JP2015116545A - Hydrogen gas treatment equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide hydrogen gas treatment equipment capable of lowering treatment temperature of hydrogen gas with respect to mixed gas containing hydrogen gas and oxygen gas, and capable of improving treatment efficiency at the treatment temperature.SOLUTION: Hydrogen gas treatment equipment for treating hydrogen gas from mixed gas containing hydrogen gas and oxygen gas, includes: a hydrogen separator which is partitioned into a mixed gas chamber and a permeated hydrogen chamber by a hydrogen permeation membrane; a mixed gas temporary storage container which is connected to the mixed gas chamber via a mixed gas supply pipe line and a deoxidation mixed gas recovery pipeline; a condenser arranged on the way of the deoxidation mixed gas recovery pipeline; an oxidative gas supply mechanism connected to the permeated hydrogen chamber via the oxidative gas supply pipeline; and a water vapor exhaust pipe line connected to the permeated hydrogen chamber. Therein, the hydrogen permeable membrane is formed of porous layers of a catalytic metal which facilitates water vapor conversion reaction of hydrogen and oxygen on both surfaces of a dense membrane of a hydrogen permeable alloy and, in the hydrogen separator, a heating mechanism for continuously heating the hydrogen separator is not disposed.

Description

  The present invention relates to a technique for processing hydrogen gas from a mixed gas containing hydrogen gas, and more particularly to a hydrogen gas processing apparatus that safely processes hydrogen gas using a water vapor conversion reaction on a hydrogen permeable membrane.

  Hydrogen gas (hereinafter sometimes simply referred to as hydrogen) is used in a wide range of technical fields such as petroleum refining, chemical production and food processing. In recent years, it has attracted attention as a clean energy source that does not emit greenhouse gases such as carbon dioxide even when burned.

Since hydrogen gas hardly exists in the atmosphere (below 1 ppm), it is usually produced by steam reforming of hydrocarbons and subsequent separation and purification. Typical hydrogen separation / purification methods include a pressure fluctuation adsorption method and a membrane separation method.

  The pressure fluctuation adsorption method has a merit that high-purity hydrogen can be purified by using a plurality of adsorption towers, but also has a demerit that the entire system is easily increased in size and complexity. The membrane separation method has an advantage that the system can be reduced in size and simplified by using a hydrogen permeable membrane (for example, a palladium (Pd) alloy membrane). However, if the operating temperature is lowered in the presence of hydrogen around the hydrogen permeable membrane, there is a demerit that the hydrogen permeable membrane is likely to deteriorate (so-called hydrogen embrittlement). In addition, the performance and efficiency of the membrane separation method largely depend on the performance of the hydrogen permeable membrane to be used, but the hydrogen permeable membrane having high hydrogen permeable performance has a problem that the production cost is high (for example, the production yield is low). there were.

  Various research and development have been conducted to solve the problems in the membrane separation system. For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2003-112905) includes a water evaporator that generates steam and a reformer that generates a hydrogen-rich reformed gas by a reforming reaction between fuel and water. The fuel reformer is a membrane reactor comprising a reforming layer and a pure hydrogen layer adjacent to each other through at least a hydrogen separation alloy membrane, and the hydrogen is added to the reforming layer and the pure hydrogen layer when the system is stopped. Only the water vapor generated by the water evaporator is supplied so as to maintain a predetermined temperature at which hydrogen embrittlement of the separation alloy film can be avoided, and it is necessary to purge the residual gas in the reformed layer and the pure hydrogen layer. A fuel reforming system is disclosed in which air is supplied to the reformer after the amount of water vapor is supplied. According to Patent Document 1, when a residual gas such as hydrogen is present in the fuel reforming system, the hydrogen separation alloy membrane is maintained at a temperature that does not cause hydrogen embrittlement, so that hydrogen embrittlement of the hydrogen separation alloy membrane can be prevented. It is supposed to be possible.

  Patent Document 2 (Japanese Patent Laid-Open No. 2008-289948) discloses a step of forming a Pd film or a Pd alloy film on a substrate by a sputtering method and a substrate on which the Pd film or the Pd alloy film is formed in a vacuum or inactive. Disclosed is a method for producing a Pd-based hydrogen-permeable metal film, which includes a step of heat-treating at a temperature of 400 to 700 ° C. in a gas atmosphere and a step of peeling the heat-treated Pd film or Pd alloy film from the substrate. ing. According to Patent Document 2, after forming a uniform thin hydrogen-permeable metal film without pinholes on a substrate by a sputtering method, a predetermined heat treatment is performed to facilitate peeling of the hydrogen-permeable metal film from the substrate, It is said that even if the film thickness is extremely thin (for example, about 0.1 to 5 μm), a hydrogen-permeable metal film that is free from cracks, breakage, and deformation (for example, curl) can be stably produced.

  On the other hand, as one application example of a technique for separating hydrogen gas from a hydrogen mixed gas, there is a technique for separating the hydrogen gas contained in the mixed gas and then safely processing the hydrogen gas to prevent ignition and explosion. For example, in Patent Document 3 (Japanese Patent Publication No. 59-12332), a hydrogen permeable film such as a palladium alloy that can be heated appropriately is provided in an exhaust path capable of exhausting hydrogen, and is divided into an exhausted chamber and an exhaust chamber. Oxygen is introduced into the exhaust chamber to maintain the hydrogen permeable membrane surface in an oxygen atmosphere, and hydrogen from the exhausted chamber permeates the hydrogen permeable membrane and then reacts with oxygen on the hydrogen permeable membrane surface to generate water vapor. A method for exhausting hydrogen to be generated and an exhaust device for the method are disclosed. According to Patent Document 3, a hydrogen exhaust method and exhaust apparatus applied to a hydrogen plasma apparatus, a hydrogen ion source, etc., and exhaust hot hydrogen (for example, high energy hydrogen ions, hydrogen atoms, etc.) with a large displacement. It is supposed to be possible.

JP 2003-112905 A JP 2008-289948 A Japanese Patent Publication No.59-12332

  Since hydrogen gas is highly flammable (minimum ignition energy 0.019 mJ) and has a wide explosion range (4 to 75% by volume when mixed with air), the technology for separating and treating the hydrogen gas contained in the mixed gas is safe. This is a very important technology. The technique described in Patent Document 3 is considered to be one technique that provides the guideline.

  However, the technique described in Patent Document 3 is most suitable to operate by heating the hydrogen permeable membrane to around 500 ° C. using a heating device from the viewpoint of hydrogen permeability of the hydrogen permeable membrane, water vapor conversion reaction, and the like. It is said that there is. On the other hand, since the temperature of 500 ° C is close to the ignition point of hydrogen gas, if the technique described in Patent Document 3 is applied to the separation and treatment of hydrogen gas in the mixed gas, careful operation and sufficient safety measures will be taken. Cost is considered necessary.

  Furthermore, when oxygen gas is contained in the mixed gas in addition to hydrogen gas, it is safe for the hydrogen / oxygen mixed gas to contact a high-temperature metal film at around 500 ° C. as in the technique described in Patent Document 3. It is desirable to avoid it from the viewpoint of safety measures cost. In other words, in order to safely and reliably process a mixed gas containing hydrogen gas and oxygen gas, it is desirable to simultaneously satisfy a reduction in the processing temperature of hydrogen gas and an improvement in processing efficiency at that temperature.

  Accordingly, an object of the present invention is to provide a hydrogen gas processing apparatus that can reduce the processing temperature of hydrogen gas for a mixed gas containing hydrogen gas and oxygen gas and that can improve the processing efficiency at that temperature. It is to provide.

One aspect of the present invention is a hydrogen gas processing apparatus for processing hydrogen gas from a mixed gas containing hydrogen gas and oxygen gas in order to achieve the above object,
A hydrogen separator partitioned into a mixed gas chamber and a permeated hydrogen chamber by a hydrogen permeable membrane;
A mixed gas temporary storage container connected to the mixed gas chamber via a mixed gas supply pipe and a deoxygenated mixed gas recovery pipe;
A condenser disposed in the middle of the deoxygenated mixed gas recovery pipe;
An oxidizing gas supply mechanism connected to the permeated hydrogen chamber via an oxidizing gas supply pipe;
A water vapor exhaust pipe connected to the permeate hydrogen chamber;
In the hydrogen permeable membrane, a porous layer of a catalytic metal that promotes a water vapor conversion reaction between hydrogen and oxygen is formed on both surfaces of the dense membrane of the hydrogen permeable alloy.
The hydrogen separator is not provided with a heating mechanism for continuously heating the hydrogen separator. A hydrogen gas processing apparatus is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the hydrogen gas processing apparatus which lowered the processing temperature of hydrogen gas with respect to the mixed gas containing hydrogen gas and oxygen gas, and improved the processing efficiency in the temperature can be provided. As a result, the mixed gas containing hydrogen gas and oxygen gas can be processed more safely and reliably. In addition, since the hydrogen gas treatment temperature can be lowered, there is no need for a heater for heating and continuously heating the hydrogen permeable membrane, and the running cost required for the operation of the heater can be reduced. There is also.

It is a systematic diagram which shows an example of the principal part of the hydrogen gas processing apparatus which concerns on 1st Embodiment of this invention. 6 is a graph showing the relationship between the ratio of the amount of permeated hydrogen gas to the amount of hydrogen gas supplied, “permeated hydrogen gas amount / the amount of hydrogen gas supplied”, and the operating time. It is a systematic diagram which shows an example of the principal part of the hydrogen gas processing apparatus which concerns on 2nd Embodiment of this invention.

In the hydrogen gas processing apparatus according to the present invention described above, the present invention can be improved or changed as follows.
(I) The catalyst metal porous layer is a porous layer mainly composed of particles of the catalyst metal having an average particle diameter of 10 nm to 50 nm.
(Ii) The hydrogen permeable alloy dense membrane has a thickness of 15 μm or more and 50 μm or less, and the catalytic metal porous layer has an average thickness of 20 nm or more and less than 100 nm.
(Iii) A second condenser is further disposed downstream of the water vapor exhaust pipe.
(Iv) An exhaust pump is further disposed downstream of the second condenser.
(V) The hydrogen permeable alloy is a palladium (Pd) alloy, and the catalytic metals are rubidium (Rb), ruthenium (Ru), rhodium (Rh), palladium, rhenium (Re), iridium (Ir), and platinum. (Pt).
(Vi) A circulation pump is further provided in the middle of the mixed gas supply pipe or the deoxygenated mixed gas recovery pipe.

(Basic idea of the present invention)
The inventors of the present invention are diligent about a technique for lowering the treatment temperature of hydrogen gas and improving the treatment efficiency at the temperature in a technique for separating and treating the hydrogen gas from a mixed gas containing hydrogen gas using a hydrogen permeable membrane. I did research. As a result, a hydrogen permeable membrane in which a porous layer of a catalytic metal that promotes a water vapor conversion reaction between hydrogen and oxygen is formed on both surfaces of a dense membrane of a hydrogen permeable alloy as a hydrogen permeable membrane. It was also found that the water vapor conversion reaction occurs actively from a much lower temperature (for example, room temperature). In addition, the thickness of the catalytic metal porous layer (related to the surface area of the catalytic metal and affects the efficiency of the water vapor conversion reaction) and the thickness of the hydrogen permeable alloy dense membrane (related to the heat capacity and hydrogen permeation flux) It was found that the entire hydrogen permeable membrane can be heated to and maintained at a temperature suitable for hydrogen treatment (for example, 200 ° C. or more and 400 ° C. or less) by the reaction heat (exotherm) of the steam conversion reaction by adjusting the balance. The present invention has been completed based on these findings.

  Hereinafter, embodiments of the present invention will be described. However, the present invention is not limited to the embodiments described here, and can be appropriately combined and improved without departing from the technical idea of the present invention.

(First embodiment)
FIG. 1 is a system schematic diagram showing an example of a main part of the hydrogen gas processing apparatus according to the first embodiment of the present invention. The hydrogen gas processing apparatus 100 according to the present embodiment basically uses a water vapor conversion reaction between hydrogen and oxygen on both surfaces of the hydrogen permeable membrane 11 built in the hydrogen separator 10 to provide a mixed gas. It is an apparatus for processing the hydrogen gas inside.

  As shown in FIG. 1, the interior of the hydrogen separator 10 is partitioned into a mixed gas chamber 12 and a permeated hydrogen chamber 13 by a hydrogen permeable membrane 11, and the hydrogen permeable membrane 11 is a hydrogen permeable alloy dense membrane. A catalytic metal porous layer 11b that promotes a water vapor conversion reaction between hydrogen and oxygen is formed on both surfaces of 11a. As described above, in the present invention, the temperature of the hydrogen permeable membrane 11 is promptly raised to a temperature suitable for hydrogen treatment (for example, 200 ° C. or more and 400 ° C. or less) by the reaction heat (exotherm) of the active steam conversion reaction. can do. As a result, the hydrogen gas treatment apparatus of the present invention is characterized in that no heating mechanism for continuing to heat the hydrogen separator 10 is provided.

  A mixed gas temporary storage container 20 is connected to the mixed gas chamber 12 of the hydrogen separator 10 through a mixed gas supply pipe 21 and a deoxygenated mixed gas recovery pipe 22. A condenser 30 (refrigerator 31, refrigerant pipe 32, condensed water container 33) for separating water vapor generated by the water vapor conversion reaction in the mixed gas chamber 12 is connected in the middle of the deoxygenated mixed gas recovery pipe 22. ing. Further, although not essential, it is preferable that a circulation pump 23 is disposed in the middle of the mixed gas supply pipe 21 or the deoxygenated mixed gas recovery pipe 22.

  In the permeated hydrogen chamber 13 of the hydrogen separator 10, there is an oxidizing gas supply mechanism 40 that supplies hydrogen permeated through the hydrogen permeable membrane 11 and an oxidizing gas (for example, oxygen gas, air) for causing a water vapor conversion reaction. A steam exhaust pipe 16 for discharging water vapor generated by the water vapor conversion reaction is connected while being connected via an oxidizing gas supply pipe 41.

  Next, while explaining the operation method of the hydrogen gas processing apparatus 100, each configuration of the hydrogen gas processing apparatus 100 will be described in more detail.

  First, a mixed gas (including hydrogen gas and oxygen gas) discharged from an external device (not shown) is stored in the mixed gas temporary storage container 20. In order to start processing the mixed gas in the mixed gas temporary storage container 20, the circulation pump 23 and the refrigerator 31 are started, and the valve 50 is opened. By driving the circulation pump 23, the mixed gas is supplied to the mixed gas chamber 12 of the hydrogen separator 10 through the mixed gas supply pipe 21. The mixed gas supplied to the mixed gas chamber 12 comes into contact with the catalytic metal porous layer 11b of the hydrogen permeable membrane 11, and a water vapor conversion reaction occurs to generate water vapor.

  At this time, the heat generated by the water vapor conversion reaction heats the hydrogen permeable membrane 11 itself. As the temperature of the hydrogen permeable membrane 11 rises, the hydrogen permeable capacity of the hydrogen permeable alloy dense membrane 11a improves, and hydrogen surplus in the water vapor conversion reaction in the mixed gas chamber 12 permeates the hydrogen permeable alloy dense membrane 11a. To do. In order to monitor the temperature of the hydrogen permeable membrane 11, a thermometer 14 is preferably disposed on the hydrogen permeable membrane 11 (particularly the hydrogen permeable alloy dense membrane 11a).

  On the other hand, the water vapor generated by the water vapor conversion reaction in the mixed gas chamber 12 is guided to the condenser 30 through the deoxygenated mixed gas recovery pipe 22. In the condenser 30, the refrigerant cooled by the refrigerator 31 circulates in the refrigerant pipe 32, and the introduced water vapor exchanges heat with the refrigerant to become condensed water 34 and accumulates in the condensed water container 33.

  A hydrogen concentration meter 35 is preferably connected to the condensed water container 33. Thereby, it can be detected whether or not hydrogen gas is mixed in the gas recovered in the condensed water container 33 through the deoxygenated mixed gas recovery pipe 22. When mixing of hydrogen gas is detected, the valve 51 is opened, and the mixed gas from which water vapor has been removed (deoxygenated mixed gas) is returned to the mixed gas temporary storage container 20. When hydrogen gas is not mixed in the gas collected in the condensed water container 33, the valve 52 is opened and the deoxygenated mixed gas is discharged from the deoxygenated mixed gas exhaust pipe.

  The condensed water container 33 is preferably connected to a pressure gauge 37 via a pressure gauge pipe 38 and a valve 53. When the amount of the condensed water 34 in the condensed water container 33 increases (when the water level of the condensed water 34 rises), the volume of the gas phase portion in the condensed water container 33 decreases and the internal pressure rises. Thereby, the amount of the condensed water 34 in the condensed water container 33 can be detected. When the internal pressure of the condensed water container 33 rises to the set pressure, the valve 54 is opened and the condensed water 34 is discharged from the drain pipe 39.

  As described above, the oxidizing gas supply mechanism 40 is connected to the permeated hydrogen chamber 13 of the hydrogen separator 10 via the oxidizing gas supply pipe 41 and the valve 55. The hydrogen that has permeated through the hydrogen permeable membrane 11 (hydrogen permeable alloy dense membrane 11a) is vaporized on the catalytic metal porous layer 11b together with the oxidizing gas (for example, oxygen gas, air) supplied from the oxidizing gas supply mechanism 40. A conversion reaction takes place and is converted to water vapor. The reaction heat (exotherm) at this time maintains the temperature of the hydrogen permeable membrane 11 within a temperature range suitable for hydrogen treatment (for example, 200 ° C. or more and 400 ° C. or less).

  A hydrogen concentration meter 15 is preferably connected to the permeate hydrogen chamber 13. By monitoring the hydrogen gas concentration in the permeate hydrogen chamber 13, the amount of oxidizing gas supplied to the permeate hydrogen chamber 13 can be appropriately controlled. Note that the amount of oxidizing gas supplied to the permeate hydrogen chamber 13 is desirably controlled so that the atmosphere in the permeate hydrogen chamber 13 deviates from the hydrogen gas explosion range.

  After confirming that the hydrogen gas concentration in the permeated hydrogen chamber 13 is almost zero (the hydrogen permeated through the hydrogen permeable membrane 11 (hydrogen permeable alloy dense membrane 11a) is almost completely converted into water vapor), the valve 56 is turned on. Open and discharge water vapor from the water vapor exhaust pipe 16.

  In the present invention, the hydrogen permeable alloy dense membrane 11a of the hydrogen permeable membrane 11 is not limited as long as it has sufficient hydrogen permeability (for example, hydrogen permeability coefficient) in the hydrogen treatment temperature range (for example, 200 ° C. or more and 400 ° C. or less). There is no limitation, and a dense film of a known hydrogen permeation alloy (for example, a palladium alloy such as Pd-23% Ag, Pd-5% Au, Pd-40% Cu) (film without pinholes or cracks). Can be used.

  However, the thickness of the hydrogen permeable alloy dense film 11a is preferably 15 μm or more and 50 μm or less from the viewpoint of improving the amount of hydrogen treatment (hydrogen treatment efficiency) and raising and maintaining the temperature to a desired temperature. When the thickness of the hydrogen permeable alloy dense film 11a is less than 15 μm, the absolute value of the mechanical strength of the film becomes too low, and the hydrogen permeable alloy dense film 11a is easily damaged. If the thickness of the hydrogen permeable alloy dense film 11a exceeds 50 μm, the permeated hydrogen flux becomes too small, and the heat capacity becomes too large, making it difficult to raise and maintain the desired temperature.

  The metal species of the catalyst metal porous layer 11b of the hydrogen permeable membrane 11 is not particularly limited as long as it is a catalyst metal that promotes a water vapor conversion reaction between hydrogen and oxygen, and a known catalyst metal can be used. . For example, at least one of rubidium, ruthenium, rhodium, palladium, rhenium, iridium, and platinum can be suitably used.

  Here, the present invention is characterized in that the catalytic metal layer formed on the surface of the hydrogen permeable membrane 11 is a porous layer. For example, by forming a porous layer mainly composed of catalytic metal particles, the surface area of the catalytic metal can be increased to increase the efficiency (reaction rate) of the water vapor conversion reaction (as a result, the calorific value per unit time can be reduced). Can be increased). In addition, there is an advantage that the catalytic metal layer itself does not become a hydrogen permeation barrier (it does not become a hydrogen permeation limiting layer). As an example of the form of the porous layer mainly composed of catalyst metal particles, an island-shaped film may be formed so that voids remain between the catalyst metal particles.

  There is no particular limitation on the method for forming the catalytic metal porous layer 11b as long as a porous layer mainly composed of catalytic metal particles can be formed. Vapor growth methods (for example, sputtering, vapor deposition, molecular beam epitaxy, plasma spraying, plasma spraying, laser ablation, ion plating, cluster ion beam, chemical vapor deposition) and liquid phase formation A film method (for example, an electrolytic plating method, an electroless plating method, a metal organic compound decomposition method, a slurry coating method, a spin coating method, a dip method) can be suitably used.

  From the viewpoint of easy formation of a porous layer mainly composed of catalytic metal particles, the efficiency of the water vapor conversion reaction (reaction rate), and the viewpoint of material cost, the catalytic metal porous layer 11b has an average thickness. Is preferably 20 nm or more and less than 100 nm, more preferably 30 nm or more and 50 nm or less. If the average thickness of the catalytic metal porous layer 11b is less than 20 nm, it is difficult to increase the surface area of the catalytic metal, and the efficiency of the water vapor conversion reaction cannot be secured sufficiently. When the average thickness of the catalytic metal porous layer 11b is 100 nm or more, the catalytic metal particles are in close contact with each other and easily become the same as the dense film, and the advantages of the porous layer are diminished and the material cost is increased.

(Experiment for confirming hydrogen permeable membrane throughput)
A Pd-23% Ag film (thickness 15μm) is prepared as a hydrogen permeable alloy dense film, and a Pd layer (average thickness 30 nm) is sputtered as a catalytic metal porous layer on both surfaces of the Pd-23% Ag film. A hydrogen permeable membrane (Example 1) of the present invention was produced by the method. For comparison, a Pd-23% Ag film alone (thickness 15 μm, Comparative Example 1) without a Pd layer and a Pd film alone (thickness 15 μm, Comparative Example 2) were prepared.

  The prepared hydrogen permeable membrane (Example 1, Comparative Examples 1 and 2) was incorporated into the hydrogen gas processing apparatus 100 of FIG. 1 and an experiment was conducted to investigate the water vapor conversion reaction in the hydrogen permeable membrane. As a gas to be treated, a mixed gas of “3% hydrogen + 3% oxygen + 94% nitrogen” was used. In addition, the hydrogen separator 10 was preheated to 100 ° C. for the purpose of preventing condensation in the hydrogen separator 10 (condensation of water vapor generated by the water vapor conversion reaction).

  In this experiment, oxygen gas was not supplied to the permeate hydrogen chamber 13 of the hydrogen separator 10 by the oxidizing gas supply mechanism 40, and the amount of hydrogen gas permeated to the permeate hydrogen chamber 13 was measured. The difference between the amount of hydrogen gas supplied to the mixed gas chamber 12 and the amount of hydrogen gas permeated to the permeated hydrogen chamber 13 is considered to be the amount that caused a water vapor conversion reaction on the surface of the hydrogen permeable membrane on the mixed gas chamber side. The ratio between the amount of hydrogen gas and the amount of permeated hydrogen gas was evaluated.

  FIG. 2 is a graph showing the relationship between the ratio of the amount of hydrogen gas permeated to the amount of hydrogen gas supplied “permeated hydrogen gas amount / the amount of hydrogen gas supplied” and the operation time. As shown in FIG. 2, in Comparative Example 1 (Pd-23% Ag film simple substance), the hydrogen gas supplied to the mixed gas chamber 12 almost permeated into the permeated hydrogen chamber 13 as hydrogen gas. From this result, it was confirmed that the water vapor conversion reaction hardly occurred on the surface of the single Pd-23% Ag film under the experimental conditions.

  In Comparative Example 2 (Pd membrane alone), the amount of hydrogen gas permeated decreased with the passage of time, and after about 40 minutes, “permeated hydrogen gas amount / supplied hydrogen gas amount” became about 5% or less. In the case of the Pd film alone, it was found that the reaction efficiency of the water vapor conversion reaction on the surface is low under the experimental conditions, and it takes a long time for the water vapor conversion reaction to become stable (the water vapor conversion reaction occurs actively).

  On the other hand, in Example 1 (hydrogen permeable membrane of the present invention), the amount of hydrogen gas permeated from immediately after the start of the supply of the mixed gas was very small, and “permeated hydrogen gas amount / supplied hydrogen gas amount” was about 2%. there were. From this result, it was confirmed that in Example 1, the water vapor conversion reaction was actively occurring in the catalytic metal porous layer even under the present experimental conditions.

In addition, when the temperature of each hydrogen permeable membrane (Example 1, Comparative Examples 1 and 2) was monitored with a thermometer 14, Comparative Example 1 showed almost no change from 100 ° C. However, Comparative Example 2 and Example 1 When the “permeated hydrogen gas amount / supplied hydrogen gas amount” reached about 2%, it was about 350 ° C.

  Next, the influence of the thickness of the catalytic metal porous layer in the hydrogen permeable membrane of the present invention was investigated. As in Example 1, a Pd-23% Ag film (thickness 15 μm) was prepared as a hydrogen permeable alloy dense film, and various thicknesses were formed as catalytic metal porous layers on both surfaces of the Pd-23% Ag film. Pd layers (average thickness 10, 30, 50, 100 nm) were formed by sputtering to produce a hydrogen permeable membrane.

  Under the same conditions as in the previous experiment, the reaction efficiency of the water vapor conversion reaction in each hydrogen permeable membrane was investigated. Here, “reaction efficiency” was defined as “{1− (amount of permeated hydrogen gas / amount of supplied hydrogen gas)} × 100%”. In addition, the reaction efficiency 3 minutes after the start of the supply of the mixed gas was investigated. The results are shown in Table 1. The previous comparative example 1 is also shown in Table 1 as “average thickness of catalytic metal porous layer 0 nm”.

  As shown in Table 1, in Comparative Example 1, 98% of the hydrogen gas supplied to the mixed gas chamber 12 permeated into the permeated hydrogen chamber 13 as hydrogen gas, and the reaction efficiency was evaluated as 2%.

  On the other hand, in the sample in which the Pd layer (catalytic metal porous layer) was formed, the amount of permeated hydrogen gas to the permeated hydrogen chamber 13 was clearly reduced, and the water vapor conversion reaction occurred in the catalytic metal porous layer. It was confirmed. In detail, Comparative Example 3 having an average Pd layer thickness of 10 nm and Comparative Example 4 having a thickness of 100 nm were insufficient in reaction efficiency. On the other hand, in Examples 1-2, very high reaction efficiency was achieved.

  In order to investigate the cause of the difference in reaction efficiency, the microstructure of the Pd layer (catalytic metal porous layer) was observed using a scanning electron microscope (SEM). As a result, in each of Examples 1 and 2 and Comparative Examples 3 and 4, a layer mainly composed of Pd particles (Pd crystal grains) having an average particle diameter of 10 to 50 nm was confirmed.

  More specifically, in Comparative Example 3 where the average thickness of the Pd layer was 10 nm, the Pd particles were formed in an island shape, but the island density (islet existence ratio) was very small, and the surface area of the catalyst metal was small. Therefore, it was considered that the reaction efficiency of the steam conversion reaction was insufficient. In Comparative Example 4 having an average thickness of Pd layer of 100 nm, Pd particles were formed very densely, and the advantage of the porous layer was lost because it was equivalent to a dense film (Comparative Example 2 above). (Pd film alone). On the other hand, in Examples 1 and 2, it was confirmed that a porous layer mainly composed of Pd particles was formed.

  From these experimental results, it was confirmed that the average thickness of the catalytic metal porous layer is preferably 20 nm or more and less than 100 nm.

(Second Embodiment)
FIG. 3 is a system schematic diagram showing an example of a main part of the hydrogen gas processing apparatus according to the second embodiment of the present invention. The hydrogen gas processing apparatus 200 according to this embodiment has a configuration in which a second condenser 60 is further arranged on the downstream side of the steam exhaust pipe 16 in addition to the configuration of the hydrogen gas processing apparatus 100 according to the first embodiment. It is. Hereinafter, regarding the hydrogen gas processing apparatus 200, members having the same meaning as those of the hydrogen gas processing apparatus 100 are denoted by the same reference numerals, and redundant description is omitted.

  As shown in FIG. 3, the hydrogen gas processing apparatus 200 has a second condenser 60 (freezer) for separating water vapor generated by the water vapor conversion reaction in the permeated hydrogen chamber 13 downstream of the water vapor exhaust pipe 16. Machine 61, refrigerant pipe 62, and condensate container 63) are connected. In the second condenser 60, the refrigerant cooled by the refrigerator 61 circulates in the refrigerant pipe 62, and the introduced water vapor exchanges heat with the refrigerant to become condensed water 34 and accumulate in the condensed water container 63.

  A pressure gauge 64 is preferably connected to the condensed water container 63 via a pressure gauge pipe 65 and a valve 57. When the amount of condensed water 34 in the condensed water container 63 increases (when the water level of the condensed water 34 rises), the volume of the gas phase portion in the condensed water container 63 decreases and the internal pressure increases. Thereby, the amount of the condensed water 34 in the condensed water container 63 can be detected. When the internal pressure of the condensed water container 63 rises to the set pressure, the valve 58 is opened and the condensed water 34 is discharged from the drain pipe 66.

  In addition, an exhaust pump 67 is preferably connected to the condensed water container 63 via an exhaust pipe 68 and a valve 59. Before performing the hydrogen gas treatment, the exhaust pump 67 is activated, the valve 59 is opened, and the inside of the condensed water container 63 is decompressed in advance. Thereby, water vapor generated by the water vapor conversion reaction in the permeated hydrogen chamber 13 can be positively discharged. It is desirable to adjust the pressure in the condensed water container 63 so that the condensed water 34 stored in the condensed water container 63 does not boil. For example, when the temperature in the condensate container 63 is normal temperature (25 ° C.), it is desirable that the temperature is adjusted to about 5 kPa so that the water vapor pressure (3.1 kPa) does not fall below 25 ° C.

  During the hydrogen gas treatment, it is desirable to close the valve 59 and stop the exhaust pump 67. In other words, it is desirable to operate the hydrogen gas processing apparatus 200 in a state sealed with the second condenser 60. Thereby, even if the hydrogen permeable membrane 10 is broken during the hydrogen gas treatment, untreated hydrogen gas can be prevented from being released into the atmosphere.

  As described above, the hydrogen gas processing apparatuses 100 and 200 according to the present invention are characterized in that no heating mechanism for continuing to heat the hydrogen separator 10 is provided. However, for the purpose of preventing condensation in the hydrogen separator 10 (condensation of water vapor generated by the water vapor conversion reaction) and / or for the purpose of shortening the warm-up time of the hydrogen gas treatment devices 100 and 200, A mechanism for preheating the hydrogen separator 10 to about 100 to 150 ° C. may be provided. Even when the preheating mechanism is provided, when the hydrogen gas treatment reaches a steady state (for example, when the hydrogen permeable membrane 10 reaches 200 ° C. or more), the preheating mechanism is stopped. Thereby, the running cost for continuing to heat the hydrogen separator can be reduced.

  The above-described embodiment has been specifically described to help understanding of the present invention, and the present invention is not limited to having all the configurations described. For example, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Furthermore, a part of the configuration of each embodiment can be deleted, replaced with another configuration, or added with another configuration.

100, 200 ... Hydrogen gas treatment equipment,
10 ... Hydrogen separator, 11 ... Hydrogen permeable membrane, 12 ... Mixed gas chamber, 13 ... Permeated hydrogen chamber,
11a ... hydrogen permeable alloy dense membrane, 11b ... catalytic metal porous layer,
14 ... Thermometer, 15 ... Hydrogen concentration meter, 16 ... Steam exhaust pipe,
20 ... Mixed gas temporary storage container, 21 ... Mixed gas supply piping, 22 ... Deoxygenated mixed gas recovery piping,
23 ... circulation pump,
30 ... Condenser, 31 ... Refrigerator, 32 ... Refrigerant tube, 33 ... Condensed water container, 34 ... Condensed water,
35 ... Hydrogen concentration meter, 36 ... Deoxygenated mixed gas exhaust piping, 37 ... Pressure gauge, 38 ... Pressure gauge piping,
39… Drain piping,
40 ... oxidizing gas supply mechanism, 41 ... oxidizing gas supply piping,
50-59… Valve,
60 ... Condenser, 61 ... Refrigerator, 62 ... Refrigerant tube, 63 ... Condensate container,
64 ... pressure gauge, 65 ... pressure gauge piping, 66 ... drain piping, 67 ... exhaust pump, 68 ... exhaust piping.

Claims (7)

A hydrogen gas processing apparatus for processing hydrogen gas from a mixed gas containing hydrogen gas and oxygen gas,
A hydrogen separator partitioned into a mixed gas chamber and a permeated hydrogen chamber by a hydrogen permeable membrane;
A mixed gas temporary storage container connected to the mixed gas chamber via a mixed gas supply pipe and a deoxygenated mixed gas recovery pipe;
A condenser disposed in the middle of the deoxygenated mixed gas recovery pipe;
An oxidizing gas supply mechanism connected to the permeated hydrogen chamber via an oxidizing gas supply pipe;
A water vapor exhaust pipe connected to the permeate hydrogen chamber;
In the hydrogen permeable membrane, a porous layer of a catalytic metal that promotes a water vapor conversion reaction between hydrogen and oxygen is formed on both surfaces of the dense membrane of the hydrogen permeable alloy.
A hydrogen gas processing apparatus, wherein the hydrogen separator is not provided with a heating mechanism for continuously heating the hydrogen separator. The hydrogen gas processing apparatus according to claim 1,
The hydrogen gas treatment apparatus, wherein the catalyst metal porous layer is a porous layer mainly composed of the catalyst metal particles having an average particle diameter of 10 nm to 50 nm. In the hydrogen gas processing apparatus according to claim 1 or 2,
The hydrogen permeable alloy dense membrane has a thickness of 15 μm or more and 50 μm or less,
The catalytic metal porous layer has an average thickness of 20 nm or more and less than 100 nm. In the hydrogen gas processing apparatus according to any one of claims 1 to 3,
A hydrogen gas processing apparatus, wherein a second condenser is further disposed downstream of the water vapor exhaust pipe. The hydrogen gas processing apparatus according to claim 4, wherein
A hydrogen gas processing apparatus, wherein an exhaust pump is further disposed downstream of the second condenser. In the hydrogen gas processing apparatus according to any one of claims 1 to 5,
The hydrogen permeable alloy is made of a palladium alloy,
The hydrogen gas treatment apparatus, wherein the catalyst metal is made of at least one of rubidium, ruthenium, rhodium, palladium, rhenium, iridium, and platinum. In the hydrogen gas processing apparatus according to any one of claims 1 to 6,
A hydrogen gas processing apparatus, wherein a circulation pump is further provided in the middle of the mixed gas supply pipe or the deoxygenated mixed gas recovery pipe.

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