JP2012062367A - Desulfurization system and method of controlling the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a desulfurization system that can prevent failures of a desulfurizer, and to provide a method of controlling the same.SOLUTION: The desulfurization system (100) includes: a dehumidifier (21) that includes an adsorbent for adsorbing the moisture of a raw fuel gas to be modified into a hydrogen-containing gas; the desulfurizer (22) that desulfurizes the raw fuel gas dehumidified by the dehumidifier (21); a regenerator (40) for regenerating the dehumidifier (21) by supplying, to the dehumidifier (21), a dehumidifier-regenerating gas that is lower in water vapor partial pressure or is higher in temperature than the raw fuel gas supplied to the dehumidifier (21); and a first bypass unit (24) for the dehumidifier-regenerating gas discharged from the dehumidifier (21) to bypass the desulfurizer (22) when the regenerator (40) supplies the dehumidifier-regenerating gas to the dehumidifier (21).

Description

  The present invention relates to a desulfurization system and a control method for the desulfurization system.

  Hydrogen consumed by power generation or the like of the fuel cell is generated in, for example, a reformer. In the reformer, hydrogen is generated by a steam reforming reaction between raw fuel gas such as hydrocarbon and reformed water. The raw fuel gas contains a small amount of odorant such as sulfur compound for the purpose of early detection of leakage. Since this sulfur compound causes a reduction in reforming efficiency of the reformer, it is preferably removed before being supplied to the reformer.

  Therefore, a desulfurizer may be provided. In addition, a dehumidifier may be provided before the desulfurizer for the purpose of removing moisture in the raw fuel gas. Patent Document 1 discloses a technique of providing a plurality of sets of dehumidifiers and desulfurizers and regenerating the dehumidifiers and desulfurizers as necessary.

JP 2008-277300 A

  However, in the technique of Patent Document 1, the dehumidifier and the desulfurizer are simultaneously regenerated. In this case, a malfunction may occur in the desulfurizer due to water vapor desorbed from the dehumidifier during regeneration.

  This invention is made | formed in view of the said problem, and it aims at providing the control method of the desulfurization system which can suppress the malfunction of a desulfurizer, and a desulfurization system.

  A desulfurization system according to the present invention includes a dehumidifier including an adsorbent that adsorbs moisture of raw fuel gas to be reformed into a hydrogen-containing gas, a desulfurizer that desulfurizes the raw fuel gas dehumidified by the dehumidifier, A regeneration means for regenerating the dehumidifier by supplying a dehumidifier regeneration gas having a lower water vapor partial pressure or a higher temperature than the raw fuel gas supplied to the dehumidifier to the dehumidifier; When supplying the dehumidifier regeneration gas to the dehumidifier, the dehumidifier regeneration gas exhausted from the dehumidifier is provided with first bypass means for bypassing the desulfurizer. In the desulfurization system according to the present invention, it is possible to suppress the inflow of moisture into the desulfurizer when the dehumidifier is regenerated. Thereby, the malfunction of a desulfurizer can be suppressed.

  When the regeneration unit supplies the dehumidifier regeneration gas to the dehumidifier, the regeneration unit may include a second bypass unit that supplies the raw fuel gas to the desulfurizer without passing through the dehumidifier. The regeneration means may supply the dehumidifier regeneration gas to the dehumidifier when the temperature of the adsorbent, the temperature of the raw fuel gas, or the outside air temperature exceeds a predetermined value. The regeneration means may supply the dehumidifier regeneration gas to the dehumidifier when the rate of temperature increase of the adsorbent falls below a predetermined value. The dehumidifier regeneration gas may be air. The dehumidifier regeneration gas may be heated air. The first bypass channel may supply the air exhausted from the dehumidifier to a cathode of a fuel cell.

  The raw fuel gas is supplied to the reformer through the dehumidifier and the desulfurizer in this order, and the air is supplied to the cathode of the fuel cell without going through the dehumidifier and the desulfurizer. The flow path configuration, and the raw fuel gas is supplied to the reformer via the desulfurizer without passing through the dehumidifier, and the air passes through the desulfurizer via the dehumidifier. It may be provided with a flow path configuration selection means for selecting any one of the second flow path configurations supplied to the cathode of the fuel cell. The flow path form selection means selects the first flow path form and the second flow path form based on a temperature increase rate of the adsorbent within a predetermined period immediately after selecting the first flow path form. May be.

  The regeneration unit may supply a desulfurizer regeneration gas having a sulfur component partial pressure lower than that of the raw fuel gas supplied to the dehumidifier to the desulfurizer without passing through the dehumidifier. When the desulfurizer regeneration gas is supplied to the desulfurizer, the desulfurizer regeneration gas may be provided with discharge means for releasing the desulfurizer regeneration gas discharged from the desulfurizer to the atmosphere. The regeneration means may supply the desulfurizer regeneration gas to the desulfurizer as long as a condition that is equal to or less than a detection limit of the odor of the raw fuel gas discharged from the desulfurizer is satisfied. The regeneration means may supply the desulfurizer regeneration gas to the desulfurizer when a required load of a fuel cell to which the hydrogen-containing gas is supplied is below a predetermined value. The desulfurizer regeneration gas may be air. The desulfurizer regeneration gas may be heated air.

  A desulfurization system control method according to the present invention includes a dehumidifier having an adsorbent that adsorbs moisture of raw fuel gas to be reformed into a hydrogen-containing gas, and desulfurization that desulfurizes the raw fuel gas dehumidified by the dehumidifier. A desulfurization system comprising: a regeneration step for regenerating the dehumidifier by supplying a dehumidifier regeneration gas having a water vapor partial pressure lower than that of the raw fuel gas supplied to the dehumidifier to the dehumidifier; A bypass step of bypassing the desulfurizer with the dehumidifier regeneration gas exhausted from the dehumidifier when the dehumidifier regeneration gas is supplied to the dehumidifier in the regeneration step. Is. In the control method of the desulfurization system according to the present invention, it is possible to suppress the inflow of moisture into the desulfurizer when the dehumidifier is regenerated. Thereby, the malfunction of a desulfurizer can be suppressed.

  ADVANTAGE OF THE INVENTION According to this invention, the control method of the desulfurization system which can suppress the malfunction of a desulfurizer, and a desulfurization system can be provided.

1 is a block diagram illustrating an overall configuration of a fuel cell system including a desulfurization system according to Embodiment 1. FIG. It is a fragmentary perspective view containing the cross section of a fuel cell. It is a figure which shows the flowchart which shows switching of a dehumidifier reproduction | regeneration process and normal operation. It is a figure which shows the flowchart which shows switching of a dehumidifier reproduction | regeneration process and normal operation. It is a figure which shows the temperature sensor in a dehumidifier. It is a figure which shows the flowchart which shows switching of a dehumidifier reproduction | regeneration process and normal operation. It is a figure which shows the flowchart which shows switching of a dehumidifier reproduction | regeneration process and normal operation. It is a figure which shows the flowchart which shows switching of a dehumidifier reproduction | regeneration process and normal operation. It is a figure which shows the other example of a bypass flow path. FIG. 3 is a block diagram showing an overall configuration of a fuel cell system including a desulfurization system according to Example 2. It is a figure which shows an example of the flowchart which judges the reproduction | regeneration processing start of a desulfurizer based on a strange odor detection limit. It is a figure which shows the flowchart which shows desulfurizer reproduction | regeneration processing and switching of normal operation.

  Hereinafter, the best mode for carrying out the present invention will be described.

  FIG. 1 is a block diagram illustrating an overall configuration of a fuel cell system 100 including a desulfurization system 20 according to the first embodiment. As shown in FIG. 1, a fuel cell system 100 includes a raw fuel supply unit 10, a desulfurization system 20, a reforming water supply unit 30, an oxidant gas supply unit 40, a reformer 50, a combustion chamber 60, a fuel cell 70, The heat exchange part 80 and the control part 90 are provided.

  The raw fuel supply unit 10 is a raw fuel pump for supplying raw fuel such as hydrocarbons to the reformer 50. As an example of the hydrocarbon, city gas, natural gas, liquefied petroleum gas (LPG), or the like can be used. The raw fuel supply unit 10 is connected to a switching valve 23 (described later) through a pipe.

  The desulfurization system 20 includes a dehumidifier 21 for removing moisture in the raw fuel, a desulfurizer 22 for removing sulfur components in the raw fuel, switching valves 23 and 24 for switching the flow path, and a temperature for detecting the temperature of the raw fuel. A sensor 25, a temperature sensor 26 that detects the temperature of the adsorbent in the dehumidifier 21, a temperature sensor 27 that detects the outside air temperature, an optical sensor 28, and a water vapor sensor 29 are included.

  The dehumidifier 21 includes an adsorbent for adsorbing water vapor. The adsorbent of the dehumidifier 21 may include one or both of a physical adsorbent and a chemical adsorbent. As an adsorbent of the dehumidifier 21, for example, dry allite, A-type zeolite, silica gel, molecular sieves 3A, 4A, 5A, and combinations thereof can be used.

  The desulfurizer 22 includes an adsorbent for adsorbing sulfur or a sulfur compound (hereinafter referred to as a sulfur component). The adsorbent of the desulfurizer 22 may include one or both of a physical adsorbent and a chemical adsorbent. As the adsorbent of the desulfurizer 22, for example, a material in which Ag, Cu, Zn, Fe, Co, Ni or the like is supported on a hydrophobic zeolite can be used, and a Y-type zeolite, a β-type zeolite, or an X-type zeolite can be used. You may use what carried Ag or Cu. Further, as the adsorbent for the desulfurizer 22, a molecular sieve 13X, a copper-zinc-based desulfurization material, or a porous carrier carrying copper may be used. These adsorbents may be ion-exchanged with, for example, a metal selected from the group consisting of noble metals, transition metals, and combinations thereof.

  The adsorbents of the dehumidifier 21 and the desulfurizer 22 may be the same. However, in this case, by making the pores of the adsorbent of the dehumidifier 21 smaller than the pores of the adsorbent of the desulfurizer 22, the dehumidifier 21 can mainly dehumidify and the desulfurizer 22 can mainly desulfurize.

  The switching valve 23 opens the flow path that connects the raw fuel supply unit 10 and the dehumidifier 21, and the flow path that connects the raw fuel supply unit 10 and the desulfurizer 22, the oxidant gas supply unit 40, and the dehumidifier 21. It is a valve that can be switched between opening of a flow path connecting the two. The switching valve 24 opens a flow path connecting the dehumidifier 21 and the desulfurizer 22, opening a flow path connecting the oxidant gas supply unit 40 and the cathode 71, and a flow path connecting the dehumidifier 21 and the cathode 71. It is a valve that can be switched between opening and closing.

  The optical sensor 28 is a sensor that detects a hue change of the adsorbent of the dehumidifier 21. The water vapor sensor 29 is a sensor that detects the water vapor concentration in the raw fuel gas flowing from the dehumidifier 21 toward the switching valve 24.

  The reforming water supply unit 30 stores the reforming water tank 31 that stores the reforming water necessary for the steam reforming reaction in the reformer 50, and the reforming water tank 31 that supplies the necessary reforming water from the condensed water tank 82 described later. A pump 32 for supplying to the reforming water, an ion exchanger 33 for performing ion exchange on the reforming water supplied to the reforming water tank 31, and the reforming water stored in the reforming water tank 31 to the reformer 50. A flow rate regulator 34 and the like for supply are included.

  The oxidant gas supply unit 40 includes a pump or the like for supplying oxidant gas to the cathode 71 of the fuel cell 70. In this embodiment, air is used as the oxidant gas. The oxidant gas supply unit 40 is connected to the switching valve 23 and the switching valve 24 via a pipe. The piping is arranged so as to pass through the package 61 in which the fuel cell 70 and the reformer 50 are arranged. As a result, the oxidant gas supplied to the switching valve 23 and the switching valve 24 is heated by the heat generated by the power generation of the fuel cell 70 and the heat generated by the combustion in the combustion chamber 60.

  The reformer 50 includes a vaporizer 51 for vaporizing the reformed water and a reformer 52 for generating a fuel gas containing hydrogen gas by a steam reforming reaction. The vaporization unit 51 and the reforming unit 52 are adjacent to the combustion chamber 60 so that the combustion heat of the combustion chamber 60 can be used. The reforming unit 52 includes a reforming catalyst and the like. The fuel cell 70 has a structure in which an electrolyte 73 is sandwiched between a cathode 71 and an anode 72. The heat exchange unit 80 includes a heat exchanger 81 and a condensed water tank 82. The heat exchanger 81 is a heat exchanger for performing heat exchange between the exhaust gas in the combustion chamber 60 and tap water. The condensed water tank 82 is a tank that stores condensed water generated from exhaust gas by heat exchange in the heat exchanger 81.

  The control unit 90 is a device that controls the fuel cell system 100 and includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. The control unit 90 controls the operation of each unit.

  FIG. 2 is a partial perspective view including a cross section of the fuel cell 70. As shown in FIG. 2, the fuel cell 70 has a flat plate-like overall shape. A plurality of fuel gas passages 12 penetrating along the axial direction (longitudinal direction) are formed in the conductive support 11 having gas permeability. A fuel electrode 13, a solid electrolyte 14, and an oxygen electrode 15 are laminated in this order on one plane on the outer peripheral surface of the conductive support 11. On the other plane facing the oxygen electrode 15, an interconnector 17 is provided via a bonding layer 16, and a P-type semiconductor layer 18 for reducing contact resistance is provided thereon. The fuel electrode 13 functions as the anode 72 in FIG. 1, the oxygen electrode 15 functions as the cathode 71 in FIG. 1, and the solid electrolyte 14 functions as the electrolyte 73 in FIG. The fuel cell 70 may have a stack structure in which a plurality of single cells shown in FIG. 2 are stacked.

By supplying the reformed gas containing hydrogen to the fuel gas passage 12, hydrogen is supplied to the fuel electrode 13. On the other hand, oxygen is supplied to the oxygen electrode 15 by supplying an oxidant gas containing oxygen around the fuel cell 70. As a result, the following electrode reactions occur in the oxygen electrode 15 and the fuel electrode 13 to generate power. The power generation reaction is performed at 600 ° C. to 1000 ° C., for example.
Oxygen electrode: 1 / 2O ₂ + 2e ⁻ → O ²⁻ (solid electrolyte)
Fuel electrode: O ²⁻ (solid electrolyte) + H ₂ → H ₂ O + 2e ⁻

The material of the oxygen electrode 15 has oxidation resistance and is porous so that gaseous oxygen can reach the interface with the solid electrolyte 14. The solid electrolyte 14 has a function of moving oxygen ions O ²⁻ from the oxygen electrode 15 to the fuel electrode 13. The solid electrolyte 14 is composed of an oxygen ion conductive oxide. Further, since the solid electrolyte 14 physically separates the fuel gas and the oxidant gas, the solid electrolyte 14 is stable and dense in the oxidizing / reducing atmosphere. The fuel electrode 13 is made of a material that is stable in a reducing atmosphere and has an affinity for hydrogen. The interconnector 17 is provided to electrically connect the fuel cells 70 in series and is dense to physically separate the fuel gas and the oxidant gas.

For example, the oxygen electrode 15 is formed of a lanthanum cobaltite-based perovskite complex oxide having high conductivity of both electrons and ions. The solid electrolyte 14 is formed of ZrO ₂ (YSZ) containing Y ₂ O ₃ having high ion conductivity. The fuel electrode 13 is formed of a mixture of Ni having high electronic conductivity and ZrO ₂ (YSZ) containing Y ₂ O ₃ . The interconnector 17 is made of LaCrO ₃ or the like that has a high electronic conductivity and in which an alkaline earth oxide is dissolved. These materials are preferably close in thermal expansion coefficient.

  Next, the normal operation of the fuel cell system 100 will be described with reference to FIG. First, the control unit 90 opens the flow path that connects the raw fuel supply unit 10 and the dehumidifier 21 to the switching valve 23, and the flow path that connects the dehumidifier 21 and the desulfurizer 22 to the switching valve 24. A flow path connecting the oxidant gas supply unit 40 and the cathode 71 is opened. Thereby, the raw fuel gas is supplied to the reformer 50 through the dehumidifier 21 and the desulfurizer 22 in this order, and the air is supplied to the cathode 71 of the fuel cell 70 without going through the dehumidifier 21 and the desulfurizer 22. The first flow path configuration is realized.

  The raw fuel supply unit 10 causes a required amount of raw fuel gas to flow toward the switching valve 23 in accordance with an instruction from the control unit 90. The switching valve 23 introduces raw fuel gas into the dehumidifier 21. The dehumidifier 21 dehumidifies the raw fuel gas by adsorbing moisture in the raw fuel gas. The raw fuel gas dehumidified by the dehumidifier 21 flows toward the switching valve 24. The switching valve 24 introduces the dehumidified raw fuel gas into the desulfurizer 22. The desulfurizer 22 desulfurizes the raw fuel gas by adsorbing the sulfur component in the dehumidified raw fuel gas. The desulfurized raw fuel gas is supplied to the vaporizer 51 of the reformer 50.

  The flow controller 34 supplies a required amount of reforming water to the vaporization unit 51 of the reformer 50 in accordance with an instruction from the control unit 90. The reforming water is evaporated by the heat received from the combustion chamber 60 in the vaporization unit 51 and supplied to the reforming unit 52. In the reforming unit 52, a steam reforming reaction occurs between the steam and the raw fuel gas using the heat received from the combustion chamber 60. Thereby, fuel gas containing hydrogen gas is generated. The fuel gas generated in the reformer 50 is supplied to the anode 72 of the fuel cell 70. The oxidant gas supply unit 40 causes the required amount of oxidant gas to flow through the switching valve 24 in accordance with an instruction from the control unit 90. The switching valve 24 introduces oxidant gas into the cathode 71. Thereby, power generation is performed in the fuel cell 70.

  The oxidant off-gas discharged from the cathode 71 and the fuel off-gas discharged from the anode 72 flow into the combustion chamber 60. In the combustion chamber 60, the combustible component of the fuel off gas is burned by oxygen in the oxidant off gas. The heat obtained by the combustion is given to the reformer 50 and the fuel cell 70. Thus, in the fuel cell system 100, combustible components such as hydrogen and carbon monoxide contained in the fuel off-gas can be burned in the combustion chamber 60.

  The heat exchanger 81 exchanges heat between the exhaust gas discharged from the combustion chamber 60 and tap water flowing in the heat exchanger 81. Condensed water obtained from the exhaust gas by heat exchange is stored in a condensed water tank 82. The tap water heated by heat exchange is stored in a hot water tank as hot water. The pump 32 supplies the condensed water stored in the condensed water tank 82 to the reformed water tank 31 via the ion exchanger 33 in accordance with an instruction from the control unit 90.

  Through the above normal operation, the fuel cell system 100 continues power generation. In the normal operation, since the sulfur component in the raw fuel gas is removed in the desulfurizer 22, a reduction in the catalytic performance of the reforming catalyst in the reforming unit 52 is suppressed. Thereby, the reforming efficiency fall in the reforming part 52 is suppressed. Moreover, the adhesion of sulfur components in the fuel cell 70 is suppressed. Thereby, a decrease in power generation performance of the fuel cell 70 is suppressed. Moreover, mixing of the sulfur component into the condensed water tank 82 is suppressed. Thereby, the durable performance fall of the ion exchanger 33 is suppressed. In addition, since the moisture in the raw fuel gas is removed in the dehumidifier 21, the inflow of moisture into the desulfurizer 22 is suppressed. Thereby, the fall of the desulfurization capability in the desulfurizer 22 is suppressed.

  When the amount of moisture adsorbed in the dehumidifier 21 increases, the dehumidifying capacity of the dehumidifier 21 decreases. Therefore, when the amount of moisture adsorbed in the dehumidifier 21 increases, it is preferable to perform a regeneration process on the dehumidifier 21. Therefore, in the present embodiment, the regeneration process of the dehumidifier 21 is performed when a condition that requires the regeneration process of the dehumidifier 21 (hereinafter, dehumidifier regeneration condition) is satisfied.

Here, the regeneration process of the dehumidifier 21 refers to a gas having a lower vapor partial pressure than the raw fuel gas or a gas having a higher temperature than the raw fuel gas without supplying the raw fuel gas to the dehumidifier 21 (hereinafter referred to generically). Thus, the dehumidifier regeneration gas) is introduced into the dehumidifier 21. As a dehumidifier regeneration gas, air, inert gas (N ₂ , H ₂ , He, etc.), combustion gas exhausted from the combustion chamber 60, heat exchange with tap water exhausted from the combustion chamber 60 and in the heat exchanger 81 Combustion gas etc. from which moisture has been removed can be used. In the present embodiment, air as the oxidant gas is used as the dehumidifier regeneration gas. By introducing into the dehumidifier 21 a gas having a lower water vapor partial pressure than the raw fuel gas or a gas having a higher temperature than the raw fuel gas, the moisture adsorbed by the adsorbent of the dehumidifier 21 is desorbed. As a result, the dehumidifier 21 is regenerated.

  The dehumidifier regeneration gas has a higher regeneration capability as the water vapor partial pressure is lower than that of the raw fuel gas. The dehumidifier regeneration gas has a higher regeneration capability as the temperature is higher than that of the raw fuel gas. For example, the temperature of the dehumidifier regeneration gas is preferably higher than the temperature of the raw fuel gas supplied to the dehumidifier 21 when the fuel cell 70 is performing the rated operation. Further, as the dehumidifier regeneration gas, a high-temperature gas having a temperature of 100 ° C. or higher due to heat exchange with the fuel cell 70, the reforming unit 52, the vaporizing unit 51, the combustion chamber 60, the combustion gas discharged from the combustion chamber 60, and the like is used. It is preferable.

  Further, when the regeneration process is performed on the dehumidifier 21, the moisture adsorbed by the adsorbent of the dehumidifier 21 is desorbed in a short time, so that the water vapor concentration in the gas discharged from the dehumidifier 21 is instantaneous. To be high. When the raw fuel gas having a high water vapor concentration is supplied to the desulfurizer 22, a problem occurs in the desulfurizer 22. Therefore, by preventing the dehumidifier regeneration gas that has passed through the dehumidifier 21 from flowing into the desulfurizer 22, moisture inflow into the desulfurizer 22 is suppressed.

  In the present embodiment, the control unit 90, when the dehumidifier regeneration condition is satisfied, the flow path connecting the raw fuel supply unit 10 and the desulfurizer 22 to the switching valve 23, the oxidant gas supply unit 40, and the dehumidification. The flow path connecting the dehumidifier 21 and the cathode 71 is opened by the switching valve 24. As a result, the raw fuel gas is supplied to the reformer 50 via the desulfurizer 22 without passing through the dehumidifier 21, and the fuel cell 70 passes through the dehumidifier 21 and does not pass through the desulfurizer 22. A second flow path configuration to be supplied to the cathode 71 is realized.

In this case, the raw fuel gas from the raw fuel supply unit 10 is introduced into the desulfurizer 22 without passing through the dehumidifier 21. The raw fuel gas that has passed through the desulfurizer 22 is supplied to the vaporizer 51 of the reformer 50. Air from the oxidant gas supply unit 40 is introduced into the dehumidifier 21 via the switching valve 23 and supplied to the cathode 71 via the switching valve 24. The regeneration process is performed on the dehumidifier 21 by the above gas flow. As described above, the air as the oxidant gas is heated by the fuel cell 70 and the combustion chamber 60 in the package 61. Therefore, the moisture adsorbed by the adsorbent of the dehumidifier 21 can be efficiently desorbed. Furthermore, since the air that has passed through the dehumidifier 21 is supplied to the cathode 71 without passing through the desulfurizer 22, the inflow of moisture into the desulfurizer 22 is suppressed. Thereby, the malfunction of the desulfurizer 22 is suppressed. Moreover, since the gas used for regeneration of the dehumidifier 21 can be used as the oxidant gas, the apparatus can be simplified.
(Example 1 of dehumidifier regeneration conditions)

  Next, an example of dehumidifier regeneration conditions will be described. In general, the adsorption capacity of the adsorbent decreases as the temperature increases. Therefore, the dehumidifier regeneration condition may be satisfied when the temperature of the adsorbent of the dehumidifier 21 becomes high. Specifically, the dehumidifier regeneration condition may be satisfied when the temperature of the raw fuel gas supplied to the dehumidifier 21 exceeds a predetermined value based on the detection result of the temperature sensor 25.

  FIG. 3 is a diagram showing a flowchart executed in this case. The flowchart of FIG. 3 is executed at a predetermined cycle (for example, every second). As shown in FIG. 3, the control unit 90 determines whether or not the temperature detected by the temperature sensor 25 exceeds a predetermined value (for example, 15 ° C.) (step S1). When it determines with "Yes" in step S1, the control part 90 makes the switching valves 23 and 24 select the 2nd flow-path form mentioned above. Thereby, a reproduction process is performed (step S2). Thereafter, the control unit 90 ends the execution of the flowchart.

  When it determines with "No" in step S1, the control part 90 makes the switching valves 23 and 24 select a 1st flow path form. Thereby, normal operation is implemented (step S3). Thereafter, the control unit 90 ends the execution of the flowchart.

  When it is estimated that the adsorption capacity of the adsorbent of the dehumidifier 21 is reduced by the control according to the flowchart of FIG. 3, the regeneration process of the dehumidifier 21 is performed. Thereby, the dehumidification ability of the dehumidifier 21 can be improved. Furthermore, since the gas discharged from the dehumidifier 21 during the regeneration process of the dehumidifier 21 is not introduced into the desulfurizer 22, the inflow of moisture into the desulfurizer 22 is suppressed. Thereby, the malfunction of the desulfurizer 22 is suppressed.

  In the flowchart of FIG. 3, when the regeneration process is being performed, the predetermined value in step S1 is set low (for example, 10 ° C.), and when the normal operation is being performed, the predetermined value in step S1 is increased. You may set (for example, 15 degreeC). Thereby, it is possible to prevent frequent switching between the regeneration process and the normal operation.

Further, instead of the temperature detected by the temperature sensor 25, the temperature detected by the temperature sensor 26 or the temperature sensor 27 may be used. In particular, since the temperature of the adsorbent of the dehumidifier 21 can be directly detected by using the temperature detected by the temperature sensor 26, the estimation accuracy of the decrease in the adsorbent capacity of the adsorbent of the dehumidifier 21 is improved.
(Example 2 of dehumidifier regeneration conditions)

  If the raw fuel gas contains moisture and the adsorption capacity of the dehumidifier 21 is not lowered, the moisture in the raw fuel gas is adsorbed by the dehumidifier 21. In this case, heat of adsorption is generated. Here, heat generation by adsorption will be described. The phenomenon of adsorption can be defined as a reaction that restricts the freedom of the substance to be adsorbed. Therefore, the free energy of the substance to be adsorbed is released by adsorption. As a result, adsorption material such as silica gel adsorbs the substance to be adsorbed to generate heat of adsorption.

  If attention is paid to this heat of adsorption, it can be estimated whether or not the adsorption capacity of the adsorbent of the dehumidifier 21 is lowered. Therefore, here, it is assumed that the dehumidifier regeneration condition is satisfied when the index value of the calorific value due to adsorption shows a decreasing tendency. Specifically, the temperature of the dehumidifier 21 increases with the generation of heat of adsorption. In other words, if the temperature of the dehumidifier 21 does not increase or the temperature increase width is small even though the raw fuel gas has moisture, the adsorption capacity of the dehumidifier 21 is reduced. Judgment can be made. From the above, the dehumidifier regeneration condition may be satisfied when the temperature increase rate of the adsorbent of the dehumidifier 21 is equal to or less than a predetermined value.

  FIG. 4 is a diagram showing a flowchart executed in this case. The flowchart of FIG. 4 is executed at a predetermined cycle (for example, every second). As shown in FIG. 4, the control unit 90 determines whether or not the rate of increase of the temperature detected by the temperature sensor 26 is less than a predetermined value (for example, 1/60 (° C./second)) (step S11). When it determines with "Yes" in step S11, the control part 90 makes the switching valves 23 and 24 select a 2nd flow-path form. Thereby, a reproduction process is performed (step S12). Thereafter, the control unit 90 ends the execution of the flowchart. In the determination in units of seconds, there is a possibility that the rate of increase of the temperature detected by the temperature sensor 26 varies and the measurement accuracy is lowered. Therefore, in step S11, for example, an average rate of increase for 120 seconds (2 ° C./120 seconds) may be employed.

  When it determines with "No" in step S11, the control part 90 makes the switching valves 23 and 24 select a 1st flow path form. Thereby, normal operation is performed (step S13). Thereafter, the control unit 90 ends the execution of the flowchart.

  When it is estimated that the adsorption capacity of the adsorbent of the dehumidifier 21 is reduced by the control according to the flowchart of FIG. 4, the regeneration process of the dehumidifier 21 is performed. Thereby, the dehumidification ability of the dehumidifier 21 can be improved. Furthermore, since the gas discharged from the dehumidifier 21 during the regeneration process of the dehumidifier 21 is not introduced into the desulfurizer 22, the inflow of moisture into the desulfurizer 22 is suppressed. Thereby, the malfunction of the desulfurizer 22 is suppressed.

  Note that an index value other than the temperature increase rate may be used as the index value of the amount of heat generated by the adsorption. For example, a temperature difference between the outside air temperature and the inside of the dehumidifier 21 may be used. Specifically, when the temperature of the dehumidifier 21 falls within a predetermined value with respect to the outside air temperature, it may be estimated that the adsorption capacity of the adsorbent of the dehumidifier 21 is reduced. For example, in step S11 of FIG. 4, it may be determined whether or not the value obtained by subtracting the temperature detected by the temperature sensor 26 from the temperature detected by the temperature sensor 27 is less than a predetermined value.

  Further, in the dehumidifier 21, the adsorption reaction proceeds from the upstream side in the flow direction of the raw fuel gas. Therefore, when the adsorbable amount of the adsorbent of the dehumidifier 21 has a margin, the temperature of the upstream adsorbent inside the dehumidifier 21 becomes higher than the temperature of the downstream adsorbent. On the other hand, when there is no allowance for the adsorbable amount of the adsorbent in the dehumidifier 21, the temperature difference between the upstream side and the downstream side becomes small. Therefore, the temperature difference between the upstream side adsorbent and the downstream side adsorbent in the flow direction of the raw fuel gas inside the dehumidifier 21 may be used as an index value of the amount of heat generated by the adsorption.

  For example, as shown in FIG. 5, in the dehumidifier 21, a temperature sensor 26a is arranged on the upstream side in the flow direction of the raw fuel gas, and a temperature sensor 26b is arranged on the downstream side. Then, in step S11 of FIG. 4, it may be determined whether or not a value obtained by subtracting the detected temperature of the temperature sensor 26b from the detected temperature of the temperature sensor 26a is less than a predetermined value.

  Note that the flowchart of FIG. 3 may be executed in parallel with the execution of the flowchart of FIG. In this case, even if the dehumidifier regeneration condition in the flowchart of FIG. 4 is not satisfied, the regeneration process for the dehumidifier 21 may be performed if the dehumidifier regeneration condition of the flowchart in FIG. 3 is satisfied. That is, the dehumidifier regeneration condition in the flowchart of FIG. 3 may be prioritized. In this case, the dehumidifying ability of the dehumidifier 21 can be more reliably recovered.

  Further, the selection operation of the first flow path form and the second flow path form is performed based on the temperature increase rate of the adsorbent of the dehumidifier 21 in a predetermined period immediately after switching from the second flow path form to the first flow path form. You may go. Specifically, immediately after switching from the second flow path form to the first flow path form, it is immediately after the regeneration process of the dehumidifier 21 is completed, so that the adsorption reaction of moisture in the raw fuel gas is likely to proceed. . That is, the temperature increase rate of the adsorbent of the dehumidifier 21 should be high. Nevertheless, if the temperature increase rate is lower than a predetermined value, the moisture concentration in the raw fuel gas is low. Therefore, even if the raw fuel gas is supplied to the desulfurizer 22 without going through the dehumidifier 21, a decrease in the desulfurization capacity of the desulfurizer 22 is suppressed.

  FIG. 6 is a flowchart for explaining a specific example. The flowchart of FIG. 6 is executed at a predetermined cycle (for example, every second). As shown in FIG. 6, the controller 90 determines that the rate of increase in the temperature detected by the temperature sensor 26 in a predetermined period immediately after switching from the second flow path configuration to the first flow channel configuration is a predetermined value (for example, 5/120 ( It is determined whether it exceeded (degrees C / sec)) (step S21). When it is determined as “Yes” in Step S21, it is determined that the water vapor concentration in the raw fuel gas is high. Therefore, the control unit 90 causes the switching valves 23 and 24 to continue the first flow path configuration. Thereby, normal operation is performed (step S22). Thereafter, the control unit 90 ends the execution of the flowchart. In the determination in units of seconds, there is a possibility that the rate of increase of the temperature detected by the temperature sensor 26 varies and the measurement accuracy is lowered. Therefore, in step S21, for example, an average rate of increase for 120 seconds (5 ° C./120 seconds) may be employed.

  When it is determined “No” in step S21, it is determined that the water vapor concentration in the raw fuel gas is low. Therefore, the control unit 90 causes the switching valves 23 and 24 to select the second flow path configuration. Thereby, a reproduction process is performed (step S23). Thereafter, the control unit 90 ends the execution of the flowchart.

  By the control according to the flowchart of FIG. 6, when the moisture concentration in the raw fuel gas is low, the raw fuel gas is supplied to the desulfurizer 22 without passing through the dehumidifier 21 to regenerate the dehumidifier 21. it can. Thereby, the dehumidification capability of the dehumidifier 21 can be improved, suppressing the malfunction of the desulfurizer 22.

Moreover, when the temperature increase rate of the dehumidifier 21 in a predetermined period immediately after switching from the second flow channel configuration to the first flow channel configuration is equal to or less than a predetermined value, the regeneration processing time may be lengthened. Thereby, the dehumidifier 21 is fully regenerated.
(Example 3 of dehumidifier regeneration conditions)

  The hue of the adsorbent of the dehumidifier 21 changes as moisture is adsorbed. For example, silica gel turns pink as it adsorbs moisture. Therefore, the dehumidifier regeneration condition may be satisfied when the hue of the adsorbent of the dehumidifier 21 changes by a predetermined amount or more.

  FIG. 7 is a diagram showing a flowchart executed in this case. The flowchart of FIG. 7 is executed at a predetermined cycle (for example, every second). As shown in FIG. 7, the control unit 90 determines whether the hue change amount of the adsorbent of the dehumidifier 21 exceeds a predetermined amount based on the detection result of the optical sensor 28 (step S <b> 31). When it determines with "Yes" in step S31, the control part 90 makes the switching valves 23 and 24 select a 2nd flow-path form. Thereby, a reproduction process is performed (step S32). Thereafter, the control unit 90 ends the execution of the flowchart.

  When it determines with "No" in step S31, the control part 90 makes the switching valves 23 and 24 select a 1st flow path form. Thereby, normal operation is performed (step S33). Thereafter, the control unit 90 ends the execution of the flowchart.

When it is estimated that the adsorption capacity of the adsorbent of the dehumidifier 21 is reduced by the control according to the flowchart of FIG. 7, the regeneration process of the dehumidifier 21 is performed. Thereby, the dehumidification ability of the dehumidifier 21 can be improved. Furthermore, since the gas discharged from the dehumidifier 21 during the regeneration process of the dehumidifier 21 is not introduced into the desulfurizer 22, the inflow of moisture into the desulfurizer 22 is suppressed. Thereby, the malfunction of the desulfurizer 22 is suppressed.
(Example 4 of dehumidifier regeneration conditions)

  As the moisture adsorption amount of the adsorbent of the dehumidifier 21 increases, the dehumidifying ability of the dehumidifier 21 decreases. If the dehumidifying capacity of the dehumidifier 21 decreases, the water vapor concentration in the raw fuel gas discharged from the dehumidifier 21 increases. Therefore, the dehumidifier regeneration condition may be satisfied when the water vapor concentration in the raw fuel gas discharged from the dehumidifier 21 becomes a predetermined value or more.

  FIG. 8 is a diagram showing a flowchart executed in this case. The flowchart of FIG. 8 is executed at a predetermined cycle (for example, every second). As shown in FIG. 8, the control unit 90 determines whether or not the water vapor concentration detected by the water vapor sensor 29 exceeds a predetermined value (step S41). When it determines with "Yes" in step S41, the control part 90 makes the switching valves 23 and 24 select a 2nd flow-path form. Thereby, a reproduction process is performed (step S42). Thereafter, the control unit 90 ends the execution of the flowchart.

  When it determines with "No" in step S41, the control part 90 makes the switching valves 23 and 24 select a 1st flow path form. Thereby, normal operation is implemented (step S43). Thereafter, the control unit 90 ends the execution of the flowchart.

  When it is estimated that the adsorption capacity of the adsorbent of the dehumidifier 21 is reduced by the control according to the flowchart of FIG. 8, the regeneration process of the dehumidifier 21 is performed. Thereby, the dehumidification ability of the dehumidifier 21 can be improved. Furthermore, since the gas discharged from the dehumidifier 21 during the regeneration process of the dehumidifier 21 is not introduced into the desulfurizer 22, the inflow of moisture into the desulfurizer 22 is suppressed. Thereby, the malfunction of the desulfurizer 22 is suppressed.

  In this embodiment, as shown in FIG. 9A, the switching valve 24 is used for bypassing the dehumidifier regeneration gas discharged from the dehumidifier 21, but the present invention is not limited to this. For example, as shown in FIG. 9B, the dehumidifier 21 may be separately provided with a discharge system. For example, a flow rate adjustment valve can be provided instead of the switching valve 24. In this case, the desulfurizer 22 can be bypassed by the dehumidifier regeneration gas discharged from the dehumidifier 21 by reducing the flow rate with the flow rate adjustment valve.

  Moreover, as shown in FIG.9 (c), the discharge system may be separately provided between the dehumidifier 21 and the flow regulating valve. Even in this case, the desulfurizer 22 can be bypassed by the dehumidifier regeneration gas discharged from the dehumidifier 21 by reducing the flow rate with the flow rate adjustment valve.

  In the present embodiment, the fuel cell system 100 includes the temperature sensor 25, the temperature sensor 26, the temperature sensor 27, the optical sensor 28, and the water vapor sensor 29, but is not limited thereto. It is only necessary to provide a sensor necessary for detecting the establishment of the dehumidifier regeneration condition. Accordingly, it is sufficient that at least one of the plurality of sensors is provided.

  Further, in the flowcharts of FIGS. 3, 4, 7, and 8, the regeneration process is performed until the dehumidifier regeneration condition is not satisfied, but the present invention is not limited to this. For example, the normal operation may be selected after a predetermined time (for example, about 10 minutes) has elapsed since the start of the regeneration process.

  In this embodiment, the switching valve 24 functions as a first bypass means for bypassing the desulfurizer 22 to the dehumidifier regeneration gas exhausted from the dehumidifier 21, and the oxidant gas supply unit 40 dehumidifies the dehumidifier regeneration gas. The switching valve 23 functions as a second bypass means for supplying the raw fuel gas to the desulfurizer 22 without passing through the dehumidifier 21, and the switching valves 23, 24 It functions as a channel configuration selection means for selecting either the first channel configuration or the second channel configuration.

  FIG. 10 is a block diagram illustrating an overall configuration of a fuel cell system 100a including a desulfurization system 20a according to the second embodiment. As shown in FIG. 10, the desulfurization system 20 a includes a first desulfurizer 22 a and a second desulfurizer 22 b instead of the desulfurizer 22. The desulfurization system 20a includes three-way valves 41 to 44 and a valve 45.

  In the present embodiment, the switching valve 23 includes the opening of a flow path connecting the raw fuel supply unit 10 and the dehumidifier 21, the flow path connecting the raw fuel supply unit 10 and the three-way valve 41, and the switching valve 24. Switching between opening the flow path connecting the dehumidifier 21 is performed. The switching valve 24 opens the flow path connecting the oxidant gas supply unit 40 and the cathode 71 and the flow path connecting the dehumidifier 21 and the valve 45, and the oxidant gas supply unit 40, the valve 45, and the switching valve 23. And the opening of the flow path connecting the dehumidifier 21 and the cathode 71 are switched.

  The three-way valve 41 includes a flow path connecting the switching valve 23 to the first desulfurizer 22a and the second desulfurizer 22b, a flow path connecting the switching valve 23 and the first desulfurizer 22a, The flow path connecting the 2 desulfurizer 22b is switched. The three-way valve 42 includes a flow path connecting the valve 45 to the first desulfurizer 22a and the second desulfurizer 22b, a flow path connecting the valve 45 and the first desulfurizer 22a, a valve 45 and a second desulfurizer. And a flow path connecting to 22b. The three-way valve 43 switches between a flow path that connects the first desulfurizer 22a and the reformer 50 and a flow path that connects the first desulfurizer 22a to the atmosphere. The three-way valve 44 switches between a flow path that connects the second desulfurizer 22b and the reformer 50 and a flow path that connects the second desulfurizer 22b to the atmosphere.

  Next, the normal operation of the fuel cell system 100a will be described with reference to FIG. First, the control unit 90 opens the flow path that connects the raw fuel supply unit 10 and the dehumidifier 21 to the switching valve 23, and the flow path and the oxidation path that connects the dehumidifier 21 and the valve 45 to the switching valve 24. The flow path connecting the agent gas supply unit 40 and the cathode 71 is opened, and the valve 45 is controlled to open. Thereby, the raw fuel gas is supplied to the reformer 50 through the dehumidifier 21 and the desulfurizer 22 in this order, and the air is supplied to the cathode 71 of the fuel cell 70 without passing through the dehumidifier 21 and the desulfurizer 22. The first flow path configuration is realized.

  The raw fuel supply unit 10 causes a required amount of raw fuel gas to flow toward the switching valve 23 in accordance with an instruction from the control unit 90. The switching valve 23 introduces raw fuel gas into the dehumidifier 21. The dehumidifier 21 dehumidifies the raw fuel gas by adsorbing moisture in the raw fuel gas. The raw fuel gas dehumidified by the dehumidifier 21 flows into the first desulfurizer 22a and the second desulfurizer 22b via the switching valve 24, the valve 45, and the three-way valve 42. The first desulfurizer 22a and the second desulfurizer 22b desulfurize the raw fuel gas by adsorbing a sulfur component in the raw fuel gas. The desulfurized raw fuel gas is supplied to the vaporizer 51 of the reformer 50 via the three-way valves 43 and 44.

  The oxidant gas supply unit 40 causes the required amount of oxidant gas to flow through the switching valve 24 in accordance with an instruction from the control unit 90. The switching valve 24 introduces oxidant gas into the cathode 71. Thereby, power generation is performed in the fuel cell 70. Other operations are the same as those in the first embodiment.

  Through the above normal operation, the fuel cell system 100a continues power generation. In the normal operation, since the sulfur component in the raw fuel gas is removed by the first desulfurizer 22a and the second desulfurizer 22b, a reduction in the catalytic performance of the reforming catalyst in the reforming section 52 is suppressed. Thereby, the reforming efficiency fall in the reforming part 52 is suppressed. Moreover, the adhesion of sulfur components in the fuel cell 70 is suppressed. Thereby, a decrease in power generation performance of the fuel cell 70 is suppressed. Moreover, mixing of the sulfur component into the condensed water tank 82 is suppressed. Thereby, the durable performance fall of the ion exchanger 33 is suppressed. In addition, since moisture in the raw fuel gas is removed in the dehumidifier 21, the inflow of moisture into the first desulfurizer 22a and the second desulfurizer 22b is suppressed. Thereby, the fall of the desulfurization capability in the 1st desulfurizer 22a and the 2nd desulfurizer 22b is suppressed.

  The fuel cell system 100a performs regeneration processing of the dehumidifier 21 when any of the dehumidifier regeneration conditions described in the first embodiment is satisfied. First, the control unit 90 opens the flow path connecting the raw fuel supply unit 10 and the three-way valve 41 and the flow path connecting the switching valve 24 and the dehumidifier 21 to the switching valve 23. A flow path connecting the oxidant gas supply unit 40 and the switching valve 23 is opened. In addition, the control unit 90 causes the three-way valve 41 to open a flow path that connects the switching valve 23 to the first desulfurizer 22a and the second desulfurizer 22b. Further, the control unit 90 controls the valve 45 to be closed. In addition, the control unit 90 opens the flow path connecting the first desulfurizer 22 a and the reformer 50 to the three-way valve 43, and connects the second desulfurizer 22 b and the reformer 50 to the three-way valve 44. Open the flow path. Thereby, the raw fuel gas is supplied to the reformer 50 via the first desulfurizer 22 a and the second desulfurizer 22 b without passing through the dehumidifier 21, and the air is first desulfurized via the dehumidifier 21. A second flow path configuration is realized that is supplied to the cathode 71 of the fuel cell 70 without passing through the vessel 22a and the second desulfurizer 22b.

  In this case, the raw fuel gas from the raw fuel supply unit 10 is introduced into the first desulfurizer 22 a and the second desulfurizer 22 b without passing through the dehumidifier 21. The raw fuel gas that has passed through the first desulfurizer 22 a and the second desulfurizer 22 b is supplied to the vaporizer 51 of the reformer 50. Air from the oxidant gas supply unit 40 is introduced into the dehumidifier 21 and supplied to the cathode 71 without passing through the first desulfurizer 22a and the second desulfurizer 22b. The regeneration process is performed on the dehumidifier 21 by the above gas flow. Since the air passing through the dehumidifier 21 is supplied to the cathode 71 without passing through the first desulfurizer 22a and the second desulfurizer 22b, the inflow of moisture into the first desulfurizer 22a and the second desulfurizer 22b is prevented. It is suppressed. Thereby, the malfunction of the 1st desulfurizer 22a and the 2nd desulfurizer 22b is suppressed. Moreover, since the gas used for regeneration of the dehumidifier 21 can be used as the oxidant gas, the apparatus can be simplified.

  When the adsorption amount of the sulfur component increases in the first desulfurizer 22a and the second desulfurizer 22b, the desulfurization ability of the first desulfurizer 22a and the second desulfurizer 22b is lowered. In this case, the reformer 50 and the fuel cell 70 may be defective due to the outflow of sulfur components from the first desulfurizer 22a and the second desulfurizer 22b. Therefore, it is preferable to regenerate the first desulfurizer 22a and the second desulfurizer 22b before the desulfurization ability of the first desulfurizer 22a and the second desulfurizer 22b is lowered.

  Here, the regeneration treatment of the first desulfurizer 22a and the second desulfurizer 22b refers to a sulfur component partial pressure higher than that of the raw fuel gas without supplying the raw fuel gas to the first desulfurizer 22a and the second desulfurizer 22b. Is a process of introducing a low gas (hereinafter referred to as desulfurizer regeneration gas) into the first desulfurizer 22a and the second desulfurizer 22b. In this embodiment, air as the oxidant gas is used as the desulfurizer regeneration gas. Sulfur adsorbed by the adsorbents of the first desulfurizer 22a and the second desulfurizer 22b is introduced by introducing a gas having a lower sulfur component partial pressure than the raw fuel gas into the first desulfurizer 22a and the second desulfurizer 22b. Components are desorbed. As a result, the first desulfurizer 22a and the second desulfurizer 22b are regenerated.

  First, the case where the desulfurizer regeneration gas is supplied to either the first desulfurizer 22a or the second desulfurizer 22b when the second flow path configuration is selected will be described. When the second flow path configuration is selected, the control unit 90 causes the three-way valve 41 to open a flow path that connects the switching valve 23 and the second desulfurizer 22b. Further, the control unit 90 controls the valve 45 to open, and causes the three-way valve 42 to open a flow path connecting the valve 45 and the first desulfurizer 22a. Furthermore, the control unit 90 causes the three-way valve 43 to open a flow path that leads from the first desulfurizer 22a to the atmosphere.

  In this case, a part of the air supplied to the dehumidifier 21 is supplied to the first desulfurizer 22a. Thereby, the sulfur component adsorbed by the adsorbent of the first desulfurizer 22a is desorbed. The air discharged from the first desulfurizer 22 a is released to the atmosphere via the three-way valve 43. Thereby, inflow of the sulfur component into the reformer 50 and the fuel cell 70 is suppressed.

  In addition, when the second flow path configuration is selected, the control unit 90 causes the three-way valve 41 to open the flow path that connects the switching valve 23 and the first desulfurizer 22a at a predetermined timing. In addition, the control unit 90 controls the valve 45 to open, and causes the three-way valve 42 to open a flow path that connects the valve 45 and the second desulfurizer 22b. Furthermore, the control unit 90 causes the three-way valve 44 to open a flow path that leads from the second desulfurizer 22b to the atmosphere.

  In this case, a part of the air supplied to the dehumidifier 21 is supplied to the second desulfurizer 22b. Thereby, the sulfur component adsorbed by the adsorbent of the second desulfurizer 22b is desorbed. The air discharged from the second desulfurizer 22 b is released to the atmosphere via the three-way valve 44. Thereby, inflow of the sulfur component into the reformer 50 and the fuel cell 70 is suppressed.

  As described above, by alternately performing the regeneration process on the first desulfurizer 22a and the second desulfurizer 22b, both the desulfurization of the raw fuel gas and the regeneration of the first desulfurizer 22a and the second desulfurizer 22b are achieved. can do.

  In addition, when releasing the air used for the regeneration process of the desulfurizer to the atmosphere, if a large amount of sulfur component is released to the atmosphere, a strange odor may be detected. Therefore, it is preferable to perform the regeneration treatment of the desulfurizer under the condition below the detection limit of the off-flavor of the gas released from the desulfurizer. The off-flavor detection limit can be calculated from the integrated supply amount of raw fuel gas to the desulfurizer, the flow rate of the desulfurizer regeneration gas that flows to the desulfurizer during the regeneration process of the desulfurizer, and the like.

For example, when the integrated flow rate of the raw fuel gas supplied from the raw fuel supply unit 10 to the first desulfurizer 22a and the second desulfurizer 22b is less than a predetermined amount (for example, 3 m ³ ), the first desulfurizer 22a and the second desulfurizer 22a 2 When the regeneration treatment is performed on the desulfurizer 22b, it is estimated that the sulfur component concentration in the gas discharged from the first desulfurizer 22a and the second desulfurizer 22b is less than the off-flavor detection limit (for example, 0.1 ppm). Can do.

  FIG. 11 is a diagram illustrating an example of a flowchart for determining the start of the regeneration process of the desulfurizer based on the off-flavor detection limit when the second flow path configuration is selected. As shown in FIG. 11, when the second flow path configuration is selected, the control unit 90 has an integrated flow rate of the raw fuel gas supplied to the first desulfurizer 22a and the second desulfurizer 22b that is less than a predetermined value. It is determined whether or not (step S51).

  When it determines with "Yes" in step S51, the control part 90 controls the three-way valve 42,43,44 and the valve 45, and implements the regeneration process with respect to the 1st desulfurizer 22a and the 2nd desulfurizer 22b alternately. (Step S52). Thereafter, the control unit 90 ends the execution of the flowchart. When it determines with "No" in step S51, the control part 90 makes the switching valves 23 and 24, the three-way valves 42, 43, 44, and the valve 45 select a 1st flow-path form. Thereby, normal operation is performed (step S53). Thereafter, the control unit 90 ends the execution of the flowchart.

  According to the flowchart of FIG. 11, the regeneration process can be performed on the first desulfurizer 22a and the second desulfurizer 22b under the condition that is less than the detection limit of off-flavor. Thereby, the desulfurizer regeneration gas can be released to the atmosphere. If the regeneration process is performed, the integrated flow rate of the raw fuel gas is reset.

  When regeneration processing of the first desulfurizer 22a and the second desulfurizer 22b is performed using air from the oxidant gas supply unit 40, oxygen used for power generation of the fuel cell 70 may be insufficient. Therefore, when the second flow path configuration is selected and the required load required for the fuel cell 70 is less than a predetermined value, regeneration processing of the first desulfurizer 22a and the second desulfurizer 22b is performed. Also good. FIG. 12 is a diagram illustrating an example of a flowchart executed in this case.

  First, in the case where the second flow path configuration is selected, the control unit 90 determines whether or not a predetermined time (for example, 20 hours) has elapsed since the completion of the previous regeneration process (step S61). When it is determined as “Yes” in step S61, the control unit 90 determines whether the required load required for the fuel cell 70 is less than a predetermined value (for example, rated load of the fuel cell 70 × 0.3). Determination is made (step S62).

  When it determines with "Yes" in step S62, the control part 90 controls the three-way valve 42,43,44 and the valve 45, and implements the regeneration process with respect to the 1st desulfurizer 22a and the 2nd desulfurizer 22b alternately. (Step S63). Thereafter, the control unit 90 ends the execution of the flowchart.

  When it determines with "No" in step S62, the control part 90 makes the switching valves 23 and 24, the three-way valves 42, 43, 44, and the valve 45 select a 1st flow path form. Thereby, normal operation is performed (step S64). Thereafter, the control unit 90 ends the execution of the flowchart.

  According to the flowchart of FIG. 12, when the required load of the fuel cell 70 is low, the regeneration process of the first desulfurizer 22a and the second desulfurizer 22b is performed. Thereby, the dehumidifying ability of the first desulfurizer 22a and the second desulfurizer 22b can be improved only by the oxidant gas supply unit 40 without causing the air supply amount to the fuel cell to be insufficient. Therefore, it is not necessary to newly provide a device for supplying the desulfurizer regeneration gas. In step S61, it may be determined whether or not a predetermined time has come. In this case, it is possible to determine whether or not to regenerate the desulfurizer when the power demand generally decreases at midnight or the like.

  In the present embodiment, the regeneration process of the first desulfurizer 22a and the second desulfurizer 22b is performed when the second flow path form is selected, but the present invention is not limited to this. For example, the regeneration process of the first desulfurizer 22a and the second desulfurizer 22b may be alternately repeated independently of the regeneration process of the dehumidifier 21.

  In this embodiment, the switching valve 24 functions as a first bypass means for bypassing the first desulfurizer 22a and the second desulfurizer 22b with the dehumidifier regeneration gas exhausted from the dehumidifier 21, and the oxidant gas supply unit 40. However, it functions as a regeneration means for supplying the dehumidifier regeneration gas to the dehumidifier 21, and the switching valve 23 supplies the raw fuel gas to the first desulfurizer 22a and the second desulfurizer 22b without passing through the dehumidifier 21. It functions as a second bypass means, the switching valves 23 and 24 function as a flow path form selection means for selecting either the first flow path form or the second flow path form, and the three-way valves 43 and 44 as discharge means. Function.

  The above-described embodiments can be applied to any other type of fuel cell such as a solid polymer type, a solid oxide type, and a carbonated molten salt type.

DESCRIPTION OF SYMBOLS 10 Raw fuel supply part 20 Desulfurization system 21 Dehumidifier 22 Desulfurizer 23, 24 Switching valve 25, 26, 27 Temperature sensor 28 Optical sensor 29 Water vapor sensor 30 Reformed water supply part 31 Reformed water tank 32 Pump 33 Ion exchanger 34 Flow controller 40 Oxidant gas supply unit 50 Reformer 51 Vaporization unit 52 Reformer 60 Combustion chamber 61 Package 70 Fuel cell 71 Cathode 72 Anode 73 Electrolyte 80 Heat exchanger 81 Heat exchanger 82 Condensed water tank 90 Controller 100 Fuel cell system

Claims (16)

A dehumidifier comprising an adsorbent that adsorbs the moisture of the raw fuel gas to be reformed into a hydrogen-containing gas;
A desulfurizer for desulfurizing the raw fuel gas dehumidified by the dehumidifier;
Regeneration means for regenerating the dehumidifier by supplying to the dehumidifier a dehumidifier regeneration gas having a lower water vapor partial pressure or higher temperature than the raw fuel gas supplied to the dehumidifier;
When the regeneration means supplies the dehumidifier regeneration gas to the dehumidifier, the desulfurization regeneration gas exhausted from the dehumidifier comprises first bypass means for bypassing the desulfurizer. To desulfurization system.   When the regeneration unit supplies the dehumidifier regeneration gas to the dehumidifier, the regeneration unit includes a second bypass unit that supplies the raw fuel gas to the desulfurizer without passing through the dehumidifier. The desulfurization system according to claim 1.   The regenerator supplies the dehumidifier regenerated gas to the dehumidifier when the temperature of the adsorbent, the temperature of the raw fuel gas, or the outside air temperature exceeds a predetermined value. 2. The desulfurization system according to 2.   The desulfurization according to any one of claims 1 to 3, wherein the regeneration unit supplies the dehumidifier regeneration gas to the dehumidifier when a temperature increase rate of the adsorbent is lower than a predetermined value. system.   The desulfurization system according to claim 1, wherein the dehumidifier regeneration gas is air.   The desulfurization system according to any one of claims 1 to 4, wherein the dehumidifier regeneration gas is heated air.   The desulfurization system according to claim 5 or 6, wherein the first bypass passage supplies the air exhausted from the dehumidifier to a cathode of a fuel cell.   The raw fuel gas is supplied to the reformer through the dehumidifier and the desulfurizer in this order, and the air is supplied to the cathode of the fuel cell without going through the dehumidifier and the desulfurizer. The flow path configuration, and the raw fuel gas is supplied to the reformer via the desulfurizer without passing through the dehumidifier, and the air passes through the desulfurizer via the dehumidifier. The desulfurization system according to claim 7, further comprising: a flow path configuration selection unit that selects any one of the second flow path configurations supplied to the cathode of the fuel cell.   The flow path form selection means selects the first flow path form and the second flow path form based on a temperature increase rate of the adsorbent within a predetermined period immediately after selecting the first flow path form. The desulfurization system according to claim 8.   The regeneration means supplies a desulfurizer regeneration gas having a sulfur component partial pressure lower than that of the raw fuel gas supplied to the dehumidifier to the desulfurizer without passing through the dehumidifier. Item 10. The desulfurization system according to any one of Items 1 to 9.   11. The desulfurization according to claim 10, further comprising discharge means for discharging the desulfurizer regeneration gas discharged from the desulfurizer to the atmosphere when the desulfurizer regeneration gas is supplied to the desulfurizer. system.   The regenerator supplies the desulfurizer regenerative gas to the desulfurizer within a range that satisfies a condition equal to or less than a detection limit of the off-flavor of the raw fuel gas discharged from the desulfurizer. 11. The desulfurization system according to 11.   12. The regeneration unit according to claim 10, wherein the regeneration unit supplies the desulfurizer regeneration gas to the desulfurizer when a required load of a fuel cell to which the hydrogen-containing gas is supplied is lower than a predetermined value. Desulfurization system.   The desulfurization system according to any one of claims 10 to 13, wherein the desulfurizer regeneration gas is air.   The desulfurization system according to any one of claims 10 to 13, wherein the desulfurizer regeneration gas is heated air. In a desulfurization system comprising: a dehumidifier comprising an adsorbent that adsorbs moisture of raw fuel gas to be reformed into hydrogen-containing gas; and a desulfurizer for desulfurizing the raw fuel gas dehumidified by the dehumidifier.
A regeneration step of regenerating the dehumidifier by supplying to the dehumidifier a dehumidifier regeneration gas having a lower partial pressure of water vapor than the raw fuel gas supplied to the dehumidifier;
A bypass step of bypassing the desulfurizer with the dehumidifier regeneration gas exhausted from the dehumidifier when the dehumidifier regeneration gas is supplied to the dehumidifier in the regeneration step. Control method of desulfurization system.

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