Systems and methods for recovering heat energy generated by electricity using molten salts in industrial processes

Abstract

The invention includes systems and methods for chemical production that utilize an electric furnace and a molten salt loop to extract thermal energy from effluent exiting the furnace to preheat feedstock entering the furnace. Some such systems and methods utilize a feed preheat (FPH) heat exchanger through which the feedstock passes before entering the furnace, and an effluent heat exchanger through which the effluent passes after exiting the furnace, such that molten salt can be circulated (1) through the effluent heat exchanger to extract thermal energy from the effluent and (2) through the FPH heat exchanger to transfer the extracted thermal energy to the feedstock.

Description

Technical Field

[0001] This disclosure generally relates to the recovery of heat energy in industrial processes, and more specifically, but not in a limited way, to systems, methods, and processes in which heat energy is recovered using molten salt (e.g., for the production of chemicals). Background Technology

[0002] Open-flame heaters or combustion furnaces are used to incinerate or burn specific fuels to provide heat for a variety of purposes. For example, in chemical plants, open-flame heaters can be used in olefin cracking furnaces, MeOH and NH3 reforming furnaces, dehydrogenation heaters, etc. To further illustrate, these furnaces can provide reaction heat for chemical synthesis, energy for heating one or more process streams, energy for evaporating liquids (e.g., boiling water), energy for doing work via steam (e.g., driving compressors or pumps), or energy for other process operations within the overall chemical production facility. Such incineration or combustion of fuel results in the generation of flue gas, which can subsequently be used to recover heat. However, the flue gas contains CO2, which can be harmful to the environment.

[0003] The desire to reduce greenhouse gas emissions has recently spurred various approaches to reduce reliance on open-flame furnaces in chemical production. One such approach is to replace open-flame heating with electric heating. For example, WO2020 / 150244 describes the use of electrified furnaces in ethylene production and illustrates how equipment using electrified furnaces may affect other aspects of thermal integration, such as steam generation and furnace feed preheating, compared to equipment using conventional fuel incinerators. A particular challenge lies in effectively utilizing the heat contained in the furnace's products to preheat the furnace feed. Another example, WO2023 / 025737, proposes a solution to this challenge using specially designed feed-effect heat exchangers. Such heat exchangers may limit design flexibility or have other drawbacks that make them unsuitable for all applications. The inventors recognize the need to design alternative solutions to efficiently and reliably transfer heat from the process effect to the process feed of the electrically heated furnace. Summary of the Invention

[0004] In high-temperature chemical production processes where carbon dioxide (CO2) emissions need to be reduced or eliminated, the replacement of open-flame furnaces with electric furnaces has been proposed. Such furnaces can, for example, use carbon-free electricity, such as renewable electricity, as their energy source. However, the use of electric furnaces may require process redesign, which can be complex, expensive, and pose risks to the original process system.

[0005] Conventional open-flame furnaces used in chemical production typically utilize steam generation as a means of cooling the furnace effluent, such as in transfer line heat exchangers or waste heat boilers, while simultaneously using the heat contained in the furnace flue gas for other tasks, such as preheating process feed. The first heat exchanger used to cool the hot furnace effluent can be called a transfer line heat exchanger (TLE), regardless of the cooling method. In electric furnaces, no flue gas is generated, so the process feed must be preheated by other means. From an energy efficiency standpoint, it is generally desirable to use the heat contained in the furnace process effluent to provide such preheating.

[0006] The systems and methods of this disclosure alternatively utilize molten salt as the heat transfer fluid in the TLE. For example, using molten salt as the heat transfer fluid within the TLE allows for smaller TLE dimensions, higher heat transfer coefficients (e.g., U-values) for faster cooling of the effluent (which can lead to higher yields), and greater design flexibility. For example, in at least some configurations of this system, the molten salt heat exchanger is a shell-and-tube heat exchanger configured for the process flow to flow on the tube side of the heat exchanger (through the tubes) and for the molten salt to flow on the shell side of the heat exchanger (through the shell outside the tubes), making it relatively easy to clean any coke formation (e.g., through the interior of the tubes of a hydraulically jetted heat exchanger). This represents an advantage over conventional feed / effluent heat exchangers (TLEs), in which process steam flows on the shell side, making coking in the shell significantly more difficult to clean.

[0007] Some configurations of this system include: an electric furnace, a feed preheating (FPH) heat exchanger, an effluent heat exchanger, and a molten salt circuit. In some such configurations, the electric furnace has a fluid inlet, a fluid outlet, and multiple reactor tubes extending through the furnace between the fluid inlet and the fluid outlet. In some such configurations, the FPH heat exchanger includes a feed inlet, a feed outlet, a salt inlet, and a salt outlet, and is configured such that the fluid feed is in thermal communication but not fluid communication with the molten salt when the fluid feed flows from the feed inlet to the feed outlet and the molten salt flows from the salt inlet to the salt outlet, wherein the feed outlet of the FPH heat exchanger is in fluid communication with the fluid inlet of the furnace. In some such configurations, the effluent heat exchanger includes an effluent inlet, an effluent outlet, a salt inlet, and a salt outlet. The effluent heat exchanger is configured such that when the effluent feed flows from the effluent inlet to the effluent outlet and the molten salt flows from the salt inlet to the salt outlet, the effluent feed and the molten salt are in thermal but not fluid communication, wherein the effluent inlet of the effluent heat exchanger is in fluid communication with the fluid outlet of the furnace. In some such configurations, the molten salt circuit includes: a first conduit extending from the salt outlet of the effluent heat exchanger to the salt inlet of the FPH heat exchanger; a second conduit extending from the salt outlet of the FPH heat exchanger to the salt inlet of the effluent heat exchanger; and molten salt; wherein the molten salt circuit is configured to sequentially circulate the molten salt through the effluent heat exchanger to receive heat energy from the effluent, through the first conduit, through the FPH heat exchanger to transfer heat energy from the molten salt to the fluid feed to preheat the fluid feed before it enters the furnace, and through the second conduit.

[0008] In some of the aforementioned configurations of this system, the effluent heat exchanger is a first effluent heat exchanger, and the system further includes a second effluent heat exchanger, which includes an effluent inlet, an effluent outlet, a heat transfer fluid (HTF) inlet, and an HTF outlet. The second effluent heat exchanger is configured such that when the effluent feed flows from the effluent inlet to the effluent outlet and the HTF flows from the HTF inlet to the HTF outlet, the effluent feed is in thermal communication with the HTF but not in fluid communication, wherein the effluent inlet of the second effluent heat exchanger is in fluid communication with the fluid outlet of the first effluent heat exchanger. In some such configurations, the FPH heat exchanger is a first FPH heat exchanger, and the system further includes a second feed preheating (FPH) heat exchanger, which includes a feed inlet, a feed outlet, an HTF inlet, and an HTF outlet. The second FPH heat exchanger is configured such that when the fluid feed flows from the feed inlet to the feed outlet and the HTF flows from the HTF inlet to the HTF outlet, the fluid feed is in thermal communication with the HTF but not in fluid communication, wherein the feed outlet of the second FPH heat exchanger is in fluid communication with the feed inlet of the first FPH heat exchanger. Some such configurations further include: a secondary FPH loop comprising: a first HTF conduit extending from the HTF outlet of the second effluent heat exchanger to the HTF inlet of the second FPH heat exchanger; a second HTF conduit extending from the HTF outlet of the second FPH heat exchanger to the HTF inlet of the second effluent heat exchanger; and a heat transfer fluid (HTF), optionally wherein the HTF comprises H2O or heat transfer oil; wherein the secondary FPH loop is configured to cause the HTF to circulate sequentially through the second effluent heat exchanger to receive heat energy from the effluent, through the first HTF conduit, through the second FPH heat exchanger to transfer heat energy from the HTF to the fluid feed to preheat the fluid feed before it enters the first FPH heat exchanger, and through the second HTF conduit.

[0009] In some of the aforementioned configurations of this system, the molten salt circuit further includes a pump configured to circulate the molten salt.

[0010] In some of the aforementioned configurations of this system, the molten salt circuit further includes an accumulator container in fluid communication with the first conduit and the second conduit. In some such configurations, the accumulator container is located at a low point in the molten salt circuit.

[0011] In some of the aforementioned configurations of this system, the molten salt circuit further includes a heater configured to heat the molten salt when it is in the accumulator container.

[0012] In some embodiments of this steam cracking method, the method includes: guiding a hydrocarbon-containing fluid feed through a feed preheating (FPH) heat exchanger; guiding the hydrocarbon-containing fluid feed from the FPH heat exchanger to a fluid inlet of an electric furnace and through multiple coils to heat the fluid feed to the reaction temperature and initiate the cracking reaction, the fluid feed comprising hydrocarbon feedstock and steam; guiding the effluent from the furnace fluid outlet to the effluent inlet of an effluent heat exchanger to reduce the effluent temperature (e.g., to a temperature below the reaction temperature) and slow down or stop the cracking reaction, the effluent heat exchanger including a salt inlet and a salt outlet, and configured such that when the effluent feed is discharged from the effluent outlet... When the effluent feed flows from the inlet to the outlet and the molten salt flows from the inlet to the outlet, the effluent feed is in thermal communication with the molten salt but not in fluid communication; molten salt at an elevated temperature is directed from the outlet of the effluent heat exchanger to the inlet of the FPH heat exchanger to transfer heat from the molten salt to the fluid feed, the FPH heat exchanger being configured such that when the fluid feed flows from the inlet to the outlet and the molten salt flows from the inlet to the outlet, the fluid feed is in thermal communication with the molten salt but not in fluid communication; and molten salt at a decreased temperature is directed from the outlet of the FPH heat exchanger to the inlet of the effluent heat exchanger to absorb heat from the effluent. In some such embodiments, the method further includes adding steam to the hydrocarbon-containing fluid feed before directing it into the furnace (e.g., before directing it into the FPH heat exchanger).

[0013] In some of the foregoing embodiments of this method, the temperature increase is greater than 500°C and the temperature decrease is less than 400°C.

[0014] In some of the foregoing embodiments of this method, the effluent heat exchanger is a first effluent heat exchanger, and the method further includes: guiding the effluent feed from the effluent outlet of the first effluent heat exchanger to the effluent inlet of a second effluent heat exchanger to further reduce the temperature of the effluent feed, the second effluent heat exchanger including a heat transfer fluid (HTF) inlet and an HTF outlet, and configured such that when the effluent feed flows from the effluent inlet to the effluent outlet and the HTF flows from the HTF inlet to the HTF outlet, the effluent feed is in thermal communication with the HTF but not in fluid communication. In some such configurations, the FPH heat exchanger is a first FPH heat exchanger, and the method further includes: guiding the fluid feed through a second feed preheating (FPH) heat exchanger before guiding the fluid feed through the first FPH heat exchanger. The second FPH heat exchanger includes an HTF inlet and an HTF outlet and is configured such that when the fluid feed flows through the second FPH heat exchanger and the HTF flows from the HTF inlet to the HTF outlet, the fluid feed is in thermal communication with the HTF but not in fluid communication with it; guiding the HTF at an elevated temperature from the HTF outlet of the second effluent heat exchanger to the HTF inlet of the second FPH heat exchanger to transfer heat from the HTF to the fluid feed; and guiding the HTF at a decreased temperature from the HTF outlet of the second FPH heat exchanger to the HTF inlet of the second effluent heat exchanger to absorb heat from the feed effluent. In some such configurations, the HTF comprises H2O or heat transfer oil.

[0015] In some of the foregoing embodiments of this method, the heat capacity rate (C) of the molten salt is... S The heat capacity of the fluid feed (C) is greater than that of the feed fluid. F ), optionally, C S It is C F More than 150% of the total, and additionally, C is optional. S C F More than 200%.

[0016] In some of the foregoing embodiments of this method, the heat capacity of the molten salt (C) S The heat capacity of the effluent feed is greater than that of the feed (C). F ), optionally, C S C F More than 120% of the total, and additionally, C can be selected from the following locations. S C F More than 140%.

[0017] The term "connection" is defined as a link, although not necessarily a direct or mechanical connection; the two items in a "connection" may be integral to each other. Unless expressly required otherwise in this disclosure, the terms "an" and "a" are defined as one or more / a kinds. As will be understood by those skilled in the art, the term "substantially" is defined as most, but not necessarily all, of the specified contents (and includes the specified contents; for example, substantially 90 degrees includes 90 degrees, and substantially parallel includes parallel). In any embodiment of the apparatus, kit, and method of the present invention, the term "substantially" may be replaced by the specified "within [percentage] of," wherein the percentage includes 0.1%, 1%, 5%, and / or 10%.

[0018] The terms “comprises” (and any form of inclusion, such as “comprises” and “comprising”), “has” (and any form of having, such as “has” and “having”), “includes” (and any form of inclusion, such as “includes” and “including”), and “contains” (and any form of containing, such as “contains” and “containing”) are open-ended connecting verbs. Therefore, an apparatus or kit that “comprises,” “has,” “includes,” or “contains” one or more elements possesses, but is not limited to, those elements. Similarly, a method that “comprises,” “has,” “includes,” or “contains” one or more steps possesses, but is not limited to, those steps.

[0019] In addition, a device, apparatus or system configured in a certain way is configured at least in that way, but may also be configured in other ways besides those specifically described.

[0020] Any embodiment of this device and method may consist of or substantially consist of any of the described steps, elements and / or features, rather than including / comprises / contains / has any of the described steps, elements and / or features. Therefore, in any claim, the terms “consisting of” or “substantially consisting of” may replace any of the aforementioned open-ended connecting verbs in order to change the scope of the given claim from the scope that would have been used with the open-ended connecting verbs.

[0021] Details relating to the above description and other implementation schemes are presented below.

[0022] Some details relating to aspects of this disclosure have been described above, and other details are described below. Further embodiments, advantages, and features of this disclosure will become apparent upon review of the entire application (including the description of the drawings, detailed description, and claims). Attached Figure Description

[0023] The following figures are shown by way of example and not limitation. For the sake of brevity and clarity, each feature of a given structure is not always labeled in every drawing in which the structure appears. The same reference numerals or figure marks do not necessarily indicate the same structure. Instead, the same figure marks may be used to indicate similar features or features having similar functions, and different figure marks may also be used in this way. Dimensional drawings are drawn to scale (unless otherwise stated), meaning that, at least for the embodiments depicted in the figures, the dimensions of the depicted elements are accurate relative to each other.

[0024] Figure 1 A block diagram depicts a general steam pyrolysis equipment or method.

[0025] Figure 2 A schematic diagram of a conventional hydrocarbon vapor cracking system is depicted.

[0026] Figure 3 Depicting Figure 2 A schematic diagram of an example of the convection section of a conventional hydrocarbon steam cracking furnace system.

[0027] Figure 4 A schematic diagram depicts a first example of this system using molten salt as the heat transfer fluid in a transfer line heat exchanger (TLE).

[0028] Figure 5 Depicting Figure 4 The system diagram illustrates certain characteristics modeled for a given implementation of the system.

[0029] Figure 6 A schematic diagram of a second example of the system is depicted, which utilizes molten salt as the heat transfer fluid in the primary TLE and the secondary heat transfer fluid for the secondary TLE feed preheating loop.

[0030] Figure 7 Depicting Figure 6 The system diagram illustrates certain characteristics modeled for a given implementation of the system.

[0031] Figure 8 A schematic diagram of the molten salt circuit for some configurations of this system is shown. Detailed Implementation

[0032] Now refer to the attached diagram, for more specific details. Figure 1The diagram illustrates a flow chart of an example of a general steam cracking apparatus or method, comprising one or more of the following process sections for converting feed stream 5 into a desired olefin product stream 50: feed pretreatment section 10, pyrolysis reaction section 20, primary fractionation and compression section 30, product fractionation (separation) section 40, or a combination thereof. These sections will be briefly described in the following paragraphs and in more detail below.

[0033] The feed pretreatment section 10 can be configured to regulate the pressure of the feed 5, remove unwanted components (e.g., carbon dioxide (CO2), mercury, water) from the feed, combine the incoming feed with the stored feed to minimize variations in the feed to the pyrolysis reaction section 20, and / or preheat the feed 5 to provide the pretreated feed stream 15.

[0034] The pyrolysis reaction section 20 may include at least one steam cracking furnace or "pyrolysis" furnace configured to crack hydrocarbons in the presence of steam to produce a cracked gas stream, and a transfer line heat exchanger (TLE) or other heat transfer device to quench the cracked gas stream (and optionally harvest heat from it) to provide a cooled cracked stream 25. Conventionally, furnaces in steam cracking equipment generate a high-temperature environment by burning fuels such as methane, which produces carbon dioxide emissions from conventional steam cracking equipment / methods. However, in this embodiment, the furnace is instead an electrically heated furnace, such as one in which electrically heated elements provide heat or thermal energy from the heating chamber to the pipe through which the feed stream flows.

[0035] The primary fractionation and compression section 30 can be configured to provide additional heat recovery from the cooled cracked gas stream 25 and quench it, remove one or more components (e.g., fuel oil, hydrogen sulfide, carbon dioxide, water, or combinations thereof) from the cracked gas stream 25, and / or compress the cracked gas stream 25 to provide a compressed cracked gas stream 38.

[0036] Product fractionation or separation section 40 can be configured to fractionate compressed cracked gas stream 38, selectively hydrogenate one or more streams generated during fractionation, and provide one or more olefin (e.g., ethylene, propylene) product streams 50. Product fractionation or separation section 40 may also provide one or more by-product streams 60, such as, but not limited to, C1 stream, C2 saturated stream, C3 saturated stream, C4 saturated stream, acetylene stream, butadiene stream, L-butene stream, isobutene stream, aromatic stream, hydrogen stream, pyrolytic gasoline stream and / or pyrolytic fuel oil stream, or streams containing combinations of these components. Some of these streams may be recycled to one or more sections of the steam cracking unit. For example, but not limited to, saturated C2, C3, and / or C4 streams can be recycled to one or more pyrolysis furnaces in pyrolysis reaction section 20, and hydrogen can be purified (e.g., via a pressure swing adsorption (PSA) unit and a methanation reactor to remove CO) and recycled to a hydrogenation reactor (e.g., a C2, C3, acetylene, or diene hydrogenator) and / or used as a fuel source (e.g., via a fuel cell). C1 streams can be diverted for use as fuel or chemical feedstock (e.g., for the production of hydrogen from it).

[0037] Now for reference Figure 2-3 , Figure 2 A more detailed example of a prior art steam cracking furnace system 100 is shown (from Ullman, Encyclopedia of Industrial Chemistry, p. 470, 2012, Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim). System 100 includes a steam cracking furnace 104 having a radiant section 108 and a convection section 112. The radiant section has a burner 116 for heating an open-flame tubular reactor 120, where the actual steam cracking of the hydrocarbon feedstock occurs. Flue gas 124 from the burner 116 flows through the open-flame tubular reactor 120 to provide the necessary energy for the endothermic steam cracking process within the tubular reactor 120. Flue gas 124 then flows to the convection section 112 of the steam cracking furnace 104.

[0038] Hydrocarbon feedstock can be introduced into inlet stream 128, which is then directed to convection bank 132 for preheating in the convection section 112 of the steam cracker. See below for reference. Figure 3 The components and functions of the convection tube bundle 132 are described in more detail.

[0039] Boiler feedwater is introduced into stream 136, which is also heated in convection tube bundle 132 and conveyed to steam drum 140. Steam from steam drum 140 is superheated in convection tube bundle 132 to form superheated high-pressure (VHP) steam stream 144. VHP steam typically has an absolute pressure in the range of 5.0 to 16.0 MPa. Diluted steam 148 is then injected into the hydrocarbon stream for mixing and steam cracking processes in open-flame tubular reactor 120.

[0040] The cracked hydrocarbon gas flows from the open-flame tubular reactor 120 to the transfer line heat exchanger 152, where it is cooled and discharged as stream 156 for further processing. The heat recovered from the cracked gas in the transfer line heat exchanger 152 is transferred to the steam drum 140.

[0041] Figure 3 An example of a convection section 112 of a steam cracking furnace is shown. In this example, hot flue gas 124 enters the convection section 112 at a high temperature, where heat is recovered by preheating the feedstock in the lower mixing preheater (LMP) of the convection tube bundle, preheating the boiler feedwater in the economizer (ECO) of the convection tube bundle, and superheating the steam generated by the transfer line heat exchanger 152 in the upper superheater (USH) and lower superheater (LSH) of the convection tube bundle 132. A liquid (e.g., light) hydrocarbon feedstock (128) is preheated and vaporized in the feed preheater (FPH), mixed with dilution steam 148, and further heated in the upper mixing preheater (UMP) and LMP. The preheated mixture stream 160 then enters the open-flame tubular reactor 120 in the radiant section 108 of the furnace 104. Additional heat is recovered by preheating the boiler feedwater (e.g., 136) in the economizer (ECO) of the convection tube bundle 132 and superheating the steam from the steam drum 140 in the USH, after which some boiler feedwater is added at 164 to quench the temperature of the steam, which is then further superheated in the LSH convection tube bundle, where superheated, very high-pressure steam is produced.

[0042] As explained above, the steam cracking furnace 104 delivers heat in both the radiant section 108 (e.g., from the burner 116) and the convection section 112 (e.g., via flue gas 124). It is desirable to eliminate or reduce CO2 emissions from the furnace and other open-flame heaters. A promising approach for this is to replace the open-flame heaters with electric heaters. Many means of providing electric heating to the furnace have been described and can be envisioned, including, but not limited to, direct ohmic heating of the reaction tubes within the furnace, radiant heating by means of heating elements placed within the furnace, induction heating, and heating in electrically driven rotating devices (e.g., rotary dynamic reactors). For the purposes of this disclosure, all such devices should be considered as electric heating furnaces. A common characteristic of such electric heaters is that, since they do not burn fuel to generate heat, they do not produce flue gas that can be used as a heat source in subsequent processes (e.g., in the convection section described above). To compensate for the lack of a convection section, it is often necessary to redesign the process heating equipment and thermal integration scheme, or to utilize additional components (e.g., resistance heaters). Therefore, there is a need to provide different means of heating the hydrocarbon feed gas to the cracking furnace to replace heating in the convection section. As described herein, this disclosure provides such different heating means that can be implemented in existing or newly constructed cracking plants.

[0043] Now for reference Figure 4 and 5 This illustrates a first example 200 of the system utilizing molten salt as the heat transfer fluid in a transfer line heat exchanger (TLE). More specifically, Figure 4 A schematic diagram of system 200 is depicted, and Figure 5 A second schematic diagram of system 200 is depicted, illustrating some characteristics of the system modeled using business process modeling software.

[0044] In the depicted example, system 200 is configured as an electrosteam cracking system. As shown, system 200 includes: an electric furnace 204, a feed preheating (FPH) heat exchanger 208, an electric feed preheater 228, an effluent heat exchanger 212 (e.g., a transfer line heat exchanger (TLE)), and a molten salt loop 216. The electric furnace 204 has a fluid inlet (left side of the furnace 204), a fluid outlet (right side of the furnace 204), and a plurality of reactor tubes 220 extending through the furnace between the fluid inlet and the fluid outlet. The FPH heat exchanger 208 includes a feed inlet (left side of the FPH heat exchanger 208), a feed outlet (right side of the FPH heat exchanger 208), a salt inlet (top of the FPH heat exchanger 208), and a salt outlet (bottom of the FPH heat exchanger 208). FPH heat exchanger 208 is configured such that when the fluid feed flows from the feed inlet to the feed outlet (from left to right in the depicted orientation) and the molten salt flows from the salt inlet to the salt outlet (from top to bottom in the depicted orientation), the fluid feed and the molten salt are in thermal communication but not fluid communication. This arrangement, in which heat is transferred from one fluid to another through a solid wall without direct contact between the two fluids, is generally referred to as indirect contact heat exchange, and the device implementing this arrangement is called an indirect contact heat exchanger. In various embodiments (e.g., for steam cracking), the feed may include hydrocarbon feedstocks such as ethane, propane, butane, naphtha, gas condensate, pyrolysis oil, and combinations thereof.

[0045] The effluent heat exchanger 212 includes an effluent inlet (left side of the effluent heat exchanger 212), an effluent outlet (right side of the effluent heat exchanger 212), a salt inlet (bottom of the effluent heat exchanger 212), and a salt outlet (top of the effluent heat exchanger 212). The effluent heat exchanger 212 is configured such that when the effluent feed flows from the effluent inlet to the effluent outlet (from left to right in the depicted orientation) and the molten salt flows from the salt inlet to the salt outlet (from bottom to top in the depicted orientation), the effluent feed is in thermal communication with the molten salt but not in fluid communication.

[0046] The feed outlet of the FPH heat exchanger 208 is in fluid communication with the fluid inlet of the furnace 204; for example, in the depicted configuration, the feed outlet of the FPH heat exchanger is in fluid communication with the fluid inlet of the furnace via an intermediate supplementary feed preheater 228, which is configured to provide additional preheating of the feed before it enters the furnace 204. In this configuration, dilution steam is added to the hydrocarbon feedstock via line 232, such that the feedstock is heated separately in the FPH heat exchanger 208, and the mixture of feedstock and dilution steam is further heated in the supplementary feed preheater 228. The effluent inlet of the effluent heat exchanger 212 is in fluid communication with the fluid outlet of the furnace 204, allowing effluent to flow from the furnace to the effluent heat exchanger 212. As shown, the molten salt (MS) circuit 216 includes: a first conduit 236 extending from the salt outlet of the effluent heat exchanger 212 to the salt inlet of the FPH heat exchanger 208; a second conduit 240 extending from the salt outlet of the FPH heat exchanger 208 to the salt inlet of the effluent heat exchanger 212; and molten salt disposed in the MS circuit 216. The MS circuit 216 is configured to allow the molten salt to circulate sequentially through: (1) the effluent heat exchanger 212 to receive heat energy from the effluent, (2) the first conduit 236, (3) the FPH heat exchanger 208 to transfer heat energy from the molten salt to the feed to preheat the feed before it enters the furnace 204, and (4) the second conduit 240.

[0047] In some embodiments, the molten salt comprises one or more salts selected from the group consisting of sodium nitrate (NaNO3), potassium nitrate (KNO3), lithium fluoride (LiF), and beryllium fluoride (BeF2). For example, in some embodiments, the molten salt may comprise: (1) a mixture of 60% by weight sodium nitrate and 40% by weight potassium nitrate, which can be used in liquid form at molten salt temperatures of 260°C to 550°C; or (2) a mixture of lithium fluoride (LiF) and beryllium fluoride (BeF2) (e.g., a 2:1 molar mixture, Li2[BeF4]), which can be used in liquid form at molten salt temperatures of 500°C to 700°C. Any other combination of salts adapted to the purposes of this application may also be used; for example, other salts and salt mixtures covering a wider temperature range and / or higher temperature levels may increase the flexibility of the application.

[0048] In the depicted configuration, system 200 also includes a second effluent heat exchanger 244, which includes an effluent inlet (left side of the second effluent heat exchanger 244), an effluent outlet (right side of the second effluent heat exchanger 244), a heat transfer fluid (HTF) inlet (bottom of the second effluent heat exchanger 244), and an HTF outlet (top of the second effluent heat exchanger 244). The second effluent heat exchanger 244 is configured such that when the effluent feed flows from the effluent inlet to the effluent outlet (from left to right in the depicted orientation) and the HTF flows from the HTF inlet to the HTF outlet (from bottom to top in the depicted orientation), the effluent feed is in thermal communication with the HTF, but not in fluid communication.

[0049] As shown, the effluent inlet of the second effluent heat exchanger 244 is in fluid communication with the fluid outlet of the first effluent heat exchanger 212, allowing effluent to flow from the first effluent heat exchanger 212 to the second effluent heat exchanger 244. In the depicted configuration, the second effluent heat exchanger 244 is configured to transfer heat from the effluent to H2O, placing the second effluent heat exchanger at a higher specific enthalpy (i.e., a higher vapor fraction and / or a higher temperature) than its entering state (e.g., as liquid water, a mixture of liquid water and steam, or substantially all steam). In this configuration, the second effluent heat exchanger 244 functions and can be referred to as a secondary transfer line heat exchanger (STLE), and the first effluent heat exchanger 212 functions and can be referred to as a primary transfer line heat exchanger (PTLE). In this configuration, the system 200 also includes a steam loop 248, wherein the steam exiting the second effluent heat exchanger 244 can be used to provide heat to various sub-sections 248 of the system. For example, the steam exiting the second effluent heat exchanger 244 can be considered medium-pressure steam (MPS). MPS applications may include, for example, process heaters, direct steam generation, pumps, etc. When heat energy is extracted from the steam, a portion of the steam can be condensed, and the H2O stream can be returned to a substantially complete liquid form (e.g., boiler feedwater (BFW)) via the condensate system 252.

[0050] In some embodiments of this steam cracking method (e.g., utilizing system 200), the method includes: guiding a fluid feed through a feed preheating (FPH) heat exchanger (e.g., 208) and into the fluid inlet of an electric furnace (e.g., 204), and through multiple coils (e.g., 220) to heat the fluid feed to the reaction temperature and initiate the cracking reaction, wherein the fluid feed contains hydrocarbon feedstock and steam upon its entry into the electric furnace. In some embodiments, this steam cracking method may include: guiding an effluent feed from the fluid outlet of the furnace (e.g., 204) to the effluent inlet of an effluent heat exchanger (e.g., 212) to reduce the temperature of the effluent feed below the reaction temperature and slow down or stop the cracking reaction. In some embodiments, this steam cracking method includes: guiding molten salt at an elevated temperature from the salt outlet of the effluent heat exchanger (e.g., 212) to the salt inlet of the FPH heat exchanger (e.g., 208) to transfer heat from the molten salt to the fluid feed. In some embodiments, this steam cracking method includes guiding molten salt at a reduced temperature from the salt outlet of an FPH heat exchanger (e.g., 208) to the salt inlet of an effluent heat exchanger (e.g., 212) to absorb heat energy from the feed effluent. The increased temperature may, for example, be greater than 500°C; and / or the reduced temperature may, for example, be less than 400°C.

[0051] In at least some of these embodiments, the method is carried out such that the heat capacity of the circulating molten salt is at least as large as the heat capacity of the feed through the FPH heat exchanger (e.g., greater than, for example, 150%, 200%, 220%, 240% or more), and at least as large as the heat capacity of the effluent through the TLE (e.g., greater than, for example, 90%, 115%, 140% or more). For example, in the depicted embodiments, (1) the heat capacity of the molten salt is about 240% of the heat capacity of the feed through the FPH heat exchanger 208; and, after steam is added to the feed at 232 and the combined feed / steam passes through furnace 204, (2) the same heat capacity of the molten salt is about 140% of the effluent through the TLE 212. As used in this disclosure, heat capacity refers to the amount of heat that a flowing fluid (e.g., molten salt) can absorb or release per unit time per unit temperature change, and can be expressed according to the following equation (1):

[0052] C = c p m (1)

[0053] in C Therefore, W.K -1 Heat capacity per unit, m It is in kg s -1 c is the unit fluid mass flow rate. p Therefore, J kg -1 K -1 Specific heat of the fluid is expressed in units. Maintaining the heat capacity ratio of the molten salt at or above the heat capacity ratio of the fluid flowing through the furnace helps ensure that the low temperatures reached by the molten salt leaving the FPH heat exchanger (e.g., 208) remain above the melting point of the molten salt (to avoid freezing and clogging of the molten salt loop), and the high temperatures reached by the molten salt leaving the effluent heat exchanger 212 remain below the boiling point or degradation temperature of the molten salt.

[0054] In some embodiments, the steam cracking method further includes directing the effluent feed from the effluent outlet of a first effluent heat exchanger (e.g., 212) to the effluent inlet of a second effluent heat exchanger (e.g., 244) to further reduce the temperature of the effluent feed.

[0055] A sample of System 200 was modeled using commercial process modeling software, specifically for a steam cracking process with a hydrocarbon feedstock mass flow rate of 283 tons / hour, a dilution steam mass flow rate of 85 tons / hour, and a molten salt (a mixture of 60% sodium nitrate and 40% potassium nitrate) mass flow rate of 1650 tons / hour. Loads in megawatts (MW) and temperatures in degrees Celsius for various components were modeled. Figure 4 As shown; Figure 5 The figure shows the temperature (°C), pressure (bar), mass flow rate (tons / hour), and load (MW) of various components of the system at different points.

[0056] Now for reference Figure 6 and 7 ; Figure 6 A schematic diagram of a second example 200a of the system is depicted, which utilizes molten salt as the heat transfer fluid in the primary TLE and a second heat transfer fluid for the secondary TLE feed preheating loop; and Figure 7A second schematic diagram of system 200a is depicted, illustrating certain characteristics of the system modeled using commercial process modeling software. System 200a is substantially similar to system 200, with the major exception that system 200a includes a second TLE-FPH loop that utilizes a second FPH heat exchanger instead of a second electric preheater 228 to preheat the feedstock. In the absence of preheater 228, the depicted instance of system 200a directly (i.e., without intervening moving parts) guides the preheated mixture of feedstock and steam from FPH heat exchanger 208 to furnace 204, for example, via ducts. Other configurations of system 200a may also include a second electric preheater 228 to provide additional thermal energy. Unlike system 200, system 200a includes a second feed preheating (FPH) heat exchanger 256, which has a feed inlet (left side of the second FPH heat exchanger 256), a feed outlet (right side of the second FPH heat exchanger 256), an HTF inlet (top of the second FPH heat exchanger 256), and an HTF outlet (bottom of the second FPH heat exchanger 256). Similar to FPH heat exchanger 208, the second FPH heat exchanger 256 is configured such that when the fluid feed flows from the feed inlet to the feed outlet (from left to right in the depicted orientation) and the HTF flows from the HTF inlet to the HTF outlet (from top to bottom in the depicted orientation), the fluid feed is in thermal communication with the HTF but not in fluid communication with it. In system 200a, dilution steam is added to the hydrocarbon feedstock via line 232a between the second FPH heat exchanger 256 and the first FPH heat exchanger 208, such that the feedstock is heated separately in the second FPH heat exchanger 256, and the mixture of feedstock and dilution steam is heated in the first FPH heat exchanger 208. As shown, the feed outlet of the second FPH heat exchanger 256 is in fluid communication with the fluid inlet of the first FPH heat exchanger 208, such that the mixture of feedstock and dilution steam flows from the second FPH heat exchanger 256 to the first FPH heat exchanger 208.

[0057] In the depicted configuration, system 200a includes a secondary FPH loop 260. As shown, the secondary FPH loop 260 includes: a first HTF conduit 264 extending from the HTF outlet of the second effluent heat exchanger 244 to the HTF inlet of the second FPH heat exchanger 256; and a second HTF conduit 268 extending from the HTF outlet of the second FPH heat exchanger 256 to the HTF inlet of the second effluent heat exchanger 244; and a heat transfer fluid (HTF). The HTF may include, for example, oil, H2O, or any other HTF that allows the system to function as described. In system 200a, the secondary FPH loop 260 is configured to allow the HTF to circulate sequentially through: (1) a second effluent heat exchanger 244 to receive heat from the effluent, (2) a first HTF conduit 264, (3) a second FPH heat exchanger 256 to transfer heat from the HTF to the fluid feed to preheat the fluid feed before it enters the first FPH heat exchanger 208, and (4) a second HTF conduit 268. Some such embodiments may also include a steam drum and / or other components.

[0058] In some embodiments of this steam cracking method (e.g., using system 200a), the method includes: guiding a fluid feed through a feed preheating (FPH) heat exchanger (e.g., 208) and into the fluid inlet of an electric furnace (e.g., 204), and through multiple coils (e.g., 220) to heat the fluid feed to the reaction temperature and initiate the cracking reaction, wherein the fluid feed contains hydrocarbon feedstock and steam upon its entry into the electric furnace. In some embodiments, this steam cracking method may include: guiding an effluent feed from the fluid outlet of the furnace (e.g., 204) to the effluent inlet of an effluent heat exchanger (e.g., 212) to reduce the temperature of the effluent feed below the reaction temperature and slow down or stop the cracking reaction. In some embodiments, this steam cracking method includes: guiding molten salt at an elevated temperature from the salt outlet of the effluent heat exchanger (e.g., 212) to the salt inlet of the FPH heat exchanger (e.g., 208) to transfer heat from the molten salt to the fluid feed. In some embodiments, this steam cracking method includes guiding molten salt at a decreasing temperature from the salt outlet of an FPH heat exchanger (e.g., 208) to the salt inlet of an effluent heat exchanger (e.g., 212) to absorb heat energy from the feed effluent. The increased temperature may, for example, be greater than 500°C; and / or the decreased temperature may, for example, be less than 400°C. In at least some such embodiments, the method is carried out such that the heat capacity of the circulating molten salt is at least as large as the heat capacity of each of the feed / steam passing through the FPH heat exchanger and the effluent passing through the TLE (e.g., greater than, for example, 90%, 115%, 140% or more). Figure 6 and Figure 7In this configuration, steam is added to the feed at 232a before the feed enters the FPH heat exchanger 208, such that the heat capacity of the feed / steam passing through the FPH heat exchanger is relatively close to (approximately equal to) that of the effluent passing through TLE 212.

[0059] In some embodiments, this steam cracking method further includes: directing the effluent feed from the effluent outlet of a first effluent heat exchanger (e.g., 212) to the effluent inlet of a second effluent heat exchanger (e.g., 244) to further reduce the temperature of the effluent feed. Some such embodiments further include: directing the HTF at an elevated temperature from the HTF outlet of the second effluent heat exchanger (e.g., 244) to the HTF inlet of a second FPH heat exchanger (e.g., 256) to transfer heat energy from the HTF to the fluid feed; and directing the HTF at a decreased temperature from the HTF outlet of the second FPH heat exchanger 256 to the HTF inlet of the second effluent heat exchanger 244 to absorb heat energy from the feed effluent.

[0060] A case study of System 200a was modeled using commercial process modeling software, specifically for a steam cracking process with a hydrocarbon feedstock mass flow rate of 283 tons / hour, a dilution steam mass flow rate of 85 tons / hour, and a molten salt (a mixture of 60% sodium nitrate and 40% potassium nitrate) mass flow rate of 1650 tons / hour. Loads in megawatts (MW) and temperatures in degrees Celsius for various components were modeled. Figure 6 As shown; Figure 7 The diagram shows the temperature (°C), pressure (bar), mass flow rate (tons / hour), and loads (MW) of various system components at different points in the system. As shown, for the modeled example, system 200a is configured to recapture (via effluent heat exchangers 212 and 244) a larger portion of the heat energy added by furnace 204 than system 200 (via effluent heat exchanger 212), and therefore, the amount of electric heating required for feed preheating of system 200a (via electric furnace 204) can be reduced (e.g., up to complete elimination) compared to system 200 (via electric preheater 228 and electric furnace 204). Additionally, further residual heat can be extracted from the effluent exiting the second effluent heat exchanger 244, for example, to heat other streams and / or generate steam.

[0061] As mentioned above, managing the relative magnitudes of the heat capacities of the molten salt and process fluid through each molten salt heat exchanger (e.g., heat exchangers 208 and 212 in systems 200 and 200a) is a crucial factor for the efficient operation of the entire system. While the molten salt (C S The heat capacity of the process stream is (almost) the same in both FPH and TLE heat exchangers, but the heat capacity of the process stream in these two heat exchangers (C in the FPH heat exchanger) is different. CFAnd C in TLE EF The process streams may differ considerably. One reason for this is that the mass flow rates of the process streams through the heat exchangers may differ, for example, because in some cases dilution steam is added after the process streams pass through the FPH heat exchanger. Another reason is that the differences in chemical conversion in the electric furnace and the temperature levels of the process streams result in different heat capacities for the two streams. Even so, the system must be configured and operated to allow the molten salt loop to operate properly in both heat exchangers, which means that the inlet ratio of heat capacity (C) must be considered in both cases. S / C CF The ratio of heat capacity to outlet temperature (C) S / C EF ).

[0062] Figure 8 A schematic diagram of the molten salt circuit 216a in some configurations of this system is depicted. For illustrative purposes, Figure 8 Only those components of the molten salt circuit 216a are shown; however, it should be understood that the configuration of the molten salt circuit 216a can be used in certain embodiments of any of this system. In the configuration shown, in addition to those referenced above... Figure 4 and Figure 5 In addition to the components described, loop 216a further includes pump 272 and salt accumulator 276. Pump 272 is configured to circulate molten salt, i.e., circulate it from FPH heat exchanger 208 to effluent heat exchanger 212 via conduit 240, and from effluent heat exchanger 212 to FPH heat exchanger 208 via conduit 236. Salt accumulator 276 includes a container in fluid communication with the first and second conduits 236, 240 (e.g., in direct fluid communication with conduit 240, as shown). In some configurations, salt accumulator 276 is positioned at a low point in the molten salt loop 216a such that molten salt can be collected in the accumulator in the event of a loss of power or heat, i.e., allowing the molten salt to be gravity-fed into the accumulator before it solidifies. Similarly, in at least some configurations, loop 216a includes a safety trip interlock to allow salt to be discharged while in a molten state, further mitigating the risk of the salt freezing in a manner that could otherwise interfere with and / or damage the operation of loop (216a). In the depicted configuration, loop 216a also includes a heater 280 configured to heat the molten salt while it is in the accumulator container. The heater 280 can be particularly useful during system startup and shutdown (e.g., 200, 200a) to melt the salt for circulation.

[0063] Further details regarding the various components of steam pyrolysis equipment and methods can be found in International Patent Application Publication No. WO2020 / 150244, which is incorporated herein by reference in its entirety.

[0064] The foregoing specification and embodiments provide a complete description of the structure and use of exemplary embodiments. While certain embodiments have been described above with a degree of specificity or by reference to one or more individual embodiments, those skilled in the art can make many changes to the disclosed embodiments without departing from the scope of the invention. Therefore, the various illustrative embodiments of this device are not intended to be limited to the specific forms disclosed. Rather, they include all modifications and alternatives falling within the scope of the claims, and embodiments other than those shown may include some or all of the features of the depicted embodiments. For example, components may be combined into an integral structure, and / or connections may be replaced. Furthermore, where appropriate, aspects of any instance described above may be combined with aspects of any other instance described to form additional instances having comparable or different properties and solving the same or different problems. Similarly, it will be understood that the benefits and advantages described above may apply to one embodiment or to several embodiments.

[0065] The claims are not intended to include, nor should they be construed as including, means plus function or steps plus function limitations, unless such limitations are expressly stated in the given claims by the phrases “means for…” or “steps for…”, respectively.

Claims

1. A system, the system comprising: An electric furnace having a fluid inlet, a fluid outlet, and a plurality of reactor tubes extending through the furnace between the fluid inlet and the fluid outlet; A feed preheating (FPH) heat exchanger includes a feed inlet, a feed outlet, a salt inlet, and a salt outlet, wherein the FPH heat exchanger is configured such that when a fluid feed flows from the feed inlet to the feed outlet and molten salt flows from the salt inlet to the salt outlet, the fluid feed is in thermal communication with the molten salt but not in fluid communication, wherein the feed outlet of the FPH heat exchanger is in fluid communication with the fluid inlet of the furnace; An effluent heat exchanger includes an effluent inlet, an effluent outlet, a salt inlet, and a salt outlet, the effluent heat exchanger being configured such that when the effluent feed flows from the effluent inlet to the effluent outlet and molten salt flows from the salt inlet to the salt outlet, the effluent feed is in thermal communication with the molten salt but not in fluid communication, wherein the effluent inlet of the effluent heat exchanger is in fluid communication with the fluid outlet of the furnace; Molten salt circuit, comprising: A first conduit extends from the salt outlet of the effluent heat exchanger to the salt inlet of the FPH heat exchanger; A second conduit extends from the salt outlet of the FPH heat exchanger to the salt inlet of the effluent heat exchanger; and Molten salt; The molten salt circuit is configured to sequentially circulate the molten salt through the effluent heat exchanger to receive heat energy from the effluent, through the first conduit, through the FPH heat exchanger to transfer heat energy from the molten salt to the fluid feed to preheat the fluid feed before it enters the furnace, and through the second conduit.

2. The system of claim 1, wherein the effluent heat exchanger is a first effluent heat exchanger, and the system further comprises: A second effluent heat exchanger includes an effluent inlet, an effluent outlet, a heat transfer fluid (HTF) inlet, and an HTF outlet. The second effluent heat exchanger is configured such that when the effluent feed flows from the effluent inlet to the effluent outlet and the HTF flows from the HTF inlet to the HTF outlet, the effluent feed is in thermal communication with the HTF but not in fluid communication, wherein the effluent inlet of the second effluent heat exchanger is in fluid communication with the fluid outlet of the first effluent heat exchanger.

3. The system of claim 2, wherein the FPH heat exchanger is a first FPH heat exchanger, and the system further comprises: A second feed preheating (FPH) heat exchanger includes a feed inlet, a feed outlet, an HTF inlet, and an HTF outlet. The second FPH heat exchanger is configured such that when a fluid feed flows from the feed inlet to the feed outlet and the HTF flows from the HTF inlet to the HTF outlet, the fluid feed is in thermal communication with the HTF but not in fluid communication with the HTF, wherein the feed outlet of the second FPH heat exchanger is in fluid communication with the feed inlet of the first FPH heat exchanger.

4. The system according to claim 3, wherein the system further comprises: The secondary FPH circuit includes: A first HTF conduit extends from the HTF outlet of the second effluent heat exchanger to the HTF inlet of the second FPH heat exchanger; A second HTF conduit extends from the HTF outlet of the second FPH heat exchanger to the HTF inlet of the second effluent heat exchanger; and Heat transfer fluid (HTF), optionally wherein the HTF comprises H2O or heat transfer oil; The secondary FPH loop is configured to cause the HTF to sequentially circulate through the second effluent heat exchanger to receive heat energy from the effluent, through the first HTF conduit, through the second FPH heat exchanger to transfer heat energy from the HTF to the fluid feed to preheat the fluid feed before it enters the first FPH heat exchanger, and through the second HTF conduit.

5. The system according to any one of claims 1-4, wherein the molten salt circuit further comprises: A pump configured to circulate the molten salt.

6. The system according to any one of claims 1-5, wherein the molten salt circuit further comprises: An energy storage container in fluid communication with the first conduit and the second conduit.

7. The system of claim 6, wherein the accumulator container is located at the lowest point in the molten salt circuit.

8. The system according to any one of claims 1-7, wherein the molten salt circuit further comprises: A heater configured to heat the molten salt when it is in the accumulator container.

9. A steam cracking method, the method comprising: Hydrocarbon-containing fluid feed is guided through a feed preheating (FPH) heat exchanger; The hydrocarbon-containing fluid feed is guided from the FPH heat exchanger to the fluid inlet of the electric furnace and passed through multiple coils to heat the fluid feed to the reaction temperature and initiate the cracking reaction; The effluent is directed from the fluid outlet of the furnace to the effluent inlet of an effluent heat exchanger to reduce the temperature of the effluent. The effluent heat exchanger includes a salt inlet and a salt outlet and is configured such that when the effluent feed flows from the effluent inlet to the effluent outlet and molten salt flows from the salt inlet to the salt outlet, the effluent feed is in thermal communication with the molten salt but not in fluid communication. Molten salt at an elevated temperature is directed from the salt outlet of the effluent heat exchanger to the salt inlet of the FPH heat exchanger to transfer heat energy from the molten salt to the fluid feed. The FPH heat exchanger is configured such that when the fluid feed flows from the feed inlet to the feed outlet and the molten salt flows from the salt inlet to the salt outlet, the fluid feed is in thermal communication with the molten salt but not in fluid communication. and Molten salt at a reduced temperature is guided from the salt outlet of the FPH heat exchanger to the salt inlet of the effluent heat exchanger to absorb heat energy from the effluent. The method optionally further includes adding steam to the hydrocarbon-containing fluid feed before directing the hydrocarbon-containing fluid feed into the furnace, and optionally before directing the hydrocarbon-containing fluid feed into the FPH heat exchanger.

10. The method of claim 9, wherein the increased temperature is greater than 500°C and the decreased temperature is less than 400°C.

11. The method according to any one of claims 9-10, wherein the effluent heat exchanger is a first effluent heat exchanger, and the method further comprises: The effluent feed is directed from the effluent outlet of the first effluent heat exchanger to the effluent inlet of a second effluent heat exchanger to further reduce the temperature of the effluent feed. The second effluent heat exchanger includes a heat transfer fluid (HTF) inlet and an HTF outlet, and is configured such that when the effluent feed flows from the effluent inlet to the effluent outlet and the HTF flows from the HTF inlet to the HTF outlet, the effluent feed is in thermal communication with the HTF but not in fluid communication.

12. The method of claim 11, wherein the FPH heat exchanger is a first FPH heat exchanger, and the method further comprises: Before guiding the fluid feed through the first FPH heat exchanger, the fluid feed is guided through a second feed preheating (FPH) heat exchanger, the second FPH heat exchanger including an HTF inlet and an HTF outlet, and configured such that when the fluid feed flows through the second FPH heat exchanger and the HTF flows from the HTF inlet to the HTF outlet, the fluid feed is in thermal communication with the HTF but not in fluid communication with the HTF; The HTF, which is at an elevated temperature, is directed from the HTF outlet of the second effluent heat exchanger to the HTF inlet of the second FPH heat exchanger to transfer heat energy from the HTF to the fluid feed. and The HTF, which is at a reduced temperature, is guided from the HTF outlet of the second FPH heat exchanger to the HTF inlet of the second effluent heat exchanger to absorb heat energy from the feed effluent.

13. The method according to any one of claims 11-12, wherein the HTF comprises H2O or heat transfer oil.

14. The method according to any one of claims 9-13, wherein the heat capacity (C) of the molten salt is... S The heat capacity of the hydrocarbon-containing fluid feed is greater than that of the feedstock (C). F ), where C is optional S It is C F More than 150% of the total, and additionally, C is optional. S C F More than 200%.

15. The method according to any one of claims 9-14, wherein the heat capacity (C) of the molten salt is... S The heat capacity of the effluent feed is greater than that of the feed material (C). F ), where C is optional S C F More than 120% of the total, and additionally, C can be selected from the following locations. S C F More than 140%.

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