Heat energy recovery device in electric heating cracking process

Abstract

A process for producing olefins may include at least one cooling step in thermal energy recovery by supplying a hydrocarbon feed to an outer tube of a thermal energy recovery assembly; heating the hydrocarbon feed in the outer tube of the thermal energy recovery assembly to output a preheated hydrocarbon feed; supplying the preheated hydrocarbon feed to an electric cracking furnace comprising a reaction zone to heat the preheated hydrocarbon feed; cracking the preheated hydrocarbon feed using heat generated by electricity in a reaction zone of an electrically heated cracking furnace to output a thermal reactor effluent comprising cracked hydrocarbons and olefins; supplying the thermal reactor effluent to an inner tube of a thermal energy recovery assembly; cooling the thermal reactor effluent in the inner tube of the thermal energy recovery assembly by transferring heat to the hydrocarbon feed; and wherein the inner tube exterior temperature in the thermal energy recovery assembly remains below 720 DEG C and the inner tube interior temperature in the thermal energy recovery assembly remains above 180 DEG C.

Description

Technical Field

[0001] This disclosure relates to systems and methods for transferring thermal energy, and more specifically, to energy recovery devices for transferring thermal energy from hot effluent to reactor feed. Background Technology

[0002] Steam cracking of hydrocarbon feedstocks in gas-fired steam crackers is a major commercial method for producing olefins. In this method, hydrocarbons such as ethane, propane, butane, condensate, light naphtha, heavy naphtha, gas oil, pyrolysis oil, materials from processing refinery streams, Fischer-Tropsch products, plastic waste, or biofeedback are heated from about 550°C to about 650°C, and sometimes close to 850°C, to facilitate their conversion into light olefins such as ethylene and propylene. Because the cracking reaction is endothermic, a large amount of heat must be supplied.

[0003] To provide the energy required for conventional steam cracking processes, natural gas and / or light gas can be burned in a gas-fired steam cracker. The combustion of hydrocarbons in the gas-fired steam cracker forms carbon dioxide, which is emitted as part of the flue gas from the cracker. Given current environmental considerations, such emissions are likely undesirable. Olefins are a major chemical building block and are typically produced in large quantities, ranging from hundreds of thousands of tons per year in small cracking units to 2 million tons or more per year in single large olefin production facilities. Therefore, using a gas-fired steam cracker to produce olefins could result in undesirable high levels of carbon dioxide emissions.

[0004] In conventional gas-fired olefin production furnaces, the combustion gases can only supply heat to the cracking reaction when the temperature exceeds the reaction temperature, for example, 550°C-650°C to 850°C. Once the gases cool below this temperature, it may be desirable to extract as much waste heat as possible to achieve energy-efficient operation of the equipment. This heat is typically recovered in the so-called convection section. Energy is often used to preheat the reactor feed and dilute the steam to the temperature required for the cracking reaction to occur.

[0005] In olefin production, once the feedstock is cracked, the reactor effluent should be cooled before further treatment of the cracked gas. Ideally, initial cooling occurs rapidly to reduce or prevent side reactions in the reactor effluent while it remains at a relatively high temperature. Furthermore, for energy-efficient processes, the heat from the reactor effluent should be recovered and used elsewhere in the process as much as possible.

[0006] In some systems, this quenching and cooling occurs in a quench waste heat boiler (TLE), where the reactor effluent is cooled to produce high-pressure steam by exchanging heat with liquid water. The advantage of cooling by exchanging heat with boiling water is that heat transfer is generally faster than when cooling with gas, sometimes five or even ten times faster for the same exchanger geometry. This steam can be used to drive turbines or other auxiliary equipment. For example, steam is commonly used to drive cracked gas compressors, one or more refrigeration compressors, or one or more pumps. Using steam to drive rotating equipment such as compressors and pumps is a convenient way to utilize energy recovered from cooling reactor effluent; however, the efficiency of converting energy in the form of heat (e.g., heat contained in the steam) into mechanical work is generally low, ranging from 30% to 50%.

[0007] One solution to reduce the significant amounts of carbon dioxide produced by conventional steam cracking processes is electrified steam cracking. Electrified steam cracking involves using a cracking furnace that is at least partially heated directly or indirectly by electricity. Compared to gas-fired cracking furnaces, electrified steam cracking furnaces produce fewer emissions.

[0008] However, electrified steam pyrolysis furnaces introduce new technological challenges that must be overcome. One consequence of using electrified steam pyrolysis furnaces is the elimination of hot flue gas from fuel combustion in gas-fired pyrolysis furnaces, meaning that heating typically provided by hot flue gas, including feed preheating, must be provided in a different manner. A second consequence is the need for different energy integrations during the pyrolysis process. For example, rotating equipment such as compressors and pumps is readily electrically driven; moreover, operating such equipment electrically is far more efficient than operating it with steam, typically achieving energy efficiencies greater than 90% compared to the 30% to 50% typically achieved with steam. Therefore, there is a considerable incentive to use electricity to drive these devices in electro-steam pyrolysis processes. This means that the energy currently recovered during cooling reactor effluent cannot be used to drive pumps and compressors; instead, different uses for this energy need to be found so that the overall energy efficiency of the process can be maintained at a high level.

[0009] For the electric process, the applicant has identified the need for systems and methods that utilize energy derived from the effluent of the quenched hot reactor while still rapidly quenching the pyrolysis gas to prevent further reaction. The applicant has also identified the need for systems and methods for preheating the feed to the electric furnace. Summary of the Invention

[0010] In embodiments of this disclosure, a method for producing olefins may include at least one cooling step in a heat recovery assembly. The cooling step may be characterized by: supplying a hydrocarbon feed to an outer tube of the heat recovery assembly; heating the hydrocarbon feed in the outer tube of the heat recovery assembly to output a preheated hydrocarbon feed; supplying the preheated hydrocarbon feed to an electrically heated cracking furnace including a reaction zone to heat the preheated hydrocarbon feed; cracking the preheated hydrocarbon feed in the reaction zone of the electrically heated cracking furnace using electrically generated heat to output a thermal reactor effluent containing cracked hydrocarbons and olefins; supplying the thermal reactor effluent to an inner tube of the heat recovery assembly; and cooling the thermal reactor effluent in the inner tube of the heat recovery assembly by transferring heat to the hydrocarbon feed. The external temperature of the inner tube in the heat recovery assembly may be maintained below 720°C and the internal temperature of the inner tube in the heat recovery assembly may be maintained above 160°C, preferably above 180°C.

[0011] In some embodiments, for ethane feedstocks, the external temperature of the inner tube can be maintained below 720°C; for propane feedstocks, below 700°C; for butane feedstocks, below 680°C; for naphtha feedstocks, below 660°C; and for feedstocks heavier than naphtha, below 640°C. In some embodiments, for ethane feedstocks, the internal temperature of the inner tube can be maintained above 160°C; for propane feedstocks, above 170°C; for butane feedstocks, above 180°C; and for naphtha feedstocks or feedstocks heavier than naphtha, above 270°C.

[0012] In some implementations, the thermal reactor effluent may first pass through a co-current section to exchange heat with the hydrocarbon feed portion for cooling, and then in a counter-current section for further heat exchange with the hydrocarbon feed for cooling.

[0013] In some implementations, the effluent from the thermal reactor is first cooled by heat exchange with the hydrocarbon feed in a co-current section, further cooled by heat exchange with the hydrocarbon feed in a steam generation section, and then further cooled by heat exchange with the hydrocarbon feed in a counter-current section.

[0014] In some embodiments, the hydrocarbon feed first passes through a co-current section and then through a counter-current section. In some embodiments, the hydrocarbon feed first passes through a counter-current section and then through a co-current section. In some embodiments, the counter-current section is a separate unit and is a shell-and-tube or tubular heat exchanger.

[0015] In some embodiments, the heat recovery assembly may include an outer tube; and an inner tube; wherein a hydrocarbon feed is supplied to an electric cracking furnace including a reaction zone to heat the hydrocarbon feed; wherein the inner tube includes a first inlet configured to receive thermal reactor effluent from the electric cracking furnace; and wherein the outer tube is disposed around the inner tube to surround an annular space surrounding the inner tube, the annular space including a second inlet configured to receive the hydrocarbon feed.

[0016] In some embodiments, the annular space includes at least one heat transfer enhancement structure to enhance heat transfer from the inner tube to the annular space. The at least one heat transfer enhancement structure may include one or more of an impingement structure, a turbulence-promoting structure, a high-shear-induced geometry, or a structure that increases surface area. The annular space may include a plate impingement structure located between an upstream and a downstream end, the plate impingement structure including: a first channel having a staged inlet at the upstream end and a closed flow at the downstream end; a second channel having a staged outlet at the downstream end, the second channel being disposed between the first channel and the inner tube; a wall separating the first channel and the second channel, the wall defining an opening for fluid connection of the first channel and the second channel; and the plate impingement structure configured to receive feed through the staged inlet, allow feed to flow from the first channel to the second channel via the opening in the wall, and cause the feed flow to impinge on the outer surface of the inner tube and discharge the feed through the staged outlet of the second channel. The annular space may include a piccolo impingement, comprising: an upstream separator disposed around an inner tube and within an outer tube; a downstream separator disposed around the inner tube and within the outer tube downstream of the upstream separator in the annular space, the downstream separator defining at least one stage outlet; a chamber defined within the outer tube and surrounding the inner tube between the upstream and downstream separators; and a piccolo tube disposed offset from the inner tube, extending from the upstream separator through the chamber to the downstream separator, the piccolo tube including a stage inlet for receiving incoming feed, the piccolo tube including a plurality of openings defined therein, the piccolo impingement being configured to receive feed from the stage inlet, allow feed to flow from the piccolo tube into the chamber via the plurality of openings, and discharge feed from the chamber via at least one stage outlet.

[0017] In some embodiments, the heat recovery assembly may include a plurality of inner tubes parallel to each other, wherein each inner tube is disposed within an outer tube, and each outer tube has one or more of the following: an impact structure, a turbulence-enhancing structure, a high-shear-induced geometry, or a structure that increases surface area, to enhance heat transfer from the inner tubes to the annular space defined within the outer tubes.

[0018] Some implementations may include the use of heat recovery components for implementing methods of olefin production.

[0019] This document also discusses in detail other aspects and advantages of these exemplary embodiments and other embodiments. Furthermore, it should be understood that the foregoing information and the following detailed description are merely illustrative examples of various aspects and embodiments, and are intended to provide an overview or framework for understanding the nature and characteristics of the claimed aspects and embodiments. Therefore, these and other objects, advantages, and features of this disclosure will become apparent from the following description and accompanying drawings. Moreover, it should be understood that the features of the various embodiments described herein are not mutually exclusive and can exist in various combinations and arrangements. Attached Figure Description

[0020] The accompanying drawings, which are incorporated in and constitute a part of this specification, are provided to provide a further understanding of embodiments of this disclosure and serve to illustrate embodiments of this disclosure, and together with the specific embodiments, to explain the principles of the embodiments discussed herein. No more detailed depiction of the structural details of this disclosure is attempted than is necessary for a basic understanding of the embodiments discussed herein and the various ways in which they can be practiced. By convention, the various features in the drawings discussed below are not necessarily drawn to scale. The dimensions of the various features and elements in the drawings may be enlarged or reduced to more clearly illustrate embodiments of this disclosure.

[0021] Figure 1 This is a schematic diagram of a portion of an example furnace assembly for heating feed to provide thermal reactor effluent according to an embodiment of this disclosure;

[0022] Figure 2A This is a partial schematic cross-sectional side view of an example heat recovery assembly according to an embodiment of this disclosure;

[0023] Figure 2B It is based on the implementation scheme of this disclosure. Figure 2A The example heat recovery assembly shown is a partial schematic cross-sectional end view taken along line BB.

[0024] Figure 3A This is a partial schematic perspective view of another example heat recovery assembly according to an embodiment of this disclosure;

[0025] Figure 3B It is based on the implementation scheme disclosed herein. Figure 3A The example heat recovery assembly shown is a partial schematic cross-sectional end view taken along line BB.

[0026] Figure 4A This is a schematic cross-sectional view of an example inner tube including example circular protrusions on the inner surface of the inner tube according to an embodiment of the present disclosure;

[0027] Figure 4BThis is a schematic cross-sectional view of another example inner tube, including example rectangular protrusions on the inner surface of the inner tube, according to an embodiment of this disclosure.

[0028] Figure 5 This is a block diagram of an example method for producing olefins according to an embodiment of this disclosure.

[0029] Figure 6A This is a block diagram of a single-stage implementation of an exemplary feed-effect exchanger.

[0030] Figure 6B This is a block diagram of two exemplary implementations of a feed-effect exchanger. Detailed Implementation

[0031] The accompanying drawings include the same figures indicating the same components in multiple views. The following description is provided as an enabling teaching of exemplary embodiments, and those skilled in the art will recognize that many changes can be made to the described embodiments. It will also be apparent to those skilled in the art that some desired benefits of the described embodiments can be obtained by selecting some features of the embodiments without utilizing others. Therefore, those skilled in the art will recognize that many modifications and adaptations to the described embodiments are possible and, in some cases, even desirable. Thus, the following description is provided as an illustration of the principles of the embodiments and not as a limitation thereof.

[0032] The wording and terminology used herein are for descriptive purposes and should not be considered restrictive. As used herein, the term “a plurality” means two or more items or components. The terms “comprising,” “including,” “carrying,” “having,” “containing,” and “involving,” whether in the drafted specification or claims, are open-ended terms, meaning “including, but not limited to,” unless otherwise stated. Therefore, the use of such terms is intended to include the items listed thereafter, their equivalents, and additional items. The transitional phrases “consisting of…” and “consisting substantially of…” are respectively closed or semi-closed transitional phrases relating to any claim. The use of sequential terms such as “first,” “second,” “third,” etc., in claims to modify the claim elements themselves does not imply any priority, precedence, or order of action of one claim element relative to another claim element, but is merely used as labels to distinguish one claim element with a particular name from another element with the same name (but for the use of sequential terms, to differentiate claim elements).

[0033] Furthermore, although references may be made in this document to quantitative measurements, values, geometric relationships, etc., unless otherwise stated, any one or more of these, if not all, may be absolute or approximate to account for possible acceptable variations, such as those caused by manufacturing or engineering tolerances.

[0034] The applicant has identified a preferred operating window / scheme to prevent undesirable performance losses in the heat recovery unit due to feed pre-cracking and / or effluent coking mechanisms.

[0035] Figure 1 An example furnace assembly 10 for heating feed to provide thermal reactor effluent according to an embodiment of this disclosure is illustrated schematically. In some embodiments, furnace assembly 10 can be used for the production of olefins from hydrocarbons. Figure 1 As shown, furnace assembly 10 may include an electric furnace 20 and a heat recovery assembly 30. As used herein, the phrase "thermal reactor effluent" refers to reactor effluent downstream of furnace 20 and beginning to cool from the temperature at which it exits furnace 20. In some embodiments, heat recovery assembly 30 may include one or more stages, such as a first stage 31a, a second stage 31b, and a third stage 31c, for example, as... Figure 1As shown. As used herein, the term stage refers to a discrete portion of a heat recovery assembly configured to allow indirect thermal contact between the feed and the thermal reactor effluent, for example, using a heat transfer enhancement structure method described in more detail below. In some embodiments including more than one stage, the stages may have substantially the same structural configuration, and in some embodiments including more than one stage, one or more stages may have a structural configuration different from the other stages. In some embodiments including more than one stage, the heat recovery assembly may include two or more segments, each segment including one or more stages. Within a segment including more than one stage, the feed flows sequentially through these stages, defining an overall flow direction that may be co-current or counter-current with the flow direction of the thermal reactor effluent. Each segment may have corresponding inlets and outlets for the feed and may handle the same or different (partial) feeds. Within the same heat recovery assembly, some segments may have a co-current configuration while others may have a counter-current configuration. When the heat recovery assembly has more than one segment, these segments may be implemented in a single device or in different devices. For example, the first section can be implemented as a coaxial heat exchanger to heat the hydrocarbon feed, using a heat transfer enhancement structure described in more detail below; the second section can be implemented as a steam-generating quench waste heat boiler; and the third section can be implemented as a conventional countercurrent heat exchanger to heat the hydrocarbon feed. As used herein, the terms upstream and downstream should be understood relative to the flow direction of the thermal reactor effluent; that is, if the first section cools the thermal reactor effluent and the second section further cools the partially cooled reactor effluent, then the second section is downstream of the first section, regardless of the configuration and direction of the coolant flow. As used herein, co-current and countercurrent should be understood relative to the flow direction of the thermal reactor effluent; that is, a section in which the overall flow direction of the coolant is opposite to that of the thermal reactor effluent should be considered a countercurrent section.

[0036] In some embodiments, furnace 20 may be configured to receive feed and heat the feed to a reaction temperature to provide a thermal reactor effluent. In some embodiments, the feed and / or effluent may be in the form of a liquid, a gas, or a combination thereof. For example, furnace 20 may be an electric cracking furnace and the feed may be or include hydrocarbons for cracking in furnace 20 to provide a thermal reactor effluent containing cracked hydrocarbons, said effluent being, for example, at least partially gaseous (e.g., completely gaseous). In some embodiments, furnace 20 may be configured to heat the feed to a cracking temperature to break down the hydrocarbons into desired products that can be discharged from furnace 20 as a thermal reactor effluent. The feed may include, for example, ethane, propane, butane, condensate, light naphtha, heavy naphtha, gas oil, pyrolysis oil, materials derived from processing refinery streams, Fischer-Tropsch products, plastic waste, or biofeed. The feed may additionally include steam. In some embodiments, furnace 20 may be configured to receive feed into one or more reaction zones or chambers 25 (e.g., pyrolysis tubes or pyrolysis coils) via reactor feed line 22, and discharge hot reactor effluent via reactor effluent line 28. In some embodiments, furnace 20 may be electrically heated to the pyrolysis temperature, for example, such that the feed flows substantially continuously into one or more reaction chambers 25 via reactor feed line 22, and flows out of one or more reaction chambers 25 as hot reactor effluent via reactor effluent line 28. One or more reaction chambers 25 may be heated directly or indirectly by electricity. To improve the efficiency of furnace 20, the feed may be preheated to a temperature closer to the feed's pyrolysis temperature before entering one or more reaction chambers 25 (e.g., upstream of the reaction chambers 25). Reactor feed line 22 and reactor effluent line 28 may be configured to pass through additional equipment, such as... Figure 1 Heat transfer devices not depicted in the text.

[0037] In some embodiments, the heat recovery assembly 30 may be or include a gas-to-gas energy recovery device or a heat exchanger. The heat recovery assembly 30 may be configured to receive hot reactor effluent from one or more reaction chambers 25 and quench the hot reactor effluent to a quench temperature to retain the desired product within the reactor effluent and / or prevent side reactions from occurring within the reactor effluent, for example, when the hot reactor effluent is cooled. In some embodiments, a single heat recovery assembly 30 may receive hot reactor effluent from multiple reaction chambers 25. In some embodiments, a single reaction chamber 25 may supply hot reactor effluent to multiple heat recovery assemblies 30. The ratio between the number of reaction chambers 25 and the number of heat recovery assemblies 30 may be from 0.1 to 10, for example, from 0.5 to 2.

[0038] The thermal reactor effluent enters the heat recovery assembly 30 at a temperature of at least 550°C, at least 575°C, at least 600°C, at least 610°C, at least 620°C, at least 625°C, at least 630°C, at least 640°C, at least 650°C, at least 700°C, at least 750°C, at least 800°C, or at least 850°C. To quench the thermal reactor effluent, the heat recovery assembly 30 may utilize the feed as a cooling medium, for example, before the feed enters the reaction chamber 25 (e.g., upstream of the reaction chamber 25). By cooling the thermal reactor effluent within the heat recovery assembly 30, the feed can be preheated to a temperature closer to its pyrolysis temperature (e.g., to at least 350°C, at least 375°C, at least 400°C, at least 450°C, at least 500°C, or at least 550°C). In some embodiments, the heat recovery assembly 30 may be configured to preheat the feed to above the pyrolysis temperature, for example, to cause pyrolysis to begin in the heat recovery assembly 30, such as when the feed is preheated to a temperature above 550°C to 650°C. As used herein, "quenched reactor effluent" refers to reactor effluent that has passed through the heat recovery assembly 30. In some embodiments, the hot reactor effluent may be additionally partially cooled or quenched before or after passing through the heat recovery assembly 30. In some embodiments, the preheated feed may also be heated (e.g., by a flame heater or an electric heater) before entering the reaction chamber.

[0039] In some implementations, the heat recovery assembly 30 can be configured to recover heat from the thermal reactor effluent to heat the feed to the electric reactor. (See the section on...) Figures 2A to 3BAs explained, in some embodiments, the heat recovery assembly 30 may include an inner tube 34 and an outer tube 40. The inner tube 34 may include a first inlet configured to receive thermal reactor effluent from the electric reactor. The outer tube 40 may be disposed around the inner tube 34 to surround an annular space 44 surrounding the inner tube 34. Although the terms “annular space” and “ring-shaped” (and their derivatives) are used herein, “annular space 44” may be defined by an inner circle and an outer circle, or may not be defined by an inner circle and an outer circle to create an annular cross-section having an inner circular boundary and an outer circular boundary. In some embodiments, the inner and / or outer boundaries of the cross-section may have shapes other than circular, such as triangles, rectangles, polygons, ellipses, ovals, etc. In some embodiments, the central axis of the inner tube may coincide with the central axis of the outer tube. In some embodiments, the central axis of the inner tube may be offset from the central axis of the outer tube. The term “annular” (and its derivatives) may be interpreted similarly. The annular space 44 may include a second inlet configured to receive feed from the electric reactor. The annular space 44 can be configured to use the feed for the electric reactor as a cooling medium to recover heat energy from the thermal reactor effluent before supplying the feed to the electric reactor. The annular space 44 can be configured to enhance heat transfer from the thermal reactor effluent to the feed. In some embodiments, the thermal reactor effluent can reach the first inlet via an effluent gas inlet chamber or other connector. In some embodiments, cooling can be supplied to the feed gas inlet chamber or other connector. In some embodiments, the effluent gas inlet chamber can connect one or more reaction chambers to one or more inner tubes. In some embodiments, a header can be provided to connect the feed to more than one annular space 44. In some embodiments, a header can be used to collect cooled cracked gas from more than one inner tube 34. In some embodiments, heated feed from more than one annular space 44 can be combined via a header. In some embodiments, multiple annular spaces 44 can be included in a single mechanical device that can receive hot effluent from multiple cracked coils and cold feed from the feed header via gas inlet chambers or other connectors.

[0040] In some applications, the residence time and / or pressure drop of the reactor effluent in the heat recovery assembly 30 can affect the processes and / or products achieved through the heating process in the furnace assembly 10. Both residence time and pressure drop can affect the ethylene selectivity of the products produced by the furnace assembly 10 as the thermal reactor effluent passes through the heat recovery assembly 30. Residence time can be defined as the time the thermal reactor effluent remains above its cracking temperature, for example, above 550°C to 650°C. In some embodiments, residence time and pressure drop can be balanced during the quenching of the thermal reactor effluent, for example, to maintain the ethylene selectivity of the reactor effluent. For example, an increased pressure drop in the heat recovery assembly can affect selectivity because the increased pressure in the cracking coil of the furnace assembly 10 alters the selectivity of the cracking reaction in the furnace assembly 10. Regarding residence time, a longer residence time can allow additional side reactions to occur in the heat recovery assembly 30.

[0041] In some embodiments, the heat recovery assembly 30 may be configured to use the feed from furnace 20 as a cooling medium for the thermal reactor effluent received from furnace 20, for example, and to preheat the feed through the thermal reactor effluent before it enters reaction chamber 25. For example, as Figure 1 As shown, the heat recovery unit 30 can receive feed through the cold feed line 32 and provide preheated feed to the reaction chamber 25 through the reactor feed line 22. The heat recovery unit 30 can receive hot reactor effluent from the reactor effluent line 28 and provide quenched reactor effluent to the quench effluent line 38.

[0042] In some embodiments, the heat recovery assembly 30 may be configured to operate as a gas-to-gas heat exchanger to exchange heat from the thermal reactor effluent to the feed. As a result of heat exchange between gases, it is more difficult to quench the reactor effluent during the desired residence time compared to a liquid-to-gas heat exchanger (e.g., a steam-generating heat exchanger using boiling water as a relatively low-temperature cooling medium, typically used with a gas-fired pyrolysis furnace), due to, for example, the typically lower heat transfer coefficient in a gas-to-gas heat exchanger and the lower temperature difference between the hot and cold fluids. Therefore, additional design features for the heat recovery assembly 30 may be desired, as described in some of the following exemplary embodiments.

[0043] Reference Figure 2A and Figure 2B The figure shows a portion of an example heat recovery assembly 30 with a sleeve design, wherein the effluent from the thermal reactor flows through an inner tube 34 (e.g., a central tube), and the feed flows through an annular space 44 defined at least partially by the inner tube 34 and the outer tube 40. As shown, the inner tube 34 is arranged around the central axis of the heat recovery assembly 30. In some embodiments, the inner tube 34 may be arranged around or off-center from the central axis of the heat recovery assembly 30.

[0044] The heat recovery assembly 30 can be a co-current or counter-current heat exchanger (e.g., as shown in the figure), in which the thermal reactor effluent flows through the heat recovery assembly 30 in a first direction and the feed flows through the heat recovery assembly 30 in a second direction opposite to the first direction. In some embodiments, the inner tube 34 may include an inlet 33 and an outlet 35, wherein the thermal reactor effluent enters through the inlet 33, flows through the inner tube 34, and exits through the outlet 35. The annular space 44 may include an inlet 43 and an outlet 45, wherein the feed enters through the inlet 43, flows through the annular space 44, and exits as preheated feed through the outlet 45. In such an embodiment, the thermal reactor effluent is at its highest temperature before being cooled by preheating the feed through heat transfer, enters the heat recovery assembly 30 at the inlet 33 near the feed point, at which point the feed is at its highest temperature after being heated by the reactor effluent, and exits the heat recovery assembly 30 as preheated feed through the outlet 45. The reactor effluent (e.g., quenched reactor effluent) is at its lowest temperature after heating the feed and exits the heat recovery assembly 30 as quenched reactor effluent at outlet 35 near the feed point, where the feed is at its lowest temperature before being heated by the reactor effluent, and enters the heat recovery assembly 30 through inlet 43. In some such embodiments, the heated reactor effluent enters the heat recovery assembly 30 at its highest temperature, where the feed exits the heat recovery assembly 30 at its highest temperature, and the reactor effluent exits the heat recovery assembly 30 at its lowest temperature, where the feed enters the heat recovery assembly 30 at its lowest temperature. In some embodiments, the heat recovery assembly 30 may be a co-current heat exchanger, wherein the reactor effluent and feed flow in the same direction within the heat recovery assembly 30. In some embodiments, if the heat recovery assembly 30 consists of more than one section, some sections may be co-current and others may be counter-current.

[0045] In some embodiments, the inner tube 34 may be or include a bare tube or a smooth tube with a smooth inner surface. In some embodiments, the inner tube 34 may include a heat transfer enhancement structure, such as a turbulence-promoting structure or a structure that increases the surface area of ​​the inner tube 34. For example, the inner tube 34 may include a velocity bar or other turbulence-promoting structure. In some embodiments, the inner tube 34 may include fins (e.g., straight fins and / or threaded fins, rectangular and / or circular cross-sections) or other surfaces to increase the surface area in contact with the reactor effluent flowing through the inner tube 34. Such heat transfer enhancement structures within the inner tube 34 can reduce the residence time of the reactor effluent. Heat transfer enhancement structures can increase the pressure drop within the reactor effluent. In some embodiments, including heat transfer enhancement structures within the inner tube 34 may be balanced, for example, to reduce the pressure drop that may be caused by the heat transfer enhancement structures. In some embodiments, fouling may be expected, making frequent cleaning of the inner tube 34 potentially necessary. In such embodiments, the inner tube 34 may be straight or bare to facilitate cleaning. In a particular embodiment, the section of the inner tube 34 may be exposed, and the section of the inner tube 34 may include heat transfer enhancement structures, such as the aforementioned turbulence-promoting structures and / or area-increasing structural features.

[0046] In some embodiments, the annular space 44 may include turbulence-enhancing structures, such as, for example, fins, artificial roughening structures, corrugations / grooves, pin fins, and / or indentations. Such structures can increase the heat transfer rate from the outer surface of the inner tube 34 and / or increase the pressure drop of the feed through the annular space 44. Such structures can be used alone as heat transfer enhancement structures or in combination with other heat transfer enhancement structures, such as the plate-type impact structures and flute-type impact structures described herein.

[0047] In some embodiments, the annular space 44 may include a high-shear-induced geometry configured to promote high-shear flow, for example, generated by a feed flow at a high speed, such as greater than 50 m / s, or greater than 60 m / s, or greater than 70 m / s, or greater than 80 m / s. In some embodiments, the direction of the high-shear feed flow through the annular space is substantially parallel to the inner tube. In some embodiments, the high-shear-induced geometry may include an outer tube configured such that the distance between the outer surface of the inner tube 34 and the inner surface of the outer tube 40 is 10 mm or less, 8 mm or less, 6 mm or less, or 4 mm or less. The high shear rate can act as a heat transfer enhancement structure by promoting a high heat transfer rate from the flowing feed to the outer surface of the inner tube 34.

[0048] In some embodiments, the heat transfer enhancement structure through impingement can refer to the flow of fluid through the outer tube, whose average direction from inlet to outlet can be substantially parallel to the inner tube, intentionally oriented towards the inner tube, for example, using geometric features introduced into the annular space. In some embodiments, this oriented (impingement) flow can be, for example, perpendicular to the inner tube, or directed towards the inner tube at an angle greater than thirty degrees relative to the axis of the inner tube, while its velocity can be relatively greater than the apparent velocity of the fluid in the outer tube (e.g., the volumetric flow rate of the fluid in the outer tube divided by the area of ​​the annular cross-section between the inner and outer tubes). In some embodiments, the geometric features promoting impingement can include, for example, nozzles and / or openings toward the inner tube, and / or obstructions placed in the flow path, which can redirect the fluid more directly toward the outer surface of the inner tube from a direction more parallel to the inner tube. These example features can be implemented in a periodic manner, for example, creating impingement zones that appear at circumferential intervals along the length and / or circumference of the inner tube. The applicant has found that introducing such impingement features can increase the heat transfer rate relative to the heat transfer rate obtained by flowing parallel through the outer tube. Furthermore, the applicant has found that, for a suitable level of heat transfer enhancement, the ratio of the impinging flow velocity to the apparent velocity can be greater than 2, greater than 5, or greater than 10. In the case of a nozzle or opening, the impinging flow velocity can be approximated as the volumetric flow rate divided by the total flow area defined by the nozzle or opening, through which the flow is directed. Additionally, it has been found that the heat transfer enhancement structure is more suitable when the distance between the impinging feature (e.g., between the nozzle or opening 54 and the inner tube) and the inner tube is approximately to about twelve times the diameter of the nozzle or opening 54, approximately ten times the diameter, or approximately two to about eight times the diameter. Examples of impinging features may include plate-type impinging structures and / or flute-type impinging structures. In some embodiments, at least one heat transfer enhancement structure in the first stage may be the same as or different from at least one heat transfer enhancement structure in the second stage.

[0049] Now refer to Figure 2A , Figure 2B , Figure 3A and Figure 3B The annular space 44 of the heat recovery component 30 (see Figure 2A and Figure 2B The heat recovery assembly 30 may include one or more structures to facilitate heat transfer from the reactor effluent in the inner tube 34 to the feed in the annular space 44 of the heat recovery assembly 30. For example, the heat recovery assembly 30 may include a plate-shaped impact structure 50 in the annular space 44 of the heat recovery assembly 30, such as... Figure 2A and 2B As shown, and / or the heat recovery assembly 30 may be included in the annular space 44 of the heat recovery assembly 30 (see also...). Figure 3B The flute-shaped impact structure 60 in ) (see also) Figure 3A ).

[0050] Special reference Figure 2A and Figure 2B The plate-shaped impact structure 50 may include a cooling medium (e.g., feed) entering a first channel 52 via a staged inlet 43, which may be spaced apart from the inner tube 34, for example, on the outer side or outer circumference of the annular space 44 of the heat recovery assembly 30. The cooling medium exits the first channel via one or more nozzles or openings 54 in the walls 55 into a second channel 56 that contacts the inner tube 34. For example, the first channel 52 may terminate at a downstream end 58, such that the cooling medium can be forced into the second channel 56 to flow through the annular space 44 and exit through a staged outlet 45 at the downstream end of the second channel 56. The walls 55 separate the first channel 52 from the second channel 56. The heat recovery assembly 30 may include one or more plate-shaped impact structures 50 arranged along its length. Figure 2A and Figure 2B Each plate-shaped impact structure 50 shown can be considered as a plate-shaped impact structure stage, wherein the heat recovery assembly 30 includes one or more plate-shaped impact structure stages connected in series or in parallel with each other.

[0051] In some embodiments, one or more nozzles or openings 54 may have a circular cross-section. In some such embodiments, the diameter of one or more nozzles or openings 54 may be from about 1 mm to about 15 mm, for example, from about 2 mm to about 10 mm, from about 3 mm to about 8 mm, or from about 4 mm to about 7 mm. In nozzles or openings 54 that do not have a circular cross-section, the area of ​​the cross-section of the nozzle or opening 54 may substantially correspond to the area of ​​the nozzle or opening 54 having a circular cross-section. In some embodiments, the nozzles or openings 54 may be circumferentially aligned at different points along the longitudinal length of the wall 55, or they may be circumferentially staggered along the longitudinal length of the wall, for example, in a spiral manner. In some embodiments, the wall 55 may be spaced apart from the outer surface of the inner tube 34 by a distance, for example, when the nozzles or openings 54 have a circular cross-section, from a distance approximately equal to the diameter of the nozzle or opening 54 to about twelve times the diameter of the nozzle or opening 54, or from about the diameter to about ten times the diameter, or from about two times the diameter to about eight times the diameter.

[0052] In some embodiments, the nozzles or openings 54 may be spaced apart circumferentially around the wall 55. For example, at a given point along the longitudinal length of the wall 55, the wall may include, for example, one to fifteen nozzles or openings 54, which may depend at least in part on the size of the inner tube 34; for example, a relatively larger inner tube 34 has a relatively larger number of nozzles or openings 54. In some embodiments, the nozzles or openings 54 may be circumferentially spaced around the inner tube 34, for example, such that the spacing is equal to π (i.e., 3.14159) multiplied by the sum of the diameter of the outer surface of the inner tube 34 and twice the distance from the nozzle or opening 54 to the outer surface of the inner tube 34, all divided by the number of nozzles or openings 54 around the circumference. In some embodiments, the nozzles or openings 54 may be substantially equally spaced apart from each other circumferentially along the longitudinal length of the wall 55 and / or around the wall 55.

[0053] Reference Figure 3A and 3B The whistle-shaped impact structure 60 may include a cooling medium (e.g., feed) entering one or more whistle-shaped tubes or outer tubes 62 and defining a chamber 66 surrounding an inner tube 34. In some embodiments, the chamber 66 may typically define an annular space, such as, for example... Figure 2A and Figure 2B The annular space 44 is shown. The outer tube 62 may include a stage inlet 43 and may include one or more nozzles or openings 64 configured to allow cooling medium to flow from the outer tube 62 into the chamber 66, for example, such that the cooling medium contacts the inner tube 34. In some embodiments, one or more nozzles or openings 64 may point towards the outer surface of the inner tube 34, for example, as shown. Figure 3B As shown. Chamber 66 may be defined between a first or upstream divider 65 and a second or downstream divider 67. The upstream divider 65 may include an opening allowing cooling medium to enter the outer tube 62. The downstream divider 67 may terminate the downstream end of each outer tube 62 and may include an outlet defined therein, the outlet allowing cooling medium to exit chamber 66 and flow into another set of outer tubes 62 or exit the heat recovery assembly 30. The heat recovery assembly 30 may include one or more flute-shaped impact structures 60 arranged along its length. Figure 3A and Figure 3B As shown, each flute-shaped impact structure 60 can be considered as a flute-shaped impact structure stage, wherein the heat recovery component 30 includes one or more flute-shaped impact structures connected in series or in parallel with each other.

[0054] In some embodiments, one or more nozzles or openings 64 may have a circular cross-section. In some such embodiments, the diameter of one or more nozzles or openings 64 may be from about 1 mm to about 15 mm, for example, from about 2 mm to about 10 mm, from about 3 mm to about 8 mm, or from about 4 mm to about 7 mm. In nozzles or openings 64 that do not have a circular cross-section, the area of ​​the cross-section of the nozzle or opening 64 may substantially correspond to the area of ​​a nozzle or opening 64 having a circular cross-section. In some embodiments, the nozzles or openings 64 may be circumferentially aligned relative to a corresponding outer tube 62 such that fluid passing through each of the nozzles or openings 64 is directed to the outer surface of the inner tube 34, for example, at an angle of about ninety degrees relative to the outer surface of the inner tube 34. In some embodiments, one or more nozzles or openings 64 may be circumferentially oriented relative to their respective outer tubes 62, such that the fluid through the nozzles or openings 64 forms a non-perpendicular angle with respect to the outer surface of the inner tube 34, for example, about 10 degrees to about 80 degrees, 20 degrees to about 80 degrees, 30 degrees to about 80 degrees, or about 45 degrees to about 80 degrees. In some embodiments, the nozzles or openings 64 may be located at different points and circumferentially aligned along the length of the outer tube 62 (e.g., in the direction along the longitudinal axis). In some embodiments, the nozzles or openings 64 may be spaced apart from the outer surface of the inner tube 34 by a distance, for example, when the nozzles or openings 64 have a circular cross-section, ranging from a distance approximately equal to the diameter of the nozzle or opening 64 to about twelve times the diameter of the nozzle or opening 64, or from about the diameter to about ten times the diameter, or from about two times the diameter to about eight times the diameter.

[0055] In some embodiments, each outer tube 62 may include a single nozzle or opening 64 at each of a plurality of locations along the length of the outer tube 62. In some embodiments, each outer tube 62 may include a plurality of nozzles or openings 64, which may be one to fifteen nozzles or openings 64, one to ten nozzles or openings 64, one to five nozzles or openings 64 (e.g., four nozzles or openings 64), or five to ten nozzles or openings 64. In some embodiments, the distance between nozzles or openings 64 on a given outer tube 62 may be defined, for example, such that the distance between adjacent nozzles or openings 64 divided by the diameter of the nozzle or opening 64 is greater than or equal to 1 and less than or equal to 20. The number of outer tubes 62 in a stage may be one to twelve, or two to six.

[0056] The heat recovery assembly 30 may have a modular design with multiple stages along its length. For example, the heat recovery assembly 30 may include one or more plate-shaped impact structure stages 50 and one or more whistle-shaped impact structure stages 60. In some embodiments, the heat recovery assembly 30 may include only the plate-shaped impact structure stage 50 or only the whistle-shaped impact structure stage 60. In a particular embodiment, the heat recovery assembly 30 may include the plate-shaped impact structure stage 50, the whistle-shaped impact structure stage 60, and a turbulence-enhancing structure (TP) feature or TP stage.

[0057] The heat recovery assembly 30 can be used in conjunction with a conventional gas-liquid vapor-generating TLE. For example, a conventional TLE can be used for initial quenching of the reactor effluent, followed by the heat recovery assembly 30, provided that the temperature of the reactor effluent entering the heat recovery assembly 30 is at least 550°C, at least 575°C, at least 600°C, at least 610°C, at least 620°C, at least 630°C, at least 640°C, at least 650°C, at least 700°C, at least 750°C, or at least 800°C, or at least 850°C. Alternatively, a conventional TLE can follow the heat recovery assembly 30, for example, if the heat recovery assembly 30 preheats the feed to at least 350°C, at least 375°C, at least 400°C, at least 425°C, at least 450°C, at least 475°C, at least 500°C, at least 525°C, at least 550°C, at least 600°C, at least 625°C, or at least 650°C. For example, furnace assembly 10 may include a conventional TLE before or after heat recovery assembly 30. For example, reactor effluent line 28 and / or quench effluent line 38 may include a conventional TLE. In some embodiments, a conventional gas-liquid generating steam TLE may be part of the same assembly as heat recovery assembly 30. In some embodiments, according to some examples, heat recovery assembly 30 may be combined with a superheated steam stream.

[0058] The characteristics of the stages of the heat recovery assembly 30 can be adjusted, for example, according to the location of the stages within the heat recovery assembly 30. For example, when the heat recovery assembly 30 includes a plate-shaped impact structure stage 50, the size and dimensions of the channels 52 and / or 56, the nozzles or openings 54, and / or the length of the plate-shaped impact structure stage 50 can be configured to optimize heat transfer along the conditions at that location of the heat recovery assembly 30. Thus, the radial height of the first channel 56 of the stage 50 at a first location of the heat recovery assembly 30 can be greater than the radial height of the first channel 56 of the stage 50 at a second location of the heat recovery assembly 30. Similarly, the diameter of the nozzle or opening 54 of the stage 50 at the first location can be smaller than the diameter of the nozzle or opening 54 of the stage 50 at the second location. In some embodiments, the radial heights can remain substantially equal between one or more stages. In some embodiments, when the heat recovery assembly 30 includes a flute-shaped impact structure stage 60, the diameter of the outer tube 62, the size and / or number of nozzles 64, and / or the length and dimensions of the flute-shaped impact structure stage 60 can be configured to optimize heat transfer along the conditions at that location of the heat recovery assembly 30. In some embodiments, the number of nozzles or openings 54 from stage to stage can be higher, lower, or the same. In some embodiments, the number of rows of nozzles or openings 54 can vary with each stage. The conditions along the heat recovery assembly 30 can include the temperature of the reactor effluent, the temperature of the feed, the inlet and / or outlet pressure of the reactor effluent, the inlet and / or outlet pressure of the feed, the pressure drop of the reactor effluent along the pressure length of the assembly, the pressure drop of the feed along the length of the heat recovery assembly 30, the temperature difference between the feed and the reactor effluent, and the velocity of the reactor effluent and / or the feed.

[0059] As described above, the heat recovery assembly 30 may include segments connected in series with each other. The heat recovery assembly 30 may enable or disable one or more of these segments based on, for example, the temperature of the hot reactor effluent entering the heat recovery assembly 30, the temperature of the quenched reactor effluent leaving the heat recovery assembly 30, the temperature of the feed entering the heat recovery assembly 30, and / or the temperature of the feed leaving the heat recovery assembly 30. In some embodiments, when a segment is enabled, the feed may flow through the enabled segment, and when a segment is disabled, the feed is prevented from flowing through the disabled segment. For example, when the quenched reactor effluent leaving the heat recovery assembly 30 is above a desired temperature, the heat recovery assembly 30 may activate one or more additional segments to cause the temperature of the quenched reactor effluent leaving the heat recovery assembly 30 to decrease towards the desired temperature, and / or when the quenched reactor effluent leaving the heat recovery assembly 30 is below a desired temperature, the heat recovery assembly 30 may deactivate one or more segments to cause the temperature of the quenched reactor effluent leaving the heat recovery assembly 30 to increase towards the desired temperature. In some embodiments, the heat recovery assembly 30 may include one or more controllers configured to control the operation of one or more segments, for example, as those skilled in the art will understand. For example, the heat recovery assembly 30 may include multiple temperature sensors, pressure sensors, flow sensors, etc., communicating with the controller, and the controller may use control logic in the form of computer software and / or hardware programs to make control decisions associated with controlling the operation of the heat recovery assembly 30, for example, the heat recovery assembly includes one or more segments. In some embodiments, the heat recovery assembly 30 may include valves associated with pipelines and / or conduits, and a controller may transmit control signals, at least in part, based on control decisions, to actuators associated with the valves to control the flow of fluids (e.g., gases and / or liquids) and / or heat, and the actuators may operate according to the transmitted control signals to operate components of the heat recovery assembly 30. In some examples, the controller may be supplemented or replaced by an operator who manually controls the heat recovery assembly 30, at least in part, to meet desired performance parameters, at least in part, based on efficiency considerations.

[0060] In some embodiments, the heat recovery assembly 30 may be configured to quench the hot reactor effluent in a manner consistent with other quenching devices for a gas-fired pyrolysis furnace in terms of residence time and / or pressure drop. In some embodiments, the heat recovery assembly 30 may be adjusted or optimized to be substantially equivalent to or improved relative to other types of quenching devices. For example, the heat recovery assembly 30 may be configured such that the residence time, measured by time within the heat recovery assembly 30, is less than 100 milliseconds (ms), e.g., less than 90 ms or less than 85 ms (e.g., less than 83 ms); the pressure drop of the reactor effluent is less than 0.35 bar, e.g., less than 0.30 bar, less than 0.25 bar, or less than 0.20 bar (e.g., less than 0.15 bar); and / or the cooling rate is greater than 2.5 Kelvin (K) / ms, e.g., greater than 3.5 K / ms, greater than 4.0 K / ms, greater than 4.5 K / ms. K / ms, at least 5 K / ms, or at least 5.5 K / ms, for example, wherein the cooling rate can be defined as the inlet temperature of the thermal reactor effluent (in K) minus 923 K, divided by the residence time required to cool from the temperature of the thermal reactor effluent to 923 K, unless the inlet temperature of the thermal reactor effluent (in K) is less than 923 K or the temperature of the cooled reactor effluent is greater than 923 K, in which case the cooling rate can be defined as the inlet temperature of the thermal reactor effluent (in K) minus the temperature of the cooled reactor effluent leaving the heat recovery unit, divided by the residence time of the effluent in the unit. In addition to effluent-side pressure drop and cooling rate performance, the heat recovery assembly 30 can be configured to achieve a pressure drop of 2 to 15 bar for the feed, such as 2.5 to 10 bar, 3 to 8 bar, 3 to 10 bar, or 4 to 9 bar (e.g., 5 to 8 bar), for example, to manage the amount of pressurization required before the feed enters the heat recovery assembly 30, while promoting a sufficiently high heat transfer rate from the inner tube to the feed.

[0061] In some embodiments, the heat recovery assembly 30 may be configured and / or controlled to quench the hot reactor effluent and preheat the hydrocarbon feed to the reactor feed temperature. For example, the heat recovery assembly 30 may be configured with one or more stages to transfer heat from the hot reactor effluent to the hydrocarbon feed, which may not be preheated, or at least not sufficiently preheated, to be supplied to the cracking furnace for cracking. In some embodiments, the stages may have a sleeve design, with the hot reactor effluent flowing through an inner tube and the hydrocarbon feed flowing through an outer tube. The outer tube may include a stage with one or more heat transfer enhancement structures, such as, for example, plate-type impact structures, flute-type impact structures, one or more turbulence-promoting structural features associated with the outer and / or inner tubes, and / or structures with increased surface areas associated with the outer and / or inner tubes. For example, the inner tube may include one or more heat transfer enhancement structures configured to promote heat transfer from the hot reactor effluent. Configuring one or more stages and the inner tube may include selecting stages to achieve desired properties of the hot reactor effluent while transferring heat to the cold feed. For example, stages can be selected to increase or maximize the cooling rate of the thermal reactor effluent, increase or minimize the pressure drop of the thermal reactor effluent, increase or minimize the residence time of the thermal reactor effluent, and / or increase or minimize the pressure drop of the hydrocarbon feed.

[0062] In some embodiments, the heat recovery assembly may include a plurality of inner tubes parallel to each other, wherein each inner tube is disposed within an outer tube, and each outer tube has one or more heat transfer enhancement structures to enhance heat transfer from the inner tubes to the annular space defined within the outer tubes. In some embodiments, the heat recovery assembly may include a plurality of inner tubes parallel to each other, wherein each inner tube is disposed within an outer tube, and wherein the outer tubes and optionally the inner tubes have one or more heat transfer enhancement structures to enhance heat transfer from the inner tubes to the annular space defined within the outer tubes.

[0063] Figure 4A This is a schematic cross-sectional view of an example inner tube 34a, including an example circular protrusion 70a on the inner surface 72a of the inner tube 34a, according to an embodiment of this disclosure. Figure 4A As shown, in some embodiments, the inner surface 72a of the inner tube 34 may include a flow-enhancing structure and / or a structure for increasing the surface area of ​​the inner surface 72a. For example, as Figure 4AAs shown, the inner surface 72a of the inner tube 34a may include one or more circular protrusions 70a. In some embodiments, one or more circular protrusions 70a may extend toward the center of the inner tube 34a and / or may extend longitudinally, partially, intermittently, or completely along the length of the inner tube 34a. In some embodiments, the circular protrusions 70a may be the same or different from each other. In some embodiments, one or more circular protrusions 70a may extend helically along the longitudinal length of the inner tube 34a, for example, to promote vortices in the flow through the inner tube 34a. In some embodiments, the protrusions on the inner surface of the inner tube 34 may have a non-circular configuration. For example, Figure 4B This is a schematic cross-sectional view of another example inner tube 34b, including an example rectangular protrusion 70b on the inner surface 72b of the inner tube 34b, according to an embodiment of the present disclosure. In some embodiments, the inner surface of the inner tube 34 may include a combination of circular and rectangular protrusions. Other configurations of the protrusions may be considered. In some embodiments, the inner tube 34 may include a flow-enhancing structure and / or a structure for increasing the surface area of ​​the outer surface of the inner tube 34. For example, the flow-enhancing structure and / or the structure for increasing the surface area of ​​the outer surface of the inner tube 34 may include protrusions at least similar to the aforementioned protrusions on the inner surface of the inner tube 34. In some embodiments, the structure for increasing the surface area of ​​the outer surface of the inner tube 34 may be configured to enhance the effectiveness of the flow-enhancing structure and / or impact structure features. In some embodiments, the inner surface of the outer tube 40 may include structures that increase the surface area, such as those described above.

[0064] Figure 5 This is a block diagram of an example method 500 for heating a hydrocarbon feedstock, said hydrocarbon feedstock comprising, for example, one or more of ethane, propane, butane, condensate oil, light naphtha, heavy naphtha, gas oil, pyrolysis oil, materials derived from a processing refinery stream, Fischer-Tropsch products, plastic waste, or bio-feed. The hydrocarbon feedstock may additionally include steam. The hydrocarbon feedstock may be preheated and subsequently cracked in an electrically heated cracking furnace, said cracking furnace being able to output cracked hydrocarbons containing olefins. According to some embodiments, example method 500 in… Figure 5 The diagram shows a set of boxes representing sequences of operations in a logic flowchart. The order in which operations are described is not intended to be construed as a limitation, and any number of described blocks can be combined in any order and / or in parallel to implement the method. Furthermore, operations described in one or more boxes can be optional and / or omitted from example method 500, such as those described by boxes 512 and / or 514, although operations described in one or more other boxes may also be omitted from example method 500, or alternatively.

[0065] At 502, example method 500 may include an outer pipe supplying a hydrocarbon feedstock to a heat recovery assembly. For example, the heat recovery system may include any heat recovery system described herein. As described above, the hydrocarbon feedstock may comprise, for example, one or more of ethane, propane, butane, condensate oil, light naphtha, heavy naphtha, gas oil, pyrolysis oil, materials derived from a processing refinery stream, Fischer-Tropsch products, plastic waste, or bio-based materials, or any other hydrocarbon that can be converted to olefins during cracking, and may additionally include steam. In some embodiments, the hydrocarbon feedstock may comprise or be supplied by a hydrocarbon feedstock source.

[0066] At 504, example method 500 may further include heating the hydrocarbon feed in the outer tube of the heat recovery assembly to output a preheated hydrocarbon feed. For example, as explained herein, the hydrocarbon feed may be preheated by heat transfer in a heat recovery system, wherein the heat energy is supplied at least in part by the thermal reactor effluent from the cracking process.

[0067] At 506, example method 500 may also include supplying a preheated hydrocarbon feed to an electrically heated cracking furnace including a reaction zone to heat the preheated hydrocarbon feed, for example, as previously described herein.

[0068] At 508, example method 500 may also include cracking a preheated hydrocarbon feed in the reaction zone to output a thermal reactor effluent containing cracked hydrocarbons and olefins, for example, as previously described herein.

[0069] At 510, example method 500 may further include supplying the thermal reactor effluent to an inner tube of a heat recovery assembly, for example, as previously described herein. For example, in some embodiments, supplying the thermal reactor effluent to the heat recovery assembly may include supplying the thermal reactor effluent to the heat recovery assembly at temperatures of at least 350°C, at least 375°C, at least 400°C, at least 425°C, at least 450°C, at least 475°C, at least 500°C, at least 525°C, at least 550°C, at least 575°C, at least 600°C, at least 625°C, at least 650°C, at least 700°C, at least 750°C, at least 800°C, or at least 850°C.

[0070] At 512, example method 500 may further include supplying additional feed to the outer tube of the heat recovery assembly. In some embodiments, the additional feed may be a continuation of the hydrocarbon feed supplied at 502 from a hydrocarbon feed source, a different hydrocarbon feed, or a hydrocarbon feed supplied with water or steam. The additional feed may be supplied to a different section than the section supplying the hydrocarbon feed. The additional feed may be mixed with the hydrocarbon feed, and the mixed feed exits the heat recovery assembly at a common outlet. The additional feed may pass through a different section than the hydrocarbon feed and exit through a different outlet.

[0071] At 514, example method 500 may further include heating the additional feed by transferring heat from the thermal reactor effluent to the additional hydrocarbon feed via a heat recovery assembly, for example, as previously described herein. Heating the additional feed in the outer tube of the heat recovery assembly to output a preheated feed may include heating the feed to a temperature of at least 350°C, at least 375°C, at least 400°C, at least 425°C, at least 450°C, at least 475°C, at least 500°C, at least 525°C, at least 550°C, at least 575°C, at least 600°C, at least 625°C, or at least 650°C. In some embodiments, supplying the thermal reactor effluent to the inner tube of the heat recovery assembly may include quenching the thermal reactor effluent via heat transfer to the additional hydrocarbon feed, for example, as described herein. In some embodiments, heating the feed in the outer tube of the heat recovery assembly may include preheating the feed via heat transfer from the thermal reactor effluent to the feed. In some implementations, example method 500 may further include enhancing heat transfer to the additional feed by providing heat transfer enhancement structures on one or more of the outer or inner tubes. The heat transfer enhancement structures may include one or more of plate-type impact structures, flute-type impact structures, turbulence-promoting structures, or structures that increase surface area, for example, as previously described herein.

[0072] In embodiments of this disclosure, a method for producing olefins may include one or more cooling steps, characterized by: supplying a hydrocarbon feed to an outer tube of a heat recovery assembly; heating the hydrocarbon feed in the outer tube of the heat recovery assembly to output a preheated hydrocarbon feed; supplying the preheated hydrocarbon feed to an electrically heated cracking furnace including a reaction zone to heat the preheated hydrocarbon feed; cracking the preheated hydrocarbon feed in the reaction zone of the electrically heated cracking furnace using electrically generated heat to output a thermal reactor effluent containing cracked hydrocarbons and olefins; supplying the thermal reactor effluent to an inner tube of the heat recovery assembly; and cooling the thermal reactor effluent in the inner tube of the heat recovery assembly by transferring heat to the hydrocarbon feed; the heat recovery is configured to operate in a preferred operating condition without performance loss due to feed pre-cracking and / or effluent coking.

[0073] In some implementations, the heat recovery assembly may include one or more segments configured in series or parallel, each segment having a counter-current or co-current flow direction. The detailed layout of these segments, and the detailed layout of the stages included within these segments, may be partially or completely different in terms of pipe and annular space layout, heat transfer enhancement structural methods, and heat transfer area enhancement methods.

[0074] In some implementations of heat recovery components, individual stages or sections can be configured and sized such that heat recovery operates within preferred operating conditions without significant or any performance loss. The latter can occur when a fouling layer is formed inside or on the outer surface of the inner tube via chemical and / or physical processes, reducing heat transfer from the inner tube to the annular space. These chemical and physical processes depend heavily on the temperatures inside the inner tube and on the corresponding outer surfaces, in addition to the type and composition of the hydrocarbon feed and the composition of the thermal reactor effluent. Such processes can be feed pre-cracking in the annular space and chemically and physically induced coking on the effluent side. Feed pre-cracking in the annular space defines an upper temperature level that should not be exceeded on the outer surface of the inner tube. An additional upper temperature level that should not be exceeded on the inner surface of the inner tube can be defined by accelerated chemical coking at high surface temperatures. Lower temperature levels that should not be reached on the inner surface of the inner tube can be defined by coking driven by the condensation of heavy components in the effluent. The upper temperature level defined by the risks posed by pre-cracking in the annular space can depend on the type of hydrocarbon feedstock. The upper limit temperature level can be, for example, 530°C, 540°C, 550°C, 600°C, 640°C, 650°C, 660°C, 680°C, 700°C, 720°C, 750°C, etc. For ethane feedstocks, this upper limit temperature level can be 700°C to 720°C. For propane feedstocks, this upper limit temperature level can be 680°C to 700°C. For butane feedstocks, this upper limit temperature level can be 660°C to 680°C. For naphtha feedstocks, this upper limit temperature level can be 640°C to 660°C. For feedstocks heavier than naphtha, this upper limit temperature level can be 540°C to 640°C. The upper limit temperature level, defined by the risk of enhanced chemical coking at the inner surface of the inner tube, can be determined by the effluent reactivity at temperatures above 650°C to 680°C. The lower limit temperature, defined by enhanced coking caused by the condensation of heavy components in the effluent, can be determined by the feed type and pyrolysis conditions. Lower temperature levels can be, for example, 150°C, 160°C, 170°C, 180°C, 200°C, 250°C, 270°C, 300°C, 350°C, etc. For ethane feedstocks, lower temperature levels can be 160°C to 220°C. For propane feedstocks, lower temperature levels can be 170°C to 250°C. For butane feedstocks, lower temperature levels can be 180°C to 270°C. For naphtha feedstocks, lower temperature levels can be 270°C to 320°C. For feedstocks heavier than naphtha, the lower temperature level can be 270°C to 320°C.

[0075] Reference Figure 6AFor single-stage applications of coaxial gas-to-gas exchangers within energy recovery components, reactor effluent can flow counter-currently or concurrently with the feed. The thermal reactor effluent can be supplied to the inner tube, and the feed can be supplied to an outer tube surrounding the inner tube to enclose the annular space. The annular space may include at least one heat transfer enhancement structure to enhance heat transfer from the inner tube to the annular space through impact structures, turbulence-promoting structures, high-shear-induced geometry, or structures that increase surface area.

[0076] Reference Figure 6B For a two-stage application of a coaxial gas-gas exchanger within an energy recovery assembly, the reactor effluent flow direction can be co-current with the feed in the first stage and counter-current with the feed in the second stage. The thermal reactor effluent can be supplied to the inner tube, and the feed can be supplied to an outer tube surrounding the inner tube to enclose the annular space. The annular space can include at least one heat transfer enhancement structure to enhance heat transfer from the inner tube to the annular space through impact structures, turbulence-promoting structures, high-shear-induced geometry, or structures that increase surface area. The applied heat transfer enhancement structure method and detailed layout can be the same or different for both stages.

[0077] In some implementations of the two-section application, the cold feed can enter the coaxial gas-gas exchanger in the upstream co-current section for initial preheating, and can also be heated in the downstream counter-current section. The thermal reactor effluent can be supplied to the inner tube, and the feed can be supplied to an outer tube surrounding the inner tube to enclose the annular space. The annular space can include at least one heat transfer enhancement structure to enhance heat transfer from the inner tube to the annular space through impingement structures, turbulence-promoting structures, high-shear-induced geometry, or structures that increase surface area. The applied heat transfer enhancement structural methods and detailed layout can be the same or different for both sections.

[0078] In some implementations of the two-section application, the cold feed can enter the coaxial gas-gas exchanger in the downstream countercurrent section for initial preheating, and can also be heated in the upstream cocurrent section. The thermal reactor effluent can be supplied to the inner tube, and the feed can be supplied to an outer tube surrounding the inner tube to enclose the annular space. The annular space can include at least one heat transfer enhancement structure to enhance heat transfer from the inner tube to the annular space through impingement structures, turbulence-promoting structures, high-shear-induced geometry, or structures that increase surface area. The applied heat transfer enhancement structural methods and detailed layout can be the same or different for both sections.

[0079] In some implementations, the co-current and counter-current sections can be implemented in a single device. In some implementations, the co-current and counter-current sections can be implemented as different devices; for example, the co-current section can be constructed as a co-tube heat exchanger with heat transfer enhancement structures, and the counter-current section can be constructed as a conventional co-tube or shell-and-tube heat exchanger, or any other suitable conventional heat exchanger design.

[0080] Example

[0081] The heat transfer performance of several heat recovery components including heat transfer enhancement structures according to embodiments of the present invention was compared with that of conventional coaxial gas-to-gas heat exchangers. Conventional heat exchangers are designed for a feed-side pressure drop of 1.76 bar and do not include enhancements in the inner tube or annular space. The heat recovery components according to embodiments of the present disclosure are as follows: (1) a coaxial heat recovery component without heat transfer enhancement structures in the inner tube and having a high shear geometry in the annular space; (2) a heat recovery component including fins in the inner tube and turbulence-promoting structural features in the annular space; (3) a heat recovery component including fins in the inner tube and a plate-shaped impact structure in the annular space; (4) a heat recovery component including fins in the inner tube and a flute-shaped impact structure in the annular space; (5) a heat recovery component including a bare tube (without internal fins) and turbulence-promoting structural features in the annular space; (6) a heat recovery component including a bare tube and a plate-shaped impact structure in the annular space; and (7) a heat recovery component including a bare tube and a flute-shaped impact structure in the annular space.

[0082] For comparison, the boundary conditions for each of the conventional heat exchanger (“Comparative Example”) and the seven example heat recovery assemblies according to embodiments (1 to 7) of this disclosure are established as follows: a hot effluent from the vapor cracking of ethane flows through an inner tube, and a cold feed comprising ethane and vapor flows through an outer tube. The mass flow rate of the hot effluent is 351.6 kg / h, and the outer diameter of the inner tube is 60.3 mm, with a wall thickness of 3.6 mm. The hot effluent and cold feed flow counter-currently with the following inlet and outlet temperatures: T 入，热 Equal to 827℃; T 出，热 Equal to 486℃; T 入，冷 Equal to 236℃; T 出，冷 It equals 650℃.

[0083] Software tools designed for calculating heat transfer are used to evaluate the performance of a conventional heat exchanger (“Comparative Examples”) and seven embodiments according to the present disclosure. Table A below shows the comparative performance based on various metrics explained below. For each metric, the value for each heat recovery component according to embodiments (1 to 7) of the present disclosure is listed relative to the corresponding value for the conventional heat exchanger. The embodiments provided for comparison are effluent cooling rate, heated surface area, pressure drop on the feed and effluent sides of the respective devices, and effluent residence time.

[0084]

[0085] Table A

[0086] As shown in Table A, compared to heat exchangers without such heat transfer enhancement structural features, the heat recovery assembly according to embodiments of this disclosure can provide improved performance, for example, in terms of cooling rate, residence time, effluent pressure drop, and / or required cooling surface area. It will be clear from this disclosure that higher cooling rates and lower required surface area, effluent pressure drop, and effluent residence time are generally advantageous in terms of process performance and / or equipment cost.

[0087] Examples 2(a) to 2(e)

[0088] Heating and cooling profiles for the furnace mixed feed (i.e., steam plus naphtha) and reaction zone effluent (876.8 t / h) were generated using process simulation software tools, along with the energy requirements for the steam cracking reaction. Feasible energy balances with and without heat recovery components were constructed. Based on the plant-wide model, downstream unit operations of the cracking unit have a net heat input requirement of 163 MW. Furthermore, the compressors and pumps were determined to require 151 MW of power, which can be supplied by recovering steam using a 41% condensing turbine or by generating electricity with a 95% efficiency.

[0089] Example 2(a) is a comparative example of generating 120 bar steam in a conventional quench waste heat boiler (TLE). The mixed feed temperature is initially 180°C, as available heat recovery from downstream of the equipment provides this initial temperature. The mixed feed can be heated from 180°C to 300°C using 120 bar steam, since the saturated steam temperature is 324°C. 244 MW of the remaining steam, representing 314 MW of the heat removed from the TLE, is used to supply 163 MW of downstream heating load and 33 MW of mechanical work (i.e., calculated as follows: (244 MW - 163 MW) multiplied by 0.41, equals 33 MW); the remaining 118 MW of work is supplied by 124 MW of electricity (i.e., calculated as follows: 118 divided by 0.95 equals 124 MW). In this Comparative Example 2(a), there is no direct feed-effect heat exchange. The feed is electrically heated from 300°C to 650°C, driving the pyrolysis reaction via electric heating. In this comparative embodiment, in addition to the reaction, preheating requires 682 MW of electricity, resulting in a total power consumption of 806 MW in this comparative embodiment.

[0090] Example 2(b), according to an embodiment of the present disclosure, uses a heat recovery assembly according to the present disclosure to preheat the mixed feed to 450°C via feed-effect heat exchange. Residual cooling of the pyrolysis gas is achieved through steam generation, recovering 145 MW, which can provide energy for all downstream heating except for 18 MW; all mechanical work can be performed electrically, requiring 159 MW of electricity according to this embodiment. The feed is electrically heated from 450°C to 650°C, and the pyrolysis reaction is driven by electric heating. In this embodiment, the total electricity required for the feed, excluding furnace heating, is 583 MW, resulting in a total power consumption of 760 MW.

[0091] In Example 2(c), according to other embodiments of the present disclosure, using a heat recovery assembly according to the present disclosure, the mixed feed can be heated to a relatively high temperature of 550°C. As the heat transferred from the heat recovery assembly to the feed increases, steam generation decreases, and the electricity required for the feed and pyrolysis reaction decreases. In Example 2(c), the feed is electrically heated from 550°C to 650°C, and the pyrolysis reaction is driven by electric heating. In this embodiment, 72 MW of steam is generated, which can be used to supply some of the downstream heating; all mechanical work can be done electrically. In this embodiment, the total electricity required for the feed, excluding furnace heating, is 511 MW, resulting in a total electricity consumption of 760 MW.

[0092] In Example 2(d), according to another embodiment of the present disclosure, feed preheating is increased to 650°C and steam generation is eliminated. A small adjustment to reduce the target hot-side temperature from 400°C to 392°C marks the enthalpy balance point under these feed and target preheating conditions. In Example 2(d), the furnace requires 433 MW of electricity. With no steam generation, downstream heating requires 163 MW of electricity, and mechanical operation requires 159 MW, resulting in a total power consumption of 755 MW.

[0093] In Example 2(e), according to yet another embodiment of the present disclosure, steam is used only when it is used to preheat the mixed feed to 300°C; the remaining preheating is achieved using a coaxial heat exchanger according to the present disclosure. There is no steam outlet. The total electric heating load of the furnace is 433 MW, the same as in Example 2(d), and 250 MW less than the comparative example (i.e., Example 2(a)). In Example 2(e), downstream heating requires 163 MW of electricity, and mechanical work requires 159 MW of electricity, resulting in a total power consumption of 755 MW, or 51 MW less than the comparative example (i.e., Example 2(a)).

[0094] Table B below provides a summary of the heat and electricity usage for Examples 2(a) through 2(e). Comparing Comparative Example 2(a) with Examples 2(b) through 2(e) according to embodiments of the present disclosure shows that when the feed is preheated to a temperature of at least 450°C using the heat recovery assembly according to embodiments of the present disclosure, the total power required to operate the pyrolysis process is reduced. This indicates that the heat recovery assembly conforming to embodiments of the present disclosure can promote increased efficiency, for example, when a sufficiently high level of preheating is achieved. In Examples 2(b) through 2(e), the power demand can remain substantially the same, demonstrating that the heat recovery assembly conforming to embodiments of the present disclosure can be used flexibly without sacrificing efficiency, for example, as long as a minimum level of preheating is achieved.

[0095]

[0096] Table B

[0097] Examples 3(a) to 3(e)

[0098] Examples 3(a) to 3(e) are similar to Examples 2(a) to 2(e) described above, except that the heat exchange sequence on the pyrolysis gas cooling stream is reversed. Steam generation is used for the first part of cooling, and feed-effect heat exchange is used for secondary cooling. The results of Examples 3(a) to 3(e) are summarized in Table C below. As with Examples 2(a) to 2(e), the results show that the total power consumption of the pyrolysis process can be reduced by using a heat recovery assembly consistent with the embodiments of this disclosure. Furthermore, a comparison of the results in Tables B and C shows that, under a wide range of conditions, equivalent power consumption can be achieved by using different sequences of steam generation combined with a heat recovery assembly consistent with the embodiments of this disclosure.

[0099]

[0100] Table C

[0101] Examples 4(a) to 4(c)

[0102] In Examples 4(a) through 4(c), for ethane applications, the feed-effect heat exchanger is used for primary cooling and steam generation for secondary cooling. Examples 4(a) through 4(c) differ in the configuration of the feed-effect heat exchanger. In Example 4(a), the feed-effect heat exchanger comprises one section and is counter-current (i.e., completely counter-current). In Examples 4(b) and 4(c), the feed-effect heat exchanger comprises two sections having a first co-current section and a second counter-current section. In Example 4(b), the cold feed first enters the co-current section and then the counter-current section. In Example 4(c), the cold feed first enters the counter-current section and then the co-current section. In all three Examples 4(a) through 4(c), the reactor effect flow rate and feed flow rate are the same. In all three Examples 4(a) through 4(c), the feed was heated from 230°C to 580°C, and the reactor effluent was cooled from 849°C to 561°C. The configurations of Examples 4(a) through 4(c) were not economically optimized and are presented here primarily to illustrate possible trade-offs between different conceptual configurations. The results of Examples 4(a) through 4(c) are summarized in Table D below. The tube metal temperature for each metric is given in °C, while values ​​for other metrics are listed relative to the corresponding values ​​in Example 4(a). These comparative metrics are heat transfer, tube pressure drop (i.e., effluent pressure drop), effluent residence time, cooling rate, and required heating surface area.

[0103] For Example 4(a), the highest maximum tube surface temperature is expected at the inner tube, while for Example 4(b), the lowest maximum tube surface temperature is expected. Therefore, for the configuration represented by Example 4(a), the risk of coking due to pre-cracking at the outer tube surface and enhanced chemical coking at the inner tube surface is highest. The tube surface temperature obtained in Example 4(c) is between that of Examples 4(a) and 4(b), but closer to that of Example 4(b). At the cold end of the assembly, the lowest tube temperatures are expected in Examples 4(a) and 4(c), while Example 4(b) exhibits a higher tube temperature. For the ethane application examples shown herein, the risk of significant condensation coking is low for any of Examples 4(a) to 4(c).

[0104] Regarding the in-tube effluent pressure drop that affects pyrolysis selectivity, Example 4(a) has the lowest, followed by Example 4(c), with Example 4(b) being significantly higher. The high effluent pressure drop in Example 4(b) is due to the significantly longer tube length compared to Examples 4(a) and 4(c).

[0105] Regarding residence time and cooling rate, both refer to the temperature at which the effluent is cooled to 650°C. For the configuration of Example 4(b), the most favorable values ​​can be seen, which have the highest temperature difference between the effluent and the feed at the effluent inlet.

[0106] Considering the high heat transfer surface required in Example 4(b) and the high high-strength metal temperature seen in Example 4(a), the configuration described in Example 4(c) is likely the best solution for the application shown herein.

[0107]

[0108] Table D

[0109] Examples 5(a) to 5(e)

[0110] In Examples 5(a) through 5(c), for naphtha applications, the feed-effect heat exchanger is used for primary cooling and steam generation for secondary cooling. Examples 5(a) through 5(c) differ in the configuration of the feed-effect heat exchanger. In Example 5(a), the feed-effect heat exchanger comprises one section and is counter-current (i.e., completely counter-current). In Examples 5(b) and 5(c), the feed-effect heat exchanger comprises two sections having a first co-current section and a second counter-current section. In Example 5(b), the cold feed first enters the co-current section and then may enter the counter-current section. In Example 5(c), the cold feed first enters the counter-current section and then enters the co-current section. In all three Examples 5(a) through 5(c), the reactor effect flow rate and feed flow rate are the same. In all three Examples 5(a) through 5(c), the feed was heated from 223°C to 594°C, and the reactor effluent was cooled from 862°C to 539°C. The configurations of Examples 5(a) through 5(c) were not economically optimized and are presented here primarily to illustrate possible trade-offs between different conceptual configurations. The results of Examples 5(a) through 5(c) are summarized in Table E below. The tube metal temperature for each metric is given in °C, while the values ​​for other metrics are listed relative to the corresponding values ​​in Example 5(a). These comparative metrics are heat transfer, tube pressure drop (i.e., effluent pressure drop), effluent residence time, cooling rate, and required heating surface area.

[0111] For Example 5(a), the highest maximum tube surface temperature is expected at the inner tube, while for Example 5(b), the lowest maximum tube surface temperature is expected. Therefore, for the configuration represented by Example 5(a), the risk of coking due to pre-cracking at the outer tube surface and enhanced chemical coking at the inner tube surface is highest. The tube surface temperature obtained in Example 5(c) is between that of Example 5(a) and Example 5(b), but closer to that of Example 5(b). At the cold end of the assembly, the lowest tube internal temperature is expected in Examples 5(a) and 5(c), while Example 5(b) exhibits a higher tube internal temperature. For Examples 5(a) and 5(c), the distance to the temperature is lowest, below which the risk of condensation coking increases.

[0112] Regarding the effluent pressure drop, which affects pyrolysis selectivity, Example 5(a) had the lowest effluent pressure drop, followed by Example 5(c), with Example 5(b) being significantly higher. The high effluent pressure drop in Example 5(b) is due to the significantly longer tube length compared to Examples 5(a) and 5(c).

[0113]

[0114] Table E

[0115] Regarding residence time and cooling rate, both refer to the temperature at which the effluent is cooled to 650°C. For the configuration of Example 5(b), the most favorable values ​​can be seen, which have the highest temperature difference between the effluent and the feed at the effluent inlet.

[0116] Considering the high heat transfer surface required in Example 5(b) and the high pipe metal temperature seen in Example 5(a), the configuration defined in Example 5(c) may be the optimal solution for the application described herein, provided that a minimum in-pipe temperature of 310°C is acceptable for the naphtha feedstock. If higher temperatures are required to prevent condensation and coking, then the configuration defined in Example 5(b) may be the preferred solution. Generally, those skilled in the art will select from the configurations of Examples 5(a) to 5(c) based on specific requirements, technical and economic boundary conditions.

[0117] Some illustrative embodiments of this disclosure have now been described. It will be apparent to those skilled in the art that the foregoing is merely illustrative and not restrictive, and is presented only by way of example. Many modifications and other embodiments are within the scope of those skilled in the art and are considered to fall within the scope of this disclosure. Specifically, although many embodiments presented herein relate to specific combinations of method actions or system elements, it should be understood that those actions and those elements can be combined in other ways to achieve the same purpose. Those skilled in the art will understand that the parameters and configurations described herein are exemplary, and actual parameters and / or configurations will depend on the specific application in which the system and techniques of this disclosure are used. Those skilled in the art will also recognize or be able to use equivalents that do not exceed conventional experimentation to determine specific embodiments of this disclosure. Therefore, it should be understood that the embodiments described herein are presented only by way of example, and that embodiments of this disclosure can be practiced in ways other than those specifically described within the scope of any appended claims and their equivalents.

[0118] Furthermore, the scope of this disclosure should be understood to encompass various modifications, combinations, additions, alterations, etc., of the above and aforementioned embodiments, which should be considered within the scope of this disclosure. Therefore, the various features and characteristics discussed herein may be selectively interchanged and applied to other illustrated and unillustrated embodiments, and many changes, modifications, and additions may be made thereto without departing from the spirit and scope of this disclosure as set forth in the appended claims.

[0119] An example heat recovery assembly A for recovering thermal energy from the effluent of a thermal reactor to heat the feed to an electric reactor furnace may include an inner tube having a first inlet configured to receive the thermal reactor effluent from the electric reactor, and an inner tube disposed around the inner tube to surround an annular space surrounding the inner tube. The annular space may have a second inlet configured to receive the feed to the electric reactor, and the annular space may be configured to use the feed to the electric reactor as a cooling medium to recover thermal energy from the thermal reactor effluent before the feed is supplied to the electric reactor. The annular space may be configured to enhance heat transfer from the thermal reactor effluent to the feed into the annular space.

[0120] In some embodiments, the thermal reactor effluent may reach the first inlet via a gas inlet chamber or other connector. In some embodiments, cooling may be supplied to the gas inlet chamber or other connector. In some embodiments, the gas chamber may connect one or more pyrolysis coils to one or more inner tubes. In some embodiments, a manifold may be provided to connect the feed to more than one annular space. In some embodiments, a manifold may be used to collect cooled pyrolysis gas from more than one inner tube. In some embodiments, heated feed from more than one annular space may be combined via a manifold. In some embodiments, multiple annular spaces may be included in a single mechanical device that may receive hot effluent from multiple pyrolysis coils and cold feed from a feed manifold via a gas inlet chamber or other connector.

[0121] The example component A described above includes an outer tube comprising at least one heat transfer enhancement structure to enhance heat transfer from the inner tube to the ring.

[0122] The above example component A, wherein the outer tube includes a first stage, and at least one heat transfer enhancement structure includes one or more of a plate-shaped impact structure, a flute-shaped impact structure, a turbulence-promoting structure, or a structure that increases the surface area.

[0123] In the example component A described above, the impingement heat transfer enhancement structure refers to the flow of fluid through the outer tube, whose average direction from inlet to outlet can be substantially parallel to the inner tube, intentionally oriented towards the inner tube, for example, using geometric features that introduce an annular space. In some embodiments, this directional (impingement) flow can be, for example, perpendicular to the inner tube, or directed towards the inner tube at an angle greater than thirty degrees relative to the axis of the inner tube, while its velocity can be relatively greater than the apparent velocity of the fluid in the outer tube (e.g., the volumetric flow rate of the fluid in the outer tube divided by the area of ​​the annular cross-section between the inner and outer tubes). In some embodiments, the geometric features that promote impingement can include, for example, nozzles and / or openings toward the inner tube, and / or obstructions placed in the flow path that can redirect the fluid more directly toward the outer surface of the inner tube from a direction more parallel to the inner tube. These example features can be implemented in a periodic manner, for example, creating impingement zones that appear at intervals along the length and / or circumference of the inner tube. The applicant has found that introducing such impingement features can increase the heat transfer rate relative to the heat transfer rate obtained by flowing parallel through the outer tube. Furthermore, the applicant has found that, for a suitable level of heat transfer enhancement, the ratio of the impinging flow velocity to the apparent velocity can be greater than 2, greater than 5, or greater than 10. In the case of a nozzle or opening, the impinging flow velocity can be approximated as the volumetric flow rate divided by the total flow area defined by the nozzle or opening, through which the flow is directed. Additionally, it has been found that the heat transfer enhancement structure is more suitable when the distance between the impinging feature (e.g., between the nozzle or opening 54 and the inner tube) and the inner tube is approximately twelve times the diameter of the nozzle or opening 54, or approximately ten times the diameter, or approximately two times to approximately eight times the diameter. Examples of impinging features may include plate-type impinging structures and / or flute-type impinging structures.

[0124] The example component A described above includes an outer tube comprising a plate-shaped impact structure disposed between an upstream end and a downstream end. The plate-shaped impact structure may include a first channel having a staged inlet at the upstream end and a closed flow at the staged inlet at the downstream end. The plate-shaped impact structure may also include a second channel having a staged outlet at the downstream end. The second channel may be disposed between the first channel and the inner tube. The plate-shaped impact structure may further include a wall separating the first channel and the second channel. The wall may define an opening to fluidly connect the first channel and the second channel. The plate-shaped impact structure may be configured to receive feed through the staged inlet, allow feed to flow from the first channel to the second channel via the opening in the wall to impact the outer surface of the inner tube, and discharge feed through the staged outlet of the second channel.

[0125] The example component A described above includes an outer tube comprising a flute-shaped impact structure. The flute-shaped impact structure may include an upstream divider disposed around an inner tube and within the outer tube, and a downstream divider within the outer tube disposed around the inner tube and downstream of the upstream divider in an annular space. The downstream divider may define at least one stage outlet. The flute-shaped impact structure may also include a chamber defined within the outer tube and surrounding the inner tube between the upstream and downstream dividers, and the flute-shaped tube may be parallel to or at an angle relative to the inner tube, and / or may be straight, curved, or tortuous, and / or offset from the inner tube. The flute-shaped tube may extend from the upstream divider through the chamber to the downstream divider. The flute-shaped tube may include a stage inlet for receiving incoming feed and a plurality of openings defined therein, and the openings may be oriented toward the outer surface of the inner tube. The flute-shaped impact structure may be configured to receive feed from the stage inlet, allow feed to flow from the flute-shaped tube into the chamber via the plurality of openings, impinge the flow onto the outer surface of the inner tube, and / or discharge feed from the chamber via at least one stage outlet.

[0126] The above example component A, wherein: the at least one stage includes a first stage and a second stage; and has one or more of the following features: (1) the inner tube of the first stage has a first outlet, and the inner tube is configured to allow the effluent from the thermal reactor to flow from the first inlet to the first outlet; the outer tube of the first stage has a second outlet, and the outer tube is configured to allow the feed to flow from the second inlet to the second outlet; and the second inlet of the first stage is adjacent to the first outlet of the first stage, and the second outlet of the first stage is adjacent to the first inlet of the first stage; (2) the second stage includes at least one heat transfer enhancement structure, including one or more of a plate-type impact structure, a flute-type impact structure, a turbulence-promoting structure, or a structure that increases the surface area; the second stage is connected in series with the first stage; or (3) the second stage includes an inner tube having a first inlet and a first outlet, and the inner tube is configured to allow the effluent from the reactor to flow from the first inlet of the second stage to the first outlet of the second stage; the outer tube has a second inlet and a second outlet, and the outer tube is configured to allow the feed to flow from the second inlet of the second stage to the second outlet of the second stage; and the second inlet of the second stage is adjacent to the first inlet of the second stage, and the second outlet of the second stage is adjacent to the first outlet of the second stage.

[0127] The above-described example component A, wherein at least one heat transfer enhancement structure in the first stage includes a first impact hole having a first diameter, and at least one heat transfer enhancement structure in the second stage includes a second impact hole having a second diameter different from the first diameter.

[0128] Example component A above, wherein the inner tube includes a heat transfer enhancement structure.

[0129] Example component A described above, wherein the inner tube has a first outlet and the inner tube is configured to allow the thermal reactor effluent to flow from a first inlet to a first outlet, the outer tube has a second outlet and the outer tube is configured to allow the feed to flow from a second inlet to a second outlet, and has one of the following characteristics: the second inlet is adjacent to the first outlet and the second outlet is adjacent to the first inlet; or the first inlet is adjacent to the second inlet and the first outlet is adjacent to the second outlet.

[0130] The example component A described above, wherein the heat recovery assembly includes a plurality of inner tubes parallel to each other, wherein each inner tube is disposed within an outer tube, and each outer tube has at least one or more plate-shaped impingement structure, flute-shaped impingement structure, or turbulence-enhancing structure to enhance heat transfer from the inner tube to the annular space defined within the outer tube. In some embodiments, the heat recovery assembly may include a plurality of inner tubes parallel to each other, wherein each inner tube is disposed within an outer tube, and wherein the outer tube and optionally the inner tubes have one or more heat transfer enhancement structures to enhance heat transfer from the inner tube to the annular space defined within the outer tube.

[0131] Example component A above, wherein the heat recovery component is configured to cool the thermal reactor effluent at a rate of at least 2.5 K / ms, at least 3.5 K / ms, at least 4.5 K / ms, at least 5 K / ms, or at least 5.5 K / ms. For example, the cooling rate may be defined as the inlet temperature of the thermal reactor effluent (in K) minus 923 K, divided by the residence time required to cool the thermal reactor effluent from its temperature to 923 K, unless the inlet temperature of the thermal reactor effluent (in K) is below 923 K or the temperature of the cooled reactor effluent is above 923 K. In this case, the cooling rate may be defined as the inlet temperature of the thermal reactor effluent (in K) minus the temperature of the cooled reactor effluent leaving the heat recovery component, divided by the residence time of the effluent in the component. In some implementations, the heat recovery assembly can be configured such that the pressure drop of the thermal reactor effluent through the heat recovery assembly is less than 0.35 bar, less than 0.30 bar, less than 0.25 bar, or less than 0.20 bar; the residence time of the thermal reactor effluent in the heat recovery assembly is less than 100 milliseconds, less than 95 milliseconds, less than 90 milliseconds, less than 85 milliseconds, less than 83 milliseconds, or less than 80 milliseconds; or the pressure drop of the feed through the heat recovery assembly is less than 15 bar, less than 12 bar, less than 10 bar, less than 8 bar, or less than 6 bar.

[0132] Example component A above, wherein the heat recovery component is configured to preheat the feed to at least 350°C, at least 375°C, at least 400°C, at least 425°C, at least 450°C, at least 475°C, at least 500°C, at least 525°C, at least 550°C, at least 575°C, at least 600°C, at least 625°C, or at least 650°C.

[0133] The above-described example component A, wherein the effluent from the thermal reactor enters the heat recovery component at a temperature greater than 575°C, greater than 600°C, greater than 610°C, greater than 620°C, greater than 630°C, greater than 640°C, or greater than 650°C.

[0134] Furnace assemblies for heating feedstock to provide thermal reactor effluent may include the above-described example heat recovery assembly A; and an electrically powered reactor including a reaction zone configured to heat one or more of the following feedstocks to their pyrolysis temperature: ethane, propane, butane, condensate oil, light naphtha, heavy naphtha, gas oil, pyrolysis oil, materials derived from processing refinery streams, Fischer-Tropsch products, plastic waste, or bio-feed.

[0135] Method B for producing olefins may include supplying a hydrocarbon feed to the outer tube of a heat recovery assembly and heating the hydrocarbon feed in the outer tube of the heat recovery assembly to output a preheated hydrocarbon feed. Example method B may also include supplying the preheated hydrocarbon feed to an electrically heated cracking furnace including a reaction zone to heat the preheated hydrocarbon feed, and cracking the preheated hydrocarbon feed in the reaction zone to output a thermal reactor effluent containing cracked hydrocarbons and olefins. Example method B may also include supplying the thermal reactor effluent to the inner tube of the heat recovery assembly and supplying additional hydrocarbon feed to the outer tube of the heat recovery assembly. Example method B may also include heating the additional hydrocarbon feed by transferring heat from the thermal reactor effluent to the additional hydrocarbon feed via the heat recovery assembly.

[0136] Example method B described above has one or more of the following features: (1) supplying the thermal reactor effluent to the inner tube of a heat recovery assembly, the heat recovery assembly including quenching the thermal reactor effluent via heat transfer to an additional hydrocarbon feed; or (2) heating the hydrocarbon feed in the outer tube of the heat recovery assembly, the heat recovery assembly including preheating the hydrocarbon feed via heat transfer from the thermal reactor effluent to the hydrocarbon feed. Example method B described above further includes enhancing the heat transfer to the additional hydrocarbon feed by providing a heat transfer enhancement structure on one or more of the outer or inner tube, the heat transfer enhancement structure including one or more of a plate-type impact structure, a flute-type impact structure, or a turbulence-promoting structure.

[0137] The above-described example method B, wherein supplying the thermal reactor effluent to the inner tube of the heat recovery assembly includes supplying the thermal reactor effluent to the inner tube of the heat recovery assembly at a temperature of at least 350°C, at least 375°C, at least 400°C, at least 425°C, at least 450°C, at least 475°C, at least 500°C, at least 525°C, at least 550°C, at least 575°C, at least 600°C, at least 625°C, or at least 650°C.

[0138] The above-described method B, wherein heating the hydrocarbon feed in the outer tube of the heat recovery assembly to output preheated hydrocarbon feed includes heating the hydrocarbon feed to a temperature of at least 350°C, at least 375°C, at least 400°C, at least 425°C, at least 450°C, at least 475°C, at least 500°C, at least 525°C, at least 550°C, at least 575°C, at least 600°C, at least 625°C, or at least 650°C.

Claims

1. A method for producing olefins, the method comprising: At least one cooling step in a heat recovery assembly, characterized in that: Hydrocarbon feed is supplied to the outer pipe of the heat recovery unit; The hydrocarbon feed in the outer tube of the heat recovery unit is heated to output preheated hydrocarbon feed; The preheated hydrocarbon feed is supplied to an electric cracking furnace that includes a reaction zone to heat the preheated hydrocarbon feed. In the reaction zone of an electrically heated cracking furnace, preheated hydrocarbon feed is cracked using electrically generated heat to output a thermal reactor effluent containing cracked hydrocarbons and olefins. The effluent from the thermal reactor is supplied to the inner tube of the heat recovery assembly; and The thermal reactor effluent in the inner tubes of the heat recovery unit is cooled by transferring heat to the hydrocarbon feed; and The external temperature of the inner tube in the heat recovery assembly is kept below 720°C and the internal temperature of the inner tube is kept above 160°C.

2. The method according to claim 1, wherein the external temperature of the inner tube is maintained below 720°C for ethane feedstocks, below 700°C for propane feedstocks, below 680°C for butane feedstocks, below 660°C for naphtha feedstocks, and below 640°C for feedstocks heavier than naphtha.

3. The method according to claim 1, wherein the internal temperature of the inner tube is maintained above 160°C for ethane feedstocks, above 170°C for propane feedstocks, above 180°C for butane feedstocks, and above 270°C for naphtha feedstocks or feedstocks heavier than naphtha.

4. The method according to any one of the preceding claims, wherein the thermal reactor effluent is first cooled by heat exchange with the hydrocarbon feed portion in a co-current section, and then further cooled by heat exchange with the hydrocarbon feed in a counter-current section.

5. The method according to any one of claims 1 to 3, wherein the thermal reactor effluent is first cooled by heat exchange with the hydrocarbon feed in a co-current section, further cooled by a steam generation section, and subsequently cooled by further heat exchange with the hydrocarbon feed in a counter-current section.

6. The method according to claim 4 or 5, wherein the hydrocarbon feed first passes through a co-current section and then through a counter-current section.

7. The method according to claim 4 or 5, wherein the hydrocarbon feed first passes through a countercurrent section and then through a cocurrent section.

8. The method according to claim 4 or 5, wherein the countercurrent section is a separate device and is a shell-and-tube heat exchanger.

9. A heat recovery assembly for implementing the method according to any one of the preceding claims, the heat recovery assembly comprising: outer tube; and Inner tube; The hydrocarbon feed is supplied to an electric cracking furnace, which includes a reaction zone, to heat the hydrocarbon feed. The inner tube includes a first inlet configured to receive thermal reactor effluent from an electric pyrolysis furnace; and The outer tube is arranged around the inner tube to surround an annular space surrounding the inner tube, the annular space including a second inlet configured to receive hydrocarbon feed.

10. The heat recovery assembly of claim 9, wherein the annular space includes at least one heat transfer enhancement structure to enhance heat transfer from the inner tube to the annular space.

11. The heat recovery assembly according to claim 10, wherein the at least one heat transfer enhancement structure comprises one or more of an impact structure, a turbulence-promoting structure, a high shear-induced geometry, or a structure that increases surface area.

12. The heat recovery assembly of claim 11, wherein the annular space includes a plate-shaped impact structure between the upstream end and the downstream end, the plate-shaped impact structure comprising: The first channel has a staged inlet at the upstream end and a closed flow at the downstream end; The second channel has a stage outlet at its downstream end and is located between the first channel and the inner tube; A wall separating the first channel from the second channel, the wall defining an opening for fluid connection between the first channel and the second channel; and The plate-type impact structure is configured to receive feed through a stage inlet, allow the feed to flow from the first channel to the second channel through an opening in the wall, and cause the feed flow to impact the outer surface of the inner tube and discharge the feed through the stage outlet of the second channel.

13. The heat recovery assembly according to claim 11, wherein the annular space includes a flute-shaped impact structure, the flute-shaped impact structure comprising: An upstream separator, which is disposed around the inner tube and inside the outer tube; A downstream separator, which is disposed around an inner tube and within an outer tube downstream of an upstream separator in an annular space, defines at least one stage outlet. The chamber is defined within the outer tube and surrounds the inner tube between the upstream and downstream dividers; and A flute-shaped tube with an offset inner tube arrangement extends from an upstream divider through the chamber to a downstream divider. The flute-shaped tube includes a stage inlet for receiving incoming feed and includes a plurality of openings defined therein. A flute-shaped impact structure is configured to receive feed from the stage inlet, allowing the feed to flow from the flute-shaped tube into the chamber through the plurality of openings and to discharge the feed from the chamber through at least one stage outlet.

14. The heat recovery assembly according to any one of claims 9 to 13, wherein the heat recovery assembly comprises a plurality of inner tubes parallel to each other, wherein each inner tube is disposed within an outer tube, and each outer tube has one or more of an impact structure, a turbulence-enhancing structure, a high-shear-induced geometry, or a structure that increases surface area to enhance heat transfer from the inner tubes to an annular space defined within the outer tubes.

15. Use of the heat recovery assembly according to any one of claims 9 to 14 for implementing the method according to any one of claims 1 to 8.

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