JP5823341B2 - Self-heating reformer and steam reforming method using the same - Google Patents

Description

  The present invention relates to an autothermal reformer and a steam reforming method using the same.

The steam reforming method is a typical method for producing hydrogen. In this steam reforming method, hydrogen is generated by reforming a mixed gas of a hydrocarbon-containing gas such as natural gas, naphtha, kerosene, and methanol and steam in the presence of a catalyst. Specifically, hydrogen is generated by continuously generating a reforming reaction represented by the following formula (1) and a modification reaction represented by the following formula (2).
C _n H _m + nH ₂ O → nCO + (m / 2 + n) H ₂ (1)
CO + H ₂ O → CO ₂ + H ₂ (2)

  The reforming reaction is an endothermic reaction. Thus, there is a method of supplying the heat necessary for the reforming reaction from the outside. In this case, it takes a long time until the reformer becomes stable and produces hydrogen. Such an inconvenience appears remarkably in a hydrogen station operated by DSS (Daily Start and Stop). In addition, since an apparatus for supplying an external heat source is required, it is difficult to make the entire apparatus compact.

  Therefore, as a heat source necessary for the reforming reaction, a self-heat reformer using the combustion heat of the hydrocarbon is known. This self-heating reformer includes an oxidation reforming section including an oxidation catalyst together with a reforming catalyst. When hydrogen is produced, a small amount of oxygen-containing gas is added to the oxidation reforming section in addition to the mixed gas. Supply. By doing so, a part of the hydrocarbon is oxidized (combusted) in the oxidation reforming section due to the presence of the oxidation catalyst, and the reforming reaction can be advanced using this combustion heat. This self-heating reformer has little heat loss and can shorten the time required for temperature increase. Furthermore, a technique has been proposed in which a preliminary reforming chamber is provided on the upstream side of the main reformate, and the temperature rise time is further shortened by circulating high-temperature gas to the oxidation reforming section (Japanese Patent Application Laid-Open No. 2007-145637). No. publication).

  In the self-heating reformer, the oxygen-containing gas is supplied through a pipe having a supply port provided in the oxidation reforming section. However, in this case, a combustion (oxidation) reaction tends to occur in the vicinity of the oxygen-containing gas supply port in the oxidation reforming section, and the amount of heat generation decreases as the distance from the oxygen-containing gas supply port increases. Therefore, when the oxygen-containing gas is supplied near the inlet (upstream) of the oxidation reforming unit with respect to the flow of the mixed gas, the temperature near the outlet (downstream) of the oxidation reforming unit becomes lower than the temperature near the inlet. . Since the reforming reaction is an endothermic reaction and a reversible reaction, the reverse reaction of the reforming reaction occurs near the outlet, and the hydrogen conversion rate decreases. Therefore, it is conceivable to increase the supply flow rate of the oxygen-containing gas in order to increase the temperature near the outlet. However, even in this case, oxygen is consumed only in the vicinity of the inlet of the oxidation reforming section. As a result, the temperature in the vicinity of the inlet is excessively increased, and the catalyst and the reformer material are deteriorated. It is also conceivable to install an oxygen-containing gas supply port near the outlet in order to increase the temperature near the outlet without increasing the temperature near the inlet. However, in this case, the temperature in the vicinity of the inlet of the oxidation reforming section is lowered and the conversion efficiency is lowered. In addition, all the oxygen is not consumed and easily flows out of the oxidation reforming section. In the autothermal reformer, a shift reaction unit for performing the modification reaction is provided on the downstream side of the oxidation reforming unit. Therefore, when oxygen flows into the shift reaction unit, There is also a disadvantage that the activity of the shift catalyst is lowered.

JP 2007-145637 A

  The present invention has been made on the basis of the above-described circumstances, and is capable of generating hydrogen at a high conversion rate, and can suppress the decrease in the activity of the shift catalyst in the shift reaction section. It is an object of the present invention to provide a quality device and a steam reforming method using the same.

The invention made to solve the above problems is
An oxidation reforming section including an oxidation and reforming catalyst,
A shift reaction unit including a shift catalyst located downstream of the oxidation reforming unit, and an oxygen supply means for supplying an oxygen-containing gas to the oxidation reforming unit,
A self-thermal reformer that performs a steam reforming reaction of hydrocarbons by circulating a mixed gas of hydrocarbon and steam through the oxidation reforming unit and the shift reaction unit,
The oxygen supply means has a plurality of oxygen-containing gas supply ports arranged at at least two locations on the upstream and downstream sides in the oxidation reforming section.

  The self-heating reformer has oxygen-containing gas supply ports provided at at least two locations on the upstream side and the downstream side in the oxidation reforming section, and supplies oxygen-containing gas from the downstream supply port. Thus, the combustion amount of hydrocarbons on the downstream side (outlet side) can be increased. By doing in this way, the fall of the temperature in the downstream (exit side) of an oxidation reforming part, ie, generation | occurrence | production of the reverse reaction of a reforming reaction, can be suppressed, and a hydrogen conversion rate can be raised. In addition, according to the self-thermal reformer, the amount of oxygen flowing out from the oxidation reforming section is reduced by adjusting the position of the downstream supply port and the supply amount of the oxygen-containing gas from the supply port. As a result, it is possible to suppress a decrease in the activity of the shift catalyst in the shift reaction section.

  The oxygen supply means may include a control means for controlling each oxygen-containing gas supply amount from the plurality of oxygen-containing gas supply ports. By having such a control means, adjustment to a suitable temperature in the oxidation reforming unit and reduction of the amount of oxygen flowing out from the oxidation reforming unit can be performed efficiently and easily.

  The angle formed by the oxygen-containing gas ejection direction and the mixed gas flow direction at the oxygen-containing gas supply port may be 90 ° or more and 150 ° or less. Moreover, it is good to make the jet direction of this oxygen containing gas radial with respect to the distribution direction of mixed gas. By doing so, the oxygen-containing gas can be supplied widely and uniformly into the oxidation reforming section, and the temperature of the entire oxidation reforming section can be raised, so that the conversion efficiency can be increased. In addition, since oxygen is efficiently consumed, the amount of oxygen flowing out from the oxidation reforming unit can be reduced.

The steam reforming method of the present invention comprises:
Using the autothermal reformer,
A step of circulating a mixed gas of hydrocarbon and water vapor through the oxidation reforming unit and the shift reaction unit, and a step of supplying an oxygen-containing gas to the oxidation reforming unit by the oxygen supply means.

  Since the autothermal reforming method is carried out using the autothermal reformer of the present invention, hydrogen can be generated at a high conversion rate, and the decrease in the activity of the shift catalyst in the shift reaction section can be suppressed. Can do.

  It is preferable to use pure oxygen as the oxygen-containing gas. By using pure oxygen, the temperature can be increased efficiently and catalyst deterioration due to by-products can be suppressed.

  Here, the “oxidation and reforming catalyst” includes, in addition to a mixture of an oxidation catalyst and a reforming catalyst, a catalyst having a catalytic function for an oxidation reaction and a catalytic function for a reforming reaction.

  As described above, according to the autothermal reformer and the steam reforming method of the present invention, hydrogen can be generated at a high conversion rate, and the decrease in the activity of the shift catalyst in the shift reaction section can be suppressed. Can do.

Schematic sectional view showing an embodiment of the self-heating reformer of the present invention The typical perspective view which shows the front-end | tip of piping which the self-heat type reformer of FIG. 1 has Schematic perspective view showing the tip of piping in other embodiments

  Hereinafter, embodiments of the self-heating reformer and the steam reforming method of the present invention will be described in detail with reference to the drawings as appropriate.

<Self-thermal reformer>
The self-heating reformer 1 of FIG. 1 is a hollow substantially cylindrical body having a substantially cylindrical outer wall. The autothermal reformer 1 is provided under a substantially cylindrical reaction chamber 2 disposed substantially coaxially inside, a mixed gas supply port 3 communicating with a lower portion of the outer wall, and the reaction chamber 2. 2 is mainly provided with a reformed gas discharge port 4 communicating with the lower part. In the self-heating reformer 1, the gas flowing in from the mixed gas supply port 3 rises in the outer wall, flows into the reaction chamber 2, descends in the reaction chamber 2, and is discharged from the reformed gas discharge port 4. It is comprised so that.

  The reaction chamber 2 includes an oxidation reforming unit 5 provided on the upper side and a shift reaction unit 6 provided downstream of the oxidation reforming unit 5. Further, the self-heating reformer 1 includes two pipes 7 and 8 as oxygen-containing gas supply means for supplying an oxygen-containing gas to the oxidation reforming unit 5 from the outside. Furthermore, the self-heating reformer 1 usually has heating means such as a heater for heating the outer wall of the reformer.

  The oxidation reforming section 5 is filled with an oxidation catalyst and a reforming catalyst.

  The oxidation catalyst oxidizes (combusts) hydrocarbons to obtain a temperature necessary for the steam reforming reaction. The oxidation catalyst is not particularly limited, and a known catalyst can be used. Examples thereof include platinum, palladium, rhodium, ruthenium, and compounds thereof. These can be used alone or in combination of two or more.

  The content of the oxidation catalyst relative to the total of the oxidation catalyst and the reforming catalyst is appropriately selected depending on the type of hydrocarbon used, and is, for example, 1 to 15% by mass. In addition, when using methane as a hydrocarbon, 1-5 mass% is preferable, and when using methanol, 1-3 mass% is preferable.

The reforming catalyst generates hydrogen by steam reforming a hydrocarbon. The reforming catalyst is not particularly limited, and known catalysts can be used. For example, NiO—A1 ₂ O, NiO—SiO ₂ .A1 ₂ O ₃ , NiO—WO ₂ .SiO ₂ .A1 ₂ O ₃ And nickel-based catalysts such as WO ₂ —SiO ₂ .A1 ₂ O ₃ . These can be used alone or in combination of two or more.

  The shape of the oxidation catalyst and the reforming catalyst is not particularly limited, and a pellet type or a monolith type can be used. Further, instead of mixing the oxidation catalyst and the reforming catalyst, a catalyst having both a catalytic function for the oxidation reaction and a catalytic function for the reforming reaction can be used.

  The length L (length in the flow direction of the mixed gas) of the oxidation reforming part 5 is not particularly limited, but is, for example, 50 mm or more and 300 mm or less, and preferably 100 mm or more and 200 mm or less. By making the oxidation reforming portion 5 such a size, the oxidation and reforming reaction can be performed efficiently.

  The pipe 7 has an oxygen-containing gas supply port 9 provided at the tip portion. The oxygen-containing gas supply port 9 is disposed on the upstream side (inlet side) in the oxidation reforming unit 5. The distance A from the inlet of the oxidation reforming unit 5 of the oxygen-containing gas supply port 9 is preferably 1/2 or less of the length L of the oxidation reforming unit 5 and more preferably 1/10 or more and 1/3 or less. . By disposing the upstream oxygen-containing gas supply port 9 at such a position, a combustion reaction can be performed efficiently.

  The pipe 8 also has an oxygen-containing gas supply port 10 provided at the tip portion. The oxygen-containing gas supply port 10 is disposed on the downstream side (outlet side) in the oxidation reforming unit 5. The distance B from the outlet of the oxidation reforming unit 5 of the oxygen-containing gas supply port 10 is preferably 1/8 or more and 1/2 or less of the length of the oxidation reforming unit 5, and is 1/6 or more and 1/3 or less. Is more preferable. By disposing the downstream oxygen-containing gas supply port 10 at such a position, the combustion reaction can be efficiently performed also on the outlet side while suppressing the amount of oxygen flowing out from the oxidation reforming unit 5. .

  The oxygen-containing gas supply ports 9 and 10 are formed such that the direction in which the oxygen-containing gas Y is ejected is substantially perpendicular to the flow direction (vertical direction) of the mixed gas X. Specifically, as an example of the pipe 8, as shown in FIG. 2 (a), the tip is branched in a T-shape. By doing in this way, since oxygen-containing gas can be widely supplied in the oxidation reforming part 5 and the temperature of the entire oxidation reforming part 5 can be raised, the conversion efficiency can be increased. Further, since oxygen is efficiently consumed, the amount of oxygen flowing out from the oxidation reforming unit 5 can also be reduced.

  Further, as shown in FIG. 2B, the pipe 8 'may have a structure in which the tip of the pipe 8' branches slightly upward (Y-shaped). In this way, by causing the oxygen-containing gas Y to be ejected in a direction slightly opposite to the mixed gas X, the outflow of oxygen from the oxidation reforming unit 5 can be further reduced. The angle α between the direction in which the oxygen-containing gas Y is ejected (the direction in which the tip of the pipe extends) and the flow direction of the mixed gas X is preferably 90 ° or more and 150 ° or less, more preferably more than 90 ° and 120 ° or less. .

  As described above, it is preferable that the plurality of oxygen-containing gas supply ports provided in one pipe are formed so that the jet direction Y of the oxygen-containing gas is radial with respect to the flow direction X of the mixed gas. . Here, “radial” means that angles formed by a plurality of ejection directions are substantially equal. For example, when there are two supply ports, the ejection direction is 180 ° (reverse direction). By providing a plurality of oxygen-containing gas supply ports in this manner, oxygen can be diffused more uniformly in the oxidation reforming unit 5 to cause a combustion reaction.

  The oxygen-containing gas supply ports 9 and 10 are preferably arranged so as to be movable in the flow direction (vertical direction) of the mixed gas. In this case, while checking the temperature in the oxidation reforming unit 5 in operation and the amount of oxygen flowing out, the position of the supply ports 9 and 10 (particularly the supply port 10) is moved to react in a more suitable combustion environment. Since it can be performed, conversion efficiency etc. can be raised more.

  The pipes 7 and 8 are respectively provided with mass flow controllers 11 and 12 as control means for controlling the oxygen-containing gas supply amount. The mass flow controllers 11, 12 can control the oxygen-containing gas supply amounts at the oxygen-containing gas supply ports 9, 10. By having such a control means, adjustment to a suitable temperature in the oxidation reforming unit 5 and reduction of the amount of oxygen flowing out from the oxidation reforming unit 5 can be performed efficiently and easily.

  Note that the self-thermal reformer 1 preferably includes a temperature measuring unit that measures the temperature in the oxidation reforming unit 5. Furthermore, it is preferable that the temperature measuring means is provided so as to be able to measure temperatures at at least two locations on the upstream side (inlet side) and downstream side (outlet side). By providing such temperature measuring means, it is possible to control the supply amount of oxygen while grasping the temperature, and to move the position of the oxygen-containing gas supply port. The temperature measuring means is not particularly limited, and a known thermometer or the like may be used.

  The shift reaction unit 6 includes a high temperature shift catalyst layer 13 provided on the upstream (upper) side and a low temperature shift catalyst layer 14 provided on the downstream (lower) side. The high temperature shift catalyst layer 13 and the low temperature shift catalyst layer 14 are filled with a shift catalyst. This shift reaction unit 6 converts carbon monoxide remaining in the reformed gas into carbon dioxide. That is, in the shift reaction unit 6, the mixture of water vapor and carbon monoxide remaining in the reformed gas is shift-converted into hydrogen and carbon dioxide in the presence of the shift catalyst to generate hydrogen, which remains in the reformed gas. Reduce the concentration of carbon monoxide and increase the hydrogen concentration.

The shift catalyst is not particularly limited, and a known catalyst can be used. Examples thereof include CuO—ZnO ₂ , Fe ₂ O ₃ , Fe ₃ O ₄ , and copper oxide. These can be used alone or in combination of two or more.

<Steam reforming method>
The steam reforming method of the present invention comprises:
Using the autothermal reformer 1,
A step of circulating a mixed gas of hydrocarbon and water vapor through the oxidation reforming unit and the shift reaction unit, and a step of supplying an oxygen-containing gas to the oxidation reforming unit by the oxygen supply means.

  Specifically, first, the heated mixed gas X of hydrocarbon and steam is supplied from the gas supply port 3 in a state where the oxidation reforming unit 5 is heated to the combustion start temperature of hydrocarbon. It does not specifically limit as said hydrocarbon, City gas, such as methane and 13A, kerosene, methanol, etc. can be used. The mixed gas X flows from the gas supply port 3 to the reaction chamber 2 and flows through the oxidation reforming unit 5 and the shift reaction unit 6.

  On the other hand, the oxygen-containing gas Y is supplied from the oxygen-containing gas supply pipes 7 and 8 to the oxidation reforming unit 5. As the oxygen-containing gas Y, air or pure oxygen can be used, but pure oxygen is preferably used. When air is used, energy efficiency is lowered because part of heat generated by combustion is used to raise the temperature of nitrogen, which occupies most of the air. In some cases, nitrogen is denatured into ammonia and the catalyst is deteriorated. Therefore, by using pure oxygen, loss of generated heat can be suppressed and energy efficiency can be increased. On the other hand, catalyst deterioration due to by-products such as ammonia can also be suppressed. Here, pure oxygen refers to a gas having an oxygen concentration of 99% by volume or more, and more preferably, this oxygen concentration is 99.9% by volume or more.

  The mixed gas X supplied from the mixed gas supply port 3 flows into the reaction chamber 2 together with the oxygen-containing gas Y, and a part of hydrocarbons contained in the mixed gas X is oxidized (combusted) in the oxidation reforming unit 5. To do. This combustion heat proceeds the steam reforming reaction of the hydrocarbons to produce hydrogen and carbon monoxide. Carbon monoxide in the reformed gas is converted into hydrogen and carbon dioxide in the shift reaction unit 6. The reformed gas Z thus obtained is discharged from the gas outlet 4 as the hydrogen-rich reformed gas Z.

  Since the steam reforming method is performed using the autothermal reformer, the oxygen-containing gas Y is also supplied from the oxygen-containing gas supply port 10 on the downstream side in the oxidation reforming unit 5. The amount of combustion of hydrocarbons on the downstream side (exit side) can be increased. By doing in this way, the fall of the temperature in the downstream (outlet side) of the oxidation reforming part 5, ie, the reverse reaction of a reforming reaction, can be suppressed, and a hydrogen conversion rate can be raised.

  Further, according to the steam reforming method, the position of the oxygen-containing gas supply port 10 on the downstream side of the oxidation reforming unit 5 and the oxygen-containing gas supply amount from the supply port 10 are adjusted using the mass flow controller 12. As a result, the temperature in the oxidation reforming unit 5 and the amount of oxygen flowing out from the oxidation reforming unit 5 can also be reduced. By doing in this way, it becomes possible to improve the conversion rate and to suppress the activity reduction of the shift catalyst in the shift reaction unit 6.

  The upper limit of the temperature of the oxidation reforming unit 5 during steady operation is preferably 900 ° C. on both the upstream side (near the inlet) and the downstream side (near the outlet), and more preferably 850 ° C. On the other hand, as a minimum of this temperature, 750 degreeC is preferable and 800 degreeC is more preferable. By setting it as such a temperature range, efficient reforming reaction can be performed, suppressing deterioration of a catalyst or a reformer material.

  The oxygen gas supply amount from the downstream oxygen-containing gas supply port with respect to 100 volume parts of the oxygen-containing gas supply amount from the upstream oxygen-containing gas supply port of the oxidation reforming unit 5 is 30 parts by volume in terms of oxygen The amount is preferably 100 parts by volume or less and more preferably 50 parts by volume or more and 80 parts by volume or less. By setting such a supply amount ratio, it is possible to efficiently raise the temperature of the oxidation reforming unit 5 as a whole while suppressing the outflow of oxygen from the oxidation reforming unit 5.

<Other embodiments>
The autothermal reformer and the steam reforming method of the present invention are not limited to the above embodiment. For example, the ends of the pipes 7 and 8 may have a shape that branches into three or more, or may have a shape that is not branched and the ends are simply bent. Moreover, you may use one piping as an oxygen supply means. In this case, as shown in FIG. 3, an oxygen-containing gas supply port 15 located on the upstream side and an oxygen-containing gas supply port 16 located on the downstream side can be disposed at the tip of the pipe 17. The plurality of oxygen-containing gas supply ports 15 are formed such that the direction of oxygen gas ejection is radial with respect to the flow direction of the mixed gas. The same applies to the plurality of oxygen-containing gas supply ports 16. By using such a pipe 17, it becomes possible to efficiently raise the temperature of the oxidation reforming section as a whole with a single pipe 17. Conversely, three or more pipes may be used, and three or more oxygen-containing gas supply ports may be provided in the oxidation reforming section.

  Moreover, the control means which controls each oxygen-containing gas supply amount does not need to be provided. For example, by making it possible to control only the supply amount of one oxygen-containing gas, the self-heat reformer can be simplified.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples.

[Example 1]
Steam reforming was performed using the autothermal reformer 1 shown in FIG. 1 to generate hydrogen. The conditions are as follows.

Oxidation reforming part: platinum catalyst, 150mm length
Shift reaction section: Nickel-based catalyst Hydrocarbon (fuel gas) species: City gas 13A
Hydrocarbon (fuel gas) flow rate: 15.8 NL / min
Water vapor flow rate: 57.8 NL / min
Reforming gas pressure: 0.75 MPaG
Oxygen-containing gas: pure oxygen Oxygen reforming section upstream oxygen flow rate: 5.8 NL / min
Oxidation reformer downstream oxygen flow rate: 3.7 NL / min
The upstream oxygen-containing gas supply port is located at a position approximately 30 mm from the inlet of the oxidation reforming section (a position that is 1/5 of the length of the oxidation reforming section). The contained gas supply port was provided at a position of about 30 mm from the outlet of the oxidation reforming section (position of 1/5 length from the outlet with respect to the length of the oxidation reforming section).
Water vapor and 13 A as fuel gas were supplied from the mixed gas supply port 3 at the above flow rates. The gas reformed in the oxidation reforming unit 5 was denatured in the shift reaction unit 6 and discharged from the reformed gas discharge port 4. At this time, in consideration of deterioration of the catalyst and the reformer material, the upper limit of the upper inlet temperature of the oxidation reforming unit 5 was set to 850 ° C.

  The operation was performed in this manner, and the temperature of the upper inlet and the lower outlet in the oxidation reforming unit 5 in the steady state and the gas composition discharged from the reformed gas outlet were analyzed.

[result]
Upper inlet temperature 850 ° C
Lower outlet temperature 810 ° C
Reformed gas composition H ₂ : 74.8%, CO ₂ : 24.8%, CO: 0.1%, CH ₄ : 0.3%
The methane conversion was 98.7%.

[Comparative Example 1]
The same operation as in Example 1 was performed except that the oxygen reforming portion downstream oxygen flow rate was set to 0 NL / min. Similarly to Example 1, the temperature of the upper inlet and the lower outlet in the oxidation reforming unit 5 in a steady state and the gas composition discharged from the reformed gas outlet were analyzed.

[result]
Upper inlet temperature 850 ° C
Lower outlet temperature 610 ° C
Reformed gas composition H ₂ : 64.4%, CO ₂ : 22.8%, CO: 0.1%, CH ₄ : 12.7%
The methane conversion was 64.3%.

  As shown in the above results, according to the steam reforming method of the example, hydrogen can be generated at a high conversion rate.

  According to the autothermal reformer and the steam reforming method of the present invention, hydrogen can be generated at a high conversion rate, and can be suitably used for, for example, a hydrogen station.

DESCRIPTION OF SYMBOLS 1 Autothermal reformer 2 Reaction chamber 3 Mixed gas supply port 4 Reformed gas discharge port 5 Oxidation reforming part 6 Shift reaction part 7, 8, 8 ', 17 Piping 9, 10, 15, 16 Oxygen containing gas supply Mouth controller 11, 12 Mass flow controller 13 High temperature shift catalyst layer 14 Low temperature shift catalyst layer X Mixed gas Y Oxygen-containing gas Z Reformed gas

Claims (5)

An oxidation reforming section including an oxidation and reforming catalyst,
A shift reaction unit including a shift catalyst located downstream of the oxidation reforming unit, and an oxygen supply means for supplying an oxygen-containing gas to the oxidation reforming unit,
A self-thermal reformer that performs a steam reforming reaction of hydrocarbons by circulating a mixed gas of hydrocarbon and steam through the oxidation reforming unit and the shift reaction unit,
The oxygen supply means includes a plurality of oxygen-containing gas supply ports disposed at least two locations on the upstream side and the downstream side in the oxidation reforming unit, and each oxygen-containing gas supply from the plurality of oxygen-containing gas supply ports. A self-heating reformer characterized by comprising control means for controlling the amount . Self thermal reformer of claim 1, the angle and direction of flow of the injection direction and a mixed gas of oxygen-containing gas is 150 ° or less 90 ° or more in the oxygen-containing gas supply port. The self-heating reformer according to claim 2 , wherein the oxygen-containing gas ejection direction at the oxygen-containing gas supply port is radial with respect to the flow direction of the mixed gas. Using the autothermal reformer according to claim 1, claim 2, or claim 3 ,
A steam reforming method comprising: flowing a mixed gas of hydrocarbon and steam through the oxidation reforming unit and the shift reaction unit; and supplying an oxygen-containing gas to the oxidation reforming unit by the oxygen supply unit. The steam reforming method according to claim 4 , wherein pure oxygen is used as the oxygen-containing gas.

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