Methane pyrolysis using a layered fluidized bed with electrical heating of coke

Abstract

Systems and methods are provided for converting methane and / or other hydrocarbons to hydrogen by pyrolysis while reducing or minimizing the production of carbon oxides. Heating of the pyrolysis environment can be performed at least in part using electrical heating in a first stage, where coke particles are heated to a desired pyrolysis temperature. To reduce, minimize, or eliminate coke formation on the surface of the electrical heater, electrical heating can be performed in a hydrogen-rich environment. The heated coke particles are then transferred to a second stage for contact with a methane-containing feedstock, such as a natural gas feedstock. Depending on the configuration, pyrolysis of methane can occur in both the first and second stages. In some embodiments, the hydrogen-rich environment in the first stage is created by passing a partially converted effluent from the second stage back to the first stage. In such embodiments, the partially converted effluent from the second stage can have an H content of 60% by volume or more, 70% by volume or more, or 80% by volume or more, e.g., up to 99% by volume, and in some cases even higher.

Description

[Technical field]

[0001] The present invention relates to a system and method for converting methane to hydrogen while reducing or minimizing the production of CO2. [Background technology]

[0002] One of the challenges with carbon capture or sequestration technologies is the wide variety of processes that consume hydrocarbons and generate CO2. In addition to the difficulty of applying carbon capture technologies to small point sources such as automobiles, there can also be challenges with larger CO2 sources. For example, a refinery may be considered a single CO2 source, but the current refinery configuration is more like multiple small sources. Achieving economies of scale with carbon capture can be difficult, due to the challenges involved in trying to stream CO2 from various sources within a refinery to a single CO2 sequestration unit.

[0003] An alternative to attempting to capture CO2 from multiple point sources would be to first convert the hydrocarbons to hydrogen in a central location and then distribute the hydrogen to various systems and / or processes for consumption. In a refinery setting, this could be achieved, for example, by steam reforming of hydrocarbons (e.g., methane). While this could potentially create a single source of CO2, the fundamental challenge of generating large quantities of CO2 remains.

[0004] An alternative to using steam reforming to produce hydrogen is to use the pyrolysis of methane (or, more generally, the pyrolysis of hydrocarbons), during which methane is converted to hydrogen and solid carbon, thus avoiding the stoichiometric CO2 emissions associated with steam reforming.

[0005] Unfortunately, the pyrolysis of methane poses additional challenges. For example, in addition to being an endothermic process, pyrolysis of methane requires temperatures much higher than those required for steam reforming. Generating the heat required to achieve such temperatures can be a source of CO2 emissions. Efficient heat recovery and / or transfer is also desirable to mitigate heating needs. Other challenges can be associated with managing heat within the reaction zone of the reactor while also maintaining a desirable reaction rate.

[0006] What is needed are systems and methods that can convert methane (or other hydrocarbons) to hydrogen while reducing or minimizing the production of CO. Preferably, the systems and methods can allow for heat management and heat recovery while maintaining commercially desirable reaction rates.

[0007] US Patent No. 3,284,161 describes a method for producing hydrogen by catalytic decomposition of a gaseous hydrocarbon stream. The method is carried out in a two-vessel system. In the first vessel, the gaseous hydrocarbon is exposed to a catalyst at high temperature to produce hydrogen and carbon, which is deposited on the catalyst. After separation of the catalyst from the products (and unreacted feed), the catalyst is sent to a regenerator where the carbon on the catalyst is burned. The heat generated during combustion is returned, at least in part, to the first vessel by recirculation of the catalyst. Before contacting the catalyst particles with the gaseous feed, the catalyst particles are stripped with hydrogen generated in the reaction zone. This is explained as being beneficial to reduce the generation of carbon oxides in the reaction zone.

[0008] U.S. Patent No. 3,284,161 describes a system and method for the catalytic decomposition of methane in a countercurrent reactor. The reactor is described as including side-to-side plates to provide multiple contacting stages within the reactor.

[0009] US Patent No. 9,359,200 describes a system and method for the thermal cracking of methane. Methane is exposed to a countercurrent flow of carbonaceous particles at sufficient temperature in either a fluidized or moving bed environment to be pyrolyzed into hydrogen and carbon. The process is also described as being useful in converting smaller coke particles that are unsuitable for use as fuel in a blast furnace environment into particles that can be used as fuel.

[0010] A journal article titled “Introduction to Fluidization Methods” (Cocco et al., pp. 21-29, CEP Magazine, November 2014, published by the American Institute of Chemical Engineers) provides a detailed example on how to calculate the minimum fluidization velocity of particles in a fluidized bed. Summary of the Invention

[0011] In some embodiments, a method of carrying out pyrolysis of hydrocarbons to produce H2 is provided. The method may include heating a first fluidized bed of coke particles in a first fluidized bed stage to a temperature of 1000°C or more using one or more electric heating elements in the first fluidized bed. The gas environment in the first fluidized bed may include 60% by volume or more of H2. Additionally, the method may include flowing at least a portion of the coke particles from the first fluidized bed to a second fluidized bed stage containing the coke particles. The second fluidized bed stage may include a second fluidized bed having a temperature of 1000°C or more. The method may further include contacting the hydrocarbon-containing feedstock with the coke particles in the second fluidized bed stage under pyrolysis conditions to produce a partially converted effluent containing H2. Additionally, the method may include contacting at least a portion of the partially converted effluent with the first fluidized bed stage of the coke particles to produce an H2-containing product.

[0012] In some embodiments, a system for carrying out pyrolysis of hydrocarbons is provided. The system may include a first fluidized bed stage including a first fluidized bed of coke particles and one or more electric heating elements in the first fluidized bed. The system may further include a second fluidized bed stage including a second fluidized bed of coke particles. The second fluidized bed stage may be in fluid and particle transport communication with the first fluidized bed stage. The system may further include a particle recycle loop providing fluid communication between a first upstream fluidized bed in the second fluidized bed stage and a final downstream fluidized bed in the first fluidized bed stage. The particle recycle loop may include a pneumatic transport conduit. The system may further include a feed inlet in fluid communication with the second fluidized bed stage. Additionally, the system may include a product effluent outlet in fluid communication with the first fluidized bed stage. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 illustrates an example of a reactor system for carrying out thermal cracking of hydrocarbons using electrical heating of a fluidized bed. [Diagram 2] FIG. 2 shows an example of a reaction system for carrying out thermal cracking of hydrocarbons using sequential fluidized beds. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] For all numerical values ​​within the detailed description and claims herein, the indicated value is modified by "about" or "approximately" to account for experimental error and variations that would be expected by one of ordinary skill in the art.

[0015] overview In various embodiments, systems and methods are provided for converting methane and / or other hydrocarbons to hydrogen by pyrolysis while reducing or minimizing the production of carbon oxides. Heating of the pyrolysis environment can be performed, at least in part, by heating the coke particles to a desired pyrolysis temperature using electrical heating in the first stage. To reduce, minimize, or eliminate the formation of coke on the surface of the electrical heater, this electrical heating can be performed in a hydrogen-rich environment. The heated coke particles can then be transferred to a second stage for contact with a methane-containing feedstock, such as a natural gas feedstock. Depending on the configuration, pyrolysis of methane can occur in both the first and second stages. In some embodiments, the hydrogen-rich environment in the first stage is formed by passing the partially converted effluent from the second stage to the first stage. In such embodiments, the partially converted effluent from the second stage can have an H2 content of 60% by volume or more, 70% by volume or more, or 80% by volume or more, such as up to 99% by volume, and in some cases even higher. Additionally, or alternatively, in such embodiments, the partially converted effluent may have a methane content of 40 vol.% or less, 30 vol.% or less, or 20 vol.% or less, for example, a minimum of 1.0 vol.%, and in some cases even lower.

[0016] One of the challenges of using pyrolysis of methane (or pyrolysis of hydrocarbons more generally) to convert methane (or hydrocarbons) to hydrogen and solid carbon is to reduce or minimize secondary reactions within the pyrolysis environment. As an example, in a fluidized bed setting, one way to provide the heat required for pyrolysis of methane is to burn the hydrogen produced by pyrolysis of methane to heat the coke particles formed from the carbon. While this appears to avoid adding CO2 to the pyrolysis environment, burning hydrogen produces water. The presence of water in an environment with heated coke particles induces secondary reactions that produce CO2. Thus, while burning hydrogen in a pyrolysis environment does not directly produce CO2, burning hydrogen produces products that promote secondary reactions that result in the production of CO2.

[0017] Another consideration for converting methane to hydrogen and solid carbon is to provide the heat necessary to carry out the pyrolysis of methane without consuming most or all of the resulting desired hydrogen product as fuel for the pyrolysis environment. Based on the chemistry of pyrolysis of methane, if the carbon from methane is successfully converted to solid carbon, no CO2 is produced. From a carbon recovery perspective, this is a favorable outcome, since the carbon product is solid and can be used or disposed of in any useful way. However, the production of CO2 is highly exothermic, representing more than half of the heating value typically expected from the combustion of methane. As a result, the heating value of the hydrogen generated in the pyrolysis of methane represents about 45% of the initial heating value of the methane feedstock. Attempting to use hydrogen from methane pyrolysis as fuel to heat the pyrolysis environment can be challenging, since a large portion of the hydrogen produced may be required just to maintain the desired reaction temperature for pyrolysis, given the heat losses.

[0018] An alternative to burning hydrogen to provide heat to the reaction environment is to burn another type of fuel. Although this is effective, it poses additional challenges due to the CO2 produced from the other fuel. Burning a carbon-containing fuel in situ produces CO2 in the reaction environment. In this case, further downstream processing of the effluent from the pyrolysis reactor may be required so that the CO2 reduction benefits of hydrogen production by pyrolysis are not lost due to the combustion required to heat the reaction environment. By indirectly heating the reaction environment, any CO2 capture unit can be part of a separate processing step (or processing train) from the pyrolysis effluent, but there is a risk of producing larger amounts of CO2 due to the reduced efficiency associated with indirect heating.

[0019] For pyrolysis carried out in a fluidized bed environment, electrical heating of the fluidized bed can alleviate some of the difficulties associated with achieving and maintaining the desired temperature for pyrolysis of methane while reducing or minimizing secondary reactions in the pyrolysis environment. Electrical heating can be carried out in the fluidized bed environment by including electric heating elements in the fluidized bed. The nature of the fluidized bed allows for efficient heat transfer between a heating element and the fluidized bed. Electrical heating can be used to heat at least one fluidized bed (in a H2-rich environment) to a temperature of 1000°C or higher for transport of coke particles to the pyrolysis bed operating at 1000°C or higher. It is noted that while some pyrolysis can occur at temperatures below 1000°C, without at least one fluidized bed for pyrolysis at temperatures of approximately 1000°C or higher, the reactor size would need to be excessively large to achieve commercial scale production of hydrogen.

[0020] Because electrical heating does not involve the performance of additional reactions within the pyrolysis reaction environment, the number of secondary reactions caused by electrical heating is minimized. However, the inclusion of an electrical heating element in a fluidized bed environment containing coke particles can result in coke migration from the coke particles to the heating element. To reduce or eliminate this coke migration, electrical heating in the fluidized bed environment can be performed in the presence of significant amounts of H2 and / or reduced or minimal amounts of methane. This can be accomplished, for example, by heating a first fluidized bed of coke particles in a hydrogen-rich environment and passing the heated coke particles from the first fluidized bed through a second fluidized bed of coke particles.

[0021] With regard to further CO2 production, it is noted that CO2 production associated with electrical heating can vary depending on the source of electricity used to generate it. Electricity generated by burning hydrocarbon fuels at remote power generating facilities can have relatively high CO2 emissions per unit of electricity due to transmission line losses. On the other hand, if renewable electricity is available, it can have relatively low CO2 emissions per unit of electricity.

[0022] In some embodiments, the conversion of hydrocarbons to hydrogen can be carried out in one or more pyrolysis or conversion reactors that include multiple continuous fluidized beds. The fluidized beds are arranged so that the coke particles forming the fluidized bed move in a countercurrent direction to the gas-phase flow of feed and / or products (e.g., methane, partially recycled effluent, H2) in the fluidized bed. In such embodiments, electrical heating of the coke particles can occur in at least one bed of a first group of one or more fluidized beds. The coke particles can then be transferred to a second group of one or more fluidized beds for contact with fresh feed. By using multiple continuous fluidized beds, the heat transfer and management advantages of fluidized beds can be realized while also at least partially achieving the enhanced reaction rates associated with plug flow or moving bed reactors.

[0023] It should be noted that the inclusion of four or more fluidized beds, or five or more fluidized beds, may be sufficient to achieve most of the kinetic reaction advantages of a plug flow moving bed reactor. The pyrolysis / conversion reactor may include a substantially oxygen-free reaction environment under fluidized bed reaction conditions. Because the pyrolysis environment is substantially oxygen-free, it may be possible to pyrolyze methane into hydrogen and carbon while reducing or minimizing the direct production of carbon oxides.

[0024] In embodiments using multiple fluidized beds to carry out pyrolysis, the multiple fluidization may also provide reaction rate advantages. The conversion of methane to hydrogen and carbon is an equilibrium reaction. As a result, a high concentration of hydrogen in the local environment reduces the net conversion rate of methane to hydrogen and carbon. In reactors where a single fluidized bed is used for pyrolysis, the well-mixed nature of the fluidized bed may result in a relatively uniform hydrogen concentration throughout the bed. Thus, when carrying out pyrolysis in a single fluidized bed, the net conversion of hydrogen is reduced.

[0025] By using multiple fluidized beds operating under pyrolysis conditions, the concentration of hydrogen can be varied within the bed. For example, as the methane feedstock flows upward through the fluidized beds, it reaches the first bed operating under pyrolysis conditions. In this first bed, the hydrogen content will be relatively low. This can allow for rapid conversion of methane to hydrogen and carbon in the first bed. As the gas stream proceeds upward, it reaches the second fluidized bed operating under pyrolysis conditions. Because some hydrogen is already present in the gaseous feed to the second bed, the concentration of hydrogen in the second fluidized bed will be higher and the reaction rate will be slower. However, a net increase in conversion rate can be achieved based on the increase in reaction rate achieved in the first fluidized bed operating under pyrolysis conditions. Without being bound to a particular theory, it is noted that two hydrogen molecules are required to combine H2 with carbon (a solid) to produce methane, and such a reaction is quadratic in the H2 concentration under standard kinetic models. Due to this quadratic dependence, the reaction rate of methane production is believed to vary as a function of the square of the H2 concentration. As a result, carrying out pyrolysis reactions in multiple fluidized beds does not simply result in reaction rates comparable to a single bed of similar total area. Rather, the increase in reaction rate achieved in a low concentration fluidized bed can be greater than the decrease in reaction rate in a higher concentration fluidized bed. This allows multiple fluidized beds to provide a higher net conversion rate of methane conversion than would be achieved by a single fluidized bed of the same size.

[0026] The use of multiple continuous fluidized beds can have advantages in the pyrolysis of methane compared to configurations employing either moving beds or a single fluidized bed of similar size to the continuous fluidized bed. With respect to a single fluidized bed of similar size, it should be noted that the fluidized bed is a well-mixed environment. Thus, although the gas in the fluidized bed has a net flow direction, the concentration of the gas in the fluidized bed is relatively constant throughout the bed. This allows the fluidized bed to have excellent heat transfer capabilities and a relatively uniform temperature throughout the fluidized bed. However, equilibrium reactions also mean that the entire bed operates at the average concentration of reactants and products in the bed. Thus, for equilibrium reactions with a product concentration dependency of second order (or higher) for at least one product, a single fluidized bed can significantly reduce the net conversion rate compared to multiple continuous fluidized beds of similar total volume.

[0027] Countercurrent plug-flow configurations for methane pyrolysis are an alternative option to achieve increased methane net conversion rates compared to single fluidized bed configurations. With moving bed configurations, increased net conversion rates for pyrolysis of methane can be achieved due to the low concentration of hydrogen in the portion of the moving bed where methane is first exposed to pyrolysis conditions. However, maintaining temperature control throughout the moving bed is difficult. In particular, the moving bed or plug flow environment provides poor lateral (perpendicular to the flow direction of the moving bed) heat transfer. This means that external heating methods based on electrical heating have great difficulty in providing heat to the pyrolysis reactions inside the moving bed. While this can be overcome by using heating tubes inside the moving bed environment, using a sufficient number of heating tubes to provide relatively uniform heating throughout the moving bed can result in significant disturbances or turbulence in the flow pattern. Such turbulence defeats the purpose of using a fluidized bed, as it modifies the characteristics of the fluidized bed to behave more like a fluidized bed. Another alternative is to use a direct heating method, such as moving the moving bed particles to a second reaction environment and directly heating the particles by combustion. Heating the particles to transfer heat to the moving bed overcomes the difficulties of lateral heat transfer through the moving bed. However, such heating of the particles by combustion typically requires the combustion of hydrocarbons. As a result, large amounts of CO2 are produced, reducing or minimizing the benefits of carrying out the pyrolysis of methane.

[0028] In contrast to systems using a single fluidized bed or countercurrent moving bed, in various embodiments, multiple continuous fluidized beds can be used to carry out the thermal cracking of hydrocarbons. By using multiple continuous fluidized beds, the heat transfer advantages of a fluidized bed can be achieved, allowing the use of external heating methods while achieving increases in net conversion rate similar to those provided by moving bed reactors.

[0029] Additionally or alternatively, systems and methods are provided for managing particle flow in one or more pyrolysis or conversion reactors that include multiple continuous fluidized beds. One of the challenges in managing one or more fluidized beds can be managing the particle flow after the particles are withdrawn from the fluidized bed. For example, some system for moving the particles is required to recycle the particles from the bottom to the top of the fluidized bed reactor. Since commercial scale reactors can move thousands of tons of particles per hour, various problems can arise when attempting to use mechanically driven transport mechanisms (such as using a screw conveyor). Such problems can include particle agglomeration, bonding, and / or particle attrition forming undesirable particle fines. In various embodiments, particle transport challenges can be reduced or minimized by using pneumatic transport to circulate the particles from the final bed back to the initial bed of the continuous fluidized bed. The gas used for pneumatic transport can correspond to the hydrogen-containing product gas produced by the pyrolysis reactor. At the top of the pneumatic transport conduit, a gas-solid separator can be used to recover the hydrogen-containing product gas from the solid particles. In addition to reducing or minimizing mechanical challenges, the use of product gas for pneumatic transport can also avoid dilution of the desired product with another type of pneumatic gas.

[0030] After exiting the reactor, the hydrogen of the hydrogen-containing product gas can be separated from any remaining methane in the product gas by any useful method. Examples of suitable methods include pressure swing adsorption (PSA) and membrane separation. Methane recovered from the hydrogen-containing product gas can be recycled, for example, for use as part of the feedstock, and / or diverted for another use.

[0031] In some embodiments, multiple fluidized beds may be organized as a vertical stack, in which case the transport of coke particles from one bed to another may be managed by using gravity assisted flow in conjunction with selected fluidized bed conditions.

[0032] definition In this paper, the terms "upstream" and "downstream" are defined with respect to the gas flow in the reactor or reactors. Thus, the fluidized beds "upstream" of the fluidized beds operating under pyrolysis conditions correspond to those fluidized beds whose gas flow corresponds mainly to unreacted methane (and / or other hydrocarbons). The fluidized beds "downstream" of the fluidized beds operating under thermolysis conditions correspond to those fluidized beds whose gas flow contains a significant amount of hydrogen. Thus, the first group of fluidized beds is upstream of the fluidized beds operating under pyrolysis conditions (i.e., the second group of fluidized beds), and the third group of fluidized beds is downstream of the fluidized beds operating under pyrolysis conditions. It should be noted that since the coke particles move in a countercurrent direction, the coke particles are heated in the heat transfer beds "downstream" of the fluidized beds operating under pyrolysis conditions. Similarly, the coke particles are cooled in the heat transfer beds "upstream" of the fluidized beds operating under pyrolysis conditions.

[0033] In this document, the term "adjacent" may be used to describe the relative location of fluidized beds. For example, a fluidized bed that is "upstream adjacent" to a fluidized bed operating under pyrolysis conditions corresponds to the last heat exchange fluidized bed to which the methane feedstock is exposed before being exposed to pyrolysis conditions. A fluidized bed that is "downstream adjacent" to an externally heated fluidized bed corresponds to the first fluidized bed to which the product gas stream is exposed after exiting the externally heated fluidized bed.

[0034] In this document, a "continuous" fluidized bed refers to multiple fluidized beds, each of which is in both fluid communication and solid particle transport communication with any adjacent fluidized bed. Fluid communication refers to the passage of gas and / or liquid between elements in the system. Note that particles may be entrained in the fluid, so some solids may also be transported through the fluid communication. Particle transport communication refers to the transport of solids between elements in the system, and refers to the passage of particles from a first fluidized bed to an adjacent fluidized bed. Note that the first and last beds in a continuous fluidized bed only have one adjacent bed, and the remaining fluidized beds in the continuous fluidized bed have both an adjacent upstream fluidized bed and an adjacent downstream fluidized bed.

[0035] In this document, a "hydrocarbon-containing feed" is defined as a feed containing 75% or more, 90% or more, 95% or more, or 98% or more by volume of C1-C4 alkanes, e.g., substantially all of the feed corresponds to C1-C4 alkanes. Examples of suitable feeds include methane and natural gas. In some embodiments, the hydrocarbon-containing feed may contain 10% or less, 5.0% or less, or 2.0% or less by volume of N2, e.g., substantially no N2 (less than 0.1% by volume). In some embodiments, the H2 content of the input feed may be 10% or less, or 1.0% or less by volume, e.g., substantially no H2 (less than 0.1% by volume).

[0036] Electrical heating and temperature control of a fluidized bed of coke particles. In various embodiments, the pyrolysis of hydrocarbons (such as the pyrolysis of methane) can be carried out by using at least two fluidized beds of coke particles. The electric heating element can be disposed in the first fluidized bed (in the first fluidized bed stage) operating in an H2-rich environment.

[0037] To achieve 60% or more methane conversion of the input methane feedstock, pyrolysis temperatures of 1000° C. or higher can be used in at least one fluidized bed of the pyrolysis reactor having a methane-rich environment. For example, the temperature in at least one fluidized bed for pyrolysis can be 1000° C. to 1400° C., 1000° C. to 1200° C., 1000° C. to 1600° C., 1100° C. to 1400° C., 1100° C. to 1600° C., 1200° C. to 1400° C., or 1200° C. to 1600° C. Subjecting the pyrolysis bed having a methane-rich environment to such temperatures means that the at least one fluidized bed including the electric heating element (and having a H2-rich environment) also has such temperatures.

[0038] An array of electric heating elements may be included in the fluidized bed to provide heat to the coke particles in the fluidized bed. The array of electric heating elements may have any useful geometric shape or arrangement. In embodiments where the fluidized bed has sufficient height, the array of heating elements may optionally correspond to a three-dimensional array such that the heating elements are spatially distributed within the height, width, and length of the fluidized bed. The symmetry (or lack of symmetry) of the arrangement of the heating elements may correspond to any useful type of arrangement. Possible types of arrangements may include an arrangement with radial symmetry, an arrangement including a row of heating elements along an axis, multiple rows of heating elements along one or more axes, stacked rows of heating elements where the heating elements of different rows are substantially parallel, or stacked rows of heating elements where the heating elements of different rows are not substantially parallel.

[0039] In some embodiments, a single fluidized bed may include an electric heating element. In other embodiments, multiple fluidized beds may include at least one electric heating element. In embodiments where one or more fluidized beds include a heating element, different fluidized beds may be heated to different temperatures. One or more fluidized beds that include an electric heating element within the fluidized bed correspond to a first stage of the fluidized bed. Note that additional fluidized beds that do not include a heating element may also be included in the first stage. In some embodiments, the division of the fluidized bed between the first stage fluidized bed and the second stage fluidized bed may correspond to the position where the fluidized bed that includes the electric heating element and the H2-rich environment is adjacent to an upstream bed that does not include an electric heating element. If multiple positions in a series of multiple fluidized beds meet this criterion, the division between the first stage and the second stage corresponds to the most upstream position where the fluidized bed that includes the electric heating element and the H2-rich environment is adjacent to an upstream bed that does not include an electric heating element.

[0040] Due to the high fluidized bed temperatures for carrying out pyrolysis of hydrocarbons (such as pyrolysis of methane), the electric heating elements may be formed from materials that are resistant to high temperatures while also being sufficiently wear-resistant to maintain structural integrity within the fluidized bed of coke particles. Silicon carbide is one example of a material suitable for forming the electric heating elements. Examples of silicon carbide heating elements are sold under the brand name Kanthal® by Sandvik Materials Technology, Hallstahammar, Sweden. Other examples of materials that may be used to form the heating elements include, but are not limited to, Fe / Cr / Al alloys; molybdenum; tungsten; silicon carbide; and combinations thereof. It is noted that suitable refractory materials are also available for the construction of reactors including fluidized beds operating at temperatures of 1000° C. or higher.

[0041] For the H2-rich environment used to perform the electrical heating of the fluidized bed of coke particles, such an environment can be provided by passing the partially converted effluent through at least one fluidized bed used for electrical heating. For example, the fluidized bed (or beds) for pyrolysis can convert enough methane so that 60% by volume or more, 70% by volume or more, or 80% by volume or more, for example up to 99% by volume of the partially converted effluent corresponds to H2. The partially converted effluent can still contain some methane, for example 40% by volume or less, 30% by volume or less, or 20% by volume or less, for example as low as 1.0% by volume. Thus, some further conversion of methane can occur in the fluidized bed (or beds) including the electrical heater. It is noted that hydrogen separated from the pyrolysis effluent can be used to provide an H2-rich environment for electrical heating. However, significant additional heating and cooling may be required if hydrogen separated from the pyrolysis effluent is to be used. In particular, typical processes for the separation of H2 from CH4 are carried out at temperatures much lower than those used for pyrolysis, and therefore the use of H2 separated from the pyrolysis effluent requires reheating of the separated H2.

[0042] In addition to using electric heating elements to heat the coke particles in at least one fluidized bed in an H2-rich environment, other types of heat management can be used to achieve the desired temperature for pyrolysis of hydrocarbons. For example, the fluidized beds are typically arranged in a countercurrent manner so that the net flow of gas in the reaction system is in the opposite direction to the net flow of the coke particles. Based on the definition that "upstream" and "downstream" are defined based on gas flow, the at least one fluidized bed containing electric heating elements is typically arranged downstream of the one or more beds in which pyrolysis is carried out in a methane-rich environment. In some embodiments, there may be one or more upstream fluidized beds that can be used to provide supplemental heating of the coke particles before entering the at least one fluidized bed containing electric heating elements. The supplemental heating in the one or more upstream beds can be carried out by heat exchange with the gas passing through the bed.

[0043] Another type of temperature management can be based on limiting the amount of cooling of the coke particles that occurs after pyrolysis. In some embodiments, the methane feedstock can be introduced to an initial fluidized bed (i.e., the most upstream bed) of coke particles having a temperature of 700°C or more, 800°C or more, 900°C or more, or 1000°C or more, for example, up to 1400°C or up to 1600°C. As the coke particles leave the initial fluidized bed, they can be recycled to the final bed (i.e., the most downstream bed) of the reaction system. By having a temperature of the initial fluidized bed of coke particles of 700°C or more, the temperature of the coke particles is maintained at a high temperature within the reaction system. This reduces the amount of energy input required to increase the temperature of the coke particles using electrical heating. Additionally or alternatively, the temperature of the initial fluidized bed of coke particles can be sufficiently high such that the coke particles recycled from the initial fluidized bed of coke particles to the final bed of the reaction system have a temperature of 700°C or more, 800°C or more, or 900°C or more, for example, up to 1400°C.

[0044] In an embodiment where only one fluidized bed is used for pyrolysis, the methane feed may be passed through a single fluidized bed for pyrolysis at a temperature of 1000° C. or higher. Coke particles withdrawn from the pyrolysis fluidized bed are then recycled to the top of the fluidized bed which contains an electric heater, also maintained at a temperature similar to that of the pyrolysis fluidized bed.

[0045] When multiple continuous fluidized beds are used in the pyrolysis environment and / or when a further continuous fluidized bed is adjacent to at least one bed containing an electric heating element, the further fluidization may allow heat exchange between the coke particles and the gas stream. For example, any fluidized bed upstream of a fluidized bed having a temperature of 1000° C. or higher may contain hot coke particles. Such beds may be used to preheat the incoming methane gas stream. Similarly, any fluidized bed downstream of at least one bed containing an electric heating element may represent a fluidized bed in which the gas stream is at a high temperature. Such downstream beds may be used to transfer heat from the gas stream to the incoming coke particles and preheat the particles before entering at least one bed containing an electric heating element.

[0046] Fluidized bed management for multiple fluidized beds in series In some embodiments, the methane pyrolysis reaction may be carried out using multiple fluidized beds in series arranged in at least two groups. A first group of one or more fluidized beds may correspond to a fluidized bed for heating coke particles, including heating the coke particles with an electric heating element in an H2-rich environment. A second group of one or more fluidized beds may correspond to a fluidized bed for pyrolyzing a methane feedstock (or other hydrocarbon feedstock, such as natural gas).

[0047] In some embodiments, the temperatures of the various fluidized beds may be selected in part to achieve a desired amount of heat energy transfer downward from the bed containing the electric heating elements and H2-rich environment to the second stage fluidized bed where the high concentration of hydrocarbons is present. To achieve this, the heat capacity of the coke moving downward (upstream relative to the gas flow direction) may be made greater than the heat capacity of the gas moving upward (downstream relative to the gas flow direction). Mathematically, this can be expressed as C p (Coke particle) x <Coke mass flow rate>> C p It can be expressed as (gas flow) x <gas mass flow rate>. p are the heat capacities per gram of coke particles or gas stream, respectively. This can reduce or minimize the temperature difference between the fluidized bed containing the electric heating element and the upstream fluidized bed that does not contain the electric heating element but has a higher concentration of hydrocarbons. It should be noted that the total heat capacity of the coke particle and gas streams can change within the fluidized bed as the methane is converted to hydrogen and solid carbon by pyrolysis. Thus, the heat capacity of the coke increases as it descends the continuous fluidized bed, and the heat capacity of the gas decreases as the hydrocarbon-containing feedstock is converted to the hydrogen-containing product effluent.

[0048] In embodiments in which one or both of the groups of fluidized beds comprises multiple fluidized beds, the number of beds in each group of fluidized beds can be selected to be any useful number, in some examples, from 2 to 10, or from 2 to 15 fluidized beds can be used in each group.

[0049] It should be noted that the second group of beds corresponding to the pyrolysis reaction zone may include multiple sets of reaction conditions. For example, if there are multiple fluidized beds in the group of fluidized beds for pyrolysis, at least one fluidized bed may have a temperature of 1000°C or higher. This may include having multiple fluidized beds with a temperature of 1000°C or higher, or having only a single fluidized bed with a temperature of 1000°C or higher. In such an embodiment, the temperature of the fluidized bed may decrease in the upstream direction.

[0050] The size of the fluidized beds may be independently selected in any useful manner. This allows the fluidized beds in the first group of fluidized beds and / or the second group of fluidized beds to have different sizes. The use of different sized beds may vary the average residence time of the coke particles and / or gases in the fluidized bed. This may allow independent control of the average residence time. For example, the desired average residence time in the fluidized bed in the reaction zone of the pyrolysis may be different from the desired average residence time of the coke particles in the fluidized bed that includes the electric heating elements.

[0051] In addition to the superficial velocity of the gas in the reactor, another factor in the size of the fluidized bed may be the size and amount of openings at the bottom of the fluidized bed to allow the coke particles to move between the beds. To form the fluidized bed, a mesh tray or another type of sufficiently porous support structure may be used to allow the fluidizing gas to pass through the support structure while retaining a substantial majority of the coke particles in the fluidized bed. One or more openings or conduits may be provided in the support structure to allow a portion of the coke particles to fall from the fluidized bed at a higher height to the top of the adjacent bed in an upstream direction. As an example, the size and / or number of openings in the support structure may be changed to vary the size of the fluidized bed at a constant superficial velocity of the fluidizing gas. As another example, if the superficial gas velocity changes due to the conversion of methane to hydrogen, the size and / or number of openings in the support structure may be changed to maintain a constant fluidized bed size.

[0052] Another factor in the size of the fluidized bed can be the size of the reactor. When methane is converted to hydrogen and solid carbon, one mole of methane produces two moles of hydrogen. This corresponds to an increase in gas volume when methane is converted to hydrogen. If larger hydrocarbons are used (such as those present in natural gas), an even larger increase in gas volume can occur. One way to manage the increase in gas volume is to allow for an increase in reactor size in the pyrolysis reaction zone and / or downstream beds. This allows, for example, to maintain a relatively constant superficial gas velocity in the reactor, if desired.

[0053] In various embodiments, the average residence time of the gas stream in the fluidized beds in the pyrolysis zone can vary depending on a variety of factors, including the number of fluidized beds in the pyrolysis zone, the desired net conversion of the feedstock to hydrogen, the temperature in the fluidized beds, the size of the given fluidized bed, and the pressure in the reactor. Examples of suitable residence times can range from 0.1 seconds to 500 seconds, 0.1 seconds to 100 seconds, or 1 second to 100 seconds.

[0054] The flow rate of methane into the second stage fluidized bed can be selected such that the fluidizing gas velocity is greater than the minimum fluidizing velocity of the coke particles in any bed in the series of multiple fluidized beds. The minimum fluidizing velocity of the coke particles can be readily estimated based on the density and particle size of each type of particle, and based on the density and velocity of the fluidizing gas. In some embodiments, the flow rate of the partially converted effluent can be sufficient so that the partially converted effluent can serve as the fluidizing gas for the first stage of the fluidized bed.

[0055] Transport of coke particles One of the challenges in carrying out pyrolysis using a fluidized or moving bed is managing the transport of particles through the system. Unlike fluids, it is usually not feasible to transport particles through the system simply by controlling pressure. To get the particles to flow in the desired manner within the reaction system usually requires one or more of gravity, mechanical assistance, and a transport fluid.

[0056] In various aspects, the systems and methods described herein provide for the transport of coke particles within a pyrolysis reaction system while reducing or minimizing mechanical transport of the particles and while reducing or minimizing the introduction of dilution gases that reduce the amount of pyrolysis products. The improved particle transport achieved herein is made possible in part by the use of multiple continuous fluidized beds.

[0057] In a reactor containing fluidized beds, the movement of coke particles can be controlled based on the support structure of the fluidized bed, the fluidized bed conditions, and gravity. The combination of the support structure and the fluidized bed conditions of each fluidized bed determines the average residence time of the particles in each fluidized bed. This average residence time reflects the average time that the particles stay in the bed before passing through the openings in the support structure and dropping (by gravity) into the adjacent upstream bed.

[0058] Any useful method can be used to recycle or return the coke particles from the bottom bed to the top of the multiple fluidized beds. One example of a suitable method is to use a hydrogen-containing product as a transport gas, and after leaving the first upstream fluidized bed, a portion of the coke particles can be drawn off and transported through a conduit (via gravity) to a pneumatic transport conduit. The gas in the pneumatic transport conduit can be a hydrogen-containing product produced in the pyrolysis reaction system. After pneumatically lifting the coke particles, the coke particles can be separated from the hydrogen-containing product gas, such as by using a cyclone separator. The hydrogen-containing product gas can then be combined with fresh product gas from the reactor for use as a product and / or for use as a transport fluid.

[0059] The use of gravity and pneumatic transport for the movement of coke particles in a reaction system may provide various advantages compared to reaction systems using mechanical transport. For example, a screw feeder is a common device for the movement of solids in a reaction system. Unfortunately, mechanical transport devices such as screw feeders tend to cause particle agglomeration, binding, and / or particle / surface wear in the reaction system. These physical side effects of mechanical particle transport may cause significant variations in particle size, increasing the possibility of equipment damage and / or reduced reliability in operation. However, in some embodiments, mechanical transport of particles may be used to recycle coke particles.

[0060] In some optional embodiments, gases other than the hydrogen-containing product gas can be used as the pneumatic transport gas. For example, nitrogen can be used as the transport gas. The use of an inert transport gas increases the likelihood that diluent gas will enter the reactor and thereby the hydrogen-containing product gas stream. However, such an inert gas is effective for carrying out the pneumatic transport.

[0061] Typical Configuration FIG. 1 shows an example of a general configuration for using electrical heating in an H2-rich environment to provide heating for the thermal decomposition of methane (and / or other hydrocarbons) to produce H2. In FIG. 1, the system for performing the thermal decomposition of methane is depicted as a two-stage system. In the first stage 120, coke particles in a fluidized bed are heated by an electrical heating element 127 to achieve a desired temperature for the thermal decomposition. The heated coke particles 125 are then passed to at least one fluidized bed in the second stage 130. The methane-containing feedstock 101 (and / or other hydrocarbon-containing feedstock) is passed countercurrently to the second stage 130. This thermal decomposition produces a partially converted effluent 135, which is then passed to the first stage 120. The partially converted effluent 135 may have an H2 content of 60% or more by volume, and / or a methane content of 40% or less by volume. Having a hydrogen content of 60% or more by volume allows the gas phase environment in the first stage 120 to correspond to an H2-rich environment. This may reduce or minimize any coke buildup on the electric heating elements 127. The partially converted effluent 135 may then undergo further pyrolysis in the first stage 120 to produce a hydrogen containing output 115. The coke exiting the bottom of the second stage 130 may be returned 160 to the top of the first stage 120 by any useful method.

[0062] FIG. 2 shows an example of a configuration using a continuous fluidized bed to perform the thermal cracking of methane while providing heating using an electric heating element. FIG. 2 shows a reactor 210 including multiple fluidized beds in series. Although the reactor 210 is shown as a single reactor, any useful number of reactors may be used to accommodate the fluidized beds. The reactor 210 includes a first group of fluidized beds including at least one fluidized bed 220 including an electric heating element 227. The first group of fluidized beds may also include one or more fluidized beds 222 that do not include a heating element but can preheat the coke particles based on heat transfer from hot gas passing countercurrently through the bed. The reactor 210 also includes a second group of fluidized beds including at least one fluidized bed 230 at a temperature of 1000° C. or higher to perform the thermal cracking of methane (and / or other hydrocarbons). The second group of fluidized beds may also include one or more additional beds 232 that are at temperatures below 1000° C. but at temperatures of 700° C. or higher to allow some additional pyrolysis to occur. In some embodiments, all of the fluidized beds 220, 222, 230, and 232 may be at a high enough temperature for at least some pyrolysis to occur within each bed. Alternatively, one or more of the fluidized beds 222 and / or 232 may be at a sufficiently low temperature such that substantially no pyrolysis of hydrocarbons occurs.

[0063] In Figure 2, an electric heating element 227 is used to heat the coke particles in the fluidized bed 220 to the desired pyrolysis temperature. Although only a single fluidized bed 220 is shown in Figure 2, in other embodiments, multiple fluidized beds 220 may include electric heating elements.

[0064] In operation, an input gas stream 201, such as a methane or natural gas stream, can enter the reactor 210 at the bottom. The input gas stream 201 can serve as a fluidizing gas for the various fluidized beds as the gas stream rises through them. As the input gas stream 201 travels through the fluidized beds 232 and 230, the input gas stream is heated by the successive fluidized beds to a temperature at which pyrolysis can occur. This results in pyrolysis of at least a portion of the input gas stream into H2, producing a partially converted effluent 235. The pyrolysis also produces solid carbon that is deposited on the coke particles. The partially converted effluent 235 can include 60% or more by volume of H2. The partially converted effluent 235 continues to pass through the fluidized bed 220, where it provides an H2-rich environment for heating of the coke particles in the fluidized bed 220 by the electric heating elements 227. Further conversion of the partially converted effluent may also occur to form product gas stream 215. The product gas stream then continues through fluidized bed 222. Note that further conversion of methane to hydrogen may still occur in the product gas stream as it passes through fluidized bed 222. Product gas stream 215 may be cooled by heat exchange in fluidized bed 222 before exiting the top of reactor 210.

[0065] In operation, the coke particles in the reactor may flow countercurrently to the input gas stream 201, the partially converted effluent 235, and the hydrogen-containing product gas stream 215. In the example shown in FIG. 2, the coke stream 265 is introduced into the top of one or more fluidized beds 222. The coke is preheated by the hydrogen-containing product gas stream 215 in the one or more fluidized beds 222. The coke particles are then further heated by the electric heating elements 227 in the fluidized bed 220 to achieve the desired temperature for pyrolysis. The heated coke is then passed to the fluidized bed 230 for pyrolysis of the feedstock 201. The pyrolysis reaction adds carbon to the coke particles. The hot coke particles then continue into one or more fluidized beds 232 and are cooled by heat exchange with the input gas stream 201.

[0066] After exiting the fluidized bed(s) 232, the cooled coke particles are passed to a reservoir 244. A portion of the coke particles exits the reservoir 244 to form a coke particle stream 250. A portion of the coke particle stream 250 may be withdrawn from the system as a coke product 255. The remainder of the coke particle stream 250 is then recycled back to the top of the reactor. In FIG. 2, this is accomplished using a pneumatic transport conduit 260, with a portion 279 of the hydrogen-containing product gas stream 215 used as a pneumatic transport gas. A compressor or blower 277 may be used to provide sufficient pressure for the portion 279 to function as a pneumatic transport gas. At the top of the conduit 260, the coke particles are separated from a portion 269 of the hydrogen-containing product gas stream in a cyclone separator 262. This forms a coke stream 265. In the example shown in FIG. 2, the portion 269 of the hydrogen-containing product gas stream is combined with the hydrogen-containing product gas stream 215. The hydrogen-containing product gas stream 215 is then used to form a hydrogen product 275 and a pneumatic transport gas stream 279 .

[0067] Further coke processing may also be performed on the coke particles at one or more locations, although this is not shown in FIG. 2. For example, coke processing may include chemical or thermal activation of the coke particles. Additionally or alternatively, coke processing may include particle size distribution management, including removal of oversized coke particles and / or removal of very fine particles. In yet another option, some of the larger particles may be crushed to achieve a desired range of particle size distribution.

[0068] Further embodiments EMBODIMENT 1 A method of carrying out pyrolysis of hydrocarbons to produce H2, the method comprising: heating a first fluidized bed of coke particles in a first fluidized bed stage to a temperature of 1000°C or more using one or more electric heating elements in the first fluidized bed; flowing at least a portion of the coke particles from the first fluidized bed to a second fluidized bed stage containing the coke particles; contacting a hydrocarbon-containing feedstock with the coke particles in the second fluidized bed stage under pyrolysis conditions to produce a partially converted effluent containing H2; and contacting at least a portion of the partially converted effluent with the first fluidized bed stage of coke particles to produce a H2-containing product. The gas environment in the first fluidized bed comprises 60% by volume or more of H2. The second fluidized bed stage comprises a second fluidized bed having a temperature of 1000°C or more.

[0069] EMBODIMENT 2 2. The process of embodiment 1, wherein the partially converted effluent comprises a fluidizing gas for a first fluidized bed of coke particles.

[0070] EMBODIMENT 3 The process of any of the above embodiments, wherein the H2-containing product comprises 80% or more by volume of H2, the partially converted effluent comprises 80% or more by volume of H2, or a combination thereof.

[0071] EMBODIMENT 4 The process of any of the above embodiments, wherein the first fluidized bed stage comprises a plurality of continuous fluidized beds and the partially converted effluent is passed sequentially through each of the fluidized beds of the first fluidized bed stage; the second fluidized bed stage comprises a plurality of continuous fluidized beds and the hydrocarbon-containing feedstock is passed sequentially through each of the fluidized beds of the second fluidized bed stage; or a combination thereof.

[0072] EMBODIMENT 5 The method of any of the above embodiments, wherein the first fluidized bed stage includes one or more additional electric heating elements in the one or more additional fluidized beds, and the gas environment in the one or more additional fluidized beds includes 60% or more H by volume.

[0073] EMBODIMENT 6 The method of any of the above embodiments, wherein the first fluidized bed stage includes at least one fluidized bed that does not include an electric heating element, and the at least one fluidized bed is downstream from the first fluidized bed relative to the flow direction of the partially diverted effluent.

[0074] EMBODIMENT 7 The process of any of the above embodiments, wherein i) the first fluidized bed is heated to a temperature of 1200°C or greater; ii) the second fluidized bed comprises a temperature of 1100°C or greater; iii) the hydrocarbon-containing feedstock is passed through a plurality of continuous fluidized beds in the second fluidized bed stage having a temperature of 1000°C or greater; or iv) a combination of two or more of i), ii), and iii).

[0075] EMBODIMENT 8 The method of any of the above embodiments, further comprising flowing a second portion of the coke particles from the second fluidized bed stage and passing at least a recycle fraction of the second portion of the coke particles to the first fluidized bed stage, wherein the recycle fraction of the second portion of the coke particles comprises a temperature of 700° C. or greater.

[0076] EMBODIMENT 9 The method of embodiment 8, wherein flowing the second portion of the coke particles from the second fluidized bed stage comprises flowing the second portion of the coke particles from the second fluidized bed, or passing at least a recycle fraction of the second portion of the coke particles through the first fluidized bed stage comprises passing at least a recycle fraction of the second portion of the coke particles through the first fluidized bed, or a combination thereof.

[0077] EMBODIMENT 10 The method of embodiment 8 or 9, wherein passing at least the recycle fraction of the second portion of the coke particles to the first fluidized bed stage comprises: pneumatically transporting at least the recycle fraction of the second portion of the coke particles with a pneumatic transport gas; separating at least the recycle fraction of the second portion of the coke particles from the pneumatic transport gas; separating at least a portion of the pneumatic transport gas from the hydrogen-containing effluent prior to pneumatic transport; and combining at least a portion of the pneumatic transport gas with the hydrogen-containing effluent after pneumatic transport.

[0078] EMBODIMENT 11 The process of any of the above embodiments, wherein the first fluidized bed in the first fluidized bed stage is adjacent to the second fluidized bed in the second fluidized bed stage.

[0079] EMBODIMENT 12 The method of any of the above embodiments, wherein a) the hydrocarbon-containing feedstock comprises 95% or more by volume of hydrocarbons; b) the hydrocarbon-containing feedstock comprises methane, natural gas, or a combination thereof; or c) a combination of a) and b).

[0080] EMBODIMENT 13 A system for conducting thermal cracking of hydrocarbons, the system comprising: a first fluidized bed stage comprising a first fluidized bed of coke particles and one or more electric heating elements within the first fluidized bed; a second fluidized bed stage comprising a second fluidized bed of coke particles, the second fluidized bed stage being in fluid communication and particle transport communication with the first fluidized bed stage; a particle recycle loop providing fluid communication between a first upstream fluidized bed in the second fluidized bed stage and a last downstream fluidized bed in the first fluidized bed stage, the particle recycle loop comprising a pneumatic transport conduit; a feed inlet in fluid communication with the second fluidized bed stage; and a product effluent outlet in fluid communication with the first fluidized bed stage.

[0081] EMBODIMENT 14 14. The system of embodiment 13, wherein the first fluidized bed stage comprises multiple fluidized beds, the second fluidized bed stage comprises multiple fluidized beds, the first fluidized bed is adjacent to the second fluidized bed, or a combination thereof.

[0082] EMBODIMENT 15 15. The system of embodiment 13 or 14, wherein the system further comprises a pneumatic transport gas recycle loop in fluid communication between the product effluent outlet and the particle recycle loop, the particle recycle loop and the pneumatic transport gas recycle loop comprising a gas-solid separation stage.

[0083] While the present invention has been described and illustrated with reference to specific embodiments, those skilled in the art will recognize that variations suitable for the present invention may not necessarily be illustrated herein, and therefore, reference should then be made solely to the appended claims for purposes of determining the true scope of the present invention.

Claims

1. Pyrolysis of hydrocarbons is carried out to produce H ２ 1. A method for producing heating the first fluidized bed of coke particles in a first fluidized bed stage to a temperature of 1000° C. or greater using one or more electric heating elements in the first fluidized bed; flowing at least a portion of the coke particles from the first fluidized bed to a second fluidized bed stage containing the coke particles; Contacting the coke particles with a hydrocarbon-containing feedstock in the second fluidized bed stage under pyrolysis conditions to produce H ２ producing a partially converted effluent comprising: A first fluidized bed stage of coke particles is contacted with at least a portion of the partially converted effluent to produce H ２ Producing a containing product Including, The gas environment in the first fluidized bed is 60% by volume or more of H ２ Including, the second fluidized bed stage comprises a second fluidized bed having a temperature of 1000° C. or greater; The hydrocarbon-containing feedstock optionally comprises: a) 95% or more by volume of hydrocarbons; b) methane, natural gas, or a combination thereof; or c) A combination of a) and b) Including, The process wherein the partially converted effluent optionally comprises a fluidizing gas for a first fluidized bed of coke particles.

2. H ２ The product contains 80% or more by volume of H ２ Contains or The partially converted effluent is 80% by volume or more of H ２ Contains or Combinations of these The method of claim 1, wherein

3. the first fluidized bed stage comprises a plurality of successive fluidized beds and the partially diverted effluent is passed sequentially through each fluidized bed of the first fluidized bed stage; the second fluidized bed stage comprises a plurality of successive fluidized beds and the hydrocarbon-containing feed is passed sequentially through each fluidized bed of the second fluidized bed stage; or Combinations of these The method according to claim 1 or 2,

4. the first fluidized bed stage comprises one or more additional electric heating elements in one or more additional fluidized beds; The gas environment in one or more additional fluidized beds is at least 60% by volume of H ２ The method according to any one of claims 1 to 3, comprising:

5. the first fluidized bed stage comprises at least one fluidized bed that does not include an electric heating element; The process according to any one of claims 1 to 4, wherein at least one fluidized bed is downstream from the first fluidized bed relative to the flow direction of the partially diverted effluent.

6. i) the first fluidized bed is heated to a temperature of 1200°C or greater; ii) the second fluidized bed has a temperature of 1100°C or greater; iii) the hydrocarbon-containing feedstock is passed through a plurality of continuous fluidized beds having a temperature of 1000° C. or greater in the second fluidized bed stage; or iv) a combination of two or more of i), ii), and iii). The method according to any one of claims 1 to 5, wherein

7. flowing the coke particles from the second fluidized bed stage; and passing at least a recycle fraction of the coke particles from the second fluidized bed stage to the first fluidized bed stage. Further comprising: The process according to any one of claims 1 to 6, wherein the recycle fraction of coke particles from the second fluidized bed stage has a temperature of 700°C or higher.

8. Passing at least a recycle fraction of the coke particles from the second fluidized bed stage to the first fluidized bed stage, pneumatically conveying at least a recycle fraction of the coke particles from the second fluidized bed stage with a pneumatic conveying gas; separating at least a recycle fraction of the coke particles from the second fluidized bed stage from the pneumatic transport gas; separating at least a portion of the pneumatic transport gas from the hydrogen-containing effluent prior to pneumatic transport; and combining the hydrogen-containing effluent with at least a portion of the pneumatic transport gas after pneumatic transport; The method of claim 7, comprising:

9. 1. A system for conducting thermal cracking of hydrocarbons, comprising: a first fluidized bed stage comprising a first fluidized bed of coke particles and one or more electric heating elements within the first fluidized bed; a second fluidized bed stage comprising a second fluidized bed of coke particles; a particle recycle loop providing fluid communication between the first upstream fluidized bed in the second fluidized bed stage and the final downstream fluidized bed in the first fluidized bed stage; a feed inlet in fluid communication with the second fluidized bed stage; and a product effluent outlet in fluid communication with the first fluidized bed stage; Equipped with a second fluidized bed stage in fluid and particle transport communication with the first fluidized bed stage; the particle recycle loop comprises a pneumatic transport conduit; The system further comprises a pneumatic transport gas recycle loop in fluid communication between the product effluent outlet and the particle recycle loop.

10. The system of claim 9, wherein the particle recycle loop and the pneumatic conveyed gas recycle loop are provided with a gas-solid separation stage.

Images