Direct electrical heating of process heater tubes using galvanic isolation technology.

Abstract

The present disclosure relates to systems and methods for direct electrical heating of process heater tubes (e.g., reactor tubes) utilizing galvanic isolation techniques. The present disclosure also relates to systems and methods for direct electrical heating of process heater tubes, where the tubes are galvanically isolated such that there is no need to electrically isolate the tubes from the rest of the system, such as other tubes, tube inlet and / or tube outlet headers, and reactor shells.

Description

[Technical Field]

[0001] Provided herein are methods and systems for direct electrical heating of catalytic reaction systems. Also provided herein are methods for conducting catalytic reactions, including systems that utilize direct electrical heating. Still further provided herein are systems and methods for direct electrical heating of reactor tubes that utilize galvanic isolation techniques. [Background technology]

[0002] Typically, a reaction system for a catalytic reaction is configured such that a catalyst is placed in a reactor, a fluid (i.e., a liquid or gas) is passed through the reactor, and the product of the catalytic reaction is removed from the reactor and either collected as a final product or directed to further processing.

[0003] Some catalytic reactions require external heating to drive the reaction and / or efficiently produce the desired products. Many systems are known for heating catalytic reactors, including combustion heating. Combustion heating typically consists of either a direct-fired or indirect-fired heating system. In both combustion heating systems, heat is typically generated by the combustion of hydrocarbons. Summary of the Invention [Problem to be solved by the invention]

[0004] However, problems exist when the heat supplied to a reactor system is provided by a combustion heating system. For example, in catalytic reaction systems that include reactor tubes, combustion heating of the reactor tubes often results in non-uniform temperature gradients along the tubes. Non-uniform temperature gradients along the tubes can lead to premature tube failure, adversely affecting throughput, catalyst life, and the yield / quality of the desired product. Furthermore, when multiple reactor tubes are present, there are typically temperature differences between the tubes. Temperature differences between reactor tubes within the same reactor system can result in suboptimal throughput and reduced yield / quality of the desired product. Furthermore, all combustion heaters are subject to typical wear and tear, which ultimately leads to reduced energy efficiency of the combustion heater. When the combustion heater involves the combustion of hydrocarbons or other materials that emit greenhouse gases, such as CO2, reduced energy efficiency of the combustion heater contributes to increased greenhouse gas emissions from the combustion heater.

[0005] One solution to this problem is to utilize direct electric heating. However, a problem exists when a direct electric heating system requires electrical isolation of one or more components. For example, each reactor tube may need to be electrically isolated from the rest of the system, such as other tubes, tube inlet headers, and / or tube outlet headers.

[0006] Thus, there remains a need in the art to develop systems and methods for directly electrically heating process heater tubes (e.g., reactor tubes) where the tubes are electrically isolated from the rest of the system, e.g., other tubes, tube inlet headers, and / or tube outlet headers, etc. There also remains a need in the art to develop systems and methods for directly electrically heating process heater tubes (e.g., reactor tubes) where the tubes are galvanically isolated from the rest of the system, e.g., other tubes, tube inlet headers, and / or tube outlet headers, etc., so as to avoid the use of electrical insulation on the tubes. [Means for solving the problem]

[0007] One embodiment of the present disclosure relates to a method of heating a reactor system comprising at least one reactor tube having a catalyst disposed therein, each reactor tube comprising at least one electrically conductive surface, the method including electrically isolating the reactor tube from other electrically conductive components of the reactor system, supplying electrical energy to the at least one electrically conductive surface of each of the reactor tubes, and individually adjusting a current level of the electrical energy supplied to the at least one electrically conductive surface of each of the reactor tubes to individually control a temperature of one or more of the reactor tubes and the catalyst disposed therein.

[0008] Another embodiment of the present disclosure relates to a method for heating a reactor system including a plurality of reactor tubes having a catalyst disposed therein, each of the plurality of reactor tubes comprising at least one electrically conductive surface, the method including electrically isolating each of the plurality of reactor tubes from other electrically conductive components of the reactor system, supplying electrical energy to the at least one electrically conductive surface of each of the plurality of reactor tubes, and controlling the temperature of each of the plurality of reactor tubes and the catalyst disposed therein by individually adjusting a current level of the electrical energy supplied to the at least one electrically conductive surface of each of the plurality of reactor tubes.

[0009] A reactor system embodying some aspects of the present disclosure includes one or more reactor tubes, each having a catalyst disposed therein, and inlet and outlet pipes through which fluids enter and exit the reactor tubes. The inlet pipes may be referred to interchangeably herein as inlet pipe headers or inlet pipe devices. The outlet pipes may be referred to interchangeably herein as outlet pipe headers or outlet pipe devices. In various embodiments, fluid (i.e., a substance to be heated in a reactor heater system) enters each of the one or more reactor tubes through an associated inlet pipe device and exits each of the one or more reactor tubes through an associated outlet pipe device.

[0010] In some embodiments, the reactor system may also include gaskets between one or more reactor tubes and the inlet and outlet tubing arrangements to electrically insulate each of the one or more reactor tubes from other electrically conductive components of the reactor system.

[0011] The power supply is configured to apply an adjustable current level of electrical energy to at least one conductive surface of each of the one or more reactor tubes to control the temperature of each of the one or more reactor tubes and the catalyst disposed therein.

[0012] The present disclosure relates to a further method for heating a reactor system, the reactor system comprising a plurality of reactor tubes, each of the plurality of reactor tubes having a catalyst disposed therein and at least one electrically conductive surface. A fluid enters each of the plurality of reactor tubes through an associated inlet pipe header and exits each of the plurality of reactor tubes through an associated outlet pipe header. The method includes galvanically isolating the plurality of reactor tubes such that each of the plurality of reactor tubes can be directly connected to the inlet pipe header and the outlet pipe header; supplying electrical energy to the at least one electrically conductive surface of each of the plurality of reactor tubes; and individually adjusting a current level of the electrical energy supplied to the at least one electrically conductive surface of each of the plurality of reactor tubes to individually control a temperature of each of the reactor tubes and the catalyst disposed therein.

[0013] In another embodiment, the present disclosure relates to any of the above reactor systems or methods of heating a reactor system, wherein electrical energy is supplied from a three-phase power source to a transformer. A first phase from the transformer is routed to a first location on the conductive surface of the reactor tube. A second phase from the transformer is routed to a second location on the conductive surface of the reactor tube. A third phase from the transformer is routed to a third location on the conductive surface of the reactor tube. The three phases create multiple heating zones in each of the reactor tubes.

[0014] The present disclosure further relates to a method of heating a reactor system including a plurality of reactor tubes, each of the plurality of reactor tubes having a catalyst disposed therein and having at least one electrically conductive surface, the plurality of reactor tubes being galvanically isolated using a plurality of power controllers, the plurality of power controllers being configured to mirror each other to transition from 0 volts at an inlet header to 0 volts at an outlet header.

[0015] A further embodiment of the present disclosure relates to a method of heating a reactor system comprising a reactor tube having a catalyst disposed therein and at least one electrically conductive surface, the method including galvanically isolating the reactor tube from other electrically conductive components of the reactor system, supplying electrical energy to the at least one electrically conductive surface of the reactor tube, and individually adjusting a current level of the electrical energy supplied to the at least one electrically conductive surface of the reactor tube to control a temperature of the reactor tube and the catalyst disposed therein.

[0016] A further embodiment of the present disclosure relates to a method of heating a reactor system comprising a controller, the method including: executing, by the controller, a cascade control scheme; and adjusting an operational setpoint of the controller according to the cascade control scheme; wherein a power controller coupled to a source of electrical energy adjusts a current level of the source of electrical energy in response to the operational setpoint to heat each of a plurality of reactor tubes to a desired reactor outlet temperature.

[0017] Yet another embodiment relates to a reactor system including a plurality of reactor tubes, each of which has a catalyst disposed therein and at least one electrically conductive surface. Fluid enters the reactor tubes of the plurality of reactor tubes through an associated inlet header and exits the reactor tubes of the plurality of reactor tubes through an associated outlet header. Electrical energy is supplied to the at least one electrically conductive surface of the reactor tubes of the plurality of reactor tubes, and the temperature of the reactor tubes and the catalyst disposed therein are individually controlled by adjusting the current level of the electrical energy supplied to the at least one electrically conductive surface of the reactor tubes of the plurality of reactor tubes. The plurality of reactor tubes are galvanically isolated so that each of the plurality of reactor tubes can be directly connected to the inlet header and the outlet header.

[0018] Other objects and features will be in part apparent and in part pointed out hereinafter. [Brief explanation of the drawings]

[0019] [Figure 1] Block diagram of a reactor system according to an embodiment. [Figure 2] FIG. 2 is a top view of the reactor system of FIG. 1, including multiple reactor tubes with catalyst disposed therein. [Figure 3] FIG. 3 is a side view of an individual reactor tube among the multiple reactor tubes present in the reactor system of FIG. [Figure 4] FIG. 3 is a side view of an individual reactor tube of the reactor system of FIG. 2, the reactor tube having an electrical ground instead of an electrical insulator. [Figure 5] FIG. 3 is a side view of an individual reactor tube of the reactor system of FIG. 2, the reactor tube having an electrical ground instead of an upper electrical insulator. [Figure 6] Top view of an individual reactor tube [Figure 7] FIG. 2 is a side view of the reactor system of FIG. 1 with multiple reactor tubes. [Figure 8] FIG. 1 illustrates a direct power control loop according to an embodiment of a reactor system. [Figure 9]1 is a diagram of an embodiment of a galvanic isolation system. [Figure 10] Diagram showing AC galvanic isolation system showing current connection to tube [Figure 11] Electrical diagram overlaid on reactor heating system including direct electrical heating [Figure 12A] Electrical diagram of one configuration for direct electrical heating and galvanic insulation of the reactor tubes [Figure 12B] Electrical diagram of one configuration for direct electrical heating and galvanic isolation of multiple reactor tubes [Figure 13] 1 is a side view of a heater system according to one embodiment; [Figure 14] Diagram of a galvanic isolation system with multiple heating zones [Figure 15] Diagram of a three-phase galvanic isolation system with multiple heating zones [Figure 16] Alternative tube layout for another embodiment [Figure 17] Electrical diagram overlaid on reactor heating system, reactor tubes with several bends. DETAILED DESCRIPTION OF THE INVENTION

[0020] Corresponding reference characters indicate corresponding parts throughout the drawings.

[0021] One embodiment of the present disclosure relates to a method of heating a reactor system that includes a reactor (e.g., a reactor tube) having a catalyst disposed therein, wherein the reactor and catalyst are heated by supplying electrical energy to at least one electrically conductive surface of the reactor.

[0022] In another embodiment of the present disclosure, the reactor tubes are galvanically isolated to avoid the need for electrical isolation of the reactor tubes from the rest of the system, such as other reactor tubes, inlet pipe headers, and / or outlet pipe headers. Without galvanic isolation, the pipes typically must be individually electrically isolated using flange or gasket arrangements. With galvanic isolation, flanges and gaskets are not required, and the pipes can be directly connected (e.g., welded) to the inlet pipe headers and outlet pipe headers. This has the added benefit of improving the safety of the system with respect to potential fluid leaks and reducing maintenance costs, downtime, and capital investment costs. Such a system of the present disclosure can also reduce the risk of electrical hazards to personnel.

[0023] 1 illustrates a reactor system 100 embodying aspects of the present disclosure. The reactor system 100 comprises a reactor 102 having one or more reactor tubes (not shown) through which material enters the reactor at an inlet 104 and exits the reactor at an outlet 106. A power supply 108 is configured to energize an electrically conductive surface (not shown) of each of the reactor tubes. During operation, a controller 110 regulates the current level of electrical energy supplied by the power supply 108 to the electrically conductive surfaces.

[0024] 2 shows a top view of the reactor 102, which includes multiple reactor tubes 202, each having a catalyst (not shown) disposed therein. In this embodiment, the circles represent individual reactor tubes 202 housed within an insulated housing 204. Additionally, each of the individual reactor tubes 202 is electrically isolated from other electrically conductive elements within the reactor 102 and from each other.

[0025] FIG. 3 shows a side view of one reactor tube 202 as described above. Materials to be contacted with catalyst 302 are introduced through the top of reactor tube 202 via inlet 104, contact the catalyst particles present within reactor tube 202, and exit the bottom of reactor tube 202 via outlet 106. In various embodiments, inlet 104 is an inlet pipe header or inlet pipe arrangement, and outlet 106 is an outlet pipe header or outlet pipe arrangement. FIG. 3 shows an electrical connector 304 from power source 108 connected to the left side of reactor tube 202. Electrical connector 304 is configured to allow electrical energy to be delivered from power source 108 to a conductive surface on reactor tube 202 (e.g., the wall of reactor tube 202 or an external conductor electrically connected to reactor 202). Finally, electrical insulators 308 are shown at the top and bottom of reactor tube 202. The electrical insulators 308 are configured so that each reactor tube 202 is electrically isolated from other electrically conductive elements of the reactor system 100 , such as the inlet 104 and outlet 106 piping, and other reactor tubes 202 .

[0026] One embodiment of the present disclosure relates to a reactor system 100 comprising a plurality of reactor tubes 202 having a catalyst 302 disposed therein. The reactor tubes 202 and the catalyst 302 are heated by a method including supplying electrical energy to at least one electrically conductive surface of each of the plurality of reactor tubes 202. It should be understood that the reactor tubes 202 referred to herein are interchangeable with embodiments described herein with reference to the reactor 102 when the reactor 102 comprises a single reactor tube 202.

[0027] In some embodiments of the present disclosure, the reactor 102 is electrically isolated from other electrically conductive components of the reactor system 100, and the temperature of the reactor 102 and the catalyst disposed therein is controlled by adjusting the current level of electrical energy supplied to at least one electrically conductive surface of the reactor.

[0028] For example, one embodiment of the present disclosure relates to a reactor system 100 comprising a plurality of reactor tubes 202 having a catalyst 302 disposed therein, wherein the plurality of reactor tubes 202 and the catalyst are heated by the following method, which includes electrically isolating each of the plurality of reactor tubes 202 from other electrically conductive components of the reactor system 100, supplying electrical energy to at least one electrically conductive surface of each of the reactor tubes of the plurality of reactor tubes 202, and individually adjusting the current level of the electrical energy supplied to the at least one electrically conductive surface of each of the plurality of reactor tubes to individually control the temperature of each of the reactor tubes of the plurality of reactor tubes 202 and the catalyst 302 disposed therein.

[0029] In some embodiments, a reaction system for a catalytic reaction includes disposing a catalyst in a reactor and passing a fluid (i.e., liquid or gas) through the reactor where the catalytic reaction occurs. The product of the catalytic reaction is then removed from the reactor and either collected as a final product or directed to further processing. In embodiments, the reactor for the catalytic reaction may include a fixed-bed reactor or a fluidized-bed reactor. In a fixed-bed reactor, the catalyst is maintained within a defined space in the reactor, and a fluid flows over the catalyst and / or through the interstitial regions between the catalyst particles. In a fluidized-bed reactor, a fluid is introduced into the reactor at a velocity sufficient to fluidize the catalyst or catalyst particles. A fluidized-bed reactor can maintain the catalyst within a defined area of ​​the reactor (e.g., between two screens) so that the catalyst is not lost during the course of the process. An example of a catalytic reaction system includes one or more reactor tubes with a catalyst disposed therein. In other embodiments, a reactor bed system may include a screening process to remove the catalyst from the fluid present in the reactor.

[0030] Some catalytic reactions require external heat to drive the reaction and / or to efficiently produce the desired products. Traditionally, heat is provided to catalytic reactions by either direct-fired or indirect-fired heating systems.

[0031] In direct-fired heating systems, heat is supplied to the reactor. In indirect-fired heating systems, heat is generated and transferred to an intermediate fluid. The intermediate fluid is then transported to the reactor to provide heat. However, combustion heating systems often result in uneven temperature gradients along the reactor. This uneven temperature along the reactor surface typically contributes to premature reactor failure, adversely affecting throughput, catalyst life, and the yield / quality of the desired product. When catalysts disposed within the reactor experience uneven heating, catalyst life also decreases significantly. Furthermore, combustion heaters are subject to typical wear and tear, which ultimately leads to a decrease in the energy efficiency of the combustion heater. Because most combustion heaters generate heat through combustion, such as the combustion of hydrocarbons or other materials that emit greenhouse gases such as CO2, a decrease in the energy efficiency of the combustion heater contributes to an increase in greenhouse gases emitted and / or produced by the combustion heater. In some cases, this decrease in efficiency can result in an efficiency drop outside of the design conditions.

[0032] A solution to this problem has been found in the disclosed method and reaction system. In this disclosure, the combustion heating system is replaced with a direct electrical heating system. Furthermore, the direct electrical heating system uses the reactor as a heating element by supplying electrical energy to the reactor's conductive surfaces. The current supplied to the reactor can be adjusted to control the temperature of the reactor and / or the catalyst within the reactor and maintain an appropriate temperature gradient. Therefore, direct electrical heating of the reactor allows for more precise control of the reactor temperature. This can result in improved yield / quality of the desired product, increased throughput, extended catalyst life, etc.

[0033] Systems with multiple reactors (e.g., reactor tubes 202) can electrically heat each reactor individually by supplying electrical energy to the conductive surfaces of each individual reactor. This allows for a high degree of control over each reactor and significantly reduces temperature differences between individual reactors. More uniform temperature distribution along the reactor walls and uniform reactor temperatures within the reaction system reduces stress on the reactors, extending reactor and catalyst life and further benefiting process operation.

[0034] The ability to finely control reactor temperature gradients in direct electrical heating systems also allows for the division of individual reactor tubes into two or more heating zones, potentially further improving process operation and increasing throughput, yield / quality of desired products, etc.

[0035] The problem of increased greenhouse gas emissions and pollution associated with the degradation of combustion heaters can also be avoided by using an electric heating system. Because the electric heating system heats the reactor by directly supplying electrical energy to the reactor's conductive surfaces, no intermediate fluid is required, and energy can be supplied to the reactor by methods other than the combustion of greenhouse gas-emitting hydrocarbons or other materials. Instead, the present disclosure directs electrical energy to the reactor's conductive surfaces. This electrical energy may be supplied from any renewable or low-emission (i.e., low-carbon) energy source. For example, the electrical energy may be supplied from a renewable energy source selected from the group consisting of solar energy sources, wind energy sources, geothermal energy sources, hydroelectric energy sources, or tidal energy sources. In one embodiment, the electrical energy is supplied from a nuclear energy source.

[0036] Catalyst life is affected by catalyst poisoning and physical destruction of the catalyst. Catalyst destruction is primarily caused by reactor expansion and contraction, both longitudinally and radially. During catalytic reactions, as the reactor and catalyst heat up, the reactor and / or catalyst may expand or contract. For example, in a steam methane reforming process, a 40-foot reactor tube typically expands approximately 250 mm during heating, while the catalyst expands at a much slower rate. This difference in expansion rate results in catalyst settling. When the reactor tube cools, the catalyst may be crushed during the reactor tube contraction.

[0037] Combustion heating of a reactor creates a non-uniform temperature gradient along the reactor. The temperature gradient can be measured along the length of the reactor and / or can be obtained by comparing one side of the reactor to the other. Direct flame impingement or flame-associated hot gas flow can create additional hot spots in the reactor. This non-uniform heating and resulting temperature gradient cause the reactor to experience non-uniform expansion and contraction during reactor heating. This non-uniform expansion and contraction is characterized as oscillatory expansion (i.e., oscillating between expansion and contraction). The physical stresses imposed on the reactor by this oscillatory expansion contribute significantly to reactor and catalyst degradation, ultimately shortening the usable life of the reactor and / or catalyst. Premature reactor and / or catalyst degradation not only adversely affects the throughput, yield, and / or quality of the desired product in a catalytic reaction, but also increases the maintenance and operating costs of the catalytic reaction.

[0038] In contrast, the direct electric heating system of the present disclosure can control the temperature throughout the reactor, ensuring a more uniform temperature gradient both longitudinally and radially. While heating the reactor with an electric heating system can cause expansion and contraction, the expansion and contraction are not oscillatory. For example, the reactor may expand once during uniform heating and contract once as the electrical energy supplied to heat the reactor is uniformly reduced. Therefore, by limiting the expansion and contraction cycles experienced by the reactor, the reactor's useful life can be significantly improved. Similarly, because a direct electric heating system can heat the reactor more uniformly, the catalyst within the reactor is also heated more uniformly. By limiting the temperature fluctuations experienced by the catalyst, the physical integrity and useful life of the catalyst are significantly increased. While temperature fluctuations due to changes in throughput or feed composition may occur, such fluctuations do not significantly contribute to reactor / catalyst degradation compared to conventional combustion-heated reactor systems.

[0039] For example, in one embodiment of the present disclosure, the temperature difference between two points on the surface of one or more reactors (e.g., reactor tubes) is about 50° C. or less, about 40° C. or less, about 30° C. or less, about 20° C. or less, about 10° C. or less, about 5° C. or less, about 4° C. or less, about 3° C. or less, about 2° C. or less, or about 1° C. or less. In another embodiment, the temperature difference between two points on the surface of one or more reactors (e.g., reactor tubes) is about 50° C. to about 0.5° C., about 40° C. to about 0.5° C., about 40° C. to about 1° C., about 30° C. to about 1° C., about 20° C. to about 1° C., about 10° C. to about 1° C., about 5° C. to about 1° C., about 4° C. to about 1° C., about 3° C. to about 1° C., or about 2° C. to about 1° C.

[0040] In embodiments of the present disclosure comprising multiple reactors (e.g., reactor tubes), the temperature difference between the hottest reactor of the multiple reactors and the coolest reactor of the multiple reactors may be about 50° C. or less, about 40° C. or less, about 30° C. or less, about 20° C. or less, about 10° C. or less, about 5° C. or less, about 4° C. or less, about 3° C. or less, about 2° C. or less, or about 1° C. or less. For example, in some embodiments, the temperature difference between the hottest reactor of the multiple reactors and the coolest reactor of the multiple reactors may be about 50° C. to about 0.5° C., about 40° C. to about 0.5° C., about 40° C. to about 1° C., about 30° C. to about 1° C., about 20° C. to about 1° C., about 10° C. to about 1° C., about 5° C. to about 1° C., about 4° C. to about 1° C., about 3° C. to about 1° C., or about 2° C. to about 1° C.

[0041] In addition to improving the reactor and catalyst service life and increasing the throughput, yield, and / or quality of desired products compared to combustion-heated systems, the disclosed methods including direct electrical heating systems also allow for significantly improved control of the reactor system.

[0042] As explained above, combustion heating systems typically involve the combustion of hydrocarbons or the transfer of thermal energy to a reactor via an intermediate fluid (i.e., heat transfer fluid). In a combustion heating system, the amount by which the reactor is heated is controlled based on the desired temperature of the reactor fluid at the reactor outlet. There is a significant delay in adjusting the temperature of the reactor because the combustion rate of the combustion must be adjusted to increase the temperature of the intermediate fluid so that it transfers heat to the reactor and its contents. In this configuration, heat transfer from the intermediate fluid is convective, which is typically slow compared to, for example, radiative heat transfer. Thus, there may be a delay between the control input to the combustion heating system and the actual temperature change of the reactor fluid at the reactor outlet.

[0043] In contrast, the disclosed electric heating system involves directly supplying electrical energy to the conductive surfaces of the reactor. For example, in one embodiment, a reactor system includes a plurality of reactor tubes, each of which contains a catalyst and has at least one conductive surface, and electrical energy is supplied to the at least one conductive surface of each of the plurality of reactor tubes. The disclosed electric heating system controls the heat of the reactor system 100 through energy control (i.e., by adjusting the electrical energy supplied to the at least one conductive surface of each of the plurality of reactor tubes). Thus, the disclosed electric heating system can rapidly change the reaction temperature by adjusting the electrical energy input to each of the reactor tubes. This allows for more precise control of the reactor system, more accurately maintaining the temperature of each individual reactor tube, and reducing the maximum temperature difference between reactor tubes within a reactor. The disclosed electric heating system also reduces the uneven temperature distribution within individual tubes commonly observed in conventional processes, i.e., the creation of hot spots due to flame impingement on the tubes, or other factors that lead to uneven distribution of heat from combustion processes.

[0044] The electrical heating system of the present disclosure also allows for a correlation to be established between electrical energy input and catalytic reaction products. In this manner, the amount of energy input to the reactor system can be controlled to ensure that no more electrical energy is introduced into the system than is necessary for the reaction to reach a desired yield or purity. In some embodiments, it may be desirable to control the electrical energy input so that a slight excess of electrical energy is provided to the reactor system 100.

[0045] The control provided by an electric heating system can offer significant improvements over combustion heating systems. For example, in a reactor system equipped with an indirect combustion heating system, it can take 20 minutes or more to adjust the heater's temperature profile and achieve the desired change in the reactor system. However, a reactor system equipped with an electric heating system can adjust the energy input to the reactor and achieve the desired change in the reactor system in less than one minute. This not only improves the safety of the reactor system compared to systems equipped with combustion heaters, but also allows for a more efficient process.

[0046] The electrical energy supplied to at least one conductive surface of the reactor or reactors may be supplied from multiple electrical energy sources. In some embodiments, at least a portion of the electrical energy is supplied by a renewable energy source or a low-carbon emission source. For example, the energy may be supplied from a nuclear power source. In other embodiments, the electrical energy is supplied exclusively by renewable energy sources. The renewable energy source may be selected from the group consisting of, for example, a solar energy source, a wind energy source, a geothermal energy source, a hydroelectric energy source, or a tidal energy source.

[0047] The reactor used in the reactor system of the present disclosure may be any suitable reactor. For example, the reactor may be a fixed-bed reactor or a fluidized-bed reactor. In some embodiments, the reactor of the direct electric heating system of the present disclosure comprises multiple reactor tubes. The multiple reactor tubes may be, for example, multiple fixed-bed reactor tubes. Although described herein with reference to embodiments comprising multiple reactor tubes, it should be understood that the reactor systems and methods of the present disclosure are equally applicable to systems comprising other types of reactors.

[0048] The reactors are designed or selected so that each reactor has at least one electrically conductive surface for applying electrical energy. In some embodiments, each of the plurality of reactors comprises an electrically conductive material, and at least one surface of the reactor is electrically conductive. For example, in some embodiments, the structural material of the reactor comprises an electrically conductive material, and at least one surface of the reactor is electrically conductive. In other embodiments, the reactor comprises an electrically conductive material affixed to one or more surfaces of the reactor.

[0049] The conductive material may include a conductive metal or alloy. For example, the metal or alloy may be selected from the group consisting of gold, silver, copper, aluminum, nickel, tin, brass, iron, platinum, palladium, molybdenum, tungsten, chromium, niobium, chromium, alloys thereof, and combinations thereof. In some embodiments, the metal or alloy is selected from the group consisting of gold, silver, copper, nickel, tin, chromium, niobium, alloys thereof, and combinations thereof. In yet further embodiments, the metal or alloy is selected from the group consisting of nickel, chromium, niobium, alloys thereof, and combinations thereof. In some embodiments, the metal or alloy is a nickel alloy, and the alloy further includes chromium, iron, molybdenum, and / or copper. In yet further embodiments, the conductive material may include a conductive ceramic.

[0050] In various embodiments, the reactor (eg, reactor tube) may comprise carbon steel or a carbon steel alloy, stainless steel or a stainless steel alloy, nickel or a nickel alloy, or a combination thereof. For example, the reactor (e.g., reactor tube) may be manufactured in accordance with ASTM A192, ASTM A210 Gr A-1, ASTM A209 Gr T1, ASTM A213 Gr T11, ASTM A213 Gr T22, ASTM A213 Gr T21, ASTM A213 Gr T5, ASTM A213 Gr T5b, ASTM A213 Gr T9, ASTM A213 T91, ASTM 213 ASTM TP 304, ASTM A213 TP 304H, ASTM A213 TP 304L, ASTM A213 TP 316, ASTM A213 TP 316H, ASTM A213 TP 316L, ASTM A213 TP 317, ASTM A213 TP 317L ... 321, ASTM A213 TP 321H, ASTM A213 TP 347, ASTM A213 TP 347H, ASTM B407, ASTM A213 TP 310H, or combinations thereof. In some embodiments, the above-mentioned materials may form at least a portion of the conductive metal or alloy of the conductive material / surface.

[0051] In one embodiment, one or more reactors comprise a conductive metal or alloy such that at least one surface of each reactor is conductive. Each reactor tube may comprise, for example, a total of about 25% by weight or more, about 30% by weight or more, about 35% by weight or more, about 40% by weight or more, about 45% by weight or more, about 50% by weight or more, about 55% by weight or more, about 60% by weight or more, about 65% by weight or more, about 70% by weight or more, or about 75% by weight or more of the conductive metal or alloy. In some embodiments, each reactor comprises a total of about 25% to about 75% by weight, about 30% to about 70% by weight, about 35% to about 70% by weight, about 40% to about 70% by weight, about 45% to about 70% by weight, about 50% to about 70% by weight, about 55% to about 65% by weight, or about 60% to about 65% by weight of the conductive metal or alloy.

[0052] In one embodiment, each reactor contains between about 5% and about 40%, between about 10% and about 35%, between about 15% and about 30%, or between about 20% and about 30% chromium by weight.

[0053] In some embodiments, each reactor contains between about 5% and about 50%, between about 10% and about 45%, between about 15% and about 40%, between about 20% and about 40%, between about 25% and about 40%, or between about 30% and about 40% nickel by weight.

[0054] In some embodiments, each reactor contains between about 0.5% and about 5% by weight, between about 0.5% and about 4% by weight, between about 0.5% and about 3% by weight, between about 0.5% and about 2% by weight, or between about 1% and about 2% by weight of niobium.

[0055] In other embodiments, each reactor contains between about 0.5% and about 5% by weight, between about 0.5% and about 4% by weight, between about 0.5% and about 3% by weight, between about 0.5% and about 2% by weight, or between about 1% and about 2% by weight of molybdenum.

[0056] In yet further embodiments, each reactor comprises a nickel alloy, the alloy further comprising chromium, iron, molybdenum, and / or copper, and the reactor comprises between about 0.5% and about 5%, between about 0.5% and about 4%, between about 0.5% and about 3%, between about 0.5% and about 2%, or between about 1% and about 2% by weight of the nickel alloy.

[0057] In one embodiment of the present disclosure, each of the reactors 102 in the reactor system 100 and methods of the present disclosure is insulated and / or isolated to ensure that electrical energy supplied to at least one conductive surface of the reactor does not flow freely to other portions of the reactor system. In an embodiment comprising multiple reactors, each of the multiple reactors is electrically isolated from other conductive components of the reactor system. For example, in some embodiments, each of the multiple reactors may be electrically isolated from each other and from other conductive process equipment present in the process.

[0058] In some embodiments, the reactor 102 may be electrically insulated, for example, by a refractory material. In some embodiments, the reactor 102 may be electrically insulated by a material selected from the group consisting of ceramic, nylon, polystyrene, polyvinylchloride (PVC), silicone, rubber, glass, and combinations thereof.

[0059] In one embodiment, electrical insulators are placed at the physical connection points between one or more reactors. In another embodiment, reactor system 100 includes multiple reactors 102, and electrical insulators are placed so that none of the reactors contact any of the other reactors. In yet a further embodiment, reactor system 100 includes multiple reactors 102, and the multiple reactors are electrically isolated from the rest of the process equipment. Figure 2, described in more detail below, shows a reactor system with 16 reactor tubes arranged such that each reactor tube is electrically isolated and the entire reactor system is surrounded by insulating wall material.

[0060] The material that can be used to electrically insulate and / or isolate each of the reactors in the reactor system may be any suitable insulating / isolating material. For example, the insulating / isolating material may be selected from the group consisting of ceramic, nylon, polystyrene, polyvinyl chloride (PVC), silicone, rubber, glass, and combinations thereof. In some embodiments, the insulating / isolating material may be selected from the group consisting of refractory materials, ceramic, and glass. In some embodiments, the insulating / isolating material may be a ceramic selected from the group consisting of ceramic fiber, ceramic blanket, ceramic substrate, or combinations thereof. In other embodiments, the insulating / isolating material may be selected from the group consisting of concrete (e.g., castable insulating concrete), fiber brick, mineral wool, or combinations thereof.

[0061] It will be understood that the particular catalyst used in the reactor systems and methods of the present disclosure will depend on the catalytic reaction being carried out. Exemplary embodiments of steam methane reforming are described herein. However, the scope and application of the reactor systems of the present disclosure are not limited to steam methane reforming processes.

[0062] In methods involving a steam methane reforming process, the catalyst may be a catalyst comprising nickel. The catalyst may be prepared by supporting nickel on a support. For example, the nickel may be supported on an oxide substrate selected from the group consisting of Al2O3, CeO2, La2O3, MgO, SiO2, ZrO2, calcium aluminate, and combinations thereof. In one embodiment, the nickel is supported on an alumina ceramic substrate (e.g., Al2O3).

[0063] In another embodiment, in a methane reforming process, the catalyst may include Ru and / or Rh on a support. For example, Ru and / or Rh may be supported on an oxide substrate selected from the group consisting of Al2O3, CeO2, La2O3, MgO, SiO2, ZrO2, calcium aluminate, and combinations thereof.

[0064] In one embodiment, the catalyst comprises at least about 10 wt%, at least about 15 wt%, at least about 20 wt%, at least about 25 wt%, at least about 30 wt%, at least about 35 wt%, at least about 40 wt%, or at least about 45 wt% nickel, based on the total weight of the catalyst. In another embodiment, the catalyst comprises from about 10 wt% to about 50 wt%, from about 15 wt% to about 50 wt%, from about 15 wt% to about 40 wt%, from about 20 wt% to about 40 wt%, from about 20 wt% to about 35 wt%, or from about 20 wt% to about 30 wt% nickel, based on the total weight of the catalyst. In another embodiment, the catalyst comprises from about 10 wt% to about 50 wt%, from about 15 wt% to about 50 wt%, from about 20 wt% to about 50 wt%, from about 25 wt% to about 50 wt%, or from about 30 wt% to about 50 wt% nickel, based on the total weight of the catalyst.

[0065] The catalyst may be in any commercially suitable shape. For example, the catalyst may be in the shape of a ring, sphere, tablet, pellet, or particle. In one embodiment, the catalyst is in the form of a ring. In other embodiments, the catalyst may be in a complex shape to increase porosity and geometric surface area (e.g., MAGCAT TEXTURED catalyst, available from Magma Catalyst).

[0066] In some embodiments, the catalyst has an average diameter of about 2 inches or less, about 1.5 inches or less, about 1.25 inches or less, about 1 inch or less, about 0.75 inches or less, about 0.5 inches or less, or about 0.25 inches or less. In one embodiment, the catalyst has an average diameter of about 2 inches to about 0.25 inches, about 1.75 inches to about 0.25 inches, about 1.5 inches to about 0.25 inches, about 1.5 inches to about 0.5 inches, about 1.25 inches to about 0.5 inches, or about 1 inch to about 0.5 inches.

[0067] 2 is a top view of one embodiment of a reactor 102 comprising multiple reactor tubes 202 having catalyst 302 disposed therein. The circles represent individual reactor tubes 202 within the reactor 102, with each reactor tube 202 being electrically isolated from other electrically conductive elements within the reactor 102. Furthermore, each individual reactor tube 202 is electrically isolated from other reactor tubes 202 within the reactor 102.

[0068] FIG. 3 is a side view of the reactor tube 202 described above. Materials that contact the catalyst 302 are introduced through the top of the reactor tube 202, contact the catalyst 302 present within the reactor tube 202, and exit the bottom of the reactor tube 202. The catalyst 302 can be maintained within the reactor tube 202 through the use of one or more catalyst support plates and / or screens 310. FIG. 3 illustrates a reactor tube 202 utilizing a lower catalyst support plate 310. The one or more catalyst support plates and / or screens 310 can be selected to allow materials (e.g., liquids or gases) that contact the catalyst 302 to flow through the respective plates and / or screens, but prevent catalyst particles from exiting the reactor tube 202. However, it will be appreciated that in practice, it may be impossible to prevent all catalyst particles from exiting the reactor tube 202. Therefore, in the design of the reactor tubes 202, the commercial aspects of the target reaction and the properties of the catalyst 302 should be taken into consideration, and the support plates and / or screens 310 should be selected to minimize catalyst particle loss. FIG. 3 shows electrical connectors 304 connected to the left side of the reactor tubes 202. As previously mentioned, these electrical connectors 304 are positioned to allow electrical energy to be delivered from the electrical energy source 108 to the conductive surfaces present on the reactor tubes 202. Finally, electrical insulators 308 are shown at the top and bottom of the reactor tubes. These electrical insulators 308 are positioned so that each reactor tube 202 is electrically isolated from the other reactor tubes 202 and from other conductive elements within the reactor system 100.

[0069] FIG. 4 shows a side view of another embodiment of the reactor tube 202 as described above. The reactor tube of FIG. 4 is similar to the reactor tube of FIG. 3, except that FIG. 4 utilizes a ground 306 instead of an electrical insulator. An electrical ground may be desirable as a way to electrically isolate individual reactor tubes without requiring physical insulation. In certain configurations, the exterior of the reactor tube may reach temperatures that exceed the operating range of typical insulators. Electrical isolation by the ground 306 allows for the isolation of the reactor tube without the use of insulators specifically designed for extreme temperatures. This may result in significant cost savings.

[0070] FIG. 5 shows a side view of yet another embodiment of the reactor tube 202 as described above. The reactor tube of FIG. 5 is similar to the reactor tube of FIG. 3, except that FIG. 5 utilizes a single ground 306 at the top of the reactor tube instead of an electrical insulator. Replacing a physical electrical insulator with a ground can have the advantages described above. In a reactor tube such as FIG. 5, where material flows from bottom to top, the internal temperature of the reactor tube typically increases as the material flows toward the top. This is because the material inside the tube is heated as it passes through the reactor tube. By replacing only the top insulator with an electrical ground, the hotter end of the reactor tube is electrically isolated without the need for a physical insulator specifically designed for extreme temperatures.

[0071] Figure 6 provides a detailed view of one embodiment of an individual reactor tube 202. The drawing is oriented from the top of the reactor tube. The large circle represents the reactor tube wall. The reactor tube wall comprises at least one electrically conductive surface to which electrical energy can be applied to heat the reactor tube and its contents.

[0072] The particles within the large circle represent particles of catalyst 302 disposed within the reactor tube 202. While the catalyst particles are shown as uniformly dispersed and occupying the majority of the area within the reactor tube 202, one skilled in the art will understand that the amount and orientation of the catalyst particles within the reactor tube 202 will depend on the intended application. For example, in some reactions, the process may require a high flow rate of material. In this situation, the catalyst 302 should be packed into the reactor tube 202 at a sufficiently low density so that the system 100 can achieve such a high flow rate and maintain the overall reaction rate desired for the process. In other reactions, an increased time for the material to be in physical contact with the catalyst may be required. In that situation, it may be desirable to pack the catalyst 302 into the reactor tube 202 at a higher density to increase the residence time within the reactor tube 202, thereby increasing the time the material is in physical contact with the catalyst. It will be understood that these design choices regarding catalyst packing within the reactor tube are made based on the reaction conditions, catalyst composition, physical properties of the catalyst particles (e.g., particle size), and / or the desired end product. That is, the catalyst may be packed in the reaction tube in a uniform orientation or in a random orientation.

[0073] Two electrical connectors 304 connected to the reactor tube walls are shown in FIG. 6. The electrical connectors 304 contact the reactor tube walls, which include at least one electrically conductive surface. In this manner, electrical energy can be supplied from the electrical energy source 108 to the electrically conductive surface of each individual reactor tube 202. When electrical energy is applied to the electrically conductive surface, the reactor tubes 202 heat the catalyst and reactor fluid disposed therein. The temperature of the reactor tubes 202 and catalyst 302 can be precisely controlled by adjusting the amount of electrical energy applied to the electrical connectors 304 of each of the reactor tubes 202.

[0074] FIG. 7 shows a side view of one embodiment of a reactor 102 comprising multiple reactor tubes 202. Each of the reactor tubes 202 is arranged as described in FIGS. 3 and 4. In FIG. 7, an inlet stream of material to be contacted with a catalyst 302 enters the top of each reactor tube 202 through an inlet tube 104 (i.e., an inlet tube arrangement or inlet tube header 104), contacts the catalyst 302, and is collected at the bottom of each reactor tube 202 through an outlet tube 106 (i.e., an outlet tube arrangement or outlet tube header 106). Also shown in FIG. 7 are a heater shell 304 and electrical insulators 308. The shell 304 is insulated by electrical insulators 308 such that each of the reactor tubes 202 is electrically isolated from the other reactor tubes 202 and from other electrically conductive elements within the reactor system 100.

[0075] In other embodiments, in addition to or instead of the electrical insulators 308, the system may include an insulating gasket between one or more reactor tubes and an associated inlet piping arrangement (i.e., inlet piping header) 104. In another embodiment, the system includes an insulating gasket between one or more reactor tubes and an associated outlet piping arrangement (i.e., outlet piping header) 106. In yet a further embodiment, the system includes a first insulating gasket between one or more reactor tubes and an associated inlet piping arrangement (i.e., inlet piping header) 104 and a second insulating gasket between one or more reactor tubes and an associated outlet piping arrangement (i.e., outlet piping header) 106. In various embodiments, the insulating gasket may comprise a material selected from the group consisting of ceramic, nylon, polystyrene, polyvinyl chloride (PVC), silicone, rubber, glass, and combinations thereof. In some embodiments, the insulating gasket may comprise a ceramic selected from the group consisting of ceramic fiber, ceramic blanket, ceramic substrate, or combinations thereof. In other embodiments, the insulating gasket may comprise a material selected from the group consisting of concrete (eg, castable insulating concrete), fiber brick, mineral wool, or combinations thereof.

[0076] In one embodiment of the present disclosure, a method for heating a reactor system with a PID controller is described, the method including: implementing a cascade control scheme with a proportional-integral-derivative (PID) controller; regulating an output of the PID controller to an operational setpoint according to the cascade control scheme; and a power controller connected to a power source adjusts a current level of the power source in response to the operational setpoint to heat each of a plurality of reactor tubes to a desired reactor outlet temperature.

[0077] Referring to FIG. 8, an example of a cascade control scheme implemented by the controller 110 is shown. In this embodiment, the controller 110 includes a proportional-integral-derivative (PID) controller 602 for regulating the current to an operating setpoint, and a power controller 604 for adjusting the current level of the power supply 108 in response to the operating setpoint and heating the reactor 102 to achieve the desired reactor outlet temperature. PID temperature control loops tend to be slow to respond (e.g., several minutes of lag) due to several factors, including thermal inertia, heat transfer to the reactor, and the time response of the temperature sensor itself. Conventional embodiments require adjustment of PID settings to account for combustion instabilities, such as flame instability, fluctuations in gas heating value and flow rate, and fluctuations in exhaust gas flow rate within the chamber. By introducing an accurate and direct power control loop (control in kW, volts, or amperes) within the temperature control loop, the PID controller 602 of the controller 110 significantly improves the stability, accuracy, and speed of the temperature control loop. In particular, heat transfer to the reactor is much simpler because the heat transfer function is very constant (no convective and radiative transfer modes are required). Furthermore, aspects of the present disclosure provide the opportunity to model the heat transfer function and implement a temperature control loop based on a predictive model, making the process control loop much faster than typical PID control. The time response of the direct power control loop of the power controller 604 is extremely accurate and fast. The PID control loop of the PID controller 602 is improved by eliminating combustion instabilities in the combustion chamber, fluctuations in gas heating value, and instabilities in the exhaust flow rate.

[0078] Although PID control loops and / or PID controllers are described herein, it will be understood that other controllers and control strategies, including but not limited to fuzzy logic control (FLC), programmable logic controller (PLC), linear quadratic regulator (LQR) control, model predictive control (MPC), adaptive control, sliding mode control, and multivariable predictive control, can also be utilized to adjust the current level of the power supply 108 to heat the reactor 102 and achieve the desired reactor outlet temperature.

[0079] Further embodiments of the present disclosure relate to galvanic isolation of reactors (e.g., reactor tubes) in reactor heater systems. Without galvanic isolation, reactor tubes typically need to be individually electrically insulated or isolated using insulating materials (e.g., insulating gaskets or insulating materials). With galvanic isolation, insulating gaskets or insulating materials are not required, and reactor tubes can be directly connected (e.g., welded) to inlet and outlet headers (i.e., inlet and outlet pipe headers). This has the added benefits of improving system safety with respect to potential fluid leaks, reducing maintenance costs, and reducing downtime and capital costs. In these embodiments, the systems and methods of the present disclosure also reduce the risk of electrical hazards to personnel. In some embodiments, the present disclosure relates to galvanic isolation of systems utilizing alternating current.

[0080] While this specification discusses galvanic isolation, or galvanic isolation of a reactor tube or reactor heating system, it is understood that "isolation" is intended to refer to commercially viable isolation. While it is the goal of this disclosure to strive for perfect galvanic isolation of the reactor tube or reactor heating system (i.e., as close to 0 V as possible to prevent current flow at the inlets and outlets of the reactor tube or reactor heating system), unavoidable impedance differences or voltage potential differences may cause a negligible amount of current to leak from the reactor tube or system. As long as the amount of current leaking from an insulated tube or reactor heating system is within commercially feasible and / or safe operating limits, the tube or system is understood to be galvanically isolated.

[0081] In one embodiment, a method for heating a reactor system is provided. The reactor system includes a plurality of reactor tubes, each of the plurality of reactor tubes having a catalyst disposed therein and at least one electrically conductive surface. A fluid enters each of the plurality of reactor tubes through an associated inlet header and exits each of the plurality of reactor tubes through an associated outlet header. The method includes galvanically isolating the plurality of reactor tubes so that each of the plurality of reactor tubes can be directly connected to the inlet header and the outlet header; supplying electrical energy to at least one electrically conductive surface of each of the plurality of reactor tubes; and individually adjusting a current level of the electrical energy supplied to the one electrically conductive surface of each of the plurality of reactor tubes to individually control a temperature of each of the reactor tubes and the catalyst disposed therein.

[0082] In some embodiments of this method, each of the plurality of reactor tubes is not electrically isolated.

[0083] The multiple reactor tubes may be galvanically isolated, for example, by using multiple power controllers that are mirrored to each other to achieve commercially acceptable voltage and / or current levels (i.e., negligible amounts of voltage and current) at the inlet and outlet tube headers.

[0084] In some embodiments, in addition to galvanic isolation, one or more grounding points may be provided to the system, such as a grounding point at the inlet of each of the one or more reactor tubes, a grounding point at the outlet of each of the one or more reactor tubes, or a grounding point at the inlet of each of the one or more reactor tubes and a grounding point at the outlet of each of the one or more reactor tubes.

[0085] In some embodiments, electrical energy is supplied to each of the multiple reactor tubes from multiple three-phase power sources. In other embodiments, electrical energy is supplied to each of the multiple reactor tubes from multiple three-phase power sources to multiple transformers. In either configuration, the resulting three-phase electrical energy is routed to each reactor tube, creating one or more individually controllable heating zones within the reactor tube. For example, two or more, three or more, four or more, five or more, six or more, seven or more, eight or more, nine or more, or ten or more heating zones may be created.

[0086] In one embodiment, for each of the plurality of reactor tubes, a first phase from each of the plurality of transformers may be directed to a first location on the conductive surface of the reactor tube, a second phase from each of the plurality of transformers may be directed to a second location on the conductive surface of the reactor tube, and a third phase from each of the plurality of transformers may be directed to a third location on the conductive surface of the reactor tube. In this embodiment, two or more individually controllable heating zones may be formed within the reactor tube.

[0087] In some configurations, insulating gaskets may be required at the inlet and outlet of each reactor tube (e.g., as shown in FIG. 7 ) and / or insulation may be required between the outer shell and the reactor tube (e.g., as shown in FIG. 13 ). Insulating gaskets are typically exposed to high temperatures and pressures, and insulators may also be exposed to high temperatures. However, in some embodiments of the present disclosure, direct electrical heating of the reactor tubes is configured to eliminate the need for insulating gaskets at the inlet and outlet of each reactor tube and / or insulation between the outer shell and the reactor tube. For example, galvanically isolating individual tubes can eliminate the need for insulating gaskets or insulators (e.g., as described in more detail in FIGS. 10-12B ). In another example, space between the outer shell and the reactor tubes can be used to reduce the risk of electrical current flow between the direct electrical heating process and the shell of the reactor heating system and other components of the reactor system (e.g., as shown in more detail in FIG. 9 ). Eliminating these insulating gaskets and / or insulation between the outer shell and the reactor tubes can eliminate potential points of failure in the system and reduce material and maintenance costs.

[0088] 9 illustrates one embodiment of the disclosed reactor heating system and method including multiple reactor tubes as a cross-sectional view of the reactor system. Direct electrical heating of the reactor tubes is described in more detail below with reference to FIG. 10.

[0089] In Figure 9, an inlet tube 901 is shown at the top with arrows indicating the direction of flow. The material within this reactor tube is the material (e.g., fluid) intended to be heated within the reactor tube. At a 90° angle from the inlet tube, four reactor tubes 902, 903, 904, and 905 are shown. Material flows in parallel through each of these reactor tubes and is collected in an outlet tube 906, shown at the bottom. In various embodiments, the inlet tube 901 is an inlet tube header or inlet tube system, and the outlet tube 906 is an outlet tube header or outlet tube system. As will be described in more detail with respect to Figure 10, in some embodiments, the reactor tubes are galvanically isolated from the inlet tube 901 and the outlet tube 906.

[0090] 9 is an enlarged inset showing the connections between the reactor system's outer shell 907 and each reactor tube. The metal outer shell 907 of the reactor heater system, shown in bold, is not in direct contact with the reactor tube walls. Instead, the shell is connected to refractory material on both sides of the reactor tube, leaving a space between the outer shell and the reactor tube.

[0091] This configuration offers many advantages. Other configurations may require insulating gaskets at the inlet and outlet of each reactor tube and / or require insulation between the outer shell and the reactor tube. As described in more detail herein, in some embodiments, direct electrical heating of the reactor tubes is arranged to eliminate the need for insulating gaskets at the inlet and outlet of each reactor tube. To reduce the risk of electrical current flow between the direct electrical heating process and the shell of the reactor heating system, the space between the outer shell and the reactor tube can be used instead of insulation. Eliminating these insulating gaskets and / or insulation can eliminate the possibility of failure in the system and reduce material and maintenance costs.

[0092] In some embodiments, the refractory material may be selected from the group consisting of ceramic, nylon, polystyrene, polyvinyl chloride (PVC), silicone, rubber, glass, and combinations thereof. In some embodiments, the refractory material may be a ceramic selected from the group consisting of ceramic fiber, ceramic blanket, ceramic substrate, or combinations thereof. In other embodiments, the refractory material may be selected from the group consisting of concrete (e.g., castable insulating concrete), fiber brick, mineral wool, or combinations thereof.

[0093] In some embodiments, the outer shell of the reactor heating system may comprise a metal. For example, the outer shell may comprise low carbon steel. In various embodiments, the outer shell has a thickness of about 1 / 8 inch, about 1 / 6 inch, about 1 / 4 inch, about 1 / 2 inch, or about 1 inch. In other embodiments, the outer shell has a thickness of about 1 / 8 inch to about 5 inches, about 1 / 8 inch to about 4 inches, about 1 / 8 inch to about 3 inches, about 1 / 8 inch to about 2 inches, about 1 / 6 inch to about 2 inches, about 1 / 6 inch to about 1 inch, or about 1 / 6 inch to about 1 / 2 inch.

[0094] In embodiments in which a space exists between the outer shell of the reactor system and the reactor tube, the space may be about 0.1 mm or more, about 0.5 mm or more, about 1 mm or more, about 2 mm or more, about 3 mm or more, about 4 mm or more, about 5 mm or more, about 6 mm or more, about 7 mm or more, about 8 mm or more, about 9 mm or more, about 10 mm or more, about 15 mm or more, about 20 mm or more, about 25 mm or more, about 30 mm or more, about 35 mm or more, about 40 mm or more, about 45 mm or more, or about 50 mm or more. For example, the space may be about 1 mm to about 100 mm, about 2 mm to about 90 mm, about 3 mm to about 80 mm, about 4 mm to about 70 mm, about 5 mm to about 60 mm, about 6 mm to about 50 mm, about 7 mm to about 50 mm, about 8 mm to about 50 mm, about 9 mm to about 50 mm, or about 10 mm to about 50 mm.

[0095] As described in more detail below, a multiphase current heating system can use multiple power controllers that mirror each other to transition from 0 volts at the inlet to 0 volts at the outlet. For example, in one embodiment, multiple reactor tubes are galvanically isolated using multiple power controllers that mirror each other to transition from 0 volts at the inlet header to 0 volts at the outlet header. This results in a system that is referred to as "zero net voltage" and galvanically isolates the multiple reactor tubes.

[0096] In another embodiment, the multi-phase current heating system includes multiple power controllers that mirror each other to form multiple heating zones within a single reactor tube and galvanically isolate the single reactor tube.

[0097] In some embodiments, the reactor heating system may include one or more ground points in addition to galvanic isolation, for example, as shown in FIG.

[0098] 9 shows a ground point (e.g., earth) 908 connected to the inlet and outlet tubes. In some embodiments, the ground points may be connected or routed to the same ground potential. In some embodiments, the ground point 908 may be located away from the direct inlet / outlet of the first reactor tube, but within a reasonable distance to ensure that the inlet and outlet tubes are properly grounded and at the same potential. In one embodiment, the ground point 908 is located as close as possible to the inlet / outlet of the reactor tube.

[0099] By placing grounding points 908 at the inlet and outlet of the reactor tubes and spacing the outer shell of the reactor system from the walls of the reactor tubes, it is believed that the system can be safely operated without installing electrical insulation (e.g., gaskets) on each of the reactor tubes. This is especially important in high temperature reactions where common gasket materials may not withstand the conditions or may be prohibitively expensive.

[0100] Although one ground point is shown at the inlet of the first reactor tube and one ground point is shown at the outlet of the first reactor tube, in some embodiments, the reactor system may include multiple ground points. For example, there may be one ground point at each reactor tube inlet of one or more reactor tubes, one ground point at each reactor tube outlet of one or more reactor tubes, or a ground point at each reactor tube inlet of one or more reactor tubes and a ground point at each reactor tube outlet of one or more reactor tubes. In some embodiments, the multiple ground points may be connected or routed to the same ground potential.

[0101] FIG. 10 illustrates heating of a reactor system including direct electrical heating. This diagram shows a cross-section of the reactor system. While one reactor tube is shown, the system may include multiple reactor tubes. An inlet tube 1001 is shown at the top, with arrows indicating the direction of flow. The material within the reactor tube is the material (e.g., fluid) intended to be heated within the reactor tube. Reactor tube 1002 is shown at a 90° angle from the inlet tube. Material flows through the reactor tube and is collected in outlet tube 1003, shown at the bottom. In various embodiments, inlet tube 1001 is an inlet tube header or inlet tube arrangement, and outlet tube 1003 is an outlet tube header or outlet tube arrangement. As described in further detail herein, in some embodiments, the reactor tubes are galvanically isolated from inlet tube 1001 and outlet tube 1003.

[0102] Ground points 1004 are present on the inlet and outlet pipes and are utilized in the same manner as described in Figure 9. In some embodiments, the ground points may be bonded or connected to the same ground.

[0103] In Figure 10, two power sources are used to create two "zones" within the reactor tube. A first AC power source 1005 is connected to a transformer 1006, and power is delivered to connections 1007 and 1008 on the reactor tube.

[0104] A second AC power source 1009 is connected to a transformer 1010 and power is delivered to nodes 1008 and 1011 .

[0105] The power supplied from transformer 1006 to nodes 1007 and 1008, and from transformer 1010 to nodes 1008 and 1011 is 0 V at node 1007, +50 V at node 1008, and 0 V at node 1011. This results in the same potential difference between the top and bottom of the reactor tube, galvanically isolating the reactor tube.

[0106] Although the reactor system may be described herein as having the same potential between the top and bottom of the reactor tube, it will be understood that in some embodiments, the voltage between the inlet and outlet of the reactor tube may not be exactly 0. For example, in one embodiment, the inlet or outlet of the reactor tube may have a voltage of about 5 V or less, about 4 V or less, about 3 V or less, about 2 V or less, about 1 V or less, about 0.5 V or less, or about 0.25 V or less. In some embodiments, the inlet or outlet of the reactor tube may have a voltage of about 0.2 V to about 1 V. In other embodiments, the reactor tube inlets or outlets (i.e., inlet and outlet pipe headers) may have a voltage of about 0.1 V to about 20 V, about 0.1 V to about 15 V, about 0.1 V to about 10 V, about 0.1 V to about 9 V, about 0.1 V to about 8 V, about 0.1 V to about 7 V, about 0.1 V to about 6 V, about 0.1 V to about 5 V, about 0.1 V to about 4 V, about 0.1 V to about 3 V, about 0.1 V to about 2 V, about 0.1 V to about 1 V, or about 0.1 V to about 0.5 V. The grounding points of the inlet and outlet pipes (i.e., inlet and outlet pipe headers) ground out any residual voltages, so that operator-facing system components (e.g., inlet / outlet pipes, reactor shell, etc.) do not pose a hazard to the operator.

[0107] Similarly, systems such as that illustrated in FIG. 10 may contain some current "leakage" resulting from the direct electrical heating of the reactor tubes. In some embodiments, about 1% to about 5% of the total current supplied to the system may be present at the inlets or outlets of the reactor tubes. In other embodiments, about 10% or less, about 9% or less, about 8% or less, about 7% or less, about 6% or less, about 5% or less, about 4% or less, about 3% or less, about 2% or less, about 1% or less, about 0.5% or less, about 0.25% or less, or about 0.1% or less of the total current supplied to the system may be present at the inlets or outlets of the reactor tubes. The inlet and outlet tube grounding points provide a ground for such residual currents so that operator-facing system components (e.g., inlet / outlet tube headers, reactor shell, etc.) do not pose a hazard to the operator.

[0108] The connection points allow electrical energy to be supplied directly to the reactor tube (e.g., to a conductive surface of the reactor tube) or to a conductive surface connected to the reactor tube. The direct electrical heating, materials of construction, and electrical configuration of the reactor tube are described in further detail above.

[0109] In Figure 10, connection points 1007, 1008, and 1011 may be directly connected to the reactor tube. As described elsewhere herein, one aspect of the present disclosure provides electrical energy to a conductive surface present on the reactor tube (e.g., the wall of the reactor tube or an external conductor electrically connected to the reactor tube). The current provided to the reactor tube can be adjusted to control the temperature of the reactor tube and / or the catalyst within the reactor tube and maintain an appropriate temperature gradient. Thus, direct electrical heating of the reactor tube allows for finer and more precise control of the reactor tube temperature. This can result in improved yield / quality of desired products, increased throughput, extended catalyst life, etc.

[0110] Figure 11 shows an electrical diagram superimposed on a reactor heating system including direct electrical heating. This diagram shows a cross-section of the reactor system. While Figure 11 shows one reactor tube, the system may include multiple reactor tubes. For example, multiple reactor tubes may be arranged in parallel between inlet tube 1101 and outlet tube 1103.

[0111] An inlet tube 1101 is shown at the top with an arrow indicating the direction of flow. The material in this reactor tube is the material (e.g., fluid) intended to be heated within the reactor tube. At a 90° angle from the inlet tube is reactor tube 1102. The material flows through the reactor tube and is collected in outlet tube 1103, shown at the bottom. In various embodiments, inlet tube 1101 is an inlet tube header or system, and outlet tube 1103 is an outlet tube header or system.

[0112] As shown in Figure 11, there is a ground point 1109. In some embodiments, the ground points may be coupled or connected to the same ground.

[0113] In Figure 11, three "zones" are created within the reactor tube using a single power supply and ground 1109. An AC power source 1104 is connected to the primary side of a transformer 1105, and its three-phase power is delivered to reactor tube connections 1106, 1107, and 1108. In this embodiment, the power delivered by transformer 1105 is polyphase. As shown, connections 1106, 1107, and 1108 each carry a different phase, A, B, and C, respectively.

[0114] As described elsewhere herein, the reactor tube comprises an electrically conductive surface, and when electrical energy is applied to the electrically conductive surface, the reactor tube generates an electric current (I 2The reactor tubes are heated by a resistor (R). Heating the reactor tubes then heats the catalyst or reactor fluid disposed therein. The impedance of the tubes acts as a resistive load in the circuit, as shown by the resistors placed over the tubes in FIG. 11 . Power supplied from transformer 1105 to nodes 1106, 1107, and 1108 causes the reactor tubes' electrical impedance to be equal i) between top ground node 1109 and node 1106, ii) between node 1106 and node 1107, and iii) between node 1107 and node 1108. That is, zones 1, 2, and 3 have equal (or approximately equal) electrical impedances. This equal (or approximately equal) electrical impedance is intended to result in equal (or approximately equal) energy being supplied to each zone, and therefore equal (or approximately equal) heating in each zone.

[0115] The presence of ground point 1109 allows the top and bottom of the reactor tube to have the same potential and provide galvanic isolation.

[0116] The inset "Electrical Configuration" schematic on the left shows a corner-grounded transformer configuration, as in FIG. 11, in which the ground bonds at the top and bottom of the reactor tubes are at the same potential. The inset schematic in FIG. 11 further shows how the corner-grounded transformer secondary is connected to the reactor tubes to provide power to three zones for heating. As explained above, the reactor tubes in FIG. 11 are electrically divided into thirds, creating three zones (e.g., Zone 1, Zone 2, and Zone 3). These zones have approximately equal impedances, as indicated by the resistors stacked on top of the tubes. The transformer secondary is configured as a corner-grounded delta, so one of the phases (i.e., Phase C in this case) is grounded. The "Electrical Configuration" schematic shows the electrical configuration of how the reactor tubes are connected to the transformer secondary by stacking the reactor tubes in a delta configuration.

[0117] While Figure 11 depicts a single reactor tube, a single power source, and a single transformer, it will be understood that multiple alternative configurations are within the scope of the present disclosure. For example, the reactor heating system may include multiple reactor tubes with similar connections and galvanic isolation. In another example, each reactor tube may include multiple power sources or multiple transformers. Additionally, multiple connection points may be used to direct electrical energy to the conductive surfaces of the reactor tubes to form more than three zones. In various embodiments, multiple transformers may be added in parallel or sequentially to meet the operational requirements of the reactor tube(s).

[0118] 12A shows one configuration for direct electrical heating and galvanic isolation of the reactor tubes. The reactor tubes use a split-phase transformer and a three-wire configuration (described in more detail below). While one reactor tube is shown, it will be understood that the system may include multiple reactor tubes. For example, multiple reactor tubes may be arranged in parallel between inlet tube 1201 and outlet tube 1203.

[0119] As shown, power is conducted from a power source 1205 to a split-phase single-phase transformer 1207 and then to the reactor tube 1202. The split-phase single-phase transformer uses three conductors to connect to the single-phase circuit. These are shown in FIG. 12A as Line 1, Line 2, and Neutral / Ground. Line 1 may be connected, for example, to the top of the single-phase transformer winding. Line 2 may be connected, for example, to the bottom of the single-phase transformer winding. Neutral / Ground may be connected, for example, to the center of the single-phase transformer winding.

[0120] The reactor tube is divided into four zones: Zone 1, Zone 2, Zone 3, and Zone 4. Each of the four zones of the reactor tube is divided so that each has approximately equal impedance. This ensures a balanced circuit load. As described elsewhere herein, the reactor tube has conductive surfaces, and when electrical energy is applied to the conductive surfaces, the reactor tube heats. The reactor tube impedance acts as a resistive load on the circuit, as represented by the resistors placed over the reactor tube. The inlet, outlet, and midpoint of each reactor tube are connected directly or indirectly to the neutral / ground connection of a split-phase transformer.

[0121] In Figure 12A, Line 1 and Line 2 are connected at approximately 1 / 4 and 3 / 4 of the reactor tube length, respectively. The connection point of Line 1 and Line 2 is also the "electrical midpoint" between the upper and lower halves of the reactor tube impedance. That is, Line 1 is connected to the midpoint between the upper ground point 1208 and the neutral / ground ground point, and Line 2 is connected to the midpoint between the neutral / ground and the lower ground point 1208. In this manner, the reactor shell, inlet, outlet, and any other external connections (except for Line 1 and Line 2) can be grounded, improving the operational safety of the design.

[0122] In some other configurations, the neutral / ground connection and ground may be eliminated. In this configuration, the space between the connection points of Line 1 and Line 2 has twice the impedance (and twice the voltage) compared to Zone 2 or Zone 3.

[0123] In some embodiments, multiple three-phase transformers can be connected in parallel to increase the total current passing through the reactor tubes. By appropriately controlling the output of each phase and / or each transformer, the amount of current can be increased or decreased to optimize heating of the reactor tubes.

[0124] Figure 12B shows one configuration for direct electric heating and galvanic isolation of multiple reactor tubes, similar to Figure 12A. In Figure 12B, a single power source and three-phase transformer are used to provide three-phase power. Each phase is routed to a separate reactor tube or to multiple reactor tubes operating in parallel.

[0125] Power is supplied from an AC power source 1205 to a first transformer 1207. The three-phase power from transformer 1207 is then supplied in separate phases to reactor tubes 1202, 1204, and 1206. Each phase is first fed to a split-phase single-phase transformer, which then supplies power to the reactor tubes.

[0126] For example, phase A from first transformer 1207 is directed to split-phase single-phase transformer 1210, after which power is supplied to reactor tube 1202 via line 1 and line 2. Phase B from first transformer 1207 is directed to split-phase single-phase transformer 1211, after which power is supplied to reactor tube 1204 via line 1 and line 2. Phase C from first transformer 1207 is directed to split-phase single-phase transformer 1212, after which power is supplied to reactor tube 1206 via line 1 and line 2.

[0127] FIG. 12B otherwise operates similarly to FIG. 12A.

[0128] FIG. 13 illustrates one embodiment of a reactor heating system of the present disclosure that includes insulation. In contrast to the reactor system of FIG. 9, FIG. 13 utilizes an insulator 1306, whose outer shell contacts the reactor tubes 1302, 1303, 1304, and 1305. As shown in the enlarged view portion of FIG. 13, the insulator forms a physical barrier between the metal outer shell of the reactor system and the reactor tubes. The insulator functions to electrically insulate the reactor tubes from the shell. In some embodiments, the insulator 1306 can also function to ensure that the reactor tubes are insulated from each other. In this configuration, electrical energy supplied to the reactor tubes for direct electrical heating is contained within the system by the insulator. In some other embodiments, insulating gaskets can be provided at the inlet and outlet to each reactor tube to insulate the reactor tubes from other components of the system. The use of the insulator 1306 or insulating gaskets may eliminate the need for grounding the inlet tube 1301 and outlet tube 1307, as shown in FIG. 9. In various embodiments, the inlet pipe 1301 is an inlet pipe header or arrangement, and the outlet pipe 1307 is an outlet pipe header or arrangement.

[0129] FIG. 14 is a diagram illustrating a galvanic isolation system with multiple heating zones.

[0130] An inlet tube 1401 is shown at the top, with arrows indicating the direction of flow. The material in this reactor tube is the material (e.g., fluid) intended to be heated within the reactor tube. At a 90° angle from the inlet, reactor tube 1402 is shown with multiple heating zones. While a single reactor tube is shown, the configuration of FIG. 14 is equally applicable to reactor systems with multiple reactor tubes. Material flows through the reactor tube and is collected in outlet tube 1403, shown at the bottom. In various embodiments, inlet tube 1401 is an inlet tube header or inlet tube arrangement, and outlet tube 1403 is an outlet tube header or outlet tube arrangement. As described in more detail below, in some embodiments, the reactor tubes are galvanically isolated from inlet tube 1401 and outlet tube 1403.

[0131] Three zones are formed within reactor tube 1202 by multiple AC power sources (1404, 1405, and 1406) and transformers (1407, 1408, and 1409) operating in parallel. In some embodiments, the voltage provided by each AC power source is the same. In other embodiments, the voltage provided by each AC power source is different.

[0132] A first AC power source 1404 is connected to a first transformer 1407, and power is conducted to nodes 1410 and 1411 on the reactor tube. Zone 1 of the reactor tube is formed between node 1410 and node 1411.

[0133] A second AC power source 1405 is connected to a second transformer 1408, and power is directed to nodes 1411 and 1412 on the reactor tube. Zone 2 of the reactor tube is formed between nodes 1411 and 1412.

[0134] A third AC power source 1406 is connected to a third transformer 1409, and power is directed to nodes 1412 and 1413 on the reactor tube. Zone 3 of the reactor tube is formed between nodes 1412 and 1413.

[0135] Grounding points 1414 are attached to the inlet and outlet tubes. The grounding points 1414 may be located away from the direct inlet / outlet of the reactor tube, but can be located within a reasonable distance to ensure that the inlet and outlet tubes are properly grounded. In some embodiments, the grounding points are located as close as possible to the inlet / outlet of the reactor tube.

[0136] FIG. 15 shows an alternative configuration to FIG. 14. FIG. 15 shows an inlet tube 1501 at the top, with arrows indicating the direction of flow. The material in this reactor tube is the material (e.g., fluid) intended to be heated within the reactor tube. At a 90° angle from the inlet, reactor tube 1502 is shown with multiple heating zones. While a single reactor tube is shown, the configuration of FIG. 15 is equally applicable to reactor systems with multiple reactor tubes. The material flows through the reactor tube and is collected in outlet tube 1503, shown at the bottom. In various embodiments, inlet tube 1501 is an inlet tube header or inlet tube arrangement, and outlet tube 1503 is an outlet tube header or outlet tube arrangement. As described in more detail below, in some embodiments, the reactor tubes are galvanically isolated from inlet tube 1501 and outlet tube 1503.

[0137] Within reactor tube 1502, three zones are formed by multiple AC power supplies (1504, 1505, and 1506) and transformers (1507, 1508, and 1509) operating in parallel.

[0138] A first AC power source 1504 is connected to a first transformer 1507. A second AC power source 1505 is connected to a second transformer 1508. A third AC power source 1506 is connected to a third transformer 1509.

[0139] In one embodiment of Figure 15, the transformers (1507, 1508, and 1509) are three-phase transformers. In another embodiment of Figure 15, the AC power sources (1504, 1505, and 1506) are three-phase power sources and the transformers (1507, 1508, and 1509) are three-phase transformers.

[0140] The first phase generated from each of transformers 1507, 1508, and 1509 is conducted to "phase 1" connection points 1510 and 1513. The second phase generated from each of transformers 1507, 1508, and 1509 is conducted to "phase 2" connection point 1511. The third phase generated from each of transformers 1507, 1508, and 1509 is conducted to "phase 3" connection point 1512. In this manner, three separate heating zones of the reactor tube can be created. Zone 1 is formed between connection points 1510 and 1511, zone 2 is formed between connection points 1511 and 1512, and zone 3 is formed between connection points 1512 and 1513.

[0141] In some embodiments, the currents supplied to Zone 1, Zone 2, and Zone 3 are the same. In other embodiments, the currents supplied to Zone 1, Zone 2, and Zone 3 are different.

[0142] Grounding points 1514 are attached to the inlet and outlet tubes. In some embodiments, the grounding points may be connected or routed to the same ground. The grounding points 1514 may be located away from the direct inlet / outlet of the reactor tube, but can be located within a reasonable distance to ensure that the inlet and outlet tubes are properly grounded. In some embodiments, the grounding points are located as close as possible to the inlet / outlet of the reactor tube.

[0143] Figure 16 shows a schematic diagram of one embodiment of a reactor heating system, where the reactor tube has several bends. It is known that piping can be oriented within an enclosure by using reactor tubes that bend one or more times from one side of the enclosure to the other, such as in a shell-and-tube heat exchanger. Figure 16 employs a similar design technique for the reactor tube.

[0144] In FIG. 16, reactor tube 1601 is configured to enter the outer shell 1602 of the reactor heating system, turn toward the bottom of the housing, return toward the top of the housing, and exit the bottom of the housing.

[0145] At the bottom of the housing, the reactor tubes are held in place by guide pins 1603 that can move to accommodate reactor tube movement due to thermal expansion and contraction of the tubes. The guide pins should be selected to be strong enough to hold the reactor tubes in place and to withstand the heat and energy conditions of the direct electric heating operation described herein. For example, the guide pins may be constructed of a similar material to the reactor tubes.

[0146] At the top of the enclosure, hangers are used to hold the reactor tubes in place. The hangers should be strong enough to hold the reactor tubes in place and be able to withstand the heat and energy conditions of the direct electric heating operation described herein. In some embodiments, a material may be used to electrically insulate and / or isolate the hangers from the reactor tubes. In some embodiments, the insulating / isolating material may be selected from the group consisting of ceramic, nylon, polystyrene, polyvinyl chloride (PVC), silicone, rubber, glass, and combinations thereof. In some embodiments, the insulating / isolating material may be selected from the group consisting of refractory materials, ceramic, and glass. In one embodiment, the insulating / isolating material may be a ceramic selected from the group consisting of ceramic fiber, ceramic blanket, ceramic substrate, or combinations thereof. In other embodiments, the insulating / isolating material may be selected from the group consisting of concrete (e.g., castable insulating concrete), fiber brick, mineral wool, or combinations thereof.

[0147] The reactor heating system of Figure 16 comprises two AC power sources (1605 and 1606) and two transformers (1607 and 1608). The first AC power source 1605 is connected to the transformer 1607, and power is directed to a connection point 1609 and the guide pin 1603. The second AC power source 1606 is connected to the transformer 1608, and power is directed to a connection point 1610 and the guide pin 1603. In this way, two zones are formed within the reactor tube: a first zone from the connection point 1609 to the guide pin 1603, and a second zone from the guide pin 1603 to the connection point 1610.

[0148] As previously mentioned, one aspect of this embodiment is that the guide pins are capable of withstanding the heat and energy conditions of direct electrical heating operation. A further aspect of this embodiment is that the guide pins comprise a material that allows electrical energy supplied to the guide pins to be directed into the reactor tube, as shown in FIG.

[0149] The use of a guide pin as one connection point for direct electrical heating of the reactor tube provides several advantages. Any electrical connection point is subject to wear and tear and requires maintenance at regular intervals. By utilizing a connection point that is external to the heater housing, the electrical connection point is easier to access and maintain. Furthermore, the electrical connection point is not exposed to the same extreme conditions (i.e., heat) as connections 1609 and 1610. Therefore, the material of the connection point on the guide pin does not need to withstand the temperatures that the material of connections 1609 and 1610 must withstand.

[0150] 16 shows power being supplied through the shell of the reactor heating system to connection points 1609 and 1610, and guide pin 1603 passing through the shell. In some embodiments, one or more insulating gaskets, electrical insulators, or insulating / isolating materials can be placed between the power source or guide pin and the shell wall.

[0151] While FIG. 16 shows one reactor tube in a bent tube configuration, it will be understood that similar designs can be employed in any of the methods or systems described herein to accommodate multiple reactor tubes or reactor tubes of different shapes within an enclosure.

[0152] Figure 17 shows a diagram of a reactor heating system similar to Figure 16, where the reactor tube has multiple bends, and in Figure 17, a single power supply 1705 and transformer 1706 is used.

[0153] 17 shows an electrical diagram superimposed on the reactor heating system. As described elsewhere herein, the reactor tube has an electrically conductive surface, and when electrical energy is applied to the electrically conductive surface, the reactor tube heats. The heating of the reactor tube then heats the catalyst or reactor fluid disposed therein. The impedance of the reactor tube acts as a resistive load in the circuit, as represented by the resistor superimposed on the reactor tube.

[0154] In FIG. 17, the reactor tubes are configured to enter the outer shell 1702 of the reactor heating system, turn toward the bottom of the housing, return toward the top of the housing, and exit the bottom of the housing.

[0155] At the bottom of the housing, the reactor tubes are held in place by guide pins 1703 that are able to move with the reactor tubes due to thermal expansion and contraction. At the top of the housing, the reactor tubes are held in place by hangers 1704. Guide pins 1703 and hangers 1704 are as generally described with reference to FIG. 16.

[0156] An AC power source 1705 is connected to a transformer 1706, and three-phase power is delivered to the nodes shown in Figure 17. Phase A of the three-phase power is delivered to node 1707, phase B is delivered to node 1708, and phase C is delivered to node 1709.

[0157] The reactor heating system has a ground point 1711. For example, as shown in Figure 17, the guide pin 1703 and hanger 1704 may be grounded.

[0158] In this configuration, equal electrical impedance is achieved in each zone formed within the reactor tube. For example, equal electrical impedance is observed in each zone between 1707 and 1708 and in each zone between 1708 and 1709.

[0159] While Figure 17 shows a bent tube configuration, the power configuration shown in this figure can also be applied to embodiments with multiple reactor tubes. For example, multiple parallel vertical reactor tubes may be arranged inside reactor shell 1702. In this case, a single source of three-phase power may be routed to a similarly arranged connection point for phase A, a similarly arranged connection point for phase B, and a similarly arranged connection point for phase C on each of the parallel reactor tubes.

[0160] In various embodiments, the present disclosure relates to heating systems and methods that utilize low voltage from one or more power sources. For example, the voltage may be about 100V or less, about 90V or less, about 80V or less, about 70V or less, about 60V or less, about 50V or less, about 40V or less, about 30V or less, about 20V or less, or about 10V or less.

[0161] In other embodiments, the present disclosure relates to heating systems and methods utilizing medium voltages. For example, the voltage may be from about 480 V to about 1 kV. In other embodiments, the voltage may be from about 1 kV to about 35 kV, from about 1 kV to about 30 kV, from about 1 kV to about 29 kV, from about 1 kV to about 28 kV, from about 1 kV to about 27 kV, from about 1 kV to about 26 kV, from about 1 kV to about 25 kV, from about 1 kV to about 24 kV, from about 1 kV to about 23 kV, from about 1 kV to about 22 kV, or from about 1 kV to about 21 kV. V, about 1 kV to about 20 kV, about 1 kV to about 19 kV, about 1 kV to about 18 kV, about 1 kV to about 17 kV, about 1 kV to about 16 kV, about 1 kV to about 15 kV, about 1 kV to about 14 kV, about 1 kV to about 13 kV, about 1 kV to about 12 kV, about 1 kV to about 11 kV, or about 1 kV to about 10 kV.

[0162] While certain configurations and embodiments are described herein, it will be understood that the heating systems and methods of the present disclosure should be designed to avoid electrical arcing. In certain configurations, the reactor tubes may be in close enough proximity that additional insulation or material is required to avoid electrical arcing. Similarly, in certain configurations, the reactor heating system components may be in close enough proximity to the reactor shell that additional insulation or material is required to avoid electrical arcing. The use of such insulation or other materials is within the scope of the present invention.

[0163] Although certain configurations and embodiments are described herein, it will be understood that the heating systems and methods of the present disclosure may comprise either grounded or ungrounded systems.

[0164] In some embodiments, the present disclosure relates to systems that utilize hybrid heat input control, such as systems that utilize both fuel-fired heating and electric heating (e.g., direct electric heating).

[0165] Those skilled in the art will appreciate that any of the methods or systems described herein are equally applicable to single-phase and multi-phase (eg, three-phase) current heating devices.

[0166] In one exemplary embodiment, the disclosed heating method and reactor system can be utilized in a steam methane reforming (SMR) process. While reference is made below to a catalytic SMR process, it will be understood that the disclosed method and reactor system are equally applicable to other catalytic reactions involving providing heat to the reaction. For example, the disclosed method and reactor system can also be applied to hydrotreating or hydrocracking processes. In one embodiment, the disclosed heating method and reactor system can be utilized in an ethylene reactor system. In another embodiment, the disclosed heating method and reactor system can be utilized in an ammonia cracking system.

[0167] The SMR process generally involves introducing methane and steam into a catalytic reactor and heating them to high temperatures to produce hydrogen and carbon monoxide. That is, the SMR process operates according to the following reaction scheme:

[0168] [ka]

[0169] The catalyst for the SMR process may be a nickel-containing catalyst. For example, in one embodiment, the catalyst comprises nickel deposited on an alumina ceramic substrate, such as Al2O3.

[0170] In one embodiment, a catalytic reactor for an SMR process includes a plurality of reactor tubes comprising an electrically conductive metal or alloy. For example, one or more of the reactor tubes may comprise nickel, chromium, niobium, and combinations thereof. In this embodiment, one or more surfaces of each of the reactor tubes comprise a sufficient electrically conductive metal or alloy such that at least one surface of each reactor tube is electrically conductive.

[0171] One or more reactor tubes in an SMR process are heated by supplying electrical energy to at least one electrically conductive surface of each of the reactor tubes. The temperature of each of the reactor tubes and the catalyst disposed therein is controlled by adjusting the current level of the electrical energy supplied to the at least one electrically conductive surface of each of the reactor tubes. Each of the reactor tubes is electrically isolated, or galvanically isolated as described in more detail above, from other electrically conductive components of the reactor system.

[0172] The SMR process may include heating one or more reactor tubes and the catalyst and reactor fluids disposed therein to a temperature of about 700°C or greater, about 750°C or greater, about 800°C or greater, about 850°C or greater, about 900°C or greater, or about 1,000°C or greater. In some embodiments, the one or more reactor tubes and catalyst are heated to a temperature of about 700°C to about 1,000°C, about 750°C to about 900°C, about 800°C to about 900°C, about 825°C to about 900°C, about 850°C to about 900°C, or about 850°C to about 875°C. For example, in one embodiment, the SMR process includes heating one or more reactor tubes and the catalyst and reactor fluids disposed therein to a temperature of about 870°C.

[0173] The SMR process may include maintaining a pressure of about 15 bar or more, about 16 bar or more, about 17 bar or more, about 18 bar or more, about 19 bar or more, about 20 bar or more, about 21 bar or more, about 22 bar or more, about 23 bar or more, about 24 bar or more, or about 25 bar or more, for example, about 15 bar to about 30 bar, about 16 bar to about 30 bar, about 17 bar to about 30 bar, about 18 bar to about 30 bar, about 19 bar to about 30 bar, about 20 bar to about 30 bar, about 20 bar to about 29 bar, about 20 bar to about 28 bar, about 20 bar to about 27 bar, about 20 bar to about 26 bar, or about 20 bar to about 25 bar.

[0174] Having described aspects of the present invention in detail, it will be apparent that modifications and variations are possible without departing from the scope of the invention as defined in the appended claims.

[0175] When describing elements of the invention or preferred embodiments thereof, the articles "a," "an," "the," and "said" are intended to mean that there are one or more elements. The terms "comprising," "including," and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements.

[0176] In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

[0177] Because various changes can be made in the above systems, processes, and reactions without departing from the scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings be interpreted as illustrative and not in a limiting sense.

Claims

1. 1. A method for heating a reactor system, comprising: The reactor system comprises: a plurality of reactor tubes, each of the plurality of reactor tubes having a catalyst disposed therein and at least one electrically conductive surface; a fluid flows into each of the plurality of reactor tubes through an associated inlet pipe header and flows out of each of the plurality of reactor tubes through an associated outlet pipe header; The method comprises: galvanically isolating the plurality of reactor tubes such that each of the plurality of reactor tubes is directly connectable to the inlet pipe header and the outlet pipe header; providing electrical energy to at least one conductive surface of each of the plurality of reactor tubes; individually adjusting a current level of the electrical energy supplied to at least one electrically conductive surface of each of the plurality of reactor tubes to individually control the temperature of each of the reactor tubes and the catalyst disposed therein; Including, method.

2. each of the plurality of reactor tubes is not electrically insulated; The method of claim 1.

3. each of the plurality of reactor tubes is galvanically isolated using a plurality of power controllers, the plurality of power controllers mirroring each other to generate approximately 0 volts at the inlet pipe header and approximately 0 volts at the outlet pipe header; The method of claim 1.

4. each of the plurality of reactor tubes is galvanically isolated using a split-phase transformer and grounding points at the inlet and outlet of the reactor tube; The method of claim 1.

5. a ground point connected to the inlet pipe header and a ground point connected to the outlet pipe header; The method of claim 1.

6. Providing electrical energy is providing energy from an AC power source to at least one of the conductive surfaces of each of the plurality of reactor tubes; 6. The method according to any one of claims 1 to 5.

7. Providing electrical energy is providing energy from a power source to a transformer to generate alternating current; applying the alternating current to at least one conductive surface of each of a plurality of reactor tubes; Including, 6. The method according to any one of claims 1 to 5.

8. electrical energy is supplied from a plurality of power sources to a plurality of locations on the at least one electrically conductive surface of each of a plurality of reactor tubes of the plurality of reactor tubes, thereby forming a plurality of heating zones within each of the reactor tubes; 8. The method according to claim 6 or 7.

9. For each of the plurality of reactor tubes, electrical energy is supplied from a first power source to a first location and a second location on the electrically conductive surface, and electrical energy is supplied from a second power source to the second location and a third location on the electrically conductive surface. The method of claim 8.

10. for each reactor tube of the plurality of reactor tubes, electrical energy is supplied from a three-phase power source to a transformer; a first phase from the transformer is directed to a first location on the conductive surface of the reactor tube; a second phase from the transformer is directed to a second location on the conductive surface of the reactor tube; a third phase from the transformer is directed to a third location on the conductive surface of the reactor tube; creating multiple heating zones within the reactor tube; 6. The method according to any one of claims 1 to 5.

11. 11. The method of claim 10, wherein there is a ground point at the inlet and outlet of each of the reactor tubes.

12. 1. A method for heating a reactor system, comprising: the reactor system comprises a reactor tube having a catalyst disposed therein and at least one electrically conductive surface; The method comprises: galvanically isolating the reactor tube from other conductive components of the reactor system; providing electrical energy to the at least one electrically conductive surface of the reactor tube; individually adjusting the current level of the electrical energy supplied to at least one conductive surface of the reactor tube to control the temperature of the reactor tube and the catalyst disposed therein; Including, method.

13. the reactor tube is present in the reactor system as a two-pass reactor tube; The reactor tube is fixed at one end of the reactor system by a guide pin and at the other end of the reactor system by a hanger. The method of claim 12.

14. the guide pin is electrically conductive and is connected to a second location on the electrically conductive surface of the reactor tube. The method of claim 13.

15. a first power source supplies electrical energy to a first location on the conductive surface of the reactor tube and to the guide pin, and a second power source supplies electrical energy to the guide pin and to a third location on the conductive surface of the reactor tube; 15. The method of claim 13 or 14.

16. each of the reactor tubes includes an electrically conductive material attached thereto; the attached conductive material forms a conductive surface of each of the reactor tubes.

16. The method of any one of claims 1 to 15.

17. the conductive material comprises a metal or alloy selected from the group consisting of gold, silver, copper, aluminum, nickel, tin, brass, iron, platinum, palladium, molybdenum, tungsten, chromium, niobium, chromium, alloys thereof, and combinations thereof; 17. The method of any one of claims 1 to 16.

18. a temperature of at least one reactor tube of the plurality of reactor tubes is different from a temperature of other reactor tubes of the plurality of reactor tubes; a temperature difference between the hottest reactor tube of the plurality of reactor tubes and the coldest reactor tube of the plurality of reactor tubes is about 50° C. or less; 12. The method according to any one of claims 1 to 11.

19. implementing a cascade control scheme by a controller; adjusting operational setpoints of the controller in accordance with the cascade control scheme, wherein a power controller coupled to a source of electrical energy adjusts a current level of the source of electrical energy in response to the operational setpoints to heat each of the reactor tubes of the plurality of reactor tubes to a desired reactor outlet temperature; Including, 19. The method of any one of claims 1 to 18.

20. 1. A reactor system comprising a plurality of reactor tubes, each of the plurality of reactor tubes having a catalyst disposed therein and at least one electrically conductive surface; a fluid flows into each of the plurality of reactor tubes through an associated inlet pipe header and flows out of each of the plurality of reactor tubes through an associated outlet pipe header; electrical energy is supplied to at least one conductive surface of each of the plurality of reactor tubes, and a current level of the electrical energy supplied to the at least one conductive surface of each of the plurality of reactor tubes is adjusted to individually control the temperature of each of the reactor tubes and the catalyst disposed therein; the reactor tubes are galvanically insulated so that each of the reactor tubes can be directly connected to the inlet pipe header and the outlet pipe header; Reactor system.

21. The reactor tubes are galvanically isolated using power controllers, the power controllers configured to mirror each other to generate approximately 0 volts at the inlet pipe header and approximately 0 volts at the outlet pipe header.

21. The reactor system of claim 20.

22. each of the plurality of reactor tubes is galvanically isolated using a split-phase transformer, and a ground point is present at the inlet and outlet of each of the plurality of reactor tubes; 21. The reactor system of claim 20.

23. for each reactor tube of the plurality of reactor tubes, electrical energy is supplied from a three-phase power source to a transformer; a first phase from the transformer is directed to a first location on the conductive surface of the reactor tube; a second phase from the transformer is directed to a second location on the conductive surface of the reactor tube; a third phase from the transformer is directed to a third location on the conductive surface of the reactor tube; creating multiple heating zones within the reactor tube; 21. The reactor system of claim 20.

24. a ground point is present at the inlet and outlet of each of the reactor tubes of the plurality of reactor tubes; 24. The method of claim 23.

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