HEAT ABSORPTION, TRANSPORTATION, AND REGENERATION FOR PROCESS HEAT DELIVERY USING THE SORPTION ASSISTED BOUDOUARD REACTION

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO APPENDIX

Not applicable

BACKGROUND OF THE INVENTION
Field of the Invention

The disclosure generally relates to a transport of heat through a medium from a chemical process. More specifically, the disclosure relates to a transport of heat through a medium from a catalytic enhanced chemically reversible process.

Description of the Related Art
BACKGROUND

Generating industrial process heat using clean and renewable resources is an important part of the green energy transition. Industrial processes account for about 23% of U.S. greenhouse gas emissions. The use of low-carbon energy sources for industrial heat is a specific strategy proposed in the US Department of Energy's Industrial Decarbonization Roadmap.

FIG. 1 is a schematic diagram of a nuclear reactor of the high temperature gas reactor type as an example of a low-carbon, alternative high temperature heat generator. The high temperature heat generator 1 can include a fuel supply 2 is fed into a reactor 3 that generates heat energy within a pressure vessel 4. The heat energy is applied to a circulating fluid such as a gas or a supercritical fluid that flows through a closed loop circuit by a circulator 5. The heated fluid from the reactor flows through a heat exchanger 6 through which a secondary fluid circuit flows by a circulation pump 7. The heated fluid from the reactor transfers the heat into the secondary fluid that may produce steam, chemicals, or perform other work with the heated energy.

Despite being a relatively clean energy source, nuclear energy is costly for individual facilities and historically has not been practical. Other renewable sources such as wind for wind turbines and solar for solar concentrators are by nature intermittent. Thus, industry, particularly chemical process plants, typically uses gas-fired boilers to generate steam and transport the steam throughout the plant for the various processes. The heat loss to the environment and reduced steam quality through steam pipelines throughout the plant results in a loss of efficiency.

Great environmental and economic value can be created by a system for storing and transmitting clean, high-quality industrial process heat. A challenge of incorporating renewable clean energy sources lies in flexibly integrating variable sources with existing industrial infrastructure.

FIG. 2 is a schematic diagram of typical reverse and forward Boudouard reactions. A reverse Boudouard reaction 8, known as “dry reforming”, converts with energy input carbon dioxide (CO2) and carbon (C) to carbon monoxide (CO) with chemically stored heat in the CO from the conversion. An absorber 10 absorbs heat input from an external energy source (not shown) for the conversion to CO at a capture temperature. The CO flows to a regenerator 12 for a forward Boudouard reaction that converts the CO back to CO2 and C and releases the heat.

To obtain even higher temperatures for a higher “quality” heat, a Boudouard reaction can be combined with an alkali metal carbonate decomposition. Initially, a metal carbonate (MCO3) is heated to its decomposition temperature, absorbing heat and producing CO2 and a metal oxide (MO). The CO2 is then used at the point of capture in the reverse Boudouard reaction as a dry reforming process with heat input as described above and CO gas is produced with the chemically stored energy. To release the stored energy as heat, the forward Boudouard reaction flows the CO through a blend of catalyst and metal oxide powder to drive two reactions-the Boudouard reaction and the conversion of metal oxides to metal carbonates-releasing more energy and therefore producing higher quality heat. The catalyst assisted conversion is termed a Sorption Assisted Boudouard Reaction (SABR). Higher temperatures can be achieved if the CO is compressed, and can produce temperatures higher than the capture temperatures, sometimes also termed higher quality heat.

- Add product scavenger

$\frac{\begin{matrix} 2 CO \to {CO}_{2} + C + \\ M O + {CO}_{2} \to {M CO}_{3} (M = Mg, Ca, Sr, Ba) \end{matrix}}{= 2 CO + MO \to {M CO}_{3} + C}$

- “Sorption Assisted Boudouard Reaction”

The symbol “M” stands for an alkali earth metal (i.e., a Group 2 element on the Periodic Table). The conversion from the products of the SABR process are:

MCO₃+C+350 KJ⇄2CO+MO

There remains a need for a system and method of improved efficiency in transporting heat to a desired destination for use.

BRIEF SUMMARY OF THE INVENTION

The disclosure provides a system and method for absorbing clean heat, storing it at ambient temperature for transport or delayed use, and regenerating it with high exergetic efficiency. “Clean” heat does not generate carbon emissions or other emissions like nitrogen and sulfur oxides (i.e., NOx and SOx). The system and method can capture high quality heat at high temperatures from a source such as nuclear, concentrated sunlight, or geothermal, then store that energy in the form of chemical bonds at a transport temperature that generally is at ambient temperature, and can regenerate the heat at temperatures at or slightly below the capture temperature. Because energy can be stored at ambient temperature, the process allows heat to be transmitted over great distances or held long term with minimal losses. The chemical reaction uses the Boudouard reaction dry reforming of carbon, layered with metal carbonate decompositions and a catalyst, to generate a higher heat than a typical Boudouard reaction. The sensible heat that is lost in conventional steam piping by heat transfer to the environment can be reduced or replaced with the present invention that transports chemical heat at ambient temperatures with little, if any, sensible heat loss. The process provides direct integration of carbon exhaust free heat with an opportunity to increase the reliability of industrial heat while reducing greenhouse gas emissions and fuel costs, furthering environmental justice for underserved communities, and forming a physical multi-sector infrastructure for net-zero industry by 2050.

In at least one application, the process could be used to deliver energy from nuclear facilities to industrial processes without converting heat to electricity. As a process example, delivered heat could be used to preheat boiler intake air, drastically decreasing fuel consumption and carbon emissions. The invention efficiency limit at ambient pressure is modeled to be about around 70% compared to about 45% for Carnot-limited electrical processes. The process can also enable smooth and continuous delivery of heat, even when an intermittent heat source such as sunlight is employed.

The disclosure provides a method for delivering high-quality heat to a site, comprising: heating carbon and a metal carbonate powder at a capture temperature to produce carbon monoxide and a metal oxide powder; separating the carbon monoxide from the metal oxide powder; transporting the carbon monoxide to the site; transporting the metal oxide power to the site; and blowing the carbon monoxide through the metal oxide powder containing a catalyst to yield carbon and metal carbonate powder to release heat at the site.

The disclosure also provides a method for delivering high-quality heat to a site, comprising: heating carbon and carbon dioxide at a capture temperature to produce carbon monoxide; transporting the carbon monoxide to the site at a temperature that is optionally different than the capture temperature; and blowing the carbon monoxide through a catalyst to yield carbon and carbon dioxide to release heat at the site.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a schematic diagram of a nuclear reactor of the high temperature gas reactor type as an example of a low-carbon, alternative high temperature heat generator.

FIG. 2 is a schematic diagram of typical reverse and forward Boudouard reactions.

FIG. 3 is a schematic diagram of an illustrative embodiment from a catalytic reaction in the invention transporting a stored energy in a fluid at ambient temperatures for low loss and high efficiency.

FIG. 4 is a schematic diagram of an illustrative embodiment from a catalytic reaction in the invention flowing a stored energy in a fluid at ambient temperatures for low loss and high efficiency.

FIG. 6 is an illustrative graph showing an effect of process pressures relative to outlet temperatures for the reactions of the invention.

FIG. 7 is an illustrative graph showing an effect of process efficiency relative to outlet temperatures for the reactions of the invention.

FIG. 9 is an exemplary conceptual embodiment using a high-temperature gas reactor and an industrial sector with the invention as described above.

DETAILED DESCRIPTION

The Figures described above and incorporated from the Appendices, and the written description of specific aspects and functions below are not presented to limit the scope of what Applicant has invented or the scope of the appended claims. Rather, the Figures and written description are provided to teach any person skilled in the art to make and use the inventions for which patent protection is sought. Those skilled in the art will appreciate that not all features of a commercial embodiment of the inventions are described or shown for the sake of clarity and understanding. Persons of skill in this art will also appreciate that the development of an actual commercial embodiment incorporating aspects of the present disclosure will require numerous implementation-specific decisions to achieve the developer's ultimate goal for the commercial embodiment. Such implementation-specific decisions may include, and likely are not limited to, compliance with system-related, business-related, government-related, and other constraints, which may vary by specific implementation or location, or with time. While a developer's efforts might be complex and time-consuming in an absolute sense, such efforts would be, nevertheless, a routine undertaking for those of ordinary skill in this art having benefit of this disclosure. It must be understood that the inventions disclosed and taught herein are susceptible to numerous and various modifications and alternative forms. The use of a singular term, such as, but not limited to, “a,” is not intended as limiting of the number of items. Further, the various methods and embodiments of the system can be included in combination with each other to produce variations of the disclosed methods and embodiments. Discussion of singular elements can include plural elements and vice-versa. References to at least one item may include one or more items. Also, various aspects of any embodiments could be used in conjunction with each other to accomplish the understood goals of the disclosure. Unless the context requires otherwise, the term “comprise” or variations such as “comprises” or “comprising,” should be understood to imply the inclusion of at least the stated element or step or group of elements or steps or equivalents thereof, and not the exclusion of a greater numerical quantity or any other element or step or group of elements or steps or equivalents thereof. The device or system may be used in a number of directions and orientations. The terms “top”, “up’, “upward’, “bottom”, “down”, “downwardly”, and like directional terms are used to indicate the direction relative to the figures and their illustrated orientation and are not absolute relative to a fixed datum such as the earth in commercial use. The term “inner,” “inward,” “internal” or like terms refers to a direction facing toward a center portion of an assembly or component, such as longitudinal centerline of the assembly or component, and the term “outer,” “outward,” “external” or like terms refers to a direction facing away from the center portion of an assembly or component. The term “coupled,” “coupling,” “coupler,” and like terms are used broadly herein and may include any method or device for securing, binding, bonding, fastening, attaching, joining, inserting therein, forming thereon or therein, communicating, or otherwise associating, for example, mechanically, magnetically, electrically, chemically, operably, directly or indirectly with intermediate elements, one or more pieces of members together and may further include without limitation integrally forming one functional member with another in a unitary fashion. The coupling may occur in any direction, including rotationally. The order of steps can occur in a variety of sequences unless otherwise specifically limited. The various steps described herein can be combined with other steps, interlineated with the stated steps, and/or split into multiple steps. Similarly, elements have been described functionally and can be embodied as separate components or can be combined into components having multiple functions. Some elements are nominated by a device name for simplicity and would be understood to include a system of related components that are known to those with ordinary skill in the art and may not be specifically described. Various examples are provided in the description and figures that perform various functions and are non-limiting in shape, size, description, but serve as illustrative structures that can be varied as would be known to one with ordinary skill in the art given the teachings contained herein. As such, the use of the term “exemplary” is the adjective form of the noun “example” and likewise refers to an illustrative structure, and not necessarily a preferred embodiment. Element numbers with suffix letters, such as “A”, “B”, and so forth, are to designate different elements within a group of like elements having a similar structure or function, and corresponding element numbers without the letters are to generally refer to one or more of the like elements. Any element numbers in the claims that correspond to elements disclosed in the application are illustrative and not exclusive, as several embodiments may be disclosed that use various element numbers for like elements.

The disclosure provides a system and method for absorbing clean heat, storing it at ambient temperature for transport or delayed use, and regenerating with high exergetic efficiency. The system and method can capture high quality heat at high temperatures from a source such as nuclear, concentrated sunlight, or geothermal, store that energy in chemical bonds at ambient temperature, and regenerate the heat at the same or similar temperatures. By storing at ambient temperature, the process allows heat to be transmitted over great distances or held long term with minimal losses. The chemical reaction uses the Boudouard reaction with metal carbonate and catalyst to generate a higher heat than a typical Boudouard reaction. The sensible heat that is lost in conventional steam piping by heat transfer to the environment can be reduced or replaced with the present invention that transports chemical heat at ambient temperatures with little sensible heat loss.

FIG. 3 is a schematic diagram of an illustrative embodiment of a conceptual system using the SABR process for heat capture, transfer, and regeneration process, with necessary energy storage to buffer variability, availability and/or operation. Such variability and availability can occur for example during dark hours when solar heat is employed or when wind energy is not available.

Depending on the Alkali Earth metal chosen, the process can deliver heat in the 600° C. (873K) to 1175° C. (1448K) range. If operated using carbon-free heat, such as concentrated solar or from a high temperature gas reactor, the process could drive complete decarbonization of all process heat requiring temperatures up to 1175° C. Further, using mechanical work to raise the pressure of the reaction could result in higher temperatures.

Heat is captured in the strongly endothermic reverse SABR reaction shown in (1) (r-SABR), and is released when forward SABR occurs with CO disproportionation at the surface of a suitable catalyst. This effect intentionally cokes with C the catalyst, which is therefore a reactant consumed during heat release (i.e., it is a “catalyst”), and is regenerated during heat absorption.

As shown in FIG. 3, a system 20 can include an absorber 24, such as a reactor including a fluidized bed reactor. The absorber 24 can receive heat from an external heat source 22, such as solar, nuclear, or other sources. The absorber with the heat input can reverse the Boudouard process in which a reaction mixture C+MO3 can be roasted at a capture temperature, converting the heat to chemical energy in an absorber output gas/solid mixture of 2CO+MO at the absorber outlet 26. The absorber output can flow through a heat exchanger 28 that can also separate the MO powder from the CO gas. The MO can be loaded into a transportation vehicle 30 and taken to a site where the MO is used in a regenerator 40. The heat exchanger 28 can exchange at least some of the heat in the absorber output gas and preheat recycled gas in a pipeline 56 from a transportation vehicle 54 from the regenerator 40 in the process loop. Downstream of the heat exchanger toward the absorber, the recycled gas can enter an input 60 of the absorber 24.

The CO gas separated from the MO powder can flow through a pipeline 32 (or be transported on road or rail as a compressed gas) from which a portion can flow through a conduit 34 into a storage tank 36 for an indefinite period at ambient conditions to provide a buffer quantity of the CO gas to supplement times of low flows. The remainder of the CO gas in the pipeline 32 can flow to a remote point of use location with minimal storage duration or distance related losses. In proximity to the regenerator, CO gas can flow through another heat exchanger 52 to be heated up by the output fluid from the regenerator output 50. In the regenerator, the CO gas contacts the MO powder from the transportation vehicle 30, referenced above, generally in the presence of a catalyst to cause the forward Boudouard process and release of the stored heat. The regenerator 40 regenerates the stored heat in the MO powder and CO gas, where the regenerator could include a fluidized bed system at the point of use that results in C and MCO3 from the energy release. The C can be transported as a solid to the absorber 24 for another cycle. The MCO3 forms particles that can be also transported back to the absorber 24 for another cycle. The exothermic reaction regenerates the chemically stored heat through an outlet 42 that can be transferred into air through a heat exchanger and used for various purposes such as heating in HVAC systems such as in residential and commercial sectors 44. The heat can be used to preheat intake air of fossil fuel-fired boilers used to provide process heat to the industrial sector 46, and other applications. Further, the regenerator 40 can be a skid-built embodiment that can be located on a remote site for a temporary or special purpose provision of heat input or to minimize costs associated with integrating the system into existing processes.

The exothermic reaction regenerates the chemically stored heat from heat outlet 42, that can be transferred into the heated air through a heat exchanger and used for various purposes such as heating in HVAC systems such as in residential and commercial sectors 44. The heat can be used to preheat intake air of fossil fuel-fired boilers used to provide process heat to the industrial 46, and other applications. Further, the regenerator 40 can be a skid-built embodiment that can be located on a remote site for a temporary or special purpose provision of heat input or to minimize costs associated with integrating the system into existing processes.

A significant concern of chemical companies around integrating clean process heat is the potential start-up time associated with transitioning to and from a traditional natural gas-fired heat source if necessary. This concern is driven by the recognized long period (up to five-days or even longer) required to safely warm up interior refractory material of a boiler or furnace as an existing heat source to operating temperatures. The system can inject heat into the existing heat infrastructure at the process enabling seamless transition between total and partial clean heat supply, and legacy fuels using existing in-situ controls.

In this proposed technology, carbon free heat can be collected at the available resource rate, stored, and delivered at the required process rate, smoothing out uneven supply or demand limited only by tank capacity, but with no losses penalty incurred due to storage duration.

Likewise, heat can be transported great distances, limited only by pipeline infrastructure. Novel solutions have been developed to mitigate environmental, health, and safety risks associated with storing and transporting CO. Existing pipeline easements and infrastructure may be repurposed for clean energy transport as industry transitions away from legacy fuels.

FIG. 4 is a schematic diagram of an illustrative embodiment from a catalytic reaction in the invention flowing a stored energy in a fluid at ambient temperatures for low loss and high efficiency. FIG. 4 is similar to the embodiment in FIG. 3 and like components have like element numbers. A difference is that an absorber return pipeline 62 from the heat exchanger 52 to the heat exchanger 28 allows a flow between the heat exchangers to return the output fluid from the regenerator 40 back to the absorber 24.

FIG. 5 is a schematic diagram of an illustrative embodiment from a reaction in the invention flowing a stored energy in a fluid from a reaction at ambient temperatures for low loss and high efficiency. The system 18 is similar to the embodiment in FIG. 4 and like components have like element numbers. The embodiment illustrates a reverse Boudouard process in the system 18 where absorber 24 uses the heat source 22 to convert C+CO2 into 2CO without using a catalyst. The process may not have the higher heat content or efficiency, but may be a practical solution for various applications. The regenerator converts the 200 back to C+CO3 when the heat is released from the reaction. A catalyst can be useful for the regeneration for increased results.

FIG. 6 is an illustrative graph showing an effect of process pressures relative to outlet temperatures for the reactions of the invention. Though the equilibrium temperatures at which the SABR reactions take place under standard conditions are fixed, the range of temperatures at which the process may be carried out is expanded through the change of pressure of the reactant gases. Thus, the SABR process temperature can be adjusted by changing a pressure of the process.

FIG. 7 is an illustrative graph showing an effect of process efficiency relative to outlet temperatures for the reactions of the invention. Process modelling has also shown that significantly lower energy losses are incurred by transmitting the heat as chemical heat using SABR rather than by using sensible heat in superheated steam. Calculated exergy efficiencies for different outlet temperatures resulting from process implementation are shown in FIG. 7, and can be shown to be as high as 70% at a temperature of 1175° C.

As noted above, to perform a forward Boudouard process to release the heat, a catalyst can be used. Catalytic materials include transition metal catalyst, including fourth, fifth and sixth row elements from groups 3 to 14 (i.e., Scandium, Vanadium, Titanium, Chromium, Manganese, Iron, Cobalt, Copper, Zinc, Gallium, Germanium, Yttrium, Zirconium, Niobium, Molybdenum, Ruthenium, Rhodium, Palladium, Silver, Cadmium, Indium, Tin, Lanthanum, Hafnium, Tantalum, Tungsten, Rhenium, Osmium, Iridium, Platinum, Gold, Mercury, Thallium, Bismuth, the lanthanides and actinides), or alloys thereof, both as metals or metal alloys, their carbides, and both as metal or metal carbide macroscopic particles or as micro-or nano-particles dispersed on the surface of a substrate like Alumina (Al2O3), Silica (SiO2), Titania (TiO2), and so forth), with preference for the first row transition metals Fe, Co, Ni and their mixtures. Recently it has also been shown that carbon deposition may occur from other materials including Au, Ag, Cu, Pd, Rh, some semiconductors such as Si and Ge, some carbides such as SiC and Fe3C, and oxides including Al2O3, TiO2, and rare earth oxides.

An exemplary embodiment includes 1) a chemical reactor, such as a fluidized or spouted bed, sustaining the heat-absorbing step supplied with nuclear or concentrated solar heat, 2) transportation of the product carbon monoxide via pipeline or transportation vehicle, 3) a reactor that can be skid-built, sustaining the heat-releasing step, and 4) the product gases of the heat-releasing step preheating the intake air of a combustion unit used for industrial process heat generation via a gas-gas heat exchanger.

By transporting thermal energy at close to ambient temperature, the process also has the potential to be significantly less expensive to implement than classic transfer as sensible heat, such as through superheated steam or air. Due to the high temperature and pressure required for steam and air, the header and main steam piping must be constructed from a heavy wall thickness pipe with a large diameter. Additionally, the pipe material advantageously has good creep strength and good ductility and toughness along with high thermal fatigue resistance to prevent catastrophic failure during operation. Moreover, sensible heat pipes also would advantageously be insulated to remain efficient.

Conversely, because for the SABR process the delivery of heat occurs at close to ambient temperature, polymeric materials such as those used for transmission of natural gas—like polyethylene of polyamide-12 (see 49 CFR Part 192)—become practical. Some capital costs associated with thermal insulation and corrosion prevention, potential installation costs, and operational costs associated with loss of heat to the surroundings can be avoided.

Preliminary Results and Research Tasks

FIG. 8 is an exemplary graph of a residual gas analyzer trace showing two cycles of chemical conversion between a reverse Boudouard reaction and a forward Boudouard reaction as would be performed in an absorber and regenerator as taught herein, respectively. The inventors experimented with using both the reverse Boudouard reaction (i.e., dry reforming) combined with the forward Boudouard reaction as closed symbiotic reversible loop using the same solid catalyst in relevant gas flows. The Mass Spectrometer trace from a process demonstration experiment is shown in FIG. 4 below.

FIG. 9 is an exemplary conceptual embodiment using a high-temperature gas reactor and an industrial sector with the invention as described above. A coolant stream from a high-temperature gas reactor 14 (˜950° C.) or molten salt reactor (˜860° C.) heats gas in a heat exchanger 16 used as a heat source for the reverse SABR reaction in the absorber 24. The process is similar to heating the boiler 3 to provide steam to the turbine 4 of FIG. 1, but the heated gas enters the absorber 24 as an SABR reactor instead of the steam turbine. After heat is extracted, the cooling medium returns to the plant to be cycled again.

Heated inert gas drives the reverse SABR reaction, converting carbon black and metal carbonate powders into CO gas and metal oxide powder.

(HEAT+C+MCO3->2CO+MO)

CO gas is separated from the absorber (reactor) 24 using a membrane. The gas is distributed at ambient temperature via a pipeline 66 to various industrial customers 46A-46D. Metal oxide powder is distributed to the same customers via a transportation vehicle 68 such as by rail or trucking.

Onsite SABR reactors as regenerators 40 reverse the previous reaction by blowing CO gas through metal oxide powder to yield carbon black and metal carbonate powders, releasing heat in the process.

(2CO+MO->HEAT+C+MCO3)

The gaseous intermediate products of the SABR reaction (CO2) circulate through a gas-gas heat exchanger 70, preheating the intake air entering industrial combustors. Preheated air significantly reduces the fuel needed to sustain operational temperatures.

Metal carbonate powder is returned to the location of the high-temperature gas reactor 14 via a transportation vehicle 68 such as by rail or trucking.

Combustors burn natural gas in preheated air to generate steam. The steam circulates throughout the industrial facility to drive processes.

The SABR absorber 40 and heat exchanger 70 proximal to the industrial site 46 can be combined into a single skid-build system to be deployed on industrial sites. Advantageously, combustion intake air can be seamlessly routed around the SABR system, preventing shutdowns due to installation time or maintenance.

Other and further embodiments utilizing one or more aspects of the inventions described above can be devised without departing from the disclosed invention as defined in the claims. For example, various sources of heat for the chemical process activation for reversal are possible, different catalysts, and other variations than those specifically disclosed herein within the scope of the claims.

The invention has been described in the context of preferred and other embodiments and not every embodiment of the invention has been described. Obvious modifications and alterations to the described embodiments are available to those of ordinary skill in the art. The disclosed and undisclosed embodiments are not intended to limit or restrict the scope or applicability of the invention conceived of by the Applicant, but rather, in conformity with the patent laws, Applicant intend to protect fully all such modifications and improvements that come within the scope of the following claims.

HEAT ABSORPTION, TRANSPORTATION, AND REGENERATION FOR PROCESS HEAT DELIVERY USING THE SORPTION ASSISTED BOUDOUARD REACTION

Information

Publication Number

Date Filed

Date Published

Inventors

Original Assignees

CPC

International Classifications

Abstract

Description

Claims

CROSS REFERENCE TO RELATED APPLICATIONS

Provisional Applications (1)