JP5350750B2 - Fuel cell system - Google Patents

Description

  The present invention relates to a desulfurization system and a fuel cell system, and more particularly to a desulfurization system that removes sulfur from kerosene that is a raw material for producing a hydrogen-containing gas, and a fuel cell system including the desulfurization system.

A fuel cell that is expected to spread in recent years is a device that introduces hydrogen and oxygen and generates electric power through these electrochemical reactions. Fuel cells require hydrogen for power generation, but they are relatively difficult to obtain because the infrastructure for supplying hydrogen itself is not widespread, so steam-based reforming of hydrocarbon-based raw materials such as city gas and kerosene In many cases, a fuel cell system in which a reformer that generates hydrogen-rich reformed gas is attached to the fuel cell is constructed. As can be seen from the fact that kerosene, one of the hydrocarbon-based raw materials, is widely used as a fuel for household heaters, it is easy to store and handle, so it is particularly useful as a raw material for household fuel cell systems. Is suitable. Since kerosene has a higher sulfur content than natural gas or the like, desulfurization treatment is performed by heating with a heater in order to avoid sulfur poisoning of the electrode catalyst of the fuel cell (see, for example, Patent Document 1). .)
Japanese Unexamined Patent Publication No. 2004-31025 (paragraph 0005, FIG. 4 etc.)

  However, in order to desulfurize kerosene having a high sulfur content to such an extent that sulfur poisoning of the electrode catalyst of the fuel cell can be avoided, for example, it is necessary to treat it at a high temperature, which increases the power consumption of the heater. When the power load is large and the output of the fuel cell is increased, the amount of raw material consumed, that is, the amount of kerosene to be desulfurized, increases, so the power consumption of the heater during desulfurization further increases, and the power generated by the fuel cell is used for desulfurization If the heater is generating heat, less power can be used for the external power load generated by the fuel cell, and if the heater for desulfurization is heated by the commercial power source, the load on the commercial power source Will become bigger.

  In view of the above problems, an object of the present invention is to provide a desulfurization system and a fuel cell system that can reduce the influence of power consumption during desulfurization on an external power load.

  In order to achieve the above object, the desulfurization system according to the first aspect of the present invention has a heater 13 that receives power from a commercial power source 99 to generate heat, as shown in FIG. Is desulfurized by heating with a heater 13 to generate desulfurized kerosene k1, desulfurized kerosene tank 15 for storing desulfurized kerosene k1, and desulfurization in a predetermined time zone when the power load of the commercial power source 99 is small. Thus, a control device 81 for controlling the desulfurizer 11 is provided. Here, the “predetermined time period when the power load of the commercial power supply is small” can be statistically specified, and typically, a midnight charge that is lower than the daytime is set by the power company. Match the time zone.

  When configured in this manner, the desulfurized kerosene tank that stores desulfurized kerosene is provided, and desulfurization is performed in a predetermined time zone in which the power load of the commercial power source is small, which can contribute to leveling the power load of the commercial power source. The influence of the power consumption of the heater during desulfurization on the external power load can be reduced. In addition, since the electricity bill is often relatively inexpensive during the time period when the power load of the commercial power source is small, the running cost of the desulfurization system can be suppressed.

  In addition, the fuel cell system according to the second aspect of the present invention includes a desulfurization system 10 according to the first aspect of the present invention described above; for example, as shown in FIG. A reformer 20 that generates a reformed gas g mainly composed of hydrogen; and a fuel cell 30 that generates power by introducing the reformed gas g and an oxidant gas t containing oxygen.

  If comprised in this way, since the desulfurization system which has the desulfurized kerosene tank which stores desulfurized kerosene is provided, it will suppress that the electric power generated with the fuel cell is used for desulfurization when the external electric power load is comparatively large Therefore, the electric power generated by the fuel cell can be used effectively.

  Moreover, when the fuel cell system according to the third aspect of the present invention is shown with reference to FIG. 1, for example, in the fuel cell system 1 according to the second aspect of the present invention, the desulfurized kerosene tank 15 is at least The amount of desulfurized kerosene k1 consumed when the fuel cell 30 is operated at the rated time for a time corresponding to the predetermined time zone is set as the effective capacity.

  With this configuration, when the fuel cell is operated in a time zone other than the predetermined time zone while making the size of the desulfurizer appropriate without increasing the size, the fuel cell is operated over a time corresponding to the predetermined time zone. It is not necessary to operate the desulfurizer until the amount of desulfurized kerosene consumed at the rated operation is consumed, and the influence of the heater power consumption during desulfurization on the external power load can be reduced. .

  According to the present invention, a desulfurized kerosene tank that stores desulfurized kerosene is provided, and desulfurization is performed in a predetermined time zone when the power load of the commercial power source is small, which can contribute to leveling the power load of the commercial power source, The influence of the power consumption of the heater during desulfurization on the external power load can be reduced.

  Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same or similar members are denoted by the same or similar reference numerals, and redundant description is omitted.

  A fuel cell system 1 according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic system diagram of the fuel cell system 1. The fuel cell system 1 includes a desulfurization system 10 according to an embodiment of the present invention that removes and stores sulfur from kerosene k, a reformer 20 that reforms desulfurized kerosene k1, a fuel cell 30, and a fuel cell. And a control device 82 for controlling the system 1. Prior to describing the fuel cell system 1, the desulfurization system 10 will be described.

  The desulfurization system 10 includes a desulfurizer 11 that generates desulfurized kerosene k1 obtained by removing sulfur from kerosene k, a desulfurized kerosene tank 15 that stores the desulfurized kerosene k1, and a controller 81 that controls the desulfurization system 10. ing.

  The desulfurizer 11 includes an electric heater 13 that heats kerosene k and a desulfurization catalyst (not shown) that promotes desulfurization of kerosene k. The electric heater 13 is a heater that receives power from the commercial power source 99 and generates heat. Therefore, the electric heater 13 is connected to the commercial power source 99 by the commercial power cable 69 and is configured to receive power from the commercial power source 99. In general, the commercial power source 99 is often applied with a midnight charge that is less loaded during the day, typically at a late night time, and the late night charge is also applied in this embodiment. Let the time zone be a predetermined time zone. The electric heater 13 has kerosene to such an extent that when the desulfurized kerosene k1 is reformed into the reformed gas g by the reformer 20 and supplied to the fuel cell 30, the electrode catalyst (not shown) of the fuel cell 30 is not poisoned. The kerosene k can be heated to a temperature at which sulfur in k can be removed. The electric heater 13 is configured so that the presence or absence of energization, that is, the presence or absence of heat generation, is controlled by a signal from the control device 81. A desulfurization catalyst (not shown) is filled so as to enclose the electric heater 13 so as to be heated by the electric heater 13. The desulfurization catalyst (not shown) is filled with a capacity capable of desulfurizing kerosene k having a flow rate corresponding to the flow rate of the reformed gas g supplied to the fuel cell 30 when the fuel cell 30 is operated at a rated value. In other words, an appropriate desulfurization rate (a flow rate at which desulfurization treatment can be performed per unit time) of kerosene k corresponding to the flow rate of the reformed gas g supplied to the fuel cell 30 when the fuel cell 30 is operated at a rated value. A desulfurization catalyst (not shown) is filled so as to be equal to the flow rate. The size of the desulfurizer 11 depends on the size of the electric heater 13 and the capacity of the desulfurization catalyst (not shown) to be filled. By setting the filling amount of the desulfurization catalyst (not shown) as described above, desulfurization is performed. The enlargement of the vessel 11 is suppressed. From the viewpoint of reducing the size of the fuel cell system 1, the desulfurizer 11 is preferably as small as possible. Since the desulfurizer 11 desulfurizes the kerosene k by heating with the electric heater 13, the apparatus can be simplified and desulfurized with superior temperature controllability compared to the case of desulfurizing by heating by burning fuel (for example, kerosene k itself). Damage due to overheating of a catalyst (not shown) can be reduced.

  The desulfurized kerosene tank 15 is a tank for storing desulfurized kerosene k1 generated by desulfurizing kerosene k in the desulfurizer 11 as described above. The desulfurized kerosene tank 15 is consumed when the fuel cell 30 is rated for a time corresponding to a predetermined time zone, in other words, when it is assumed that the fuel cell 30 is rated for a predetermined time zone. The desulfurized kerosene k1 corresponding to the reformed gas g is formed in a size that can be stored as an effective capacity. For example, when the predetermined time zone is 8 hours, the desulfurized kerosene k1 corresponding to the reformed gas g consumed when the fuel cell 30 is rated for 8 hours can be stored as an effective capacity. By forming the desulfurized kerosene tank 15 at least in this size, when the fuel cell 30 is operated in a time zone other than the predetermined time zone, the fuel cell 30 is rated for a time corresponding to the predetermined time zone. It is not necessary to operate the desulfurizer 11 until the amount of desulfurized kerosene k1 consumed when operating at is consumed. The desulfurized kerosene tank 15 is provided with a liquid level detector 15s for detecting the liquid level of the stored desulfurized kerosene k1. The liquid level detector 15s can detect a low liquid level, a desulfurized kerosene replenishment start liquid level, a desulfurized kerosene replenishment stop liquid level, and a high liquid level set from the bottom to the top. It is configured. The low liquid level is a liquid level that is not detected when there is no failure in the desulfurization system 10. Typically, when a low liquid level is detected, the desulfurization system 10 is stopped and an alarm is issued. The desulfurized kerosene replenishment start liquid level is a liquid level at which desulfurization of kerosene k is started in order to replenish desulfurized kerosene k1 when detected in a time zone other than a predetermined time zone. The desulfurized kerosene replenishment stop liquid level is a liquid level at which desulfurization of kerosene k is stopped. In order to prevent the desulfurized kerosene k1 from overflowing from the desulfurized kerosene tank 15, the high liquid level typically stops the desulfurization system 10 and issues an alarm when a high liquid level is detected. In the present embodiment, the volume in the desulfurized kerosene tank 15 between the desulfurized kerosene replenishment start liquid level and the desulfurized kerosene replenishment stop liquid level is the effective capacity. The liquid level detector 15s is configured to transmit the detected liquid level as a signal to the control device 81.

  Kerosene k before being desulfurized by the desulfurizer 11 is stored in a kerosene tank 16 before desulfurization. Connected to the pre-desulfurization kerosene tank 16 are a desulfurization line 41 for supplying the stored pre-desulfurization kerosene k to the desulfurizer 11 and a combustion line 44 for supplying the combustion unit 23 of the reformer 20. ing. Both the desulfurization line 41 and the combustion line 44 are constituted by piping. The end of the desulfurization line 41 opposite to the pre-desulfurization kerosene tank 16 is connected to the desulfurizer 11. The desulfurization line 41 is provided with a desulfurization pump 17 that sends kerosene k toward the desulfurizer 11. The desulfurization pump 17 receives a signal from the control device 81 to start and stop, and is configured to be operated at a constant rotation speed (typically the most efficient rotation speed) during the start-up. Yes. By being configured in this way, it is avoided that kerosene k having a flow rate exceeding an appropriate desulfurization rate is introduced into the desulfurizer 11 (this means that desulfurization of the desulfurized kerosene k1 becomes insufficient. (This leads to avoidance) and enables high-efficiency operation of the pump. The desulfurizer 11 and the desulfurized kerosene tank 15 are connected by a storage line 42 that guides the desulfurized kerosene k1 from the desulfurizer 11 to the desulfurized kerosene tank 15. The storage line 42 is composed of piping. The desulfurized kerosene k1 in the storage line 42 flows at the discharge pressure of the desulfurization pump 17. The desulfurized kerosene tank 15 is also connected with a supply line 43 that guides the desulfurized kerosene k1 to the reforming unit 25 of the reformer 20. The supply line 43 is composed of piping.

  The control device 81 is connected to the electric heater 13 through a signal cable, and is configured to control whether the electric heater 13 generates heat. The control device 81 is connected to the liquid level detector 15s through a signal cable, and is configured to receive a liquid level signal from the liquid level detector 15s. The control device 81 is connected to the desulfurization pump 17 through a signal cable, and is configured to control the start / stop of the desulfurization pump 17. The control device 81 has a built-in clock and is configured to recognize whether or not it is a predetermined time zone. The control device 81 is communicably connected to a control device 82 that controls the reforming device 20 and the fuel cell 30. In FIG. 1, the control device 81 and the control device 82 are shown to be separated from each other. However, this is because the concept is divided for convenience of explanation, and the control device 81 and the control device 82 are separated. You may be comprised integrally.

  Next, the operation of the desulfurization system 10 will be described with reference to the flowchart of FIG. In the desulfurization system 10, the control device 81 determines whether or not it is the above-mentioned predetermined time zone with a built-in clock (ST1). When it is a predetermined time zone, it is determined whether or not the liquid level of the desulfurized kerosene k1 in the desulfurized kerosene tank 15 detected by the liquid level detector 15s is equal to or higher than the desulfurized kerosene replenishment stop liquid level (ST2). . When the liquid level of the desulfurized kerosene k1 is equal to or higher than the desulfurized kerosene replenishment stop liquid level, the process returns to the step (ST1) for determining again whether or not it is the predetermined time zone. If it is not the predetermined time zone in the step (ST1) for determining whether or not it is the predetermined time zone, the liquid level of the desulfurized kerosene k1 in the desulfurized kerosene tank 15 detected by the liquid level detector 15s is the desulfurized kerosene. It is determined whether or not it is below the replenishment start liquid level (ST3). If the liquid level of the desulfurized kerosene k1 is not less than or equal to the desulfurized kerosene replenishment start liquid level, the process returns to the step (ST1) of determining whether or not it is a predetermined time zone.

  When the level of the desulfurized kerosene k1 in the desulfurized kerosene tank 15 is not equal to or higher than the desulfurized kerosene replenishment stop liquid level in the step (ST2) of determining whether or not the level is higher than the desulfurized kerosene replenishment stop liquid level; When the liquid level of the desulfurized kerosene k1 in the tank 15 is equal to or lower than the desulfurized kerosene replenishment start liquid level in the step (ST3), it is determined whether or not the control device 81 is for desulfurization. The pump 17 is activated and the electric heater 13 is activated (ST4). The desulfurization pump 17 and the electric heater 13 are typically activated by the commercial power source 99, but may be configured to be activated by the electric power generated by the fuel cell 30 when the fuel cell 30 is generating power. . By the activation of the desulfurization pump 17, the kerosene k in the pre-desulfurization kerosene tank 16 flows toward the desulfurized kerosene tank 15. The kerosene k led out from the pre-desulfurization kerosene tank 16 flows into the desulfurizer 11, heated by the electric heater 13, reformed later, and supplied to the fuel cell 30 with respect to the electrode catalyst of the fuel cell 30. Thus, the desulfurized kerosene k1 is desulfurized to the extent that it is not affected by poisoning. The desulfurized kerosene k <b> 1 is fed by the pressure of the desulfurization pump 17 and flows into the desulfurized kerosene tank 15.

  While the kerosene k is being desulfurized, the control device 81 determines whether or not the liquid level of the desulfurized kerosene k1 in the desulfurized kerosene tank 15 detected by the liquid level detector 15s is equal to or higher than the desulfurized kerosene replenishment stop liquid level. (ST5). When the liquid level of the desulfurized kerosene k1 is not equal to or higher than the desulfurized kerosene replenishment stop liquid level, it is determined again whether or not the liquid level of the desulfurized kerosene k1 in the desulfurized kerosene tank 15 is equal to or higher than the desulfurized kerosene replenishment stop liquid level. Return to step (ST5). On the other hand, when the liquid level of the desulfurized kerosene k1 is equal to or higher than the desulfurized kerosene replenishment stop liquid level, the control device 81 stops the desulfurization pump 17 and stops the electric heater 13 (ST6). Thereafter, the process returns to the step (ST1) for determining whether or not it is a predetermined time period, and thereafter the above-described flow is repeated.

  The desulfurization system 10 described above generates and stores desulfurized kerosene k1 as much as possible in a predetermined time zone, and desulfurized kerosene k1 stored in the desulfurized kerosene tank 15 in a time zone other than the predetermined time zone. Is used preferentially, and when the desulfurized kerosene k1 in the desulfurized kerosene tank 15 is insufficient, the desulfurization pump 17 and the electric heater 13 are activated to supplementarily desulfurize the kerosene k. This can contribute to the leveling of the load, and the influence of the power consumption of the electric heater 13 during desulfurization on the power load outside the fuel cell system 1 can be reduced. In addition, the running cost of the desulfurization system 10 can be suppressed. When kerosene k is desulfurized supplementarily in a time zone other than the predetermined time zone, the desulfurization pump 17 operates at a constant flow rate, so that it is supplied to the fuel cell 30 when the fuel cell 30 is operated at a rated value. A desulfurized kerosene k1 having a flow rate corresponding to the flow rate of the reformed gas g is generated, and when the flow rate of the generated desulfurized kerosene k1 is larger than the flow rate used, the surplus is desulfurized kerosene tank 15 It is stored in.

  Next, the fuel cell system 1 including the desulfurization system 10 described above will be described with reference to FIG. As described above, the fuel cell system 1 includes the desulfurization system 10, the reforming device 20, the fuel cell 30, and the control device 82.

  The reformer 20 introduces desulfurized kerosene k1 and reforming water s into a reforming unit 25 that generates a reformed gas g rich in hydrogen by a steam reforming reaction, and a steam reforming reaction of the desulfurized kerosene k1. And a combustion section 23 that generates the heat of reforming used. The reformed gas g rich in hydrogen is a gas containing hydrogen as a main component, and is a gas supplied to the fuel cell 30 containing hydrogen in an amount of 40% by volume or more, typically about 70 to 80% by volume. The hydrogen concentration in the reformed gas g may be 80% by volume or more, that is, any concentration that can generate power by an electrochemical reaction with oxygen in the oxidant gas t when supplied to the fuel cell 30. The reforming water s introduced into the reforming unit 25 may be steam. The reformer 20 is capable of generating the reformed gas g stably and at low cost by using kerosene k, which is versatile and has infrastructure, as a raw material.

  The reforming unit 25 is filled with a reforming catalyst and configured to promote a steam reforming reaction. As the reforming catalyst, a nickel-based reforming catalyst or a ruthenium-based reforming catalyst is typically used. When the desulfurized kerosene k1 is reformed by the action of the reforming catalyst and the generated hydrogen-rich gas contains a predetermined amount or more of carbon monoxide, the electrode catalyst of the fuel cell 30 is poisoned. Therefore, the reforming section 25 has a shift section (not shown) filled with a shift catalyst and a selective oxidation section (not shown) filled with a selective oxidation catalyst, and is reformed from the reformer 20. It is preferable that the concentration of carbon monoxide in the gas g is about 10 ppm by volume or less, preferably about 1 ppm by volume. As the shift catalyst, typically, an iron-chromium shift catalyst, a copper-zinc shift catalyst, a platinum shift catalyst, or the like is used. Typically, a platinum-based selective oxidation catalyst, a ruthenium-based selective oxidation catalyst, a platinum-ruthenium-based selective oxidation catalyst, or the like is used as the selective oxidation catalyst. The reaction in the reforming catalyst is an endothermic reaction, but the reaction in the shift part having the shift catalyst and the selective oxidation part having the selective oxidation catalyst is an exothermic reaction.

  Connected to the reforming unit 25 are a supply line 43 for introducing desulfurized kerosene k1 and a reforming water pipe 26 for introducing reforming water s. The reforming water pipe 26 is typically connected to the supply line 43 in the reforming unit 25 so that the desulfurized kerosene k1 is vaporized and then mixed with the reforming water s. The supply line 43 is provided with a supply pump 18 for feeding desulfurized kerosene k1 toward the reforming unit 25. The supply pump 18 is configured to start and stop by receiving a signal from the control device 82, and to change the rotation speed during startup in accordance with the signal received from the control device 82. The reforming water pipe 26 is provided with a reforming water pump 27 that supplies the reforming water s to the reforming unit 25. In addition, a reformed gas pipe 51 for deriving the reformed gas g is connected to the reforming unit 25 (in the case where the reformed gas has a site for reducing the carbon monoxide concentration). Further, the reforming unit 25 is provided with a temperature detector (not shown) for detecting the temperature.

  The combustion unit 23 is disposed in the reforming device 20 so as to be adjacent to the position where the reforming catalyst of the reforming unit 25 is provided, and a burner ( (Not shown) is provided. The combustion unit 23 introduces the kerosene k stored in the pre-desulfurization kerosene tank 16, the anode offgas p and the reformed gas g, which are gases containing hydrogen derived from the fuel cell 30, and the combustion air a It is configured to be introduced and burned with a burner (not shown) to obtain reforming heat used in the steam reforming reaction. The combustion unit 23 introduces and burns one or more of kerosene k, anode offgas p, and reformed gas g according to the state of the fuel cell system 1. The components of the anode off gas p typically include about half of hydrogen and the other half containing carbon dioxide, nitrogen, raw materials or compounds thereof.

  In the combustion section 23, an anode offgas pipe 52 as an anode offgas line capable of introducing the anode offgas p and the reformed gas g, a combustion line 44 for introducing kerosene k, and combustion air for introducing combustion air a A combustion air pipe 58 as a line is connected. A combustion pump 19 that feeds kerosene k toward the combustion unit 23 is disposed in the combustion line 44 that guides the kerosene k from the pre-desulfurization kerosene tank 16 to the combustion unit 23 of the reformer 20. The combustion pump 19 is configured to start and stop by receiving a signal from the control device 82, and to change the rotation speed during startup in accordance with the signal received from the control device 82. Further, an exhaust gas pipe 59 for discharging the exhaust gas e after being burned by a burner (not shown) is connected to the combustion unit 23.

  The fuel cell 30 is typically a polymer electrolyte fuel cell. The fuel cell 30 includes an anode 31 that introduces a reformed gas g, a cathode 32 that introduces an oxidant gas t, and a cooling unit 33 that removes heat generated by an electrochemical reaction. The oxidant gas t introduced to the cathode 32 is typically air. Although the fuel cell 30 is shown in a simplified manner in the figure, in practice, a single cell is formed by sandwiching a solid polymer membrane between an anode 31 and a cathode 32, and this cell is interposed via a cooling unit 33. A plurality of layers are laminated. In the fuel cell 30, hydrogen in the reformed gas g supplied to the anode 31 is decomposed into hydrogen ions and electrons, and the hydrogen ions pass through the solid polymer film and move to the cathode 32, and the electrons move to the anode 31. It moves to the cathode 32 through a conducting wire connecting to the cathode 32, reacts with oxygen in the oxidant gas t supplied to the cathode 32 to generate water, and generates heat during this reaction. In this reaction, the direct current can be taken out by passing electrons through the conducting wire. The extracted direct current power is converted into alternating current power by an inverter in a power conditioner (not shown), or a direct current power load outside the fuel cell system 1 and a power load inside the fuel cell system 1 (electric heater) 13, each pump 17-19, 27, air blower 29, etc.).

  The anode 31 and the reforming unit 25 are connected via a reformed gas pipe 51 serving as a reformed gas line. The reformed gas pipe 51 is provided with a reformed gas valve 61 capable of blocking the flow of the reformed gas g. Further, the anode 31 and the combustion part 23 are connected via an anode off-gas pipe 52, and an anode off-gas p containing hydrogen that has not been used for an electrochemical reaction in the fuel cell 30 can be introduced into the combustion part 23. It can be done. The anode off gas pipe 52 is provided with an anode off gas valve 62 that can block the flow of the anode off gas p. A reformed gas pipe 51 upstream of the reformed gas valve 61 and an anode offgas pipe 52 downstream of the anode offgas valve 62 are connected by a bypass pipe 53. A bypass valve 63 is provided in the bypass pipe 53. The reformed gas valve 61, the anode off gas valve 62, and the bypass valve 63 are typically normally closed electromagnetic valves.

  The cathode 32 includes an oxidant gas pipe 54 serving as an oxidant gas line for introducing the oxidant gas t, and a cathode offgas that discharges a cathode offgas q containing oxygen that has not been used for an electrochemical reaction in the fuel cell 30. A cathode offgas pipe 55 as a line is connected. A combustion air pipe 58 branches from the oxidant gas pipe 54. An air blower as an oxidant gas supply means for sending the oxidant gas t to the cathode 32 and the combustion air a to the combustion part 23 is sent to the oxidant gas pipe 54 upstream of the branch to the combustion air pipe 58. 29 is arranged. The air blower 29 is typically configured such that the rotation speed (rpm) can be adjusted by an inverter, whereby the flow rates of the combustion air a and the oxidant gas t can be increased or decreased. An oxidant gas shut-off valve 64 capable of shutting off the flow of the oxidant gas t is provided in the oxidant gas pipe 54 on the downstream side of the branching portion to the combustion air pipe 58. The oxidant gas cutoff valve 64 is typically an electric two-way valve. The oxidant gas pipe 54 is typically provided with a humidifier (not shown) that humidifies the oxidant gas t. The cathode offgas pipe 55 is provided with a cathode offgas cutoff valve 65 capable of blocking the flow of the cathode offgas q. The cathode off-gas cutoff valve 65 is typically an electric two-way valve.

  A cooling water line 48 for circulating the cooling water c is connected to the cooling unit 33 of the fuel cell 30. The cooling water line 48 is composed of piping. The cooling water line 48 is provided with a heat exchanger (not shown) that is omitted in FIG. 1, and the cooling water c that has passed through the heat exchanger (not shown) and the temperature has dropped is a cooling water pump (not shown). A circulation flow path is formed so as to be introduced into the fuel cell 30 as shown.

  The control device 82 controls the operation of the fuel cell system 1. The operation of the fuel cell system 1 is typically controlled in accordance with a sequence in accordance with a procedure for explaining the operation described later. The control device 82 transmits signals to the supply pump 18, the combustion pump 19, the reforming water pump 27, and the air blower 29 to control the start and stop, and also controls the flow rate of the discharged fluid. Note that transmitting signals to the supply pump 18, the combustion pump 19, the reforming water pump 27, and the air blower 29 includes transmitting a signal to a power panel (not shown) that transmits power to them. Further, the control device 82 is connected to each of the valves 61 to 65 by a signal cable, and is configured to transmit an opening / closing signal to open / close the valve. The control device 82 is connected to a temperature detector (not shown) that detects the temperature of the reforming unit 25 by a signal cable, and is configured to receive a temperature signal. The control device 82 is electrically connected to a control device 81 that controls the desulfurization system 10, and is configured to be able to communicate with each other between the control devices 81 and 82. In FIG. 1, the two control devices 81 and 82 are shown as separate bodies, but may be configured integrally.

  With continued reference to FIG. 1, the operation of the fuel cell system 1 will be described. In order to start the operation of the stopped fuel cell system 1, the combustion pump 19 is activated to supply kerosene k to the combustion unit 23 and the air blower 29 is activated to supply the combustion air a to the combustion unit 23. Supply. At this time, the valves 61 to 65 are closed. When the kerosene k burns in the combustion section 23 and reforming heat is generated and the reforming section 25 is heated, the supply pump 18 is activated to introduce the desulfurized kerosene k1 into the reforming section 25. The temperature of the reforming unit 25 is detected by a temperature detector (not shown). Reforming water s is also introduced into the reforming unit 25 by starting the reforming water pump 27, and the reforming heat is obtained from the combustion unit 23, and the desulfurized kerosene k1 undergoes a steam reforming reaction to generate reformed gas g. Is done. In the reformer 20, the reformed gas g is generated as described above, but since the composition of the reformed gas g is not stable at the beginning of operation, the reformed gas valve 61 and the anode off-gas valve 62 are closed. Then, the bypass valve 63 is opened, and the reformed gas g whose composition is not stable is led to the combustion section 23 without being supplied to the fuel cell 30 and burned. At this time, the reformed gas g having an unstable composition introduced into the combustion unit 23 is mainly burned, and a shortage of kerosene k is introduced into the combustion unit 23. When the reformed gas g having an unstable composition is sufficient, the combustion pump 19 is stopped and the supply of kerosene k to the combustion unit 23 is stopped.

  When the composition of the reformed gas g generated in the reformer 20 is stabilized and the carbon monoxide concentration in the reformed gas g is reduced to a predetermined value, the controller 82 controls the reformed gas valve 61 and the anode. The off gas valve 62 is opened and the bypass valve 63 is closed so that the reformed gas g is introduced into the fuel cell 30. As a result, the reformed gas g is introduced into the anode 31 of the fuel cell 30. On the other hand, the control device 82 opens the oxidant gas cutoff valve 64 and the cathode off-gas cutoff valve 65, whereby the oxidant gas t is introduced into the cathode 32 of the fuel cell 30. Typically, the reforming gas g is supplied from the reforming apparatus 20 so that the amount of the reforming gas g supplied to the anode 31 is about 70 to 80%, preferably about 75%, of the hydrogen utilization rate. (Desulfurized kerosene k1 is introduced into the reforming unit 25 accordingly). In addition, the rotation speed of the air blower 29 and a flow rate adjusting valve (not shown) are supplied so that an amount of oxidant gas t with an oxygen utilization rate of about 45 to 60%, preferably about 50%, is supplied to the cathode 32. Adjusted.

In the fuel cell 30, an electrochemical reaction is performed between hydrogen in the reformed gas g introduced into the anode 31 and oxygen in the oxidant gas t introduced into the cathode 32. As for the electrochemical reaction, the reaction represented by the following formula (1) is performed on the anode 31 side, and the reaction represented by the following formula (2) is performed on the cathode 32 side.
2H ₂ → 4H ⁺ + 4e ⁻ (1)
O ₂ + 4H ⁺ + 4e ⁻ → 2H ₂ O (2)
Electricity is generated by this electrochemical reaction, heat is generated, and moisture is generated. In further explanation, electric power can be obtained when electrons on the anode 31 side move to the cathode 32 side through the external electric circuit. Hydrogen ions on the anode 31 side pass through the solid polymer film and move to the cathode 32 side, and combine with oxygen to generate moisture. This electrochemical reaction is an exothermic reaction.

  Since the power obtained by the fuel cell 30 is DC power, it is converted into AC power by a power conditioner (not shown) and applied to an external power load (not shown) and to an internal power load (electric heater 13, desulfurization pump 17). , Power supply pump 18, combustion pump 19, reforming water pump 27, air blower 29, accessories including valves 61 to 65, etc.). The power generated by the fuel cell 30 is a power conditioner (not shown) such that the electric power generated by the fuel cell 30 has a predetermined value (eg, 90% of the total power consumption) with respect to the total power consumption of the external power load and the internal power load. Is set. The amounts of the reformed gas g and the oxidant gas t supplied to the fuel cell 30 are adjusted by the control device 82 so that the supply amount is appropriate for the set value. At this time, in the power conditioner (not shown), the inverter is controlled so as to link the fuel cell 30 and the commercial power source 99, and the insufficient power is supplied with AC power from the commercial power source 99.

  During the operation of the fuel cell 30, the anode off gas p is discharged from the anode 31. The discharged anode off gas p is guided to the combustion unit 23 of the reformer 20 via the anode off gas pipe 52 and burned. By the combustion of the anode off gas p in the combustion unit 23, reforming heat used for reforming in the reforming unit 25 can be generated. When the reforming heat generated by the combustion of the anode off gas p introduced into the combustion unit 23 is insufficient, the combustion pump 19 is activated to introduce kerosene k into the combustion unit 23. The exhaust gas e generated by the combustion in the combustion unit 23 is discharged out of the system through the exhaust gas pipe 59. On the other hand, the cathode offgas q is discharged from the cathode 32 and discharged outside the system via the cathode offgas pipe 55.

  As described above, since the electrochemical reaction in the fuel cell 30 is an exothermic reaction, the heat generated to continue the operation of the fuel cell 30 is removed by the cooling water c. When the reformed gas g and the oxidant gas t are introduced into the fuel cell 30 and power generation is performed, the controller 82 activates a cooling water pump (not shown) to circulate the cooling water c. The temperature of the cooling water c introduced into the cooling unit 33 rises due to the heat generated by the electrochemical reaction in the fuel cell 30. The fuel cell 30 is maintained at a temperature suitable for operation (about 60 ° C. to 80 ° C.) after the heat generation is removed by the cooling water c.

  When stopping the power generation of the fuel cell 30, first, the air blower 29 is stopped and the oxidant gas cutoff valve 64 and the cathode off-gas cutoff valve 65 are closed to seal the cathode 32. Next, the supply pump 18 and the reforming water pump 27 are stopped, and the reformed gas valve 61 and the anode offgas valve 62 are closed. Thus, when the cathode 32 is first sealed, oxygen in the oxidant gas t sealed in the cathode 32 causes an electrochemical reaction with hydrogen in the anode 31, and the electric power generated by the reaction is, for example, the power of the supply pump 18. And oxygen of the cathode 32 is consumed. When the oxygen at the cathode 32 is consumed, power generation in the fuel cell 30 is lost, so that the electric power necessary for the operation of the supply pump 18 and the reforming water pump 27 and the like necessary for the stop processing is supplied from the commercial power source 99. Receive. By consuming oxygen in the oxidant gas t sealed in the cathode 32, the oxygen component can be eliminated from the oxidant gas t, and the cathode 32 can be made in an inert atmosphere. Therefore, it is possible to avoid that the stopped fuel cell 30 is exposed to a high potential due to the residual voltage. By setting the cathode 32 of the stopped fuel cell 30 to an inert atmosphere, it is possible to prevent residual oxygen from passing through the solid polymer membrane and entering the anode 31 from the cathode 32. Damage due to oxidation can be prevented.

  In the above description, the fuel cell 30 has been described as a polymer electrolyte fuel cell, but may be a fuel cell other than a polymer electrolyte fuel cell such as a phosphoric acid fuel cell. However, the polymer electrolyte fuel cell can be operated at a relatively low temperature and can be downsized, so that it is suitable for installation in a general household.

1 is a schematic system diagram of a fuel cell system including a desulfurization system according to an embodiment of the present invention. It is a flowchart explaining the effect | action of the desulfurization system which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel cell system 10 Desulfurization system 11 Desulfurizer 13 Electric heater 15 Desulfurized kerosene tank 20 Reformer 30 Fuel cell 81 Controller 99 Commercial power k Kerosene k1 Desulfurized kerosene g Reformed gas t Oxidant gas

Claims (1)

A desulfurizer that has a heater that receives power from a commercial power source and generates heat, and heats the introduced kerosene with the heater to desulfurize to produce desulfurized kerosene ;
A desulfurized kerosene tank for storing the desulfurized kerosene ;
A desulfurization system that comprises a control unit for controlling the desulfurizer to perform the desulfurization to a predetermined time period the power load is small the commercial power source;
A reformer that introduces and reforms the desulfurized kerosene to generate a reformed gas mainly composed of hydrogen;
Bei example a fuel cell that generates by introducing an oxidant gas containing the reformed gas and oxygen;
The desulfurized kerosene tank is configured to have an effective capacity of an amount of the desulfurized kerosene consumed when the fuel cell is operated at a rating for at least a time corresponding to the predetermined time period;
Fuel cell system.

Images