Steam methane reforming unit for carbon capture

Abstract

A system powered by a molten carbonate fuel cell is disclosed for capturing carbon dioxide produced by a steam methane reformer system. Exhaust gas from a pressure swing adsorption (PSA) system is mixed with waste gas from the fuel cell anode, then pressurized and cooled to extract liquefied carbon dioxide. Residual low-CO2 gas is directed to an anode gas oxidizer, the anode, a reformer for fuel combustion, and / or to the PSA system. Low-CO2 flue gas from the reformer can be vented to the atmosphere or directed to the anode gas oxidizer. The reduction in the amount of CO2 reaching the fuel cell allows for fuel cell size design based on the system's power requirements and eliminates the need for additional power output.

Description

[0001] This application is a divisional application of the invention patent application filed on March 8, 2021, with application number 202180027847.7 and invention title "Steam Methane Reforming Unit for Carbon Capture".

[0002] Cross-reference of related patent applications

[0003] This application claims the benefit and priority of U.S. Provisional Application No. 62 / 987,985, filed March 11, 2020, the entire disclosure of which is incorporated herein by reference. Background Technology

[0004] This disclosure relates to a steam methane reformer (SMR). In particular, this disclosure relates to an SMR with enhanced carbon dioxide (CO2) capture.

[0005] Steam methane reformers (SMRs) are commonly used to produce syngas from gaseous feedstocks such as natural gas or refinery gas. The resulting syngas can be further processed within the plant to produce various end products, including purified hydrogen, methanol, carbon monoxide, and ammonia. However, the flue gas produced during the reforming process contains pollutants such as carbon dioxide, which are known to have adverse environmental impacts by contributing to overall climate change. SMRs are well-known as one of the largest emitters of CO2 from refineries. Therefore, in recent years, many government regulatory agencies have mandated reductions in carbon dioxide emissions into the atmosphere.

[0006] Given the awareness of the harmful effects of carbon dioxide emissions and recent restrictions on their limits, efforts have been made to efficiently remove purified forms of carbon dioxide from flue gas produced by steam reformer plants. By removing carbon dioxide from flue gas, it can be used alternatively for other, safer purposes, such as underground storage or oil production needs.

[0007] Current methods for capturing CO2 from SMR, such as removing CO2 from flue gas using amine stripping tower systems (post-combustion capture) or removing CO2 from SMR tail gas using physical or amine-based chemical solvents in stripping tower systems (pre-combustion capture), are very inefficient and costly. Stripping systems are typically too energy-intensive, requiring large amounts of steam for solvent regeneration. Recent post-combustion methods employing molten carbonate fuel cell (MCFC) technology capture CO2 from the host plant while simultaneously generating electricity. The additional electricity generated beyond the system's own needs provides a revenue stream that offsets the system's capital and operating costs. In conventional post-combustion systems, flue gas from SMR containing high CO2 levels is directed to an MCFC. Due to the high CO2 levels, this method requires a relatively large number of MCFC modules, which can be expensive and may generate more electricity than desired. Therefore, conventional MCFC-based CO2 capture systems can be very expensive and may generate excess energy that is difficult to unload. Summary of the Invention

[0008] The embodiments described herein provide an SMR-CO2 capture system for capturing CO2 from the exhaust gas of a pressure swing adsorption (PSA) system of an SMR system, which can advantageously help capture CO2 in a more efficient and cost-effective manner compared to some conventional CO2 capture systems.

[0009] In some embodiments, the system for capturing CO2 from the SMR system includes a compressor, a chiller, and a CO2 separator. Exhaust gas from the SMR system's PSA is compressed by the compressor and cooled by the chiller. The CO2 separator separates the liquefied CO2 from the remaining uncondensed gas. The uncondensed gas can then be recycled back to the SMR system's PSA and / or the SMR system's reformer for combustion as fuel.

[0010] In some embodiments, the system further includes an MCFC. Exhaust gas from the PSA can be mixed with exhaust gas from the MCFC anode before being compressed, cooled, and separated into liquid CO2 and residual gas. The residual gas can be recycled to various parts of the SMR system or a system for capturing CO2. For example, in some embodiments, a portion of the gas can be recycled to the anode gas oxidizer and then to the cathode of the MCFC, while another portion is recycled to the anode of the MCFC. In some embodiments, a third portion of the residual gas can be recycled to the PSA of the SMR system to produce more hydrogen, or recycled to a reformer in the SMR system for combustion as fuel. This third portion of the residual gas can instead be recycled to a PSA outside the SMR system. In some embodiments, a third portion of the residual gas can be recycled to the PSA of the SMR system to produce more hydrogen, and a fourth portion of the residual gas can be recycled to a reformer in the SMR system for combustion as fuel.

[0011] In some embodiments, flue gas from the reformer of the SMR system can be vented to the atmosphere. Because the exhaust gas from the PSA of the SMR system is not burned to fuel the reformer of the SMR system, the CO2 content in the flue gas is relatively low. In other embodiments, the flue gas can be directed to an anode gas oxidizer in a system for capturing CO2, and then to the cathode of the MCFC.

[0012] In some embodiments, the MCFC can be designed to power systems solely for CO2 capture, SMR systems solely, or both. Because the exhaust gas from the PSA of the SMR system is not burned to fuel the SMR system's reformer, the amount of CO2 received by the MCFC is reduced, allowing the MCFC to be designed to be smaller and reducing excess power generation.

[0013] In some embodiments, a method for capturing CO2 is provided for implementing the above system.

[0014] The foregoing is an overview of this disclosure and therefore necessarily contains simplifications, generalizations, and omissions of details. Therefore, those skilled in the art will understand that the overview is illustrative only and is not intended to be limiting in any way. Other aspects, features, and advantages of the apparatus and / or process described herein will become apparent only from the specific embodiments set forth herein and in conjunction with the accompanying drawings, as defined in the claims. Attached Figure Description

[0015] This disclosure will be more fully understood from the following detailed description, taken in conjunction with the accompanying drawings, wherein like reference numerals refer to like elements, wherein:

[0016] Figure 1 A schematic diagram of a conventional SMR-CO2 capture system is shown.

[0017] Figure 2 A schematic diagram of an SMR-CO2 capture system according to a representative embodiment of the present disclosure is shown.

[0018] Figure 3 A schematic diagram of an SMR-CO2 capture system according to another representative embodiment is shown.

[0019] Figure 4 A schematic diagram of an SMR-CO2 capture system according to yet another representative embodiment is shown.

[0020] Figure 5 A schematic diagram of an SMR-CO2 capture system according to yet another representative embodiment is shown.

[0021] Figure 6A method for capturing CO2 from an SMR according to a representative embodiment is shown. Detailed Implementation

[0022] Referring generally to the accompanying drawings, this document discloses various embodiments of enhanced SMR-CO2 capture systems capable of capturing CO2 in a more efficient and cost-effective manner compared to some conventional CO2 capture systems. The various embodiments disclosed herein can increase the amount of CO2 captured, improve the efficiency of CO2 capture, increase the amount of hydrogen produced, and / or reduce the costs associated with CO2 capture. In the various embodiments disclosed herein, the same reference numerals refer to the same elements between the figures, but are increased by 200 (e.g., ...) from one figure to another. Figure 2 PSA 450 and Figure 3 (Similar to the PSA 650, etc.).

[0023] Generally, in a typical SMR unit of an SMR-CO2 capture system, natural gas reacts with water to form hydrogen and CO2. Some methane is not converted, and some carbon monoxide is also produced in the process. These impurities, as well as any water that has not been separated by condensation, are typically removed from the hydrogen using a PSA system that desorbs these impurities at atmospheric pressure to produce a PSA tail gas that is typically high in CO2 and also contains CO, methane, and hydrogen. Typically, the PSA tail gas is recycled as fuel in the SMR unit, where it is burned with air to provide the heat required for the endothermic reforming reaction. This reaction produces flue gas with a relatively high CO2 content, which can be directed to an MCFC for subsequent CO2 capture. In this type of system configuration, the size of the MCFC is partly governed by the amount (or percentage) of CO2 transferred from the flue gas received from the SMR unit to the anode of the MCFC (e.g., 70%–90% CO2).

[0024] However, the composition of the PSA exhaust gas is very similar to that of the shift-anode exhaust gas of the MCFC in a CO2 capture system. Therefore, the applicant advantageously determined that the PSA exhaust gas can be mixed directly with the MCFC anode exhaust gas before being compressed and cooled to separate CO2 from the gas, rather than being recirculated in the SMR unit. In this way, the size of the MCFC is not dominated by the PSA exhaust gas from the SMR unit, since the CO2 typically contained in the flue gas from the PSA exhaust gas is mixed with the anode exhaust gas downstream of the MCFC for subsequent CO2 capture. Therefore, the overall system cost can be reduced by selecting a smaller MCFC that can, for example, generate just enough power for the CO2 capture system, the SMR system itself, or both's chillers and other electrical loads, as discussed in more detail below.

[0025] In some embodiments, the system can also be configured to direct flue gas from the SMR unit to the MCFC for additional CO2 capture. In some embodiments, unused fuel containing hydrogen and carbon monoxide from the MCFC anode can be directed from the CO2 capture tail gas to the PSA to increase the system's hydrogen production. In some embodiments, electricity is purchased from an external source instead of using the MCFC to power the CO2 capture system.

[0026] Figure 1 A typical SMR-CO2 capture system is shown. For example... Figure 1 As shown, steam supplied by steam supply line 210 and natural gas supplied by natural gas supply line 220 are mixed and fed to reformer 230 of reformer system 200 for converting methane into hydrogen, CO2, and CO. The reformer effluent can be conveyed to a conversion assembly of reformer system 200, where it can be cooled and most of the CO can be converted into hydrogen according to the following reaction:

[0027]

[0028] The converted gas is then fed to the PSA system 250 via shift gas line 240, where hydrogen is separated from residual methane and CO, as well as CO2 produced by the reforming and shift reactions. The residual gas is recycled as fuel to the reformer 230 via recirculation line 260, where it is burned with air supplied by air supply line 270 to provide the heat required for the endothermic reforming reaction. All CO2 produced in hydrogen production is discharged as a mixture of N2, CO2, H2O, and some NOx in the reformer flue gas.

[0029] Still referencing Figure 1 The reformer flue gas containing CO2 is fed to the AGO (anodic gas oxidizer) 110 of the CO2 capture system 100, where the flue gas is optionally combined with air from the air supply line 112 to increase the oxygen content of the flue gas to the level required for MCFC operation if necessary. The flue gas and air are heated and fed to the cathode 124 of the MCFC 120. Natural gas is supplied to the preheater 115 before being fed to the anode 122 of the MCFC 120 via the natural gas supply line 114. Due to the unique properties of MCFCs, CO32-containing gas is produced during normal MCFC power generation. ＝ The CO3 is transferred from the cathode 124 of the MCFC 120 to the anode 122. This transfer removes CO2 and O2 from the flue gas containing the cathode feed and produces cathode exhaust gas with a relatively low CO2 content, thereby reducing CO2 emissions. The CO3 transferred to the anode 122... ＝The CO reacts with hydrogen in anode 122 to form H2O and CO2, generating electricity simultaneously. During carbon capture, the effluent from anode 122 is cooled, for example, by evaporator 125, and enters a shift reactor, whereby the CO in the effluent is converted into hydrogen and CO2 via the following shift reaction:

[0030]

[0031] The outlet stream is then compressed by compressor 130 and then cooled, for example, by refrigerator 135. The compressed and cooled outlet stream is then transferred to CO2 separator 140. In the compressed and cooled outlet stream, approximately 60% to approximately 90% of the CO2 condenses into a liquid and is separated from the residual CO2 capture tail gas containing hydrogen, any unconverted CO, remaining uncondensed CO2, and methane. The residual CO2 capture tail gas is partially recirculated to anode 122 via recirculation line 142 for use as fuel in MCFC 120. The remaining portion of the residual CO2 capture tail gas is sent to AGO 110 to help prevent the buildup of inert gases such as nitrogen and to heat the gas in AGO 110 by burning the remaining hydrogen in the residual CO2 capture tail gas. This recirculation has the advantage of increasing the amount of CO2 recovered from the anode exhaust gas.

[0032] exist Figure 1 In this system, the size design of the MCFC 120 is partly based on the amount of CO2 in the flue gas to be transferred to the anode 122 (e.g., approximately 70% to approximately 90% of the CO2 in the flue gas). Therefore, Figure 1 The system configuration may be expensive to implement and may generate more electricity than expected.

[0033] Now for reference Figure 2 This illustrates an SMR-CO2 capture system comprising a CO2 capture system 300 and an SMR system 400 according to an exemplary embodiment of the present disclosure. Figure 1 Compared to other systems, the flue gas from the SMR system 400 is not directed to the MCFC for CO2 capture but is instead discharged because it typically has a low CO2 content. Instead, the SMR system 400 is configured such that the PSA exhaust gas from the PSA 450 in the SMR system 400 is directly mixed with the anode exhaust gas from the anode 322 of the MCFC 320, where the mixture can be compressed and cooled so that liquefied CO2 can be separated from the mixture to be captured. In this way, the size of the MCFC 320 is independent of the flue gas from the SMR reformer 430, allowing the MCFC 320 to be designed to provide only the power required by the CO2 capture system 300, the SMR system 400, or both, thereby reducing the overall system cost while still providing sufficient CO2 capture.

[0034] Still referencing Figure 2 Steam supplied by steam supply line 410 and natural gas supplied by natural gas supply line 420 are mixed and fed to the SMR reformer 430 of the SMR system 400 for converting methane into hydrogen, CO2, and CO. The reformer effluent can be conveyed to the shift assembly of the SMR system 400, where the effluent can be cooled and most of the CO can be converted into hydrogen. The shifted gas is then sent to the PSA 450 via shift gas line 440, where hydrogen is separated from residual methane and CO in the gas, as well as CO2 produced by the reforming and shift reactions. Residual gas from the PSA tail gas is recycled in the SMR reformer 430 as fuel, as in... Figure 1 In this system, PSA exhaust gas is directed to CO2 capture system 300 via PSA exhaust gas supply line 460 to be directly mixed with anode exhaust gas from MCFC 320's anode 322 for subsequent CO2 capture. In this way, the size of MCFC 320 is not governed by the amount of CO2 in the PSA exhaust gas to be transferred to anode 322. Therefore, the size of MCFC 320 can be designed to any specification, for example, to generate sufficient power for CO2 capture system 300, SMR system 400, or both.

[0035] Still referencing Figure 2 The mixture of anode exhaust gas and PSA tail gas is then compressed by compressor 330 and then cooled, for example, by refrigerator 335. The compressed and cooled outlet stream is then transferred to CO2 separator 340. In the compressed and cooled outlet stream, approximately 60% to approximately 90% of the CO2 condenses into liquid and is separated from the residual CO2 capture tail gas containing hydrogen, any unconverted CO, remaining uncondensed CO2, and methane. A portion of the CO2 capture tail gas is recirculated to anode 322 via recirculation line 342 to be used as fuel in MCFC 320, while a small portion of the tail gas is also sent to AGO 310 to help prevent the buildup of inert gases such as nitrogen and to heat the gas in AGO 310 by burning the remaining hydrogen in the residual CO2 capture tail gas.

[0036] exist Figure 2 In this system configuration, PSA exhaust gas is no longer directed back to the SMR reformer 430 for subsequent combustion. Therefore, natural gas can instead be used to fuel the SMR reformer 430, and, as permitted by regulations, the resulting flue gas, containing a relatively small amount of CO2, can be discharged as a mixture of N2, CO2, H2O, and some NOx. In this configuration, typically about 50% to about 60% of the CO2 emitted from the SMR is captured.

[0037] according to Figure 2In another representative embodiment shown, a portion of the residual CO2 capture tail gas can also be guided back to the SMR reformer 430 via CO2 capture tail gas supply line 344 (indicated by dashed lines / arrows). This portion of the residual CO2 capture tail gas can be used as fuel in the SMR reformer 430 to reduce the amount of natural gas required. Figure 2 As shown, this portion of the residual CO2 capture tail gas can also be recycled to PSA 450 to increase H2 production at PSA without increasing the size of SMR reformer 430. According to another representative embodiment, the MCFC 320 can be designed to use only the residual CO2 capture tail gas as fuel, thereby eliminating the need for natural gas at the MCFC 320 except for start-up and disruptive operations.

[0038] Now refer to Figure 3 This illustrates an SMR-CO2 capture system comprising a CO2 capture system 500 and an SMR system 600, according to another exemplary embodiment of this disclosure. Figure 2 Compared to other systems, in this case, flue gas from the SMR system 600 is directed along flue gas supply line 635 to the MCFC for CO2 capture, instead of being discharged. Furthermore, exhaust gas from the PSA 650 of the SMR system 600 is directed along PSA exhaust gas supply line 660 to directly mix with anode exhaust gas from the anode 522 of the MCFC 520 for CO2 capture. In this way, the size of the MCFC 520 can be designed to be smaller than that of a typical SMR-CO2 capture system (such as...). Figure 1 The system (where the exhaust gas, containing approximately 50% to 60% CO2 typically found in flue gas, is diverted to the anode exhaust gas of the MCFC because it is to be captured by the MCFC 520. Therefore, with Figure 2 Compared to other systems, this exemplary system can provide a relatively high CO2 capture, while also... Figure 1 Compared to conventional systems, it still reduces the total cost.

[0039] According to another representative embodiment, the MCFC 520 can be configured to compensate for the power consumed by the CO2 capture system 500 and the SMR system 600. In this configuration, a relatively large percentage of normal CO2 emissions (e.g., about 60% to about 70%) will still be captured by the system, but capital costs will be significantly reduced, and the need to output electricity to third parties will be eliminated or reduced.

[0040] Now for reference Figure 4 This illustrates an SMR-CO2 capture system comprising a CO2 capture system 700 and an SMR system 800 according to another exemplary embodiment of the present disclosure. Figure 4As shown, flue gas from SMR system 800 is directed along flue gas supply line 835 to cathode 724 of MCFC 720, and tail gas from PSA 850 of SMR system 800 is directed along PSA tail gas supply line 860 to directly mix with anode exhaust gas from anode 722 of MCFC 720 for CO2 capture. Unused fuel from anode 722 containing hydrogen and carbon monoxide (e.g., about 30%) and a small amount of methane can be directed from CO2 capture tail gas to PSA 850 along CO2 capture tail gas supply line 744 to increase hydrogen production in the system. In some embodiments, if, for example, PSA 850 does not have the capacity required for additional feed, CO2 capture tail gas can be sent to a separate PSA from PSA 850. In this way, this exemplary system can provide relatively high CO2 capture and increased hydrogen production while reducing overall costs.

[0041] Now for reference Figure 5 This illustrates an SMR-CO2 capture system comprising a CO2 capture system 900 and an SMR system 1000 according to another exemplary embodiment of this disclosure. Figure 5 As shown, power is received from an external source instead of using MCFCs to power the CO2 capture system 900. According to various exemplary embodiments, the external power source can be an existing power plant, a utility grid, and / or renewable energy such as solar or wind power. The exhaust gas from the PSA 1050 of the SMR system 1000 is compressed by compressor 930 and cooled by refrigerator 935, allowing the liquefied CO2 to be separated from the gas used for CO2 capture. The CO2 capture exhaust gas can be directed along the PSA exhaust gas supply line 942 to the reformer 1030 of the PSA 1050 and / or the SMR system 1000 to increase hydrogen production in the system and help prevent the accumulation of inert gases in the SMR system 1000. In this way, this exemplary system can provide a lower-cost option for CO2 capture compared to other CO2 capture systems. However, it should be understood that when estimating the CO2 reduction using this configuration, the potential amount of CO2 released by the external power source should be taken into account.

[0042] refer to Figure 6A method for implementing the above-described system is shown according to an exemplary embodiment. This exemplary method includes a mixing step 1101, in which exhaust gas from the PSA of the SMR system is mixed with anode exhaust gas from the MCFC anode; a compression step 1103, in which the mixed gas is compressed by a compressor; a cooling step 1105, in which the gas is cooled, for example, by a refrigeration unit, such that most of the CO2 is output as a liquid; a separation step 1107, in which the liquid CO2 is separated from the residual gas by a CO2 separator; a collection step 1109, in which the liquid CO2 is collected for isolation or other purposes; and a recirculation step 1111, in which the residual gas is recirculated for use in one or more of the anode gas oxidizer, the MCFC anode, the SMR as a fuel source for the reformer, and the PSA to produce hydrogen. In some embodiments, the mixing step 1101 is omitted, and the SMR exhaust gas is treated without mixing with the anode exhaust gas, particularly when an external power source is used instead of the MCFC.

[0043] According to a representative embodiment, exhaust gas from the PSA in the SMR system is directly mixed with anode exhaust gas from the MCFC anode. This mixture can be compressed, and its temperature is lowered by a chiller, allowing liquefied CO2 to be separated from the mixture for capture. Unlike some conventional SMR-CO2 capture systems, CO2 from the SMR system's reformer combustor, i.e., the flue gas from the SMR system, is not directed to the MCFC for CO2 capture. In this way, the size of the MCFC is independent of the flue gas from the SMR reformer, but is controlled by the CO2 captured from the PSA exhaust gas, thereby reducing the overall system cost while still providing CO2 capture.

[0044] According to another representative embodiment, flue gas from the SMR system is fed to the cathode of the MCFC, and exhaust gas from the PSA of the SMR system is directly mixed with anode exhaust gas from the MCFC anode for CO2 capture. In this way, the MCFC can be designed to be smaller than a typical SMR-CO2 capture system because the exhaust gas containing approximately 50% to 60% CO2 typically present in the flue gas is instead directed to the anode exhaust gas of the MCFC. Therefore, this exemplary system can provide relatively high CO2 capture while reducing the overall system cost.

[0045] According to another representative embodiment, flue gas from the SMR system is fed to the cathode of the MCFC, and tail gas from the PSA of the SMR system is directly mixed with anode exhaust gas from the MCFC anode for CO2 capture. From the MCFC anode, after CO2 removal, a portion of the unused fuel containing hydrogen and carbon monoxide (CO) can be directed from the CO2 capture tail gas to the PSA to increase the system's hydrogen production. In this way, this exemplary system can provide relatively high CO2 capture and increased hydrogen production while reducing the overall system cost.

[0046] According to another representative embodiment, the exhaust gas from the PSA of the SMR system is compressed, and its temperature is lowered by a refrigerator using an external power source (and, in the case of an absorption chiller, an external heat source), allowing liquefied CO2 to be separated from the gas used for CO2 capture. Unused fuel from the CO2 capture exhaust gas containing hydrogen, CO, residual CO2, and other non-condensable gases can be directed to the PSA to increase the system's hydrogen production, and / or to the reformer of the SMR system, helping to prevent the accumulation of inert gases in the SMR system. In this way, this exemplary system can provide a lower-cost option for CO2 capture compared to some conventional SMR-CO2 capture systems.

[0047] This document discloses various embodiments of an enhanced SMR-CO2 capture system that captures CO2 in a more efficient and cost-effective manner compared to some conventional CO2 capture systems using MCFCs. The various embodiments disclosed herein can increase the amount of CO2 captured, improve the efficiency of CO2 capture, increase the amount of hydrogen produced, and / or reduce the costs associated with CO2 capture.

[0048] As used herein, the terms “about,” “approximately,” “generally,” and similar terms are intended to have a broad meaning consistent with common and accepted usage by one of ordinary skill in the art to which the subject matter of this disclosure pertains. Those skilled in the art who have examined this disclosure will understand that these terms are intended to allow for the description of certain features described and claimed, without limiting the scope of these features to the precise numerical ranges provided. Therefore, these terms should be interpreted as indicating that non-substantial or insignificant modifications or alterations to the described and claimed subject matter are considered to fall within the scope of the invention as set forth in the appended claims.

[0049] As used herein, the terms “coupled,” “connected,” etc., mean that two components are joined together directly or indirectly. Such a connection can be static (e.g., permanent) or movable (e.g., removable or releasable). Such a connection can be achieved by the two components or two components and any additional intermediate components forming a single whole with each other, or by the two components or two components and any additional intermediate components attaching to each other.

[0050] References to the position of elements (e.g., "top", "bottom", "above", "below", etc.) herein are used only to describe the orientation of the various elements in the accompanying drawings. It should be noted that the orientation of the various elements may differ according to other exemplary embodiments, and such variations are intended to be covered by this disclosure.

[0051] It is important to note that the construction and arrangement of the various exemplary embodiments are illustrative only. While only a few embodiments are described in detail in this disclosure, those skilled in the art will readily understand that many modifications are possible (e.g., variations in the size, dimensions, structure, shape and proportions, parameter values, installation arrangements, use of materials, color, orientation, etc.) of various elements without substantially departing from the novel teachings and advantages of the subject matter described herein. For example, an element shown as integrally formed may be composed of multiple parts or elements, the positions of elements may be reversed or otherwise varied, and the nature, number, or position of discrete elements may be altered or varied. The order or sequence of any process or method steps may be varied or rearranged according to alternative embodiments. Other substitutions, modifications, alterations, and omissions may also be made in the design, operating conditions, and arrangements of the various exemplary embodiments without departing from the scope of the invention. For example, the heat recovery heat exchanger may be further optimized.

Claims

1. A system for generating hydrogen and capturing carbon from natural gas, the system comprising: A molten carbonate fuel cell, comprising an anode and a cathode; A steam methane reformer system, comprising a reformer and a pressure swing adsorption system configured to produce exhaust gas; A carbon dioxide capture system, comprising: A compressor configured to compress a gas mixture, the gas mixture comprising an anode exhaust gas stream from the anode and the tail gas; A refrigeration unit configured to cool the gas mixture; and A carbon dioxide separator is configured to separate the gas mixture into a mixture of liquefied carbon dioxide and residual gas; and An anodic gas oxidizer configured to receive and oxidize at least a portion of the residual gas mixture, wherein the cathode is configured to receive the oxidized gas from the anodic gas oxidizer.

2. The system of claim 1, wherein the anode of the molten carbonate fuel cell is configured to receive a portion of the residual gas mixture.

3. The system of claim 2, wherein the reformer is configured to receive a portion of the residual gas mixture as fuel for combustion.

4. The system according to any one of claims 1 to 3, wherein the pressure swing adsorption system is configured to receive hydrogen and separate the hydrogen from a portion of the residual gas mixture.

5. The system according to any one of claims 1 to 3, wherein the reformer is configured to generate flue gas, which is discharged into the atmosphere.

6. The system according to any one of claims 1 to 3, wherein the anode gas oxidizer is configured to receive flue gas from the reformer and oxidize the flue gas.

7. The system according to any one of claims 1 to 3, further comprising a second pressure swing adsorption system outside the steam methane reformer system, the second pressure swing adsorption system being configured to receive a portion of the residual gas mixture.

8. The system of claim 1, wherein the molten carbonate fuel cell is sized to provide an amount of power equal to the combined power consumed by the steam methane reformer system and the carbon dioxide capture system.

9. The system of claim 1, wherein the molten carbonate fuel cell is sized to provide an amount of electricity equal to the electricity consumed by either the carbon dioxide capture system or the steam methane reformer system.

10. The system of claim 1, further comprising an evaporator and a shift reactor, the evaporator being configured to cool the anode exhaust gas stream, and the shift reactor being configured to convert carbon monoxide in the anode exhaust gas stream into carbon dioxide before the anode exhaust gas stream is mixed with the tail gas.

11. The system of claim 1, wherein the molten carbonate fuel cell is sized to operate using only the residual gas mixture supplied to the anode as fuel.

12. A method for capturing carbon dioxide from a steam methane reformer system, the method comprising: The natural gas in the reformer is reformed to produce a reformed gas stream that includes hydrogen. A pressure swing adsorption system is used to separate hydrogen from the reformed gas stream to generate a hydrogen stream and exhaust gas. The exhaust gas is mixed with the anode exhaust gas from the anode section of a molten carbonate fuel cell to form a gas mixture; Compress the gas mixture; Cooling the gas mixture; The gas mixture is separated into a mixture of liquefied carbon dioxide and residual gas; A first portion of the residual gas mixture is directed to the anode gas oxidizer; The first portion of the oxidized residual gas mixture; and The residual gas mixture to be oxidized is directed to the cathode portion of the molten carbonate fuel cell.

13. The method of claim 12, further comprising: The flue gas from the reformer is oxidized using the aforementioned anode gas oxidizer; and The oxidized flue gas is directed from the anode gas oxidizer to the cathode portion of the molten carbonate fuel cell.

14. The method of claim 12, further comprising: At least a portion of the residual gas mixture is directed to the anode portion of the molten carbonate fuel cell.

15. The method according to any one of claims 12 to 14, further comprising: A portion of the residual gas mixture is directed to the reformer and combustible gases in the residual gas mixture are burned to supply heat to the reformer.

16. The method of claim 15, further comprising: The flue gas from the reformer is discharged into the atmosphere.

17. The method according to any one of claims 12 to 14, further comprising: A portion of the residual gas mixture is mixed with the reformed gas stream into the pressure swing adsorption system, and hydrogen is separated from the reformed gas stream and the portion of the residual gas mixture.

18. The method according to any one of claims 12 to 14, further comprising: The carbon monoxide in the anode exhaust gas is converted into carbon dioxide.

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