JPH04325401A - Method and equipment for producing gaseous hydrogen - Google Patents

Abstract

PURPOSE:To improve a gaseous hydrogen generating efficiency and to decrease required energy in the gaseous hydrogen production by steam reforming of light hydrocarbon. CONSTITUTION:A reactor 11 of heat exchanger construction, with a heat transfer surface, is added. Steam added feed gas passes through one side of the heat transfer surface of the reactor 11 where part of the feed gas is steam reformed, and also the remainder is steam reformed in a reformer 12. Between the outlet of the reformer 12 and a converter 23, is inserted the other side of the heat transfer surface of the reactor 11 where part of the gas leaving the reformer 12 undergoes carbon monoxide conversion reaction. Heat required for steam reforming reaction on one side of the heat transfer surface of the reactor 11 is supplied by the evolution of heat in carbon monoxide conversion reaction being in progress on the other side of the heat transfer surface.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention involves adding steam to light hydrocarbons to perform steam reforming, and further converting carbon monoxide produced by the steam reforming into carbon dioxide to obtain hydrogen gas. The present invention relates to a hydrogen gas production method and a hydrogen gas production apparatus used to carry out the hydrogen gas production method.

0002

[Prior Art] Hydrogen gas is widely produced from light hydrocarbons such as methane, ethane, propane, butane, natural gas, and petroleum naphtha through steam reforming reactions and carbon monoxide conversion reactions. . In the conventional hydrogen gas production method, after adding steam to light hydrocarbons, they are passed through a reformer filled with a nickel-based catalyst, etc.
The modification reaction is carried out at 0°C. In the reforming reaction, carbon monoxide is also produced in addition to hydrogen, so the reaction gas that has passed through the reformer is cooled, passed through a shift converter filled with iron-based catalysts, etc., and monoxide is produced at approximately 180 to 400°C. A carbon conversion reaction is carried out to convert carbon monoxide to carbon dioxide, and at the same time further hydrogen gas is generated. FIG. 3 is a process diagram showing the steps of this conventional hydrogen gas production method.

The steam reforming furnace 21 generates the heat necessary for the steam reforming reaction, which is an endothermic reaction, by combustion, and has a tubular reformer 22 in its center filled with a nickel-based catalyst or the like. is provided. The raw material gas, which is a light hydrocarbon, is preheated in the flue of the steam reforming furnace 21, desulfurized in the desulfurizer 25, then added with steam supplied from the steam drum 24, and heated again in the steam reforming furnace 21. and supplied to the reformer 22. Since steam is added to the raw material gas, a steam reforming reaction proceeds in the reformer 22, resulting in a reaction gas containing hydrogen, carbon monoxide, carbon dioxide, and unreacted steam.

[0004] The reaction gas containing carbon monoxide gas comes out of the reformer 22, is cooled in a gas boiler 28, and then is supplied to a shift converter 23 filled with an iron-based catalyst or the like. Transformer 2
In 3, an exothermic carbon monoxide conversion reaction proceeds, and the water vapor converts carbon monoxide to carbon dioxide, and at the same time further hydrogen is generated. At the outlet of the shift converter 23, the reaction gas mainly consists of hydrogen and carbon dioxide, and also contains a small amount of carbon monoxide and unreacted methane and water vapor. The PSA (Pre
The hydrogen gas is sent to a PSA device 27 and purified in a PSA device 27 to obtain hydrogen gas. The remaining reaction gas from which hydrogen has been separated in the PSA device 27 contains carbon monoxide and methane together with carbon dioxide, and is therefore supplied to the steam reforming furnace 21 as part of the fuel. Further, a part of the reaction gas from which moisture has been removed in the separator 26 is returned to the raw material gas piping through a circulating hydrogen compressor 32 in order to supply hydrogen gas necessary for desulfurization of the raw material gas. It has become.

On the other hand, pure water for generating steam is
Heated by the economizer 30, the steam drum 2
4. By recovering heat from the flue of the steam reforming furnace 21 and each gas boiler 28, 29, steam at a constant temperature and constant pressure is maintained in the steam drum 24,
This water vapor is added to the raw material gas that has passed through the desulfurizer 25, and excess water vapor is discharged from the system. Furthermore, air for combustion is sucked in through the suction port 33, passes through the compressor 34, is preheated in the flue section of the steam reforming furnace 21, and is supplied to the steam reforming furnace 21. The exhaust gas from the steam reforming furnace 21 passes through the compressor 35 and is discharged from the exhaust tower 36 .

[0006] In this hydrogen gas production method, measures have been taken to improve the efficiency, such as recovering heat generated by the carbon monoxide conversion reaction. In the publication,
A technology that uses a concentric double cylindrical reformer with an inlet and an outlet at the same end to exchange heat between the raw material gas entering the reformer and the reaction gas leaving the reformer. Disclosed. In order to improve efficiency, it is necessary to reduce the amount of externally supplied heat required for the steam reforming reaction, and to do so, it is necessary to combine heat recovery and a reaction that matches the temperature of the recovered heat. It is effective to If the amount of heat supplied from the outside is reduced, the amount of fuel supplied to the steam reformer can be reduced, and the combustion exhaust gas of the steam reformer can be effectively used.

[0007]

[Problems to be Solved by the Invention] In the conventional hydrogen production system described above, there is still room for improvement in efficiency. It is desired to reduce the amount of gas and energy. In addition, there is a drawback that excess water vapor is generated, which impairs the energy balance.

An object of the present invention is to reduce the amount of raw material gas and energy required to produce a unit amount of hydrogen gas;
A hydrogen gas production method that suppresses generation of excess water vapor,
It is an object of the present invention to provide a hydrogen gas production apparatus used for carrying out this hydrogen gas production method.

[0009]

[Means for Solving the Problems] The hydrogen gas production method of the present invention includes a first step of adding steam to light hydrocarbons, a second step of reforming a partial amount of the light hydrocarbons, and the second step of reforming a partial amount of the light hydrocarbons. a third step of reforming the light hydrocarbons that were not reformed in the step; a fourth step of converting a partial amount of carbon monoxide produced in the second and third steps; a fifth step of converting carbon monoxide that was not converted in the step, the second step and the fourth step are carried out in a thermally coupled state, and in the fourth step, The heat generated in the reaction provides at least a portion of the heat required in the second step.

[0010] The hydrogen gas production method of the present invention includes a steam reforming furnace, a reformer provided in the steam reforming furnace, and a light hydrocarbon to which steam is added to the inlet of the reformer. and a shift converter connected to an outlet of the reformer, for performing a steam reforming reaction in the reformer,
The hydrogen gas production device for producing hydrogen gas by performing a carbon monoxide conversion reaction in the shift converter, the hydrogen gas production device having a heat exchanger structure, one side of the heat transfer surface of the heat exchanger structure being connected to the supply means. and the inlet of the reformer, the other side of the heat transfer surface has a reactor inserted between the outlet of the reformer and the shift converter; A steam reforming reaction is allowed to proceed, and a carbon monoxide conversion reaction is allowed to proceed on the other side.

[0011]

[Operation] In the hydrogen gas production method of the present invention, a steam reforming reaction is carried out in the second step and the third step, a carbon monoxide reforming reaction is carried out in the fourth step and the fifth step, Since the second step and the fourth step are thermally coupled, a portion of the heat required for the endothermic steam reforming reaction is transferred to the exothermic carbon monoxide conversion when viewed throughout the entire process. Since the heat from the reaction is used, the amount of heat supplied from the outside for the steam reforming reaction can be reduced.

The reaction rate in the second step is preferably about 20% or less, and the reaction rate in the fourth step is preferably 70% or less. As light hydrocarbons, hydrocarbons such as methane, ethane, propane, butane, petroleum naphtha, petroleum gas, and natural gas can be favorably used, as in conventional steam reforming.

The hydrogen gas production apparatus of the present invention has a reactor having a heat exchanger structure, and the steam reforming reaction proceeds on one side of the heat transfer surface of the reactor, and the monoxide reaction proceeds on the other side. Since the carbon conversion reaction is allowed to proceed, part of the heat required for the steam reforming reaction in the entire apparatus can be covered by the heat from the carbon monoxide conversion reaction. It is desirable to fill the part of the reactor where the steam reforming reaction takes place with a nickel-based catalyst, etc., and the part where the carbon monoxide conversion reaction takes place with an iron-based catalyst, etc. .

Generally, the temperature suitable for the steam reforming reaction is higher than the temperature suitable for the carbon monoxide conversion reaction, so it is desirable to allow the steam reforming reaction to proceed at a lower temperature than the conventional one. It is desirable to use nickel-based catalysts that operate at lower temperatures. As such a catalyst, for example, one described in Japanese Patent Application No. 164432/1996 can be used.

[0015] As a reformer, Japanese Patent Application Laid-open No. 165-1983
A concentric double cylindrical reformer having an inlet and an outlet at the same end as shown in Japanese Patent No. 36 may also be used. In this concentric double cylindrical tube reformer, heat exchange is performed between the inlet side and the outlet side, so the outlet temperature is low, and the monoxide temperature between the outlet of this concentric double cylindrical tube reformer and the reactor is low. It can be directly connected to the side where the carbon conversion reaction takes place, and there is no need to cool the gas flowing between them.

[0016] The reaction rate of the steam reforming reaction in the reactor is desirably about 20% or less based on the light hydrocarbons of the raw material, and the reaction rate of the carbon monoxide conversion reaction in the reactor is preferably about 70% or less. It is desirable to do so.

[0017]

Embodiments Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a process diagram showing the steps of a hydrogen gas production method according to an embodiment of the present invention, and FIG. 2 is a schematic cross-sectional view showing the configuration of a reactor. First, the configuration of a hydrogen gas production apparatus used to carry out the hydrogen gas production method of the present invention will be explained with reference to the process diagram of FIG.

The steam reforming furnace 21 generates part of the heat necessary for the steam reforming reaction, and has a reformer 12 provided in its center. This reformer is JP-A-59-1
As shown in Japanese Patent No. 6536, it is a concentric double cylindrical tube type having an inlet and an outlet at the same end, and the inside thereof is filled with a known nickel-based catalyst. The inlet of the reformer 12 is the outlet on one side of the heat transfer surface of the reactor 11 (lower side in the figure).
The outlet of the reformer 12 is connected to the inlet on the other side of the heat transfer surface of the reactor 11 (left side in the figure). As will be described later, the reactor 11 has a heat exchanger structure having a heat transfer surface, and on one side of the heat transfer surface of the reactor 11,
As shown in the above-mentioned Japanese Patent Application No. 2-164432, the catalyst is filled with a nickel-based catalyst that is active at lower temperatures than conventional ones for steam reforming reactions. Further, the other side of the heat transfer surface is filled with a known iron-based catalyst that is active in a carbon monoxide reforming reaction.

[0019] The raw material gas, which is a light hydrocarbon, is supplied to this hydrogen gas production apparatus from a supply source. A part of the raw material gas is supplied to the steam reforming furnace 21 as fuel, and the rest is preheated in the flue of the steam reforming furnace 21.
It is sent to a desulfurizer 25 to prevent poisoning of the catalyst. The outlet of the desulfurizer 25 is connected to the inlet of the reactor 11 on one side of the heat transfer surface.

A gas boiler 28, a shift converter 23, a gas boiler 29, an economizer 30, and a cooler 31 are connected in series to the outlet on the other side of the heat transfer surface of the reactor 11, and a separator for separating moisture. 26 are connected. The shift converter 23 is for advancing a carbon monoxide conversion reaction, and is filled with a known iron-based catalyst. Each gas boiler 28, 29 is for recovering heat from the reaction gas passing therethrough, and the economizer 30 is for heating pure water with the heat of the reaction gas. Separator 26
The outlet of is connected to the inlet of a PSA device 27 for purifying hydrogen gas. Further, a part of the gas coming out of the separator 26 passes through the circulating hydrogen compressor 32 and joins the raw material gas before being preheated. Hydrogen gas separated by the PSA device 27 is supplied to the outside as product hydrogen gas, and gases other than hydrogen are supplied to the steam reforming furnace 21 as fuel.

Pure water for generating steam is supplied from a pure water source, heated by an economizer 30, and sent to the steam drum 24. The steam drum 24 is connected to piping for recovering heat from the flue of the steam reforming furnace 21 and the gas boilers 28 and 29, so that steam at a constant pressure and temperature is maintained within the steam drum 24. It has become. This water vapor is transferred to the desulfurizer 2
It is added to the raw material gas immediately after the outlet of No. 5. Air for combustion in the steam reforming furnace 21 is sucked in from the suction port 33, passes through the compressor 34, and passes through the steam reforming furnace 21.
1 is preheated at the top of the furnace and supplied to the steam reforming furnace 21,
The exhaust gas from the steam reforming furnace 21 passes through a compressor 35 and is discharged from an exhaust tower 36.

[0022] Here, the reactor 11 will be explained with reference to FIG.

As mentioned above, the reactor 11 has a heat exchanger structure having a heat transfer surface, for example, as shown in FIG.
Inside the reactor container 40, a large number of thin tubes 41 which are heat transfer bodies are arranged.
The structure is equipped with The thin tube 41 is made of a material with good thermal conductivity, so that heat can be efficiently exchanged between the inside and outside of the thin tube 41. The inside of the thin tube 41 is filled with a nickel-based catalyst 42, and the outside portion of the thin tube 41 is filled with an iron-based catalyst. Desulfurizer 25
The raw material gas from (FIG. 1) enters the reactor 11 from the inlet 44 on the upper side of the drawing, passes through the inside of the capillary tube 41, and is discharged from the outlet 45 on the lower side of the drawing. On the other hand, the reformer 12 (Fig. 1)
The reaction gas from the reactor 11 is fed from the inlet 46 on the left side in the figure
It passes through the outside of the thin tube 41 and is discharged from the outlet 47 on the right side of the figure. In this case, it is preferable that the gas flow inside and outside the thin tube 41 be so-called countercurrent. Further, as the nickel-based catalyst 42, as described above, it is preferable to use one that exhibits activity at relatively low temperatures.

In the reactor 11 described here, the capillary tube 41
Although the structure is such that the nickel-based catalyst 42 is present inside the thin tube 41, the thin tube 41 may be filled with an iron-based catalyst, and the outside of the thin tube 41 may be filled with a nickel-based catalyst. At this time, the raw material gas from the desulfurizer 25 is made to flow through the outside of the thin tube 41, and the reaction gas from the reformer 12 is made to flow through the inside of the thin tube 41. Furthermore, as the reactor 11, a reactor having a heat exchanger structure other than a thin tube may be used, and the steam reforming reaction and the carbon monoxide conversion reaction can be carried out in a thermally coupled state. Bye. Furthermore, the catalysts packed on both sides of the heat transfer surface do not need to be nickel-based catalysts or iron-based catalysts, respectively, as long as they have activity for steam reforming reactions and carbon monoxide conversion reactions.

Next, the hydrogen gas production method of this embodiment will be explained by explaining the hydrogen production process in this hydrogen gas production apparatus.

[0026] The raw material gas consisting of light hydrocarbons is supplied from a supply source, and a part of it is used as fuel in the steam reforming furnace 21.
sent to. The remaining part of the raw material gas is mixed with hydrogen-containing gas circulating from the separator 26 and sent to the steam reforming furnace 2.
1 flue, and through a desulfurizer 25, water vapor from a steam drum 24 is added and introduced to one side of the heat transfer surface of the reactor 11. The temperature of the raw material gas at the time of introduction is, for example, about 380°C. As described later, this reactor 1
On the other side of the heat transfer surface of No. 1, an exothermic carbon monoxide conversion reaction is progressing, so the raw material gas introduced to one side of the heat transfer surface is converted into heat due to the carbon monoxide conversion reaction. Due to the action of the nickel-based catalyst, it undergoes a steam reforming reaction, and a portion of it is reformed into hydrogen gas. The outlet temperature from one side of the heat transfer surface of the reactor 11 is, for example, about 500°C. The reason why the temperature is higher on the outlet side than on the inlet side is because the gases are flowing countercurrently within the reactor 11. The partially reformed raw material gas is sent to the inlet of the reformer 12, where the remaining part is reformed and reacted with hydrogen, carbon monoxide, carbon dioxide, and unreacted water vapor. It becomes gas.

The reaction gas from the outlet of the reformer 12 is introduced to the other side of the heat transfer surface of the reactor 11. The temperature of the reaction gas at this time is, for example, about 540°C. In addition, since the reformer 12 is of a concentric double cylindrical tube type having an inlet and an outlet at the same end, the outlet temperature of the reformer 12 is also around this temperature (approximately 540°C). . Since the other side of this heat transfer surface is filled with an iron-based catalyst, a portion of the reaction gas undergoes a carbon monoxide conversion reaction here to generate hydrogen, and the heat associated with this reaction is transferred as described above. As such, it is utilized for the steam reforming reaction that is proceeding on one side of the heat transfer surface. The reaction gas is discharged from the outlet on the other side of the heat transfer surface of the reactor 11, and the outlet temperature is approximately 430°C. The reaction gas discharged from this outlet is cooled by the gas boiler 28 and introduced into the shift converter 23, where the remaining carbon monoxide is converted into carbon dioxide by a carbon monoxide conversion reaction, and at the same time, hydrogen is further generated. do. Therefore, at the outlet of the shift converter 23, the reaction gas mainly consists of hydrogen and carbon dioxide, and contains trace amounts of carbon monoxide, methane and water vapor. Thereafter, the reaction gas is cooled while passing through a gas boiler 29, an economizer 30, and a cooler 31, and moisture is removed in a separator 26. A portion of the reaction gas from which water has been removed is returned to raw material gas by the circulating hydrogen compressor 32, and the remainder is introduced into the PSA device 27 where it is separated into hydrogen and other gases, and the hydrogen is purified. The purified hydrogen is sent out of the system as product hydrogen gas. On the other hand, since gases other than hydrogen contain combustible components in addition to carbon dioxide, they are supplied to the steam reforming furnace 21 as fuel.

[0028] Here, the heat balance in this hydrogen generation process will be considered. A part of the raw material gas is reformed by a steam reforming reaction in the reactor 11, but the heat required for this reaction is absorbed by the carbon monoxide conversion that is proceeding on the opposite side of the reactor 11 across the heat transfer surface. It is covered by the heat generated from the reaction. On the other hand, in conventional hydrogen gas production methods, the entire amount of heat required for the steam reforming reaction is not covered by the combustion heat in the steam reforming furnace.
The heat generated by the carbon monoxide conversion reaction was used only to generate water vapor. Therefore, the hydrogen generation process of this embodiment requires less fuel and less steam than the conventional process. For this reason, the amount of raw material gas used as fuel is reduced, and accordingly,
The energy required for supplying and exhausting air for combustion is reduced. Since the amount of water vapor generated is small,
Almost no surplus water vapor is generated, compared to conventional ones.
The energy carried away by excess water vapor can be significantly reduced. In other words, in this example, compared to the conventional hydrogen gas production method shown in FIG. ■ The capacity of the exhaust compressor can be reduced by about 30%, ■ The portion of the raw material gas that is used as fuel for the steam reformer can be reduced by about 40%, and ■ The amount of excess steam can be reduced by about 40%. The amount of carbon monoxide introduced into the PSA device is reduced, and the amount of hydrogen in the PSA device is reduced because the carbon monoxide conversion reaction is carried out in two stages. Gas recovery rate is improved.

[0029]

As explained above, in the hydrogen gas production method of the present invention, the steam reforming reaction is carried out in the second step and the third step, and the carbon monoxide reforming reaction is carried out in the fourth step and the third step. By carrying out step 5 and thermally coupling the second step and fourth step, a part of the heat required for the steam reforming reaction, which is an endothermic reaction, can be replaced by an exothermic reaction when looking at the entire process. The heat from a certain carbon monoxide conversion reaction improves the efficiency of hydrogen gas generation, reduces the amount of energy required, and suppresses the generation of excess water vapor.

Further, the hydrogen gas production apparatus of the present invention has a reactor having a heat exchanger structure, and the steam reforming reaction proceeds on one side of the heat transfer surface of the reactor, and the steam reforming reaction proceeds on the other side. By allowing the carbon oxide conversion reaction to proceed, part of the heat required for the steam reforming reaction in the entire device is covered by the heat from the carbon monoxide conversion reaction, improving the hydrogen gas generation efficiency.
This has the effect of reducing the amount of energy required and suppressing the generation of excess water vapor.

[Brief explanation of the drawing]

FIG. 1 is a process diagram of a hydrogen gas production method according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view showing the configuration of a reactor.

FIG. 3 is a process diagram of a conventional hydrogen gas production method.

[Explanation of symbols]

11 Reactor 12, 22 Reformer 21 Steam reforming furnace 23
Transformer 24 Steam drum 25
Desulfurizer 26 Separator 27 PSA device 41 Capillary tube 42 Nickel catalyst 43
Iron-based catalyst

Claims (3)

[Claims] 1. A method for producing hydrogen gas in which hydrogen gas is obtained by adding steam to light hydrocarbons to perform steam reforming, and further converting carbon monoxide produced by the steam reforming into carbon dioxide. a first step of adding steam to hydrocarbons, a second step of reforming a partial amount of the light hydrocarbons, and a third step of reforming the light hydrocarbons that were not reformed in the second step. step, and the second
and a fourth step of converting a partial amount of carbon monoxide produced in the third step, and a fifth step of converting carbon monoxide not converted in the fourth step, Step 2 and the fourth step are carried out in a thermally coupled state, and at least part of the heat required in the second step is absorbed by the heat generated by the reaction in the fourth step. A method for producing hydrogen gas, which is characterized by the ability to 2. A steam reforming furnace, a reformer provided in the steam reformer, a supply means for supplying light hydrocarbons to which steam is added to an inlet of the reformer, and a shift converter connected to the outlet of the reformer, and hydrogen gas is produced by carrying out a steam reforming reaction in the reformer and carrying out a carbon monoxide conversion reaction in the shift converter. The apparatus has a heat exchanger structure, one side of the heat transfer surface of the heat exchanger structure is inserted between the supply means and the inlet of the reformer, and the other side of the heat transfer surface is inserted between the supply means and the inlet of the reformer. It has a reactor inserted between the outlet of the reformer and the shift converter, and allows a steam reforming reaction to proceed on one side and a carbon monoxide conversion reaction to proceed on the other side. A hydrogen gas production device characterized by: 3. The reformer is a concentric double cylindrical tube reformer having an inlet and an outlet at the same end, and the outlet of the concentric double cylindrical reformer and the other of the heat transfer surfaces of the reactor Between the side of
3. The hydrogen gas production apparatus according to claim 2, wherein there is substantially no means for cooling the fluid flowing between the hydrogen gas production apparatus.