Patent Application
20230356175
In the past, micro- and meso-channel units requiring heat have either incorporated fluid passages that transport a preheated fluid or create heat within the passage—such as through an exothermic chemical reaction—or they have received heat through external walls of the unit. Inducing the heat to be generated within and/or in close proximity to the channels requiring heating is advantageous since it reduces the volume needed for alternate channels and also reduces the heat transfer inefficiency/irreversibility of conducting heat through the structure of the unit, resulting in a system that is process intensive and thermodynamically more efficient than alternatives.
The three patent documents discussed below are incorporated by reference in full, including definitions for terms used herein.
U.S. Pat. No. 9,950,305, entitled “Solar thermochemical processing system and method,” presents the design of a micro-/meso-channel reactor that uses concentrated solar energy to drive high temperature chemical reactions, such as methane steam reforming or the reverse-water gas shift reaction. The reactor itself is a pancake-shaped unit where reactants are transported through radial channels from the center of the reactor disk to the edges, then back again through additional heat exchange channels that flow in a counterflow direction to the reaction channels. Heat is added to the system for the endothermic reaction by directing the radiant energy from a parabolic dish concentrator.
US Published Patent Application US20200298197 entitled “Reactor Assemblies and Methods of Performing Reaction,” presents the design of an improved micro-/meso-channel reactor where the outward-flowing reaction channels are configured in a curved or spiral arrangement and/or the inward flowing heat exchange channels are configured in a similar arrangement achieving counter-cross flow operation. The major improvement in the system is that the channels spread heat in a substantially more effective manner than the reactor in the first patent document, thereby mitigating nonuniform heat from the dish concentrator, reducing the magnitude of hot spots on the reactor surface and their potential negative impact on fluid flow distribution within the reactor.
US Published Patent Application US20200001265 entitled “Enhanced Microchannel or Mesochannel Devices and Methods of Additively Manufacturing the Same,” presents 3D methods of printing micro- and meso-channel reactors, including design improvements that are enabled by 3D printing, also called additive manufacturing. 3D printing provides advantages for micro- and meso-channel units, including the opportunity to vary the magnetic properties of the structure by varying the composition of the metal powder or by inserting structures (e.g., flux concentrators) as the unit is printed. This is especially intriguing as it allows one to design structures that direct and/or concentrate an alternating Electromagnetic Field (EMF) to points of interest—including the use of constructive or destructive interference—so that heat is preferentially provided to portions of the structure. This patent application describes the combination of the counter-cross flow design from the second patent document with the methods of the third patent document, further combined and adapted to efficiently incorporate inductive heating as is presented in this provisional patent application.
The invention provides methods, systems, and apparatus for inductively heating micro- and meso-channel reactors, heat exchangers, vaporizers, and separations units.
The method comprises of inducing an alternating electromagnetic field within the micro- or meso-channel device, creating eddy currents, which produce heat through joule heating. If the material being heated is ferromagnetic, heat is also generated through magnetic hysteresis losses. In a simple version, it is similar to cooktop stove inductive heaters, but in more effective units it preferentially directs heat to fluid channels where the heat is needed.
The invention also provides a chemical transformer. A chemical transformer is analogous to an electrical transformer in that it connects to a gas grid (e.g., the natural gas grid) and perhaps an electrical grid, and performs transformations that enable better transmission and distribution, storage or use of the molecules that are the subject of the gas grid. When connected to an electrical grid it also converts electrical energy (kWh) to chemical energy (kWh) which can subsequently be restored to electrical energy in fuel cells or other power generators, thus providing a convenient means of energy storage. The chemical transformer is a process-intensive, chemical process plant that gains efficiency and productivity advantages through the inclusion of micro- and meso-channel reactors, heat exchangers and separators, thus gaining a reduced volume and footprint compared to conventional energy conversion and chemical process technologies. It also gains advantages by being mass-producible and available to be placed near the point where the chemical products are needed
The invention includes any of the components, methods of making or assembling apparatus, kits that can be assembled to make apparatus, or methods or systems described above. Systems may include both solid components as well as fluids and any selected conditions (temperatures, pressures, electric or magnetic fields, etc.) within or around the solid components. The invention may include systems or methods of converting or otherwise changing the physical properties of chemicals or chemical compounds. The components or apparatus can be any combination of the components described here. The invention can be alternatively or additionally be described in terms of properties, for example possessing at least the values described here, or within ±10%, or ±20%, or ±30%.
In one aspect, the invention provides a chemical processor, comprising: a process layer having a top wall that is adapted to heat in response to an alternating magnetic field, a bottom wall opposite the top wall, and side walls disposed between the top and bottom walls; the process layer comprising a channel adapted for fluid flow and an inlet and outlet adapted for fluid flow into and out of the process layer; a heat transfer layer adjacent the bottom wall of the process layer; the heat transfer layer having a top wall, a bottom wall opposite the top wall, and side walls disposed between the top and bottom walls; the heat transfer layer comprising a channel adapted for fluid flow and an inlet and an outlet such that a fluid can flow into and out of the heat transfer layer; wherein the outlet of the process layer is connected to the inlet of the heat transfer layer such that a fluid can flow out of the process layer and into the heat transfer layer; wherein the bottom wall of the process layer is the top wall of the heat transfer layer or where the walls are in thermal contact; and an inductor configured to generate an alternating magnetic field in the top wall of the process layer.
The invention may be further characterized by one or any combination of the following: wherein the process layer comprises a plurality of microchannels or mesochannels; wherein heat transfer layer comprises a plurality of microchannels or mesochannels; wherein, during operation, flow in the heat transfer layer is counter to the direction of flow in the process layer; wherein flow is cross flow such that the plurality of microchannels or mesochannels in the heat transfer layer overlap with the plurality of microchannels or mesochannels in the process layer such that the channels cross, so that flow is both counter-flow and cross-flow; wherein the inductor is a pancake induction coil, or a toroidal induction coil; further comprising an induction enhancer; further comprising an induction susceptor placed within the process channel; wherein the top wall is ferrimagnetic or ferromagnetic at room temperature; wherein the top wall is paramagnetic at room temperature; further comprising a recuperative heat exchanger in which the process stream flowing toward the process layer is heated by a product stream flowing away from the heat transfer layer; wherein the top wall comprises a plurality of induction enhancers joined to a surface of the top wall by a metallic braze; wherein the plurality comprises at least 20 pieces of induction enhancers; wherein the use of a plurality of enhancers prevents or reduces damage due to expansion mismatch between the enhancer and processor wall. The invention also includes a chemical transformer comprising the apparatus described herein.
In another aspect, the invention provides a method of conducting an endothermic chemical process, comprising: passing a process stream into an apparatus comprising: a process layer having a top wall that is adapted to heat in response to an alternating magnetic field, a bottom wall opposite the top wall, and side walls disposed between the top and bottom walls; the process layer comprising a channel adapted for fluid flow and an inlet and outlet adapted for fluid flow into and out of the process layer; the process stream flowing through the channel of the process layer; a heat transfer layer adjacent the bottom wall of the process layer; the heat transfer layer having a top wall, a bottom wall opposite the top wall, and side walls disposed between the top and bottom walls; the heat transfer layer comprising a channel adapted for fluid flow and an inlet and an outlet such that a fluid can flow into and out of the heat transfer layer; passing a heat transfer fluid flowing through the channel of the heat transfer layer; wherein the bottom wall of the process layer is the top wall of the heat transfer layer or where the walls are in thermal contact; wherein heat transfers between the heat transfer fluid in the heat transfer channel and the process stream in the process channel; and generating an alternating magnetic field in the top wall of the process layer via an inductor; wherein the top wall is heated by the alternating magnetic field and heat from the top wall transfers into the process stream.
The invention may be further characterized by one or any combination of the following: wherein the outlet of the process layer is connected to the inlet of the heat transfer layer; wherein the heat transfer layers comprises a plurality of microchannels or plurality of mesochannels, wherein the process stream flows out of the process layer and into the plurality of microchannels or plurality of mesochannels of the heat transfer layer; wherein the endothermic chemical process is a chemical reaction; wherein the chemical process is a chemical reaction; wherein the chemical process is a catalytic chemical reaction; wherein the chemical reaction comprises a reforming reaction or a reverse-water-gas shift reaction; wherein the endothermic chemical process comprises vaporizing the product stream; further comprising a step of exchanging heat between the process stream, prior to entering the process layer, and a product stream that has left the heat exchange layer; wherein the endothermic chemical process comprises a chemical separation; wherein the chemical separation comprises distillation or sorption; wherein the heat transfer fluid comprises the reaction products of a chemical reaction in the process layer; wherein the alternating magnetic field alternates at a frequency between 1 and 100 kHz; and/or wherein the alternating magnetic field alternates at a frequency between 1 and 50 kHz.
In another aspect, the invention provides a chemical processing system, comprising: a process layer having a top wall that is adapted to heat in response to an alternating magnetic field, a bottom wall opposite the top wall, and side walls disposed between the top and bottom walls; the process layer comprising a channel adapted for fluid flow and an inlet and outlet adapted for fluid flow into and out of the process layer; a process stream flowing through the channel of the process layer; a heat transfer layer adjacent the bottom wall of the process layer; the heat transfer layer having a top wall, a bottom wall opposite the top wall, and side walls disposed between the top and bottom walls; the heat transfer layer comprising a channel adapted for fluid flow and an inlet and an outlet such that a fluid can flow into and out of the heat transfer layer; a heat transfer fluid flowing through the channel of the heat transfer layer; wherein the bottom wall of the process layer is the top wall of the heat transfer layer or where the walls are in thermal contact; wherein heat transfers between the heat transfer fluid in the heat transfer channel and the process stream in the process channel; and an inductor to generate an alternating magnetic field in the top wall of the process layer; wherein the top wall is heated by the alternating magnetic field and heat from the top wall transfers into the process stream.
The invention may be further characterized by one or any combination of the following: wherein the outlet of the process layer is connected to the inlet of the heat transfer layer; wherein the heat transfer layers comprises a plurality of microchannels or plurality of mesochannels, wherein the process stream flows out of the process layer and into the plurality of microchannels or plurality of mesochannels of the heat transfer layer; wherein the system energy efficiency is greater than 50% (in some embodiments 50 to about 90% or 50 to about 70%), based on the ratio of the net increase in energy content of the fluids to the consumed electrical energy, times 100%; wherein the system chemical efficiency is greater than 70% (in some embodiments 70 to about 90% or 70 to about 80%), based on the ratio of the net increase in higher heating value of the fluids to the consumed electrical energy, times 100%.
In a further aspect, the invention provides a toroidal chemical processor, comprising: a toroidal-shaped processor defined by toroidal-shaped reactor wall adapted to heat in response to an alternating magnetic field and comprising an inductor coil disposed around the toroidal-shaped reactor wall; a chemical processing channel disposed inside the toroidal-shaped reactor wall; and the chemical processing channel comprising an inlet and an outlet. The toroidal reactor may comprise any of the features described herein for an inductively heated processor. For example, the toroidal reactor may further comprise a heat transfer channel adjacent to the chemical processing channel. In some embodiments, the chemical processing channel comprises a plurality of channels that extend radially from near the central axis to near the periphery of the toroid. The invention also includes methods of conducting an endothermic unit operation in a toroidal reactor. The invention also includes systems comprising compositions and conditions in a toroidal reactor.
In another aspect, the invention provides a pancake-shaped chemical processor, comprising in order: a first pancake-shaped inductor configured to generate an alternating magnetic field in the top wall of the first process layer; a first process layer having a top wall that is adapted to heat in response to an alternating magnetic field, a bottom wall opposite the top wall, and side walls disposed between the top and bottom walls; the process layer comprising a channel adapted for fluid flow and an inlet and outlet adapted for fluid flow into and out of the process layer; a heat transfer layer adjacent the bottom wall of the first process layer; the heat transfer layer having a top wall, a bottom wall opposite the top wall, and side walls disposed between the top and bottom walls; the heat transfer layer comprising a channel adapted for fluid flow and an inlet and an outlet such that a fluid can flow into and out of the heat transfer layer; wherein the bottom wall of the first process layer is the top wall of the heat transfer layer or where the walls are in thermal contact; a second process layer having a bottom wall that is adapted to heat in response to an alternating magnetic field, a top wall opposite the bottom wall, and side walls disposed between the top and bottom walls; the second process layer comprising a channel adapted for fluid flow and an inlet and outlet adapted for fluid flow into and out of the process layer; wherein the top wall of the second process layer is the bottom wall of the heat transfer layer or where the walls are in thermal contact; and a second pancake-shaped inductor configured to generate an alternating magnetic field in the bottom wall of the second process layer.
The pancake-shaped reactor may comprise any of the features described herein for an inductively heated processor. For example, the pancake-shaped reactor may further comprise, in the process layer and heat transfer layer comprise channels that radiate from a central axis, and/or where the process layers and the heat transfer layers comprise channels are configured for counter-cross flow heat exchange. The invention also includes methods of conducting an endothermic unit operation in a pancake-shaped reactor. The invention also includes systems comprising compositions and conditions in a pancake-shaped reactor.
In a further aspect, the invention provides a method of passively controlling the temperature of an inductively heated endothermic unit operation, comprising: heating a receiving body of a chemical processor by applying an alternating magnetic field from an inductor; wherein the receiving body is ferrimagnetic or ferromagnetic at room temperature; wherein a process stream is heated by the receiving body; wherein the receiving body comprises a Curie temperature; wherein a temperature of the process stream approaches within at least 50° C. of the Curie temperature and wherein, as a result of approaching within at least 50° C. of the Curie temperature, the magnetic susceptibility of the receiving body to the chemical reactants is reduced by at least 10% or by at least 20%. In this description, magnetic susceptibility refers to volume magnetic susceptibility. The endothermic unit operation may comprise endothermic reactions, separations, and/or vaporization. In some preferred embodiments, the chemical reactants reach the Curie temperature and wherein, as a result of reaching the Curie temperature, heat transfer from the receiving body to the chemical reactants is reduced. The “receiving body” means a ferrimagnetic and ferromagnetic material and includes susceptors and induction enhancers, In some preferred embodiments, the receiving body is a cladding or insert disposed in the process channel.
In another aspect, the invention provides a method of passively controlling the temperature of an inductively heated chemical reaction, comprising: heating a receiving body of a chemical reactor by applying an alternating magnetic field from an inductor; wherein the receiving body is ferrimagnetic or ferromagnetic at room temperature; wherein chemical reactants are heated by the receiving body; wherein the receiving body comprises a Curie temperature; wherein the chemical reactants reach the Curie temperature and wherein, as a result of reaching the Curie temperature, heat transfer from the receiving body to the chemical reactants is reduced.
In another aspect, the invention provides a chemical transformer, comprising: a plurality of steam reformers; a plurality of recuperative heat exchangers; wherein the plurality of steam reformers and plurality of recuperative heat exchangers are disposed in a half-hexagonal or half cylindrical housing or hexagonal housing that is openable to form half hexagons or cylindrical housing that is openable to form half cylinders. In the context of this aspect, the terms hexagonal and cylindrical do not require exact geometric dimensions, but are identifiable shapes that allow the assembly to be transported and opened for access during setup, maintenance or repair. In an preferred embodiment, the chemical transformer comprises the components: a plurality of steam methane reformers; a plurality of recuperative heat exchangers; a water-gas shift reactor; a steam generator; and a water condenser heat exchanger; wherein all of the components are disposed in a half-hexagonal or half cylindrical housing or hexagonal housing that is openable to form half hexagons or cylindrical housing that is openable to form half cylinders. The invention includes methods of producing hydrogen comprising passing a hydrocarbon into the transformer.
In another aspect, the invention provides a chemical transformer system, comprising: a plurality of steam reformers comprising a catalyst and a stream containing steam and a hydrocarbon; a plurality of recuperative heat exchangers comprising hydrogen; wherein the plurality of steam reformers and plurality of recuperative heat exchangers are disposed in a half-hexagonal or half cylindrical housing or hexagonal housing that is openable to form half hexagons or cylindrical housing that is openable to form half cylinders. In the context of this aspect, the terms hexagonal and cylindrical do not require exact geometric dimensions, but are identifiable shapes that allow the assembly to be transported and opened for access during setup, maintenance or repair.
The apparatus, methods and systems comprising chemical transformers may, in various embodiments, comprise one or any combination of the combinations, structural features, and/or conditions described herein.
In a further aspect, the invention provides a method for servicing the chemical transformer, wherein the chemical transformer is disposed in a hexagonal housing or a cylindrical housing, comprising: opening the hexagonal housing or cylindrical housing to form two half hexagon housings or two half cylinder housings each having an open face, and reaching into the open face of the housing to access a component of the chemical transformer.
In another aspect, the invention includes cyclic processes, like thermal swing adsorption and thermally-enhanced, or pressure swing adsorption. For example, where induction heat is used to drive the desorption step in the process layer and, in another step in the cycle, heat is removed from the process layer by a cooler fluid in the heat transfer layer. Yet another case is thermochemical water-splitting, where high temperature steam is introduced to a metallic material in the process channel, forming a metal oxide and producing hydrogen, with heat from this exothermic process being removed by a cooler fluid or an endothermic reaction in the heat exchange layer, and then in another step in the cycle induction heating increases the temperature of the metal oxide sufficiently to drive off the oxygen. The inclusion of multiple cells like this, acting out of phase but in a coordinated manner, allows more efficient thermal operation
As is standard patent terminology, “comprising” means “including” and neither of these terms exclude the presence of additional or plural components. In alternative embodiments, the term “comprising” can be replaced by the more restrictive phrases “consisting essentially of” or “consisting of” A “microchannel” is a channel having at least one internal dimension (wall-to-wall, not counting catalyst) of 1 mm or less, and greater than 1 μm (preferably greater than 10 μm), and in some embodiments 50 to 500 μm; preferably a microchannel remains within these dimensions for a length of at least 1 cm, preferably at least 10 cm. In some embodiments, in the range of 5 to 100 cm in length, and in some embodiments in the range of 10 to 60 cm. Microchannels are also defined by the presence of at least one inlet that is distinct from at least one outlet. Microchannels are not merely channels through zeolites or porous materials. The length of a microchannel corresponds to the direction of flow through the microchannel. Microchannel height and width are substantially perpendicular to the direction of flow of through the channel. Mesochannels are similarly defined except having an internal dimension of 1 mm to 1 cm. Typically, devices comprise multiple micro- or mesochannels that share a common header and a common footer. Although some devices have a single header and single footer; a microchannel device can have multiple headers and multiple footers. The volume of a channel or manifold is based on internal space. Channel walls are not included in the volume calculation. Catalyst can be in the form of particulate or in the form of a porous solid such as a wall coating or a porous body that is inserted into a reaction channel (a “catalyst insert”). In the present invention, the support of a catalyst insert can be a material that heats in the presence of an alternating magnetic field. Particulate refers to particles such as catalyst particles that fit within a micro- or mesochannel. Preferably, the particles (if present) have a size (largest dimension) of 2 mm or less, in some embodiments, 1 mm or less. Particle size can be measured by sieves or microscopy or other appropriate techniques. For relatively larger particles, sieving is used. The particulate may be catalyst, adsorbent, or inert material.
In some preferred configurations, the catalyst (either for steam reforming or other chemical reactions) includes an underlying large pore substrate. Examples of preferred large pore substrates include commercially available metal foams and, more preferably, metal felts. Prior to depositing any coatings, a large pore substrate has a porosity of at least 5%, more preferably 30 to 99%, and still more preferably 70 to 98%. In some preferred embodiments, a large pore substrate has a volumetric average pore size, as measured by BET, of 0.1 μm or greater, more preferably between 1 and 500 μm. Preferred forms of porous substrates are foams and felts and these are preferably made of a thermally stable and conductive material, preferably a metal such as stainless steel or FeCrAlY alloy. These porous substrates can be thin, such as between 0.1 and 1 cm. Foams are continuous structures with continuous walls defining pores throughout the structure. Alternatively, the catalyst may take any conventional form such as a powder or pellet.
A catalyst with a large pores preferably has a pore volume of 5 to 98%, more preferably 30 to 95% of the total porous material's volume. Preferably, at least 20% (more preferably at least 50%) of the material's pore volume is composed of pores in the size (diameter) range of 0.1 to 300 microns, more preferably 0.3 to 200 microns, and still more preferably 1 to 100 microns. Pore volume and pore size distribution are measured by mercury porisimetry (assuming cylindrical geometry of the pores) and nitrogen adsorption. As is known, mercury porisimetry and nitrogen adsorption are complementary techniques with mercury porisimetry being more accurate for measuring large pore sizes (larger than 30 nm) and nitrogen adsorption more accurate for small pores (less than 50 nm). Pore sizes in the range of about 0.1 to 300 microns enable molecules to diffuse molecularly through the materials under most gas phase catalysis conditions. A catalyst insert preferably has a height of 1 cm or less, in some embodiments a height and width of 0.1 to 1.0 cm. In some embodiments, the porous insert occupies at least 60%, in some embodiments at least 90%, of a cross-sectional area of a microchannel. In an alternative preferred embodiment, the catalyst is a coating (such as a washcoat) of material within a reaction channel or channels.
In many embodiments, the inductor provides heat to a heterogeneous catalyst for the endothermic steam methane reforming reaction. Other endothermic processes are also anticipated including other endothermic chemical reactions, such as dry reforming of methane with CO2 or the reverse water gas shift reaction. Preferably, the heat exchange function achieves a temperature trajectory down the length of the reaction channel that encourages greater chemical conversion. Other examples are sorption processes for heat pumps or chemical separations. For example, solar heat pumps transfer heat from a lower temperature to a hotter temperature using absorption (liquid solvent) or adsorbent (solid sorbent) heat pump cycles. An example is replacing the catalyst in the above invention with a solid sorbent that adsorbs refrigerant at low temperature and pressure and desorbs at higher temperature and pressure using solar energy. Applications include building heating ventilation and air condition (HVAC) and refrigeration. Similarly, the sorbent can be used for chemical separations in a thermal swing adsorption (TSA) process or a thermally-enhanced, pressure swing adsorption (PSA) process. One application would be capturing carbon dioxide from the atmosphere, from syngas production systems such as the H2 production/steam reforming application described herein, power plant effluents, or other potential sources.
Catalyzed chemical reactions are very well known and appropriate conditions and catalyst are very well known and do not need to be described here; it is sufficient to identify catalysts as reforming catalysts, or Sabatier catalysts (commonly Ni or Ru/Al2O3), ammonia synthesis (commonly Ru, or iron oxide, or Co—Mo—N), or reverse-water-gas shift reaction (common catalysts comprise oxides of iron, chromium, and optionally magnesium).
In some preferred embodiments, the invention converts methane or other alkane or mix of hydrocarbons to hydrogen by steam or dry reforming. A steam reforming process requires a hydrocarbon (or hydrocarbons) and steam (H2O). A reactant mixture can include other components such as CO or nonreactive diluents such as nitrogen or other inert gases. In some preferred processes, the reaction stream consists essentially of hydrocarbon and steam. In some preferred embodiments, the steam to carbon ratio in a reactant stream is 3 to 1 to 1 to 1, and in some embodiments 1.5 to 1 or less. Hydrocarbons include: alkanes, alkenes, alcohols, aromatics, and combinations thereof. A hydrocarbon can be natural gas. Preferred alkanes are C1-C10 alkanes, such as methane, ethane, propane, butane, and isooctane. A steam reforming catalyst preferably comprises one or more of the following catalytically active materials: ruthenium, rhodium, iridium, nickel, palladium, platinum, and combinations thereof. Rhodium is particularly preferred. In some preferred embodiments, the catalyst (including all support materials) contains 0.5 to 10 weight percent Rh, more preferably 1 to 3 wt % Rh. The catalyst may also contains an alumina support for the catalytically active materials. An “alumina support” contains aluminum atoms bonded to oxygen atoms, and additional elements can be present. Preferably, the alumina support comprises stabilizing element or elements that improve the stability of the catalyst in hydrothermal conditions. Examples of stabilizing elements are Mg, Ba, La, and Y, and combinations of these. Preferably, the catalytically active materials (such as Rh) are present in the form of small particles on the surface of an alumina support. The steam reforming reaction is preferably carried out at more than 400° C., more preferably 500-1000° C., and still more preferably 650-900° C. The reaction can be run over a broad pressure range from sub-ambient to very high, in some embodiments the process is conducted at a pressure of from 10 atm to 30 atm, more preferably 12 atm to 25 atm. The H2O partial pressure is preferably at least 0.2 atm, in some embodiments at least 2 atm, and in some embodiments in the range of 5 atm to 20 atm.
A channel containing a catalyst is a reaction channel. More generally, a reaction channel is a channel in which a reaction occurs. Reaction channel walls are preferably made of an iron-based alloy such as steel, or a Ni-, Co- or Fe-based superalloy such as Haynes. The choice of material for the walls of the reaction channel may depend on the reaction for which the reactor is intended. In some embodiments, the reaction chamber walls are comprised of a stainless steel or Inconel® which is durable and has good thermal conductivity. Typically, reaction channel (typically, tube) walls are formed of the material that provides the primary structural support for the microchannel apparatus.
The invention also includes methods of conducting unit operations within the apparatus described herein.
“Unit operation” means chemical reaction, vaporization, compression, chemical separation, distillation, condensation, mixing, heating, or cooling. A “unit operation” does not mean merely fluid transport, although transport frequently occurs along with unit operations. In some preferred embodiments, a unit operation is not merely mixing.
Heat exchange fluids may flow through heat transfer channels (preferably micro- or mesochannels) adjacent to process channels (preferably reaction micro- or mesochannels), and can be gases or liquids or biphasic materials and in preferred embodiments, the heat exchange fluid is a product stream used to recuperate heat generated in the reaction channel.
Flux concentrators improve the electromagnetic coupling between the wall surface and the current-carrying region of the inductor. Typically, flux concentrators are ferromagnetic materials.
Induction enhancer is a material or a combination of materials that is affixed to or placed in close proximity a region of a chemical processor (preferably the micro- or meso- process channels) to be heated by induction. The enhancer includes at least one ferromagnetic material at the desired temperature of the process.
A “thermochemical processor” is an apparatus or component of a system in which a process stream is subjected to a thermochemical process such as a reaction (such as steam reforming), separation, or vaporization. At least a portion of the process stream undergoes a chemical reaction, change of state, or change of purity or concentration. In embodiments of the invention where induction heating is used, the process is endothermic or comprises an endothermic phase.
) and chemical efficiency of converting power to higher heating value of the product gas (
) with the new copper-silver braze material.
) and chemical efficiency of converting power to higher heating value of the product gas (
) with circular segments of cobalt-iron sheet attached with copper-silver braze material.
Chemical reactors for reactions that are conducted at high temperature, such as methane steam reforming, need to be built of materials that can withstand high temperatures and thermal expansion at varying temperatures. Typically, these reactors are made of high temperature superalloys such as Haynes 282. Haynes 282 is believed to be, at best, weakly paramagnetic, with a relative magnetic permeability that is close to 1, which is the relative magnetic permeability of a vacuum. This means that Haynes will not provide very much intensification of the magnetic field on its own. We have found that some commercial induction cooktop heaters refuse to turn on with Haynes 282 or Inconel 625 as their internal sensors do not register an acceptable receiver material. However, some others, with different electronics and, presumably, different detection algorithms, do not refuse to turn on and, with some effort, we have been successful in gaining high heating rates with Haynes 282. It was believed by some experts that Haynes 282 would be more difficult to inductively heat than aluminum, which has very low resistivity and therefore does not provide sufficient Joule Heating. Surprisingly, however, we found that that Haynes 282 heats in a suitable alternating magnetic field. In addition, we found that the use of an induction enhancer provides an additional coupling advantage such that all of the tested induction heaters operated effectively and allowed us to move the process unit further from the pancake inductor; thus enabling a high temperature reaction without damaging the pancake inductor.
The addition of inductive heating to a solar-heated chemical process unit, thus producing a solar-electric hybrid, can create a substantial productivity advantage for a solar thermal or thermochemical process which otherwise might be limited by the intermittent availability of sunlight. In addition, it allows standalone operation with no solar concentrator or other source of heat.
In induction energy transfer, the current that is generated within the receiving unit—for example, a secondary coil of an electrical transformer or a reactor to be heated—is equal to the ratio of the number of turns in the primary to the number of turns in the secondary. In most cases, the effective number of turns in a micro- or meso-channel unit can be taken to be 1—the structure acts like a secondary coil where the wires are shorted out—the ratio (n-ratio) is equal to the number of turns in the primary. The voltage, frequency, and number of turns in the primary are selected or varied to achieve the desired energy transfer and depth of penetration needed in the reaction device.
The relative magnetic permeability of the material used in reactor components determines the inductive reactance of the system. Materials with high relative magnetic permeability (e.g., ferromagnetic materials) will attract and exhibit greater concentrations of magnetic flux, and magnetic energy, than materials of low relative magnetic permeability (e.g., paramagnetic materials). Placing, plating, cladding, or doping the base metal of the receiver with a ferromagnetic or paramagnetic material, or simply placing a ferromagnetic or paramagnetic material within the receiver, can be used to create the desired heating effect where the receiver material does not couple well with the induction coil. Varying the depth of placement, cladding, plating, or doping, or the location of inserts, may be used to further concentrate the heating effects to specific regions or components of the receiver.
Multiple induction coils, with varying wire sizes and coil geometries may be used simultaneously (connected in parallel or in series) to create the desired heat flux characteristic in the reactor. Higher flux can be achieved by stacking coils to increase the ratio of the number of turns in the primary induction coil to the secondary reactor. Conversely, lower flux concentrations can be achieved by changing the spacing of the wires. The approximately concentric rings that are characteristic of a flat induction coil (primary windings) can be modified into different geometries such as squares, hexagons, octagons, or irregular shapes so long as the concentric rings have an open center to minimize the interference and cancellation of electromagnetic fields caused by adjacent wires with opposite current flow directions. The size of the wire can be varied to increase the number of turns, to increase the power density and to accommodate the induction frequency.
Heat is generated in the receiver when alternating current is passed through the coil (320). The frequency of the alternating current plus the properties of the receiver determine the depth of penetration into the metal structure of the reactor; lower frequencies produce deeper heating. The frequency of the induction coil therefore may be anywhere from a few hertz to many kHz or even megahertz. However, the heating power is proportional to the frequency and the n-ratio. Higher induction frequencies require fewer turns. However, as will be noted below, lower frequencies allow greater penetration of electromotive force (EMF) energy into the receiver (the secondary) and therefore will provide deeper heating and lower surface temperatures. Optimization therefore does not always favor higher frequencies.
The picture on the left in
The degree of thermal penetration within the reactor (300) is a function of the frequency of the electrical power, and the relative magnetic permeability and the electrical resistivity of the reactor structure. In general, greater thermal penetration is enabled by low frequencies and more shallow thermal penetration is produced with higher frequencies. For materials like Haynes 230 and 282, which are at best weak paramagnetic materials and are not ferromagnetic, frequencies around 50-60 Hz (the frequency of the commercial electrical grid) will support thermal penetration of several centimeters (cm); at 400 Hz (the frequency of power electronics in common commercial aircraft) thermal penetration is reduced. At frequencies of a few tens of kHz, thermal penetration will be measured in mm.
Materials with low electrical resistivity (like copper or aluminum) do not heat well through induction. High frequencies in materials like Haynes 230 or 282 may induce heat just a few (or several) millimeters into the surface, supporting efficient heat transfer through the device by conduction or convection to heat a working fluid, a chemical reaction or a separation operation, such as desorption from a solid adsorbent. These limitations are managed by selectively varying frequency and geometry of the induction coils, by using flux concentrators, and/or by plating, cladding and doping reactor components.
Flux concentrators may be installed during the 3D printing operation, within channels after 3D printing has occurred, or during other fabrication steps. The flux concentrators may be an integral portion of the structure (for example, if they are built in during a 3D print operation) or non-structural (for example, as a material that is inserted within the fecralloy foam in which catalyst material is also inserted). One characteristic of a fecralloy material in which the catalyst is deposited is that it is ferromagnetic but has a Curie Temperature of around 600° C. Therefore, it loses its ferromagnetic properties (and becomes paramagnetic) as it approaches and surpasses that temperature. For reactions and other unit operations requiring higher temperatures, a different material than FeCralloy may be utilized in order to have embedded flux concentrators; however, the FeCralloy can still provide support to preheating the structure during startup. Alloys such as cobalt-iron (FeCo) or aluminum, nickel and cobalt (AlNiCo)— have higher Curie temperatures, ranging from about 800° C. to over 900° C., with ferromagnetic properties starting to decline at slightly colder temperatures. As those skilled in the art know, steam-methane reforming proceeds quickly at these temperatures with conventional catalysts, including rhodium. As a result, FeCo and AlNiCo are suitable materials for induction heating of high temperature reaction channels. Other materials, like FeCrAlloy or iron or nickel may be suitable for unit operations requiring more modest temperatures, such as for steam generation, desorption, distillation, or other reactions, or simply heating.
Of additional interest is the opportunity to select the flux concentrator material for its temperature-sensitive magnetic properties, so that more heat is added to colder channels, or into sections of colder channels, than to hotter process channels and/or sections. Higher temperatures translate to faster chemical (kinetic) reaction rates but excessively high temperatures may damage the materials of the receiver, catalysts, adsorbents, etc. Also, by selectively concentrating inductive heating to colder sections of a receiver, reactions, separations or other endothermic operations can be sped up and the higher overall productivity of the micro- and/or meso-channels can be achieved.
In
This toroidal approach can be used to heat an endothermic reactor such as has already been described in this text. Alternately, by segmenting the coils and independently controlling each segment, heat can be specifically varied from segment to segment. This may be particularly useful in operating a thermal-swing or thermally-enhanced pressure-swing adsorption system, with individual collections of channels operating cooperatively as “cells”, but with the cells purposely operated in or out of phase of each other. An example of out-of-phase operation can be beneficial, such as in the units described in U.S. Pat. No. 6,974,496, which includes multi-celled micro- and meso-channel adsorption units with internal thermal recuperation.
As another example, the use of a ferromagnetic foam (e.g., FeCralloy) within a channel can support placing a limited amount of heat within a fluid where vaporization is desired. Yet additional embodiments are possible. For example, coils can be arranged in non-circular geometries, such as in the form of triangles, squares, hexagons, octagons, etc. Coils can be “tiled” together in planar or non-planar structures; however, the designer should consider constructive and destructive interference when tiling units together.
Insulating materials can be added to a) limit heat leaks and b) to thermally separate the reactor from the induction coils. Ideally, the coils are located in close proximity to the unit to be heated, but with an insulating layer (for example, millimeters to centimeters in thickness, i.e., 1-30 mm or 1-20 mm or 1-10 mm) separating the coils from the micro- and/or meso-channel device. Copper such as in Litz wire or aluminum are the preferential materials for induction coils. However, they do not perform as well at elevated temperature and thus, must be isolated from high temperature reactors or cooled (actively or passively) in order to achieve the highest performance.
Basic Hybrid Micro/Meso-Channel Structure for Induction Heating with an Additional Heating Channel
In previous work, we invented a micro/meso-channel chemical processor unit, for endothermic operations—more specifically, a catalytic pancake reactor—the efficiency of which benefits from heating the reaction channels from two sides. As described in U.S. Pat. No. 9,950,305, the pancake reactor is a counter-radial flow reactor with outflowing reaction channels, with catalysts, with the reaction products then flowing inwardly in adjacent channels, providing sensible heat from the products to the catalytic reaction channels. In this manner, this heat is in addition to the solar thermal energy being provided from the opposite side.
Internal counterflow is a particularly efficient way to recuperate energy from the product stream and is exergetically more efficient than simply using the product stream to further preheat the reaction system through, say, the use of an external counterflow microchannel heat exchanger. In essence, the sensible energy in the product stream is recuperated into its reaction channel steam.
The advantage of this approach is illustrated in the graphs shown in
Alternative embodiments could have used a separate source of heat in the return channels, for example heat from a combusting fluid. The return channels can be reconfigured so that they recuperate to other reaction channels. An important benefit is the imperfections in the parabolic dish and/or the reactor design are mitigated in a way that reduces “hot spots” in the reactor. For example, imperfections in the parabolic shape of the dish can create both hot and cold spots on the chemical processor surface. Alternately, imperfections in flow, brought out by minor variations in the design of the processing unit which can be amplified: Process channels with slightly reduced flow will tend to get hotter, in the case of an endothermic chemical reaction generating greater reaction and, in cases like steam reforming, corresponding increases in volumetric flow that promote further reductions in mass flow into the hotter channels; and channels that receive greater flow will tend to run colder, producing a lower percentage of reaction with increases in volumetric flow. This is an undesirable positive feedback loop that tends to further increase the temperature of hotter channels, amplifying hot spots, and further decrease the temperature of colder channels.
Hot spots are problematic, even when nickel superalloys are used for the reactor structure, since the strength of these alloys falls rapidly at very high temperatures (e.g., in the 800-1000° C. range) as temperatures are increased. Thus, having the “hottest” reaction channels recuperate into relatively colder channels, and vice versa, provides effective thermal spreading and creates a negative feedback loop, mitigating the positive feedback loop, that enables improved system performance and greater strength in the alloy structure. The opportunity for this is evident from simulations which predicted up to 100° C. reduction in the temperatures of the hottest spots.
For induction heating, we sought to maintain the advantage of the negative feedback loop in the previous invention—brought about by the internal counter-cross flow structure, but found that additional improvements were needed in order to adapt our basic reactor concept to efficient inductive heating.
We also found that nickel superalloys, which tend to be (or are understood to be) weakly paramagnetic present both advantages and disadvantages for induction heating. For example, induction heating in paramagnetic materials is known to be through joule-heating (through induced eddy currents) and does not include a hysteresis heating component. This means there is a reduced capacity for heating but it also means there is an improved capability for reducing hot spots on the reactor surface.
When heating is dominated by eddy-current heating, it is useful to recognize and exploit the variation in heating that occurs as a function of depth into the processing unit structure. Many induction-heating references define a term, “thermal penetration” (δ), to be the distance into an externally-heated material where 86% of the heating occurs; the other 14% occurs deeper into the device. A common mathematical representation of this is:
δ=5000SQRT[σ/μf]
Where σ is the electrical resistivity of the material in ohm-centimeters (Ω-cm), μ is the relative magnetic permeability of the material (which is unitless, with the vacuum of space having the value μ=1), and f is the frequency in Hertz (Hz) of the magnetic field. In this case, the units of δ are centimeters (cm).
For near-term applications, the frequency of the induction coil is expected to typically be in the range of 1-100 kHz, more preferably between 1-50 kHz, as a number of induction heating units have already been designed for applications in this frequency range. These units, including power electronics, are in mass production and have been demonstrated to operate at high efficiencies.
Here we consider the case of heating a micro/meso-channel device that is constructed of the nickel superalloy Haynes 282, an alloy that was developed for high temperature application such as gas turbines and which exhibits favorable characteristics which increase the lifetime of high temperature chemical process units compared to many other alloys. Development work has also progressed that demonstrates the suitability of Haynes 282 for the additive manufacturing of micro/meso-channel components. For example, see U.S. Pat. No. 10,981,141 B2 which describes the design and method of making an additively manufactured, pancake reactor.
The electrical resistivity of Haynes 282 does not substantially increase with temperature. As a result, the thermal penetration distance for Haynes 282 alloys varies more strongly with frequency, and as a result we can calculate that the thermal penetration (δ) of Haynes 282 at a representative frequency of, say, 25 kHz, can be calculated to be 3.61 millimeters (mm); or about 2.85-5.71 mm if we assume a still more narrow operating range of 10-40 kHz for the induction system. This gives us a first look at the approximate depth, into our chemical processor, within which the majority of induction heating will occur.
Alternately, it can be useful to consider induction heating in terms of the half-energy distance (d1/2) into the reactor at which half of the received magnetic energy (E) is converted to heat. This term is mathematically similar to radioactive decay, where physicists discuss the time that it takes half of a radioisotope sample to decay into another species. At two half-thicknesses (2 d1/2), ¾ths of the energy has been converted into heat; at three half-thicknesses (3 d1/2), ⅞ths; at 4 d1/2, 15/16ths, etc. The relationship for energy conversion into heat within the micro/meso-channel receiver is therefore:
E/Eo=e
−λt
Where Eo is the magnetic energy entering the chemical processor, E represents the magnetic energy that has not been converted into heat throughout the material, λ is a “decay constant” based on the properties of the material and in fact is equal to 2/δ, and t as a variable represents the thickness into the material at which the value for E is desired. The half-energy distance is therefore:
d
1/2=ln(2)/λ
which, for Haynes 282 at 25 kHz is about 1.25 mm.
In
Flow is counter-cross flow, but it is convenient to consider the example as if flow is generally moving perpendicular to the page.
The cross-section was chosen for a location in the reactor where the return channel and reaction channels are atop one another. The inductors, each pancake coils, generate heat through eddy currents (as Joule-Heating), and may also generate heat through hysteresis heating in the immediate surface metal (on the upper side, this is indicated as the “top wall” and may include an Induction Enhancer).
A gap between the top wall and the inductor allows the placement of insulation and limits heat transfer to the coil, which may require passive or active cooling. In applications where an induction enhancer is desirable, one option is the placement of a thin layer of cobalt-iron (CoFe), which has an extremely high relative magnetic permeability and a high Curie Temperature (˜970° C.). Here, the induction enhancer generates heat through both Joule Heating and Hysteresis Heating.
Chemical Transformers are process-intensive chemical process systems which gain an economic and productivity advantage through the incorporation of micro- and meso-channel reactors, separators, heat exchangers, vaporizers and condensers. The compact size of these mass-producible units, plus their high process intensities, enables their use in relatively small system in a manner that is analogous to electrical transformers.
In one embodiment, the chemical transformer performs steam reforming and water-gas shift reactions, using electrical energy to provide heat for endothermic operations such as steam reforming of a hydrocarbon (e.g., methane), steam generation, preheating fluids, and of course providing the energy for classical mechanical or electrical operations such as driving pumps, compressors, valves, controls, etc. Electro-chemical operations may also be supported. Hydrogen and other chemicals can be produced in a chemical transformer using methane reforming, water-gas shift, heat exchange and other unit operations. Placing a small chemical transformer, such as the unit shown on the following slide, which has a footprint of about 2 square meters, provides an opportunity to generate around 150-200 kg of H2 per day, or larger or smaller amounts.
The illustrated five, pancake-shaped microchannel reformers (
The use of solar or other energy to drive the endothermic operations reduces the necessity of using methane for the required heat. This potentially reduces the fossil carbon emissions associated with the overall system by up to about 40% and, to the extent that the replacement energy comes from renewable sources, such as solar thermal heat or electricity from wind generators or solar photovoltaics, assures that at least a portion of the energy in the chemical products is at least somewhat renewable energy. Further, when a non-fossil methane source is the feedstock, the fossil carbon emissions of the system can be zero.
Hexagons were selected as an efficient way to configure the internals, including plumbing, controls (e.g., valves), and sensors such as pressure transducers, thermocouples and chemical sensors. The use of hexagons, which may be “regular” or “irregular” in geometry, that can be separated into two “half-hex” sections, such as shown in
Methods other than induction heaters can be used for electrical heating of endothermic operations, including electrical resistance heaters, such as cartridge heaters, and radiant heaters.
With reference to
We also designed a chemical transformer to provide shifted syngas (reformate) based on the use of six Steam Methane Reformers (SMRs), six High Temperature Recuperative (HTR) heat exchangers, two adiabatic Water-Gas Shift reactors with an intermediate heat exchanger between them, plus steam generators and a water condenser heat exchanger. The system is designed to support the production of up to 200 kg H2 per day based on the downstream inclusion (not shown) of a H2 separator/purifier (such as a Pressure Swing Adsorption unit [PSA]), with a tailgas from the PSA that contains CO2, unreacted CH4, H2 and additional constituents in smaller quantities (e.g., CO, H2O, etc).
In the apparatus illustrated in
The system is designed to be assembled into a skid structure that, from above, appears to be an irregular hexagon. However, any structure can be used. The SMRs are designed to be heated electrically, such as through the use of induction heaters, rather than by combustion of the tail gas or another combustible material, as is generally done in the industry. This allows us to use photovoltaic solar panels to heat our SMRS in parts of the world where this is a good solar resource. Alternately, any other source of electricity can be used, including electricity from an electrical grid.
This configuration creates the ability to convert excess electrical energy to the hydrogen and when there is need for extra energy on the electrical grid the hydrogen can be used to power a fuel cell or another power generator, including heat engines (e.g., gas turbines, Stirling or Otto Cycle engines). In this way we have created an electrical-chemical transformer that amplifies the energy of the methane. For example, methane has 50 mega-Joules of fuel energy per kilogram. 2 kg of methane are needed to make one kg of hydrogen which has 120 mega-Joules of Hydrogen. That is a 20% increase in fuel energy content. This is possible because the energy provided by adding electricity to heat the high temperature, endothermic methane reforming reaction increases the fuel energy of the reacting stream.
The system can also be considered an amplifier of electrical energy. It takes about 15 kilowatt hours of electricity to make a kilogram of hydrogen. If that hydrogen is converted using a fuel cell it will produces about 17 kilowatt hours of electricity assuming about 55% efficiency. Finally, the system can be used to make water where it is needed because it makes more water than it consumes. For every 18 kilogram of water used in the SMR to make hydrogen, the fuel cell will discharge 36 kg of water vapor, this make the SMR/Fuel Cell process a water amplifier as well.
The hydrogen generation industry has relied on the economics of large scale to reduce the cost of production. The economics of hardware mass production will reduce the cost of the hydrogen produced by chemical transformers. A 200 kg per day SMR skid (excluding control panels, de-sulfuring, de-ionizing water, and pressure swing adsorption) has a footprint of about 2 meters. Alternately, further stacking the SMRs within a chemical transformer would enable nine of the designed SMRs in an area of approximately 1 square, capable of producing more than 300 kg of hydrogen per day. The modularity of the design allows the production of hydrogen on-site anywhere there is the infrastructure for methane, water and electricity.
A steam methane reformer (SMR) reactor was fabricated using the additive manufacturing process called selective laser melting (SLM) or laser powder bed fusion (LPBF). The diameter is approximately 11 inches and the thickness is less than 1 inch. The structure in the center on top has two openings, one channel for flowing reactants, methane and steam, into the reactor and one channel for product reformate gas to flow out of the reactor. The groove around the perimeter is used for electro-discharge machining (EDM) to remove the outer ring. Metal foam structures coated with SMR catalyst are inserted into the catalyst channels. The ring is replaced around the perimeter and welded in place to seal the reactor except for the inlet and outlet channels on top. This type of reactor is described in U.S. Pat. No. 9,950,305 with the reaction channels being straight and the return channels (heat transfer channels) being curved, therefore providing counter-cross flow heat exchange from the return channels to the backside of the reaction channels. A hydrogen production module is completed by attaching a high temperature recuperative heat exchanger to the inlet and outlet channels, as shown in
The reactor is heated from the bottom side from a pancake induction coil. Alternating current electricity passing through the inductor creates a magnetic field that induces mirror currents in the adjacent reactor. The reactor rested on top of a commercial induction coil rated for 5 kw power.
The SMR reactor operates at temperatures near the exit of the process channels in excess of 750° C., or 800° C. or more, or between 750 and 900 or 950° C. Since the coil would be damaged at typical SMR temperatures, insulation is placed between the induction coil and reactor. The coil can be cooled by convectively flowing air across the side of the coil opposite the reactor, or alternatively, by placing a cold plate against the coil. One example of a cold plate is an aluminum block with cold water flowing through channels or tubing embedded in the aluminum. The configuration used 1.2 cm of insulation between the coil and reactor and cooling of the coil with air flow.
These test results illustrate the importance of using the reactor body as a moderator of temperature for the CoFe, the magnetic susceptibility of which falls as the Curie Temperature is approached. By gaining good thermal contact between the CoFe and the reactor, the temperature of the CoFe is limited to approximately a slightly greater temperature than the reactor surface, which should in all areas of the reactor should be less than 900° C.
An innovation to promote inductive coupling between the induction coil and the reactor was to add another layer of material acting as an induction enhancer that is ferromagnetic between the coil and the reactor. A sheet approximately 0.35 mm thick of Cobalt-Iron (FeCo) sheet was inserted between the insulation and the SMR reactor and affixed to the reactor with a thermal paste that cures into a ceramic material compatible with the reactor temperatures. The Curie temperature of the Cobalt-Iron material is approximately 950° C. where it undergoes a phase change and transitions from ferromagnetism to paramagnetism.
The initial campaign tested the reactor at varying temperatures while maintaining a methane flow rate of 9 SLPM, a pressure of 132 psig, and 3:1 steam to carbon ratio. Methane conversion as a function of reactor temperature, which is the average of 12 thermocouples located around the perimeter of the reactor, closely tracked equilibrium conversion (within 3%) indicating that the reactor is equilibrium limited and has higher potential production capacity. This is expected because the flow rates for this test were approximately one third of reactor design flow rate. Testing at full design flow is constrained by the induction heating capacity of the test unit as explained above. Likewise, the fraction of methane converted to CO2 and the equilibrium mole fraction, were also equilibrium limited at these test conditions. The thermal energy efficiency of the induction process was between 50 to 52% at an induction heater power between 1.85 and 2.45 kW. Thermal energy efficiency is the efficiency of converting power to chemical energy, defined as the change in enthalpy between the SMR inlet and outlet streams divided by the power consumed by the induction heating system. A similar metric, called the chemical efficiency, which is the change in higher heating value (HHV) of the stream divided by the induction power was measured to be 58% to 62% at an induction heater power between 1.85 and 2.45 kW. Thermal energy efficiency is consistently above 50% in this test, and the conversion to higher heating value was around 60%. The thermal energy efficiency can be compared with the prior reported energy efficiency of 10 or 23% as reported by Amind et al., Catalysis Today, pp. 13-20 (February 2020).
The average perimeter temperature is plotted with induction power current in
The thermal paste that forms a rigid ceramic material was replaced with a braze consisting of 98% copper and 2% silver to provide more ductility and compliance in the braze joint to accommodate the CTE mismatch. Running the reactor with the new braze material resulted in the results shown in
The next attempt was to reconfigure the cobalt-iron sheet into an improved, engineered induction enhancer, producing circular segments that were then brazed onto the reactor wall with the copper-silver braze as shown in
In this section, we describe an overall package design for an inductively-heated, three-layer SMR. The three layers within the SMR are two process layers sandwiching a heat transfer layer. An induction enhancer may or may not be included as some unit processes may not need the induction enhancer. For example, steam generation at modestly hot temperature (e.g., 200° C. or less) can easily be conducted at temperatures where the process unit is made of a ferromagnetic alloy (e.g., magnetic stainless steel) and the operating temperature may not require insulation between the reactor body and the induction subsystem.
Related Applications: This application claims the priority benefit of U.S. Provisional Patent Applications 63/107,420 filed 16 Sep. 2020 and 63/140,745 filed 22 Jan. 2021.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2021/050756 | 9/16/2021 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63079420 | Sep 2020 | US | |
| 63140745 | Jan 2021 | US |
