Control method and system of fuel cell anode circulation system and hydrogen-oxygen fuel cell

Abstract

The invention discloses a control method and system of a fuel cell anode circulation system and a hydrogen-oxygen fuel cell. The control method is used for controlling the supply of anode gas to a plurality of electric piles, and comprises the following steps: configuring at least one of the plurality of electric piles as an upstream electric pile, and configuring at least one of the plurality of electric piles as a downstream electric pile; after the reaction is carried out for a preset time, switching at least one upstream electric pile to a downstream electric pile and / or switching at least one downstream electric pile to the upstream electric pile; wherein the upstream electric pile inputs anode gas from an anode gas supply source for reaction, and the downstream electric pile inputs residual anode gas discharged by the upstream electric pile for reaction. According to the control method and system of the fuel cell anode circulating system and the fuel cell, the problem that the anode circulating system in the prior art is insufficient in reliability can be solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fuel cells, in particular to a control method and system of a fuel cell anode circulation system and a hydrogen-oxygen fuel cell. BACKGROUND

[0002] A fuel cell is a device in which reaction gas undergoes an electrochemical reaction in an electric pile to generate electric energy. A common proton exchange membrane hydrogen fuel cell, as a zero-carbon emission power generation device, has been widely used in the field of transportation and fixed power generation.

[0003] In order to ensure the reliability of the electrode operation, the current fuel cell system needs to use an anode circulation system. The anode circulation system is mainly used to separate and discharge liquid water from the anode gas after the reaction of the electric pile, and then recycle the anode gas into the electric pile for reaction. During the anode gas circulation process, since the anode gas supply source also continuously inputs anode gas into the electric pile, the anode gas has a large pressure, so the anode gas circulation needs to be boosted to deliver the gas back to the electric pile. Therefore, the existing anode circulation system needs to be configured with a circulation pump and an ejector. The configuration of these components not only increases the cost, but also causes the circulation pump to have faults such as oil leakage, impeller wear and low-temperature stall in actual use, and the actual circulation capacity is affected by the electric pile flow resistance, pipeline arrangement and operating conditions, and the actual excess coefficient is unstable, and the reliability is weak.

[0004] Therefore, it is necessary to provide a technical scheme to overcome the shortcomings of the prior art. SUMMARY

[0005] In order to overcome the defects of the prior art, the present application provides a control method and system of a fuel cell anode circulation system and a fuel cell, which solves the problem of insufficient reliability of the anode circulation system in the prior art.

[0006] The present application is realized by the following technical scheme: a control method of a fuel cell anode circulation system, a control method of a fuel cell anode circulation system for controlling the supply of anode gas to multiple electric piles, the control method comprising: configuring at least one of the multiple electric piles as an upstream electric pile and configuring at least one of the multiple electric piles as a downstream electric pile; switching at least one upstream electric pile to a downstream electric pile and / or switching at least one downstream electric pile to an upstream electric pile after a preset reaction time; wherein the upstream electric pile inputs anode gas from an anode gas supply source for reaction, and the downstream electric pile inputs the remaining anode gas from the upstream electric pile for reaction.

[0007] As a further improved technical solution, the control method comprises: in a low load working condition, the number of upstream stacks is configured to be no more than the number of downstream stacks.

[0008] As a further improved technical solution, the control method comprises: in a high load working condition, the number of upstream stacks is configured to be no less than the number of downstream stacks.

[0009] As a further improved technical solution, the control method comprises: in a low load working condition, the switching period of switching upstream stacks to downstream stacks or switching downstream stacks to upstream stacks is greater than the switching period of switching upstream stacks to downstream stacks or switching downstream stacks to upstream stacks in a high load working condition.

[0010] As a further improved technical solution, the reaction remaining anode gas discharged by the upstream stack is only input into the downstream stack by the pressure difference between the upstream stack and the downstream stack.

[0011] As a further improved technical solution, the control method comprises: the reaction remaining anode gas discharged by the upstream stack is subjected to gas-liquid separation and then input into the downstream stack.

[0012] As a further improved technical solution, the control method comprises setting the anode excess coefficient λ=(m+n) / m of the upstream stack, wherein m is the number of upstream stacks, and n is the number of downstream stacks.

[0013] The present application also realizes the following technical solutions: a fuel cell anode circulation system comprising an anode gas supply source, a plurality of stacks, and a switching valve, the plurality of stacks and the anode gas supply source and the plurality of stacks being connected by the switching valve; wherein the switching valve is configured to: connect at least one of the plurality of stacks as an upstream stack and at least one of the plurality of stacks as a downstream stack; and, switch at least one upstream stack to a downstream stack and / or switch at least one downstream stack to an upstream stack; wherein the upstream stack is a stack that inputs anode gas from the anode gas supply source for reaction, and the downstream stack is a stack that inputs reaction remaining anode gas discharged by the upstream stack for reaction.

[0014] As a further improved technical solution, the switching valve comprises a plurality of input valves connected to the input end of the stack, and a plurality of output valves connected to the output end of the stack, the plurality of output valves being controllably connected to the inlet end of the same water separator, and the plurality of input valves being controllably connected to the outlet end of the water separator.

[0015] As a further improved technical solution, the system comprises a nitrogen discharge valve, and the plurality of stacks are connected between the anode gas supply source and the nitrogen discharge valve through a plurality of switching valves, wherein the number of the stacks is not less than three, and any two of the stacks can be switched between series connection and parallel connection through the switching valves.

[0016] The application is also achieved by the following technical solution: a hydrogen-oxygen fuel cell comprising the fuel cell anode circulation system, wherein the anode gas provided by the anode gas supply source is hydrogen, and the gas output by the output end of the upstream stack is a mixture of hydrogen, nitrogen and water vapor.

[0017] The control method of the fuel cell anode circulation system provided by the application can realize normal circulation of the anode gas and self-circulation of the anode gas without the aid of a circulation pump, so that the circulation pump and the ejector can be omitted, and the reliability of the anode circulation system is improved. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a connection diagram of the fuel cell anode circulation system of the application.

[0019] Figure 2 is a connection diagram of the fuel cell anode circulation system of the application in one operating state.

[0020] Figure 3 is a connection diagram of the fuel cell anode circulation system of the application in another operating state.

[0021] The reference signs are as follows: 1-anode gas supply source; 11-hydrogen inlet valve; 12-nitrogen discharge valve; 21-first stack; 22-second stack; 23-third stack; 3-water separator; 41-first input valve; 42-first output valve; 51-second input valve; 52-second output valve; 61-third input valve; 62-third output valve. DETAILED DESCRIPTION

[0022] In order to have a clearer understanding of the technical features, objects and effects of the application, the specific embodiments of the application will be described in detail with reference to the drawings.

[0023] The technical solutions in the embodiments of the application will be described clearly and completely below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only some of the embodiments of the application, but not all the embodiments of the application. Based on the embodiments of the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0024] Referring to Figure 1 As shown in the drawings, the present application provides a fuel cell anode circulation system and a control method thereof. The fuel cell anode circulation system comprises an anode gas supply source 1, a plurality of stacks, and a switching valve, the plurality of stacks and the anode gas supply source 1 and the plurality of stacks are connected by the switching valve. The switching valve is configured to: connect at least one of the plurality of stacks as an upstream stack, connect at least one of the plurality of stacks as a downstream stack; and switch at least one upstream stack to a downstream stack and at least one downstream stack to an upstream stack; wherein the upstream stack is a stack that inputs anode gas from the anode gas supply source for reaction, and the downstream stack is a stack that inputs anode gas remaining after reaction from the upstream stack for reaction.

[0025] As Figure 1 As shown in the drawings, in an embodiment, the anode circulation system comprises a hydrogen inlet valve 11, a plurality of stacks, and a nitrogen outlet valve 12, the anode gas supply source 1, the hydrogen inlet valve 11, the plurality of stacks, and the nitrogen outlet valve 12 are connected in sequence, and the downstream of the nitrogen outlet valve 12 is connected to a tail exhaust. In this embodiment, the anode gas supply source 1 supplies hydrogen, the hydrogen provided by the anode gas supply source 1 enters the plurality of stacks through the hydrogen inlet valve 11, reacts with the air supplied by the air supply subsystem in the stacks, and the anode gas remaining after reaction in the stacks is separated from the liquid by the water trap 3, then is circulated to the stacks to participate in the reaction again. During the reaction process, the opening or closing of the nitrogen outlet valve 12 is controlled according to the needs, so as to realize the normal operation of the system.

[0026] The plurality of stacks are connected with the anode gas supply source 1 and between the plurality of stacks by switching valves. The plurality of stacks are connected between the anode gas supply source 1 and the nitrogen exhaust valve 12 by the switching valves, which include a plurality of input valves connected to the input ends of the stacks and a plurality of output valves connected to the output ends of the stacks. In an embodiment, the number of the stacks is not less than three and any two of them can be switched between series connection and parallel connection by the switching valves. This embodiment takes three stacks as an example, and it can be understood that in other embodiments, the stacks can also be two, four or more. In this embodiment, the stacks include a first stack 21, a second stack 22 and a third stack 23, and the switching valves include a first input valve 41, a second input valve 51, a third input valve 61 and a first output valve 42, a second output valve 52 and a third output valve 62. The first stack 21 is connected to the anode gas supply source 1 by the first input valve 41 and to the nitrogen exhaust valve 12 by the first output valve 42, the second stack 22 is connected to the anode gas supply source 1 by the second input valve 51 and to the nitrogen exhaust valve 12 by the second output valve 52, and the third stack 23 is connected to the anode gas supply source 1 by the third input valve 61 and to the nitrogen exhaust valve 12 by the third output valve 62. The first input valve 41, the second input valve 51, the third input valve 61 and the first output valve 42, the second output valve 52 and the third output valve 62 are all multi-way valves, each of which can switch the connection of the stacks between the anode gas supply source 1 and the nitrogen exhaust valve 12 and also connect the stacks with each other.

[0027] See also Figure 2 and Figure 3As shown, multiple connection modes can be achieved by controlling the on / off modes of each switching valve. For ease of description, the valve port on the left side of each switching valve shown in the figure is referred to as the first valve port, the valve port on the right side as the second valve port, and the valve port on the upper or lower side as the third valve port. In this embodiment, the first input valve 41, the second input valve 51, the third input valve 61, the first output valve 42, the second output valve 52, and the third output valve 62 are all three-way valves; wherein, the first valve port of each of the first input valve 41, the second input valve 51, and the third input valve 61 is connected to the anode gas supply source 1, their respective second valve ports are connected to the input end of the corresponding fuel cell stack, and their respective third valve ports are connected to each other in a controllable on / off manner; the first valve port of each of the first output valve 42, the second output valve 52, and the third output valve 62 is connected to the output end of the corresponding fuel cell stack, their respective second valve ports are connected to the nitrogen venting valve 12, and their respective third valve ports are connected to each other in a controllable on / off manner. Multiple output valves are connected to the inlet end of the same water distributor 3 in an on / off controllable manner, and multiple input valves are connected to the outlet end of the same water distributor 3 in an on / off controllable manner; that is, the third valve ports of the first output valve 42, the second output valve 52, and the third output valve 62 are connected to the third valve ports of the first input valve 41, the second input valve 51, and the third input valve 61 through the water distributor 3. By having multiple fuel cells share a single water distributor 3, the number of components can be reduced, and the complexity and cost of the system can be lowered.

[0028] like Figure 2 As shown, the dashed lines represent disconnections, and the solid lines represent connections. Specifically, the third valve port of the first input valve 41, the third valve port of the second input valve 51, and the first valve port of the third input valve 61 are not connected, and the second valve ports of the first output valve 42, the second valve port of the second output valve 52, and the third valve port of the third output valve 62 are also not connected. At this time, the anode gas supplied by the anode gas supply source 1 is split into two paths, respectively transported through the first valve port of the first input valve 41 and the first valve port of the second input valve 51 to the first fuel cell stack 21 and the second fuel cell stack 22. The anode gas remaining after the reaction discharged from the first fuel cell stack 21 and the second fuel cell stack 22 flows through the third valve ports of the first output valve 42 and the second output valve 52 to the water separator 3. After liquid separation by the water separator 3, it is transported through the third valve port of the third input valve 61 to the third fuel cell stack 23. The gas reacted in the third fuel cell stack 23 can be discharged through the nitrogen venting valve 12. Figure 2 In the connection shown, the first fuel cell stack 21 and the second fuel cell stack 22 are connected in parallel and constitute the upstream fuel cell stack, while the third fuel cell stack 23 constitutes the downstream fuel cell stack.

[0029] like Figure 3As shown, the third port of the first input valve 41, the first port of the second input valve 51 and the first port of the third input valve 61 are disconnected, and the second port of the first output valve 42, the third port of the second output valve 52 and the third port of the third output valve 62 are disconnected, at this time, the anode gas provided by the anode gas supply source 1 is only delivered to the first stack 21 through the first port of the first input valve 41, the reaction remaining anode gas discharged from the first stack 21 flows to the water separator 3 through the third port of the first output valve 42, and after being separated by the water separator 3, the anode gas is delivered to the second stack 22 and the third stack 23 through the third port of the second input valve 51 and the third port of the third input valve 61 respectively, and the gas reacted by the second stack 22 and the third stack 23 can be discharged through the nitrogen discharge valve 12. Figure 3 As shown in the connection mode, the first stack 21 constitutes an upstream stack, and the second stack 22 and the third stack 23 are connected in parallel and constitute a downstream stack. It can be understood that by controlling other switching valves, other forms of upstream stack and downstream stack switching can be realized.

[0030] The fuel cell anode circulation system provided by the application relies on the upstream and downstream relationship of multiple stacks, and only relies on the switching of valve pieces to change the upstream and downstream stacks. Since the downstream stack can quantitatively consume the anode gas discharged from the upstream stack, the upstream stack can be set to a high enough anode excess factor. The upstream stack is dry gas in and wet gas out, and the anode gas flowing into the downstream stack is the wet gas discharged from the upstream stack. During operation, the positions of the upstream stack and the downstream stack can be periodically switched, i.e. the upstream stack at the current time is switched to the downstream stack after a short time, and the downstream stack at the current time is switched to the downstream stack after a short time. This not only enables long-term circulation of the discharged anode gas, but also enables the humidity of the anode gas input into each stack to be more balanced.

[0031] The fuel cell anode circulation system provided by the application can realize normal circulation of anode gas by configuring some of the plurality of stacks as upstream stacks and some as downstream stacks and switching after a preset reaction time. Moreover, the anode gas discharged from the upstream stacks is circulated to the downstream stacks instead of being circulated to the upstream stacks themselves, and since the gas pressure of the downstream stacks can be less than that of the upstream stacks, the anode gas can realize self-circulation without the aid of a circulating pump, and the circulating pump and the ejector can be omitted. The switching valve is a valve body, and only on-off control is needed, which is low in cost, simple in control and higher in reliability, and thus the reliability of the anode circulation system can be improved. In different operating stages, such as start-up conditions, low-load conditions, high-load conditions, shutdown and the like, the use of the nitrogen discharge valve 12 and the water discharge valve can completely realize anode gas circulation without a circulating pump and an ejector. In an embodiment, the water discharge valve is integrated in the water distributor 3.

[0032] The application further provides a control method of a fuel cell anode circulation system for controlling supply of anode gas to a plurality of stacks, the control method comprising: configuring at least one of the plurality of stacks as an upstream stack and at least one of the plurality of stacks as a downstream stack; switching at least one upstream stack to a downstream stack and / or at least one downstream stack to an upstream stack after a preset reaction time; wherein the upstream stack inputs anode gas from an anode gas supply source for reaction, and the downstream stack inputs anode gas remaining after reaction discharged from the upstream stack for reaction. In some embodiments, the anode gas remaining after reaction discharged from the upstream stack is only input into the downstream stack by a pressure difference between the upstream stack and the downstream stack, and the anode gas remaining after reaction discharged from the upstream stack is input into the downstream stack after being subjected to gas-liquid separation.

[0033] It should be noted that in some operating conditions, the upstream and downstream positions of all the stacks participating in operation are not switched synchronously. For example, in the connection mode shown in FIG. 1, the first stack 21 is an upstream stack, and the second stack 22 and the third stack 23 are downstream stacks. When the connection mode is switched to the connection mode shown in FIG. 2, the first stack 21 is still an upstream stack, and the third stack 23 is still a downstream stack, and only the second stack 22 is switched from a downstream stack to an upstream stack. One or more stacks can be switched according to actual needs by those skilled in the art. Figure 2 The connection mode shown in FIG. 1, the first stack 21 is an upstream stack, and the second stack 22 and the third stack 23 are downstream stacks. When the connection mode is switched to the connection mode shown in FIG. 2, the first stack 21 is still an upstream stack, and the third stack 23 is still a downstream stack, and only the second stack 22 is switched from a downstream stack to an upstream stack. One or more stacks can be switched according to actual needs by those skilled in the art. Figure 2 The connection mode shown in FIG. 1, the first stack 21 is an upstream stack, and the second stack 22 and the third stack 23 are downstream stacks. When the connection mode is switched to the connection mode shown in FIG. 2, the first stack 21 is still an upstream stack, and the third stack 23 is still a downstream stack, and only the second stack 22 is switched from a downstream stack to an upstream stack. One or more stacks can be switched according to actual needs by those skilled in the art. Figure 3 The connection mode shown in FIG. 1, the first stack 21 is an upstream stack, and the second stack 22 and the third stack 23 are downstream stacks. When the connection mode is switched to the connection mode shown in FIG. 2, the first stack 21 is still an upstream stack, and the third stack 23 is still a downstream stack, and only the second stack 22 is switched from a downstream stack to an upstream stack. One or more stacks can be switched according to actual needs by those skilled in the art.

[0034] The control method comprises: in the starting condition, when there is no current output, only one of the plurality of stacks is connected, or a plurality of stacks are connected in parallel, and the nitrogen discharge valve 12 is opened to operate in a direct discharge mode. The control method comprises: in the low load condition, the number of upstream stacks is not more than the number of downstream stacks to ensure that the upstream stacks have a relatively high excess coefficient. The control method comprises: in the high load condition, the number of upstream stacks is not less than the number of downstream stacks; because the total flow of anode gas is larger in the high load condition, the required excess system of the upstream stack can be relatively small. The control method comprises: the switching period of switching the upstream stack to the downstream stack or switching the downstream stack to the upstream stack in the low load condition is greater than the switching period of switching the upstream stack to the downstream stack or switching the downstream stack to the upstream stack in the high load condition, so as to facilitate the balanced discharge of anode gas and liquid.

[0035] Regarding the number of upstream stacks and downstream stacks, the number is adjusted according to different working conditions. The overall configuration strategy is that when the current density of the stack is large, the number of upstream stacks is large and the number of downstream stacks is small, and when the current density of the stack is small, the number of downstream stacks is large and the number of upstream stacks is small. Regarding the size of the switching period, the size is adjusted according to different working conditions. The overall configuration strategy is that when the current density of the stack is large, the switching period is short, and when the current density of the stack is small, the switching period is long. In some embodiments, the switching period is 0.5s to 10s, preferably 1s to 8s. In a specific embodiment, when the current density is less than 0.5A / cm 2 , the switching period is 5s; when the current density is greater than 0.5A / cm 2 and less than 1A / cm 2 , the switching period is 3s; when the current density is greater than 1A / cm 2 , the switching period is 1s. In a certain state, for example, there are m upstream stacks and n downstream stacks, and the current is equal to I, then the anode excess coefficient of the upstream stack λ= (m+n) / m; in cooperation with the use of the drainage and nitrogen discharge valve, the instantaneous excess coefficient can be slightly larger to reduce the possibility of waterlogging of the stack. In some cases, when the downstream stack appears single low, the problem can be solved by shortening the working period of the nitrogen discharge valve 12, shortening the upstream and downstream switching period of the stack, and timely switching the stack to the upstream stack.

[0036] The application further provides a hydrogen-oxygen fuel cell comprising the fuel cell anode circulation system described above, wherein the anode gas is hydrogen, and the gas output from the output end of the upstream stack is a mixed gas of hydrogen, nitrogen and water vapor. It can be understood by those skilled in the art that the hydrogen-oxygen fuel cell further comprises other components such as a pressure reducing valve, a heater, an air subsystem, a thermal management subsystem and related electrical control parts, etc. In some embodiments, the electrical control of the multiple stacks can be series control or parallel control; the air subsystem and the thermal management subsystem corresponding to the multiple stacks adopt a parallel mode to achieve relatively independent gas supply and heat management. The other components not described in the application can be implemented with reference to the solutions in the prior art.

[0037] It can be known from the above description of the specific embodiments that the control method and system of the fuel cell anode circulation system and the hydrogen-oxygen fuel cell provided by the application can realize normal circulation of the anode gas and self-circulation of the anode gas without the aid of a circulation pump by configuring some of the multiple stacks as upstream stacks and some as downstream stacks and switching after a preset reaction time, so that the circulation pump and the ejector can be omitted and the reliability of the anode circulation system is improved.

[0038] The application is described by several specific embodiments, and those skilled in the art should understand that various modifications and equivalent replacements can be made to the application without departing from the scope of the application. In addition, various modifications can be made to the application for specific situations or specific conditions without departing from the scope of the application. Therefore, the application is not limited to the disclosed specific embodiments, but should include all the embodiments falling within the scope of the claims of the application.

Claims

1. A control method of a fuel cell anode circulation system for controlling supply of anode gas to a plurality of stacks, characterized by, The control method comprises: configuring at least one of the plurality of stacks as an upstream stack and at least one of the plurality of stacks as a downstream stack; switching at least one upstream stack to a downstream stack and / or switching at least one downstream stack to an upstream stack after a preset reaction time; wherein the upstream stack is a stack that inputs anode gas from an anode gas supply source for reaction, and the downstream stack is a stack that inputs anode gas remaining after reaction discharged by the upstream stack for reaction.

2. The control method of the fuel cell anode circulation system according to claim 1, characterized by, The control method comprises: in a low load working condition, the number of upstream stacks is not more than the number of downstream stacks; and in a high load working condition, the number of upstream stacks is not less than the number of downstream stacks.

3. The control method of the fuel cell anode circulation system according to claim 1 or 2, characterized by, The control method comprises: in a low load working condition, the switching period of switching an upstream stack to a downstream stack or switching a downstream stack to an upstream stack is greater than the switching period of switching an upstream stack to a downstream stack or switching a downstream stack to an upstream stack in a high load working condition.

4. The control method of the fuel cell anode circulation system according to claim 1, characterized by, The anode gas remaining after reaction discharged by the upstream stack is only input into the downstream stack by a pressure difference between the upstream stack and the downstream stack.

5. The control method of the fuel cell anode circulation system according to claim 1 or 4, characterized by, The control method comprises: after gas-liquid separation of the anode gas remaining after reaction discharged by the upstream stack, the anode gas is input into the downstream stack.

6. The control method of the fuel cell anode circulation system according to claim 1, characterized by, The control method comprises setting an anode excess coefficient λ=(m+n) / m of the upstream stack, wherein m is the number of upstream stacks, and n is the number of downstream stacks.

7. A fuel cell anode recycle system characterized by, The system comprises an anode gas supply source, a plurality of stacks, and a switching valve, the plurality of stacks and the anode gas supply source and the plurality of stacks are connected by the switching valve; wherein the switching valve is configured to: connect at least one of the plurality of stacks as an upstream stack and at least one of the plurality of stacks as a downstream stack; and switch at least one upstream stack to a downstream stack and / or switch at least one downstream stack to an upstream stack; wherein the upstream stack is a stack that inputs anode gas from an anode gas supply source for reaction, and the downstream stack is a stack that inputs anode gas remaining after reaction discharged by the upstream stack for reaction.

8. The fuel cell anode recycle system of claim 7, wherein the anode exhaust gas is heated by the heat exchanger to a temperature of about 150°C to about 200°C. The switching valve comprises a plurality of input valves connected to the input end of the stack, and a plurality of output valves connected to the output end of the stack, the plurality of output valves are controllably connected to the inlet end of the same water separator, and the plurality of input valves are controllably connected to the outlet end of the water separator.

9. A fuel cell anode recycle system as claimed in claim 7 or 8, characterised in that, The system comprises a nitrogen discharge valve, and the plurality of stacks are connected between the anode gas supply source and the nitrogen discharge valve through a plurality of switching valves, wherein the number of stacks is not less than three, and any two of the stacks can be switched between series connection and parallel connection through the switching valves.

10. A hydrogen-oxygen fuel cell, characterized by comprising: The fuel cell anode circulation system comprises the fuel cell anode circulation system according to any one of claims 7 to 9, wherein the anode gas supplied by the anode gas supply source is hydrogen, and the gas output from the output end of the upstream stack is a mixture of hydrogen, nitrogen and water vapor.

Images