JP2020077569A - Fuel cell system - Google Patents

Abstract

To provide a fuel cell system capable of stabilizing operation of the fuel cell system by preventing liquid such as water as an impurity discharged from the fuel cell system from being frozen.SOLUTION: Introduction piping 32 for introducing fuel off-gas of a fuel cell stack 2 into a gas liquid separator 30 is arranged so as to be tilted downward from the fuel cell stack toward the gas liquid separator. In the gas liquid separator, a discharge passage 33 for discharging liquid from the gas liquid separator and a liquid storage part 34 for storing liquid are formed below a discharge port of the introduction piping. The discharge passage is formed so that the discharge passage is tilted upward from an upstream side to a downstream side in a first posture in which a fuel cell vehicle is tilted from a horizontal posture so as to increase an angle θ2 at which the introduction piping tilts downward and so that the discharge passage is tilted downward from the upstream side to the downstream side in a second posture in which the fuel cell vehicle is tilted from the horizontal posture so as to decrease the angle θ2 at which the introduction piping tilts downward.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a fuel cell system equipped with a gas-liquid separator.

  Conventionally, this type of fuel cell system is mounted on a fuel cell vehicle and separates liquid such as water contained in fuel off-gas discharged from the fuel cell stack, and gas-liquid separation which stores and discharges the liquid. A fuel cell system including a container is used (for example, see Patent Document 1).

JP, 2016-96012, A

  By the way, an introduction pipe for introducing the fuel off gas of the fuel cell stack is connected to the gas-liquid separator as disclosed in Patent Document 1. The gas-liquid separator has a discharge path for separating a liquid such as water contained in the fuel off-gas introduced from the introduction pipe from the fuel off-gas and discharging the separated liquid.

  However, the discharge route is formed in the lower part of the gas-liquid separator in consideration of the drainage property of the liquid, and for example, while the fuel cell vehicle is stopped (specifically, when the power generation of the fuel cell system is stopped), When the liquid flows down from the introduction pipe, the liquid that flows down may stay in the discharge path. If the fuel cell vehicle is exposed to a sub-zero temperature environment in such a state, it is assumed that the accumulated liquid freezes in the discharge path and the exhaust discharge path is blocked when the fuel cell system is restarted. It This may cause malfunction of the fuel cell system, and it takes time to melt the frozen liquid.

  The present invention has been made in view of such a problem, and an object thereof is to prevent the liquid flowing down from the fuel cell system from freezing in the discharge path of the gas-liquid separator. It is to provide a fuel cell system that can stabilize the operation of the fuel cell system.

  To achieve the above object, a fuel cell system according to the present invention is mounted on a fuel cell vehicle, separates a liquid contained in a fuel off gas discharged from a fuel cell stack from the fuel off gas, and separates the separated liquid. A fuel cell system including a gas-liquid separator for storing and discharging, wherein the fuel cell stack is connected with an introduction pipe for introducing the fuel off-gas of the fuel cell stack into the gas-liquid separator. The introduction pipe is arranged to incline downward from the fuel cell stack toward the gas-liquid separator, and the gas-liquid separator is below the discharge port of the introduction pipe. A discharge path for discharging the liquid from the gas-liquid separator and a liquid storage section for storing the liquid are formed on the upstream side of the discharge path. In the first posture in which the fuel cell vehicle is inclined so that the angle of inclination of the pipe downward is increased, the discharge path is inclined upward from the upstream side to the downstream side of the discharge path, and In a second posture in which the fuel cell vehicle is inclined from the horizontal posture so that the angle of the downward inclination of the introduction pipe is reduced, the discharge path is from the upstream side to the downstream side of the discharge path. The discharge path is formed so as to incline downward toward the side.

  According to the fuel cell system of the present invention configured as described above, the liquid such as generated water generated when power is generated in the fuel cell stack is introduced into the gas-liquid separator through the introduction pipe together with the fuel off gas. It The liquid introduced and separated into the gas-liquid separator is stored in the liquid reservoir, and then discharged from the gas-liquid separator via the discharge path formed downstream from the liquid reservoir.

  After the liquid is discharged from the liquid reservoir and the power generation of the fuel cell stack is stopped, when the fuel cell vehicle is in the first posture, the angle of the downward inclination of the introduction pipe increases. The attached liquid easily flows down from the introduction pipe. The liquid that has flowed down from the introduction pipe is stored in the liquid reservoir, and the discharge route downstream of the liquid reservoir is inclined upward from the upstream side to the downstream side, so that the liquid is unlikely to stay in the discharge route. As described above, in the first posture of the fuel cell vehicle, the liquid is unlikely to stay in the discharge path, so that the discharge path can be prevented from being blocked by the freezing of the liquid.

  On the other hand, when the fuel cell vehicle is in the second posture, the angle of the downward inclination of the introduction pipe decreases, so that the liquid attached to the introduction pipe is less likely to flow down from the introduction pipe. On the other hand, since the discharge path is inclined downward from the upstream side to the downstream side, the liquid remaining in the liquid reservoir and the liquid staying in the discharge path are easily discharged from the discharge path. In this way, even in the second position of the fuel cell vehicle, the liquid is unlikely to stay in the discharge path, and therefore the discharge path can be prevented from being blocked by freezing of the liquid.

It is a schematic diagram showing a schematic structure of a fuel cell system according to the present invention. It is a side view which shows the principal part structure of the fuel cell system shown in FIG. FIG. 3 is a schematic cross-sectional view showing a main part configuration of the gas-liquid separator shown in FIGS. 1 and 2, and is a cross-sectional view of the gas-liquid separator in a horizontal position of the fuel cell vehicle. FIG. 4 is a schematic cross-sectional view illustrating a state of the gas-liquid separator shown in FIG. 3 when the fuel cell vehicle is in the first posture. FIG. 4 is a schematic cross-sectional view illustrating the state of the gas-liquid separator shown in FIG. 3 when the fuel cell vehicle is in the second posture.

  Hereinafter, an embodiment of a fuel cell system according to the present invention will be described in detail with reference to FIGS. 1 and 2, the fuel cell stack is schematically illustrated. In FIG. 1, the stack frame is omitted, and in FIG. 2, the oxidizing gas supply system is omitted. In addition, with respect to the fuel cell vehicle (hereinafter referred to as “vehicle”) 100 shown in FIGS. 1 to 5, F is a front direction, B is a rear direction, U is an upward direction, D is a downward direction, L is a left direction, R indicates the right direction.

  The fuel cell system 1 of the present embodiment is a system for supplying driving power, and includes a fuel cell stack 2, a fuel gas supply system 10 for supplying a fuel gas such as hydrogen to the fuel cell stack 2, and a fuel. An oxidant gas supply system 20 for supplying an oxidant gas such as air to the battery stack 2 is provided.

  The fuel cell stack 2 is mounted in the front room F of the vehicle 100. The fuel cell stack 2 has a structure in which a plurality of unit cells are stacked and sandwiched between the end plates 3 and 3 and is housed in a stack case (not shown).

  The one end plate 3 is provided with six openings for supplying and discharging the fuel gas, the oxidant gas, and the refrigerant to the power generation region (not shown) of the stacked single cells.

  In FIG. 1, the opening 3a is a fuel gas supply port, and the opening 3b is a fuel off-gas discharge port after power generation. On the other hand, the opening 3c is a supply port for the oxidant gas, and the opening 3d is a discharge port for the oxidant off gas after power generation. The opening 3e is a cooling refrigerant supply port, and the opening 3f is a cooling refrigerant discharge port.

  As shown in FIG. 2, the fuel cell stack 2 is fixedly housed in the stack frame 2a in the front room S of the vehicle 100. The fuel cell stack 2 is installed so as to incline downward in the vehicle length direction from the front direction F of the vehicle to the rear direction B of the vehicle 100, and its inclination angle is set to θ1.

  That is, the fuel cell stack 2 is installed so as to incline with respect to the horizontal direction so that the vehicle front is higher and the fuel cell stack 2 is lower toward the rear of the vehicle. Therefore, the liquid such as water generated after the chemical reaction in the fuel cell stack 2 is configured to be easily discharged by being collected at the rear of the vehicle by utilizing gravity.

  The oxidant gas supply system 20 supplies, for example, a supply channel 25 for supplying the oxidant gas to (the cathode electrode of) the fuel cell stack 2 and the oxidant off gas after being subjected to an electrochemical reaction in each fuel cell. And a discharge flow path 29 for discharging from the fuel cell stack 2. Each flow path of the oxidant gas supply system 20 can be configured by a pipe such as a rubber hose or a metal pipe.

  An air cleaner 21, a compressor 22, an intercooler 23, etc. are provided below the fuel cell stack 2 from the upstream side in the supply flow path 25, and a muffler (not shown) is provided in the discharge flow path 29.

  In the supply passage 25, the air cleaner 21 removes dust in the oxidant gas (air or the like) taken from the atmosphere. The compressor 22 compresses the oxidant gas introduced through the air cleaner 21, and sends the compressed oxidant gas to the intercooler 23 under pressure.

  The intercooler 23 cools, for example, by heat exchange with a refrigerant and supplies the oxidant gas, which is pumped from the compressor 22 and introduced, to the fuel cell stack 2 (cathode electrode thereof). The supply passage 25 is provided with an inlet valve 27 for blocking the flow of the oxidant gas between the intercooler 23 and the fuel cell stack 2.

  The fuel gas supply system 10 includes a supply source 11 such as a hydrogen tank that stores high-pressure fuel gas such as hydrogen gas, and a supply flow path that supplies the fuel gas from the supply source 11 to (the anode electrode of) the fuel cell stack 2 12 and.

  Further, the fuel gas supply system 10 is branched and connected to the circulation flow path 13 for circulating a part of the fuel off gas (unconsumed fuel gas) discharged from the fuel cell stack 2 to the supply flow path 12, and the circulation flow path 13. And a discharge passage 14 for discharging the fuel off gas in the circulation passage 13 to the outside (released to the atmosphere).

  The supply flow path 25 is provided with a shutoff valve 15, a regulator 16, an injector 17 and the like from the upstream side, and the discharge flow path 14 is provided with a gas-liquid separator 30, a discharge valve 19 and the like from the upstream side for circulation. A pump 18 is provided in the flow path 13. In the present embodiment, the discharge valve 19 is provided below the gas-liquid separator 30.

  In the present embodiment, the gas-liquid separator 30 and the discharge valve 19 are arranged below the fuel cell stack 2 and on the side from which the oxidant off gas is discharged (close to the opening 3d). Thereby, the flow path length of the discharge flow path 14a on the upstream side of the gas-liquid separator 30 can be increased, and the discharge flow path 14a in which the liquid such as generated water is frozen at the time of power generation of the fuel cell system 1 The temperature can be raised by the liquid (generated water) generated during power generation.

  In addition to this, a downstream discharge passage 14b for the fuel offgas can be provided in the vicinity of the discharge passage 29 for the oxidant offgas, and the flow passage length of the downstream discharge passage 14b described later can be shortened. The fuel off gas can be merged with the oxidant off gas discharge passage 29. As a result, it is possible to prevent the liquid from staying in the discharge flow path 14 and to prevent the liquid from freezing.

  In the present embodiment, the pump 18 is arranged near the portion where the circulation flow path 13 joins (returns to) the supply flow path 12. As a result, the pressure loss of the fuel gas in the confluent portion can be reduced, and the heat generation of the pump 18 can prevent the liquid from freezing in this portion.

  A gas-liquid separator 30 is installed in the discharge passage 14, and includes an upstream discharge passage 14a and a downstream discharge passage 14b. The gas-liquid separator 30, which will be described in detail later, has a characteristic configuration according to the present invention, and separates a liquid such as water contained in the fuel off gas discharged from the fuel cell stack 2 and stores the liquid. It has the function of discharging it. Each flow path of the fuel gas supply system 10 can be configured by a pipe such as a rubber hose or a metal pipe.

  Fuel gas such as hydrogen gas with which the supply source 11 is filled passes through the shutoff valve 15, the regulator 16, and the injector 17, and is supplied to the opening 3 a of the fuel cell stack 2. On the other hand, the oxidant gas such as the atmosphere passes through the air cleaner 21, the compressor 22, the intercooler 23, and the inlet valve 27 as described above, and is supplied to the opening 3c of the fuel cell stack 2. The fuel gas and the oxidant gas supplied to the fuel cell stack 2 chemically react with each other, whereby the fuel cell stack 2 generates electricity and is discharged as a fuel off gas and an oxidant off gas.

  The fuel off-gas discharged from the opening 3b is introduced into the gas-liquid separator 30 through the discharge flow passage 14a on the upstream side of the discharge flow passage 14 and separated into gas and liquid such as water. The separated gas is supplied to the pump 18 through the circulation flow path 13. The gas supplied to the pump 18 is pressure-fed to the opening 3 a to which the fuel gas is supplied, merges with the fuel gas supplied from the supply source 11, and is reused in the fuel cell stack 2 for power generation.

  The liquid such as water separated by the gas-liquid separator 30 is discharged to the outside of the system via the discharge flow passage 14b by opening the discharge valve 19 arranged on the downstream side of the gas-liquid separator 30. The oxidant off-gas discharged from the opening 3d is discharged to the outside of the system through the discharge flow path 29. The discharge flow path 14b downstream of the discharge valve 19 joins with the discharge flow path 29 through which the oxidant off-gas is discharged, and the liquid and the like separated by the gas-liquid separator 30 are outside the vehicle 100 together with the oxidant off-gas. Is discharged to.

  Next, the gas-liquid separator 30 used in the fuel cell system 1 of this embodiment will be described in detail with reference to FIG. The gas-liquid separator 30 separates a liquid such as water contained in the fuel off gas discharged from the fuel cell stack 2, and stores and discharges the separated liquid. The gas-liquid separator 30 also has a function of circulating the separated gas, merging it with the fuel gas, and supplying the fuel gas to the fuel cell stack 2.

  The gas-liquid separator 30 is composed of a case 31 composed of an upper case 31a and a lower case 31b, and is an airtight case with an O-ring (not shown) or the like. The upper case 31a is provided with an introduction pipe 32 that forms an exhaust flow path 14b at the upper part, communicates with the opening 3b from which the fuel off gas of the fuel cell stack 2 is exhausted, and after the power is generated in the fuel cell stack 2. The fuel off gas is introduced into the case 31.

  The introduction pipe 32 is the discharge flow passage 14a on the upstream side of the discharge flow passage 14, and is inclined downward from the vehicle front direction F toward the rear direction B. Specifically, the introduction pipe 32 is inclined downward from the fuel cell stack 2 toward the gas-liquid separator 30, and is connected to the gas-liquid separator 30. The introduction pipe 32 is set to have a predetermined inclination angle θ2 with respect to a reference line (horizontal line) L when it is installed in the vehicle 100.

  The gas-liquid separator 30 has a discharge path 33 for discharging the separated liquid such as water below the discharge port 32a of the introduction pipe 32, and the separated liquid is stored on the upstream side of the discharge path 33. A liquid reservoir 34 is formed.

  Specifically, the lower case 31b has a shape that gradually swells downward, and the liquid reservoir 34 is formed in the lowermost recess of the lower case 31b. The discharge path 33 is a through hole that penetrates in a substantially horizontal direction at a position slightly higher than the bottom surface of the liquid reservoir 34 in a horizontal posture of the vehicle 100.

  The through hole as the discharge path 33 extends to the outside of the case 31 and is connected to the discharge valve 19 installed outside the case. Therefore, the fuel off gas discharged from the fuel cell stack 2 through the introduction pipe 32 is introduced into the case 31 of the gas-liquid separator 30 and separated into gas and liquid.

  During operation of the fuel cell system 1, the gas separated by the gas-liquid separator 30 joins the supply passage 12 through the circulation passage 13 from the exhaust hole 35 opening upward from the upper case 31a, and the fuel cell stack is formed. It is supposed to be supplied to 2.

  On the other hand, the liquid separated by the gas-liquid separator 30 is stored in the liquid storage portion 34 of the lower case 31b while the discharge valve 19 is closed during the operation of the fuel cell system 1. When a liquid level sensor (not shown) of the liquid reservoir 34 detects that a predetermined amount of liquid has been stored in the liquid reservoir 34, the drain valve 19 opens, and the stored liquid is drained from the drain path 33. And is discharged to the outside. The exhaust valve 19 remains open even when the fuel cell system 1 is stopped.

  Here, in the horizontal posture of the vehicle 100, as shown in FIG. 3, the component of the liquid flow in the horizontal direction of the discharge path 33 is opposite to the component of the flow of the fuel off-gas in the horizontal direction of the introduction pipe 32. The discharge path 33 is formed at a position having a directional component.

  Specifically, in the discharge path 33, the vehicle 100 tilts so that the angle at which the vehicle 100 tilts downward from the horizontal posture increases (changes from θ2 in FIG. 3 to θ3 in FIG. 4). In the first posture described above, the discharge path 33 is formed so as to incline upward from the upstream side of the discharge path 33 toward the downstream side.

  In addition to this, in the discharge path 33, the vehicle 100 tilts so that the angle at which the vehicle 100 tilts downward from the horizontal posture decreases (changes from θ3 in FIG. 4 to θ4 in FIG. 5). In the second posture, the discharge path 33 is formed so as to incline downward from the upstream side of the discharge path 33 toward the downstream side.

  The operation of the fuel cell system 1 configured as above will be described. First, when the fuel cell system 1 is in operation, the fuel gas is supplied from the opening 3 a of the end plate 3, the oxidant gas is supplied from the opening 3 c of the end plate 3, and a chemical reaction occurs in the fuel cell stack 2 to generate electricity. To be done.

  The fuel off-gas after the reaction is discharged from the opening 3b and introduced into the gas-liquid separator 30 via the introduction pipe 32 forming the discharge flow passage 14a on the upstream side of the discharge flow passage 14. Further, in the fuel cell stack 2, the oxidant off-gas after the reaction is discharged from the opening 3d and discharged to the outside through the discharge flow path 29.

  The fuel off-gas introduced into the gas-liquid separator 30 is separated into a gas and a liquid such as water, and the gas is joined to the supply passage 12 through the circulation passage 13 and used again in the fuel cell stack 2. The liquid separated by the gas-liquid separator 30 is stored in the lower liquid reservoir 34 in the case 31, passes through the discharge valve 33, the discharge valve 19, and the discharge flow path 14 b on the downstream side of the discharge flow path 14. Is discharged to the outside through.

  Since the introduction pipe 32 for introducing the fuel off-gas to the gas-liquid separator 30 is inclined downward with respect to the horizontal at an inclination angle θ2, the liquid component in the fuel off-gas is surely dropped by gravity, and the liquid reservoir part It is stored in 34. The liquid stored in the liquid reservoir 34 is drained to the outside when the discharge valve 19 is opened. As described above, while the fuel cell system 1 is in operation, the liquid separated by the gas-liquid separator 30 is reliably drained to the outside.

  When the fuel cell system 1 is stopped, a slight amount of liquid remains in the discharge flow passage 14a (introduction pipe 32) on the upstream side of the discharge flow passage 14. The small amount of the remaining liquid is gradually dropped and stored in the liquid reservoir 34. Since the through hole of the discharge path 33 is located slightly higher than the bottom surface of the liquid reservoir 34, a small amount of liquid accumulates.

  When the fuel cell system 1 is stopped, the vehicle 100 may tilt from the horizontal state to the first posture. In the present embodiment, as described above, the first posture is such that the gas-liquid separator 30 of the fuel cell system 1 is inclined from the horizontal posture to the downward direction of the introduction pipe 32 as shown in FIG. The posture in which the vehicle 100 is inclined so as to increase, that is, the inclination angle increases to θ3 which is larger than θ2. In the first posture, the discharge path 33 inclines upward from the upstream side to the downstream side, and inclines upward at an angle α1 with respect to the horizontal line L.

  In the first posture, since the inclination angle of the introduction pipe 32 into which the fuel off-gas is introduced into the gas-liquid separator 30 increases from θ2 to θ3, the liquid remaining in the introduction pipe 32 has a steep gradient. The liquid can be easily dropped, and the liquid can be stored in the liquid reservoir 34 (FIG. 4, W1).

  In addition to this, since the discharge path on the downstream side of the liquid reservoir 34 is inclined upward from the upstream side to the downstream side, it is difficult for the liquid to stay in the discharge path 33. As described above, in the first posture of the fuel cell vehicle, since the liquid is unlikely to stay in the discharge path 33, it is possible to prevent the discharge path 33 from being blocked by the freezing of the liquid.

  When the fuel cell system 1 is stopped, the vehicle 100 may tilt from the horizontal state to the second posture. In the present embodiment, as described above, in the second posture, the gas-liquid separator 30 of the fuel cell system 1 has an angle at which the gas pipe separator 30 inclines downward from the horizontal posture as shown in FIG. The posture in which the vehicle 100 is inclined so as to decrease, that is, the inclination angle decreases to θ4 which is smaller than θ2. In this second posture, the discharge path 33 inclines downward from the upstream side to the downstream side and inclines downward at an angle α2 with respect to the horizontal line L.

  In the second posture, the inclination angle of the introduction pipe 32 into which the fuel off-gas is introduced into the gas-liquid separator 30 decreases from θ2 to θ4, so that the liquid attached to the introduction pipe 32 drops from the introduction pipe 32. Disappear.

  On the other hand, since the discharge path is inclined downward from the upstream side to the downstream side, the liquid remaining in the liquid reservoir 34 and the liquid staying in the discharge path 33 are easily discharged from the discharge path 33. As described above, even when the vehicle 100 is in the second posture, the liquid is unlikely to stay in the discharge path 33, so that it is possible to prevent the discharge path 33 from being blocked by freezing of the liquid.

  Although one embodiment of the present invention has been described in detail above, the present invention is not limited to the above embodiment, and various modifications are possible within the scope of the present invention as set forth in the claims. The design can be changed.

  For example, as the liquid separated by the gas-liquid separator, water generated by a chemical reaction during power generation in the fuel cell stack, which is a combination of hydrogen gas as a fuel gas and oxygen gas as an oxidant gas, is discharged. Although the description has been given, it goes without saying that not only water but also a liquid containing impurities mixed in water may be discharged.

1: Fuel cell system, 2: Fuel cell stack, 3: End plate, 10: Fuel gas supply system, 13: Circulation flow path, 14: Discharge flow path, 19: Discharge valve, 20: Oxidant gas supply system, 30 : Gas-liquid separator, 31: Case, 32: Introduction pipe, 33: Discharge route, 34: Liquid reservoir, 100: Fuel cell vehicle (vehicle)

Claims (1)

A fuel cell system mounted on a fuel cell vehicle, comprising a gas-liquid separator for separating a liquid contained in a fuel off-gas discharged from a fuel cell stack from the fuel off-gas, and storing and discharging the separated liquid. There
An introduction pipe for introducing the fuel off-gas of the fuel cell stack into the gas-liquid separator is connected to the fuel cell stack, and the introduction pipe extends from the fuel cell stack to the gas-liquid separator. , It is arranged to incline downward,
The gas-liquid separator has a discharge path for discharging the liquid from the gas-liquid separator below the discharge port of the introduction pipe, and a liquid reservoir for storing the liquid on the upstream side of the discharge path. Part is formed,
In the first posture in which the fuel cell vehicle is inclined from the horizontal posture so that the angle of the downward inclination of the introduction pipe is increased, in the first posture, the discharge path is from the upstream side to the downstream side of the discharge path. Toward the side, tilts upward, and
In the second posture in which the fuel cell vehicle is inclined from the horizontal posture so that the angle of the downward inclination of the introduction pipe is decreased, in the second posture, the discharge path is from the upstream side to the downstream side of the discharge path. The fuel cell system is characterized in that the discharge path is formed so as to incline downward toward the side.

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