JP2009004346A - Reformer, fuel cell system, and shut-down method for reformer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reformer, a fuel cell system, and a stopping method for a reformer capable of shortening a time period from shutdown of the reformer to blocking the supply to utilities. <P>SOLUTION: The reformer 10 has a reforming section 21 for creating reformed gas g containing hydrogen as a main component by reforming a material r for reforming, a heating section 11 for generating reforming heat used for reforming of the material r for reforming, a cooling fluid passage 16 which flows cooling fluid a for cooling the reforming section 21 increased in temperature by the reforming heat, and a control section for controlling whether forced cooling is performed to flow the cooling fluid a in the cooling fluid passage 16 when stopping generation of the reforming gas g or natural cooling for flowing no cooling fluid a is performed. When designating the forced cooling, the time period from a standstill of the reformer to blocking of the supply to the utilities can be shortened. The fuel cell system is formed to include the reformer 10 and a fuel cell. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a reformer, a fuel cell system, and a method for stopping a reformer, and in particular, a reformer, a fuel cell system, and a reformer that can shorten the time from when the reformer stops until maintenance becomes possible. The present invention relates to a method for stopping a reformer.

  A fuel cell that uses hydrogen and oxygen to generate electric power through these electrochemical reactions has attracted attention as an environmentally friendly power generator. Fuel cells require hydrogen for power generation, but they are relatively difficult to obtain because the infrastructure for supplying hydrogen itself is not widespread. In many cases, a fuel cell system in which a reformer that generates reformed gas is provided in the fuel cell is constructed. The reformer has an operating temperature of about 600 ° C. or higher.

If the reformer is left as it is after the fuel cell system is stopped, the internal pressure of the reformer decreases as the temperature drops from about 600 ° C., which is the operating temperature, and the water vapor condenses. When the internal pressure decreases below the specified pressure and outside air enters the reformer, the catalyst in the reformer deteriorates. Therefore, after the fuel cell system is stopped, the reformed gas and steam in the reformer are removed. Purging is generally performed. There is a technique in which this purging is performed with a raw material gas that is a raw material of the reformed gas without using an inert gas that requires a special apparatus (for example, see Patent Document 1).
JP 2003-288930 A

  However, if the raw material gas is introduced into the reformer while the reformer is at a high temperature (generally about 400 ° C. or higher) after the reformer is stopped, hydrocarbons in the raw material gas are thermally decomposed and carbon is precipitated and modified. Since this lowers the performance of the mass device, it is preferable to input the raw material gas after the reformer is no longer in a high temperature state. On the other hand, when the fuel cell system is temporarily stopped and then restarted due to generation of power demand or heat demand, the temperature of the reformer is raised to the operating temperature (about 600 ° C. or higher). Therefore, a means for forcibly cooling the reformer is provided from the viewpoint that it is preferable from the viewpoint of reducing energy consumption that the temperature of the reformer is not lowered as much as possible when temporarily stopped. There is no actual situation. If a means for forcibly cooling the reformer is not provided, utilities for the fuel cell system (in this specification, electricity, gas, water, etc.) may be used when the fuel cell system is not used for a long period of time or for maintenance. Even if it is desired to shut off the supply of the public services such as public services, etc., until the reformer can be purged with the raw material gas, it is necessary to start the auxiliary equipment or use the gas of the gas company as a public service as the raw material gas. As a result, it was impossible to shut off the power supply, and it took a long time until the utility supply could be shut off after the reformer stopped.

  In view of the above-described problems, the present invention provides a reformer that can shorten the time from the stop of the reformer until the utility supply can be cut off, a fuel cell system including the reformer, and a reformer. It aims at providing the stop method of a vessel.

  In order to achieve the above object, a reformer according to the first aspect of the present invention includes a reformed gas g containing hydrogen as a main component by reforming a reforming raw material r as shown in FIG. A heating unit 11 that generates reforming heat used for reforming the reforming raw material r; and a cooling fluid a that cools the reforming unit 21 that has been heated by the reforming heat. A cooling fluid channel 16 to flow; forced cooling to flow the cooling fluid a through the cooling fluid channel 16 when generation of the reformed gas g is stopped, or cooling fluid when generation of the reformed gas g is stopped and a control unit 40 that controls whether natural cooling is performed without flowing a.

  With this configuration, forced cooling is performed to flow the cooling fluid through the cooling fluid flow path when the generation of the reformed gas is stopped, or natural cooling that does not flow the cooling fluid when the generation of the reformed gas is stopped. It is possible to select the stop state of the reformer according to the situation, and when forced cooling is used, for example, the utility supply can be shut off from the stop of the reformer It is possible to shorten the time until it becomes, and in the case of natural cooling, energy consumption can be reduced.

  Further, the reformer according to the second aspect of the present invention is the reformer 10 according to the first aspect, for example, as shown in FIG. 1, wherein the heating unit 11 includes the combustion fuel f and the combustion air a. And the combustion fluid f is burned, and the cooling fluid channel 16 communicates with the heating unit 11 so that the combustion air a flows through the cooling fluid channel 16 during the forced cooling. It is configured.

  With this configuration, since the combustion air is configured to flow through the cooling fluid flow path during forced cooling, the combustion air is used as the cooling fluid, and the apparatus configuration can be simplified. .

  Further, the reformer according to the invention described in claim 3 is, for example, as shown in FIG. 1, in the reformer 10 according to claim 1 or 2, the control unit 40 includes forced cooling and natural cooling. The cooling designation means 45 is provided for accepting manual input as to which of the above is to be performed.

  If comprised in this way, the cooling system when a reformer will be stopped by simple operation can be selected.

  Moreover, the reformer according to the invention of claim 4 is the reformer 10 according to any one of claims 1 to 3, for example, as shown in FIG. Reforming material supply means 31 for supplying the reforming material r; reforming part temperature detection means 42 for detecting the temperature of the reforming part 21; reforming part pressure detection for detecting the internal pressure of the reforming part 21 Means 41; sealing means 35 to 38 for sealing at least one of the reforming raw material r and the reformed gas g in the reforming part 21; and the temperature of the reforming part 21 when the generation of the reformed gas g is stopped. The reformed gas g is sealed in the reforming section 21 until the temperature of the reforming section 21 becomes equal to or lower than a predetermined temperature, and the reforming material r is sealed in the reforming section 21 when the temperature of the reforming section 21 reaches a predetermined temperature or lower. At the same time, the reforming material r is supplied to the reforming unit 21 when the internal pressure of the reforming unit 21 becomes equal to or lower than a predetermined pressure. As to increase the internal pressure of the part 21, and a control unit 40 for controlling the closure means 35-38 and the reforming material supply means 31.

  As described above, when the reforming raw material gas is sealed while the reformer is at a high temperature (about 400 ° C. or higher), the reforming raw material hydrocarbon is pyrolyzed and carbon is precipitated, and the performance of the reformer. May decrease. However, if configured as described in the previous paragraph, deterioration of the reforming catalyst can be prevented while suppressing a decrease in the performance of the reformer.

  Further, the fuel cell system according to the invention described in claim 5 includes a reformer 10 according to any one of claims 1 to 4; a reformed gas g, as shown in FIG. And a fuel cell 60 that generates power by introducing the oxidant gas t.

  If comprised in this way, it will become a fuel cell system which can shorten time until the supply of a utility can be interrupted | blocked from the stop of a reformer.

  In addition, in the fuel cell system according to the invention described in claim 6, for example, as shown in FIG. 2, in the fuel cell system 100 according to claim 5, the fuel cell system 100 is forcedly cooled in preference to natural cooling. A forced cooling start detector 49 for detecting the occurrence of a situation in which the forced cooling start detector 49 detects that a situation in which forced cooling is given priority over natural cooling has occurred. For example, the control apparatus 70 which controls the control part 40 (for example, refer FIG. 1) is provided so that forced cooling may be performed.

  With this configuration, when the forced cooling start detector is forced to perform forced cooling in preference to natural cooling, the control unit is forced to perform forced cooling. It is possible to shorten the time until the utility supply to the fuel cell system can be interrupted.

  In order to achieve the above object, the reformer stopping method according to the invention described in claim 7 is characterized in that, as shown in FIGS. A reforming unit 21 that generates the reformed gas g, a heating unit 11 that generates reforming heat used for reforming the reforming raw material r, and a reforming unit 21 that is heated by the reforming heat. A method of stopping a reformer 10 having a cooling fluid channel 16 for flowing a cooling fluid a to be cooled; a reforming material stopping step (stopping the supply of the reforming material r to the reforming unit 21) A reforming heat stopping step (ST1) for stopping the generation of the reforming heat; and a cooling step (ST4) for flowing the cooling fluid a through the cooling fluid channel 16 to cool the reforming portion 21. .

  If comprised in this way, time until it becomes possible to interrupt | block supply of a utility from the stop of a reformer can be shortened.

  Further, the reformer stopping method according to the invention described in claim 8 is modified to the reforming unit 21 in the reformer stopping method according to claim 7, for example, as shown in FIGS. A reformed gas enclosing step (ST3) for enclosing the gaseous gas g; a reforming portion temperature detecting step (ST5) for detecting the temperature of the reforming portion 21; and the temperature of the reforming portion 21 is equal to or lower than a predetermined temperature. Sometimes, the reforming material g sealed in the reforming unit 21 is replaced with the reforming material r, and the reforming material r is sealed in the reforming unit 21 (ST7). Prepare.

  If comprised in this way, the performance fall of the reformer resulting from the hydrocarbon of the raw material for a reforming being thermally decomposed and carbon depositing can be suppressed.

  Further, the reformer stopping method according to the ninth aspect of the present invention is the reformer stopping method according to the eighth aspect of the present invention, as shown in FIGS. 1 and 3, for example. A reforming section pressure detecting step (ST5) for detecting pressure; when the temperature of the reforming section 21 is equal to or lower than a predetermined temperature and the internal pressure of the reforming section 21 is equal to or lower than a predetermined pressure, the reforming section 21 A boosting step (ST9) of supplying the reforming raw material r to boost the internal pressure of the reforming unit 21.

  If comprised in this way, deterioration of a reforming catalyst can be prevented, suppressing the fall of the performance of a reformer.

  According to the present invention, forced cooling is performed by flowing a cooling fluid through the cooling fluid channel when the generation of the reformed gas is stopped, or natural cooling is performed without flowing the cooling fluid when the generation of the reformed gas is stopped. Since it is provided with a control unit that controls whether or not to perform the forced cooling, it is possible to shorten the time from the stop of the reformer until the utility supply can be cut off.

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

  First, a reformer 10 according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a longitudinal sectional view of the reformer 10. The reformer 10 includes a combustion section 11 as a heating section that generates reforming heat used for steam reforming of a raw material gas r as a reforming raw material, and a semi-reformed gas j by steam reforming the raw material gas r. , A carbon monoxide reduction unit 22 that generates a reformed gas g having a reduced carbon monoxide concentration from the semi-reformed gas j, and exhaust gas e generated in the combustion unit 11 is discharged to the outside. Exhaust gas flow path 16, water pipe 25 for flowing water s used for steam reforming of raw material gas r, and cooling of reformer 10 when the operation of reformer 10 is controlled and the generation of reformed gas g is stopped. A control device 40 having a control unit for controlling the method and an operation panel 45 as a cooling designation means for receiving manual input of a cooling method to be performed by the control device 40 are provided. The carbon monoxide reducing unit 22 converts the carbon monoxide in the semi-reformed gas j into a modified gas h in which the carbon monoxide is reduced from the semi-reformed gas j, and a carbon monoxide reducing unit 22 in the modified gas h. A selective oxidation unit 24 that selectively oxidizes carbon oxide to generate a reformed gas g in which carbon monoxide is further reduced from the modified gas h.

  The combustion unit 11 includes a burner 12 that combusts the combustion fuel f as a combustion fuel, and a combustion chamber 13 that houses a flame generated by the combustion. The combustion chamber 13 is formed inside the inner cylinder 14 that is a cylindrical member. In the present embodiment, the burner 12 is accommodated in the inner cylinder 14, and the combustion chamber 13 is formed by the space at the tip of the burner 12 being surrounded by the inner cylinder 14. In the present embodiment, the inner cylinder 14 is disposed so that its axis is substantially parallel to the vertical direction. The length of the inner cylinder 14 is equal to or longer than the length in the vertical direction of the reforming unit 21 described later. The burner 12 is disposed in the inner cylinder 14 so that the flame is formed downward. The lower end of the inner cylinder 14 is an opening. On the other hand, the upper end 14a of the inner cylinder 14 is closed. The side of the burner 12 opposite to where the flame is formed penetrates the upper end 14 a of the inner cylinder 14 and is connected to the air fuel introduction pipe 29. The air fuel introduction pipe 29 forms a flow path through which the combustion fuel f flows. A cheese 29T is attached to the air fuel introduction pipe 29.

  The inner cylinder 14 is covered with an outer cylinder 15 that is a cylindrical member that is slightly larger than itself. The lower end 15b of the outer cylinder 15 is closed. The outer cylinder 15 is disposed so that its axis substantially coincides with the axis of the inner cylinder 14. Thus, an exhaust gas flow path 16 is formed between the outer side of the inner cylinder 14 and the inner side of the outer cylinder 15 for flowing the exhaust gas e after the combustion fuel f is burned by the burner 12. By supplying the combustion air a as a cooling fluid without supplying the combustion fuel f toward the burner 12, the combustion air a can also flow through the exhaust gas passage 16. That is, the exhaust gas flow channel 16 of the present embodiment also serves as a cooling fluid flow channel. The size of the outer cylinder 15 that is one size larger than the inner cylinder 14 may be appropriately determined in consideration of the flow rates of the exhaust gas e and the combustion air a flowing through the exhaust gas passage 16. The exhaust gas flow channel 16 is connected to the exhaust gas pipe 54 and configured to discharge the exhaust gas e to the outside of the system.

  The reforming unit 21 is configured by providing a reforming catalyst on the outer periphery excluding both ends and the upper portion of the outer cylinder 15. The reforming catalyst is held by a reforming catalyst holding cylinder 17 which is a cylindrical member coaxial with the inner cylinder 14 and the outer cylinder 15. In other words, the reforming catalyst is filled between the outer cylinder 15 and the reforming catalyst holding cylinder 17. The reforming catalyst is a catalyst that promotes the steam reforming reaction of the raw material gas r, and typically a nickel-based reforming catalyst or a ruthenium-based reforming catalyst is used. Further, the shape of the reforming catalyst is preferably granular, columnar, honeycomb, or monolithic in order to efficiently perform the steam reforming reaction. The steam reforming reaction is an endothermic reaction. Therefore, the combustion fuel f is burned in the combustion section 11 to generate reforming heat. The positional relationship between the reforming unit 21 and the burner 12 is configured such that the flame of the burner 12 is positioned approximately at the center in the vertical direction of the reforming unit 21. With such a positional relationship, the entire reforming unit 21 can be heated.

  The lower end of the reforming catalyst holding cylinder 17 is an opening. The reforming part 21 communicates with the transformation part 23 through this opening. On the other hand, the upper end of the reforming catalyst holding cylinder 17 is closed, and a raw material gas introduction pipe 26 for introducing the raw material gas r into the reforming section 21 is connected to a part of the upper end. In the upper part of the reforming part 21, a space not filled with the reforming catalyst is formed so that the source gas r introduced through the source gas introduction pipe 26 reaches the entire upper part of the reforming catalyst holding cylinder 17. . The source gas introduction pipe 26 extends in the direction opposite to the combustion unit 11 (that is, outward). A raw material gas shutoff valve 36 for shutting off the flow of the raw material gas r is disposed in the raw material gas introduction pipe 26. A water pipe 25, which will be described in detail later, is connected to the raw material gas introduction pipe 26 downstream of the raw material gas cutoff valve 36.

  The shift section 23 is configured by providing a shift catalyst on the outer periphery of the outer cylinder 15 above the reforming section 21 while leaving the upper portion of the outer cylinder 15. The shift catalyst also covers the upper part of the reforming catalyst holding cylinder 17. The portion where the shift catalyst covers the reforming catalyst holding cylinder 17 is partitioned by the reforming catalyst holding cylinder 17 and is not in communication with the reforming unit 21. As described above, the shift unit 23 communicates with the reforming unit 21 through the opening at the lower end of the reforming catalyst holding cylinder 17. The shift catalyst is a catalyst that promotes a shift reaction in which carbon monoxide contained in the semi-reformed gas j generated by the steam reforming reaction in the reforming section 21 is reacted with water, and typically iron-chromium. A system shift catalyst, a copper-zinc shift catalyst, a platinum shift catalyst, or the like is used. Further, the shape of the shift catalyst is preferably granular, columnar, honeycomb, or monolithic in order to efficiently perform the shift reaction. The metamorphic reaction shifts carbon monoxide to carbon dioxide. The modification reaction is an exothermic reaction.

  The selective oxidation unit 24 is configured by providing a selective oxidation catalyst on the outer periphery of the outer cylinder 15 above the shift unit 23. The boundary between the selective oxidation unit 24 and the transformation unit 23 may be partitioned by punching metal or the like, but the selective oxidation unit 24 and the transformation unit 23 are configured to communicate with each other. The selective oxidation catalyst is a catalyst that promotes a selective oxidation reaction in which carbon monoxide contained in the shift gas h generated by the shift reaction in the shift section 23 is reacted with oxygen, 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. Further, the shape of the selective oxidation catalyst is preferably a granular shape, a cylindrical shape, a honeycomb shape, or a monolith shape in order to efficiently perform a selective oxidation reaction. The selective oxidation reaction is an exothermic reaction.

  The shift catalyst and the selective oxidation catalyst are held by a CO reduction catalyst holding cylinder 18 which is a cylindrical member coaxial with the inner cylinder 14 and the like. In other words, the shift catalyst is filled between the outer cylinder 15 and a part of the reforming catalyst holding cylinder 17 and the CO reduction catalyst holding cylinder 18, and between the upper part of the outer cylinder 15 and the CO reduction catalyst holding cylinder 18. Are filled with a selective oxidation catalyst. The CO reducing catalyst holding cylinder 18 also extends below the shift unit 23 and covers the lower part of the reforming unit 21. The CO reduction catalyst holding cylinder 18 below the shift section 23 is formed to be slightly larger than the reforming catalyst holding cylinder 17. The lower end 18b of the CO reducing catalyst holding cylinder 18 is closed. The lower end of the reforming catalyst holding cylinder 17 is disposed so as not to contact the lower end 18b of the CO reducing catalyst holding cylinder 18. As a result, the reforming unit 21 and the transformation unit 23 communicate with each other. A quasi-reformed gas flow path 19 through which the quasi-reformed gas j flows is formed between the outside of the reforming catalyst holding cylinder 17 and the inside of the CO reducing catalyst holding cylinder 18 below the shift portion 23. The quasi-reformed gas flow path 19 extends radially outward so that the quasi-reformed gas j is distributed directly below the shift catalyst and over the entire lower surface of the shift catalyst. The size of the CO reducing catalyst holding cylinder 18 that is slightly larger than the reforming catalyst holding cylinder 17 may be determined as appropriate in consideration of the flow rate of the semi-reformed gas j flowing through the semi-reformed gas flow path 19.

  A selective oxidation air introduction pipe 27 for introducing the selective oxidation air c into the selective oxidation unit 24 is connected to the CO reduction catalyst holding cylinder 18 at the selective oxidation unit 24 immediately adjacent to the shift unit 23. The selective oxidation air introduction pipe 27 extends outward. The selective oxidation air introduction pipe 27 is provided with a selective oxidation air shut-off valve 37 that blocks the flow of the selective oxidation air c. The CO reducing catalyst holding cylinder 18 is connected with a reformed gas pipe 28 for deriving the reformed gas g at a selective oxidation unit 24 opposite to the side adjacent to the shift unit 23. The reformed gas pipe 28 extends outward. The reformed gas pipe 28 is provided with a reformed gas shut-off valve 38 that shuts off the flow of the reformed gas g.

  The water pipe 25 is arranged as follows. The outside of the CO reduction catalyst holding cylinder 18 is contacted from above the selective oxidation section 24, and the outside of the CO reduction catalyst holding cylinder 18 is spirally wound downward from above the selective oxidation section 24. When it is spirally wound downward and reaches a position about 2/3 from the top of the transformation section 23, it is separated from the CO reducing catalyst holding cylinder 18 and further turned upward to be connected to the raw material gas introduction pipe 26. To do. The water pipe 25 communicates with the reforming unit 21 by connecting the water pipe 25 to the raw material gas introduction pipe 26. When the water pipe 25 is arranged in this way, the water s flows from the side of the selective oxidation unit 24 to the side of the transformation unit 23 and receives heat from the selective oxidation unit 24 and the transformation unit 23 before flowing into the raw material gas introduction pipe 26. From liquid to gas. As shown in FIG. 1, if a part of the water pipe 25 is disposed so as to pass through the selective oxidation unit 24 and / or the transformation unit 23 and contact the outer cylinder 15, the amount of heat received increases. This is preferable. The water pipe 25 is provided with a water shut-off valve 35 that shuts off the flow of water s upstream from contacting the CO reducing catalyst holding cylinder 18.

  In the semi-reformed gas flow path 19, a pressure sensor 41 is disposed as a pressure detection unit that detects the pressure of the reforming unit 21. Since the reforming unit 21 communicates with the carbon monoxide reduction unit 22 (the transformation unit 23 and the selective oxidation unit 24), the pressure of the carbon monoxide reduction unit 22 is also detected by detecting the pressure of the reforming unit 21. can do. Further, the reforming catalyst holding cylinder 17 and the CO reduction catalyst holding cylinder 18 are attached with temperature sensors 42 as temperature detecting means for detecting the temperatures of the reforming section 21, the shift section 23, and the selective oxidation section 24, respectively. . The number of the temperature sensors 42 may be appropriately determined according to the sizes of the respective parts 21, 23, and 24. Each of the pressure sensor 41 and the temperature sensor 42 is connected to the control device 40 via a signal cable, and is configured to be able to transmit the detected pressure or temperature as a signal to the control device 40.

The outer periphery of the transformation unit 23 and the reforming unit 21 below the lowermost part of the water pipe 25 (in the present embodiment, a position about 2/3 from the top of the transformation unit 23) is covered with a heat insulating material 46. The outer circumferences of the transformation section 23 and the selective oxidation section 24 above the heat insulating material 46 are covered with a heat insulating material 47. Since each part 21, 23, 24 is covered with the heat insulating materials 46, 47, each part 21, 23, 24 can be maintained at a temperature suitable for reaction during operation, and the temperature of the outer periphery of the reformer 10 Can be made lower than the temperature of each part 21, 23, 24, and contribute to burn prevention and the like. Typically, the heat insulating material 46 is obtained by press dehydrating and molding a mixture of a raw material slurry containing a silica raw material, a lime raw material, and water, a heat ray reflective material, heat resistant fibers, and the like at a density of about 500 kg / m ³ or less. It is a molded inorganic porous body. Typically, the heat insulating material 47 is formed by foaming and curing a mixture of silica / alumina-based fine particle powder, alkali metal silicate, hydrogen peroxide, and heat ray reflective material at a density of about 500 kg / m ³ or less. Inorganic foam. The heat insulating materials 46 and 47 are covered with a surface material 48, and the appearance of the reformer 10 is formed in a substantially cylindrical shape. The surface material 48 is typically an inorganic short fiber felt obtained by molding inorganic short fibers into a felt shape.

  The above-described valves 35, 36, 37, 38 and the cheese 29T attached to the air fuel introduction pipe 29 are disposed outside the surface material 48. A source gas pipe 56 is connected to the source gas cutoff valve 36. A raw material gas blower 31 for pumping the raw material gas r is disposed in the raw material gas pipe 56. When the source gas r is pumped from outside the system at the same pressure as when the source gas blower 31 is started, the source gas blower 31 may not be provided. A selective oxidation air pipe 57 is connected to the selective oxidation air shut-off valve 37. The selective oxidation air pipe 57 is provided with a selective oxidation blower 33 for pumping the selective oxidation air c. A reformed gas pipe 68 is connected to the reformed gas shut-off valve 38. A water supply pipe 55 is connected to the water cutoff valve 35. The water supply pipe 55 is provided with a water pump 34 that pumps water s. A combustion fuel pipe 59 for flowing the combustion fuel f is connected to one of the remaining connection ports of the cheese 29T attached to the air fuel introduction pipe 29, and a combustion air pipe 52 is connected to the other remaining connection ports. Is connected. The combustion air pipe 52 is provided with a combustion air blower 32 that pumps the combustion air a.

  The operation panel 45 is disposed outside the surface material 48, and is an apparatus that receives an input of a selection result of whether the cooling method of the reformer 10 is forced cooling or natural cooling. The forced cooling is typically a cooling system in which the combustion air a is allowed to flow as a cooling fluid through the exhaust gas flow channel 16 after the generation of the reformed gas g is stopped to promote a temperature drop of the reformer 10. On the other hand, natural cooling is a cooling method depending on the temperature of the surrounding environment without actively cooling the reformer 10. The operation panel 45 is provided with a button (not shown) that allows a person to select whether the cooling method after stopping the reformer 10 is forced cooling or natural cooling. The buttons provided on the operation panel 45 include, for example, a button for performing forced cooling when the reformer 10 stops, a button for performing natural cooling when the reformer 10 stops, There are a button that immediately shifts to forced cooling even during operation, a button that performs forced cooling after an arbitrary time in the future (for example, a predetermined time after one week), and the like. The button is a concept including what is displayed on a screen such as a touch panel. The operation panel 45 is electrically connected to the control device 40, and is configured to transmit a selection result as a signal to the control device 40.

  The control device 40 is disposed outside the surface material 48 and controls the operation of the reformer 10. The control device 40 receives a pressure signal from the pressure sensor 41 and receives a temperature signal from the temperature sensor 42. The control device 40 transmits an open / close signal to each of the valves 35, 36, 37, and 38 to control the open / close operation of each of the valves 35, 36, 37, and 38. Moreover, the control apparatus 40 adjusts the electric power supplied via the motive power system (not shown) connected to each blower 31, 32, 33, and starts / stops each blower 31, 32, 33, and fluid. Control the discharge rate. In addition, the control device 40 includes a control unit that controls the start and stop of the combustion air blower 32 so as to perform the stop process of the reformer 10 according to the cooling method selected from forced cooling or natural cooling. Yes. The control unit receives a selection signal from the operation panel 45 or a forced cooling start detector, which will be described later, and performs control so that the reformer 10 is stopped according to the selected cooling method. In the present embodiment, the control unit is inseparably integrated with the control device 40, but may be configured separately. In addition, the control device 40 and the operation panel 45 are conceptually illustrated as separate objects, but may be physically configured integrally or may be configured separately.

  Next, a fuel cell system 100 according to a second embodiment of the present invention will be described with reference to FIG. FIG. 2 is a schematic system diagram of the fuel cell system 100. The fuel cell system 100 detects that the reformer 10 described so far, the fuel cell 60 that generates electric power by an electrochemical reaction between hydrogen and oxygen, and a situation in which forced cooling is given priority over natural cooling have occurred. And an abnormality detecting means 49 as a forced cooling start detector.

  The fuel cell 60 is typically a polymer electrolyte fuel cell. The fuel cell 60 includes an anode 61 for introducing the reformed gas g, a cathode 62 for introducing the oxidant gas t, and a cooling unit (not shown) that removes heat generated by the electrochemical reaction. Yes. The oxidant gas t is typically air that has been humidified to a predetermined humidity. Although the fuel cell 60 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 61 and a cathode 62, and a plurality of cells are formed via a cooling unit. It is configured by stacking sheets. In the fuel cell 60, hydrogen in the reformed gas g supplied to the anode 61 is decomposed into hydrogen ions and electrons, and the hydrogen ions pass through the solid polymer film and move to the cathode 62, and the electrons It moves to the cathode 62 through a conducting wire (not shown) connecting to the cathode 62, reacts with oxygen in the oxidant gas t supplied to the cathode 62 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 fuel cell 60 is typically electrically connected to a power conditioner (not shown) that converts DC power into AC power.

  In the anode 61 of the fuel cell 60, not all of the hydrogen in the introduced reformed gas g is used for the above-described electrochemical reaction (power generation in the fuel cell 60), but some hydrogen is used. . From the anode 61, the anode off gas p containing hydrogen that has not been used for the electrochemical reaction in the fuel cell 60 is discharged. The anode off gas p contains hydrogen, carbon dioxide, nitrogen and the like. At the cathode 62 of the fuel cell 60, not all of the oxygen in the introduced oxidant gas t is used for the above-described electrochemical reaction (power generation in the fuel cell 60), but some oxygen is used. . From the cathode 62, the cathode off gas q containing oxygen that has not been used for the electrochemical reaction in the fuel cell 60 is discharged.

  The anode 61 is connected to a reformed gas pipe 68 that supplies the reformed gas g to the anode 61 and an anode offgas pipe 69 that discharges the anode offgas p. The reformed gas pipe 68 is connected to the reformed gas cutoff valve 38. In the reformed gas pipe 68, a reformed gas cutoff valve 88 is disposed. The anode off gas pipe 69 is connected to a combustion fuel pipe 59 downstream of the combustion material shutoff valve 39. The combustion fuel pipe 59 is a pipe branched from the raw material gas pipe 56 between the raw material gas blower 31 and the raw material gas cutoff valve 36. By branching the combustion fuel pipe 59 from the source gas pipe 56, the source gas r can be led to the burner 12 as the combustion fuel f. An anode off gas shutoff valve 89 is disposed in the anode off gas pipe 69. A reformed gas pipe 68 upstream of the reformed gas cutoff valve 88 and an anode offgas pipe 69 downstream of the anode offgas cutoff valve 89 are connected by a bypass pipe 67. A bypass shutoff valve 87 is disposed in the bypass pipe 67. A purge pipe 98 for discharging the gas sealed in the reformer 10 out of the system is connected to the reformed gas pipe 68 between the branch of the bypass pipe 67 and the reformed gas cutoff valve 38. The purge pipe 98 is provided with a purge valve 99 capable of shutting off the gas flow. An oxidant gas pipe 65 that supplies the oxidant gas t to the cathode 62 and a cathode offgas pipe 66 that discharges the cathode offgas q are connected to the cathode 62. The oxidant gas pipe 65 is provided with an oxidant gas blower 64 that pumps the oxidant gas t. The oxidant gas blower 64 may also serve as the combustion air blower 32 and / or the selective oxidation air blower 33.

  The abnormality detection means 49 is a device that detects that an abnormality that should immediately stop the fuel cell system 100 has occurred in the reformer 10 or the fuel cell 60. Examples of the abnormality detection means 49 include a flammable gas leak detector that detects that flammable gas has leaked, a stack voltage drop detector that detects that the power generation voltage of the fuel cell 60 has decreased, and the like. Typically, this is a device that detects an abnormality in the reformer 10 or the fuel cell 60 that requires maintenance by maintenance personnel. In the present embodiment, the abnormality detection means 49 is a device that detects both the abnormality of the reformer 10 and the abnormality of the fuel cell 60, but detects the abnormality of at least one of the reformer 10 and the fuel cell 60. It may be configured.

  The control device 70 controls the fuel cell system 100. The control device 70 is configured to transmit signals to the combustion raw material shut-off valve 39, the bypass shut-off valve 87, the reformed gas shut-off valve 88, and the anode off-gas shut-off valve 89 so as to open and close the respective valves. ing. Further, the control device 70 controls the oxidant gas blower 64. The control device 70 controls the reformer 10 in conjunction with the control device 40 (see FIG. 1) of the reformer 10. Further, the control device 70 can receive the signal from the abnormality detection means 49 and stop the fuel cell system 100 (including the reformer 10 and the fuel cell 60). The control device 70 may be configured integrally with the abnormality detection means 49. Further, the control device 70 may be configured integrally with the control device 40 (see FIG. 1) (that is, the control device 40 (see FIG. 1), the operation panel 45 (see FIG. 1), the control device 70, an abnormality. The detection means 49 may be integrally formed.)

  With continued reference to FIGS. 1 and 2, the operation of the reformer 10 and the fuel cell system 100 will be described. Here, the operation of the reformer 10 will be described as part of the operation of the fuel cell system 100.

  When the fuel cell system 100 is stopped, the valves 35, 36, 37, 38, 88, and 89 are closed. When the fuel cell system 100 is started from a stopped state, the control device 70 opens the combustion material shut-off valve 39 and starts the material gas blower 31 and the combustion air blower 32. Then, the raw material gas r is supplied as the combustion fuel f to the burner 12 in the reformer 10, and the combustion air a is also supplied to the burner 12. The source gas r is typically a chain hydrocarbon such as methane or ethane (including city gas and natural gas), but carbonization of methanol, petroleum products (kerosene, gasoline, naphtha, LPG, etc.), etc. A hydrocarbon-based fuel such as a mixture containing hydrogen as a main component may be vaporized. When the combustion fuel f and combustion air a are supplied to the burner 12, the burner 12 is ignited and the reforming unit 21 is heated. The exhaust gas e generated by the combustion flows through the exhaust gas passage 16 and flows into the exhaust gas pipe 54 and is discharged out of the system. Further, the water shut-off valve 35 is opened and the water pump 34 is activated to feed the water s to the water pipe 25. At substantially the same time, the source gas cutoff valve 36 is opened to supply the source gas r to the source gas introduction pipe 26.

  The water s receives heat from the water pipe 25 and reaches the raw material gas introduction pipe 26 to become water vapor. The steam and the source gas r are mixed in the source gas introduction pipe 26 and reach the reforming section 21. In the reforming unit 21, the hydrocarbon in the raw material gas r and the water vapor vaporized from the water s react with the reforming heat obtained from the combustion unit 11 (steam reforming reaction) and include hydrogen and carbon monoxide. The reformed gas j is generated. When a gas containing carbon monoxide exceeding the allowable amount is supplied to the anode 61 of the fuel cell 60, the electrode catalyst (not shown) of the fuel cell 60 is poisoned, so that the carbon monoxide concentration in the semi-reformed gas j is reduced. Therefore, the semi-reformed gas j generated in the reforming unit 21 is sent to the shift unit 23.

  The semi-reformed gas j sent to the shift unit 23 reacts with the water vapor in which the generated carbon monoxide remains (a shift reaction) to become hydrogen and carbon dioxide. That is, in the metamorphic gas h generated in the metamorphic section 23, carbon monoxide is reduced and hydrogen and carbon dioxide are increased compared to the semi-reformed gas j. Although the modified gas h has a reduced carbon monoxide concentration compared to the semi-reformed gas j, it usually contains about 5,000 to 10000 ppm of carbon monoxide during steady operation, and at this carbon monoxide concentration, the fuel The electrode catalyst of the battery 60 may be poisoned. For this reason, in order to reduce the carbon monoxide concentration in the shift gas h, the shift gas h generated in the shift section 23 is sent to the selective oxidation section 24.

  When the modified gas h is sent to the selective oxidation unit 24, the control device 70 opens the selective oxidation air cutoff valve 37 and the reformed gas cutoff valve 38 and activates the selective oxidation air blower 33 to selectively oxidize the selective oxidation air c. To the unit 24. The selective oxidation air shut-off valve 37 and the reformed gas shut-off valve 38 may be opened and the selective oxidation air blower 33 may be activated simultaneously with the operation of the raw material gas shut-off valve 36 or the like. You may perform after predetermined time passes since opening. Further, the operations of the selective oxidation air cutoff valve 37 and the reformed gas cutoff valve 38 may be performed at different timings.

  In the modified gas h sent to the selective oxidation unit 24, the remaining carbon monoxide reacts with oxygen in the supplied selective oxidation air c (selective oxidation reaction) to become carbon dioxide. The reformed gas g produced by the selective oxidation reaction contains about 10 ppm or less of carbon monoxide in steady operation. With this level of carbon monoxide concentration, it is possible to avoid poisoning of the electrode catalyst of the fuel cell 60.

  In the steady operation of the reformer 10, the reforming unit 21, the shift unit 23, and the selective oxidation unit 24 are in a state where the temperatures are suitable for the reactions in the respective units. The temperature of each part at the time of steady operation is about 550 ° C. to 800 ° C. for the reforming unit 21, about 160 ° C. to 280 ° C. for the transformation unit 23, and about 100 ° C. to 250 ° C. for the selective oxidation unit. When each part 21, 23, 24 has not reached the temperature during steady operation at the initial stage of starting the reformer 10, the composition of the reformed gas g led to the reformed gas pipe 28 is not stable, The electrode catalyst of the fuel cell 60 contains carbon monoxide at a concentration that can be poisoned. Therefore, the reformed gas g whose composition is not stable is not supplied to the anode 61 of the fuel cell 60 but is guided to the combustion unit 11 and combusted as the combustion fuel f.

  The control device 70 opens the bypass shut-off valve 87 and closes the combustion raw material shut-off valve 39 so that the reformed gas g whose composition is not stable is supplied to the reformed gas pipe 68, the bypass pipe 67, and the anode off-gas pipe 69. The burner 12 is supplied from the air fuel introduction pipe 29 via the combustion fuel pipe 59. At this time, the control device 40 detects the temperature of each part 21, 23, 24 by the temperature sensor 42. When the temperature of each part reaches the temperature during steady operation, the control device 70 opens the reformed gas cutoff valve 88 and the anode off-gas cutoff valve 89 and closes the bypass cutoff valve 87. By this valve operation, the reformed gas g is supplied to the anode 61 of the fuel cell 60. When the reformed gas g is supplied to the anode 61, the controller 70 activates the oxidant gas blower 64 and supplies the oxidant gas t to the cathode 62.

In the fuel cell 60, an electrochemical reaction is performed between hydrogen in the reformed gas g introduced into the anode 61 and oxygen in the oxidant gas t introduced into the cathode 62. As for the electrochemical reaction, the reaction represented by the following formula (1) is performed at the anode 61, and the reaction represented by the following formula (2) is performed at the cathode 62.
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 of the anode 61 move to the cathode 62 through an external electric circuit (not shown). Hydrogen ions of the anode 61 pass through the solid polymer film and move to the cathode 62, and combine with oxygen to generate moisture. As mentioned above, this electrochemical reaction is an exothermic reaction.

  The electric power obtained by the fuel cell 60 is direct-current power, which is converted into alternating-current power by a power conditioner (not shown) as necessary and transmitted to an electric power load (not shown). On the other hand, the heat generated in the fuel cell 60 is stored in, for example, a hot water storage tank (not shown) using cooling water (not shown) for cooling the fuel cell 60 as a medium, and in a heat load such as hot water supply or heating as necessary. Is consumed. The hot water storage tank (not shown) may be provided with a heating device (not shown) for reheating (cooking) the stored hot water. When the heating device (not shown) is operated, the cooling water temperature of the fuel cell 60 may exceed an allowable value, so that the power generation of the fuel cell 60 (and generation of the reformed gas g in the reformer 10) is performed. It is preferable to stop immediately. Therefore, since the operation of the heating device (not shown) can be regarded as a situation where forced cooling is given priority over natural cooling, when a heating device (not shown) is provided, it is used as a forced cooling start detector. It is preferable to provide a heating device operation detector (not shown). By effectively using the heat generated in the fuel cell 60, the efficiency of the fuel cell system 100 is improved.

  Also, the cooling water (not shown) for cooling the fuel cell 60 cannot be cooled by the water (warm water) in the hot water storage tank (not shown) so that the operation of the fuel cell 60 can be continued. Therefore, there is a situation in which forced cooling is given priority over natural cooling. Examples of cases where the cooling water (not shown) cannot be cooled by the water in the hot water storage tank (not shown) include cases where it is necessary to drain the water in the hot water storage tank (not shown), A case where an abnormality occurs on the side using heat such as heating and the heat stored in a hot water storage tank (not shown) can no longer be used. For example, when a fluid (hot water or air) leaks in a heating heat exchanger (not shown) that performs heat exchange between hot water derived from a hot water storage tank (not shown) and air used for heating, the heating heat Maintenance of the heating heat exchanger (not shown) is performed by stopping the supply of hot water to the exchanger (not shown), but when the supply of hot water to the heating heat exchanger (not shown) is stopped, the hot water storage tank There is a case where the temperature of the cooling water of the fuel cell 60 becomes an allowable value or higher without the temperature inside (not shown) falling. When the cooling water temperature of the fuel cell 60 exceeds the allowable value, the fuel cell 60 cannot be cooled and power generation cannot be continued. Therefore, the power generation of the fuel cell 60 and, consequently, the reformed gas g in the reformer 10 It is preferable to stop the production promptly. As described above, it is difficult to continue the operation of the fuel cell system 100 (for example, abnormalities that require maintenance by draining water in a hot water storage tank (not shown)) or use heat such as hot water supply or heating. When an abnormality in a secondary device (not shown) such as a device on the side of occurrence occurs, forced cooling is preferably performed. At this time, a secondary side device abnormality detector (not shown) as a forced cooling start detector that detects that an abnormality in which it is difficult to continue the operation of the fuel cell system 100 in the secondary side device (not shown) is provided. It is preferable to provide them together. Note that the abnormality detection means 49 may also serve as a secondary side device abnormality detector (not shown).

  During the operation of the fuel cell 60, the anode off gas p is discharged from the anode 61. The discharged anode off gas p is led to the combustion unit 11 of the reformer 10 and burned as the combustion fuel f. That is, the anode off gas p discharged from the anode 61 flows into the burner 12 from the air fuel introduction pipe 29 via the anode off gas pipe 69 and the combustion fuel pipe 59. By the combustion of the anode off gas p in the combustion unit 11, reforming heat used for reforming in the reforming unit 21 can be generated.

  Next, the operation when the fuel cell system 100 is stopped will be described with reference to the flowchart of FIG. In the example shown in the flowchart of FIG. 3, in the fuel cell system 100, whether the cooling method of the reformer 10 at the time of stop is natural cooling or forced cooling is input in advance via the operation panel 45. When natural cooling is designated, when an instruction to stop the fuel cell system 100 is input to the control device 70, the anode off-gas shut-off valve 89 is closed (the raw material gas r becomes the burner 12 as the combustion fuel f). When the fuel is supplied, the combustion material cutoff valve 39 is also closed), and the supply of the combustion fuel f to the burner 12 is stopped, and the combustion of the burner 12 is stopped (ST1). At the same time, the oxidant gas blower 64 is stopped and the shutoff valve (not shown) is closed to prevent the oxidant gas t from being supplied to the cathode 62. As a result, the solid polymer membrane of the fuel cell 60 is prevented from being dried and the catalyst is prevented from being oxidized, thereby preventing the performance of the fuel cell 60 from being lowered. Also, the blowers 31, 32, 33 and the water pump 34 are stopped, and the water shutoff valve 35, the raw material gas shutoff valve 36, the selective oxidation air shutoff valve 37, and the reformed gas shutoff valve 38 are closed, and the reformer 10 The supply of water s, source gas r, and selective oxidant air c is stopped (ST2). As a result, the reforming unit 21 and the carbon monoxide reduction unit 22 of the reformer 10 are semi-reformed gas j or the like (a gas generated by reforming the raw material gas r in the reformer 10, Gas j, modified gas h, reformed gas g, or a mixed gas thereof) is sealed (ST3). The reformed gas enclosed in the reformer 10 when the reformer 10 is stopped is a concept including not only the reformed gas g but also the semi-reformed gas j and the modified gas h (carbon monoxide). This is a gas in which the raw material for reforming is reformed regardless of the concentration). In this manner, the reforming unit 21 and the carbon monoxide reduction unit 22 are sealed with the semi-reformed gas j or the like and set to a positive pressure from the outside thereof, so that the reforming unit 21 and the carbon monoxide reduction unit 22 are transferred. Intrusion of outside air is prevented, and the reforming catalyst, shift catalyst, and selective oxidation catalyst are prevented from deteriorating due to contact with oxygen. When the fuel cell system 100 is stopped, the reformed gas cutoff valve 88 is also closed. In natural cooling, since the temperature drop of the reformer 10 is smaller than that in forced cooling, the time and energy (fuel) required to raise the temperature to the temperature during steady operation when the fuel cell system 100 is started next time is small. As a result, the time required for the fuel cell system 100 to generate power is shortened.

  On the other hand, when forced cooling is specified, when a command to stop the fuel cell system 100 is input to the control device 70, generation of reforming heat is stopped (ST1), and the reforming unit 21 is instructed. The supply of the reformed gas r is stopped (ST2), and the reforming unit 21 is sealed with the semi-reformed gas j or the like (ST3) as in the case of natural cooling, but in the case of natural cooling in the following points Is different. That is, in the case of forced cooling, the reforming unit 21 is forcibly cooled by supplying the combustion air a to the combustion chamber 13 after the reforming unit 21 is sealed with the semi-reformed gas j (ST3) (ST4). ). In the cooling step (ST4), since the supply of the combustion fuel f to the burner 12 is stopped, the combustion air a supplied to the combustion chamber 13 flows as it is through the exhaust gas passage 16 as a cooling fluid passage and reformed. It is discharged out of the vessel 10. Since the combustion air a is typically outside air, the temperature is significantly lower than the temperature of the reforming section 21 immediately after the stop (about 600 ° C.). Accordingly, when the combustion air a is caused to flow through the exhaust gas passage 16, the time until the temperature of the reformer 21 decreases (the time from when the reformer 10 is stopped to when maintenance is possible) is set for natural cooling. It can be shortened in comparison.

  Note that the forced cooling of the reformer 10 is a button that immediately shifts to forced cooling even when the reformer 10 is in operation, except when forced cooling is selected in advance via the operation panel 45. When forced cooling is selected via the operation panel 45 when the user presses (not shown), when the abnormality detecting means 49 detects abnormality of the reformer 10 or the fuel cell 60, the heating device operation detector It may also occur when (not shown) detects the operation of a heating device (not shown). That is, even if natural cooling has been selected in advance via the operation panel 45, if the user immediately presses a button (not shown) for shifting to forced cooling, the abnormality detection means 49 is used for the reformer 10 or the fuel cell. When the abnormality of 60 is detected, when a heating device operation detector (not shown) detects the operation of the heating device (not shown), a signal indicating that an abnormality has occurred is transmitted to the control device 40 and forced cooling (ST4). ) Is performed.

  By the way, the temperature of the reformer 10 during the steady operation is as described above (for example, about 550 ° C. to 800 ° C. in the reforming unit 21), but the reformer 10 is stopped when the fuel cell system 100 is stopped. Then, the temperature of the reformer 10 decreases. When the temperature of the reformer 10 decreases, the pressure of the reforming unit 21 and the carbon monoxide reduction unit 22 decreases, and when the negative pressure exceeds the allowable value, outside air enters and the catalyst of each unit 21, 22, particularly the shift catalyst, It will deteriorate. In order to prevent this, when the pressures of the reforming unit 21 and the carbon monoxide reduction unit 22 are equal to or lower than a predetermined pressure, the source gas shut-off valve 36 is opened to start the source gas blower 31, and the source unit r is supplied to the reforming unit 21. To prevent pressure drop. If the reforming portion 21 and the like are maintained at a positive pressure using the raw material gas r, special equipment required when using other gases is not required, and the system can be simplified. However, when the hydrocarbon-based raw material gas r is introduced while the reforming section 21 is at a high temperature, the hydrocarbon is thermally decomposed to deposit carbon, and the performance of the reformer 10 is degraded. In order to avoid such an inconvenience, the control device 40 performs the following control.

  The subsequent description of FIG. 3 is common to the case of natural cooling and the case of forced cooling. In the case of natural cooling, after the reforming section 21 is sealed with the semi-reformed gas j or the like (ST3), in the case of forced cooling, the control apparatus 40 detects the temperature sensor after the forced cooling (ST4) of the reforming section 21 is started. 42 detects the temperature of the reforming unit 21 as needed, and the pressure sensor 41 detects the pressure of the reforming unit 21 as needed (ST5). Detection of the temperature and pressure of the reforming unit 21 by the temperature sensor 42 and the pressure sensor 41 (ST5) may be detected at any time immediately after the reformer 10 is stopped or during steady operation of the reformer 10. .

  When the temperature and pressure of the reforming unit 21 are detected (ST5), the control device 40 determines whether or not the temperature of the reforming unit 21 is equal to or lower than a predetermined temperature (ST6). The predetermined temperature is a temperature slightly lower than the temperature at which the raw material gas r undergoes thermal decomposition (a temperature that allows for a margin in the temperature at which the raw material gas r undergoes thermal decomposition), and is, for example, 400 ° C. If the temperature is not lower than the predetermined temperature, detection of the temperature and pressure of the reforming unit 21 at any time (ST5) and determination of whether the temperature of the reforming unit 21 is lower than the predetermined temperature (ST6) are continued. . On the other hand, when the temperature is equal to or lower than the predetermined temperature, the control device 40 activates the raw material gas blower 31 and opens the raw material gas cutoff valve 36, the reformed gas cutoff valve 38, and the purge valve 99 and is enclosed in the reformer 10. The quasi-reformed gas j or the like is replaced with the raw material gas r, and when the raw material gas is replaced, the raw material gas r is sealed in the reformer 10 by closing the raw material gas cutoff valve 36, the reformed gas cutoff valve 38, and the purge valve 99 (ST7).

  When the semi-reformed gas j or the like is sealed in the reformer 10, water vapor remaining in the reformer 10 may be condensed as the temperature decreases. If the condensed water vapor adheres to the catalyst in the reformer 10, the condensed water adhering to the catalyst evaporates when the reformer 10 is started up and heated up next time, and the catalyst may be pulverized by this evaporation. is there. However, by replacing the semi-reformed gas j or the like enclosed in the reformer 10 with the raw material gas r, it is possible to avoid dew condensation in the reformer 10. If the semi-reformed gas j or the like sealed in the reformer 10 is completely replaced with the raw material gas r and the raw material gas r is sealed in the reformer 10, it becomes possible to shut off the utility supply. In the present embodiment, the following control is continued in order to prevent the outside air from entering the reformer 10 due to a pressure drop accompanying a further temperature drop.

  Thereafter, control device 40 determines whether or not the internal pressure of reformer 10 is equal to or lower than a predetermined pressure (ST8). Here, the predetermined pressure is a pressure that allows for a margin in the pressure at which the outside air does not enter the reforming unit 21 and the carbon monoxide reduction unit 22, and is, for example, 15 kPa (gauge pressure) or 20 kPa (gauge pressure). It is. When the water shut-off valve 35, the raw material gas shut-off valve 36, the selective oxidation air shut-off valve 37, and the reformed gas shut-off valve 38 are allowed to have excellent sealing properties, the predetermined pressure is negative (for example, − Up to about 20 kPa (gauge pressure). If not below the predetermined pressure, the process returns to the step of determining whether the internal pressure of the reformer 10 is below the predetermined pressure (ST8). On the other hand, when the pressure is equal to or lower than the predetermined pressure, the control device 40 activates the raw material gas blower 31 and opens the raw material gas cutoff valve 36 to feed the raw material gas r to the reforming unit 21 (ST9). And the control apparatus 40 judges whether the internal pressure of the modification | reformation part 21 was pressure | voltage-rised with the signal from the pressure sensor 41 (ST10). If the pressure is not increased, the feed of the source gas r to the reforming unit 21 is continued (ST9). On the other hand, if the pressure is increased, the process returns to the step of determining whether or not the internal pressure of the reformer 10 is equal to or lower than the predetermined pressure (ST8) and the subsequent steps are continued. In the above-described step of maintaining the internal pressure of the reformer 10 at a predetermined pressure or higher (ST8 to ST10), the raw material gas r is enclosed in the reformer 10, so that the appropriate time is set. For example, the utility supply may be shut off at a time (for example, when it is determined that the internal pressure does not decrease enough to cause the entry of outside air even if the temperature of the reformer 10 decreases).

  In the above description, when the semi-reformed gas j or the like sealed in the reformer 10 is replaced with the raw material gas r (ST7), the reformed gas cutoff valve 38 and the purge valve 99 are opened. The semi-reformed gas j and the like that have been enclosed in the reformer 10 until then are discharged out of the system, but the semi-reformed gas j and the like can be prevented from being discharged out of the system as they are. In this case, the purge pipe 98 and the purge valve 99 need not be provided. In order to prevent the semi-reformed gas j or the like from being discharged out of the system as it is, for example, the semi-reformed gas j or the like enclosed in the reformer 10 may be guided to the combustion unit 11 and burned. However, when the semi-reformed gas j or the like is burned in the combustion section 11, the temperature of the reforming section 21 rises, and when the temperature of the reforming section 21 exceeds 400 ° C., the hydrocarbon component of the substituted raw material gas r is heated. Since there is a possibility of decomposing, the temperature of the reforming section 21 (for example, 170 ° C.) such that the temperature of the reforming section 21 does not exceed 400 ° C. even if the enclosed semi-reformed gas j or the like is burned in the combustion section 11. Degree) may be set to a predetermined temperature in the step (ST6).

  As described above, according to the reformer 10 according to the present invention, it is possible to prevent the internal pressure of the reforming unit 21 and the carbon monoxide reducing unit 22 from being lowered without providing special equipment. Can be prevented. The fuel cell system 100 according to the present invention including such a reformer 10 is a fuel cell system 100 having excellent durability.

  In the above description, the reforming material is the source gas r, but a liquid material may be used as the reforming material. In this case, from the viewpoint of reforming efficiency, it is preferable to provide a vaporizer before vaporizing the liquid reforming raw material into the reforming unit 21.

  In the above description, the heating unit is the combustion unit 11 having the burner 12. However, an electric heater may be provided instead of the burner 12, and reforming heat may be generated by the electric heater. However, if the burner 12 is used, the exhaust gas flow channel 16 can also be used as a cooling fluid flow channel, so that the reformer 10 can be miniaturized and the unit cost of energy required for generating reforming heat is also reduced. This is preferable because it requires less.

  In the above description, the combustion air a is used as the cooling fluid at the time of forced cooling when the reformer 10 is stopped. However, air or gas other than air for other uses may be used, or the cooling fluid. A liquid such as water may be used. Hereinafter, a reformer using water as a cooling fluid will be described with reference to FIG.

  FIG. 4 is a schematic system diagram of a reformer 10A according to the third embodiment of the present invention. As a main difference between the reformer 10A and the reformer 10 (see FIG. 1), the reformer 10A includes a member corresponding to the water pipe 25 (see FIG. 1) in the reformer 10 (see FIG. 1). And a point that an exhaust gas passage 16A that does not pass through the vicinity of the selective oxidation unit 24 is provided instead of the exhaust gas passage 16 (see FIG. 1). In the reformer 10A, a water pipe 83 is provided instead of the water pipe 25 (see FIG. 1). The water pipe 83 is a flow path through which water w as a cooling fluid flows. The water pipe 83 is disposed so as to pass through a portion adjacent to the reforming unit 21, then pass through a portion adjacent to the transformation unit 23, and then pass through a portion adjacent to the selective oxidation unit 25. Here, “adjacent” means that the heat exchange between the adjacent parts (the reforming unit 21 and the like) and the water w in the water pipe 83 is arranged in a certain degree of proximity. The water pipe 83 may be disposed so as to meander at a part adjacent to the part in order to increase the amount of heat exchanged between the part and the water w. In view of the purpose of increasing the amount of heat exchanged, it is assumed that the meandering concept also includes arranging the water pipe 83 in a spiral shape, for example. In addition, in order to increase the heat transfer area in the portion adjacent to the portion, the water pipe 83 in the portion adjacent to the portion is configured to have a large flow area such as a jacket (heat exchanger). It is included in the concept of "

  The tip end of the water pipe 83 extending in a direction opposite to the direction from the portion disposed adjacent to the reforming unit 21 to the transformation unit 23 supplies the reforming water s to the reforming unit 21. It is connected to the leading reforming water pipe 85. In other words, the water pipe 83 and the reforming water pipe 85 are connected at the connection point J1. The end of the reforming water pipe 85 opposite to the connection point J1 is connected to the reforming unit 21. An open / close valve 85v that can block the flow of the reforming water s is inserted into the reforming water pipe 85. The on-off valve 85v is connected to the control device 40 through a signal cable, and is configured to receive a signal from the control device 40 and to open and close the valve.

  Moreover, the forced cooling water pipe | tube 82 which flows the water w inside is connected to the connection point J1. The forced cooling water pipe 82 is an end opposite to the connection point J1 and extends in a direction opposite to the direction from the portion disposed adjacent to the selective oxidation part 25 of the water pipe 83 to the transformation part 23. Is connected to the end of the. In other words, the forced cooling water pipe 82 and the water pipe 83 are connected at the connection point J2. The forced cooling water pipe 82 is provided with an open / close valve 82v that can block the flow of water w. An open / close valve 83v capable of blocking the flow of the water w is inserted and disposed in the water pipe 83 between the connection point J2 and the portion adjacent to the selective oxidation unit 25. The on-off valve 82v and the on-off valve 83v are connected to the control device 40 through signal cables, respectively, and are configured to be able to open and close the valves by receiving signals from the control device 40, respectively.

  Further, a water supply pipe 55 that leads water w from outside the system to the forced cooling water pipe 82 and the water pipe 83 is connected to the connection point J2. The water pump 34 is configured to receive a signal from the control device 40 and adjust the amount of water w introduced into the forced cooling water pipe 82 or the water pipe 83. A cooling water outlet pipe 84 for leading water w out of the reformer 10 is connected to the water pipe 83 between the portion adjacent to the selective oxidation unit 25 and the connection point J2. An on-off valve 84v capable of blocking the flow of water w is inserted and disposed in the cooling water outlet pipe 84. The on-off valve 84v is connected to the control device 40 through a signal cable, and is configured to receive a signal from the control device 40 and to open and close the valve.

  In addition to the configuration provided in the above-described reformer 10 (see FIG. 1), the control device 40 has a valve opening degree (full open and full close) for each of the on-off valves 82v, 83v, 84v, and 85v. A signal for adjusting the opening degree is included. Further, the control device 40 transmits a flow rate adjustment signal for adjusting the flow rate of the fluid (water w) to the water pump 34.

  The reformer 10A operates as follows. In the present embodiment, both the cooling fluid and the reforming water are water. Therefore, both are the same substances, but paying attention to their functions, when water acts as a cooling fluid, it acts as water w and water used for reforming the reforming raw material r. When it is, it is called water s. During the steady operation (operation for generating the reformed gas g), the control device 40 closes the on-off valves 82v and 84v, opens the on-off valves 83v and 85v, and supplies water s to the reforming unit 21. . At this time, the water s flows through the portion adjacent to the selective oxidation unit 24, the portion adjacent to the shift unit 23, and the portion adjacent to the reforming unit 21 in order, and is introduced into the reforming unit 21. Next, when natural cooling is performed when the reformer 10A is stopped, the control device 40 closes the on-off valves 82v, 83v, 84v, 85v, and further stops the water pump 34.

  On the other hand, when forced cooling is performed, the control device 40 closes the on-off valves 83v and 85v and opens the on-off valves 82v and 84v to supply water w to the water pipe 83. At this time, the water w sequentially flows through the part adjacent to the reforming unit 21, the part adjacent to the shift unit 23, and the part adjacent to the selective oxidation unit 24, and is discharged out of the reformer 10 </ b> A through the cooling water outlet pipe 84. Is done. Thus, forced cooling can be performed even if the cooling fluid is water w.

  Hereinafter, an embodiment will be described with reference to FIG. FIG. 5A is a graph showing changes in the temperature T1 of the reforming unit 21, the pressure P1 inside the reforming unit 21, and the flow rate Q1 of the supplied combustion air a when the reformer 10 is stopped by natural cooling. FIG. 5B is a graph showing changes in the temperature T2 of the reforming unit 21, the pressure P2 in the reforming unit 21, and the flow rate Q2 of the supplied combustion air a when the reformer 10 is stopped by forced cooling. In FIG. 5, the temperatures T1 and T2 of the reforming unit 21 are shown by solid lines, the pressures P1 and P2 inside the reforming unit 21 are shown by one-dot chain lines, and the flow rates Q1 and Q2 of the combustion air a are shown by two-dot chain lines.

  During natural cooling (see FIG. 5A), the supply of the combustion air a was stopped when the reformer 10 was stopped. Then, the temperature T1 of the reforming unit 21 and the pressure P1 inside the reforming unit 21 gradually decreased with time. When less than 5 hours have passed since the reformer 10 was stopped, the pressure P1 inside the reforming section 21 became 20 kPa (predetermined pressure in the present embodiment) or less, so the temperature T1 of the reforming section 21 became 400 ° C. or less. The raw material gas r was supplied to the reforming unit 21 and the pressure P1 inside the reforming unit 21 was increased. Note that the flow rate Q1 of the combustion air a is increased in conjunction with the increase in the pressure P1 inside the reforming unit 21. In this embodiment, the raw material gas shutoff valve 36 is closed in consideration of safety. This is because the combustion air a is supplied to the combustion unit 11 to purge the combustion system. The reformed gas g that has been enclosed until then, which will eventually be pushed out of the reformer 10 with the supply of the raw material gas r to the reforming section 21, is guided to the combustion section 11 and burned. Finally, when about 9 hours have passed since the reformer 10 was stopped, the temperature T1 of the reforming section 21 reached about 170 ° C. When this temperature was reached, the reformed gas g enclosed in the reformer 10 was transferred to the combustion section 11. Since the temperature T1 of the reforming section 21 will not exceed 400 ° C. (the temperature at which the hydrocarbons in the raw material gas r may be thermally decomposed) even if it is introduced to and burned, it is enclosed in the reformer 10. The reformed gas g which had been pushed out from the reformer 10 and completely replaced with the raw material gas r was introduced into the combustion section 11 and burned. Even with this combustion, the temperature T1 of the reforming section 21 did not rise above 400 ° C. After about 9 hours had passed since the reformer 10 was stopped, the replacement of the reformed gas g enclosed in the reformer 10 with the raw material gas r was completed, and the supply of the utility could be shut off.

  In forced cooling (see FIG. 5B), the supply amount Q2 of the combustion air a as the cooling fluid was increased from 0 L / min to 65 L / min immediately after the reformer 10 was stopped. Then, the temperature T2 of the reforming section 21 is drastically decreased as compared with the case of natural cooling, and the temperature T2 of the reforming section 21 is about 170 ° C. (to the reformer 10) after about 80 minutes from the stop of the reformer 10. Even if the enclosed reformed gas g is introduced into the combustion section 11 and burned, the temperature T2 of the reforming section 21 exceeds 400 ° C. (temperature at which hydrocarbons in the raw material gas r may cause thermal decomposition). The reformed gas g enclosed in the reformer 10 is extruded from the reformer 10 and completely replaced with the raw material gas r, while the extruded reformed gas g is transferred to the combustion unit 11. Guided and burned. After approximately 80 minutes from the stop of the reformer 10, the replacement of the reformed gas g enclosed in the reformer 10 with the raw material gas r was completed, and the supply of the utility could be shut off. Then, since the temperature T2 of the reforming unit 21 has reached a temperature at which the utility supply can be shut off, the supply of the combustion air a as the cooling fluid is stopped. Thereafter, the temperature T2 of the reforming section 21 gradually decreased with a decrease rate. In the present embodiment, during forced cooling, the pressure P2 inside the reforming section 21 is not increased even if it becomes negative, but this is because each shut-off valve 35, 36, 37, 38 is -20 kPa (gauge pressure). This is because the predetermined pressure is set to -20 kPa (gauge pressure) because it has a sealing property even at a degree. As described above, according to forced cooling, it was confirmed that the time required from the stop of the reformer 10 until the utility supply can be cut off can be significantly shortened (from about 9 hours to about 80 minutes). .

It is a longitudinal section of the reformer concerning a 1st embodiment of the present invention. FIG. 4 is a schematic system diagram of a fuel cell system according to a second embodiment of the present invention. It is a flowchart explaining the control at the time of a reformer stop. FIG. 4 is a schematic system diagram of a reformer according to a third embodiment of the present invention. It is a graph which shows transition of the temperature of the reforming part, the pressure inside the reformer, and the flow rate of combustion air when the reformer is stopped. (A) is for natural cooling, and (b) is for forced cooling.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Reformer 11 Heating part 12 Burner 16 Cooling fluid flow path 21 Reforming part 31 Raw material gas blower 32 Combustion air blower 35 Water shutoff valve 36 Raw material gas shutoff valve 37 Selective oxidation air shutoff valve 38 Reformed gas shutoff valves 40 and 70 Control Device 41 Pressure sensor 42 Temperature sensor 45 Operation panel 49 Abnormality detection means 60 Fuel cell 100 Fuel cell system a Cooling fluid and combustion air f Combustion fuel g Reformed gas r Reforming raw material t Oxidant gas

Claims (9)

A reforming section for reforming the reforming raw material to generate a reformed gas mainly composed of hydrogen;
A heating section for generating reforming heat used for reforming the reforming raw material;
A cooling fluid flow path for flowing a cooling fluid that cools the reforming section that has been heated by the reforming heat;
When the generation of the reformed gas is stopped, forced cooling is performed so that the cooling fluid flows through the cooling fluid flow path, or when the generation of the reformed gas is stopped, natural cooling is performed without flowing the cooling fluid. Or a control unit for controlling
Reformer. The heating unit has a burner for introducing combustion fuel and combustion air to burn the combustion fuel;
The cooling fluid channel is in communication with the heating section and configured to flow the combustion air through the cooling fluid channel during the forced cooling;
The reformer according to claim 1. Cooling designation means for receiving manual input as to whether the control unit performs the forced cooling or the natural cooling;
The reformer according to claim 1 or 2. A reforming material supply means for supplying the reforming material to the reforming section;
Reforming part temperature detecting means for detecting the temperature of the reforming part;
Reforming section pressure detecting means for detecting the internal pressure of the reforming section;
Sealing means for sealing at least one of the reforming material and the reformed gas in the reforming section;
When the generation of the reformed gas is stopped, the reformed gas is sealed in the reforming unit until the temperature of the reforming unit becomes a predetermined temperature or lower, and the temperature of the reforming unit is a predetermined temperature. The reforming raw material is enclosed in the reforming section when the pressure becomes below, and the reforming raw material is supplied to the reforming section when the internal pressure of the reforming section becomes a predetermined pressure or less. And a controller for controlling the sealing means and the reforming raw material supply means so as to increase the internal pressure of the reforming section;
The reformer according to any one of claims 1 to 3. A reformer according to any one of claims 1 to 4;
A fuel cell that generates electricity by introducing the reformed gas and the oxidant gas;
Fuel cell system. A forced cooling start detector for detecting that the forced cooling is performed in the fuel cell system in preference to the natural cooling;
A control device that controls the control unit to cause the control unit to perform the forced cooling when the forced cooling start-up detector detects the occurrence of the forced cooling prior to the natural cooling. And comprising:
The fuel cell system according to claim 5. A reforming unit that reforms the reforming raw material to generate a reformed gas mainly containing hydrogen, a heating unit that generates reforming heat used for reforming the reforming raw material, and the reforming A method of stopping a reformer having a cooling fluid flow path for flowing a cooling fluid that cools the reforming section heated by heat;
A reforming material stopping step of stopping the supply of the reforming material to the reforming section;
A reforming heat stopping step for stopping the generation of the reforming heat;
A cooling step of flowing the cooling fluid through the cooling fluid flow path to cool the reforming unit;
How to stop the reformer. A reformed gas sealing step of sealing the reformed gas in the reforming section;
A reforming section temperature detecting step for detecting the temperature of the reforming section;
When the temperature of the reforming unit becomes a predetermined temperature or lower, the reforming gas enclosed in the reforming unit is replaced with the reforming material, and the reforming material is supplied to the reforming unit. A reforming raw material enclosing step for encapsulating
The method for stopping a reformer according to claim 7. A reforming section pressure detecting step for detecting an internal pressure of the reforming section;
When the temperature of the reforming section is equal to or lower than the predetermined temperature and the internal pressure of the reforming section is equal to or lower than the predetermined pressure, the reforming material is supplied to the reforming section to A boosting step for boosting the internal pressure;
The method for stopping the reformer according to claim 8.

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