Hydrogen-producing fuel cell system and method of operating same

Abstract

A hydrogen-producing fuel cell system and a method of operating the system. The method includes initiating supply of a stored hydrogen stream including stored hydrogen to a fuel cell stack. Prior to the initiation, the stored hydrogen is stored in a low pressure hydrogen storage tank at a hydrogen storage pressure. The method also includes utilizing the fuel cell stack to generate a power output from the stored hydrogen. The method further includes monitoring a hydrogen supply variable during a supply time interval following the initiation, which indicates a flow rate of the stored hydrogen stream to the fuel cell stack. The method also includes detecting a change in the hydrogen supply variable, and responding to the detection. The system includes a controller programmed to perform the method.

Description

[0001] Cross - reference to related applications

[0002] This application claims the priority of U.S. Patent Application No. 17 / 889,295, filed on August 16, 2022, the entire content of which is incorporated herein by reference. Technical field

[0003] The present disclosure generally relates to a hydrogen - producing fuel cell system and / or a method of operating such a system. Background art

[0004] A hydrogen - producing fuel cell system uses a hydrogen - producing device, such as a fuel reformer, to produce hydrogen from a carbon - containing feedstock. The hydrogen - producing fuel cell system also includes at least one fuel cell stack configured to produce an electrical output from the hydrogen produced by the hydrogen - producing device. Some hydrogen - producing fuel cell systems are used as a backup or supplementary source of electrical output, for example, to supplement or backup a primary electrical output source such as a power grid. Some hydrogen - producing fuel cell systems that include a plurality of fuel cell stacks selectively utilize a fuel cell stack among the plurality of fuel cell stacks, for example, in response to the electrical output demand of the hydrogen - producing fuel cell system or the load applied to the hydrogen - producing fuel cell system. In both scenarios, when starting the protection of the electrical output of the fuel cell stack after a period during which the fuel cell stack does not produce an electrical output, the hydrogen - producing fuel cell system may not be properly configured to deliver hydrogen to the fuel cell stack. Therefore, there is a need for an improved hydrogen - producing fuel cell system and / or a method of operating the hydrogen - producing fuel cell system. Summary of the invention

[0005] A hydrogen - producing fuel cell system (HPFCS) and a method of operating the same. The method includes initiating a supply of a stored hydrogen stream (which includes stored hydrogen) to a fuel cell stack. Before the initiating, the stored hydrogen is stored in a low - pressure hydrogen storage tank at a hydrogen storage pressure. The method also includes using the fuel cell stack to produce an electrical output from the stored hydrogen. The method further includes monitoring a hydrogen supply variable during a supply time interval after the initiating, the hydrogen supply variable indicating the flow rate of the stored hydrogen stream to the fuel cell stack. The method also includes detecting a change in the hydrogen supply variable and responding to the detection.

[0006] The system includes a feedstock delivery system configured to provide a feedstock stream that includes a carbonaceous feedstock. The system also includes a fuel processing assembly configured to receive the feedstock stream and produce from the feedstock stream a product hydrogen stream that includes produced hydrogen. The system also includes at least one fuel cell stack configured to receive the gas and produce an electrical output from the hydrogen. The system further includes a low-pressure hydrogen storage tank configured to receive at least a portion of the product hydrogen stream and store the portion of the product hydrogen stream as stored hydrogen. The system further includes a stored hydrogen supply conduit configured to deliver a stored hydrogen stream (which includes stored hydrogen from the low-pressure hydrogen storage tank) to the at least one fuel cell stack. The system also includes a controller programmed to control the operation of the HPFCS in accordance with the method. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 Depicts an example of a hydrogen production and consumption assembly according to the present disclosure.

[0008] Figure 2 A flowchart depicting an example of a method of operating a hydrogen production fuel cell system according to the present disclosure.

[0009] Figure 3 Is a graph schematically depicting the magnitude of a hydrogen supply variable that can be produced by the hydrogen production and consumption assembly and / or utilized with the method as a function of time during startup of a fuel processing assembly according to the present disclosure.

[0010] Figure 4 Is a graph schematically depicting the magnitude of a hydrogen supply variable that can be produced by the hydrogen production and consumption assembly and / or utilized with the method as a function of time during steady-state operation of the fuel processing assembly according to the present disclosure. DETAILED DESCRIPTION

[0011] Figures 1 to 2 Examples of a hydrogen production fuel processing system 10, a hydrogen production and consumption assembly 12, and / or a method 200 according to the present disclosure are provided. Elements that serve a similar or at least substantially similar purpose are labeled with like reference numerals in each of Figures 1 to 2 each of the figures, and these elements may not be discussed in detail with reference to each of Figures 1 to 2 each of the figures. Similarly, not all elements may be labeled in each of Figures 1 to 2 the figures, but the associated reference numerals may be utilized herein for consistency. Elements, components, and / or features discussed with reference to one or more of the figures in Figures 1 to 2 may be incorporated in Figures 1 to 2in any of the figures and / or utilized thereby without departing from the scope of the present disclosure. Generally, elements that may be included in a particular embodiment are depicted with solid lines, while optional elements are depicted with dashed lines. However, elements shown with solid lines may not be essential for all embodiments and thus may be omitted in some embodiments without departing from the scope of the present disclosure.

[0012] Figure 1 Depict an example of a hydrogen generation and consumption component 12 according to the present disclosure. The hydrogen generation and consumption component 12 includes a hydrogen generation fuel processing system 10. The hydrogen generation fuel processing system 10 may also be referred to herein as the fuel processing system 10, the hydrogen generation system 10, and / or the fuel reforming system 10. The hydrogen generation and consumption component 12 also includes at least one (i.e., one, a plurality, or multiple) fuel cell stacks 40. The at least one fuel cell stack 40 may additionally or alternatively be referred to as a fuel cell system 42, and the hydrogen generation and consumption component 12 may also be referred to herein as a hydrogen generation fuel cell system (HPFCS) 12. Optionally, the hydrogen generation fuel processing system 10 may be in communication with a power-consuming device 46, such as to provide an electrical output 41 to meet an applied load from the power-consuming device. Examples of the power-consuming device 46 are discussed in more detail herein.

[0013] In addition to the fuel cell system 42 and / or one or more of its fuel cell stacks 40, the hydrogen generation fuel cell system 12 according to the present disclosure includes a feedstock delivery system 22, a fuel processing assembly 13, a low-pressure hydrogen storage tank 78, a stored hydrogen supply conduit 110, and a controller 100. The feedstock delivery system 22 may be configured to provide at least one feedstock stream 16 to the fuel processing assembly 13. The fuel processing assembly 13 is then configured to receive the at least one feedstock stream 16 and generate a product hydrogen stream 14 from the feedstock stream, which includes generated hydrogen 25. The fuel processing assembly 13 may include a hydrogen generation zone 19 that generates a mixed gas stream 20 that includes hydrogen and other gases, and the fuel processing assembly 13 may further include a separation assembly 80 that receives the mixed gas stream 20 and separates the mixed gas stream into the product hydrogen stream 14 and at least one by-product stream 68.

[0014] The low-pressure hydrogen storage tank 78 is configured to store hydrogen as stored hydrogen 79, and the stored hydrogen can be stored in the low-pressure hydrogen storage tank at a hydrogen storage pressure, as discussed in more detail herein. The low-pressure hydrogen storage tank 78 can be configured to receive at least a portion of the product hydrogen stream 14 and store the portion of the product hydrogen stream as stored hydrogen 79. The stored hydrogen supply conduit 110 is configured to convey a stored hydrogen stream 112 (which includes stored hydrogen 79 from the low-pressure hydrogen storage tank 78) to at least one fuel cell stack 40 of the fuel cell system 42. The at least one fuel cell stack 40 is configured to receive the stored hydrogen stream 112 and generate an electrical output 41 from the stored hydrogen stream.

[0015] The controller 100 is programmed or configured to monitor, regulate, and / or control the operation of the components of the HPFCS 12. For example, and as shown in dashed lines in Figure 1 , the controller 100 can be configured to receive a status signal 102 that indicates the operating status of the various components of the hydrogen production fuel processing system 10, and the controller 100 can generate a control signal 104 at least in part based on the value of the status signal, calculations within the controller, and / or control schemes to control the operation of the various components of the hydrogen production fuel processing system 10.

[0016] This can include monitoring, regulating, and / or controlling at least one component of the HPFCS 12 according to any suitable step or steps of method 200. In this context, the controller 100 can be programmed or configured to monitor a hydrogen supply variable that indicates the flow rate of the stored hydrogen stream from the low-pressure hydrogen storage tank 78, e.g., to detect a change in the hydrogen supply variable and respond to the change. As discussed in more detail herein, the controller can be programmed or otherwise configured to detect a change that is greater than or otherwise different from a critical hydrogen supply variable change, and in response to the detection of such a change, the controller 100 can be configured to respond to the detection.

[0017] After this description initially focuses on aspects of the HPFCS and the corresponding method of monitoring and responding to a change in a hydrogen supply variable when the flow of stored hydrogen from the low-pressure hydrogen storage tank 78 to a fuel cell stack 40 is initiated, the components of the HPFCS 12 and the options for the controller 100 to monitor, regulate, and control its operation are discussed in more detail herein.

[0018] In Figure 2The method 200, outlined in the flowchart and discussed in more detail herein, is an example of a control scheme that the controller 100 can utilize to control the various components of the hydrogen-producing fuel processing system 10. However, within the scope of the present disclosure, a portion of the method 200 can be manually performed by a user.

[0019] Figure 2 is a flowchart depicting an example of a method 200 for operating a hydrogen-producing fuel cell system (HPFCS) (e.g., the HPFCS 12 of Figure 1 ). The method 200 can include determining a demand at 205, and the method 200 includes initiating the supply of stored hydrogen at 210. The method 200 can also include reducing the mass of stored hydrogen at 215, generating hydrogen at 220, and / or replenishing stored hydrogen at 225. The method 200 also includes generating an electrical output at 230, monitoring a hydrogen supply variable at 235, and detecting a change in the hydrogen supply variable at 240. The method 200 can further include purging a fuel cell stack at 245, and the method 200 includes a response at 250.

[0020] Determining the demand at 205 can include determining that a power-consuming device has a demand for electrical output, e.g., from the fuel cell stack. Examples of power-consuming devices are disclosed herein with reference to the reference power-consuming device 46.

[0021] When the method 200 includes the determination at 205, the initiation at 210 and / or the generation at 220 can be at least partially based on the determination at 205. In other words, the initiation at 210 and / or the generation at 220 can be performed, initiated, and / or continued based on and / or in response to the determination at 205. In certain examples, and when the method 200 includes the determination at 205, the supply time interval can be based on the determination at 205, can start in response to the determination at 205, can start simultaneously with the initiation at 210, can start immediately after the initiation at 210, and / or can be initiated by the initiation at 210. In other words, the supply time interval can include and / or be an initial supply time interval that corresponds to a time period during which stored hydrogen has been supplied or is being supplied, e.g., to a given fuel cell stack of the fuel cell system.

[0022] The supply of stored hydrogen starting at 210 may include initiating the supply of the stored hydrogen from the low-pressure hydrogen storage tank via the stored hydrogen supply conduit to the fuel cell stack. The stored hydrogen stream may include stored hydrogen; and prior to the start at 210, the stored hydrogen may be stored within a low-pressure hydrogen storage tank at a hydrogen storage pressure. Examples of the stored hydrogen are disclosed herein with reference to stored hydrogen 79. Examples of the stored hydrogen stream are disclosed herein with reference to stored hydrogen stream 112. Examples of the low-pressure hydrogen storage tank are disclosed herein with reference to low-pressure hydrogen storage tank 78. Examples of the hydrogen storage pressure include at least 75 kilopascals gauge (kPag); at least 80 kPag, at least 85 kPag, at least 90 kPag, at least 95 kPag, at least 100 kPag, at least 105 kPag, at least 110 kPag, at least 115 kPag, at least 120 kPag, at least 125 kPag, at least 130 kPag, at least 135 kPag, at least 140 kPag, at least 145 kPag, at least 150 kPag, at least 155 kPag, at least 160 kPag, at least 165 kPag, at least 170 kPag, at least 175 kPag, at least 180 kPag, at least 185 kPag, at least 190 kPag, up to 250 kPag, up to 240 kPag, up to 230 kPag, up to 220 kPag, up to 210 kPag, up to 200 kPag, up to 195 kPag, up to 190 kPag, up to 185 kPag, and / or up to 180 kPag.

[0023] The start at 210 may be accomplished in any suitable manner. For example, the start at 210 may include opening a stored hydrogen supply valve. Examples of the stored hydrogen supply valve are disclosed herein with reference to stored hydrogen supply valve 118. Opening the stored hydrogen supply valve may include allowing and / or facilitating the flow of stored hydrogen from the low-pressure hydrogen storage tank within and / or via the stored hydrogen supply conduit to the fuel cell stack. Examples of the stored hydrogen supply conduit are disclosed herein with reference to stored hydrogen supply conduit 110.

[0024] In some examples, the HPFCS may include a stored hydrogen supply pressure regulator. Examples of the stored hydrogen supply pressure regulator are disclosed herein with reference to stored hydrogen supply pressure regulator 120. In such examples, the start at 210 may include causing the stored hydrogen stream to flow from the low-pressure hydrogen storage tank, through the stored hydrogen supply pressure regulator, and to the fuel cell stack. In such a configuration, the stored hydrogen supply pressure regulator may be configured to regulate the supply pressure of the stored hydrogen to the fuel cell stack.

[0025] Reducing the mass of stored hydrogen at 215 may include reducing the mass of stored hydrogen within the low-pressure hydrogen storage tank. The reduction at 215 may alternatively or additionally be referred to as reducing the amount and / or quantity of stored hydrogen within the low-pressure hydrogen storage tank, and / or as flowing or otherwise removing stored hydrogen from the low-pressure hydrogen storage tank. The reduction at 215 may occur (at least in part) during a startup time period of a fuel processing assembly for the HPFCS, and / or may be at least in part a result of the initiation at 210. An example of the fuel processing assembly is disclosed herein with reference to fuel processing assembly 13.

[0026] In other words, and as discussed in more detail herein, the fuel processing assembly may be configured to produce or selectively produce hydrogen; and method 200 may include performing the initiation at 210 when the fuel processing assembly is not producing hydrogen. In such a configuration, the startup time period may include and / or be a time period required for the fuel processing assembly to begin hydrogen production and / or at least produce a critical flow rate of hydrogen. During this startup time period, the flow rate of hydrogen from the low-pressure hydrogen storage tank and within the stored hydrogen stream may be greater than the flow rate of hydrogen to the low-pressure hydrogen storage tank and from the fuel processing assembly, which results in the reduction at 215.

[0027] Producing hydrogen at 220 may include producing hydrogen using the fuel processing assembly and / or within the fuel processing assembly. In some examples, the production at 220 may include providing at least one feed stream (which includes a carbonaceous feed) to the fuel processing assembly. In some such examples, the production at 220 may also include using the fuel processing assembly and / or producing a product hydrogen stream from the feed stream, which includes the produced hydrogen. In some such examples, the production at 220 may further include providing the product hydrogen stream to the low-pressure hydrogen storage tank as the stored hydrogen. Examples of the feed stream are disclosed herein with reference to feed stream 16. Examples of the product hydrogen stream are disclosed herein with reference to product hydrogen stream 14. Examples of the low-pressure hydrogen storage tank are disclosed herein with reference to low-pressure hydrogen storage tank 78.

[0028] Supplementing the stored hydrogen at 225 may include supplementing the stored hydrogen via the flow of the produced hydrogen stream to and / or into the low-pressure hydrogen storage tank. Alternatively or additionally, the supplementation at 225 may include using the product hydrogen stream to pressurize the low-pressure hydrogen storage tank, such as to the hydrogen storage pressure.

[0029] In some examples, the replenishment of 225 can be performed after the startup time range for the fuel processing assembly, during the generation of 220, and / or during the supply of the stored hydrogen to the fuel cell stack that is initiated during a start period similar to 210. In other words, and after the startup time range, the flow rate of hydrogen from the low-pressure hydrogen storage tank and within the stored hydrogen stream can be less than the flow rate of hydrogen to the low-pressure hydrogen storage tank and from the fuel processing assembly, which results in the replenishment of 225.

[0030] In some examples, the supply time interval can occur during the replenishment of 225 and / or during the pressurization of the low-pressure hydrogen storage tank by the product hydrogen stream. In other words, the supply time interval can be a period of time during the normal operation of the HPFCS, for example, it can occur well after the start of 210 and / or when the fuel processing assembly generates the product hydrogen stream.

[0031] Generating the power output at 230 can include using the fuel cell stack to generate the power output from the stored hydrogen. Examples of the power output are disclosed herein with reference to the reference power output 41. Examples of the fuel cell stack are disclosed herein with reference to the fuel cell stack 40. The generation at 230 can be accomplished in any suitable manner. For example, and as discussed in more detail herein, the generation at 230 can include reacting the stored hydrogen with an oxidant within the fuel cell stack to output and / or generate the power output.

[0032] Monitoring the hydrogen supply variable at 235 can include monitoring the hydrogen supply variable during a supply time interval after the start of 210. The hydrogen supply variable can indicate the flow rate of the stored hydrogen stream to the fuel cell stack. Detecting a change in the hydrogen supply variable at 240 can include detecting that the change in the hydrogen supply variable is greater than the change in a critical hydrogen supply variable.

[0033] In some examples, and as discussed, the supply time interval can start immediately after the start of 210 and / or can be initiated by the start of 210. In some examples, and also as discussed, the supply time interval can occur during the normal operation of the HPFCS, for example, after the start of 210, during the supply of the stored hydrogen stream to the fuel processing assembly, during the supply of the product hydrogen stream from the fuel processing assembly to the low-pressure hydrogen storage tank, and / or after the startup time range of the fuel processing assembly.

[0034] The supply time interval can have any suitable duration. For example, the duration of the supply time interval can be at least 5 seconds, at least 10 seconds, at least 15 seconds, at least 20 seconds, at least 25 seconds, at least 30 seconds, at least 35 seconds, at least 40 seconds, at least 45 seconds, at least 50 seconds, at least 55 seconds, at least 60 seconds, at most 120 seconds, at most 110 seconds, at most 100 seconds, at most 90 seconds, at most 80 seconds, at most 70 seconds, at most 60 seconds, at most 55 seconds, at most 50 seconds, at most 45 seconds, at most 40 seconds, at most 35 seconds, and / or at most 30 seconds.

[0035] In some examples, the HPFCS can include a hydrogen supply variable detector. The hydrogen supply variable detector can be configured to detect the hydrogen supply variable and / or detect a parameter indicating the hydrogen supply variable. In such an example, the monitoring at 235 can include using, passing through, and / or utilizing the hydrogen supply variable detector for monitoring. Examples of the hydrogen supply variable detector are disclosed herein with reference to the hydrogen supply variable detector 130.

[0036] In some examples, the hydrogen supply variable can include or be a hydrogen supply pressure of the stored hydrogen, for example, which can be detected by a pressure detector. In such an example, the monitoring at 235 can include monitoring the hydrogen supply pressure. This can include monitoring the hydrogen supply pressure at any suitable location within the HPFCS, examples of which include in the low-pressure hydrogen storage tank, downstream of the low-pressure hydrogen storage tank, upstream of the stored hydrogen supply valve, and / or upstream of the stored hydrogen supply pressure regulator.

[0037] In some such examples, the detection at 240 can include calculating a change in the hydrogen supply pressure during the supply time interval. The change in the hydrogen supply pressure can include and / or be the difference between (1) the hydrogen supply pressure before the start of 210 or before the supply time interval and (2) the hydrogen supply pressure after the start of 210 or during the supply time interval.

[0038] In some such examples, the change in the critical hydrogen supply variable may comprise and / or be a critical hydrogen supply pressure change. Examples of the critical hydrogen supply pressure change include 30 kPag, 35 kPag, 40 kPag, 45 kPag, 50 kPag, 55 kPag, 60 kPag, 65 kPag, 70 kPag, 75 kPag, 80 kPag, 85 kPag, 90 kPag, 95 kPag, 100 kPag, 105 kPag, 110 kPag, 115 kPag, 120 kPag, 125 kPag, 130 kPag, 135 kPag or 140 kPag. In some examples, the critical supply pressure change may comprise and / or be a critical pressure change multiple of a nominal supply pressure change, such as may be encountered during the supply time interval, during normal operation of the HPFCS and / or when there is no hydrogen leakage within the HPFCS. Examples of the critical pressure change multiple include 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5 or 7. Examples of the nominal supply pressure change include up to 5 kPag, up to 7.5 kPag, up to 10 kPag, up to 12.5 kPag, up to 15 kPag, up to 17.5 kPag or up to 20 kPag.

[0039] In some examples, the hydrogen supply variable may comprise or be a hydrogen flow rate of the stored hydrogen gas stream, such as may be detected by a hydrogen flow meter. In such examples, the monitoring at 235 may comprise monitoring the hydrogen flow rate. This may comprise monitoring the hydrogen flow rate at any suitable location within the HPFCS, examples of which include downstream of the low-pressure hydrogen storage tank and / or upstream of the fuel cell stack.

[0040] In some such examples, the change in the critical hydrogen supply variable may comprise and / or be a critical hydrogen flow rate magnitude. In some such examples, the critical hydrogen flow rate magnitude may comprise and / or be a critical flow rate multiple of a nominal hydrogen flow rate magnitude, such as may be encountered during the supply time interval, during normal operation of the HPFCS and / or when there is no hydrogen leakage within the HPFCS. Examples of the critical flow rate multiple include 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5 or 7.

[0041] In some examples, the fuel cell stack may have a maximum design wattage. In such examples, the magnitude of the critical hydrogen flow rate may be a wattage multiple of the maximum design wattage. Examples of the wattage multiple include 18 standard liters per minute per kilowatt (SLPM / kW), 20 SLPM / kW, 30 SLPM / kW, 40 SLPM / kW, 50 SLPM / kW, 60 SLPM / kW, 70 SLPM / kW, 80 SLPM / kW, or 90 SLPM / kW.

[0042] Examples of monitoring at 235 and detection at 240 are depicted in Figures 3 to 4 the Figure 3 is a diagram generally depicting the magnitude of a hydrogen supply variable (e.g., hydrogen supply pressure) as a function of time according to the present disclosure, which may be generated during startup of a fuel processing assembly by hydrogen production and consumption components and / or may be utilized in conjunction with the method. In Figure 3 the example, the magnitude of the hydrogen supply variable at time t 0 to time t 1 is increasing. This increase over time may be due to startup of the fuel processing assembly. In other words, and during startup, the fuel processing assembly may produce an increasingly larger flow rate, volume, or mass of the product hydrogen stream, which may be stored in the low-pressure hydrogen storage tank, resulting in the time trend depicted in Figure 3 . Then, at time t 1 and when the hydrogen supply variable has a magnitude of v 1 , initiation at 210 may be performed to begin supplying hydrogen for storage to a first fuel cell stack. This may cause a decrease in the mass of stored hydrogen within the low-pressure hydrogen storage tank, i.e., as discussed with reference to the decrease at 215, resulting in a decrease in the magnitude of the hydrogen supply variable at a time t 2 to a value of v 2 . This decrease in the magnitude of the hydrogen supply variable (e.g., v 1 -v 2 ) may be less than the change in the critical hydrogen supply variable. In this regard, detection at 240 may not include detecting a change in the hydrogen supply variable greater than the change in the critical hydrogen supply variable and / or method 200 may not proceed to the response at 250.

[0043] From time t 2 to time t 3 , the magnitude of the hydrogen supply variable may increase again to a magnitude of v 3 . Then, at time t 3, at the start of 210 it can be executed to begin the supply of storing hydrogen to a second fuel cell stack. This can again cause a reduction in the mass of the stored hydrogen within the low-pressure hydrogen storage tank, i.e., as discussed for the reduction at 215 herein, resulting in a reduction in the magnitude of the hydrogen supply variable at a time t 4 to a value of v 4 . This reduction in the magnitude of the hydrogen supply variable (e.g., v 3 -v 4 ) can be greater than the change in the critical hydrogen supply variable. In this regard, the detection at 240 will include detecting a change in the hydrogen supply variable that is greater than the change in the critical hydrogen supply variable, and method 200 will proceed to the response at 250. In other words, Figure 3 is an example depicting where there is no hydrogen leakage in the first fuel cell stack, but there is indeed hydrogen leakage in the second fuel cell stack, and method 200 can respond to the hydrogen leakage within the second fuel cell stack as disclosed herein with reference to the response at 250.

[0044] Figure 4 is a diagram generally depicting the magnitude of a hydrogen supply variable (e.g., hydrogen supply pressure) as a function of time according to the present disclosure, which can be generated during the steady-state operation of the fuel processing assembly by the hydrogen generation and consumption components and / or can be utilized with the method. In Figure 4 the example, the magnitude of the hydrogen supply variable is stable around a value of v 0 from time t 1 to time t 1 . Then, at time t 1 , the start of 210 is executed to begin the supply of storing hydrogen to a first fuel cell stack. This can cause a reduction in the mass of the stored hydrogen within the low-pressure hydrogen storage tank, i.e., as discussed for the reduction at 215 herein, which results in a reduction in the magnitude of the hydrogen supply variable to a value of v 2 . This reduction in the magnitude of the hydrogen supply variable (e.g., v 1 -v 2 ) can be less than the change in the critical hydrogen supply variable. In this regard, the detection at 240 may not include detecting a change in the hydrogen supply variable that is greater than the change in the critical hydrogen supply variable, and / or method 200 may not proceed to the response at 250.

[0045] At time t 2 , the fuel processing assembly can adapt to the change in hydrogen demand such that the magnitude of the hydrogen supply variable nominally returns to v 1 . From time t 2 to time t3 The magnitude of the hydrogen supply variable can then be stabilized again at around the value of v 1 . Then, at time t 3 , an initiation at 210 can be performed to start the supply of hydrogen for storage to a second fuel cell stack. This can again cause a reduction in the mass of the stored hydrogen within the low-pressure hydrogen storage tank, i.e., as discussed with reference to the decrease at 215 herein, which results in a decrease in the magnitude of the hydrogen supply variable to a value of v 3 . During a corresponding supply time interval (e.g., t 4 - t 3 ), this decrease in the magnitude of the hydrogen supply variable (e.g., v 2 - v 3 ) can be greater than the change in the critical hydrogen supply variable. In this regard, the detection at 240 will include detecting a change in the hydrogen supply variable that is greater than the change in the critical hydrogen supply variable, and method 200 will proceed to the response at 250. In other words, Figure 4 is an example depicting where there is no hydrogen leakage in the first fuel cell stack, but there is indeed hydrogen leakage in the second fuel cell stack, and as disclosed herein with reference to the response at 250, method 200 can respond to hydrogen leakage within the second fuel cell stack.

[0046] The purging of the fuel cell stack at 245 can include using, passing through, and / or utilizing the stored hydrogen stream to purge the fuel cell stack. This can include purging the fuel cell stack during a purge time interval. When the purge at 245 is performed, it can be utilized to purge unwanted compounds, materials, and / or contaminants from the fuel cell stack. For example, the purge at 245 can be utilized to remove excess water from the fuel cell stack.

[0047] When the purge at 245 is performed, it may cause a change in the hydrogen supply variable that is greater than the change in the critical hydrogen supply variable. However, this may be the result of the purge at 245 and / or may not be the result of a hydrogen leak within the HPFCS. In this regard, when the HPFCS performs the purge at 245, if the detection at 240 detects a change in the hydrogen supply variable that is greater than the change in the critical hydrogen supply variable, method 200 may not perform the response at 250. In other words, the supply time interval may not include the purge time interval and / or may not overlap with the purge time interval. In yet other words, method 200 may include omitting the response at 250 during the purge time interval. Regarding "omitting", it means that the method may include not performing the detection and / or not performing the response during the purge time interval. In some such examples, the omission may include an omission during an omission time period that is a critical omission time multiple of the purge time interval. Examples of the critical omission time multiple include at least 1.25, at least 1.5, at least 1.75, at least 2, at least 2.5, at least 3, at least 4, at least 5, up to 10, up to 9, up to 8, up to 7, up to 6, up to 5, up to 4, up to 3, and / or up to 2.

[0048] The response at 250 may include performing at least one action that is initiated based on, in response to, and / or by the detection at 240. In some examples, the response at 250 may include determining that there is a hydrogen leak within the HPFCS, downstream of the low-pressure hydrogen storage tank, and / or within the fuel cell stack.

[0049] In some examples, the initiation at 210 may include initiating the supply of stored hydrogen to a given fuel cell stack among the plurality of fuel cell stacks of the HPFCS. In some such examples, the response at 250 may include stopping the supply of stored hydrogen to the given fuel cell stack. In some such examples, method 200 may further include maintaining the supply of stored hydrogen to another fuel cell stack among the plurality of fuel cell stacks after the stop and / or repeating the initiation at 210 after the stop to supply the stored hydrogen to another fuel cell stack among the plurality of fuel cell stacks. In other words, and when the HPFCS includes the plurality of fuel cell stacks, method 200 may be applied independently to one or each of the plurality of fuel cell stacks.

[0050] In a more specific example, the start at 210 may include starting the supply of stored hydrogen to a first fuel cell stack of the plurality of fuel cell stacks, and then starting the supply of stored hydrogen to a second fuel cell stack of the plurality of fuel cell stacks. In this example, the detection at 240 may include detecting a change in the hydrogen supply variable after starting the supply of stored hydrogen to the first fuel cell stack and / or after starting the supply of stored hydrogen to the second fuel cell stack, and the response at 250 may include performing the at least one action only on and / or for the fuel cell stack that, after receiving the stored hydrogen, outputs and / or generates a change in the hydrogen supply variable. For example, a change in the hydrogen supply variable may be detected after starting at 210 for the second fuel cell stack, but may not be detected after starting at 210 for the first fuel cell stack. In this example, the response at 250 may include performing the at least one action on the second fuel cell stack; however, the at least one action may not be performed on the first fuel cell stack.

[0051] In some examples, the response at 250 may include starting a system diagnostic test of the HPFCS, a system diagnostic test of at least one fuel cell stack of the HPFCS, and / or a system diagnostic test of the plurality of fuel cell stacks of the HPFCS. In some examples, the response at 250 may include notifying an operator of the HPFCS that a hydrogen leak or a possible hydrogen leak exists within the HPFCS, within at least one fuel cell stack of the HPFCS, and / or within one or more specific fuel cell stacks of the HPFCS. In some examples, the response at 250 may include stopping the operation of the HPFCS and / or the operation of at least one component of the HPFCS. This may include shutting down the operation of the entire HPFCS, shutting down at least one fuel cell stack of the HPFCS, shutting down all fuel cell stacks of the HPFCS, stopping hydrogen production by the fuel processing assembly, and / or stopping the flow of stored hydrogen to the fuel cell stacks.

[0052] Method 200 and / or controller 100 may be utilized in a wide variety of hydrogen-producing fuel processing systems 10 and / or HPFCSs 12. In the following discussion, and with reference to Figure 1 , examples of the hydrogen-producing fuel cell system 10 and the HPFCS 12 are schematically depicted and described, but method 200 is not limited to being performed on and / or within only the hydrogen-producing fuel cell systems and HPFCSs depicted and / or described in Figure 1 .

[0053] Reference Figure 1, one or more feed streams 16 can be transported to the hydrogen production region 19 of the hydrogen production fuel processing system 10 through a feed delivery system 22. In Figure 1 , the feed stream 16 is shown as being transported to the hydrogen production region 19 by the feed delivery system 22, which generally represents any suitable mechanism, device, or combination thereof for selectively transporting the feed stream 16 to the hydrogen production region 19. For example, the feed delivery system 22 can include one or more pumps adapted to transport the components of the feed stream 16 from one or more supplies. Additionally or alternatively, the feed delivery system 22 can include a valve assembly adapted to regulate the flow rate of the components of the feed stream 16 from a pressurized supply. This supply can be located outside the fuel processing system 10, or they can be contained within or adjacent to the fuel processing system 10. When the feed stream 16 is transported to the hydrogen production region 19 as more than one stream, the streams can be transported by the same or separate feed delivery systems 22. Examples of feed delivery systems 22 are disclosed in U.S. Patent Nos. 7,601,302, 6,375,906, 7,135,048, and 6,890,672, as well as in U.S. Patent Application Publication Nos. 2009 / 0155642 and 2019 / 0273275, the entire disclosures of which are hereby incorporated by reference.

[0054] The one or more feed streams 16 include at least one carbonaceous feed 18, and the one or more feed streams can include water 17, for example when the hydrogen production region is configured to produce a mixed gas stream 20 from the carbonaceous feed 18 and water 17 through a steam reforming reaction. When the hydrogen production region is configured to produce a mixed gas stream 20 through a hydrogen production reaction such as a partial oxidation reaction, the one or more feed streams can also include an oxidizer 15 such as oxygen. When the hydrogen production region is configured to produce a mixed gas stream 20 through an autothermal reaction, the one or more feed streams can include a carbonaceous feed 16 and an oxidizer 15 such as oxygen. Within the scope of the present disclosure, the one or more feed streams 16 can additionally or alternatively be referred to in terms of their components, such as including a carbonaceous feed stream 18, a water stream 17, an oxidizer or oxygen stream 15, and / or a mixed stream containing a carbonaceous feed and water.

[0055] With this in mind, the feed delivery system 22 can be configured to supply the one or more feed streams to the hydrogen production region 19, for example by utilizing one or more pumps, compressors, or a pressurized source for the carbonaceous feed, water, and / or other feed components.

[0056] Although a single feed stream 16 is shown in Figure 1In [the figure], it is shown by solid lines, but within the scope of the present disclosure, more than one feed stream 16 can be used, and these streams can contain the same or different feeds. When the feed stream 16 contains two or more components, such as a carbonaceous feed 18 and water 17, the components can be transported by the same or different feed streams. For example, when the fuel processing system 10 is adapted to produce hydrogen from a carbonaceous feed and water and optionally (at least until both streams are vaporized or otherwise in the gaseous state), when they are immiscible with each other, these components are typically transported by separate streams, such as shown by reference numerals 17 and 18 pointing to different feed streams in Figure 1 as shown.

[0057] When the carbonaceous feed 18 is miscible with water, the carbonaceous feed 18 can be transported together with the water component of the feed stream 16, such as shown by reference numerals 17 and 18 pointing to the same feed stream 16 in Figure 1 as shown. For example, when the hydrogen production zone 19 receives a feed stream containing water and a water-soluble alcohol such as methanol, these components can be premixed and transported as a single stream. When the hydrogen production zone 19 receives a gaseous feed stream, the gaseous feed stream can be transported to the hydrogen production zone 19 together with one or more of the liquid feed streams or as a separate feed stream, such as shown in Figure 1 as shown.

[0058] As depicted in Figure 1 the fuel processing assembly 13 includes a hydrogen production zone 19. The hydrogen production zone 19 can be configured to receive one or more feed streams 16 and generate a mixed gas stream 20 from the one or more feed streams 16 through a suitable hydrogen production zone. The mixed gas stream 20 contains hydrogen as a main component and contains other gases, such as carbon monoxide, carbon dioxide, methane, unreacted carbonaceous feed 18, and vapor. Regarding "main component", it means that hydrogen is present in the mixed gas stream at a concentration or amount greater than any other gas. For example, the mixed gas stream 20 can contain at least 50 wt%, at least 60 wt%, and / or at least 70 wt% hydrogen.

[0059] The hydrogen production zone 19 can utilize any suitable process or mechanism to produce hydrogen from the feed stream 16 and can be contained within or outside a heated containment structure 70. Examples of suitable mechanisms by which the hydrogen production zone 19 can produce hydrogen from the feed stream 16 and as discussed include steam reforming, autothermal reforming, and partial oxidation reforming.

[0060] In some examples, the hydrogen production zone 19 includes one or more reforming catalysts 23 configured to produce hydrogen from a feed stream 16 that includes a carbonaceous feed stream 18 and a water stream 17. In such examples, the hydrogen production zone 19 may include, be referred to herein as, and / or may be a reformer 19. Examples of suitable carbonaceous feeds 18 include at least one hydrocarbon or alcohol. Examples of suitable hydrocarbons include methane, propane, natural gas, diesel, kerosene, gasoline, and the like. Examples of suitable alcohols include methanol, ethanol, various propanols, and polyols such as ethylene glycol and propylene glycol.

[0061] Other suitable mechanisms for producing hydrogen from the feed stream 16 include ammonia decomposition, electrolysis of water, and the water gas shift reaction. Illustrative and non-exclusive examples of suitable hydrogen production zones and / or mechanisms are disclosed in U.S. Patent Nos. 6,537,352, 6,221,117, 5,997,594, 5,861,137, and in U.S. Patent Application Publication No. 2003 / 0223926, the entire disclosures of which are hereby incorporated by reference.

[0062] Steam reforming is an example of a hydrogen production mechanism that may be employed in the hydrogen production zone 19, where the feed stream 16 includes water 17 and a carbonaceous feed 18. In a steam reforming process, the hydrogen production zone 19 includes a suitable steam reforming catalyst 23, as indicated by the dashed line in Figure 1 In such examples, the hydrogen production fuel processing system may be referred to as a steam reformer, the hydrogen production zone 19 may be referred to as a reforming zone, and the mixed gas stream 20 may be referred to as a reformate stream. As a more specific example, the hydrogen production zone 19 may utilize a methanol steam reforming reaction and / or may be referred to as a methanol reforming zone, and the hydrogen production zone 19 may include a methanol steam reforming catalyst 23 configured to produce a mixed gas stream 20 that is predominantly hydrogen from methanol and water.

[0063] When the hydrogen production zone 19 includes a reforming catalyst 23, the reforming catalyst 23 may be non-self-igniting such that the reforming catalyst 23 can be exposed or contacted with air or oxygen without burning and / or being deactivated. Examples of suitable steam reforming catalysts are disclosed in U.S. Patent No. 7,128,769, the entire disclosure of which is hereby incorporated by reference. Additional examples of non-self-igniting reforming catalysts that may be utilized in the hydrogen production zone 19 include a reforming catalyst sold by Clariant under the trade name KMA and / or a reforming catalyst containing zinc oxide supported on calcium aluminate.

[0064] Steam reformers typically operate in a temperature range of 200°C (degrees Celsius) to 900°C and a pressure range of 50 psi (pounds per square inch) to 300 psi, although temperatures and pressures outside of this range are within the scope of the present disclosure. When the carbonaceous feedstock 18 is methanol, the hydrogen-producing steam reforming reaction or the hydrogen-producing zone 19 typically operates in a hydrogen-producing temperature range of about 200 to 500°C. Illustrative subsets of this range include 275 to 375°C, 300 to 400°C, 350 to 450°C, 375 to 425°C, and 375 to 400°C.

[0065] When the carbonaceous feedstock is a hydrocarbon, ethanol, or a similar alcohol, a hydrogen-producing temperature range of about 400 to 900°C is typically utilized for the steam reforming reaction or by the hydrogen-producing zone 19. Illustrative subsets of this range include 750 to 850°C, 725 to 825°C, 650 to 750°C, 700 to 800°C, 700 to 900°C, 500 to 800°C, 400 to 600°C, and 600 to 800°C.

[0066] Within the scope of the present disclosure, the hydrogen-producing zone 19 can include two or more zones or portions, each of which can operate at the same or different temperatures. For example, when the carbonaceous feedstock 18 includes a liquid hydrocarbon, in some embodiments, it may be desirable to include two different hydrogen-producing portions, one operating at a lower temperature than the other to provide a pre-reforming zone. In such an embodiment, the fuel processing system 10 can alternatively be described as including two or more hydrogen-producing zones 19.

[0067] The hydrogen-producing fuel processing system 10 can also include a mixed gas filter 30, which is positioned downstream of the hydrogen-producing zone 19 and upstream of the separation assembly 80, such that when the mixed gas stream 20 is transferred from the hydrogen-producing zone 19 to the separation assembly 80, the mixed gas stream 20 passes through the mixed gas filter 30. The mixed gas filter 30 can be configured to filter the mixed gas stream 20 to remove or reduce the concentration of selected impurities that may be contained within the mixed gas stream 20 and that may be detrimental to the operation of the separation assembly 80. For example, the mixed gas filter 30 can be configured to remove one or more of particulate matter, sols, soot, and / or ash that may be present in the mixed gas stream 20 when the mixed gas stream 20 is released from the hydrogen-producing zone 19.

[0068] The fuel processing assembly 13 may also include a separation assembly 80. The separation assembly may be configured to receive the mixed gas stream 20 and, for example, produce a byproduct stream 68 and a product hydrogen gas stream 14 from the mixed gas stream. For example, the separation assembly 80 may be configured to separate the mixed gas stream 20 into the product hydrogen gas stream 14 and the byproduct stream 68. The product hydrogen gas stream 14 contains a greater concentration of hydrogen than the mixed gas stream and contains a lower overall concentration of other gases than the mixed gas stream. In other words, the byproduct stream 68 contains the major or most part of the other gases. The product hydrogen gas stream 14 may contain pure or at least substantially pure hydrogen. Examples of the separation assembly 80 include a membrane separation assembly 82 that includes one or more hydrogen-selective membranes and a pressure swing adsorption separation assembly 84. Examples of suitable separation assemblies 80 and their components are disclosed in U.S. Patent Nos. 7,972,420, 10,476,093, 7,733,311, 7,399,342, and 7,837,765.

[0069] As used herein, at least substantially pure hydrogen may be greater than 90% pure, greater than 95% pure, greater than 99% pure, greater than 99.5% pure, and / or greater than 99.9% pure. In contrast, the byproduct stream 68 contains a greater overall concentration of other gases than the mixed gas stream. The byproduct stream may contain hydrogen, but it contains a lower concentration of hydrogen than the mixed gas stream.

[0070] Continuing to refer Figure 1 to, the portion of the mixed gas stream 20 that does not include the product hydrogen gas stream 14 may contain impurities (other gases) contained within the mixed gas stream 20, as well as a portion of the hydrogen gas contained therein, and may be discharged as the byproduct stream 68 from the separation assembly 80. The byproduct stream 68 may be disposed of in any suitable manner, which includes discharging it to the environment external to the hydrogen-producing fuel processing system 10, chemically treating and / or reacting it prior to discharge, supplying it as a fuel stream to the burner assembly 92, using it as a reaction stream for another chemical process, and / or storing it for later use.

[0071] The fuel processing system 10 may also include a heating assembly 91 that may be configured to heat at least a portion of the fuel processing system 10, such as the hydrogen-producing region 19 and / or the separation assembly 80. For example, the heating assembly 91 may be configured to heat the portion of the fuel processing system to a suitable operating temperature or operating temperature range for producing hydrogen, purifying hydrogen, and so on. For example, the heating assembly 91 may include an evaporation region (or an evaporator) 94 that is configured to evaporate any liquid portion of the feed stream 16 such that the feed stream 16 may be in an evaporated state when entering, during, or prior to entering the hydrogen-producing region 19.

[0072] As another example, the heating assembly 91 can be configured to heat the hydrogen production region 19 to a suitable hydrogen production temperature, examples of which are included herein. In certain examples, the heating assembly 91 can additionally or alternatively be configured to maintain a portion of the fuel processing system at the operating temperature or a “primed” or “buffered” temperature during periods in which the hydrogen production region is not being utilized to produce hydrogen and / or is not producing more than a nominal amount of hydrogen, such as to maintain the HPFCS 12 in a standby or idle operating state. By doing so, compared to the hydrogen production region 19 at ambient temperature, it will take less time to heat the hydrogen production region 19 to a hydrogen production temperature. Examples of electrical energy sources for the electrical heating assembly 93 include energy supplied by the energy storage device 50, the fuel cell stack 40, and / or the main power supply 52.

[0073] The primed or buffered temperature can be less than the operating or hydrogen production temperature of the hydrogen production region 19, but greater than ambient temperature. For example, the primed or buffered temperature can be at least 100 °C, at least 150 °C, and / or at least 200 °C. Additionally or alternatively, the primed or buffered temperature can be at least 25 °C, at least 50 °C, at least 75 °C, at least 100 °C, at least 150 °C, at least 200 °C, and / or at least 250 °C less than the hydrogen production temperature of the hydrogen production region 19. Additional examples of suitable operating (i.e., hydrogen production and / or hydrogen purification), primed, and / or buffered temperature ranges and corresponding hydrogen production fuel cell systems and their components are disclosed in U.S. Patent No. 7,659,019, the entire disclosure of which is hereby incorporated by reference.

[0074] The heating assembly 91 can utilize any suitable structure to supply heat to the interior compartment of the heated containment structure 70, to components contained therein, and / or to various components of the fuel processing system 10. This can include a burner assembly 92 and / or an electrical heating assembly 93. When the heating assembly 91 includes a burner assembly 92, the burner assembly can include one or more burners, and the fuel for the burner assembly 92 can be provided from any suitable source. Examples of fuel for the burner assembly 92 include the byproduct stream 68, the product hydrogen stream 14, the mixed gas stream 20, the feed stream 16, the carbonaceous feed 18, or any other suitable combustible fuel source as discussed in more detail herein.

[0075] As shown in Figure 1 the fuel processing system 10 can include a byproduct stream conduit 62. The byproduct stream conduit can be configured to direct the byproduct stream 68 from the separation assembly 80 to another part of the fuel processing system 10, such as a burner assembly 92, and / or to direct it from outside the fuel processing system 10.

[0076] As discussed, the hydrogen-producing fuel processing system 10 can include a heated containment structure 70, which can define an internal compartment that can include a separation component 80, a heating component 91, a hydrogen-producing region 19, and / or a portion of the feed delivery system 22, as well as any suitable valves, conduits, and / or piping associated with the foregoing components. Also within the scope of the present disclosure is that the heated containment structure 70 can include or can contain additional system components.

[0077] Any components contained within the heated containment structure 70 can be maintained at substantially the same temperature or can be maintained at different temperatures. This can be accomplished in any suitable manner, such as by using individual heating components 91 for the various components contained within the heated containment structure 70, the distance of a particular component from a heating component, internal structures such as baffles, supports, partitions, and / or the like to direct and / or control the heat flow from the heating component, and / or the use of multiple heated containment structures, each having an internal compartment maintained at an individual temperature and / or temperature range. Also within the scope of the present disclosure is that the heated containment structure 70 can include insulation, which can reduce the heat transfer rate between the internal compartment of the heated containment structure 70 and the environment, and / or control the heat flow between the components contained within the internal compartment.

[0078] In some examples, the hydrogen-producing fuel processing system 10 can include a cleaning area 32 that receives a product hydrogen gas stream 14 from the separation component 80 and is configured to further purify, remove, reduce, and / or chemically react selected impurities that may be present in the product hydrogen gas stream 14. Examples of devices that can be utilized within the cleaning area 32 include water shift reactors, as well as other devices that convert carbon monoxide to carbon dioxide, and methanation catalysts that convert carbon monoxide and hydrogen to methane and water. For example, when the product hydrogen gas stream 14 is intended for use in a fuel cell system 42 that includes a proton exchange membrane (PEM) or other devices that would be damaged if the product hydrogen gas stream 14 contains more than a specified concentration of carbon monoxide or carbon dioxide, the cleaning area 32 can include at least one methanation catalyst bed.

[0079] As in Figure 1As shown and as discussed, the hydrogen production fuel processing system 10 includes a low-pressure hydrogen storage tank 78, which is configured to receive at least a portion of the product hydrogen stream 14 from the fuel processing assembly 13, from the separation assembly 80, and / or from the clean zone 32, and to store a volume of the product hydrogen stream 14 as stored hydrogen 79. As depicted, the low-pressure hydrogen storage tank 78 may be configured to receive hydrogen from the product hydrogen stream 14 before the product hydrogen stream 14 within the stored hydrogen stream 112 is supplied to at least one fuel cell stack 40 of the fuel cell system 42. The low-pressure hydrogen storage tank 78 may increase the stability of the pressure of the product hydrogen stream 14 being supplied to the fuel cell stack 40, and / or may reduce the likelihood of pressure variations in the product hydrogen stream 14 being supplied to the fuel cell stack 40. Additionally or alternatively, the low-pressure hydrogen storage tank 78 may act as or may herein be referred to as a buffer tank, which may be configured to accommodate variations in the demand for stored hydrogen 79 by the fuel cell 44, and / or variations in the production of hydrogen 25 by the fuel processing assembly 13.

[0080] As discussed, the HPFCS 12 may include a stored hydrogen supply valve 118. The stored hydrogen supply valve may be configured to selectively regulate the flow rate of the stored hydrogen stream within the stored hydrogen supply conduit 110. Examples of the stored hydrogen supply valve 118 include a manual valve, a quarter turn valve, a ball valve, a metering valve, an electric valve, a solenoid valve, and / or a pneumatic valve.

[0081] As shown in dashed lines in Figure 1 the HPFCS 12 may also include a stored hydrogen supply pressure regulator 120. The stored hydrogen supply pressure regulator may be configured to selectively regulate the hydrogen supply pressure of the stored hydrogen stream 112 received by the fuel cell stack 40. In view of this and as depicted, when the hydrogen supply variable detector 130 includes a pressure detector 132, the pressure detector may be positioned upstream of the stored hydrogen supply pressure regulator 120. To give a more specific example, the pressure detector may be configured to detect the hydrogen supply pressure in the low-pressure hydrogen storage tank 78, downstream of the low-pressure hydrogen storage tank, upstream of the stored hydrogen supply valve 118, and / or upstream of the stored hydrogen supply pressure regulator 120.

[0082] As discussed, the product hydrogen gas stream 14 produced by the fuel processing system 10 can be delivered to one or more fuel cell stacks 40 of the fuel cell system 42. A fuel cell stack is a device that generates an electrical potential from a proton source (such as hydrogen gas) and an oxidant (such as oxygen). Thus, the fuel cell stack 40 can be configured to receive at least a portion of the product hydrogen gas stream 14 and an oxygen stream (or an oxygen-containing stream), which is typically delivered in the form of an air stream, and generate an electric current therefrom. This is schematically depicted in Figure 1 where an air (or oxygen-containing) stream is indicated at 49, the fuel cell stack is indicated at 40, and the electric current or power output generated by the fuel cell stack is schematically depicted at 41.

[0083] Each fuel cell stack 40 includes at least one and typically a plurality of fuel cells 44, which are adapted to generate an electric current from the oxidant and the portion of the product hydrogen gas stream 14 delivered thereto. The fuel cells are typically connected together between common end plates 48, which include fluid transfer / removal conduits, although this configuration is not required for all embodiments. Examples of suitable fuel cells 44 include proton exchange membrane (PEM) fuel cells, high-temperature proton exchange membrane fuel cells, low-temperature proton exchange membrane fuel cells, polybenzimidazole (PBI) membrane fuel cells, alkaline fuel cells, and phosphoric acid fuel cells, although other types of fuel cells are also within the scope of the present disclosure.

[0084] The power output 41 from the fuel cell system 42 can be stored for later use, such as by the use of an energy storage device 50, and / or utilized to meet the electrical load imposed by the energy-consuming device 46. The energy storage device 50 can include any suitable configuration that is adapted to store at least a portion of the power output from the fuel cell system 42. Examples of energy storage devices 50 according to the present disclosure include any suitable battery, capacitor, supercapacitor, ultracapacitor, and flywheel. Additional examples of the energy storage device 50, the HPFCS 12 including the energy storage device 50, and / or methods of operating such a system are disclosed in U.S. Patent No. 11,316,180, the disclosure of which is incorporated herein by reference. The HPFCS 12 can include any suitable power management device, such as a DC / DC converter, rectifier, and the like, such as to rectify, increase, or decrease the voltage of the power output 41, or otherwise manage or convert the power output 41.

[0085] Examples of the energy-consuming device 46 include tools, lights or lighting assemblies, electrical appliances (such as household or other appliances), homes or other residences, offices or other commercial premises, computers, signal or communication devices, telecommunication devices, medical devices, and so on. Similarly, the fuel cell stack 40 can be used to meet the power requirements of the fuel cell system 42, which can be referred to as the power requirements of the balance-of-plant of the fuel cell system. The energy-consuming device 46 is schematically depicted in Figure 1 and is intended to represent one or more devices or a collection of devices that are adapted to draw current from the fuel cell system 42 or to impose an electrical load on the fuel cell system 42.

[0086] Within the scope of the present disclosure, the energy-consuming device 46 may optionally be electrically connected to a main power source 52, which may also provide a main power output 54 to the hydrogen-producing fuel cell system. When the energy-consuming device 46 is electrically connected to the main power source, the HPFCS 12 can operate as an auxiliary and / or backup power system 56, which is adapted to meet the load imposed by the energy-consuming device 46 when the main power source 52 cannot meet at least a portion of the applied load.

[0087] The main power source 52 includes any suitable structure that is adapted to supply the main power output 54 to meet the load imposed from the energy-consuming device 46. Examples of the main power source include the utility grid, a hydroelectric power source, a solar power source, a wind power source, other fuel cell systems, and / or energy storage devices or systems. Some main power sources may include an energy storage device or system combined with another power source (such as a hydroelectric power source, a solar power source, and / or a wind power source).

[0088] An example of the main power source not being able to meet at least a portion of the applied load is that the main power source cannot meet the entire applied load, for example, when the magnitude of the applied load is greater than the magnitude of the available power output from the main power source. In these situations, the HPFCS 12 can supplement the power output from the main power source and can also be referred to as a supplementary power source 60.

[0089] Another example of the main power source not being able to meet at least a portion of the applied load is when the main power source cannot meet the applied load at all, for example, when the main power source has no or only a minimal power output. In these situations, the HPFCS 12 can provide backup power to the energy-consuming device 46 and can thus also be referred to as a backup power source 58.

[0090] Another example where the primary power source is unable to meet at least a portion of the applied load is where the stability of the electrical output from the primary power source is lower than a critical stability level. In these situations, the HPFCS 12 can provide some or all of the power to the power-consuming device 46 and can thus be referred to as a supplementary power source 60 and / or a backup power source 58.

[0091] As discussed, the controller 100 can at least in part control the operation of the hydrogen-producing fuel processing system 10 and / or at least a portion of the HPFCS 12 based on the states of the various components of the hydrogen-producing fuel processing system 10 and / or calculations within the controller. Examples of the status signal 102 can include the controller 100 receiving a status signal indicating the operating state of the various components of the hydrogen-producing fuel processing system 10, as well as the temperature of the components and / or the temperature, pressure, concentration, flow rate, and / or humidity of the fluid contained therein. More specific examples include the controller 100 receiving a status signal 102 indicating the hydrogen supply variable, the hydrogen flow rate, and / or the hydrogen supply pressure. Additional examples include the controller 100 receiving a status signal 102 indicating the hydration level of the fuel cell stack, the electrical impedance of the fuel cell stack, the current of the fuel cell stack, the pressure within the separation assembly 80, the temperature of the components within the heated containment structure 70, and / or the ability of the primary power source 52 to meet the electrical load imposed by the power-consuming device 46.

[0092] In the context of the method 200, the controller 100 can be programmed or otherwise configured to initiate the supply of a stored hydrogen gas stream 112 containing stored hydrogen 79 to the fuel cell stack 40, for example, by opening a stored hydrogen supply valve 118 that selectively permits or restricts the flow of the stored hydrogen gas stream 112 through the stored hydrogen supply conduit 110. As another example, the controller 100 can cause the fuel cell stack 40 to generate an electrical output 41 and / or can monitor the generation of the power output by the fuel cell stack.

[0093] As yet another example, the controller 100 can monitor the hydrogen supply variable that indicates the flow rate of the stored hydrogen gas stream 112 to the fuel cell stack 40. The hydrogen supply variable can be monitored using one or more hydrogen supply variable detectors 130 and can be monitored during a supply time interval after the initiation of the supply of the stored hydrogen gas stream to the fuel cell stack. In other words, the hydrogen supply variable detector can be configured to detect a parameter that indicates the hydrogen supply variable.

[0094] As a more specific example, the hydrogen supply variable detector 130 may include a pressure detector 132. The pressure detector 132 may be utilized to detect the hydrogen supply pressure of the stored hydrogen 79, such as within and / or proximate to the low-pressure hydrogen storage tank 78. At the onset of the supply of the stored hydrogen to the fuel cell stack, a certain degree of decrease in the hydrogen supply pressure may be anticipated. However, the controller 100 may be programmed to respond if and only if the decrease in the hydrogen supply pressure is greater than an expected hydrogen supply pressure change. Such a decrease may be, for example, the result of hydrogen leakage within and / or in the fuel cell stack 40 of the HPFCS 12.

[0095] As another more specific example, the hydrogen supply variable detector 130 may include a hydrogen flow meter 134. The hydrogen flow meter 134 may be utilized to detect the hydrogen supply flow rate of the stored hydrogen 79, such as through the stored hydrogen supply conduit 110, downstream of the low-pressure hydrogen storage tank 78, and / or upstream of the fuel cell stack 40. At the onset of the supply of the stored hydrogen to the fuel cell stack, a certain degree of hydrogen supply flow rate may be anticipated. However, the controller 100 may be programmed to respond if and only if the hydrogen supply flow rate is greater than an expected flow rate. Such an increase in the hydrogen supply flow rate may be, for example, the result of hydrogen leakage within the HPFCS and / or in the fuel cell stack.

[0096] Additional examples of parts of the hydrogen production fuel processing system 10 that can be monitored and / or controlled (i.e., adjusted, regulated, changed, maintained, etc.) by the controller 100 include any valves, fluid processors, pumps, compressors, flow regulating devices, temperature regulating devices, electrical energy regulating devices, pressure regulating devices, and the like. More specific examples include the controller 100 controlling the flow rate of the feed stream 16, which is, for example, by controlling the operation of various pumps, compressors, valves, and / or mass flow controllers included in the feed delivery system 22; the controller 100 controlling the temperature of the heated containment structure 70 and / or various components of the fuel processing system 10, which is, for example, by controlling the supply of electrical energy to the electrical heating assembly 93 and / or the flow rate of the combustible fuel and / or oxidant to the burner assembly 92; the controller 100 controlling the temperature of the hydrogen production region 19 and / or the separation assembly 80; the controller 100 controlling the consumption of the power output 41 by the energy consuming device 46; the controller 100 controlling the concentration of one or more materials included within the hydrogen production fuel processing system 10; the controller 100 controlling the flow rate of the mixed gas stream 20, the product hydrogen gas stream 14, the oxidant-containing stream 49, and / or the by-product stream 68; the controller 100 controlling the pressure within the separation assembly 80; and / or the controller 100 controlling the operation and / or operating state of the various components that make up the hydrogen production fuel processing system 10, such as the feed delivery system 22, the hydrogen production region 19, the separation assembly 80, and / or the fuel cell stack 40.

[0097] The controller 100 can include any suitable type and number of devices or mechanisms to implement and provide the desired monitoring and / or control of the hydrogen production fuel processing system 10 and / or one or more components of the HPFCS 12. For example, a suitable controller can be in the form of analog or digital circuitry and appropriate electronic instructions, which instructions can be stored on a magnetic medium or a programmable memory, such as a read only memory (ROM), a programmable read only memory (PROM), or an erasable programmable read only memory (EPROM), and can be integrated into one or more systems or components of the hydrogen production fuel processing system 10 and / or the HPFCS 12 or a separate stand-alone computing device. The controller can be adapted or programmed or designed to control the operation of the hydrogen production fuel processing system 10 and / or the HPFCS 12 (including its various components) during several operating intervals of the system.

[0098] For example, controller 100 may include one or more of an electronic controller, a dedicated controller, a special-purpose controller, a personal computer, a special-purpose computer, a display device, a logic device, a memory device, and / or a memory device having a computer-readable storage medium. When present, this computer-readable storage medium may also be referred to herein as non-transitory computer-readable storage medium 106. This non-transitory computer-readable storage medium may contain, define, place, and / or store computer-executable instructions, programs, and / or code; and these computer-executable instructions may direct hydrogen production fuel processing system 10 and / or HPFCS 12 to perform any suitable portion or subset of method 200.

[0099] Examples of such non-transitory computer-readable storage media include CD-ROMs, disks, hard disk drives, flash memories, and the like. As used herein, storage or memory, devices, and / or media having computer-executable instructions in accordance with the present disclosure, as well as computer-implemented methods and other methods, are considered to be within the scope of subject matter eligible for patenting under 35 U.S.C. § 101.

[0100] Additional examples of controller 100 in accordance with the present disclosure are described in U.S. Patent Nos. 6,383,670, 6,495,277, 6,811,908, 6,835,481, 6,979,507, 7,208,241, and 7,390,587, as well as in U.S. Patent Application Publication Nos. 2005 / 0266284, 2005 / 0266285, 2006 / 0024540, 2006 / 0134473, and 2008 / 0176118, the entire disclosures of which are hereby incorporated by reference.

[0101] The hydrogen-producing fuel processing system 10 and / or HPFCS 12 according to the present disclosure may comprise (i.e., be configured and / or controlled to operate in or at) a plurality of operating intervals. The controller 100 may be utilized to configure or transition the hydrogen-producing fuel processing system 10 and / or HPFCS 12 to and / or between the plurality of operating intervals, and / or to maintain the hydrogen-producing fuel processing system 10 and / or HPFCS 12 in a selected operating interval. An example of an operating (or operational) interval is a “hydrogen production” interval, in which the fuel processing system produces the product hydrogen stream from the one or more feed streams at an appropriate capacity to meet the hydrogen demand of the fuel cell system 42 to produce an electrical output. As discussed above, in the hydrogen production interval, the feed delivery system supplies the one or more feed streams to the hydrogen production zone, the hydrogen production zone produces the mixed gas stream, and the separation component separates the mixed gas stream into the product hydrogen stream and the by-product stream.

[0102] Additional examples of an operating (or operational) interval include: a “shutdown” interval, in which the fuel processing system may not be heated and may not receive a feed stream or produce a mixed gas stream; and a “start-up” (and / or “idle”) interval, in which the fuel processing system may be maintained at an elevated thermal buffer temperature but does not receive the feed stream and / or produce the mixed gas stream. Examples of buffer or start-up temperatures and temperature ranges are discussed herein.

[0103] In the present disclosure, several of the illustrated non-exclusive examples have been discussed and / or presented in the context of flowcharts, where the method is shown and described as a series of blocks or steps. Unless explicitly set forth in the accompanying description, within the scope of the present disclosure is that the order of the blocks may be different from the order illustrated in the flowchart, including where two or more of the blocks (or steps) occur in a different order and / or simultaneously. Also within the scope of the present disclosure is that the blocks or steps may be implemented as logic, which may also be described as implementing the blocks or steps as logic. In some applications, the blocks or steps may represent expressions and / or actions that will be performed by functionally equivalent circuits or other logic devices. The illustrated blocks may (but need not) represent executable instructions that cause a computer, processor, and / or other logic device to respond to perform an action, change state, produce an output or display, and / or make a decision.

[0104] As used herein, the term "and / or" placed between a first entity and a second entity is meant to represent one of the following: (1) the first entity, (2) the second entity, and (3) the first entity and the second entity. Multiple entities listed by "and / or" should be interpreted in the same way, i.e., "one or more" of the entities so combined. Entities other than those explicitly specified by the "and / or" clause may optionally exist, regardless of whether they are related or unrelated to those explicitly specified. Thus, as a non-limiting example, a reference to "A and / or B" when used in conjunction with open-ended language such as "comprising" may, in one embodiment, refer to only A (optionally including entities other than B); in another embodiment, it may refer to only B (optionally including entities other than A); in yet another embodiment, it may refer to both A and B (optionally including other entities). These entities may refer to elements, actions, structures, steps, operations, values, and the like.

[0105] As used herein, the phrase "at least one" with respect to one or more entities of a listing should be understood to mean at least one entity selected from any one or more of the entities of the listing, but not necessarily including at least one of every entity expressly listed in the entities of the listing, and not excluding any combination of entities in the listing. This definition also allows for entities to optionally exist, whether or not they are related or unrelated to those expressly specified entities, in addition to the entities expressly specified in the listing of entities to which the phrase "at least one" refers. Thus, as a non-limiting example, "at least one of A and B" (or equivalently "at least one of A or B" or equivalently "at least one of A and / or B") can, in one embodiment, mean at least one (optionally including more than one) A with no B present (and optionally including entities other than B); in another embodiment can mean at least one (optionally including more than one) B with no A present (and optionally including entities other than A); and in yet another embodiment can mean at least one (optionally including more than one) A and at least one (optionally including more than one) B (and optionally including other entities). In other words, the phrases "at least one", "one or more", and "and / or" are open-ended expressions that are both conjunctive and disjunctive in operation. For example, each of the expressions "at least one of A, B, and C", "at least one of A, B, or C", "one or more of A, B, and C", "one or more of A, B, or C", and "A, B, and / or C" can represent only A, only B, only C, A and B together, A and C together, B and C together, A, B, and C together, and optionally any one of the foregoing in combination with at least one other entity.

[0106] In the event that any patent, patent application, or other reference is incorporated herein by reference and (1) defines a term in a manner that is inconsistent with any one of the non-incorporated portions of the present disclosure or any other incorporated reference, and / or (2) is otherwise inconsistent with any one of the non-incorporated portions of the present disclosure or any other incorporated reference, the term or the incorporated disclosure therein should be construed in accordance with the non-incorporated portion of the present disclosure, such that the term or the incorporated disclosure therein should be construed only with respect to the relevant reference in which the term is defined and / or the originally existing incorporated disclosure.

[0107] As used herein, the terms "adapted" and "configured" denote that the element, component, or other subject is designed and / or intended to perform a given function. Thus, the use of the terms "adapted" and "configured" should not be construed to mean that a given element, component, or other subject is merely "able to" perform a given function, but rather that the element, component, and / or other subject has been specifically selected, created, implemented, utilized, programmed, and / or designed for the purpose of performing the function. Also within the scope of the present disclosure, an element, component, and / or other subject described as adapted to perform a particular function may additionally or alternatively be described as configured to perform that function, and vice versa.

[0108] As used herein, the phrases "for example," "for instance," and / or simply the term "example," when used in reference to one or more components, features, details, structures, embodiments, and / or methods according to the present disclosure, are intended to convey that the component, feature, detail, structure, embodiment, and / or method is an illustrative, non-exclusive example of a component, feature, detail, structure, embodiment, and / or method according to the present disclosure. Thus, the component, feature, detail, structure, embodiment, and / or method is not intended to be restrictive, essential, or exhaustive; and other components, features, details, structures, embodiments, and / or methods (including components, features, details, structures, embodiments, and / or methods that are structurally and / or functionally similar and / or equivalent) are also within the scope of the present disclosure.

[0109] As used herein, when "at least substantially" modifies a degree or relationship, it includes not only the stated degree or relationship of "substantially," but also the entire range of the stated degree or relationship. A substantial amount of a stated degree or relationship may include at least 75% of the stated degree or relationship. For example, an object that is at least substantially formed of a material includes an object in which at least 75% of the object is formed of the material, and also includes an object that is entirely formed of the material. As another example, a first length that is at least substantially as long as a second length includes a first length that is within 75% of the second length, and also includes a first length that is as long as the second length.

[0110] Illustrative, non-exclusive examples of systems and methods according to the present disclosure are presented in the paragraphs listed below. Within the scope of the present disclosure, an individual step of a method described herein included in the paragraphs listed below may additionally or alternatively be referred to as a "step" for performing the stated action.

[0111] A1. A method of operating a hydrogen production fuel cell system (HPFCS), the method comprising:

[0112] Initiating a supply of a stored hydrogen gas stream containing stored hydrogen to a fuel cell stack, wherein prior to the initiation, the stored hydrogen is stored in a low-pressure hydrogen storage tank at a hydrogen storage pressure;

[0113] Utilizing the fuel cell stack to generate an electrical output from the stored hydrogen;

[0114] During a supply time interval after the initiation, monitoring a hydrogen supply variable indicative of the flow rate of the stored hydrogen gas stream to the fuel cell stack;

[0115] Detecting a change in the hydrogen supply variable; and

[0116] Responding to the detection.

[0117] A2. The method according to paragraph A1, wherein the initiation comprises opening a stored hydrogen supply valve.

[0118] A3. The method according to paragraph A2, wherein the HPFCS comprises a stored hydrogen supply conduit configured to convey the stored hydrogen gas stream from the low-pressure hydrogen storage tank to the fuel cell stack, and further wherein opening the stored hydrogen supply valve comprises allowing the flow of stored hydrogen from the low-pressure hydrogen storage tank through the stored hydrogen supply conduit to the fuel cell stack.

[0119] A4. The method according to any one of paragraphs A1 to A3, wherein the initiation comprises causing the stored hydrogen gas stream to flow from the low-pressure hydrogen storage tank, through a stored hydrogen supply pressure regulator to the fuel cell stack, wherein the stored hydrogen supply pressure regulator is configured to regulate a supply pressure of the stored hydrogen to the fuel cell stack.

[0120] A5. The method according to any one of paragraphs A1 to A4, wherein the hydrogen storage pressure is at least one of the following:

[0121] (i) At least 75 kPag; at least 80 kPag, at least 85 kPag, at least 90 kPag, at least 95 kPag, at least 100 kPag, at least 105 kPag, at least 110 kPag, at least 115 kPag, at least 120 kPag, at least 125 kPag, at least 130 kPag, at least 135 kPag, at least 140 kPag, at least 145 kPag, at least 150 kPag, at least 155 kPag, at least 160 kPag, at least 165 kPag, at least 170 kPag, at least 175 kPag, at least 180 kPag, at least 185 kPag or at least 190 kPag; and

[0122] (ii) At most 250 kPag, at most 240 kPag, at most 230 kPag, at most 220 kPag, at most 210 kPag, at most 200 kPag, at most 195 kPag, at most 190 kPag, at most 185 kPag or at most 180 kPag.

[0123] A6. A method according to any one of paragraphs A1 to A5, wherein the supply time interval is at least one of the following:

[0124] (i) Starting immediately after the start; and

[0125] (ii) Initiated by the start.

[0126] A7. A method according to any one of paragraphs A1 to A6, wherein a duration of the supply time interval is at least one of the following:

[0127] (i) At least 5 seconds, at least 10 seconds, at least 15 seconds, at least 20 seconds, at least 25 seconds, at least 30 seconds, at least 35 seconds, at least 40 seconds, at least 45 seconds, at least 50 seconds, at least 55 seconds or at least 60 seconds; and

[0128] (ii) At most 120 seconds, at most 110 seconds, at most 100 seconds, at most 90 seconds, at most 80 seconds, at most 70 seconds, at most 60 seconds, at most 55 seconds, at most 50 seconds, at most 45 seconds, at most 40 seconds, at most 35 seconds or at most 30 seconds.

[0129] A8. A method according to any one of paragraphs A1 to A7, wherein the HPFCS includes a hydrogen supply variable detector, and further wherein the monitoring includes using the hydrogen supply variable detector to monitor the hydrogen supply variable.

[0130] A9. A method according to any one of paragraphs A1 to A8, wherein the hydrogen supply variable includes or is a hydrogen supply pressure for storing hydrogen.

[0131] A10. The method as in paragraph A9, wherein the monitoring comprises monitoring the hydrogen supply pressure of at least one of the following:

[0132] (i) in the low-pressure hydrogen storage tank;

[0133] (ii) downstream of the low-pressure hydrogen storage tank;

[0134] (iii) upstream of a / the hydrogen storage supply valve; and

[0135] (iv) upstream of a / the hydrogen storage supply pressure regulator.

[0136] A11. The method as in any one of paragraphs A1 to A10, wherein the detection comprises detecting a change in the hydrogen supply variable that is greater than a change in a critical hydrogen supply variable.

[0137] A12. The method as in any one of paragraphs A9 to A11, wherein the detection comprises, during the supply time interval, calculating a change in the hydrogen supply pressure as a difference between the hydrogen supply pressure before the start and the hydrogen supply pressure after the start.

[0138] A13. The method as in any one of paragraphs A1 to A12, wherein the change in the critical hydrogen supply variable comprises or is a critical hydrogen supply pressure change, and optionally wherein the critical hydrogen supply pressure change is 30 kPa, 35 kPa, 40 kPa, 45 kPa, 50 kPa, 55 kPa, 60 kPa, 65 kPa, 70 kPa, 75 kPa, 80 kPa, 85 kPa, 90 kPa, 95 kPa, 100 kPa, 105 kPa, 110 kPa, 115 kPa, 120 kPa, 125 kPa, 130 kPa, 135 kPa or 140 kPa.

[0139] A14. The method as in any one of paragraphs A12 to A13, wherein the critical hydrogen supply pressure change is a critical pressure change multiple of a nominal supply pressure change that occurs during the supply time interval during normal operation of the HPFCS.

[0140] A15. The method as in paragraph A14, wherein the critical pressure change multiple is 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5 or 7.

[0141] A16. A method as in any one of paragraphs A14 to A15, wherein the nominal supply pressure change is at most 5 kPa, at most 7.5 kPa, at most 10 kPa, at most 12.5 kPa, at most 15 kPa, at most 17.5 kPa or at most 20 kPa.

[0142] A17. A method as in any one of paragraphs A1 to A16, wherein the hydrogen supply variable comprises or is a hydrogen gas flow rate of the stored hydrogen gas stream.

[0143] A18. The method as in paragraph A17, wherein the monitoring comprises monitoring the hydrogen gas flow rate of at least one of the following:

[0144] (i) downstream of the low-pressure hydrogen storage tank; and

[0145] (ii) upstream of the fuel cell stack.

[0146] A19. A method as in any one of paragraphs A1 to A18, wherein the change in the critical hydrogen supply variable comprises or is a critical hydrogen supply flow rate magnitude.

[0147] A20. The method as in paragraph A19, wherein the critical hydrogen supply flow rate magnitude is a critical flow rate multiple of a nominal hydrogen gas flow rate magnitude, which occurs during the supply time interval and during normal operation of the HPFCS, and optionally wherein the critical flow rate multiple is 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5 or 7.

[0148] A21. A method as in any one of paragraphs A19 to A20, wherein the fuel cell stack has a maximum design wattage, and further wherein the critical hydrogen supply flow rate magnitude is a wattage multiple of the maximum design wattage.

[0149] A22. The method as in paragraph A21, wherein the wattage multiple is 18 standard liters per minute per kilowatt (SLPM / kW), 20 SLPM / kW, 30 SLPM / kW, 40 SLPM / kW, 50 SLPM / kW, 60 SLPM / kW, 70 SLPM / kW, 80 SLPM / kW or 90 SLPM / kW.

[0150] A23. A method as in any one of paragraphs A1 to A22, wherein the response comprises responding to whether the detected change in the hydrogen supply variable is different from a change in a critical hydrogen supply variable.

[0151] A24. A method as in any one of paragraphs A1 to A23, wherein the response comprises determining the presence of a hydrogen leak in at least one of the following:

[0152] (i) within the HPFCS;

[0153] (ii) downstream of the low-pressure hydrogen storage tank; and

[0154] (iii) within the fuel cell stack.

[0155] A25. The method according to any one of paragraphs A1 to A24, wherein said initiating comprises initiating the supply of the stored hydrogen gas stream to a given fuel cell stack among the plurality of fuel cell stacks of the HPFCS, and further wherein said responding comprises stopping the supply of the stored hydrogen gas stream to the given fuel cell stack.

[0156] A26. The method according to paragraph A25, wherein the method further comprises at least one of the following:

[0157] (i) after said stopping, maintaining the supply of the stored hydrogen gas stream to another fuel cell stack among the plurality of fuel cell stacks; and

[0158] (ii) after said stopping, repeating said initiating to supply the stored hydrogen gas stream to said another fuel cell stack among the plurality of fuel cell stacks.

[0159] A27. The method according to any one of paragraphs A1 - A26, wherein said responding comprises initiating a system diagnostic test of the HPFCS.

[0160] A28. The method according to any one of paragraphs A1 to A27, wherein said responding comprises notifying an operator of the HPFCS that a possible hydrogen leak exists within the HPFCS.

[0161] A29. The method according to any one of paragraphs A1 to A28, wherein said responding comprises stopping the operation of the HPFCS.

[0162] A30. The method according to any one of paragraphs A1 to A29, wherein said responding comprises stopping the supply of the stored hydrogen gas stream to the fuel cell stack.

[0163] A31. The method according to any one of paragraphs A1 to A30, wherein the method further comprises generating hydrogen gas by:

[0164] (i) providing a feed stream comprising a carbonaceous feedstock to a fuel processing assembly of the HPFCS;

[0165] (ii) utilizing the fuel processing assembly from the feed stream to generate a product hydrogen gas stream comprising the generated hydrogen gas; and

[0166] (iii) Supplying the product hydrogen stream to the low-pressure hydrogen storage tank as the stored hydrogen.

[0167] A32. The method according to paragraph A31, wherein the method further comprises determining that a power-consuming device has a demand for the power output, and further wherein the initial supply of the stored hydrogen and the generation of the hydrogen are performed in response to the determination.

[0168] A33. The method according to paragraph A32, wherein the method further comprises reducing the mass of the stored hydrogen in the low-pressure hydrogen storage tank during a start-up time range for the fuel processing assembly.

[0169] A34. The method according to any one of paragraphs A32 to A33, wherein the supply time interval is an initial supply time, which is at least one of the following:

[0170] (i) Starting immediately after the start; and

[0171] (ii) Being started by the start.

[0172] A35. The method according to paragraph A31, wherein after a start-up time range for the fuel processing assembly, the method further comprises at least one of the following:

[0173] (i) Supplying the stored hydrogen by the flow of the generated hydrogen stream to the low-pressure hydrogen storage tank; and

[0174] (ii) Using the generated hydrogen stream to pressurize the low-pressure hydrogen storage tank to the hydrogen storage pressure.

[0175] A36. The method according to paragraph A35, wherein the supply time interval is at least one of the following:

[0176] (i) Occurring during the replenishment period; and

[0177] (ii) Occurring during the pressurization period.

[0178] A37. The method according to any one of paragraphs A1 to A36, wherein the method further comprises, during a purge time interval, using the stored hydrogen stream to purge the fuel cell stack, and further wherein the supply time interval does not include the purge time interval.

[0179] A38. The method according to paragraph A37, wherein the method comprises omitting the response during the purge time interval.

[0180] A39. The method as in paragraph A37, wherein the omission includes an omission during an omission time period, and the omission time period is a critical omission time multiple of the purge time interval.

[0181] A40. The method as in paragraph A39, wherein the critical omission time multiple is at least one of the following:

[0182] (i) at least 1.25, at least 1.5, at least 1.75, at least 2, at least 2.5, at least 3, at least 4, or at least 5; and

[0183] (ii) at most 10, at most 9, at most 8, at most 7, at most 6, at most 5, at most 4, at most 3, or at most 2.

[0184] B1. A hydrogen-producing fuel cell system (HPFCS) comprising:

[0185] A feedstock delivery system configured to provide a feedstock stream comprising a carbonaceous feedstock;

[0186] A fuel processing assembly configured to receive the feedstock stream from the feedstock stream and produce a product hydrogen stream comprising produced hydrogen;

[0187] A low-pressure hydrogen storage tank configured to receive and store hydrogen as stored hydrogen;

[0188] A fuel cell stack;

[0189] A stored hydrogen supply conduit configured to convey a stored hydrogen stream comprising the stored hydrogen to the fuel cell stack, wherein the fuel cell stack is configured to receive the stored hydrogen stream and produce an electrical output from the stored hydrogen stream; and

[0190] A controller programmed to control the operation of the HPFCS according to the method of any one of paragraphs A1 to A40.

[0191] B2. The HPFCS as in paragraph B1, wherein the low-pressure hydrogen storage tank is configured to receive and store at least a portion of the product hydrogen stream as the stored hydrogen.

[0192] B3. The HPFCS as in paragraphs B1 to B2, wherein the fuel processing assembly comprises a hydrogen production zone configured to receive the feedstock stream and produce a mixed gas stream comprising hydrogen and other gases from the feedstock stream.

[0193] B4. The HPFCS as in paragraph B3, wherein the hydrogen production zone comprises a reformer.

[0194] B5. The HPFCS as in any one of paragraphs B3 to B4, wherein the fuel processing assembly includes a separation assembly configured to receive the mixed gas stream and generate a by-product stream containing a major portion of the other gas, and the product hydrogen gas stream.

[0195] B6. The HPFCS as in paragraph B5, wherein the separation assembly includes at least one of a membrane separation assembly and a pressure swing adsorption separation assembly.

[0196] B7. The HPFCS as in any one of paragraphs B1 to B6, wherein the HPFCS further includes a stored hydrogen supply valve configured to selectively regulate the flow rate of the stored hydrogen gas stream within the stored hydrogen supply conduit.

[0197] B8. The HPFCS as in any one of paragraphs B1 to B7, wherein the HPFCS further includes a stored hydrogen supply pressure regulator configured to regulate a hydrogen supply pressure of the stored hydrogen gas stream received by the fuel cell stack.

[0198] B9. The HPFCS as in any one of paragraphs B1 to B8, wherein the HPFCS further includes a hydrogen supply variable detector configured to detect a parameter indicating the hydrogen supply variable.

[0199] B10. The HPFCS as in paragraph B9, wherein the hydrogen supply variable detector includes or is a pressure detector.

[0200] B11. The HPFCS as in paragraph B10, wherein the pressure detector is configured to detect the hydrogen supply pressure of at least one of the following:

[0201] (i) In the low-pressure hydrogen storage tank;

[0202] (ii) Downstream of the low-pressure hydrogen storage tank;

[0203] (iii) Upstream of a / the stored hydrogen supply valve; and

[0204] (iv) Upstream of a / the stored hydrogen supply pressure regulator.

[0205] B12. The HPFCS as in any one of paragraphs B10 to B11, wherein the hydrogen supply variable detector includes or is a hydrogen flow meter configured to detect a hydrogen supply flow rate of the stored hydrogen gas stream.

[0206] B13. The HPFCS as in paragraph B12, wherein the hydrogen flow meter is configured to detect the hydrogen supply flow rate of at least one of the following:

[0207] (i) downstream of the low-pressure hydrogen storage tank; and

[0208] (ii) upstream of the fuel cell stack.

[0209] C1. A non-transitory computer-readable storage medium containing computer-readable instructions which, when executed, direct a hydrogen-producing fuel cell system to perform a method as in any one of paragraphs A1 to A40.

[0210] D1. Use of a method as in any one of paragraphs A1 to A40, which utilizes any one of the hydrogen-producing fuel cell systems as in any one of paragraphs B1 to B13.

[0211] D2. Use of any one of the hydrogen-producing fuel cell systems as in any one of paragraphs B1 to B13, which utilizes a method as in any one of paragraphs A1 to A40.

[0212] D3. Use of a hydrogen supply variable to indicate a hydrogen leak within a hydrogen-producing fuel cell system.

[0213] Industrial Applicability

[0214] The hydrogen-producing fuel cell systems and methods disclosed herein are applicable to the industries of hydrogen production and energy generation, which include the fuel cell industry.

[0215] It is believed that the present disclosure set forth above includes a plurality of significant inventions having independent utilities. Although each of these inventions has been disclosed in its preferred form, the specific embodiments thereof as disclosed and described herein are not to be taken in a limiting sense, as many variations are possible. The subject matter of the invention includes all novel and non-obvious combinations and sub-combinations of the various elements, features, functions, and / or properties disclosed herein. Similarly, when the claims recite "a" or "a first" element or the like, such claims should be understood to include the incorporation of one or more such elements, which neither necessarily nor exclude two or more such elements.

[0216] It is believed that the following claims particularly point out certain combinations and sub-combinations that are novel and non-obvious with respect to one of the inventions disclosed. Inventions embodied in other combinations and sub-combinations of features, functions, elements, and / or properties may be claimed by amendment of the claims, or the presentation of new claims in this application or a related application. Such amendments or new claims, whether they are directed to a different invention or the same invention; whether they are broader, narrower, or equivalent in scope compared to the original claims, are also considered to be included within the subject matter of the inventions disclosed herein.

Claims

1. A method of operating a hydrogen-producing fuel cell system, the method comprising: initiating a supply of stored hydrogen gas stored in a low-pressure hydrogen storage tank at a hydrogen storage pressure to a fuel cell stack, wherein prior to the initiation, the stored hydrogen gas is stored in the low-pressure hydrogen storage tank; utilizing the fuel cell stack to generate an electrical output from the stored hydrogen gas; during a supply time interval after the initiation, monitoring a hydrogen supply variable that indicates a flow rate of the stored hydrogen gas flowing to the fuel cell stack; detecting a change in the hydrogen supply variable that is greater than a change in a critical hydrogen supply variable; and responding to the detection.

2. The method according to claim 1, wherein the hydrogen storage pressure is at least 75 kPa gauge (kPa g) and at most 250 kPa g.

3. The method according to claim 1, wherein the supply time interval is at least one of the following: (i) starting immediately after the initiation; and (ii) initiated by the initiation.

4. The method according to claim 1, wherein the duration of the supply time interval is at least 5 seconds and at most 120 seconds.

5. The method according to claim 1, wherein the hydrogen-producing fuel cell system includes a hydrogen supply variable detector, and further wherein the monitoring includes using the hydrogen supply variable detector to monitor the hydrogen supply variable.

6. The method according to claim 1, wherein the hydrogen supply variable includes a hydrogen supply pressure of the stored hydrogen gas, and further wherein the monitoring includes monitoring the hydrogen supply pressure of at least one of the following: (i) in the low-pressure hydrogen storage tank; and (ii) downstream of the low-pressure hydrogen storage tank.

7. The method according to claim 6, wherein the detecting includes calculating a change in the hydrogen supply pressure during the supply time interval as a difference between the hydrogen supply pressure before the initiation and the hydrogen supply pressure after the initiation.

8. The method according to claim 1, wherein the hydrogen supply variable includes a hydrogen supply pressure of the stored hydrogen gas, and further wherein the monitoring includes monitoring the hydrogen supply pressure of at least one of the following: (i) upstream of a stored hydrogen supply valve; and (ii) upstream of a stored hydrogen supply pressure regulator.

9. The method according to claim 8, wherein the detecting includes calculating a change in the hydrogen supply pressure during the supply time interval as a difference between the hydrogen supply pressure before the initiation and the hydrogen supply pressure after the initiation.

10. The method according to claim 1, wherein the change in the critical hydrogen supply variable includes a critical hydrogen supply pressure change of 30 kPa.

11. The method according to claim 10, wherein the critical hydrogen supply pressure change is a critical pressure change multiple of a nominal supply pressure change that occurs during the supply time interval during normal operation of the hydrogen-producing fuel cell system, wherein the critical pressure change multiple is 1.

5.

12. The method according to claim 1, wherein the hydrogen supply variable includes the hydrogen flow rate of the stored hydrogen gas stream.

13. The method according to claim 12, wherein the monitoring includes monitoring the hydrogen flow rate of at least one of the following: (i) downstream of the low-pressure hydrogen storage tank; and (ii) upstream of the fuel cell stack.

14. The method according to claim 13, wherein the change in the critical hydrogen supply variable includes the magnitude of the critical hydrogen supply flow rate.

15. The method according to claim 14, wherein the magnitude of the critical hydrogen supply flow rate is a multiple of the critical flow rate of the nominal hydrogen flow rate magnitude, which occurs during the supply time interval and during the normal operation of the hydrogen-producing fuel cell system, wherein the multiple of the critical flow rate is 1.

5.

16. The method according to claim 14, wherein the fuel cell stack has a maximum design wattage, and further wherein the magnitude of the critical hydrogen supply flow rate is a multiple of the wattage of the maximum design wattage, wherein the multiple of the wattage is 18 standard liters per kilowatt per minute.

17. The method according to claim 1, wherein the response includes determining the presence of a hydrogen leak in at least one of the following: (i) within the hydrogen-producing fuel cell system; (ii) downstream of the low-pressure hydrogen storage tank; and (iii) within the fuel cell stack.

18. The method according to claim 1, wherein the response includes at least one of the following: (i) initiating a system diagnostic test of the hydrogen-producing fuel cell system; (ii) notifying the operator of the hydrogen-producing fuel cell system of the possible presence of a hydrogen leak within the hydrogen-producing fuel cell system; (iii) stopping the operation of the hydrogen-producing fuel cell system; and (iv) stopping the supply of the stored hydrogen gas stream to the fuel cell stack.

19. The method according to claim 1, wherein the initiating includes initiating the supply of the stored hydrogen gas stream to a given fuel cell stack among a plurality of fuel cell stacks of the hydrogen-producing fuel cell system, and further wherein the response includes stopping the supply of the stored hydrogen gas stream to the given fuel cell stack.

20. The method according to claim 19, wherein the method further includes, after the stopping, maintaining the supply of the stored hydrogen gas stream to another fuel cell stack among the plurality of fuel cell stacks.

21. The method according to claim 19, wherein the method further includes, after the stopping, repeating the initiating to supply the stored hydrogen gas stream to the another fuel cell stack among the plurality of fuel cell stacks.

22. The method according to claim 1, wherein the method further includes producing hydrogen by: (i) providing a feed stream containing a carbonaceous feedstock to a fuel processing assembly of the hydrogen-producing fuel cell system; (ii) using the fuel processing assembly to produce a product hydrogen gas stream from the feed stream, the product hydrogen gas stream containing the produced hydrogen; and (iii) providing the product hydrogen gas stream to the low-pressure hydrogen storage tank as the stored hydrogen gas.

23. The method according to claim 22, wherein the method further comprises determining that the energy-consuming device has a demand for the power output, and further wherein the initial supply of the stored hydrogen and the generation of the hydrogen are both performed in response to the determination.

24. The method according to claim 22, wherein after a start-up time period for the fuel processing assembly, the method further comprises at least one of the following: (i) replenishing the stored hydrogen by flow of the generated hydrogen to the low-pressure hydrogen storage tank; and (ii) pressurizing the low-pressure hydrogen storage tank to the hydrogen storage pressure using the generated hydrogen.

25. The method according to claim 24, wherein the supply time interval is at least one of the following: (i) occurs during the replenishing; and (ii) occurs during the pressurizing.

26. The method according to claim 1, wherein the method further comprises purging the fuel cell stack using the stored hydrogen flow during a purge time interval, and further wherein the supply time interval excludes the purge time interval.

27. A hydrogen-producing fuel cell system, which comprises: a feedstock delivery system configured to provide a feedstock stream comprising a carbonaceous feedstock; a fuel processing assembly configured to receive the feedstock stream and produce a product hydrogen stream from the feedstock stream, the product hydrogen stream comprising generated hydrogen; a low-pressure hydrogen storage tank configured to receive at least a portion of the product hydrogen stream and store at least a portion of the product hydrogen stream as stored hydrogen; a fuel cell stack; a stored hydrogen supply conduit configured to deliver a stored hydrogen flow comprising the stored hydrogen to the fuel cell stack, wherein the fuel cell stack is configured to receive the stored hydrogen flow and generate a power output from the stored hydrogen flow; and a controller programmed to control the operation of the hydrogen-producing fuel cell system according to the method of claim 1.

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