Electroreactor furnace with element configuration to mitigate corner effects

Abstract

The present disclosure includes radiant electric furnaces having heating element configurations that reduce corner effects and localized temperature peaks, e.g., to extend the operational life of the electrical heating elements. More specifically, the furnace of the present invention includes electrical heating elements distributed along the interior of one or more (e.g., two opposing) furnace side walls, and by spacing such heating elements from a corner defined by the respective side wall and the respective furnace end wall. To reduce local temperature peaks that would otherwise be experienced by the heating element and to increase the operating life of the heating element. Such configurations are particularly effective for industrial scale furnaces, e.g., wherein the one or more electrical heating elements on each sidewall are configured to emit at least 30 kilowatts per square meter of the inner surface to the respective sidewall (kW / m2).

Description

Technical Field

[0001] This disclosure generally relates to methods for producing chemicals, and more specifically, but not in a limiting way, to radiant furnaces for chemical reactions, and methods for steam cracking and steam methane reforming using such furnaces. Background Technology

[0002] Chemical synthesis units are used to supply a variety of chemicals. Typically, dedicated fuels are burned or incinerated to provide the heat of reaction for chemical synthesis, energy for heating one or more process streams, energy for evaporating liquids (e.g., boiling water used as a diluent), energy for performing work (e.g., driving compressors or pumps), or energy for other process operations throughout the chemical synthesis unit. Such combustion or incineration of fuel results in the production of flue gas containing CO2, which can be harmful to the environment and also leads to energy efficiency losses in the process. Similarly, steam is typically used within chemical synthesis units as a unit-wide heat and / or energy transfer fluid. Steam used for heat and / or energy transfer is typically generated via the combustion of fuel, resulting in additional flue gas and further energy efficiency losses during chemical synthesis.

[0003] An alternative to heating in chemical synthesis apparatuses that avoid the use of fuel combustion is to instead provide heating via electrical mechanisms, such as in a radiant furnace. However, the electrification of certain components in chemical synthesis apparatuses introduces additional problems and challenges. For example, electric furnaces may present problems or considerations that differ from and / or are not necessarily present in combustion furnaces. Summary of the Invention

[0004] This disclosure includes radiant furnaces with heating element configurations that reduce corner effects and localized temperature spikes, for example, to extend the operational life of the electric heating elements. More specifically, the furnace of the present invention includes electric heating elements distributed along the interior of one or more (e.g., two opposing) furnace sidewalls, and by spacing such heating elements from corners defined by the respective sidewalls and respective furnace endwalls, localized temperature spikes that the heating elements would otherwise experience are reduced and the operational life of the heating elements is increased.

[0005] Some configurations of the radiant furnace of the present invention include: a shell, one or more first electric heating elements, one or more second electric heating elements, and a plurality of reactor tubes. In some such configurations, the shell includes a first sidewall, a second sidewall spaced apart from and opposite to the first sidewall, a first end wall extending between the first and second sidewalls at a first end of the shell, and a second end wall extending between the first and second sidewalls at a second end of the shell, opposite to and between the first and second sidewalls, wherein the shell defines a radiant heating chamber having a width extending between the first and second sidewalls, a length extending between the first and second end walls, and a height extending from the top end of the first sidewall to the bottom end of the first sidewall. In some such configurations, one or more first electric heating elements are disposed on the inner side of the first sidewall; one or more second electric heating elements are disposed on the inner side of the second sidewall; and a plurality of reactor tubes are disposed between the first and second electric heating elements, extending at least a majority of the height of the radiant heating chamber. In some such configurations, a first minimum distance between the first heating element and the first end wall is equal to or greater than 0.1 m; and a second minimum distance between the second heating element and the first end wall is equal to or greater than 0.1 m.

[0006] In some of the aforementioned configurations of the radiant furnace of the present invention, the first minimum distance is 0.1 to 0.75 meters (m). In some such configurations, the first minimum distance is 0.25 to 0.5 meters (m).

[0007] In some of the aforementioned configurations of the radiant furnace of the present invention, the second minimum distance is 0.1 to 0.75 meters (m). In some such configurations, the second minimum distance is 0.25 to 0.5 meters (m).

[0008] In some of the aforementioned configurations of the radiant furnace of the present invention, the first minimum distance is equal to the second minimum distance.

[0009] In some of the aforementioned configurations of the radiant furnace of the present invention, one or more first heating elements extend along a plurality of elongated first path segments, each of which is offset by a first offset distance relative to an adjacent first path segment; and one or more second heating elements extend along a plurality of elongated second path segments, each of which is offset by a second offset distance relative to an adjacent second path segment. In some such configurations, a first minimum distance is greater than 150% of the first offset distance (e.g., greater than 200%, greater than 400%, etc.). In some such configurations, the plurality of elongated first path segments comprises 16 or more elongated first path segments intersected by lines extending the shortest distance between a first end wall and a second end wall; and / or the first and second path segments are each linear.

[0010] In some of the aforementioned configurations of the radiant furnace of the present invention, one or more electric heating elements on each sidewall are configured to emit at least 30 kilowatts (kW / m²) of heat per square meter of inner surface to the respective sidewall. 2 In some such configurations, one or more electric heating elements comprise iron-chromium-aluminum (FeCrAl).

[0011] In some of the aforementioned configurations of the radiant furnace of the present invention, the housing further includes a top portion wall extending between the respective top portions of the first end wall and the second end wall, and the first side wall and the second side wall, wherein a third minimum distance between the first heating element and the top portion wall is greater than a first offset distance, and wherein a fourth minimum distance between the second heating element and the top portion wall is greater than the first offset distance.

[0012] The term "connection" is defined as a link, although not necessarily a direct connection, and not necessarily a mechanical connection; the two items "connected" 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%.

[0013] 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 package that “comprises,” “has,” “includes,” or “contains” one or more elements possesses, but is not limited to, possessing only those elements. Similarly, a method that “comprises,” “has,” “includes,” or “contains” one or more steps possesses, but is not limited to, possessing only those steps.

[0014] In addition, a device, apparatus or system constructed in a certain way is constructed at least in that way, but may also be constructed in other ways than those specifically described.

[0015] Any embodiment of any device and method of the present invention 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 open-ended connecting verbs listed above in order to change the scope of the given claim from the scope that would have been used with the open-ended connecting verb.

[0016] Details and other details relating to the implementation scheme described above are presented below.

[0017] Some details relating to aspects of this disclosure have been described above, and other details are described below. Other embodiments, advantages, and features of this disclosure will become apparent after a review of the entire application (including the description of the drawings, detailed description, and claims). Attached Figure Description

[0018] The following figures are shown by way of example and not limitation. For the sake of simplicity and clarity, each feature of a given structure is not always labeled in every drawing in which the structure appears. The same labels or reference numerals do not necessarily indicate the same structure. Rather, the same reference numerals may be used to indicate similar features or features with similar functions, and so may different reference numerals. 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.

[0019] Figure 1 A flow chart depicting a typical methanol synthesis unit or method is provided.

[0020] Figure 2 A flow diagram depicts a radiant electric heater that can be constructed for use in... Figure 1 In the synthesis gas synthesis section of the apparatus or method.

[0021] Figure 3 A flow diagram of a common steam cracking unit or method is depicted.

[0022] Figure 4 Depicting Figure 3 A flow chart of the pyrolysis reaction section of the apparatus or method.

[0023] Figure 5A Describing for Figure 1 Syngas synthesis section or Figure 3 A front cross-sectional view of an example of an electric furnace structure in a pyrolysis reaction section.

[0024] Figure 5B A conventional configuration with one or more electric heating elements is depicted. Figure 5A A cross-sectional side view of the inner side of the second side wall of the furnace.

[0025] Figure 6A Depicting Figure 5B The enlarged portion of the second sidewall, such as Figure 5B The box marked 6A is shown in the middle.

[0026] Figure 6B Depicting Figure 5A The enlarged portion of the first sidewall of the furnace, this portion is Figure 6A A partial mirror image.

[0027] Figure 7A One of the constructions of the present invention, having one or more electric heating elements, is depicted. Figure 5A A cross-sectional side view of the inner side of the second side wall of the furnace.

[0028] Figure 7B Depicting Figure 7A The enlarged portion of the second sidewall, such as Figure 7A The box marked 7B is shown in the middle.

[0029] Figure 8 Another example of an alternative path shape for a heating element is depicted.

[0030] Figures 9A-9C Temperature distribution diagrams are depicted for each of several modeling embodiments of the radiant furnace of the present invention.

[0031] Figure 10A-10D Temperature distribution diagrams are depicted for the hottest portions of each of several modeling embodiments of the radiant furnace of the present invention, specifically showing the regions of such portions that have experienced high temperatures.

[0032] Figure 11 A graph depicting the highest temperature, average temperature, and temperature-area ratio of each of several modeling examples of the radiant furnace of the present invention is provided. Detailed Implementation

[0033] Now refer to the attached diagram, and more specifically to... Figure 1 A flow diagram of a typical methanol synthesis unit is shown, comprising one or more of the following process sections for converting feed stream 5 into methanol product stream 45 (and optionally one or more by-product streams 41): feed pretreatment section 10, syngas synthesis section 20, methanol synthesis section 30, methanol purification section 40, or a combination thereof. Such sections will be briefly described in the following paragraphs and in more detail below.

[0034] As shown in the methanol synthesis flow diagram, the feed pretreatment section 10 of the methanol synthesis unit is operable to prepare (e.g., remove undesirable components such as sulfur, and regulate its temperature and / or pressure) feed 5 for reforming to provide pretreated feed 15. In some applications, the methanol synthesis unit of this disclosure does not include a feed pretreatment section. The syngas synthesis section 20 is operable to produce syngas from feed 5 or pretreated feed 15 to produce syngas synthesis product 25 comprising carbon monoxide (CO) and hydrogen (H2).

[0035] In some embodiments, the syngas generation section 20 is a syngas synthesis section operable to perform steam reforming of the feed (e.g., feed 5 containing natural gas or pretreated feed 15) to produce reformer products containing carbon monoxide (CO) and hydrogen (H2). The syngas synthesis (or "reformer") product 25 may additionally contain carbon dioxide (CO2), water, methane (CH4), and / or impurities. For example, some embodiments of the electric furnace of the present invention may include a steam reforming catalyst to carry out the syngas reaction to produce carbon monoxide and hydrogen.

[0036] The methanol synthesis section 30 is operable to produce methanol from the synthesis product 25 of the syngas and thus provide a crude methanol stream 35. The methanol purification section 40 is operable to separate purified methanol product 45 and byproduct 41 from the crude methanol stream 35.

[0037] Now for reference Figure 2 A block diagram of a radiant electric heater 100 is shown, which can be configured for use in Figure 1In the syngas synthesis (steam reforming) section 20 of the apparatus or method. For example... Figure 2 As shown, the furnace typically includes a fluid inlet 104 and a fluid outlet 108.

[0038] Figure 1 and Figure 2 An example of a methanol synthesis system has been described for illustrative purposes, but the radiant furnace of the present invention can be used in any of a variety of chemical synthesis systems and methods, particularly as an alternative to furnaces historically driven by direct combustion or fossil fuels.

[0039] Now for reference Figure 3 The diagram illustrates a flow chart of an example of a general steam cracking unit or method, comprising one or more of the following process sections for converting feed stream 50 into a desired olefin product stream 90: feed pretreatment section 55, pyrolysis reaction section 65, primary fractionation and compression section 75, product fractionation (separation) and compression section 75, or a combination thereof. Such sections will be briefly described in the following paragraphs and in more detail below.

[0040] The feed pretreatment section 55 can be configured to regulate the pressure of the feed 50, remove unwanted components from the feed if possible, combine the incoming feed with the stored feed to minimize variations in the feed to the pyrolysis reaction section 65, evaporate the feed 50, and / or preheat the feed 50 to provide a pretreated feed stream 60.

[0041] The pyrolysis reaction section 65 may include at least one steam cracker 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 70. Conventionally, furnaces in steam cracking units generate a high-temperature environment by burning fuels such as methane and hydrogen, which produces carbon dioxide emissions from conventional steam cracking units / methods. However, in this embodiment, the furnace is instead a radiant furnace, in which electrically heated elements provide heat or thermal energy from the heating chamber to the tubes through which the feed stream flows (e.g., reactor tubes).

[0042] The primary fractionation and compression section 75 can be configured to provide additional heat recovery from the cooled cracked gas stream 70 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 70, and / or compress the cracked gas stream 70, thus providing a compressed cracked gas stream 80.

[0043] The product fractionation or separation section 85 can be configured to fractionate compressed cracked gas stream 80, selectively hydrogenate one or more streams generated during fractionation, and provide one or more olefin (e.g., ethylene, propylene) product streams 90. The product fractionation or separation section 85 may also provide one or more by-product streams 86, such as, but not limited to, C1 streams, C2 saturated streams, C3 saturated streams, C4 saturated streams, acetylene streams, butadiene streams, L-butene streams, isobutene streams, aromatic streams, hydrogen streams, pyrolysis gasoline streams and / or fuel oil streams, 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 65, 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 also be recycled for use as fuel (e.g., for producing hydrogen from it).

[0044] Now for reference Figure 4 And as described above, the pyrolysis reaction section 65 may include at least one steam pyrolysis unit or "pyrolysis" furnace 100a, configured to crack hydrocarbons in the presence of steam to produce a cracked gas stream; and a quenching unit (e.g., a transfer line heat exchanger (TLE) or other heat transfer device) that quenches the cracked gas stream (and optionally harvests heat from it) to provide a cooled cracked stream 25. Figure 4 As shown, the furnace typically includes a fluid inlet 104 and a fluid outlet 108, wherein the fluid outlet 108 is in fluid communication with the fluid inlet of the quenching unit.

[0045] Figure 3 and Figure 4 An example of a steam pyrolysis system has been described for illustrative purposes, but the radiant furnace of the present invention can be used in any of a variety of steam pyrolysis systems and methods.

[0046] Figures 5A-5B The illustration shows aspects of the construction of an example furnace 100b that can be used for furnace 100 or furnace 100a; Figure 5A A side cross-sectional view of furnace 100b is depicted; and Figure 5BA cross-sectional view showing the inner side surface of the sidewall of furnace 100b is depicted. As shown, furnace 100b includes a housing 112 defining a radiant heating chamber 116 having a top 120 and a bottom 124 separated by a chamber height 128. In this configuration, furnace 100b also includes one or more (e.g., multiple, as depicted) first electric heating elements 132a disposed on a first side 136 of the chamber; and one or more (e.g., multiple, as depicted) second electric heating elements 132b disposed on a second side 140 of the chamber, the second side being separated from the first side by a chamber width 144. As shown, the (one or more) second electric heating elements 132b are thus spaced apart from the (one or more) first electric heating elements 132a. In this configuration, the heating elements comprise a plurality of heating elements extending along a substantial portion of the length 128 of each of the first and second walls. In other embodiments, a single large heating element may be disposed on one or both of the first side 136 and the second side 140 of the chamber.

[0047] A heating element assembly typically includes a conductive heating element having a first end and a second end, an electrical connector connected to the first and second ends, and a mechanism for securing the heating element to a furnace wall (e.g., one or more brackets, fasteners, mounts, and / or the like), through which power can be supplied to the heating element. Such a heating element can extend between its first and second ends in any manner, either in a regular or irregular pattern. Examples include a single straight line, a meandering pattern of substantially parallel line segments, a meandering pattern of zigzag line segments, and combinations thereof. In the case of meandering patterns, these patterns can extend horizontally or vertically through the furnace wall, and the heating element can include a single channel of the meandering pattern or multiple channels of the meandering pattern that are adjacent to each other (e.g., offset).

[0048] Such heating element assemblies can be distributed on the furnace sidewall in any configuration. For example, the furnace wall may include a single large heating element assembly, multiple heating element assemblies arranged vertically (e.g., offset) above each other across the length of the wall, multiple heating element assemblies arranged horizontally adjacent to each other (e.g., offset) across the height of the sidewall, or a patchwork of heating element assemblies whose dimensions do not extend across the entire height or length of the furnace sidewall. In a preferred embodiment, the heating element assemblies and the heating elements thereon are arranged to produce uniform heating on the furnace sidewall, for example, by constructing the heating elements on the heating element assemblies in a manner that provides continuous and uniform coverage in the height and width of the heating element assemblies, and by avoiding gaps between adjacent heating element assemblies.

[0049] The heating element can comprise any conductive material, such as metals and metal alloys (e.g., nickel / chromium (NiCr) or iron / chromium / aluminum (FeCrAl) alloys) and conductive ceramics (e.g., silicon carbide (SiC) or molybdenum disilicide (MoSi2)). Between the first and second ends of the heating element, the cross-sectional shape and dimensions are generally substantially uniform, regardless of the pattern followed by the heating element between them. For example, the heating element can have a cylindrical geometry (circular cross-section), a strip or ribbed geometry (rectangular cross-section), or any other suitable cross-sectional shape.

[0050] The heat flux delivered by the heating element assembly can be considered as the flow of heat energy delivered per unit surface area of ​​the portion of the corresponding wall located below a minimum rectangle, which is substantially parallel to the wall and surrounds one or more heating elements on the wall. This heat flux depends in particular on the potential difference applied between the first and second ends of the heating element, the cross-sectional shape and size of the heating element, the material (and corresponding resistance) of the heating element, and the density of the heating element pattern (e.g., the spacing between adjacent meanders in a meandering heating element pattern and the spacing between adjacent channels in a meandering pattern of a heating element comprising multiple such channels). In some preferred configurations, the heating element assembly is configured to provide a substantially uniform heat flux over the wall region occupied by the assembly (e.g., by applying a uniform density of the heating element pattern) and a substantially uniform heat flux over a large portion of the furnace sidewall (e.g., by spacing adjacent heating element assemblies in such a manner that the gaps between heating element assemblies are much larger than the intervals between features (meanders, channels) on a single heating element assembly). When the heating elements operate within their operating boundaries, such an arrangement can provide the maximum total wall heat flux (the total flow of heat energy delivered by the heating element assembly fixed to the sidewalls divided by the total area of ​​the sidewalls).

[0051] The primary material of the heating element is one of the most important factors determining the operating temperature range of the heating element. For example, NiCr alloys are typically used at element temperatures up to 1100–1200 °C, while FeCrAl alloys are used at element temperatures up to 1350 °C. Another important consideration in specifying the heating element material and construction is the expected operating life, which depends on the heating element material and geometry, the chemical environment surrounding it during operation, and the temperatures reached by the heating element during operation (this includes dynamic temperature effects, such as rapid or slow temperature gradients and / or cycling during operation). For a given material and geometry, the temperature of the heating element plays a significant role in its operating life. For example, for FeCrAl heating elements, scientific literature reports failure modes caused by progressive oxidation at high temperatures. The oxidation rate can be a strong function of temperature; for example, the lifespan of a heating element at 1200 °C can be more than twice that at 1250 °C. For this reason, even a relatively small reduction in the maximum temperature experienced by the heating element can significantly improve its lifespan.

[0052] like Figure 5AAs shown, furnace 100a also includes a plurality of hollow tubes or coils (e.g., reactor tubes) 148 extending from top 120 toward bottom 124 within a chamber. In the depicted configuration, each tube 148 has an inlet section, an outlet section, and an intermediate section 152 between the inlet and outlet sections. For each tube 148, the inlet and outlet sections extend from top 120 toward bottom 124 of the chamber in a first direction, and the intermediate section 152 is positioned closer to the bottom 124 of the chamber than the top 120. In this depicted example, each inlet section includes two tubes that split the inlet flow into two paths with a larger surface area per unit mass flow rate, and thus, the temperature rises faster (and generally greater) through the inlet section than through the outlet section. Each tube in the inlet section has a first diameter, which may be smaller than the second diameter of the tube in the corresponding outlet section. In this configuration, the pipes of the inlet and outlet sections are each arranged equidistant from the first and second sides 136, 140 to balance the amount of heat energy absorbed by the pipe 148 from each heating element. Various other configurations may include any number of pipes in any of a variety of symmetrical or asymmetrical configurations (e.g., inlets grouped together and outlets grouped together). For example, the pipes or coils in other configurations of the furnace of the present invention may have any shape, size, or configuration, including any used in industrial practice (e.g., in steam cracking and steam reforming furnaces). For example, such pipes may extend linearly through the furnace, with the inlet and outlet at opposite ends of the furnace. Such pipes may also be combined or separated within the furnace, thus having a different number of inlets than outlets (e.g., a number of inlets that is a multiple of the number of outlets, or a number of outlets that is a multiple of the number of inlets). For example, the outer diameter of the pipes may fall in the range of 2 cm to 20 cm (e.g., 2 cm to 5 cm, from 4 cm to 10 cm). Such tubes can also be oriented or arranged relative to each other in any of a variety of ways, such as by alternating inlets and outlets, by grouping several inlets together in one part of the furnace and several outlets together in another part of the furnace, and / or by using their different symmetrical or asymmetrical combinations.

[0053] In the depicted example, the intermediate section 152 of each pipe 148 extends from a first end at the inlet section to a second end at the corresponding outlet section, defining a change in the direction of each pipe. In this configuration, the inlet and outlet sections are each defined by straight sections of the conduit, and the intermediate section 152 extends between those straight sections of the conduit. In other configurations, the shapes of the inlet and outlet sections may vary. The fluid inlet conduit 104a is in fluid communication with the inlet section of pipe 148, and the fluid outlet conduit (not shown) is in fluid communication with the outlet section of pipe, such that fluid flowing into the inlet conduit 104a sequentially passes through the inlet section of pipe 148, the intermediate section 152 of pipe 148, and the outlet section of pipe 148, flowing to the fluid outlet conduit.

[0054] Figure 5B A plan view of the inner surface of the second sidewall 140 (which may be generally a mirror image of the first sidewall 136) is depicted. As shown in this example, each sidewall 140 (and 136) extends between a first end wall 156 and a second end wall 160, wherein the end walls 156, 160 are separated from each other by a chamber length 164. One or more (e.g., multiple, as shown) electric heating elements 168 are disposed on the inner surface of the sidewall 140. For the type of chemical synthesis system contemplated by this disclosure, the furnace of the present invention is typically implemented on an industrial scale. For example, chamber 116 may have a height of five (5) meters or greater 128 (e.g., greater than any one of 5, 10, 15 and / or 20 meters or between any two of them); a width of 0.5 meters or greater 144 (e.g., greater than any one of 0.5, 1, 2, 3, 4 and / or 5 meters or between any two of them); and a length of one (1) meter or greater 164 (e.g., greater than any one of 1, 2, 5, 10 and / or 20 meters or between any two of them).

[0055] like Figure 5B As shown, the heating element 168 spans a large portion of the surface area of ​​the corresponding sidewall 140. For example, in the depicted example, the heating element spans multiple path segments that alternate in direction (back and forth in the direction of height 128) while extending in the direction of length 164. In such a configuration, the multiple elongated first path segments may comprise sixteen (16) or more path segments that intersect with a line (e.g., 172) extending the shortest distance between the first end wall and the second end walls 160, 156. For example, in Figure 5B In the middle, line 172 intersects with 21 individual path segments of heating element(s) 168. In such an example, heating element(s) 168 can be configured to emit at least 30 kW / m² of internal surface area per square meter to the corresponding sidewall (e.g., 140). 2The rate and areal density of energy, for example, at least 30 kW / m². 2 40kW / m 2 60kW / m 2 80kW / m 2 Or larger. As described above, heating element 168 can have any geometry that enables the furnace to operate as described herein. For example, segment 168a can extend horizontally such that each heating element (or a portion thereof) meanders vertically (and the vertical line intersects multiple segments 168a). In another instance, the heating element may comprise ceramic (e.g., silicon carbide), and individual path segments may extend substantially linearly (in contrast to their alphanumeric form) along the sidewalls over the entire dimension spanned by the heating element.

[0056] Now for reference Figures 6A-6B ; Figure 6A It shows the corresponding Figure 5B The enlarged portion of the second sidewall 140 of the region marked 6A; and Figure 6B The corresponding mirror image of the first sidewall 136 is depicted. Figure 6A and 6B Both illustrate the heating element construction in more detail. More specifically, in the depicted example, one or more heating elements 168 extend along a plurality of elongated first path segments 168a, each elongated first path segment 168a offset by an offset distance 176 relative to at least one of its adjacent first path segments. The offset distance can be consistent between each pair (or most pairs) of adjacent path segments. In the depicted example, a given heating element 168 includes a plurality of (e.g., linear) path segments 168a, each path segment 168a extending upward or downward in the direction of height 128 as the heating element also traverses along the direction of length 164 in increments of offset distance 176. The offset distance 176 can be, for example, 50 mm to 100 mm or greater (e.g., greater than any one of 50 mm, 75 mm, 100 mm, 125 mm and / or 150 mm or between any two of them). As described above, a single heating element can traverse length 164 once or multiple times.

[0057] In the depicted configuration, the heating element 168 is spaced from the end wall 156 by a minimum distance 180 less than or equal to the offset distance 176. While it is conventionally understood in the art to maximize the heating element in the heating chamber 160 by distributing the heating element over all or almost all of the area extending into the paths of the end walls 156, 160, at least in part, due to the proximity of the heating element to such end walls (and the corners where the end walls 156, 160 intersect with their respective side walls 136, 140), the walls and heating elements may experience localized temperature maximums exceeding the desired operating temperature of the heating element, thus posing a risk of degradation and reduced service life of one or more of the respective heating elements. This heating element configuration mitigates such corner effects.

[0058] Figures 7A-7B For example, an alternative end wall 140a is depicted as an example of an embodiment having this heating element configuration, wherein the heating element(s) are relative to at least one of the end walls (e.g., the first end wall 156, such as...). Figure 7B (As shown in detail) the offset is a larger distance. However, as... Figure 7A As shown, the heating element is also offset relative to the second end wall 160. In other configurations, the heating element may be offset by a different distance relative to the second end wall 160 (e.g., a greater offset relative to the end wall closest to the outlet or "hot" side of the tube 148 than relative to the end wall closest to the inlet or "cold" side of the tube). More specifically, in this configuration, the minimum distance 180a between (one or more) heating elements and their respective end walls may be defined as 0.1 to 0.75 meters (e.g., 0.25 to 0.5 meters), and / or, for configurations where heating element path segments are regularly offset as shown, defined in a relative manner (e.g., greater than the offset distance 176 between adjacent heating element path segments 168a) and / or in an absolute manner (e.g., at least 0.1 meters). For example, in some configurations, the minimum distance 180a between the heating element(s) 168 and the corresponding end walls (156, 160) is greater than 150% of the offset distance 168 (e.g., greater than any one of 150%, 200%, 400%, and / or 500%, or between any two thereof). Regardless of how its dimensions are defined, in this configuration, the open space provided between the heating element and the adjacent corner (without the heating element) reduces excessively high maximum temperatures in the corresponding corner region, thereby reducing the local temperature maximum, decreasing the likelihood of failure, and extending the operational life of the corresponding heating element(s).

[0059] Similarly, in some configurations of this furnace, where the first end or top portion 120 is defined by a top wall (thus defining a corner at the intersection of the top wall and each side wall 136, 140), the heating element is also offset relative to the top wall by a minimum distance 184 greater than the offset distance 176. Like the minimum distance 180a, the minimum distance 184 between (one or more) heating elements and the top wall can be defined in a relative manner (e.g., greater than the offset distance 176 between adjacent heating element path segments 168a) and / or in an absolute manner (e.g., at least 0.1 meters). For example, in some configurations, the minimum distance 184 between (one or more) heating elements 168 and the top wall is greater than 150% of the offset distance 168 (e.g., greater than any one of 150%, 200%, 400%, and / or 500%, or between any two thereof); and / or the minimum distance 184 between (one or more) heating elements 168 and the top wall is 0.1 to 0.75 meters (e.g., 0.25 to 0.5 meters). By providing an open space (without a heating element) between the heating element and the adjacent corner, this construction reduces the excessively high maximum temperature in the corresponding corner area, thereby reducing the maximum local temperature, reducing the likelihood of failure, and extending the operating life of (one or more) of the corresponding heating elements.

[0060] Although for illustrative purposes, path segment 168a in Figure 5A-7B The segments are shown as parallel to each other, but it should be understood that such path segments may not be exactly parallel. For example, in some cases (such as...) Figure 8 As shown, the heating element can be arranged in alternating directions around opposing sets of knobs, the diameter of which (e.g., 25 mm) is less than the distance (e.g., 50 mm) by which the knob is offset in the direction of length 164, such that adjacent path segments 168a diverge. In such a configuration, knobs of uniform size are used, positioned at consistent intervals in the direction of length 164, and the offset distance 168 between adjacent path segments is the average offset found at the longitudinal center between adjacent knobs in at least one of the two adjacent path segments.

[0061] As those skilled in the art will understand, the insulating material covering the furnace walls (including end walls) can have varying degrees of flexibility (e.g., it can include a fiber blanket), resulting in the internal wall surface potentially not being uniformly flat (planar). Therefore, the distance between the outermost portion of the heating element and the adjacent end wall (and / or the corner between such end wall and the corresponding side wall of the heating element) may be non-uniform along the vertical dimension of the furnace, and may even vary to some extent during operation due to thermal movement (expansion / contraction) of the material. Therefore, in at least some of these configurations, it is prudent to include some margin of error beyond the minimum or optimal gap spacing that can be derived from ideal calculations, as can be inferred from the embodiments described below.

[0062] Example

[0063] To better understand the effects of separating the heating element from the internal corner, several variations of the radiant furnace in the steam cracking method were modeled using Ansys simulation software (available from Ansys, Inc., Canonsburg, Pennsylvania, USA).

[0064] Figures 9A-9C Temperature distribution diagrams are depicted for each of several modeling embodiments of the radiant furnace of the present invention. More specifically, Figure 9A Depicting Figure 5B and 6A Temperature distribution map of half of the sidewall 140, where half is taken from the midpoint of length 164; Figure 9B Depicting Figure 7A and 7B Temperature distribution map of the corresponding half of the sidewall 140a, where the distance from 180a is 0.25 meters; and Figure 9C Depicting Figure 7A and 7B Temperature distribution diagrams of the corresponding half of the sidewall 140a, where the distance from 180a is 0.5 m. In each of these images, the bottom end 124 is on the left, the second end wall 140 is at the bottom, the first end wall 136 is at the top, and the top end 120 is on the right, such that the height 128 extends from left to right and the length 164 extends from top to bottom. Figure 9A and Figure 9B The difference shows that adding a 0.25-meter gap (distance 180a) between the heating element (168) and the end wall 156 reduces the portion of the side wall 140 subjected to temperatures exceeding 1245°C. And refer to... Figure 9C The increase of 0.5 meters in interval (distance 180a) reduced the maximum temperature of the sidewall 140 by approximately 23°C, from 1270°C to 1247°C.

[0065] Figure 10A-10DTemperature distribution maps of the lower part of the furnace (which corresponds to the hottest part of the furnace in this configuration) are depicted in several modeling embodiments of this radiant furnace, specifically showing the areas of such parts that have experienced high temperatures. Figures 10A to 10D Each share and Figures 9A-9C Same orientation, but Figure 10A-10D Each of them shows approximately 1.5 m of sidewall 140 or 140a. 2 The portion, for each embodiment, represents the hottest part of the sidewall 140. Figure 10A Depicting in Figure 9A The temperature distribution diagram of half of the sidewall is shown in the image. Figure 10B Depicting Figure 7A and 7B Temperature distribution map of half of the corresponding part of the sidewall 140a, where the distance from 180a is 0.125 meters; Figure 10C Depicting in Figure 9B Temperature distribution diagram of a corresponding portion of half of the sidewall, drawn in the figure, with a distance of 0.25 meters from 180a; and Figure 10D Depicting in Figure 9C The temperature distribution map is drawn for a corresponding portion of half of the sidewall, where the distance from 180a is 0.5 meters. (As shown from...) Figures 10A to 10D As the progress has shown, the addition and expansion of the gap between the heating element and the corresponding end wall has significantly reduced the area of ​​the side wall 140a (and the corresponding heating element) subjected to temperatures exceeding 1245°C, which should reduce the likelihood of deterioration and failure and increase the operating life of the heating element.

[0066] As described above, the temperature experienced by a heating element during operation is a strong determinant of its operational life. Therefore, the overall operational life of a heating element may be limited by the portion of the heating element experiencing the highest sustained temperature. Temperature thresholds can be defined for specific heating element materials and geometries, above which the heating element life deteriorates particularly, such as 1245°C in this embodiment. Figure 11 Bar graphs depicting the maximum heating element temperature determined from the simulation model for each of several modeling embodiments of this radiant furnace are overlaid with curves indicating the fraction of surface area in the lower part of the furnace where the heating element temperature exceeds 1245°C. Specifically, Figure 11 Depicting Figure 9A , 9B Data for the 9C embodiment and another embodiment with a distance of 0.125 meters (180a). For each gap size, the bar and the number directly above the bar indicate the maximum temperature, and the line and area fraction unit on the right indicate... Figure 10A-10D The area fraction shown represents the respective sections that withstood temperatures exceeding 1245°C. Relative to... Figure 10AThe basic information includes a maximum temperature of approximately 1257°C and the hottest point on the sidewall is 1.5 m. 2 Approximately 40% of the section experiences temperatures above 1245°C. The addition of gaps not only ensures a reduction in the maximum temperature but also significantly reduces the area of ​​the sidewalls (and corresponding heating elements) exposed to temperatures above 1245°C for modeled steam cracking conditions.

[0067] By reducing not only the magnitude of the temperature exposed to the heating element, but also the portion of the heating element exposed to excessively high temperatures, the heating element in this furnace configuration is expected to experience reduced thermal degradation and a lower likelihood of premature failure. It is noteworthy that, for the aforementioned embodiment, a gap of 0.125 μm reduces the area fraction experiencing temperatures exceeding 1245°C by nearly 60%, and 0.25 μm reduces the area fraction experiencing temperatures exceeding 1245°C by more than 90%. Therefore, while a gap of at least 0.1 μm is expected to meaningfully reduce the risk of premature failure, a gap of at least 0.25 μm is expected to be particularly advantageous for ensuring the operational life of the heating element.

[0068] Further details regarding the various components of the syngas synthesis apparatus and method can be found in International Patent Application Publication No. WO2020 / 150247, which is incorporated herein by reference in its entirety.

[0069] Further details regarding the various components of the steam pyrolysis apparatus and method can be found in International Patent Application Publication No. WO2020 / 150244, which is incorporated herein by reference in its entirety.

[0070] 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.

[0071] The claims are not intended to include and should not be construed as including the limitation of a component plus function or a step plus function, unless such limitation is expressly stated in the given claim by the phrases “component for…” or “step for…”, respectively.

Claims

1. A radiant furnace, comprising A housing having a first sidewall, a second sidewall spaced apart from and opposite to the first sidewall, a first endwall extending between the first and second sidewalls at a first end of the housing, and a second endwall at a second end of the housing opposite to and extending between the first and second sidewalls, wherein the housing defines a radiant heating chamber having a width extending between the first and second sidewalls, a length extending between the first and second endwalls, and a height extending from the top end of the first sidewall to the bottom end of the first sidewall; One or more first electric heating elements are disposed on the inner side surface of the first sidewall; One or more second electric heating elements are disposed on the inner side of the second sidewall; and Multiple reactor tubes are disposed between the first electric heating element and the second electric heating element, and extend at least a majority of the height of the radiant heating chamber; Wherein the first minimum distance between the first heating element and the first end wall is equal to or greater than 0.1 meters (m); and The second minimum distance between the second heating element and the first end wall is equal to or greater than 0.1 m.

2. The radiant furnace according to claim 1, wherein the first minimum distance is 0.1 m to 0.75 m.

3. The radiant furnace according to claim 1, wherein the first minimum distance is 0.25 meters (m) to 0.5 meters (m).

4. The radiant furnace according to any one of claims 1-3, wherein the second minimum distance is from 0.1 m to 0.75 m.

5. The radiant furnace according to claim 4, wherein the second minimum distance is 0.25 meters (m) to 0.5 meters (m).

6. The radiant furnace according to any one of claims 1-5, wherein the first minimum distance is equal to the second minimum distance.

7. The radiant furnace according to any one of claims 1-6, wherein: The first heating element extends along a plurality of elongated first path segments, each of which is offset by a first offset distance relative to an adjacent first path segment in the first path segment; and The second heating element extends along a plurality of elongated second path segments, each of which is offset by a second offset distance relative to an adjacent second path segment.

8. The radiant furnace according to claim 7, wherein the first minimum distance is greater than 150% of the first offset distance.

9. The radiant furnace according to claim 8, wherein the first minimum distance is greater than 200% of the first offset distance.

10. The radiant furnace according to claim 9, wherein the first minimum distance is greater than 400% of the first offset distance.

11. The radiant furnace according to any one of claims 7-10, wherein the plurality of elongated first path segments comprises 16 or more elongated first path segments, the elongated first path segments being intersected by lines extending the shortest distance between the first end wall and the second end wall.

12. The radiant furnace according to any one of claims 7-11, wherein the first path segment and the second path segment are each linear.

13. The radiant furnace according to any one of claims 1-12, wherein one or more electric heating elements on each sidewall are configured to emit at least 30 kilowatts (kW / m²) of heat per square meter of inner surface area to the respective sidewall. 2 ).

14. The radiant furnace according to claim 13, wherein the electric heating element comprises iron-chromium-aluminum (FeCrAl).

15. The radiant furnace according to any one of claims 1-14, wherein the housing further includes a top portion wall extending between the respective top portions of the first end wall and the second end wall and each of the first side wall and the second side wall, wherein a third minimum distance between the first heating element and the top portion wall is greater than the first offset distance, and wherein a fourth minimum distance between the second heating element and the top portion wall is greater than the first offset distance.

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