Regeneration method for hydrogen generation device and manufacturing method for hydrogen generation device

Abstract

A hydrogen generation device (100) comprises: a heating unit (120); a reforming unit (122) that has a reforming catalyst and generates reformed gas containing hydrogen by reacting steam and a raw material gas by means of heat from the heating unit (120); and a CO reduction unit (123) that has a CO reduction catalyst and reduces the concentration of carbon monoxide contained in the reformed gas by means of heat from the heating unit (120). The catalyst reduction step includes: causing reducing gas to flow to the reforming unit (122) and the CO reduction unit (123) (step S1); alternately repeating a first period for heating the reforming unit (122) by means of heat from the heating unit (120) and a second period for stopping heating by means of the heating unit (120) (step S2).

Description

Method for regenerating hydrogen generation device and method for manufacturing hydrogen generation device

[0001] The present disclosure relates to a method for regenerating a hydrogen generator and a method for manufacturing a hydrogen generator.

[0002] A hydrogen generator that supplies hydrogen gas to a fuel cell is known in a fuel cell system. The hydrogen generator includes a reforming unit that generates a hydrogen-containing gas through a reforming reaction and a CO reduction unit that reduces the concentration of carbon monoxide contained in the hydrogen-containing gas. The reforming unit and the CO reduction unit each include a catalyst inside to ensure highly efficient reactions.

[0003] Patent Document 1 discloses a catalyst reduction method and device for a fuel cell system. In this catalyst reduction method, in a fuel cell power plant equipped with equipment containing a catalyst that requires reduction, one or more measuring means are provided to measure the catalyst temperature of the equipment, the maximum temperature of the catalyst layer in the equipment is estimated based on the detection signal of the temperature measuring means, and the flow rate of the reducing gas is controlled so that the estimated maximum temperature is always below the catalyst allowable temperature.

[0004] Japanese Patent Application Publication No. 6-349509

[0005] The present disclosure aims to improve technology suitable for performing reduction processing while suppressing excessive increases in catalyst temperature in a hydrogen generation device, and in particular to provide technology suitable for efficiently raising the temperature of the CO reduction section while preventing excessive temperature increases in the reforming section to perform catalyst reduction.

[0006] The present disclosure provides a regeneration method for a hydrogen generation device, including a catalyst reduction step of regenerating an oxidized catalyst using a reducing gas, wherein the hydrogen generation device comprises: a heating unit; a reforming unit having a reforming catalyst and reacting steam and a raw material gas with heat from the heating unit to produce a reformed gas containing hydrogen; and a CO reduction unit having a CO reduction catalyst and reducing the concentration of carbon monoxide contained in the reformed gas with heat from the heating unit, wherein the catalyst reduction step includes: flowing the reducing gas through the reforming unit and the CO reduction unit; and alternately repeating a first period in which at least the reforming unit is heated with heat from the heating unit and a second period in which heating by the heating unit is stopped.

[0007] In another aspect, the present disclosure provides a method for manufacturing a hydrogen generation apparatus, the method including a catalyst generation step of reducing a catalyst precursor using a reducing gas, wherein the hydrogen generation apparatus includes: a heating unit; a reforming unit having a reforming catalyst and reacting steam and a raw material gas with heat from the heating unit to generate a reformed gas containing hydrogen; and a CO reduction unit having a CO reduction catalyst and reducing a concentration of carbon monoxide contained in the reformed gas with heat from the heating unit, the catalyst generation step including: flowing the reducing gas through the reforming unit and the CO reduction unit; and alternately repeating a first period during which at least the reforming unit is heated with heat from the heating unit and a second period during which heating by the heating unit is stopped.

[0008] The technology disclosed herein can provide an improved technology suitable for performing reduction processing while suppressing excessive increases in catalyst temperature in a hydrogen generation device, particularly technology suitable for efficiently raising the temperature of the CO reduction section while preventing excessive temperature increases in the reforming section to perform catalyst reduction.

[0009] FIG. 1 is a block diagram showing a schematic configuration of a hydrogen generator and a catalytic reduction device according to a first embodiment; FIG. 2 is a vertical cross-sectional view showing a detailed configuration of the hydrogen generator according to the first embodiment; FIG. 3 is a flowchart showing the catalytic reduction process according to the first embodiment; and FIG. 4 is a vertical cross-sectional view showing a detailed configuration of a hydrogen generator according to a reference embodiment.

[0010] (Knowledge, etc. that formed the basis of the present disclosure) At the time when the inventors conceived the present disclosure, conventional technology included a technique for reducing a catalyst built into a reforming section or CO reduction section of a fuel cell power generation system while heating the catalyst so that it did not rise above its maximum allowable temperature.

[0011] However, in the conventional catalyst reduction method, if an external heating device is installed at each of the locations where the catalyst is installed to raise the temperature, the cost becomes high.

[0012] Under these circumstances, the inventors conducted extensive research with the primary objective of reducing the oxides in the catalyst sealed in the hydrogen generator before shipping. They came up with the idea of ​​using the heating unit for normal operation installed in the hydrogen generator to heat and raise the temperature of the catalyst from the inside, and then injecting reducing gas from upstream of the reforming catalyst unit to reduce both the reforming catalyst and the CO reduction catalyst.

[0013] The inventors then discovered that in order to realize this idea, a heating method using an internal heating section would cause the temperature of the reforming section to rise first, resulting in the temperature of the reforming section exceeding the allowable temperature by the time the CO reduction section reaches the reduction temperature, causing the reforming catalyst to deteriorate.In order to solve this problem, the inventors came up with the subject matter of the present disclosure.

[0014] Therefore, the present disclosure provides an improvement to a technology suitable for performing reduction processing while suppressing excessive increases in catalyst temperature in a hydrogen generation device, in particular a technology suitable for efficiently raising the temperature of the CO reduction section while preventing excessive temperature increases in the reforming section to perform catalyst reduction.

[0015] Hereinafter, embodiments will be described in detail with reference to the drawings. However, unnecessary detailed description may be omitted. For example, detailed description of already well-known matters or redundant description of substantially the same configuration may be omitted.

[0016] The accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter recited in the claims.

[0017] First Embodiment Hereinafter, a first embodiment will be described with reference to FIGS. 1 to 4. FIG.

[0018] [1-1. Configuration] (Schematic configuration of hydrogen generation device 100 and catalytic reduction device 200) Fig. 1 is a block diagram showing a schematic configuration of a hydrogen generation device 100 and catalytic reduction device 200 according to embodiment 1. The hydrogen generation device 100 is a device that supplies hydrogen gas in, for example, a fuel cell system.

[0019] In FIG. 1, the hydrogen generator 100 includes a heating section 120, an evaporating section 121, a reforming section 122, a CO reducing section 123, and a housing section 190 that houses these sections.

[0020] The heating unit 120 is a burner that burns combustible gas. The burner burns fuel gas, which is a mixture of combustion air and fuel, and discharges combustion exhaust gas. During hydrogen production, a hydrocarbon-containing raw material gas and water are supplied to the evaporation unit 121. The evaporation unit 121 heats the water and raw material gas using heat from the heating unit 120.

[0021] The reforming unit 122 generates a reformed gas containing hydrogen by subjecting the steam from the evaporating unit 121 and the raw material gas to a steam reforming reaction. The temperature suitable for the steam reforming reaction in the reforming unit 122 is, for example, in the range of 600°C to 700°C. The steam reforming reaction is an endothermic reaction. The reforming unit 122 is configured to be heated so that it can be maintained at a high temperature even when the endothermic reaction is occurring. Specifically, the reforming unit 122 and the heating unit 120 are disposed adjacent to each other so that heat exchange is possible. The reforming unit 122 contains a reforming catalyst (not shown) therein to perform the reforming reaction with high efficiency. The reforming catalyst is, for example, a catalyst containing Ni. The reforming unit 122 is provided with a first temperature sensor 205 that detects the temperature of the reforming catalyst. In this embodiment, the first temperature sensor 205 is a thermocouple.

[0022] The CO reduction unit 123 reduces the concentration of carbon monoxide contained in the reformed gas through a CO shift reaction. The temperature of the CO reduction unit 123 is maintained at a temperature suitable for the CO shift reaction (for example, in the range of 200°C to 300°C) during hydrogen generation. Specifically, the CO reduction unit 123 is disposed downstream of the reforming unit 122 so as not to directly exchange heat with the heating unit 120. Specifically, the CO reduction unit 123 is disposed farther away from the heating unit 120 than the reforming unit 122. The CO reduction unit 123 includes a CO reduction catalyst (not shown) therein to perform the shift reaction with high efficiency. The CO reduction catalyst is, for example, a catalyst containing Cu. The CO reduction unit 123 is provided with a second temperature sensor 206 that detects the temperature of the CO reduction catalyst. In this embodiment, the second temperature sensor 206 is a thermocouple.

[0023] Hereinafter, the reforming catalyst of the reforming section 122 and the CO reduction catalyst of the CO reduction section 123 may be collectively referred to simply as the "catalyst." For convenience, the process of generating hydrogen in the hydrogen generation device 100 may be referred to as normal operation to distinguish it from the catalyst reduction process in the hydrogen generation device 100.

[0024] Next, the equipment used for normal operation and catalytic reduction treatment in the hydrogen generation device 100 will be described.

[0025] The raw material gas supply unit 300 is a facility used in normal operation. The raw material gas supply unit 300 supplies raw material gas to the hydrogen generation apparatus 100 (specifically, to the evaporation unit 121). In this embodiment, the raw material gas is a gas containing hydrocarbon. In this embodiment, the raw material gas supply unit 300 is a raw material gas source such as a city gas infrastructure or a gas cylinder. The raw material gas supply path 302 is a path for supplying raw material gas from the raw material gas supply unit 300 to the evaporation unit 121. A raw material gas supply valve 301 is arranged in the raw material gas supply path 302. The raw material gas supply valve 301 is a flow rate control valve that controls the flow rate of the raw material gas supplied to the evaporation unit 121.

[0026] The reducing gas supply unit 201 is equipment used in the catalytic reduction process. The reducing gas supply unit 201 supplies a reducing gas to the hydrogen generation apparatus 100 (specifically, to the evaporation unit 121). The reducing gas is a reducing gas different from the raw material gas. In this embodiment, the reducing gas is a hydrogen-containing gas. The hydrogen-containing gas in this embodiment is a gas containing hydrogen at a concentration suitable for the reduction reaction of a catalyst, which is an oxide. Although hydrogen is contained in the atmosphere, the air that flows into the hydrogen generation apparatus 100 is not included in the reducing gas. This is because the hydrogen concentration in the atmosphere is low and therefore not suitable for the reduction reaction of the catalyst. The hydrogen concentration in the hydrogen-containing gas is, for example, 1% by volume or more and 100% by volume or less. The hydrogen concentration may also be 10% by volume or more and 100% by volume or less. When the hydrogen concentration is less than 100% by volume, for example, a hydrogen-containing gas diluted with nitrogen can be used. In this embodiment, the reducing gas supply unit 201 is a hydrogen cylinder. In another example, the reducing gas supply unit 201 is a hydrogen supply facility (hydrogen station) installed in a factory. The reducing gas supply path 207 is a path for supplying reducing gas from the reducing gas supply unit 201 to the evaporation unit 121. A reducing gas supply valve 203 is disposed in the reducing gas supply path 207. The reducing gas supply valve 203 is a flow rate control valve that controls the flow rate of the reducing gas supplied to the evaporation unit 121.

[0027] The water supply unit 202 is a facility used in normal operation and catalytic reduction treatment. The water supply unit 202 supplies water to the hydrogen generation apparatus 100 (specifically, to the evaporation unit 121). In this embodiment, the water supply unit 202 is a pump. The water supply path 208 is a path for supplying water to the evaporation unit 121. A water supply valve 204 is disposed in the water supply path 208. The water supply valve 204 is a flow rate control valve that controls the flow rate of water supplied to the evaporation unit 121.

[0028] The fuel supply unit 180 is equipment used in normal operation and catalytic reduction treatment. The fuel supply unit 180 supplies fuel gas to the burner of the heating unit 120. The fuel supply path 184 is a path for supplying fuel from the fuel supply unit 180 to the burner of the heating unit 120. A fuel supply valve 182 is disposed in the fuel supply path 184. The fuel supply valve 182 is a flow control valve that controls the flow rate of fuel supplied to the burner of the heating unit 120.

[0029] The combustion air supply unit 181 is equipment used in normal operation and catalytic reduction treatment. The combustion air supply unit 181 supplies combustion air to the burner of the heating unit 120. In this embodiment, the combustion air supply unit 181 is a blower. The combustion air supply path 185 is a path for supplying combustion air from the combustion air supply unit 181 to the burner of the heating unit 120. A combustion air supply valve 183 is disposed in the combustion air supply path 185. The combustion air supply valve 183 is a flow control valve that controls the flow rate of fuel supplied to the burner of the heating unit 120.

[0030] The hydrogen generator 100 is equipped with a control device (not shown) for performing normal operation. The control device controls control targets such as the fuel supply valve 182, the combustion air supply valve 183, the water supply valve 204, and the raw material gas supply valve 301, but details thereof will be omitted.

[0031] Next, a description will be given of the schematic configuration of the catalytic reduction device 200. The catalytic reduction device 200 is a device for performing catalytic reduction processing in the hydrogen generation device 100. In FIG.

[0032] The control unit 210 controls controlled objects such as the fuel supply valve 182, the combustion air supply valve 183, the reducing gas supply valve 203, and the water supply valve 204. Detection signals from various sensors such as a first temperature sensor 205 and a second temperature sensor 206 are input to the control unit 210. A DSP (Digital Signal Processor) including an A / D conversion circuit, an input / output circuit, an arithmetic circuit, a storage device, etc. can be used as the control unit 210. A program for performing catalytic reduction processing (described in detail below) is stored in the control unit 210.

[0033] (Detailed Configuration of the Hydrogen Generator 100) The detailed configuration of the hydrogen generator 100 will be described with reference to Fig. 2. In Fig. 2, the hydrogen generator 100 includes a heating section 120, an evaporating section 121, a reforming section 122, a CO reducing section 123, a combustion tube 130, a heating section partition wall 131, a first partition wall 132, and a second partition wall 133.

[0034] The heating section 120 is a burner that burns combustible gas. The burner burns fuel gas, which is a mixture of combustion air and fuel, and discharges combustion exhaust gas. The burner forms a downward flame. The combustion chamber 130 surrounds the heating section 120. An air supply pipe 134 is provided at the upper end of the combustion chamber 130. The air supply pipe 134 leads to the interior of the combustion chamber 130. The heating section partition wall 131 surrounds the combustion chamber 130. The heating section partition wall 131 is coaxial with the combustion chamber 130. A combustion exhaust gas flow path 140 is provided between the combustion chamber 130 and the heating section partition wall 131. Heat from the burner of the heating section 120 and heat from the combustion exhaust gas are applied to the heating section partition wall 131. An outlet pipe 155 is provided above the heating section partition wall 131. The combustion exhaust gas is discharged from the outlet pipe 155.

[0035] The first partition wall 132 is cylindrical. The first partition wall 132 surrounds the heating unit partition wall 131. The first partition wall 132 is coaxial with the heating unit partition wall 131. The first partition wall 132 includes an upper portion and a lower portion. The diameter of the lower portion is larger than the diameter of the upper portion. A gap is provided between the first partition wall 132 and the heating unit partition wall 131. The first partition wall 132 is a metal member. A supply pipe 145 is connected to the first partition wall 132. In normal operation, a raw material gas and water are supplied to the supply pipe 145. On the other hand, in the catalytic reduction process, a reducing gas and water are supplied to the supply pipe 145 (see FIG. 2 ). The reducing gas and water are supplied to the evaporation unit 121.

[0036] The evaporation section 121 is provided upstream between the heating section partition wall 131 and the first partition wall 132. A rod-shaped body 135 is disposed between the first partition wall 132 and the heating section partition wall 131. The rod-shaped body 135 is bent in a spiral shape. The rod-shaped body 135 has a spiral structure. The spiral structure functions as a partition that spirally separates the area inside the upper portion of the first partition wall 132 and the area outside the upper structure of the heating section partition wall 131. This defines a space 171. The upper portion of the first partition wall 132, the upper structure of the heating section partition wall 131, the rod-shaped body 135, and the space 171 constitute the evaporation section 121. During normal operation, source gas and water flow in the space 171 of the evaporation section 121, and the water evaporates into steam due to heat transferred from the heating section partition wall 131. On the other hand, in the catalytic reduction process, reducing gas and water flow in the space 171 of the evaporation section 121, and the water evaporates into steam due to the heat transferred from the heating section partition wall 131.

[0037] The reforming section 122 is provided downstream between the heating section partition wall 131 and the first partition wall 132. A space 172 is provided between the lower structure 162 of the heating section partition wall 131 and the lower portion of the first partition wall 132. A reforming catalyst is filled in the space 172. The reforming section 122 is composed of the lower structure 162, the lower portion of the first partition wall 132, the space 172, and the reforming catalyst. The reforming section 122 is heated by heat transmitted from the heating section partition wall 131. During normal operation, the raw material gas and steam flowing out from the evaporation section 121 flow through the space 172 of the reforming section 122. The reforming catalyst generates a reformed gas containing hydrogen from a mixed gas of the raw material gas and steam through a reforming reaction. The reformed gas is a hydrogen-containing gas containing carbon monoxide. On the other hand, in the catalytic reduction process, the reducing gas and steam flowing out from the evaporator 121 flow in the space 172 of the reformer 122. The reforming catalyst is activated by a reduction reaction caused by the mixed gas of the reducing gas and steam.

[0038] The second partition wall 133 has a cylindrical shape with a bottom. The second partition wall 133 accommodates the heating section 120, the evaporation section 121, the reforming section 122, and the CO reduction section 123. Therefore, the second partition wall 133 corresponds to the accommodation section 190 in FIG. 1 . The second partition wall 133 is coaxial with the first partition wall 132. The second partition wall 133 includes an upper portion, a lower portion, and a bottom portion. The diameter of the lower portion is smaller than the diameter of the upper portion. The second partition wall 133 is made of a metal member. The lower portion of the second partition wall 133 surrounds the lower portion of the first partition wall 132. A gap through which a fluid flows is provided between the bottom of the second partition wall 133 and the lower end of the first partition wall 132. A return flow path 141 is provided between the lower portion of the second partition wall 133 and the lower portion of the first partition wall 132. In normal operation, the return flow path 141 redirects the flow of reformed gas flowing downward from the reforming section 122 upward and guides it to the CO reduction section 123. On the other hand, in catalytic reduction treatment, the return flow path 141 redirects the flow of reducing gas and water vapor flowing downward from the reforming section 122 upward and guides it to the CO reduction section 123.

[0039] The CO reduction section 123 is provided between the first partition wall 132 and the second partition wall 133, and is located more outer circumferentially than the evaporator section 121 and the reformer section 122. The heat transfer buffer tube 104 surrounds the upper portion of the first partition wall 132. The heat transfer buffer tube 104 is coaxial with the first partition wall 132. The second partition wall 133 is coaxial with the heat transfer buffer tube 104. The upper portion of the second partition wall 133 surrounds the heat transfer buffer tube 104. A space 173 is provided between the upper portion of the second partition wall 133 and the heat transfer buffer tube 104. The CO reduction section 123 is provided in the space 173. The CO reduction section 123 is filled with a CO reduction catalyst. An outlet pipe 154 is provided to the second partition wall 133. The CO reduction section 123 is heated by the heat of the steam. During normal operation, the CO reduction unit 123 reduces the concentration of carbon monoxide contained in the reformed gas through a shift reaction. The reformed gas with reduced carbon monoxide is discharged from the outlet pipe 154. On the other hand, during catalytic reduction processing, the reducing gas and steam flowing out of the reforming unit 122 through the space 173 of the CO reduction unit 123. The CO reduction catalyst is activated by the reduction reaction of the mixed gas of the reducing gas and steam. The reduced gas is discharged from the outlet pipe 154.

[0040] 1 to 3, the operation of the catalytic reduction device 200 will be described. The catalytic reduction method is carried out in the hydrogen generator 100 by operating the catalytic reduction device 200. The catalytic reduction method of the first embodiment is carried out on the oxide of the catalyst sealed in the hydrogen generator 100 before shipment. In the catalytic reduction method of the first embodiment, the catalytic reduction process is carried out without supplying a raw material gas, unlike normal operation.

[0041] 3 is a flowchart showing the catalyst reduction process of the first embodiment. In the catalyst reduction process, the control unit 210 uses the first temperature sensor 205 to control the fuel supply valve 182, the combustion air supply valve 183, the reducing gas supply valve 203, and the water supply valve 204 (see FIG. 1). From the viewpoint of preventing catalyst deterioration, the control unit 210 monitors the detection signals of the first temperature sensor 205 and the second temperature sensor 206 during the catalyst reduction process to ensure that the temperatures of the reforming catalyst and the CO reduction catalyst do not exceed their respective allowable temperatures.

[0042] First, the reducing gas supply unit 201 starts supplying reducing gas (step S1 in FIG. 3 ). Specifically, the control unit 210 opens the reducing gas supply valve 203 to cause the reducing gas supply unit 201 to start supplying reducing gas (see FIG. 1 ). This causes reducing gas to be supplied to the hydrogen generator 100. The reducing gas is supplied to the evaporation unit 121 through the supply pipe 145 (see FIG. 2 ). The reducing gas flows into the reforming unit 122. The reducing gas then flows into the return flow path 141, flows upward, and is supplied to the CO reduction unit 123. In this way, a flow of reducing gas is formed in the order of the evaporation unit 121, the reforming unit 122, and the CO reduction unit 123. The reducing gas passes through the space 173 and the outlet pipe 154 in this order and is discharged to the outside of the hydrogen generator 100.

[0043] Next, the heating unit 120 starts intermittent operation. In intermittent operation, the heating unit 120 alternately repeats a first period (step S2 in FIG. 3 ) in which the reforming unit 122 is heated by heat from the heating unit 120 and a second period (step S3 in FIG. 3 ) in which heating by the heating unit 120 is stopped. Specifically, in the first period, the control unit 210 opens the fuel supply valve 182 and the combustion air supply valve 183 so as to combust the burner of the heating unit 120 (see FIG. 1 ). Hereinafter, the first period may be referred to as a combustion continuation period. In the second period, the control unit 210 closes the fuel supply valve 182 so as to stop combustion in the burner of the heating unit 120 (see FIG. 1 ). Hereinafter, the second period may be referred to as a combustion stop period. Throughout the first and second periods, the flow rate of the reducing gas is maintained constant during intermittent operation.

[0044] Hereinafter, the ratio between the length of the first period (combustion continuation period) and the length of the second period (combustion stop period) in intermittent operation will be referred to as the duty ratio. The duty ratio is set to, for example, 2:5. In the catalyst reduction process of this embodiment, the duty ratio is set to a fixed value.

[0045] In the first period (step S2 in FIG. 3 ), combustion of the burner in the heating unit 120 generates combustion exhaust gas. The combustion exhaust gas flows downward along the inner circumferential side of the combustion liner 130 (see FIG. 2 ). Next, the combustion exhaust gas passes through the gap between the bottom of the heating unit partition wall 131 and the lower end of the combustion liner 130 and turns back upward. Next, while flowing through the combustion exhaust gas flow path 140, the combustion exhaust gas exchanges heat with the reforming unit 122 and then with the evaporating unit 121. Finally, the combustion exhaust gas is discharged from the outlet pipe 155 to the outside of the hydrogen generator 100.

[0046] Furthermore, during the first period (step S2 in FIG. 3 ), the reducing gas supplied to the evaporator 121 is heated by heat from the heater 120. The reducing gas heated in the evaporator 121 flows to the reformer 122 and the CO reducer 123. The reformer 122 is heated by the heater 120. When the temperature of the reforming catalyst is raised to the reduction temperature, the reducing gas promotes the reduction reaction of the reforming catalyst. In this specification, the reduction temperature of the catalyst is the temperature at which the reduction reaction is promoted by the temperature increase of the catalyst and the reforming catalyst is activated by the reduction reaction. The reforming catalyst causes the reaction of the following chemical formula to occur in response to the reducing gas: NiO2 + 2H2 → Ni + 2H2O The reduction reaction converts the oxide into a zero-valent metal, activating it. This reduces the reforming catalyst to a metallic state.

[0047] The reforming section 122 is disposed adjacent to the heating section 120 so as to be able to exchange heat with it (see FIGS. 1 and 2). For this reason, the reforming section 122 heats up more easily than the CO reduction section 123. In the heating section 120, the burner is repeatedly turned on and off (step S2 in FIG. 3) to prevent the temperature of the reforming catalyst in the reforming section 120 from rising excessively.

[0048] On the other hand, the CO reduction unit 123 is disposed farther away from the heating unit 120 than the reforming unit 122 so as not to directly exchange heat with the heating unit 120 (see FIGS. 1 and 2). For this reason, the CO reduction unit 123 heats up more slowly than the reforming unit 122. In the heating unit 120, the burner is repeatedly turned on and off (step S2 in FIG. 3) so that the heated reducing gas flows through the evaporator unit 121, the reforming unit 122, and the CO reduction unit 123 in that order, and the heat of the heated reducing gas is transported to the CO reduction unit 123. As a result, the temperature of the CO reduction catalyst in the CO reduction unit 123 gradually increases.

[0049] During the first period (step S2 in FIG. 3 ), while combustion is performed by the burner, the water supply unit 202 supplies water to the evaporation unit 121. Specifically, the control unit 210 opens the water supply valve 204 to cause the water supply unit 202 to supply water (see FIG. 1 ). As a result, water is supplied to the hydrogen generator 100. The water is supplied to the evaporation unit 121 through the supply pipe 145 (see FIG. 2 ). While flowing along the spiral space 171 in the evaporation unit 121, the water receives heat from the heating unit 120 and the combustion exhaust gas through the heating unit partition wall 131. As a result, the water becomes water vapor and is mixed with the reducing gas. As the reducing gas and water are supplied to the evaporation unit 121, a flow of reducing gas and water vapor is formed in the order of the evaporation unit 121, the reforming unit 122, and the CO reduction unit 123. The heat of the water vapor is transported to the CO reduction unit 123 together with the heated reducing gas. As a result, the amount of heat transferred from the reforming section 122 to the CO reducing section 123 increases, and the temperature of the CO reducing section 123, which is difficult to heat up, can be increased.

[0050] Furthermore, during the second period (step S3 in FIG. 3 ), the burner combustion is stopped and the amount of air supplied to the burner is increased. Specifically, the control unit 210 adjusts the aperture of the combustion air supply valve 183 so that the amount of air supplied to the burner in the heating unit 120 is increased compared to the amount of air supplied to the burner during the first period (see FIG. 1 ). The control unit 210 may also increase the air supply amount by increasing the rotation speed of the blower of the combustion air supply unit 181. When the burner combustion is stopped, combustion exhaust gas accumulates in the combustion liner 130 and becomes difficult to discharge. However, by increasing the amount of air supplied to the combustion liner 130, the combustion exhaust gas accumulated in the combustion liner 130 can be more easily discharged. The combustion exhaust gas discharged from the combustion liner 130 exchanges heat with the reforming unit 122 while flowing through the combustion exhaust gas path 140. As a result, heat exchange between the combustion exhaust gas from the burner and the reforming unit 122 in the heating unit 120 is smooth. This increases the amount of heat transferred from the reforming section 122 to the CO reducing section 123. This makes it possible to increase the temperature of the CO reducing section 123, which is difficult to heat up.

[0051] The heating unit 120 performs intermittent operation (steps S2 and S3 in FIG. 3 ) until the temperature T of the CO reduction catalyst rises to a threshold temperature T thSpecifically, the control unit 210 continues the process until the temperature T of the CO reduction catalyst detected by the second temperature sensor 206 rises to the threshold temperature T th The control unit 210 determines whether the temperature T of the CO reduction catalyst reaches the threshold temperature T th The intermittent operation is continued while the temperature is lower than the reference temperature (NO in step S4 in FIG. 3).

[0052] After that, the temperature T of the CO reduction catalyst rises to the threshold temperature T th When this occurs (YES in step S4 in FIG. 3 ), the heating unit 120 switches from intermittent operation to continuous operation so that the temperature of the reforming catalyst remains constant (step S5 in FIG. 3 ). Continuous operation is operation in which combustion by the heating unit 120 continues. Specifically, in intermittent operation, the control unit 210 alternately repeats a first period in which the fuel supply valve 182 and the combustion air supply valve 183 are opened to cause combustion in the burner of the heating unit 120, and a second period in which the combustion air supply valve 183 is opened and the fuel supply valve 182 is closed to stop combustion in the burner of the heating unit 120. The control unit 210 determines whether the temperature T of the CO reduction catalyst detected by the second temperature sensor 206 rises to a threshold temperature T th When the temperature reaches 122, continuous operation is performed by opening the fuel supply valve 182 and the combustion air supply valve 183 and continuing combustion in the burner of the heating unit 120. In continuous operation, the control unit 210 adjusts, for example, the opening degree of the combustion air supply valve 183 and / or the rotation speed of the blower of the combustion air supply unit 181 so that the temperature of the reforming catalyst remains constant. In continuous operation, the amount of heat given to the reforming unit 122 can be reduced while combustion by the heating unit 120 continues, thereby maintaining the temperature of the reforming catalyst. Note that in continuous operation, the control unit 210 closes the water supply valve 204 and does not supply water to the evaporation unit 121. Meanwhile, the control unit 210 keeps the reducing gas supply valve 203 open and continues to supply reducing gas.

[0053] The reduction reaction occurs when the catalyst is at a low temperature. When the temperature of the CO reduction catalyst is raised to the reduction temperature, the reduction reaction of the CO reduction catalyst is promoted by the reducing gas. this set to, for example, the reduction temperature of the CO reduction catalyst. Generally, the reduction temperature has a range (for example, from 100° C. to 300° C.). Therefore, the threshold temperature T th may be set to any predetermined value (e.g., 200°C) within the range of reduction temperatures. The CO reduction catalyst uses the reducing gas to carry out the following chemical reaction: CuO + H → Cu + H0. The reduction reaction converts the oxide into a zero-valent metal, thereby activating it.

[0054] When the temperature of the CO reduction catalyst rises to the reduction temperature, the reduction reaction of the catalyst is accelerated and heat is generated. Therefore, even if the heat from the heating unit 120 decreases, the reduction reaction of the CO reduction catalyst can continue with only the supply of reduction gas. On the other hand, the flow of reduction gas may dissipate heat, causing a temperature drop of the CO reduction catalyst. Therefore, in the first embodiment, when the temperature T of the CO reduction catalyst rises and the threshold temperature T th When this condition is met, the intermittent operation is switched to continuous operation. In continuous operation, the amount of heat given to the CO reduction unit 123 can be reduced while combustion by the heating unit 120 continues, so the temperature of the CO reduction catalyst can be maintained.

[0055] Thereafter, the supply of the reducing gas continues until the catalysts in the reforming unit 122 and the CO reduction unit 123 are reduced, and is stopped when the catalysts are activated (step S6 in the figure). This completes the catalyst reduction process in the hydrogen generator 100. Thereafter, the hydrogen generator 100 is shipped with the catalyst in an activated state.

[0056] From the viewpoint of reducing the catalyst precursor (oxide) using a reducing gas in the hydrogen generator 100 before shipping, the catalyst reduction method of the first embodiment is a method for manufacturing the hydrogen generator 100 that includes a catalyst generation step. In the catalyst generation step, a catalyst generation operation is performed to reduce the catalyst precursor.

[0057] (Explanation of Embodiment 1 Compared with Reference Embodiment) The catalyst reduction method in the hydrogen generator 100 of Embodiment 1 will be further explained below, in comparison with the catalyst reduction method in the hydrogen generator 100A of the reference embodiment. In the explanation of the hydrogen generator 100A of the reference embodiment, the same members as those in the hydrogen generator 100 (see FIG. 2) are assigned the same reference numerals, and explanations thereof will be omitted.

[0058] 4 is a vertical cross-sectional view showing the detailed configuration of a hydrogen generator 100A of the reference embodiment. The hydrogen generator 100A of the reference embodiment differs from the hydrogen generator 100 of the first embodiment in that it includes an external heating device 150. The boundary between the inside and outside of the hydrogen generator 100 is defined by the outer edge of the storage section 190 (see FIG. 1). In FIG. 2, the second partition wall 133 corresponds to the storage section 190.

[0059] In the hydrogen generation apparatus 100A, the external heating device 150 is provided on the outer wall surface of the second partition wall 133 (accommodation section 190) (see FIG. 4). The external heating device 150 is capable of heating the CO reduction section 123 through the second partition wall 133. The external heating device 150 is an electric heater. The electric heater is, for example, a resistance heating type sheathed heater.

[0060] In contrast, in the hydrogen generator 100, the heating unit 120 is housed in the second partition wall 133 (housing unit 190), and does not include an external heating device used in the catalytic reduction method (see FIG. 2).

[0061] In the catalyst reduction method in the hydrogen generator 100A of the reference embodiment, the normal operation heating unit 120 is used to heat and increase the temperature of the reforming catalyst built into the reforming unit 122 from the inside. On the other hand, the external heating device 150 is used to heat and increase the temperature of the CO reduction catalyst built into the CO reduction unit 123 from the outside. Then, reducing gas is supplied from upstream of the reforming unit 122 to reduce both the reforming catalyst and the CO reduction catalyst.

[0062] However, the external heating device 150 of the hydrogen generation device 100A of the reference embodiment can be a factor in increasing costs.

[0063] In contrast, the catalyst reduction method in the hydrogen generator 100 of the first embodiment uses only the heating unit 120 for normal operation, and heats and raises the temperature of the reforming catalyst built into the reforming unit 122 from the inside. Then, by supplying reducing gas from upstream of the reforming unit 122, a flow of heated reducing gas is formed in the order of the evaporator unit 121, the reforming unit 122, and the CO reduction unit 123. This reduces both the reforming catalyst and the CO reduction catalyst.

[0064] In the catalyst reduction method in the hydrogen generator 100 of the first embodiment, the temperature of the reforming section 122, which is located upstream of the CO reduction section 123, is increased first. In order to raise the temperatures of the reforming catalyst and the CO reduction catalyst to the reduction temperature, it is necessary to increase the heat generation amount of the heating section 120. As a result, before the temperature of the CO reduction catalyst reaches the reduction temperature, the temperature of the reforming catalyst may exceed the allowable temperature, which may cause deterioration of the reforming catalyst. Therefore, in the present embodiment, by performing intermittent operation (steps S2 and S3 in FIG. 3 ) in which combustion and stopping are alternately repeated in the heating section 120, such a situation can be avoided, and both the reforming catalyst and the CO reduction catalyst can be reduced.

[0065] Furthermore, in the catalytic reduction method in the hydrogen generator 100 of the first embodiment, both the reforming catalyst and the CO reduction catalyst can be reduced by using the internal heating unit 120. The hydrogen generator 100 does not have an external heating device used in the catalytic reduction method. This allows the cost of the hydrogen generator 100 to be reduced. Note that not using the external heating device 150 is not essential.

[0066] (Variation) In the catalytic reduction method of the first embodiment, the intermittent operation of the heating unit 120 (steps S2 and S3 in FIG. 3) is started after the supply of the reducing gas (step S1 in FIG. 3) is started, but the supply of the reducing gas may be started after the intermittent operation of the heating unit 120 is started.

[0067] In the catalyst reduction method of the first embodiment, the water supply step during the combustion duration period (step S2 in FIG. 3) may be omitted.

[0068] In the catalytic reduction method of the first embodiment, the step of increasing the air supply amount during the combustion stop period (step S3 in FIG. 3) may be omitted.

[0069] In the catalytic reduction method of the first embodiment, the temperature T of the CO reduction catalyst rises to the threshold temperature T th When the temperature of the reforming catalyst reaches or exceeds this value, the control unit 210 controls the operation so as to switch from intermittent operation to continuous operation so as to maintain a constant temperature of the reforming catalyst, but this is not limited to this. Control may be performed so as to maintain a constant temperature of the reforming catalyst during intermittent operation. During this intermittent operation, the control unit 210 adjusts, for example, the opening degree of the combustion air supply valve 183 and / or the rotation speed of the blower of the combustion air supply unit 181 so as to maintain a constant temperature of the reforming catalyst.

[0070] In the catalyst reduction method of the first embodiment, the duty ratio during intermittent operation is set to a fixed value. However, the duty ratio may be changed. This allows the temperature of the reforming catalyst to be controlled to be constant during intermittent operation. Specifically, when the temperature of the reforming catalyst detected by the first temperature sensor 205 rises to a threshold temperature, the control unit 210 may change the parameter value so that the ratio of the length of the combustion continuation period to the length of the combustion stop period decreases. This reduces heat from the heating unit 120, thereby suppressing the temperature rise of the reforming catalyst in the reforming unit 122. Note that when the temperature of the reforming catalyst rises to the reduction temperature, the catalyst reduction reaction is promoted and heat is generated. Therefore, even if the heat from the heating unit 120 is reduced by changing the duty ratio, the reduction reaction of the reforming catalyst can continue. Alternatively, when the temperature of the CO reduction catalyst detected by the second temperature sensor 206 rises to a threshold temperature, the control unit 210 may change the parameter value so that the ratio of the length of the combustion continuation period to the length of the combustion stop period decreases.

[0071] Although the CO reduction catalyst in the first embodiment uses a Cu-containing catalyst, it may be a metal catalyst containing, for example, Zn. Also, although the reforming catalyst in the first embodiment uses a Ni-containing catalyst, it may be a metal catalyst containing, for example, Pt (platinum).

[0072] The configuration of the hydrogen generator 100 is not limited to the configuration shown in Fig. 2. For example, the hydrogen generator 100 may include a CO remover having a catalyst for selectively oxidizing and removing carbon monoxide with oxygen, downstream of the CO reducer 123.

[0073] Although the catalyst reduction method of the first embodiment is performed before shipping of the hydrogen generator 100, it may also be performed after shipping. For example, it may be performed on a catalyst that has been oxidized due to aging deterioration of the hydrogen generator 100. From the perspective of regenerating an oxidized catalyst using a reducing gas in the hydrogen generator 100 after shipping, the catalyst reduction method of the first embodiment is a regeneration method for the hydrogen generator 100 that includes a catalyst reduction step. In the catalyst reduction step, a catalyst reduction operation is performed to reduce the oxidized catalyst.

[0074] The catalytic reduction method of the first embodiment is implemented by the operation of the catalytic reduction device 200 (controller 210), but is not limited to this. The method may also be implemented by the control unit 210 of the catalytic reduction device 200 and the control device of the hydrogen generator 100 being communicably connected and operating in cooperation with each other. The method may also be implemented by the control device of the hydrogen generator 100 executing a program for catalytic reduction processing.

[0075] (Other Embodiments) As described above, the first embodiment has been described as an example of the technology disclosed in the present application. However, the technology in the present disclosure is not limited to this, and can also be applied to embodiments in which modifications, substitutions, additions, omissions, etc. are made. Furthermore, it is also possible to combine the components described in the first embodiment above to create new embodiments.

[0076] The above description of the embodiments discloses the following techniques.

[0077] (Technology 1) A regeneration method for a hydrogen generation device, including a catalyst reduction step of regenerating an oxidized catalyst using a reducing gas, wherein the hydrogen generation device comprises: a heating unit; a reforming unit having a reforming catalyst and reacting steam and a raw material gas with heat from the heating unit to generate a reformed gas containing hydrogen; and a CO reduction unit having a CO reduction catalyst and reducing a concentration of carbon monoxide contained in the reformed gas with heat from the heating unit, wherein the catalyst reduction step includes: flowing the reducing gas through the reforming unit and the CO reduction unit; and alternately repeating a first period during which at least the reforming unit is heated with heat from the heating unit and a second period during which heating by the heating unit is stopped.

[0078] In this method, in the hydrogen generator, a period (first period) in which the reforming section is heated by the heating section and a period (second period) in which the heating section is stopped are alternately repeated, which makes it possible to reduce the reforming catalyst and the CO reduction catalyst while preventing the temperature of the reforming catalyst in the reforming section from rising excessively, compared to when the reforming section is continuously heated.

[0079] Note that there are no limitations on the timing of starting the supply of reducing gas and the timing of starting the repeated heating and stopping in the method of Technology 1. For example, the repeated heating and stopping may be started after the supply of reducing gas is started, or the supply of reducing gas may be started after the repeated heating and stopping has started.

[0080] (Technology 2) The regeneration method according to Technology 1, wherein the hydrogen generation device further includes a storage unit that stores the heating unit, the reforming unit, and the CO reduction unit, and no heating device used in the catalyst reduction step is provided outside the storage unit.

[0081] In this method, the catalyst can be reduced by using a heating unit contained in the container of the hydrogen generator, so no heating unit is provided outside the hydrogen generator (container), which allows for cost reduction of the hydrogen generator.

[0082] (Technology 3) The regeneration method according to Technology 1 or Technology 2, wherein the heating unit has a burner that burns a fuel gas in which combustion air and fuel are mixed and discharges a combustion exhaust gas, and includes: burning the fuel gas by the burner in the first period; and stopping the combustion of the fuel gas by the burner in the second period.

[0083] In this method, the heating section alternates between periods of burner combustion and periods of no combustion, thereby intermittently exchanging heat between the burner and the combustion exhaust gas with the reforming section, thereby preventing the temperature of the reforming catalyst in the reforming section from rising excessively.

[0084] (Technology 4) The regeneration method according to Technology 3, further comprising increasing the amount of air supplied to the burner in the second period compared to the amount of air supplied to the burner in the first period.

[0085] When the burner combustion stops, combustion exhaust gas accumulates in the heating section and becomes difficult to discharge. However, by increasing the amount of air supplied to the burner, the combustion exhaust gas accumulated in the heating section (e.g., combustion tube) can be more easily discharged. The discharged combustion exhaust gas exchanges heat with the reforming section while flowing through the combustion exhaust gas path. As a result, heat exchange between the burner combustion exhaust gas and the reforming section is smooth in the heating section. This increases the amount of heat transported from the reforming section to the CO reduction section. This accelerates the temperature rise of the CO reduction section, shortening the reduction time of the CO reduction catalyst.

[0086] (Technology 5) The regeneration method according to any one of Technology 1 to Technology 4, wherein the hydrogen generation device further includes an evaporation unit that heats water with heat from the heating unit to generate water vapor, and in the first period, the method includes supplying water to the evaporation unit to cause the water vapor to flow through the reforming unit and the CO reduction unit.

[0087] In this method, during the burner combustion period (first period) in the heating section, water is supplied to the evaporation section, forming a flow of water vapor in the order of the evaporation section, reforming section, and CO reduction section. As a result, the amount of heat transferred from the reforming section to the CO reduction section increases. This accelerates the temperature rise in the CO reduction section and shortens the reduction time of the CO reduction catalyst.

[0088] (Technology 6) The regeneration method according to any one of Technology 1 to Technology 5, further comprising: reducing a ratio of a length of the first period to a length of the second period when the temperature of the reforming catalyst in the reforming section rises to a threshold temperature.

[0089] In this method, the ratio of the length of the first period to the length of the second period is reduced, thereby further suppressing the temperature rise of the reforming catalyst. When the temperature of the reforming catalyst rises to a threshold temperature (e.g., reduction temperature), the reduction reaction of the catalyst is promoted and heat is generated, so the reduction reaction of the catalyst can continue even if the heat from the heating unit decreases.

[0090] (Technology 7) The hydrogen generation device further includes: a combustion liner surrounding the heating unit; a heating unit partition wall surrounding the combustion liner; a first partition wall surrounding the heating unit partition wall; and a second partition wall surrounding the first partition wall; the evaporator unit is provided upstream between the heating unit partition wall and the first partition wall; the reformer unit is provided downstream between the heating unit partition wall and the first partition wall; the CO reduction unit is provided between the first partition wall and the second partition wall, on the outer circumferential side of the evaporator unit and the reformer unit; and the evaporator unit and the reformer unit are heated by heat transferred from the heating unit via the heating unit partition wall.

[0091] (Technology 8) The regeneration method according to any one of the technologies 1 to 7, wherein the reducing gas is a hydrogen-containing gas.

[0092] In this method, hydrogen contained in the reducing gas removes oxygen from the oxidation catalyst through a reduction reaction, and the oxygen combines with the hydrogen to form water, thereby reducing the oxidized catalyst.

[0093] (Technology 9) A method for manufacturing a hydrogen generation device, including a catalyst generation step of reducing a catalyst precursor using a reducing gas, wherein the hydrogen generation device comprises: a heating unit; a reforming unit having a reforming catalyst and reacting steam and a raw material gas with heat from the heating unit to generate a reformed gas containing hydrogen; and a CO reduction unit having a CO reduction catalyst and reducing a concentration of carbon monoxide contained in the reformed gas with heat from the heating unit, wherein the catalyst generation step includes: flowing the reducing gas through the reforming unit and the CO reduction unit; and alternately repeating a first period during which at least the reforming unit is heated with heat from the heating unit and a second period during which heating by the heating unit is stopped.

[0094] In Techniques 1 to 8, the "catalyst reduction step" may be read as "catalyst reduction operation." In Technique 9, the "catalyst generation step" may be read as "catalyst generation operation."

[0095] The technology of the present disclosure is useful for a hydrogen generating device equipped with a catalyst.

Claims

1. A regeneration method for a hydrogen generation device, including a catalyst reduction step of regenerating an oxidized catalyst using a reducing gas, wherein the hydrogen generation device comprises: a heating unit; a reforming unit having a reforming catalyst and using heat from the heating unit to react steam and a raw material gas to produce a reformed gas containing hydrogen; and a CO reduction unit having a CO reduction catalyst and using heat from the heating unit to reduce the concentration of carbon monoxide contained in the reformed gas, wherein the catalyst reduction step includes: flowing the reducing gas through the reforming unit and the CO reduction unit; and alternately repeating a first period during which at least the reforming unit is heated by heat from the heating unit and a second period during which heating by the heating unit is stopped.

2. The regeneration method according to claim 1, wherein the hydrogen generation device further comprises a storage unit that houses the heating unit, the reforming unit, and the CO reduction unit, and no heating device used in the catalyst reduction step is provided outside the storage unit.

3. The regeneration method according to claim 1, wherein the heating unit has a burner that burns fuel gas, which is a mixture of combustion air and fuel, and discharges combustion exhaust gas, and the regeneration method includes: burning the fuel gas with the burner during the first period; and stopping the combustion of the fuel gas with the burner during the second period.

4. The regeneration method according to claim 3, further comprising increasing the amount of air supplied to the burner during the second period from the amount of air supplied to the burner during the first period.

5. The regeneration method according to claim 1, wherein the hydrogen generation device further comprises an evaporation section that heats water with heat from the heating section to generate water vapor, and during the first period, the method includes supplying water to the evaporation section, thereby causing the water vapor to flow through the reforming section and the CO reduction section.

6. The regeneration method according to claim 1, further comprising reducing the ratio of the length of the first period to the length of the second period when the temperature of the reforming catalyst in the reforming section rises to a threshold temperature.

7. The regeneration method according to claim 5, wherein the hydrogen generation device further comprises: a combustion liner surrounding the heating section; a heating section partition wall surrounding the combustion liner; a first partition wall surrounding the heating section partition wall; and a second partition wall surrounding the first partition wall; the evaporator section is provided upstream between the heating section partition wall and the first partition wall; the reformer section is provided downstream between the heating section partition wall and the first partition wall; the CO reduction section is provided between the first partition wall and the second partition wall, on the outer periphery of the evaporator section and the reformer section; and the evaporator section and the reformer section are heated by heat from the heating section being transferred via the heating section partition wall.

8. The regeneration method according to claim 1, wherein the reducing gas is a hydrogen-containing gas.

9. A method for producing a hydrogen generation apparatus, including a catalyst generation step of reducing a catalyst precursor using a reducing gas, wherein the hydrogen generation apparatus comprises: a heating unit; a reforming unit having a reforming catalyst and reacting steam and a raw material gas with heat from the heating unit to produce a reformed gas containing hydrogen; and a CO reduction unit having a CO reduction catalyst and reducing the concentration of carbon monoxide contained in the reformed gas with heat from the heating unit, wherein the catalyst generation step includes: flowing the reducing gas through the reforming unit and the CO reduction unit; and alternately repeating a first period during which at least the reforming unit is heated with heat from the heating unit and a second period during which heating by the heating unit is stopped.

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