JP2010165639A - Fuel cell system, and starting method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To quickly carry out substitution with hydrogen with a simple structure. <P>SOLUTION: A fuel cell system 10 is provided with a fuel cell stack 100, a fuel gas supply part 200 connected to a first side in a stacking direction of the fuel cell stack, a first fuel gas exhaust part 400 connected to a second side contrary to the first side, a second fuel gas exhaust part 500 connected to the first side, and a control part 600 controlling supply and exhaust of fuel gas to and from the fuel cell stack. The control part stops exhaustion of gas from the second fuel gas exhaust part at starting of the fuel cell stack 100, supplies fuel gas from the fuel gas supply part 200, and at the same time, exhausts gas from the first fuel gas exhaust part 400 to substitute gas inside the fuel cell stack with the fuel gas, and, after substitution with the fuel gas, stops exhaustion of gas from the first fuel gas exhaust part 400, and exhausts gas from the second fuel gas exhaust part 500. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel cell system.

  In the fuel cell, when the operation is stopped, hydrogen is not supplied, so the hydrogen on the anode side is replaced with air. A conventional fuel cell is known in which hydrogen is pressurized and filled at startup, and the air in the anode is replaced with hydrogen (Patent Document 1). On the other hand, it is preferable to provide the hydrogen supply port and the exhaust port on the same end plate side from the viewpoints of piping routing and hydrogen reuse.

JP 2003-331888 A

  However, in the conventional fuel cell, when the hydrogen supply port and the exhaust port are provided on the same end plate side, it is difficult to replace the air with hydrogen in a cell close to the end plate opposite to the hydrogen supply port. was there.

  An object of the present invention is to solve at least one of the above-described problems, and to quickly replace hydrogen with a simple configuration.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

[Application Example 1]
A fuel cell system comprising: a fuel cell stack; a fuel gas supply unit connected to a first end of the fuel cell stack in a stacking direction; and the fuel cell stack opposite to the first end A first fuel gas discharge section connected to the second end of the first fuel gas discharge section, a second fuel gas discharge section connected to the first end section, and supply of the fuel gas to the fuel cell stack. A control unit that controls discharge, and the control unit stops discharge of gas from the second fuel gas discharge unit when starting the fuel cell stack, and discharges fuel gas from the fuel gas supply unit. And supplying the gas from the first fuel gas discharge unit to replace the remaining gas in the fuel gas flow path in the fuel cell stack with the fuel gas. After the replacement with the fuel gas, Gas from the fuel gas discharge part of 1 To stop the discharge, to discharge the gas from the second fuel gas discharge portion, the fuel cell system.
According to this application example, replacement with hydrogen can be performed quickly with a simple configuration.

[Application Example 2]
In the fuel cell system according to Application Example 1, the first fuel gas discharge unit includes an exhaust valve that opens at a predetermined pressure or higher and discharges the gas in the fuel cell stack. Fuel cell system.
According to this application example, it is possible to perform replacement with the fuel gas at once using the pressure of the fuel gas.

[Application Example 3]
In the fuel cell system according to Application Example 2, the first fuel gas discharge unit is further connected to a buffer tank that temporarily stores the gas discharged from the exhaust valve, and a downstream side of the buffer tank. A second exhaust valve for exhausting the gas in the buffer tank;
A fuel cell system comprising:
The gas in the fuel cell stack may include fuel gas. According to this application example, the gas in the fuel cell stack can be temporarily stored in the buffer tank and gradually exhausted.

[Application Example 4]
In the fuel cell system according to Application Example 2 or Application Example 3, the fuel gas supply unit includes a fuel tank, and a fuel gas supply pressure adjustment unit disposed between the fuel tank and the fuel cell stack. The control unit causes the fuel gas supply unit to supply the fuel gas at a pressure higher than a supply pressure of the fuel gas during normal operation of the fuel cell system when the fuel cell system is started. Battery system.
According to this application example, it is possible to increase the pressure in the fuel cell stack at the time of startup than during normal operation, and thereafter, it is possible to perform replacement with the fuel gas at once using the pressure of the fuel gas. It becomes.

  The present invention can be realized in various forms. For example, in addition to the fuel cell system, the present invention can be realized in various forms such as a fuel cell system activation method and a fuel cell system control method. .

It is explanatory drawing which shows typically the fuel cell system which concerns on the 1st Example of this invention. It is explanatory drawing which shows typically the fuel cell stack vicinity of a fuel cell system. It is explanatory drawing which shows a mode that the air in a fuel cell stack is substituted by hydrogen. It is explanatory drawing which shows typically the fuel cell system which concerns on a 2nd Example.

[First embodiment]
FIG. 1 is an explanatory view schematically showing a fuel cell system according to a first embodiment of the present invention. The fuel cell system 10 includes a fuel cell stack 100, a fuel gas supply unit 200, an oxidizing gas supply unit 300, a first fuel gas discharge unit 400, a second fuel gas discharge unit 500, and a control unit 600. . For example, it is possible to use hydrogen as the fuel gas and air as the oxidizing gas.

  The fuel cell stack 100 includes end plates 150 and 155, a fuel gas supply manifold 110, a fuel gas discharge manifold 112, an oxidizing gas supply manifold 120, and an oxidizing gas discharge manifold 122. The end plates 150 and 155 are disposed at both ends of the fuel cell stack 100. The fuel gas supply manifold 110 penetrates from the right end plate 155 of the fuel cell stack 100 shown in FIG. 1 to the leftmost power generation unit (not shown), but the left end portion of the fuel cell stack 100. The end plate 150 is not penetrated. The fuel gas discharge manifold 112 penetrates from the right end to the left end of the fuel cell stack 100. The oxidizing gas supply manifold 120 and the oxidizing gas discharge manifold 122 penetrate from the left end of the fuel cell stack 100 to the rightmost power generation unit (not shown), but the right end of the fuel cell stack 100. The end plate 155 is not penetrated.

  The fuel gas supply unit 200 includes a hydrogen tank 210, a pressure reducing valve 220, and a flow rate control valve 230. The hydrogen tank 210 is connected to the fuel gas supply manifold 110 by a pipe 240. The pressure reducing valve 220 and the flow rate control valve 230 are disposed on the pipe 240.

  The oxidizing gas supply unit 300 includes an air intake port 310 and an air pump 320. The air intake 310 is connected to the oxidizing gas supply manifold 120 by a pipe 330. The air pump 320 is disposed on the pipe 330, compresses air, and supplies the compressed air to the fuel cell stack 100. A radiator for cooling the compressed air may be provided on the pipe 330 between the air pump 320 and the fuel cell stack 100.

  The first fuel gas discharge unit 400 includes a first exhaust valve 410, a buffer tank 420, and a second exhaust valve 430. The first exhaust valve 410, the buffer tank 420, and the second exhaust valve 430 are connected to the left side of the fuel gas discharge manifold 112 by a pipe 440. That is, the connection position between the first fuel gas discharge unit 400 and the fuel cell stack 100 is opposite to the connection position between the fuel gas supply unit 200 and the fuel cell stack 100 and the stacking direction of the fuel cell stack 100. .

  The first exhaust valve 410 is opened when the fuel cell system 10 is activated, and is used to discharge the gas in the fuel cell stack 100. The first exhaust valve 410 may be configured as a relief valve that opens at a predetermined pressure value, or may be configured as an on / off valve that opens under the control of the control unit 600. The opening pressure of the relief valve is preferably higher than the pressure inside the fuel cell stack 100 during normal operation of the fuel cell system 10. The buffer tank 420 is used to temporarily store the gas in the fuel cell stack 100 before releasing it to the atmosphere. The second exhaust valve 430 is used to release the gas in the buffer tank 420 to the atmosphere.

  The second fuel gas discharge unit 500 includes a third exhaust valve 510. The third exhaust valve 510 is connected to the right side of the fuel gas discharge manifold 112 by a pipe 520. That is, the connection position of the first fuel gas discharge unit 400 to the fuel cell stack 100 is the same side as the connection position of the fuel gas supply unit 200 and the fuel cell stack 100 and the stacking direction of the fuel cell stack 100. . The third exhaust valve 510 is used for discharging fuel exhaust gas. It is also used for adjusting the pressure in the fuel cell stack 100.

  FIG. 2 is an explanatory diagram schematically showing the vicinity of the fuel cell stack of the fuel cell system. The fuel cell stack 100 includes a plurality of stacked power generation units 130, gas blocking plates 140 and 145, and end plates 150 and 155. Here, among the plurality of power generation units 130, the power generation unit at the left end is referred to as “left end power generation unit 130L”, and the power generation unit at the right end is referred to as “right end power generation unit 130R”.

  The gas cutoff plate 140 is disposed on the left side of the left end power generation unit 130L. The gas blocking plate 140 includes holes 141 to 143 for allowing the fuel gas discharge manifold 112, the oxidizing gas supply manifold 120, and the oxidizing gas discharge manifold 122 to pass therethrough. The gas cutoff plate 145 is disposed on the right side of the right end power generation unit 130R. The gas shut-off plate 145 includes holes 146 and 147 through which the fuel gas supply manifold 110 and the fuel gas discharge manifold 112 pass.

  The end plate 150 is disposed on the left side of the gas blocking plate 140. The end plate 150 includes a hole (not labeled) for allowing the fuel gas discharge manifold 112, the oxidizing gas supply manifold 120, and the oxidizing gas discharge manifold 122 to pass through. The end plate 160 is disposed on the right side of the gas blocking plate 145. The end plate 160 includes a fuel gas supply manifold 110 and a hole (not labeled) for passing through the fuel gas discharge manifold 112. In FIG. 2, the fuel cell stack 100 includes the gas blocking plates 140 and 145 and the end plates 150 and 155 separately, but does not include the gas blocking plates 140 and 145, and the end plates 150 and 155 The functions of the gas blocking plates 140 and 145 may also be used.

  An operation at startup of the fuel cell system 10 will be described. First, the control unit 600 closes the flow control valve 230, the second exhaust valve 430, and the third exhaust valve 510. Further, the control unit 600 sets the pressure of the pressure reducing valve 220 to the charging pressure Pa at the time of activation. Further, the valve opening pressure Pc at which the first exhaust valve 410 opens is set in advance to a pressure higher than the pressure Pb during normal operation of the fuel cell system 10.

Here, the pressures Pa, Pb, and Pc only need to satisfy a relationship of Pa >>Pc> Pb. For example, using the ratio of the sum Va of the fuel gas supply side pipe 240 and the anode internal volume of the fuel cell stack 100 to the sum Vb of the volume of the fuel gas discharge side pipe 440 and the volume of the buffer tank 420 is used. The filling pressure Pa may be determined. At the time of startup, the pressure inside the fuel cell stack 100, the pipes 240 and 440, and the buffer tank 420 is atmospheric pressure (1 atm). The gas equation of state at this time is
PV = 1 · (Va + Vb) = nRT (1)
It is. When this is pushed into the piping 440 and the buffer tank 420 on the fuel gas discharge side, the volume becomes Vb. If the pressure at this time is Px, the equation of state of the gas is
Px · Vb = nRT (2)
It becomes. Therefore, from Equation (1) and Equation (2),
Px = (Va + Vb) / Vb (3)
It becomes. Therefore, the filling pressure Pa is
Pa ≧ Px = (Va + Vb) / Vb (4)
You may set so that it may satisfy | fill. In this way, the inside of the fuel cell stack 100 can be replaced with hydrogen. Conversely, after determining the filling pressure Pa, the capacity of the buffer tank 420 may be determined using the value of the filling pressure Pa. This can be done by solving equation (3) for Vb,
Vb = Va / (Pa-1) (5)
It becomes. The size of the buffer tank 420 may be a size obtained by subtracting the volume of the piping 440 on the fuel gas discharge side from Vb. From this result, it is possible to reduce the size of the buffer tank 420 by increasing the filling pressure Pa.

  When the control unit 600 opens the flow control valve 230, hydrogen in the hydrogen tank 210 flows into the fuel cell stack 100 and increases the pressure in the fuel cell stack 100. When the pressure in the fuel cell stack 100 rises to the valve opening pressure Pc of the first exhaust valve 410, the first exhaust valve 410 opens. The pressure inside the fuel cell stack 100 is larger than the pressure inside the buffer tank 420 (atmospheric pressure). Accordingly, when the first exhaust valve 410 is opened, the anode flow path (the fuel gas supply manifold 110, the fuel gas discharge manifold 112, and the power generation unit 130 in the fuel cell stack 100 while the operation of the fuel cell system 10 is stopped). The air accumulated in the fuel gas flow path (not shown) flows into the buffer tank 420 together with the hydrogen supplied from the hydrogen tank 210. Thereby, the anode flow path in the fuel cell stack 100 is replaced with hydrogen. Note that by setting the valve opening pressure Pc of the first exhaust valve large, it is possible to replace the inside of the fuel cell stack 100 with hydrogen all at once. Thereby, at the time of start-up, it becomes possible to suppress the oxidation of the catalyst-supporting carbon of the catalyst layer generated by the coexistence of air and hydrogen, and to suppress the deterioration of the catalyst layer.

  When the pressure of the anode flow path in the fuel cell stack 100 rises to the filling pressure Pa, the control unit 600 closes the first exhaust valve 410 and changes the set pressure of the pressure reducing valve 220 to that during normal operation of the fuel cell system 10. Set to pressure Pb. Thereafter, the controller 600 opens the third exhaust valve 510, operates the air pump 320 to supply air to the fuel cell stack 100, and causes the fuel cell system 10 to operate normally.

  FIG. 3 is an explanatory diagram showing how the air in the fuel cell stack is replaced with hydrogen. In FIG. 3, the description of the first exhaust valve 410 is omitted. In this embodiment, since the hydrogen discharge direction at the time of startup is opposite to the hydrogen discharge direction at the time of startup, as shown in FIGS. 3 (a) to 3 (e), the fuel cell stack 100 is moved from the upper right to the lower left. On the other hand, air is replaced with hydrogen. Therefore, it is difficult to produce a power generation unit in which hydrogen is not easily replaced.

  Further, if a relief valve is used as the first exhaust valve 410, it opens when the pressure in the fuel cell stack 100 reaches the valve opening pressure Pc of the first exhaust valve 410. Therefore, it is possible to replace the valve opening pressure Pc with hydrogen at once by using the difference between the valve opening pressure Pc and the local pressure (approximately atmospheric pressure) of the buffer tank 420.

  Note that, as shown in FIG. 3, when the air remaining in the fuel cell stack 100 is replaced with hydrogen, part of the hydrogen may flow out from the pipe 440. In this embodiment, since the buffer tank 420 is provided, the hydrogen that has flowed out can be recovered in the buffer tank 420. Note that this hydrogen can be gradually released into the atmosphere by opening the second exhaust valve 430.

[Second Embodiment]
FIG. 4 is an explanatory view schematically showing a fuel cell system according to the second embodiment. In the second embodiment, a circulation pump 700 is provided between the pipe 240 of the fuel gas supply unit 200 and the pipe 520 of the second fuel gas discharge unit 500. Circulation pump 700 sends the hydrogen discharged to second fuel gas discharge unit 500 to fuel gas supply unit 200 during normal operation. This makes it possible to efficiently use hydrogen during normal operation. When the hydrogen purge shown in FIG. 4 is performed, the circulation pump 700 is stopped, thereby preventing the circulation of hydrogen. If necessary, on / off valves may be provided before and after the circulation pump 700 to control the presence or absence of hydrogen circulation. The present invention can be applied even to such a system that circulates hydrogen gas.

  In the above description, the fuel cell system 10 including the buffer tank 420 has been described as an example, but the buffer tank 420 may be omitted.

  In this embodiment, the hydrogen filling pressure at the time of startup is set higher than the supply pressure at the time of normal operation, but the hydrogen filling pressure at the time of startup may be the same as the supply pressure at the time of normal operation. . Even if the supply pressure of hydrogen at the time of startup is the same as the supply pressure during normal operation, the first fuel gas discharge unit is connected to the side opposite to the fuel gas supply unit, and the second fuel gas discharge unit If connected to the same side as the fuel gas supply unit, the air in the fuel cell stack 100 can be easily replaced with hydrogen.

  The embodiments of the present invention have been described above based on some examples. However, the above-described embodiments of the present invention are for facilitating the understanding of the present invention and limit the present invention. It is not a thing. The present invention can be changed and improved without departing from the spirit and scope of the claims, and it is needless to say that the present invention includes equivalents thereof.

DESCRIPTION OF SYMBOLS 10 ... Fuel cell system 100 ... Fuel cell stack 110 ... Fuel gas supply manifold 112 ... Fuel gas discharge manifold 120 ... Oxidation gas supply manifold 122 ... Oxidation gas discharge manifold 130 ... Power generation unit 130L ... Power generation unit 130R ... Power generation unit 140 ... Gas cutoff Plates 141 to 143, 146, 147 ... holes 145 ... gas blocking plate 150 ... end plate 160 ... end plate 200 ... fuel gas supply unit 210 ... hydrogen tank 210 ... high pressure hydrogen tank 220 ... pressure reducing valve 230 ... flow rate control valve 240 ... piping DESCRIPTION OF SYMBOLS 300 ... Oxidizing gas supply part 310 ... Air intake 320 ... Air pump 330 ... Piping 400 ... 1st fuel gas discharge part 410 ... 1st exhaust valve 420 ... Buffer tank 430 ... 2nd exhaust valve 440 ... Piping 50 ... second fuel gas discharge portion 510 ... third exhaust valves 520 ... pipe 600 ... control unit 700 ... circulation pump

Claims (7)

A fuel cell system,
A fuel cell stack;
A fuel gas supply unit connected to a first end of the fuel cell stack in the stacking direction;
A first fuel gas exhaust connected to a second end of the fuel cell stack opposite the first end;
A second fuel gas exhaust connected to the first end;
A control unit for controlling supply and discharge of the fuel gas to the fuel cell stack;
With
The controller is
When starting the fuel cell stack, the gas discharge from the second fuel gas discharge unit is stopped, the fuel gas is supplied from the fuel gas supply unit, and the gas is discharged from the first fuel gas discharge unit. And replacing the residual gas in the fuel gas flow path in the fuel cell stack with the fuel gas,
After the replacement with the fuel gas, the gas discharge from the first fuel gas discharge unit is stopped and the gas is discharged from the second fuel gas discharge unit.
Fuel cell system. The fuel cell system according to claim 1, wherein
The first fuel gas discharge unit is a fuel cell system including an exhaust valve that opens at a predetermined pressure or more and discharges gas in the fuel cell stack. The fuel cell system according to claim 2, wherein
The first fuel gas discharge unit further includes:
A buffer tank for temporarily storing the gas discharged from the exhaust valve;
A second exhaust valve connected to the downstream side of the buffer tank for exhausting the gas in the buffer tank;
A fuel cell system comprising: The fuel cell system according to claim 2 or claim 3,
The fuel gas supply unit
A fuel tank,
A fuel gas supply pressure adjusting unit disposed between the fuel tank and the fuel cell stack;
With
The control unit causes the fuel gas supply unit to supply the fuel gas at a pressure higher than a supply pressure of the fuel gas during normal operation of the fuel cell system when the fuel cell system is started. system. A method for starting a fuel cell system, comprising:
(A) When starting the fuel cell stack, supply fuel gas from the first end in the stacking direction of the fuel cell stack from the fuel tank;
(B) Replacement with fuel gas while discharging the gas in the fuel cell stack from the first fuel gas discharge portion connected to the second end portion of the fuel cell stack opposite to the first end portion And
(C) After the replacement with the fuel gas, the discharge of the gas from the first fuel gas discharge unit is stopped, and the gas is discharged from the second fuel gas discharge unit connected to the first end, How to start a fuel cell system. In the starting method of the fuel cell system according to claim 5,
In the step (a), the fuel gas is supplied at a pressure higher than the pressure during normal operation,
In the step (b), when the pressure in the fuel cell stack becomes equal to or higher than a predetermined pressure, the fuel cell discharges the gas in the fuel cell stack from the first fuel gas discharge unit. How to start the system. In the starting method of the fuel cell system according to claim 6,
In the step (b), the gas in the fuel cell stack is stored in a buffer tank, and after switching to the step (c), the gas is gradually exhausted from the buffer tank. starting method.

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