JP2008247636A - Method and device for hydrogen production and carbon dioxide recovery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the efficiency while suppressing increase in a system cost when hydrogen production and carbon dioxide recovery are simultaneously carried out from a carbon-containing fuel as a source material. <P>SOLUTION: The method of hydrogen production and carbon dioxide recovery for producing hydrogen as well as recovering carbon dioxide from a carbon-containing fuel includes steps of: reforming the carbon-containing fuel to obtain a hydrogen-containing gas containing hydrogen and carbon dioxide; separating the hydrogen-containing gas into a first hydrogen enriched gas and a PSA (pressure swing adsorption) offgas by using a pressure swing adsorption device; separating the PSA offgas into a carbon dioxide enriched gas and a carbon dioxide separation membrane offgas by using a carbon dioxide separation membrane; and separating the carbon dioxide separation membrane offgas into a second hydrogen enriched gas and a hydrogen separation membrane offgas by using a hydrogen separation membrane. A device for carrying out the above method is also disclosed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method and apparatus for producing hydrogen from carbon-containing fuels such as fossil fuels and recovering carbon dioxide.

  Hydrogen is expected as a future energy medium, and active research and development is being carried out in a wide range of technical fields such as production, storage / transport, and utilization. Advantages of using hydrogen as an energy medium include not only high energy utilization efficiency but also only water after combustion.

  Currently, about 80% of primary energy is occupied by fossil fuels such as oil, coal, and natural gas, and even if it gradually decreases due to increased use of renewable energy, the ratio is expected to remain high. Therefore, in the production of hydrogen, it can be said that the importance of the route using fossil fuel as a primary energy source will not be reduced for the time being.

However, when hydrogen is produced using a fuel containing carbon such as fossil fuel, CO ₂ is emitted.

Reduction of CO ₂ emissions is said to be an urgent issue in preventing global warming. Under such circumstances, a technology for separating and recovering CO ₂ produced as a by-product when hydrogen is produced from fossil fuel is important as achieving both CO ₂ emission reduction and early realization of a hydrogen society.

In producing hydrogen using a carbon-containing fuel such as fossil fuel as a raw material, a method for separating CO ₂ has been conventionally known.

Among these methods, the first method is high-purity using a pressure swing adsorption (PSA) device from a mixture of hydrogen, CO, CO ₂ , and methane, which is produced through fossil fuel as a raw material through steam reforming and shift reaction. While obtaining hydrogen, there can be mentioned a method in which CO ₂ is highly purified from offgas containing impurities by a chemical absorption method, and separated and recovered. However, the chemical absorption method using an organic amine solution as an absorbing solution cannot be said to be excellent in terms of energy efficiency of hydrogen production, for example, a great amount of energy is required in the CO ₂ recovery step, that is, the absorbing solution regeneration step.

As a second method, in Patent Document 1, in a process of refining and separating each gas by a two-stage purifier, a CO ₂ concentrator is arranged in the first stage and a gas flow mainly composed of CO ₂ is generated. The high purity hydrogen is obtained by treating the gas with reduced CO ₂ concentration discharged from the CO ₂ concentrator by the PSA arranged in the second stage, and the CO ₂ obtained from each stage is enriched. A method for liquefying and separating CO ₂ from a gas stream is disclosed. However, since CO ₂ is removed from a gas containing a large amount of hydrogen before separating hydrogen, it has to have a very high selectivity as a CO ₂ recovery device and generally has to adopt a method with large energy consumption. Tend to get worse.

As a third method, Patent Documents 2 and 3 disclose a process for producing high-purity hydrogen using a hydrogen purifier such as PSA and recovering CO ₂ after burning off gas containing CO ₂ , hydrogen, and the like. Has been. However, this method burns off the hydrogen purifier off-gas that still contains a large amount of hydrogen, resulting in a decrease in hydrogen yield. In addition, when air is used for combustion, nitrogen is mixed, increasing the load of CO ₂ recovery. To do. On the other hand, pure oxygen can also be used for combustion, but in this case, a great amount of energy is consumed in the production of pure oxygen and the energy efficiency tends to deteriorate.

  As a fourth method, Patent Document 4 discloses a method using a PSA having a serial configuration having a plurality of adsorption towers having different adsorption selectivity. However, this method has a very complicated absorption-regeneration cycle, and it is difficult to suppress an increase in system cost.

As a fifth method, Patent Documents 5 and 6 describe a method of separating hydrogen from a PSA offgas using a membrane and recycling it by recycling it to the PSA inlet. However, in these documents, CO ₂ is only discarded without being recovered, and there is no description about the processing method such as a concentration method.
Special table 2004-519538 gazette JP 2004-292240 A JP 2003-81605 A U.S. Pat. No. 4,913,709 U.S. Pat. No. 4,229,188 U.S. Pat. No. 5,435,836

As described above, there is room for further improvement in the method of co-producing high-purity hydrogen and high-concentration CO ₂ suitable for storage.

  An object of the present invention is to provide a more efficient method and apparatus capable of suppressing an increase in system cost when simultaneously performing hydrogen production and carbon dioxide recovery using a carbon-containing fuel as a raw material.

According to the present invention, a hydrogen production and carbon dioxide recovery method for producing hydrogen from a carbon-containing fuel and recovering carbon dioxide,
A hydrogen-containing gas production process for reforming a carbon-containing fuel to obtain a hydrogen-containing gas containing hydrogen and carbon dioxide;
Using a pressure swing adsorption apparatus, the hydrogen-containing gas is separated into a first hydrogen-enriched gas that is a gas enriched with hydrogen and a PSA offgas that is a gas enriched with components other than hydrogen. PSA process;
Using a carbon dioxide separation membrane, the PSA offgas is converted into a carbon dioxide enriched gas which is a gas enriched with carbon dioxide and a carbon dioxide separation membrane offgas which is a gas enriched with components other than carbon dioxide. A carbon dioxide membrane separation step to separate; and
Using a hydrogen separation membrane, the carbon dioxide separation membrane off-gas is divided into a second hydrogen-enriched gas that is a gas enriched with hydrogen, and a hydrogen separation membrane off-gas that is a gas enriched with components other than hydrogen. A hydrogen production and carbon dioxide recovery method having a hydrogen membrane separation step of separating into two is provided.

  Preferably, the method includes a step of liquefying the carbon dioxide-enriched gas to obtain liquefied carbon dioxide.

  The method preferably includes a step of recycling the second hydrogen-enriched gas to the hydrogen-containing gas production step or the PSA step.

  In the above method, the ratio α of the carbon dioxide permeability coefficient to the hydrogen permeability coefficient of the carbon dioxide separation membrane is preferably 5 or more.

According to the present invention, a hydrogen production and carbon dioxide recovery device for producing hydrogen from a carbon-containing fuel and recovering carbon dioxide,
A hydrogen-containing gas production apparatus for reforming a carbon-containing fuel to obtain a hydrogen-containing gas containing hydrogen and carbon dioxide;
A pressure swing adsorption device for separating the hydrogen-containing gas into a first hydrogen-enriched gas that is a gas enriched with hydrogen and a PSA offgas that is a gas enriched with components other than hydrogen;
A carbon dioxide separation membrane that separates the PSA offgas into a carbon dioxide enriched gas that is a gas enriched with carbon dioxide and a carbon dioxide separation membrane offgas that is a gas enriched with components other than carbon dioxide; and ,
A hydrogen separation membrane that separates the carbon dioxide separation membrane offgas into a second hydrogen enriched gas that is a gas enriched with hydrogen and a hydrogen separation membrane offgas that is a gas enriched with components other than hydrogen; A hydrogen production and carbon dioxide recovery apparatus is provided.

  It is preferable that the apparatus has a carbon dioxide liquefying apparatus that liquefies the carbon dioxide-enriched gas to obtain liquefied carbon dioxide.

  It is preferable that the apparatus has a recycle line for recycling the second hydrogen-enriched gas to the hydrogen-containing gas production process or the PSA process.

  In the above apparatus, the ratio α of the carbon dioxide permeability coefficient to the hydrogen permeability coefficient of the carbon dioxide separation membrane is preferably 5 or more.

  According to the present invention, when hydrogen production and carbon dioxide recovery are simultaneously performed using a carbon-containing fuel as a raw material, an increase in system cost can be suppressed, and a more efficient method and apparatus are provided.

  Unless otherwise specified, in this specification, pressure means absolute pressure, and% relating to gas composition means mol% calculated excluding water vapor.

[Carbon-containing fuel]
In the present invention, a carbon-containing fuel that is a fuel containing carbon is used as a raw material for hydrogen production. As the carbon-containing fuel, carbon can be appropriately selected from substances that can produce a hydrogen-containing gas by reforming.

  Examples of carbon-containing fuels include fossil fuels. The fossil fuels mean fuels that can be produced using fossil resources such as petroleum, coal, and natural gas as raw materials, and can be in any of gaseous, liquid, and solid forms. Specific examples include hydrocarbons such as methane, ethane, propane, natural gas, liquefied petroleum gas, naphtha, gasoline, kerosene, light oil, and heavy oil. Natural gas, liquefied petroleum gas, naphtha, Kerosene is particularly preferably used. Furthermore, as the carbon-containing fuel, oxygen-containing compounds that can be produced from fossil fuels such as methanol, dimethyl ether, and ethanol and contain oxygen atoms in the molecule can be suitably used. Moreover, it can be used even if it was not necessarily manufactured from fossil resources, such as ethanol obtained from biological resources irrespective of hydrocarbons and oxygenated compounds.

[Hydrogen-containing gas production process]
In the hydrogen-containing gas production process, the carbon-containing fuel is reformed to produce a hydrogen-containing gas containing at least hydrogen and carbon dioxide.

  As a reforming reaction method, a known reforming method such as a steam reforming method, an autothermal reforming method, or a partial oxidation method can be adopted, but a method in which nitrogen in the air is not mixed facilitates the subsequent purification process. Therefore, it is preferable. Therefore, a steam reforming method, or an autothermal reforming method or a partial oxidation method using pure oxygen as an oxidizing agent is preferably employed, and a steam reforming method can be particularly preferably employed.

  First, the case where hydrocarbons such as natural gas, liquefied petroleum gas, naphtha and kerosene are used as the carbon-containing fuel will be described. At this time, in the steam reforming method, the hydrocarbons and water are preferably at a temperature of 300 ° C. to 1000 ° C., more preferably 400 ° C. to 900 ° C., preferably 0.1 MPa to 10 MPa, more preferably 0.2 MPa to The reaction is carried out at a pressure of 2 MPa, and it is decomposed into a reformed gas containing hydrogen, carbon monoxide, carbon dioxide, and methane. S / C (ratio of the number of moles of water vapor to the number of moles of carbon atoms in the carbon-containing fuel) is preferably set in the range of 2 to 10, more preferably 2.5 to 7. At this time, it is preferable to perform the reforming reaction at a pressure exceeding the pressure necessary for driving the subsequent stage PSA because it is not necessary to pressurize the reformed gas again. The composition of the reformed gas thus obtained depends on temperature, pressure, etc., and is usually 65 to 75% hydrogen, 5 to 20% carbon monoxide, 5 to 20% carbon dioxide, and 0.5 to 10% methane. However, it is preferable to select conditions so that hydrocarbons having a carbon-carbon bond do not remain as much as possible.

  A catalyst is usually used for the steam reforming reaction. As the catalyst, a known steam reforming catalyst can be used. Examples of the catalyst include metals of Group 8, Group 9 and Group 10 such as nickel, ruthenium, rhodium and platinum. It can be determined as appropriate. The autothermal reforming method and the partial oxidation method can be appropriately selected from known catalysts that can be used for these reforming methods.

The hydrogen production apparatus used in the hydrogen production process has a reformer that performs a reforming reaction. Further, in order to further improve the hydrogen yield, a hydrogen production apparatus in which a shift reactor is arranged at the rear stage of the reformer can be used. In the shift reactor, CO and steam in the reformed gas obtained in the reformer are reacted and converted to CO ₂ and hydrogen. If necessary, steam can be added by providing a steam inlet before the shift reactor. As the catalyst used in the shift reactor, known shift reaction catalysts such as iron / chromium, copper / zinc, and noble metals such as platinum can be used. The reaction temperature of the shift reactor is appropriately set in the range of usually 200 ° C to 500 ° C. Although there is no restriction | limiting in particular in the reaction pressure, It is simple and advantageous to implement near the pressure used by the said reforming reaction.

  On the other hand, when using oxygen-containing compounds such as methanol, dimethyl ether and ethanol as the carbon-containing fuel, the same method as described above can be applied. In particular, when methanol or dimethyl ether is used, a shift reactor is obtained by performing a reforming reaction at a low carbon monoxide equilibrium concentration of 400 ° C. or lower, preferably 350 ° C. or lower, using a copper-zinc catalyst as a catalyst. It is also possible to achieve an excellent hydrogen yield without the presence of hydrogen. In this case, when the steam reforming method is applied, the amount of steam is preferably set in the range of S / C of 1.5 to 4, more preferably 1.5 to 2.5.

  From the hydrogen-containing gas production step, for example, a gas containing 65 to 80% hydrogen, 0.2 to 3% carbon monoxide, 10 to 35% carbon dioxide, and 0 to 10% methane can be obtained.

  When the carbon-containing fuel contains a sulfur content, the carbon-containing fuel can be desulfurized and supplied to the reformer in order to prevent catalyst poisoning due to the sulfur content.

[PSA process]
In the PSA process, the hydrogen-containing gas produced in the hydrogen-containing gas production process is preferably dehydrated and then introduced into a pressure swing adsorption apparatus, that is, a PSA (Pressure Swing Adsorption) apparatus to enrich the hydrogen-enriched gas ( The first hydrogen-enriched gas is separated into a gas enriched with components other than hydrogen (PSA off-gas).

  The PSA method is one of the methods for selectively separating a specific gas from a mixed gas. By introducing the mixed gas into an adsorption tower filled with an adsorbent at a relatively high pressure and adsorbing the specific component to the adsorbent, This is a method in which the adsorbed material adsorbed on the adsorbent (adsorbed gas component) is desorbed by separating the adsorbed gas component and the non-adsorbed gas component, then lowering the pressure of the adsorption system and using a purge gas if necessary. . In general, in general, a PSA apparatus provided with a plurality of towers filled with an adsorbent is used, and in each of the adsorption towers, a series of operations of pressurization, adsorption, depressurization, and washing are repeated, so that the entire apparatus is continuous. Those that enable separation and recovery are used.

  As the adsorbent packed in the PSA tower, a known filler capable of separating hydrogen and components other than hydrogen by adsorption, such as activated carbon and zeolite, can be used as appropriate. The operating pressure of PSA varies depending on the stage of the cycle, but it is preferably in the range of 0.5 MPa to 10 MPa, more preferably 1 MPa to 5 MPa at the time of adsorption operated at the highest pressure.

  In the PSA method, hydrogen normally corresponds to the non-adsorbed gas component and passes through the PSA tower without being adsorbed by the adsorbent. Therefore, the first hydrogen-enriched gas having a pressure close to the PSA apparatus introduction pressure can be obtained. The first hydrogen-enriched gas can be product hydrogen.

  The hydrogen purity of the first hydrogen-enriched gas is preferably 99% or more, more preferably 99.9% or more, and further preferably 99.99% or more. Further, the product hydrogen is preferably hydrogen that can be used in a fuel cell vehicle. In this case, the hydrogen purity is usually preferably 99.99% or more, and the dew point and other requirements for impurities are required to be satisfied. Sometimes. Therefore, if necessary, the first hydrogen-enriched gas can be further subjected to a treatment such as moisture removal. Further, the product hydrogen can be converted into high-pressure hydrogen or liquid hydrogen, which is in a form suitable for filling in a fuel cell vehicle or transporting and storing in a hydrogen station.

The PSA offgas is obtained in a process of desorbing components adsorbed on the adsorption tower, that is, a process of regenerating the adsorption tower. At this time, in order to obtain an off-gas having as high a CO ₂ concentration as possible, the desorption operation can be performed by reducing the pressure of the adsorption tower (pressure less than atmospheric pressure). Washing the adsorption tower with a gas containing a high concentration of carbon dioxide before the desorption step is also effective for increasing the carbon dioxide concentration in the PSA offgas.

  The pressure of the PSA offgas is lower than the pressure for introducing the hydrogen-containing gas into the PSA apparatus, and is preferably 0.01 to 0.5 MPa, more preferably 0.1 to 0.2 MPa. The PSA offgas contains, for example, 20 to 60% hydrogen, 0.5 to 10% carbon monoxide, 30 to 70% carbon dioxide, and 1 to 15% methane.

[CO2 membrane separation process]
In the present invention, carbon dioxide contained in the PSA offgas can be recovered in a form suitable for storage. Therefore, in the carbon dioxide membrane separation step, a membrane that selectively permeates carbon dioxide is used, and PSA off-gas is transformed into a gas enriched with carbon dioxide (carbon dioxide-enriched gas) and the carbon dioxide that has not permeated through the membrane. Separation into carbon dioxide separation membrane off-gas enriched with components other than carbon.

  As described above, since the pressure of the PSA offgas is lowered, it is preferable to increase the pressure of the PSA offgas before being introduced into the carbon dioxide membrane separation step. The pressure after the pressure increase, that is, the pressure on the carbon dioxide separation membrane supply side is preferably set in the range of 0.2 to 2 MPa, more preferably 0.2 to 1 MPa.

As the carbon dioxide separation membrane, a known membrane that can selectively permeate CO ₂ can be appropriately selected and employed. Examples include polymer membranes such as those described in Powel et al., Journal of Membrane Science, 276, 1-49 (2006), FY 2003 carbon dioxide fixation / effective utilization technology countermeasure business, global environment international research, etc. Promotion business, molecular gate function CO ₂ separation membrane basic technology R & D report, dendrimer membrane, amine group-containing membrane, or zeolite membrane as described in WO2006 / 0505051 An inorganic material film etc. can be mentioned.

  From the viewpoint of carbon dioxide separation efficiency, the ratio of the carbon dioxide permeability coefficient to the hydrogen permeability coefficient (permeability coefficient ratio) α of the membrane is preferably 5 or more, more preferably 10 or more, and further preferably 20 or more. preferable.

Here, the CO ₂ and hydrogen permeability coefficient ratio α is defined by the following equation.

  However, the permeation coefficient of each component is Q for the gas permeation rate of each component, p1 for the supply side pressure (partial pressure), p2 for the permeation side pressure (partial pressure), A for the membrane area, and L for the film thickness. Is defined by the following equation.

  No matter what material is used, the shape of the separation membrane is not particularly limited, and any shape such as a plate shape, a cylindrical shape, or a hollow fiber shape can be selected.

  The pressure on the permeate side in the carbon dioxide membrane separation step is set to be lower than the supply side pressure, and can be set to atmospheric pressure or lower, preferably in the range of 0 MPa to 0.5 MPa, more preferably 0.001 to 0.2 MPa. Selected.

  The temperature at which the membrane separation is performed is set to a temperature suitable for the membrane material to be used.

In this way, carbon dioxide can be recovered as the carbon dioxide-enriched gas. The recovered carbon dioxide-enriched gas can be stored by being injected into the ground as it is, but is preferably processed in a CO ₂ liquefaction step to produce liquefied CO ₂ . Therefore, it is preferable to increase the CO ₂ concentration of the carbon dioxide-enriched gas so as to facilitate the smooth operation of the CO ₂ liquefaction process, and the concentration is preferably 70% or more, more preferably 80% or more, and still more preferably 90%. % Or more. When the CO ₂ concentration is 70% or more, the energy required for the liquefaction step can be reduced, and the ratio of recovered liquefied CO ₂ can be increased.

  The components other than carbon dioxide contained in the carbon dioxide-enriched gas are, for example, about 0.5 to 20% hydrogen, 0.01 to 5% carbon monoxide, and about 0.01 to 5% methane. The carbon dioxide separation membrane off-gas includes, for example, hydrogen 40 to 80%, carbon dioxide 5 to 50%, carbon monoxide 0 to 20%, and methane 0 to 20%.

As a CO ₂ liquefaction method, a known CO ₂ liquefaction method such as a method using the Joule-Thompson effect or a method of cooling by external cold heat while compressing can be appropriately employed. As the carbon dioxide liquefying apparatus, a known apparatus capable of liquefying carbon dioxide by these known CO ₂ liquefaction methods can be appropriately selected and used. The liquefied CO ₂ obtained in this way can be sequestered in the ground or sea after being transported to a storage location by an appropriate method such as land transport, sea transport or pipeline, or it has a high CO ₂ concentration and is therefore chemically It can also be used as various raw materials such as product synthesis. Since the off-gas (gas that has not been liquefied) obtained from the CO ₂ liquefaction step still contains combustible gases such as hydrogen and methane, it can be sent to the reformer burner and used as fuel.

[Hydrogen membrane separation process]
In the hydrogen membrane separation step, a hydrogen-enriched gas (second hydrogen-enriched gas) is permeated through this membrane using a membrane that selectively permeates hydrogen from the carbon dioxide separation membrane off-gas. It is separated into a gas enriched with components other than hydrogen (hydrogen separation membrane off-gas). Since the carbon dioxide separation membrane off-gas is a gas that has not permeated the carbon dioxide separation membrane, the pressure drop in the carbon dioxide membrane separation step is small. Therefore, it is not necessary to increase the pressure again when introducing the carbon dioxide separation membrane off-gas into the hydrogen membrane separation step, so that hydrogen can be concentrated without consuming excess energy. That is, further effective use of hydrogen can be achieved while suppressing energy loss, and the hydrogen yield can be improved. The supply side pressure in the hydrogen membrane separation step can be set to the same level as the supply side pressure in the carbon dioxide membrane separation step.

  As the hydrogen separation membrane used in the hydrogen membrane separation step, a known membrane capable of selectively permeating hydrogen can be appropriately selected and employed. Examples of the hydrogen separation membrane include metal membranes such as palladium, polymer membranes such as polyimide, porous membranes such as porous silica, zeolite, and porous carbon. From the viewpoints of ease of operation and cost, a polymer film is preferably used.

For the hydrogen separation membrane, the CO ₂ and hydrogen permeability coefficient ratio α is preferably 0 to 0.5, more preferably 0 to 0.3, and even more preferably 0 to 0.15.

  No matter what material is used, the shape of the separation membrane is not particularly limited, and any shape such as a plate shape, a cylindrical shape, or a hollow fiber shape can be selected.

  The pressure on the permeate side in the hydrogen membrane separation step is set to a pressure lower than the supply side pressure, and can be set to atmospheric pressure or lower, preferably 0 MPa to 0.5 MPa, more preferably 0.001 to 0.1 MPa. Is done.

  The temperature at which the membrane separation is performed is set to a temperature suitable for the membrane material to be used. For example, about 250 to 500 ° C. for a palladium membrane and about room temperature to about 150 ° C. for a polyimide membrane.

  Examples of the second hydrogen-enriched gas include 50 to 97% hydrogen, 3 to 40% carbon dioxide, 0 to 10% carbon monoxide, and 0 to 10% methane. On the other hand, the hydrogen separation membrane off-gas includes, for example, 1-30% hydrogen, 30-60% carbon dioxide, 1-20% carbon monoxide, and 1-20% methane.

  The hydrogen separation membrane off-gas can be supplied to a reformer burner in the hydrogen production process and used as a fuel.

  On the other hand, since the second hydrogen-enriched gas has a relatively high hydrogen concentration, it can be recycled to the upstream side of the PSA process after being appropriately pressurized to recover it. For this purpose, a recycling line for recycling the second hydrogen-enriched gas (permeation side outlet gas of the hydrogen separation membrane) to the inlet of the PSA apparatus can be used. This can improve the yield of hydrogen. Moreover, if the second hydrogen-enriched gas is circulated upstream of the hydrogen production process, methane in the second hydrogen-enriched gas can be converted to hydrogen. For this purpose, it is possible to use a recycling line for recycling the second hydrogen-enriched gas to the inlet of the hydrogen production apparatus, in particular to the inlet of the reformer.

According to the present invention, there is no need to increase the pressure again when obtaining the second hydrogen-enriched gas. This is because the increased pressure is effectively utilized when CO ₂ is separated by the aforementioned CO ₂ separation membrane. For this reason, relatively high-purity hydrogen can be obtained with little energy consumption. Thus, the use of the second hydrogen-enriched gas having a relatively high hydrogen concentration is not limited to recycling to the hydrogen-containing gas production process and the PSA process, and can be appropriately used as a hydrogen source. For example, the second hydrogen-enriched gas can be effectively used by using it as a hydrogen source in another plant. Examples of such a plant include a plant that performs a hydrogenation reaction or hydrodesulfurization reaction of an unsaturated organic compound such as an olefin, a ketone, an aldehyde, or a nitro group.

〔process〕
Hereinafter, processes suitable for carrying out the present invention will be described with reference to the drawings, but the present invention is not limited thereto.

  As shown in FIG. 1, the hydrogen production apparatus 1 has a reformer 1-1 and a shift reactor 1-2 connected downstream of the reformer. The reformer is provided with a reforming reaction tube 1-1a and a burner 1-1b for heating it from the outside. Carbon-containing fuel is supplied from a line 100 to a reformer, particularly a reforming reaction tube. Water vapor, oxygen and the like necessary for the reforming reaction are also appropriately supplied to the reformer (not shown). When the carbon-containing fuel is liquid or solid, the carbon-containing fuel can be appropriately vaporized in advance. If necessary, the carbon-containing fuel can be supplied to the reformer after being desulfurized by a desulfurizer (not shown).

The carbon-containing fuel is reformed inside the reforming reaction tube, and the reformed gas is discharged from the reformer (line 101). In the shift reactor, CO and water vapor in the reformed gas are converted into CO ₂ and hydrogen.

  The hydrogen-containing gas (line 102) obtained from the hydrogen production apparatus is supplied to the PSA apparatus 2 via the line 103. Specifically, the hydrogen-containing gas is put into a PSA tower that is performing an adsorption process, components other than hydrogen contained in the hydrogen-containing gas are adsorbed by the adsorbent, and the first hydrogen-enriched gas is taken out as product hydrogen. (Line 104). On the other hand, the PSA off-gas is discharged from the PSA tower performing the regeneration process (line 105), and after being pressurized by the booster 3, is supplied to the carbon dioxide separation membrane 4 (line 106).

  Carbon dioxide-enriched gas (line 108) is obtained as gas that has permeated the carbon dioxide separation membrane, and this is pressurized by the booster 6 and supplied to the carbon dioxide liquefier 7 (line 109). The carbon dioxide separation membrane off-gas (line 107) discharged without passing through the carbon dioxide separation membrane is supplied to the hydrogen separation membrane 5. A second hydrogen-enriched gas is obtained as the gas that has permeated through the hydrogen separation membrane, and is recycled to the PSA device via the line 111, the booster 8, and the line 112. The hydrogen separation membrane off-gas (line 121) discharged without passing through the hydrogen separation membrane is supplied as fuel to the burner 1-1b of the reformer via the line 122.

  Product liquefied carbon dioxide is recovered from the carbon dioxide liquefier (line 110). The non-liquefied gas (line 123) discharged from the carbon dioxide liquefier joins the hydrogen separation membrane off-gas and is supplied from the line 122 to the burner 1-1b.

  The combustible component in the gas supplied from the line 122 is burned by the burner 1-1b, and the combustion gas is exhausted from the line 124. This combustion heat is used to heat the reforming reaction tube.

  ADVANTAGE OF THE INVENTION According to this invention, when manufacturing carbon dioxide of the form suitable for storage using carbon-containing fuels, such as fossil fuels, as a raw material in parallel with manufacture of high purity hydrogen, energy consumption can be suppressed. In addition, the hydrogen yield can be improved. In addition, hydrogen production and carbon dioxide recovery can be performed with a relatively simple apparatus, and an increase in system cost can be suppressed. Accordingly, the present invention contributes to the realization of a hydrogen society and the prevention of global warming.

  According to the present invention, for example, high-purity hydrogen having a purity that can be supplied as fuel for a fuel cell vehicle can be obtained. On the other hand, carbon dioxide can have a concentration suitable for recovery in the form of liquefied carbon dioxide, which is a form suitable for underground storage and ocean storage.

[Example 1]
A thermal mass balance was taken for the process having the configuration shown in FIG. Naphtha 215 kg / h (line 100) and steam 946 kg / h (not shown) are supplied to a reformer 1-1 which is charged with a Ni-based catalyst and performs a steam reforming reaction at an outlet temperature of 830 ° C. and a pressure of 2 MPa. The total flow rate was 54.2 kmol / h, the CO ₂ concentration was 20.5%, and the hydrogen concentration was 72. 2 by the shift reactor 1-2 in which the Fe—Cr catalyst was charged and the shift reaction was performed at an inlet temperature of 360 ° C. and an outlet temperature of 425 ° C. A mixed gas (line 102) of 4% and pressure 2 MPa is obtained. This is dehydrated by a dehydrator (not shown), and then high-purity hydrogen having a purity of 99.99% is obtained at a flow rate of 35.8 kmol / h by the PSA apparatus 2 (line 104). On the other hand, a PSA off-gas mixed gas (line 105) having a CO ₂ concentration of 52% and a hydrogen concentration of 30% is pressurized to 1 MPa by the compressor 3 and is provided with a membrane having a CO ₂ / hydrogen permeability coefficient ratio α of 30. ₂ Introduce into the separation membrane 4. The permeate side gas (line 108) of the CO ₂ separation membrane has a CO ₂ concentration of 94%, which is pressurized to about 8 MPa by the compressor 6 and then sent to the CO ₂ liquefier 7 to be 8.1 kmol. A liquefied CO ₂ stream of / h (line 110) is obtained. CO ₂ non-permeate side gas separation membrane (line 107) is introduced into the hydrogen separation membrane 5 which permeability coefficient ratio of CO ₂ / hydrogen α is provided with a polyimide film of 0.11 at unchanged pressure. A gas having a hydrogen concentration of 91% and a pressure of 0.1 MPa (line 111) is obtained at 3.5 kmol / h on the permeate side of the hydrogen separation membrane, and this is recycled upstream of the PSA device 2 via the compressor 8. On the other hand, the gas flow (line 122), which is a combination of the non-permeate side gas (line 121) of the hydrogen separation membrane and the off gas (line 123) of the CO ₂ liquefier, is sent to the reformer burner 1-1b and reformer fuel. Used as The energy consumed by the compressor of this process is 12.0 kW / kmol-recovered CO ₂ , and CO ₂ as liquefied CO _{2 based} on the amount of CO ₂ contained in the shift reactor outlet gas (line 102). The carbon recovery rate is 71%.

  Table 1 shows the permeability coefficient ratio α of the carbon dioxide separation membrane, the high-purity hydrogen recovery amount, the carbon dioxide recovery amount, and the energy consumption (total) of the compressor per 1 kmol of the recovered liquefied carbon dioxide. Table 4 shows the thermal mass balance.

[Examples 2 to 4]
The heat and mass balance was taken in the same manner as in Example 1 except that the membrane (permeation coefficient ratio α) used for the CO ₂ separation membrane device 4 was changed. Table 1 shows the permeability coefficient ratio α of the carbon dioxide separation membrane, the amount of high purity hydrogen recovered, the amount of carbon dioxide recovered, and the energy consumption (total) of the compressor.

[Comparative Example 1]
A thermal mass balance was obtained in the same manner as in Example 1 except that the PSA offgas (line 105) was directly compressed and liquefied by the CO ₂ liquefier 7 without using the hydrogen separation membrane and the CO ₂ separation membrane. As a result, the energy consumed by the compressor was 41 kW / kmol-CO ₂ , and the CO ₂ recovery rate as liquefied CO ₂ was only 35%.

[Comparative Example 2]
Without using the CO ₂ separation membrane, the pressurized PSA off-gas (line 106) was supplied to the hydrogen separation membrane 5, and the non-permeate side gas (line 121) of the hydrogen separation membrane was directly compressed and liquefied by the CO ₂ liquefier 7. (The hydrogen permeation membrane permeation gas, which is the second hydrogen-enriched gas, is pressurized and recycled to the PSA device). Except for this, the heat and mass balance was obtained in the same manner as in Example 1. As a result, the energy consumed by the compressor was 33 kW / kmol-CO ₂ , and the CO ₂ recovery rate as liquefied CO ₂ was only 39%.

[Comparative Examples 3 to 6]
Was first introduced into the CO ₂ separation membrane in Examples 1 to 4 In PSA offgas, subsequently CO ₂ separation membrane off-gas introduced into the hydrogen separation membrane, permeate gas of the hydrogen separation membrane was recycled as PSA material. Here, no hydrogen separation membrane was used, and therefore, the permeation gas of the hydrogen separation membrane was not recycled as a PSA raw material. A CO ₂ separation membrane off gas (line 107) was supplied as fuel to the burner 1-1b. Others were carried out in the same manner as in Example 1. At this time, the permeability coefficient ratio α of the CO ₂ separation membrane was changed as shown in Table 2 to obtain Comparative Examples 3 to 6. The results are shown in Table 2. It turns out that Comparative Examples 3-6 is inferior in hydrogen yield compared with Examples 1-4.

[Examples 5 to 8]
Instead of recycling the permeated gas of the hydrogen separation membrane upstream of the PSA apparatus, a thermal mass balance was obtained in the same manner as in Example 1 except that it was taken out for effective use. At this time, the permeability coefficient ratio α of the CO ₂ separation membrane was changed as shown in Table 3 to obtain Examples 5 to 8. The results are shown in Table 3.

  The gas having the composition of the second hydrogen-enriched gas obtained in Examples 5 to 8 was bubbled into a solution of dimethyl itaconate containing a methanol solvent and a Pt / C catalyst (a catalyst having platinum supported on carbon particles). However, production of dimethyl methyl succinate was confirmed and it was found that the second hydrogen-enriched gas could be used for olefin hydrogenation.

  The present invention is suitably used for producing high-purity hydrogen and recovering high-concentration carbon dioxide. The produced hydrogen is suitable as a fuel for a fuel cell or the like, and the recovered carbon dioxide is suitable for storage in the ground or in the sea. In addition, relatively high purity hydrogen can be obtained as a by-product, which can be used for synthesis reactions such as hydrogenation of organic compounds.

It is a flowchart for demonstrating the outline | summary of the example of the apparatus which can implement this invention.

Explanation of symbols

1: Hydrogen production apparatus 1-1: Reformer 1-1a: Reformation reaction tube 1-1b: Burner 1-2: Shift reactor 2: PSA apparatus 3: Booster 4: Carbon dioxide separation membrane 5: Hydrogen separation Membrane 6: Booster 7: Carbon dioxide liquefier 8: Booster

Claims (8)

A hydrogen production and carbon dioxide recovery method for producing hydrogen from a carbon-containing fuel and collecting carbon dioxide,
A hydrogen-containing gas production process for reforming a carbon-containing fuel to obtain a hydrogen-containing gas containing hydrogen and carbon dioxide;
Using a pressure swing adsorption apparatus, the hydrogen-containing gas is separated into a first hydrogen-enriched gas that is a gas enriched with hydrogen and a PSA offgas that is a gas enriched with components other than hydrogen. PSA process;
Using a carbon dioxide separation membrane, the PSA offgas is converted into a carbon dioxide enriched gas which is a gas enriched with carbon dioxide and a carbon dioxide separation membrane offgas which is a gas enriched with components other than carbon dioxide. A carbon dioxide membrane separation step to separate; and
Using a hydrogen separation membrane, the carbon dioxide separation membrane off-gas is divided into a second hydrogen-enriched gas that is a gas enriched with hydrogen, and a hydrogen separation membrane off-gas that is a gas enriched with components other than hydrogen. A hydrogen production and carbon dioxide recovery method comprising a hydrogen membrane separation step for separating the carbon dioxide into two.   The method according to claim 1, further comprising liquefying the carbon dioxide-enriched gas to obtain liquefied carbon dioxide.   The method according to claim 1, further comprising a step of recycling the second hydrogen-enriched gas to the hydrogen-containing gas production step or the PSA step.   The method according to any one of claims 1 to 3, wherein a ratio α of a carbon dioxide permeability coefficient to a hydrogen permeability coefficient of the carbon dioxide separation membrane is 5 or more. A hydrogen production and carbon dioxide recovery device for producing hydrogen from carbon-containing fuel and recovering carbon dioxide,
A hydrogen-containing gas production apparatus for reforming a carbon-containing fuel to obtain a hydrogen-containing gas containing hydrogen and carbon dioxide;
A pressure swing adsorption device for separating the hydrogen-containing gas into a first hydrogen-enriched gas that is a gas enriched with hydrogen and a PSA offgas that is a gas enriched with components other than hydrogen;
A carbon dioxide separation membrane that separates the PSA offgas into a carbon dioxide enriched gas that is a gas enriched with carbon dioxide and a carbon dioxide separation membrane offgas that is a gas enriched with components other than carbon dioxide; and ,
A hydrogen separation membrane that separates the carbon dioxide separation membrane offgas into a second hydrogen enriched gas that is a gas enriched with hydrogen and a hydrogen separation membrane offgas that is a gas enriched with components other than hydrogen; Having hydrogen production and carbon dioxide recovery equipment.   The apparatus according to claim 5, further comprising a carbon dioxide liquefying apparatus that liquefies the carbon dioxide-enriched gas to obtain liquefied carbon dioxide.   The method according to claim 5 or 6, further comprising a recycle line for recycling the second hydrogen-enriched gas to the hydrogen-containing gas production process or the PSA process.   The device according to any one of claims 5 to 7, wherein a ratio α of a carbon dioxide permeability coefficient to a hydrogen permeability coefficient of the carbon dioxide separation membrane is 5 or more.

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