JP5324071B2 - Fuel cell system - Google Patents

Description

  The present invention relates to a fuel cell system that generates power using liquid fuel.

As a conventional fuel cell system, one that generates a reformed gas using a liquid fuel in a reformer and generates electric power using the reformed gas in a fuel cell is known (see, for example, Patent Document 1).
JP 2006-240952 A

  However, in the fuel cell system as described above, for example, when the reformed gas is generated by steam reforming of the liquid fuel, it is necessary to mix the liquid fuel and water. If the pressure is high, this water may flow back into the liquid fuel line. Therefore, there is a problem that the equipment provided in the liquid fuel line is damaged by the backflowed water (foreign matter).

  Therefore, an object of the present invention is to provide a fuel cell system that can prevent equipment from being damaged by foreign matters mixed in liquid fuel flowing backward through the liquid fuel line.

  In order to solve the above problems, a fuel cell system according to the present invention is a fuel cell system that generates a reformed gas using a liquid fuel in a reformer and generates electric power using the reformed gas in a fuel cell. A liquid fuel line through which the liquid fuel introduced into the reformer flows, and the liquid fuel line is provided with a chamber for temporarily storing the liquid fuel so that foreign matters mixed in the liquid fuel are separated. It is characterized by.

  In this fuel cell system, a chamber provided in the liquid fuel line temporarily stores liquid fuel so that foreign matters mixed in the liquid fuel are separated. Therefore, for example, even when foreign matter such as water mixed with liquid fuel for steam reforming flows backward to the liquid fuel line, the foreign matter is separated in the chamber and only the liquid fuel passes through the chamber. It will be. Accordingly, it is possible to prevent the foreign matter from flowing backward to the upstream side of the chamber, and it is possible to prevent the device from being damaged by the foreign matter mixed in the liquid fuel flowing backward through the liquid fuel line. The “foreign matter” means other than liquid fuel, for example, for performing partial oxidation reforming in addition to “water (steam)” mixed with liquid fuel for steam reforming. In addition, “air (oxygen)”, “metal powder”, “rust”, “dust”, “trash” and the like mixed in the liquid fuel.

  Here, an orifice is preferably provided on the downstream side of the liquid fuel line. Thus, for example, when water flows backward through the liquid fuel line, even if the pressure is high and the flow velocity is high, the flow velocity is reduced by the orifice, so that water is reliably and suitably separated in the chamber. Therefore, it is possible to further prevent the equipment from being damaged by foreign matters mixed in the liquid fuel flowing backward through the liquid fuel line.

  The liquid fuel line is provided with a shut-off valve, and the shut-off valve is preferably set to open the liquid fuel line when the pressure of the flowing liquid fuel is equal to or higher than a predetermined pressure. In this case, when the pressure of the flowing liquid fuel is equal to or higher than a predetermined pressure (for example, the pressure of water mixed to perform steam reforming), the shutoff valve opens the liquid fuel line. It is possible to further prevent the device from being damaged by foreign matters mixed in the liquid fuel flowing backward through the liquid fuel line.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to prevent that an apparatus is damaged by the foreign material mixed in the liquid fuel which flows back in a liquid fuel line.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same or equivalent elements will be denoted by the same reference numerals, and redundant description will be omitted.

  FIG. 1 is a schematic configuration diagram showing a fuel cell system according to an embodiment of the present invention. The fuel cell system generates power using liquid fuel, and is employed, for example, as a household power supply source. Here, kerosene is used as the liquid fuel from the viewpoint that it is easily available and can be stored independently.

  As shown in FIG. 1, a fuel cell system 1 includes a desulfurizer 2, a fuel processing system (FPS) 3, a polymer electrolyte fuel cell (PEFC) stack (fuel cell) 4, an inverter 5, and a housing for housing them. A body 6 is provided.

  The desulfurizer 2 desulfurizes liquid fuel introduced from the outside. The desulfurizer 2 is provided with a heater (not shown), whereby the desulfurizer 2 heats the liquid fuel to, for example, 130 ° C. to 180 ° C. The FPS 3 is for reforming liquid fuel to generate reformed gas, and has a reformer 8 and a burner 9. The reformer 8 generates a reformed gas containing hydrogen by subjecting the desulfurized liquid fuel and steam (water) to a steam reforming reaction with a reforming catalyst. The burner 9 heats the reforming catalyst of the reformer 8 to supply a heat amount necessary for the steam reforming reaction. The reformer 8 is provided with a vaporizer 11 for vaporizing the introduced liquid fuel and water vapor.

  The PEFC stack 4 is configured by stacking a plurality of battery cells (not shown), and generates power using the reformed gas obtained by the FPS 3 to output a DC current. The battery cell has an anode, a cathode, and an electrolyte that is a solid polymer disposed between the anode and the cathode. By introducing the reformed gas into the anode and introducing air into the cathode, An electrochemical power generation reaction is performed in each battery cell.

  The inverter 5 converts the output DC current into AC current. The casing 6 accommodates the desulfurizer 2, the FPS 3, the PEFC stack 4, and the inverter 5 in a module.

  The fuel cell system 1 also includes a liquid fuel line L1 through which liquid fuel introduced into the reformer 8 and the burner 9 flows. The liquid fuel line L1 is made of a metallic pipe, and is connected to the reformer 8 to introduce the liquid fuel into the reformer 8, and to the burner 9 to introduce the liquid fuel into the burner 9. Is branched to a burner line L12 through a branch point T.

  Near the reformer 8 of the reformer line L11, a water line L2 for introducing water into the reformer 8 is connected, and liquid fuel and water are mixed. A recovery water line L4 for recovering water generated in the PCFC stack 4 is connected to the water line L2.

  Next, the liquid fuel line L1 will be described in detail. 2 is a schematic configuration diagram showing a liquid fuel line in the fuel cell system of FIG. 1, and FIG. 3 is a cross-sectional view showing a chamber in the fuel cell system of FIG. As shown in FIG. 2, a pump 13, a pressure gauge 52, a flow meter 41, a chamber 51, and an orifice 43 are provided in this order from the upstream side to the downstream side of the branch point T in the liquid fuel line L1. It has been.

  The pump 13 pumps the liquid fuel to the downstream side of the liquid fuel line L1, and here, a constant flow pump is used. By using the constant flow pump in this way, the flow rate of the liquid fuel introduced into the reformer 8 and the burner 9 can be stabilized. A control device 42 is connected to the pump 13.

  The pressure gauge 52 detects the pressure of the passing liquid fuel and outputs the pressure signal to the control device 42. The flow meter 41 detects the flow rate of the passing liquid fuel and outputs a flow rate signal to the control device 42. The chamber 51 temporarily stores liquid fuel so that foreign matters mixed in the liquid fuel are separated. Here, the chamber 51 is mainly composed of water mixed in the water line L2 and flowing backward through the liquid fuel line L1. The liquid fuel is temporarily stored so as to be separated (details will be described later). The orifice 43 reduces the flow area of the liquid fuel line L1, thereby limiting the liquid fuel that flows.

  The control device 42 includes, for example, a CPU, a ROM, a RAM, and the like. The control device 42 controls the driving of the pump 13 based on the flow rate signal output from the flow meter 41 and controls the flow rate of the liquid fuel pumped by the pump 13. Further, based on the pressure signal output from the pressure gauge 52, the control device 42 determines whether or not the pressure of the liquid fuel flowing through the liquid fuel line L1 is not less than a predetermined pressure (here, not less than the pressure of water in the water line L2). When the pressure of the liquid fuel is equal to or higher than a predetermined pressure, a valve opening signal is output to the shut-off valve 53 described later. Further, the control device 42 does not heat the reforming catalyst of the reformer 8 by the burner 9 (for example, when the reforming catalyst is heated using off-gas from the PEFC stack 4), the shut-off valve 54 described later. Is controlled to shut off the burner line L11.

  The reformer line L11 and the burner line L12 branched by the branch point T in the liquid fuel line L1 are provided with shutoff valves 53 and 54, respectively. The shutoff valve 53 is connected to the control device 42, shuts off the reformer line L11, and opens the reformer line L11 when a valve opening signal is input from the control device 42. That is, the reformer line L11 is opened when the pressure of the flowing liquid fuel is equal to or higher than a predetermined pressure. The shutoff valve 54 is connected to the control device 42, and shuts off the supply of liquid fuel to the burner 9 by shutting off the burner line L11 when the reforming catalyst of the reformer 8 is not heated by the burner 9.

  Here, in the fuel cell system, as described above, the chamber 51 for temporarily storing the liquid fuel is provided in the liquid fuel line L1 so that the water mixed in the liquid fuel is separated. As shown in FIG. 3, the chamber 51 temporarily stores liquid fuel in a space inside the chamber 51, floats the liquid fuel K due to the specific gravity difference between the liquid fuel K and the water W mixed in the liquid fuel, and the water W Precipitate and separate them. Only the suspended liquid fuel K can pass in the forward flow direction (arrow direction in the figure) and the reverse flow direction of the liquid fuel line L1, while the drain plug of the discharge portion 54 provided at the bottom portion. By removing 55, the precipitated water is discharged from the discharge part 54.

  In the fuel cell system 1 configured as described above, first, liquid fuel is introduced into the housing 6 from the outside by a pump (not shown). Subsequently, while the introduced liquid fuel is being pumped by the pump 13, the flow rate of the pumped liquid fuel is controlled by the control device 42 based on the flow rate signal output from the flow meter 41. Subsequently, the pumped liquid fuel passes through the pressure gauge 52, the flow meter 41, the chamber 51, and the orifice 43 in this order, and is branched at the branch point T into the reformer line L11 and the burner line L12.

  Then, one of the branched liquid fuels is introduced into the burner 9, and the other branched liquid fuel is input to the shut-off valve 53 when the valve opening signal is input and the reformer line L11 is opened (liquid When the fuel pressure is equal to or higher than the water pressure in the water line L2, it passes through the shut-off valve 53, is mixed with the water introduced from the water line L2, is vaporized in the vaporizer 11, and is introduced into the reformer 8. .

  Here, in the fuel cell system 1, since the chamber 51 is provided in the liquid fuel line L1 as described above, the water mixed from the water line L2 flows back to the liquid fuel line L1. However, the water that has flowed back is separated in the chamber 51, and only the liquid fuel passes through the chamber 51. Therefore, it is possible to suppress the backflow of water upstream of the chamber 51, and the equipment (here, the flow meter 41, the pressure gauge 52, and the pump 13) is damaged by the water mixed in the liquid fuel flowing back through the liquid fuel line L1. Can be prevented.

  As described above, since the precipitated water is discharged from the discharge portion 54, the chamber 51 not only separates the liquid fuel and the water mixed in the liquid fuel but also separates the separated water. Can be easily removed. Incidentally, in the chamber 51, it is of course possible to separate and remove the water flowing not only in the reverse flow direction but also in the forward flow direction, thereby suppressing the flow of water downstream of the chamber 51 in the liquid fuel line L1. be able to. Further, when metal powder, rust, dust, or dust having a specific gravity greater than that of the liquid fuel is mixed in the liquid fuel, these can be separated and removed by the chamber 51.

  Further, as described above, since the orifice 43 is provided on the downstream side of the chamber 51 in the liquid fuel line L1, even when the pressure of water flowing back through the liquid fuel line is high and the flow velocity is high, the orifice 43 allows the flow velocity to be increased. Is reduced (trapped), so that water is reliably and suitably separated in the chamber 51. Therefore, it is possible to further prevent the equipment from being damaged by the water mixed in the liquid fuel flowing backward through the liquid fuel line L1.

  Further, as described above, the reformer line L11 in the liquid fuel line L1 is provided with the shut-off valve 53, and in this shut-off valve 53, the pressure of the flowing liquid fuel is the water in the water line L2. It is set so that the reformer line L11 is opened when the pressure is equal to or higher than the pressure. For this reason, it is possible to prevent the water introduced from the water line L2 from flowing back to the liquid fuel line L1, and it is further prevented that the equipment is damaged by the water mixed in the liquid fuel flowing back through the liquid fuel line L1. Can be prevented.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment.

  For example, in the above embodiment, kerosene is used as the liquid fuel. However, gasoline, naphtha, light oil, methanol, ethanol, DME (dimethyl ether), and biofuel using biomass may be used. In this case, the desulfurizer (desulfurization method) and the reformer (reformation method) are adapted to the characteristics of the liquid fuel used.

  Moreover, in the said embodiment, although the chamber 51 temporarily stored liquid fuel so that the water which flows back in the liquid fuel line L1 as a foreign material was mainly isolate | separated, liquid fuel is partially oxidized reforming or autothermal reforming ( When performing ATR), for example, by providing an air hole through which air flows at the upper end of the chamber, the liquid fuel is temporarily stored so that air (oxygen) flowing back through the liquid fuel line as a foreign substance is mainly separated. In some cases. In this case, the pressure of the liquid fuel (the above-mentioned predetermined pressure) when the shutoff valve opens the liquid fuel line L1 is appropriately set according to the type of foreign matter.

  Moreover, in the said embodiment, although it was set as the fuel cell system 1 provided with the PEFC stack 4, it is good also as a fuel cell system provided with the solid oxide fuel cell (SOFC) stack. Moreover, in the said embodiment, although the constant flow pump was used for the pump 13, you may use various pumps other than constant flow pumps, such as an electromagnetic pump, for example.

1 is a schematic configuration diagram showing a fuel cell system according to an embodiment of the present invention. It is a schematic block diagram which shows the liquid fuel line in the fuel cell system of FIG. It is a schematic block diagram which shows the chamber in the fuel cell system of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fuel cell system, 4 ... PEFC stack (fuel cell), 8 ... Reformer, 43 ... Orifice, 51 ... Chamber, 53 ... Shut-off valve, L1 ... Liquid fuel line, K ... Liquid fuel, W ... Water (foreign matter) ).

Claims (2)

A fuel cell system for generating a reformed gas using liquid fuel in a reformer and generating electric power using the reformed gas in a fuel cell,
A liquid fuel line through which the liquid fuel introduced into the reformer flows;
The liquid fuel line is provided with a chamber for temporarily storing the liquid fuel so as to separate foreign matter, which is water mixed in the liquid fuel,
In the liquid fuel line, on the downstream side of the chamber, an orifice is provided to reduce the flow rate of the foreign matter that flows back through the liquid fuel line.
The chamber separates the foreign matter by a specific gravity difference between the liquid fuel and the foreign matter,
The liquid fuel line is provided with a shut-off valve,
The shutoff valve opens the liquid fuel line when the pressure of the flowing liquid fuel is equal to or higher than the pressure of the water in the water line connected to the liquid fuel line and for introducing water into the reformer. A fuel cell system that is set to Wherein the chamber, according to claim 1 Symbol mounting the fuel cell system, characterized in that the discharge unit for discharging the foreign materials is provided.

Images