JP2013127295A - Gas consumption system with high pressure container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the available amount of gas while suppressing buckling of a pressure container.SOLUTION: This gas consumption system with a high pressure container includes: a hydrogen tank 2 having a resin liner 21 filled with high pressure hydrogen inside, and a reinforcing body 22 surrounding the liner 21; a fuel cell stack 1 consuming hydrogen filled in the hydrogen tank 2; a pressure sensor 8 for detecting pressure in the liner 21; and an output limiting section 31 setting the consumption upper limit value of hydrogen consumable in the fuel cell stack 1. The output limiting section 31 sets the consumption upper limit value to the maximum consumption which is the amount of hydrogen consumed at the maximum output of the fuel cell stack 1 when the tank internal pressure detected by the pressure sensor 8 is higher than a preset limit starting pressure value, sets the consumption upper limit value to the consumption smaller than the maximum consumption when the tank internal pressure is reduced to the limit starting pressure value or lower, and sets the consumption upper limit value to the gradually smaller consumption as the tank internal pressure becomes lower.

Description

  The present invention relates to a gas consumption system with a high-pressure container.

In a fuel cell system mounted on a fuel cell vehicle, a high-pressure hydrogen tank filled with hydrogen as fuel for the fuel cell is mounted on the vehicle.
In such a vehicle, each mounted device is required to be reduced in weight, and as a high-pressure hydrogen tank for the purpose of reducing the weight, a liner formed of a resin that does not easily transmit hydrogen and a fiber provided so as to surround the liner. What is comprised from the reinforcement body formed with the reinforcement material is known.

  In this high-pressure hydrogen tank, when the tank is filled with a large amount of hydrogen and is in a high-pressure state, hydrogen with a low molecular weight permeates the liner and remains between the liner and the reinforcing body. When the pressure of hydrogen is abruptly reduced, the hydrogen remaining between the liner and the reinforcing body expands, and a phenomenon called buckling that deforms the liner to the inside of the tank may occur.

As a measure for preventing this buckling, as shown in FIG. 7, when the pressure in the tank drops to a specified pressure value Pa, the supply of hydrogen is stopped (the fuel cell output is set to “0”). A technique for preventing the pressure in the tank from falling below the prescribed pressure value Pa is known (hereinafter referred to as a first preventive measure).
Here, the prescribed pressure value Pa is, as shown in FIG. 8A, the gas pressure in the tank (tank pressure) is the pressure of the gas remaining between the liner and the reinforcing body (residual gas pressure). The pressure value Pa in the tank when the pressure difference ΔP reaches the threshold value ΔPlim and buckling starts to occur. FIG. 8B is a time chart of the upper limit value of the amount of hydrogen that can be consumed by the fuel cell. The upper limit value of the consumption amount is the maximum output of the fuel cell until the pressure in the tank reaches the pressure value Pa. When the pressure in the tank reaches the pressure value Pa, the consumption upper limit value is set to “0” thereafter.

  As another preventive measure, as disclosed in Patent Document 1, by forming a synthetic rubber barrier layer having low hydrogen permeability inside the liner, the amount of hydrogen permeation is reduced and the liner is reinforced. A technique for reducing hydrogen remaining between bodies is known (hereinafter referred to as a second prevention measure).

JP 2002-188794 A

However, in the case of the first preventive measure, since the specified pressure remains in the high-pressure hydrogen tank, the amount of hydrogen that can be used in the fuel cell is reduced, and in the case of a fuel cell vehicle, the cruising distance is reduced. There is a problem that the product becomes shorter and the merchantability is lowered.
In the case of the second preventive measure, since a barrier layer is added, the number of parts of the high-pressure hydrogen tank is increased, the productivity is deteriorated, and there is a problem that the cost is increased.

  Therefore, the present invention provides a gas consuming system with a high-pressure vessel that can increase the amount of usable hydrogen while suppressing buckling with a simple configuration.

In the gas consumption system with a high-pressure container according to the present invention, the following means are adopted in order to solve the above problems.
The invention according to claim 1 is a resin container main body (for example, a liner 21 in an embodiment described later) filled with a high-pressure gas and a reinforcing body (for example, in an embodiment described later) surrounding the container main body. A high-pressure vessel (for example, a hydrogen tank 2 in an embodiment to be described later) having a reinforcing body 22) and a gas consuming device (for example, a fuel cell stack 1 in an embodiment to be described later) that consumes the gas filled in the high-pressure vessel. ), Pressure detection means for detecting the pressure in the container body (for example, a pressure sensor 8 in an embodiment described later), and a gas consumption amount for setting an upper limit value of the consumption amount of the gas that can be consumed by the gas consumption device Upper limit value setting means (for example, output limiting unit 31 in the embodiment described later), and the gas consumption upper limit value setting means is detected by the pressure detection means. When the detected pressure is larger than a preset limit start pressure value, the consumption upper limit value is set to a maximum consumption amount that is a gas amount consumed at the maximum load of the gas consuming device, and the detected pressure is set to the limit. When the pressure drops below a starting pressure value, the consumption upper limit value is set to a consumption amount smaller than the maximum consumption amount, and the consumption amount is gradually reduced as the detected pressure decreases. It is a gas consumption system with a container.

  The invention according to claim 2 is detected by the temperature detection means (for example, temperature sensor 10 in an embodiment described later) and the temperature detection means for detecting the temperature inside the high-pressure vessel in the invention according to claim 1. And a correction means for correcting the limit start pressure value to a larger value when the detected temperature is higher than when the detected temperature is low.

  The invention according to claim 3 is the invention according to claim 1 or 2, wherein the gas consuming device is a fuel cell mounted on a vehicle, and is completed on the vehicle. .

  According to the first aspect of the present invention, when the pressure in the high-pressure vessel drops below the limit start pressure value, the consumption upper limit value is set to a consumption amount smaller than the maximum consumption amount, and the pressure in the high-pressure vessel is set. Since the upper limit value of consumption is gradually set to a smaller consumption amount as the value becomes smaller, buckling that deforms the container body inward can be suppressed, and the dying that becomes unusable in the gas contained in the high-pressure vessel The amount can be reduced, i.e. the amount of usable gas can be increased.

  According to the second aspect of the present invention, the resin container body has such characteristics that the higher the temperature, the lower the mechanical strength and the easier the buckling. Therefore, the higher the temperature in the high-pressure container, the higher the restriction start pressure value. By correcting to a large value, buckling can be reliably suppressed regardless of the temperature in the high-pressure vessel.

  According to the third aspect of the present invention, it is possible to reduce the remaining amount of gas in the high-pressure vessel and increase the amount of usable gas with only the devices and means in the vehicle. Can be extended.

It is a schematic block diagram of the gas consumption system with a high pressure container concerning this invention. (A) is a figure which shows the change of the pressure in a tank and the residual gas pressure in the gas consumption system with a high pressure container which concerns on this invention, (B) is the consumption upper limit in the gas consumption system with a high pressure container which concerns on this invention It is a time chart. It is the figure which compared the change (A) of the consumption upper limit in the gas consumption system with a high pressure container which concerns on this invention, and the change (B) of the consumption upper limit in a prior art. It is a figure which shows the one-dimensional model of gas permeation theory. It is a figure which shows the gas pressure distribution in a liner and a reinforcement body when the gas is fully filled in the high pressure vessel. It is a figure explaining the case where the output restriction start pressure is corrected according to the temperature in the tank. It is a figure which shows the change of the consumption upper limit of the fuel cell in a prior art. (A) is a figure which shows the change of the tank internal pressure in a prior art, and a residual gas pressure, (B) is a time chart of the consumption upper limit in a prior art.

Embodiments of a gas consuming system with a high pressure container according to the present invention will be described below with reference to the drawings of FIGS.
FIG. 1 is a schematic configuration diagram of a gas consuming system with a high-pressure vessel. In this embodiment, the fuel cell system is mounted on a fuel cell vehicle and supplies power to a motor or the like as a drive source.

The fuel cell system has all the components mounted on the vehicle and is completed on the vehicle.
As shown in FIG. 1, a fuel cell system includes a hydrogen tank (high pressure vessel) 2 filled with high-pressure hydrogen as a high-pressure gas, and a fuel cell stack that consumes hydrogen that is a gas filled in the hydrogen tank 2. (Gas consumption device) 1.

  The fuel cell stack 1 is a fuel cell that generates electricity by being supplied with hydrogen as fuel and oxygen as oxidant. The fuel cell stack 1 is, for example, a polymer electrolyte fuel cell (PEFC), and includes a plurality of single cells in which an MEA (Membrane Electrode Assembly) is sandwiched between separators (not shown). It is configured by stacking.

  The hydrogen tank 2 has a substantially hemispherical cylindrical shape at both ends in the longitudinal direction, the liner 21 that is disposed inside the tank and forms the container body, and the reinforcing body 22 that is disposed so as to surround the outer surface of the liner 21. It consists of and. The liner 21 is made of a high-density resin that is lightweight and has high mechanical strength and low hydrogen permeability, such as high-density polyethylene and polyamide resin. The reinforcing body 22 reinforces the liner 21 to increase the mechanical strength, and is made of fiber reinforced plastic, for example, carbon fiber reinforced plastic (abbreviated as CFRP).

  A main stop valve 4 is attached to an opening 2 a at one end in the longitudinal direction of the hydrogen tank 2, and the opening 2 a is closed by the main stop valve 4. The main stop valve 4 functions as a filling valve that opens when the hydrogen tank 2 is filled with hydrogen, and the supply that opens when the hydrogen filled in the hydrogen tank 2 is supplied to the fuel cell stack 1. The control device 30 is controlled to switch to the flow path corresponding to the function.

  Hydrogen discharged from the main stop valve 4 of the hydrogen tank 2 is adjusted to a predetermined pressure and supplied to the fuel cell stack 1 through a hydrogen supply passage (gas supply passage) 3 and air (not shown) Air containing oxygen is supplied through the supply device at a predetermined pressure and a predetermined flow rate.

  The hydrogen supply flow path 3 is provided with a pressure reducing valve 5, a relief valve 6, and an intermediate pressure device 7 from the upstream side. High-pressure (for example, 35 MPa or 70 MPa) hydrogen released from the main stop valve 4 of the hydrogen tank 2 is reduced to a predetermined pressure (for example, 1 MP or less) by the pressure reducing valve 5 and supplied to the intermediate pressure device 7. . Here, the medium pressure device 7 is a general term for devices arranged between the pressure reducing valve 5 and the fuel cell stack 1, and includes an ejector, an injector, and the like. The ejector is a device that returns the hydrogen off gas to the hydrogen supply flow path 3 again in order to circulate and use the hydrogen off gas discharged from the fuel cell stack 1, and the injector is a device that adjusts the flow rate of hydrogen supplied to the fuel cell stack 1. is there. Further, when it is desired to humidify the hydrogen supplied to the fuel cell stack 1, the humidifier may also be disposed as the intermediate pressure device 7. Which device is incorporated as the intermediate pressure device 7 is determined by the overall configuration of the fuel cell system.

  In the hydrogen supply flow path 3, a pressure sensor 8 and a temperature sensor 10 are provided upstream of the pressure reducing valve 5, and a pressure sensor 9 is provided between the pressure reducing valve 5 and the relief valve 6. The pressure detected by the pressure sensor 8 substantially matches the pressure in the hydrogen tank 2. Therefore, the pressure sensor 8 can be said to be a pressure detection means for detecting the pressure in the hydrogen tank 2. Further, the temperature detected by the temperature sensor 10 substantially matches the temperature in the hydrogen tank 2. Therefore, the temperature sensor 10 can be said to be temperature detection means for detecting the temperature in the hydrogen tank 2. Note that the pressure sensor 8 and the temperature sensor 10 may be disposed on the main stop valve 4 so as to directly detect the pressure and temperature in the hydrogen tank 2. These sensors 8, 9 and 10 output an electrical signal corresponding to the detected pressure value and temperature value to the control device 30.

  The output (power generation amount) of the fuel cell stack 1 is controlled by the control device 30 based on the load amount (mainly the depression amount of the accelerator pedal) required from the vehicle. The control device 30 includes an output limiting unit 31 that limits the output of the fuel cell stack 1. Since the output of the fuel cell stack 1 has a correlation with the amount of hydrogen consumed for power generation, the output limiting unit 31 sets “the gas that sets the upper limit value of the amount of hydrogen that can be consumed by the fuel cell stack 1”. It can be said that "consumption upper limit setting means".

  Next, the output restriction control of the fuel cell stack 1 performed in the output restriction unit 31 of the control device 30 will be described. In the following description, the output limit of the fuel cell stack 1 is replaced with “limit of the upper limit value of hydrogen that can be consumed by the fuel cell stack 1”.

As described above, the hydrogen tank 2 is composed of the resin liner 21 and the CFRP reinforcement 22, and the liner 21 has a low hydrogen permeability, but does not completely seal the hydrogen. Can not. Therefore, the high-pressure hydrogen filled in the hydrogen tank 2 slightly passes through the liner 21 and remains between the liner and the reinforcing body 22. Hereinafter, the gas (hydrogen) remaining between the liner and the reinforcing body 22 is referred to as residual gas. In addition, since the reinforcing body 22 is also low in hydrogen permeability, hydrogen cannot be completely sealed, so that the residual gas permeates the reinforcing body 22 and is gradually released to the atmosphere.
Here, when the pressure P in the hydrogen tank 2 (hereinafter also referred to as tank internal pressure) P becomes lower than the residual gas pressure (hereinafter referred to as residual gas pressure) Pr, and the pressure difference ΔP exceeds the threshold value ΔPlim. A so-called buckling phenomenon occurs in which the liner 21 is deformed inward.

  Conventionally, as shown in FIG. 8, until the pressure difference ΔP exceeds the threshold value ΔPlim, the gas consumption upper limit value Glim is changed to the maximum consumption Gmax that is the amount of hydrogen consumed at the maximum output of the fuel cell stack 1. When the pressure difference ΔP exceeds the threshold value ΔPlim (when the tank pressure P becomes Pa), the gas consumption upper limit Glim is limited to “0” at once. That is, the supply of hydrogen was stopped. However, if the gas consumption upper limit value Glim is controlled in this way, the amount of hydrogen that is stored in the hydrogen tank 2 and cannot be used, that is, the dead amount of hydrogen increases, and the cruising distance of the fuel cell vehicle increases. It will be shorter.

  Therefore, in the fuel cell system of this embodiment, as shown in FIG. 2, when the tank internal pressure P is larger than the residual gas pressure Pr, there is no possibility of buckling, so the gas consumption upper limit Glim is When the maximum consumption Gmax of the fuel cell stack 1 is set to be substantially unlimited, when the tank internal pressure P drops below the residual gas pressure Pr, the consumption upper limit Glim is less than the maximum consumption Gmax. When the pressure difference ΔP between the tank internal pressure P and the residual gas pressure Pr becomes the threshold value ΔPlim, the consumption upper limit value Glim is set to the amount. Change it to “0”. In this embodiment, the consumption upper limit Glim is reduced linearly as the tank pressure P decreases.

By controlling the consumption upper limit Glim in this way, the rate of decrease of the tank pressure P after the tank pressure P becomes less than or equal to the residual gas pressure Pr can be reduced. The time required for the pressure difference ΔP with respect to the pressure Pr to reach the threshold value ΔPlim can be made longer than before. As a result, as shown in FIG. 2, the pressure Pb in the tank when the pressure difference ΔP becomes the threshold value ΔPlim can be made lower than before (Pb <Pa), and the dead fuel amount of hydrogen can be reduced. The cruising distance of the battery vehicle can be extended as compared with the conventional case.
FIG. 3 is a diagram for explaining that the control of the consumption upper limit value Glim of this embodiment increases the amount of usable hydrogen compared to the conventional control of the consumption upper limit value Glim, and FIG. ) Shows the case of this embodiment, and FIG. 3B shows the conventional case.

As described above, in this embodiment, when the tank internal pressure P coincides with the residual gas pressure Pr, it becomes a starting point of control for limiting the consumption upper limit Glim to a value smaller than the maximum consumption Gmax.
The limit start pressure value Ps that is the tank internal pressure at the control start point can be determined as follows.
FIG. 4 is a diagram showing a first-order model of the gas permeation theory. The primary model is a model in which a gas having a pressure P1 is accommodated in one chamber and a gas having a pressure P2 is accommodated in the other chamber with a gas-permeable flat sample interposed therebetween. When the permeation coefficient of the flat plate sample is k, the thickness of the flat plate sample, that is, the diffusion distance is L, and the permeation area of the flat plate sample is A, the gas permeation amount Q can be obtained from the equation [Equation 1].

  By the way, when the gas (hydrogen) is fully filled in the hydrogen tank 2 and the gas diffuses into the liner 21 and the reinforcing body 22 to reach an equilibrium state, it remains between the liner 21 and the reinforcing body 22. The gas pressure, that is, the residual gas pressure Pr becomes the highest. When the tank internal pressure P decreases from this state and falls below the residual gas pressure Pr, the situation in which buckling is most likely to occur occurs. Therefore, limiting the internal pressure P (= residual gas pressure Pr) when the hydrogen tank 2 is fully filled with gas (hydrogen) and the gas diffuses into the liner 21 and the reinforcing body 22 to reach an equilibrium state. The pressure value Ps is preferable.

FIG. 5 is a view showing gas pressure distributions in the liner 21 and the reinforcing body 22 when the hydrogen tank 2 is fully filled with gas. In this case, the gas pressure on the inner surface of the liner 21 (inside the tank) is the gas pressure at full filling, that is, the maximum working pressure P0 of the hydrogen tank 2, and the gas pressure on the outer surface of the reinforcing body 22 (outside of the tank) is the atmospheric pressure Patm. is there.
Here, the gas permeability coefficient of the liner 21 is k1, the thickness is L1, the gas permeability coefficient of the reinforcing body 22 is k2, and the thickness is L2. When the gas diffusion is in an equilibrium state, the permeation amount Q1 of the gas passing through the liner 21 and the permeation amount Q2 of the gas passing through the reinforcing body 22 are equal (Q1 = Q2). To establish.

  From this, the residual gas pressure Pr when the gas diffuses into the liner 21 and the reinforcing body 22 to reach an equilibrium state can be obtained from [Equation 3].

  When the residual gas pressure Pr thus obtained is set as the restriction start pressure value Ps, the buckling of the liner 21 can be reliably suppressed.

Further, it is known that the resin such as polyethylene and polyamide resin used for the liner 21 has a lower longitudinal elastic modulus as the temperature is higher, and an environment in which buckling is more likely to occur as the longitudinal elastic modulus of the liner 21 decreases. It becomes.
Therefore, the temperature sensor 10 detects the temperature in the hydrogen tank 2 and corrects the limit start pressure value Ps to a higher value as the detected temperature in the hydrogen tank 2 is higher, as shown in FIG. Is preferred. As described above, when the restriction start pressure value Ps is corrected according to the temperature in the hydrogen tank 2, when the temperature in the hydrogen tank 2 is high, the restriction control of the consumption upper limit value Glim is started earlier than when the temperature is low. Therefore, buckling can be reliably suppressed regardless of the temperature in the hydrogen tank 2.
In this case, the control device 30 is provided with correction means for correcting the restriction start pressure value Ps to a higher value as the temperature in the hydrogen tank 2 is higher. However, the correction means is not essential, and the present invention can be realized without the correction means.

[Other Examples]
The present invention is not limited to the embodiments described above.
For example, the gas consuming device is not limited to a fuel cell, and the high-pressure gas is not limited to hydrogen. A gas consuming apparatus that consumes gas other than hydrogen may be used.
Further, when the gas consuming device is a fuel cell, the gas consuming device is not limited to a vehicle, and may be a stationary fuel cell and a stationary hydrogen tank.

1 Fuel cell stack (gas consumption device)
2 Hydrogen tank (high pressure vessel)
8 Pressure sensor (pressure detection means)
10 Temperature sensor (temperature detection means)
21 Liner (container body)
22 Reinforcing body 30 Control device 31 Output limiting unit (gas consumption upper limit setting means)

In addition, it is known that the strength of the resin such as polyethylene or polyamide resin used for the liner 21 decreases as the temperature increases, and an environment in which buckling easily occurs as the strength of the liner 21 decreases.
Therefore, the temperature sensor 10 detects the temperature in the hydrogen tank 2 and corrects the limit start pressure value Ps to a higher value as the detected temperature in the hydrogen tank 2 is higher, as shown in FIG. Is preferred. As described above, when the restriction start pressure value Ps is corrected according to the temperature in the hydrogen tank 2, when the temperature in the hydrogen tank 2 is high, the restriction control of the consumption upper limit value Glim is started earlier than when the temperature is low. Therefore, buckling can be reliably suppressed regardless of the temperature in the hydrogen tank 2.
In this case, the control device 30 is provided with correction means for correcting the restriction start pressure value Ps to a higher value as the temperature in the hydrogen tank 2 is higher. However, the correction means is not essential, and the present invention can be realized without the correction means.

Claims (3)

A resin-made container main body filled with a high-pressure gas inside, and a high-pressure container having a reinforcing body surrounding the container main body;
A gas consuming device for consuming the gas filled in the high pressure vessel;
Pressure detecting means for detecting the pressure in the container body;
Gas consumption upper limit value setting means for setting an upper limit value of consumption of the gas that can be consumed by the gas consuming device;
With
The gas consumption upper limit setting means consumes the consumption upper limit value at the maximum load of the gas consuming device when the detected pressure detected by the pressure detection means is larger than a preset limit start pressure value. When the detected pressure drops below the limit start pressure value, the consumption upper limit value is set to a consumption amount smaller than the maximum consumption amount, and the detected pressure The gas consumption system with a high-pressure container is characterized in that the consumption is gradually reduced as the value becomes smaller. Temperature detecting means for detecting the temperature in the high-pressure vessel;
Correction means for correcting the restriction start pressure value to a larger value when the detected temperature detected by the temperature detecting means is higher than when the detected temperature is low;
The gas consumption system with a high-pressure vessel according to claim 1, further comprising:   The gas consuming system with a high-pressure container according to claim 1 or 2, wherein the gas consuming device is a fuel cell mounted on a vehicle and is completed on the vehicle.

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