Patent Description:
Conventional methods for hydrogen generation and/or power production result in significant dilute CO<NUM> flue streams. Producing clean H<NUM> or power often requires adding costly cleanup systems to concentrate or capture the CO<NUM> in the flue stream so that it is suitable for sequestration. Currently, this processing of flue gases is cost prohibitive.

Current methods of producing clean H<NUM> are therefore much higher in cost than the incumbent method of steam methane reforming (SMR) which produces significant dilute CO<NUM> emissions. Prior art <CIT> discloses a direct carbon fuel cell (DCFC) based arrangement for producing electric power and H<NUM> gas, running on hydrocarbon fuel and using a plasma or dissociation reactor for separating the fuel into H2 gas as a bi-product and molten carbon for the DCFC.

There is therefore a need in the art to produce clean industrial H<NUM> at a cost at or better than existing methods.

According to the invention, there is provided, according to claim <NUM>, a system for producing hydrogen and generating electrical power, comprising: a heat exchanger; a hydrocarbon dissociation reactor; a carbon separator; a direct carbon fuel cell (DCFC) comprising an anode and an electrolyte flow field; and a fluid circulation system configured to: circulate a hydrocarbon fuel source to the heat exchanger for heating the hydrocarbon fuel source in the heat exchanger; circulate the heated hydrocarbon fuel source to the hydrocarbon dissociation reactor for decomposing the hydrocarbon fuel source into hydrogen and carbon; circulate the hydrogen and carbon to the carbon separator for separating the carbon from the hydrogen; circulate a molten carbonate electrolyte to the carbon separator for mixing with the separated carbon to form a slurry; circulate the slurry to the electrolyte flow field of the DCFC for converting in the anode of the DCFC at least some carbon comprised in the slurry to carbon dioxide and electrical power, thereby forming a carbon-depleted slurry; circulate the carbon-depleted slurry away from the DCFC; and circulate one or more of the carbon-depleted slurry, the molten carbonate electrolyte, and carbon dioxide from the DCFC to the heat exchanger.

The invention provides further improvements according to the dependent claims <NUM>-<NUM>, as well as a corresponding method according to claim <NUM>.

The system may comprise any of the features described herein, and in particular any of the features described above in connection with the method for producing hydrogen.

This summary does not necessarily describe the entire scope of all aspects. Other aspects, features and advantages will be apparent to those of ordinary skill in the art upon review of the following description of specific embodiments.

Embodiments of the disclosure will now be described in detail in conjunction with the accompanying drawings of which:.

The present disclosure seeks to provide an improved method of producing hydrogen and generating electrical power. While various embodiments of the disclosure are described below, the disclosure is not limited to these embodiments, and variations of these embodiments may well fall within the scope of the disclosure which is to be limited only by the appended claims.

The present disclosure describes a Tri-Generation Pyrolysis (TGP) technology designed to produce industrial-scale, clean H<NUM>, electrical power, heat, and a pure stream of CO<NUM> that can be either easily sequestered or sold as a feedstock to other industrial processes. According to some embodiments, the TGP comprises a hydrogen dissociation reactor (HDR), a direct carbon fuel cell (DCFC), a molten carbonate carbon separator (MCCS), and a multi-stream heat exchanger (MSHX). An objective is to maximize the efficiency of the TGP by optimizing the integration of the HDR, the DCFC, the MCCS, and the MSHX.

Conventional high-temperature carbon fuel cell designs that are based on a molten carbonate electrolyte tend to have a captive electrolyte constrained within a porous separator matrix between an anode and a cathode. The electrolyte is static and does not flow in or out of the fuel cell. In such a cell, cooling is performed by the cathode flow of oxidant and carbon dioxide. Such cells are prone to electrolyte loss and degradation which necessitates frequent servicing. Flowing a common electrolyte to the fuel cells in parallel mitigates problematic electrolyte servicing and enables a direct medium to manage the temperature of the fuel cell. Flowing an electrolyte further enables a higher degree of system integration when a solid carbon fuel is supplied by an HDR.

Key challenges of integrating such a system include the effective separation of the solid carbon from the HDR product stream and its delivery to the DCFC. Efficiently providing the heating and cooling requirements of various subsystems presents additional challenges. The present disclosure proposes a novel integration of the carbon carrier function to fuel the DCFC, the carbon separation function from the HDR, the pre-heating function of the hydrocarbon feedstock to the HDR, and the cooling function of the DCFC.

Throughout this disclosure, the term "direct carbon fuel cell" (DCFC) may refer to a fuel cell using a carbon-rich material as a feedstock or fuel. The DCFC may generate energy using carbon and oxygen, with carbon dioxide as a by-product.

Throughout this disclosure, the term "pyrolysis" may refer to the act of decomposing material at elevated temperatures in an inert atmosphere.

Throughout this disclosure, the term "electrolyte" may refer to a substance that possesses ionic conductance properties.

Throughout this disclosure, the term "PSA" may refer to pressure swing adsorption, which is a technique used for purifying gases such as hydrogen.

Embodiments of the disclosure may provide for the generation of hydrogen, power, high-grade heat, and a near pure stream of CO<NUM>. Furthermore, embodiments of the disclosure may provide for the integration of: a hydrocarbon dissociation reactor producing both solid carbon and a hydrogen (H<NUM>) rich gas; a direct carbon fuel cell (DCFC) that uses the produced carbon to generate electrical power and heat; a carbon separator; and a gas separator that separates the solid carbon and purifies the H<NUM> from the gas mixture exiting the hydrogen dissociation reactor.

Embodiments of the disclosure may assist in producing clean H<NUM> and clean dispatchable electrical power at a cost at or lower than the incumbent technologies. A tri-generation pyrolysis process (TGP) or TGP-like system, according to embodiments of the disclosure, can be deployed at sites requiring low cost and clean industrial H<NUM> such as upgrading/refining operations, ammonia and other chemical production, steel and glass making, etc., as well as for low-cost clean transportation and for large-scale H<NUM> export applications. In addition, a TGP or TGP-like systems, according to embodiments of the disclosure, can be deployed to produce clean electric power for dispatchable applications.

Embodiments of the disclosure may perform hydrogen dissociation which may comprise a pulsed methane pyrolyzer (PMP) to convert a hydrocarbon feedstock into carbon and an H<NUM>-rich gas. The PMP may be a pyrolyzer as described in co-pending PCT Patent Application No. <CIT>, in the name of Ekona Power Inc. , and entitled "Method and Reactor for Producing One or More Products". For example, the PMP may comprise a feedstock gas reactor comprising: a mixing chamber; a combustion chamber; valving for controlling flow of gases into and out of the mixing chamber and the combustion chamber; an igniter; and one or more controllers configured to perform a method comprising: controlling the valving to introduce a feedstock gas (such as CH<NUM> and O<NUM> (or air)) into the mixing chamber, wherein the feedstock gas comprises one or more gases; controlling the valving to introduce a combustible gas into the combustion chamber, wherein the combustible gas comprises one or more gases; and thereafter, controlling the igniter to ignite the combustible gas so as to cause the combustible gas to flow into the mixing chamber via one or more fluid flow paths between the combustion chamber and the mixing chamber, and to mix with the feedstock gas, wherein energy is transferred from the combustible gas to the feedstock gas and thereby causes one or more products to be produced. The one or more products may comprise carbon, H<NUM>-rich syngas (H<NUM>, CH<NUM>, CO, CO<NUM>), H<NUM><NUM>, and nitrogen.

A molten salt carbon carrier may be used in a DCFC and may also be used to separate the carbon and the H<NUM>-rich gas from the PMP. The same molten salt/carbon carrier may be used to transfer heat to the hydrocarbon input of the PMP. The DCFC may be a DCFC as described in co-pending PCT Patent Application No. <CIT>, in the name of Ekona Power Inc. , and entitled "Molten Carbonate Direct Carbon Fuel Cell Systems and Methods". For example, the DCFC may comprise: a plurality of fuel cells, each fuel cell comprising a porous fuel cell anode and a fuel cell cathode; a molten carbonate electrolyte; a fuel supply apparatus for flowing a fuel slurry comprising carbon particles and a carbon carrier fluid to the fuel cell anodes in parallel, wherein the carbon carrier fluid has a same composition as the molten carbonate electrolyte; an oxidant supply apparatus for flowing an oxygen-containing stream to the fuel cell cathodes in parallel; and an electrolyte circulation apparatus for circulating the molten carbonate electrolyte in contact with each of the plurality of fuel cells, wherein, during operation of the direct carbon fuel cell system to generate electric power, carbon is oxidized at the fuel cell anodes to produce carbon dioxide, and at the fuel cell cathodes oxygen and carbon dioxide react to produce carbonate ions.

Embodiments of the disclosure may use a pulsed methane pyrolyzer (PMP) for a hydrogen dissociation reactor. Furthermore, according to embodiments of the disclosure, there is described a system that integrates the separation of carbon and H<NUM>-rich gas with electrolyte and fuel feeds for the DCFC, pre-heating of the hydrocarbons into the PMP, and cooling for the DCFC.

According to embodiments of the disclosure, the DCFC reactor may be externally fuelled with, for example, a slurry mixture of carbon and molten salt electrolyte.

According to embodiments of the disclosure, the system may integrate the separation of carbon and H<NUM>-rich gas by using a molten electrolyte and/or molten carbon carrier to separate the carbon from the H<NUM>-rich gas and for combining the carbon fuel feed with the molten electrolyte to be fed to the DCFC. As well, the molten electrolyte / carbon carrier stream may be used for cooling the DCFC and the pre-heating of the hydrocarbon feedstock into the dissociation reactor.

According to embodiments of the disclosure, the PMP may use a single stage thermal pyrolysis reaction to convert feedstock hydrocarbons into carbon and H<NUM>-rich gas. According to embodiments of the disclosure, the system may also comprise a DCFC to produce electrical power and high-grade heat.

Each embodiment of the present disclosure may offer one or more of the following: optimization of the separation of solid carbon from the H<NUM> and other gases that have exited the PMP; optimization of the mixing of the solid carbon with a molten electrolyte (or other suitable carbon carrier fluid) as a fuel for the DCFC anode; and optimization of the heat utilization and cooling requirements among the PMP, DCFC, MCCS and hydrogen gas separator.

Producing industrial H<NUM> at a cost at or better than the incumbent process may require the co-generation of valuable commodities to offset the cost of the clean H<NUM> production. According to embodiments of the disclosure, a Tri-Generation Pyrolysis (TGP) technology may be used produce industrial H<NUM>, electrical power, high-grade heat, and a pure stream of CO<NUM> that can be either easily sequestered or sold as a feedstock to other industrial processes. The TGP may include a PMP, DCFC, carbon separator, and hydrogen gas separator configured to provide an integrated process. The efficiency of the TGP can be maximized by optimizing the integration of the PMP and DCFC, and the carbon separator and hydrogen gas separator.

Referring to <FIG> which depicts a tri-generation pyrolysis process (TGP) <NUM> according to an embodiment of the disclosure, H<NUM>-rich gas and solid carbon are produced in the PMP <NUM> from a suitable hydrocarbon feedstock <NUM> (e.g. natural gas (NG)). The carbon and the H<NUM>-rich gas are separated in the carbon management subsystem <NUM> after which the H<NUM>-rich gas stream is fed to a gas separator <NUM> where the H<NUM> is purified to industrial process specifications. The rejected gas from the gas separator <NUM> is recycled back to the PMP <NUM> where some is burned to provide the heat of reaction required for the thermal pyrolysis process. The carbon is fed to the DCFC <NUM> by means of a carbon management subsystem <NUM> where it is combined with the carbon carrier and fed to the DCFC anode. Oxygen, O<NUM>, is introduced via air to the cathode of the DCFC <NUM> and the carbon and O<NUM> are electrochemically converted into electrical power, heat, and a pure stream of CO<NUM> <NUM>.

Some challenges of integrating such a system may relate to efficiently separating and managing the carbon fuel, and efficiently providing the heating and cooling requirements of the various subsystems. Embodiments of the disclosure may involve a process that integrates the functions of the various TGP subsystems to substantially reduce the overall complexity and cost. Specifically, embodiments of the disclosure may integrate (a) the carbon carrier function to fuel the DCFC anode, (b) the carbon separation function from the PMP <NUM>, (c) the pre-heating function of the hydrocarbon feedstock to the PMP <NUM>, and (d) the cooling function of the DCFC <NUM>.

Each embodiment of the present disclosure offers one or more of the following: optimization of the separation of solid carbon from the H<NUM> and other gases that have exited the PMP; optimization of the mixing of the solid carbon with a molten electrolyte (or other suitable carbon carrier fluid) as a fuel for the DCFC anode; and optimization of the heat utilization and cooling requirements among the PMP, DCFC, MCCS and hydrogen gas separator.

Referring to <FIG>, there are shown according to an embodiment of the disclosure a molten carbonate carbon separator (MCCS) <NUM> and a multi-stream heat exchanger (MSHX) <NUM> for integrating a hydrocarbon dissociation pulsed methane pyrolysis reactor (PMP) <NUM> with a DCFC <NUM>. In particular, MCCS <NUM> uses a circulating molten fuel mediator that is the same as the DCFC electrolyte from the DCFC <NUM> to simplify separating the carbon from H<NUM>-rich gas exiting the PMP <NUM> and to simplify the mixing of the carbon with the molten electrolyte, enabling the continuous carbon fuelling function of the DCFC <NUM>. There is further depicted a Molten Electrolyte Carbon Separator <NUM> that uses a circulating molten carbon carrier (fuel mediator) to simplify the separation of the carbon from H<NUM>-rich gas that exits the PMP <NUM> and to simplify the mixing of the carbon with the molten carbon carrier, improving the carbon delivery to the DCFC <NUM>. MSHX <NUM> is designed to pre-heat the input hydrocarbon fuel and oxidizing feedstocks <NUM> to the PMP <NUM> with the hot circulating molten electrolyte <NUM> and/or carbon carrier fluid and CO<NUM> <NUM> exiting the DCFC <NUM> and to cool the circulating molten electrolyte and/or carbon carrier fluid to provide the required cooling to the DCFC <NUM>.

Feedstock hydrocarbons <NUM> are preheated by the hot molten salt electrolyte <NUM> and CO<NUM> <NUM> exiting the DCFC <NUM>. These hot hydrocarbons are then introduced into the PMP <NUM>. At the same time, the hot molten salt electrolyte and/or carbon carrier fluid is cooled providing a required heat sink for the circulating electrolyte DCFC operation. The molten salt electrolyte and/or carbon carrier fluid <NUM> is pumped to the MCCS <NUM>. The solid carbon and the produced H<NUM>-rich gas <NUM> from the PMP <NUM> are sent into the bottom of the molten salt column of the MCCS <NUM> where the H<NUM>-rich gas <NUM> bubbles to the surface and exits to the H<NUM> separator PSA to produce industrial grade H<NUM>. In some embodiments, the contents of the MCCS <NUM> are stirred in order to entrain the carbon into the electrolyte.

The solid carbon is (i) mixed with the molten electrolyte in the MCCS <NUM> to form a slurry <NUM> that is sent as fuel to the anode <NUM> of the DCFC <NUM>, or (ii) skimmed off the top of the molten electrolyte column to be formed into solid carbon fuel to be delivered as fuel to the anode <NUM> of the DCFC <NUM>, or (iii) used as a solid carbon product for other applications.

According to the embodiment of <FIG>, the hydrogen dissociation reactor is a pulsed methane pyrolyzer (PMP) <NUM> producing H<NUM>-rich gas and solid carbon <NUM>. The DCFC <NUM> uses a molten carbonate (MC) electrolyte that circulates through the MCCS <NUM>. The carbon and the H<NUM>-rich gas <NUM> from the PMP <NUM> are sent to the MCCS <NUM> where they are mixed with the molten carbonate electrolyte, the H<NUM>-rich gas <NUM> is separated from the carbon, and the remaining carbon and molten carbonate form a carbon/molten carbonate slurry <NUM>. This carbon/molten carbonate slurry is pumped to the DCFC <NUM> where it operates both as the electrolyte and as the carbon fuel for the anode <NUM>. Some of the carbon is consumed in the DCFC <NUM> and the carbon-depleted carbon/molten carbonate slurry <NUM> is pumped back to the MCCS <NUM> where more carbon and H<NUM>-rich gas from the PMP <NUM> are introduced, and the process continues.

The pure CO<NUM> product <NUM> is separated from the depleted carbon/molten carbonate slurry in a gas separator <NUM> and is also cooled by the MSHX <NUM> and compressed by a CO<NUM> compressor <NUM> for export or sequestration.

According to some embodiments, the DCFC <NUM> has separate anode and electrolyte flow fields and inlet headers <NUM> to which the carbon/molten carbonate slurry are individually delivered. Alternately, the DCFC <NUM> only inputs the carbon/molten carbonate slurry to the electrolyte flow field <NUM> where the fuel slurry is supplied. The slurry in this embodiment serves as both the cell electrolyte and mediated fuel for the cell. In some cases, all or a portion of the slurry penetrates and flows through the DCFC anode electrodes <NUM> and is independently collected at the outlet of the DCFC <NUM>.

According to some embodiments, the molten carbonate electrolyte, and/or carbon/molten carbonate slurry and the CO<NUM> produced in the DCFC <NUM> is used to pre-heat the hydrocarbon fluid feedstock going into the PMP <NUM>. This enables the system to be more efficient by lowering the energy requirement for the PMP <NUM> and providing the needed cooling for the DCFC <NUM>.

The flow of the molten carbonate electrolyte and/or carbon/molten carbonate slurry may be at different pressures, for example, and at temperatures above the solidification temperature of the molten electrolyte.

With reference to <FIG> which shows a variation of the embodiment of <FIG>, only a portion of the molten carbonate electrolyte passes through the MCCS <NUM> that is used to separate the H<NUM>-rich gas and mixed with the carbon to produce the carbon/molten carbonate slurry. This slurry <NUM> is then sent to the anode <NUM> of the DCFC <NUM> and kept separate from the pure molten carbonate electrolyte <NUM>. The carbon depleted slurry <NUM> is then returned to the MCCS <NUM> forming a separate loop from the pure molten carbonate electrolyte.

The DCFC electrolyte <NUM> is circulated through the DCFC <NUM> and the MSHX <NUM> by an independent molten carbonate pump <NUM> and buffered in an independent holding tank <NUM>. In this embodiment, the DCFC fuel slurry and circulating electrolyte are independent fluid streams but each deliver heat to the MSHX <NUM>. According to this embodiment, the molten carbonate DCFC electrolyte is maintained carbon-free but is still circulated for heat removal from the DCFC <NUM>.

The DCFC <NUM> produces electrical power, high-grade heat, and a mostly pure stream of CO<NUM> by electrochemically converting the carbon in the carbon/molten carbonate slurry feed at the anode <NUM> and the O<NUM> from the air at the cathode. Most of the carbon is consumed in the DCFC <NUM> and the carbon-depleted hot carbon/molten carbonate slurry <NUM>, and hot CO<NUM> <NUM> is pumped to a multi-stream heat exchanger <NUM> where the PMP feedstocks (natural gas and oxidant) are preheated before going into the PMP, and the molten carbonate electrolyte is cooled for the DCFC operation. From the MSHX <NUM>, the cooler molten carbonate electrolyte <NUM> is pumped to the MCCS <NUM> where more carbon and H<NUM>-rich gas from the PMP are introduced. The process may then be repeated.

Referring to <FIG>, there is shown another embodiment where the carbon and the H<NUM>-rich gas <NUM> are sent to the MCCS <NUM>. The carbon is not mixed with the molten carbonate electrolyte but rather floats to the top of the molten carbonate liquid column and is skimmed off, or filtered out. The method of skimming (or filtering) the carbon may be performed according to any of various suitable methods and may use any of various suitable systems. By way of example, an active carbon skimmer <NUM> may be driven by a prime mover <NUM> and ejected from the MCCS <NUM>. The solid carbon can be moved by carbon management equipment such as a conveyor <NUM> to be further processed as a DCFC fuel. Various carbon processing methods may include forming the carbon into an aggregated solid carbon form <NUM> for use as a fuel for the DCFC anode or for mixing with another fluid carrier <NUM>, such as CO<NUM>, prior to introduction to the DCFC anode. The solid carbon may alternately be removed from the system and processed and/or exported for other applications.

In general, unless otherwise indicated, singular elements may be in the plural and vice versa with no loss of generality.

Throughout the description, specific details have been set forth in order to provide a more thorough understanding of the disclosure. However, the disclosure may be practiced without these particulars. In other instances, well-known elements have not been shown or described in detail and repetitions of steps and features have been omitted to avoid unnecessarily obscuring the disclosure. Accordingly, the specification is to be regarded in an illustrative, rather than a restrictive, sense.

Claim 1:
A system for producing hydrogen and generating electrical power, comprising:
a heat exchanger (<NUM>);
a hydrocarbon dissociation reactor (<NUM>);
a carbon separator (<NUM>);
a direct carbon fuel cell, DCFC, (<NUM>) comprising an anode and an electrolyte flow field; and
a fluid circulation system configured to:
circulate a hydrocarbon fuel source to the heat exchanger for heating the hydrocarbon fuel source in the heat exchanger;
circulate the heated hydrocarbon fuel source to the hydrocarbon dissociation reactor for decomposing the hydrocarbon fuel source into hydrogen and carbon;
circulate the hydrogen and carbon to the carbon separator for separating the carbon from the hydrogen;
circulate a molten carbonate electrolyte to the carbon separator for mixing with the separated carbon to form a slurry;
circulate the slurry to the electrolyte flow field of the DCFC for converting in the anode of the DCFC at least some carbon comprised in the slurry to carbon dioxide and electrical power, thereby forming a carbon-depleted slurry;
circulate the carbon-depleted slurry away from the DCFC; and
circulate one or more of the carbon-depleted slurry, the molten carbonate electrolyte, and carbon dioxide from the DCFC to the heat exchanger.