WO2014156467A1 - Method for purifying hydrogen gas and purification apparatus - Google Patents

Method for purifying hydrogen gas and purification apparatus Download PDF

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Publication number
WO2014156467A1
WO2014156467A1 PCT/JP2014/055045 JP2014055045W WO2014156467A1 WO 2014156467 A1 WO2014156467 A1 WO 2014156467A1 JP 2014055045 W JP2014055045 W JP 2014055045W WO 2014156467 A1 WO2014156467 A1 WO 2014156467A1
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gas
adsorption tower
pressure
desorption
hydrogen
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PCT/JP2014/055045
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French (fr)
Japanese (ja)
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充 岸井
春名　一生
康一 志摩
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住友精化株式会社
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Priority to KR1020157030178A priority Critical patent/KR20150134379A/en
Publication of WO2014156467A1 publication Critical patent/WO2014156467A1/en

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
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    • F17B1/00—Gas-holders of variable capacity
    • F17B1/24—Gas-holders of variable capacity of dry type
    • F17B1/26—Gas-holders of variable capacity of dry type with flexible walls, e.g. bellows
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
    • B01D53/04—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography with stationary adsorbents
    • B01D53/0407—Constructional details of adsorbing systems
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
    • B01D53/04—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography with stationary adsorbents
    • B01D53/047—Pressure swing adsorption
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    • C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
    • C01B3/50—Separation of hydrogen or hydrogen containing gases from gaseous mixtures, e.g. purification
    • C01B3/56—Separation of hydrogen or hydrogen containing gases from gaseous mixtures, e.g. purification by contacting with solids; Regeneration of used solids
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    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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    • B01D2259/40058—Number of sequence steps, including sub-steps, per cycle
    • B01D2259/40075—More than ten
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    • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
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    • C01B2203/0205—Processes for making hydrogen or synthesis gas containing a reforming step
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    • C01B2203/042—Purification by adsorption on solids
    • C01B2203/043—Regenerative adsorption process in two or more beds, one for adsorption, the other for regeneration
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    • C01B2203/0465—Composition of the impurity
    • C01B2203/047—Composition of the impurity the impurity being carbon monoxide
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    • C01B2203/048—Composition of the impurity the impurity being an organic compound
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Definitions

  • the present invention relates to a method and an apparatus for purifying and obtaining hydrogen gas by removing impurities from a mixed gas containing hydrogen using a pressure fluctuation adsorption method (PSA method).
  • PSA method pressure fluctuation adsorption method
  • Purification of hydrogen gas by the PSA method is performed, for example, by introducing a gas mixture containing hydrogen into an adsorption tower packed with an adsorbent under high pressure to adsorb impurities to the adsorbent, and hydrogen-enriched gas enriched with hydrogen. And a step of depressurizing the inside of the adsorption tower to desorb impurities from the adsorbent and deriving the desorption gas from the adsorption tower.
  • the hydrogen production efficiency means the ratio of the energy of the hydrogen gas acquired to the energy (including purification of the hydrogen gas by the PSA method) input to produce hydrogen gas from the raw material.
  • the desorption gas derived from the adsorption tower contains carbon monoxide, hydrocarbons, residual hydrogen, and the like, and is a combustible gas.
  • combustible desorption gas (off-gas) is, for example, temporarily stored in a gas tank, and then supplied to a burner of a reforming reactor for hydrogen production and reused as fuel. In order to obtain a stable combustion state in the burner, it is necessary to supply fuel to the burner at a substantially constant flow rate.
  • the off-gas is temporarily stored in a gas tank, and the gas in the gas tank is adjusted to be sent to the fuel consumption system at a constant flow rate (for example, (See Patent Documents 1 and 2).
  • Patent Document 1 hydrogen gas is purified from the reformed gas by a pressure fluctuation adsorption gas separation apparatus (PSA apparatus) having three adsorption towers, and an offgas (desorption gas) derived from the adsorption tower is an offgas tank.
  • PSA apparatus pressure fluctuation adsorption gas separation apparatus
  • an offgas (desorption gas) derived from the adsorption tower is an offgas tank.
  • the amount of gas flowing to the off-gas tank varies depending on the process of the PSA method, and the gas pressure in the off-gas tank varies with this, but a flow rate adjustment valve is provided downstream of the off-gas tank.
  • the opening degree of the flow rate adjusting valve is increased or decreased based on the pressure.
  • the minimum pressure of the off-gas tank is 0.2 kg / cm 2 G (20 kPaG), which is due to the occurrence of gas flow resistance when adjusting the off-gas flow rate. Cannot be lower than the above.
  • Patent Document 2 hydrogen gas is purified from the reformed gas by a PSA apparatus having four adsorption towers, and off-gas (desorption gas) derived from the adsorption tower is stored in an off-gas storage tank.
  • a valve is provided on the upstream side of the off-gas storage tank, and the degree of opening of the valve is opened in stages. The law is disclosed.
  • the pressure increase in the off-gas storage tank can be suppressed to some extent, a pressure loss occurs due to the control of the off-gas flow rate, and the desorption pressure is increased by the loss. So improvement was desired.
  • the present invention has been conceived under such circumstances, and in purifying hydrogen gas from a mixed gas containing hydrogen, while collecting high-purity hydrogen gas by using a pressure fluctuation adsorption method, A method and apparatus suitable for supplying a desorption gas to a reuse destination at a stable gas pressure while increasing the recovery rate of high-purity hydrogen gas by reducing it to a lower pressure even if the desorption gas amount varies. It is an issue to provide.
  • the hydrogen gas purification method provided by the first aspect of the present invention is for purifying hydrogen gas from a mixed gas containing hydrogen and impurities, and is a pressure performed using an adsorption tower filled with an adsorbent.
  • the mixed gas is introduced into the adsorption tower in a state where the adsorption tower is at a relatively high pressure so that impurities in the mixed gas are adsorbed on the adsorbent, and hydrogen is absorbed from the adsorption tower.
  • a cycle including a step of deriving an enriched hydrogen-enriched gas and a step of depressurizing the adsorption tower to desorb impurities from the adsorbent and desorbing a desorption gas from the adsorption tower,
  • the desorption gas derived from the adsorption tower is introduced into a gas holder whose capacity changes, and the gas in the gas holder is discharged while maintaining the pressure in the gas holder substantially constant.
  • the present inventor conducted the following factor analysis in order to solve the above problems.
  • the space for the desorption gas to flow is fixed, the gas flow resistance increases as the amount of gas from the adsorption tower increases, and the pressure in the space for the desorption gas to rise once during the desorption operation. To do.
  • the present inventor has intensively studied to solve the above problems, and in order to make the pressure of the desorption gas derived from the adsorption tower constant at a low pressure more quickly on the downstream side, the desorption gas has a capacity of gas. It has been found that this can be realized by introducing it into a variable capacity gas holder. In addition, when the desorption gas flow path from the adsorption tower becomes stable at a low pressure, the desorption gas pressure in the adsorption tower decreases at a faster rate, and impurities are desorbed faster from the adsorbent, thereby increasing the decompression regeneration effect. It was also found.
  • the space (gas holder) through which the desorption gas flows is increased or decreased according to the amount of desorption gas, the flow path of the desorption gas can be made constant at a lower pressure, and the separation performance by the pressure fluctuation adsorption method can be improved. It becomes. Furthermore, when the desorbed gas is used as fuel, it is not necessary to attach a pressure regulating valve or pressure reducing valve that causes extra gas flow resistance. *
  • the gas holder includes a partition member that contains the desorption gas so as to block contact with the atmosphere and is displaced according to the amount of the desorption gas, and the capacity of the gas holder is downward with respect to the partition member.
  • the acting load and the force acting upward on the partition member due to the pressure of the desorption gas change while maintaining a balance.
  • the partition member supports a weight body. More specifically, the partition member is in the form of a diaphragm, and the weight body is in the form of a piston supported by the diaphragm. Alternatively, the partition member may be in the form of a film body, and the weight body may be in the form of a weight supported by the film body.
  • the partition member is configured as a weight body. More specifically, the partition member is in the form of a drum whose top is closed and whose bottom is open, and the bottom of the drum is immersed in the liquid.
  • the minimum pressure in the adsorption tower in the step of desorbing the desorption gas from the adsorption tower is 20 kPaG or less.
  • the gas discharged from the gas holder is supplied as fuel to another system.
  • an apparatus for purifying hydrogen gas from a mixed gas containing hydrogen wherein the adsorption tower is subjected to a pressure fluctuation adsorption method performed using an adsorption tower filled with an adsorbent.
  • the mixed gas is introduced to adsorb the impurities in the mixed gas to the adsorbent, the hydrogen-enriched gas is led out from the adsorption tower, and the adsorption tower is depressurized to desorb the impurities from the adsorbent.
  • a pressure fluctuation adsorption type gas separation device for deriving the desorption gas from the adsorption tower, a capacity variable type gas holder for introducing and discharging the desorption gas derived from the adsorption tower, An apparatus for purifying hydrogen gas is provided.
  • the gas holder includes a main body configured in a container shape, and a partition member accommodated in the main body and displaceable while maintaining a gas seal state between the main body and the gas holder.
  • the partition member With the displacement of the partition member, the amount of gas stored in the gas storage section partitioned by the main body portion and the partition member changes.
  • the partition member supports a weight body. More specifically, the partition member is in the form of a diaphragm, and the weight body is in the form of a piston supported by the diaphragm. Alternatively, the partition member may be in the form of a film body, and the weight body may be in the form of a weight supported by the film body.
  • the partition member instead of supporting the weight body by the partition member, the partition member itself may be configured as a weight body. More specifically, the partition member is in the form of a drum whose top is closed and whose bottom is open, and the bottom of the drum is immersed in the liquid.
  • the piston or the drum may be in contact with the inner surface of the main body through a plurality of rollers.
  • purification apparatus which can be used in performing the refinement
  • the gas flow state in steps 1 to 8 of the method for purifying hydrogen gas according to the present invention is shown.
  • the gas flow state in steps 9 to 16 of the method for purifying hydrogen gas according to the present invention is shown.
  • FIG. 1 shows a schematic configuration of a hydrogen gas purification apparatus that can be used to execute a hydrogen gas purification method according to an embodiment of the present invention.
  • the hydrogen gas purification apparatus X1 includes, for example, a plurality of adsorption towers 10A, 10B, 10C, and 10D, a gas holder 2, and pipes 31 to 36 that connect these and form gas passages, and pressure from a mixed gas containing hydrogen. Hydrogen is concentrated and purified using a variable adsorption method (PSA method).
  • the mixed gas is, for example, a reformed gas obtained by a steam reforming reaction of a hydrocarbon-based raw material (hydrocarbon or hydrocarbon derivative).
  • examples of the hydrocarbon-based raw material include natural gas, LPG (liquefied petroleum gas), biogas, methanol, and dimethyl ether.
  • the reformed gas contains, for example, carbon dioxide, carbon monoxide, and methane as impurities in addition to hydrogen as a main component.
  • hydrogen is 76.0 mol%
  • carbon dioxide is 20.0 mol%
  • carbon monoxide is 0.4 mol%
  • methane is 3.6 mol%.
  • Each of the adsorption towers 10A, 10B, 10C, and 10D has gas passages 11 and 12 at both ends, and impurities (carbon dioxide, carbon monoxide, methane) contained in the mixed gas between the gas passages 11 and 12. Etc.) is adsorbed for selective adsorption.
  • impurities carbon dioxide, carbon monoxide, methane contained in the mixed gas between the gas passages 11 and 12. Etc.
  • adsorbents include silica, alumina, activated carbon, and zeolite, and these may be used alone or in combination.
  • the piping 31 is for supplying the mixed gas to the adsorption towers 10A, 10B, 10C, and 10D, and is connected to the main trunk path 31 ′ and the gas passage 11 side of the adsorption towers 10A to 10D. It has branch paths 31A, 31B, 31C, 31D.
  • the branch paths 31A to 31D are provided with automatic valves 31a, 31b, 31c, and 31d for switching between an open state and a closed state.
  • a compressor (not shown) for pumping the mixed gas to the adsorption towers 10A to 10D may be provided on the main path 31 'of the pipe 31.
  • the piping 32 is a flow path of product gas (hydrogen-enriched gas) derived from each of the adsorption towers 10A to 10D, and is respectively connected to the main passage 32 'and the gas passage 12 side of the adsorption towers 10A to 10D. It has connected branch paths 32A, 32B, 32C, 32D.
  • the branch paths 32A to 32D are provided with automatic valves 32a, 32b, 32c, and 32d that switch between an open state and a closed state.
  • the pipe 33 is for returning a part of the product gas flowing through the pipe 32 (main trunk path 32 ′) to the adsorption towers 10A to 10D, and is connected to the main trunk path 32 ′ of the pipe 32.
  • 33 ′ and branch paths 33A, 33B, 33C, 33D connected to the gas passage 12 side of the adsorption towers 10A to 10D, respectively.
  • a flow rate adjustment valve 331 is provided in the main trunk path 33 ′.
  • the branch paths 33A to 33D are provided with automatic valves 33a, 33b, 33c, and 33d capable of switching between an open state and a closed state.
  • the pipe 34 is used to connect the adsorption towers 10A to 10D to each other.
  • the pipe 34 ' is turned back in the middle, and one half path of the main road 34' ("half path" is a turned-up portion).
  • Branch path 34A, 34B, 34C, 34D each connected to the gas passage 12 side of the adsorption towers 10A-10D.
  • branch paths 34A ′, 34B ′, 34C ′, and 34D ′ connected to the other half path of the main trunk path 34 ′ and connected to the gas passage 12 side of the adsorption towers 10A to 10D, respectively.
  • a flow rate adjustment valve 341 is provided at an intermediate portion of the main trunk line 34 '.
  • the branch paths 34A to 34D and 34A 'to 34D' are provided with automatic valves 34a, 34b, 34c, 34d and 34a ', 34b', 34c ', 34d' for switching between the open state and the closed state. Yes.
  • the pipe 35 is for introducing the gas (desorption gas) derived from each of the adsorption towers 10A to 10D into the gas holder 2, and is connected to the main path 35 'connected to the gas holder 2 and the adsorption towers 10A to 10D.
  • Each of the gas passages 11 has branch paths 35A, 35B, 35C, and 35D connected to each side.
  • the branch paths 35A to 35D are provided with automatic valves 35a, 35b, 35c, and 35d for switching between an open state and a closed state.
  • the pipe 36 is a flow path for desorption gas discharged from the gas holder 2, and is connected to the gas holder 2.
  • the pipe 36 is connected to another system such as a fuel system attached to a reforming reactor (not shown) for producing hydrogen, for example.
  • the gas holder 2 is a variable capacity gas holder that accommodates desorption gas from the adsorption towers 10A to 10D.
  • the gas holder 2 is a piston type, and includes a main body portion 21, a diaphragm 22, and a piston 23.
  • the main body 21 is made of a metal such as iron or stainless steel and has a cylindrical container shape.
  • the main body 21 has a lower main body 211 and an upper main body 212 and can be separated vertically, and is integrally combined by fastening the flanges of the lower main body 211 and the upper main body 212 with bolts 213.
  • the lower main body 211 is provided with a gas inlet 214 and a gas outlet 215.
  • a main trunk path 35 ′ of a pipe 35 is connected to the gas inlet 214, and a pipe 36 is connected to the gas outlet 215.
  • the diaphragm 22 is molded from synthetic rubber reinforced with fibers.
  • the diaphragm 22 includes an annular flange 221, a cylindrical portion 222 that extends with one end connected to the inner peripheral edge of the flange 221, and a bottom 223 that closes the other end of the cylindrical portion 222.
  • the diaphragm 22 is accommodated in the main body 21 while the flange portion 221 is sandwiched between the flanges of the lower main body 211 and the upper main body 212 in a sealed state.
  • the diaphragm 22 can be moved up and down (displaceable) while maintaining a gas seal state with the lower main body 211 (main body portion 21), and functions as a partition member.
  • a region partitioned by the diaphragm 22 and the lower main body 211 (main body portion 21) is a gas storage portion 24 that stores the desorption gas from the adsorption towers 10A to 10D.
  • the piston 23 is made of metal such as iron or stainless steel, and is disposed inside the cylindrical portion 222 of the diaphragm 22.
  • the piston 23 has a cylindrical piston cylinder portion 231 extending in the vertical direction and a piston bottom portion 232 connected to the lower end of the piston cylinder portion 231.
  • the piston 23 is supported by the diaphragm 22 in a state where the piston bottom portion 232 is aligned with the bottom portion 223 of the diaphragm 22.
  • a plurality of guide rollers 235 are provided, each via a fixture 234. At least three guide rollers 235 (only two are shown in FIG. 2) are provided. Preferably, these guide rollers 235 are arranged at equal intervals in the circumferential direction of the piston cylinder portion 231.
  • Each guide roller 235 is in contact with the inner peripheral surface of the upper body 212 and is rotatable about a horizontal axis.
  • the outer diameter dimension of the piston cylinder portion 231 is, for example, about 1000 mm.
  • the gap between the outer peripheral surface of the piston cylinder portion 231 and the inner peripheral surface of the upper main body 212 is, for example, 50 to 200 mm, and preferably 100 to 150 mm.
  • the diaphragm 22 and the piston 23 supported by the diaphragm 22 move up and down while maintaining a substantially constant posture by the guide roller 235.
  • the gas amount in the gas storage unit 24 changes (increases), In response to the change, the piston 23 rises while being supported by the diaphragm 22.
  • the pressure (internal pressure) of the gas storage unit 24 is determined according to the weight of the piston 23, and can be set to 1 kPaG or less (G means gauge pressure; the same applies hereinafter) at the lowest pressure.
  • the hydrogen gas purification method can be executed using the hydrogen gas purification apparatus X1 having the above-described configuration. Specifically, during the operation of the hydrogen gas purification apparatus X1, the automatic valves 31a to 31d, 32a to 32d, 33a to 33d, 33a to 33d, 34a to 34d, 34a ′ to 34d ′, 35a to 35d, and the like shown in FIG. By switching the flow control valves 331 and 341, a desired gas flow state is realized in the apparatus, and one cycle consisting of the following steps 1 to 16 is repeated (in FIG. 3, the open state of each valve is represented by ⁇ and The closed state is indicated by x).
  • an adsorption step in each of the adsorption towers 10A, 10B, 10C, 10D, an adsorption step, a pressure equalization (first pressure reduction) step, a cocurrent flow pressure reduction step, a pressure equalization (second pressure reduction) step, a countercurrent flow
  • a pressure reduction process a pressure equalization cleaning process, a pressure equalization (first pressure increase) process, a standby process, a pressure equalization (second pressure increase) process, and a pressure increase process are performed.
  • equal amounts of activated carbon and zeolite as adsorbents are stacked and packed in the lower and upper portions of the adsorption towers 10A to 10D. 4 and 5 show the gas flow state in the hydrogen gas purification apparatus X1 in steps 1 to 16.
  • step 1 the open / close state of each valve is selected as shown in FIG. 3, and the gas flow state as shown in FIG. 4 (a) is achieved.
  • the adsorption process is performed in the adsorption tower 10A, and the adsorption tower 10B.
  • the pressure equalization (first pressure reduction) step is performed in the adsorption tower 10C, and the pressure equalization (second pressure increase) step is performed in the adsorption tower 10D.
  • the operation time of each step in Step 1 is set to 20 seconds, for example.
  • step 1 the raw material gas (mixed gas) is introduced into the adsorption tower 10 ⁇ / b> A via the pipe 31 and the gas passage port 11.
  • the inside of the adsorption tower 10A in the adsorption process is maintained at a predetermined high pressure state, and impurities (carbon dioxide, carbon monoxide, methane, etc.) in the mixed gas are adsorbed by the adsorbent in the adsorption tower 10A, and are adsorbed.
  • a product gas (hydrogen-enriched gas) having a high hydrogen gas concentration is led out from the gas passage 12 side of the tower 10A. This product gas is recovered via a pipe 32 to, for example, a buffer tank (not shown) outside the apparatus.
  • the adsorption tower 10B by depressurizing the inside of the tower in the countercurrent direction, impurities are desorbed from the adsorbent, and desorbed gas is led out from the gas passage 11 side of the adsorption tower 10B.
  • the desorption gas is introduced into the gas holder 2 through the pipe 35. Since the adsorption tower 10B has previously performed the countercurrent depressurization step (see step 16 shown in FIG. 5 (p)), the desorption gas has already been derived in the previous step. Therefore, the amount of desorption gas derived from the adsorption tower 10B in step 1 is small.
  • the gas in the adsorption tower 10C led out from the gas passage 12 of the adsorption tower 10C is introduced through the pipe 34.
  • the pressure in the tower of the adsorption tower 10C is higher than that in the tower of the adsorption tower 10D. Therefore, by introducing the gas in the adsorption tower 10C into the adsorption tower 10D, the pressure in the adsorption tower C is reduced and the pressure in the adsorption tower 10D is increased.
  • step 2 the open / close state of each valve is selected as shown in FIG. 3, the gas flow state as shown in FIG. 4B is achieved, and the adsorption step continues to the adsorption tower 10B in the adsorption tower 10A.
  • the pressure equalization washing process is performed in the adsorption tower 10C, the cocurrent depressurization process is performed, and the adsorption tower 10D is pressurized.
  • the operation time of each step in step 2 is, for example, 70 seconds.
  • step 2 the mixed gas is introduced into the adsorption tower 10A via the pipe 31 and the gas passage port 11 following the step 1,
  • Product gas is derived from the adsorption tower 10A.
  • the product gas is recovered in the same manner as in Step 1, but a part of the product gas is introduced into the adsorption tower 10D through the pipe 33, and the pressure of the adsorption tower 10D is increased.
  • step 2 the gas in the adsorption tower 10C led out from the gas passage opening 12 of the adsorption tower 10C is introduced to the gas passage opening 12 side of the adsorption tower 10B via the pipe 34, and the inside of the adsorption tower 10B.
  • the gas (desorption gas) remaining in the gas is led out from the gas passage port 11 side.
  • the desorption gas is introduced into the gas holder 2 through the pipe 35.
  • the gas amount of the desorption gas derived from the adsorption tower 10B is larger than the gas amount of the desorption gas derived from the adsorption tower 10B in Step 1.
  • step 3 the open / close state of each valve is selected as shown in FIG. 3, the gas flow state as shown in FIG. 4C is achieved, and the adsorption process is continued in the adsorption tower 10A.
  • the pressure equalization (first pressure increase) step is performed in the adsorption tower 10C
  • the pressure equalization (second pressure reduction) step is continued
  • the pressure increase step is continued in the adsorption tower 10D.
  • the operation time of each step in Step 3 is set to 20 seconds, for example.
  • Step 3 the mixed gas is introduced into the adsorption tower 10A via the pipe 31 and the gas passage port 11 following Step 2, Product gas is derived from the adsorption tower 10A. Part of the product gas is introduced into the adsorption tower 10D via the pipe 33, and the pressure in the adsorption tower 10D is continuously increased.
  • step 3 the gas in the adsorption tower 10 ⁇ / b> C derived from the gas passage opening 12 of the adsorption tower 10 ⁇ / b> C is introduced to the gas passage opening 12 side of the adsorption tower 10 ⁇ / b> B through the pipe 34. Note that in step 3, no gas is led out toward the gas holder 2 from any of the adsorption towers 10A to 10D.
  • step 4 the open / close state of each valve is selected as shown in FIG. 3, the gas flow state shown in FIG. 4 (d) is achieved, and the adsorption step continues to the adsorption tower 10B in the adsorption tower 10A. Then, the standby process is performed, the countercurrent pressure reducing process is performed in the adsorption tower 10C, and the pressure increasing process is continued in the adsorption tower 10D.
  • the operation time for each step in step 4 is, for example, 90 seconds.
  • step 4 following step 3, the mixed gas is introduced into the adsorption tower 10 ⁇ / b> A via the pipe 31 and the gas passage port 11.
  • Product gas is derived from the adsorption tower 10A.
  • Part of the product gas is introduced into the adsorption tower 10D via the pipe 33, and the pressure in the adsorption tower 10D is continuously increased.
  • the adsorption tower 10B receives the first pressure equalization (pressure increase) in the previous step 3, but waits to receive the second pressure equalization (pressure increase) in the subsequent step 5.
  • the adsorption tower 10C As for the adsorption tower 10C, by depressurizing in the counterflow direction, impurities are desorbed from the adsorbent, and desorption gas is led out from the gas passage 11 side of the adsorption tower 10C.
  • the adsorption tower 10C is continuously depressurized in steps 1 to 3, and the pressure in the adsorption tower 10C is considerably low at the start of step 4.
  • Step 4 since the adsorption tower 10C is further depressurized, the amount of gas desorbed from the adsorbent is large, and the amount of desorption gas derived from the adsorption tower 10C is relatively large.
  • Steps 1 to 4 correspond to 1 ⁇ 4 of one cycle composed of steps 1 to 16, and the process time of steps 1 to 4 is a total of 200 seconds.
  • steps 5 to 8 the open / closed state of each valve is selected as shown in FIG. 3, and as shown in FIGS. 4 (e) to (h), the adsorption tower 10A in the adsorption tower 10C in steps 1 to 4 is selected.
  • the pressure equalization (first pressure reduction) step, the cocurrent pressure reduction step, the pressure equalization (second pressure reduction) step, and the countercurrent pressure reduction step are performed.
  • the adsorption tower 10B is the same as the adsorption tower 10D in steps 1 to 4.
  • a pressure equalization (second pressure increase) step and a pressure increase step are performed.
  • a counter-current depressurization process In the adsorption tower 10C, a counter-current depressurization process, a pressure equalization washing process, a pressure equalization (first pressure increase) process, and a standby process are performed in the same manner as in the adsorption tower 10B in steps 1 to 4, and in the adsorption tower 10D, steps 1 to The adsorption step is performed in the same manner as the adsorption tower 10A in FIG.
  • steps 9 to 12 the open / close state of each valve is selected as shown in FIG. 3, and in the adsorption tower 10A, as shown in FIGS. 5 (i) to (l), the adsorption tower 10B in steps 1 to 4 is selected.
  • the counter-current depressurization step, the pressure equalization washing step, the pressure equalization (first pressure increase) step, and the standby step are performed in the same manner as described above.
  • the adsorption step is performed in the same manner as the adsorption tower 10A in steps 1 to 4. Is called.
  • the pressure equalization (second pressure increase) process and the pressure increase process are performed in the same manner as the adsorption tower 10D in steps 1 to 4, and the adsorption tower 10D is equalized in the same manner as the adsorption tower 10C in steps 1 to 4.
  • a pressure (first pressure reduction) step, a cocurrent pressure reduction step, a pressure equalization (second pressure reduction) step, and a countercurrent pressure reduction step are performed.
  • steps 13 to 16 the open / close state of each valve is selected as shown in FIG. 3, and as shown in FIGS. 5 (m) to (p), in the adsorption tower 10A, the adsorption tower 10D in steps 1 to 4 is selected.
  • the pressure equalization (second pressure increase) step and the pressure increase step are performed in the same manner as described above.
  • the pressure equalization (first pressure reduction) step, the cocurrent flow pressure reduction step, A pressure equalization (second pressure reduction) step and a countercurrent pressure reduction step are performed.
  • an adsorption process is performed in the same manner as the adsorption tower 10A in steps 1 to 4, and in the adsorption tower 10D, a counter-current decompression process, a pressure equalization washing process, A pressure equalization (first pressure increase) step and a standby step are performed.
  • the steps 1 to 16 described above are repeatedly performed in each of the adsorption towers 10A to 10D, so that the mixed gas is continuously introduced into any of the adsorption towers 10A to 10D and the hydrogen gas concentration is high. Product gas is acquired continuously.
  • the desorption gas when the desorption gas is led out from any of the adsorption towers 10A to 10D by the operation steps (steps 1 to 16) shown in FIGS. 4 and 5, the desorption gas is supplied to the gas holder 2 through the gas inlet 214. The gas is discharged from the gas outlet 215 while being introduced into the gas outlet. Since the capacity of the gas holder 2 is variable, the capacity of the space (gas holder 2) through which the gas flows increases or decreases according to the amount of desorbed gas derived from the adsorption towers 10A to 10D.
  • the load of the piston 23 acting downward on the diaphragm 22 and the force acting upward on the diaphragm 22 by the pressure of the desorption gas are kept in balance.
  • capacitance of the gas holder 2 changes. Thereby, even if the gas amount of the desorption gas derived from the adsorption towers 10A to 10D fluctuates, the capacity of the gas holder 2 increases or decreases according to the desorption gas amount, and the pressure in the gas holder 2 does not change substantially. Kept constant.
  • the flow rate of the desorption gas from the gas holder 2 is kept substantially constant without attaching a flow rate adjusting valve or the like that causes gas flow resistance.
  • the desorption gas is a combustible gas containing carbon monoxide, hydrocarbons, residual hydrogen, and the like. Therefore, the desorption gas discharged from the gas holder 2 at a constant flow rate can be stably supplied as fuel to other systems such as a burner attached to the reforming reactor.
  • a configuration that does not require a flow rate adjustment valve or the like is preferable for further reducing the pressure in the gas holder 2.
  • the pressure in the gas tank fluctuates due to the fluctuation of the gas amount of the desorption gas from the adsorption tower.
  • the pressure in the gas tank increases. Therefore, the gas pressure (desorption pressure) in the adsorption tower during the desorption operation Is difficult to lower.
  • the pressure in the gas holder 2 is maintained substantially constant even when the amount of the desorption gas from the adsorption towers 10A to 10D increases.
  • the effect that the depressurization speed of the adsorption towers 10A to 10D is increased can be obtained.
  • the decompression regeneration effect of the adsorption towers 10A to 10D is enhanced, and the amount of product gas acquired is increased and the hydrogen recovery rate is increased.
  • the desorption gas when the desorption gas is stored in a fixed capacity type gas tank, the internal space capacity is fixed. For this reason, the change in the gas amount of the desorption gas from the adsorption tower is accompanied by a pressure change in the gas tank. Therefore, in the fixed capacity type gas tank, in order to suppress the influence of the fluctuation of the gas amount, a relatively large space capacity is required. For example, a space capacity about 10 times the capacity of the adsorption tower is required.
  • the desorption gas when the desorption gas is stored in the variable capacity type gas holder 2 as in this embodiment, the gas holder is displaced by displacing the diaphragm 22 (partition member) according to the changed gas amount without causing a pressure change. 2 capacity can be increased or decreased. Thereby, in the gas holder 2, it is sufficient to secure about 3 times the capacity of the adsorption towers 10A to 10D as the maximum capacity, and the waste of the gas storage space can be eliminated.
  • FIG. 6 shows pressure profiles when a variable capacity gas holder is attached to a desorption gas pipe and when a fixed capacity gas tank is attached in a pressure fluctuation adsorption operation for purifying hydrogen using four adsorption towers.
  • the piston-type gas holder 2 shown in FIG. 2 was used as the variable-capacity gas holder, and the capacity of the gas holder 2 (gas storage unit 24) was about three times the capacity of the adsorption tower.
  • the capacity of the fixed capacity type gas tank was about 10 times the capacity of the adsorption tower.
  • As the mixed gas one having a composition of 76.0 mol% hydrogen, 20.0 mol% carbon dioxide, 0.4 mol% carbon monoxide, and 3.6 mol% methane was used.
  • the adsorption pressure was 2 MPaG and the desorption pressure was 33 kPaG.
  • the pressure related to the variable capacity gas holder shown in FIG. 6 is expressed for steps 1 to 4 in the above steps 1 to 16, and the pressure related to the fixed capacity gas tank is also expressed for steps 1 to 4.
  • the pressure in the adsorption tower (desorption pressure) is shown for the adsorption tower 10C in steps 1 to 4.
  • the internal pressure of the fixed-capacity gas tank rises along with the introduction of the desorption gas into the gas tank after the start of steps 2 and 4, and in step 2, the pressure increases to 60 kPaG (FIG. 6).
  • the pressure reached 58 kPaG (120 seconds in FIG. 6).
  • the internal pressure of the variable capacity gas holder was about 32 kPaG through steps 1 to 4, and was kept substantially constant.
  • the pressure (desorption pressure) in the adsorption tower is determined from the time when switching from Step 3 to Step 4 (when 110 seconds have elapsed in FIG. 6) in the case of a fixed capacity type gas tank. It slowly dropped and took about 40 seconds to reach the lowest pressure.
  • the pressure in the adsorption tower (desorption pressure) decreased at a stroke from the time of switching from step 3 to step 4 and decreased to the minimum pressure at a fairly high speed within 10 seconds.
  • the 7 includes a body 21A, a balloon 22A accommodated in the body 21A, and a weight 23A, and is configured as a balloon type.
  • the body 21A is made of a metal such as iron or stainless steel, has a cylindrical shape as a whole, and has a top plate 216 for closing an opening formed in the upper portion.
  • An inlet gas nozzle 217 and an outlet gas nozzle 218 are provided below the body 21A.
  • the main gas passage 35 ′ (FIG. 1) of the pipe 35 is connected to the inlet gas nozzle 217, and the pipe 36 (FIG. 1) is connected to the outlet gas nozzle 218.
  • the balloon 22A is molded from a synthetic rubber reinforced with fibers, and is a film that becomes hemispherical when expanded.
  • the peripheral edge of the balloon 22A is fixed to an annular mounting bracket 219 provided on the inner surface of the body 21A.
  • the balloon 22A is movable up and down (displaceable) while maintaining the gas seal state between the balloon 21A and functions as a partition member.
  • a region partitioned by the balloon 22A and the lower part of the body 21A is a gas storage unit 24 for storing the desorption gas from the adsorption towers 10A to 10D.
  • the weight 23A is for adjusting the internal pressure of the gas holder 2A, and is fixed to the central upper surface of the balloon 22A.
  • the pressure (internal pressure) of the gas storage unit 24 is determined according to the weight of the weight 23A, and can be set to 1 kPaG or less at the lowest pressure.
  • the difference between the volume of the gas storage portion 24 in the state indicated by the solid line where the balloon 22A is most deflated and the volume of the gas storage portion 24 in the state indicated by the imaginary line where the balloon 22A is expanded most is the gas holder 2A.
  • the capacity in the (gas storage unit 24) can be increased or decreased.
  • the load of the weight 23A acting downward with respect to the balloon 22A and the force acting upward with respect to the balloon 22A due to the pressure of the desorption gas are kept in balance, while the gas holder 2A ( The capacity of the gas storage part 24) changes.
  • the capacity of the gas storage part 24 changes.
  • the gas holder 2B shown in FIG. 8 includes a cylindrical container-shaped body 25 and a drum 26 accommodated inside the body 25.
  • the body 25 is made of metal such as iron or stainless steel, and the body 25 is filled with a liquid 27 such as water or an organic liquid (oil) having low activity.
  • the liquid 27 is continuously discharged from the overflow nozzle 252 while being introduced from the water supply nozzle 251 provided in the body 25, and for example, the reduced amount is replenished even when the water as the liquid 27 evaporates. Yes.
  • the liquid 27 becomes dirty, it can be discharged from the discharge nozzle 253 and replaced.
  • the drum 26 is made of a metal such as iron or stainless steel, and has a cylindrical shape with the top covered.
  • the drum 26 is immersed in the liquid 27, and the internal space and the outside are blocked by the liquid 27.
  • the drum 26 is an example of a partition member.
  • a plurality of rollers 261 and 262 are provided below and above the drum 26. Each roller 261 contacts the inner peripheral surface of the body 25 and moves up and down. Each roller 262 moves up and down using a plurality of cylindrical support members 28 arranged on the outer periphery of the body 25 as guides. As a result, the drum 26 moves up and down while maintaining a substantially constant posture by the rollers 261 and 262.
  • An inlet gas nozzle 254 and an outlet gas nozzle 255 are provided at the lower part of the body 25.
  • the main gas passage 35 ′ of the pipe 35 is connected to the inlet gas nozzle 254, and the pipe 36 is connected to the outlet gas nozzle 255.
  • Each of the inlet gas nozzle 254 and the outlet gas nozzle 255 rises inside the drum 26, and the upper end opens above the liquid level of the liquid 27.
  • the drum 26 can be moved up and down by the liquid 27 while maintaining the gas seal state of the internal space between the liquid 27 and the liquid surface.
  • the space partitioned by the drum 26 and the liquid 27 is a gas storage space 29 for storing the desorption gas from the adsorption towers 10A to 10D.
  • the drum 26 has a function of adjusting the internal pressure of the gas holder 2B.
  • the pressure (internal pressure) of the gas storage space 29 is determined according to the weight of the drum 26 floating in the liquid 27, and can be set to 1 kPaG or less at the lowest pressure.
  • the difference between the volume of the gas storage space 29 in the state indicated by the solid line with the drum 26 at the lowest level and the volume of the gas storage space 29 in the state indicated by the virtual line with the drum 26 at the highest level is The capacity of the gas holder 2B (the gas storage space 29) can be increased or decreased.
  • the load of the drum 26 that acts downward with respect to the drum 26 and the force that acts upward with respect to the drum 26 due to the pressure of the desorption gas are balanced, while the gas holder 2B ( The capacity of the gas storage space 29) changes.
  • the capacity of the gas storage space 29 changes.
  • the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the invention.
  • a configuration different from that of the above-described embodiment may be adopted for the configuration of the piping that forms the gas flow path in the apparatus that executes the method for purifying hydrogen gas according to the present invention.
  • the number of adsorption towers is not limited to the four-column type shown in the above embodiment, and the same effect can be expected even when there are three or less towers or five or more towers.
  • Example 1 Using the hydrogen gas purification apparatus X1 having the schematic configuration shown in FIG. 1, the adsorption process, pressure equalization (first pressure reduction) process, cocurrent pressure reduction process, pressure equalization (second pressure reduction) process shown in FIGS. , A counter flow depressurization step, a pressure equalization cleaning step, a pressure equalization (first pressure increase) step, a standby step, a pressure equalization (second pressure increase) step, and a pressure increase step are performed in one cycle (steps 1 to 16). By repeating at 10B, 10C, and 10D, hydrogen gas was concentrated and purified from a predetermined mixed gas.
  • Each of the adsorption towers 10A, 10B, 10C, and 10D of the hydrogen gas purification apparatus X1 used in this example is made of stainless steel and has a cylindrical shape (inner diameter: 37 mm, inner height: 1,000 mm), and a capacity of about 1 dm. It was 3 .
  • Each adsorption tower was packed with 0.5 dm 3 (apparent volume) of activated carbon and 5A-type zeolite as adsorbents.
  • the balloon type (volume variable type) gas holder 2A shown in FIG. 7 was used, and the one having a capacity of about 3 dm 3 was used.
  • the composition of the mixed gas was 76.0 mol% for hydrogen, 20.0 mol% for carbon dioxide, 0.4 mol% for carbon monoxide, and 3.6 mol% for methane.
  • This mixed gas was continuously supplied to the hydrogen gas purification apparatus X1 at a flow rate of 18.3 Ndm 3 / min (N represents a standard state, the same applies hereinafter).
  • steps 1, 2, 3, and 4 are respectively 20 seconds, 70 seconds, 20 seconds, and 90 seconds, and the total of steps 1 to 4 is 200 seconds.
  • the cycle time of one cycle consisting of steps 1 to 16 was 800 seconds.
  • the maximum pressure inside the adsorption towers 10A to 10D in the adsorption process is 2.0 MPaG, and the minimum pressure (desorption pressure) inside the adsorption towers 10A to 10D during the desorption operation (countercurrent depressurization process, pressure equalization washing process) is 33 kPaG. It adjusted so that it might become.
  • the hydrogen purity is 99.999 vol%, and the content of impurities (carbon dioxide, carbon monoxide and methane) in the product gas is less than 100 vol ppm.
  • the acquired gas amount was 12.3 Ndm 3 / min.
  • the recovery rate of hydrogen in the acquired gas was 88.2%.
  • the internal pressure of the gas holder 2A was constant at about 32 kPaG and did not vary. The results of this example are shown in Table 1.
  • Example 2 Hydrogen gas was purified from the mixed gas in the same manner as in Example 1 except that the desorption pressure was 20 kPaG.
  • the product gas concentrated and purified in this example performed under such conditions has a hydrogen purity of 99.999 vol%, and the content of impurities (carbon dioxide, carbon monoxide and methane) in the product gas is less than 10 volppm.
  • the acquired gas amount was 12.55 Ndm 3 / min.
  • the recovery rate of hydrogen in the acquired gas was 90.0%.
  • the internal pressure of the gas holder 2A was constant at about 20 kPaG and did not change. The results of this example are shown in Table 1.
  • Example 3 Hydrogen gas was purified from the mixed gas in the same manner as in Example 1 except that the desorption pressure was 10 kPaG.
  • the product gas concentrated and purified in this example performed under such conditions has a hydrogen purity of 99.999 vol%, and the content of impurities (carbon dioxide, carbon monoxide and methane) in the product gas is less than 10 volppm.
  • the acquired gas amount was 12.6 Ndm 3 / min.
  • the recovery rate of hydrogen in the acquired gas was 90.5%.
  • the internal pressure of the gas holder 2A was constant at about 10 kPaG and did not fluctuate. The results of this example are shown in Table 1.
  • Example 4 Hydrogen gas was purified from the mixed gas in the same manner as in Example 1 except that the desorption pressure was 1 kPaG.
  • the product gas concentrated and purified in this example performed under such conditions has a hydrogen purity of 99.999 vol%, and the content of impurities (carbon dioxide, carbon monoxide and methane) in the product gas is less than 10 volppm.
  • the acquired gas amount was 12.8 Ndm 3 / min.
  • the recovery rate of hydrogen in the acquired gas was 92.1%.
  • the internal pressure of the gas holder 2A was constant at about 1 kPaG and did not vary. The results of this example are shown in Table 1.
  • each of the four towers was packed with 0.5 dm 3 each of activated carbon and 5A-type zeolite.
  • the fixed capacity type gas tank one having a capacity of about 10 dm 3 was used.
  • the composition of the mixed gas and the gas supply mode were the same as in Example 1.
  • one cycle (steps 1 to 16) consisting of each process shown in FIGS. 3 to 5 was repeated, and the timing of switching each step was the same as in the first embodiment.
  • the maximum pressure inside the adsorption tower in the adsorption process is 2.0 MPaG
  • the minimum pressure (desorption pressure) inside the adsorption tower during the desorption operation is 33 kPaG. It adjusted so that it might become.
  • the hydrogen purity is 99.999 vol%, and the content of impurities (carbon dioxide, carbon monoxide and methane) in the product gas is less than 10 volppm.
  • the acquired gas amount was 12.1 Ndm 3 / min.
  • the recovery rate of hydrogen in the acquired gas was 86.8%.
  • the internal pressure of the gas tank fluctuated in the range from the minimum value 32 kPaG to the maximum value 60 kPaG. The results of this comparative example are shown in Table 2.
  • variable capacity gas holder was about three times the capacity of the adsorption tower, and could be made relatively small.
  • the capacity of the space (gas holder) for storing and discharging the desorption gas derived from the adsorption tower is variable according to the fluctuation of the desorption gas amount.
  • the pressure fluctuation in the entire space through which the desorption gas flows is eliminated and the pressure is maintained at a constant low pressure, so that the decompression regeneration effect is enhanced and the hydrogen recovery rate is improved.
  • the desorption gas is supplied to a reuse destination such as a fuel consumption system, the amount of gas supplied to the reuse destination is stabilized. This leads to an increase in the utilization efficiency of the desorption gas, which can be expected to improve the production efficiency of hydrogen in the entire system related to hydrogen production.

Abstract

This method for purifying hydrogen gas comprises repeating a cycle that includes: a step for introducing a mixed gas into adsorption columns (10A-10D) packed with adsorbent, adsorbing the impurities in the mixed gas on the adsorbent, and delivering hydrogen-enriched gas enriched by hydrogen from the adsorption columns, the adsorption columns (10A-10D) being kept under relatively high pressure, and the mixed gas being introduced by a pressure swing adsorption technique that uses the adsorption columns; and a step for depressurizing the adsorption columns, desorbing the impurities from the adsorbent, and delivering the desorbed gas from the adsorption columns. The gas inside a variable-volume gas holder (2) is discharged while introducing the desorbed gas delivered from the adsorption columns into the gas holder (2) and maintaining a substantially constant pressure inside the gas holder (2).

Description

水素ガスの精製方法及び精製装置Method and apparatus for purifying hydrogen gas
　本発明は、圧力変動吸着法（ＰＳＡ法）を利用して、水素を含む混合ガスから不純物を除去して水素ガスを精製し取得する方法及び装置に関する。 The present invention relates to a method and an apparatus for purifying and obtaining hydrogen gas by removing impurities from a mixed gas containing hydrogen using a pressure fluctuation adsorption method (PSA method).
　近年、水素ガスを燃料とする燃料電池自動車の普及に向けて、その燃料を供給する水素ステーションの整備が必要となり、それに伴い高効率な水素製造技術が求められている。水素をオンサイトで製造する場合、その原料としては、例えば天然ガスやＬＰＧ、メタノールなどの炭化水素系原料が用いられ、この原料を改質することによって水素を製造する。炭化水素系原料の改質により得られるガスは、主成分としての水素の他に、不純物として、一酸化炭素、二酸化炭素、炭化水素などを含む。このような水素を含む混合ガスを精製して高純度の水素ガスを得るための代表的な手法として、圧力変動吸着法（ＰＳＡ法）が用いられる。ＰＳＡ法による水素ガスの精製は、例えば、吸着剤が充填された吸着塔に水素を含む混合ガスを高圧下で導入して不純物を吸着剤に吸着させ、水素が富化された水素富化ガスを導出する工程と、吸着塔内を減圧して吸着剤から不純物を脱着させ、吸着塔から当該脱着ガスを導出する工程と、を含むサイクルを繰り返すことにより行う。 In recent years, with the spread of fuel cell vehicles using hydrogen gas as fuel, it has become necessary to develop a hydrogen station that supplies the fuel, and accordingly, highly efficient hydrogen production technology is required. When hydrogen is produced on-site, as a raw material, for example, a hydrocarbon-based raw material such as natural gas, LPG, or methanol is used, and hydrogen is produced by reforming this raw material. The gas obtained by reforming the hydrocarbon-based raw material contains carbon monoxide, carbon dioxide, hydrocarbons and the like as impurities in addition to hydrogen as a main component. A pressure fluctuation adsorption method (PSA method) is used as a representative method for purifying a mixed gas containing hydrogen to obtain a high-purity hydrogen gas. Purification of hydrogen gas by the PSA method is performed, for example, by introducing a gas mixture containing hydrogen into an adsorption tower packed with an adsorbent under high pressure to adsorb impurities to the adsorbent, and hydrogen-enriched gas enriched with hydrogen. And a step of depressurizing the inside of the adsorption tower to desorb impurities from the adsorbent and deriving the desorption gas from the adsorption tower.
　燃料電池自動車の燃料として水素を製造する場合、得られる水素ガスが高純度であることが求められるとともに、製造効率が少なくとも８０％を超えることが必要とされる。ここで、水素の製造効率とは、原料から水素ガスを製造するために投入したエネルギー（ＰＳＡ法による水素ガスの精製を含む）に対して取得された水素ガスのエネルギーの割合を意味する。水素の製造効率を高めるためには、ＰＳＡ法を利用して水素をより高純度かつ高い回収率（例えば９０％以上）で回収することが望まれている。 When hydrogen is produced as a fuel for a fuel cell vehicle, it is required that the obtained hydrogen gas has high purity, and the production efficiency needs to exceed at least 80%. Here, the hydrogen production efficiency means the ratio of the energy of the hydrogen gas acquired to the energy (including purification of the hydrogen gas by the PSA method) input to produce hydrogen gas from the raw material. In order to increase the production efficiency of hydrogen, it is desired to recover hydrogen with higher purity and higher recovery rate (for example, 90% or more) using the PSA method.
　ＰＳＡ法による水素ガスの精製において、吸着塔から導出される脱着ガスは、一酸化炭素、炭化水素、及び残留水素等を含んでおり、可燃性ガスである。このような可燃性の脱着ガス（オフガス）については、例えば、ガスタンクに一旦蓄えられた後、水素製造用改質反応器のバーナに供給されて燃料として再利用される。バーナにおいて安定した燃焼状態を得るためには、バーナへ略一定の流量にて燃料を供給する必要がある。一方、ＰＳＡ法において導出されるオフガスのガス量は工程によって変動するので、例えばオフガスをガスタンクに一旦収容し、当該ガスタンク内のガスを一定流量で燃料消費系に送るように調整される（例えば、特許文献１，２を参照）。 In the purification of hydrogen gas by the PSA method, the desorption gas derived from the adsorption tower contains carbon monoxide, hydrocarbons, residual hydrogen, and the like, and is a combustible gas. Such combustible desorption gas (off-gas) is, for example, temporarily stored in a gas tank, and then supplied to a burner of a reforming reactor for hydrogen production and reused as fuel. In order to obtain a stable combustion state in the burner, it is necessary to supply fuel to the burner at a substantially constant flow rate. On the other hand, since the amount of off-gas derived in the PSA method varies depending on the process, for example, the off-gas is temporarily stored in a gas tank, and the gas in the gas tank is adjusted to be sent to the fuel consumption system at a constant flow rate (for example, (See Patent Documents 1 and 2).
　特許文献１では、３塔の吸着塔を具備する圧力変動吸着式ガス分離装置（ＰＳＡ装置）によって改質ガスから水素ガスを精製するとともに、吸着塔から導出されるオフガス（脱着ガス）がオフガスタンクに収容される。オフガスタンクに流れるガス量はＰＳＡ法の工程によって変動し、これにともなってオフガスタンク内のガス圧は変動するが、オフガスタンクの下流側には流量調整バルブが設けられており、オフガスタンクの最小圧力を基準に上記流量調整バルブの開度が増減される。ここで、オフガスタンクの最小圧力は０．２ｋｇ／ｃｍ2Ｇ（２０ｋＰａＧ）とされているが、これはオフガスの流量調整の際にガス流れ抵抗が生じることによるものであり、オフガスタンク内の圧力を上記よりも下げることはできない。 In Patent Document 1, hydrogen gas is purified from the reformed gas by a pressure fluctuation adsorption gas separation apparatus (PSA apparatus) having three adsorption towers, and an offgas (desorption gas) derived from the adsorption tower is an offgas tank. Is housed in. The amount of gas flowing to the off-gas tank varies depending on the process of the PSA method, and the gas pressure in the off-gas tank varies with this, but a flow rate adjustment valve is provided downstream of the off-gas tank. The opening degree of the flow rate adjusting valve is increased or decreased based on the pressure. Here, the minimum pressure of the off-gas tank is 0.2 kg / cm 2 G (20 kPaG), which is due to the occurrence of gas flow resistance when adjusting the off-gas flow rate. Cannot be lower than the above.
　特許文献２では、４塔の吸着塔を具備するＰＳＡ装置によって改質ガスから水素ガスを精製するとともに、吸着塔から導出されるオフガス（脱着ガス）がオフガス貯蔵タンクに収容される。オフガス貯蔵タンクの上流側にはバルブが設けられており、当該バルブの開度を段階的に開けて行くことを特徴とする、ブローダウン工程時のオフガス流量の制御方

法が開示されている。特許文献２に開示された方法では、オフガス貯蔵タンク内の圧力上昇をある程度抑制することができるものの、オフガス流量の制御によって圧力損失がおこり、その損失分だけ脱着圧力が上昇することになっていたので、改善が望まれていた。 In Patent Document 2, hydrogen gas is purified from the reformed gas by a PSA apparatus having four adsorption towers, and off-gas (desorption gas) derived from the adsorption tower is stored in an off-gas storage tank. A valve is provided on the upstream side of the off-gas storage tank, and the degree of opening of the valve is opened in stages.

The law is disclosed. In the method disclosed in Patent Document 2, although the pressure increase in the off-gas storage tank can be suppressed to some extent, a pressure loss occurs due to the control of the off-gas flow rate, and the desorption pressure is increased by the loss. So improvement was desired.
　圧力変動吸着法において、一酸化炭素、二酸化炭素、炭化水素などを不純物として含む、水素を主成分とする混合ガスから、高純度の水素をより高い回収率で得るのに、脱着時の圧力をより速く、しかもより低圧にすることがもっとも有効であると知られている。しかしながら、上記従来技術では脱着ガスを溜める空間（オフガスタンク、或いはオフガス貯蔵タンク）が固定されていたので、脱着時の圧力はすぐには低下せず、到達圧力は小さくても２０ｋＰａＧ以上となって、水素回収率を高くすることに限界があった。 In the pressure fluctuation adsorption method, in order to obtain high purity hydrogen at a higher recovery rate from a mixed gas containing hydrogen as a main component, which contains carbon monoxide, carbon dioxide, hydrocarbons, etc. as impurities, the pressure during desorption is reduced. Faster and lower pressures are known to be most effective. However, since the space for storing desorption gas (off-gas tank or off-gas storage tank) is fixed in the above prior art, the pressure at the time of desorption does not decrease immediately, and the ultimate pressure is 20 kPaG or more even if it is small. There was a limit to increasing the hydrogen recovery rate.
特開２００１－１０８０６号公報Japanese Patent Laid-Open No. 2001-10806 特開２００２－３５５５２１号公報JP 2002-355521 A
　本発明は、このような事情のもとで考え出されたものであって、水素を含む混合ガスから水素ガスを精製するにあたり、圧力変動吸着法の利用により高純度水素ガスを回収するとともに、脱着ガス量の変動があってもより低い圧力にまで低下させて、高純度水素ガスの回収率を高めながら、脱着ガスを再利用先に安定したガス圧力で供給するのに適した方法及び装置を提供することを課題としている。 The present invention has been conceived under such circumstances, and in purifying hydrogen gas from a mixed gas containing hydrogen, while collecting high-purity hydrogen gas by using a pressure fluctuation adsorption method, A method and apparatus suitable for supplying a desorption gas to a reuse destination at a stable gas pressure while increasing the recovery rate of high-purity hydrogen gas by reducing it to a lower pressure even if the desorption gas amount varies. It is an issue to provide.
　本発明の第１の側面によって提供される水素ガスの精製方法は、水素及び不純物を含む混合ガスから水素ガスを精製するためのものであり、吸着剤が充填された吸着塔を用いて行う圧力変動吸着法により、上記吸着塔が相対的に高圧である状態にて、上記吸着塔に上記混合ガスを導入して当該混合ガス中の不純物を上記吸着剤に吸着させ、当該吸着塔から水素が富化された水素富化ガスを導出する工程と、上記吸着塔を減圧して上記吸着剤から不純物を脱着させ、当該吸着塔から脱着ガスを導出する工程と、を含むサイクルを繰り返し行い、上記吸着塔から導出された上記脱着ガスを容量が変化するガスホルダに導入しつつ、上記ガスホルダ内の圧力を実質的に一定に保ちながら当該ガスホルダ内のガスを排出することを特徴としている。 The hydrogen gas purification method provided by the first aspect of the present invention is for purifying hydrogen gas from a mixed gas containing hydrogen and impurities, and is a pressure performed using an adsorption tower filled with an adsorbent. By the variable adsorption method, the mixed gas is introduced into the adsorption tower in a state where the adsorption tower is at a relatively high pressure so that impurities in the mixed gas are adsorbed on the adsorbent, and hydrogen is absorbed from the adsorption tower. Repeating a cycle including a step of deriving an enriched hydrogen-enriched gas and a step of depressurizing the adsorption tower to desorb impurities from the adsorbent and desorbing a desorption gas from the adsorption tower, The desorption gas derived from the adsorption tower is introduced into a gas holder whose capacity changes, and the gas in the gas holder is discharged while maintaining the pressure in the gas holder substantially constant.
　本発明者は、上記課題を解決するために、次のような要因解析を行った。まず、脱着操作時のガス圧と脱着ガスの量について分析すると、脱着操作時に吸着塔内の圧力を低下させていくと、吸着塔から導出される脱着ガスの量は、脱着操作時の初期に多く、末期に近づくにつれて減少していく。ここで、脱着ガスが流れるための空間が固定されていると、吸着塔からのガス量が多くなることによってガス流れの抵抗が大きくなり、当該脱着ガスが流れる空間の圧力は脱着操作時に一旦上昇する。一方、脱着操作が進んで吸着塔からのガス量が減少すると、ガス流れ抵抗が小さくなるので、上記空間の圧力は低下していく。したがって、上記空間の容量が固定されていると、脱着ガスの圧力を一気に低下させることが困難であり、また、この圧力を大気圧レベルにまで近づけることには限界があった。そして、吸着塔から導出された脱着ガスについて圧力変動があると、脱着ガスを燃料として再利用するためには圧力を一定にする必要があり、その手段として圧力調節弁や減圧弁を取り付けなければならない。この場合、ガス流れ抵抗を伴うので、脱着ガスの圧力を２０ｋＰａＧ以下の低圧にすることは実質的にできなかった。 The present inventor conducted the following factor analysis in order to solve the above problems. First, when analyzing the gas pressure and the amount of desorption gas during the desorption operation, if the pressure in the adsorption tower is decreased during the desorption operation, the amount of the desorption gas derived from the adsorption tower is reduced to the initial value during the desorption operation. Mostly, it decreases as it approaches the end. Here, if the space for the desorption gas to flow is fixed, the gas flow resistance increases as the amount of gas from the adsorption tower increases, and the pressure in the space for the desorption gas to rise once during the desorption operation. To do. On the other hand, when the desorption operation proceeds and the amount of gas from the adsorption tower decreases, the gas flow resistance decreases, so the pressure in the space decreases. Therefore, if the capacity of the space is fixed, it is difficult to reduce the pressure of the desorption gas at a stretch, and there is a limit in bringing this pressure close to the atmospheric pressure level. And if there is a pressure fluctuation in the desorption gas derived from the adsorption tower, it is necessary to make the pressure constant in order to reuse the desorption gas as fuel. Don't be. In this case, since gas flow resistance is involved, the pressure of the desorption gas cannot be reduced to a low pressure of 20 kPaG or less.
　本発明者は、上記課題を解決するべく鋭意検討したところ、吸着塔から導出される脱着ガスの圧力を下流側でより速く低圧で一定とするためには、当該脱着ガスを、ガスの容量が変化する容量可変式のガスホルダに導入することにより実現可能であることを見出した。また、吸着塔からの脱着ガスの流路が低圧で安定した状態になると、吸着塔内の脱着ガス圧力がより速い速度で低下し、吸着剤から不純物がより速く脱着して減圧再生効果が高まることも見出された。すなわち、脱着ガスが流れる空間（ガスホルダ）を、脱着ガス量に応じて増減させれば、脱着ガスの流路をより低い圧力にて一定化でき、圧力変動吸着法による分離性能を高めることが可能となる。さらに、脱着ガスを燃料して再利用する場合において、余計なガス流れ抵抗の原因となる圧力調整弁や減圧弁を取り付ける必要がない。　 The present inventor has intensively studied to solve the above problems, and in order to make the pressure of the desorption gas derived from the adsorption tower constant at a low pressure more quickly on the downstream side, the desorption gas has a capacity of gas. It has been found that this can be realized by introducing it into a variable capacity gas holder. In addition, when the desorption gas flow path from the adsorption tower becomes stable at a low pressure, the desorption gas pressure in the adsorption tower decreases at a faster rate, and impurities are desorbed faster from the adsorbent, thereby increasing the decompression regeneration effect. It was also found. That is, if the space (gas holder) through which the desorption gas flows is increased or decreased according to the amount of desorption gas, the flow path of the desorption gas can be made constant at a lower pressure, and the separation performance by the pressure fluctuation adsorption method can be improved. It becomes. Furthermore, when the desorbed gas is used as fuel, it is not necessary to attach a pressure regulating valve or pressure reducing valve that causes extra gas flow resistance. *
　好ましくは、上記ガスホルダは、大気との接触を遮断するように上記脱着ガスを収容し、当該脱着ガスの量に応じて変位する仕切部材を備え、上記ガスホルダの容量は、上記仕切部材に下向きに作用する荷重と、上記脱着ガスの圧力により上記仕切部材に上向きに作用する力とが均衡を保ちながら変化する。 Preferably, the gas holder includes a partition member that contains the desorption gas so as to block contact with the atmosphere and is displaced according to the amount of the desorption gas, and the capacity of the gas holder is downward with respect to the partition member. The acting load and the force acting upward on the partition member due to the pressure of the desorption gas change while maintaining a balance.
　本発明の好適な実施形態では、上記仕切部材は、重量体を支持している。より具体的には、上記仕切部材はダイヤフラムの形態であり、上記重量体は当該ダイヤフラムに支持されたピストンの形態である。また、これに代えて、上記仕切部材は膜体の形態であり、上記重量体は当該膜体に支持された錘の形態であってもよい。 In a preferred embodiment of the present invention, the partition member supports a weight body. More specifically, the partition member is in the form of a diaphragm, and the weight body is in the form of a piston supported by the diaphragm. Alternatively, the partition member may be in the form of a film body, and the weight body may be in the form of a weight supported by the film body.
　本発明の別の実施形態では、上記仕切部材は、重量体として構成されている。より具体的には、上記仕切部材は、頂部が閉鎖し、底部が開口したドラムの形態であり、当該ドラムの開口底部が液体中に浸漬されている。 In another embodiment of the present invention, the partition member is configured as a weight body. More specifically, the partition member is in the form of a drum whose top is closed and whose bottom is open, and the bottom of the drum is immersed in the liquid.
　好ましくは、上記吸着塔から脱着ガスを導出する工程における当該吸着塔内の最低圧力は、２０ｋＰａＧ以下である。 Preferably, the minimum pressure in the adsorption tower in the step of desorbing the desorption gas from the adsorption tower is 20 kPaG or less.
　好ましくは、上記ガスホルダから排出されるガスを燃料として他の系に供給する。 Preferably, the gas discharged from the gas holder is supplied as fuel to another system.
　本発明の第２の側面によれば、水素を含む混合ガスから水素ガスを精製するための装置であって、吸着剤が充填された吸着塔を用いて行う圧力変動吸着法により、上記吸着塔に上記混合ガスを導入して当該混合ガス中の不純物を上記吸着剤に吸着させ、当該吸着塔から水素富化ガスを導出し、且つ、上記吸着塔を減圧して上記吸着剤から不純物を脱着させ、当該吸着塔から脱着ガスを導出するための、圧力変動吸着式ガス分離装置と、上記吸着塔から導出された上記脱着ガスを導入し、且つ、排出するための容量可変式のガスホルダと、を備える水素ガスの精製装置が提供される。 According to a second aspect of the present invention, there is provided an apparatus for purifying hydrogen gas from a mixed gas containing hydrogen, wherein the adsorption tower is subjected to a pressure fluctuation adsorption method performed using an adsorption tower filled with an adsorbent. The mixed gas is introduced to adsorb the impurities in the mixed gas to the adsorbent, the hydrogen-enriched gas is led out from the adsorption tower, and the adsorption tower is depressurized to desorb the impurities from the adsorbent. A pressure fluctuation adsorption type gas separation device for deriving the desorption gas from the adsorption tower, a capacity variable type gas holder for introducing and discharging the desorption gas derived from the adsorption tower, An apparatus for purifying hydrogen gas is provided.
　好ましくは、上記ガスホルダは、容器状に構成された本体部と、上記本体部の内部に収容され、上記本体部との間のガスシール状態を維持しつつ変位可能な仕切部材と、を備え上記仕切部材の変位にともない、上記本体部及び上記仕切部材によって区画されたガス収容部に収容されるガスの量が変化する。 Preferably, the gas holder includes a main body configured in a container shape, and a partition member accommodated in the main body and displaceable while maintaining a gas seal state between the main body and the gas holder. With the displacement of the partition member, the amount of gas stored in the gas storage section partitioned by the main body portion and the partition member changes.
　好ましくは、上記仕切部材は、重量体を支持している。より具体的には、上記仕切部材はダイヤフラムの形態であり、上記重量体は当該ダイヤフラムに支持されたピストンの形態である。また、これに代えて、上記仕切部材は膜体の形態であり、上記重量体は当該膜体に支持された錘の形態であってもよい。 Preferably, the partition member supports a weight body. More specifically, the partition member is in the form of a diaphragm, and the weight body is in the form of a piston supported by the diaphragm. Alternatively, the partition member may be in the form of a film body, and the weight body may be in the form of a weight supported by the film body.
　また、上記仕切部材に重量体を支持させることに代えて、上記仕切部材自体を重量体として構成してもよい。より具体的には、上記仕切部材は、頂部が閉鎖し、底部が開口したドラムの形態であり、当該ドラムの開口底部が液体中に浸漬されている。 Moreover, instead of supporting the weight body by the partition member, the partition member itself may be configured as a weight body. More specifically, the partition member is in the form of a drum whose top is closed and whose bottom is open, and the bottom of the drum is immersed in the liquid.
　上記ピストン又は上記ドラムは、上記本体部の内側面に複数のローラを介して案内接触するようにしてもよい。 The piston or the drum may be in contact with the inner surface of the main body through a plurality of rollers.
　本発明のその他の特徴及び利点は、添付図面を参照して以下に行う詳細な説明によって、より明らかとなろう。 Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.
本発明に係る水素ガスの精製方法を実行するのに使用することのできる水素ガス精製装置の概略構成を表す。The schematic structure of the hydrogen gas refinement | purification apparatus which can be used in performing the refinement | purification method of the hydrogen gas which concerns on this invention is represented. ガスホルダの一例の概略構成を示す縦断面図である。It is a longitudinal cross-sectional view which shows schematic structure of an example of a gas holder. 本発明に係る水素ガスの精製方法の各ステップについて、各吸着塔で行われる工程、及び図１に示す水素ガス精製装置の各弁の開閉状態を示す表である。It is a table | surface which shows the process performed by each adsorption tower about each step of the purification method of the hydrogen gas which concerns on this invention, and the open / close state of each valve of the hydrogen gas purification apparatus shown in FIG. 本発明に係る水素ガスの精製方法のステップ１～８におけるガス流れ状態を表す。The gas flow state in steps 1 to 8 of the method for purifying hydrogen gas according to the present invention is shown. 本発明に係る水素ガスの精製方法のステップ９～１６におけるガス流れ状態を表す。The gas flow state in steps 9 to 16 of the method for purifying hydrogen gas according to the present invention is shown. 圧力変動吸着法における脱着圧力及び容量可変式ガスホルダと容量固定式ガスタンクの内部圧力変化を表すグラフである。It is a graph showing the desorption pressure in a pressure fluctuation adsorption method, and the internal pressure change of a capacity variable type gas holder and a capacity fixed type gas tank. ガスホルダの他の例の概略構成を示す縦断面図である。It is a longitudinal cross-sectional view which shows schematic structure of the other example of a gas holder. ガスホルダの他の例の概略構成を示す縦断面図である。It is a longitudinal cross-sectional view which shows schematic structure of the other example of a gas holder.
　以下、本発明の好ましい実施の形態について、図面を参照して具体的に説明する。 Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the drawings.
　図１は、本発明の実施形態に係る水素ガスの精製方法を実行するのに使用することができる水素ガス精製装置の概略構成を示している。水素ガス精製装置Ｘ１は、例えば複数の吸着塔１０Ａ，１０Ｂ，１０Ｃ，１０Ｄと、ガスホルダ２と、これらをつなぎ、ガス流路をなす配管３１～３６と、を備え、水素を含む混合ガスから圧力変動吸着法（ＰＳＡ法）を利用して水素を濃縮精製する。混合ガスは、例えば炭化水素系原料（炭化水素又は炭化水素の誘導体）の水蒸気改質反応により得られた改質ガスである。ここで、炭化水素系原料としては、天然ガス、ＬＰＧ（液化石油ガス）、バイオガス、メタノール、ジメチルエーテルなどが挙げられる。改質ガスには、主成分たる水素の他に、例えば二酸化炭素、一酸化炭素、メタン等が不純物として含まれる。混合ガスの組成の一例を挙げると、水素が７６．０モル％、二酸化炭素が２０．０モル％、一酸化炭素が０．４モル％、メタンが３．６モル％である。 FIG. 1 shows a schematic configuration of a hydrogen gas purification apparatus that can be used to execute a hydrogen gas purification method according to an embodiment of the present invention. The hydrogen gas purification apparatus X1 includes, for example, a plurality of adsorption towers 10A, 10B, 10C, and 10D, a gas holder 2, and pipes 31 to 36 that connect these and form gas passages, and pressure from a mixed gas containing hydrogen. Hydrogen is concentrated and purified using a variable adsorption method (PSA method). The mixed gas is, for example, a reformed gas obtained by a steam reforming reaction of a hydrocarbon-based raw material (hydrocarbon or hydrocarbon derivative). Here, examples of the hydrocarbon-based raw material include natural gas, LPG (liquefied petroleum gas), biogas, methanol, and dimethyl ether. The reformed gas contains, for example, carbon dioxide, carbon monoxide, and methane as impurities in addition to hydrogen as a main component. As an example of the composition of the mixed gas, hydrogen is 76.0 mol%, carbon dioxide is 20.0 mol%, carbon monoxide is 0.4 mol%, and methane is 3.6 mol%.
　吸着塔１０Ａ，１０Ｂ，１０Ｃ，１０Ｄの各々は、両端にガス通過口１１，１２を有し、ガス通過口１１，１２の間において、混合ガスに含まれる不純物（二酸化炭素、一酸化炭素、メタンなど）を選択的に吸着するための吸着剤が充填されている。そのような吸着剤としては、例えば、シリカ、アルミナ、活性炭、及びゼオライトなどが挙げられ、これらは単独で使用しても複数種を併用してもよい。 Each of the adsorption towers 10A, 10B, 10C, and 10D has gas passages 11 and 12 at both ends, and impurities (carbon dioxide, carbon monoxide, methane) contained in the mixed gas between the gas passages 11 and 12. Etc.) is adsorbed for selective adsorption. Examples of such adsorbents include silica, alumina, activated carbon, and zeolite, and these may be used alone or in combination.
　配管３１は、混合ガスを吸着塔１０Ａ，１０Ｂ，１０Ｃ，１０Ｄに供給するためのものであり、主幹路３１’、及び、吸着塔１０Ａ～１０Ｄの各ガス通過口１１側に各々が接続された分枝路３１Ａ，３１Ｂ，３１Ｃ，３１Ｄを有する。分枝路３１Ａ～３１Ｄには、開状態と閉状態との間を切り替える自動弁３１ａ，３１ｂ，３１ｃ，３１ｄが設けられている。配管３１の主幹路３１’には、混合ガスを吸着塔１０Ａ～１０Ｄに圧送するための圧縮機（図示略）を設けてもよい。 The piping 31 is for supplying the mixed gas to the adsorption towers 10A, 10B, 10C, and 10D, and is connected to the main trunk path 31 ′ and the gas passage 11 side of the adsorption towers 10A to 10D. It has branch paths 31A, 31B, 31C, 31D. The branch paths 31A to 31D are provided with automatic valves 31a, 31b, 31c, and 31d for switching between an open state and a closed state. A compressor (not shown) for pumping the mixed gas to the adsorption towers 10A to 10D may be provided on the main path 31 'of the pipe 31.
　配管３２は、各吸着塔１０Ａ～１０Ｄから導出される製品ガス（水素富化ガス）の流路であり、主幹路３２’、及び、吸着塔１０Ａ～１０Ｄの各ガス通過口１２側に各々が接続された分枝路３２Ａ，３２Ｂ，３２Ｃ，３２Ｄを有する。分枝路３２Ａ～３２Ｄには、開状態と閉状態との間を切り替える自動弁３２ａ，３２ｂ，３２ｃ，３２ｄが設けられている。 The piping 32 is a flow path of product gas (hydrogen-enriched gas) derived from each of the adsorption towers 10A to 10D, and is respectively connected to the main passage 32 'and the gas passage 12 side of the adsorption towers 10A to 10D. It has connected branch paths 32A, 32B, 32C, 32D. The branch paths 32A to 32D are provided with automatic valves 32a, 32b, 32c, and 32d that switch between an open state and a closed state.
　配管３３は、配管３２（主幹路３２’）を通流する製品ガスの一部を吸着塔１０Ａ～１０Ｄに戻し供給するためのものであり、配管３２の主幹路３２’に接続された主幹路３３’、及び、吸着塔１０Ａ～１０Ｄの各ガス通過口１２側に各々が接続された分枝路３３Ａ，３３Ｂ，３３Ｃ，３３Ｄを有する。主幹路３３’には、流量調整弁３３１が設けられている。分枝路３３Ａ～３３Ｄには、開状態と閉状態との間を切り替える可能な自動弁３３ａ，３３ｂ，３３ｃ，３３ｄが設けられている。 The pipe 33 is for returning a part of the product gas flowing through the pipe 32 (main trunk path 32 ′) to the adsorption towers 10A to 10D, and is connected to the main trunk path 32 ′ of the pipe 32. 33 ′ and branch paths 33A, 33B, 33C, 33D connected to the gas passage 12 side of the adsorption towers 10A to 10D, respectively. A flow rate adjustment valve 331 is provided in the main trunk path 33 ′. The branch paths 33A to 33D are provided with automatic valves 33a, 33b, 33c, and 33d capable of switching between an open state and a closed state.
　配管３４は、吸着塔１０Ａ～１０Ｄを互いに接続するためのものであり、中間において折り返された主幹路３４’、及び、この主幹路３４’の一方の半経路（「半経路」とは折返し部の一側の経路という意味で、長さが半分という意味ではない）に繋がるとともに、吸着塔１０Ａ～１０Ｄの各ガス通過口１２側に各々が接続された分枝路３４Ａ，３４Ｂ，３４Ｃ，３４Ｄ、及び、主幹路３４’の他方の半経路に繋がり、吸着塔１０Ａ～１０Ｄの各ガス通過口１２側に各々が接続された分枝路３４Ａ’，３４Ｂ’，３４Ｃ’，３４Ｄ’を有する。主幹路３４’の中間部には、流量調整弁３４１が設けられている。分枝路３４Ａ～３４Ｄ及び３４Ａ’～３４Ｄ’には、開状態と閉状態との間を切り替える自動弁３４ａ，３４ｂ，３４ｃ，３４ｄ及び３４ａ’，３４ｂ’，３４ｃ’，３４ｄ’が設けられている。 The pipe 34 is used to connect the adsorption towers 10A to 10D to each other. The pipe 34 'is turned back in the middle, and one half path of the main road 34' ("half path" is a turned-up portion). Branch path 34A, 34B, 34C, 34D each connected to the gas passage 12 side of the adsorption towers 10A-10D. And branch paths 34A ′, 34B ′, 34C ′, and 34D ′ connected to the other half path of the main trunk path 34 ′ and connected to the gas passage 12 side of the adsorption towers 10A to 10D, respectively. A flow rate adjustment valve 341 is provided at an intermediate portion of the main trunk line 34 '. The branch paths 34A to 34D and 34A 'to 34D' are provided with automatic valves 34a, 34b, 34c, 34d and 34a ', 34b', 34c ', 34d' for switching between the open state and the closed state. Yes.
　配管３５は、各吸着塔１０Ａ～１０Ｄから導出されるガス（脱着ガス）をガスホルダ２に導入するためのものであり、ガスホルダ２に接続された主幹路３５’、及び、吸着塔１０Ａ～１０Ｄの各ガス通過口１１側に各々が接続された分枝路３５Ａ，３５Ｂ，３５Ｃ，３５Ｄを有する。分枝路３５Ａ～３５Ｄには、開状態と閉状態との間を切り替える自動弁３５ａ，３５ｂ，３５ｃ，３５ｄが設けられている。 The pipe 35 is for introducing the gas (desorption gas) derived from each of the adsorption towers 10A to 10D into the gas holder 2, and is connected to the main path 35 'connected to the gas holder 2 and the adsorption towers 10A to 10D. Each of the gas passages 11 has branch paths 35A, 35B, 35C, and 35D connected to each side. The branch paths 35A to 35D are provided with automatic valves 35a, 35b, 35c, and 35d for switching between an open state and a closed state.
　配管３６は、ガスホルダ２から排出される脱着ガスの流路であり、ガスホルダ２に接続されている。配管３６は、例えば水素を製造するための改質反応器（図示略）に付属する燃料系などの他の系に接続される。 The pipe 36 is a flow path for desorption gas discharged from the gas holder 2, and is connected to the gas holder 2. The pipe 36 is connected to another system such as a fuel system attached to a reforming reactor (not shown) for producing hydrogen, for example.
　ガスホルダ２は、吸着塔１０Ａ～１０Ｄからの脱着ガスを収容する容量可変式のガスホルダである。本実施形態において、図２に示すように、ガスホルダ２はピストン式であり、本体部２１と、ダイヤフラム２２と、ピストン２３とを備える。 The gas holder 2 is a variable capacity gas holder that accommodates desorption gas from the adsorption towers 10A to 10D. In the present embodiment, as shown in FIG. 2, the gas holder 2 is a piston type, and includes a main body portion 21, a diaphragm 22, and a piston 23.
　本体部２１は、例えば鉄もしくはステンレスなどの金属製であり、円筒容器状とされている。本体部２１は、下部本体２１１及び上部本体２１２を有し、上下に分離可能であるとともに、下部本体２１１及び上部本体２１２のフランジどうしをボルト２１３によって締結することにより一体に組み合わされる。下部本体２１１には、ガス導入口２１４及びガス排出口２１５が設けられている。ガス導入口２１４には、配管３５の主幹路３５’が接続されており、ガス排出口２１５には、配管３６が接続されている。 The main body 21 is made of a metal such as iron or stainless steel and has a cylindrical container shape. The main body 21 has a lower main body 211 and an upper main body 212 and can be separated vertically, and is integrally combined by fastening the flanges of the lower main body 211 and the upper main body 212 with bolts 213. The lower main body 211 is provided with a gas inlet 214 and a gas outlet 215. A main trunk path 35 ′ of a pipe 35 is connected to the gas inlet 214, and a pipe 36 is connected to the gas outlet 215.
　ダイヤフラム２２は、繊維で補強された合成ゴムによって成型されている。ダイヤフラム２２は、円環状の鍔部２２１と、鍔部２２１の内周縁に一端側がつながって延びる円筒状部２２２と、円筒状部２２２の他端側を塞ぐ底部２２３とを有する。ダイヤフラム２２は、鍔部２２１が下部本体２１１及び上部本体２１２のフランジ間に密封状態で挟まれたまま本体部２１の内部に収容されている。ダイヤフラム２２は、下部本体２１１（本体部２１）との間のガスシール状態を維持したまま昇降可能（変位可能）とされており、仕切部材として機能する。ダイヤフラム２２と下部本体２１１（本体部２１）とで区画された領域は、吸着塔１０Ａ～１０Ｄからの脱着ガスを収容するガス収容部２４となる。 The diaphragm 22 is molded from synthetic rubber reinforced with fibers. The diaphragm 22 includes an annular flange 221, a cylindrical portion 222 that extends with one end connected to the inner peripheral edge of the flange 221, and a bottom 223 that closes the other end of the cylindrical portion 222. The diaphragm 22 is accommodated in the main body 21 while the flange portion 221 is sandwiched between the flanges of the lower main body 211 and the upper main body 212 in a sealed state. The diaphragm 22 can be moved up and down (displaceable) while maintaining a gas seal state with the lower main body 211 (main body portion 21), and functions as a partition member. A region partitioned by the diaphragm 22 and the lower main body 211 (main body portion 21) is a gas storage portion 24 that stores the desorption gas from the adsorption towers 10A to 10D.
　ピストン２３は、例えば鉄もしくステンレスなどの金属製であり、ダイヤフラム２２の円筒状部２２２の内側に配置されている。ピストン２３は、上下方向に延びる円筒状のピストン筒部２３１と、ピストン筒部２３１の下端につながるピストン底部２３２とを有する。ピストン２３は、ピストン底部２３２がダイヤフラム２２の底部２２３に対して位置合わせされた状態にて、ダイヤフラム２２に支持されている。 The piston 23 is made of metal such as iron or stainless steel, and is disposed inside the cylindrical portion 222 of the diaphragm 22. The piston 23 has a cylindrical piston cylinder portion 231 extending in the vertical direction and a piston bottom portion 232 connected to the lower end of the piston cylinder portion 231. The piston 23 is supported by the diaphragm 22 in a state where the piston bottom portion 232 is aligned with the bottom portion 223 of the diaphragm 22.
　ピストン筒部２３１の上端近傍には、各々が取付具２３４を介して複数のガイドローラ２３５が設けられている。ガイドローラ２３５は少なくとも３つ（図２には２個しか表れていない）設けられている。好ましくは、これらガイドローラ２３５は、ピストン筒部２３１における周方向に等間隔で配されている。各ガイドローラ２３５は、上部本体２１２の内周面に接触するとともに水平軸周りに回転自在とされている。ピストン筒部２３１の外径寸法は、例えば約１０００ｍｍである。ピストン筒部２３１の外周面と上部本体２１２の内周面との間の隙間は、例えば５０～２００ｍｍとされ、好ましくは１００～１５０ｍｍとされる。ダイヤフラム２２及びこのダイヤフラム２２に支持されたピストン２３は、ガイドローラ２３５によって略一定姿勢を維持しながら、上下動する。 In the vicinity of the upper end of the piston cylinder portion 231, a plurality of guide rollers 235 are provided, each via a fixture 234. At least three guide rollers 235 (only two are shown in FIG. 2) are provided. Preferably, these guide rollers 235 are arranged at equal intervals in the circumferential direction of the piston cylinder portion 231. Each guide roller 235 is in contact with the inner peripheral surface of the upper body 212 and is rotatable about a horizontal axis. The outer diameter dimension of the piston cylinder portion 231 is, for example, about 1000 mm. The gap between the outer peripheral surface of the piston cylinder portion 231 and the inner peripheral surface of the upper main body 212 is, for example, 50 to 200 mm, and preferably 100 to 150 mm. The diaphragm 22 and the piston 23 supported by the diaphragm 22 move up and down while maintaining a substantially constant posture by the guide roller 235.
　吸着塔１０Ａ～１０Ｄからの脱着ガスがガス導入口２１４を介してガス収容部２４（ガスホルダ２内）に導入されると、ガス収容部２４のガス量が変化（増加）し、そのガス量の変化に応じて、ピストン２３はダイヤフラム２２に支持されたまま上昇する。ガス収容部２４の圧力（内圧）は、ピストン２３の重量に応じて決定され、最も低い圧力では１ｋＰａＧ以下（Ｇはゲージ圧を意味する。以下同じ）にまで設定することができる。 When the desorption gas from the adsorption towers 10A to 10D is introduced into the gas storage unit 24 (inside the gas holder 2) via the gas introduction port 214, the gas amount in the gas storage unit 24 changes (increases), In response to the change, the piston 23 rises while being supported by the diaphragm 22. The pressure (internal pressure) of the gas storage unit 24 is determined according to the weight of the piston 23, and can be set to 1 kPaG or less (G means gauge pressure; the same applies hereinafter) at the lowest pressure.
　本実施形態においては、以上のような構成を有する水素ガス精製装置Ｘ１を用いて水素ガスの精製方法を実行することができる。具体的には、水素ガス精製装置Ｘ１の稼働時において、図３に示す態様で自動弁３１ａ～３１ｄ，３２ａ～３２ｄ，３３ａ～３３ｄ，３４ａ～３４ｄ，３４ａ’～３４ｄ’，３５ａ～３５ｄ、及び流量制御弁３３１，３４１を切り替えることにより、装置内において所望のガス流れ状態を実現し、以下のステップ１～１６からなる１サイクルを繰り返す（図３では、各弁の開状態を〇で表し且つ閉状態を×で表す。）。本方法の１サイクルにおいては、吸着塔１０Ａ，１０Ｂ，１０Ｃ，１０Ｄの各々にて、吸着工程、均圧（第１減圧）工程、並流減圧工程、均圧（第２減圧）工程、向流減圧工程、均圧洗浄工程、均圧（第１昇圧）工程、待機工程、均圧（第２昇圧）工程、及び昇圧工程が行われる。本実施形態では、各吸着塔１０Ａ～１０Ｄの下部及び上部には、吸着剤としての活性炭及びゼオライトが等量ずつ積層充填されている。図４及び５は、ステップ１～１６における水素ガス精製装置Ｘ１でのガスの流れ状態を表す。 In the present embodiment, the hydrogen gas purification method can be executed using the hydrogen gas purification apparatus X1 having the above-described configuration. Specifically, during the operation of the hydrogen gas purification apparatus X1, the automatic valves 31a to 31d, 32a to 32d, 33a to 33d, 33a to 33d, 34a to 34d, 34a ′ to 34d ′, 35a to 35d, and the like shown in FIG. By switching the flow control valves 331 and 341, a desired gas flow state is realized in the apparatus, and one cycle consisting of the following steps 1 to 16 is repeated (in FIG. 3, the open state of each valve is represented by ◯ and The closed state is indicated by x). In one cycle of this method, in each of the adsorption towers 10A, 10B, 10C, 10D, an adsorption step, a pressure equalization (first pressure reduction) step, a cocurrent flow pressure reduction step, a pressure equalization (second pressure reduction) step, a countercurrent flow A pressure reduction process, a pressure equalization cleaning process, a pressure equalization (first pressure increase) process, a standby process, a pressure equalization (second pressure increase) process, and a pressure increase process are performed. In the present embodiment, equal amounts of activated carbon and zeolite as adsorbents are stacked and packed in the lower and upper portions of the adsorption towers 10A to 10D. 4 and 5 show the gas flow state in the hydrogen gas purification apparatus X1 in steps 1 to 16. FIG.
　ステップ１では、図３に示すように各弁の開閉状態が選択され、図４（ａ）に示すようなガス流れ状態が達成されて、吸着塔１０Ａにて吸着工程が、吸着塔１０Ｂにて向流減圧工程が、吸着塔１０Ｃにて均圧（第１減圧）工程が、吸着塔１０Ｄにて均圧（第２昇圧）工程が行われる。ステップ１の各工程の操作時間は、例えば２０秒とされる。 In step 1, the open / close state of each valve is selected as shown in FIG. 3, and the gas flow state as shown in FIG. 4 (a) is achieved. The adsorption process is performed in the adsorption tower 10A, and the adsorption tower 10B. In the counter-current decompression step, the pressure equalization (first pressure reduction) step is performed in the adsorption tower 10C, and the pressure equalization (second pressure increase) step is performed in the adsorption tower 10D. The operation time of each step in Step 1 is set to 20 seconds, for example.
　図１及び図４（ａ）を併せて参照するとよく理解できるように、ステップ１では、原料ガス（混合ガス）が、配管３１及びガス通過口１１を介して吸着塔１０Ａに導入される。吸着工程にある吸着塔１０Ａ内は所定の高圧状態に維持されており、混合ガス中の不純物（二酸化炭素、一酸化炭素、メタンなど）が吸着塔１０Ａ内の吸着剤に吸着され、且つ、吸着塔１０Ａのガス通過口１２側から水素ガス濃度の高い製品ガス（水素富化ガス）が導出される。この製品ガスは、配管３２を介して装置外の例えばバッファタンク（図示せず）に回収される。 As can be well understood with reference to FIGS. 1 and 4A together, in step 1, the raw material gas (mixed gas) is introduced into the adsorption tower 10 </ b> A via the pipe 31 and the gas passage port 11. The inside of the adsorption tower 10A in the adsorption process is maintained at a predetermined high pressure state, and impurities (carbon dioxide, carbon monoxide, methane, etc.) in the mixed gas are adsorbed by the adsorbent in the adsorption tower 10A, and are adsorbed. A product gas (hydrogen-enriched gas) having a high hydrogen gas concentration is led out from the gas passage 12 side of the tower 10A. This product gas is recovered via a pipe 32 to, for example, a buffer tank (not shown) outside the apparatus.
　吸着塔１０Ｂでは、塔内を向流方向で減圧することにより吸着剤から不純物が脱着され、吸着塔１０Ｂのガス通過口１１側から脱着ガスが導出される。当該脱着ガスは、配管３５を介してガスホルダ２に導入される。吸着塔１０Ｂは、先に向流減圧工程を行っていたから（図５（ｐ）に示されるステップ１６参照）、前の工程で既に脱着ガスを導出している。したがって、ステップ１において吸着塔１０Ｂから導出される脱着ガスのガス量は少ない。 In the adsorption tower 10B, by depressurizing the inside of the tower in the countercurrent direction, impurities are desorbed from the adsorbent, and desorbed gas is led out from the gas passage 11 side of the adsorption tower 10B. The desorption gas is introduced into the gas holder 2 through the pipe 35. Since the adsorption tower 10B has previously performed the countercurrent depressurization step (see step 16 shown in FIG. 5 (p)), the desorption gas has already been derived in the previous step. Therefore, the amount of desorption gas derived from the adsorption tower 10B in step 1 is small.
　吸着塔１０Ｄでは、吸着塔１０Ｃのガス通過口１２から導出された吸着塔１０Ｃ内のガスが配管３４を介して導入される。吸着塔１０Ｃでは、先に吸着工程を行っていたから（図５（ｐ）に示されるステップ１６参照）、吸着塔１０Ｃの塔内の方が吸着塔１０Ｄの塔内よりも高圧となっている。そのため、吸着塔１０Ｃの塔内ガスを吸着塔１０Ｄに導入することにより、吸着塔Ｃの塔内が減圧されるとともに、吸着塔１０Ｄの塔内が昇圧される。 In the adsorption tower 10D, the gas in the adsorption tower 10C led out from the gas passage 12 of the adsorption tower 10C is introduced through the pipe 34. In the adsorption tower 10C, since the adsorption step has been performed first (see step 16 shown in FIG. 5 (p)), the pressure in the tower of the adsorption tower 10C is higher than that in the tower of the adsorption tower 10D. Therefore, by introducing the gas in the adsorption tower 10C into the adsorption tower 10D, the pressure in the adsorption tower C is reduced and the pressure in the adsorption tower 10D is increased.
　ステップ２では、図３に示すように各弁の開閉状態が選択され、図４（ｂ）に示すようなガス流れ状態が達成されて、吸着塔１０Ａにて引き続き吸着工程が、吸着塔１０Ｂにて均圧洗浄工程が、吸着塔１０Ｃにて並流減圧工程が、吸着塔１０Ｄにて昇圧工程が行われる。ステップ２の各工程の操作時間は、例えば７０秒とされる。 In step 2, the open / close state of each valve is selected as shown in FIG. 3, the gas flow state as shown in FIG. 4B is achieved, and the adsorption step continues to the adsorption tower 10B in the adsorption tower 10A. Thus, the pressure equalization washing process is performed in the adsorption tower 10C, the cocurrent depressurization process is performed, and the adsorption tower 10D is pressurized. The operation time of each step in step 2 is, for example, 70 seconds.
　図１及び図４（ｂ）を併せて参照するとよく理解できるように、ステップ２では、ステップ１から引き続いて、混合ガスが配管３１及びガス通過口１１を介して吸着塔１０Ａに導入されて、吸着塔１０Ａから製品ガスが導出される。製品ガスは、ステップ１と同様に回収されるが、その一部が配管３３を介して吸着塔１０Ｄに導入され、吸着塔１０Ｄの昇圧が行われる。これとともに、ステップ２では、吸着塔１０Ｃのガス通過口１２から導出された吸着塔１０Ｃ内のガスが配管３４を介して吸着塔１０Ｂのガス通過口１２側に導入され、吸着塔１０Ｂの塔内に残留するガス（脱着ガス）がガス通過口１１側から導出される。当該脱着ガスは、配管３５を介してガスホルダ２に導入される。ここで、吸着塔１０Ｂから導出される脱着ガスのガス量は、ステップ１にておいて吸着塔１０Ｂから導出される脱着ガスのガス量よりも多い。 As can be well understood with reference to FIGS. 1 and 4B together, in step 2, the mixed gas is introduced into the adsorption tower 10A via the pipe 31 and the gas passage port 11 following the step 1, Product gas is derived from the adsorption tower 10A. The product gas is recovered in the same manner as in Step 1, but a part of the product gas is introduced into the adsorption tower 10D through the pipe 33, and the pressure of the adsorption tower 10D is increased. At the same time, in step 2, the gas in the adsorption tower 10C led out from the gas passage opening 12 of the adsorption tower 10C is introduced to the gas passage opening 12 side of the adsorption tower 10B via the pipe 34, and the inside of the adsorption tower 10B. The gas (desorption gas) remaining in the gas is led out from the gas passage port 11 side. The desorption gas is introduced into the gas holder 2 through the pipe 35. Here, the gas amount of the desorption gas derived from the adsorption tower 10B is larger than the gas amount of the desorption gas derived from the adsorption tower 10B in Step 1.
　ステップ３では、図３に示すように各弁の開閉状態が選択され、図４（ｃ）に示すようなガス流れ状態が達成されて、吸着塔１０Ａにて引き続き吸着工程が、吸着塔１０Ｂにて均圧（第１昇圧）工程が、吸着塔１０Ｃにて均圧（第２減圧）工程が、吸着塔１０Ｄにて引き続き昇圧工程が行われる。ステップ３の各工程の操作時間は、例えば２０秒とされる。 In step 3, the open / close state of each valve is selected as shown in FIG. 3, the gas flow state as shown in FIG. 4C is achieved, and the adsorption process is continued in the adsorption tower 10A. Thus, the pressure equalization (first pressure increase) step is performed in the adsorption tower 10C, the pressure equalization (second pressure reduction) step is continued, and the pressure increase step is continued in the adsorption tower 10D. The operation time of each step in Step 3 is set to 20 seconds, for example.
　図１及び図４（ｃ）を併せて参照するとよく理解できるように、ステップ３では、ステップ２から引き続いて、混合ガスが配管３１及びガス通過口１１を介して吸着塔１０Ａに導入されて、吸着塔１０Ａから製品ガスが導出される。製品ガスの一部は配管３３を介して吸着塔１０Ｄに導入され、吸着塔１０Ｄの昇圧が引き続き行われる。これとともに、ステップ３では、吸着塔１０Ｃのガス通過口１２から導出された吸着塔１０Ｃ内のガスが配管３４を介して吸着塔１０Ｂのガス通過口１２側に導入される。なお、ステップ３では、吸着塔１０Ａ～１０Ｄのいずれからもガスホルダ２に向かってガスの導出はされない。 As can be understood with reference to FIGS. 1 and 4C together, in Step 3, the mixed gas is introduced into the adsorption tower 10A via the pipe 31 and the gas passage port 11 following Step 2, Product gas is derived from the adsorption tower 10A. Part of the product gas is introduced into the adsorption tower 10D via the pipe 33, and the pressure in the adsorption tower 10D is continuously increased. At the same time, in step 3, the gas in the adsorption tower 10 </ b> C derived from the gas passage opening 12 of the adsorption tower 10 </ b> C is introduced to the gas passage opening 12 side of the adsorption tower 10 </ b> B through the pipe 34. Note that in step 3, no gas is led out toward the gas holder 2 from any of the adsorption towers 10A to 10D.
　ステップ４では、図３に示すように各弁の開閉状態が選択され、図４（ｄ）に示すようなガス流れ状態が達成されて、吸着塔１０Ａにて引き続き吸着工程が、吸着塔１０Ｂにて待機工程が、吸着塔１０Ｃにて向流減圧工程が、吸着塔１０Ｄにて引き続き昇圧工程が行われる。ステップ４の各工程の操作時間は、例えば９０秒とされる。 In step 4, the open / close state of each valve is selected as shown in FIG. 3, the gas flow state shown in FIG. 4 (d) is achieved, and the adsorption step continues to the adsorption tower 10B in the adsorption tower 10A. Then, the standby process is performed, the countercurrent pressure reducing process is performed in the adsorption tower 10C, and the pressure increasing process is continued in the adsorption tower 10D. The operation time for each step in step 4 is, for example, 90 seconds.
　図１及び図４（ｄ）を併せて参照するとよく理解できるように、ステップ４では、ステップ３から引き続いて、混合ガスが配管３１及びガス通過口１１を介して吸着塔１０Ａに導入されて、吸着塔１０Ａから製品ガスが導出される。製品ガスの一部は配管３３を介して吸着塔１０Ｄに導入され、吸着塔１０Ｄの昇圧が引き続き行われる。吸着塔１０Ｂについては、先のステップ３で一度目の均圧（昇圧）を受けているが、後のステップ５にて二度目の均圧（昇圧）を受けるために待機する。吸着塔１０Ｃについては、向流方向で減圧することにより吸着剤から不純物が脱着され、吸着塔１０Ｃのガス通過口１１側から脱着ガスが導出される。吸着塔１０Ｃは、ステップ１～３において続けて減圧されており、ステップ４の開始時に吸着塔１０Ｃ内の圧力はかなり低くなっている。そして、ステップ４では、吸着塔１０Ｃはさらに減圧されるので、吸着剤から脱着するガスの量は多く、吸着塔１０Ｃから導出される脱着ガスの量も比較的に多い。 As can be well understood with reference to FIGS. 1 and 4 (d) together, in step 4, following step 3, the mixed gas is introduced into the adsorption tower 10 </ b> A via the pipe 31 and the gas passage port 11. Product gas is derived from the adsorption tower 10A. Part of the product gas is introduced into the adsorption tower 10D via the pipe 33, and the pressure in the adsorption tower 10D is continuously increased. The adsorption tower 10B receives the first pressure equalization (pressure increase) in the previous step 3, but waits to receive the second pressure equalization (pressure increase) in the subsequent step 5. As for the adsorption tower 10C, by depressurizing in the counterflow direction, impurities are desorbed from the adsorbent, and desorption gas is led out from the gas passage 11 side of the adsorption tower 10C. The adsorption tower 10C is continuously depressurized in steps 1 to 3, and the pressure in the adsorption tower 10C is considerably low at the start of step 4. In Step 4, since the adsorption tower 10C is further depressurized, the amount of gas desorbed from the adsorbent is large, and the amount of desorption gas derived from the adsorption tower 10C is relatively large.
　ステップ１～４は、ステップ１～１６により構成される１サイクルの１／４に相当し、そのステップ１～４の工程時間は、合計２００秒である。 Steps 1 to 4 correspond to ¼ of one cycle composed of steps 1 to 16, and the process time of steps 1 to 4 is a total of 200 seconds.
　ステップ５～８においては、図３に示すように各弁の開閉状態が選択され、図４（ｅ）～（ｈ）に示したように、吸着塔１０Ａでは、ステップ１～４における吸着塔１０Ｃと同様にして均圧（第１減圧）工程、並流減圧工程、均圧（第２減圧）工程、向流減圧工程が行われ、吸着塔１０Ｂでは、ステップ１～４における吸着塔１０Ｄと同様にして均圧（第２昇圧）工程、昇圧工程が行われる。吸着塔１０Ｃでは、ステップ１～４における吸着塔１０Ｂと同様にして向流減圧工程、均圧洗浄工程、均圧（第１昇圧）工程、待機工程が行われ、吸着塔１０Ｄでは、ステップ１～４における吸着塔１０Ａと同様にして吸着工程が行われる。 In steps 5 to 8, the open / closed state of each valve is selected as shown in FIG. 3, and as shown in FIGS. 4 (e) to (h), the adsorption tower 10A in the adsorption tower 10C in steps 1 to 4 is selected. The pressure equalization (first pressure reduction) step, the cocurrent pressure reduction step, the pressure equalization (second pressure reduction) step, and the countercurrent pressure reduction step are performed. The adsorption tower 10B is the same as the adsorption tower 10D in steps 1 to 4. Thus, a pressure equalization (second pressure increase) step and a pressure increase step are performed. In the adsorption tower 10C, a counter-current depressurization process, a pressure equalization washing process, a pressure equalization (first pressure increase) process, and a standby process are performed in the same manner as in the adsorption tower 10B in steps 1 to 4, and in the adsorption tower 10D, steps 1 to The adsorption step is performed in the same manner as the adsorption tower 10A in FIG.
　ステップ９～１２においては、図３に示すように各弁の開閉状態が選択され、図５（ｉ）～（ｌ）に示したように、吸着塔１０Ａでは、ステップ１～４における吸着塔１０Ｂと同様にして向流減圧工程、均圧洗浄工程、均圧（第１昇圧）工程、待機工程が行われ、吸着塔１０Ｂでは、ステップ１～４における吸着塔１０Ａと同様にして吸着工程が行われる。吸着塔１０Ｃでは、ステップ１～４における吸着塔１０Ｄと同様にして均圧（第２昇圧）工程、昇圧工程が行われ、吸着塔１０Ｄでは、ステップ１～４における吸着塔１０Ｃと同様にして均圧（第１減圧）工程、並流減圧工程、均圧（第２減圧）工程、向流減圧工程が行われる。 In steps 9 to 12, the open / close state of each valve is selected as shown in FIG. 3, and in the adsorption tower 10A, as shown in FIGS. 5 (i) to (l), the adsorption tower 10B in steps 1 to 4 is selected. The counter-current depressurization step, the pressure equalization washing step, the pressure equalization (first pressure increase) step, and the standby step are performed in the same manner as described above. In the adsorption tower 10B, the adsorption step is performed in the same manner as the adsorption tower 10A in steps 1 to 4. Is called. In the adsorption tower 10C, the pressure equalization (second pressure increase) process and the pressure increase process are performed in the same manner as the adsorption tower 10D in steps 1 to 4, and the adsorption tower 10D is equalized in the same manner as the adsorption tower 10C in steps 1 to 4. A pressure (first pressure reduction) step, a cocurrent pressure reduction step, a pressure equalization (second pressure reduction) step, and a countercurrent pressure reduction step are performed.
　ステップ１３～１６においては、図３に示すように各弁の開閉状態が選択され、図５（ｍ）～（ｐ）に示したように、吸着塔１０Ａでは、ステップ１～４における吸着塔１０Ｄと同様にして均圧（第２昇圧）工程、昇圧工程が行われ、吸着塔１０Ｂでは、ステップ１～４における吸着塔１０Ｃと同様にして均圧（第１減圧）工程、並流減圧工程、均圧（第２減圧）工程、向流減圧工程が行われる。吸着塔１０Ｃでは、ステップ１～４における吸着塔１０Ａと同様にして吸着工程が行われ、吸着塔１０Ｄでは、ステップ１～４における吸着塔１０Ｂと同様にして向流減圧工程、均圧洗浄工程、均圧（第１昇圧）工程、待機工程が行われる。 In steps 13 to 16, the open / close state of each valve is selected as shown in FIG. 3, and as shown in FIGS. 5 (m) to (p), in the adsorption tower 10A, the adsorption tower 10D in steps 1 to 4 is selected. The pressure equalization (second pressure increase) step and the pressure increase step are performed in the same manner as described above. In the adsorption tower 10B, the pressure equalization (first pressure reduction) step, the cocurrent flow pressure reduction step, A pressure equalization (second pressure reduction) step and a countercurrent pressure reduction step are performed. In the adsorption tower 10C, an adsorption process is performed in the same manner as the adsorption tower 10A in steps 1 to 4, and in the adsorption tower 10D, a counter-current decompression process, a pressure equalization washing process, A pressure equalization (first pressure increase) step and a standby step are performed.
　そして、以上に説明したステップ１～１６が吸着塔１０Ａ～１０Ｄの各々において繰り返し行われることにより、吸着塔１０Ａ～１０Ｄのいずれかに混合ガスが連続的に導入され、且つ、水素ガス濃度の高い製品ガスが連続的に取得される。 The steps 1 to 16 described above are repeatedly performed in each of the adsorption towers 10A to 10D, so that the mixed gas is continuously introduced into any of the adsorption towers 10A to 10D and the hydrogen gas concentration is high. Product gas is acquired continuously.
　本実施形態において、図４及び５に示す操作工程（ステップ１～１６）によって吸着塔１０Ａ～１０Ｄのいずれかから脱着ガスが導出されると、当該脱着ガスはガス導入口２１４を介してガスホルダ２に導入されつつガス排出口２１５から排出される。ガスホルダ２は容量可変式であるため、吸着塔１０Ａ～１０Ｄから導出される脱着ガスのガス量に応じて、ガスが流れる空間（ガスホルダ２）の容量が増減する。 In this embodiment, when the desorption gas is led out from any of the adsorption towers 10A to 10D by the operation steps (steps 1 to 16) shown in FIGS. 4 and 5, the desorption gas is supplied to the gas holder 2 through the gas inlet 214. The gas is discharged from the gas outlet 215 while being introduced into the gas outlet. Since the capacity of the gas holder 2 is variable, the capacity of the space (gas holder 2) through which the gas flows increases or decreases according to the amount of desorbed gas derived from the adsorption towers 10A to 10D.
　例えば、図２を参照すると理解されるように、ガスホルダ２に導入されるガス量が多くなると、ガスホルダ２内においてダイヤフラム２２と下部本体２１１（本体部２１）とで囲まれた領域（ガス収容部２４）の内部圧力が上昇しようとする。そうすると、ピストン２３の重量（荷重）に抗して、ダイヤフラム２２及びダイヤフラム２２に支持されたピストン２３が押し上げられ、ガスが蓄えられる。図２においては、ピストン２３が上昇した状態を仮想線で表す。一方、ガスホルダ２に導入されるガス量が減少、或いは無くなると、ガス排出口２１５からガスが排出されることによってピストン２３が下降する。なお、図２において、ピストン２３が最も下位にある実線で示す状態でのガス収容部２４の容積と、ピストン２３が最も上位にある仮想線で示す状態でのガス収容部２４の容積との差が、ガスホルダ２（ガス収容部２４）における増減可能な容量になる。 For example, as understood with reference to FIG. 2, when the amount of gas introduced into the gas holder 2 increases, a region (gas storage portion) surrounded by the diaphragm 22 and the lower main body 211 (main body portion 21) in the gas holder 2. 24) The internal pressure is going to rise. If it does so, the piston 23 supported by the diaphragm 22 and the diaphragm 22 will be pushed up against the weight (load) of the piston 23, and gas will be stored. In FIG. 2, the state in which the piston 23 is raised is represented by a virtual line. On the other hand, when the amount of gas introduced into the gas holder 2 decreases or disappears, the gas is discharged from the gas discharge port 215 and the piston 23 is lowered. In FIG. 2, the difference between the volume of the gas storage unit 24 in the state indicated by the solid line with the piston 23 at the lowest level and the volume of the gas storage unit 24 in the state indicated by the imaginary line with the piston 23 at the highest level. However, it becomes the capacity | capacitance which can be increased / decreased in the gas holder 2 (gas accommodating part 24).
　以上から理解されるように、ガスホルダ２においては、ダイヤフラム２２に対して下向きに作用するピストン２３の荷重と、脱着ガスの圧力によりダイヤフラム２２に対して上向きに作用する力とが均衡を保ちながら、ガスホルダ２（ガス収容部２４）の容量が変化する。これにより、吸着塔１０Ａ～１０Ｄから導出される脱着ガスのガス量が変動しても、当該脱着ガス量に応じてガスホルダ２の容量が増減し、ガスホルダ２内の圧力が変化せずに実質的に一定に保たれる。 As understood from the above, in the gas holder 2, the load of the piston 23 acting downward on the diaphragm 22 and the force acting upward on the diaphragm 22 by the pressure of the desorption gas are kept in balance. The capacity | capacitance of the gas holder 2 (gas accommodating part 24) changes. Thereby, even if the gas amount of the desorption gas derived from the adsorption towers 10A to 10D fluctuates, the capacity of the gas holder 2 increases or decreases according to the desorption gas amount, and the pressure in the gas holder 2 does not change substantially. Kept constant.
　このようにガスホルダ２内の圧力が実質的に一定に保たれると、ガス排出口２１５を介して排出される脱着ガス量も実質的に一定となる。このため、ガス流れ抵抗の原因となる流量調整弁等を取り付けることなく、ガスホルダ２からの脱着ガスの流量が実質的に一定に保たれる。脱着ガスは、一酸化炭素、炭化水素、及び残留水素等を含む可燃性ガスである。したがって、ガスホルダ２から一定流量にて排出される脱着ガスは、改質反応器に付属するバーナなどの他の系に燃料として安定供給することができる。また、流量調整弁等が不要である構成は、ガスホルダ２内の圧力をより低下させるうえで好ましい。 As described above, when the pressure in the gas holder 2 is kept substantially constant, the amount of desorbed gas discharged through the gas discharge port 215 becomes substantially constant. For this reason, the flow rate of the desorption gas from the gas holder 2 is kept substantially constant without attaching a flow rate adjusting valve or the like that causes gas flow resistance. The desorption gas is a combustible gas containing carbon monoxide, hydrocarbons, residual hydrogen, and the like. Therefore, the desorption gas discharged from the gas holder 2 at a constant flow rate can be stably supplied as fuel to other systems such as a burner attached to the reforming reactor. In addition, a configuration that does not require a flow rate adjustment valve or the like is preferable for further reducing the pressure in the gas holder 2.
　本実施形態と異なり、容量固定式のガスタンクに脱着ガスを蓄える場合には、吸着塔からの脱着ガスのガス量の変動によりガスタンク内の圧力が変動する。この場合、脱着操作時に吸着塔内を減圧して当該吸着塔からの脱着ガスのガス量が多くなると、ガスタンク内の圧力が上昇するので、脱着操作時の当該吸着塔におけるガス圧（脱着圧力）を低下させ難い。これに対し、本実施形態では、上述のように吸着塔１０Ａ～１０Ｄからの脱着ガスのガス量が多くなってもガスホルダ２内の圧力は実質的に一定に維持されるため、脱着操作時における吸着塔１０Ａ～１０Ｄの減圧の速度が速くなるといった効果を得ることができる。その結果、吸着塔１０Ａ～１０Ｄの減圧再生効果が高まり、製品ガスの取得量が増えるとともに水素回収率が高まる。 Unlike the present embodiment, when the desorption gas is stored in the fixed capacity type gas tank, the pressure in the gas tank fluctuates due to the fluctuation of the gas amount of the desorption gas from the adsorption tower. In this case, when the pressure in the adsorption tower is reduced during the desorption operation and the amount of the desorption gas from the adsorption tower increases, the pressure in the gas tank increases. Therefore, the gas pressure (desorption pressure) in the adsorption tower during the desorption operation Is difficult to lower. On the other hand, in the present embodiment, as described above, the pressure in the gas holder 2 is maintained substantially constant even when the amount of the desorption gas from the adsorption towers 10A to 10D increases. The effect that the depressurization speed of the adsorption towers 10A to 10D is increased can be obtained. As a result, the decompression regeneration effect of the adsorption towers 10A to 10D is enhanced, and the amount of product gas acquired is increased and the hydrogen recovery rate is increased.
　また、本実施形態と異なり、容量固定式のガスタンクに脱着ガスを蓄える場合、内部の空間容量が固定されている。このため、吸着塔からの脱着ガスのガス量の変動について、ガスタンク内の圧力変化を伴うことになる。したがって、容量固定式ガスタンクでは、ガス量の変動の影響を抑制するには、比較的に大きな空間容量が必要になり、例えば吸着塔の容量の１０倍程度の空間容量を要する。これに対し、本実施形態のような容量可変式のガスホルダ２に脱着ガスを蓄える場合、圧力変化を伴わずに、変動したガス量に応じてダイヤフラム２２（仕切部材）を変位させることで、ガスホルダ２の容量を増減できる。これにより、ガスホルダ２においては、最大の容量として吸着塔１０Ａ～１０Ｄの容量の３倍程度確保しておけばよく、ガス貯蔵空間の無駄をなくすことができる。 Also, unlike the present embodiment, when the desorption gas is stored in a fixed capacity type gas tank, the internal space capacity is fixed. For this reason, the change in the gas amount of the desorption gas from the adsorption tower is accompanied by a pressure change in the gas tank. Therefore, in the fixed capacity type gas tank, in order to suppress the influence of the fluctuation of the gas amount, a relatively large space capacity is required. For example, a space capacity about 10 times the capacity of the adsorption tower is required. On the other hand, when the desorption gas is stored in the variable capacity type gas holder 2 as in this embodiment, the gas holder is displaced by displacing the diaphragm 22 (partition member) according to the changed gas amount without causing a pressure change. 2 capacity can be increased or decreased. Thereby, in the gas holder 2, it is sufficient to secure about 3 times the capacity of the adsorption towers 10A to 10D as the maximum capacity, and the waste of the gas storage space can be eliminated.
　図６は、４塔の吸着塔を用いて水素を精製するための圧力変動吸着操作において、脱着ガス用配管に容量可変式ガスホルダを取り付けた場合と、容量固定式ガスタンクを取り付けた場合の圧力プロファイルを示す。容量可変式ガスホルダとして図２に示されたピストン式のガスホルダ２を用い、ガスホルダ２（ガス収容部２４）の容量を吸着塔の容量の約３倍とした。一方、容量固定式ガスタンクの容量は吸着塔容量の約１０倍とした。混合ガスとしては、水素が７６．０モル％、二酸化炭素が２０．０モル％、一酸化炭素が０．４モル％、メタンが３．６モル％の組成のものを用いた。吸着圧力は２ＭＰａＧ、脱着圧力は３３ｋＰａＧになるようにした。 FIG. 6 shows pressure profiles when a variable capacity gas holder is attached to a desorption gas pipe and when a fixed capacity gas tank is attached in a pressure fluctuation adsorption operation for purifying hydrogen using four adsorption towers. Indicates. The piston-type gas holder 2 shown in FIG. 2 was used as the variable-capacity gas holder, and the capacity of the gas holder 2 (gas storage unit 24) was about three times the capacity of the adsorption tower. On the other hand, the capacity of the fixed capacity type gas tank was about 10 times the capacity of the adsorption tower. As the mixed gas, one having a composition of 76.0 mol% hydrogen, 20.0 mol% carbon dioxide, 0.4 mol% carbon monoxide, and 3.6 mol% methane was used. The adsorption pressure was 2 MPaG and the desorption pressure was 33 kPaG.
　図６に示した容量可変式ガスホルダに関する圧力は、上述のステップ１～１６のうちステップ１～４について表し、容量固定式ガスタンクに関する圧力についても、ステップ１～４について表す。吸着塔内の圧力（脱着圧力）については、ステップ１～４における吸着塔１０Ｃについて表す。 The pressure related to the variable capacity gas holder shown in FIG. 6 is expressed for steps 1 to 4 in the above steps 1 to 16, and the pressure related to the fixed capacity gas tank is also expressed for steps 1 to 4. The pressure in the adsorption tower (desorption pressure) is shown for the adsorption tower 10C in steps 1 to 4.
　図６から理解されるように、容量固定式ガスタンクの内部圧力は、ステップ２，４の開始後に当該ガスタンク内に脱着ガスが導入されるとこれに伴って上昇し、ステップ２では６０ｋＰａＧ（図６における５０秒経過時）に達し、ステップ４では５８ｋＰａＧ（図６における１２０秒経過時）に達した。一方、容量可変式ガスホルダの内部圧力は、ステップ１～４を通じて約３２ｋＰａＧであり、実質的に一定に保たれた。 As understood from FIG. 6, the internal pressure of the fixed-capacity gas tank rises along with the introduction of the desorption gas into the gas tank after the start of steps 2 and 4, and in step 2, the pressure increases to 60 kPaG (FIG. 6). In step 4, the pressure reached 58 kPaG (120 seconds in FIG. 6). On the other hand, the internal pressure of the variable capacity gas holder was about 32 kPaG through steps 1 to 4, and was kept substantially constant.
　また、図６から理解されるように、吸着塔内の圧力（脱着圧力）については、容量固定式ガスタンクの場合には、ステップ３からステップ４に切り替わる時点（図６における１１０秒経過時）から緩やかに低下し、最低圧力まで低下するのに約４０秒間を要した。その一方、容量可変式ガスホルダの場合、吸着塔内の圧力（脱着圧力）は、ステップ３からステップ４に切り替わる時点から一気に低下して１０秒以内のかなり速い速度で最低圧力まで低下した。 In addition, as understood from FIG. 6, the pressure (desorption pressure) in the adsorption tower is determined from the time when switching from Step 3 to Step 4 (when 110 seconds have elapsed in FIG. 6) in the case of a fixed capacity type gas tank. It slowly dropped and took about 40 seconds to reach the lowest pressure. On the other hand, in the case of a variable capacity gas holder, the pressure in the adsorption tower (desorption pressure) decreased at a stroke from the time of switching from step 3 to step 4 and decreased to the minimum pressure at a fairly high speed within 10 seconds.
　図７及び図８は、容量可変式のガスホルダの他の例を示す。 7 and 8 show other examples of variable capacity type gas holders.
　図７に示すガスホルダ２Ａは、胴体２１Ａと、胴体２１Ａの内部に収容されたバルーン２２Ａと、錘２３Ａとを備え、バルーン式として構成されたものである。胴体２１Ａは、例えば鉄もしくはステンレスなどの金属製であり、全体として円筒状とされ、且つ上部に形成された開口を塞ぐための天板２１６を有する。胴体２１Ａの下部には、入口ガスノズル２１７及び出口ガスノズル２１８が設けられている。入口ガスノズル２１７には、配管３５の主幹路３５’（図１）が接続されており、出口ガスノズル２１８には、配管３６（図１）が接続されている。バルーン２２Ａは、繊維で補強された合成ゴムによって成型されており、膨張時に半球状となる膜体とされている。バルーン２２Ａの周縁部は、胴体２１Ａの内面に設けられた円環状の取付金具２１９に固定されている。バルーン２２Ａは、胴体２１Ａとの間のガスシール状態を維持したまま上下動可能（変位可能）とされており、仕切部材として機能する。そして、バルーン２２Ａと胴体２１Ａの下部とで区画された領域は、吸着塔１０Ａ～１０Ｄからの脱着ガスを収容するためのガス収容部２４とされている。錘２３Ａは、ガスホルダ２Ａの内部圧力を調整するためのものであり、バルーン２２Ａの中央上面に固定されている。ガス収容部２４の圧力（内圧）は、錘２３Ａの重量に応じて決定され、最も低い圧力では１ｋＰａＧ以下にまで設定することができる。 7 includes a body 21A, a balloon 22A accommodated in the body 21A, and a weight 23A, and is configured as a balloon type. The body 21A is made of a metal such as iron or stainless steel, has a cylindrical shape as a whole, and has a top plate 216 for closing an opening formed in the upper portion. An inlet gas nozzle 217 and an outlet gas nozzle 218 are provided below the body 21A. The main gas passage 35 ′ (FIG. 1) of the pipe 35 is connected to the inlet gas nozzle 217, and the pipe 36 (FIG. 1) is connected to the outlet gas nozzle 218. The balloon 22A is molded from a synthetic rubber reinforced with fibers, and is a film that becomes hemispherical when expanded. The peripheral edge of the balloon 22A is fixed to an annular mounting bracket 219 provided on the inner surface of the body 21A. The balloon 22A is movable up and down (displaceable) while maintaining the gas seal state between the balloon 21A and functions as a partition member. A region partitioned by the balloon 22A and the lower part of the body 21A is a gas storage unit 24 for storing the desorption gas from the adsorption towers 10A to 10D. The weight 23A is for adjusting the internal pressure of the gas holder 2A, and is fixed to the central upper surface of the balloon 22A. The pressure (internal pressure) of the gas storage unit 24 is determined according to the weight of the weight 23A, and can be set to 1 kPaG or less at the lowest pressure.
　入口ガスノズル２１７を介してガスホルダ２Ａに導入されるガス量が多くなると、ガスホルダ２Ａ内においてバルーン２２Ａと胴体２１Ａとで囲まれた領域（ガス収容部２４）の内部圧力が上昇しようとする。そうすると、錘２３Ａの重量（荷重）に抗して、バルーン２２Ａが上方に膨らみ、ガスが蓄えられる。図７においては、バルーン２２Ａが膨らんだ状態を仮想線で表す。一方、ガスホルダ２Ａに導入されるガス量が減少、或いは無くなると、出口ガスノズル２１８からガスが排出されることによってバルーン２２Ａが下方に萎む。図７において、バルーン２２Ａが最も萎んだ実線で示す状態でのガス収容部２４の容積と、バルーン２２Ａが最も膨らんだ仮想線で示す状態でのガス収容部２４の容積との差が、ガスホルダ２Ａ（ガス収容部２４）における増減可能な容量になる。 When the amount of gas introduced into the gas holder 2A through the inlet gas nozzle 217 increases, the internal pressure of the region (gas storage unit 24) surrounded by the balloon 22A and the body 21A in the gas holder 2A tends to increase. Then, the balloon 22A bulges upward against the weight (load) of the weight 23A, and gas is stored. In FIG. 7, the state where the balloon 22A is inflated is represented by a virtual line. On the other hand, when the amount of gas introduced into the gas holder 2A decreases or disappears, the gas is discharged from the outlet gas nozzle 218, whereby the balloon 22A is deflated downward. In FIG. 7, the difference between the volume of the gas storage portion 24 in the state indicated by the solid line where the balloon 22A is most deflated and the volume of the gas storage portion 24 in the state indicated by the imaginary line where the balloon 22A is expanded most is the gas holder 2A. The capacity in the (gas storage unit 24) can be increased or decreased.
　このような構成のガスホルダ２Ａにおいては、バルーン２２Ａに対して下向きに作用する錘２３Ａの荷重と、脱着ガスの圧力によりバルーン２２Ａに対して上向きに作用する力とが均衡を保ちながら、ガスホルダ２Ａ（ガス収容部２４）の容量が変化する。これにより、吸着塔１０Ａ～１０Ｄから導出される脱着ガスのガス量が変動しても、当該脱着ガス量に応じてガスホルダ２Ａの容量が増減し、ガスホルダ２Ａ内の圧力が変化せずに実質的に一定に保たれる。 In the gas holder 2A having such a configuration, the load of the weight 23A acting downward with respect to the balloon 22A and the force acting upward with respect to the balloon 22A due to the pressure of the desorption gas are kept in balance, while the gas holder 2A ( The capacity of the gas storage part 24) changes. Thereby, even if the gas amount of the desorption gas derived from the adsorption towers 10A to 10D fluctuates, the capacity of the gas holder 2A increases or decreases in accordance with the desorption gas amount, and the pressure in the gas holder 2A does not change substantially. Kept constant.
　図８に示すガスホルダ２Ｂは、円筒容器状の胴体２５と、胴体２５の内側に収容されたドラム２６とを備える。胴体２５は、例えば鉄もしくはステンレスなどの金属製であり、この胴体２５の内部には、水、或いは活性の低い有機液体（オイル）などの液体２７が充填されている。液体２７は、胴体２５に設けられた給水ノズル２５１から導入されつつオーバーフローノズル２５２から連続的に外部に排出され、例えば液体２７である水が蒸発しても減少分が補充されるようになっている。液体２７が汚れた場合には、排出ノズル２５３から排出して入れ替えることができる。 The gas holder 2B shown in FIG. 8 includes a cylindrical container-shaped body 25 and a drum 26 accommodated inside the body 25. The body 25 is made of metal such as iron or stainless steel, and the body 25 is filled with a liquid 27 such as water or an organic liquid (oil) having low activity. The liquid 27 is continuously discharged from the overflow nozzle 252 while being introduced from the water supply nozzle 251 provided in the body 25, and for example, the reduced amount is replenished even when the water as the liquid 27 evaporates. Yes. When the liquid 27 becomes dirty, it can be discharged from the discharge nozzle 253 and replaced.
　ドラム２６は、例えば鉄もしくはステンレスなどの金属製であり、頂部が覆われた円筒状とされている。ドラム２６は、液体２７に浸かっており、当該液体２７によって内部空間と外部とが遮断されている。ドラム２６は、仕切部材の一例である。ドラム２６の下部及び上部には、複数ずつのローラ２６１，２６２が設けられている。各ローラ２６１は、胴体２５の内周面に接触するとともに上下に移動する。各ローラ２６２は、胴体２５の外周部に分散して配置された複数の筒状のサポート部材２８をガイドとして上下に移動する。これにより、ドラム２６は、ローラ２６１，２６２によって略一定姿勢を維持しながら、上下動する。 The drum 26 is made of a metal such as iron or stainless steel, and has a cylindrical shape with the top covered. The drum 26 is immersed in the liquid 27, and the internal space and the outside are blocked by the liquid 27. The drum 26 is an example of a partition member. A plurality of rollers 261 and 262 are provided below and above the drum 26. Each roller 261 contacts the inner peripheral surface of the body 25 and moves up and down. Each roller 262 moves up and down using a plurality of cylindrical support members 28 arranged on the outer periphery of the body 25 as guides. As a result, the drum 26 moves up and down while maintaining a substantially constant posture by the rollers 261 and 262.
　胴体２５の下部には、入口ガスノズル２５４及び出口ガスノズル２５５が設けられている。入口ガスノズル２５４には、配管３５の主幹路３５’が接続されており、出口ガスノズル２５５には、配管３６が接続されている。入口ガスノズル２５４及び出口ガスノズル２５５は、それぞれ、ドラム２６の内側において立ち上がり、上端が液体２７の液面より上位において開口している。 An inlet gas nozzle 254 and an outlet gas nozzle 255 are provided at the lower part of the body 25. The main gas passage 35 ′ of the pipe 35 is connected to the inlet gas nozzle 254, and the pipe 36 is connected to the outlet gas nozzle 255. Each of the inlet gas nozzle 254 and the outlet gas nozzle 255 rises inside the drum 26, and the upper end opens above the liquid level of the liquid 27.
　ドラム２６は、液体２７によって当該液体２７の液面との間の内部空間のガスシール状態を維持したまま上下動可能とされている。そして、ドラム２６と液体２７とで区画された空間は、吸着塔１０Ａ～１０Ｄからの脱着ガスを収容するためのガス収容空間２９とされている。ドラム２６は、ガスホルダ２Ｂの内部圧力を調整する機能を有する。ガス収容空間２９の圧力（内圧）は、液体２７に浮かぶドラム２６の重量に応じて決定され、最も低い圧力では１ｋＰａＧ以下にまで設定することができる。 The drum 26 can be moved up and down by the liquid 27 while maintaining the gas seal state of the internal space between the liquid 27 and the liquid surface. The space partitioned by the drum 26 and the liquid 27 is a gas storage space 29 for storing the desorption gas from the adsorption towers 10A to 10D. The drum 26 has a function of adjusting the internal pressure of the gas holder 2B. The pressure (internal pressure) of the gas storage space 29 is determined according to the weight of the drum 26 floating in the liquid 27, and can be set to 1 kPaG or less at the lowest pressure.
　入口ガスノズル２５４を介してガスホルダ２Ｂに導入されるガス量が多くなると、ガスホルダ２Ｂ内においてドラム２６と液体２７とで囲まれた領域（ガス収容空間２９）の内部圧力が上昇しようとする。そうすると、ドラム２６の重量（荷重）に抗して、ドラム２６が上昇し、ガスが蓄えられる。図８においては、ドラム２６が上昇した状態を仮想線で表す。一方、ガスホルダ２Ｂに導入されるガス量が減少、或いは無くなると、出口ガスノズル２５５からガスが排出されることによってドラム２６が下降する。図８において、ドラム２６が最も下位にある実線で示す状態でのガス収容空間２９の容積と、ドラム２６が最も上位にある仮想線で示す状態でのガス収容空間２９の容積との差が、ガスホルダ２Ｂ（ガス収容空間２９）における増減可能な容量になる。 When the amount of gas introduced into the gas holder 2B through the inlet gas nozzle 254 increases, the internal pressure of the region (gas storage space 29) surrounded by the drum 26 and the liquid 27 in the gas holder 2B tends to increase. Then, the drum 26 rises against the weight (load) of the drum 26, and gas is stored. In FIG. 8, the state where the drum 26 is raised is represented by a virtual line. On the other hand, when the amount of gas introduced into the gas holder 2B is reduced or eliminated, the gas is discharged from the outlet gas nozzle 255, and the drum 26 is lowered. In FIG. 8, the difference between the volume of the gas storage space 29 in the state indicated by the solid line with the drum 26 at the lowest level and the volume of the gas storage space 29 in the state indicated by the virtual line with the drum 26 at the highest level is The capacity of the gas holder 2B (the gas storage space 29) can be increased or decreased.
　このような構成のガスホルダ２Ｂにおいては、ドラム２６に対して下向きに作用するドラム２６の荷重と、脱着ガスの圧力によりドラム２６に対して上向きに作用する力とが均衡を保ちながら、ガスホルダ２Ｂ（ガス収容空間２９）の容量が変化する。これにより、吸着塔１０Ａ～１０Ｄから導出される脱着ガスのガス量が変動しても、当該脱着ガス量に応じてガスホルダ２Ｂの容量が増減し、ガスホルダ２Ｂ内の圧力が変化せずに実質的に一定に保たれる。 In the gas holder 2B having such a configuration, the load of the drum 26 that acts downward with respect to the drum 26 and the force that acts upward with respect to the drum 26 due to the pressure of the desorption gas are balanced, while the gas holder 2B ( The capacity of the gas storage space 29) changes. Thereby, even if the gas amount of the desorption gas derived from the adsorption towers 10A to 10D fluctuates, the capacity of the gas holder 2B increases / decreases in accordance with the desorption gas amount, and the pressure in the gas holder 2B does not change substantially. Kept constant.
　以上、本発明の具体的な実施形態を説明したが、本発明はこれに限定されるものではなく、発明の思想から逸脱しない範囲内で種々の変更が可能である。例えば、本発明に係る水素ガスの精製方法を実行する装置におけるガス流路をなす配管の構成については、上記実施形態と異なる構成を採用してもよい。吸着塔の数については上記実施形態で示した４塔式だけに限定されるものではなく、３塔以下、或いは５塔以上の場合でも同様の効果が期待できる。 Although specific embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the invention. For example, a configuration different from that of the above-described embodiment may be adopted for the configuration of the piping that forms the gas flow path in the apparatus that executes the method for purifying hydrogen gas according to the present invention. The number of adsorption towers is not limited to the four-column type shown in the above embodiment, and the same effect can be expected even when there are three or less towers or five or more towers.
　次に、本発明の有用性を実施例及び比較例により説明する。 Next, the usefulness of the present invention will be described with reference to examples and comparative examples.
　　〔実施例１〕
　図１に示す概略構成を有する水素ガス精製装置Ｘ１を使用して、図３～図５に示す吸着工程、均圧（第１減圧）工程、並流減圧工程、均圧（第２減圧）工程、向流減圧工程、均圧洗浄工程、均圧（第１昇圧）工程、待機工程、均圧（第２昇圧）工程、及び昇圧工程からなる１サイクル（ステップ１～１６）を吸着塔１０Ａ，１０Ｂ，１０Ｃ，１０Ｄにおいて繰り返すことにより、所定の混合ガスから、水素ガスを濃縮精製した。 [Example 1]
Using the hydrogen gas purification apparatus X1 having the schematic configuration shown in FIG. 1, the adsorption process, pressure equalization (first pressure reduction) process, cocurrent pressure reduction process, pressure equalization (second pressure reduction) process shown in FIGS. , A counter flow depressurization step, a pressure equalization cleaning step, a pressure equalization (first pressure increase) step, a standby step, a pressure equalization (second pressure increase) step, and a pressure increase step are performed in one cycle (steps 1 to 16). By repeating at 10B, 10C, and 10D, hydrogen gas was concentrated and purified from a predetermined mixed gas.
　本実施例において使用した水素ガス精製装置Ｘ１の吸着塔１０Ａ，１０Ｂ，１０Ｃ，１０Ｄの各々は、ステンレス製で円筒形状（内径３７ｍｍ，内寸高さ１，０００ｍｍ）を有し、容量が約１ｄｍ3であった。各吸着塔内には、吸着剤として活性炭と５Ａ型ゼオライトをそれぞれ０.５ｄｍ3（見掛け体積）ずつ積層充填した。ガスホルダについては、図７に示したバルーン式（容量可変式）のガスホルダ２Ａを使用し、容量が約３ｄｍ3のものを使用した。混合ガスの組成は、水素が７６．０モル％、二酸化炭素が２０．０モル％、一酸化炭素が０．４モル％、メタンが３．６モル％であった。この混合ガスを、水素ガス精製装置Ｘ１に対して１８．３Ｎｄｍ3／ｍｉｎ（Ｎは標準状態を表す。以下同じ。）の流量で供給し続けた。本実施例では、吸着塔１０Ａ，１０Ｂ，１０Ｃ，１０Ｄの各々において、ステップ１，２，３，４がそれぞれ２０秒間、７０秒間、２０秒間、９０秒間でステップ１～４の合計が２００秒間であり、ステップ１～１６からなる１サイクルのサイクルタイムは、８００秒間であった。吸着工程における吸着塔１０Ａ～１０Ｄの内部の最高圧力は２．０ＭＰａＧとし、脱着操作時（向流減圧工程，均圧洗浄工程）における吸着塔１０Ａ～１０Ｄの内部の最低圧力（脱着圧力）は３３ｋＰａＧとなるように調整した。 Each of the adsorption towers 10A, 10B, 10C, and 10D of the hydrogen gas purification apparatus X1 used in this example is made of stainless steel and has a cylindrical shape (inner diameter: 37 mm, inner height: 1,000 mm), and a capacity of about 1 dm. It was 3 . Each adsorption tower was packed with 0.5 dm 3 (apparent volume) of activated carbon and 5A-type zeolite as adsorbents. As the gas holder, the balloon type (volume variable type) gas holder 2A shown in FIG. 7 was used, and the one having a capacity of about 3 dm 3 was used. The composition of the mixed gas was 76.0 mol% for hydrogen, 20.0 mol% for carbon dioxide, 0.4 mol% for carbon monoxide, and 3.6 mol% for methane. This mixed gas was continuously supplied to the hydrogen gas purification apparatus X1 at a flow rate of 18.3 Ndm 3 / min (N represents a standard state, the same applies hereinafter). In this embodiment, in each of the adsorption towers 10A, 10B, 10C, and 10D, steps 1, 2, 3, and 4 are respectively 20 seconds, 70 seconds, 20 seconds, and 90 seconds, and the total of steps 1 to 4 is 200 seconds. Yes, the cycle time of one cycle consisting of steps 1 to 16 was 800 seconds. The maximum pressure inside the adsorption towers 10A to 10D in the adsorption process is 2.0 MPaG, and the minimum pressure (desorption pressure) inside the adsorption towers 10A to 10D during the desorption operation (countercurrent depressurization process, pressure equalization washing process) is 33 kPaG. It adjusted so that it might become.
　このような条件で行った本実施例において濃縮精製された製品ガスについて、水素純度は９９.９９９ｖｏｌ％であり、製品ガス中の不純物（二酸化炭素、一酸化炭素及びメタン）の含有率は１００ｖｏｌｐｐｍ未満であり、取得ガス量は１２．３Ｎｄｍ3／ｍｉｎであった。取得ガスにおける水素の回収率は、８８．２％であった。本実施例において、ガスホルダ２Ａの内部圧力は、ほぼ３２ｋＰａＧで一定となり変動しなかった。本実施例の結果を表１に示した。 With respect to the product gas concentrated and purified in this example performed under such conditions, the hydrogen purity is 99.999 vol%, and the content of impurities (carbon dioxide, carbon monoxide and methane) in the product gas is less than 100 vol ppm. The acquired gas amount was 12.3 Ndm 3 / min. The recovery rate of hydrogen in the acquired gas was 88.2%. In this example, the internal pressure of the gas holder 2A was constant at about 32 kPaG and did not vary. The results of this example are shown in Table 1.
　　〔実施例２〕
　脱着圧力を２０ｋＰａＧとした以外は、実施例１と同様にして、混合ガスから水素ガスの精製を行った。このような条件で行った本実施例において濃縮精製された製品ガスについて、水素純度は９９.９９９ｖｏｌ％であり、製品ガス中の不純物（二酸化炭素、一酸化炭素及びメタン）の含有率は１０ｖｏｌｐｐｍ未満であり、取得ガス量は１２．５５Ｎｄｍ3／ｍｉｎであった。取得ガスにおける水素の回収率は、９０．０％であった。本実施例において、ガスホルダ２Ａの内部圧力は、ほぼ２０ｋＰａＧで一定となり変動しなかった。本実施例の結果を表１に示した。 [Example 2]
Hydrogen gas was purified from the mixed gas in the same manner as in Example 1 except that the desorption pressure was 20 kPaG. The product gas concentrated and purified in this example performed under such conditions has a hydrogen purity of 99.999 vol%, and the content of impurities (carbon dioxide, carbon monoxide and methane) in the product gas is less than 10 volppm. The acquired gas amount was 12.55 Ndm 3 / min. The recovery rate of hydrogen in the acquired gas was 90.0%. In this example, the internal pressure of the gas holder 2A was constant at about 20 kPaG and did not change. The results of this example are shown in Table 1.
　　〔実施例３〕
　脱着圧力を１０ｋＰａＧとした以外は、実施例１と同様にして、混合ガスから水素ガスの精製を行った。このような条件で行った本実施例において濃縮精製された製品ガスについて、水素純度は９９.９９９ｖｏｌ％であり、製品ガス中の不純物（二酸化炭素、一酸化炭素及びメタン）の含有率は１０ｖｏｌｐｐｍ未満であり、取得ガス量は１２．６Ｎｄｍ3／ｍｉｎであった。取得ガスにおける水素の回収率は、９０．５％であった。本実施例において、ガスホルダ２Ａの内部圧力は、ほぼ１０ｋＰａＧで一定となり変動しなかった。本実施例の結果を表１に示した。 Example 3
Hydrogen gas was purified from the mixed gas in the same manner as in Example 1 except that the desorption pressure was 10 kPaG. The product gas concentrated and purified in this example performed under such conditions has a hydrogen purity of 99.999 vol%, and the content of impurities (carbon dioxide, carbon monoxide and methane) in the product gas is less than 10 volppm. The acquired gas amount was 12.6 Ndm 3 / min. The recovery rate of hydrogen in the acquired gas was 90.5%. In this example, the internal pressure of the gas holder 2A was constant at about 10 kPaG and did not fluctuate. The results of this example are shown in Table 1.
　　〔実施例４〕
　脱着圧力を１ｋＰａＧとした以外は、実施例１と同様にして、混合ガスから水素ガスの精製を行った。このような条件で行った本実施例において濃縮精製された製品ガスについて、水素純度は９９.９９９ｖｏｌ％であり、製品ガス中の不純物（二酸化炭素、一酸化炭素及びメタン）の含有率は１０ｖｏｌｐｐｍ未満であり、取得ガス量は１２．８Ｎｄｍ3／ｍｉｎであった。取得ガスにおける水素の回収率は、９２．１％であった。本実施例において、ガスホルダ２Ａの内部圧力は、ほぼ１ｋＰａＧで一定となり変動しなかった。本実施例の結果を表１に示した。 Example 4
Hydrogen gas was purified from the mixed gas in the same manner as in Example 1 except that the desorption pressure was 1 kPaG. The product gas concentrated and purified in this example performed under such conditions has a hydrogen purity of 99.999 vol%, and the content of impurities (carbon dioxide, carbon monoxide and methane) in the product gas is less than 10 volppm. The acquired gas amount was 12.8 Ndm 3 / min. The recovery rate of hydrogen in the acquired gas was 92.1%. In this example, the internal pressure of the gas holder 2A was constant at about 1 kPaG and did not vary. The results of this example are shown in Table 1.
　　〔比較例１〕
　上記実施例１で使用した水素ガス精製装置Ｘ１におけるガスホルダ２Ａを容量固定式のガスタンクに代えた水素ガス精製装置を使用して、圧力吸着変動法により、図３～図５に示す各工程からなる１サイクル（ステップ１～１６）を繰り返すことにより、所定の混合ガスから水素ガスを濃縮精製した。ガスタンクに関する相違点を除いた本比較例使用の精製装置の構成は、水素ガス精製装置Ｘ１と同様である。 [Comparative Example 1]
Using the hydrogen gas purification apparatus in which the gas holder 2A in the hydrogen gas purification apparatus X1 used in the first embodiment is replaced with a fixed capacity type gas tank, the steps shown in FIGS. By repeating one cycle (steps 1 to 16), hydrogen gas was concentrated and purified from a predetermined mixed gas. The configuration of the refining device used in this comparative example, excluding the differences related to the gas tank, is the same as that of the hydrogen gas refining device X1.
　本比較例において、４塔の各吸着塔内には、活性炭と５Ａ型ゼオライトをそれぞれ０.５ｄｍ3ずつ積層充填した。容量固定式ガスタンクとしては、容量が約１０ｄｍ3のものを使用した。混合ガスの組成及びガス供給態様は、上記実施例１と同様とした。本比較例では、図３～図５に示す各工程からなる１サイクル（ステップ１～１６）を繰り返し、各ステップの切り替えのタイミングは上記実施例１と同様とした。本比較例において、吸着工程における吸着塔の内部の最高圧力は２．０ＭＰａＧとし、脱着操作時（向流減圧工程，均圧洗浄工程）における吸着塔の内部の最低圧力（脱着圧力）は３３ｋＰａＧとなるように調整した。 In this comparative example, each of the four towers was packed with 0.5 dm 3 each of activated carbon and 5A-type zeolite. As the fixed capacity type gas tank, one having a capacity of about 10 dm 3 was used. The composition of the mixed gas and the gas supply mode were the same as in Example 1. In this comparative example, one cycle (steps 1 to 16) consisting of each process shown in FIGS. 3 to 5 was repeated, and the timing of switching each step was the same as in the first embodiment. In this comparative example, the maximum pressure inside the adsorption tower in the adsorption process is 2.0 MPaG, and the minimum pressure (desorption pressure) inside the adsorption tower during the desorption operation (countercurrent depressurization process, pressure equalization washing process) is 33 kPaG. It adjusted so that it might become.
　このような条件で行った本比較例において濃縮精製された製品ガスについて、水素純度は９９.９９９ｖｏｌ％であり、製品ガス中の不純物（二酸化炭素、一酸化炭素及びメタン）の含有率は１０ｖｏｌｐｐｍ未満であり、取得ガス量は１２．１Ｎｄｍ3／ｍｉｎであった。取得ガスにおける水素の回収率は、８６．８％であった。本比較例において、ガスタンクの内部圧力は、最小値３２ｋＰａＧから最大値６０ｋＰaＧの範囲で変動した。本比較例の結果を表２に示した。 About the product gas concentrated and purified in this comparative example performed under such conditions, the hydrogen purity is 99.999 vol%, and the content of impurities (carbon dioxide, carbon monoxide and methane) in the product gas is less than 10 volppm. The acquired gas amount was 12.1 Ndm 3 / min. The recovery rate of hydrogen in the acquired gas was 86.8%. In this comparative example, the internal pressure of the gas tank fluctuated in the range from the minimum value 32 kPaG to the maximum value 60 kPaG. The results of this comparative example are shown in Table 2.
　　〔比較例２〕
　脱着圧力を２０ｋＰａＧとした以外は、比較例１と同様にして、混合ガスから水素ガスの精製を行った。このような条件で行った本比較例において濃縮精製された製品ガスについて、水素純度は９９.９９９ｖｏｌ％であり、製品ガス中の不純物（二酸化炭素、一酸化炭素及びメタン）の含有率は１０ｖｏｌｐｐｍ未満であり、取得ガス量は１２．２Ｎｄｍ3／ｍｉｎであった。取得ガスにおける水素の回収率は、８７．７％であった。本比較例において、ガスタンクの内部圧力は、最小値２０ｋＰａＧから最大値４７ｋＰaＧの範囲で変動した。本比較例の結果を表２に示した。 [Comparative Example 2]
Hydrogen gas was purified from the mixed gas in the same manner as in Comparative Example 1 except that the desorption pressure was 20 kPaG. About the product gas concentrated and purified in this comparative example performed under such conditions, the hydrogen purity is 99.999 vol%, and the content of impurities (carbon dioxide, carbon monoxide and methane) in the product gas is less than 10 volppm. The acquired gas amount was 12.2 Ndm 3 / min. The recovery rate of hydrogen in the acquired gas was 87.7%. In this comparative example, the internal pressure of the gas tank fluctuated in the range from the minimum value 20 kPaG to the maximum value 47 kPaG. The results of this comparative example are shown in Table 2.
　　〔比較例３〕
　脱着圧力を１０ｋＰａＧとした以外は、比較例１と同様にして、混合ガスから水素ガスの精製を行った。このような条件で行った本比較例において濃縮精製された製品ガスについて、水素純度は９９.９９９ｖｏｌ％であり、製品ガス中の不純物（二酸化炭素、一酸化炭素及びメタン）の含有率は１０ｖｏｌｐｐｍ未満であり、取得ガス量は１２．３Ｎｄｍ3／ｍｉｎであった。取得ガスにおける水素の回収率は、８８．１％であった。本比較例において、ガスタンクの内部圧力は、最小値１０ｋＰａＧから最大値３７ｋＰaＧの範囲で変動した。本比較例の結果を表２に示した。 [Comparative Example 3]
Hydrogen gas was purified from the mixed gas in the same manner as in Comparative Example 1 except that the desorption pressure was 10 kPaG. About the product gas concentrated and purified in this comparative example performed under such conditions, the hydrogen purity is 99.999 vol%, and the content of impurities (carbon dioxide, carbon monoxide and methane) in the product gas is less than 10 volppm. The acquired gas amount was 12.3 Ndm 3 / min. The recovery rate of hydrogen in the acquired gas was 88.1%. In this comparative example, the internal pressure of the gas tank fluctuated in a range from a minimum value of 10 kPaG to a maximum value of 37 kPaG. The results of this comparative example are shown in Table 2.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　比較例１～３では、タンク容量が吸着塔の容量の１０倍の容量固定式ガスタンクを用いたが、脱着圧力を低く安定させることはできなかった。これ対し、実施例１～４においては、容量が吸着塔容量の３倍の容量可変式のガスホルダを用いることにより、ガスホルダ内部の圧力変動をなくすことができた。これにより、脱着圧力をより低い圧力（１ｋＰａＧレベル）まで下げることが可能となり、水素回収率が向上した。脱着圧力を２０ｋＰａＧ以下とした場合、水素回収率は９０％以上になり、良い結果が得られた。また、圧力変動のない脱着ガスについては、容量可変式ガスホルダから実質的に一定のガス量で排出され、例えば改質反応器の燃料消費系に安定的に送ることができた。なお、容量可変式のガスホルダの容量については、吸着塔の容量の約３倍で済み、比較的小さくすることができた。 In Comparative Examples 1 to 3, a fixed capacity gas tank having a tank capacity 10 times the capacity of the adsorption tower was used, but the desorption pressure could not be stabilized low. On the other hand, in Examples 1 to 4, the pressure fluctuation inside the gas holder could be eliminated by using a variable capacity gas holder whose capacity is three times the capacity of the adsorption tower. As a result, the desorption pressure can be lowered to a lower pressure (1 kPaG level), and the hydrogen recovery rate is improved. When the desorption pressure was 20 kPaG or less, the hydrogen recovery rate was 90% or more, and good results were obtained. Further, the desorbed gas having no pressure fluctuation was discharged from the variable capacity gas holder at a substantially constant gas amount, and could be stably sent to the fuel consumption system of the reforming reactor, for example. Note that the capacity of the variable capacity gas holder was about three times the capacity of the adsorption tower, and could be made relatively small.
　水素を含む混合ガスからの圧力変動吸着法を利用した水素ガスの精製において、吸着塔から導出される脱着ガスを貯蔵し、排出する空間（ガスホルダ）が脱着ガス量の変動に合わせて容量可変される。これにより、脱着ガスが流れる空間全体の圧力変動がなくなり一定の低圧で保持されるので、減圧再生効果が高まり水素回収率が向上する。また、それによって、脱着ガスを燃料消費系などの再利用先に供給する場合、再利用先への供給ガス量が安定する。このことは、脱着ガスの利用効率を高めることに繋がり、それによって水素製造に係る系全体における水素の製造効率向上を期待することができる。 In the purification of hydrogen gas using a pressure fluctuation adsorption method from a mixed gas containing hydrogen, the capacity of the space (gas holder) for storing and discharging the desorption gas derived from the adsorption tower is variable according to the fluctuation of the desorption gas amount. The As a result, the pressure fluctuation in the entire space through which the desorption gas flows is eliminated and the pressure is maintained at a constant low pressure, so that the decompression regeneration effect is enhanced and the hydrogen recovery rate is improved. Further, when the desorption gas is supplied to a reuse destination such as a fuel consumption system, the amount of gas supplied to the reuse destination is stabilized. This leads to an increase in the utilization efficiency of the desorption gas, which can be expected to improve the production efficiency of hydrogen in the entire system related to hydrogen production.
Ｘ１　　　　水素ガス精製装置
１０Ａ，１０Ｂ，１０Ｃ，１０Ｄ　　吸着塔
１１，１２　　ガス通過口
２，２Ａ，２Ｂ　　ガスホルダ
２１　　　　本体部
２１Ａ　　　胴体
２１１　　　下部本体
２１２　　　上部本体
２１４　　　ガス導入口
２１５　　　ガス排出口
２１６　　　天板
２１７　　　入口ガスノズル
２１８　　　出口ガスノズル
２２　　　　ダイヤフラム（仕切部材）
２２Ａ　　　バルーン（仕切部材）
２２１　　　鍔部
２２２　　　円筒状部
２２３　　　底部
２３　　　　ピストン（錘部）
２３Ａ　　　錘
２３１　　　ピストン筒部
２３２　　　ピストン底部
２３４　　　取付具
２３５　　　ガイドローラ
２４　　　　ガス収容部
２５　　　　胴体
２５４　　　入口ガスノズル
２５５　　　出口ガスノズル
２６　　　　ドラム（仕切部材、錘部）
２６１，２６２　　ローラ
２７　　　　液体
２８　　　　サポート部材
２９　　　　ガス収容空間
３１～３６　　配管
３１’，３２’，３３’，３４’，３５’　　主幹路
３１Ａ～３１Ｄ，３２Ａ～３２Ｄ，３３Ａ～３３Ｄ，３４Ａ～３４Ｄ，３４Ａ’～３４Ｄ’，３５Ａ～３５Ｄ　　分岐路
３１ａ～３１ｄ，３２ａ～３２ｄ，３３ａ～３３ｄ，３４ａ～３４ｄ，３４ａ’～３４ｄ’，３５ａ～３５ｄ　　自動弁
３３１，３４１　　流量調整弁 X1 Hydrogen gas purifiers 10A, 10B, 10C, 10D Adsorption towers 11, 12 Gas passage ports 2, 2A, 2B Gas holder 21 Body 21A Body 211 Lower body 212 Upper body 214 Gas inlet 215 Gas outlet 216 Top plate 217 Inlet Gas nozzle 218 Outlet gas nozzle 22 Diaphragm (partition member)
22A Balloon (partition member)
221 flange 222 cylindrical portion 223 bottom 23 piston (weight)
23A Weight 231 Piston cylinder part 232 Piston bottom part 234 Attaching tool 235 Guide roller 24 Gas storage part 25 Body 254 Inlet gas nozzle 255 Outlet gas nozzle 26 Drum (partition member, weight part)
261, 262 Roller 27 Liquid 28 Support member 29 Gas storage space 31-36 Piping 31 ', 32', 33 ', 34', 35 'Main trunk paths 31A-31D, 32A-32D, 33A-33D, 34A-34D, 34A '-34D', 35A-35D Branch passages 31a-31d, 32a-32d, 33a-33d, 34a-34d, 34a'-34d ', 35a- 35d Automatic valves 331, 341 Flow control valves

Claims (16)

  1. 　水素及び不純物を含む混合ガスから水素ガスを精製するための方法であって、
    　当該方法は、吸着剤が充填された吸着塔を用いて行う圧力変動吸着法により、上記吸着塔が相対的に高圧である状態にて、上記吸着塔に上記混合ガスを導入して当該混合ガス中の不純物を上記吸着剤に吸着させ、当該吸着塔から水素が富化された水素富化ガスを導出する工程と、上記吸着塔を減圧して上記吸着剤から不純物を脱着させ、当該吸着塔から脱着ガスを導出する工程と、を含むサイクルを繰り返し行い、
    　上記吸着塔から導出された上記脱着ガスを容量が変化するガスホルダに導入しつつ、上記ガスホルダ内の圧力を実質的に一定に保ちながら当該ガスホルダ内のガスを排出する、水素ガスの精製方法。     A method for purifying hydrogen gas from a mixed gas containing hydrogen and impurities,
    In this method, the mixed gas is introduced into the adsorption tower by a pressure fluctuation adsorption method using an adsorption tower filled with an adsorbent while the adsorption tower is at a relatively high pressure. Adsorbing impurities in the adsorbent and deriving a hydrogen-enriched gas enriched in hydrogen from the adsorption tower, depressurizing the adsorption tower to desorb impurities from the adsorbent, A process including the step of desorbing the desorption gas from
    A method for purifying hydrogen gas, wherein the gas in the gas holder is discharged while the pressure in the gas holder is kept substantially constant while introducing the desorption gas derived from the adsorption tower into a gas holder having a variable capacity.
  2. 　上記ガスホルダは、大気との接触を遮断するように上記脱着ガスを収容し、当該脱着ガスの量に応じて変位する仕切部材を備え、
    　上記ガスホルダの容量は、上記仕切部材に下向きに作用する荷重と、上記脱着ガスの圧力により上記仕切部材に上向きに作用する力とが均衡を保ちながら変化する、請求項１に記載の水素ガスの精製方法。     The gas holder contains the desorption gas so as to block contact with the atmosphere, and includes a partition member that is displaced according to the amount of the desorption gas,
    The capacity of the gas holder is changed while maintaining a balance between a load acting downward on the partition member and a force acting upward on the partition member due to the pressure of the desorption gas. Purification method.
  3. 　上記仕切部材は、重量体を支持している、請求項２に記載の水素ガスの精製方法。 The method for purifying hydrogen gas according to claim 2, wherein the partition member supports a weight body.
  4. 　上記仕切部材はダイヤフラムの形態であり、上記重量体は当該ダイヤフラムに支持されたピストンの形態である、請求項３に記載の水素ガスの精製方法。 4. The method for purifying hydrogen gas according to claim 3, wherein the partition member is in the form of a diaphragm, and the weight body is in the form of a piston supported by the diaphragm.
  5. 　上記仕切部材は膜体の形態であり、上記重量体は当該膜体に支持された錘の形態である、請求項３に記載の水素ガスの精製方法。 The method for purifying hydrogen gas according to claim 3, wherein the partition member is in the form of a film body, and the weight body is in the form of a weight supported by the film body.
  6. 　上記仕切部材は、重量体として構成されている、請求項２に記載の水素ガスの精製方法。 The method for purifying hydrogen gas according to claim 2, wherein the partition member is configured as a weight body.
  7. 　上記仕切部材は、頂部が閉鎖し、底部が開口したドラムの形態であり、当該ドラムの開口底部が液体中に浸漬されている、請求項６に記載の水素ガスの精製方法。 The method for purifying hydrogen gas according to claim 6, wherein the partition member is in the form of a drum with the top closed and the bottom open, and the open bottom of the drum is immersed in a liquid.
  8. 　上記吸着塔から脱着ガスを導出する工程における当該吸着塔内の最低圧力は、２０ｋＰａＧ以下である、請求項１ないし７のいずれかに記載の水素ガスの精製方法。 The method for purifying hydrogen gas according to any one of claims 1 to 7, wherein the minimum pressure in the adsorption tower in the step of desorbing the desorption gas from the adsorption tower is 20 kPaG or less.
  9. 　上記ガスホルダから排出されるガスを燃料として他の系に供給する、請求項１ないし８のいずれかに記載の水素ガスの精製方法。 The method for purifying hydrogen gas according to any one of claims 1 to 8, wherein the gas discharged from the gas holder is supplied as fuel to another system.
  10. 　水素及び不純物を含む混合ガスから水素ガスを精製するための装置であって、
    　吸着剤が充填された吸着塔を用いて行う圧力変動吸着法により、上記吸着塔に上記混合ガスを導入して当該混合ガス中の不純物を上記吸着剤に吸着させ、当該吸着塔から水素富化ガスを導出し、且つ、上記吸着塔を減圧して上記吸着剤から不純物を脱着させ、当該吸着塔から脱着ガスを導出するための、圧力変動吸着式ガス分離装置と、
    　上記吸着塔から導出された上記脱着ガスを導入し、且つ、排出するための容量可変式のガスホルダと、を備える、水素ガスの精製装置。     An apparatus for purifying hydrogen gas from a mixed gas containing hydrogen and impurities,
    The mixed gas is introduced into the adsorption tower by the pressure fluctuation adsorption method using an adsorption tower filled with an adsorbent, and the impurities in the mixed gas are adsorbed on the adsorbent, and hydrogen is enriched from the adsorption tower. A pressure fluctuation adsorption type gas separation device for deriving gas and desorbing impurities from the adsorbent by depressurizing the adsorption tower, and deriving desorption gas from the adsorption tower;
    An apparatus for purifying hydrogen gas, comprising: a variable capacity gas holder for introducing and discharging the desorption gas derived from the adsorption tower.
  11. 　上記ガスホルダは、容器状に構成された本体部と、上記本体部の内部に収容され、上記本体部との間のガスシール状態を維持しつつ変位可能な仕切部材と、を備え
    　上記仕切部材の変位にともない、上記本体部及び上記仕切部材によって区画されたガス収容部に収容されるガスの量が変化する、請求項１０に記載の水素ガスの精製装置。     The gas holder includes: a main body configured in a container shape; and a partition member accommodated in the main body and displaceable while maintaining a gas seal state between the main body and the gas holder. The apparatus for purifying hydrogen gas according to claim 10, wherein the amount of gas stored in the gas storage section partitioned by the main body section and the partition member changes with displacement.
  12. 　上記仕切部材は、重量体を支持している、請求項１１に記載の水素ガスの精製装置。 The hydrogen gas purifier according to claim 11, wherein the partition member supports a weight body.
  13. 　上記仕切部材はダイヤフラムの形態であり、上記重量体は当該ダイヤフラムに支持されたピストンの形態である、請求項１２に記載の水素ガスの精製装置。 13. The apparatus for purifying hydrogen gas according to claim 12, wherein the partition member is in the form of a diaphragm, and the weight body is in the form of a piston supported by the diaphragm.
  14. 　上記仕切部材は膜体の形態であり、上記重量体は当該膜体に支持された錘の形態である、請求項１２に記載の水素ガスの精製装置。 13. The apparatus for purifying hydrogen gas according to claim 12, wherein the partition member is in the form of a film body, and the weight body is in the form of a weight supported by the film body.
  15. 　上記仕切部材は、重量体として構成されている、請求項１２に記載の水素ガスの精製装置。 The hydrogen gas purifier according to claim 12, wherein the partition member is configured as a weight body.
  16. 　上記仕切部材は、頂部が閉鎖し、底部が開口したドラムの形態であり、当該ドラムの開口底部が液体中に浸漬されている、請求項１５に記載の水素ガスの精製装置。 The hydrogen gas refining device according to claim 15, wherein the partition member is in the form of a drum having a top closed and a bottom opened, and the open bottom of the drum is immersed in a liquid.
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