximately 120 bar absolute pressure).

[0086] However, the intermediate heat transfer medium 2 in the proposed concept is a dense-phase or even supercritical medium that utilizes sensible heat to recover heat from the heat source and transfer it to the heat sink. Therefore, this cycle can cover a wide process temperature range from low temperatures to 700 to 720°C.

[0087] Furthermore, the dense phase of the heat transfer medium is advantageous for the heat transfer rate in the heat exchanger and allows for smaller circulation pipe diameters. Although the medium is in a dense or supercritical phase, the operating pressure level of the circulation (approximately 60 to 70 bar absolute pressure) is much lower than that of conventional ultra-high pressure (SHP) steam systems (approximately 110 to 120 bar absolute pressure), which allows for lower design pressures for process equipment and piping.

[0088] Another aspect particularly relevant to electrically heated steam pyrolysis furnaces (i.e., heated reactor F) is that the steam generated from the heat of the pyrolysis gas cannot be superheated by the process itself and requires electrical superheating. From a thermodynamic perspective, the use of this steam in steam turbines is not recommended, as the shaft power generated by the turbines is almost no more than the electrical power previously used for steam superheating. If steam is not required for purposes such as process heating (depending on the specific circumstances), it is more efficient to electrically vaporize the machine drive of the separation process and transfer the heat of the pyrolysis gas to the heat carrier cycle as proposed in this paper.

[0089] Another significant advantage of the concept presented in this paper is its ability to cover temperatures far exceeding the application range of conventional heat transfer oils and even molten salt heat transfer fluids. Simultaneously, the intermediate heat transfer fluid is cooled to a suitable intake temperature by the feed, enabling the application of existing turbine compressor technology based on conventional compressor materials. Industrial facilities already in operation where hot air or nitrogen is compressed as the heat transfer fluid in a thermal storage cycle (e.g., Stiesdal & AtlasCopco's grid-scale thermal battery) operate at similar temperatures in the compressor.

[0090] The embodiments presented herein may include at least one of the following additional or alternative features, either alone or in any combination.

[0091] As mentioned above, the application is not limited to steam cracking, but can also be applied to other reaction processes where it is necessary to recover the heat of reaction and transfer it to the reactor feed. It is particularly suitable for processes where the feed preheating load exceeds the available reactor effluent heat load and the circulating compressor allows the heat gap to be compensated for through its heat pump mechanism.

[0092] In the foregoing, the invention has been exemplarily described in an electrically heated pyrolysis furnace environment. However, the invention can also be applied to combustion pyrolysis furnaces, particularly combustion-heated furnaces with high levels of air preheating, ideally combined with high hydrogen content (15 to 100% molar content) in the furnace fuel gas: the heat that the cycle can provide for feed preheating no longer needs to be provided by flue gas heat. This surplus flue gas heat can then be used for combustion air preheating.

[0093] The steam cracking furnace device of the electric heating furnace system with the thermal integration system proposed in this paper may further include a combustion heating furnace in a hybrid system architecture.

[0094] When applied to steam cracking, the embodiments presented herein can be particularly combined with a separation section, in which all gas compressors with power tasks above 1 MW are driven by electric motors, since the steam output used to drive the turbines is less or no longer generated.

[0095] A steam pyrolysis furnace apparatus having an electric heating furnace system with integrated heat recovery according to the invention may further include a combustion heating furnace in a hybrid system architecture.

[0096] In existing plants or modified steam cracking furnace scenarios, this invention is preferably applied when steam production must be minimized or eliminated for any reason.

[0097] Figure 2 An embodiment of apparatus 200 in a gas-feed (ethane, propane) based steam cracking furnace environment is shown. The basic embodiment of the intermediate heat carrier cycle can be extended to an organic Rankine cycle (ORC), such as... Figure 2As shown, an organic Rankine cycle medium 6 is used. The organic Rankine cycle (e.g., using propane as the organic Rankine cycle medium 6) absorbs excess heat from the heat carrier cycle that is not needed for preheating the feed 3 in the heat exchanger E5 and converts it into shaft power by expanding via a turbine T1, which can be coupled to the circulating compressor C1, as shown.

[0098] Also in Figure 2 In the apparatus 200 shown, the heat of the reactor effluent 1 is transferred to the heat carrier medium 2 after the heat carrier medium has been compressed by the circulating compressor C1 and before the heat of the heat carrier medium is transferred to the heat sink via the feed / steam superheater E2.

[0099] Waste heat below 100°C can be used for process heating in the separation section, or alternatively transferred to the cooling water. Further components of the organic Rankine cycle include a heat exchanger E6 configured as an economizer, a heat exchanger E7 configured as a condenser (which is operated with a cooling medium flow 7 such as cooling water or process steam), a condensate drum or vessel D1, and an organic Rankine cycle pump P1.

[0100] For steam cracking furnaces with gaseous feedstocks, the anticipated alternative is to use the excess heat from the intermediate cycle for the organic Rankine cycle to generate minimum shaft power (as described above), and instead use the excess heat from the cycle for process heating or transfer it to other users, such as thermal energy storage.

[0101] For a steam cracker with gaseous feedstock, another embodiment proposed herein divides the cracked gas quenching into multiple independent exchangers: a primary quench exchanger that circulates heat to the intermediate heat carrier (just sufficient for preheating the feed and dilution steam); and a secondary quench exchanger that generates ultra-high pressure (SHP) or high pressure (HP) steam for heating the separation section of the steam cracker unit. A third-stage quench exchanger for preheating boiler feedwater can optionally be added.

[0102] In another embodiment of the present invention in a steam cracking furnace, the effluent from a hot reactor in a furnace can be split into two parallel quenching routes: one of which circulates sufficient heat to an intermediate heat carrier for feed preheating, while the parallel routes generate SHP or HP steam in a conventional quench exchanger.

[0103] Another embodiment of feedstocks with higher boiling point temperatures, such as heavy vacuum gas oil (HVO), crude diesel oil, pyrolysis oil from waste plastics, waxy fractions, etc., is shown as equipment 300 in Figure 4.

[0104] Heavy feedstocks require a higher hydrocarbon / dilution steam ratio and also a higher dilution steam superheat to fully vaporize the feed. Figure 4 illustrates how the proposed thermal integration concept can be extended to an electrically heated dilution steam superheater H1 to achieve higher dilution steam temperatures up to 500°C.

[0105] However, also in Figure 4, the heat of reactor effluent 1 is transferred to heat carrier medium 2 after the heat carrier medium has been compressed by the circulating compressor C1 and before the heat of the heat carrier medium is transferred to the heat sink via the feed / steam superheater E2.

[0106] The higher the boiling point of the feedstock, the faster the heat transfer performance is lost due to the gradual coking of the quench exchanger during operation. Ideas to compensate for this effect include, for example, operating the heat transfer fluid cycle under different process parameters, such as varying the suction pressure during operation (e.g., throttling of the suction valve or IGV causes an increase in compressor discharge temperature). This is to balance the reduced heat transfer from the quench exchanger to the cycle and ensure sufficient heat is provided for feed preheating.

[0107] To maximize reliability and availability in steam cracking applications, the embodiments proposed herein can be designed such that one intermediate heat carrier cycle is allocated to one cracking furnace. However, if capital expenditure is more important than availability, it is also feasible to use one heat carrier cycle to serve multiple furnace units to reduce the number of units. Another embodiment can also be based on the operation of one furnace unit with multiple parallel-operating thermally integrated cycles.

[0108] A further embodiment in the field of hydrocarbon cracking is to implement heat carrier circulation in a self-heating cracking reactor to produce light olefins, such as ethylene and propylene.

[0109] Another application area is syngas technology: for example, one embodiment of the invention can be high-temperature thermal integration in autothermal reforming processes, particularly where steam production is not required or only required to a certain extent. The same applies to electrically heated steam methane reformers (e-SMR) to reduce or eliminate unwanted steam production and / or reduce or even eliminate flame-heated feed preheating. Furthermore, conventional steam methane reforming or processes based on partial oxidation reactions can also reduce flame-heated feed preheating loads and thus CO2 emissions by implementing the proposed invention.

Claims

1. A method for producing reaction products using an apparatus (100, 200, 300) including a heated reactor (F), wherein a reaction feed (5) is supplied to the reactor and a reactor effluent (1) is removed from the reactor (F), wherein heat of the reactor effluent (1) is transferred to a heat carrier medium (2), wherein heat of the heat carrier medium (2) is transferred to a heat sink, and wherein the heat carrier medium (2) is provided in a cycle in which the heat carrier medium (2) is compressed using a circulating compressor (C1), wherein heat of the reactor effluent (1) is transferred to the heat carrier medium (2) after the heat carrier medium (2) has been compressed using the circulating compressor (C1) and before the heat of the heat carrier medium (2) is transferred to the heat sink, and wherein the reaction feed (5) or a portion or component thereof is used as the heat sink.

2. The method according to claim 1, wherein the heat of compression generated when the heat carrier medium (2) is compressed using the circulating compressor (C1) is transferred at least partially together with the heat carrier medium (2) to the heat sink.

3. The method according to claim 1 or 2, wherein the reactor (F) is used for an endothermic reaction process to produce reaction products.

4. The method according to claim 3, wherein the reaction process is selected from steam cracking process, autothermal reforming process, steam methane reforming process, ammonia cracking process, or a combination thereof.

5. The method according to claim 3 or 4, wherein the reactor (F) is a combustion reactor in which flue gas is generated, and the heat of the flue gas is used for at least one of process and boiler feedwater / steam heating and combustion air preheating.

6. The method according to claim 3 or 4, wherein the reactor (F) is an electrically heated reactor that does not produce flue gas.

7. The method according to any one of the preceding claims, wherein the heat carrier medium (2) is provided in a dense gaseous state or a supercritical state during the cycle and does not undergo a phase change during the thermal cycle.

8. The method according to any one of the preceding claims, wherein the temperature distribution of the heat carrier medium (2) in the circulation is provided such that the temperature of the heat carrier medium (2) in the heat exchanger (E1) for transferring heat from the reactor effluent (1) to the heat carrier medium (2) does not exceed a predetermined temperature value.

9. The method according to claim 7 or 8, wherein the heat carrier medium (2) comprises at least one of argon, helium, nitrogen, air and hydrocarbons, and / or wherein further heat of the reactor effluent (1) is transferred to another medium, and / or wherein the pressure drop of the heat carrier medium (2) in circulation is 5 to 20 bar.

10. The method according to any one of the preceding claims, wherein heat transfer from the reactor effluent (1) to the heat carrier medium (2) is carried out using the heat exchanger (E1), in which the reactor effluent (1) is supplied to an inner tube and cooled therein, and the heat carrier medium (2) is supplied to an outer tube disposed around the inner tube and heated therein to surround the inner tube to form an annular gap, the annular gap including features for enhancing heat transfer.

11. The method of claim 10, wherein the features for enhancing heat transfer include features for fluid impingement, turbulence promotion, high shear-induced geometry, or increased surface area.

12. The method according to any one of the preceding claims, wherein the heat of the heat carrier medium is transferred to an organic Rankine cycle, the organic Rankine cycle using an expander (T1) that drives the cycle compressor (C1).

13. An apparatus (100, 200, 300) for producing reaction products, comprising a heated reactor (F), wherein the apparatus (100, 200, 300) is configured to supply the reaction feed (5) to the reactor (F) and to remove reactor effluent (1) from the reactor (F), wherein the apparatus (100, 200, 300) includes a first heat exchanger (E1) configured to transfer heat from the reactor effluent (1) to a heat carrier medium (2), wherein the apparatus (100, 200, 300) includes a second heat exchanger (E2) configured to transfer heat from the heat carrier medium (2) to a heat carrier medium (2). The heat is transferred to the heat sink, and the device (100, 200, 300) includes means for providing the heat carrier medium (2) in a cycle, wherein the first heat exchanger (E1), the second heat exchanger (E2) and the circulating compressor (C1) configured to compress the heat carrier medium (2) are arranged in the cycle, wherein the first heat exchanger (E1) is arranged downstream of the circulating compressor (C1) in the cycle, wherein the second heat exchanger (E2) is arranged downstream of the first heat exchanger (E1) in the cycle, and wherein the second heat exchanger (E2) is configured to transfer the heat of the heat carrier medium (2) to the reaction feed (5) which is the heat sink.

14. The apparatus (100, 200, 300) according to claim 13, configured to perform the method according to any one of claims 1 to 12.

Images