Hydrogen generating fuel cell system and method of operating same

Abstract

A hydrogen-producing fuel cell system and method for operating the same. The method includes initiating a supply of a stored hydrogen stream, including stored hydrogen gas, to a fuel cell stack. Prior to the initiating step, the stored hydrogen gas is stored in a low-pressure hydrogen storage tank at a hydrogen storage pressure. The method also includes generating electrical power from the stored hydrogen gas using the fuel cell stack. The method further includes monitoring a hydrogen supply variable indicative of flow of the stored hydrogen stream to the fuel cell stack during a supply time interval following the initiating step. The method also includes detecting a change in the hydrogen supply variable and responding to the detection. The system includes a controller programmed to execute the method.

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims priority to U.S. Patent Application No. 17 / 889,295, filed August 16, 2022, the complete disclosure of which is incorporated herein by reference.

[0002] FIELD OF THE DISCLOSURE The present disclosure relates generally to hydrogen-producing fuel cell systems and / or methods of operating same. [Background technology]

[0003] To produce hydrogen gas from a carbon-containing feedstock, a hydrogen-producing fuel cell system utilizes a hydrogen generator, such as a fuel reformer. The hydrogen-producing fuel cell system also includes at least one fuel cell stack configured to output electrical power using the hydrogen gas produced by the hydrogen generator. Some hydrogen-producing fuel cell systems are used as auxiliary or standby power sources to supplement or back up a primary source of electrical power, such as a power grid. Some hydrogen-producing fuel cell systems that include multiple fuel cell stacks selectively use these multiple fuel cell stacks depending on the demand or load for electrical power from the hydrogen-producing fuel cell system. In either situation, the hydrogen-producing fuel cell system may not be configured to properly supply hydrogen gas to the fuel cell stacks when the fuel cell stacks begin to output electrical power after a period in which they have not output electrical power. Therefore, a need exists for improved hydrogen-producing fuel cell systems and / or methods of operating the same. Summary of the Invention

[0004] Hydrogen-producing fuel cell systems (HPFCS) and methods for operating them include initiating a supply of a stored hydrogen stream comprising stored hydrogen gas to a fuel cell stack. Prior to the initiating step, the stored hydrogen gas is stored in a low-pressure hydrogen storage tank at a hydrogen storage pressure. The methods also include generating electrical power from the fuel cell stack using the stored hydrogen gas. The methods also include monitoring a hydrogen supply variable indicative of the rate at which the stored hydrogen stream is supplied to the fuel cell stack during a supply time interval after the supply initiation. The methods also include detecting and responding to a change in the hydrogen supply variable.

[0005] The systems include a feedstock supply system configured to supply a feedstock stream comprising a carbon-containing feedstock. The systems also include a fuel processing assembly configured to receive the feedstock stream and produce a product hydrogen stream comprising hydrogen gas produced from the feedstock stream. The systems also include at least one fuel cell stack configured to receive the gas and output electrical power from the produced hydrogen gas. The systems further include a low-pressure hydrogen storage tank configured to receive at least a portion of the product hydrogen stream and store the portion as stored hydrogen gas. The systems further include stored hydrogen supply piping configured to transport a stored hydrogen stream comprising the stored hydrogen gas from the low-pressure hydrogen storage tank to the at least one fuel cell stack. The systems also include a controller programmed to control operation of the HPFCS according to the methods. [Brief explanation of the drawings]

[0006] [Figure 1] 1 illustrates an example of a hydrogen producing and / or consuming assembly according to the present disclosure. [Figure 2] 1 is a flow chart illustrating an example method of operating a hydrogen-producing fuel cell system according to the present disclosure. [Figure 3]1 is a graph that schematically illustrates the magnitude of a hydrogen supply variable produced by or used in a hydrogen producing and / or consuming assembly as a function of time during start-up of a fuel processing assembly according to the present disclosure. [Figure 4] 1 is a graph that schematically illustrates the magnitude of a hydrogen supply variable produced by or used in a hydrogen producing and / or consuming assembly as a function of time during steady-state operation of a fuel processing assembly according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0007] 1 and 2 illustrate examples of a hydrogen-producing fuel processing system 10, a hydrogen-producing and / or consuming assembly 12, and a method 200 according to the present disclosure. In FIGS. 1 and 2, elements having similar or at least substantially similar purposes are labeled with the same reference numerals, and these elements may not be described in detail with respect to FIGS. 1 and 2, respectively. Similarly, not all elements are labeled in FIGS. 1 and 2, but associated numerals may be used throughout the text for consistency. Elements, components, and / or features described in connection with either or both of FIGS. 1 and 2 may be included in or utilized with either of FIGS. 1 and 2 without departing from the scope of the present disclosure. In general, elements likely to be included in a particular embodiment are indicated with solid lines, while optional elements are indicated with dashed lines. However, elements indicated with solid lines are not required for all embodiments and may be omitted in some embodiments without departing from the scope of the present disclosure.

[0008] FIG. 1 illustrates an example of a hydrogen producing and / or consuming assembly 12 according to the present disclosure. The hydrogen producing and consuming assembly 12 includes a hydrogen producing fuel processing system 10. The hydrogen producing fuel processing system 10 may be referred to herein as a fuel processing system 10, a hydrogen generation system 10, and / or a fuel reforming system 10. The hydrogen producing and consuming assembly 12 also includes at least one (i.e., one, multiple, or more) fuel cell stack 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 producing and consuming assembly 12 may also be referred to herein as a hydrogen producing fuel cell system (HPFCS) 12. The hydrogen producing fuel processing system 10 may optionally be in communication with an energy consuming device 46 and configured to provide a power output 41, e.g., to satisfy a load on the energy consuming device. Examples of energy consuming devices 46 are described in further detail herein.

[0009] In addition to fuel cell system 42 and / or one or more fuel cell stacks 40, a hydrogen-producing fuel cell system 12 according to the present disclosure includes a feedstock supply system 22, a fuel processing assembly 13, a low-pressure hydrogen storage tank 78, a stored hydrogen supply line 110, and a controller 100. Feedstock supply system 22 may be configured to supply at least one feedstock stream 16 to fuel processing assembly 13. Fuel processing assembly 13, in turn, is configured to receive at least one feedstock stream 16 and produce a product hydrogen stream 14 comprising hydrogen gas 25 produced from the feedstock stream. Fuel processing assembly 13 may include a hydrogen-producing region 19 that produces a mixed gas stream 20 comprising hydrogen gas and other gases, and may further include a separation assembly 80 that receives mixed gas stream 20 and separates the mixed gas stream 20 into product hydrogen stream 14 and at least one by-product stream 68.

[0010] The low-pressure hydrogen storage tank 78 is configured to store hydrogen gas as stored hydrogen gas 79, which may be stored in the low-pressure hydrogen storage tank at a hydrogen storage pressure, as described in further detail herein. The low-pressure hydrogen storage tank 78 may 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 gas 79. The stored hydrogen supply line 110 is configured to convey a stored hydrogen stream 112 comprising the stored hydrogen gas 79 from the low-pressure hydrogen storage tank 78 to at least one fuel cell stack 40 (forming part 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 power output 41 from the stored hydrogen stream.

[0011] Controller 100 is programmed or otherwise configured to monitor, regulate, and / or control the operation of the components of HPFCS 12. For example, as shown by the dashed lines in Figure 1, controller 100 may be configured to receive status signals 102 indicating the operational status of each component of hydrogen-producing fuel processing system 10. Controller 100 may also generate control signals 104 for controlling the operation of each component of hydrogen-producing fuel processing system 10 based at least in part on the values ​​of the status signals, calculations internal to the controller, and / or a control scheme.

[0012] This may include monitoring, regulating, and / or controlling at least one component of HPFCS 12 according to any suitable step and / or procedural step of method 200. In this context, controller 100 monitors a hydrogen supply variable indicative of the flow of stored hydrogen gas from low-pressure hydrogen storage tank 78, and controller 100 may be programmed or otherwise configured, for example, to detect changes in the hydrogen supply variable and respond accordingly. As detailed herein, the controller may be programmed or otherwise configured to detect changes in the hydrogen supply variable that exceed or differ from threshold changes, and upon detecting such a change, controller 100 may be configured to respond accordingly.

[0013] The components of the HPFCS 12 are described in further detail herein, along with options for the controller 100 to monitor, regulate, and control their operation. This description will initially focus on aspects of the HPFCS, followed by methods related to monitoring and responding to changes in hydrogen supply variables when the flow of stored hydrogen gas from the low-pressure hydrogen storage tank 78 to the fuel cell stack 40 is initiated.

[0014] 2 and described in detail herein provides an example of a control scheme that the controller 100 may utilize to control the components of the hydrogen-producing fuel processing system 10. However, within the scope of this disclosure, portions of the method 200 may be performed manually by a user.

[0015] 2 is a flowchart illustrating an example method 200 of operating a hydrogen-producing fuel cell system (HPFCS), such as the HPFCS 12 of FIG. 1 , according to the present disclosure. Method 200 may include determining demand 205 and initiating a supply of stored hydrogen gas 210. Method 200 may also include reducing the mass of the stored hydrogen gas 215, generating hydrogen gas 220, and / or replenishing the stored hydrogen gas 225. Method 200 also includes generating a power output 230, monitoring a hydrogen supply variable 235, and detecting a change in the hydrogen supply variable 240. Method 200 may further include purging the fuel cell stack 245 and corresponding step 250.

[0016] Determining 205 the demand may include, for example, determining that the demand for power output from the fuel cell stack is being generated by an energy consuming device, examples of which are disclosed herein with reference to energy consuming device 46.

[0017] If method 200 includes determining step 205, initiating supplying step 210 and / or generating hydrogen step 220 may be based at least in part on determining step 205. In other words, initiating step 210 and / or generating step 220 may be performed, initiated, and / or continued based on determining step 205. In some examples, and if method 200 includes determining step 205, a supply time interval may be based on determining step 205, initiated in response to determining step 205, initiated simultaneously with initiating step 210, initiated immediately after initiating step 210, and / or initiated by initiating step 210. In other words, a supply time interval may include and / or be an initial supply time interval corresponding to a period during which supply of stored hydrogen gas to a particular fuel cell stack of a fuel cell system has occurred and / or is occurring.

[0018] Initiating the supply of stored hydrogen gas 210 may include initiating the supply of stored hydrogen gas from a low-pressure hydrogen storage tank to the fuel cell stack via a stored hydrogen supply conduit. The stored hydrogen stream includes stored hydrogen gas, and prior to initiating the supply 210, the stored hydrogen gas may be stored in a low-pressure hydrogen storage tank at a hydrogen storage pressure. Examples of stored hydrogen gas are disclosed herein for stored hydrogen gas 79. Examples of stored hydrogen streams are disclosed herein for stored hydrogen stream 112. Examples of low-pressure hydrogen storage tanks are disclosed herein for low-pressure hydrogen storage tank 78. Examples of hydrogen storage pressures include at least 75 kilopascal 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 160 kPag, at least 170 kPag, at least 180 kPag, at least 190 kPag, at least 200 kPag, at least 210 kPag, at least 220 kPag, at least 230 kPag, at least 240 kPag, at least 250 kPag, at least 260 kPag, at least 270 kPag, at least 280 kPag, at least 290 kPag, at least 300 kPag, at least 310 kPag, at least 320 kPag, at least 330 kPag, at least 340 kPag, at least 350 kPag, at least 360 kPag, at least 370 kPag, at least 380 kPag, at least 390 kPag, at least 400 kPag, at least 410 kPag, at least 420 kPag, at least 430 kPag, at least 440 kPag, at least 450 kPag, at least 460 kPag, at least 470 kPag, at least 480 kPag, at least 490 kPag, at least Including 50kPag, at least 155kPag, at least 160kPag, at least 165kPag, at least 170kPag, at least 175kPag, at least 180kPag, at least 185kPag, at least 190kPag, up to 250kPag, up to 240kPag, up to 230kPag, up to 220kPag, up to 210kPag, up to 200kPag, up to 195kPag, up to 190kPag, up to 185kPag, and / or up to 180kPag.

[0019] Initiating the supply 210 may be performed in any suitable manner. For example, initiating the supply 210 may include opening a stored hydrogen supply valve. An example of a stored hydrogen supply valve is disclosed herein for stored hydrogen supply valve 118. Opening the stored hydrogen supply valve may include allowing or facilitating flow of stored hydrogen gas from the low-pressure hydrogen storage tank to the fuel cell stack in and / or through a stored hydrogen supply conduit. An example of a stored hydrogen supply conduit is disclosed herein for stored hydrogen supply conduit 110.

[0020] In some examples, the HPFCS may include a stored hydrogen supply pressure regulator, examples of which are disclosed herein for stored hydrogen supply pressure regulator 120. In such examples, initiating supply 210 may include flowing stored hydrogen from a low-pressure hydrogen storage tank through the stored hydrogen supply pressure regulator to the fuel cell stack. In such configurations, the stored hydrogen supply pressure regulator may be configured to regulate the supply pressure of the stored hydrogen gas to the fuel cell stack.

[0021] Reducing the mass of stored hydrogen gas 215 may include reducing the mass of stored hydrogen gas in the low-pressure hydrogen storage tank. Reducing 215 may additionally or alternatively be referred to as reducing the amount and / or volume of stored hydrogen gas in the low-pressure hydrogen storage tank and / or bleeding or removing stored hydrogen gas from the low-pressure hydrogen storage tank. Reducing 215 may occur, at least in part, during the start-up timeframe of a fuel processing assembly of the HPFCS and / or may be at least partially a result of the commencement of delivery of step 210. Examples of fuel processing assemblies are disclosed herein for fuel processing assembly 13.

[0022] In other words, and as described in more detail herein, the fuel processing assembly may be configured to produce, or selectively produce, hydrogen gas, and method 200 may include performing step 210 of initiating the supply while the fuel processing assembly is not producing hydrogen gas. In such a configuration, the startup window may include and / or be the time window required for the fuel processing assembly to begin producing hydrogen gas and / or to produce at least a threshold flow rate of hydrogen gas. During the startup window, the flow rate of hydrogen gas from the low-pressure hydrogen storage tank into the stored hydrogen stream may exceed the flow rate of hydrogen gas from the fuel processing assembly to the low-pressure hydrogen storage tank, which may result in step 215 of reducing.

[0023] Producing hydrogen gas 220 may include generating hydrogen gas in and / or using a fuel processing assembly. In some embodiments, generating 220 may include at least one feed stream comprising a carbon-containing feedstock to fuel the fuel processing assembly. In some such embodiments, generating 220 may also include generating a product hydrogen stream comprising generated hydrogen gas using the fuel processing assembly and / or from the feed stream. In such embodiments, generating 220 may further include providing the product hydrogen stream to a low-pressure hydrogen storage tank as stored hydrogen gas. Examples of feed streams are disclosed herein with respect to feed stream 16. Examples of product hydrogen streams are disclosed herein with respect to product hydrogen stream 14. Examples of low-pressure hydrogen storage tanks are disclosed herein with respect to low-pressure hydrogen storage tank 78.

[0024] Refilling 225 the stored hydrogen gas may include refilling the stored hydrogen gas by flowing the product hydrogen gas stream into and / or into a low-pressure hydrogen storage tank. Additionally or alternatively, refilling 225 may include pressurizing the low-pressure hydrogen storage tank with the product hydrogen stream, for example, to the hydrogen storage pressure.

[0025] In some embodiments, refilling step 225 may occur after the start-up window of the fuel processing assembly, during generating step 220, and / or during the supply of stored hydrogen gas to the fuel cell stack initiated by initiating step 210. In other words, and after the start-up window, refilling step 225 will occur when the hydrogen gas flow rate from the low-pressure hydrogen storage tank and the hydrogen gas flow rate in the stored hydrogen stream is less than the hydrogen gas flow rate from the fuel processing assembly to the low-pressure hydrogen storage tank.

[0026] In some embodiments, the delivery time interval may occur during the step of refilling 225 and / or during the step of pressurizing the low-pressure hydrogen storage tank with the product hydrogen stream. In other words, the delivery time interval is a period of time during normal operation of the HPFCS, and may occur, for example, well after the step of starting 210 and / or while the fuel processing assembly is producing the product hydrogen stream.

[0027] Producing 230 may include generating the power output from the stored hydrogen gas in a fuel cell stack. An example power output is disclosed herein for power output 41. An example fuel cell stack is disclosed herein for fuel cell stack 40. Producing 230 may be accomplished in any suitable manner. For example, and as described in more detail herein, generating 230 may include reacting the stored hydrogen gas with an oxidant in a fuel cell stack to produce and / or generate the power output.

[0028] Monitoring 235 the hydrogen supply variable may include monitoring the hydrogen supply variable during a supply time interval following starting 210. The hydrogen supply variable may be an indicator of the flow of stored hydrogen supplied to the fuel cell stack. Detecting 240 a change in the hydrogen supply variable may include detecting a change in the hydrogen supply variable that exceeds a predetermined threshold.

[0029] In some embodiments, as previously described, the delivery time interval may begin immediately after and / or be initiated by initiating step 210. In some embodiments, as previously described, the delivery time interval may also occur during normal operation of the HPFCS, such as after initiating step 210, during delivery of the stored hydrogen stream to the fuel processing assembly, during delivery of the product hydrogen stream from the fuel processing assembly to the low-pressure hydrogen storage tank, and / or after a start-up timeframe of the fuel processing assembly.

[0030] The delivery time interval may have any suitable duration. For example, the delivery time interval may have a duration of 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, or up to 120 seconds, up to 110 seconds, up to 100 seconds, up to 90 seconds, up to 80 seconds, up to 70 seconds, up to 60 seconds, up to 55 seconds, up to 50 seconds, up to 45 seconds, up to 40 seconds, up to 35 seconds, and / or up to 30 seconds.

[0031] In some embodiments, the HPFCS may include a hydrogen supply variable detector. The hydrogen supply variable detector may be configured to detect a hydrogen supply variable and / or to detect a parameter indicative of a hydrogen supply variable. In these embodiments, the monitoring step 235 may be performed with, via, and / or utilizing the hydrogen supply variable detector. Examples of hydrogen supply variable detectors are disclosed herein for hydrogen supply variable detector 130.

[0032] In some embodiments, the hydrogen supply variable includes or is the hydrogen supply pressure of the stored hydrogen gas, which may be detected by a pressure detector. In these embodiments, monitoring 235 may include monitoring the hydrogen supply pressure, which may include monitoring at any suitable location within the HPFCS, including, for example, within 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.

[0033] In such an embodiment, detecting 240 may include calculating during the delivery time interval, i.e., during a change in hydrogen delivery pressure. The change in hydrogen delivery pressure may include or may be the difference between (1) the hydrogen delivery pressure before initiating step 210 or before the delivery time interval, and (2) the hydrogen delivery pressure after initiating step 210 or during the delivery time interval.

[0034] In some such examples, the threshold hydrogen supply variable change may include and / or may itself be a threshold hydrogen supply pressure change. Examples of threshold hydrogen supply pressure changes 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, and 140 kPag. In some embodiments, the threshold supply pressure change may include, or may itself be, a threshold pressure change factor of a nominal supply pressure change experienced during the supply time interval, during normal operation of the HPFCS, and / or when no hydrogen leaks are present within the HPFCS. Examples of threshold pressure change factors include 1.5x, 2x, 2.5x, 3x, 3.5x, 4x, 4.5x, 5x, 5.5x, 6x, 6.5x, and 7x, and further examples of nominal supply pressure changes 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, and up to 20 kPag.

[0035] In some embodiments, the hydrogen supply variable may include or be the hydrogen flow rate of the stored hydrogen stream, which may be detected by a hydrogen flow meter. In such embodiments, monitoring 235 may include monitoring the hydrogen flow rate, which may include monitoring at any suitable location within the HPFCS, including downstream of a low-pressure hydrogen storage tank and / or upstream of the fuel cell stack.

[0036] In such embodiments, the threshold hydrogen delivery variable change can include or be a threshold hydrogen flow rate magnitude. In some such embodiments, the threshold hydrogen flow rate magnitude can include and / or be a threshold flow rate multiplier of the nominal hydrogen flow rate magnitude, i.e., the value experienced during the delivery time interval, during normal operation of the HPFCS, and / or when no hydrogen leaks are present in the HPFCS. Examples of threshold flow rate multipliers include 1.5x, 2x, 2.5x, 3x, 3.5x, 4x, 4.5x, 5x, 5.5x, 6x, 6.5x, and 7x.

[0037] In some embodiments, the fuel cell stack may have a maximum design wattage. In such embodiments, the magnitude of the threshold hydrogen flow rate may be a wattage multiple of the maximum design wattage. Examples of wattage multiples 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, and 90 SLPM / kW.

[0038] Examples of the monitoring step 235 and the detecting step 240 are shown in FIGS. 3 and 4. FIG. 3 is a graph that schematically illustrates the magnitude of a hydrogen supply variable, such as hydrogen supply pressure, as a function of time, which may be generated by a hydrogen producing and consuming assembly or may be generated in a manner that may be utilized during start-up of a fuel processing assembly in accordance with the present disclosure. In the example of FIG. 3, the magnitude of the hydrogen supply variable increases from time t0 to time t1. This increase over time may be due to start-up of the fuel processing assembly. In other words, and during start-up, the fuel processing assembly may produce a gradually increasing flow rate, volume, or mass of a product hydrogen stream, which may accumulate in a low-pressure hydrogen storage tank, resulting in the temporal change illustrated in FIG. 3. Thereafter, at time t1, when the magnitude of the hydrogen supply variable is v1, starting step 210 may be performed to begin supplying stored hydrogen gas to the first fuel cell stack. This may cause the mass of stored hydrogen gas in the low-pressure hydrogen storage tank to decrease, as described herein with respect to decreasing step 215, resulting in a decrease in the magnitude of the hydrogen supply variable, which may reach a value v2 at time t2. This decrease in the magnitude of the hydrogen supply variable (e.g., v1 - v2) may be less than the threshold hydrogen supply variable change. Thus, detecting step 240 may not detect that the change in the hydrogen supply variable exceeds the threshold hydrogen supply variable change, and / or method 200 may not proceed to the corresponding step 250.

[0039] From time t2 to time t3, the magnitude of the hydrogen supply variable may again increase and reach a magnitude of v3. Subsequently, at time t3, starting step 210 may be performed to begin supplying stored hydrogen gas to the second fuel cell stack. This may also decrease the mass of stored hydrogen gas in the low-pressure hydrogen storage tank, as described herein for the decreasing step of step 215, thereby decreasing the magnitude of the hydrogen supply variable, reaching a value v4 at time t4. This decrease in the magnitude of the hydrogen supply variable (e.g., v3 - v4) may be greater than the threshold hydrogen supply variable change. Thus, detecting step 240 includes detecting that the change in the hydrogen supply variable exceeds the threshold hydrogen supply variable change, and method 200 proceeds to corresponding step 250. In other words, FIG. 3 illustrates an example in which the first fuel cell stack does not have a hydrogen gas leak, but the second fuel cell stack has a hydrogen gas leak, and method 200 may respond to the hydrogen gas leak in the second fuel cell stack as disclosed herein for corresponding step 250.

[0040] 4 is a schematic illustration of a hydrogen supply variable, such as hydrogen supply pressure, as a function of time that may be produced by a hydrogen producing and consuming assembly and / or utilized during steady-state operation of a fuel processing assembly in a method according to the present disclosure. In the example of FIG. 4, the magnitude of the hydrogen supply variable is stable near a value v1 between time t0 and time t1. Then, at time t1, initiating step 210 is performed to begin supplying stored hydrogen gas to the first fuel cell stack. This may decrease the mass of stored hydrogen gas in the low-pressure hydrogen storage tank, as described herein with respect to decreasing step 215, thereby decreasing the magnitude of the hydrogen supply variable and reaching a value v2. This decrease in the magnitude of the hydrogen supply variable (e.g., v1 - v2) may be less than the threshold hydrogen supply variable change. Thus, detecting step 240 may not detect that the change in the hydrogen supply variable exceeds the threshold hydrogen supply variable change, or method 200 may not proceed to the corresponding step 250.

[0041] At time t2, the fuel processing assembly may adapt to the change in hydrogen demand, and the magnitude of the hydrogen supply variable may return to nominally v1. From time t2 to time t3, the magnitude of the hydrogen supply variable may again stabilize near v1. Subsequently, at time t3, initiating step 210 is performed to begin supplying stored hydrogen gas to the second fuel cell stack. This may decrease the mass of stored hydrogen gas in the low-pressure hydrogen storage tank, as described herein with respect to decreasing step 215, and the magnitude of the hydrogen supply variable may decrease to reach a value v3. This decrease in the hydrogen supply variable magnitude (e.g., v2 - v3) may be greater than the threshold hydrogen supply variable change during the corresponding supply time interval (e.g., t4 - t3). That is, detecting step 240 includes detecting that the change in the hydrogen supply variable exceeds the threshold hydrogen supply variable change, and method 200 proceeds to corresponding step 250. In other words, FIG. 4 illustrates an example in which the first fuel cell stack does not have a hydrogen gas leak, but the second fuel cell stack has a hydrogen gas leak, and method 200 may respond to the hydrogen gas leak in the second fuel cell stack as disclosed in corresponding step 250 herein.

[0042] Purging the fuel cell stack 245 may include purging the fuel cell stack with, through, and / or utilizing the stored hydrogen flow. This may include purging the fuel cell stack during a purge time interval. Purging 245, if performed, may be utilized to purge unwanted compounds, substances, and / or contaminants from the fuel cell stack. For example, purging 245 may be utilized to remove excess water from the fuel cell stack.

[0043] When purging step 245 is performed, it may cause a change in the hydrogen supply variable to exceed a threshold hydrogen supply variable change. However, this may be due to purging step 245 and / or may not be due to a hydrogen leak within the HPFCS. Thus, if detecting step 240 detects that a change in the hydrogen supply variable exceeds a threshold hydrogen supply variable change while the HPFCS is performing purging step 245, method 200 may not perform corresponding step 250. In other words, the supply time interval may exclude the purge time interval and / or may not overlap with the purge time interval. In yet other words, method 200 may omit corresponding step 250 during the purge time interval. By "omit" it is meant that the method includes not performing the detecting step and / or not performing the corresponding step during the purge time interval. In some such embodiments, the omitting step includes omitting during an omitting time period, which may be a threshold omitting time multiple of the purge time interval. Examples of threshold omission time multipliers include at least 1.25x, at least 1.5x, at least 1.75x, at least 2x, at least 2.5x, at least 3x, at least 4x, at least 5x, up to 10x, up to 9x, up to 8x, up to 7x, up to 6x, up to 5x, up to 4x, up to 3x, and up to 2x.

[0044] Corresponding step 250 may include performing at least one action based on, in response to, and / or initiated by the detecting step 240. In some embodiments, corresponding step 250 may include determining that a hydrogen gas leak exists within the HPFCS, downstream of the low-pressure hydrogen storage tank, and / or within the fuel cell stack.

[0045] In some embodiments, initiating step 210 may include initiating a supply of the stored hydrogen stream to a given fuel cell stack of a plurality of fuel cell stacks of the HPFCS. In some such embodiments, corresponding step 250 may include terminating the supply of the stored hydrogen stream to the given fuel cell stack. In some such embodiments, method 200 may further include maintaining the supply of the stored hydrogen stream to other fuel cell stacks of the plurality of fuel cell stacks after the supply termination and / or repeating initiating step 210 to supply the stored hydrogen stream to other fuel cell stacks after the supply termination. In other words, and if the HPFCS includes multiple fuel cell stacks, method 200 may be applied independently to one or each fuel cell stack of the plurality of fuel cell stacks.

[0046] In a more specific example, initiating step 210 may include initiating a supply of stored hydrogen gas to a first fuel cell stack of the plurality of fuel cell stacks, followed by initiating a supply of stored hydrogen gas to a second fuel cell stack of the plurality of fuel cell stacks. In this example, detecting step 240 may include detecting a change in a hydrogen supply variable after initiating a supply of stored hydrogen gas to the first fuel cell stack and / or after initiating a supply of stored hydrogen gas to the second fuel cell stack, and corresponding step 250 may include performing at least one action only on and / or only on the fuel cell stack that causes and / or generates the change in the hydrogen supply variable after receiving the stored hydrogen gas. For example, a change in the hydrogen supply variable may be detected after performing initiating step 210 for the second fuel cell stack, but not after performing initiating step 210 for the first fuel cell stack. In this example, corresponding step 250 may include performing at least one action on the second fuel cell stack, but the at least one action may not be performed on the first fuel cell stack.

[0047] In some embodiments, corresponding step 250 may include initiating a system diagnostic test on the entire HPFCS, at least one fuel cell stack of the HPFCS, and / or multiple fuel cell stacks of the HPFCS. In some embodiments, corresponding step 250 may include notifying an operator of the HPFCS of the presence of a hydrogen leak or a potential hydrogen leak within the HPFCS, at least one fuel cell stack of the HPFCS, and / or one or more specific fuel cell stacks of the HPFCS. In some embodiments, corresponding step 250 may include shutting down operation of the HPFCS and / or at least one component of the HPFCS. This may include shutting down operation of the entire HPFCS, shutting down operation of at least one fuel cell stack of the HPFCS, shutting down operation of all fuel cell stacks of the HPFCS, shutting down hydrogen production by the fuel processing assembly, and / or shutting down the flow of stored hydrogen to the fuel cell stacks.

[0048] Method 200 and / or controller 100 may be utilized with a wide variety of hydrogen-producing fuel processing systems 10 and / or HPFCSs 12. Although an example hydrogen-producing fuel processing system 10 and HPFCS 12 is generally shown and described in the following description and with reference to FIG. 1, method 200 is not limited to being performed only in the hydrogen-producing fuel cell system and HPFCS generally shown and / or described in FIG.

[0049] Referring to FIG. 1 , one or more feedstreams 16 may be provided to hydrogen-producing region 19 of hydrogen-producing fuel processing system 10 via feedstream supply system 22. In FIG. 1 , feedstream 16 is shown provided to hydrogen-producing region 19 by feedstream supply system 22, which schematically represents any suitable mechanism, device, or combination thereof for selectively providing feedstream 16 to hydrogen-producing region 19. For example, feedstream supply system 22 may include one or more pumps adapted to provide the components of feedstream 16 from one or more sources. Additionally or alternatively, feedstream supply system 22 may include a valve assembly adapted to regulate the flow of the components of feedstream 16 from a pressurized source. The source may be located external to fuel processing system 10 or may be located within or adjacent to fuel processing system 10. When feedstream 16 is provided to hydrogen-producing region 19 as multiple streams, the streams may be provided by the same feedstream supply system 22 or by separate feedstream supply systems 22. Examples of raw material supply systems 22 are disclosed in U.S. Patent Nos. 7,601,302, 6,375,906, 7,135,048, and 6,890,672, and U.S. Patent Publication Nos. 2009 / 0155642 and 2019 / 0273275, the complete disclosures of which are incorporated herein by reference.

[0050] The one or more feed streams 16 include at least a carbon-containing feedstock 18 and may further include water 17 if the hydrogen-producing region is configured to produce a mixed gas stream 20 from the carbon-containing feedstock 18 and water 17 via a steam reforming reaction. If the hydrogen-producing region is configured to produce a mixed gas stream 20 via a hydrogen production reaction such as a partial oxidation reaction, the one or more feed streams may also include oxygen gas 15 as an oxidant. If the hydrogen-producing region is configured to produce a mixed gas stream 20 via an autothermal reaction, the one or more feed streams may include a carbon-containing feedstock 16 and an oxidant (e.g., oxygen gas 15). Within the scope of this disclosure, the one or more feed streams 16 may also be referred to based on their components and may include, for example, a carbon-containing feedstock stream 18, a water stream 17, an oxidant or oxygen gas stream 15, and / or a mixed stream comprising a carbon-containing feedstock and water.

[0051] With this in mind, feedstock supply system 22 may be configured to supply one or more feedstock streams to hydrogen-producing region 19 and may utilize, for example, one or more pumps, compressors, or pressurized sources for supplying the carbon-containing feedstock, water, and / or other feedstock components.

[0052] Although a single feed stream 16 is shown in Figure 1 with a solid line, it is contemplated within the scope of this disclosure that multiple feed streams 16 may be used and that the streams may contain the same or different feedstocks. When feed stream 16 contains two or more components, such as carbon-containing feedstock 18 and water 17, the components may be provided in the same feed stream or as different feed streams. For example, when fuel processing system 10 is adapted to produce hydrogen gas from a carbon-containing feedstock and water, and optionally, the components are immiscible with each other (at least until both components are vaporized or otherwise brought to a gaseous state), the components are typically provided as separate streams, as shown in Figure 1 by reference numerals 17 and 18.

[0053] If carbon-containing feedstock 18 is miscible with water, it may be provided along with the water component of feedstream 16, with reference numerals 17 and 18 referring to the same feedstream 16, as shown in Figure 1. For example, if hydrogen-producing region 19 receives a feedstream containing water and a water-soluble alcohol, such as methanol, these components may be premixed and provided as a single stream. Alternatively, if hydrogen-producing region 19 receives a gaseous feedstream, the gaseous feedstream may be provided along with one or more liquid feedstreams, or may be provided as a separate feedstream, as shown in Figure 1.

[0054] As shown in FIG. 1 , fuel processing assembly 13 includes hydrogen-producing region 19. Hydrogen-producing region 19 can be configured to receive one or more feed streams 16 and generate mixed gas stream 20 from feed stream 16 via an appropriate hydrogen-producing region. Mixed gas stream 20 contains hydrogen gas as a major component and may also contain other gases, such as carbon monoxide, carbon dioxide, methane, unreacted carbon-containing feedstock 18, and water vapor. Here, "major component" means that hydrogen gas is present in the mixed gas stream in a higher concentration or amount than any other gas. For example, mixed gas stream 20 can contain at least 50% by weight, at least 60% by weight, and / or at least 70% by weight of hydrogen gas.

[0055] Hydrogen-producing region 19 may utilize any suitable process or mechanism to produce hydrogen gas from feedstream 16 and may be located inside or outside heated containment structure 70. Examples of suitable mechanisms by which hydrogen-producing region 19 may produce hydrogen gas from feedstream 16 include steam reforming, autothermal reforming, and partial oxidation reforming.

[0056] In some embodiments, hydrogen-producing region 19 includes one or more reforming catalysts 23 configured to produce hydrogen gas from feed stream 16, including carbon-containing feed stream 18 and water stream 17. In such examples, hydrogen-producing region 19 may be referred to as and / or may be a reformer 19 that includes reformer 19. Examples of suitable carbon-containing feedstocks 18 include at least one hydrocarbon or alcohol. Examples of suitable hydrocarbons include methane, propane, natural gas, diesel, kerosene, gasoline, etc. Examples of suitable alcohols include methanol, ethanol, various propanols, and polyols such as ethylene glycol and propylene glycol.

[0057] Other suitable mechanisms for producing hydrogen gas from feed stream 16 include ammonia decomposition, water electrolysis, and the water-gas shift reaction. Representative, but non-limiting, examples of suitable hydrogen-producing regions and / or mechanisms are disclosed in U.S. Patent Nos. 6,537,352, 6,221,117, 5,997,594, 5,861,137, and U.S. Patent Publication No. 2003 / 0223926, the complete disclosures of which are incorporated herein by reference.

[0058] Steam reforming is one example of a hydrogen production mechanism that may be used in hydrogen-producing region 19, where feed stream 16 includes water 17 and carbon-containing feedstock 18. In a steam reforming process, hydrogen-producing region 19 includes a suitable steam reforming catalyst 23, which is shown by the dashed line in FIG. 1 . In this example, the hydrogen-producing fuel processing system may be referred to as a "steam reformer," and hydrogen-producing region 19 may be referred to as a "reforming region." Also, mixed gas stream 20 may be referred to as a "reformed gas stream." As a more specific example, hydrogen-producing region 19 may utilize a methanol steam reforming reaction and be referred to as a "methanol reforming region." In this case, hydrogen-producing region 19 includes a methanol steam reforming catalyst 23 configured to produce mixed gas stream 20 primarily composed of hydrogen gas from methanol and water.

[0059] If hydrogen-producing region 19 includes a reforming catalyst 23, the reforming catalyst 23 may be non-pyrophoric, so that it can be used without burning or being deactivated when exposed to air or oxygen. Examples of suitable steam reforming catalysts are disclosed in U.S. Patent No. 7,128,769, the complete disclosure of which is incorporated herein by reference. Further, additional examples of non-pyrophoric reforming catalysts that can be used in hydrogen-producing region 19 include reforming catalysts sold under the trade name KMA by Clariant, and reforming catalysts comprising zinc oxide supported on calcium aluminate.

[0060] Steam reformers typically operate at temperatures ranging from 200°C to 900°C and pressures ranging from 50 pounds per square inch (psi) to 300 psi, although operation at temperatures and pressures outside these ranges is within the scope of this disclosure. When the carbon-containing feedstock 18 is methanol, the hydrogen-producing steam reforming reaction, or hydrogen-producing region 19, typically operates at a hydrogen-producing temperature range of about 200°C to 500°C. Specific ranges within this range include 275°C to 375°C, 300°C to 400°C, 350°C to 450°C, 375°C to 425°C, and 375°C to 400°C.

[0061] When the carbon-containing feedstock is a hydrocarbon, ethanol, or similar alcohol, a hydrogen production temperature range of about 400°C to 900°C is typically used in the hydrogen-producing steam reforming reaction, or hydrogen production region 19. Specific ranges include 750°C to 850°C, 725°C to 825°C, 650°C to 750°C, 700°C to 800°C, 700°C to 900°C, 500°C to 800°C, 400°C to 600°C, and 600°C to 800°C.

[0062] Within the scope of the present disclosure, hydrogen-producing region 19 may include two or more zones or sections, each operating at the same or different temperatures. For example, when carbon-containing feedstock 18 includes liquid hydrocarbons, in some embodiments it may be desirable to include two different hydrogen-producing sections, with one operating at a lower temperature to provide a pre-reforming region. In such embodiments, fuel processing system 10 may alternatively be described as including two or more hydrogen-producing regions 19.

[0063] Hydrogen-producing fuel processing system 10 may include mixed gas filter 30 located downstream of hydrogen-producing region 19 and upstream of separation assembly 80. In this configuration, mixed gas stream 20 passes through mixed gas filter 30 as it is transferred from hydrogen-producing region 19 to separation assembly 80. Mixed gas filter 30 is configured to filter mixed gas stream 20 to remove or reduce certain impurities present in the gas stream, thereby removing components that may adversely affect the operation of separation assembly 80. For example, mixed gas filter 30 may be configured to remove one or more of particles, sols, soot, and ash that may be present in mixed gas stream 20 as it leaves hydrogen-producing region 19.

[0064] The material processing assembly 13 may also include a separation assembly 80. The separation assembly 80 may be configured to receive the mixed gas stream 20 and produce therefrom a by-product stream 68 and a product hydrogen stream 14. For example, the separation assembly 80 may be configured to separate the mixed gas stream 20 into a product hydrogen stream 14 and a by-product stream 68. The product hydrogen stream 14 is a gas stream having a higher concentration of hydrogen gas and a reduced total concentration of other gases than the mixed gas stream 20. In other words, the by-product stream 68 may contain a majority of the other gas components. Examples of the separation assembly 80 include a membrane separation assembly 82 including a hydrogen-selective membrane and a pressure swing adsorption separation assembly 84. Examples of suitable separation assemblies 80 and their components are disclosed in U.S. Pat. Nos. 7,972,420, 10,476,093, 7,733,311, 7,399,342, and 7,837,765, the complete disclosures of which are incorporated herein by reference.

[0065] As used herein, "at least substantially pure hydrogen gas" refers to hydrogen having a purity of 90% or greater, 95% or greater, 99% or greater, 99.5% or greater, and / or 99.9% or greater. In contrast, by-product stream 68 comprises a gas stream having a higher overall concentration of other gas components contained in the mixed gas stream. While by-product stream 68 may contain hydrogen gas, the concentration of hydrogen gas is lower than in the mixed gas stream.

[0066] 1 , the portion of mixed gas stream 20 that does not constitute product hydrogen stream 14 includes impurities (other gas components) contained in mixed gas stream 20 and some hydrogen gas, which may be discharged from separation assembly 80 as by-product stream 68. By-product stream 68 may be treated in any suitable manner, such as being discharged to an environment external to hydrogen-producing fuel processing system 10, being chemically treated and / or reacted prior to being discharged, being provided as a fuel stream for combustor assembly 92, being used as a reaction stream in another chemical process, or being stored for later use.

[0067] Fuel processing system 10 may also include a heating assembly 91, which may be configured to heat at least a portion of fuel processing system 10, such as hydrogen-producing region 19 and / or separation assembly 80. For example, heating assembly 91 may be configured to heat the appropriate portion of the fuel processing system to an appropriate operating temperature or range of temperatures for the production and / or purification of hydrogen gas. As an example, heating assembly 91 may include an evaporation region or evaporator 94, which may vaporize the liquid portion of feed stream 16. As a result, feed stream 16 is in a vaporized state upon or before entering hydrogen-producing region 19.

[0068] As another example, heating assembly 91 can be configured to heat hydrogen-producing region 19 to an appropriate hydrogen-producing temperature, examples of which are described herein. In some embodiments, heating assembly 91 can also or alternatively be configured to maintain a portion of the fuel processing system at an operating temperature, or a "preheat temperature," or "buffer temperature," thereby maintaining HPFCS 12 in a standby or idle state during periods when the hydrogen-producing region is not producing hydrogen gas or is not producing more than a nominal amount of hydrogen gas. Examples of sources of electrical power for powering electrical heating assembly 93 include energy storage device 50, fuel cell stack 40, and / or primary power source 52.

[0069] The preheat or buffer temperature is lower than the operating temperature (i.e., hydrogen production temperature) of hydrogen-producing region 19, but higher than ambient temperature. For example, the preheat or buffer temperature can be at least 100°C, at least 150°C, and / or at least 200°C. Alternatively, the preheat or buffer 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 lower than the hydrogen production temperature of hydrogen-producing region 19. Additional examples of suitable operating temperature (i.e., hydrogen production and / or hydrogen purification temperatures), preheat temperature, and buffer temperature ranges, and corresponding hydrogen-producing fuel cell systems and components thereof, are disclosed in U.S. Pat. No. 7,659,019, the complete disclosure of which is incorporated herein by reference.

[0070] The heating assembly 91 may utilize any suitable structure to provide heat to the internal compartments of the heated containment structure 70, the components contained therein, and / or the various components of the fuel processing system 10. This may include a combustor assembly 92 and / or an electric heating assembly 93. If the heating assembly 91 includes a combustor assembly 92, the combustor assembly may comprise one or more burners, and fuel for the combustor assembly 92 may be provided from any suitable source. Examples of applicable fuels for the combustor assembly 92 include the by-product stream 68 (described in detail herein), the product hydrogen stream 14, the mixed gas stream 20, the feedstock stream 16, the carbon-containing feedstock 18, or other suitable combustible fuel source, as described in more detail herein.

[0071] 1 , the fuel processing system 10 may include a by-product flow conduit 62. The by-product flow conduit 62 may be configured to direct the by-product stream 68 from the separation assembly 80 to another portion of the fuel processing system 10. For example, the by-product stream 68 may be provided to a combustor assembly 92 or may be discharged externally from the fuel processing system 10.

[0072] As previously mentioned, hydrogen-producing fuel processing system 10 may include heated containment structure 70, which defines an interior compartment that may house separation assembly 80, heating assembly 91, hydrogen-producing region 19, and / or a portion of feedstock supply system 22. It may also include appropriate components, such as valves, conduits, and / or piping associated with the above components. It is also within the scope of the present disclosure that heated containment structure 70 may include or house additional system components.

[0073] Each component contained within the heated containment structure 70 may be maintained at approximately the same temperature, or may be maintained at different temperatures. This temperature management may be achieved by any suitable method, including using a separate heating assembly 91 for each component within the heated containment structure 70, arranging each component according to its distance from the heating assembly, utilizing internal structures (e.g., baffles, supports, dividers, etc.) to direct and control heat flow from the heating assembly, and / or using multiple heated containment structures, each with its own internal compartment maintained at a different temperature or temperature range. Also within the scope of the present disclosure, the heated containment structure 70 may include insulation to reduce the rate of heat transfer between the internal compartments of the heated containment structure 70 and the external environment and / or to control heat flow between components within the internal compartments.

[0074] In some embodiments, the hydrogen-producing fuel processing system 10 may include a purification region 32 configured to receive the product hydrogen stream 14 from the separation assembly 80 and further purify, remove, reduce, and / or chemically react certain impurities contained within the gas stream. Examples of equipment that may be used within the purification region 32 include an aqueous shift reactor that converts carbon monoxide to carbon dioxide, a methanation catalyst that converts carbon monoxide and hydrogen to methane and water, and other carbon monoxide to carbon dioxide conversion devices. For example, if the product hydrogen stream 14 is to be used in a fuel cell system 42 that includes a proton exchange membrane (PEM) or other device that may be damaged by the presence of carbon monoxide or carbon dioxide above certain concentrations, the purification region 32 may include at least one methanation catalyst layer.

[0075] As shown in FIG. 1 and described above, the hydrogen-producing fuel processing system 10 includes a low-pressure hydrogen storage tank 78 configured to receive at least a portion of the product hydrogen stream 14 from the fuel processing assembly 13, the separation assembly 80, and / or the purification region 32 and store a certain amount as stored hydrogen gas 79. As shown, the low-pressure hydrogen storage tank 78 may be configured to receive hydrogen gas from the product hydrogen stream 14 before the product hydrogen stream 14 is delivered to at least one fuel cell stack 40 of the fuel cell system 42. The low-pressure hydrogen storage tank 78 may improve the stability of the pressure of the product hydrogen stream 14 delivered to the fuel cell stack 40 and may reduce the likelihood of pressure fluctuations in the product hydrogen stream 14 delivered to the fuel cell stack 40. Additionally or alternatively, the low-pressure hydrogen storage tank 78 may function as a buffer tank, or may be referred to as a buffer tank, which may be configured to absorb fluctuations in demand for stored hydrogen gas 79 by the fuel cells 44 and / or adjust for fluctuations in production of hydrogen product gas 25 by the fuel processing assembly 13.

[0076] As previously mentioned, HPFCS 12 may include stored hydrogen supply valve 118. Stored hydrogen supply valve 118 may be configured to selectively regulate the flow of stored hydrogen in stored hydrogen supply conduit 110. Examples of stored hydrogen supply valve 118 include manually operated valves, quarter-turn valves, ball valves, metering valves, electrically operated valves, solenoid valves, and pneumatically operated valves.

[0077] 1 , HPFCS 12 may include stored hydrogen supply pressure regulator 120. Stored hydrogen supply pressure regulator 120 may be configured to selectively adjust the hydrogen supply pressure of stored hydrogen stream 112 supplied to fuel cell stack 40. With this in mind, and as shown, when hydrogen supply variable detector 130 includes pressure detector 132, the pressure detector may be located upstream of stored hydrogen supply pressure regulator 120. More specifically, the pressure detector may be configured to detect the hydrogen supply pressure within low-pressure hydrogen storage tank 78, downstream of the low-pressure hydrogen storage tank, upstream of stored hydrogen supply valve 118, and / or upstream of stored hydrogen supply pressure regulator 120.

[0078] As previously mentioned, the product hydrogen stream 14 produced by the fuel processing system 10 may be provided to one or more fuel cell stacks 40 of a fuel cell system 42. A fuel cell stack is a device that utilizes a proton source, such as hydrogen gas, and an oxidant, such as oxygen gas, to generate an electrical potential. Thus, the fuel cell stack 40 may be configured to receive at least a portion of the product hydrogen stream 14 and a stream containing oxygen gas (typically provided as an air stream) and generate an electrical current therefrom. This is shown schematically in FIG. 1, where the oxygen-containing air stream is designated 49, the fuel cell stack is designated 40, and the electrical current or power output produced by the fuel cell stack is designated 41.

[0079] The fuel cell stack 40 includes at least one, and typically multiple, fuel cells 44 adapted to generate electrical current using a portion of the supplied oxidant and product hydrogen stream 14. The fuel cells are typically arranged between common end plates 48, which include conduits for fluid supply and exhaust, 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 (BPI) membrane fuel cells, alkaline fuel cells, and phosphoric acid fuel cells, although other fuel cells are within the scope of this disclosure.

[0080] The power output 41 from the fuel cell system 42 may be stored using an energy storage device 50 and / or for later use, such as supplying a power load by an energy consumption device 46. The energy storage device 50 may include any suitable structure for storing 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 batteries, capacitors, ultracapacitors, supercapacitors, and flywheels. Additional examples of HPFCSs 12 including energy storage devices 50 and / or methods of operating these systems are disclosed in U.S. Patent No. 11,316,180, the disclosure of which is incorporated herein by reference. The HPFCS 12 may include suitable power management devices, such as DC / DC converters, rectifiers, etc., to rectify, boost, buck, or otherwise manage and convert the power output 41.

[0081] Examples of energy consuming devices 46 include tools, lights or lighting assemblies, home appliances (electrical appliances for home or other use), homes or other living spaces, offices or other commercial facilities, computers, signaling or communication devices, communications equipment, medical equipment, etc. Similarly, the fuel cell stack 40 may be used to meet the power requirements of the fuel cell system 42, which may be referred to as the balance-of-plant power requirements of the fuel cell system. Energy consuming devices 46 are shown schematically in FIG. 1 and represent one or more devices or groups of devices adapted to draw current or apply a power load from the fuel cell system 42.

[0082] Within the scope of the present disclosure, the energy consuming device 46 may optionally be electrically connected to a primary power source 52, which may also provide the hydrogen producing fuel cell system with a primary power source power output 54. When the energy consuming device 46 is electrically connected to the primary power source, the HPFCS 12 may operate as an auxiliary power source and / or backup power system 56 to supply a load applied by the energy consuming device 46 when the primary power source 52 is unable to meet at least a portion of the load.

[0083] The primary power source 52 may include any suitable structure adapted to provide a primary power source power output 54 to satisfy a load applied by the energy consuming device 46. Examples of primary power sources include a power grid, a hydroelectric source, a solar power source, a wind power source, another fuel cell system, and an energy storage device or system. Some primary power sources may include an energy storage device or system or a combination with other power sources, such as a hydroelectric source, a solar power source, and / or a wind power source.

[0084] An example of a situation in which the primary power source is unable to meet at least a portion of the applied load is when the primary power source is unable to meet the entire applied load, such as when the magnitude of the applied load exceeds the amount of power output available from the primary power source. In such a situation, the HPFCS 12 supplements the power output of the primary power source and may also be referred to as an auxiliary power source 60.

[0085] Another example of a situation in which the primary power source is unable to meet at least a portion of the applied load is when there is no or very little power output from the primary power source and the applied load cannot be met at all. In this situation, the HPFCS 12 provides backup power to the energy consuming device 46 and may also be referred to as a backup power source 58.

[0086] Yet another example of a primary power source being unable to meet at least a portion of the applied load is when the stability of the power output from the primary power source falls below a predetermined threshold stability level. Under such circumstances, the HPFCS 12 provides some or all of the power to the energy consuming device 46, and the HPFCS 12 may also be referred to as an auxiliary power source 60 and / or a backup power source 58.

[0087] As previously mentioned, the controller 100 may control at least a portion of the operation of the hydrogen-producing fuel processing system 10 and / or the HPFCS 12 based on the status of various components of the hydrogen-producing fuel processing system 10 and / or calculations within the controller. Examples of the status signal 102 include signals received by the controller 100 indicating the operating status of each component of the hydrogen-producing fuel processing system 10, as well as signals indicating the temperature, pressure, concentration, flow rate, and / or humidity of each component or a stream therein. As a more specific example, the controller 100 may receive a status signal 102 indicating a hydrogen supply variable, hydrogen flow rate, and / or hydrogen supply pressure. As a further example, the controller 100 may receive a status signal 102 indicating the moisture level of the fuel cell stack, the electrical impedance of the fuel cell stack, the current flow of the fuel cell stack, the pressure within the separation assembly 80, the temperature of each component within the heated containment structure 70, and / or the ability of the primary power source 52 to meet the power load applied by the energy consuming device 46.

[0088] In the context of method 200, controller 100 may be programmed or configured to supply stored hydrogen stream 112, including stored hydrogen gas 79, to fuel cell stack 40, for example, by opening stored hydrogen supply valve 118, which selectively allows or restricts the flow of stored hydrogen stream 112 through stored hydrogen supply conduit 110. As another example, controller 100 may cause fuel cell stack 40 to generate electrical power output 41 and / or monitor the production of electrical power output by the fuel cell stack.

[0089] As yet another example, the controller 100 may monitor a hydrogen supply variable indicative of the flow of stored hydrogen flow 112 to the fuel cell stack 40. The hydrogen supply variable may be monitored using one or more hydrogen supply variable detectors 130, and may occur within a supply time interval after the supply of stored hydrogen flow to the fuel cell stack begins. In other words, the hydrogen supply variable detector may be configured to detect a parameter indicative of the hydrogen supply variable.

[0090] As a more specific example, hydrogen supply variable detector 130 may include pressure detector 132. Pressure detector 132 may be used to detect the hydrogen supply pressure of stored hydrogen gas 79, such as in and / or near low-pressure hydrogen storage tank 78. When the supply of stored hydrogen gas to the fuel cell stack begins, a certain drop in hydrogen supply pressure is expected. However, controller 100 may be programmed to respond only if, or only if, the drop in hydrogen supply pressure exceeds the expected amount of change. Such a pressure drop may be caused, for example, by a hydrogen gas leak within HPFCS 12 and / or fuel cell stack 40.

[0091] As a more specific example, the hydrogen supply variable detector 130 may include a hydrogen flow meter 134. The hydrogen flow meter 134 may be used to detect the hydrogen supply flow rate of stored hydrogen gas 79 through the stored hydrogen supply conduit 110, such as downstream of the low-pressure hydrogen storage tank 78 or upstream of the fuel cell stack 40. When the supply of stored hydrogen gas to the fuel cell stack is initiated, a constant hydrogen supply flow rate is expected. However, the controller 100 may be programmed to respond only if, and only if, the hydrogen supply flow rate exceeds the expected rate. Such an increase in hydrogen supply flow rate may be caused, for example, by a hydrogen leak within the HPFCS and / or the fuel cell stack.

[0092] Additional examples of portions of the hydrogen-producing fuel processing system 10 that may be monitored and / or controlled (i.e., adjusted, regulated, modified, maintained, etc.) by the controller 100 include any valves, fluid treatment devices, pumps, compressors, flow regulators, temperature regulators, power regulators, pressure regulators, etc. As more specific examples, controller 100 may control the following: regulating the flow rate of feedstock stream 16 by controlling the operation of various pumps, compressors, valves, and mass flow controllers included in feedstock supply system 22; regulating the temperature of heated containment structure 70 and various components of fuel processing system 10 by controlling the power supply to electric heating assembly 93 or controlling the flow rate of combustible fuel and / or oxidant to combustor assembly 92; controlling the temperature of hydrogen-producing region 19 and separation assembly 80; controlling the consumption of power output 41 by energy consuming device 46; controlling the concentration of one or more substances included in hydrogen-producing fuel processing system 10; controlling the flow rates of mixed gas stream 20, product hydrogen stream 14, oxidant-containing stream 49, and by-product stream 68; controlling the pressure within separation assembly 80; and controlling the operation and / or operating state of various components of hydrogen-producing fuel processing system 10, including feedstock supply system 22, hydrogen-producing region 19, separation assembly 80, and fuel cell stack 40.

[0093] Controller 100 may include any suitable type and number of devices or mechanisms for performing and providing the desired monitoring and / or control of one or more components of hydrogen-producing fuel processing system 10 and / or HPFCS 12. By way of example, a suitable controller may take the form of analog or digital circuitry and may be used in combination with suitable electronic instructions stored on magnetic media or programmable memory, such as read only memory (ROM), programmable read only memory (PROM), or erasable programmable read only memory (EPROM). The controller may be integrated into one or more systems or assemblies of hydrogen-producing fuel processing system 10 and / or HPFCS 12, or may be configured as a separate, independent computing device. The controller may be adapted or programmed or designed to control the operation of hydrogen-producing fuel processing system 10 and / or HPFCS 12 in multiple operating modes of the systems, including controlling the operation of various components of the systems.

[0094] By way of example, controller 100 may include one or more electronic controllers, dedicated controllers, application-specific controllers, personal computers, application-specific computers, display devices, logic devices, memory devices, and / or memory devices, including computer-readable storage media. Computer-readable storage media, if present, may also be referred to herein as “non-transitory computer-readable storage media 106.” This non-transitory computer-readable storage media may include, define, hold, and / or store computer-executable instructions, programs, and / or code. These computer-executable instructions may direct hydrogen-producing fuel processing system 10 and / or HPFCS 12 to perform any suitable portion or subset of method 200.

[0095] Examples of such non-transitory computer-readable storage media include CD-ROMs, disks, hard drives, flash memory, etc. As used herein, storage devices or memory devices having computer-executable instructions, and computer-implemented and other methods according to the present disclosure, are deemed to be within the scope of patent-eligible inventions under 35 U.S.C. § 101.

[0096] Additional examples of controllers 100 according to 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, and U.S. Patent Publication Nos. 2005 / 0266284, 2005 / 0266285, 2006 / 0024540, 2006 / 0134473, and 2008 / 0176118, the complete disclosures of which are incorporated herein by reference.

[0097] The hydrogen-producing fuel processing system 10 and / or HPFCS 12 according to the present disclosure may include (be configured and / or operate in) multiple operating modes. The controller 100 may be utilized to transition the hydrogen-producing fuel processing system 10 and / or HPFCS 12 to and / or between multiple operating modes and / or maintain the hydrogen-producing fuel processing system 10 and / or HPFCS 12 in a selected operating mode. One example of an operating (or operational) mode is a “hydrogen-producing” mode in which the fuel processing system produces a product hydrogen stream from one or more feedstock streams in a capacity adequate to satisfy the hydrogen demand of the fuel cell system 42 to produce an electrical power output. As described above, in the hydrogen-producing mode, the feedstock supply system supplies one or more feedstock streams to the hydrogen-producing region, which produces a mixed gas stream, and the separation assembly separates the mixed gas stream into a product hydrogen stream and a by-product stream.

[0098] Additional examples of operational modes include an "off" mode in which the fuel processing system is not heated, does not receive a feed stream, or does not produce a mixed gas stream, and a "primed" (and / or "idle") mode in which the fuel processing system is maintained at a thermally buffered elevated temperature but does not receive a feed stream and / or does not produce a mixed gas stream. Examples of buffer or preheat temperatures and temperature ranges are described herein.

[0099] In this disclosure, some exemplary and non-limiting examples are described and / or presented in the form of flow diagrams or flowcharts, where methods are shown and described as a series of blocks or steps. Unless otherwise specified in the accompanying description, it is within the scope of this disclosure that the order of the blocks may differ from the order depicted in the flow diagrams, including that two or more blocks (or steps) occur in a different order and / or simultaneously. It is also within the scope of this disclosure that blocks or steps may be implemented as logic or described as being implemented as logic. In some applications, blocks or steps may represent equations and / or operations performed by functionally equivalent circuitry 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, perform an action, change state, generate an output or display, and / or make a decision.

[0100] As used herein, the term "and / or" placed between a first entity and a second entity means one of (1) the first entity, (2) the second entity, and (3) the first entity and the second entity. Also, multiple entities listed with "and / or" should be construed similarly, i.e., to mean "one or more" of the entities so joined. Optionally, entities other than those specifically identified by the "and / or" clause may be present, whether or not related to the specifically identified entity. 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 A only (optionally including entities other than B), in another embodiment, refer to B only (optionally including entities other than A), and in yet another embodiment, refer to both A and B (optionally including other entities). These entities may refer to elements, actions, structures, steps, operations, values, etc.

[0101] As used herein, the phrase "at least one" in reference to a list of one or more entities should be understood to mean at least one entity selected from any one or more entities in the list of entities, but not necessarily including at least one of each and every entity specifically listed in the list of entities, and not excluding any combination of entities in the list of entities. This definition also recognizes that entities other than those specifically identified in the list of entities to which the phrase "at least one" refers may optionally be present, whether or not related to the specifically identified entity. 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") may refer, in one embodiment, to the inclusion of at least one, optionally one or more, A, with no B present (and optionally including entities other than B); in another embodiment, to at least one with no A present (and optionally including entities other than A), optionally including one or more B; and, in yet another embodiment, to at least one optionally including one or more As, and at least one optionally including one or more Bs (and optionally including other entities). In other words, the terms "at least one," "one or more," and "and / or" are open-ended expressions that operate as both conjunctions and conjunctions.For example, each of the phrases "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 mean A alone, B alone, C alone, A and B together, A and C together, B and C together, A, B, and C together, and any of the above, optionally in combination with at least one other entity.

[0102] If a patent, patent application, or other reference is incorporated herein by reference and (1) defines a term in a manner that conflicts with either the non-incorporated portion of this disclosure or the other incorporated reference, and / or (2) conflicts in any other way, the non-incorporated portion of this disclosure shall control, and that term or incorporated disclosure shall control only with respect to the reference in which the term was defined and / or in which the incorporated disclosure originally resided.

[0103] As used herein, the terms "adapted" and "configured" mean that an element, component, or other subject matter is designed and / or intended to perform a certain function. Thus, use of the terms "adapted" and "configured" should be interpreted to mean that an element, component, and / or other subject matter is specifically selected, created, implemented, utilized, programmed, and / or designed for the purpose of performing a function, rather than that a given element, component, or other subject matter is merely "capable of" performing a certain function. Also, elements, components, and / or other described subject matter that are described as being adapted to perform a particular function may additionally or alternatively be described as being configured to perform that function, and vice versa, within the scope of this disclosure.

[0104] As used herein, the terms "for example," "as an example," and / or simply "example," when used in connection with one or more components, features, details, structures, embodiments, and / or methods according to the present disclosure, are intended to convey that the described components, features, details, structures, embodiments, and / or methods are illustrative, non-exclusive examples of components, features, details, structures, embodiments, and / or methods according to the present disclosure. Thus, the described components, features, details, structures, embodiments, and / or methods are not intended to be limiting, essential, or exclusive / exhaustive, and other components, features, details, structures, embodiments, and / or methods, including structurally and / or functionally similar and / or equivalent components, features, details, structures, embodiments, and / or methods, are also within the scope of the present disclosure.

[0105] As used herein, "at least substantially," when modifying a degree or relationship, can include not only the stated "substantial" degree or relationship, but also the entire range of the stated degree or relationship. A substantial amount of a stated degree or relationship can include at least 75% of the stated degree or relationship. For example, an object at least substantially formed from a material includes an object in which at least 75% of the object is formed from the material, and also includes an object formed entirely from the material. As another example, a first length at least substantially the same as a second length includes a first length within 75% of the second length, and also includes a first length that is the same as the second length.

[0106] Illustrative, non-exclusive examples of systems and methods according to the present disclosure are set forth in the enumerated paragraphs below. It is within the scope of this disclosure that individual steps of the methods referred to herein, including in the enumerated paragraphs below, may additionally or alternatively be referred to as a "step for" performing the referenced action.

[0107] A1 A method of operating a hydrogen generating fuel cell system (HPFCS), comprising: initiating a supply of a stored hydrogen stream comprising stored hydrogen gas to the fuel cell stack, wherein prior to the initiation, the stored hydrogen gas is stored in a low-pressure hydrogen storage tank at a hydrogen storage pressure; generating electricity from the stored hydrogen gas with a fuel cell stack; monitoring a hydrogen delivery variable indicative of the flow of stored hydrogen to the fuel cell stack during a delivery time interval following the initiating step; Detecting a change in a hydrogen supply variable; and Responding to the detection; A method comprising:

[0108] A2. The method of paragraph A1, wherein the initiating step includes opening a stored hydrogen supply valve.

[0109] A3. The method of paragraph A2, wherein the HPFCS includes a stored hydrogen supply conduit configured to convey a stored hydrogen flow from a low-pressure hydrogen storage tank to the fuel cell stack, and further wherein opening the stored hydrogen supply valve includes allowing a flow of stored hydrogen gas from the low-pressure hydrogen storage tank to the fuel cell stack via the stored hydrogen supply conduit.

[0110] A4 A method according to any one of paragraphs A1 to A3, wherein the starting step includes flowing a flow of stored hydrogen from a low-pressure hydrogen storage tank through a stored hydrogen supply pressure regulator to the fuel cell stack, the stored hydrogen supply pressure regulator being configured to adjust the supply pressure of the stored hydrogen gas to the fuel cell stack.

[0111] A5 In the method according to any one of paragraphs A1 to A4, the hydrogen storage pressure is (i) at least 75 kilopascal 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, or at least 190 kPag; and (ii) up to 250kPag, up to 240kPag, up to 230kPag, up to 220kPag, up to 210kPag, up to 200kPag, up to 195kPag, up to 190kPag, up to 185kPag, or up to 180kPag; A method in which at least one of the above is satisfied.

[0112] A6 In the method according to any one of paragraphs A1 to A5, the supply time interval is: (i) beginning immediately after the initiating step, and (ii) starting with a starting step; A method in which at least one of the above is satisfied.

[0113] A7. The method of any one of paragraphs A1 to A6, wherein the duration of the delivery time interval is: (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 (ii) up to 120 seconds, up to 110 seconds, up to 100 seconds, up to 90 seconds, up to 80 seconds, up to 70 seconds, up to 60 seconds, up to 55 seconds, up to 50 seconds, up to 45 seconds, up to 40 seconds, up to 35 seconds, or up to 30 seconds; A method in which at least one of the above is satisfied.

[0114] A8. The method of any of paragraphs A1-A7, wherein the HPFCS includes a hydrogen supply variable detector, and further wherein the monitoring step includes monitoring the hydrogen supply variable using the hydrogen supply variable detector.

[0115] A9 The method of any of paragraphs A1-A8, wherein the hydrogen supply variable includes or is the hydrogen supply pressure of the stored hydrogen gas.

[0116] A10. The method of paragraph A9, wherein the monitoring step comprises: (i) in a low-pressure hydrogen storage tank; (ii) downstream of a low-pressure hydrogen storage tank; (iii) upstream of the stored hydrogen supply valve; and (iv) upstream of the stored hydrogen supply pressure regulator; monitoring the hydrogen supply pressure of at least one of

[0117] A11. The method of any of paragraphs A1-A10, wherein the detecting step includes detecting that the change in the hydrogen supply variable is greater than a threshold hydrogen supply variable change.

[0118] A12. The method of any of paragraphs A9 to A11, wherein the detecting step includes calculating the change in hydrogen supply pressure during the supply time interval as the difference between the hydrogen supply pressure before initiation and the hydrogen supply pressure after initiation.

[0119] A13 The method of any of paragraphs A1-A12, wherein the threshold hydrogen supply variable variation includes or is a threshold hydrogen supply pressure change, optionally, the threshold 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.

[0120] A14 The method of any of paragraphs A12-A13, wherein the threshold hydrogen supply pressure change is a threshold pressure change multiple of a nominal supply pressure change occurring in the supply time interval during normal operation of the HPFCS.

[0121] A15 The method of paragraph A14, wherein the threshold pressure change factor is 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, or 7.

[0122] A16 The method of any of paragraphs A14-A15, wherein the nominal supply pressure change is up to 5 kPa, up to 7.5 kPa, up to 10 kPa, up to 12.5 kPa, up to 15 kPa, up to 17.5 kPa, or up to 20 kPa.

[0123] A17 The method of any of paragraphs A1-A16, wherein the hydrogen supply variable includes or is the hydrogen flow rate of the stored hydrogen stream.

[0124] A18. The method of paragraph A17, wherein the monitoring step comprises: (i) downstream of a low-pressure hydrogen storage tank; and (ii) Upstream of the fuel cell stack monitoring the hydrogen flow rate of at least one of

[0125] A19 The method of any of paragraphs A1-A18, wherein the threshold hydrogen supply change includes or is a threshold hydrogen supply flow rate magnitude.

[0126] A20. The method of paragraph A19, wherein the threshold hydrogen supply flow rate occurs during the supply time interval and normal operation of the HPFCS and is a threshold flow rate multiple of the nominal hydrogen flow rate, and optionally the threshold flow rate multiple is 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, or 7.

[0127] A21 The method of any of paragraphs A19-A20, wherein the fuel cell stack has a maximum design wattage, and further wherein the magnitude of the threshold hydrogen supply flow rate is a number of watts times the maximum design wattage.

[0128] A22 The method of paragraph A21, wherein the wattage multiplier 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.

[0129] A23 The method of any of paragraphs A1-A22, wherein the responding step includes responding to the detection when the change in the hydrogen supply variable differs from a threshold hydrogen supply variable change.

[0130] A24 In the method according to any one of paragraphs A1 to A23, the corresponding step is to determine whether the hydrogen gas leak is (i) Within HPFCS, (ii) downstream of a low-pressure hydrogen storage tank; and (iii) In the fuel cell stack determining that the information is present in at least one of the following:

[0131] A25 A method according to any one of paragraphs A1 to A24, wherein the starting step includes a step of starting the supply of stored hydrogen flow to a predetermined fuel cell stack among a plurality of fuel cell stacks of the HPFCS, and further, the corresponding step includes a step of stopping the supply of stored hydrogen flow to the predetermined fuel cell stack.

[0132] A26 The method according to paragraph A25, further comprising: (i) following the shutting down step, maintaining a supply of the stored hydrogen flow to another fuel cell stack of the plurality of fuel cell stacks; and (ii) following the shutting down step, repeating the starting step to provide the stored hydrogen flow to another fuel cell stack of the plurality of fuel cell stacks. A method comprising at least one of the following:

[0133] A27 The method of any of paragraphs A1-A26, wherein the corresponding step includes initiating a system diagnostic test of the HPFCS.

[0134] A28 The method of any of paragraphs A1-A27, wherein the corresponding step includes notifying an operator of the HPFCS that there is a possible hydrogen gas leak in the HPFCS.

[0135] A29 The method according to any one of paragraphs A1 to A28, wherein the corresponding step includes a step of stopping operation of the HPFCS.

[0136] A30 The method of any of paragraphs A1 to A29, wherein the corresponding step includes stopping the supply of the stored hydrogen flow to the fuel cell stack.

[0137] A31 The method according to any one of paragraphs A1 to A30, further comprising: (i) providing a feed stream comprising a carbon-containing feedstock to a fuel processing assembly of an HPFCS; (ii) producing a product hydrogen stream from the feed stream using a fuel processing assembly, the product hydrogen stream comprising product hydrogen gas; and (iii) delivering the product hydrogen stream as stored hydrogen gas to a low-pressure hydrogen storage tank; producing hydrogen gas by

[0138] A32. The method of paragraph A31, further comprising the step of determining that there is a demand for electrical power output by the energy consuming device, and further wherein both the step of initiating the supply of stored hydrogen gas and the step of producing hydrogen gas are performed in response to the determining step.

[0139] A33 The method of paragraph A32, further comprising reducing the mass of stored hydrogen gas in the low-pressure hydrogen storage tank during a start-up window of the fuel processing assembly.

[0140] A34 In the method according to any one of paragraphs A32 to A33, the supply time interval is an initial supply time; (i) beginning immediately after the initiating step, and (ii) starting with a starting step; A method that is at least one of the above.

[0141] A35. The method of paragraph A31, further comprising: (i) replenishing stored hydrogen gas by flowing the produced hydrogen gas stream into a low-pressure hydrogen storage tank; and (ii) pressurizing a low pressure hydrogen storage tank with the produced hydrogen gas stream to hydrogen storage pressure; A method including at least one of the following:

[0142] A36 In the method described in paragraph A35, the supply time interval is: (i) occurs during the replenishing step, and (ii) occurring during the pressurizing step; A method in which at least one of the above is satisfied.

[0143] A37. A method according to any one of paragraphs A1 to A36, further comprising purging the fuel cell stack using the stored hydrogen flow during the purge time interval, and further wherein the supply time interval excludes the purge time interval.

[0144] A38 The method of paragraph A37, including omitting the corresponding step during the purge time interval.

[0145] A39 The method of paragraph A37, wherein the omitting step includes omitting for an omit time period that is a threshold omit time multiple of the purge time interval.

[0146] A40 In the method described in paragraph A39, the multiple of the threshold omission time is (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 (ii) maximum 10, maximum 9, maximum 8, maximum 7, maximum 6, maximum 5, maximum 4, maximum 3, or maximum 2; A method that is at least one of the above.

[0147] B1 A hydrogen generating fuel cell system (HPFCS), a feedstock supply system configured to supply a feedstock stream comprising a carbon-containing feedstock; a fuel processing assembly configured to receive a feed stream and to produce a product hydrogen stream comprising product hydrogen gas from the feed stream; a low-pressure hydrogen storage tank configured to receive and store hydrogen gas as stored hydrogen gas; a fuel cell stack; the fuel cell stack is configured to receive the stored hydrogen stream and generate electrical power from the stored hydrogen stream, a stored hydrogen supply conduit configured to deliver the stored hydrogen stream, including the stored hydrogen gas, to the fuel cell stack; a controller programmed to control operation of the HPFCS in accordance with the method of any of paragraphs A1 through A40; HPFCS equipped with.

[0148] B2. The HPFCS of 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 stored hydrogen gas.

[0149] B3 The HPFCS of paragraphs B1-B2, wherein the fuel processing assembly includes a hydrogen-producing region configured to receive a feed stream and produce a mixed gas stream comprising hydrogen gas and other gases from the feed stream.

[0150] B4. The HPFCS of paragraph B3, wherein the hydrogen-producing region includes a reformer.

[0151] B5. The HPFCS described in any of paragraphs B3-B4, wherein the fuel processing assembly includes a separation assembly configured to receive the mixed gas stream and produce a by-product stream containing a majority of other gases and a product hydrogen stream.

[0152] B6. The HPFCS of paragraph B5, wherein the separation assembly includes at least one of a membrane separation assembly and a pressure swing adsorption separation assembly.

[0153] B7. The HPFCS of any of paragraphs B1-B6, further comprising a stored hydrogen supply valve configured to selectively adjust the flow of stored hydrogen in the stored hydrogen supply conduit.

[0154] B8. The HPFCS of any of paragraphs B1-B7, further comprising a stored hydrogen supply pressure regulator configured to adjust the hydrogen supply pressure of the stored hydrogen stream received by the fuel cell stack.

[0155] B9 The HPFCS of any of paragraphs B1-B8, further comprising a hydrogen supply variable detector configured to detect a parameter indicative of a hydrogen supply variable.

[0156] B10. The HPFCS of paragraph B9, wherein the variable hydrogen supply detector includes or is a pressure detector.

[0157] B11. In the HPFCS described in paragraph B10, the pressure detector: (i) in a low-pressure hydrogen storage tank; (ii) downstream of a low-pressure hydrogen storage tank; (iii) upstream of the stored hydrogen supply valve; and (iv) upstream of the stored hydrogen supply pressure regulator; and detecting a hydrogen supply pressure in at least one of the HPFCSs.

[0158] B12. The HPFCS of any of paragraphs B10-B11, wherein the hydrogen supply fluctuation detector includes or is a hydrogen flow meter configured to detect a hydrogen supply flow rate of the stored hydrogen stream.

[0159] B13. In the HPFCS described in paragraph B12, the hydrogen flow meter: (i) downstream of a low-pressure hydrogen storage tank; and (ii) upstream of the fuel cell stack; and a HPFCS configured to detect a hydrogen supply flow rate of at least one of the HPFCSs.

[0160] C1. A non-transitory computer-readable storage medium containing computer-readable instructions that, when executed, direct a hydrogen-producing fuel cell system to perform the method of any of paragraphs A1-A40.

[0161] D1. A method of using the method of any of paragraphs A1-A40 in conjunction with the hydrogen generating fuel cell system of any of paragraphs B1-B13.

[0162] D2. A method of using the hydrogen generating fuel cell system of any of paragraphs B1 to B13 in combination with any of the methods of any of paragraphs A1 to A40.

[0163] D3 How to use hydrogen supply variables to indicate hydrogen gas leaks in a hydrogen generating fuel cell system. [Industrial Applicability]

[0164] The hydrogen producing fuel cell systems and methods disclosed herein are applicable to the hydrogen generation and energy production industries, including the fuel cell industry.

[0165] The above disclosure is believed to encompass multiple distinct inventions with independent utility. While each of these inventions is disclosed in a preferred form, the specific embodiments thereof as disclosed and illustrated herein are susceptible to numerous variations and are not to be considered in a limiting sense. The subject matter of the inventions includes all novel and non-obvious combinations and subcombinations of the various elements, features, functions and / or properties disclosed herein. Similarly, when a claim recites "a" or "a first" element, or the equivalent, such claim should be understood to include the incorporation of one or more such elements, and neither requires nor excludes two or more such elements.

[0166] The following claims are believed to be directed to one of the disclosed inventions, particularly pointing out certain combinations and subcombinations that are novel and non-obvious. Inventions embodied in other combinations and subcombinations of features, functions, elements and / or properties may be claimed by amending the present claims or by presenting new claims in this or a related application. Such amended or new claims, whether directed to a different invention or the same invention, or of a different, broader, narrower, or equal scope than the original claims, are deemed to fall within the inventive spirit of this disclosure.

Claims

1. 1. A method of operating a hydrogen producing fuel cell system (HPFCS), comprising: a step of initiating supply of a stored hydrogen stream comprising stored hydrogen gas to the fuel cell stack, the stored hydrogen gas being stored in a low-pressure hydrogen storage tank at a hydrogen storage pressure before the initiation; generating electrical power from the stored hydrogen gas using the fuel cell stack; monitoring a hydrogen delivery variable indicative of the stored hydrogen flow to the fuel cell stack during a delivery time interval following the initiating step; detecting a change in the hydrogen supply variable that is greater than a threshold hydrogen supply variable change; and a step corresponding to the detecting step; A method comprising:

2. 10. The method of claim 1, wherein the hydrogen storage pressure is at least 75 kilopascals gauge (kPag) and up to 250 kPag.

3. 2. The method of claim 1, wherein the delivery time interval is: (i) beginning immediately after the starting step; and (ii) starting with the starting step; A method that is at least one of the above.

4. 10. The method of claim 1, wherein the delivery time interval is at least 5 seconds long and at most 120 seconds long.

5. 10. The method of claim 1, wherein the HPFCS includes a hydrogen supply variable detector, and further wherein monitoring includes utilizing the hydrogen supply variable detector to monitor the hydrogen supply variable.

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

7. 7. The method of claim 6, wherein the detecting step includes calculating the change in the hydrogen supply pressure during the delivery time interval as the difference between the hydrogen supply pressure before the step of starting the hydrogen delivery and the hydrogen supply pressure after the step of starting the hydrogen delivery.

8. 10. The method of claim 1, wherein the hydrogen supply variables include the hydrogen supply pressure of the stored hydrogen gas, and further wherein the monitoring step includes: (i) upstream of the stored hydrogen supply valve; and (ii) upstream of the stored hydrogen supply pressure regulator; monitoring the hydrogen supply pressure of at least one of:

9. 9. The method of claim 8, wherein the detecting step includes calculating the change in the hydrogen supply pressure during the delivery time interval as the difference between the hydrogen supply pressure before the step of starting the hydrogen delivery and the hydrogen supply pressure after the step of starting the hydrogen delivery.

10. 10. The method of claim 1, wherein the threshold hydrogen supply change comprises a threshold hydrogen supply pressure change of 30 kPa.

11. 11. The method of claim 10, wherein the threshold hydrogen supply pressure change is a threshold pressure change multiple of a nominal supply pressure change occurring in the supply time interval during normal operation of the HPFCS, the threshold pressure change multiple being 1.

5.

12. The method of claim 1 , wherein the hydrogen supply variable comprises a hydrogen flow rate of the stored hydrogen stream.

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

14. 14. The method of claim 13, wherein the threshold hydrogen supply change comprises a threshold hydrogen supply flow rate magnitude.

15. 15. The method of claim 14, wherein the magnitude of the threshold hydrogen supply flow rate is a threshold flow rate multiple of the magnitude of a nominal hydrogen flow rate occurring during the supply time interval and normal operation of the HPFCS, the threshold flow rate multiple being 1.

5.

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

17. 2. The method of claim 1, wherein the corresponding step is to determine whether the hydrogen gas leak is (i) within the HPFCS; (ii) downstream of the low-pressure hydrogen storage tank; and (iii) within the fuel cell stack; determining that the at least one of the following is present:

18. 2. The method of claim 1, wherein the corresponding step comprises: (i) initiating a system diagnostic test of the HPFCS; (ii) notifying an operator of the HPFCS of the possible hydrogen gas leak in the HPFCS; (iii) stopping operation of the HPFCS; and (iv) stopping the supply of stored hydrogen to the fuel cell stack; A method including at least one of the following:

19. 2. The method of claim 1, wherein the starting step includes starting the supply of the stored hydrogen stream to a predetermined one of a plurality of fuel cell stacks of the HPFCS, and further wherein a corresponding step includes stopping the supply of the stored hydrogen stream to the predetermined one of the fuel cell stacks.

20. 20. The method of claim 19, further comprising the step of maintaining a supply of the stored hydrogen stream to another fuel cell stack of the plurality of fuel cell stacks following the step of shutting down.

21. 20. The method of claim 19, further comprising repeating the step of shutting down followed by the step of starting to supply the stored hydrogen stream to another fuel cell stack of the plurality of fuel cell stacks.

22. The method of claim 1 further comprising: (i) providing a feed stream comprising a carbon-containing feedstock to a fuel processing assembly of said HPFCS; (ii) producing, by the fuel processing assembly, a product hydrogen stream from the feed stream, the product hydrogen stream comprising product hydrogen gas; and (iii) supplying the product hydrogen stream as the stored hydrogen gas to the low-pressure hydrogen storage tank; producing hydrogen gas by

23. 23. The method of claim 22, further comprising the step of determining that there is a demand for electrical power output by an energy consuming device, and further wherein both the step of initiating the supply of stored hydrogen gas and the step of producing hydrogen gas are performed in response to the step of determining.

24. 23. The method of claim 22, following the start-up timeframe of the fuel processing assembly, further comprising: (i) replenishing the stored hydrogen gas by flowing the produced hydrogen gas into the low-pressure hydrogen storage tank; and (ii) pressurizing the low-pressure hydrogen storage tank with the produced hydrogen gas to the hydrogen storage pressure; A method comprising at least one of the following:

25. 25. The method of claim 24, wherein the delivery time interval is: (i) occurs during the refilling step, and (ii) occurring during the pressurizing step; A method comprising at least one of the following:

26. 10. The method of claim 1, further comprising utilizing the stored hydrogen flow to purge the fuel cell stack during a purge time interval, and further wherein the supply time interval is exclusive of the purge time interval.

27. 1. A hydrogen generating fuel cell system (HPFCS), comprising: a feedstock supply system configured to supply a feedstock stream comprising a carbon-containing feedstock; a fuel processing assembly configured to receive a feed stream and to produce a product hydrogen stream from the feed stream, the product hydrogen stream comprising product hydrogen gas; 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 gas; a fuel cell stack; a stored hydrogen supply conduit configured to convey a stored hydrogen stream comprising the stored hydrogen gas to the fuel cell stack, the fuel cell stack configured to receive the stored hydrogen stream and generate electrical power from the stored hydrogen stream; and a controller programmed to control operation of the HPFCS in accordance with the method of claim 1; HPFCS equipped with.

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