Hydrogen production apparatus and method for operating a hydrogen production apparatus

Abstract

To provide a hydrogen production device for reducing an amount of fuel consumption in an operation state other than normal operation, and an operation method of the hydrogen production device.SOLUTION: A hydrogen production device 100 comprises: a compressor 105; a desulfurizer 110; a reformer 120; a transformer 130; a liquid gas separator 140; and a hydrogen purification unit 150, in which, there is also provided hydrogen circulation operation piping L51 for circulating hydrogen to an inlet of the compressor 105, from piping L4 coupling the liquid gas separator 140 and the hydrogen purification unit 150, and in hydrogen circulation operation in standby operation time, the hydrogen is circulated through the hydrogen circulation operation piping L51 while supplying pure water PW or steam.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a hydrogen production apparatus and a method for operating the hydrogen production apparatus.

Background Art

[0002] Conventionally, a hydrogen production apparatus 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 (see, for example, Patent Documents 1 and 2). Since hydrogen is generally consumed continuously in a hydrogen production apparatus for industrial use, it is often operated continuously day and night. Also, in the case of continuous day and night operation, the efficiency can be increased, and as a result, the unit price of hydrogen can be reduced.

[0003] On the other hand, a hydrogen production apparatus used in a hydrogen station for filling a fuel cell vehicle with hydrogen, etc., is assumed not to operate at night, especially during the popularization period of hydrogen stations. Therefore, it can be said that it is more economical to stop the hydrogen production apparatus outside business hours.

[0004] Therefore, in the hydrogen production apparatuses disclosed in Patent Documents 1 and 2, only the hydrogen or hydrogen-rich gas that has already been produced is circulated during standby operation when hydrogen is not being produced. In other hydrogen production apparatuses, the supply amount of the raw material gas is reduced to the minimum (idling operation), and the minimum amount of hydrogen produced is self-consumed by circulating it or using it as fuel for the combustion burner of the reformer.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, as in the hydrogen production apparatuses disclosed in Patent Documents 1 and 2, there is a problem that if only hydrogen or hydrogen-rich gas is circulated during standby operation, the catalyst of the hydrogen production apparatus will be over-reduced. Further, when returning from standby operation to normal operation, there is a problem that it takes time until the return. Furthermore, when hydrogen is self-consumed during idling operation, although the transition to normal operation and the return from normal operation can be performed quickly, there is a problem that a relatively large amount of fuel is consumed even during idling operation.

[0007] Therefore, the present invention has been made in view of the above problems, and an object thereof is to provide a hydrogen production apparatus and an operation method of a hydrogen production apparatus capable of reducing the fuel consumption amount during standby operation.

Means for Solving the Problems

[0008] A hydrogen production apparatus according to one aspect of the present invention is a hydrogen production apparatus including a compressor, a desulfurizer, a reformer, a converter, a gas-liquid separator, and a hydrogen purification apparatus, further including a hydrogen circulation operation pipe for circulating hydrogen from a pipe connecting between the gas-liquid separator and the hydrogen purification apparatus to an inlet side of the compressor, and circulating the hydrogen through the hydrogen circulation operation pipe while supplying pure water or steam during the hydrogen circulation operation in standby operation.

[0009] An operation method of a hydrogen production apparatus according to another aspect of the present invention is an operation method of a hydrogen production apparatus including a compressor, a desulfurizer, a reformer, a converter, a gas-liquid separator, and a hydrogen purification apparatus, further including a hydrogen circulation operation pipe for circulating hydrogen from a pipe connecting between the gas-liquid separator and the hydrogen purification apparatus to an inlet side of the compressor, and circulating the hydrogen through the hydrogen circulation operation pipe while supplying pure water or steam during the hydrogen circulation operation in standby operation.

Effects of the Invention

[0010] According to the present invention, it is possible to provide a hydrogen production apparatus and a method for operating the hydrogen production apparatus that reduce fuel consumption in an operating state other than normal operation.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

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Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the embodiments of this specification, the same members are denoted by the same reference numerals throughout.

[0013] First, the hydrogen production apparatus 100 will be described. FIG. 1 is a system diagram showing an outline of the hydrogen production apparatus 100 according to an embodiment of the present invention.

[0014] The hydrogen production apparatus 100 includes a desulfurizer 110, a reformer 120, a converter 130, a gas-liquid separator 140, and a hydrogen purification apparatus 150 as main apparatuses. In FIG. 1, reference numerals G1, G2, G3, G4, G5, and OG denote a raw material gas, a reformed gas, an exhaust gas, a converted gas, a purified gas, and an off-gas, respectively.

[0015] The desulfurizer 110 removes sulfur components contained as odorants in hydrocarbon fuels such as city gas and LPG. Since the sulfur components become catalyst poisons for reforming catalysts and conversion catalysts used in the subsequent process, the sulfur components contained in the raw material gas G1 are removed in advance by this desulfurizer 110.

[0016] Specifically, the desulfurizer 110 is composed of a flow path filled with a hydrodesulfurization catalyst composed of, for example, a hydrogenation catalyst such as a Co-Mo system or a Ni-Mo system and a ZnO-based desulfurization catalyst that adsorbs hydrogen sulfide. By supplying the raw material gas G1 and hydrogen to this desulfurizer 110, a hydrogenation (hereinafter referred to as "hydrogenation") reaction is carried out to convert the sulfur component into hydrogen sulfide, take in the hydrogen sulfide into zinc oxide to form zinc sulfide, and remove the sulfur component. The reaction formulas for this hydrodesulfurization are as shown in the following reaction formulas (1) and (2). CmHnS + H2 → CmHn + H2S ···(1) H2S + ZnO → H2O + ZnS ···(2)

[0017] Note that the desulfurizer 110 may perform desulfurization using an adsorbent for sulfur compounds that reacts at normal temperature or high temperature instead of the hydrogenation reaction as in this embodiment. Also, in the case of the raw material gas G1 that does not contain sulfur components, it is not necessary to provide the desulfurizer 110.

[0018] The reformer 120 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 generate a reformed gas G2 such as hydrogen and carbon monoxide. The reaction formulas for this steam reforming are as shown in the following reaction formulas (3) and (4). CmHn + mH2O → mCO + (m + n / 2)H2 ···(3) CO + 3H2 ←→ CH4 + H2O ···(4)

[0019] These steam reforming reactions are endothermic reactions. The steam / carbon ratio for mixing is preferably about 3 times so as not to deposit carbon on the surface of the catalyst.

[0020] This reformer 120 is provided with a catalyst reaction tube filled with a catalyst for steam reforming. A plurality of these catalyst reaction tubes are arranged and housed inside a reactor (not shown).

[0021] Then, the reformer 120 uses a part of the raw material gas G1 and the off-gas OG from the hydrogen purification device 150 described later as fuel gas, and supplies it together with air from the air blower 125 to the combustion burner 126 to heat the catalyst reaction tubes in the reactor.

[0022] The converter 130 reacts carbon monoxide in the reformed gas G2 sent from the reformer 120 with steam to produce even more hydrogen H2. The reaction formula for this CO conversion is as follows in Reaction Formula (5) below. CO + H2O ←→ CO2 + H2 ··· (5)

[0023] In this converter 130, for example, a catalyst such as an Fe-Cr based, Cu-Zn based, or Pt based catalyst is used according to a reaction temperature of 200°C to 500°C.

[0024] The gas-liquid separator 140 separates and removes condensed water from the reformed gas G2 as drain water.

[0025] The hydrogen purification device 150 uses an adsorbent to adsorb gases such as carbon monoxide, carbon dioxide, methane, and steam other than hydrogen H2, separates only hydrogen H2 from the reformed gas G4, and can finally increase the hydrogen concentration to about 99.999%. The off-gas OG generated in this hydrogen purification device 150 may be used as fuel for heating the reformer 120.

[0026] Then, in addition to the main devices described above, the hydrogen production device 100 is provided with, for example, a compressor 105 that compresses the raw material gas G1 and supplies it to the desulfurizer 110.

[0027] Furthermore, the hydrogen production device 100 is provided with the following components. (1) A raw material regulating valve V1 is provided in the raw material pipe L1 connecting the raw material supply source 160 and the compressor 105. (2) The compressor 105 and the desulfurizer 110 are connected by a second pipe L2, and the desulfurizer 110 and the reformer 120 are connected by a third pipe L3. A gas discharge pipe L7 for discharging the exhaust gas G3 is connected to the reformer 120. (3) An on-off valve V4 is provided in the extraction pipe L4 connecting the gas-liquid separator 140 and the hydrogen purification device 150. (4) On the outlet side of the hydrogen purification device 150, a hydrogen extraction pipe L5 for extracting the purified gas (hydrogen H2) G5 is provided. A hydrogen regulating valve V5 is provided in this hydrogen extraction pipe L5. (5) A fuel pipe L 11 is provided to supply the raw material gas G1 as fuel gas from the raw material supply source 160 to the combustion burner 126, and a fuel regulating valve V 11 is provided in this fuel pipe L 11 . (6) An off-gas pipe L 12 is provided to supply the off-gas OG from the hydrogen purification device 150 to the combustion burner 126, and an off-gas holder 190 and an off-gas regulating valve V 12 are provided in this off-gas pipe L 12 . (7) A pure water pipe L 31 is connected from the pure water supply source 170 to the third pipe L3, and a pure water regulating valve V 31 is provided in this pure water pipe L 31 . A heat exchanger (not shown) is provided in this pure water pipe L 31 to convert the supplied pure water into steam. Alternatively, steam may be directly supplied separately. (8) A vent pipe L 42 for discharging gas is provided in the extraction pipe L4, and a vent regulating valve V 42 for releasing the pressure in the extraction pipe L4 is provided. (9) A hydrogen circulation operation pipe L 51 is provided to loop from the extraction pipe L4 to the raw material pipe L1, and a hydrogen circulation operation valve V 51It is provided with a circulation on-off valve V 51 . (10) In the raw material pipe L1, a hydrogenation pipe L for adding hydrogen H2 from a hydrogen supply source 180 is provided 61 , and this hydrogenation pipe L 61 is provided with a hydrogenation control valve V 61 . (11) A pipe L 61 is connected to the hydrogen extraction pipe L5 and the hydrogenation pipe L 62 , and a part of the purified hydrogen is supplied to the hydrogenation pipe L 61 . The pipe L 62 is provided with a hydrogenation on-off valve V 62 . (12) Between the connection part of the pipe L 61 connected to the hydrogenation pipe L and the hydrogen supply source 180, a hydrogen introduction on-off valve V 62 is provided 63 . In addition to the above, for example, pipes are also connected between the reformer 120 and the converter 130, etc. Also, although not shown, bypass pipes and on-off valves for maintenance of various devices are appropriately provided

[0028] With such a configuration, the hydrogen production apparatus 100 sends the raw material gas G1 to the desulfurizer 110 via the compressor 105, removes the sulfur component, and then supplies the desulfurized raw material gas G1 to the reformer 120 together with pure water PW (steam) to generate a reformed gas G2 containing hydrogen H2. The reformed gas G2 is sent to the converter 130, and further, hydrogen H2 is generated to obtain a converted gas G4. The liquid is separated from the converted gas G4 by the gas-liquid separator 140, and components other than hydrogen H2 are adsorbed as off-gas OG by the hydrogen purification apparatus 150 to produce a large amount of hydrogen H2 as the purified gas G5

[0029] (Operating Procedure A) FIG. 2 is a system diagram showing the operating procedure A in the operating method of the hydrogen production apparatus 100 As shown in FIG. 2, this operating procedure A shows the state during normal operation. In the operating procedure A, a part of the hydrogen H2 in the purified gas G5 from the hydrogen purification apparatus 150 is for the hydrogenation reaction of the desulfurizer 110, and is supplied to the hydrogenation pipe L 61It is circulated through etc. In the on-off valve or regulating valve Vn in FIGS. 2 to 6, the white part indicates the open state, and the filled part indicates the closed state. In the compressor 105 and the hydrogen purification device 150, the white part indicates the on state, and the filled part indicates the off state.

[0030] (Operating Instructions B) FIG. 3 is a system diagram showing the operating instructions B in the operating method of the hydrogen production device 100. As shown in FIG. 3, this operating instruction B indicates a state of shifting from the hydrogen production operation to the standby operation. The raw material regulating valve V1 is closed to cut off the supply of the raw material gas G1 from the raw material supply source 160, and the extraction regulating valve V5 is closed, and the production of hydrogen H2 by the hydrogen production device 100 is stopped.

[0031] At this time, the compressor 105 and the hydrogen purification device 150 also stop. When stopping the compressor 105, the hydrogenation regulating valve V 61 is closed, and when stopping the hydrogen purification device 150, the on-off valve V4, the off-gas regulating valve V 12 and the circulation on-off valve V 62 are closed.

[0032] Then, as shown in FIG. 3, while the supply of pure water PW from the pure water supply source 170 continues, the supply amount of pure water PW is reduced by adjusting the flow rate of the pure water regulating valve V 31 . Also, the supply of the raw material gas G1 through the fuel pipe L 11 from the raw material supply source 160 continues, and the combustion of the combustion burner 126 continues. Then, the opening degree of the fuel regulating valve V 11 is adjusted so as to maintain the reforming temperature of the reformer 120 at a predetermined temperature (for example, 800°C to 900°C). Further, from the vent regulating valve V 42 , the reforming process gas in the reforming system pipes of the raw material pipes L1 to the extraction pipes L4 is exhausted to the outside as the vent gas G6.

[0033] That is, in this operation procedure B, while maintaining the heating of the reformer 120, the gas (reforming process gas) remaining in the raw material pipes L1 to extraction pipe L4 from the raw material regulating valve V1 to the extraction regulating valve V4 is forcibly released through the vent regulating valve V 42 and exhausted as vent gas G6. In the hydrogen purification device 150, since the adsorption tower is maintained at the pressure during normal operation and the off-gas OG other than hydrogen H2 remains adsorbed, the pressure is reduced.

[0034] (Operation Procedure C) Figure 4 is a system diagram showing the operation procedure C in the operation method of the hydrogen production device 100. As shown in Figure 4, this operation procedure C shows the state during the transition to the standby operation (hydrogen circulation operation). While controlling the temperature of the reformer 120, the reforming system pipes of the raw material pipes L1 to extraction pipe L4 are filled (replaced) with purge hydrogen H2. This purge hydrogen is supplied from the hydrogen supply source 180. Note that this hydrogen supply source 180 may be a hydrogen cylinder, or a part of the hydrogen H2 in the purified gas G5 may be introduced.

[0035] (Operation Procedure D) Figure 5 is a system diagram showing the operation procedure D in the operation method of the hydrogen production device 100. As shown in Figure 5, this operation procedure D shows the state during the standby operation (hydrogen circulation operation). While maintaining a predetermined heating temperature of the reformer 120 and continuing the supply of pure water PW, the purged hydrogen H2 is circulated through the hydrogen circulation operation pipe L 51 to perform a hydrogen circulation operation. In this operation procedure D, the heating temperature of the reformer 120 is reduced to a temperature slightly lower (for example, 50°C to 150°C) than the heating temperature during normal operation, and the operation is performed at a heating temperature of, for example, 600°C to 850°C. Thereby, the fuel consumption of the raw material gas G1 can be reduced.

[0036] After the supply of the raw material gas G1 is stopped and the replacement with hydrogen H2 in the operation procedure C shown in Figure 4 is completed, the hydrogenation regulating valve V 61 and the hydrogen on-off valve V 63Close it, stop the supply of hydrogen H2 from the raw material pipes L1 to the extraction pipe L4 to the reforming pipes, and the hydrogen circulation operation pipe L 51 Open the circulation operation on-off valve V 51 of, and turn on the compressor 105 to circulate the purged hydrogen H2 through the reforming pipes and the hydrogen circulation operation pipe L 51 in a hydrogen circulation operation while continuing to supply pure water PW.

[0037] In FIG. 5, when the detected value of the pressure at the outlet of the gas-liquid separator 140 by the pressure detector P, that is, the pressure of the extraction pipe L4, drops to a predetermined pressure (for example, 0.1 MPaG), as in the operation procedure C shown in FIG. 4, the hydrogenation adjustment valve V 61 and the hydrogen on-off valve V 63 are opened, and hydrogen H2 from the hydrogen supply source 180 is introduced from the inlet side of the compressor 105 into the reforming pipes of the raw material pipes L1 to the extraction pipe L4 to return to the predetermined pressure and maintain the predetermined pressure (for example, 0.15 MPaG) during the purge operation.

[0038] (Operation Procedure E) This operation procedure E shows the state during the transition from the standby operation to the return to the normal operation. In FIG. 5, the supply amount of pure water PW is increased by adjusting the opening degree of the pure water adjustment valve V 31 and, in order to return the reformer 120 to the predetermined heating temperature (for example, from 650 °C to 900 °C) of the normal operation, the raw material gas G1 from the raw material supply source 160 is supplied to the combustion burner 126 to start the temperature rise in the reformer 120.

[0039] (Operation Procedure F) FIG. 6 is a system diagram showing the operation procedure F in the operation method of the hydrogen production apparatus 100. As shown in FIG. 6, in this operation procedure F, when the catalytic reaction temperature of the reformer 120, that is, the detected value of the temperature detector T of the reactor of the reformer 120 reaches a predetermined temperature (for example, from 800 °C to 900 °C), the hydrogen circulation operation on-off valve V 51Close it to stop the hydrogen circulation, open the raw material regulating valve V1, and introduce the raw material gas G1. Finally, operate the hydrogen purification device 150 to start the production of hydrogen H2 and return to the operating state of the operation procedure A shown in FIG. 2.

[0040] As described above, the hydrogen production device 100 according to the embodiment of the present invention is a hydrogen production device 100 including a compressor 105, a desulfurizer 110, a reformer 120, a converter 130, a gas-liquid separator 140, and a hydrogen purification device 150. A hydrogen circulation operation pipe L that loops from the extraction pipe L4 connecting between the gas-liquid separator 140 and the hydrogen purification device 150 to the inlet side of the compressor 105 51 and further includes, in the hydrogen circulation operation during standby operation, while supplying pure water PW or steam, the hydrogen circulation operation pipe L 51 circulates hydrogen H2 through it.

[0041] Thereby, it is possible to significantly reduce the fuel consumption of the raw material gas G1 in an operating state other than normal operation, for example, during standby operation. The consumption of the raw material gas G1 (for example, city gas) during this standby operation is 7.5, which is 1 / 10 or less when the rated operation of the hydrogen production device 100 is set to 100, and can be made very small, and the effect of reducing the usage amount of the raw material gas G1 can be exerted. During idle operation with a low hydrogen production amount, it was about 18 to 20 with respect to 100 during rated operation.

[0042] In addition, in the hydrogen production device 100 of the embodiment, the start-up time from start-up to normal operation was about 4 hours, whereas the return time from standby operation to normal operation was about 1 hour, and the return time could be shortened. Furthermore, since steam is also supplied in addition to hydrogen H2, the respective catalysts of the reformer 120 and the converter 130 are not over-reduced.

[0043] In the embodiment, in the hydrogen circulation operation during standby operation, the heating temperature of the reformer 120 may be, for example, 600°C or higher and 850°C or lower, and ideally it should be maintained at the same temperature as during normal operation (hydrogen production). This can keep the temperature of the reformer 120 high while suppressing the consumption of the raw material gas G1. Therefore, the heat loads of various devices such as the components 110 to 140 constituting the hydrogen production apparatus 100 and heat exchangers (not shown) can be reduced, and the service life of the apparatus, devices, etc. can be extended. However, since a lower heating temperature of the reformer 120 can suppress the fuel consumption, the heating temperature (holding temperature) during standby operation should be appropriately set in consideration of the frequency and duration of standby operation.

[0044] Furthermore, by supplying the hydrogen H2 and steam heated by the reformer 120, the converter 130 can also be indirectly heated. When a separate heater is installed, the temperature may be maintained at about 200°C to 350°C by heating with the heater.

[0045] In this embodiment, in the hydrogen circulation operation during standby operation, the pressure of the hydrogen circulation operation pipe L 51 may be within the range from atmospheric pressure to the normal operation pressure, for example, 0.3 MPaG or lower, more preferably 0.2 MPaG. That is, since the hydrogen purification apparatus 150 is not used during standby operation, the pressure of the circulation system pipe can be reduced. Therefore, in the hydrogen circulation operation during standby operation, it is preferable to make the pressure lower, as this can reduce the power of the compressor 105 used for hydrogen circulation.

[0046] As described above, the preferred embodiments of the present invention have been described in detail. However, the present invention is not limited to the above-described embodiments, and various modifications and changes are possible within the scope of the gist of the present invention described in the claims.

Explanation of Reference Numerals

[0047] 100 Hydrogen production apparatus 105 Compressor 110 Desulfurizer 120 Reformer 125 Air Blower 126 Combustion Burner 130 Transformer 140 Gas-Liquid Separator 150 Hydrogen Purification Device 160 Raw Material Source 170 Pure Water Source 180 Hydrogen Source 190 Off-Gas Holder Vn On-Off Valve or Control Valve Ln Pipe G1 Raw Material Gas G2 Reformed Gas G3 Exhaust Gas G4 Shift Gas G5 Purified Gas G6 Vent Gas OG Off-Gas PW Pure Water P Pressure Detector T Temperature Detector

Claims

1. A hydrogen production apparatus comprising a compressor, a desulfurizer, a reformer, a transformer, a gas-liquid separator, and a hydrogen purification apparatus, further comprising a hydrogen circulation operation pipe for circulating hydrogen from a pipe connecting the gas-liquid separator and the hydrogen purification apparatus to the inlet side of the compressor, In the hydrogen circulation operation during standby operation, the hydrogen is circulated through the hydrogen circulation operation pipe while supplying pure water or steam. A hydrogen production apparatus characterized by the above.

2. In the hydrogen circulation operation during standby operation, the heating temperature of the reformer is set to 600°C or higher and 850°C or lower. The hydrogen production apparatus according to claim 1, characterized by the above.

3. In the hydrogen circulation operation during standby operation, the pressure of the hydrogen circulation operation pipe is set to 0.3 MPaG or lower. The hydrogen production apparatus according to claim 1 or 2, characterized by the above.

4. The hydrogen production apparatus further comprises a pure water supply source for supplying pure water to a pipe connecting the desulfurizer and the reformer, and a pure water regulating valve for regulating the supply amount of the pure water. The hydrogen production apparatus according to any one of claims 1 to 3, characterized by the above.

5. An operation method of a hydrogen production apparatus comprising a compressor, a desulfurizer, a reformer, a transformer, a gas-liquid separator, and a hydrogen purification apparatus, further comprising a hydrogen circulation operation pipe for circulating hydrogen from a pipe connecting the gas-liquid separator and the hydrogen purification apparatus to the inlet side of the compressor, In the hydrogen circulation operation during standby operation, the hydrogen is circulated through the hydrogen circulation operation pipe while supplying pure water or steam. An operation method of a hydrogen production apparatus characterized by the above.

6. In the hydrogen circulation operation during standby operation, the heating temperature of the reformer is set to 600°C or higher and 850°C or lower. The operation method of the hydrogen production apparatus according to claim 5, characterized in that...

7. In the hydrogen circulation operation during standby operation, the pressure of the hydrogen circulation operation pipe is set to 0.3 MPaG or less. The operation method of the hydrogen production apparatus according to claim 5 or 6, characterized in that...

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