Thermal energy recovery device for electrically heated cracking processes.

Abstract

The method for producing olefins may include at least one cooling stage 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 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 hot reactor effluent including cracked hydrocarbons and olefins; supplying the hot reactor effluent to an inner tube of the thermal energy recovery assembly; and cooling the hot reactor effluent in the inner tube of the thermal energy recovery assembly by transferring heat to the hydrocarbon feed, wherein the external temperature of the inner tube in the thermal energy recovery assembly remains below 720°C and the internal temperature of the inner tube in the thermal energy recovery assembly is maintained above 180°C. TIFF2026505563000007.tif127128

Description

[Technical Field]

[0001] The present disclosure relates to systems and methods for transferring thermal energy, and more particularly to an energy recovery device for transferring thermal energy from a hot effluent to a reactor feed. [Background technology]

[0002] background Steam cracking of hydrocarbon feeds in gas-fired steam cracking furnaces is a major commercial method for producing olefins. In such processes, hydrocarbons such as ethane, propane, butane, condensates, light naphtha, heavy naphtha, gas oil, pyrolysis oil, materials derived from the processing of refinery streams, Fischer-Tropsch products, plastic waste, or biofeedstocks are heated to temperatures of approximately 550–650 °C, sometimes approaching 850 °C, to facilitate their conversion to light olefins such as ethylene and propylene. Because the cracking reaction is endothermic, a large amount of heat must be provided.

[0003] To provide the required energy for conventional steam cracking processes, natural gas and / or light gases may be combusted in gas-fired steam cracking furnaces. Combustion of hydrocarbons in gas-fired steam cracking furnaces forms carbon dioxide, which is emitted from the gas-fired steam cracking furnace as part of the flue gas. Such emissions may be undesirable in light of current environmental considerations. Olefins are major chemical building blocks and are often produced in large quantities, from hundreds of thousands of tons per year in small-scale crackers to over 2 million tons per year in a single large-scale olefin production facility. As a result, the production of olefins using gas-fired steam cracking furnaces may result in large, undesirable emissions of carbon dioxide.

[0004] In conventional gas-fired olefin production furnaces, the combustion gases can only provide heat for the cracking reaction once they exceed the reaction temperature, e.g., 550-650 °C to 850 °C. Once the gases cool below this temperature, it may be desirable to extract as much of the remaining heat as possible to achieve energy-efficient plant operation. Traditionally, this heat is recovered in the so-called convection section. The energy is often used to preheat the reactor feed and diluent vapors to the temperatures required for the cracking reaction to occur.

[0005] In olefin production, once the feed is cracked, the reactor effluent should be cooled before further processing of the cracked gas. Ideally, the initial cooling should occur quickly to reduce or prevent side reactions in the reactor effluent while it is at a relatively high temperature. Additionally, for energy-efficient processing, as much of the heat in the reactor effluent as possible should be recovered and used elsewhere in the process.

[0006] In some systems, this quenching and cooling occurs in a transfer line exchanger (TLE), where the reactor effluent is cooled by exchanging heat with liquid water to produce high-pressure steam. Cooling by exchanging heat with boiling water has the advantage that heat transfer is generally faster than cooling against a gas, sometimes five or even ten times faster for the same exchanger geometry. This steam may be used to power a steam turbine or other auxiliaries. For example, steam is commonly used to power a cracked gas compressor, one or more refrigeration compressors, or one or more pumps. While using steam to drive rotating equipment such as compressors and pumps is a convenient way to use the energy recovered from cooling the reactor effluent, the efficiency of converting energy in the form of heat (e.g., the heat contained in the steam) to mechanical work is typically low, ranging from 30 to 50%.

[0007] One solution to reducing the large amounts of carbon dioxide produced by conventional steam cracking processes is electric-current steam cracking. Electric-current steam cracking involves the use of a cracking furnace that is at least partially heated, directly or indirectly, by electricity. Electric-current steam cracking furnaces have lower emissions than gas-fired cracking furnaces.

[0008] However, electric steam cracking furnaces introduce new technical challenges that must be overcome. One consequence of using electric steam cracking furnaces is the elimination of hot flue gases from fuel combustion in gas-fired cracking furnaces. Therefore, heating, including feed preheating, typically provided by hot flue gases, must be provided by other means. A second consequence is the need for different energy integration in the cracking process. Rotating equipment such as compressors and pumps can be easily powered by electricity; moreover, the efficiency of operating such equipment with electricity is much higher than with steam, typically achieving energy efficiencies above 90% compared to the 30–50% typically achieved with steam. Therefore, there is a significant incentive to use electricity to power these devices in electric steam cracking processes. This means that the energy currently recovered during reactor effluent cooling can no longer be used to power pumps and compressors; instead, different uses of this energy must be found so that the overall energy efficiency of the process can be maintained at a high level.

[0009] For electrically powered processing, applicants have identified a need for a system and method for using energy obtained from quenching the hot reactor effluent while quenching the cracked gases rapidly enough to prevent further reaction. Applicants have also identified a need for a system and method for preheating the feed for an electrically powered furnace. Summary of the Invention

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

[0011] In certain embodiments, the external temperature of the inner tubes may remain below 720° C. for operation with ethane-type feedstocks, below 700° C. for operation with propane-type feedstocks, below 680° C. for operation with butane-type feedstocks, below 660° C. for operation with naphtha-type feedstocks, and below 640° C. for operation with feedstocks heavier than naphtha. In certain embodiments, the internal temperature of the inner tubes may remain above 160° C. for operation with ethane-type feedstocks, above 170° C. for operation with propane-type feedstocks, above 180° C. for operation with butane-type feedstocks, and above 270° C. for operation with naphtha-type or heavier feedstocks.

[0012] In certain embodiments, the hot reactor effluent may first be partially cooled against the hydrocarbon feed through a co-current section and then further cooled against the hydrocarbon feed in a counter-current section.

[0013] In certain embodiments, the hot reactor effluent is first cooled against the hydrocarbon feed through a co-current section, further cooled through a steam generating section, and then further cooled against the hydrocarbon feed in a counter-current section.

[0014] In certain embodiments, the hydrocarbon feed first passes through a co-current section and then passes through a counter-current section. In certain embodiments, the hydrocarbon feed first passes through a counter-current section and then passes through a co-current section. In certain embodiments, the counter-current section is a separate piece of equipment and is a tube-in-tube or shell-and-tube heat exchanger.

[0015] In certain embodiments, the thermal energy 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 for heating the hydrocarbon feed; the inner tube includes a first inlet configured to receive hot reactor effluent from the electric cracking furnace; and the outer tube is disposed around the inner tube so as to surround an annulus around the inner tube, wherein the annulus includes a second inlet configured to receive the hydrocarbon feed.

[0016] In certain embodiments, the annulus includes at least one heat transfer enhancement for enhancing heat transfer from the inner tube to the annulus. The at least one heat transfer enhancement may include one or more of impingement, turbulence promoter, high shear-inducing geometry, or increased surface area. The annulus may include a plate impingement between its upstream and downstream ends, the plate impingement including: a first channel having a stage inlet at its upstream end and closed to flow at its downstream end; a second channel having a stage outlet at its downstream end disposed between the first channel and the inner tube; and a wall separating the first channel from the second channel, the wall defining an opening for fluidly connecting the first and second channels; and the plate impingement is configured to receive a feed through the stage inlet, flow the feed from the first channel to the second channel through the opening in the wall to impinge the feed flow on the outer surface of the inner tube, and discharge the feed through the stage outlet of the second channel. The annulus may include a piccolo impingement; the piccolo impingement includes an upstream partition disposed around the inner tube and within the outer tube; a downstream partition disposed within the annulus, around the inner tube and within the outer tube downstream of the upstream partition, and defining at least one stage outlet; a chamber defined within the outer tube and around the inner tube between the upstream and downstream partitions; and a piccolo tube offset from the inner tube; the piccolo tube extends through the chamber from the upstream partition to the downstream partition; the piccolo tube includes a stage inlet for receiving an incoming feed; the piccolo tube includes a plurality of openings defined therein; and the piccolo impingement is configured to receive the feed from the stage inlet, flow the feed from the piccolo tube into the chamber through the plurality of openings, and discharge the feed from the chamber through the at least one stage outlet.

[0017] In certain embodiments, the thermal energy recovery assembly may include multiple inner tubes parallel to one another; each inner tube disposed within an outer tube, each outer tube having one or more of impingement, turbulence promoters, high shear inducing geometries, or increased surface area to enhance heat transfer from the inner tube to the annulus defined within the outer tube.

[0018] Certain embodiments may include the use of a thermal energy recovery assembly to carry out the present method to produce olefins.

[0019] Still other aspects and advantages of these exemplary embodiments and other embodiments are discussed in detail herein. Furthermore, it should be understood that both the foregoing information and the following detailed description provide merely illustrative examples of the 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. Accordingly, these and other objects, along with advantages and features of the present disclosure, will become apparent through the following description and reference to the accompanying drawings. Furthermore, it should be understood that the features of the various embodiments described herein are not mutually exclusive and may exist in various combinations and permutations. [Brief explanation of the drawings]

[0020] The accompanying drawings, which are included to provide a further understanding of aspects of the present disclosure, are incorporated in and form a part of this specification, illustrate aspects of the present disclosure, and, together with the detailed description, serve to explain the principles of the aspects discussed herein. No attempt has been made to show structural details of the present disclosure in more detail than is necessary for a fundamental understanding of the aspects discussed herein and the various ways in which they may be practiced. According to common practice, the various features of the drawings described below are not necessarily to scale. Dimensions of various features and elements in the drawings may be expanded or reduced to more clearly illustrate aspects of the present disclosure. [Figure 1]FIG. 1 is a schematic diagram of a portion of an exemplary furnace assembly for heating a feed to provide a hot reactor effluent, according to aspects of the present disclosure. [Figure 2] 2A and 2B are schematic, partial cross-sectional side and end views of an exemplary thermal energy recovery assembly according to embodiments of the present disclosure, taken along line BB, of the exemplary thermal energy recovery assembly shown in FIG. 2A, according to embodiments of the present disclosure. [Figure 3] 3A and 3B are partial schematic perspective and end cross-sectional views of another exemplary thermal energy recovery assembly according to aspects of the present disclosure, taken along line BB, of the exemplary thermal energy recovery assembly shown in FIG. 3A, according to aspects of the present disclosure. [Figure 4] 4A and 4B are schematic cross-sectional views of an exemplary inner tube including exemplary rounded protrusions on an inner surface of the inner tube according to embodiments of the present disclosure, and another exemplary inner tube including exemplary rectangular protrusions on an inner surface of the inner tube according to embodiments of the present disclosure. [Figure 5] FIG. 1 is a block diagram of an exemplary method for producing olefins according to aspects of the present disclosure. [Figure 6] Figures 6A and 6B are block diagrams of an exemplary single-section embodiment of a feed-effluent exchanger and a two-section embodiment of an exemplary feed-effluent exchanger, respectively. DETAILED DESCRIPTION OF THE INVENTION

[0021] Detailed Description The drawings include like numerals to indicate like parts throughout the drawings, and the following description is provided as an enabling teaching of exemplary embodiments; those skilled in the art will recognize that many variations can be made to the described embodiments. It will also become apparent that some of the desirable advantages of the described embodiments may be obtained by selecting some of the embodiments' features without utilizing other features. Thus, those skilled in the art will recognize that many modifications and adaptations to the described embodiments are possible and may even be desirable in certain circumstances. Thus, the following description is provided by way of illustration, not limitation, of the principles of the embodiments.

[0022] The phraseology and terminology used herein are for purposes of description and should not be regarded as limiting. As used herein, the term "plurality" refers to two or more items or components. The terms "comprising," "including," "carrying," "having," "containing," and "involving," whether in the written description or claims or otherwise, are open-ended terms, i.e., mean "including but not limited to," unless otherwise stated. Thus, the use of such terms is intended to encompass the items listed thereafter and equivalents thereof, as well as additional items. The transitional phrases "consisting of" and "consisting essentially of" are closed or semi-closed transitional phrases, respectively, with respect to any claim. The use of ordinal terms such as "first," "second," and "third" in the claims to modify claim elements does not, by itself, imply a priority, precedence, or ordering of one claim element relative to another claim element, or a chronological order in which the actions of a method are performed, but is merely used as a label to distinguish one claim element having a certain name from another element having the same name (but subject to the use of that ordinal term) to distinguish between claim elements.

[0023] Additionally, reference may be made herein to quantitative measurements, values, geometric relationships, and the like, and unless otherwise stated, one or more, if not all, of these may be absolute or may be approximate to accommodate acceptable variations, such as those due to manufacturing or engineering tolerances.

[0024] Applicants have identified a preferred operating window / regime to prevent undesirable performance loss of the thermal energy recovery assembly through feed pre-cracking and / or effluent coking mechanisms.

[0025] FIG. 1 schematically illustrates an exemplary furnace assembly 10 for heating a feed to provide a hot reactor effluent according to embodiments of the present disclosure. In some embodiments, the furnace assembly 10 may be used to produce olefins from hydrocarbons. As shown in FIG. 1, the furnace assembly 10 may include an electric furnace 20 and a thermal energy recovery assembly 30. As used herein, the phrase "hot reactor effluent" refers to the reactor effluent downstream of the furnace 20 and being cooled from the reactor effluent temperature upon exiting the furnace 20. In some embodiments, the thermal energy recovery assembly 30 may include one or more stages, such as a first stage 31a, a second stage 31b, and a third stage 31c, as shown in FIG. 1. As used herein, the term "stage" refers to a discrete part of the thermal energy recovery assembly configured to place the feed in indirect thermal contact with the hot reactor effluent, such as by using methods of heat transfer enhancement, as 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 of the stages may have a structural configuration that differs from that of the other stages. In some embodiments including more than one stage, the thermal energy recovery assembly may include two or more sections, each section including one or more stages. Within a section including more than one stage, the feed flows sequentially through the stages to define an overall flow direction that may be either cocurrent or countercurrent to the direction of flow of the hot reactor effluent. Each section may have corresponding inlets and outlets for the feeds and may process the same or different feeds (portions of the feed). Within the same thermal energy recovery assembly, some sections may have a cocurrent configuration, while other sections may have a countercurrent configuration.When the thermal energy recovery assembly has more than one section, the sections may be implemented in a single piece of equipment or in different pieces of equipment. For example, a first section may be implemented as a tube-in-tube exchanger for heating the hydrocarbon feed with heat transfer enhancement, as described in more detail below, a second section may be implemented as a steam-generating transfer line exchanger, and a third section may be implemented as a conventional countercurrent exchanger for heating the hydrocarbon feed. As used herein, the terms upstream and downstream are meant relative to the direction of flow of the hot reactor effluent; i.e., if a first section provides cooling of the hot reactor effluent and a second section provides further cooling of the partially cooled reactor effluent, the second section is downstream of the first section, regardless of the configuration and direction of the coolant stream. As used herein, co-current and countercurrent are meant relative to the direction of flow of the hot reactor effluent; i.e., a section in which the overall flow direction of the coolant is opposite to the hot reactor effluent is considered a countercurrent section.

[0026] In some embodiments, furnace 20 may be configured to receive a feed and heat the feed to a reaction temperature to provide a hot 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, e.g., to provide a hot reactor effluent containing cracked hydrocarbons, e.g., at least partially in a gaseous state (e.g., completely in a gaseous state). In some embodiments, furnace 20 may be configured to heat the feed to a cracking temperature to crack the hydrocarbons into desired products, which may be discharged from furnace 20 as a hot reactor effluent. The feed may include, for example, ethane, propane, butane, condensate, light naphtha, heavy naphtha, gas oil, pyrolysis oil, materials derived from the processing of refinery streams, Fischer-Tropsch products, plastic waste, and / or biofeedstock. The feed may additionally include steam. In some embodiments, furnace 20 may be configured to receive a feed into one or more reactor zones or reactor chambers 25 (e.g., cracker tubes or cracking coils) via reactor feed line 22 and discharge a hot reactor effluent via reactor effluent line 28. In some embodiments, furnace 20 may be electrically heated to the cracking temperature, e.g., such that the feed flows substantially continuously into reactor chamber 25 via reactor feed line 22 and exits reactor chamber 25 as a hot reactor effluent via reactor effluent line 28. Reactor chamber 25 may be heated directly or indirectly by electrical power. To increase the efficiency of furnace 20, the feed may be preheated to a temperature closer to the cracking temperature of the feed before entering reactor chamber 25 (e.g., upstream thereof).Reactor feed line 22 and reactor effluent line 28 may be configured to pass through additional equipment not depicted in FIG. 1, such as, for example, heat transfer equipment.

[0027] The thermal energy recovery assembly 30 may be or include a gas-to-gas energy recovery device or heat exchanger in some embodiments. The thermal energy recovery assembly 30 may be configured to receive the hot reactor effluent from the reactor chamber 25 and quench the hot reactor effluent to a quench temperature, e.g., to preserve desirable products in the reactor effluent and / or prevent side reactions from occurring in the reactor effluent as the hot reactor effluent cools. In some embodiments, a single thermal energy recovery assembly 30 may receive the hot reactor effluent from multiple reactor chambers 25. In certain embodiments, a single reactor chamber 25 may provide the hot reactor effluent to multiple thermal energy recovery assemblies 30. The ratio of the number of reactor chambers 25 to the number of thermal energy recovery assemblies 30 may be in the range of 0.1 to 10, e.g., in the range of 0.5 to 2.

[0028] The hot reactor effluent enters the thermal energy 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 hot reactor effluent, the thermal energy recovery assembly 30 may utilize the feed as a coolant, for example, before the feed enters the reactor chamber 25 (e.g., upstream of the reactor chamber 25). As a result of cooling the hot reactor effluent in the thermal energy recovery assembly 30, the feed may be preheated to a temperature closer to its cracking temperature (e.g., to a temperature of 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 thermal energy recovery assembly 30 may be configured to preheat the feed above the cracking temperature, such that cracking begins to occur within the thermal energy recovery assembly 30, for example, when the feed is preheated to a temperature above 550-650°C. As used herein, "quenched reactor effluent" refers to the reactor effluent that has passed through the thermal energy recovery assembly 30. In some embodiments, the hot reactor effluent may be additionally partially cooled or quenched before or after passing through the thermal energy recovery assembly 30. In some embodiments, the preheated feed may be further heated (e.g., by means of a fired heater or an electric heater) before entering the reactor chamber.

[0029] In some embodiments, the thermal energy recovery assembly 30 may be configured to recover thermal energy from the hot reactor effluent to heat the feed to the electro-reactor. As described herein with respect to FIGS. 2A-3B, in some embodiments, the thermal energy 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 the hot reactor effluent from the electro-reactor. The outer tube 40 may be disposed around the inner tube 34 to enclose an annulus 44 around the inner tube 34. While the terms "annulus" and "annular" (and derivatives thereof) are used herein, the "annulus 44" may or may not be defined by inner and outer circles to result in a circular cross-section having inner and outer circular boundaries. In some embodiments, the inner and / or outer boundaries of the cross-section may have a shape other than a circle, such as a triangle, a rectangle, a polygon, an ellipse, or an oval. 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 annulus 44 may include a second inlet configured to receive a feed to the electro-reactor. The annulus 44 may be configured to use the feed to the electro-reactor as a coolant to recover thermal energy from the hot reactor effluent before the feed is provided to the electro-reactor. The annulus 44 may be configured to enhance heat transfer from the hot reactor effluent to the feed. In some embodiments, the hot reactor effluent may reach the first inlet through an effluent gas inlet chamber or other connector. In some embodiments, cooling may be provided to a feed gas inlet chamber or other connector. In some embodiments, an effluent gas inlet chamber may connect one or more reaction chambers to one or more inner tubes. In some embodiments, headers may be provided to connect feeds to more than one annulus 44.In some embodiments, the cracked and cooled gas from more than one inner tube 34 may be collected using a header. In some embodiments, the heated feed from more than one annulus 44 may be combined via a header. In some embodiments, multiple annulus 44 may be contained within a single mechanical device that may receive hot effluent from multiple cracking coils via gas inlet chambers or other connectors and cold feed from a feed header.

[0030] In some applications, the residence time and / or pressure drop of the reactor effluent within the thermal energy recovery assembly 30 can affect the process and / or the product realized by the thermal process within the furnace assembly 10. Both the residence time and pressure drop experienced as the hot reactor effluent passes through the thermal energy recovery assembly 30 can affect the ethylene selectivity of the product produced by the furnace assembly 10. Residence time can be defined as the time the hot reactor effluent remains above its cracking temperature, e.g., above 550-650°C. In some embodiments, both residence time and pressure drop during quenching of the hot reactor effluent may be balanced, e.g., to preserve the ethylene selectivity of the reactor effluent. For example, an increased pressure drop within the thermal energy recovery assembly 30 can affect selectivity as a result of increased pressure within the cracking coil of the furnace assembly 10, which changes the selectivity of the cracking reaction within the furnace assembly 10. With regard to residence time, longer residence times can allow additional side reactions within the thermal energy recovery assembly 30.

[0031] In some embodiments, thermal energy recovery assembly 30 may be configured to quench the hot reactor effluent received from furnace 20, e.g., using the feed to furnace 20 as a coolant for the hot reactor effluent, and such that the feed is preheated by the hot reactor effluent before entering reactor chamber 25. For example, as shown in FIG. 1 , thermal energy recovery assembly 30 may receive the feed through cold feed line 32 and provide the preheated feed to reaction chamber 25 through reactor feed line 22. Thermal energy recovery assembly 30 may receive the hot reactor effluent from reactor effluent line 28 and provide the quenched reactor effluent to quenched effluent line 38.

[0032] In some embodiments, the thermal energy recovery assembly 30 may be configured to operate as a gas-to-gas heat exchanger to exchange heat from the hot reactor effluent to the feed. As a result of heat being exchanged between gases, it is more difficult to quench the reactor effluent within a desired residence time compared to a liquid-to-gas heat exchanger (e.g., a steam-generating heat exchanger that uses boiling water as a relatively low-temperature refrigerant, as typically used with gas-fired cracking furnaces), e.g., due to the generally lower heat transfer coefficient and smaller temperature difference between the hot and cold fluids in a gas-to-gas exchanger. Therefore, additional design features for the thermal energy recovery assembly 30 may be desirable, as described in some exemplary embodiments below.

[0033] 2A and 2B, a portion of an exemplary thermal energy recovery assembly 30 is shown having a tube-in-tube design in which hot reactor effluent flows through an inner tube 34 (e.g., a center tube) and feed flows through an annulus 44 defined at least in part by the inner tube 34 and the outer tube 40. As shown, the inner tube 34 is disposed about a central axis of the thermal energy recovery assembly 30. In some embodiments, the inner tube 34 may be disposed about the central axis of the thermal energy recovery assembly 30 or may be offset from the central axis.

[0034] Thermal energy recovery assembly 30 may be a parallel flow heat exchanger or may be a counter flow heat exchanger (e.g., as shown) where hot reactor effluent flows through thermal energy recovery assembly 30 in a first direction and feed flows through thermal energy recovery assembly 30 in a second direction opposite the first direction. In some embodiments, inner tube 34 may include inlet 33 and outlet 35, where hot reactor effluent enters through inlet 33, flows through inner tube 34, and exits through outlet 35. Annulus 44 may include inlet 43 and outlet 45, where feed enters through inlet 43, flows through annulus 44, and exits through outlet 45 as preheated feed. In such embodiments, the hot reactor effluent, at its highest temperature before being cooled by heat transfer to the feed to preheat the feed, enters the thermal energy recovery assembly 30 at inlet 33; inlet 33 is at a point proximate to where the feed, at its highest temperature after being heated by the reactor effluent, exits the thermal energy recovery assembly 30 through outlet 45 as preheated feed. The reactor effluent, at its lowest temperature after heating the feed (e.g., quenched reactor effluent), exits the thermal energy recovery assembly 30 as quenched reactor effluent at outlet 35; outlet 35 is at a point proximate to where the feed, at its lowest temperature before being heated by the hot reactor effluent, enters the thermal energy recovery assembly 30 through inlet 43. In some such embodiments, the hot reactor effluent enters the thermal energy recovery assembly 30 at its highest temperature, at the point where the feed exits the thermal energy recovery assembly 30 at its highest temperature, and the reactor effluent exits the thermal energy recovery assembly 30 at its lowest temperature, at the point where the feed enters the thermal energy recovery assembly 30 at its lowest temperature. In some embodiments, the thermal energy recovery assembly 30 may be a parallel flow heat exchanger, where the reactor effluent and feed flow in the same direction within the thermal energy recovery assembly 30 .In some embodiments, if the thermal energy recovery assembly 30 is made up of more than one section, some sections may be co-flow and other sections may be counter-flow.

[0035] In some embodiments, the inner tube 34 may be or include a bare or plain tube with a smooth inner surface. In some embodiments, the inner tube 34 may include heat transfer augmentations that promote turbulence or increase the surface area of ​​the inner tube 34. For example, the inner tube 34 may include velocity rods or other turbulence-promoting structures. In some embodiments, the inner tube 34 may include fins (e.g., straight and / or rifled fins with rectangular and / or rounded 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 augmentations within the inner tube 34 may reduce the residence time of the reactor effluent. The heat transfer augmentations may increase the pressure drop in the reactor effluent. In some embodiments, the inclusion of heat transfer augmentations within the inner tube 34 may be balanced, for example, to reduce the pressure drop resulting from the heat transfer augmentation. In certain embodiments, fouling may be expected, requiring frequent cleaning of the inner tube 34. In such embodiments, the inner tube 34 may be straight or bare to aid in cleaning. In certain embodiments, some sections of the inner tube 34 may be bare, and some sections of the inner tube 34 may include heat transfer enhancements, such as the turbulence-promoting structures and / or area-enhancing features described above.

[0036] In some embodiments, the annulus 44 may include turbulence-promoting structures such as, for example, winglets, artificial roughness, washboards / grooves, pin fins, and / or dimples. Such structures may increase the heat transfer rate from the outer surface of the inner tube 34 and / or increase the pressure drop of the feed passing through the annulus 44. Such structures may be used by themselves as heat transfer augmentations or may be used in combination with other heat transfer augmentations, such as, for example, the plate impingement and piccolo impingement described herein.

[0037] In some embodiments, the annulus 44 may include a high-shear-inducing geometry configured to promote high-shear flow; the high-shear flow may result from a feed flowing at high velocities, such as greater than 50 meters per second (m / s), greater than 60 m / s, greater than 70 m / s, or greater than 80 m / s. In some embodiments, the direction of the high-shear feed flow through the annulus is substantially parallel to the inner tube. In some embodiments, the high-shear-inducing geometry may include configuring the outer tube such that the spacing between the outer surface of the inner tube 34 and the inner surface of the outer tube 40 is 10 millimeters (mm) or less, 8 mm or less, 6 mm or less, or 4 mm or less. The high shear rate may serve as a heat transfer enhancement by promoting a high heat transfer rate from the flowing feed to the outer surface of the inner tube 34.

[0038] In some embodiments, heat transfer enhancement due to impingement can refer to the flow of fluid through the outer tube; the average direction of that flow as it travels from inlet to outlet can be substantially parallel to the inner tube, while being intentionally directed toward the inner tube, e.g., using geometric features introduced within the annulus. In some embodiments, this directed (impinging) flow can be, for example, perpendicular to the inner tube, or can be directed toward the inner tube at an angle greater than 30 degrees relative to the axis of the inner tube; while its velocity can be relatively greater than the superficial 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, geometric features that promote impingement can include, for example, nozzles and / or openings oriented toward the inner tube; and / or obstacles placed in the flow path that redirect the fluid from a direction more parallel to the inner tube toward more directly toward the outer surface of the inner tube. These exemplary features may be implemented in a periodic manner, resulting in, for example, impingement zones spaced along the length and / or circumference of the inner tube. Applicant has discovered that the introduction of such impingement features increases the heat transfer rate relative to the heat transfer rate achieved by parallel flow through the outer tube. Furthermore, Applicant has discovered that for a suitable level of heat transfer enhancement, the ratio of impinging flow velocity to superficial velocity may be greater than 2, greater than 5, or greater than 10. In the case of a nozzle or orifice through which flow is directed, the impinging flow velocity may be approximated as the volumetric flow rate divided by the total flow area defined by the nozzle or orifice. Additionally, heat transfer enhancement may be found to be more favorable when the distance between the impingement-inducing feature (e.g., nozzle or opening 54) and the inner tube is from about the diameter of the nozzle or opening 54 to about 12 times the diameter, from about the diameter of the nozzle or opening 54 to about 10 times the diameter, or from about 2 times the diameter to about 8 times the diameter. Examples of impingement features may include plate impingement and / or piccolo impingement.In certain embodiments, the at least one heat transfer augmentation in the first stage may be the same as or different from the at least one heat transfer augmentation in the second stage.

[0039] 2A, 2B, 3A, and 3B, the annulus 44 of the thermal energy recovery assembly 30 (see FIGS. 2A and 2B) may include another structure to facilitate heat transfer from the reactor effluent in the inner tube 34 to the feed in the annulus 44 of the thermal energy recovery assembly 30. For example, the thermal energy recovery assembly 30 may include, for example, a plate impingement 50 in the annulus 44 of the thermal energy recovery assembly 30, as shown in FIGS. 2A and 2B, and / or the thermal energy recovery assembly 30 may include a piccolo impingement 60 (see also FIG. 3A) in the annulus 44 of the thermal energy recovery assembly 30 (see also FIG. 3B).

[0040] 2A and 2B , the plate impingement 50 may include a coolant (e.g., a feed) entering a first channel 52 through a stage inlet 43; the first channel 52 may be spaced from the inner tube 34, such as on the outside or outer periphery of the annulus 44 of the thermal energy recovery assembly 30. The coolant exits the first channel through one or more nozzles or openings 54 in a wall 55 and enters a second channel 56 in contact with the inner tube 34. For example, the first channel 52 may terminate at a downstream end 58 such that the coolant is forced into the second channel 56, flows through the annulus 44, and exits through a stage outlet 45 at the downstream end of the second channel 56. The wall 55 separates the first channel 52 from the second channel 56. The thermal energy recovery assembly 30 may include one or more plate impingements 50 disposed along its length. Each plate impingement 50 as shown in FIGS. 2A and 2B can be considered a stage of plate impingement, where the thermal energy recovery assembly 30 includes one or more plate impingements in series or parallel with each other.

[0041] In some embodiments, one or more of the nozzles or openings 54 may have a circular cross-section. In such embodiments, the diameter of the one or more nozzles or openings 54 may range from about 1 millimeter (mm) to about 15 mm, such as about 2 mm to about 10 mm, about 3 mm to about 8 mm, or about 4 mm to about 7 mm. For nozzles or openings 54 that do not have a circular cross-section, the cross-sectional area of ​​the nozzle or opening 54 may substantially correspond to the area of ​​a 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 may be staggered circumferentially along the longitudinal length of the wall, for example, in a spirally extending manner. In some embodiments, wall 55 may be spaced from the outer surface of inner tube 34 by a distance ranging from about the diameter of nozzle or opening 54 to about 12 times the diameter of nozzle or opening 54, from about that diameter to about 10 times that diameter, or from about 2 times that diameter to about 8 times that diameter, for example, when nozzle or opening 54 has a circular cross-section.

[0042] In some embodiments, the nozzles or openings 54 may be spaced around the circumference of the wall 55. For example, at a given point along the longitudinal length of the wall 55, the wall may include, for example, 1 to 15 nozzles or openings 54, which may depend at least in part on the dimensions of the inner tube 34, e.g., a relatively longer inner tube 34 may have more nozzles or openings 54. In some embodiments, the nozzles or openings 54 may be circumferentially spaced around the inner tube 34, with the spacing being equal to the sum of the diameter of the outer surface of the inner tube 34 and twice the distance from the nozzles or openings 54 to the outer surface of the inner tube 34 multiplied by pi (i.e., 3.14159), 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 from one another along the longitudinal length of the wall 55 and / or substantially equally spaced around the circumference of the wall 55.

[0043] 3A and 3B, piccolo impingement 60 may include a refrigerant (e.g., feed) entering one or more piccolo or outer tubes 62 and a chamber 66 defined around inner tube 34. In some embodiments, chamber 66 may generally define an annulus, such as annulus 44 shown in FIGS. 2A and 2B. Outer tube 62 may include stage inlet 43 and may include one or more nozzles or openings 64 configured to contact refrigerant with inner tube 34, e.g., to allow refrigerant to flow from outer tube 62 into chamber 66. In some embodiments, one or more of nozzles or openings 64 may be directed toward the exterior surface of inner tube 34, as shown in FIG. 3B. Chamber 66 may be defined between a first or upstream partition 65 and a second or downstream partition 67. Upstream partition 65 may include an opening that allows refrigerant to enter outer tube 62. A downstream partition 67 may terminate the downstream end of each outer tube 62 and may include an outlet defined in the downstream partition 67 that allows the refrigerant to exit the chamber 66 and flow into another set of outer tubes 62 or exit the thermal energy recovery assembly 30. The thermal energy recovery assembly 30 may include one or more piccolo impingements 60 arranged along its length. Each piccolo impingement 60, as shown in Figures 3A and 3B, can be considered a stage of piccolo impingement, where the thermal energy recovery assembly 30 includes one or more plate impingements in series or parallel with each other.

[0044] In some embodiments, one or more of the nozzles or openings 64 may have a circular cross-section. In such embodiments, the diameter of the one or more nozzles or openings 64 may be in the range of about 1 millimeter (mm) to about 15 mm, such as about 2 mm to about 10 mm, about 3 mm to about 8 mm, or about 4 mm to about 7 mm. For nozzles or openings 64 that do not have a circular cross-section, the cross-sectional area 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 with respect to their respective outer tubes 62 so that fluid passing through each of the nozzles or openings 64 is directed toward the outer surface of the inner tube 34, for example, at an angle of about 90 degrees relative to the outer surface of the inner tube 34. In some embodiments, one or more of the nozzles or openings 64 may be circumferentially oriented with respect to their respective outer tubes 62 so that fluid passing through the nozzles or openings 64 is at a non-perpendicular angle to the outer surface of the inner tube 34, e.g., in the range of 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 along the length of the outer tube 62 (e.g., in a direction along the longitudinal axis) and may be aligned circumferentially. In some embodiments, the nozzles or openings 64 may be spaced from the outer surface of the inner tube 34 by a distance ranging from about the diameter of the nozzle or opening 64 to about 12 times the diameter of the nozzle or opening 64, from about that diameter to about 10 times that diameter, or from about 2 times that diameter to about 8 times that diameter, e.g., when the nozzle or opening 64 has a circular cross-section.

[0045] In some embodiments, each outer tube 62 may include a single nozzle or opening 64 at each of multiple locations along the length of the outer tube 62. In some embodiments, each outer tube 62 may include a number of nozzles or openings 64 ranging from 1 to 15 nozzles or openings 64, 1 to 10 nozzles or openings 64, 1 to 5 nozzles or openings 64 (e.g., 4 nozzles or openings 64), or 5 to 10 nozzles or openings 64. In some embodiments, the distance between nozzles or openings 64 on each outer tube 62 may be specified, for example, such that the distance between adjacent nozzles or openings 64 divided by the diameter of the nozzles or openings 64 is equal to or greater than 1 and equal to or less than 20. The number of outer tubes 62 in a stage may be 1 to 12, or 2 to 6.

[0046] The thermal energy recovery assembly 30 may have a modular design with multiple stages along its length. For example, the thermal energy recovery assembly 30 may include one or more plate impingement stages 50 and one or more piccolo impingement stages 60. In some embodiments, the thermal energy recovery assembly 30 may include only a plate impingement stage 50 or only a piccolo impingement stage 60. In certain embodiments, the thermal energy recovery assembly 30 may include a plate impingement stage 50, a piccolo impingement stage 60, and a turbulence-promoting (TP) feature or TP stage.

[0047] The thermal energy recovery assembly 30 may be used in conjunction with a conventional gas-to-liquid vapor-generating TLE. For example, a conventional TLE may be used to provide an initial quench of the reactor effluent, followed by the thermal energy recovery assembly 30, so long as the reactor effluent enters the thermal energy 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 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. Alternatively, the thermal energy recovery assembly 30 may be followed by a conventional TLE, for example, if the thermal energy 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 575°C, at least 600°C, at least 625°C, or at least 650°C. For example, the furnace assembly 10 may include a conventional TLE before or after the thermal energy recovery assembly 30. For example, the reactor effluent line 28 and / or the quenched effluent line 38 may include a conventional TLE. In some embodiments, a conventional gas-to-liquid vapor-generating TLE may be part of the same assembly as the thermal energy recovery assembly 30. In some embodiments, the thermal energy recovery assembly 30 according to some embodiments may be combined with superheating of a steam stream.

[0048] The characteristics of the stages of the thermal energy recovery assembly 30 may be fine-tuned depending on, for example, the position of the stage within the thermal energy recovery assembly 30. For example, if the thermal energy recovery assembly 30 includes a plate impingement stage 50, the channels 52 and / or 56, nozzles or openings 54, and / or the length of the plate impingement stage 50 may be sized and dimensioned to optimize heat transfer for the conditions at that position along the thermal energy recovery assembly 30. As such, a first channel 56 of a stage 50 at a first position along the thermal energy recovery assembly 30 may have a greater radial height than a first channel 56 of a stage 50 at a second position along the thermal energy recovery assembly 30. Similarly, a nozzle or opening 54 of a stage 50 at a first position may have a smaller diameter than a nozzle or opening 54 of a stage 50 at a second position. In some embodiments, the radial height may remain substantially equal between one or more stages. In some embodiments, when the thermal energy recovery assembly 30 includes a piccolo impingement stage 60, the diameter of the outer tube 62, the size and / or number of nozzles 64, and / or the length of the piccolo impingement stage 60 may be sized and dimensioned to optimize heat transfer for the conditions at that position along the thermal energy recovery assembly 30. In some embodiments, the number of nozzles or openings 54 may be greater, fewer, or the same per stage. In some embodiments, the number of rows of nozzles or openings 54 may vary per stage. The conditions along the thermal energy recovery assembly 30 may include the reactor effluent temperature, the feed temperature, the reactor effluent inlet and / or outlet pressure, the feed inlet and / or outlet pressure, the reactor effluent pressure drop along the length of the assembly, the feed pressure drop along the length of the thermal energy recovery assembly 30, the temperature difference between the feed and the reactor effluent, the reactor effluent velocity, and / or the feed velocity.

[0049] As described above, the thermal energy recovery assembly 30 may include sections in series with one another. The thermal energy recovery assembly 30 may activate or deactivate one or more of these sections based on, for example, the temperature of the hot reactor effluent entering the thermal energy recovery assembly 30, the temperature of the quenched reactor effluent exiting the thermal energy recovery assembly 30, the temperature of the feed entering the thermal energy recovery assembly 30, and / or the temperature of the feed exiting the thermal energy recovery assembly 30. In some embodiments, when a section is activated, flow may flow through the activated section, and when a section is deactivated, flow is prevented from flowing through the deactivated section. For example, when the quenched reactor effluent exiting the thermal energy recovery assembly 30 is above a desired temperature, the thermal energy recovery assembly 30 may activate one or more additional sections so that the temperature of the quenched reactor effluent exiting the thermal energy recovery assembly 30 decreases toward the desired temperature, and / or when the quenched reactor effluent exiting the thermal energy recovery assembly 30 is below a desired temperature, the thermal energy recovery assembly 30 may deactivate one or more sections so that the temperature of the quenched reactor effluent exiting the thermal energy recovery assembly 30 increases toward the desired temperature. In some embodiments, as will be understood by those skilled in the art, the thermal energy recovery assembly 30 may include one or more controllers configured to control the operation of, for example, one or more of the sections. For example, the thermal energy recovery assembly 30 may include multiple temperature sensors, pressure sensors, flow sensors, etc. in communication with the controller, and the controller may employ control logic in the form of computer software and / or hardware programs to make control decisions related to controlling the operation of the thermal energy recovery assembly 30, including, for example, the one or more sections.In some embodiments, the thermal energy recovery assembly 30 may include valves associated with the lines and / or conduits, and the controller may communicate control signals based at least in part on the control decisions to actuators associated with the valves to control the flow of fluid (e.g., gas and / or liquid) and / or heat, and the actuators may be actuated in accordance with the communicated control signals to operate parts of the thermal energy recovery assembly 30. In some examples, the controller may be supplemented or replaced by a human operator who at least partially manually controls the thermal energy recovery assembly 30 to meet desired performance parameters based at least in part on efficiency considerations.

[0050] In some embodiments, the thermal energy recovery assembly 30 may be configured to quench the hot reactor effluent within a residence time and / or with a pressure drop consistent with other quench devices in a gas-fired cracking furnace. In some embodiments, the thermal energy recovery assembly 30 may be tuned or optimized to be substantially equivalent to or improved over other types of quench devices. For example, the thermal energy recovery assembly 30 may be configured such that: the residence time, as measured by time within the thermal energy 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 reactor effluent pressure drop 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 degrees Kelvin (K) / ms, e.g., greater than 3.5 K / ms, greater than 4.0 K / ms, greater than 4.5 K / ms, at least 5 K / ms, or at least 5.5 K / ms; for example, where the cooling rate is calculated by subtracting 923 K from the hot reactor effluent inlet temperature (degrees Kelvin) and subtracting 923 K from the hot reactor effluent temperature. the cooling rate may be defined as the hot reactor effluent inlet temperature (Kelvin) less than 923 K or the cooled reactor effluent temperature greater than 923 K, in which case the cooling rate may be defined as the hot reactor effluent inlet temperature (Kelvin) minus the temperature of the cooled reactor effluent as it exits the thermal energy recovery assembly, divided by the residence time of the effluent within the assembly. In addition to effluent pressure drop and cooling rate performance, the thermal energy recovery assembly 30 may be configured to achieve a feed pressure drop of 2 to 15 bar, e.g., 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 required amount of pressurization of the feed before it enters the thermal energy recovery assembly 30 while facilitating a sufficiently high rate of heat transfer from the inner tubes to the feed.

[0051] In some embodiments, the thermal energy 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 thermal energy recovery assembly 30 may be configured with one or more stages for transferring heat from the hot reactor effluent to a hydrocarbon feed that is not preheated, or at least not preheated sufficiently to be fed to a cracking furnace for cracking. In some embodiments, the stages may have a tube-in-tube 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 having one or more heat transfer enhancements, such as, for example, plate impingement, piccolo impingement, one or more turbulence-promoting features associated with the outer and / or inner tubes, and / or increased surface area associated with the outer and / or inner tubes. For example, the inner tube may include one or more heat transfer enhancements configured to facilitate heat transfer from the hot reactor effluent. Configuring the one or more stages and inner tubes may include selecting stages to achieve desired properties of the hot reactor effluent while transferring heat to the cold feed. For example, stages may be selected to improve or maximize the cooling rate of the hot reactor effluent, improve or minimize the pressure drop of the hot reactor effluent, improve or minimize the residence time of the hot reactor effluent, and / or improve or minimize the pressure drop of the hydrocarbon feed.

[0052] In some embodiments, a thermal energy recovery assembly may include a plurality of parallel inner tubes; each inner tube disposed within an outer tube, each outer tube having one or more heat transfer enhancements for enhancing heat transfer from the inner tube to an annulus defined within the outer tube. In some embodiments, a thermal energy recovery assembly may include a plurality of parallel inner tubes; each inner tube disposed within an outer tube, each outer tube, and optionally, inner tube, having one or more heat transfer enhancements for enhancing heat transfer from the inner tube to an annulus defined within the outer tube.

[0053] FIG. 4A is a schematic cross-sectional view of an exemplary inner tube 34a including exemplary rounded protrusions 70a on an inner surface 72a of the inner tube 34a according to embodiments of the present disclosure. As shown in FIG. 4A, in some embodiments, the inner surface 72a of the inner tube 34a may include turbulence-promoting structures and / or structures that increase the surface area of ​​the inner surface 72a. For example, as shown in FIG. 4A, the inner surface 72a of the inner tube 34a may include one or more rounded protrusions 70a. In some embodiments, the one or more rounded protrusions 70a may extend toward the center of the inner tube 34a and / or may extend partially, intermittently, or fully longitudinally along the length of the inner tube 34a. In some embodiments, the rounded protrusions 70a may be the same as or different from one another. In some embodiments, one or more rounded protrusions 70a may extend helically along the longitudinal length of the inner tube 34a, for example, to promote swirling of the flow through the inner tube 34a. In some embodiments, the protrusions on the inner surface of the inner tube 34a may have a non-rounded configuration. For example, FIG. 4B is a schematic cross-sectional view of another exemplary inner tube 34b including an exemplary rectangular protrusion 70b on the inner surface 72b of the inner tube 34b according to embodiments of the present disclosure. In some embodiments, the inner surface of the inner tube 34 may include a combination of rounded and rectangular protrusions. Other protrusion configurations are also contemplated. In some embodiments, the inner tube 34 may include turbulence-promoting structures and / or structures that increase the surface area of ​​the outer surface of the inner tube 34. For example, the turbulence-promoting structures and / or structures that increase the surface area of ​​the outer surface of the inner tube 34 may include protrusions at least similar to the protrusions on the inner surface of the inner tube 34 described above. In some embodiments, the surface area-increasing structures on the outer surface of the inner pipe 34 may be configured to enhance the effectiveness of the turbulence-promoting structures and / or impingement features. In some embodiments, the inner surface of the outer pipe 40 may include surface area-increasing structures, for example, as described above.

[0054] FIG. 5 is a block diagram of an exemplary method 500 for heating a hydrocarbon feed, including, for example, one or more of ethane, propane, butane, condensate, light naphtha, heavy naphtha, gas oil, pyrolysis oil, materials derived from the processing of refinery streams, Fischer-Tropsch process products, plastic waste, and / or biofeedstock. The hydrocarbon feed may additionally include steam. The hydrocarbon feed may be preheated and then cracked in an electrically heated cracking furnace; the cracking furnace may output cracked hydrocarbons containing olefins. An exemplary method 500 according to some embodiments is illustrated in FIG. 5 as a collection of blocks in a logical flow graph representing a sequence of operations. The order in which the operations are described is not intended to be limiting, and any number of the described blocks may be combined in any order and / or in parallel to implement the method. Additionally, operations described in one or more blocks, such as, for example, operations described by blocks 512 and / or 514, may be optional and / or omitted from example method 500; however, one or more operations described by other blocks may also or alternatively be omitted from example method 500.

[0055] The exemplary method 500 may include, at 502, supplying a hydrocarbon feed to an outer tube of a thermal energy recovery assembly. For example, the thermal energy recovery system may include any of the thermal energy recovery systems described herein. As described above, the hydrocarbon feed may include one or more of ethane, propane, butane, condensate, light naphtha, heavy naphtha, gas oil, pyrolysis oil, and / or materials derived from the processing of refinery streams, Fischer-Tropsch products, plastic waste, or biofeedstock, or any other hydrocarbon that can be converted to olefins in a cracking process; and may additionally include steam. The hydrocarbon feed, in some embodiments, may include or be a hydrocarbon feed provided by a hydrocarbon feed source.

[0056] The exemplary method 500 may further include heating the hydrocarbon feed within the outer tube of the thermal energy recovery assembly to output a preheated hydrocarbon feed at 504. For example, the hydrocarbon feed may be preheated via heat transfer within a thermal energy recovery system, with the thermal energy being provided at least in part by the hot reactor effluent of a cracking process, as described herein.

[0057] The exemplary method 500 may also include, at 506, feeding the preheated hydrocarbon feed to an electrically heated cracking furnace including a reaction zone to heat the preheated hydrocarbon feed, for example, as described previously herein.

[0058] The exemplary method 500 may further include, at 508, cracking the preheated hydrocarbon feed in a reaction zone to output a hot reactor effluent comprising cracked hydrocarbons and olefins, for example, as described previously herein.

[0059] The exemplary method 500 may also include, at 510, providing the hot reactor effluent to an inner tube of a thermal energy recovery assembly, e.g., as described previously herein. For example, in some embodiments, providing the hot reactor effluent to the inner tube of the thermal energy recovery assembly may include providing the hot reactor effluent to the inner tube of the thermal energy 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., at least 650° C., at least 700° C., at least 750° C., at least 800° C., or at least 850° C.

[0060] The exemplary method 500 may further include supplying an additional feed to the outer tube of the thermal energy recovery assembly at 512. The additional feed may be a continuation of the hydrocarbon feed supply at 502, a different hydrocarbon feed, water, or steam, in some embodiments, from a hydrocarbon feed source. The additional feed may be supplied to a different section than the section to which the hydrocarbon feed is supplied. The additional feed may be mixed with the hydrocarbon feed, and the mixed feed exits the thermal energy recovery assembly at a common outlet. The additional feed may pass through a different stage than the hydrocarbon feed and exit through a different outlet.

[0061] The exemplary method 500 may also include, at 514, heating the additional feed by transferring heat from the hot reactor effluent to the additional hydrocarbon feed via a thermal energy recovery assembly, e.g., as described previously herein. Heating the additional feed within the outer tube of the thermal energy 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, feeding the hot reactor effluent to the inner tube of the thermal energy recovery assembly may include quenching the hot reactor effluent via heat transfer to the additional hydrocarbon feed, e.g., as described herein. In some embodiments, heating the feed within the outer tube of the thermal energy recovery assembly may include preheating the feed via heat transfer from the hot reactor effluent to the feed. In some embodiments, the exemplary method 500 may further include enhancing heat transfer to the additional feed by providing heat transfer augmentations on one or more of the outer tube or inner tube. The heat transfer augmentations may include one or more of plate impingement, piccolo impingement, turbulence promoters, or increased surface area, for example, as described previously herein.

[0062] In one embodiment of the present disclosure, a method for producing olefins may include one or more cooling stages characterized by: feeding 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; feeding 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 hot reactor effluent including cracked hydrocarbons and olefins; feeding the hot reactor effluent to an inner tube of the thermal energy recovery assembly; cooling the hot reactor effluent in the inner tube of the thermal energy recovery assembly by transferring heat to the hydrocarbon feed; and configuring the thermal energy recovery to operate within a preferred operating regime without performance loss through precracking of the feed and / or coking of the effluent.

[0063] In certain embodiments, the heat recovery assembly may include one or more sections in a series or parallel configuration, each with countercurrent or cocurrent flow direction. The detailed layout of these sections, and the stages contained within these sections, may differ partially or entirely in terms of tube and annulus layout, methods of heat transfer enhancement, and methods of heat transfer area enhancement.

[0064] In certain embodiments of the thermal energy recovery assembly, individual stages or sections may be configured and sized to operate within a preferred operating regime for thermal energy recovery without significant or any performance loss. Performance loss can occur when a fouling layer forms on the inner or outer surfaces of the inner tubes through chemical and / or physical processes, reducing heat transfer from the inner tubes to the annulus. These chemical and physical processes are highly dependent on the type and composition of the hydrocarbon feed and the composition of the hot reactor effluent, as well as the prevailing temperatures on the inner and respective outer surfaces of the inner tubes. Such processes can be feed precracking within the annulus and chemically and physically induced coking on the effluent side. Feed precracking within the annulus defines a high-temperature level that should not be exceeded on the outer surface of the inner tubes. An additional high-temperature level that should not be exceeded on the inner surface of the inner tubes can be defined by chemical coking, which is accelerated by high surface temperatures. The low temperature level that should not be reached on the inner surface of the inner tube may be determined by coking driven by condensation of heavy components in the effluent. The high temperature level, determined by the risk of precracking initiation within the annulus, may depend on the hydrocarbon feedstock type. For example, the high temperature level may be 530°C, 540°C, 550°C, 600°C, 640°C, 650°C, 660°C, 680°C, 700°C, 720°C, or 750°C. For ethane-type feedstocks, this high temperature level may be 700-720°C. For propane-type feedstocks, this high temperature level may be 680-700°C. For butane-type feedstocks, this high temperature level may be 660-680°C. For naphtha-type feedstocks, this high temperature level may be 640-660°C. For feedstocks heavier than naphtha, this upper temperature level may be 540-640°C.The upper temperature level, defined by the risk of enhanced chemical coking on the inner surface of the inner tubes, may be determined by the reactivity of the effluent at temperatures above 650-680°C. The lower temperature limit, defined by enhanced coking due to condensation of heavy components in the effluent, may be determined by the feed type and cracking conditions. For example, the lower temperature level may be 150°C, 160°C, 170°C, 180°C, 200°C, 250°C, 270°C, 300°C, 350°C, etc. For ethane-type feedstocks, this lower temperature level may be 160-220°C. For propane-type feedstocks, this lower temperature level may be 170-250°C. For butane-type feedstocks, this lower temperature level may be 180-270°C. For naphtha-type feedstocks, this lower temperature level may be 270-320°C. For feedstocks heavier than naphtha, this lower temperature level may be 270-320°C.

[0065] For the application of a single section of a tube-in-tube gas-gas exchanger in an energy recovery assembly, referring to FIG. 6A, the reactor effluent may be in either a countercurrent or cocurrent flow direction relative to the feed. The hot reactor effluent may be fed to an inner tube, and the feed may be fed to an outer tube disposed around the inner tube to enclose an annulus. The annulus may include at least one heat transfer augmentation feature to enhance heat transfer from the inner tube to the annulus through impingement, turbulence promoters, high shear-inducing geometries, or increased surface area.

[0066] For the application of two sections of a tube-in-tube gas-gas exchanger in an energy recovery assembly, referring to FIG. 6B, the reactor effluent flow direction may be cocurrent with the feed in the first section and countercurrent to the feed in the second section. The hot reactor effluent may be fed to the inner tube, and the feed may be fed to the outer tube, which is arranged around the inner tube to enclose an annulus. The annulus may include at least one heat transfer enhancement to enhance heat transfer from the inner tube to the annulus through impingement, turbulence promoters, high shear-inducing geometries, or increased surface area. The method of heat transfer enhancement applied and the detailed layout may be the same for both sections or may be different.

[0067] In some embodiments of the two-section application, a cold feed may enter a tube-in-tube gas-gas exchanger in the upstream co-current section where primary preheating occurs and may be further heated in the downstream counter-current section. Hot reactor effluent may be fed to the inner tube, and the feed may be fed to an outer tube arranged around the inner tube to enclose an annulus. The annulus may include at least one heat transfer enhancement to enhance heat transfer from the inner tube to the annulus through impingement, turbulence promoters, high shear-inducing geometries, or increased surface area. The method and detailed layout of the heat transfer enhancement applied may be the same for both sections or may be different.

[0068] In some embodiments of the two-section application, the cold feed may enter a tube-in-tube gas-gas exchanger in the downstream countercurrent section where primary preheating occurs and may be further heated in the upstream cocurrent section. The hot reactor effluent may be fed to the inner tube, and the feed may be fed to the outer tube, which is arranged around the inner tube to enclose an annulus. The annulus may include at least one heat transfer enhancement to enhance heat transfer from the inner tube to the annulus through impingement, turbulence promoters, high shear-inducing geometries, or increased surface area. The method and detailed layout of the heat transfer enhancements applied may be the same for both sections or may be different.

[0069] In some embodiments, the co-current and counter-current sections may be implemented in a single piece of equipment. In some embodiments, the co-current and counter-current sections may be implemented in different pieces of equipment, for example, the co-current stage may be constructed as a tube-in-tube exchanger with heat transfer enhancements and the counter-current stage may be constructed as a conventional tube-in-tube or shell-and-tube heat exchanger, or any other suitable conventional heat exchanger design. [Example]

[0070] The heat transfer performance of several thermal energy recovery assemblies including heat transfer augmentations according to aspects of the present disclosure was compared to the performance of a conventional tube-in-tube gas-to-gas heat exchanger designed for a feed-side pressure drop of 1.76 bar and containing no augmentations in either the inner tube or the annulus. Thermal energy recovery assemblies according to aspects of the present disclosure were as follows: (1) a tube-in-tube type thermal energy recovery assembly with no heat transfer enhancements in the inner tube and a high shear geometry in the annulus; (2) a thermal energy recovery assembly including fins in the inner tube and turbulence-promoting features in the annulus; (3) a thermal energy recovery assembly including fins in the inner tube and plate impingement in the annulus; (4) a thermal energy recovery assembly including fins in the inner tube and piccolo impingement in the annulus; (5) a thermal energy recovery assembly including plain tubes (no internal fins) and turbulence-promoting features in the annulus; (6) a thermal energy recovery assembly including plain tubes and plate impingement in the annulus; and (7) a thermal energy recovery assembly including plain tubes and piccolo impingement in the annulus.

[0071] For comparison purposes, boundary conditions for a conventional heat exchanger ("Comp.") and each of seven exemplary thermal energy recovery assemblies (1-7) according to embodiments of the present disclosure were established as follows: a hot effluent resulting from steam cracking of ethane was passed through the inner tube, and a cold feed comprising ethane and steam was passed through the outer tube. The mass flow rate of the hot effluent was 351.6 kilograms / hour, the outer diameter of the inner tube was 60.3 mm, and the wall thickness of the tube was 3.6 mm. The hot effluent and cold feed followed countercurrent flow, and the inlet and outlet temperatures were as follows: T in, hot is equal to 827 degrees Celsius;T out, hot is equal to 486 degrees Celsius;T in, cold is equal to 236 degrees Celsius;T out, cold is equal to 650 degrees Celsius.

[0072] A software tool designed for heat transfer calculations was used to assess the performance of a conventional heat exchanger ("Comp.") and seven examples according to aspects of the present disclosure. Table A below shows a performance comparison in terms of various metrics described below. For each metric, the value for each of the thermal energy recovery assemblies (1-7) according to aspects of the present disclosure is listed relative to the corresponding value for the conventional heat exchanger. Exemplary metrics provided for comparison are the effluent cooling rate, the surface area for heating, the pressure drop on the feed and effluent sides of the corresponding device, and the effluent residence time.

[0073] [Table A]

[0074] As shown in Table A, thermal energy recovery assemblies according to embodiments of the present disclosure may provide improved performance compared to heat exchangers without such heat transfer enhancement features, e.g., in terms of cooling rate, residence time, effluent pressure drop, and / or required cooling surface area. As will become apparent from the present disclosure, higher cooling rate values ​​and lower required surface area, effluent pressure drop, and effluent residence time values ​​may generally be favorable in terms of process performance and / or equipment cost.

[0075] Examples 2(a) to 2(e) Heating and cooling profiles for the 876.8 tonnes per hour (t / h) furnace mixed feed (i.e., steam plus naphtha) and the reaction zone effluent stream (876.8 t / h), along with the energy requirements of the steam cracking reaction, were generated using a process simulation software tool. Feasible energy balances were constructed with and without the use of a thermal energy recovery assembly. According to the model for the complete plant, unit operations downstream of the cracker have a net heat input requirement of 163 megawatts (MW). In addition, it was determined that there was a work requirement of 151 MW for compressors and pumps; this could be supplied by steam recovered using a condensing steam turbine at 41% efficiency or by electricity at 95% efficiency.

[0076] Example 2(a) is a comparative example in which 120 bar steam is generated in a conventional transfer line exchanger (TLE). The mixed feed temperature is initially 180°C because available heat recovery from downstream of the plant can provide this starting temperature. Since the saturated steam temperature is 324°C, the mixed feed can be heated from 180°C to 300°C using 120 bar steam. The remaining steam, representing 244 MW of the 314 MW of heat extracted from the TLE, is used to provide 163 MW of downstream heating duty and 33 MW of mechanical work (i.e., the calculation is: (244 MW - 163 MW) multiplied by 0.41 equals 33 MW); the remaining 118 MW of work is provided by 124 MW of electricity (i.e., the calculation is: 118 divided by 0.95 equals 124 MW). In this comparative example 2(a), there is no direct feed-effluent heat exchange. The feed is electrically heated from 300°C to 650°C, and the cracking reaction is driven by electrical heating. In this comparative example, 682 MW of electricity is required for the reaction plus preheating, resulting in a total power usage of 806 MW in this comparative example.

[0077] In one example according to aspects of the present disclosure, Example 2(b), the mixed feed is preheated to 450°C by feed-effluent heat exchange using a thermal energy recovery assembly according to aspects of the present disclosure. Remaining cooling of the cracked gas is achieved through steam generation, recovering 145 MW, which may provide energy for most of the 18 MW of downstream heating; all of the mechanical work may be performed electrically, which requires 159 MW of electricity according to this example. The feed is electrically heated from 450°C to 650°C, and the cracking reaction is driven by electrical heating. In this example, the total power required for the furnace heating plus the feed is 583 MW, resulting in a total power usage of 760 MW.

[0078] In a further example according to aspects of the present disclosure, Example 2(c), the mixed feed may be heated to a relatively higher temperature of 550°C using a thermal energy recovery assembly according to aspects of the present disclosure. The increased amount of heat transferred from the thermal energy recovery assembly to the feed reduces steam production and reduces the electrical requirements for the feed and cracking reaction. In Example 2(c), the feed is electrically heated from 550°C to 650°C, and the cracking reaction is driven by electrical heating. In this example, 72 MW of steam is generated, which may be used to provide some downstream heating; all of the mechanical work may be performed electrically. In this example, the total power required for the furnace heating plus the feed is 511 MW, resulting in a total power usage of 760 MW.

[0079] In another example according to aspects of the present disclosure, Example 2(d), the feed preheat is increased to 650°C and steam generation is eliminated. A small adjustment to lower the hot side target temperature from 400°C to 392°C illustrates the enthalpy balance point for this feed and target preheat condition. In Example 2(d), the furnace requires 433 MW of electricity. Because no steam is generated, 163 MW of electricity is required for downstream heating and 159 MW of electricity for mechanical work, resulting in a total power consumption of 755 MW.

[0080] In yet a further example according to aspects of the present disclosure, Example 2(e), steam generation is utilized only to the extent that steam is used to preheat the mixed feed to 300 degrees Celsius; the remainder of the preheating is achieved using a tube-in-tube exchanger according to aspects of the present disclosure. There is no steam export. The total electrical heating duty in the furnace is 433 MW, which is the same as in Example 2(d) and 250 MW less than the comparative example (i.e., Example 2(a)). In Example 2(e), 163 MW of electricity is required for downstream heating and 159 MW of electricity is required for mechanical work, resulting in a total power consumption of 755 MW, or 51 MW less than the comparative example (i.e., Example 2(a)).

[0081] A summary of heat and electricity usage for Examples 2(a)-2(e) is provided in Table B below. Comparing Comparative Example 2(a) to Examples 2(b)-2(e), which are examples according to aspects of the present disclosure, shows that the total electrical requirements to operate the cracking process are reduced when an exemplary thermal energy recovery assembly according to aspects of the present disclosure is used to preheat the feed to a temperature of at least 450°C. This demonstrates that a thermal energy recovery assembly consistent with aspects of the present disclosure may facilitate increased efficiency, for example, when a sufficiently high level of preheating is achieved. The power requirements remain essentially the same between Examples 2(b)-2(e), which shows that a thermal energy recovery assembly consistent with aspects of the present disclosure may be used flexibly without loss of efficiency, for example, as long as a minimum level of preheating is achieved.

[0082] [Table B]

[0083] Examples 3(a) to 3(e) Examples 3(a)-3(e) are similar to Examples 2(a)-2(e) above, except that the heat exchange order is reversed for the streams cooling the hot cracked gas. Steam generation is used for the initial portion of the cooling, and feed-effluent heat exchange is used for secondary cooling. A summary of the results of Examples 3(a)-3(e) is provided in Table C below. As with Examples 2(a)-2(e), the results demonstrate that the total power consumed by the cracking process may be reduced through the use of a thermal energy recovery assembly consistent with aspects of the present disclosure. Additionally, a comparison of the results in Tables B and C demonstrates that similar power consumption may be achieved under a wide range of conditions using different sequences combining steam generation with the use of a thermal energy recovery assembly consistent with aspects of the present disclosure.

[0084] [Table C]

[0085] Examples 4(a) to 4(c) In Examples 4(a)-4(c), for the ethane application example, a feed-effluent heat exchanger is used for primary cooling and steam production is used for secondary cooling. Examples 4(a)-4(c) differ with respect to the configuration of the feed-effluent heat exchanger. In Example 4(a), the feed-effluent heat exchanger contains one section and is countercurrent (i.e., completely countercurrent). In Examples 4(b) and 4(c), the feed-effluent heat exchanger contains two sections, with a first cocurrent section and a second countercurrent section. In Example 4(b), the cold feed is first sent to the cocurrent section and then to the countercurrent section. In Example 4(c), the cold feed is first sent to the countercurrent section and then to the cocurrent section. In all three Examples 4(a)-4(c), the reactor effluent flow and feed flow are identical. In all three Examples 4(a)-4(c), the feed is heated from 230°C to 580°C and the reactor effluent is cooled from 849°C to 561°C. The configurations of Examples 4(a)-4(c) are not economically optimized and are presented primarily to illustrate the trade-offs that may exist between different conceptual configurations. A summary of the results of Examples 4(a)-4(c) is provided below in Table D. Tube metal temperatures are given in °C for each metric, while values ​​for other metrics are listed relative to the corresponding values ​​in Example 4(a). These comparative metrics are heat transferred, internal tube pressure drop (i.e., effluent pressure drop), effluent residence time, cooling rate, and required heating surface area.

[0086] The highest maximum tube surface temperature at the inner tube is expected for Example 4(a), while the lowest maximum tube surface temperature is expected for Example 4(b). As a result, the risk of entering a regime where coking can occur due to precracking on the outer tube surface and enhanced chemical coking on the inner tube surface is highest for the configuration represented by Example 4(a). The resulting tube surface temperature for Example 4(c) is between Examples 4(a) and 4(b), but closer to 4(b). At the cold end of the assembly, the lowest internal tube temperatures are expected for Examples 4(a) and 4(c), while Example 4(b) exhibits higher internal tube temperatures. For the ethane application examples presented herein, the risk of significant condensation coking is low for any of Examples 4(a)-4(c).

[0087] With regard to the effluent pressure drop inside the tubes, which has an effect on cracking selectivity, it is lowest for Example 4(a), followed by Example 4(c), and significantly higher for Example 4(b). The higher effluent pressure drop in Example 4(b) results from the significantly longer tube length compared to Examples 4(a) and 4(c).

[0088] The most promising values ​​for residence time and cooling rate, both of which relate to cooling the effluent to a temperature of 650°C, were found for the configuration of Example 4(b), which had the largest temperature difference between the effluent and the feed at the effluent inlet.

[0089] Considering the large heat transfer surface required for Example 4(b) and the high tube metal temperatures observed for Example 4(a), the configuration as defined for Example 4(c) may be the best solution for the application case presented here.

[0090] [Table D]

[0091] Examples 5(a) to 5(c) In Examples 5(a)-5(c), for the naphtha application example, a feed-effluent heat exchanger is used for primary cooling, and steam generation is used for secondary cooling. Examples 5(a)-5(c) differ with respect to the configuration of the feed-effluent heat exchanger. In Example 5(a), the feed-effluent heat exchanger contains one section and is countercurrent (i.e., completely countercurrent). In Examples 5(b) and 5(c), the feed-effluent heat exchanger contains two sections, with a first cocurrent section and a second countercurrent section. In Example 5(b), the cold feed is first sent to the cocurrent section and then to the countercurrent section. In Example 5(c), the cold feed is first sent to the countercurrent section and then to the cocurrent section. In all three Examples 5(a)-5(c), the reactor effluent flow and feed flow are identical. In all three Examples 5(a)-5(c), the feed is heated from 223°C to 594°C and the reactor effluent is cooled from 862°C to 539°C. The configurations of Examples 5(a)-(c) are not economically optimized and are presented primarily to illustrate the trade-offs that may exist between different conceptual configurations. A summary of the results of Examples 5(a)-5(c) is provided below in Table E. Tube metal temperatures are given in °C for each metric, while values ​​for other metrics are listed relative to the corresponding values ​​in Example 5(a). These comparative metrics are heat transferred, internal tube pressure drop (i.e., effluent pressure drop), effluent residence time, cooling rate, and required heating surface area.

[0092] The highest maximum tube surface temperature at the inner tube is expected for Example 5(a), while the lowest maximum tube surface temperature is expected for Example 5(b). As a result, the risk of entering a regime where coking can occur due to precracking on the outer tube surface and enhanced chemical coking on the inner tube surface is highest for the configuration represented by Example 5(a). The resulting tube surface temperature for Example 5(c) is between Examples 5(a) and 5(b), but closer to 5(b). At the cold end of the assembly, the lowest internal tube temperatures are expected for Examples 5(a) and 5(c), while Example 5(b) exhibits higher internal tube temperatures. The distance to the temperature below which the risk of enhanced condensation coking increases is smallest for Examples 5(a) and 5(c).

[0093] With regard to the effluent pressure drop, which has an effect on cracking selectivity, it is lowest for Example 5(a), followed by Example 5(c), and significantly higher for Example 5(b). The higher effluent pressure drop in Example 5(b) results from the significantly longer pipe length compared to Examples 5(a) and 5(c).

[0094] [Table E]

[0095] For residence time and cooling rate, both of which relate to cooling the effluent to a temperature of 650°C, the most promising values ​​were found for the configuration of Example 5(b), which had the largest temperature difference between the effluent and the feed at the effluent inlet.

[0096] Considering the larger heat transfer surface required for Example 5(b) and the higher tube metal temperatures observed for Example 5(a), the configuration as specified for Example 5(c) may be the best solution for the application case presented herein, as long as 310°C is acceptable as the minimum internal tube temperature for this naphtha feedstock. If higher temperatures are required to prevent condensation coking, the configuration as specified for Example 5(b) may be the preferred solution. In general, one skilled in the art would select between the configurations of Examples 5(a)-5(c) depending on the specific requirements and technical and economic boundary conditions.

[0097] While several illustrative aspects of the present disclosure have been described above, it should be apparent to those skilled in the art that the foregoing has been presented by way of example only, and is illustrative rather than limiting. Numerous modifications and other aspects are within the purview of those skilled in the art and are contemplated as falling within the scope of the present disclosure. In particular, while many of the examples presented herein involve specific combinations of method acts or system elements, it should be understood that these acts and their elements may be combined in other manners to achieve the same purpose. It should be recognized by those skilled in the art that the parameters and configurations described herein are exemplary, and that the actual parameters and / or configurations will depend on the specific application in which the disclosed systems and techniques are used. Those skilled in the art will also recognize or be able to ascertain, using no more than routine experimentation, equivalents to specific aspects of the present disclosure. It should therefore be understood that the aspects described herein are presented by way of example only, and that, within the scope of any appended claims and equivalents thereof, aspects of the present disclosure may be practiced otherwise than as specifically described.

[0098] Furthermore, the scope of the present disclosure should be construed as covering the above and various modifications, combinations, additions, alterations, etc. to the above-described embodiments, which should be considered to be within the scope of the present disclosure. Thus, various features and characteristics as discussed herein may be selectively interchanged and applied to other illustrated and non-illustrated embodiments; and numerous variations, modifications, and additions may further be made thereto without departing from the spirit and scope of the present disclosure as set forth in the appended claims.

[0099] An exemplary thermal energy recovery assembly A for recovering thermal energy from a hot reactor effluent to heat a feed to an electro-reactor may include an inner tube having a first inlet configured to receive the hot reactor effluent from the electro-reactor and an outer tube disposed around the inner tube to enclose an annulus around the inner tube. The annulus may have a second inlet configured to receive the feed to the electro-reactor, and the annulus may be configured to use the feed to the electro-reactor as a coolant to recover thermal energy from the hot reactor effluent before the feed is provided to the electro-reactor. The annulus may be configured to enhance heat transfer from the hot reactor effluent to the feed within the annulus.

[0100] In some embodiments, the hot reactor effluent may reach the first inlet through a gas inlet chamber or other connector. In some embodiments, cooling may be provided to the gas inlet chamber or other connector. In some embodiments, a gas chamber may connect one or more cracking coils to one or more inner tubes. In some embodiments, headers may be provided to connect feeds to more than one annulus. In some embodiments, cracked and cooled gas from more than one inner tube may be collected using a header. In some embodiments, heated feeds from more than one annulus may be combined via a header. In some embodiments, multiple annulus may be contained within a single mechanical device that may receive hot effluent from multiple cracking coils through gas inlet chambers or other connectors and cold feeds from a feed header.

[0101] Exemplary assembly A as described above, wherein the outer tube includes at least one heat transfer enhancement for enhancing heat transfer from the inner tube to the annulus.

[0102] The above-described example assembly A, wherein the outer tube comprises a first stage and the at least one heat transfer enhancement comprises one or more of plate impingement, piccolo impingement, turbulence promoters, or increased surface area.

[0103] In the above-described exemplary assembly A, heat transfer enhancement through impingement can refer to the flow of fluid through the outer tube; the average direction of that flow as it travels from inlet to outlet can be substantially parallel to the inner tube, while being intentionally directed toward the inner tube, e.g., using geometric features introduced within the annulus. In some embodiments, this directed (impinging) flow can be, for example, perpendicular to the inner tube, or can be directed toward the inner tube at an angle greater than 30 degrees relative to the axis of the inner tube; while its velocity can be relatively greater than the superficial 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, geometric features that promote impingement can include, for example, nozzles and / or openings oriented toward the inner tube; and / or obstacles placed in the flow path that redirect the fluid from a direction more parallel to the inner tube toward more directly toward the outer surface of the inner tube; etc. These exemplary features may be implemented in a periodic manner, resulting in, for example, impingement zones spaced along the length and / or circumference of the inner tube. Applicant has discovered that the introduction of such impingement features increases the heat transfer rate relative to the heat transfer rate achieved by parallel flow through the outer tube. Furthermore, Applicant has discovered that for a suitable level of heat transfer enhancement, the ratio of impinging flow velocity to superficial velocity may be greater than 2, greater than 5, or greater than 10. In the case of a nozzle or orifice through which flow is directed, the impinging flow velocity may be approximated as the volumetric flow rate divided by the total flow area defined by the nozzle or orifice. Additionally, heat transfer enhancement may be found to be more favorable when the distance between the impingement-inducing feature (e.g., nozzle or opening 54) and the inner tube is from about the diameter of the nozzle or opening 54 to about 12 times the diameter, from about the diameter of the nozzle or opening 54 to about 10 times the diameter, or from about 2 times the diameter to about 8 times the diameter. Examples of impingement features may include plate impingement and / or piccolo impingement.

[0104] Exemplary assembly A, as described above, includes a plate impingement disposed between an upstream end and a downstream end of the outer pipe. The plate impingement may include a first channel having a stage inlet at its upstream end and closed to flow at its downstream end. The plate impingement may also include a second channel having a stage outlet at its downstream end. The second channel may be disposed between the first channel and the inner pipe. The plate impingement may further include a wall separating the first channel from the second channel. The wall may define an opening for fluidly connecting the first and second channels. The plate impingement may be configured to receive a feed through the stage inlet, flow the feed from the first channel to the second channel through the opening in the wall to impinge on the outer surface of the inner pipe, and discharge the feed through the stage outlet of the second channel.

[0105] In the above-described exemplary assembly A, the outer tube includes a piccolo impingement. The piccolo impingement may include an upstream partition disposed around and within the inner tube; and a downstream partition disposed around and within the inner tube downstream of the upstream partition within the annulus. The downstream partition may define at least one stage outlet. The piccolo impingement may also include a chamber defined within and around the inner tube between the upstream and downstream partitions; and a piccolo tube that may be parallel or angled relative to the inner tube, and / or may be straight, curved, or bent, and / or offset from the inner tube. The piccolo tube may extend from the upstream partition to the downstream partition through the chamber. The piccolo tube may include a stage inlet for receiving an incoming feed; and a plurality of openings defined in the piccolo tube, which may be oriented toward the outer surface of the inner tube. The piccolo impingement may be configured to receive a feed from a stage inlet, flow the feed from the piccolo tube into the chamber through the plurality of openings, impinge the flow onto an outer surface of the inner tube, and / or discharge the feed from the chamber through the at least one stage outlet.

[0106] The above-described exemplary assembly A, wherein the at least one stage includes a first stage and a second stage, and is one or more of the following: (1) the inner tube of the first stage has a first outlet and is configured to pass hot reactor effluent from the first inlet to the first outlet; the outer tube of the first stage has a second outlet and is configured to pass feed from the second inlet to the second outlet; 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 is configured to use plate impingement, piccolo impingement, turbulence promoters, or a second stage in series with the first stage, the second stage including at least one heat transfer enhancement including one or more of the increased surface areas; or (3) the second stage including an inner tube having a first inlet and a first outlet and configured to channel reactor effluent from the first inlet of the second stage to the first outlet of the second stage; and an outer tube having a second inlet and a second outlet and configured to channel feed from the second inlet of the second stage to the second outlet of the second stage; wherein 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.

[0107] The above-described example assembly A, wherein the at least one heat transfer enhancement portion of the first stage includes a first impingement hole having a first diameter, and the at least one heat transfer enhancement portion of the second stage includes a second impingement hole having a second diameter different from the first diameter.

[0108] Exemplary assembly A as described above, where the inner tube includes a heat transfer enhancement.

[0109] The inner tube has a first outlet and is configured to pass hot reactor effluent from the first inlet to the first outlet; the outer tube has a second outlet and is configured to pass feed from the second inlet to the second outlet; and one of the second inlet being adjacent to the first outlet and the second outlet being adjacent to the first inlet, or the first inlet being adjacent to the second inlet and the first outlet being adjacent to the second outlet; exemplary assembly A described above.

[0110] Exemplary Assembly A, described above, in which a thermal energy recovery assembly includes a plurality of parallel inner tubes, each inner tube disposed within an outer tube, and each outer tube having one or more, at least one of plate impingement, piccolo impingement, or turbulence promoters, for enhancing heat transfer from the inner tube to an annulus defined within the outer tube. In some embodiments, a thermal energy recovery assembly may include a plurality of parallel inner tubes, each inner tube disposed within the outer tube, and the outer tubes, and optionally the inner tubes, have one or more heat transfer augmentations for enhancing heat transfer from the inner tube to an annulus defined within the outer tube.

[0111] The above-described exemplary assembly A, wherein the thermal energy recovery assembly is configured to cool the hot reactor effluent at a cooling rate of at least 2.5 degrees Kelvin / msec, at least 3.5 degrees Kelvin / msec, at least 4.5 degrees Kelvin / msec, at least 5 degrees Kelvin / ms, or at least 5.5 degrees Kelvin / ms; for example, where the cooling rate may be defined as the hot reactor effluent inlet temperature (Kelvin) minus 923 K divided by the residence time required to cool the hot reactor effluent temperature to 923 K, unless the hot reactor effluent inlet temperature (Kelvin) is less than 923 K or the cooled reactor effluent temperature is greater than 923 K, in which case the cooling rate may be defined as the hot reactor effluent inlet temperature (Kelvin) minus the temperature of the cooled reactor effluent as it exits the thermal energy recovery assembly divided by the residence time of the effluent within the assembly. In some embodiments, the thermal energy recovery assembly may be configured such that the pressure drop of the hot reactor effluent passing through the thermal energy recovery assembly is less than 0.35 bar, less than 0.30 bar, less than 0.25 bar, or less than 0.20 bar; such that the residence time of the hot reactor effluent in the thermal energy 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 such that the pressure drop of the feed passing through the thermal energy recovery assembly is less than 15 bar, less than 12 bar, less than 10 bar, less than 8 bar, or less than 6 bar.

[0112] Exemplary assembly A described above, wherein the thermal energy recovery assembly is configured to preheat the feed to at least 350° Celsius, at least 375° Celsius, at least 400° Celsius, at least 425° Celsius, at least 450° Celsius, at least 475° Celsius, at least 500° Celsius, at least 525° Celsius, at least 550° Celsius, at least 575° Celsius, at least 600° Celsius, at least 625° Celsius, or at least 650° Celsius.

[0113] Exemplary Assembly A described above, wherein the hot reactor effluent enters the thermal energy recovery assembly at a temperature greater than 575° Celsius, greater than 600° Celsius, greater than 610° Celsius, greater than 620° Celsius, greater than 630° Celsius, greater than 640° Celsius, or greater than 650° Celsius.

[0114] The furnace assembly for heating the feed to provide a hot reactor effluent may include the exemplary thermal energy recovery assembly A described above; and an electrically powered reactor including a reaction zone configured to heat one or more feeds selected from ethane, propane, butane, condensate, light naphtha, heavy naphtha, gas oil, pyrolysis oil, materials derived from the processing of refinery streams, Fischer-Tropsch products, plastic waste, or biofeedstock to their cracking temperatures.

[0115] Method B for producing olefins may include feeding a hydrocarbon feed to an outer tube of a thermal energy recovery assembly; and heating the hydrocarbon feed in the outer tube of the thermal energy recovery assembly to output a preheated hydrocarbon feed. Exemplary Method B may also include feeding 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 hot reactor effluent including cracked hydrocarbons and olefins. Exemplary Method B may further include feeding the hot reactor effluent to an inner tube of the thermal energy recovery assembly; and feeding an additional hydrocarbon feed to the outer tube of the thermal energy recovery assembly. Exemplary Method B may also include heating the additional hydrocarbon feed by transferring heat from the hot reactor effluent to the additional hydrocarbon feed through the thermal energy recovery assembly.

[0116] The above-mentioned exemplary method B, which is one or more of the following: (1) feeding the hot reactor effluent to the inner tube of the thermal energy recovery assembly comprises quenching the hot reactor effluent via heat transfer to the additional hydrocarbon feed; or (2) heating the hydrocarbon feed in the outer tube of the thermal energy recovery assembly comprises preheating the hydrocarbon feed via heat transfer from the hot reactor effluent to the hydrocarbon feed. The above-mentioned exemplary method B, further comprising enhancing heat transfer to the additional hydrocarbon feed by providing heat transfer enhancements, including one or more of plate impingement, piccolo impingement, or turbulence promoters, on one or more of the outer tube or the inner tube.

[0117] Exemplary Method B, as described above, wherein supplying the hot reactor effluent to the inner tube of the thermal energy recovery assembly comprises supplying the hot reactor effluent to the inner tube of the thermal energy recovery assembly at a temperature of at least 350° Celsius, at least 375° Celsius, at least 400° Celsius, at least 425° Celsius, at least 450° Celsius, at least 475° Celsius, at least 500° Celsius, at least 525° Celsius, at least 550° Celsius, at least 575° Celsius, at least 600° Celsius, at least 625° Celsius, or at least 650° Celsius.

[0118] Exemplary Method B, as described above, wherein heating the hydrocarbon feed in the outer tube of the thermal energy recovery assembly to output the preheated hydrocarbon feed comprises heating the hydrocarbon feed to a temperature of at least 350° Celsius, at least 375° Celsius, at least 400° Celsius, at least 425° Celsius, at least 450° Celsius, at least 475° Celsius, at least 500° Celsius, at least 525° Celsius, at least 550° Celsius, at least 575° Celsius, at least 600° Celsius, at least 625° Celsius, or at least 650° Celsius.

Claims

1. providing a hydrocarbon feed to an outer tube of a thermal energy recovery assembly; heating the hydrocarbon feed within the outer tube of the thermal energy recovery assembly to output a preheated hydrocarbon feed; feeding the preheated hydrocarbon feed to an electric 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 hot reactor effluent comprising cracked hydrocarbons and olefins; supplying the hot reactor effluent to an inner tube of the thermal energy recovery assembly; and cooling the hot reactor effluent within the inner tube of the thermal energy recovery assembly by transferring heat to the hydrocarbon feed. at least one cooling stage in a thermal energy recovery assembly, characterized by whereby the external temperature of the inner tube in the thermal energy recovery assembly remains below 720°C and the internal temperature of the inner tube in the thermal energy recovery assembly remains above 160°C; A method for producing olefins.

2. 10. The method of claim 1, wherein the external temperature of the inner tube remains below 720°C for operation with ethane-type feedstocks, below 700°C for operation with propane-type feedstocks, below 680°C for operation with butane-type feedstocks, below 660°C for operation with naphtha-type feedstocks, and below 640°C for operation with feedstocks heavier than naphtha.

3. 10. The method of claim 1, wherein the internal temperature of the inner tube remains above 160°C for operation with ethane-type feedstocks, above 170°C for operation with propane-type feedstocks, above 180°C for operation with butane-type feedstocks, and above 270°C for operation with naphtha-type or heavier feedstocks.

4. 10. The process of any one of the preceding claims, wherein the hot reactor effluent is first partially cooled against the hydrocarbon feed through a co-current section and then further cooled against the hydrocarbon feed in a counter-current section.

5. 4. The process of any one of claims 1 to 3, wherein the hot reactor effluent is first cooled against the hydrocarbon feed through a co-current flow section, further cooled through a steam generation section, and then further cooled against the hydrocarbon feed in a counter-current flow section.

6. 6. The process of claim 4 or 5, wherein the hydrocarbon feed is first passed through a co-current section and then through a counter-current section.

7. 6. The process of claim 4 or 5, wherein the hydrocarbon feed is first passed through a countercurrent section and then through a cocurrent section.

8. 6. The method of claim 4 or 5, wherein the countercurrent section is a separate piece of equipment and is a tube-in-tube or shell-and-tube heat exchanger.

9. an outer tube; and inner tube Including, a hydrocarbon feed is supplied to an electric cracking furnace including a reaction zone for heating the hydrocarbon feed; the inner tube includes a first inlet configured to receive hot reactor effluent from the electric cracking furnace; and the outer tube is disposed around the inner tube to surround an annulus around the inner tube, the annulus including a second inlet configured to receive the hydrocarbon feed; A thermal energy recovery assembly for operating the method according to any one of the preceding claims.

10. 10. The thermal energy recovery assembly of claim 9, wherein the annulus includes at least one heat transfer enhancement for enhancing heat transfer from the inner tube to the annulus.

11. The thermal energy recovery assembly of claim 10 , wherein the at least one heat transfer enhancement comprises one or more of impingement, turbulence promoters, high shear inducing geometries, or increased surface areas.

12. The annular portion includes a plate impingement between the upstream end and the downstream end, the plate impingement comprising: a first channel having a stage inlet at its upstream end and closed to flow at its downstream end; a second channel disposed between the first channel and the inner pipe, the second channel having a stage outlet at the downstream end; a wall separating the first channel from the second channel, the wall defining an opening for fluidly connecting the first channel and the second channel; and the plate impingement is configured to receive a feed through the stage inlet, flow the feed from the first channel to the second channel through the opening in the wall, impinge the feed flow on an outer surface of the inner tube, and discharge the feed through the stage outlet of the second channel.

12. The thermal energy recovery assembly of claim 11.

13. The annular portion includes a piccolo impingement, an upstream partition disposed around the inner pipe and within the outer pipe; a downstream partition disposed within the annulus downstream of the upstream partition, about the inner pipe and within the outer pipe, the downstream partition defining at least one stage outlet; a chamber defined within the outer tube and around the inner tube between the upstream partition and the downstream partition; and a piccolo tube offset from the inner tube the piccolo tube extends through the chamber from the upstream partition to the downstream partition; the piccolo tube includes a stage inlet for receiving an incoming feed; the piccolo tube includes a plurality of openings defined therein; the piccolo impingement is configured to receive the feed from the stage inlet, flow the feed from the piccolo tube into the chamber through the plurality of openings, and discharge the feed from the chamber through the at least one stage outlet.

12. The thermal energy recovery assembly of claim 11.

14. 14. The thermal energy recovery assembly of claim 9, wherein the thermal energy recovery assembly comprises a plurality of parallel inner tubes; each inner tube is disposed within an outer tube; and each outer tube has one or more of impingement, turbulence promoters, high shear inducing geometries, or increased surface areas to enhance heat transfer from the inner tubes to an annulus defined within the outer tubes.

15. Use of a thermal energy recovery assembly according to any one of claims 9 to 14 for carrying out a method according to any one of claims 1 to 8.

Images