JP2000247604A - Hydrogen producing device and method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently recover carbon dioxide, to produce hydrogen at high efficiency, to improve the energy efficiency of the whole system and to prolong the service of each catalyst in use. SOLUTION: A reformed gas consisting essentially of hydrogen is obtained in a stem reforming reactor 12 by mixing steam with a gas, from which sulfur portion contained in liquefied natural gas is removed in a desulfurization reactor 11, and using the heat source from a combustion burner. The carbon monoxide and moisture contained in the reformed gas are respectively removed in a carbon monoxide remover 13 and a cooling moisture separator 14 and hydrogen is selectively separated from the reformed gas in a gas separator 15. The remaining gas after the separation is supplied to a combustion burner, steam is removed from the off gas of the combustion burner in a gas-liquid separator 16 and carbon dioxide contained in the off-gas is heat exchanged with the liquefied natural gas as evaporation heat source. As a result, carbon dioxide is solidified and recovered in a recovering device 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and method for producing hydrogen by steam reforming liquefied natural gas to produce hydrogen and recovering carbon dioxide contained in separated off-gas.

[0002]

2. Description of the Related Art For example, in a fuel power plant, liquefied natural gas is reformed in a steam reforming reactor to obtain hydrogen. In this case, in order to obtain the heat of reforming reaction required in the steam reforming reactor, a part of the reformed gas obtained in the steam reforming reactor is burned and used as the combustion source. . Since liquefied natural gas contains components other than hydrogen, a gas other than hydrogen is also generated in a hydrogen production apparatus that produces hydrogen by such a steam reforming reaction.

That is, the reformed gas obtained in the steam reforming reactor contains hydrogen as a main component, and a part of the reformed gas is supplied to the steam reforming reactor as a fuel source of reaction heat in the steam reforming reactor. You. The exhaust gas of the reformed gas used as a fuel source for this steam reforming reaction is a gas containing carbon dioxide and water vapor as main components, and this off-gas is discharged to the atmosphere or recovered after being separated into carbon dioxide and water vapor. You.

In such a hydrogen production apparatus, seawater or the like is used as a heat medium for vaporizing liquefied natural gas which is a hydrocarbon fuel. The reaction heat of the reforming reaction is obtained by burning a part of the reformed gas containing hydrogen as a main component by a combustion burner. For the recovery of the carbon dioxide gas thus generated, an alkali absorption method, an adsorption method using an adsorbent, a pressure swing adsorption method, or the like is used.

[0005]

However, when recovering carbon dioxide gas, the alkali absorption method requires the supply of a recovery medium and the processing after recovery, and the adsorption method using an adsorbent requires the treatment of the gas after adsorption. Is required. In the pressure swing adsorption method, since a driving source is required, the energy efficiency of the entire system is reduced.

Further, it is necessary to vaporize liquefied natural gas as a fuel source, and seawater is used as a heat medium for the vaporization of the liquefied natural gas. Energy efficiency is reduced.

The supply of reaction heat to the steam reforming reactor is obtained by burning the reformed gas with a combustion burner, so that the combustion state may change and the temperature distribution may change. . In this case, the reforming efficiency and the life of the reforming catalyst decrease. In addition, depending on the combustion conditions, incomplete combustion may result in emission of high-energy components.

[0008] On the other hand, since sulfur is present in liquefied natural gas, if not sufficiently removed in the desulfurization reactor, the sulfur is led to the reforming reactor, thereby lowering the reforming efficiency and the life of the reforming catalyst. Sometimes. Further, when a large amount of carbon monoxide is present in the reformed gas, the reaction of reducing carbon monoxide in the carbon monoxide remover is an exothermic reaction, which may shorten the catalyst life.

An object of the present invention is to provide a hydrogen production apparatus and method capable of efficiently recovering carbon dioxide gas and producing hydrogen with high efficiency, improving the energy efficiency of the entire system and extending the life of each catalyst used. That is.

[0010]

According to a first aspect of the present invention, there is provided a hydrogen production apparatus, comprising: a desulfurization reactor for removing sulfur contained in liquefied natural gas; and a process for converting water vapor into gas desulfurized by the desulfurization reactor. A steam reforming reactor for mixing and performing a steam reforming reaction with a heat source from a combustion burner to obtain a reformed gas containing hydrogen as a main component; and a steam reforming reactor obtained in the steam reforming reactor. A carbon monoxide remover for reducing carbon oxide, a cooling water separator for removing water contained in the reformed gas from the carbon monoxide remover, and a reformate gas from the cooling water separator. A gas separator for separating hydrogen and supplying the remaining separated gas to the combustion burner of the steam reforming reactor; and a gas-liquid separator for removing steam from off-gas of the combustion burner of the steam reforming reactor. And the gas-liquid separator Characterized by comprising a recovery unit for recovering and solidifying the liquefied natural gas and heat exchange with the carbon dioxide gas to carbon dioxide gas contained in the off-gas after over a vaporization heat of the liquefied natural gas.

According to the first aspect of the present invention, sulfur contained in the liquefied natural gas is removed by a desulfurization reactor, steam is mixed with the desulfurized gas, and steam is reformed by a heat source from a combustion burner. A reforming gas containing hydrogen as a main component is obtained by performing a steam reforming reaction using a high quality reactor. Then, the carbon monoxide contained in the reformed gas is reduced by a carbon monoxide remover, and the water contained in the reformed gas is further removed by a cooling water separator, and selected from the reformed gas by a gas separator. To separate hydrogen. The separated gas is supplied to a combustion burner, and water vapor is removed from the off-gas of the combustion burner by a gas-liquid separator, and carbon dioxide contained in the off-gas is exchanged with liquefied natural gas as a heat source for vaporizing the liquefied natural gas. . Thereby, the carbon dioxide gas is solidified and recovered by the recovery device.

[0012] The hydrogen production apparatus according to the second aspect of the present invention comprises:
The invention according to claim 1, wherein a combustion catalyst is provided in place of the combustion burner of the steam reforming reactor, and the remaining gas from which hydrogen has been selectively separated by the gas separator is supplied to the combustion catalyst. I do.

According to the hydrogen production apparatus according to the second aspect of the present invention, in addition to the operation of the first aspect of the present invention, the combustion catalyst provided in place of the combustion burner is obtained by selectively separating hydrogen with a gas separator. The gas generates heat to cause a steam reforming reaction.

According to a third aspect of the present invention, there is provided a hydrogen production apparatus comprising:
In the invention according to claim 1 or 2, the gas separator selectively separates hydrogen by a pressure swing adsorption method or a membrane separation method using a palladium membrane.

According to the hydrogen production apparatus of the third aspect of the present invention, in addition to the operation of the first or second aspect of the present invention, the gas separator can be selectively operated by a pressure swing adsorption method or a membrane separation method using a palladium membrane. Separate hydrogen.

[0016] The hydrogen production apparatus according to the invention of claim 4 comprises:
In the invention according to any one of claims 1 to 3,
The carbon monoxide remover has a catalytic reactor containing at least Cu.

According to the hydrogen production apparatus according to the fourth aspect of the present invention, in addition to the function of any one of the first to third aspects of the present invention, the carbon monoxide remover employs a catalytic reactor containing Cu. Carbon monoxide is removed. The reaction temperature is dispersed.

[0018] The hydrogen production apparatus according to the invention of claim 5 comprises:
In the invention according to any one of claims 1 to 4,
The desulfurization reactor has a catalyst reactor containing at least Cu.

According to the hydrogen production apparatus according to the fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the desulfurization reactor is desulfurized by a catalytic reactor containing Cu. Therefore, the sulfur content flowing into the steam reforming reactor is reduced.

[0020] The method for producing hydrogen according to the invention of claim 6 comprises:
The sulfur content contained in the liquefied natural gas is removed, steam is mixed with the gas from which the sulfur content has been removed, and a steam reforming reaction is performed with a heat source from a combustion burner to produce a reformed gas containing hydrogen as a main component, Reduce carbon monoxide contained in the reformed gas, remove water contained in the reformed gas from which carbon monoxide has been removed, and selectively separate hydrogen from the reformed gas from which the moisture has been removed to form hydrogen. The remaining gas from which hydrogen has been separated is supplied to the combustion burner, water vapor is removed from the off-gas of the combustion burner, and carbon dioxide contained in the off-gas from which the water vapor has been removed is used as a heat source for vaporizing the liquefied natural gas. It is characterized in that the carbon dioxide gas is solidified and recovered by heat exchange with liquefied natural gas.

According to the method for producing hydrogen according to the sixth aspect of the present invention, the gas from which the sulfur content is removed from the liquefied natural gas is mixed with steam and subjected to a steam reforming reaction with a heat source from a combustion burner to perform hydrogen reforming. To generate a reformed gas containing as a main component. Next, carbon monoxide and moisture contained in the reformed gas are removed, hydrogen is selectively separated to generate hydrogen, and the remaining gas from which hydrogen has been separated is supplied to a combustion burner. Water vapor is removed from the off-gas of the combustion burner, and carbon dioxide contained therein is exchanged with liquefied natural gas as a heat source for vaporizing the liquefied natural gas. Thereby, the carbon dioxide is solidified and recovered.

[0022] The method for producing hydrogen according to the invention of claim 7 comprises:
The sulfur content contained in the liquefied natural gas is removed, steam is mixed with the gas from which the sulfur content has been removed, and a steam reforming reaction is performed with a heat source from a combustion catalyst to generate a reformed gas mainly containing hydrogen, Reduce carbon monoxide contained in the reformed gas, remove water contained in the reformed gas from which carbon monoxide has been removed, and selectively separate hydrogen from the reformed gas from which the moisture has been removed to form hydrogen. Is generated, the remaining gas from which hydrogen is separated is supplied to the combustion catalyst, water vapor is removed from the off gas of the combustion catalyst, and carbon dioxide contained in the off gas from which the water vapor has been removed is used as a heat source for vaporizing the liquefied natural gas. It is characterized in that the carbon dioxide gas is solidified and recovered by heat exchange with liquefied natural gas.

According to the method for producing hydrogen according to the seventh aspect of the present invention, the gas from which the sulfur content is removed from the liquefied natural gas is mixed with steam, and a steam reforming reaction is performed by a heat source using a combustion catalyst to perform hydrogen reforming. To generate a reformed gas containing as a main component. Next, carbon monoxide and moisture contained in the reformed gas are removed, and further, hydrogen is selectively separated to generate hydrogen,
The remaining gas from which hydrogen has been separated is supplied to the combustion catalyst. Water vapor is removed from the off-gas of the combustion catalyst, and carbon dioxide contained therein is exchanged with liquefied natural gas as a heat source for vaporizing the liquefied natural gas. Thereby, the carbon dioxide is solidified and recovered.

[0024]

Embodiments of the present invention will be described below. FIG. 1 is a configuration diagram of the hydrogen production apparatus according to the first embodiment of the present invention. Liquefied natural gas (LNG), which is a raw material of hydrogen, is supplied to the desulfurization reactor 11 through the gas supply pipe 17 and the recovery unit 10. The desulfurizer 11 removes the sulfur content in the liquefied natural gas, which is a raw material for hydrogen, and the gas desulfurized in the desulfurization reactor 11 is added with steam from a steam supply pipe 18. The gas mixed with steam is led to the steam reforming reactor 12, where a reformed gas containing hydrogen as a main component is generated.

The reformed gas generated in the steam reforming reactor 12 is led to a carbon monoxide remover 13. In the carbon monoxide remover 13, carbon monoxide in the reformed gas is converted into carbon dioxide by a shift reaction and reduced. The reformed gas from which the carbon monoxide has been reduced by the carbon monoxide remover 13 is separated from the remaining water in the reformed gas by the cooling water separator 14,
Furthermore, the hydrogen in the reformed gas is selectively and efficiently separated by the gas separator 15. Thus, hydrogen is generated from the gas separator 15.

On the other hand, the remaining off-gas from which hydrogen has been separated by the gas separator 15 is led to the combustion burner of the steam reforming reactor 12 through the burner fuel gas supply pipe 19 and mixed with air from the air supply pipe 20. Then, the off-gas is burned by a combustion burner to obtain a heat quantity necessary for reforming. That is, the steam reforming reaction is performed by burning a part of the reformed gas generated in the steam reforming reactor 12. As described above, the steam reforming reactor 12 has the reforming tube filled with the steam reforming catalyst and the fuel burner that supplies reaction heat required for the steam reforming reaction.

The off-gas generated by the combustion in the steam reforming reactor 12 is led to the gas-liquid separator 16 through the combustion gas pipe 21. The off-gas generated by the combustion in the steam reforming reactor 12 contains steam and carbon dioxide, and is separated by the gas-liquid separator 16.

The carbon dioxide gas separated by the gas-liquid separator 16 is
The exhaust gas is led to the recovery unit 10 through the exhaust gas pipe 22. The recovery unit 10 performs heat exchange between carbon dioxide gas and liquefied natural gas. That is, by heat exchange between carbon dioxide gas in the off-gas and liquefied natural gas serving as a cooling and heating medium, the carbon dioxide gas is solidified and recovered as dry ice in the recovery unit 10, and the liquefied natural gas is simultaneously vaporized.

This eliminates the need for a recovery medium and post-recovery processing in the recovery of carbon dioxide gas.
Since no driving source is required, the energy efficiency of the entire system is improved. Further, in the vaporization of liquefied natural gas, a heat medium (seawater) for vaporization and a power source for supplying the heat medium (seawater) are not required, so that the energy efficiency of the entire system is improved.

FIG. 2 is an explanatory diagram of the gas separator 15 according to the first embodiment of the present invention. Steam reforming reactor 12
The reformed gas generated by the steam reforming reaction is guided to a gas separator 15 via a carbon monoxide remover 13 and a cooling water separator 14. In the gas separator 15, a pressure swing adsorption method or a membrane separation method using a palladium membrane is used.
Hydrogen and other gases are separated to obtain hydrogen, and the other gases are supplied to the combustion burner via a burner combustion gas supply pipe 19 as combustion fuel for the combustion burner of the steam reforming reactor.

That is, since the reformed gas is separated into hydrogen and other off-gases by a pressure swing adsorption method for selectively separating hydrogen or a membrane separation method using a palladium membrane, hydrogen is selectively and highly purified. Can be recovered. For this reason, the hydrogen production efficiency of the entire system is improved.

FIG. 3 is an explanatory view of the carbon monoxide remover 13 according to the first embodiment of the present invention. FIG. 3 (a) shows Cu (copper) between the high temperature reactor 13a and the low temperature reactor 13b.
FIG. 3 (b) shows a low-temperature reactor 13b and a catalytic reactor 13c containing Cu (copper) arranged in parallel at the subsequent stage of the high-temperature reactor 13a. It shows what is provided.

In FIG. 3A, the steam reforming reactor 1
The reformed gas generated by the steam reforming reaction in Step 2 is led to the high-temperature reactor 13a of the carbon monoxide remover 13, where the carbon monoxide is removed and the monoxide that cannot be removed by the high-temperature reactor 13a is removed. The carbon is introduced into the catalytic reactor 13c and further introduced into the low-temperature reactor 13b and removed.

In FIG. 3B, in the steam reforming reactor 1
The reformed gas generated by the steam reforming reaction in Step 2 is led to the high-temperature reactor 13a of the carbon monoxide remover 13, where the carbon monoxide is removed and the monoxide that cannot be removed by the high-temperature reactor 13a is removed. The carbon is introduced into and removed from the catalytic reactor 13c and the low-temperature reactor 13b.

As described above, the carbon monoxide remover 13 is divided into the high-temperature reactor 13a and the low-temperature reactor 13b, and the catalyst reactor 13c containing at least Cu is connected to the high-temperature reactor 13a as shown in FIG. 13a and the low-temperature reactor 13b in series or as shown in FIG.
3b is attached in parallel. Therefore, the carbon monoxide remover 13
Since the amount of carbon monoxide in the reformed gas guided to the low-temperature reaction section 13b of the low-temperature reaction section 13b decreases,
The life of the low-temperature shift catalyst used for 3b is improved.

FIG. 4 is an explanatory view of the desulfurization reactor 11 according to the first embodiment of the present invention. Liquefied natural gas, which is a raw material, is vaporized in a recovery unit 10 and desulfurized in a desulfurization reactor 11 of a desulfurization reactor 11.
1a. The desulfurization reactor 11 is configured such that a catalyst reactor 11b containing at least Cu is connected in series at the subsequent stage of the desulfurizer 11a for reducing the sulfur content in the gas. Reactor 11
The value is further reduced by b.

As a result, the sulfur content in the gas led to the reforming pipe of the steam reforming reactor 12 is reduced, so that the reforming efficiency and the life of the reforming catalyst are improved.

Next, a second embodiment of the present invention will be described. FIG. 5 is a configuration diagram of the hydrogen production apparatus according to the second embodiment of the present invention. As compared with the first embodiment shown in FIG. 1, a combustion catalyst 23 is provided in place of the combustion burner of the steam reforming reactor 12, and the remaining gas from which hydrogen has been selectively separated by the gas separator 15 is used as the combustion catalyst. The combustion catalyst 23 is used to obtain the reaction heat of the steam reforming reaction. Other configurations are the same as those of the first embodiment shown in FIG. 1, and therefore, the same components are denoted by the same reference characters and description thereof is omitted.

In FIG. 5, as the heat source of the steam reforming reaction in the steam reforming reactor 12, catalytic combustion is performed by the combustion catalyst 23 and the heat is used. In the catalytic combustion by the combustion catalyst 23, complete combustion is performed, and the off-gas discharged to the combustion gas pipe 21 has a composition of only carbon dioxide and water vapor.

As described above, since the reaction heat required for the reforming reaction is supplied by the catalytic combustion of the combustion catalyst 23, the reforming tube of the steam reforming reactor 12 is uniformly heated, and the reforming efficiency and the reforming catalyst are improved. The service life is improved. Further, the emission of the remaining high-energy gas components can be reduced.

[0041]

As described above, according to the present invention, a medium and a driving source are not required for vaporizing liquefied natural gas and recovering carbon dioxide gas, so that the energy efficiency of the entire system is improved. Further, by providing a desulfurization reactor, supplying heat to the reformer by catalytic combustion, and providing a carbon monoxide remover, the efficiency and life of each catalyst used can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a hydrogen production apparatus according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a gas separator according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram of a carbon monoxide remover according to the first embodiment of the present invention.

FIG. 4 is an explanatory diagram of a desulfurization reactor according to the first embodiment of the present invention.

FIG. 5 is a configuration diagram of a hydrogen production apparatus according to a second embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 10 recovery unit 11 desulfurization reactor 12 steam reforming reactor 13 carbon monoxide remover 14 cooling water separator 15 gas separator 16 gas-liquid separator 17 gas supply pipe 18 steam supply pipe 19 burner fuel gas supply pipe 20 air supply Piping 21 Combustion gas pipe 22 Exhaust gas pipe 23 Combustion catalyst

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Ryo Harada 2-4-4 Suehirocho, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture Inside Keihin Works, Toshiba Corporation (72) Junji Hizuka 2-chome, Suehirocho, Tsurumi-ku, Yokohama-shi, Kanagawa No. 4 F-term in Toshiba i-Tech Corporation (reference) 4G040 EA03 EA06 EB01 EB33 EC02 EC03

Claims (7)

[Claims] 1. A desulfurization reactor for removing sulfur contained in a liquefied natural gas, and steam mixed with the gas desulfurized in the desulfurization reactor, and a steam reforming reaction is performed by a heat source from a combustion burner to produce hydrogen. A steam reforming reactor for obtaining a reformed gas as a main component, and a carbon monoxide remover for reducing carbon monoxide contained in the reformed gas obtained in the steam reforming reactor,
A cooling water separator for removing water contained in the reformed gas from the carbon monoxide remover, and selectively separating hydrogen from the reformed gas from the cooling water separator and separating the remaining gas. A gas separator for supplying to the combustion burner of the steam reforming reactor, a gas-liquid separator for removing steam from off-gas of the combustion burner of the steam reforming reactor, and an off-gas after passing through the gas-liquid separator A hydrogen recovery device, comprising: a heat recovery unit for exchanging heat with the liquefied natural gas using carbon dioxide contained in the liquefied natural gas as a heat of vaporization of the liquefied natural gas to solidify and recover the carbon dioxide gas. 2. A combustion catalyst is provided in place of the combustion burner of the steam reforming reactor, and the remaining gas from which hydrogen has been selectively separated by the gas separator is supplied to the combustion catalyst. Item 2. A hydrogen production apparatus according to item 1. 3. The gas separator according to claim 1, wherein the gas separator selectively separates hydrogen by a pressure swing adsorption method or a membrane separation method using a palladium membrane.
A hydrogen production apparatus according to item 1. 4. The carbon monoxide remover comprises at least Cu
The hydrogen production apparatus according to any one of claims 1 to 3, further comprising a catalyst reactor containing: 5. The hydrogen production apparatus according to claim 1, wherein the desulfurization reactor has a catalyst reactor containing at least Cu. 6. A reforming process in which sulfur contained in liquefied natural gas is removed, steam is mixed with the gas from which sulfur has been removed, and a steam reforming reaction is carried out using a heat source from a combustion burner to reform hydrogen-based gas. A gas is generated, carbon monoxide contained in the reformed gas is reduced, moisture contained in the reformed gas from which carbon monoxide is removed is removed, and hydrogen is selectively produced from the reformed gas from which moisture is removed. To produce hydrogen, the remaining gas from which hydrogen has been separated is supplied to the combustion burner, and water vapor is removed from the off-gas of the combustion burner, and the carbon dioxide contained in the off-gas from which the water vapor has been removed is converted to the liquefied natural gas. A method for producing hydrogen, wherein heat is exchanged with the liquefied natural gas as a heat source of vaporization to solidify and collect the carbon dioxide gas. 7. A reforming method comprising removing sulfur contained in a liquefied natural gas, mixing steam with the gas from which the sulfur has been removed, and performing a steam reforming reaction with a heat source from a combustion catalyst to reform hydrogen-based gas. A gas is generated, carbon monoxide contained in the reformed gas is reduced, moisture contained in the reformed gas from which carbon monoxide is removed is removed, and hydrogen is selectively produced from the reformed gas from which moisture is removed. To produce hydrogen, supply the remaining gas from which hydrogen has been separated to the combustion catalyst, remove water vapor from the off-gas of the combustion catalyst, and convert the carbon dioxide contained in the off-gas from which the water vapor has been removed into the liquefied natural gas. A method for producing hydrogen, wherein heat is exchanged with the liquefied natural gas as a heat source of vaporization to solidify and collect the carbon dioxide gas.