Method of producing of hydrogen and carbon monoxide using a fuel cell

Abstract

A method to produce streams of hydrogen and carbon monoxide uses the exhaust stream of a fuel cell with a methane pyrolizer and a carbon dioxide pyrolizer. The fuel cell uses natural gas and atmospheric air as input streams and produces electric and thermal energy, and an exhaust stream of CO2 and steam. A methane pyrolizer, powered by the fuel cell, produces hydrogen and a carbon stream as a feedstock for a carbon dioxide pyrolizer. A carbon dioxide pyrolizer reacts CO2 from the fuel cell with carbon supplied from the methane pyrolizer to produce carbon monoxide. The streams of hydrogen and carbon monoxide may be used as syngas to produce a desirable petrochemical.

Description

METHOD OF PRODUCING OF HYDROGEN AND CARBON MONOXIDE USING A FUEL CELLFIELD

[0001] This relates to a method of producing hydrogen and carbon monoxide, and in particular a method that uses a methane pyrolizer and a carbon dioxide pyrolizer with a fuel cell.BACKGROUND

[0002] A common starting point for making petrochemicals is the creation of synthesis gas (syngas), a mixture of carbon monoxide and hydrogen. Syngas may be produced using known methods, typically including energy intensive catalytic processes with high GHG (greenhouse gas) emissions. Increased focus on mitigating the effects of climate change challenges industry to reduce GHG emissions in the production of syngas. Steam Methane Reforming (SMR) and Autothermal Reforming (ATR) are widely used and proven at scale to produce high carbon emissions syngas, both methods require additional carbon capture infrastructure and capital investment carbon capture and storage (CCS).SUMMARY

[0003] According to an aspect, there is provided a method of producing components for syngas that may be mixed in suitable proportions for the production of petrochemicals using a fuel cell with a methane pyrolizer and a carbon dioxide pyrolizer to produce hydrogen and carbon monoxide. This may be done at near zero GHG emissions.

[0004] The method enables the use of carbon dioxide to produce carbon monoxide - a useful reactant in a wide spectrum of industrial processes. A fuel cell is used to convert natural gas into electricity and carbon dioxide. The electricity from the fuel cell is used as an energy source for the pyrolizers and the carbon dioxide in the exhaust of the fuel cell is used as afeedstock for the carbon dioxide pyrolizer. A methane pyrolizer is used to convert methane (natural gas) into hydrogen and carbon. The methane may be diverted from the fuel stream connected to the fuel cell. A carbon dioxide pyrolizer is used to react carbon dioxide produced in the fuel cell with carbon produced in methane pyrolizer to produce carbon monoxide.

[0005] A carbon dioxide stream from an anode exhaust stream of the fuel cell may be cooled, separated, condensed, recovered, pumped, and / or heated prior to being reacted in the carbon dioxide pyrolizer with a carbon stream that may be produced in a methane pyrolizer to produce a rich carbon monoxide stream. This carbon monoxide product may be used as a feedstock in various petrochemicals processes. Features of the process may include the generation of electrical energy from natural gas, recovery of process generated CO2 and its conversion into carbon monoxide.

[0006] According to an aspect, the method may include recovering CO2 and thermal energy from a fuel cell anode exhaust stream and using electrical energy generated by the fuel cell to power a methane pyrolizer to produce hydrogen and carbon from an input stream of methane gas. The fuel cell may also provide electrical energy for a carbon dioxide pyrolizer, which may be used to produce carbon monoxide from the reaction of the carbon dioxide recovered from the fuel cell with carbon from the methane pyrolizer. In some implementations, this may be done at near zero GHG emissions.

[0007] The process of generating power with a natural gas fuel cell differs from standard power generation plants that use natural gas. In a fuel cell, natural gas is consumed at the anode through an electrochemical reaction that produces electricity and a hot exhaust stream of gases, mainly water vapor and carbon dioxide whereas in combustion-based power generation plants the exhaust stream is mainly nitrogen oxides, with water and carbon dioxide being minor components by mass and or volume in the combustion exhaust stream. The fuel cell anode exhaust stream is mainly carbon dioxide and water vapor which combined is less than 75% of the exhaust mass flow rate of power generation combustion process. The concentrated fuel cell anode exhaust stream with its thermal energy is an ideal source to recover and convert carbon dioxide into value added products. The anode exhauststream is a by-product of producing electricity with a fuel cell. The thermal energy of this anode exhaust gas stream is typically partially recovered in cogeneration processes to supply heat before the exhaust gas is released into the atmosphere.

[0008] According to an aspect, the method may include the following features:• Power generation by chemical reaction of natural gas in a fuel cell.• No GHG emissions released into the atmosphere, the fuel cell anode exhaust stream and its thermal energy is fully recovered to produce water and carbon dioxide.• Production of water, the anode chemical reaction by stoichiometry produces 2.25 Kg of water per Kg of methane.• Production of carbon dioxide, the anode chemical reaction by stoichiometry produces 2.75 Kg of carbon dioxide per Kg of methane.• Recovering a fuel cell anode exhaust stream thermal energy to heat; carbon dioxide, water and natural gas.• Recovering a fuel cell cathode exhaust stream thermal energy to heat; steam, natural gas and atmospheric air.• Recovery and efficient production of carbon dioxide, water and nitrogen.• Production of hydrogen and carbon by methane pyrolysis.• Reducing carbon dioxide from a fuel cell with carbon from a methane pyrolizer to produce carbon monoxide.• Conversion of nitrogen from a fuel cell and hydrogen from a methane pyrolizer into ammonia through catalytic processes.• Production of selective H2:CO ratios from methane pyrolizer hydrogen stream and carbon dioxide pyrolizer carbon monoxide stream.• A method where a fuel cell is both an energy provider (thermal + electrical) and a producer of carbon dioxide, water and nitrogen for other petrochemical uses, a methane pyrolizer a producer of hydrogen and carbon and a carbon dioxide pyrolizer a producer of carbon monoxide.• A method to produce petrochemicals at near zero GHG emissions.

[0009] In some examples, the process may uses a fuel cell to produce electricity for use and / or export and recovers the thermal energy and components of its exhaust streams for other uses. The process for the recovery of CO2 as a feedstock may comprise one or more of the following features:• Reducing the pressure of a natural gas supply to the methane pyrolizer and fuel cell anode pressure through an expander generator to produce electricity and a refrigerant natural gas stream.• Passing the refrigerant natural gas stream through a series of heat exchangers in a counter-current flow with the fuel cell gaseous anode exhaust stream to cool and condense the water and carbon dioxide components.• Causing the natural gas supply stream to give up its generated coolth energy in a series of counter-current heat exchangers to cool and condense the anode exhaust gaseous stream while simultaneously preheating the natural gas to the anode exhaust temperature.• Inputting the heated natural gas supply stream into the fuel cell anode where it is converted, such as by steam reforming and electrochemical reactions, into electricity and a high temperature anode exhaust gas stream that is primarily carbon dioxide and water.• Pre-cooling the high temperature anode exhaust gas stream in a counter-current flow heat exchanger with by the natural gas supply stream.• Cooling the anode exhaust gas stream further in a counter-current flow heat exchanger by the recovered carbon dioxide stream.• Recovering the condensed water fraction of the anode exhaust gas stream in a gas / liquid separator and routing the separated anode exhaust gaseous carbon dioxide stream for further cooling in a counter-current heat exchanger with the recovered liquid carbon dioxide stream.• Cool the carbon dioxide from the anode exhaust stream further in a countercurrent heat exchanger with a cold carbon dioxide gaseous stream.• Cool carbon dioxide from the anode exhaust stream further in a counter-currentheat exchanger with a refrigerant natural gas supply stream to cool and condense a portion of the anode exhaust carbon dioxide.• Pressurizing the recovered liquid carbon dioxide stream using a pump passing the pressurized stream through a counter-current heat exchanger with the anode exhaust stream to heat the pressurized stream.• Pumping and pressurizing the recovered water stream and passing it through a counter-current heat exchanger with the anode exhaust stream.• Mixing the gaseous carbon dioxide stream from the carbon dioxide separator with fresh air and catalysing it in a catalytic oxidizer to heat the oxidant stream up to fuel cell cathode temperature. The cathode converts oxygen from the air into an oxygen ion that is transferred through the fuel cell electrolyte layer to the anode to react and produce water, carbon dioxide and electricity.• Routing a portion of the recovered water to produce steam in a counter-current flow heat exchanger with the cathode exhaust gas stream to supply steam reformer at the anode.• Pre-cooling the high temperature cathode exhaust gas stream in a counter-current flow heat exchanger using natural gas fuel stream for the fuel cell anode.• Further cooling the cathode exhaust stream in a counter-current flow heat exchanger using the steam stream supplied to the fuel cell anode.• Further cooling the cathode exhaust stream in a counter-current flow heat exchanger using atmospheric air supplied to the fuel cell cathode.• Using electricity generated by the fuel cell as the heat source for methane pyrolizer, reactors and or electric devices to meet energy requirements of the processes.• Using a fuel cell that produces electricity, water, carbon dioxide and nitrogen. The products recovered from the fuel cell, including thermal and electrical energy, may be combined with a methane pyrolizer to produce feed streams of hydrogen and carbon monoxide that may be converted into various petrochemical products at near zero GHG emissions.

[0010] The method may recover the components and thermal energy of a fuel cell exhaust streams and, combined with a methane pyrolizer, use the electrical energy from the fuel cell to produce hydrogen and carbon monoxide as feedstocks.

[0011] According to other aspects, the method may operate at a site where natural gas is readily available. The recovered components of carbon dioxide, water and nitrogen, combined with methane pyrolizer products of hydrogen and carbon, and the carbon dioxide pyrolizer product of carbon monoxide, may be used as petrochemical feedstocks and / or products. The electricity and / or thermal energy produced in the process may also provide power and thermal energy requirements of petrochemical processes. The method may provide for the production of petrochemicals at near zero GHG emissions.

[0012] The above-described method may be used to recover thermal energy and fuel cell exhaust streams that, combined with a methane pyrolizer and a carbon dioxide pyrolizer, may be used to produce petrochemicals feedstocks. The process recovers and converts carbon dioxide (a GHG emission gas), using a methane pyrolizer and a carbon dioxide pyrolizer to produce valuable hydrogen and carbon monoxide products.

[0013] As will hereinafter be further described, there is provided a method to produce petrochemical products and feedstocks from fuel cell exhaust streams, which includes a natural gas supply stream to a methane pyrolizer and a fuel cell. The method may include the following features:• the natural gas pressure may be reduced through a gas expander / generator to produce a refrigerant natural gas stream and electricity.• The refrigerant natural gas stream may be pre-heated in a series of counter-current heat exchangers to cool and condense carbon dioxide and water from a fuel cell anode exhaust stream.• The heated fuel cell natural gas stream may be further heated and fed to the fuel cell anode where first it is steam reformed to produce hydrogen and carbon dioxide.• The hydrogen may be further reacted with oxygen ions to produce water and electricity.• The hot carbon dioxide anode exhaust gas stream component may be cooled, condensed, separated, recovered, pressurized and heated for a reduction reaction.• The cathode exhaust stream of mainly nitrogen, may be cooled, separated and recovered for other uses, such as ammonia synthesis.• An electric methane pyrolizer, powered by electricity supplied by the fuel cell may chemically reduce methane into hydrogen and carbon.• The methane-pyrolizer-produced carbon may be reacted with the fuel cell recovered carbon dioxide in a carbon dioxide pyrolizer to produce carbon monoxide.• The methane-pyrolizer-produced hydrogen and the carbon dioxide-pyrolizer- produced carbon monoxide products may be mixed at desirable T^CO ratios to produce various petrochemicals, or the produced hydrogen stream may also be reacted with fuel cell produced nitrogen to produce ammonia, etc.

[0014] The method described above may be implemented to combine a fuel cell with a methane pyrolizer and a carbon dioxide pyrolizer to produce various products from a natural gas feed stream efficiently at near zero GHG emissions.

[0015] According to an aspect, there is provided a method of operating a fuel cell to condense, recover, pump and heat a fuel cell exhaust streams of carbon dioxide, water and nitrogen, and to produce electrical and thermal energy that, combined with a methane pyrolizer and a carbon dioxide pyrolizer, generate segregated hydrogen and carbon monoxide streams that, selectively mixed at desirable ratios, produce a syngas feedstock to manufacture a desired petrochemical at near zero GHG emissions, the method comprising: providing a pressurized natural gas supply stream to a fuel cell and to a methane pyrolizer unit; providing a gas expander / generator to produce electricity and a refrigerant natural gas supply stream as per the Joules Thompson effect when decreasing pressure of a gas stream; providing a series of heat exchangers or cold box to condense carbon dioxide from a fuel cell anode exhaust stream; providing a second heat exchanger to heat the fuel cell natural gas stream for mixing with steam and reforming at a fuel cell anode; providing an air stream for mixing with gaseous carbon dioxide and unreacted residuals from the fuel cell anode exhaust stream and pre-heat in acatalytic oxidizer to meet temperature of the fuel cell cathode; providing a fuel cell for power generation fuelled by natural gas; providing a series of heat exchangers on the fuel cell anode exhaust stream to condense the steam component of the stream; providing a separator to recover the condensed water and separate the gaseous carbon dioxide and unreacted residuals for further cooling; providing a series of heat exchangers to condense the carbon dioxide stream exited from the water separator; providing a separator to recover the condensed carbon dioxide and separate the unreacted residuals; providing a pump to pressure the recovered liquid carbon dioxide to downstream petrochemical units operating pressures; providing a series of heat exchangers to heat the liquid carbon dioxide for carbon dioxide pyrolizer unit; providing a pump to pressure the recovered water condensate to produce steam for mixing with the heated supply of natural gas for the fuel cell anode reformer; providing a second pump to pressure the net water condensate produced in the fuel cell anode for export; and providing a series of heat exchangers to heat the steam condensate for export.

[0016] According to other aspects, the method may include one or more of the following features, alone or in combination: the separated carbon dioxide and unreacted residuals may be compressed to meet desired operations properties as per the pressure enthalpy diagram of the stream; a Joules-Thompson valve may be employed in lieu of a expander / generator; the transmission natural gas supply may be boosted and then cooled by ambient air heat exchange to increase the refrigeration properties of the natural gas supply stream; a refrigeration plant may be added to increase the refrigeration properties of the natural gas supply stream; the natural gas supply may be liquid natural gas (LNG) in lieu of a pressurized natural gas supply; an external source of carbon dioxide may be added to the fuel cell produced carbon dioxide stream; an external source of nitrogen may be added to the fuel cell produced nitrogen stream; the method may be employed at an existing gas processing plant or at a straddle gas plant; the electricity generated in the fuel cell may be the energy source for the methane pyrolizer and carbon dioxide pyrolizer; and the produced streams of hydrogen and carbon monoxide may be mixed at a ratio to produce an optimum syngas feedstock to produce a desirable petrochemical, or may be used as feedstocks in various industries.

[0017] In other aspects, the method may be used to combine a methane pyrolizer with a fuel cell to produce hydrogen and carbon at near zero GHG emissions, where a fuel cell anode exhaust streams of carbon dioxide and its thermal energy may recovered and employed to react with carbon from a methane pyrolizer in a carbon dioxide pyrolizer to produce carbon monoxide. Energy from a fuel cell, including electrical and thermal, may be combined with its co-products of carbon dioxide, provide the means to meet proven methane pyrolyzer and carbon dioxide pyrolizer processes inputs to generate segregated streams of hydrogen and carbon monoxide at near zero GHG emissions.

[0018] According to an aspect, there is provided a method of producing hydrogen and carbon monoxide, comprising the steps of operating a fuel cell to produce electricity, thermal energy, and an exhaust stream that comprises at least carbon dioxide and water, the fuel cell receiving a fuel stream of natural gas and a stream of atmospheric air as inputs; obtaining a stream of carbon dioxide by cooling the exhaust stream to condense the water and separating the carbon dioxide in a separator; operating a methane pyrolyzer to convert a stream of methane into hydrogen and a carbon stream, such as solid carbon; operating a carbon pyrolyzer to convert the carbon stream and the stream of carbon dioxide to produce carbon monoxide; wherein the methane pyrolyzer and the carbon pyrolyzer are powered by the electricity, the thermal energy, or both the electricity and the thermal energy produced by the fuel cell.

[0019] According to other aspects, the method may comprise one or more of the following aspects, alone or in combination: the hydrogen produced by the methane pyrolyzer and the carbon monoxide produced by the carbon pyrolyzer may be combined in a predetermined ratio to produce a hydrocarbon feedstock for a hydrocarbon generator; the stream of methane may be obtained from the fuel stream of natural gas; and the thermal energy of the produced by the fuel cell may be used to preheat reactant streams of the carbon pyrolyzer and the methane pyrolyzer.

[0020] According to other aspects, the features described above may be combined in any suitable combination as will be recognized by those skilled in the art.BRIEF DESCRIPTION OF THE DRAWINGS

[0021] These and other features will become more apparent from the following description in which reference is made to the appended drawings, the drawings are for the purpose of illustration only, wherein:FIG. l is a schematic diagram of a fuel cell, depicting the recovery of water, carbon dioxide, nitrogen and thermal energy from the exhaust stream.FIG. 2 is a schematic diagram of an alternative natural gas pressure expansion that expands a stream of natural gas to meet fuel cell pressure requirements and another stream to meet the pressure requirements of a methane pyrolizer.FIG. 3 is a schematic diagram of a method to produce hydrogen and carbon monoxide using a fuel cell, a methane pyrolizer, and a carbon dioxide pyrolizer.FIG. 4 is a schematic diagram of a method to produce methanol by using streams of carbon dioxide and steam produced in the fuel cell with natural gas.FIG. 5 is a schematic diagram of methods to produce various petrochemical feedstocks and products from streams of carbon dioxide, nitrogen and water produced at a fuel cell, supported with electrical energy produced by the fuel cell.FIG. 6 is a schematic diagram of further methods to produce various petrochemical feedstocks and products from streams of carbon dioxide, nitrogen and water produced at a fuel cell supported with electrical energy produced by the fuel cell.DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0022] A method of operating a fuel cell to produce petrochemical feedstocks will now be described with reference to FIG. 1 to FIG. 6. This method may be used to recover and convert exhaust streams from a fuel cell into petrochemical feedstocks and other products at near zero GHG emissions. The method uses heat exchangers to recover thermal energy from an exhaust stream to separate and / or condense components while using the recovered thermal energy to preheat and / or produce input streams for the fuel cell, or as petrochemical feedstocks and / or products. As such, the system is designed to use the exhaust streams, electricity, and thermal energy produced by the fuel cell system to separate, recover, and / or convert hot exhaust gasstreams from the fuel cell into petrochemical feedstocks and products, which may be done at near zero GHG emissions. The exhaust gas streams of a fuel cell, typically discharged into the atmosphere as a by-product of power generation, are therefore recovered and used to produce petrochemical feedstocks and products at near zero GHG emissions. The description of application of the systems and methods below will, therefore, be considered examples.

[0023] In the methods described herein, suitable fuel cells may include Solid Oxide Fuel Cells (SOFC) manufactured by Bloom and Fuel Cell Energy in the USA, as well as other type of fuel cell such as Molten carbonate fuel cells, polymer electrolyte membrane fuel cells, or other fuel cells readily available in the market may be used. A major advantage of fuel cell power generation plants versus standard power generation combustion process plants is the separated and highly concentrated mass flow rate of the exhaust gas streams allowing for ease of recovery and use.

[0024] Referring to FIG. 1, an example of a method that may be used to recover water, carbon dioxide, and thermal energy from a fuel cell anode exhaust stream to produce a carbon dioxide stream for deoxidation with carbon to produce carbon monoxide is shown. The method uses natural gas input stream 1 as a refrigerant. As shown, input stream 1 is natural gas delivered from a main transmission pipeline through stream 1 that enters an expander / generator 2 to reduce the pressure from the main transmission pipeline pressure to meet a required inlet pressure for fuel cell 100 in expanded natural gas stream 3, and to reduce the temperature of expanded natural gas stream 3 relative to stream 1. Expander / generator 2 also generates electricity that may be used to power other equipment discussed below, or as a power source for other purposes. The temperature of stream 3 may be decreased by 1.5 to 2 degrees Celsius for every 15-psi pressure drop.

[0025] The cooler natural gas stream 3 enters heat exchanger 4 to give up its coolth energy to stream 58. The natural gas stream 5 is heated in heat exchanger 6 by anode exhaust stream 38. Natural gas stream 7 is further heated in heat exchanger 8 as anode exhaust stream 31 is cooled. The heated natural gas stream 9 is split into streams 10 and 11. The heated natural gas stream 11 is routed to a methane pyrolizer, as shown in FIG. 3 and discussed below. A portionof natural gas stream 10 may be routed to catalytic air pre-heater 23 in stream 15 to combust any unreacted hydrocarbons or hydrogen in stream 63. The balance of stream 10, the natural gas feed to the fuel cell 100, is further heated in heat exchanger 12 by fuel cell cathode exhaust stream 26. The heated fuel cell gas stream 13 is mixed with steam stream 45, and enters the fuel cell anode section 47, through anode feed stream 46. At fuel cell anode 47, the natural gas / steam stream 46 is first reformed to produce hydrogen and carbon dioxide. Anode feed stream 46, which is made up primarily of natural gas and steam, is conditioned prior to entering anode section 47, during which an appropriate pressure and temperature are achieved. The natural gas and steam may be pressurized and heated as separate streams, as a combined stream, or partly while separated, and then completed after they are combined.

[0026] Through an electrochemical reaction with an oxygen ion produced in cathode 25 and transferred through an electrolyte layer to the anode 47, the hydrogen produces electricity stream 69. A hot anode exhaust stream 31 exits anode 47. The main components of hot anode exhaust stream 31 are steam and carbon dioxide, with some unreacted residuals of hydrogen and natural gas. Hot anode exhaust stream 31 enters heat exchanger 8 to give up some of its heat to natural gas stream 7, and the cooler anode exhaust stream 32 is further cooled in heat exchanger 33 to give up more of its heat to carbon dioxide stream 67 to generate high temperature carbon dioxide stream 68. The cooler anode exhaust stream 34, is further cooled in heat exchanger 35 by water stream 43 to generate low pressure steam streams 44 and 48. The cooler anode exhaust stream 36, is further cooled in heat exchanger 37 by overhead unreacted hydrogen and residual hydrocarbons stream 62. The cooler anode exhaust stream 38, is further cooled in heat exchanger 6 by natural gas stream 5 and enters separator 40 to separate and collect the condensed water component of the anode exhaust stream 39. The concentrated carbon dioxide anode exhaust stream 49, exits separator 40 and is pressurized by compressor 51, followed by cooling in air cooled fin / fan 52. The air-cooled concentrated carbon dioxide stream 53 is further cooled in heat exchanger 19 by atmospheric air supply stream 18. The cooler concentrated carbon dioxide stream 54 is further cooled in heat exchanger 55 by unreacted hydrogen and hydrocarbon residuals gaseous stream 61. The colder concentrated carbon dioxide anode exhaust 56 is further cooled in heat exchanger 57 by liquid carbondioxide stream 66 and further cooled in heat exchanger 4 by expanded natural gas stream 3. The cold concentrated carbon dioxide anode exhaust stream 59 enters carbon dioxide separator 60 where the condensed carbon dioxide is separated from the gaseous fractions. The gaseous cold unreacted residuals stream 61 enters heat exchanger 55 to give up some of its coolth to anode exhaust stream 54, the warmer stream 62 is further heated in heat exchanger 37 by anode exhaust stream 36, the heated gaseous unreacted residuals stream 63 is mixed with air stream 22 at air pre-heater 23 where the unreacted residuals are catalytically oxidized and the oxidant stream 24 is heated to a temperature of cathode 25, such that it becomes the cathode feed stream 24. Other heating and pressuring steps may be required to properly condition cathode feed stream 24. Air stream 22 may be obtained by pressurizing atmospheric air stream 14 in a compressor 16, and then cooled in air cooled fin / fan 17. Pressurized atmospheric air stream 18 is then heated in heat exchanger 19 by concentrated carbon dioxide stream 53 and stream 20 is further heated in heat exchanger 21 by cathode exhaust stream 29. The fuel cell cathode 25, converts oxygen from oxidant stream to produce an oxygen ion for transfer through an electrolyte to the fuel cell anode 47. Cathode 25 produces a hot cathode exhaust stream that exits through stream 26, and is composed of mainly nitrogen with residuals of carbon dioxide, water vapour and oxygen. Hot cathode exhaust stream 26 enters heat exchanger 12 to heat fuel cell natural gas feed stream 10, The cathode exhaust stream 27 is further cooled in heat exchanger 28, heating fuel cell anode reformer steam supply stream 44 and is further cooled in heat exchanger 21 by atmospheric air supply 20 to air pre-heater 23. The cooled cathode exhaust stream 30 may be separated downstream (not shown) to recover nitrogen for other uses. Where nitrogen is used to produce petrochemicals, the nitrogen obtained from cathode exhaust stream 30 may be supplemented by, or replaced by, an external source of nitrogen (not shown). A water stream 41 recovered from separator 40 enters pump 42 and pumped into stream 43, routed to heat exchanger 35 to produce 2 steam streams. A first steam stream 44 is recycled through heat exchanger 28 and heated steam stream 45 is mixed with heated fuel cell gas stream 13 to enter a reformer of fuel cell anode 47. A second steam stream 48 is routed to other uses. A carbon dioxide liquid stream 64 recovered from carbon dioxide separator 60, is routed to pump 65 and pressurized to a carbon deoxidation reactor pressure. Pressurized carbon dioxide liquid stream is heated in heat exchanger 57 by colder concentrated carbon dioxide anode exhaust 56.The cooled pressurized liquid carbon dioxide stream 67 is routed through heat exchanger 33 where it is further heated by anode exhaust stream 32. Once properly conditioned, the heated and pressurized carbon dioxide stream 68 is routed to the carbon reduction reactor, as discussed below.

[0027] In other implementations, expander / generator 2 may be replaced by a Joules- Thompson valve (not shown). In yet another implementation, input stream 1 may be a cold, low pressure stream of natural gas, such as LNG (liquid natural gas). In such a case, expander / generator 2 may not be required. While the examples discussed above permit the method to be implemented with all cooling energy being generated by, or derived from, input stream 1, in other examples, an external source of cooling energy may be used to enhance the available cooling energy. In one implementation, supplemental cooling equipment may be provided as an external refrigeration plant (not shown) that cools stream 1, 3, 5, and / or 7, such as by using a heat exchanger. In another implementation, the cooling equipment may include a compressor, an air-exchanger, and an expander connected to stream 1, 3, 5, and / or 7 in series (not shown). These considerations may also be incorporated into the other examples discussed below.

[0028] The process may be used to recover and separate the components of fuel cell exhaust streams by condensation in counter current heat exchange process configuration, and to produce streams for other uses by pressurizing and heating the recovered liquids in a counter current heat exchange process configuration.

[0029] Referring to FIG. 2, the method may differ from the example shown in FIG. 1 by routing a portion of natural gas stream 1 through a dedicated gas expander 200 to reduce the gas pressure in stream 201 to the pressure requirements of a methane pyrolizer. The expanded gas pyrolizer stream 201 is further heated in heat exchangers 6 and 8 and routed to a methane pyrolyzer through stream 203. The variations related to approaches to cooling natural gas stream 1 may also apply to the separated portion of natural gas.

[0030] Referring to FIG. 3, the method combines a fuel cell 100 with a methane pyrolizer 300 and a carbon dioxide pyrolizer 304. While FIG. 3 is depicted as receiving the produced streams from the system shown in FIG. 1, it will be understood that FIG. 3 may be adapted to also receive the additional pyrolizer stream 201 shown in FIG. 2. The fuel cell 100 generates electricity to power electric methane pyrolizer 300 and carbon dioxide pyrolizer 304. The fuel cell 100 also generates the carbon dioxide stream 68 for the electric carbon dioxide pyrolizer 304. Methane pyrolysis uses heat to breakdown methane (natural gas) into hydrogen and carbon. The carbon produced in the methane pyrolysis unit 300 is fed into a carbon dioxide pyrolizer 304 to reduce carbon dioxide to carbon monoxide. The reduction of carbon dioxide with carbon to generate carbon monoxide is known and defined by Boudard’s work. This is an endothermic reaction, as carbon dioxide pyrolysis uses heat to breakdown carbon dioxide into carbon monoxide and oxygen, and the oxygen reacts with carbon to produce another mole of carbon monoxide. A feature of the proposed process is the possibility of producing hydrogen and carbon monoxide at near zero GHG emissions, which may be used to generate optimum H2:CO syngas ratios for desirable petrochemical processes.

[0031] The proposed method uses a natural gas stream 11, preheated by fuel cell anode exhaust stream 31 (as shown in FIG. 1 and FIG. 2), and routed to an electric methane pyrolizer 300. As methane pyrolysis is an endothermic reaction, electricity generated by the fuel cell 100 is delivered through electrical supply line 301 to methane pyrolizer 300 to provide the thermal energy for the pyrolysis to breakdown methane into hydrogen and carbon. The use of electricity to power electric methane pyrolizer 300 and maintain an endothermic reaction to enable the production of hydrogen and carbon monoxide at near zero GHG emissions in methane pyrolizer 300. The produced hydrogen stream 302 leaves methane pyrolizer 300 for other downstream processes and or uses. Any excess electricity 307 may be supplied to other loads.

[0032] Carbon dioxide stream 68, which was condensed, separated, recovered, pressurized and heated from a fuel cell anode exhaust stream 31 (as shown in FIG. 1 and FIG. 2), may be routed to electric carbon dioxide pyrolizer 304. As carbon dioxide pyrolysis is an endothermic reaction, electricity generated by the fuel cell 100 is delivered through electrical supply line 305 to carbon dioxide pyrolizer 304 to provide the thermal energy to reduce the pre-heated carbondioxide stream 68 with carbon stream 303 supplied by methane pyrolizer 300. The use of electricity to power electric carbon dioxide pyrolizer 304 to maintain an endothermic reaction to enable the production of carbon monoxide at near zero GHG emissions in a carbon dioxide pyrolizer 304. The produced carbon monoxide stream 306 leaves carbon dioxide pyrolizer 304 for other downstream processes and or uses. The pyrolizers used in the method preferably use direct microwave heating without creating a plasma or requiring a catalyst.

[0033] The hydrogen and carbon monoxide produced according to the method are produced with near zero GHG emissions and generate optimum H2:CO syngas ratios for desirable petrochemical processes.

[0034] The high-quality hydrogen and carbon monoxide streams, including the optimum generation of H2:CO syngas ratios, may be used to produce various petrochemicals at near zero GHG emissions, examples of which are discussed below.

[0035] Referring to FIG. 4, the method may use the produced hydrogen and carbon monoxide streams to produce methanol. The proposed method uses carbon monoxide stream 401 ratioed with hydrogen stream 402 at 2:1 mol ratio of H2:CO syngas as a feedstock to a methanol synthesis unit 400, powered by electricity stream 403 to produce a methanol stream 404. The reactants and energy produced by the fuel cell 100, methane pyrolizer and a carbon dioxide pyrolizer enables the method to produce methanol at near zero GHG emissions. While FIG. 4 is depicted as receiving the produced streams from the system shown in FIG. 1, it will be understood that FIG. 4 may be adapted to also receive the additional pyrolizer stream 201 shown in FIG. 2.

[0036] Referring to FIG. 5, a variation of the method of FIG. 4 is shown, which uses the produced hydrogen and carbon monoxide to produce acetic acid. The method uses carbon monoxide stream 501 ratioed with hydrogen stream 502 at 1: 1 mol ratio of H2:CO syngas as a feedstock to an acetic acid synthesis unit 500 to produce an acetic acid stream 504. Acetic acid synthesis unit may require electricity delivered through electrical supply line 503. The reactants and energy produced by a fuel cell 100, methane pyrolizer and a carbon dioxide pyrolizerenables the method to produce acetic acid at near zero GHG emissions. While FIG. 5 is depicted as receiving the produced streams from the system shown in FIG. 1, it will be understood that FIG. 5 may be adapted to also receive the additional pyrolizer stream 201 shown in FIG. 2.

[0037] Referring to FIG. 6, a variation of the method of FIG. 5 is shown, which uses of the produced hydrogen and carbon monoxide streams to produce liquid fuels and lubricants via the Fisher-Tropsch process. The method uses carbon monoxide stream 601 ratioed with hydrogen stream 602 at 2.1 : 1 mol ratio of FF CO syngas as a feedstock to a Fischer-Tropsch (FT) process unit 600 to produce liquid fuel / lubricant stream 604. FT process unit 600 may require electricity delivered through electrical supply line 603. The reactants and energy produced by a fuel cell 100, methane pyrolizer and a carbon dioxide pyrolizer enables the method to produce liquid fuels and lubricants at near zero GHG emissions. While FIG. 6 is depicted as receiving the produced streams from the system shown in FIG. 1, it will be understood that FIG. 6 may be adapted to also receive, or alternatively receive, the additional pyrolizer stream 201 shown in FIG. 2. In addition, carbon dioxide stream 68 may be supplemented, or replaced, by an external source of carbon dioxide, and

[0038] The method described herein combines the use of a fuel cell with a methane pyrolyzer and a carbon dioxide pyrolizer to produce segregated streams of hydrogen and carbon monoxide. As may be appreciated, these hydrogen and carbon monoxide streams may be provided in any ratio to achieve a syngas feedstock suitable for producing a desired petrochemical. As the syngas feedstocks are produced from the exhaust of a fuel cell, it may be accomplished at near zero GHG emissions.

[0039] The method may therefore be used to efficiently recover CO2 and thermal energy from a fuel cell anode exhaust stream, generate electricity without emitting carbon dioxide, conduct methane pyrolysis to produce hydrogen and carbon, and conduct carbon dioxide pyrolysis with carbon from the methane pyrolysis step to produce carbon monoxide.

[0040] The examples described above are some of the many possible application of the method of using a fuel cell, methane pyrolizer and carbon dioxide pyrolizer to produce petrochemical feedstocks and products from two single inputs; natural gas and atmospheric air. The method may be used for the efficient production of other petrochemical products at near zero GHG emissions.

[0041] In this patent document, the word "comprising" is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article "a" does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one of the elements.

[0042] The scope of the claims should not be limited by the embodiments set forth in the examples, but should be given a broad purposive interpretation consistent with the description as a whole.

Claims

What is Claimed is:

1. A method of producing hydrogen and carbon monoxide, comprising: operating a fuel cell to produce electricity, thermal energy, and an exhaust stream that comprises at least carbon dioxide and water, the fuel cell receiving a fuel stream of natural gas and a stream of atmospheric air as inputs; obtaining a stream of water and a stream of carbon dioxide by cooling the exhaust stream to condense and separate the water prior and further cooling the exhaust stream to condense and separate at least a portion of the carbon dioxide; operating a methane pyrolyzer to convert a pyrolizer stream of natural gas into hydrogen and a carbon stream; and operating a carbon pyrolyzer to convert the carbon stream and the stream of carbon dioxide to produce carbon monoxide; wherein the methane pyrolyzer and the carbon pyrolyzer are powered by the electricity produced by the fuel cell.

2. The method of claim 1, wherein the hydrogen produced by the methane pyrolyzer and the carbon monoxide produced by the carbon pyrolyzer are combined as a syngas.

3. The method of claim 2, wherein the syngas has a predetermined ratio of the hydrogen and the carbon monoxide, and further comprising the step of operating a petrochemical generator to produce a petrochemical from the syngas.

4. The method of claim 1, wherein the pyrolizer stream of natural gas is separated from the fuel stream of natural gas.

5. The method of claim 1, wherein the thermal energy produced by the fuel cell is used to preheat the stream of carbon dioxide upstream of the carbon pyrolizer and the pyrolizer stream of natural gas upstream of the methane pyrolyzer.

6. The method of claim 1, wherein the fuel stream of natural gas is generated from a refrigerant stream of natural gas, the refrigerant stream of natural gas being used to cool theexhaust stream.

7. The method of claim 1, wherein at least a portion of the stream of water is heated to produce a stream of steam, the stream of steam being combined with the fuel stream of natural gas prior to form an anode fuel stream.

8. A method to produce hydrogen and carbon monoxide using a fuel cell fuelled by an anode feed stream and a cathode feed stream, the method comprising the steps of: operating a fuel cell to produce electricity and an exhaust stream that comprises carbon dioxide and water; providing a refrigerant natural gas stream; obtaining a separated stream of water and a separated stream of carbon dioxide by: cooling the exhaust stream in a series of heat exchangers to condense and separate the water; and further cooling the exhaust stream in a further series of heat exchangers to condense and separate at least a portion of the carbon dioxide; wherein a remaining portion of the exhaust stream comprises a stream of carbon dioxide and residuals; passing the refrigerant natural gas stream through at least some of the series of heat exchangers and / or at least some of the further series of heat exchangers as a cooling stream and to produce a heated natural gas stream; separating the heated natural gas stream into a fuel cell feed stream and a pyrolizer feed stream; forming the anode feed stream by combining a steam stream and the fuel cell feed stream; generating hydrogen and carbon monoxide by: heating and pressurizing the separated stream of carbon dioxide to produce a pyrolizer stream of carbon dioxide; using a methane pyrolizer, producing hydrogen and a carbon stream from a pyrolizer stream of natural gas; and using a carbon pyrolizer, producing carbon monoxide from the carbon stream andthe stream of carbon dioxide; wherein the methane pyrolizer and the carbon pyrolizer are powered by the electricity produced by the fuel cell.

9. The method of claim 8, wherein producing the anode feed stream comprises: heating and pressurizing a portion of the separated stream of water to produce the steam stream; and mixing an atmospheric air stream with the stream of carbon dioxide and residuals to produce the cathode feed stream; wherein the anode feed stream and the cathode feed stream are preconditioned to operating conditions of the fuel cell.

10. The method of claim 8, wherein the cathode feed stream is pre-heated in a catalytic oxidizer11. The method of claim 8, wherein the pyrolizer stream of natural gas is obtained from the refrigerant natural gas stream.

12. The method of claim 8, wherein the refrigerant natural gas stream is a stream of liquid natural gas.

13. The method of claim 8, further comprising the step of using thermal energy in a cathode exhaust stream to condition the anode feed stream and the cathode feed stream, the cathode exhaust stream comprising nitrogen.

14. The method of claim 8, wherein providing the refrigerant natural gas stream comprises expanding a pressurized natural gas supply stream, such that the refrigerant natural gas stream has a lower pressure and temperature than the pressurized natural gas supply stream.

15. The method of claim 14, where the pressurized natural gas supply stream is expanded using an expander / generator that generates electricity, or a Joules-Thompson valve.

16. The method of claim 14, further comprising cooling the pressurized natural gassupply stream or the refrigerant natural gas stream using a refrigeration plant.

17. The method of claim 14, employed at a gas processing plant or a straddle gas plant, and wherein the pressurized natural gas supply stream is obtained from the gas processing plant or the straddle gas plant.

18. The method of claim 8, where the methane pyrolizer and the carbon dioxide pyrolizer are powered by electricity generated by the fuel cell.

19. The method of claim 8, where the hydrogen and carbon monoxide are mixed at a predetermined ratio to produce syngas suitable for producing a desired petrochemical.

20. The method of claim 8, where the hydrogen and carbon monoxide are captured and transported for use as feedstocks.

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