Hydrogen production apparatus and hydrogen production method

Abstract

The present invention provides a hydrogen production apparatus and method that enables operation of the hydrogen production apparatus at a lower load and operation without discharging product hydrogen outside the system. [Solution] A portion of the purified hydrogen gas G4 from the hydrogen purification unit 40 is recycled into the raw material introduction line L1 on the inlet side of the compressor 10 via the recycled hydrogen line L. 11 Equipped with, during normal operation of hydrogen production, the recycled hydrogen line L 11 The purified hydrogen gas recycled is supplied as the amount of hydrogen required for the hydrogenation reaction in the desulfurizer 14, and during low-load idle operation, the recycled hydrogen line L 11 Recycled purified hydrogen gas (recycled hydrogen gas for idle operation) 4b The amount of gas in the desulfurizer 14 is used for the hydrogenation reaction (recycled hydrogen G for hydrogenation). 4a Supply in quantities 4 to 10 times the normal amount.

Description

Technical Field

[0001] The present invention relates to a hydrogen production device and a hydrogen production method.

Background Art

[0002] Conventionally, a hydrogen production device is known to supply hydrocarbon gases such as natural gas and LPG as raw material gases to a reformer together with steam and react them with a reforming catalyst to produce a hydrogen-containing gas (for example, see Patent Documents 1 to 3). Since the product hydrogen produced continuously in a hydrogen production device for industrial use is generally consumed, it is often operated continuously day and night. Also, if it is operated continuously day and night, the efficiency can be increased, and as a result, the unit price of hydrogen can be reduced.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] Among the users of hydrogen production devices, there are cases where, since hydrogen production is not required at night or on holidays, they are required to set the hydrogen delivery amount to zero without stopping the device. When the hydrogen production device is stopped when hydrogen is not needed, there is a problem that it takes several hours to half a day to restart, and it cannot be used immediately the next day, which hinders the user's production operations.

[0005] Also, in the conventional operation method, in order to suppress the hydrogen generation amount as much as possible, even when operating at the minimum load, the produced hydrogen that still occurs is vented or incinerated, resulting in a loss of product hydrogen. Therefore, there is a strong desire to operate the hydrogen production apparatus at a lower load and to realize an operation in which the produced hydrogen is not sent out of the system.

[0006] The present invention has been made in view of the above problems, and an object thereof is to provide a hydrogen production apparatus and a hydrogen production method capable of operating the hydrogen production apparatus at a lower load and realizing an operation in which the produced hydrogen is not sent out of the system.

Means for Solving the Problems

[0007] The hydrogen production apparatus according to the first aspect of the present invention includes a raw material introduction line for introducing a raw material gas, a desulfurizer provided in the raw material introduction line for desulfurizing sulfur components in the raw material gas, a reformer for reforming the raw material gas after desulfurization, a converter for converting the reformed gas after reforming by the reformer, a hydrogen purification apparatus for purifying the converted gas after conversion by the converter, a recycle hydrogen line for recycling a part of the purified hydrogen gas from the hydrogen purification apparatus to the raw material introduction line on the inlet side of the compressor, and is a hydrogen production apparatus characterized in that during normal operation of hydrogen production, the delivery amount of the purified hydrogen gas recycled through the recycle hydrogen line is the hydrogen required for the hydrogenation reaction in the desulfurizer, and during low-load idle operation, the delivery amount of the purified hydrogen gas recycled throughthe recycle hydrogen line is 4 to 10 times the amount of hydrogen for the hydrogenation reaction in the desulfurizer.

[0008] The hydrogen production method according to the second aspect of the present invention includes a raw material introduction line for introducing a raw material gas, a desulfurizer provided in the raw material introduction line for desulfurizing sulfur components in the raw material gas, a reformer for reforming the raw material gas after desulfurization, a converter for converting the reformed gas after reforming by the reformer, a hydrogen purification apparatus for purifying the converted gas after conversion by the converter, A hydrogen recycling line that recycles a portion of the purified hydrogen gas from the hydrogen purification apparatus to the raw material introduction line on the inlet side of the compressor, Using a hydrogen production apparatus equipped with, During normal operation of hydrogen production, the amount of purified hydrogen gas recycled in the recycling hydrogen line is supplied to provide the hydrogen necessary for the hydrogenation reaction in the desulfurizer, During low-load idle operation, the amount of purified hydrogen gas to be recycled in the recycling hydrogen line is characterized by supplying 4 to 10 times the amount of hydrogen used for the hydrogenation reaction in the desulfurizer. [Effects of the Invention]

[0009] According to the present invention, the amount of product hydrogen supplied outside the hydrogen production apparatus is virtually zero, significantly reducing the net raw material load, and also reducing the fuel consumption of the reformer burner.

[0010] Furthermore, by increasing the amount of recycled hydrogen supplied to the raw gas side during idle operation to 4 to 10 times the normal amount, and by utilizing the surplus hydrogen produced as fuel for the reformer burner, the effective amount of product hydrogen is reduced to zero. In this idle operation, utilizing the surplus product hydrogen as fuel makes it possible to significantly reduce the consumption of hydrocarbon fuel gas. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram of the hydrogen production apparatus according to this embodiment of the present invention. [Figure 2] This is a schematic diagram of the hydrogen production apparatus according to this embodiment of the present invention. [Figure 3] This is a schematic diagram of the hydrogen production apparatus according to this embodiment of the present invention. [Figure 4] This is another schematic diagram of the hydrogen production apparatus according to this embodiment of the present invention. [Figure 5] This is a schematic diagram showing the amount of recycled hydrogen when transitioning from normal operation to idle operation according to the present invention. [Modes for carrying out the invention]

[0012] Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the embodiments described below. Furthermore, the components in the embodiments below include those that are easily conceivable by those skilled in the art, those that are substantially the same, and those that are equivalent. Moreover, the components disclosed in the embodiments below can be combined as appropriate. In the embodiments described herein, the same reference numerals are used for the same components throughout. This embodiment is merely an example illustrating the configuration of the present invention, and various design modifications can be made without departing from the claims.

[0013] Figure 1 is a schematic diagram of the normal operation of the hydrogen production apparatus of this embodiment. Figure 2 is a schematic diagram of the transition state to idle operation of the hydrogen production apparatus of this embodiment. Figure 3 is a schematic diagram of the idle operation state of the hydrogen production apparatus of this embodiment. Figure 4 is another schematic diagram of the idle operation state of the hydrogen production apparatus of this embodiment. Figure 5 is a schematic diagram showing the amount of recycled hydrogen when transitioning from normal operation to idle operation according to the present invention.

[0014] Embodiments of the present invention will be described in detail below with reference to the drawings. In the embodiments described herein, the same reference numerals are used for the same components throughout the text.

[0015] First, let's describe the hydrogen production apparatus. Figure 1 is a schematic system diagram showing an embodiment of the hydrogen production apparatus according to the present invention. As shown in Figure 1, the hydrogen production apparatus 100-1 of this embodiment mainly comprises a desulfurizer 14, a reformer 20 equipped with a reforming tube 21, a transformer 30, a pressure swing adsorption device (hereinafter also referred to as "PSA") unit 40, and an off-gas holder 45. In Figure 1, the symbols 10, 11, 12, 13, 15, 14, 15 are indicated as follows: 10 is the compressor, 11 is the raw material flow meter, 12 is the raw material flow control valve, 13 is the raw material preheater, 15 is the raw material heater, 22 is the combustion burner, 23 is the air blower, 24 is the gas boiler, 31 is the gas boiler / gas cooler, 41 is the product hydrogen delivery pressure meter, 42 is the product hydrogen delivery pressure control valve, 43 is the product hydrogen gas delivery valve, 44 is the fuel hydrogen gas shutoff valve, 46 is the off-gas pressure meter, 47 is the off-gas pressure control valve, 48 is the recycled hydrogen flow meter, 49 is the recycled hydrogen flow control valve, 50 is the product hydrogen release shutoff valve, G1 is the raw material gas, G2 is the reformed gas, G3 is the modified gas, G4 is the purified gas, and G5 is the off-gas.

[0016] As shown in Figure 1, the hydrogen production apparatus 100-1 according to this embodiment comprises a raw material introduction line L1 for introducing raw material gas G1, a desulfurizer 14 provided in the raw material introduction line L1 for desulfurizing the sulfur (S) content in the raw material gas G1, a reformer 20 for reforming the raw material gas after desulfurization, a transformer 30 for transforming the reformed gas G2, and a hydrogen purification apparatus (e.g., a PSA unit) 40 for purifying the transformed gas G3, wherein a portion of the purified gas G4 from the hydrogen purification apparatus 40 is recycled to the raw material introduction line L1 on the inlet side of the compressor 10, and a recycling hydrogen line L 11 It is equipped with the following features.

[0017] Furthermore, during normal operation of hydrogen production, the recycled hydrogen line L 11 The purified hydrogen gas recycled in the desulfurizer 14 is supplied as the amount of hydrogen required for the hydrogenation reaction. Furthermore, during low-load standby operation (idle operation), the recycled hydrogen line L 11 Recycled purified hydrogen gas (recycled hydrogen gas for idling) 4b The amount of gas in the desulfurizer 14 is used for the hydrogenation reaction (recycled hydrogen G for hydrogenation). 4a It is supplied in an amount 4 to 10 times the amount of ) the normal amount. In other words, hydrogen G for idling 4b The amount recycled is hydrogen for hydrogenation G 4a If we consider "0.05 times the amount of raw gas" as 1 (normal), then it is 4 to 10 times that amount.

[0018] The desulfurizer 14 removes sulfur components contained as odorants in hydrocarbon fuels such as city gas and LPG. Since sulfur components become catalyst poisons for the reforming catalyst and conversion catalyst used in the reformer 20 in subsequent processes, the sulfur components contained in the raw material gas G1 are removed in advance by this desulfurizer 14.

[0019] Specifically, the desulfurizer 14 consists of a flow path filled with a hydrogenation desulfurization catalyst, which is composed of a hydrogenation catalyst such as a Co-Mo or Ni-Mo system and a ZnO-based desulfurization catalyst that adsorbs hydrogen sulfide. The desulfurizer 14 is supplied with raw material gas G1 and hydrogen to carry out a hydrogenation reaction (hereinafter referred to as "hydrogenation"), converting sulfur components into hydrogen sulfide, incorporating the hydrogen sulfide into zinc oxide to form zinc sulfide, and removing the sulfur components.

[0020] The reaction equations for this hydrogenation desulfurization are as shown in the following reaction equations (1) and (2). CmHnS + H2 → CmHn + H2S ... (1) H2S + ZnO → H2O + ZnS ... (2)

[0021] Furthermore, the desulfurizer 14 may perform desulfurization using an adsorbent for sulfur compounds that reacts at room temperature or high temperature, rather than using a hydrogenation reaction as in this embodiment. Also, if the raw material gas G1 does not contain sulfur components, it is not necessary to provide the desulfurizer 14.

[0022] The reformer 20 adds steam (or pure water) to the raw material gas G1 and brings it into contact with a reforming catalyst (hereinafter referred to as "catalyst"), described later, at a high temperature (for example, 650°C to 900°C) to reform the raw material gas G1 and produce reformed gas G2 such as hydrogen and carbon monoxide. The reaction equations for this steam reforming are as shown in the following reaction equations (3) and (4). CmHn+mH2O→mCO+(m+n / 2)H2...(3) CO + 3H2 ←→ CH4 + H2O···(4)

[0023] These steam reforming reactions are endothermic. To prevent carbon deposition on the catalyst surface, the steam / carbon ratio of the mixture should preferably be approximately 3:1.

[0024] This reformer 20 is equipped with reforming tubes 21 filled with a catalyst for steam reforming. Multiple reforming tubes 21 are arranged and housed inside the reactor.

[0025] Then, the reformer 20 processes a portion of the raw material gas G1. 1a Fuel gas F (off-gas G5) from the PSA unit 40, described later, is supplied to the burner 22 along with air from the air blower 23, and the reforming tube 21 in the reactor is heated to a predetermined temperature (for example, about 950°C).

[0026] The transformer 30 reacts the carbon monoxide in the reformed gas G2 sent from the reformer 20 with water vapor to produce even more hydrogen H2. The reaction equation for this CO transformation is shown in reaction equation (5) below. CO + H2O ←→ CO2 + H2···(5)

[0027] In this transformer 30, depending on the reaction temperature, for example, between 200°C and 500°C, catalysts such as Fe-Cr, Cu-Zn, or Pt are used.

[0028] The hydrogen purification unit, PSA unit 40, uses an adsorbent to adsorb impurity gases other than hydrogen (H2), such as carbon monoxide, carbon dioxide, methane, and water vapor. It separates purified gas G4, which contains only hydrogen (H2), from the modified gas G3, and can ultimately reduce the hydrogen concentration to approximately 99.999%. The off-gas G5 generated by this hydrogen purification unit 40 is sometimes used as fuel for the burner 22 that heats the reformer 20. The PSA unit 40 is designed to return the impurities to a state where they can be adsorbed again through the aforementioned desorption process. The produced hydrogen is then pressurized to approximately 20 MPa using a hydrogen compressor (not shown) and sent to the shipping facility. Also, when the demand for hydrogen is low, the system according to the present invention enables idling operation to maintain the temperature of the catalyst. During idling operation, by using the generated hydrogen as a heat source, it is possible to reduce the amount of raw material gas used.

[0029] Furthermore, the hydrogen production apparatus 100-1 is provided with the following components. (1) The raw material gas G1 from the raw material supply source is compressed by the compressor 10, and a raw material flow rate control valve 12 is provided in the raw material introduction line L1. (2) The reformed gas G2 reformed by the reforming tubes 21 of the reformer 20 is supplied to the transformer 30 via the reformed gas line L2. (3) The transformed gas G'3 from the transformer 30 is sent to the PSA unit 40, which is a hydrogen purification apparatus, via the transformed gas line L3. The fed transformed gas G3 is purified within the PSA unit 40. (4) On the outlet side of the hydrogen purification apparatus 40, a hydrogen extraction line L4 for extracting the purified purified gas (hydrogen H2) G4 is provided. This hydrogen extraction line L4 is equipped with a product hydrogen delivery pressure gauge 41, a product hydrogen delivery pressure control valve 42, and a product hydrogen gas delivery valve 43. (5) From the raw material supply source, a fuel line L 1a supplies fuel gas G 1-1 to the burner 22 of the reformer 20. (6) An off-gas line L 12 is provided to supply the off-gas G5 from the hydrogen purification apparatus 40 to the burner 22. And this off-gas line L 12 is equipped with an off-gas holder 45 and an off-gas pressure control valve 47. [[ID=2)6]](7) On the downstream side of the desulfurizer 14, a pure water supply line L 20 is connected, and this pure water supply line L 20 is equipped with a pure water control valve (not shown). A heat exchanger (not shown) is provided in this pure water supply line L 20 to convert the supplied pure water into steam. Note that steam may be directly supplied separately.

[0030] With this configuration, the hydrogen production apparatus 100-1 processes raw material gas (hereinafter referred to as "reforming raw material") G via the compressor 10. 1b The material is sent to the desulfurizer 14 to remove sulfur components, and then the desulfurized reformed raw material G 1b The mixture is supplied to the reformer 20 along with pure water (steam). In the reformer 20, reformed gas G2 containing hydrogen H2 is generated, and the reformed gas G2 is sent to the transformer 30, where it is further transformed into transformed gas G3. Subsequently, the liquid is separated from the transformed gas G3 in a gas-liquid separator (not shown), and the PSA unit 40 adsorbs everything except hydrogen H2 as off-gas G5 to produce a large amount of purified gas G4, which is product hydrogen H2.

[0031] The equipment configuration of hydrogen production apparatus 100-1 is as described above, with hydrocarbons such as methane and LPG used as raw material gas G1, and a portion of it used as fuel gas G 1a Hydrogenated recycled hydrogen (H2) G 4a The gas mixed with reforming raw material G 1b After the compressor 10 increases the pressure to a predetermined level (for example, about 0.9 MPa), the flow rate is adjusted by the raw material flow meter 11 and the raw material flow control valve 12, and the raw material gas G1 is heated to a predetermined level in the raw material preheater 13 to the level of fuel gas G 1a Modified raw material G, which was branched from 1b It is heated.

[0032] Subsequently, it passes through the desulfurizer 14, is mixed with pure water or steam, is heated in the raw material heater 15, and is reformed in the reforming tube 21. 1b This is then reformed into hydrogen-rich reformed gas G2 through a reforming reaction.

[0033] Next, the reformed gas G2 undergoes heat exchange in the gas boiler 24, and then in the transformer 30, the hydrogen fraction of the hydrogen-rich reformed gas G2 is further increased, and in the PSA unit 40, purified gas G4 of high purity hydrogen is produced.

[0034] A portion of this refined gas G4 is recycled hydrogen G 4a It is used as such (the flow rate is fixed at 0.05 times the raw material flow rate at rated load). This recycled hydrogen G 4a The supply rate is preferably set to 0.05 times the raw material flow rate at rated load. Normally, this is fixed in each hydrogen production system.

[0035] This recycled hydrogen G 4a The flow rate is adjusted by the recycled hydrogen flow meter 48 and the recycled hydrogen flow control valve 49, and the off-gas G5, which is an impurity gas captured by the PSA unit 40, is used as fuel for the burner 22 of the reformer 20 via the off-gas holder 45.

[0036] In idle operation in this embodiment, the amount of recycled hydrogen is set to 4 to 10 times the raw material flow rate at rated load, so that the majority of the generated hydrogen is recycled hydrogen G 4a It will be used as modified raw material G 1b The raw material composition becomes hydrogen-rich, making it possible to significantly reduce the consumption of raw material gas.

[0037] The raw material flow rate meter 11 of this device measures the flow rate obtained by subtracting the fuel used from the supplied hydrocarbon raw material gas G1 and adding the amount of recycled hydrogen, and adjusts the flow rate with the raw material flow rate control valve 12 according to the load of the device. For example, when idle operation is performed at a load of 25% of the rated load, the adjusted flow rate is equivalent to a 25% load, but because the proportion of recycled hydrogen within that amount increases, the amount of hydrocarbon raw material decreases.

[0038] The operating conditions during normal hydrogen production will be explained with reference to Figure 1. In this invention, "normal operation" refers to operation with a load of 30-100%. "Low-load operation" refers to operation with a load of less than 30%.

[0039] First, as shown in Figure 1, during normal operation of hydrogen production, the recycled hydrogen line L 11 The purified hydrogen gas recycled is used for the hydrogenation reaction in the desulfurizer 14 (recycled hydrogen G for hydrogenation). 4aIt is supplied in the specified quantity. This flow rate is fixed at 0.05 times the raw material flow rate at rated load.

[0040] Figure 2 shows the low-load standby operation (idle operation: load less than 30%), and the recycled hydrogen line L 11 Recycled purified hydrogen gas (recycled hydrogen gas for idle operation) 4b The amount of gas in the desulfurizer 14 is used for the hydrogenation reaction (hydrogenated recycled hydrogen G 4a The supply will be 4 to 10 times the specified amount. Furthermore, as will be explained later, this supply will be gradually increased.

[0041] Figure 3 shows that during low-load standby operation (idle operation: load less than 30%), the increase in recycled hydrogen is completed and surplus hydrogen is discharged, and of the generated hydrogen G4, hydrogenated recycled hydrogen G 4a Hydrogen that is not being used as such, i.e., surplus hydrogen (off-gas introduced hydrogen G 4c ) is the surplus hydrogen introduction line L 13 This allows the fuel to be transported to the off-gas holder 43 and mixed with off-gas G5 to become fuel F for the burner 22, thereby reducing the consumption of hydrocarbon fuel gas.

[0042] Based on the above, the operating method of the present invention makes it possible to reduce the amount of product hydrogen (G4) supplied to the outside of the device to virtually zero, thereby significantly reducing the net raw material load and also reducing fuel consumption.

[0043] Also, recycled hydrogen G for idle operation during idle driving 4b By increasing the amount of hydrogen supplied to the raw material gas side to 4 to 10 times the normal amount, and further utilizing the surplus hydrogen produced as fuel, the effective amount of product hydrogen becomes zero. Thus, in idle operation, excess hydrogen (G4) of product hydrogen (G4) 4c By using ) as fuel gas F, it becomes possible to significantly reduce the consumption of hydrocarbon fuel gas.

[0044] Unlike conventional systems, the device does not completely shut down during idle operation, and because it is idle operation, it can quickly return to normal operation.

[0045] Raw material gas G1 and recycled hydrogen G for idling 4b As a result of the introduction of modified raw material G 1b The hydrogen content increases, and the total reforming raw material G 1b The flow rate increases. As a result, even during low-load idle periods, the flow rate can be measured by the raw material flow rate meter 11 and controlled by the control valve.

[0046] In addition, recycled hydrogen G for idling is used as the raw material gas G1. 4b As a result of its introduction, the process-side flow rate in the raw material preheater 13, raw material heater 15, and reformer 20 increases, making it possible to avoid overheating.

[0047] The raw material load is reduced to produce only a very small amount of hydrogen, and the surplus hydrogen gas is used as fuel for the reformer.

[0048] Idle operation can be achieved without making major changes to the equipment or altering any special load equipment.

[0049] Here, in order to eliminate hydrogen emission during the increased amount of recycled hydrogen, the fuel hydrogen gas shut-off valve 44 is immediately opened to shut off the off-gas line L 12 Introducing this system could lead to an excess of fuel, potentially disrupting the thermal balance.

[0050] Therefore, in this embodiment, as shown in Figure 2, recycled hydrogen G for idle 4b We have started increasing the amount of recycled hydrogen G for idle 4b Once the increase in hydrogen reaches the specified amount, the system controls the opening of the fuel hydrogen gas shutoff valve 44 and the closing of the product hydrogen emission shutoff valve 50, as shown in Figure 3.

[0051] Here, when the fuel hydrogen gas shutoff valve 44 is opened and the product hydrogen release shutoff valve 50 is closed, as shown in Figure 4 as a modified example of Figure 3, during idle operation, excess hydrogen (G) of product hydrogen (G4) 4c When using ) as fuel F, it is also possible to supply it directly to the burner 22 as fuel without introducing it into the off-gas holder 45. However, as shown in the system configuration of Figure 3, supplying it to the off-gas holder 45 is preferable because it averages out the calories of the fuel F, resulting in more stable operation.

[0052] Figure 5 shows the changes in recycled hydrogen during normal operation (30-100% load), idle operation (recycled hydrogen increase in progress "less than 30% load"), and idle operation (recycled hydrogen increase completed / surplus hydrogen discharge "less than 30% load"). Figure 5 is a graph showing the increase in hydrogen content from the normal case (0.05 times the amount of raw gas) to 4 times the amount of raw gas.

[0053] As shown in Figure 5, in normal operation (Figure 1), recycled hydrogen is hydrogenated recycled hydrogen G 4a This is the amount of hydrogen required for the hydrogenation reaction (0.05 times the amount of raw material gas G1). In this case, when operating the PC screen 200 in Figure 1, the "Dispatch" button is operated on the panel for product hydrogen delivery 200A. In this case, the panel for standby operation 200B is set to "OFF".

[0054] In Figures 1 to 3, for shut-off valves 43, 44, and 50, white indicates "open" and black indicates "closed". During normal operation, as shown in Figure 1, when "Dispatch" is selected for product hydrogen delivery on the PC screen 200, the product hydrogen gas delivery valve 43 is set to "Open".

[0055] To switch from normal operation to idle operation, standby operation must be set to "ON" on PC screen 200. This operation stops the supply of product hydrogen, in which case the product hydrogen gas supply valve 43 is "closed" and the product hydrogen emission shut-off valve 50 is "open". Then, the opening degree of the recycled hydrogen flow control valve 49 is gradually increased.

[0056] After the recycled hydrogen flow rate meter 48 confirms that the predetermined flow rate has been reached, the product hydrogen emission shutoff valve 50 is closed and the fuel hydrogen gas shutoff valve 44 is opened. At this point, hydrogen emission is zero.

[0057] In other words, during idle operation (Figure 2), recycled hydrogen is used as recycled hydrogen G for idling. 4b Therefore, the amount of hydrogen required for the hydrogenation reaction in normal operation (Figure 1) is gradually increased from 0.05 times the amount of raw material gas G1 to a specified amount (in this example, for example, 4 times). At this time, in the operation of the PC screen 200 in Figure 2, the "Stop" button is operated on the panel of product hydrogen delivery 200A. In this case, the panel of standby operation 200B is set to "ON".

[0058] Next, during idle operation (when the amount of recycled hydrogen has been increased (Figure 3), recycled hydrogen is used for idling recycled hydrogen G 4b The specified amount (in this example, for example, four times the amount) is maintained. In this case, when operating the PC screen 200 in Figure 3, the "Stop" button is pressed on the panel for product hydrogen delivery 200A. In this case, the panel for standby operation 200B is set to "ON".

[0059] Thus, during idle operation, the off-gas line L supplies off-gas G5 from the hydrogen purification unit 40 as fuel F for the burner 22 of the reformer 20. 12 Using this off-gas line L 12 A portion of purified gas G4 (off-gas hydrogen G 4c ) Excess hydrogen introduction line L 13It is supplied by this and used as fuel F for the burner 22. This makes it possible to stop the discharge of product hydrogen to the outside (air supply: none).

[0060] Figure 5 shows the relationship of the increase in recycled hydrogen between "Normal operation" shown in Figure 1, "Idle operation (increasing recycled hydrogen "less than 30% load")" shown in Figure 2; increasing recycled hydrogen" shown in Figure 3, and "Idle operation (increasing recycled hydrogen "less than 30% load"); increased recycled hydrogen completed / excess hydrogen discharged" shown in Figure 3.

[0061] In Figure 5, during normal operation, the amount of hydrogen for the hydrogenation reaction is set to 0.05 times the raw material flow rate at rated load, and there is no fluctuation in the hydrogen output. During low-load idle operation, as shown in Figure 2, recycled hydrogen G for idle is used. 4b The flow rate is gradually increased. Then, as shown in Figure 3, after the increase in recycled hydrogen is complete, the increased flow rate is maintained until the idle operation ends, and recycled hydrogen G for idle operation is used. 4b The flow rate is kept constant.

[0062] As explained above, according to the present invention, the amount of hydrogen produced is, for example, 800 Nm³. 3 When idle operation is performed on a hydrogen production unit with a capacity of / h, the amount of recycled hydrogen introduced is 7.5 times that of normal operation, and the raw material flow rate is 100 Nm³ at a 30% load. 3 While the torque is around / h, it is 30-40Nm during idle operation. 3 This means the reduction can be reduced to approximately / h.

[0063] In this way, even when operating the hydrogen production system at a lower load (less than 30%), it is possible to achieve operation without releasing hydrogen outside the system, as in conventional methods. In other words, there is an operation method called "hydrogen circulation operation" which is implemented as a standby operation that does not release hydrogen, in which hydrogen and steam are circulated in the system up to the PSA unit to maintain the temperature of the equipment. However, since this operation method does not include a hydrogen generation process, the amount of hydrogen generated is zero, and returning to normal operation requires a startup process such as reintroducing raw materials and restarting the PSA unit, which takes about 2 to 3 hours.

[0064] In contrast, in this invention, while hydrogen is produced, the excess hydrogen is supplied as fuel to the burner 22 of the reformer 20, so as in the conventional method, only a portion of the raw material gas G1 is used as fuel gas G 1a This allows for a reduction in the amount of hydrogen supplied. Furthermore, because hydrogen production is not stopped as in conventional methods, but rather kept idle, startup is also faster. For example, starting up a hydrogen production system from a completely stopped state takes about 4 to 6 hours, whereas, as in the present invention, restarting from idle operation can shorten the startup time to, for example, about 1.5 hours. [Industrial applicability]

[0065] This invention is applicable to hydrogen production apparatuses and hydrogen production methods in general, enabling operation of the hydrogen production apparatus at a lower load and operation without discharging product hydrogen outside the system. [Explanation of symbols]

[0066] 10 Compressor 13. Raw material preheater 14 Desulfurizer 15 Raw material heater 22 burners 30 Transformers 40 PSA units G1 raw material gas G2 reformed gas G3 modified gas G4 purified gas G5 Off-Gas

Claims

1. A raw material introduction line for introducing raw material gas, A desulfurizer is provided in the raw material introduction line for desulfurizing the sulfur content in the raw material gas, A reformer that reforms the raw material gas after desulfurization, A transformer that transforms the reformed gas after it has been reformed in the aforementioned reformer, A hydrogen purification apparatus for purifying the transformed gas after transformation in the aforementioned transformer, A hydrogen production apparatus comprising a recycling hydrogen line that recycles a portion of the purified hydrogen gas from the hydrogen purification apparatus to the raw material introduction line on the inlet side of the compressor, During normal operation of hydrogen production, the amount of purified hydrogen gas delivered from the recycling hydrogen line is equal to the amount of hydrogen needed for the hydrogenation reaction in the desulfurizer, A hydrogen production apparatus characterized in that, during low-load idle operation, the amount of purified hydrogen gas delivered by the recycling hydrogen line is 4 to 10 times the amount of hydrogen used for the hydrogenation reaction in the desulfurizer.

2. The above-mentioned normal operation is a load operation of 30-100%, The hydrogen production apparatus according to claim 1, characterized in that the idle operation is a low-load operation of less than 30%.

3. The hydrogen production apparatus according to claim 1 or 2, characterized in that, during the idle operation, the heating temperature of the reformer is set to 600°C or higher and 850°C or lower.

4. The hydrogen production apparatus according to claim 1 or 2, characterized in that, during the idle operation, the amount of recycled hydrogen gas to be recycled for hydrogenation is gradually increased to a desired specified value.

5. In the idle operation described above, an off-gas line is provided to supply off-gas from the refining apparatus as fuel for the burner of the reforming apparatus. The hydrogen production apparatus according to claim 1 or 2, characterized in that a portion of the purified gas is supplied to the off-gas line via a surplus hydrogen introduction line and used as fuel for the burner.

6. A raw material introduction line for introducing raw material gas, A desulfurizer is provided in the raw material introduction line for desulfurizing the sulfur content in the raw material gas, A reformer that reforms the raw material gas after desulfurization, A transformer that transforms the reformed gas after it has been reformed in the aforementioned reformer, A hydrogen purification apparatus for purifying the transformed gas after transformation in the aforementioned transformer, A hydrogen recycling line that recycles a portion of the purified hydrogen gas from the hydrogen purification apparatus to the raw material introduction line on the inlet side of the compressor, Using a hydrogen production apparatus equipped with, During normal operation of hydrogen production, the amount of purified hydrogen gas recycled in the recycling hydrogen line is supplied to provide the hydrogen necessary for the hydrogenation reaction in the desulfurizer, A hydrogen production method characterized in that, during low-load idle operation, the amount of purified hydrogen gas to be recycled in the recycling hydrogen line is supplied to be 4 to 10 times the amount of hydrogen used for the hydrogenation reaction in the desulfurizer.

7. The above-mentioned normal operation is a load operation of 30-100%, The hydrogen production method according to claim 6, characterized in that the idle operation is a low-load operation of less than 30%.

8. The hydrogen production method according to claim 6 or 7, characterized in that, during the idle operation, the heating temperature of the reformer is set to 600°C or higher and 850°C or lower.

9. The hydrogen production method according to claim 6 or 7, characterized in that, during the idle operation, the amount of purified hydrogen gas to be recycled is gradually increased to a desired specified value.

10. In the idle operation described above, an off-gas line is used to supply off-gas from the refining apparatus as fuel for the burner of the reforming apparatus. The hydrogen production method according to claim 6 or 7, characterized in that a portion of the purified gas is supplied to the off-gas line through a surplus hydrogen introduction line and used as fuel for the burner.

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