Electric heating furnace using conductive refractory material

Abstract

Systems and methods of electrically heated chemical processes utilizing electrically conductive refractory materials are described. The heating device may include an electrically conductive refractory material without separate heating elements; and a furnace for heating hydrocarbons. The furnace includes one or more process tubes configured to receive process steam or fluid such that the process steam or fluid does not contact the electrically conductive refractory material. The electrically conductive refractory material may be at least partially disposed within the furnace and configured to receive power from the power source and generate heat such that the electrically conductive refractory material radiates heat directly within the furnace. A method of operating a chemical process may include providing such a furnace; and applying an electrical current directly to the conductive refractory such that the temperature of the conductive refractory rises and provides heat to the chemical process.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of European Patent Application No. EP22175712 filed on May 27, 2022, which is incorporated herein by reference in its entirety. Technical Field

[0002] The present disclosure relates to systems and methods for generating thermal energy, and more particularly to heating devices for use in electrical heating processes. Background Art

[0003] High temperature furnaces have a variety of applications including, but not limited to, chemical processes. Specifically, radiant high temperature furnaces have been considered for steam cracking, steam methane reforming (SMR), ammonia reforming, dehydrogenation, tar cracking, or similar applications. Such processes, and the furnaces used to heat such processes, have traditionally relied on combustion. In order to meet new sustainability and CO2 reduction requirements, such fired heaters may need to be replaced.

[0004] Recent developments include heaters and furnaces powered by electricity, preferably renewable electricity. Non-combustion heaters are needed to provide heat for such processes. An exemplary configuration of a heater for such applications includes a conductive heating element, typically a wire or strip of metal as shown in Figures 1A and 1B, suspended from a non-conductive refractory material (e.g., non-conductive refractory bricks). In these systems, a voltage is applied to the conductive element, and the resulting current causes the element to heat up. This is known as impedance heating or ohmic heating. As the elements heat up, they heat the refractory material. When the system reaches operating temperature, the heater radiates heat from the elements and refractory bricks into the furnace box, and the heat is then transferred to the furnace tubes. This makes it possible to replace combustion with an electric heating system.

[0005] 1A and 1B schematically illustrate a conventional radiant heating element 100 that can be used for heating applications (e.g., heating hydrocarbons). A metal, ceramic, or other type of material heating element (e.g., a wire or ribbon 102) can be attached to a non-conductive refractory material 104, i.e., the heating element is not integral to the non-conductive refractory material 104. When the wire or ribbon 102 is heated, the heat energy generated by the heating element 102 heats the non-conductive refractory material 104, and the heat radiates from the heating element and the non-conductive refractory material 104 to the interior of the furnace shell.

[0006] However, in the above systems, the permissible operating temperature of the heating element is limited and its life will be shortened as the temperature increases. The maximum operating temperature may vary, but in general, the maximum operating temperature of metal elements should not exceed about 1300 ° C. However, in many processes, higher temperatures are required.

[0007] For electric processes, the inventors have discovered a need for systems and methods of heating using heaters capable of operating at high temperatures. Summary of the invention

[0008] In an embodiment of the present disclosure, a heating device may include a conductive refractory material (and a non-conductive refractory material) without a separate heating element; and a furnace for heating hydrocarbons. The furnace may include one or more process tubes passing through the interior of the furnace, the process tubes configured to receive process steam or fluid so that the process steam or fluid does not contact the conductive refractory material. The conductive refractory material may be at least partially exposed to the interior of the furnace (e.g., at least partially disposed within the furnace), and may be configured to receive power from a power source to generate heat, so that the conductive refractory material radiates heat (e.g., directly) to the interior of the furnace.

[0009] In one embodiment of the present disclosure, a method of operating a chemical process may include providing a furnace with a conductive refractory material that is at least partially exposed to the interior of the furnace (e.g., disposed within the furnace). The furnace may include one or more process tubes that extend through the interior of the furnace and are configured to receive process steam or fluid so that the process steam or fluid does not contact the conductive refractory material. The method may also include applying an electric current directly to the conductive refractory material so that the current flowing through the conductive refractory material generates thermal energy, thereby increasing the temperature of the conductive refractory material and heating the process steam or fluid in the process tube.

[0010] In the present disclosure, a "conductive refractory material" is a material that is inherently conductive, such that the current flowing through the material itself generates thermal energy (e.g., converts electrical energy into thermal energy), i.e., the conductive refractory material does not include a separate heating element. Various examples of conductive refractory materials are known and commercially available, for example, the ETS Joule Hive technology provided by Electrified Thermal Solutions, Inc. (Medford, Massachusetts, USA).

[0011] In certain embodiments, the conductive refractory material may be a ceramic material (e.g., an electrically heated ceramic material). One or more process tubes of the furnace may be configured to receive process steam or fluid associated with a process selected from steam cracking, steam methane reforming, ammonia reforming, dehydrogenation, and tar cracking. One or more process tubes may include a plurality of process tubes. In some aspects, a plurality of process tubes may be arranged in two or more rows of process tubes, and the rows may be alternated with conductive refractory materials. Alternatively, in some aspects, a plurality of process tubes may be arranged in a single row of a plurality of process tubes. In this case, each individual process tube in the plurality of process tubes may be spaced apart from the conductive refractory material by at least a process tube wall thickness corresponding to the difference between the process tube outer diameter and the process tube inner diameter. The conductive refractory material may be formed into the shape of a cylinder, a plate, or a rod. The conductive refractory material may form a channel. According to certain embodiments, one or more process tubes include a plurality of process tubes, and each individual process tube is arranged in a particular channel. For illustration, in some cases, the conductive refractory material includes a plurality of channels extending through the conductive refractory material, and each individual process tube may be inserted through a corresponding one of the plurality of channels. The power from the power source may correspond to a voltage greater than 500 volts, preferably greater than 1000 volts, and more preferably greater than 2000 volts. In one embodiment of the present disclosure, a method of operating a chemical process may include: providing a furnace having an electrically conductive refractory material at least partially disposed within the furnace, the electrically conductive refractory material having no separate heating element, wherein the furnace includes one or more process tubes configured to receive a process vapor or fluid, the one or more process tubes being separated from the electrically conductive refractory material to prevent the process vapor or fluid from directly contacting the electrically conductive refractory material; and applying electricity directly to the electrically conductive refractory material such that a temperature of the electrically conductive refractory material increases and provides heat for the chemical process.

[0012] In certain embodiments, the chemical process may correspond to one of: a steam cracking process (e.g., in some examples, an ethane (C2H6) cracking process or an olefin steam cracking process); a steam methane reforming (SMR) process (e.g., for syngas production); an ammonia, hydrogen, or methanol reforming process; a dehydrogenation process (e.g., conversion of propane to propylene); and a tar cracking process. According to certain embodiments, the chemical process may be a steam methane reforming process, and the one or more process tubes may include a plurality of process tubes. According to certain embodiments, the chemical process may be an ethane cracking process or an olefin steam cracking process, and the one or more process tubes may include a plurality of process tubes. In this case, each individual process tube in the plurality of process tubes may be spaced apart from the conductive refractory material by at least a process tube wall thickness corresponding to the difference between the process tube outer diameter and the process tube inner diameter.

[0013] Other aspects and advantages of these exemplary embodiments and other embodiments are discussed in detail herein. In addition, it should be understood that the foregoing information and the following detailed description only provide illustrative examples of various aspects and embodiments, and are intended to provide an overview or framework for understanding the nature and characteristics of the claimed aspects and embodiments. Therefore, these and other purposes, advantages and features of the present disclosure will become apparent by reference to the following description and accompanying drawings. In addition, it should be understood that the features of the various embodiments described herein are not mutually exclusive and may exist in various combinations and arrangements.

[0014] The term "coupled" is defined as connected, although not necessarily directly and not necessarily mechanically; two "coupled" objects may be integral to one another. Unless otherwise expressly required by the present disclosure, the terms "a" and "an" are defined as one or more. The term "substantially" is defined as largely, but not necessarily completely, as specified (and including what is specified; for example, substantially 90 degrees includes 90 degrees and substantially parallel includes parallel), as understood by one of ordinary skill in the art. In any embodiment of the present devices, kits, and methods, the term "substantially" may be replaced with "within a specified percentage," where percentages include 0.1%, 1%, 5%, and / or 10%.

[0015] The terms "comprise" (and any form of including, such as "comprises" and "comprising"), "have" (and any form of having, such as "has" and "having"), "include" (and any form of including, such as "includes" and "including"), and "contain" (and any form of containing, such as "contains" and "containing") are open conjunctions. Thus, a device or kit that "comprises," "has," "includes," or "contains" one or more elements possesses the one or more elements, but is not limited to possessing only the one or more elements. Similarly, a method that "comprises," "has," "includes," or "contains" one or more steps means possessing the one or more steps, but is not limited to possessing only the one or more steps.

[0016] Furthermore, a device, apparatus, or system that is configured in a certain way is configured in at least that way, but may also be configured in other ways besides the specifically described way.

[0017] Any embodiment of the present apparatus and method may consist of or consist essentially of (rather than include / comprise / contain / have) any of the steps, elements and / or features described. Thus, in any claim, the term "consisting of" or "consisting essentially of" may replace any of the above open conjunctions in order to alter the scope of a given claim from that using the open conjunctions.

[0018] Some details related to aspects of the present disclosure are described above, and other details are described below. Other implementations, advantages, and features of the present disclosure will become apparent after reading the entire application (including the brief description of the drawings, the detailed description, and the claims). BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings are used to help further understand the embodiments of the present disclosure, are incorporated into and constitute a part of this specification, illustrate embodiments of the present disclosure, and are used together with the detailed description to explain the principles of the embodiments discussed herein. No attempt is made to show the structural details of the present disclosure in more detail, except for the basic understanding of the embodiments discussed herein and the various ways in which they can be implemented. As a matter of convention, the various features in the drawings discussed below are not necessarily drawn to scale. The sizes of the various features and elements in the drawings may be enlarged or reduced to more clearly illustrate the embodiments of the present disclosure.

[0020] FIG. 1 is a schematic front view of a conventional radiant heating element that may be used in heating applications.

[0021] 1B is a schematic side view of a conventional radiant heating element that may be used in heating applications.

[0022] 2 is a schematic diagram of an exemplary electrically conductive refractory system.

[0023] 3A is a flow diagram of an electrically conductive refractory system used as a thermal storage device.

[0024] 3B is a flow diagram of an electrically conductive refractory system for use as a furnace.

[0025] 4A and 4B are schematic side and top views, respectively, showing the use of a conductive refractory stack to heat a process tube.

[0026] 5A and 5B are schematic side and end views, respectively, illustrating the use of conductive refractory walls alternating with rows of process tubes.

[0027] 6 is a schematic diagram showing a cross-sectional side view of an example furnace design including a plurality of process tubes disposed between two electrically conductive refractory walls.

[0028] 7 is a graph showing modeling results corresponding to a tube temperature profile associated with an exemplary SMR process performed using a furnace design similar to that shown in FIG. 6 .

[0029] 8 is a schematic diagram showing a cross-sectional side view of another example of a furnace design including a plurality of process tubes disposed between two electrically conductive refractory walls.

[0030] 9 is a graph showing modeling results corresponding to tube temperature profiles associated with an exemplary ethane cracking process performed using a furnace design similar to the furnace design shown in FIG. 8 . Detailed Description

[0031] While the drawings include like numerals to indicate like components throughout the several views, the following description is provided as an enabling teaching of exemplary embodiments, and those skilled in the relevant art will recognize that many variations can be made to the described embodiments. It should also be understood that some of the desired benefits of the embodiments may be obtained by selecting certain features of the embodiments without utilizing other features. Therefore, those skilled in the art will recognize that many modifications and adjustments to the embodiments are possible and even desirable in some cases. Therefore, the following description is intended only to illustrate the principles of the embodiments and does not limit the principles thereof.

[0032] The words and terms used herein are for descriptive purposes only and should not be considered as limiting. As used herein, the term "plurality" refers to two or more items or components. Whether in a written specification or in a claim, the terms "including", "comprising", "carrying", "having", "containing" and "involving" are open terms, that is, "including but not limited to", unless otherwise specified. Therefore, the use of these terms is intended to cover the items listed thereafter and their equivalents and other items. For any claim, the transition phrases "consisting of..." and "consisting essentially of..." are closed transition phrases or semi-closed transition phrases, respectively. The use of ordinal numbers such as "first", "second", "third" and other words that modify claim elements in the claims does not itself indicate the priority, priority or order of one claim element relative to another claim element, nor does it indicate the time sequence of the actions of the execution method, but is only used as a label to distinguish a claim element with a specific name from another element with the same name (but using ordinal numbers) to distinguish claim elements.

[0033] Furthermore, although this document may refer to quantitative measurements, values, geometric relationships, etc., unless otherwise stated, one or more (if not all) of them may be absolute or approximate to account for acceptable variations that may occur, such as those due to manufacturing or engineering tolerances, etc.

[0034] Compared to the prior art configurations of FIGS. 1A and 1B , FIG. 2 shows an example of an exemplary conductive refractory system 200 that includes a conductive refractory material (e.g., in the form of a brick) configured to be resistively heated by an electric current. In some configurations, the conductive refractory brick includes a conductive material or can be doped with a conductive material (e.g., a metal oxide) so that the current will flow through the brick, but with sufficient resistance to convert the electrical energy into thermal energy and thereby heat the material. Such conductive refractory materials may have a relatively high emissivity (e.g., 0.5 or greater, 0.7 or greater, or 0.8 or greater) to effectively emit thermal radiation, and have a relatively high specific heat (e.g., 400 J / kg-K or greater, 450 J / kg-K or greater, or 500 J / kg-K or greater) to increase thermal energy so as to temporarily "store" thermal energy when the thermal energy is dissipated (e.g., when no current is provided).

[0035] The use of conductive refractory materials allows the chimney to omit conventional heating metal elements, such as wires or metal strips, which are generally more susceptible to oxidation and other degradation at high temperatures (and are therefore not suitable for use at temperatures comparable to those produced by conventional burners). In use, the conductive refractory materials of the conductive refractory system are heated by directly passing electricity through the conductive refractory material 202.

[0036] The conductive refractory materials of the present disclosure may be configured to be resistively heated by an electric current. The use of conductive refractory materials (such as refractory bricks) may replace wire or metal strip heating elements, or replace separate ceramic or other types of heating elements that are not an integral component of the conductive refractory system, such as silicon carbide (SiC) or molybdenum carbide (MoC) heating elements. For the purposes of this application, reference may be made to "bricks", but the conductive refractory materials of the system may be provided in various formats, sizes, shapes, and other configurations as desired for a particular embodiment.

[0037] The use of conductive refractory materials can further eliminate or reduce certain design limitations of existing systems. Generally speaking, the conductive refractory material can be a brick, which does not have a metal conductor itself, but has an electric current flowing through the conductive refractory material. In some embodiments, the conductive refractory material can be a ceramic. In other embodiments, the conductive refractory material can be a stand-alone device that does not include a separate heating element. In some embodiments, the conductive refractory material can also be referred to as an electrically heated ceramic (EHC).

[0038] In some configurations, the conductive refractory materials of the present disclosure can be configured to operate at temperatures up to 2000°C or higher, which is much higher than the operating temperature of traditional electrical heating elements (e.g., Kanthal-FeCrAl alloy or Fe-, Cr-, Al-based metal elements or their alloys).

[0039] Advantages of the conductive fire resistant system of the present invention may include, but are not limited to, one or more of the following (e.g., a combination of any two or more): Improved simplicity and reduced costs. Conductive refractory materials do not require the use of separate conductive wires or other heating elements of various materials (metals, ceramics, etc.), so for current conductive refractory systems, the use of conductive refractory materials can eliminate such separate conductive wires or other heating elements, which are one of the most expensive components in heating technology. Stated more succinctly, the elimination of separate conductive wires or other heating elements can make the conductive refractory system simpler. Higher heat flux and higher temperatures. Conductive refractory materials can operate at temperatures up to about 2000C, while metal heating elements are limited to about 1300C. Conductive refractory materials can have better maintenance and reliability than metal wires and ribbons because they do not need to operate near the temperature limits of the material, and their construction can be simpler (reducing potential failure points within the system). Conductive refractory systems can be used for heating to higher temperatures. · Conductive refractory materials can achieve higher (total wall) flux. For example, the increase in flux may have two aspects: (1) the flux may be higher at higher temperatures; (2) a larger proportion of the total wall area is utilized. Since the heating refractory system can utilize most of the wall area of ​​the conductive refractory material, the total surface area and furnace size required for a given task can be reduced (relative to traditional electrically heated refractory materials). · Higher voltage. The conductive refractory system can operate at voltages up to 13kV. In some embodiments, voltages greater than 500 volts, preferably greater than 1000 volts, and more preferably greater than 2000 volts can be provided. Therefore, heating can be achieved at lower current intensities, and the required electrical equipment may be much cheaper. The electrical equipment may include, but is not limited to, step-down transformers, control elements, switchgear, conductors, connectors, and other equipment.

[0040] Energy storage technology can provide heat or thermal energy to process streams through a conductive refractory system. The heat can be used to heat itself or drive chemical reactions in various chemical processes. Figure 3A is a flow chart 300 of a conductive refractory system used as a heat storage device. In certain embodiments, when a conductive refractory material is used as a heat storage device, heat will be absorbed from a conductive refractory system 302, for example, a system composed of bricks of conductive refractory bricks or composed of conductive refractory bricks arranged in a furnace or other area to be heated (for example, a heat storage brick stack according to some embodiments). The heat from the conductive refractory system 302 can be used to generate a hot working fluid 304 (typically a hot gas), which then transfers the thermal energy to the process, for example, through a heat exchanger 306. The flow chart 300 of Figure 3A further illustrates that the conductive refractory system 302 may include a power input to receive electricity 308 (for example, in some cases, from an alternating current (AC) power source). Flowchart 300 further illustrates that, according to certain aspects of the present disclosure, a bypass 310 (e.g., a gas bypass in some cases) may be configured to direct a portion of the working fluid (e.g., gas) around the conductive refractory system 302 and redirected to join the hot working fluid 304 downstream of the working fluid output of the conductive refractory system 302.

[0041] 3A further illustrates that the heat exchanger 306 may also include at least one process input and at least one process output. The process input may be configured to receive a process feed 312, and the heat exchanger 306 may heat the process feed to form a hot process output 314 outputted through the process output. The flow chart 300 of FIG3A further illustrates that the heat exchange reactor 306 may also include at least one working fluid output, which is configured to output a reduced temperature working fluid 316 after the heat energy is transferred to the process feed 312 to produce the hot process output 314.

[0042] FIG3B is a flow chart 400 of a conductive refractory system used as a furnace. In certain embodiments, when the conductive refractory material is used as a furnace (referred to herein as a "conductive refractory system" or "conductive brick furnace" and identified in FIG4B by reference character 402), heat can be transferred directly from the hot bricks in the same manner as conventional techniques, but without the limitation of conductive metal wires or metal strips. Similar to the flow chart 300 of FIG3A depicting an example conductive refractory system 302, the flow chart 400 of FIG3B further illustrates that the conductive refractory system 402 may include a power input to receive power 408 (e.g., in some cases, from an alternating current (AC) power source).

[0043] 3B further illustrates that, in some cases, the conductive refractory system 402 may also include at least one process input and at least one process output. The process input may be configured to receive a process feed 412, and the conductive refractory system 402 may directly apply heat (e.g., according to one embodiment, directly apply heat from a hot brick, corresponding to a temperature of approximately 1000° C.) to create a thermal process output 414 outputted through the process output. As an illustrative, non-limiting example, the initial temperature of the process feed 412 (e.g., a hydrocarbon feed in some cases) at the process input end of the conductive refractory system 402 may be approximately 650° C., and after the application of heat, the output temperature of the thermal process output 414 at the process output end of the conductive refractory system 402 may be approximately 850° C.

[0044] In certain embodiments, the conductive refractory system includes process tubes that pass through or extend through a stack of conductive refractory materials. For example, Figures 4A and 4B are diagrams 500 and 520 depicting side and top schematic views, respectively, showing the use of conductive refractory materials 502 (or conductive refractory stacks) to heat process tubes 518, showing process feeds 512 (e.g., hydrocarbon feeds) at the input end of each individual tube and hot process outputs 514 at the output end of each individual tube.

[0045] In some embodiments, the process tube 518 may penetrate or otherwise pass through the conductive refractory material 502. The conductive refractory material 502 may have one or more channels (also referred to herein as "channels" or "tunnels") through which one or more process tubes 518 may be inserted. In this case, one or more process tubes 518 may be partially or completely surrounded by the conductive refractory material 502. In some embodiments, the conductive refractory material 502 may be a stack. When a voltage is applied to the stack, the power supply 508 input may be ohmic heating. Heat can be transferred from the hot bricks (which may be heated to about 2000C) to the process pipe 518 (e.g., hydrocarbon pipe) by radiation, and then transferred to the material (e.g., hydrocarbon gas) in the process pipe 518 (e.g., received at the input end of each pipe 518 by the process feed 512 and output at the output end of each pipe 518 by the hot process output 514).

[0046] In certain embodiments, the conductive refractory system can include alternating conductive refractory walls and rows of process tubes. Figures 5A and 5B are schematic diagrams 600 and 620 showing the use of conductive refractory walls alternating with rows of process tubes 618, showing a process feed 612 (e.g., a hydrocarbon feed) at the input end of each individual tube 618 and a hot process output 614 at the output end of each individual tube 618. The schematic diagrams 600 and 620 shown in Figures 5A and 5B correspond to a top view and an end view, respectively, showing the use of a conductive refractory stack 602 to heat the process tubes 618.

[0047] In certain embodiments, the conductive refractory system may include alternating brick walls and rows of process tubes. In general, the size and configuration of the conductive refractory material may vary to provide the heat required for a particular application. In certain embodiments, the wall may include one or more conductive refractory bricks, and the width may be one or more bricks.

[0048] In some embodiments, the wall may be a stack of conductive and non-conductive refractory bricks. When a voltage is applied across the stack, the power input may be ohmic heating. Heat may be transferred by radiation from the hot brick wall (which may be up to about 2000°C) to the process pipe (e.g., a hydrocarbon pipe) and then to the material within the pipe (e.g., hydrocarbon gas).

[0049] In addition, various other geometries may be realized. The examples listed in Figures 4A-4B and 5A-5B are merely illustrative geometries, and other configurations may also provide heat for various processes. Exemplary configurations may include, but are not limited to: The process piping can be placed in a box whose walls are lined with heat-generating conductive refractory materials (powered by electricity). Non-conductive refractory materials can also be used to line the outer walls to isolate them from the vessel walls (e.g. metal) and the surrounding environment. Multiple rows of pipes and conductive refractory materials are arranged alternately. Conductive refractory materials in various geometric shapes, including but not limited to cylinders, plates, etc., to construct high temperature elastic heating elements or structural channels or structural porous network frameworks.

[0050] The systems and methods described herein can be used to heat process streams or drive endothermic chemical reactions with or without catalysts. Example 1

[0051] 6, a schematic diagram 700 shows a cross-sectional side view of an example of a furnace having a design similar in some respects to the furnace design described herein with respect to FIGS. 5A and 5B. The example furnace design shown in FIG. 6 includes a plurality of process tubes 718 disposed between two walls (only one of which is shown) of a conductive refractory material 702 to prevent process vapors or fluids from directly contacting the conductive refractory material 702.

[0052] 6, the plurality of process tubes 718 corresponds to six different process tubes arranged in a single row, wherein the single row is located between two walls of the conductive refractory material 702. Each individual process tube 718 has the following characteristics: tube inner diameter (ID) of 127 mm; tube length of 12.22 m; tube wall thickness of 10 mm. The total surface area of ​​the outer surface of all process tubes 718 exposed to radiant heating between the two walls of the conductive refractory material 702 corresponds to 70 square meters.

[0053] The example furnace design shown in Figure 6 is modeled for a steam methane reforming (SMR) process. The power 708 provided to the conductive refractory material 702 corresponds to an energy input of 0.4 MW for each individual process tube 718. The tube inlet feed conditions are shown below in Tables 1 and 2. The tube outlet conditions (corresponding to average variations for each individual process tube 718) are shown below in Table 3. Table 1 Temperature(℃) 565 Flow rate per pipe (kg / s) 0.124089 Pressure (Pascal) 4175000 Table 2 Table 3 Temperature (K) 1161.327 Wall temperature (K) 1246.8271 Nusselt number 617.65716 <![CDATA[Wall heat flux density (W / m 2 )]]> -63929.765 Speed ​​(m / s) 1.8351336 <![CDATA[Density (kg / m 3 )]]> 5.3439704 Pressure (Pascal) 4175000 <![CDATA[Mass fraction of C2H6 (ethane)]]> 0 <![CDATA[Mass fraction of H2 (hydrogen gas)]]> 0.0770734 <![CDATA[Mass fraction of H2O (water)]]> 0.48162041 <![CDATA[Mass fraction of CO2 (carbon dioxide)]]> 0.18272876 <![CDATA[Mass fraction of CH4 (methane)]]> 0.041943179 <![CDATA[Mass fraction of N2 (nitrogen)]]> 0.010772998 <![CDATA[Mass fraction of C3H8 (propane)]]> 0 Mass fraction of CO (carbon monoxide) 0.20586125

[0054] Based on a comparison of the initial methane (CH4) mass fractions shown in Figure 3, as shown in Table 2, the methane mass fractions correspond to the methane mass fractions in Table 3, and the methane conversion obtained by modeling the SMR process using the furnace design shown in Figure 6 is approximately 79%. For the thermal data, the flux at the heated wall corresponds to 33.55 kW / m 2 (based on wall area average); the flux at the tube wall corresponds to 80.7kW / m 2(Averaged based on the identifier associated with each individual process tube 718). With respect to the wall temperature data, the simulated maximum wall temperature was approximately 1215°C and the average wall temperature was measured to be approximately 1151°C. FIG. 7 is a graph 800 depicting tube temperature profiles, wherein the top line (“thickness”) corresponds to the external temperature, the upper line corresponds to the outside diameter (T_ID) of the process tube 718, the middle line corresponds to the temperature at the inside diameter (T_ID) of the process tube 718, and the lower line corresponds to the temperature of the process gas (T_gas) within the process tube 718. The “thickness” of the top line of the graph 800 shown in FIG. 7 is because there is a range of temperatures around the circumference of each individual process tube 718, with the highest temperatures toward the heated wall and the lowest temperatures toward adjacent tubes. Example 2

[0055] Referring to Figure 8, a schematic diagram 900 shows a cross-sectional side view of another example furnace design similar in some respects to the furnace design described herein with respect to Figures 5A and 5B. The example furnace design shown in Figure 8 includes a plurality of process tubes 918 disposed between two walls (only one of which is shown) of a conductive refractory material 902 to prevent process vapors or fluids from directly contacting the conductive refractory material 902.

[0056] In the example of FIG. 8 , the plurality of process tubes 918 corresponds to eight different process tubes arranged in a single row, wherein the single row is located between two walls of the electrically conductive refractory material 902 . Each individual process tube 918 has the following characteristics: tube inner diameter (ID) is 50.8 mm; tube length is 14.5 meters; tube wall thickness is 3.5 mm. The total surface area of ​​the exterior surfaces of all process tubes 918 exposed to radiant heating between the two walls of conductive refractory material 902 corresponds to 23.6 square meters.

[0057] The example furnace design shown in FIG8 is modeled for an ethane (C2H6) steam cracking process. The power 908 provided to the conductive refractory material 902 corresponds to an energy input of 0.098 MW for each individual process tube 918. The tube inlet feed conditions are shown in Tables 4 and 5 below. The tube outlet conditions (corresponding to the average variables for each individual process tube 918) are shown in Table 6 below. Table 4 Temperature(℃) 692 Flow rate per pipe (kg / s) 0.033 Pressure (Pascal) 200000 Table 5 type Quality score: <![CDATA[C2H6 (Ethane)]]> 0.714 <![CDATA[C2H4(Ethylene)]]> 0 <![CDATA[H2 (Hydrogen gas)]]> 0 <![CDATA[H2O (water)]]> 0.286 Table 6

[0058] Based on the comparison of the initial mass fraction of ethane (C2H6), as shown in Table 5, the mass fraction of ethane is the same as that shown in Table 6, and the ethane cracking process modeled using the furnace design shown in Figure 8 has an ethane conversion of about 71%. For the thermal data, the flux at the heating wall corresponds to 33.44kW / m2 (averaged based on the wall area); the flux at the tube wall corresponds to about 49.2kW / m2 (averaged based on the identifier associated with each individual process tube 918). For the wall temperature data, the maximum wall temperature simulated is about 1210.6°C, and the average wall temperature measurement is about 1189°C. Figure 9 is a graph 1000 depicting the tube temperature curve, where the top line ("thickness") corresponds to the temperature at the outer diameter (TOD) of the process tube 918, the middle line (roughly parallel to the bottom edge of the thick top line, but not visible in Figure 9) corresponds to the temperature at the inner diameter (T_ID) of the process tube 918, and the bottom line corresponds to the temperature of the process gas (Tgas) within the process tube 918. The "thickness" of the top line in the graph 1000 shown in FIG. 9 is because there is a range of temperatures around the circumference of each individual process tube 918, with the highest temperatures facing the heated wall and the lowest temperatures facing the adjacent tubes.

[0059] The above description and examples provide a complete description of the structure and use of exemplary embodiments. Although certain embodiments have been described above with a certain degree of particularity or with reference to one or more individual embodiments, those skilled in the art may make many modifications to the disclosed embodiments without departing from the scope of the invention. Therefore, the various illustrative embodiments of the present system are not limited to the specific forms disclosed. On the contrary, they include all modifications and alternatives that fall within the scope of the claims, and embodiments other than the illustrated embodiments may include some or all of the features of the illustrated embodiments. For example, components may be combined into a single structure, and / or connections may be replaced. In addition, where appropriate, aspects of any of the above examples may be combined with aspects of any of the other examples described above to form further examples of comparable or different natures and solving the same or different problems. Similarly, it should be understood that the benefits and advantages described above may relate to one embodiment or may relate to several embodiments.

[0060] The claims are not intended to include, nor should they be interpreted as including means-plus- or step-plus-function limitations, unless such limitation is explicitly recited in a given claim using the phrases "means" or "step", respectively.

Claims

1. A heating device, characterized in that: include: Conductive refractory materials without separate heating elements; and a furnace for heating hydrocarbons, wherein the furnace includes one or more process tubes extending through the interior of the furnace and configured to receive process steam or fluid such that the process steam or fluid does not contact the electrically conductive refractory material; wherein the electrically conductive refractory material is at least partially exposed to the interior of the furnace and configured to receive electricity from a power source and generate heat such that the electrically conductive refractory material radiates heat to the interior of the furnace.

2. The device according to claim 1, characterized in that The conductive refractory material is a ceramic material.

3. The device according to claim 1, characterized in that One or more of the process tubes are spaced apart from the electrically conductive refractory material such that process vapor or fluid does not contact the electrically conductive refractory material.

4. The device according to any one of claims 1 to 3, characterized in that The one or more process tubes include a plurality of process tubes.

5. The device according to claim 4, characterized in that Wherein a plurality of process tubes are arranged into two or more rows of process tubes, and the rows are alternated with conductive refractory materials.

6. The device according to claim 4, characterized in that The plurality of process tubes are arranged into a single row of a plurality of process tubes.

7. The device according to claim 4, characterized in that Wherein each individual process tube of the plurality of process tubes is spaced apart from the electrically conductive refractory material by at least a process tube wall thickness corresponding to a difference between an outer diameter of the process tube and an inner diameter of the process tube.

8. The device according to any one of claims 1 to 7, characterized in that The conductive refractory material is formed into a cylinder, a plate or a rod.

9. The device according to any one of claims 1 to 7, characterized in that wherein the electrically conductive refractory material forms a channel, wherein the one or more process tubes comprises a plurality of process tubes, and Each of the plurality of process tubes is arranged in a corresponding channel.

10. The device according to any one of claims 1 to 9, characterized in that Wherein one or more process tubes of the furnace are configured to receive process steam or fluid associated with a process selected from the group consisting of: steam cracking; steam methane reforming for syngas production; reforming for ammonia, hydrogen or methanol; propane dehydrogenation to propylene; and tar cracking.

11. The device according to any one of claims 1 to 10, characterized in that The electrical power from the power source corresponds to a voltage greater than 500 volts, preferably greater than 1000 volts, more preferably greater than 2000 volts.

12. A method of operating a chemical process, characterized in that The method includes: providing a furnace having an electrically conductive refractory material, the electrically conductive refractory material being at least partially exposed to an interior of the furnace, the electrically conductive refractory material not having a separate heating element, wherein the furnace includes one or more process tubes extending through the interior of the furnace, the process tubes being configured to receive process steam or fluid such that the process steam or fluid does not contact the electrically conductive refractory material; and applying electricity directly to the electrically conductive refractory material such that an electric current flowing through the electrically conductive refractory material generates thermal energy to increase a temperature of the electrically conductive refractory material and heat the process steam or fluid in the process tubes.

13. The method according to claim 12, characterized in that One or more process tubes are spaced apart from the conductive refractory material such that the one or more process tubes do not contact the conductive refractory material, and wherein the chemical process is selected from the group consisting of: a process selected from the group consisting of: steam cracking; steam methane reforming for producing synthesis gas; reforming for ammonia, hydrogen or methanol; propane dehydrogenation to propylene; and tar cracking.

14. The method according to any one of claims 12-13, characterized in that wherein the chemical process is a steam methane reforming process, wherein the one or more process tubes comprises a plurality of process tubes, and wherein each individual process tube in the plurality of process tubes is separated from the electrically conductive refractory material by at least a process tube wall thickness corresponding to a difference between an outer diameter of the process tube and an inner diameter of the process tube.

15. The method according to any one of claims 12-13, characterized in that: wherein the chemical process is a steam cracking process corresponding to an ethane cracking process or an olefin steam cracking process, wherein the one or more process tubes comprises a plurality of process tubes, and wherein each individual process tube in the plurality of process tubes is separated from the electrically conductive refractory material by at least a process tube wall thickness, the process tube wall thickness corresponding to a difference between an outer diameter of the process tube and an inner diameter of the process tube.

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