Hydrogen production apparatus and control method for hydrogen production apparatus

Abstract

The present invention provides a hydrogen production apparatus capable of controlling the temperature of water vapor circulating within the system to a certain range during closed-circulation operation, and a method for operating the same. [Solution] A hydrogen production apparatus configured such that the operation control unit M calculates a first instruction value by performing PID control based on the difference between the current temperature of the reforming catalyst and the catalyst temperature setpoint, calculates a second instruction value by performing PID control based on the difference between the current temperature of the steam and the upper limit setpoint, obtains a low selector instruction value by selecting the lower of the first and second instruction values, calculates a third instruction value by performing PID control based on the difference between the current temperature of the steam and the lower limit setpoint, obtains a high selector instruction value by selecting the higher of the third instruction value and the low selector instruction value, calculates a final instruction value by performing PID control based on the difference between the high selector instruction value and the current fuel flow rate, and controls the opening degree of the flow control valve V20 based on the final instruction value.

Description

Technical Field

[0001] The present invention relates to a hydrogen production apparatus that performs a hydrogen purification operation by supplying a raw material gas to a gas flow passage, and a control method thereof. The hydrogen production apparatus is provided with: a desulfurizer that subjects the supplied raw material gas to desulfurization treatment; a reformer comprising a reforming reaction tube having a reforming treatment catalyst that subjects the raw material gas from the desulfurizer to steam reforming treatment to generate a reformed gas, and a reforming burner that heats the reforming reaction tube; a CO converter having a carbon monoxide shift catalyst that subjects carbon monoxide contained in the reformed gas from the reformer to shift treatment to generate a shifted gas; a hydrogen separation unit that separates impurities other than hydrogen from the shifted gas treated by the CO converter to purify hydrogen gas; and a heat exchanger for steam generation that heats water for steam generation with the combustion gas of the reforming burner to generate steam to be mixed with the raw material gas, wherein the gas flow passage for circulating gas is provided extending across the desulfurizer, the reformer, the CO converter, and the hydrogen separation unit.

Background Art

[0002] In recent years, development of on-site hydrogen production apparatuses that use natural gas, city gas or the like as a raw material gas to produce hydrogen on site has been carried out.

[0003] As an example of such a hydrogen production apparatus, there is known an apparatus including: a desulfurizer that desulfurizes a raw material gas pressure-fed by a pressure feeding device; a reformer that heats the desulfurized raw material gas in a state mixed with steam to obtain a reformed gas; a CO converter that causes carbon monoxide in the reformed gas from the reformer to react with steam to obtain a hydrogen-rich gas; and a hydrogen separation unit (for example, an apparatus using a PSA system) that separates impurities other than hydrogen from the hydrogen-rich gas to purify hydrogen (see, for example, Patent Documents 1 and 2).

[0004] The reforming process involves supplying a raw material gas, such as natural gas or naphtha, which is a hydrocarbon gas, to a desulfurizer for desulfurization. The desulfurized raw material gas is then supplied to a reforming reaction tube in a mixture with water vapor, where it is reformed into a reformed gas with a high hydrogen content. The carbon monoxide contained in the reformed gas is then converted into carbon dioxide in a CO converter, thereby producing a reformed gas with a high hydrogen content and a low carbon monoxide concentration.

[0005] In hydrogen production equipment, reducing the time loss during startup is widely recognized as one of the technical challenges.

[0006] In typical hydrogen production systems, during shutdowns, such as overnight, the desulfurizer, reformer, and CO transformer cool down to temperatures below their optimal operating temperature. Therefore, when restarting hydrogen production after a shutdown, a startup delay of approximately six hours occurs between the restart and the start of supplying product hydrogen with a sufficiently high hydrogen concentration.

[0007] Patent documents 1 and 2 describe that when hydrogen purification operations are temporarily stopped and hydrogen gas production is temporarily halted (for example, for several hours), a standby operation is performed. Specifically, while the reformer is continuously heated by the reforming burner, a standby operation (closed circulation operation) is performed (hot standby mode) in which the product gas (hydrogen gas) filled in the closed circulation circuit is circulated through the closed circulation circuit, passing through the compressor, desulfurizer, reformer, and CO transformer.

[0008] Standby operation (hot standby mode) is an operating state in which the hydrogen production system itself is running, but hydrogen production is not being performed while maintaining the temperature within the hydrogen production system. Putting the hydrogen production system into standby operation allows for a reduction in the response time when restarting hydrogen production, while also allowing for a safe shutdown of hydrogen production. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2016-675 [Patent Document 2] Japanese Patent Publication No. 2022-155214 [Overview of the project] [Problems that the invention aims to solve]

[0010] During the standby operation described above, the reformer (reforming reaction tube) is continuously heated by the reforming burner, and the only heat source for this standby operation is the combustion heat of the fuel gas supplied to the reformer.

[0011] The reforming reaction tube is filled with a reforming catalyst. The raw material gas after desulfurization is supplied to the reforming reaction tube in a mixture with water vapor. If the temperature of the water vapor drops, there is a risk that water may enter the reforming reaction tube. If the reforming catalyst packed inside the reforming reaction tube comes into contact with water, the reforming catalyst will be deactivated, and there is a risk that it will not be possible to produce reformed gas (containing hydrogen). In order to prevent the reforming catalyst from being deactivated in this way, conventionally, during standby operation, the fuel flow rate, which is the flow rate of fuel gas supplied to the reforming burner, was controlled solely by the temperature of the reforming catalyst.

[0012] In the hydrogen production apparatus described above, there is no means to control the fuel flow rate based on the temperature of the steam. Therefore, for example, during long-term standby operation, the temperature of the steam may decrease, and there was a risk that standby operation with steam introduced could not be sustained.

[0013] One factor that affects the temperature of water vapor is the combustion air supplied to the reforming burner. Increasing the flow rate of this combustion air increases the amount of combustion exhaust gas, while increasing the flow rate too much may cause the flame to be extinguished. Therefore, increasing the amount of combustion air is not practical because it may cause the hydrogen production equipment to shut down.

[0014] The steam mixed with the raw material gas is generated from water through heat exchange with the combustion heat in a steam generation heat exchanger. If, as described above, the amount of heat exchanged in the steam generation heat exchanger decreases during long-term standby operation, causing the steam temperature to drop, it will become impossible to mix steam with the raw material gas and supply it to the reforming reaction tube during hydrogen purification operation in order to protect the reforming catalyst. This would render the standby operation, which is intended to shorten the response time when restarting hydrogen production, unusable.

[0015] Therefore, the object of the present invention is to provide a hydrogen production apparatus and a method for operating the same that can control the temperature of the water vapor circulating in the system within a certain range during closed-circulation operation. [Means for solving the problem]

[0016] To achieve the above objective, the hydrogen production apparatus according to the present invention comprises: a desulfurizer for desulfurizing a supplied raw material gas; a reformer equipped with a reforming reaction tube having a reforming catalyst for steam reforming the raw material gas from the desulfurizer to generate a reformed gas, and a reforming burner for heating the reforming reaction tube; a CO transformer having a carbon monoxide transformation catalyst for transforming carbon monoxide contained in the reformed gas from the reformer to generate a transformed gas; a hydrogen separation unit for separating impurities other than hydrogen from the transformed gas after treatment in the CO transformer to purify hydrogen gas; and a steam generation heat exchanger for heating water for steam generation with the combustion gas of the reforming burner to generate steam to be mixed with the raw material gas. The hydrogen production apparatus is characterized by the provision of a gas flow passage through which gas flows between the desulfurizer, the reformer, the CO transformer, and the hydrogen separation unit, and by supplying raw material gas to the gas flow passage to perform hydrogen purification operation. The gas flow path is provided with a closed circulation circuit that circulates the gas in the order of the desulfurizer, the reformer, and the CO transformer, bypassing the hydrogen separation unit, and includes an operation control unit that switches between a state in which the hydrogen purification operation is performed and a state in which the closed circulation operation is performed in which the hydrogen separation unit is stopped while maintaining the heating of the reformer by the reforming burner, and the gas filled in the closed circulation circuit is circulated in the closed circulation circuit, and the operation control unit is configured to determine the fuel flow rate, which is the flow rate of fuel gas supplied to the reforming burner, based on the temperature of the reforming catalyst filled in the reforming reaction tube and the temperature of the steam generated in the steam generation heat exchanger, and further the operation control unit is configured to determine an upper limit setting value, which is the upper limit reference value of the steam temperature, a lower limit setting value, which is the lower limit reference value of the steam temperature, and a catalyst temperature setting value, which is the reference value of the temperature of the reforming catalyst, The system is configured to set a first instruction value, which is the fuel flow rate instruction value, by performing PID control based on the difference between the current temperature of the reforming catalyst and the catalyst temperature set value; to calculate a second instruction value, which is the fuel flow rate instruction value, by performing PID control based on the difference between the current temperature of the steam and the upper limit set value; to obtain a low selector instruction value by selecting the lower of the first and second instruction values; to calculate a third instruction value, which is the fuel flow rate instruction value, by performing PID control based on the difference between the current temperature of the steam and the lower limit set value; to obtain a high selector instruction value by selecting the higher of the third instruction value and the low selector instruction value; to calculate a final instruction value for adjusting the fuel flow rate by performing PID control based on the difference between the high selector instruction value and the current fuel flow rate; and to control the opening degree of the flow control valve that adjusts the fuel flow rate based on the final instruction value.

[0017] In this configuration, the calculation of the first, second, and third indicated values, and the control of the opening degree of the flow control valve are performed by PID control (Proportional-Integral-Derivative Controller).

[0018] The first instruction value is a provisional fuel flow rate calculated by performing PID control based on the difference between the current temperature of the reforming catalyst and the catalyst temperature setpoint, in order to minimize the deviation (degree of discrepancy) between the current temperature of the reforming catalyst and the catalyst temperature setpoint.

[0019] The second instruction value is a provisional fuel flow rate calculated by performing PID control based on the difference between the current water vapor temperature and the upper limit setting value, in order to minimize the deviation (degree of discrepancy) between the current water vapor temperature and the upper limit setting value.

[0020] In this configuration, a low selector instruction value is obtained by selecting the lower of the first instruction value and the second instruction value. In this way, by obtaining a low selector instruction value based on the first instruction value, which takes into account the current temperature of the reforming catalyst and the catalyst temperature setpoint, and the second instruction value, which takes into account the current water vapor temperature and the upper limit setpoint, it is possible to obtain a provisional fuel flow rate instruction value that prevents the reforming catalyst from rising while controlling the water vapor temperature to be lower than the upper limit setpoint.

[0021] The third instruction value is a provisional fuel flow rate calculated by performing PID control based on the difference between the current water vapor temperature and the lower limit setting value, in order to minimize the deviation (degree of discrepancy) between the current water vapor temperature and the lower limit setting value.

[0022] In this configuration, the higher of the third instruction value and the low selector instruction value is selected to obtain the high selector instruction value. In this way, by obtaining the high selector instruction value based on the third instruction value, which takes into account the current water vapor temperature and the lower limit setting value, and the low selector instruction value, it is possible to obtain a provisional instruction value for the fuel flow rate that allows control to raise the water vapor temperature above the lower limit setting value.

[0023] The final indicated value is calculated by performing PID control based on the difference between the high selector indicated value and the current fuel flow rate, and minimizing the deviation (degree of discrepancy) between the high selector indicated value and the current fuel flow rate. In this configuration, the opening degree of the flow control valve that adjusts the fuel flow rate is controlled based on this final indicated value.

[0024] Accordingly, in this configuration, by controlling the opening degree of the flow control valve based on the final instruction value, during closed circulation operation, the current temperature of water vapor can be kept within an appropriate range (between the upper limit set value and the lower limit set value) while preventing the temperature of the reforming catalyst from rising.

[0025] Therefore, in this configuration, compared with the conventional case where the fuel flow rate, which is the flow rate of fuel gas supplied to the reforming burner during closed circulation operation (standby operation), is controlled only by the temperature of the reforming catalyst, it becomes easier to control the temperature of the water vapor circulating in the system during closed circulation operation within a fixed range (between the upper limit set value and the lower limit set value).

[0026] The gas circulating in the system during closed circulation operation is supplied to the reforming reaction tube in a mixed state with water vapor. Since the temperature of the water vapor is controlled within a fixed range to make it difficult for the water vapor temperature to decrease, water hardly enters the inside of the reforming reaction tube, and it is possible to prevent the reforming catalyst filled in the reforming reaction tube from being deactivated due to contact with water. Accordingly, in the hydrogen production apparatus of this configuration, the closed circulation operation, which is an operation for shortening the response time when resuming hydrogen production, can be reliably established.

[0027] A further characteristic configuration of the hydrogen production apparatus according to the present invention is that the closed circulation operation is defined as a standby operation.

[0028] According to this configuration, the standby operation, which is an operation for shortening the response time when resuming hydrogen production, can be reliably established.

[0029] The characteristic configuration of the control method for a hydrogen production apparatus according to the present invention is a control method for the hydrogen production apparatus described above, comprising: a steam temperature reference value setting step of setting an upper limit reference value which is an upper limit reference value for the steam temperature and a lower limit reference value which is a lower limit reference value for the steam temperature; a catalyst temperature reference value setting step of setting a catalyst temperature reference value which is a reference value for the temperature of the reforming catalyst; a first instruction value calculation step of calculating a first instruction value which is an instruction value for the fuel flow rate by performing PID control based on the difference between the current temperature of the reforming catalyst and the catalyst temperature setting value; a second instruction value calculation step of calculating a second instruction value which is an instruction value for the fuel flow rate by performing PID control based on the difference between the current temperature of the steam temperature and the upper limit reference value; and the first The system includes: a low selector instruction value acquisition step, which acquires a low selector instruction value by selecting the lower of the instruction value and the second instruction value; a third instruction value calculation step, which calculates a third instruction value, which is the instruction value of the fuel flow rate, by performing PID control based on the difference between the current water vapor temperature and the lower limit setting value; a high selector instruction value acquisition step, which acquires a high selector instruction value by selecting the higher of the third instruction value and the low selector instruction value; and a fuel flow rate control step, which calculates a final instruction value for adjusting the fuel flow rate by performing PID control based on the difference between the high selector instruction value and the current fuel flow rate, and controls the opening degree of the flow control valve that adjusts the fuel flow rate based on the final instruction value.

[0030] In the first instruction value calculation step, PID control is performed based on the difference between the current temperature of the reforming catalyst and the catalyst temperature setpoint, and a provisional instruction value for the fuel flow rate can be calculated to reduce the deviation (degree of discrepancy) between the current temperature of the reforming catalyst and the catalyst temperature setpoint.

[0031] In the second instruction value calculation step, PID control is performed based on the difference between the current water vapor temperature and the upper limit setting value, and a provisional instruction value for the fuel flow rate can be calculated to reduce the deviation (degree of discrepancy) between the current water vapor temperature and the upper limit setting value.

[0032] In the low selector instruction value acquisition step, the low selector instruction value is obtained by selecting the lower of the first instruction value and the second instruction value. In this way, by obtaining the low selector instruction value based on the first instruction value, which takes into account the current temperature of the reforming catalyst and the catalyst temperature setpoint, and the second instruction value, which takes into account the current water vapor temperature and the upper limit setpoint, it is possible to obtain a provisional fuel flow rate instruction value that prevents the reforming catalyst from rising while controlling the water vapor temperature to be lower than the upper limit setpoint.

[0033] In the third instruction value calculation step, PID control is performed based on the difference between the current water vapor temperature and the lower limit setting value, and a provisional instruction value for the fuel flow rate can be calculated to reduce the deviation (degree of discrepancy) between the current water vapor temperature and the lower limit setting value.

[0034] In the high selector instruction value acquisition step, the higher of the third instruction value and the low selector instruction value is selected to acquire the high selector instruction value. In this way, by acquiring the high selector instruction value based on the third instruction value, which takes into account the current water vapor temperature and the lower limit setting value, and the low selector instruction value, it is possible to obtain a provisional instruction value for the fuel flow rate that allows control to raise the water vapor temperature above the lower limit setting value.

[0035] In the fuel flow control step, PID control is performed based on the difference between the high selector instruction value and the current fuel flow rate to calculate a final instruction value for adjusting the fuel flow rate, and the opening degree of the flow control valve that adjusts the fuel flow rate can be controlled based on this final instruction value.

[0036] Therefore, in the control method for the hydrogen production apparatus of the present invention, by controlling the opening degree of the flow control valve based on the final instruction value, it is possible to keep the current water vapor temperature within an appropriate range (between the upper and lower set limits) while preventing the rise of the reforming catalyst during closed circulation operation (standby operation).

[0037] Therefore, with this control method, compared to the conventional method where the fuel flow rate, which is the flow rate of fuel gas supplied to the reforming burner during closed-circulation operation (standby operation), was controlled solely by the temperature of the reforming catalyst, it becomes easier to control the temperature of the water vapor circulating within the system during closed-circulation operation (standby operation) to a certain range (between the upper and lower limit settings).

[0038] During closed-circulation operation, the circulating gas within the system is supplied to the reforming reaction tube in a mixture with water vapor. However, by controlling the temperature of the water vapor within a certain range, the temperature of the water vapor is less likely to drop, making it difficult for water to enter the reforming reaction tube. This prevents the reforming catalyst packed inside the reforming reaction tube from coming into contact with water and becoming inactive. Therefore, this control method ensures that closed-circulation operation (standby operation), which is an operation designed to shorten the response time when restarting hydrogen production, can be reliably achieved. [Brief explanation of the drawing]

[0039] [Figure 1] This is a schematic diagram of the hydrogen production system. [Figure 2] This diagram shows the gas flow status during the startup operation of a hydrogen production plant. [Figure 3] This diagram shows the flow state of pure water in startup mode. [Figure 4] This figure shows the flow state of pure water in steady-state operation mode. [Figure 5] This is a longitudinal cross-sectional front view showing a CO transformer. [Figure 6] This is a longitudinal cross-sectional front view of the reforming reactor. [Figure 7] This is a plan view showing the arrangement of reaction tubes in a reforming reactor. [Figure 8] This is a partially abbreviated longitudinal cross-sectional front view showing the reaction tube. [Figure 9] This is a schematic diagram illustrating how the fuel flow rate, which is the flow rate of fuel gas supplied to the reforming burner during standby operation, is controlled by the operation control unit. [Figure 10]This is a block diagram showing how the fuel flow rate, which is the flow rate of fuel gas supplied to the reforming burner during standby operation, is controlled by the operation control unit. [Figure 11] This is a block diagram (Reference Example 1) showing how the fuel flow rate, which is the flow rate of fuel gas supplied to the reforming burner during conventional standby operation, is controlled by the operation control unit. [Figure 12] This is a block diagram (Reference Example 2) showing how the fuel flow rate, which is the flow rate of fuel gas supplied to the reforming burner during standby operation, is controlled by the operation control unit. [Modes for carrying out the invention]

[0040] Embodiments of the present invention will be described below with reference to the drawings. As shown in Figures 1 to 10, the hydrogen production apparatus 100 of the present invention includes a desulfurizer P for desulfurizing the supplied raw material gas G, a reformer H equipped with a reforming reaction tube A having a reforming catalyst S for steam reforming the raw material gas G from the desulfurizer P to produce reformed gas K, and a reforming burner B for heating the reforming reaction tube A, a CO transformer Q having a carbon monoxide transformation catalyst Z for transforming carbon monoxide contained in the reformed gas K from the reformer H to produce transformed gas, a hydrogen separation unit 20 for separating impurities other than hydrogen from the transformed gas after treatment in the CO transformer Q to purify hydrogen gas, and a steam generation heat exchanger J for heating water for steam generation with the combustion gas E of the reforming burner B to generate steam to be mixed with the raw material gas G. A gas flow passage is provided through which gas flows between the desulfurizer P, the reformer H, the CO transformer Q, and the hydrogen separation unit 20, and the raw material gas G is supplied to the gas flow passage to perform hydrogen purification operation. The hydrogen production apparatus 100 is equipped with a closed circulation circuit C in the gas flow path that bypasses the hydrogen separation unit 20 and circulates the gas in the order of desulfurizer P, reformer H, and CO transformer Q, and includes an operation control unit M that switches between a state in which hydrogen purification operation is performed and a state in which closed circulation operation is performed in which the heating of the reformer H by the reforming burner B is maintained, the hydrogen separation unit 20 is stopped, and the gas filled in the closed circulation circuit C is circulated through the closed circulation circuit C.

[0041] In this embodiment, the case where closed-circulation operation is set to standby operation will be described.

[0042] (Overall configuration of the hydrogen production system) The hydrogen production apparatus 100 will be described based on Figure 1. Figure 1 illustrates the state when hydrogen purification operation is being performed. In the figure, flow paths through which various gases such as raw material gas G are flowing are shown with thick lines, and flow paths through which no gases are flowing are shown with thin lines. Valves that open and close the flow paths are shown in white when open, and in black when closed. The same applies to Figure 2, which shows the state when startup operation is being performed, Figure 3, which shows the startup operation mode, and Figure 4, which shows the steady-state operation mode.

[0043] The hydrogen production apparatus 100 is equipped with a reforming section R and a pressure fluctuation adsorption type hydrogen separation section 20 that adsorbs and removes impurities contained in the modified gas supplied from the reforming section R to purify a product gas with a high hydrogen concentration. The operation control unit M is configured to control the operation of the reforming unit R and the hydrogen separation unit 20.

[0044] (Details of the modified section) The reforming unit R comprises a desulfurizer P that desulfurizes the raw material gas G, which is a hydrocarbon gas supplied under pressure by a compressor D; a reformer H to which the desulfurized raw material gas G is supplied in a mixture with water vapor; and a CO converter Q that converts the carbon monoxide contained in the reformed gas K produced in the reformer H into carbon dioxide. Furthermore, a raw material gas valve V1, which intermittently supplies raw material gas G and adjusts the amount of raw material gas G supplied, is installed on the upstream side of the compressor D.

[0045] The raw material gas G, pumped by the compressor D, is supplied to the desulfurizer P through the first flow path L1 (gas passage). The desulfurizer P is filled with desulfurization catalysts such as Ni-Mo-based or ZnO-based catalysts, and is configured to remove sulfur components such as odorants from the raw material gas G using these catalysts. The desulfurized raw material gas G is supplied to the reformer H through the second flow path L2 (gas flow passage). Steam generated in the steam generation heat exchanger J is supplied to the second flow path L2, and the steam is mixed with the raw material gas G flowing through the second flow path L2.

[0046] In the reformer H, the reforming burner B burns the reforming reaction tube A (see Figure 6), and the raw material gas G, which is mixed with steam, is subjected to steam reforming treatment to produce reformed gas K. Figure 1 shows a schematic representation of the reformer H, and omits the description of the configuration for supplying combustion air AR to the reforming burner B.

[0047] The reformed gas K obtained in reformer H is supplied through the third flow path L3 (gas flow path) to the CO transformer Q, which reacts the carbon monoxide in the reformed gas with water vapor. The CO transformer Q is filled with a carbon monoxide transformation catalyst Z (see Figure 5), and the carbon monoxide in the reformed gas is transformed into hydrogen and carbon dioxide by reacting with water vapor. The reaction in the CO transformer Q results in reformed gas K becoming a transformed gas containing hydrogen, carbon monoxide, carbon dioxide, and methane (hydrogen concentration of 64-96% by volume). Furthermore, since the desulfurization reaction in desulfurizer P is an endothermic reaction and the CO conversion reaction in CO converter Q is an exothermic reaction, these are configured to exchange heat with each other, for example, by housing them in a single reaction vessel.

[0048] (Regarding the flow of modified gases) The transformed gas discharged from the CO transformer Q flows through the fourth flow path L4 (gas flow passage), where it exchanges heat with the cooling water in the cooling water heat exchanger 18, causing it to cool down and liquefy the water vapor. The water is then removed by the gas-liquid separation unit 19, and subsequently guided to the hydrogen separation unit 20 through the fifth flow path L5 (gas flow passage). The fifth flow path L5 is equipped with a transformed gas valve V5 that opens and closes the fifth flow path L5.

[0049] A return path L10 branches off from the fifth flow path L5, which returns the modified gas from which moisture has been removed in the gas-liquid separation unit 19 to the upstream side of the compressor D, bypassing the PSA device 22. The return path L10 is provided with a return valve V10 that opens and closes the return path L10.

[0050] Although not shown in the diagram, a desulfurization return line is provided to return the modified gas from which moisture has been removed in the gas-liquid separation section 19 to the upstream side of the compressor D for desulfurization treatment in the desulfurizer P, and a desulfurization valve is provided to open and close this desulfurization return line. The desulfurization valve will be opened during the hydrogen purification operation (steady-state operation) described later, and closed at other times.

[0051] Furthermore, upstream of the cooling water heat exchanger 18 in the fourth flow path L4, a pure water heat exchanger 26 is provided to exchange heat between the pure water W supplied by a pure water supply pump 25 from a pure water tank 24 that stores pure water W and the modified gas. Furthermore, an exhaust passage L12 is branched from the fifth flow path L5 to discharge the gas flowing through the fifth flow path L5 to the outside. The exhaust passage L12 is equipped with an exhaust valve V12 that opens and closes the exhaust passage L12.

[0052] Incidentally, in addition to the first channel L1, second channel L2, third channel L3, fourth channel L4, and fifth channel L5, a closed-circuit circuit C can be formed in which the gas that has passed through the CO transformer Q is circulated via the desulfurizer P, reformer H, and CO transformer Q using a return path L10 that bypasses the hydrogen separation unit (PSA device) 22 from the fifth channel L5 (see Figure 2).

[0053] (Details of the hydrogen separation section) The hydrogen separation unit 20 includes a pressure-oscillating adsorption type PSA device 22 that separates impurities other than hydrogen (miscellaneous gases) contained in the modified gas processed by the CO transformer Q to purify a product gas with a high concentration of hydrogen gas, a product tank 23 for storing the purified product gas, and an off-gas tank 21 for storing off-gas discharged from the PSA device 22.

[0054] The PSA device 22 is equipped with multiple (three in this embodiment) adsorption towers 20a, 20b, and 20c. Each adsorption tower 20a, 20b, and 20c is filled with a combination of adsorbent materials such as zeolite-based adsorbent, activated carbon, and silica gel. Each of the adsorption towers 20a, 20b, and 20c is configured to purify a product gas with a high hydrogen gas concentration by executing the adsorption process, depressurization process, purging process, and pressurization process (PSA process) in different phases across the multiple adsorption towers 20a, 20b, and 20c.

[0055] Although a detailed explanation is omitted, the above process (PSA process) is executed sequentially by the operation control unit M opening and closing multiple valves (not shown) provided in each flow passage connected to the multiple adsorption towers 20a, 20b, and 20c. Figure 1 shows the state in which the adsorption tower 20a is performing an adsorption process to obtain the product gas by passing the modified gas through it.

[0056] The product gas purified in the PSA device 22 is supplied to the product tank 23 through the sixth channel L6, and the product gas stored in the product tank 23 is stably supplied to the hydrogen usage locations. The sixth flow path L6 is provided with a product gas valve V6 that opens and closes the sixth flow path L6. After hydrogen is separated in the PSA device 22, the off-gas (miscellaneous gas) is supplied to the off-gas tank 21 through the seventh channel L7. The seventh passage L7 is equipped with an off-gas valve V7 that opens and closes the seventh passage L7.

[0057] The off-gas stored in the off-gas tank 21 contains flammable gases such as methane and hydrogen, and is therefore guided to the fuel gas supply unit 10 via the off-gas flow passage L8. From the fuel gas supply unit 10, it is supplied as fuel gas to the reforming burner B. The off-gas flow passage L8 is equipped with an off-gas return valve V8 that opens and closes the off-gas flow passage L8. Although Figure 1 only shows the flow of the product gas, there are timings in which the delivery of the product gas and the delivery of the off-gas occur simultaneously for different adsorption towers 20a, 20b, and 20c.

[0058] Incidentally, a hydrogen supply channel L11 is provided to supply hydrogen gas from the product tank 23 to the return channel L10 in order to perform the hydrogen purging process described later. The hydrogen supply channel L11 is equipped with a hydrogen gas valve V11 that opens and closes the hydrogen supply channel L11.

[0059] (Details of the hydrogen purification process) As shown in Figure 1, in the hydrogen purification operation state (steady-state operation), the raw material gas G passes through the raw material gas valve V1, is pumped by the compressor D, flows through the first channel L1, and is led to the desulfurizer P where it is desulfurized. After that, the raw material gas G mixed with steam is led to the reformer H where it undergoes steam reforming to produce reformed gas K. The reformed gas K is reformed in the CO transformer Q, the reformed gas is cooled in the cooling water heat exchanger 18, and after water is removed in the gas-liquid separation unit 19, it is introduced to the hydrogen separation unit 20 through the fifth channel L5, where the product gas (hydrogen gas) is purified.

[0060] (Overall configuration of the reformer) As shown in Figure 6, the reformer H is used to reform hydrocarbon feedstock gases G, such as natural gas and naphtha, into reformed gas K with a high hydrogen content by steam reforming treatment, and comprises a reforming furnace 2 equipped with a reforming reaction tube A and a reforming burner B for heating the reforming reaction tube A.

[0061] The reforming furnace 2 is configured to include a ceiling wall 2U, a bottom wall 2D, and a cylindrical side wall 2S positioned between the ceiling wall 2U and the bottom wall 2D. Furthermore, a reforming burner B is installed in the center of the ceiling wall 2U of the reformer H in a configuration that burns downwards, and an outlet 2E for discharging the combustion gas E from the reforming burner B is opened in the upper part of the side wall 2S.

[0062] As shown in Figures 6 and 7, multiple reforming reaction tubes A are installed in a manner that they hang down from the ceiling wall 2U of the reformer H and are spaced apart and arranged side by side around the reforming burner B. In this embodiment, we illustrate the case where four reforming reaction tubes A are provided as the multiple reforming reaction tubes A, but it may also be implemented with three or five or more reforming reaction tubes A.

[0063] Furthermore, as shown in Figure 6, a cylindrical outer wall 2G is provided on the outer side of the side wall 2S of the reformer H, positioned between the ceiling wall 2U and the bottom wall 2D. Furthermore, a steam generating heat exchanger J is positioned in the external space F between the side wall 2S and the outer wall 2G to generate steam to be mixed with the raw material gas G supplied to the upper part of the reforming reaction tube A. Additionally, an external outlet 2Z is ​​provided below the outer wall 2G to discharge the combustion gas E flowing through the external space F from the discharge section 2E.

[0064] Furthermore, as shown in Figure 6, an air preheating heat exchanger N is provided between the steam generation heat exchanger J and the outer wall 2G in the external space F to preheat the air supplied to the reforming burner B.

[0065] (Details of the reaction tube section) As shown in Figure 8, the reforming reaction tube A comprises an outer tube 3 with a closed bottom and an inner tube 4 positioned inside the outer tube 3. The inner tube 4 is formed with an open bottom, and a packed section filled with granular reforming catalyst S is formed between the outer tube 3 and the inner tube 4, oriented in an up-and-down direction. The reforming reaction tube A is equipped with a catalyst temperature sensor (not shown) for measuring the temperature of the layered reforming catalyst S (temperature of the catalyst layer). The upper end portion of the outer pipe 3 is supported by the ceiling wall 2U of the reformer H, with the inner pipe 4 being supported by the upper wall 3u of the outer pipe 3, with the inner pipe being supported by the upper wall 3u of the outer pipe 3, with the inner pipe being supported by the upper wall 3u of the outer pipe 3, with the inner pipe being supported by the upper wall 3u of the outer pipe 3, with the inner pipe being supported by the upper wall 3u of the outer pipe 3, with the inner pipe being supported by the upper wall 3u of the outer pipe 3, with the upper end portion of the outer pipe 3

[0066] A porous catalyst support section T is provided between the outer tube 3 and the inner tube 4 to receive and support the catalyst S for the reforming treatment. The catalyst support section T is formed to have a passage hole that allows reformed gas K (an example of a processed gas) flowing between the outer tube 3 and the inner tube 4 toward the bottom side of the outer tube 3, and is supported at the lower end of the inner tube 4. Incidentally, in Figure 8, the catalyst support T is shown as an example of a porous plate-like form with through-holes formed throughout the entire surface. However, the catalyst support T can be configured in various forms, such as a plate-like form in which the through-holes are arranged in a single row along the circumferential direction, as long as it has through-holes that receive the reforming catalyst S and allow the reformed gas K to pass through.

[0067] As shown in Figures 6 and 8, a raw material gas introduction pipe 5a is connected to the portion of the outer pipe 3 that protrudes from the ceiling wall 2U of the reformer H, for introducing raw material gas G mixed with water vapor. As shown in Figure 6, this raw material gas introduction pipe 5a is connected to an annular raw material gas distribution pipe 5b, and a raw material gas pipe 5 that supplies raw material gas G mixed with water vapor is connected to this raw material gas distribution pipe 5b. In other words, the raw material gas G mixed with water vapor is supplied from the raw material gas pipe 5 to the annular raw material gas distribution pipe 5b, and the raw material gas G mixed with water vapor is supplied from the annular raw material gas distribution pipe 5b to multiple reforming reaction tubes A.

[0068] Incidentally, as shown in Figure 6, the raw material gas pipe 5 is supplied with steam generated in the steam generation heat exchanger J, as described later, and the raw material gas G and steam are supplied to the outer pipe 3 in a mixed state through the raw material gas pipe 5.

[0069] As shown in Figures 6 and 8, a discharge pipe 6a for discharging the reformed gas K is connected to the portion of the inner pipe 4 that protrudes from the outer pipe 3. As shown in Figure 6, this discharge pipe 6a is connected to an annular confluence pipe 6b, and a guide pipe 6 for guiding the reformed gas K is connected to this confluence pipe 6b. In other words, the reformed gas K is discharged from the reforming reaction tube A through the discharge tube 6a, and this reformed gas K flows through the annular confluence tube 6b and then through the guide tube 6 towards the CO transformer Q.

[0070] (Details of the heat exchanger for steam generation) As shown in Figure 6, the heat exchanger J for steam generation is configured such that the heat transfer tubes 7 are arranged spirally along the outer circumference of the side wall 2S of the reformer H. In other words, a pure water inlet pipe section 7a is formed at the lower end of the heat transfer pipe 7, through which pure water W is supplied, and a steam outlet pipe section 7b is formed at the upper end of the heat transfer pipe 7, through which steam is supplied to the raw material gas pipe 5.

[0071] Therefore, the steam generation heat exchanger J is configured to generate steam by flowing pure water W supplied to the pure water inlet pipe section 7a through the inside of a heat transfer pipe 7 which is heated by combustion gas E flowing in the external space F, and to supply the generated steam to the raw material gas pipe 5 from the steam discharge pipe section 7b. The steam generation heat exchanger J is provided with a steam temperature sensor (not shown) for measuring the temperature of the generated steam. This steam temperature sensor may be installed, for example, in the raw material gas pipe 5 or the raw material gas inlet pipe 5a, just before the generated steam flows into the reforming reaction pipe A. In addition, a branch pipe 7c is connected to the steam discharge pipe section 7b, which supplies the generated steam U as heating steam to the CO transformer Q during the startup operation described later.

[0072] (Details of the air preheating heat exchanger) As shown in Figures 6 and 7, the air preheating heat exchanger N is configured in a cylindrical shape that allows air to flow between a cylindrical inner wall 8n and a cylindrical outer wall 8g. Furthermore, an air inlet 8d is provided below the air preheating heat exchanger N to introduce combustion air AR supplied from a blower (not shown). Multiple air supply pipes 9 connecting the upper part of the air preheating heat exchanger N to the reforming burner B are installed inside the ceiling wall 2U of the reformer H, arranged radially around the reforming burner B.

[0073] Therefore, the air preheating heat exchanger N is configured to heat the combustion air AR supplied to the air inlet 8d to a high temperature by flowing it between the inner wall 8n and the outer wall 8g, which are heated by the combustion gas E flowing in the external space F, and to supply the high-temperature heated combustion air AR to the reforming burner B through the air supply pipe 9.

[0074] Incidentally, although the detailed configuration of the reforming burner B is omitted, in addition to being connected to the air supply pipe 9, the reforming burner B is also connected to the fuel supply pipe 10a (see Figure 1), which is connected to the fuel gas supply unit 10, and is configured to burn the fuel gas supplied from the fuel gas supply unit 10 with the combustion air AR supplied through the air supply pipe 9. A flow meter 40 for measuring the flow rate of the fuel gas is installed upstream of the flow control valve V20 (described later) in the fuel supply pipe 10a.

[0075] The fuel gas supply unit 10 supplies off-gas from the off-gas tank 21 (see Figure 1) as fuel gas, and when the off-gas is insufficient, it supplies raw material gas G as fuel gas. Therefore, although a detailed explanation will be omitted, the fuel gas supply unit 10 is configured to include supply adjustment valves (for example, an off-gas return valve V8 and a flow control valve V20) for adjusting the supply amount of off-gas and raw material gas G. Furthermore, the blower (not shown) that supplies combustion air AR to the air inlet 8d is configured so that the amount of air supplied can be adjusted by adjusting the output.

[0076] (Details of the CO transformer) As shown in Figure 5, the CO converter Q has a carbon monoxide conversion catalyst Z that converts carbon monoxide contained in the reformed gas K into carbon dioxide, and is equipped with a cooling pipe 11 through which cooling water flows to cool the carbon monoxide conversion catalyst Z. In other words, the CO transformer Q is configured to include a cylindrical transformer body 12 that has a reformed gas inlet 12a at one end and a transformed gas outlet 12b at the other end. A columnar packing body 13 is positioned radially in the center of the interior of the reactor body 12, extending from one end to the other. Cooling pipes 11 are arranged spirally in the space outside the packing body 13 inside the reactor body 12, extending from one end to the other, and are filled with a carbon monoxide conversion catalyst Z. The filling body 13 is, for example, made of a cylindrical iron pipe.

[0077] To further explain, the reforming furnace body 12 comprises a bottomed cylindrical body portion 12A and a reformed gas receiving portion 12B that is flange-connected to the upper part of the body portion 12A. The reformed gas receiving section 12B is configured as a cylindrical section through which reformed gas K is introduced via the third flow path L3 and which is discharged toward the main body section 12A.

[0078] In the upper part of the interior of the main body portion 12A, for example, a porous frame 14, which is formed in a porous manner and has air permeability, is positioned to close the upper end of the packing body 13. In addition, a cylindrical gas receiving body 15, which forms multiple reformed gas inlets 12a in the circumferential direction, is provided in a position corresponding to the upper part of the packing body 13, communicating with the reformed gas receiving section 12B and with its lower end portion inserted into the porous frame 14. Therefore, the reformed gas K that flows from the reformed gas receiving section 12B to the gas receiving body 15 is discharged from the reformed gas inlet 12a, and the reformed gas K is configured to flow through the porous frame 14 into the outer space of the packing body 13.

[0079] A receiving plate 16 for receiving the carbon monoxide-modified catalyst Z is provided at the lower part of the main body portion 12A, with the portion facing the packing body 13 being non-porous and the portion located outside the packing body 13 being porous, and is provided at a location corresponding to the lower end of the packing body 13. Furthermore, the space below the receiving plate 16 is filled with a spherical metal body 16a.

[0080] (Regarding the mode switching section) As shown in Figure 4, the system is configured to allow switching between a steady-state operation mode in which water (pure water W) from a pure water tank 24 (an example of a water supply source) is supplied to the cooling pipe 11 as cooling water, and the water (pure water W) that has flowed through the cooling pipe 11 is supplied to the steam generation heat exchanger J as water for steam generation, and a startup operation mode in which, as shown in Figure 3, water (pure water W) from a pure water tank 24 (an example of a water supply source) is supplied to the steam generation heat exchanger J to generate steam U for heating, and the steam U for heating is supplied to the cooling pipe 11.

[0081] To elaborate, as shown in Figure 4, in steady-state operation mode, a first pure water supply passage L13 is provided that flows pure water W supplied by the pure water supply pump 25 to the inlet of the cooling pipe 11, and a second pure water supply passage L14 is provided that flows pure water W discharged from the outlet of the cooling pipe 11 to the pure water introduction pipe section 7a of the heat transfer pipe 7.

[0082] Furthermore, as shown in Figure 3, in the startup operation mode, a third pure water supply channel L15 is provided which branches off from the first pure water supply channel L13 and merges with the second pure water supply channel L14. This third pure water supply channel L15 bypasses the cooling pipe 11 and directs the pure water W flowing through the first pure water supply channel L13 to the pure water introduction pipe section 7a of the heat transfer pipe 7. Furthermore, in the startup operation mode, a steam flow path L16 is provided that flows the steam discharged from the steam discharge pipe section 7b of the heat transfer pipe 7 as heating steam U to the inlet of the cooling pipe 11, and this steam flow path merges with the first pure water supply path L13.

[0083] Furthermore, a steam discharge passage L17 is provided, branching off from the second pure water supply passage L14, which allows the steam discharged from the outlet of the cooling pipe 11 to flow into the pure water tank 24. The steam discharge passage L17 is equipped with a steam cooling heat exchanger 27 that cools and condenses the steam with cooling water. Incidentally, although I will omit the detailed explanation, the pure water tank 24 is equipped with a pure water system, such as an ion exchange type, that purifies the condensate that returns through the steam discharge passage L17.

[0084] Furthermore, a first on-off valve 28 is provided downstream of the branching point of the third pure water supply channel L15 in the first pure water supply channel L13, and a second on-off valve 29 is provided near the inlet of the cooling pipe 11 in the steam flow path L16. Furthermore, a third on-off valve 30 is provided downstream of the branching point of the steam discharge channel L17 in the second pure water supply channel L14, and a fourth on-off valve 31 is provided in the steam discharge channel L17.

[0085] Therefore, the system is configured to switch to steady-state operation mode by opening the first on-off valve 28 and the third on-off valve 30 and closing the second on-off valve 29 and the fourth on-off valve 31, and to switch to startup operation mode by closing the first on-off valve 28 and the third on-off valve 30 and opening the second on-off valve 29 and the fourth on-off valve 31.

[0086] Incidentally, in this embodiment, the mode switching unit Y that switches between the steady-state operation mode and the startup operation mode is mainly composed of the first on-off valve 28, the second on-off valve 29, the third on-off valve 30, and the fourth on-off valve 31. Furthermore, the first on-off valve 28, the second on-off valve 29, the third on-off valve 30, and the fourth on-off valve 31 are controlled to open and close by the operation control unit M.

[0087] (Details of the stopped operation) When hydrogen purification operations are stopped and hydrogen gas production is halted for an extended period (for example, longer than a few days), hydrogen purging, steam discharge, and hydrogen refueling processes are performed sequentially. In other words, when stopping the hydrogen purification operation, first, while keeping the compressor D running and continuing to mix (supply) steam and heat the reformer H with the reforming burner B, the raw material gas valve V1, the modified gas valve V5, and the return valve V10 are closed, and the hydrogen gas valve V11 and the exhaust valve V12 are opened to perform a hydrogen purging process that supplies the product gas (hydrogen gas) to the closed circulation circuit C. This hydrogen purging process allows the product gas (hydrogen gas) to flow through the closed circulation circuit C, discharging any remaining gas from the closed circulation circuit C through the exhaust passage L12 while simultaneously replacing the inside of the closed circulation circuit C with the product gas (hydrogen gas).

[0088] Next, with compressor D running continuously, the steam mixing (supply) is stopped, the heating of reformer H by reforming burner B is stopped, the hydrogen gas valve V11 and exhaust valve V12 are opened, and the return valve V10 is closed, thereby causing the product gas (hydrogen gas) filled in closed circulation circuit C to flow through closed circulation circuit C, and performing a steam discharge treatment to discharge the steam inside closed circulation circuit C.

[0089] Subsequently, the compressor D is stopped, the steam mixing (supply) is stopped while continuing, the heating of the reformer H by the reforming burner B is stopped while continuing, the hydrogen gas valve V11 and exhaust valve V12 are closed, and a hydrogen filling process is carried out to fill the inside of the closed circulation circuit C with product gas (hydrogen gas). Although not shown in the diagram, a pressure sensor is provided to detect the internal pressure of the closed circulation circuit C. If the internal pressure of the closed circulation circuit C decreases, the hydrogen gas valve V11 is opened to replenish the product gas (hydrogen gas). Although a detailed explanation will be omitted, when shutdown operation is performed, a hydrogen filling process is carried out in which product gas (hydrogen gas) is supplied to and filled the adsorption towers 20a, 20b, and 20c of the PSA unit 22.

[0090] (Regarding startup operation) When restarting operation from a stopped operation state in which the supply of raw material gas G is stopped and the combustion of the reforming burner B is stopped, the operation control unit M first switches the mode switching unit Y to the start operation mode and then performs the start operation (see Figure 2). In other words, with the supply of raw material gas G stopped and the reforming burner B burning, a startup operation is performed in which the heating gas is circulated through the desulfurizer P, reformer H, and CO transformer Q in a manner that it is discharged from the CO transformer Q and returned to the desulfurizer P.

[0091] In other words, with the raw material gas valve V1, the modified gas valve V5, the hydrogen gas valve V11, and the exhaust valve V12 closed, the compressor D is started, and the reformer H is heated by the reforming burner B. The desulfurizer P, the reformer H, and the CO transformer Q are heated while the product gas (hydrogen gas) filled in through the closed circulation circuit C is flowed through it. At this time, the hydrogen gas valve V11 is opened to replenish the product gas (hydrogen gas), which increases the internal pressure of the closed circulation circuit C. Furthermore, when circulating the product gas (hydrogen gas) as a heating gas, a startup operation mode is performed in which pure water W from the pure water tank 24 is supplied to the steam generation heat exchanger J to generate heating steam U, and this heating steam U is supplied to the cooling pipe 11 and the reforming reaction pipe A.

[0092] Subsequently, when the desulfurizer P, reformer H, and CO transformer Q reach a certain temperature, the operation control unit M switches the mode switching unit Y to steady-state operation mode and starts supplying the raw material gas G to perform steady-state operation to generate the transformed gas. In other words, the raw material gas valve V1 and the modified gas valve V5 are opened, and the return valve V10 is closed to generate modified gas, which is then supplied to the PSA device 22. Although a detailed explanation will be omitted, after restarting operation, the PSA unit 22 will exhaust the purified product gas until the hydrogen concentration of the purified product gas reaches or exceeds a set value. Once the hydrogen concentration of the purified product gas reaches or exceeds the set value, the purified product gas will be stored in the product tank 23.

[0093] (Details of standby operation) When hydrogen purification operations are temporarily stopped and hydrogen gas production is temporarily halted (for example, for several hours), standby operation is performed. In other words, the operation control unit M continues heating the reformer H with the reforming burner B, and performs a standby operation in which the product gas (hydrogen gas) filled in the closed circulation circuit C is circulated through the closed circulation circuit C, passing through the compressor D, desulfurizer P, reformer H, and CO transformer Q.

[0094] In other words, in the present invention, the operation control unit M is configured to switch between a state in which hydrogen purification operation is performed and a state in which standby operation is performed in which the hydrogen separation unit 20 is stopped while maintaining the heating of the reformer H by the reforming burner B, and the gas filled in the closed circulation circuit C is circulated through the closed circulation circuit C.

[0095] To elaborate, when transitioning from hydrogen purification operation to standby operation, first, while keeping compressor D running and continuing to mix (supply) steam and heat reformer H with reforming burner B, the raw material gas valve V1, modified gas valve V5, and return valve V10 are closed, and the hydrogen gas valve V11 and exhaust valve V12 are opened to perform a hydrogen purging process that supplies product gas (hydrogen gas) to the closed circulation circuit C. This hydrogen purging process allows the product gas (hydrogen gas) to flow through the closed circulation circuit C, discharging any remaining gas from the closed circulation circuit C through the exhaust passage L12 while simultaneously replacing the inside of the closed circulation circuit C with the product gas (hydrogen gas).

[0096] Subsequently, while the compressor D continues to operate and the reformer H continues to be heated by the reforming burner B, the steam mixing (supply) is stopped, the hydrogen gas valve V11 and exhaust valve V12 are closed, and the return valve V10 is opened, thereby performing a standby operation in which the product gas (hydrogen gas) filled in the closed circulation circuit C is circulated through the closed circulation circuit C.

[0097] Although a detailed explanation will be omitted, when standby operation is performed, a hydrogen replacement process is carried out in which product gas (hydrogen gas) is supplied to and filled the adsorption towers 20a, 20b, and 20c of the PSA unit 22.

[0098] The steam flow during standby operation is the same as that in steady-state operation mode. That is, after stopping the steam mixing as described above and forming a closed circulation circuit C, steam is introduced into the system using the same circuit as in steady-state operation mode, as shown in Figure 4.

[0099] The operation control unit M is configured to determine the fuel flow rate, which is the flow rate of fuel gas supplied to the reforming burner B, based on the temperature of the reforming catalyst S filled in the reforming reaction tube A and the temperature of the steam generated in the steam generation heat exchanger J.

[0100] With this configuration, the fuel flow rate can be determined based on two types of temperatures: the temperature of the reforming catalyst S and the temperature of the steam generated in the steam generation heat exchanger J.

[0101] Furthermore, the operation control unit M sets an upper limit setting value, which is the upper limit reference value for the water vapor temperature, a lower limit setting value, which is the lower limit reference value for the water vapor temperature, and a catalyst temperature setting value, which is the reference value for the temperature of the reforming catalyst S. Based on the difference between the current temperature of the reforming catalyst S and the catalyst temperature setpoint, PID control is performed to calculate the first instruction value, which is the fuel flow rate instruction value. Based on the difference between the current water vapor temperature and the upper limit setting, PID control is performed to calculate the second instruction value, which is the fuel flow rate instruction value. The low selector value is obtained by selecting the lower of the first and second indicated values. Based on the difference between the current water vapor temperature and the lower limit setting, PID control is performed to calculate the third instruction value, which is the fuel flow rate instruction value. The higher of the third indicator value and the low selector indicator value is selected to obtain the high selector indicator value. The system is configured to calculate a final instruction value for adjusting the fuel flow rate by performing PID control based on the difference between the high selector instruction value and the current fuel flow rate, and then to control the opening degree of the flow control valve V20 that adjusts the fuel flow rate based on this final instruction value.

[0102] The phrase "calculate the indicated value" above means that the indicated value is calculated using the manipulated amount (MV value) when the fuel flow range is set to 100%. For example, if the range is 50 Nm 3 For / h, 25Nm 3 When you want to play / h, the instruction value MV=50 is calculated.

[0103] In this configuration, the calculation of the first, second, and third indicated values, and the control of the opening degree of the flow control valve V20 are performed by PID control (Proportional-Integral-Derivative Controller). PID control is preferably performed by a PID calculation unit (not shown) provided in the operation control unit M.

[0104] The PID calculation unit performs a known PID calculation using, for example, the deviation between the input target value (upper or lower limit setting value) and the current water vapor temperature. Alternatively, the PID calculation unit performs a known PID calculation using, for example, the deviation between the input target value (catalyst temperature setting value) and the current temperature of the reforming catalyst S. That is, the PID calculation unit sets the P value, I value, and D value, and outputs the data obtained by calculation using these values ​​as the instruction value.

[0105] The first instruction value is calculated by performing PID control based on the difference between the current temperature of the reforming catalyst S and the catalyst temperature setpoint, and determining a provisional fuel flow rate to minimize the deviation (degree of discrepancy) between the current temperature of the reforming catalyst S and the catalyst temperature setpoint (Figures 9 and 10 (1)).

[0106] The second instruction value is a provisional fuel flow rate calculated by performing PID control based on the difference between the current water vapor temperature and the upper limit setting value, in order to reduce the deviation (degree of discrepancy) between the current water vapor temperature and the upper limit setting value (Figures 9 and 10 (2)).

[0107] In this configuration, a low selector instruction value is obtained by selecting the lower of the first instruction value and the second instruction value. In this way, by obtaining a low selector instruction value based on the first instruction value, which takes into account the current temperature of the reforming catalyst S and the catalyst temperature setpoint, and the second instruction value, which takes into account the current water vapor temperature and the upper limit setpoint, it is possible to obtain a provisional fuel flow rate instruction value that prevents the reforming catalyst S from rising while controlling the water vapor temperature to be lower than the upper limit setpoint.

[0108] The third instruction value is a provisional fuel flow rate calculated by performing PID control based on the difference between the current water vapor temperature and the lower limit setting value, in order to reduce the deviation (degree of discrepancy) between the current water vapor temperature and the lower limit setting value (Figures 9 and 10 (3)).

[0109] In this configuration, the higher of the third instruction value and the low selector instruction value is selected to obtain the high selector instruction value. In this way, by obtaining the high selector instruction value based on the third instruction value, which takes into account the current water vapor temperature and the lower limit setting value, and the low selector instruction value, it is possible to obtain a provisional instruction value for the fuel flow rate that allows control to raise the water vapor temperature above the lower limit setting value.

[0110] The final indicated value is calculated by performing PID control based on the difference between the high selector indicated value and the current fuel flow rate, and minimizing the deviation (degree of discrepancy) between the high selector indicated value and the current fuel flow rate. In this configuration, the opening degree of the flow control valve V20, which adjusts the fuel flow rate, is controlled based on this final indicated value (Figures 9 and 10 (4)).

[0111] Therefore, in this configuration, by controlling the opening degree of the flow control valve V20 based on the final indicated value, it is possible to keep the current steam temperature within an appropriate range (between the upper and lower set limits) while preventing the rise of the reforming catalyst S during standby operation.

[0112] Therefore, in this configuration, compared to the conventional method where the fuel flow rate, which is the flow rate of fuel gas supplied to the reforming burner B during standby operation, was controlled solely by the temperature of the reforming catalyst S, it becomes easier to control the temperature of the water vapor circulating within the system during standby operation to a certain range (between the upper and lower limit settings).

[0113] During closed-circulation operation, the circulating gas within the system is supplied to the reforming reaction tube A in a mixture with water vapor. However, by controlling the temperature of the water vapor within a certain range, the temperature of the water vapor does not easily decrease, making it difficult for water to enter the inside of the reforming reaction tube A. This prevents the reforming catalyst S, which is packed inside the reforming reaction tube A, from coming into contact with water and becoming inactive. Therefore, in the hydrogen production apparatus 100 with this configuration, standby operation, which is an operation to shorten the response time when restarting hydrogen production, can be reliably performed.

[0114] Furthermore, the control method for the hydrogen production apparatus 100 of the present invention includes a water vapor temperature reference value setting step in which an upper limit setting value, which is an upper limit reference value for the water vapor temperature, and a lower limit setting value, which is a lower limit reference value for the water vapor temperature, A catalyst temperature reference value setting step, which sets a catalyst temperature setpoint, which is a reference value for the temperature of the catalyst S for the reforming process, A first instruction value calculation step calculates a first instruction value, which is an instruction value for fuel flow rate, by performing PID control based on the difference between the current temperature of the reforming catalyst S and the catalyst temperature setpoint. A second instruction value calculation step involves performing PID control based on the difference between the current water vapor temperature and the upper limit setting value to calculate a second instruction value, which is the instruction value for fuel flow rate. A low selector indicator value acquisition step obtains a low selector indicator value that selects the lower of the first and second indicator values, A third instruction value calculation step involves performing PID control based on the difference between the current water vapor temperature and the lower limit setting value to calculate a third instruction value, which is the fuel flow rate instruction value. A high selector instruction value acquisition step, which acquires a high selector instruction value by selecting the higher of the third instruction value and the low selector instruction value, The system includes a fuel flow control step which involves performing PID control based on the difference between the high selector indicator value and the current fuel flow rate to calculate a final indicator value for adjusting the fuel flow rate, and controlling the opening degree of the flow control valve V20 that adjusts the fuel flow rate based on the final indicator value.

[0115] The order in which the water vapor temperature reference value setting step and the catalyst temperature reference value setting step are performed does not matter. The order in which the first instruction value calculation step and the second instruction value calculation step are performed does not matter. The third instruction value calculation step and the high selector instruction value acquisition step are performed in this order. The low selector instruction value acquisition step, the high selector instruction value acquisition step and the fuel flow rate control step are performed in this order.

[0116] In the first instruction value calculation step, PID control is performed based on the difference between the current temperature of the reforming catalyst S and the catalyst temperature setpoint, and a provisional instruction value for the fuel flow rate can be calculated to reduce the deviation (degree of discrepancy) between the current temperature of the reforming catalyst S and the catalyst temperature setpoint.

[0117] In the second instruction value calculation step, PID control is performed based on the difference between the current water vapor temperature and the upper limit setting value, and a provisional instruction value for the fuel flow rate can be calculated to reduce the deviation (degree of discrepancy) between the current water vapor temperature and the upper limit setting value.

[0118] In the low selector instruction value acquisition step, the lower of the first instruction value and the second instruction value is selected to acquire the low selector instruction value. In this way, by acquiring the low selector instruction value based on the first instruction value, which takes into account the current temperature of the reforming catalyst S and the catalyst temperature set value, and the second instruction value, which takes into account the current water vapor temperature and the upper limit set value, it is possible to acquire a provisional fuel flow rate instruction value that prevents the reforming catalyst S from rising while controlling the water vapor temperature to be lower than the upper limit set value.

[0119] In the third instruction value calculation step, PID control is performed based on the difference between the current water vapor temperature and the lower limit setting value, and a provisional instruction value for the fuel flow rate can be calculated to reduce the deviation (degree of discrepancy) between the current water vapor temperature and the lower limit setting value.

[0120] In the high selector instruction value acquisition step, the higher of the third instruction value and the low selector instruction value is selected to acquire the high selector instruction value. In this way, by acquiring the high selector instruction value based on the third instruction value, which takes into account the current water vapor temperature and the lower limit setting value, and the low selector instruction value, it is possible to obtain a provisional instruction value for the fuel flow rate that allows control to raise the water vapor temperature above the lower limit setting value.

[0121] In the fuel flow control step, PID control is performed based on the difference between the high selector instruction value and the current fuel flow rate to calculate a final instruction value for adjusting the fuel flow rate, and the opening degree of the flow control valve V20 that adjusts the fuel flow rate can be controlled based on this final instruction value.

[0122] Therefore, in the control method for the hydrogen production apparatus 100 of the present invention, by controlling the opening degree of the flow control valve V20 based on the final instruction value, it is possible to keep the current water vapor temperature within an appropriate range (between the upper limit and lower limit settings) while preventing the rise of the reforming catalyst S during standby operation.

[0123] Therefore, with this control method, compared to the conventional method where the fuel flow rate, which is the flow rate of fuel gas supplied to the reforming burner B during standby operation, was controlled solely by the temperature of the reforming catalyst S, it becomes easier to control the temperature of the water vapor circulating within the system during standby operation to a certain range (between the upper and lower limit settings).

[0124] During closed-circulation operation, the circulating gas within the system is supplied to the reforming reaction tube A in a mixture with water vapor. However, by controlling the temperature of the water vapor within a certain range, the temperature of the water vapor is less likely to drop, making it difficult for water to enter the reforming reaction tube A. This prevents the reforming catalyst S, which is packed inside the reforming reaction tube A, from coming into contact with water and becoming inactive. Therefore, with the control method of the hydrogen production apparatus 100 with this configuration, standby operation, which is an operation to shorten the response time when restarting hydrogen production, can be reliably achieved.

[0125] When transitioning from standby operation to hydrogen purification operation, first, the compressor D is kept running, and the reformer H is kept heated by the reforming burner B. At the same time, the raw material gas valve V1 and the modified gas valve V5 are opened, and the return valve V10 is closed to supply modified gas to the PSA device 22. Although a detailed explanation will be omitted, after restarting operation, the PSA unit 22 will exhaust the purified product gas until the hydrogen concentration of the purified product gas reaches or exceeds a set value. Once the hydrogen concentration of the purified product gas reaches or exceeds the set value, the purified product gas will be stored in the product tank 23. [Examples]

[0126] [Example 1] In the hydrogen production apparatus 100 of the present invention, the fuel flow rate, which is the flow rate of fuel gas supplied to the reforming burner B during standby operation, was controlled by the operation control unit M as follows.

[0127] The upper limit setting value, which is the upper limit reference value for water vapor temperature, is set to 400°C, and the lower limit setting value, which is the lower limit reference value for water vapor temperature, is set to 300°C (water vapor temperature reference value setting step). The catalyst temperature setting value, which is the reference value for the temperature of the reforming catalyst S, is set to 700°C (catalyst temperature reference value setting step).

[0128] The temperature of the catalyst S used for the reforming process (temperature of the catalyst layer) was measured at 600°C using a catalyst temperature sensor, and the temperature of the generated water vapor was measured at 450°C using a water vapor temperature sensor.

[0129] As shown in (1) of Figures 9 and 10, PID control was performed based on the difference between the current temperature of the reforming catalyst S (TI_F1.PV: 600°C) and the catalyst temperature setpoint (TIC_F1F: 700°C) to calculate the first instruction value, which is the fuel flow rate instruction value (first instruction value calculation step). Since the current temperature of the reforming catalyst S is lower than the catalyst temperature setpoint, the first instruction value calculated was an instruction value in the direction of increasing the fuel flow rate.

[0130] As shown in (2) of Figures 9 and 10, PID control was performed based on the difference between the current steam temperature (TI_ST.PV: 450°C) and the upper limit setting value (TIC_STH: 400°C) to calculate the second instruction value, which is the fuel flow rate instruction value (second instruction value calculation step). Since the current steam temperature is higher than the upper limit setting value, the second instruction value calculated was an instruction value that reduces the fuel flow rate.

[0131] The low selector indicator value was obtained by selecting the lower of the first and second indicator values ​​(low selector indicator value acquisition step). In other words, the low selector indicator value obtained was an indicator value that reduces the fuel flow rate.

[0132] In each of the above steps (first instruction value calculation step, second instruction value calculation step, low selector instruction value acquisition step), an instruction value that reduces the fuel flow rate was calculated by considering the current temperature of the reforming catalyst S and the catalyst temperature setpoint, as well as the current water vapor temperature and upper limit setpoint.

[0133] As shown in (3) of Figures 9 and 10, PID control was performed based on the difference between the current water vapor temperature (TI_ST.PV: 450°C) and the lower limit setting value (TIC_STL: 300°C) to calculate the third instruction value, which is the fuel flow rate instruction value (third instruction value calculation step). Since the current water vapor temperature is higher than the lower limit setting value, the third instruction value calculated was an instruction value that reduces the fuel flow rate.

[0134] The higher of the third indicator value and the low selector indicator value was selected to obtain the high selector indicator value (high selector indicator value acquisition step). That is, since both the third indicator value and the low selector indicator value were calculated to decrease the fuel flow rate, the high selector indicator value obtained was a value that decreases the fuel flow rate.

[0135] In each of the above steps (third instruction value calculation step, high selector instruction value acquisition step), the low selector instruction value (considering the current temperature of the reforming catalyst S, the catalyst temperature set value, the current water vapor temperature, and the upper limit set value), and the current water vapor temperature and the lower limit set value were considered to calculate an instruction value that reduces the fuel flow rate.

[0136] As shown in (4) of Figures 9 and 10, a final instruction value is calculated based on the difference between the high selector instruction value and the current fuel flow rate (FI_FG) to adjust the fuel flow rate in a downward direction using PID control, and the opening degree of the flow control valve V20 (FCV_FG) is controlled based on this final instruction value (fuel flow rate control step).

[0137] As described above, in the hydrogen production apparatus 100 (control method for the hydrogen production apparatus 100) of the present invention, even when the current temperature of the steam is higher than the upper limit setting value during standby operation, it was possible to prevent the temperature of the reforming catalyst S from rising, lower the current temperature of the steam below the upper limit setting value, and control it within a certain range (between the upper limit setting value and the lower limit setting value).

[0138] [Example 2] Example 1 described the case where the current temperature of the water vapor is higher than the upper limit setting value. This example describes the case where the current temperature of the water vapor is lower than the lower limit setting value.

[0139] Similar to Example 1, the upper limit setting value for the water vapor temperature was set to 400°C and the lower limit setting value for the water vapor temperature was set to 300°C (water vapor temperature reference value setting step), and the catalyst temperature setting value for the reforming catalyst S was set to 700°C (catalyst temperature reference value setting step).

[0140] The temperature of the catalyst S used for the reforming process was measured at 600°C using a catalyst temperature sensor, and the temperature of the generated water vapor was measured at 250°C using a water vapor temperature sensor.

[0141] As shown in (1) of Figures 9 and 10, PID control was performed based on the difference between the current temperature of the reforming catalyst S (TI_F1.PV: 600°C) and the catalyst temperature setpoint (TIC_F1F: 700°C) to calculate the first instruction value, which is the fuel flow rate instruction value (first instruction value calculation step). Since the current temperature of the reforming catalyst S is lower than the catalyst temperature setpoint, the first instruction value calculated was an instruction value in the direction of increasing the fuel flow rate.

[0142] As shown in (2) of Figures 9 and 10, PID control was performed based on the difference between the current water vapor temperature (TI_ST.PV: 250°C) and the upper limit setting value (TIC_STH: 400°C) to calculate the second instruction value, which is the fuel flow rate instruction value (second instruction value calculation step). Since the current water vapor temperature is lower than the upper limit setting value, the second instruction value calculated was an instruction value in the direction of increasing the fuel flow rate.

[0143] The low selector indicator value was obtained by selecting the lower of the first and second indicator values ​​(low selector indicator value acquisition step). In other words, the low selector indicator value obtained was an indicator value in the direction of increasing the fuel flow rate. As shown in (3) of Figures 9 and 10, PID control was performed based on the difference between the current water vapor temperature (TI_ST.PV: 250°C) and the lower limit setting (TIC_STL: 300°C) to calculate the third instruction value, which is the fuel flow rate instruction value (third instruction value calculation step). Since the current water vapor temperature is lower than the lower limit setting value, the third instruction value calculated was an instruction value in the direction of increasing the fuel flow rate.

[0144] The higher of the third indicator value and the low selector indicator value was selected to obtain the high selector indicator value (high selector indicator value acquisition step). That is, since both the third indicator value and the low selector indicator value were calculated to increase the fuel flow rate, the high selector indicator value obtained was an indicator value that increases the fuel flow rate.

[0145] As shown in (4) of Figures 9 and 10, a final instruction value is calculated based on the difference between the high selector instruction value and the current fuel flow rate (FI_FG) to adjust the fuel flow rate in the direction of increasing it, and the opening degree of the flow control valve V20 is controlled based on this final instruction value (fuel flow rate control step).

[0146] As described above, in the hydrogen production apparatus 100 (control method for the hydrogen production apparatus 100) of the present invention, even when the current temperature of the water vapor is lower than the lower limit setting value during standby operation, it was possible to raise the current temperature of the water vapor above the lower limit setting value while preventing the rise of the reforming catalyst S, and to control it within a certain range (between the upper limit setting value and the lower limit setting value).

[0147] [Reference example 1] In conventional hydrogen production systems, during standby operation, the fuel flow rate, which is the flow rate of fuel gas supplied to the reforming burner B, was controlled solely by the temperature of the reforming catalyst S. In this case, the fuel flow rate was controlled as follows (Figure 11).

[0148] Specifically, the catalyst temperature setpoint for the reforming catalyst S was set, and the fuel flow rate was calculated by performing PID control based on the difference between the current temperature of the reforming catalyst S and the catalyst temperature setpoint.

[0149] In this case, there is no means to control the fuel flow rate based on the temperature of the steam. For example, during long-term standby operation, the temperature of the steam may decrease, and there was a risk that standby operation with steam introduced could not be sustained.

[0150] [Reference example 2] In the above-described examples 1 and 2, the case where the high selector instruction value acquisition step is performed after the low selector instruction value acquisition step was explained. In contrast, the case where the low selector instruction value acquisition step is performed after the high selector instruction value acquisition step will be explained (Figure 12). In this case, PID control is performed based on the difference between the current water vapor temperature and the lower limit setting value before the high selector instruction value acquisition step, and PID control is performed based on the difference between the current water vapor temperature and the upper limit setting value before the low selector instruction value acquisition step.

[0151] Similar to Examples 1 and 2, the upper limit setting value for the water vapor temperature was set to 400°C and the lower limit setting value for the water vapor temperature was set to 300°C (water vapor temperature reference value setting step), and the catalyst temperature setting value for the reforming catalyst S was set to 700°C (catalyst temperature reference value setting step).

[0152] If the temperature of the catalyst S used for the reforming process is measured at 850°C using a catalyst temperature sensor, and the temperature of the generated water vapor is measured at 250°C using a water vapor temperature sensor, the control would be as follows, for example.

[0153] As shown in Figure 12(1), PID control was performed based on the difference between the current temperature of the reforming catalyst S (850°C) and the catalyst temperature setpoint (700°C) to calculate the first reference indicator value, which is the indicated value for fuel flow rate (first reference indicator value calculation step). Since the current temperature of the reforming catalyst S is higher than the catalyst temperature setpoint, the first reference indicator value calculated was an indicator value that reduces the fuel flow rate.

[0154] As shown in Figure 12 (2), PID control was performed based on the difference between the current water vapor temperature (250°C) and the lower limit setting value (300°C) to calculate the second reference indicator value, which is the indicated value for the fuel flow rate (second reference indicator value calculation step). Since the current water vapor temperature is lower than the lower limit setting value, the second reference indicator value calculated was an indicator value that increases the fuel flow rate.

[0155] The higher of the first and second reference indicator values ​​was selected to obtain the high selector indicator value (high selector indicator value acquisition step). In other words, the high selector indicator value obtained was an indicator value that increases the fuel flow rate.

[0156] As shown in Figure 12 (3), PID control was performed based on the difference between the current water vapor temperature (250°C) and the upper limit setting value (400°C) to calculate the third reference indicator value, which is the indicated value for the fuel flow rate (third reference indicator value calculation step). Since the current water vapor temperature is lower than the upper limit setting value, the third reference indicator value calculated was an indicator value that increases the fuel flow rate.

[0157] The low selector indicator value was obtained by selecting the lower of the third reference indicator value and the high selector indicator value (low selector indicator value acquisition step). That is, since both the third reference indicator value and the high selector indicator value are calculated to increase the fuel flow rate, the low selector indicator value obtained is an indicator value that increases the fuel flow rate.

[0158] As shown in Figure 12 (4), PID control is performed based on the difference between the low selector instruction value and the current fuel flow rate to calculate a final instruction value that adjusts the fuel flow rate in a direction that increases it, and the opening degree of the flow control valve V20 is controlled based on this final instruction value (fuel flow rate control step).

[0159] Thus, even though the current temperature of the reforming catalyst S (850°C) was higher than the catalyst temperature setpoint (700°C), the control system was adjusted to increase the fuel flow rate.

[0160] Since the temperature of the reforming catalyst S rises further when the fuel flow rate increases, it was considered undesirable to adjust the control to increase the fuel flow rate when the current temperature of the reforming catalyst S is higher than the catalyst temperature setpoint, as this could lead to catalyst degradation and other problems.

[0161] Therefore, as in this reference example, it was found that performing the low selector instruction value acquisition step after the high selector instruction value acquisition step results in control that may lead to catalyst degradation, etc. Thus, as in Examples 1 and 2 of the present invention described above, by performing the high selector instruction value acquisition step after the low selector instruction value acquisition step, it is possible to control the current water vapor temperature to stay within a certain range (between the upper and lower limit settings) while preventing the rise of the reforming catalyst S during standby operation.

[0162] [Another embodiment] (1) In the above embodiment, when the hydrogen purification operation is stopped and the production of hydrogen gas is stopped for a long period of time, a configuration in which hydrogen purging, steam discharge, and hydrogen filling are performed sequentially is illustrated. However, in the steam discharge, instead of product gas (hydrogen gas), an inert gas (nitrogen gas, etc.) stored in an inert gas storage cylinder (for example, a nitrogen cylinder, etc.) may be supplied to the closed circulation circuit C, and in the hydrogen filling process, the inert gas (nitrogen gas, etc.) may be filled into the closed circulation circuit C. In other words, instead of hydrogen filling, the process may be carried out by filling with an inert gas (such as nitrogen gas).

[0163] In this manner, when filling the closed-circuit circuit C with an inert gas (such as nitrogen gas), the startup operation is performed first by supplying the product gas (hydrogen gas) to the closed-circuit circuit C while simultaneously performing an inert gas discharge process to discharge the inert gas (such as nitrogen gas) from the closed-circuit circuit C. Then, with the mode switching unit Y switched to the startup operation mode, the startup operation is performed (see Figure 2). In other words, with the raw material gas valve V1, the modified gas valve V5, the hydrogen gas valve V11, and the exhaust valve V12 closed, the compressor D is started, the reformer H is heated by the reforming burner B, and the desulfurizer P, reformer H, and CO transformer Q are heated up while the product gas (hydrogen gas) used as a heating gas, which has been filled through the closed circulation circuit C, flows through the circuit. At that time, the pure water W from the pure water tank 24 is supplied to the steam generation heat exchanger J to generate heating steam U, and the startup operation mode is performed in which the heating steam U is supplied to the cooling pipe 11.

[0164] (2) In the above embodiment, a reformer H equipped with multiple reforming reaction tubes A was illustrated, but the present invention can also be applied to a reformer H equipped with a single reforming reaction tube A.

[0165] (3) In the above embodiment, the reformer H is shown as being equipped with a steam generation heat exchanger J and an air preheating heat exchanger N, but the reformer H may also be formed in a manner that does not include a steam generation heat exchanger J and an air preheating heat exchanger N.

[0166] (4) In the above embodiment, an example was given in which a hydrogen separation unit 20 is provided to separate hydrogen gas from the modified gas from the reforming unit R. However, the embodiment may also be carried out in a manner in which the modified gas is used as is, such as by supplying the modified gas to a gas engine as the product gas.

[0167] (5) In the embodiments described above, standby operation was given as an example of closed-circulation operation, and the case in which the fuel flow rate, which is the flow rate of fuel gas supplied to the reforming burner B during standby operation, is controlled to control the temperature of the steam within a certain range (between the upper limit and lower limit setting values) was explained. However, the control of the steam temperature is not limited to standby operation, and for example, the above-described start-up operation can be applied as a closed-circulation operation, and it can also be applied when controlling the temperature of the heating steam U during start-up operation within a certain range (between the upper limit and lower limit setting values). (6) In the embodiments described above, an upper limit value, which is an upper reference value, and a lower limit value, which is a lower reference value, were set for the temperature of the water vapor. However, the embodiments are not limited to this form, and an upper limit value and a lower limit value may also be set for the temperature of the reforming catalyst S.

[0168] Furthermore, the configurations disclosed in the above embodiments (including other embodiments, the same applies hereinafter) can be applied in combination with configurations disclosed in other embodiments, as long as no inconsistencies arise. Moreover, the embodiments disclosed herein are illustrative, and the embodiments of the present invention are not limited thereto, and can be modified as appropriate without departing from the object of the present invention. [Industrial applicability]

[0169] The present invention can be used in a hydrogen production apparatus and a control method thereof, which comprises a desulfurizer for desulfurizing a supplied raw material gas, a reformer equipped with a reforming reaction tube having a reforming catalyst for steam reforming the raw material gas from the desulfurizer to produce reformed gas and a reforming burner for heating the reforming reaction tube, a CO reformer having a carbon monoxide reforming catalyst for reforming carbon monoxide contained in the reformed gas from the reformer to produce reformed gas, a hydrogen separation unit for separating impurities other than hydrogen from the reformed gas after treatment in the CO reformer to purify hydrogen gas, and a steam generation heat exchanger for heating water for steam generation with the combustion gas of the reforming burner to generate steam to be mixed with the raw material gas, and a gas flow passage for gas to flow across the desulfurizer, the reformer, the CO reformer and the hydrogen separation unit, and which supplies raw material gas to the gas flow passage to perform hydrogen purification operation. [Explanation of Symbols]

[0170] A Reforming Reaction Tube B. Burner for modification C closed circuit H Modifier J Heat exchanger for steam generation M Operation Control Unit P desulfurizer S Catalyst for Reforming Treatment Z Carbon monoxide modified catalyst 17 CO transformer 20 Hydrogen separation section 100 Hydrogen production equipment

Claims

1. The system includes a desulfurizer for desulfurizing the supplied raw material gas, a reformer equipped with a reforming reaction tube having a reforming catalyst for steam reforming the raw material gas from the desulfurizer to produce reformed gas, and a reforming burner for heating the reforming reaction tube, a CO reformer equipped with a carbon monoxide conversion catalyst for converting carbon monoxide contained in the reformed gas from the reformer to carbon dioxide to produce reformed gas, a hydrogen separation unit for separating impurities other than hydrogen from the reformed gas after treatment in the CO reformer to purify hydrogen gas, and a steam generation heat exchanger for heating water for steam generation with the combustion gas of the reforming burner to generate steam to be mixed with the raw material gas. A hydrogen production apparatus is provided with a gas flow passage through which gas flows across the desulfurizer, the reformer, the CO transformer, and the hydrogen separation section, and a raw material gas is supplied to the gas flow passage to perform hydrogen purification operation, A closed circulation circuit is provided in the gas flow passage that circulates the gas in the order of the desulfurizer, the reformer, and the CO transformer, bypassing the hydrogen separation section. The system includes an operation control unit that switches between a state in which the hydrogen purification operation is performed and a state in which a closed circulation operation is performed in which the hydrogen separation unit is stopped while maintaining the heating of the reformer by the reforming burner, and the gas filled in the closed circulation circuit is circulated through the closed circulation circuit. The operation control unit is configured to determine the fuel flow rate, which is the flow rate of fuel gas supplied to the reforming burner, based on the temperature of the reforming catalyst filled in the reforming reaction tube and the temperature of the steam generated in the steam generation heat exchanger. Furthermore, the operation control unit, An upper limit setting value, which is the upper limit reference value for the water vapor temperature, a lower limit setting value, which is the lower limit reference value for the water vapor temperature, and a catalyst temperature setting value, which is the reference value for the temperature of the catalyst for the reforming treatment, are set. Based on the difference between the current temperature of the reforming catalyst and the catalyst temperature setpoint, PID control is performed to calculate the first instruction value, which is the instruction value for the fuel flow rate. Based on the difference between the current water vapor temperature and the upper limit setting, PID control is performed to calculate the second instruction value, which is the instruction value for the fuel flow rate. The lower of the first and second indicated values ​​is selected to obtain a low selector indicator value. Based on the difference between the current water vapor temperature and the lower limit setting, PID control is performed to calculate the third instruction value, which is the instruction value for the fuel flow rate. The higher of the third indicator value and the low selector indicator value is selected to obtain the high selector indicator value. A hydrogen production apparatus configured to calculate a final instruction value for adjusting the fuel flow rate by performing PID control based on the difference between the high selector instruction value and the current fuel flow rate, and to control the opening degree of a flow control valve that adjusts the fuel flow rate based on the final instruction value.

2. The hydrogen production apparatus according to claim 1, wherein the closed-circulation operation is a standby operation.

3. A control method for a hydrogen production apparatus according to claim 1 or 2, A water vapor temperature reference value setting step, which sets an upper limit reference value, which is the upper limit reference value of the water vapor temperature, and a lower limit reference value, which is the lower limit reference value of the water vapor temperature. A catalyst temperature reference value setting step, which sets a catalyst temperature setpoint, which is a reference value for the temperature of the catalyst for the reforming treatment, A first instruction value calculation step involves performing PID control based on the difference between the current temperature of the reforming catalyst and the catalyst temperature setpoint to calculate a first instruction value, which is the instruction value for the fuel flow rate. A second instruction value calculation step involves performing PID control based on the difference between the current water vapor temperature and the upper limit setting value to calculate a second instruction value, which is the instruction value for the fuel flow rate. A low selector instruction value acquisition step, which acquires a low selector instruction value by selecting the lower of the first instruction value and the second instruction value, A third instruction value calculation step involves performing PID control based on the difference between the current water vapor temperature and the lower limit setting value to calculate a third instruction value, which is the instruction value for the fuel flow rate. A high selector instruction value acquisition step, which acquires a high selector instruction value by selecting the higher of the third instruction value and the low selector instruction value, A control method for a hydrogen production apparatus, comprising: a fuel flow control step of performing PID control based on the difference between the high selector instruction value and the current fuel flow rate to calculate a final instruction value for adjusting the fuel flow rate, and controlling the opening degree of a flow control valve that adjusts the fuel flow rate based on the final instruction value.

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