JP2012214371A - Method for refining high-purity hydrogen - Google Patents
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本発明は、水素吸蔵合金が充填された水素回収塔を用いて、水素含有ガス中から水素を高純度かつ高回収率で精製する方法に関するものである。 The present invention relates to a method for purifying hydrogen from a hydrogen-containing gas with high purity and high recovery rate using a hydrogen recovery tower packed with a hydrogen storage alloy.
近年、地球環境の改善につながる燃料電池用の燃料として、水素への期待が高まっている。この水素は、天然ガス、ナフサ、灯油、メタノールなどの炭化水素含有燃料と水蒸気を金属触媒の存在下で改質・変成した後、精製して得ることが一般的である。また、この変成後のガスには水素以外に一酸化炭素、二酸化炭素、メタン、水など燃料電池用の燃料にとって不純物となる成分が含まれてしまう。しかし、燃料電池用の燃料としては、高純度な水素である方が、発電効率が向上する。このような高純度水素を得る代表的な方法としては、複数の吸着塔を用いた水素ＰＳＡ法が知られている（例えば、特許文献１を参照）。 In recent years, there is an increasing expectation for hydrogen as a fuel for fuel cells that leads to improvement of the global environment. In general, this hydrogen is obtained by reforming and reforming a hydrocarbon-containing fuel such as natural gas, naphtha, kerosene, and methanol and steam in the presence of a metal catalyst. In addition to hydrogen, the gas after the transformation contains components that are impurities for fuel for fuel cells, such as carbon monoxide, carbon dioxide, methane, and water. However, as fuel for the fuel cell, high-purity hydrogen improves power generation efficiency. As a typical method for obtaining such high-purity hydrogen, a hydrogen PSA method using a plurality of adsorption towers is known (see, for example, Patent Document 1).
また、吸着塔を用いた水素ＰＳＡ法以外にも純度の高い水素を得る方法が開発されている（例えば、特許文献２を参照）。この特許文献２に開示された技術は、水素吸蔵合金が充填された水素回収塔に水素含有ガスを通じ、この水素含有ガス中の水素のみを選択的に水素吸蔵合金に吸蔵させて不純物ガスと分離し、この水素吸蔵合金に吸蔵された水素のみを水素回収塔から放出させて水素を製造する方法（以下、「水素吸蔵合金法」と称す）である。 In addition to the hydrogen PSA method using an adsorption tower, a method for obtaining high-purity hydrogen has been developed (see, for example, Patent Document 2). The technique disclosed in Patent Document 2 is such that a hydrogen-containing gas is passed through a hydrogen recovery tower packed with a hydrogen storage alloy, and only hydrogen in the hydrogen-containing gas is selectively stored in the hydrogen storage alloy to be separated from the impurity gas. Then, only hydrogen stored in the hydrogen storage alloy is released from the hydrogen recovery tower to produce hydrogen (hereinafter referred to as “hydrogen storage alloy method”).
また、上記特許文献２に開示された技術をさらに発展させた技術も開発されている（例えば、特許文献３を参照）。この特許文献３に開示された技術は、改質ガスから水素分離膜で水素を分離した上で水素吸蔵合金により水素精製を行うと共に、水素吸蔵合金に水素を吸蔵させた後の水素回収塔内に残る不純物を精製した高純度水素の一部を用いて洗浄する洗浄工程を備えたものである。 Further, a technique that further develops the technique disclosed in Patent Document 2 has been developed (see, for example, Patent Document 3). In the technique disclosed in Patent Document 3, the hydrogen is separated from the reformed gas by a hydrogen separation membrane, and then the hydrogen is purified by the hydrogen storage alloy, and the hydrogen is stored in the hydrogen recovery tower after the hydrogen is stored in the hydrogen storage alloy. And a cleaning step of cleaning using a part of the high-purity hydrogen obtained by purifying the remaining impurities.
上記特許文献１に開示された複数の吸着塔を用いた水素ＰＳＡ法では、９９．９９９容積％（以下、「容積％」を単に「％」と表す。）以上の高純度水素を製造することができるが、水素以外の除去成分に応じた吸着剤がそれぞれ必要となり、そのために吸着塔が大型化するばかりか、さらに水素の回収率が高くても８０％と、２０％以上のロスが発生するという問題点があった。 In the hydrogen PSA method using a plurality of adsorption towers disclosed in Patent Document 1, high purity hydrogen of 99.999 volume% (hereinafter, “volume%” is simply expressed as “%”) or more is produced. However, it is necessary to use an adsorbent according to the removed components other than hydrogen, which not only increases the size of the adsorption tower, but also generates a loss of 20% or more at 80% even when the hydrogen recovery rate is high. There was a problem of doing.
また、上記特許文献２に開示された水素吸蔵合金法では、水素吸蔵合金が多量の水素を吸蔵量できる利点を利用しているため、製造時の工程切り替えサイクルを上記特許文献１に開示した水素ＰＳＡ法と比べて長くすることができる。そのため、水素吸蔵合金法の方が切り替え時の脱圧ロスが少なく、水素ＰＳＡ法に比べて水素の回収率を向上させることができるのである。しかし、この水素吸蔵合金法では、水素吸蔵合金に水素を吸蔵させた後の水素回収塔内に残る不純物が、水素放出工程で前記水素回収塔内から放出した高純度水素とともに回収されてしまう。したがって、水素回収率は前記水素ＰＳＡ法に比べて向上するものの、回収した水素純度は逆に前記水素ＰＳＡ法で得られる９９．９９９％以上よりも低くなってしまうという問題点があった。 Further, in the hydrogen storage alloy method disclosed in Patent Document 2, since the hydrogen storage alloy uses the advantage that a large amount of hydrogen can be stored, the process switching cycle at the time of production is disclosed in Patent Document 1 above. The length can be increased compared to the PSA method. Therefore, the hydrogen storage alloy method has less depressurization loss at the time of switching, and the hydrogen recovery rate can be improved compared to the hydrogen PSA method. However, in this hydrogen storage alloy method, impurities remaining in the hydrogen recovery tower after hydrogen is stored in the hydrogen storage alloy are recovered together with the high purity hydrogen released from the hydrogen recovery tower in the hydrogen release step. Therefore, although the hydrogen recovery rate is improved as compared with the hydrogen PSA method, there is a problem that the purity of the recovered hydrogen is conversely lower than 99.999% or more obtained by the hydrogen PSA method.
また、上記特許文献３に開示された水素吸蔵合金法では、上記特許文献２に開示された水素吸蔵合金法の問題点（回収した水素純度の低下）を改善しているが、水素分離膜を採用した新たなプロセスが必要な上に、さらに水素吸蔵合金部において、洗浄のために用いる精製した高純度水素の一部をオフガスとして水素回収塔外へ排出するため、水素回収率は逆に上記特許文献２に開示された水素吸蔵合金法に比べて低くなってしまうという問題点があった。 In addition, the hydrogen storage alloy method disclosed in Patent Document 3 has improved the problems of the hydrogen storage alloy method disclosed in Patent Document 2 (reduction in the purity of recovered hydrogen). In addition to the need for a new process, the hydrogen storage alloy part also discharges a portion of the purified high-purity hydrogen used for cleaning out of the hydrogen recovery tower as off-gas. There was a problem that it was lower than the hydrogen storage alloy method disclosed in Patent Document 2.
本発明の目的は、製品水素の損失を低減し、水素含有ガス中から高い回収率で高純度水素を回収可能な高純度水素精製方法を提供することにある。 An object of the present invention is to provide a high-purity hydrogen purification method capable of reducing loss of product hydrogen and recovering high-purity hydrogen from a hydrogen-containing gas at a high recovery rate.
この目的を達成するために、本発明の請求項１に記載の発明は、
水素含有ガスを水素吸蔵合金が充填された水素回収塔に通じ、この水素含有ガス中の水素を前記水素吸蔵合金に吸蔵させる水素吸蔵工程と、前記水素吸蔵合金に水素を吸蔵させた後の水素回収塔内に残る不純物ガスをパージするためのパージ工程と、このパージ工程後に前記水素吸蔵工程で吸蔵された水素を前記水素回収塔内から放出し高純度水素を得る水素放出工程と、を有した高純度水素精製方法において、
前記パージ工程と前記水素放出工程との間に、前記パージ工程後にも水素回収塔内に残る不純物を前記高純度水素の一部（以下、「洗浄用水素」と称す）を用いて洗浄する洗浄工程を有し、
この洗浄工程で排出される洗浄オフガスを回収し、この回収した洗浄オフガスを水素吸蔵工程が実施されるタイムステップにある水素回収塔および／または水素吸蔵工程の直前に設けた水素回収塔内の水素吸蔵合金を予め冷却する冷却工程が実施されるタイムステップにある水素回収塔に供給するようにしたことを特徴とする高純度水素精製方法である。
In order to achieve this object, the invention according to claim 1 of the present invention provides:
A hydrogen storage step of passing the hydrogen-containing gas through a hydrogen recovery tower filled with a hydrogen storage alloy, and storing the hydrogen in the hydrogen-containing gas into the hydrogen storage alloy, and the hydrogen after storing the hydrogen in the hydrogen storage alloy A purge step for purging the impurity gas remaining in the recovery tower; and a hydrogen release step for releasing high-purity hydrogen by releasing the hydrogen stored in the hydrogen storage step after the purge step. In the purified high purity hydrogen purification method,
Cleaning that cleans impurities remaining in the hydrogen recovery tower after the purging step with a part of the high-purity hydrogen (hereinafter referred to as “cleaning hydrogen”) between the purging step and the hydrogen releasing step. Having a process,
The cleaning off-gas discharged in this cleaning process is recovered, and the recovered cleaning off-gas is supplied to the hydrogen recovery tower in the time step where the hydrogen storage process is performed and / or the hydrogen in the hydrogen recovery tower provided immediately before the hydrogen storage process. A high-purity hydrogen refining method characterized in that it is supplied to a hydrogen recovery tower at a time step in which a cooling step for cooling the storage alloy in advance is performed.
請求項２に記載の発明は、請求項１に記載の発明において、
前記水素回収塔において、洗浄工程と水素放出工程の間に水素回収塔内の水素吸蔵合金を予め加熱する加熱工程を有したことを特徴とする。
The invention according to claim 2 is the invention according to claim 1,
The hydrogen recovery tower is characterized in that it has a heating step of preheating the hydrogen storage alloy in the hydrogen recovery tower between the washing step and the hydrogen releasing step.
請求項３に記載の発明は、請求項１または２に記載の発明において、
水素吸蔵合金が充填された２塔の水素回収塔で対をなし、この対をなした２塔の水素回収塔を少なくとも二対以上備えて高純度水素精製システムを構成し、この高純度水素精製システムの各対においてそれぞれ、一方の水素回収塔で洗浄工程が実施されるタイムステップにおいて、水素吸蔵工程および／または冷却工程が実施されるタイムステップにある他方の水素回収塔では前記一方の水素回収塔から排出され回収された洗浄オフガスが供給されるように構成されたことを特徴とする。
The invention according to claim 3 is the invention according to claim 1 or 2,
A pair of two hydrogen recovery towers filled with a hydrogen storage alloy are paired, and at least two pairs of hydrogen recovery towers are paired to form a high-purity hydrogen purification system. In each pair of systems, in the time step in which the cleaning process is performed in one hydrogen recovery tower, in the other hydrogen recovery tower in the time step in which the hydrogen storage process and / or the cooling process are performed, the one hydrogen recovery tower The cleaning off-gas discharged and recovered from the tower is supplied.
請求項４に記載の発明は、請求項３に記載の発明において、
前記高純度水素精製システム全体の各タイムステップにおいて、いずれのタイムステップにも、必ず水素吸蔵工程と水素放出工程を有するように構成されたことを特徴とする。
The invention according to claim 4 is the invention according to claim 3,
In each time step of the high-purity hydrogen purification system as a whole, each time step always includes a hydrogen storage process and a hydrogen release process.
請求項５に記載の発明は、請求項１に記載の発明において、
前記水素吸蔵合金がＡＢ５系水素吸蔵合金であることを特徴とする。
The invention according to claim 5 is the invention according to claim 1,
The hydrogen storage alloy is an AB5 hydrogen storage alloy.
請求項６に記載の発明は、請求項２に記載の発明において、
前記水素吸蔵合金がＡＢ５系水素吸蔵合金であり、このＡＢ５系水素吸蔵合金の２５℃における水素平衡圧が０．０５ＭＰａ以上０．３ＭＰａ以下であり、
前記ＡＢ５系水素吸蔵合金の温度制御用の媒体流通路が前記水素回収塔の内側または外側に設けられ、
前記水素吸蔵工程、パージ工程、洗浄工程と冷却工程においては、前記媒体流通路に０℃以上４０℃未満の媒体を流通させ、
前記水素放出工程と加熱工程においては、前記媒体流通路に４０℃以上１５０℃未満の媒体を流通させることを特徴とする。
The invention according to claim 6 is the invention according to claim 2,
The hydrogen storage alloy is an AB5-based hydrogen storage alloy, and the hydrogen equilibrium pressure at 25 ° C. of the AB5-based hydrogen storage alloy is 0.05 MPa or more and 0.3 MPa or less,
A medium flow passage for temperature control of the AB5 hydrogen storage alloy is provided inside or outside the hydrogen recovery tower,
In the hydrogen storage step, purge step, cleaning step and cooling step, a medium having a temperature of 0 ° C. or higher and lower than 40 ° C. is circulated through the medium flow path,
In the hydrogen releasing step and the heating step, a medium having a temperature of 40 ° C. or higher and lower than 150 ° C. is circulated through the medium flow path.
請求項７に記載の発明は、請求項１または２に記載の発明において、
前記洗浄工程において、前記水素含有ガス中の水素の流量に対する前記洗浄用水素の流量の比が、０．０５以上１．００未満であることを特徴とする。
The invention according to claim 7 is the invention according to claim 1 or 2,
In the cleaning step, a ratio of a flow rate of the cleaning hydrogen to a flow rate of hydrogen in the hydrogen-containing gas is 0.05 or more and less than 1.00.
請求項８に記載の発明は、請求項１または２に記載の発明において、
前記洗浄工程において、前記水素吸蔵合金の飽和水素吸蔵量に対する前記洗浄用水素の量の比が、０．５ｍｏｌ％以上２０ｍｏｌ％未満であることを特徴とする。
The invention according to claim 8 is the invention according to claim 1 or 2,
In the cleaning step, a ratio of the amount of cleaning hydrogen to a saturated hydrogen storage amount of the hydrogen storage alloy is 0.5 mol% or more and less than 20 mol%.
以上のように、本発明に係る高純度水素精製方法によれば、
水素含有ガスを水素吸蔵合金が充填された水素回収塔に通じ、この水素含有ガス中の水素を前記水素吸蔵合金に吸蔵させる水素吸蔵工程と、前記水素吸蔵合金に水素を吸蔵させた後の水素回収塔内に残る不純物ガスをパージするためのパージ工程と、このパージ工程後に前記水素吸蔵工程で吸蔵された水素を前記水素回収塔内から放出し高純度水素を得る水素放出工程と、を有した高純度水素精製方法において、
前記パージ工程と前記水素放出工程との間に、前記パージ工程後にも水素回収塔内に残る不純物を前記高純度水素の一部（洗浄用水素）を用いて洗浄する洗浄工程を有し、
この洗浄工程で排出される洗浄オフガスを回収し、この回収した洗浄オフガスを水素吸蔵工程が実施されるタイムステップにある水素回収塔および／または水素吸蔵工程の直前に設けた水素回収塔内の水素吸蔵合金を予め冷却する冷却工程が実施されるタイムステップにある水素回収塔に供給するようにしているため、
製品水素の損失を低減し、水素含有ガス中から高い回収率で高純度水素を回収可能な高純度水素精製方法を提供することができる。
As described above, according to the high purity hydrogen purification method of the present invention,
A hydrogen storage step of passing the hydrogen-containing gas through a hydrogen recovery tower filled with a hydrogen storage alloy, and storing the hydrogen in the hydrogen-containing gas into the hydrogen storage alloy, and the hydrogen after storing the hydrogen in the hydrogen storage alloy A purge step for purging the impurity gas remaining in the recovery tower; and a hydrogen release step for releasing high-purity hydrogen by releasing the hydrogen stored in the hydrogen storage step after the purge step. In the purified high purity hydrogen purification method,
Between the purge step and the hydrogen releasing step, there is a cleaning step of cleaning impurities remaining in the hydrogen recovery tower after the purge step using a part of the high-purity hydrogen (hydrogen for cleaning),
The cleaning off-gas discharged in this cleaning process is recovered, and the recovered cleaning off-gas is supplied to the hydrogen recovery tower in the time step where the hydrogen storage process is performed and / or the hydrogen in the hydrogen recovery tower provided immediately before the hydrogen storage process. Because it is designed to supply the hydrogen recovery tower in the time step where the cooling process for cooling the storage alloy in advance is performed,
A loss of product hydrogen can be reduced, and a high-purity hydrogen purification method capable of recovering high-purity hydrogen from a hydrogen-containing gas at a high recovery rate can be provided.
以下、本発明の実施の形態について、添付図面を参照しながら説明する。 Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
図１は本発明の一実施形態に係る高純度水素精製システムの構成の概要を模式的に説明する説明図である。 FIG. 1 is an explanatory diagram schematically illustrating an outline of a configuration of a high purity hydrogen purification system according to an embodiment of the present invention.
図１において、１ａ、１ｂ、１ｃ、１ｄは水素吸蔵合金が充填された水素回収塔、２ａ、２ｂ、２ｃ、２ｄは水素吸蔵合金の温度制御用に水素回収塔１ａ、１ｂ、１ｃ、１ｄの外側に設けられた媒体流通路、３は圧力コントロール弁、４、５は弁、６は真空ポンプ、７、８はマスフローコントローラである。 In FIG. 1, 1a, 1b, 1c and 1d are hydrogen recovery towers filled with a hydrogen storage alloy, 2a, 2b, 2c and 2d are hydrogen recovery towers 1a, 1b, 1c and 1d for temperature control of the hydrogen storage alloy. A medium flow passage provided on the outside, 3 is a pressure control valve, 4 and 5 are valves, 6 is a vacuum pump, and 7 and 8 are mass flow controllers.
図１に示すように、本実施形態の高純度水素精製システムは、４つの水素回収塔１ａ、１ｂ、１ｃ、１ｄを有し、水素回収塔１ａと水素回収塔１ｂが対をなし、水素回収塔１ｃと水素回収塔１ｄが対をなすように構成されている。 As shown in FIG. 1, the high-purity hydrogen purification system of this embodiment has four hydrogen recovery towers 1a, 1b, 1c, and 1d. The hydrogen recovery tower 1a and the hydrogen recovery tower 1b form a pair, and hydrogen recovery The tower 1c and the hydrogen recovery tower 1d are configured to make a pair.
ライン１０１は、水素含有ガスＡの導入ラインである。ライン１０１と各水素回収塔１ａ、１ｂ、１ｃ、１ｄとはそれぞれ弁Ａ１、弁Ｂ１、弁Ｃ１、弁Ｄ１を介して接続されている。 Line 101 is an introduction line for hydrogen-containing gas A. The line 101 and the hydrogen recovery towers 1a, 1b, 1c, and 1d are connected to each other through a valve A1, a valve B1, a valve C1, and a valve D1, respectively.
ライン１０２は、各水素回収塔１ａ〜１ｄにて水素含有ガスＡより高純度水素を得て、この高純度水素（製品水素）Ｃを回収する回収ラインであり、各水素回収塔１ａ〜１ｄとはそれぞれ弁Ａ２、弁Ｂ２、弁Ｃ２、弁Ｄ２を介して接続されており、回収した高純度水素（製品水素）Ｃはマスフローコントローラ７を介してさらにバッファタンク（図示せず）に一時的に貯蔵される。 The line 102 is a recovery line that obtains high-purity hydrogen from the hydrogen-containing gas A in each of the hydrogen recovery towers 1a to 1d and recovers this high-purity hydrogen (product hydrogen) C. The hydrogen recovery towers 1a to 1d and Are connected via valves A2, B2, C2 and D2, respectively, and the recovered high-purity hydrogen (product hydrogen) C is further temporarily supplied to a buffer tank (not shown) via the mass flow controller 7. Stored.
ライン１０３は、各水素回収塔１ａ〜１ｄで水素吸蔵合金に水素を吸蔵させた後の各水素回収塔１ａ〜１ｄ内に残る不純物ガスを常圧まで、もしくは減圧することにより、オフガスＢとしてパージするためのオフガスラインである。ライン１０３と各水素回収塔１ａ〜１ｄとはそれぞれ弁Ａ４、弁Ｂ４、弁Ｃ４、弁Ｄ４を介して接続され、さらに、ライン１０３は圧力コントロール弁３を介して常圧まで圧力を下げる弁４に接続されている。また、必要に応じてさらに減圧するためにライン１０３は圧力コントロール弁３、弁５を介して真空ポンプ６に接続されている。 The line 103 is purged as an off-gas B by reducing the impurity gas remaining in the hydrogen recovery towers 1a to 1d after the hydrogen storage alloy has occluded hydrogen in the hydrogen recovery towers 1a to 1d to normal pressure or reduced pressure. It is an off-gas line. The line 103 and the hydrogen recovery towers 1a to 1d are connected to each other via a valve A4, a valve B4, a valve C4, and a valve D4, and the line 103 is a valve 4 that reduces the pressure to normal pressure via the pressure control valve 3. It is connected to the. Further, the line 103 is connected to the vacuum pump 6 via the pressure control valve 3 and the valve 5 in order to further reduce the pressure as required.
ライン１０４は、各水素回収塔１ａ〜１ｄ内に残る不純物ガスを常圧まで、もしくは減圧することによりライン１０３を経由してオフガスＢとしてパージした後に、水素回収塔１ａ〜１ｄ内に残る不純物を回収した高純度水素（製品水素）Ｃの一部（洗浄用水素）を用いて洗浄するためのラインである。ライン１０４と各水素回収塔１ａ〜１ｄとはそれぞれ弁Ａ３、弁Ｂ３、弁Ｃ３、弁Ｄ３を介して接続されている。ライン１０４はマスフローコントローラ７、８を介してバッファタンクに接続されている。 The line 104 purges the impurity gas remaining in each of the hydrogen recovery towers 1a to 1d to normal pressure or by depressurizing the gas as the off-gas B via the line 103, and then the impurities remaining in the hydrogen recovery towers 1a to 1d. This is a line for cleaning using a part of the recovered high-purity hydrogen (product hydrogen) C (hydrogen for cleaning). The line 104 and the hydrogen recovery towers 1a to 1d are connected to each other via a valve A3, a valve B3, a valve C3, and a valve D3. The line 104 is connected to the buffer tank via the mass flow controllers 7 and 8.
ライン１０５ａは、上述したようにライン１０４を用いて水素回収塔１ａ内に残る不純物を洗浄用水素で洗浄し、その洗浄オフガスを回収し、この回収した洗浄オフガスを対をなす水素回収塔１ｂ内に供給するラインである。水素回収塔１ａは弁Ａ５とライン１０５ａを介して水素回収塔１ｂにデッドエンドとして接続されている。 As described above, the line 105a uses the line 104 to clean impurities remaining in the hydrogen recovery tower 1a with cleaning hydrogen, recovers the cleaning offgas, and forms a pair with the recovered cleaning offgas in the hydrogen recovery tower 1b. It is a line to supply to. The hydrogen recovery tower 1a is connected as a dead end to the hydrogen recovery tower 1b through a valve A5 and a line 105a.
ライン１０５ｂは、上述したようにライン１０４を用いて水素回収塔１ｂ内に残る不純物を洗浄用水素で洗浄し、その洗浄オフガスを回収し、この回収した洗浄オフガスを対をなす水素回収塔１ａ内に供給するラインである。水素回収塔１ｂは弁Ｂ５とライン１０５ｂを介して水素回収塔１ａにデッドエンドとして接続されている。 As described above, the line 105b uses the line 104 to clean impurities remaining in the hydrogen recovery tower 1b with cleaning hydrogen, recovers the cleaning offgas, and forms a pair with the recovered cleaning offgas in the hydrogen recovery tower 1a. It is a line to supply to. The hydrogen recovery tower 1b is connected as a dead end to the hydrogen recovery tower 1a via a valve B5 and a line 105b.
ライン１０５ｃは、上述したようにライン１０４を用いて水素回収塔１ｃ内に残る不純物を洗浄用水素で洗浄し、その洗浄オフガスを回収し、この回収した洗浄オフガスを対をなす水素回収塔１ｄ内に供給するラインである。水素回収塔１ｃは弁Ｃ５とライン１０５ｃを介して水素回収塔１ｄにデッドエンドとして接続されている。 As described above, the line 105c uses the line 104 to clean impurities remaining in the hydrogen recovery tower 1c with cleaning hydrogen, recovers the cleaning off gas, and forms a pair with the recovered cleaning off gas in the hydrogen recovery tower 1d. It is a line to supply to. The hydrogen recovery tower 1c is connected as a dead end to the hydrogen recovery tower 1d through a valve C5 and a line 105c.
ライン１０５ｄは、上述したようにライン１０４を用いて水素回収塔１ｄ内に残る不純物を洗浄用水素で洗浄し、その洗浄オフガスを回収し、この回収した洗浄オフガスを対をなす水素回収塔１ｃ内に供給するラインである。水素回収塔１ｄは弁Ｄ５とライン１０５ｄを介して水素回収塔１ｃにデッドエンドとして接続されている。 As described above, the line 105d uses the line 104 to clean impurities remaining in the hydrogen recovery tower 1d with cleaning hydrogen, recovers the cleaning offgas, and forms a pair with the recovered cleaning offgas in the hydrogen recovery tower 1c. It is a line to supply to. The hydrogen recovery tower 1d is connected as a dead end to the hydrogen recovery tower 1c through a valve D5 and a line 105d.
次に、水素含有ガスＡ中から高純度水素（製品水素）Ｃを精製する方法の操作手順を具体的に説明する。なお、以下においては、原則として水素回収塔１ａの操作手順のみについて説明するが、運転は下記表１のタイムステップテーブルに示すように、水素回収塔１ａ〜１ｄの４塔を用いてサイクリックに行う。また、上述したように、水素回収塔１ａと水素回収塔１ｂが対をなし、水素回収塔１ｃと水素回収塔１ｄが対をなすため、適宜これらとの係わりについても説明する。 Next, the operation procedure of the method for purifying high-purity hydrogen (product hydrogen) C from the hydrogen-containing gas A will be specifically described. In the following, only the operation procedure of the hydrogen recovery tower 1a will be described in principle, but the operation is cyclic using four hydrogen recovery towers 1a to 1d as shown in the time step table of Table 1 below. Do. As described above, since the hydrogen recovery tower 1a and the hydrogen recovery tower 1b make a pair, and the hydrogen recovery tower 1c and the hydrogen recovery tower 1d make a pair, the relationship with these will be described as appropriate.
１）［水素吸蔵工程（タイムステップ番号１〜４）］：媒体流通路２ａに０℃以上４０℃未満の媒体（例えば、冷水）を流しながら、水素回収塔１ａに導入し、水素含有ガスＡ中の水素を水素吸蔵合金に吸蔵させる（弁Ａ２，Ａ３，Ａ４，Ａ５、Ｂ５：閉、弁Ａ１：開）。水素吸蔵反応は発熱反応であるため、除熱のため、上述したように冷水を流しながら水素吸蔵を行なう。これにより、水素吸蔵速度も低下しないため、水素の回収率も向上する。また、水素吸蔵合金として、例えばＡＢ５系水素吸蔵合金のような種類を用いる場合には、高圧化（例えば、０．９ＭＰａに）した水素含有ガスＡを水素回収塔１ａに導入する。なお、処理する水素含有ガスＡの水素濃度が低い場合、すなわち不純物濃度が高い場合、弁Ａ４を開き、圧力コントロール弁３で圧力をコントロールしながらライン１０３を経由して不純物をオフガスとして排出してもよい。 1) [Hydrogen occlusion step (time step numbers 1 to 4)]: While flowing a medium (for example, cold water) of 0 ° C. or higher and lower than 40 ° C. through the medium flow passage 2a, the hydrogen-containing gas A is introduced into the hydrogen recovery tower 1a. The hydrogen is stored in the hydrogen storage alloy (valves A2, A3, A4, A5, B5: closed, valve A1: opened). Since the hydrogen occlusion reaction is an exothermic reaction, hydrogen occlusion is performed while flowing cold water as described above for heat removal. Thereby, since the hydrogen occlusion speed is not lowered, the hydrogen recovery rate is also improved. Moreover, when using a kind like an AB5 type | system | group hydrogen storage alloy as a hydrogen storage alloy, the hydrogen-containing gas A made into high pressure (for example, 0.9 MPa) is introduce | transduced into the hydrogen recovery tower 1a. When the hydrogen concentration of the hydrogen-containing gas A to be processed is low, that is, when the impurity concentration is high, the valve A4 is opened and the pressure is controlled by the pressure control valve 3 and the impurities are discharged as off-gas via the line 103. Also good.
２）［待機工程（タイムステップ番号５）］：上記１）に示す水素吸蔵工程終了後、水素回収塔１ａ内に僅かに残る水素も可能な限り水素吸蔵合金に吸蔵させるために、水素回収塔１ａ内にガスを留める（弁Ａ１、Ａ２，Ａ３，Ａ４，Ａ５、Ｂ５：閉）。 2) [Standby process (time step number 5)]: After the hydrogen storage process shown in the above 1) is completed, in order to store as little hydrogen as possible in the hydrogen recovery tower 1a in the hydrogen storage alloy as much as possible, the hydrogen recovery tower Gas is retained in 1a (valves A1, A2, A3, A4, A5, B5: closed).
３）［パージ工程（タイムステップ番号６）］：上記２）に示す待機工程終了後、水素回収塔１ａ内に残る不純物ガスを常圧まで、もしくは減圧することによりライン１０３を経由してオフガスＢとしてパージする。なお、常圧にする場合には、弁Ａ１、Ａ２，Ａ３，Ａ５とＢ５を閉じ、弁Ａ４，圧力コントロール弁３と弁４を開く。また、減圧する場合には、弁Ａ１、Ａ２，Ａ３，Ａ５、Ｂ５と弁４を閉じ、弁Ａ４と弁５を開け、真空ポンプ６を起動し、圧力コントロール弁３を調節しながら所定の圧力まで減圧する。 3) [Purge process (time step number 6)]: After completion of the standby process shown in 2) above, the offgas B via the line 103 is reduced through the line 103 by reducing the impurity gas remaining in the hydrogen recovery tower 1a to normal pressure. Purge as In the case of normal pressure, valves A1, A2, A3, A5 and B5 are closed, and valve A4, pressure control valve 3 and valve 4 are opened. When the pressure is reduced, the valves A1, A2, A3, A5, B5 and the valve 4 are closed, the valves A4 and 5 are opened, the vacuum pump 6 is started, and the pressure control valve 3 is adjusted while adjusting the predetermined pressure. Depressurize until.
４）［洗浄工程（タイムステップ番号７）］：上記３）に示すパージ工程終了後、水素回収塔１ａ内に残る不純物をバッファタンク内に一時的に貯蔵してある回収した高純度水素（製品水素）Ｃの一部（洗浄用水素）、またはライン１０２より他の水素回収塔から排出される高純度水素の一部を用い、マスフローコントローラ７、８を制御しながら洗浄する（弁Ａ１、Ａ２，Ａ４，Ｂ５：閉、弁Ａ３，Ａ５：開）。これにより、水素回収塔１ａ内は、不純物が十分に少ない状態となり、結果として後述の水素放出工程において９９．９９９％以上（例えば、９９．９９９９％）の高純度水素が得られる。なお、この洗浄工程が実施されるタイムステップ（上記タイムステップ番号７）においては、対をなす水素回収塔１ｂでは下記表1に示すように冷却工程（詳細は後記する）が実施されるタイムステップにあり、水素回収塔１ａから排出され回収された洗浄オフガスが供給されるように構成されている。上述したように、水素回収塔１ａ内を上記洗浄用水素を用いて洗浄したものであり、洗浄オフガスは不純物を含むとはいえ、まだ高い水素濃度を有しているため、この洗浄オフガスを回収し、対をなす水素回収塔１ｂに供給することにより、製品水素の損失を低減しながら、水素の回収率を向上させることが可能となる。 4) [Washing step (time step number 7)]: After completion of the purging step shown in 3) above, recovered high-purity hydrogen (product) in which impurities remaining in the hydrogen recovery tower 1a are temporarily stored in the buffer tank Hydrogen) A part of C (hydrogen for cleaning) or a part of high-purity hydrogen discharged from another hydrogen recovery tower from line 102 is used for cleaning while controlling mass flow controllers 7 and 8 (valves A1 and A2). A4, B5: closed, valves A3, A5: open). As a result, the hydrogen recovery tower 1a has a sufficiently small amount of impurities, and as a result, 99.999% or more (for example, 99.9999%) of high-purity hydrogen is obtained in the hydrogen release step described later. In the time step (time step number 7) in which this cleaning process is performed, the cooling step (details will be described later) is performed in the hydrogen recovery tower 1b that makes a pair as shown in Table 1 below. The cleaning off-gas discharged and recovered from the hydrogen recovery tower 1a is supplied. As described above, the inside of the hydrogen recovery tower 1a is cleaned with the above-described cleaning hydrogen, and the cleaning off gas has a high hydrogen concentration even though it contains impurities, so that this cleaning off gas is recovered. However, by supplying the hydrogen recovery tower 1b which makes a pair, it is possible to improve the hydrogen recovery rate while reducing the loss of product hydrogen.
５）［加熱工程（タイムステップ番号８、９）］：上記４）に示す洗浄工程終了後、媒体流通路２ａに４０℃以上１５０℃未満の媒体（例えば、温水）を流しながら、水素回収塔１ａ内に充填された水素吸蔵合金を加熱する（弁Ａ１、Ａ２，Ａ３，Ａ４，Ａ５、Ｂ５：閉）。これにより、後記水素放出工程で必要な熱量が事前に供給されるため、水素放出工程で十分な水素放出速度を素早く得られる。 5) [Heating step (time step numbers 8 and 9)]: After completion of the cleaning step shown in 4) above, a medium (for example, hot water) of 40 ° C. or higher and lower than 150 ° C. is allowed to flow through the medium flow path 2a. The hydrogen storage alloy filled in 1a is heated (valves A1, A2, A3, A4, A5, B5: closed). As a result, the amount of heat necessary for the hydrogen release step described later is supplied in advance, so that a sufficient hydrogen release rate can be quickly obtained in the hydrogen release step.
６）［水素放出工程（タイムステップ番号１０〜１３）］：上記５）に示す加熱工程終了後、媒体流通路２ａに４０℃以上１５０℃未満の媒体（例えば、温水）を流しながら、上記水素吸蔵工程で吸蔵された水素を水素回収塔１ａ内から放出し高純度水素を得る（弁Ａ１、Ａ３，Ａ４，Ａ５、Ｂ５：閉、弁Ａ２：開）。水素放出反応は吸熱反応のため、熱の補給のため、上述したように温水を流しながら水素放出を行なう。これにより、水素放出速度も低下しないため、高純度な水素が得られる。 6) [Hydrogen releasing step (time step numbers 10 to 13)]: After completion of the heating step shown in 5) above, the above hydrogen is supplied while flowing a medium (for example, hot water) of 40 ° C. or higher and lower than 150 ° C. through the medium flow passage 2a. The hydrogen occluded in the occlusion process is released from the hydrogen recovery tower 1a to obtain high purity hydrogen (valves A1, A3, A4, A5, B5: closed, valve A2: opened). Since the hydrogen releasing reaction is an endothermic reaction, hydrogen is released while flowing warm water as described above in order to replenish heat. Thereby, since the hydrogen release rate does not decrease, high-purity hydrogen can be obtained.
７）［冷却工程（タイムステップ番号１４〜１６）］：上記６）に示す水素放出工程終了後、再び媒体流通路２ａに０℃以上４０℃未満の媒体（例えば、冷水）を流しながら、水素回収塔１ａ内に充填された水素吸蔵合金を冷却する（弁Ａ１、Ａ２，Ａ３，Ａ４，Ａ５、Ｂ５：閉）。これにより、次工程（上記水素吸蔵工程）に備えて、必要な除熱が事前に行なわれるため、水素吸蔵工程で十分な水素吸蔵速度を素早く得られる。また、冷却工程が実施されるタイムステップ番号１５にある水素回収塔１ａでは、洗浄工程が実施されるタイムステップ番号１５にある水素回収塔１ｂから排出され回収された洗浄オフガスが供給されるように構成されている。 7) [Cooling step (time step numbers 14 to 16)]: After completion of the hydrogen releasing step shown in 6) above, while a medium (for example, cold water) of 0 ° C. or higher and lower than 40 ° C. is flowed again through the medium flow passage 2a, The hydrogen storage alloy filled in the recovery tower 1a is cooled (valves A1, A2, A3, A4, A5, B5: closed). Thereby, in preparation for the next step (the hydrogen storage step), necessary heat removal is performed in advance, so that a sufficient hydrogen storage rate can be quickly obtained in the hydrogen storage step. Further, in the hydrogen recovery tower 1a at the time step number 15 where the cooling process is performed, the cleaning off-gas discharged and recovered from the hydrogen recovery tower 1b at the time step number 15 where the cleaning process is performed is supplied. It is configured.
上記１）から７）の操作手順を、対をなす水素回収塔１ａと水素回収塔１ｂとの間、および、対をなす水素回収塔１ｃと水素回収塔１ｄとの間で繰り返すことにより、製品水素の損失を低減し、水素含有ガスＡ中から高い回収率で高純度水素を回収する。 By repeating the operation procedures 1) to 7) between the hydrogen recovery tower 1a and the hydrogen recovery tower 1b that make a pair and between the hydrogen recovery tower 1c and the hydrogen recovery tower 1d that make a pair, Hydrogen loss is reduced, and high purity hydrogen is recovered from the hydrogen-containing gas A at a high recovery rate.
なお、本実施形態に係る高純度水素精製システムにおける高純度水素精製方法では、１つの水素回収塔についての１サイクルの中に水素吸蔵工程、待機工程、パージ工程、洗浄工程、加熱工程、水素放出工程と冷却工程を備えた例について説明したが、必ずしもこれに限定されるものではない。本発明の技術思想においては、前記パージ工程と前記水素放出工程との間に、前記パージ工程後にも水素回収塔内に残る不純物を回収した高純度水素の一部（洗浄用水素）を用いて洗浄する洗浄工程を有し、この洗浄工程で排出される洗浄オフガスを回収し、この回収した洗浄オフガスを水素吸蔵工程が実施されるタイムステップにある水素回収塔および／または水素吸蔵工程の直前に設けた水素回収塔内の水素吸蔵合金を予め冷却する冷却工程が実施されるタイムステップにある水素回収塔に供給するようにしてあればよい。ただし、１つの水素回収塔についての１サイクルの中に待機工程、加熱工程と冷却工程を備えると、上述したようなさらなる作用効果を生ずるため、これらの工程を設けるのがより好ましい。 In the high-purity hydrogen purification method in the high-purity hydrogen purification system according to this embodiment, the hydrogen storage process, standby process, purge process, cleaning process, heating process, hydrogen release in one cycle for one hydrogen recovery tower Although the example provided with the process and the cooling process was demonstrated, it is not necessarily limited to this. In the technical idea of the present invention, a part of the high-purity hydrogen (cleaning hydrogen) recovered from impurities remaining in the hydrogen recovery tower after the purge step is used between the purge step and the hydrogen release step. The cleaning off-gas discharged in the cleaning step is recovered, and the recovered cleaning off-gas is recovered immediately before the hydrogen recovery tower and / or the hydrogen storage step in the time step where the hydrogen storage step is performed. What is necessary is just to make it supply to the hydrogen recovery tower in the time step in which the cooling process which cools the hydrogen storage alloy in the provided hydrogen recovery tower previously is implemented. However, if a standby process, a heating process, and a cooling process are provided in one cycle for one hydrogen recovery tower, the above-described additional effects are produced, so it is more preferable to provide these processes.
また、本実施形態に係る高純度水素精製システムにおける高純度水素精製方法では、４つの水素回収塔１ａ〜１ｄを有し、水素回収塔１ａと水素回収塔１ｂで対をなし、水素回収塔１ｃと水素回収塔１ｄで対をなす例について説明したが、必ずしもこれに限定されるものではない。上述した本発明の技術思想を順守する構成であれば、１つの水素回収塔だけであっても構わない。しかし、水素吸蔵合金が充填された２塔の水素回収塔で対をなし、この対をなした２塔の水素回収塔を少なくとも二対以上備えて高純度水素精製システムを構成し、この高純度水素精製システムの各対においてそれぞれ、一方の水素回収塔で洗浄工程が実施されるタイムステップにおいて、水素吸蔵工程および／または冷却工程が実施されるタイムステップにある他方の水素回収塔では前記一方の水素回収塔から排出され回収された洗浄オフガスが供給されるように構成されていれば、高純度水素精製の連続的かつ生産効率向上の点から好適である。さらに、本実施形態に係る高純度水素精製システムにおける高純度水素精製方法では、この高純度水素精製システム全体の各タイムステップにおいて、いずれのタイムステップにも、必ず水素吸蔵工程と水素放出工程を有するように構成されている（上記表１参照）ため、高純度水素精製の連続的かつ生産効率向上の点からより好適である。 Further, in the high purity hydrogen purification method in the high purity hydrogen purification system according to the present embodiment, the hydrogen recovery tower 1c has four hydrogen recovery towers 1a to 1d, and the hydrogen recovery tower 1a and the hydrogen recovery tower 1b are paired together. However, the present invention is not necessarily limited to this. As long as the above-described technical idea of the present invention is observed, only one hydrogen recovery tower may be used. However, two hydrogen recovery towers filled with hydrogen storage alloy are paired, and at least two pairs of hydrogen recovery towers are paired to form a high-purity hydrogen purification system. In each pair of hydrogen purification systems, in the time step in which the cleaning process is performed in one hydrogen recovery tower, in the other hydrogen recovery tower in the time step in which the hydrogen storage process and / or the cooling process are performed, If the cleaning off-gas discharged from the hydrogen recovery tower and recovered is supplied, it is preferable from the viewpoint of continuous and high production efficiency of high-purity hydrogen purification. Furthermore, in the high-purity hydrogen purification method in the high-purity hydrogen purification system according to the present embodiment, in each time step of the entire high-purity hydrogen purification system, every time step always includes a hydrogen storage process and a hydrogen release process. Since it is configured as described above (see Table 1 above), it is more preferable from the viewpoint of continuous and high production efficiency of high-purity hydrogen purification.
また、ＣＯ２、Ｎ２などの不純物が水素含有ガスＡに含まれた場合、水素吸蔵合金としてＡＢ５系水素吸蔵合金を採用すると、ＡＢ２系水素吸蔵合金を初めとした他の水素吸蔵合金と比較してＣＯ２、Ｎ２などの不純物に対する耐性が強く、システムとしての耐久性を持たせることが可能となり好ましい。このＡＢ５系水素吸蔵合金の２５℃における水素平衡圧が０．０５ＭＰａ以上０．３ＭＰａ以下であり、前記ＡＢ５系水素吸蔵合金の温度制御用の媒体流通路が水素回収塔の内側または外側に設けられ、水素吸蔵工程、パージ工程、洗浄工程と冷却工程においては、前記媒体流通路に０℃以上４０℃未満の媒体（以下、「冷媒」と称す）を流通させ、水素放出工程と加熱工程においては、前記媒体流通路に４０℃以上１５０℃未満の媒体（以下、「熱媒」と称す）を流通させるのが好ましい。何故ならば、冷媒の温度がこの範囲より低すぎると冷媒を作成するためのエネルギーが必要となりエネルギー効率が落ちる。一方、この範囲より高すぎると十分な水素吸蔵速度が得られなくなる。また、熱媒の温度がこの範囲より低すぎると十分な水素放出速度が得られなくなり、一方この範囲より高すぎると熱媒を作製するためのエネルギーが必要となり、エネルギー効率が落ちる。エネルギー効率ならびにコストを考えるとより好ましい冷媒温度は２０℃〜４０℃であり、より好ましい熱媒温度は通常利用されていない低品位排熱で回収可能な６０℃〜８０℃である。 Further, when impurities such as CO 2 and N 2 are contained in the hydrogen-containing gas A, when an AB5 hydrogen storage alloy is adopted as the hydrogen storage alloy, it is compared with other hydrogen storage alloys such as an AB2 hydrogen storage alloy. Therefore, it is preferable because it has high resistance to impurities such as CO 2 and N 2 and can provide durability as a system. The AB5 hydrogen storage alloy has a hydrogen equilibrium pressure at 25 ° C. of 0.05 MPa or more and 0.3 MPa or less, and a medium flow passage for temperature control of the AB5 hydrogen storage alloy is provided inside or outside the hydrogen recovery tower. In the hydrogen storage process, the purge process, the cleaning process and the cooling process, a medium (hereinafter referred to as “refrigerant”) of 0 ° C. or more and less than 40 ° C. is circulated through the medium flow path, and in the hydrogen release process and the heating process. Preferably, a medium (hereinafter referred to as “heat medium”) having a temperature of 40 ° C. or higher and lower than 150 ° C. is circulated through the medium flow path. This is because if the temperature of the refrigerant is too lower than this range, energy for producing the refrigerant is required and energy efficiency is lowered. On the other hand, if it is higher than this range, a sufficient hydrogen storage rate cannot be obtained. On the other hand, if the temperature of the heat medium is lower than this range, a sufficient hydrogen release rate cannot be obtained. On the other hand, if it is higher than this range, energy for producing the heat medium is required, and the energy efficiency is lowered. Considering energy efficiency and cost, a more preferable refrigerant temperature is 20 ° C. to 40 ° C., and a more preferable heat medium temperature is 60 ° C. to 80 ° C. that can be recovered by low-grade exhaust heat that is not normally used.
以下、実施例を挙げて本発明を具体的に説明するが、本発明はもとより下記実施例によって制限を受けるものではない。 EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not restrict | limited by the following Example from the first.
本発明の効果を確証するために、上記本実施形態で例示した図１の高純度水素精製システムの構成を有し、かつ、上記表１のタイムステップテーブルに示す運転を採用して、高純度水素精製の試験を行った。 In order to confirm the effect of the present invention, the configuration of the high-purity hydrogen purification system of FIG. 1 exemplified in the present embodiment is employed, and the operation shown in the time step table of Table 1 is adopted to achieve high purity. A hydrogen purification test was conducted.
実験条件は以下の通りである。
＜被精製ガス（水素含有ガスＡ）条件＞
圧力：０．９ＭＰａ
温度：２０℃
流量：２．０ＮＬ／ｍｉｎ
組成：Ｈ２：８０％、ＣＯ２：２０％（水素分圧０．７２ＭＰａ）
∴ 被精製ガス（水素含有ガスＡ）中の水素の流量は、１．６ＮＬ／ｍｉｎである。
＜水素吸蔵合金＞
２５℃における水素平衡圧が０．１ＭＰａとなるように調整したＡＢ５系水素吸蔵合金（例えば、ＭｍＮｉ４．０２５Ｃｏ０．４Ｍｎ０．２７５Ａｌ０．３）である。
また、各水素回収塔１ａ〜１ｄ内のＡＢ５系水素吸蔵合金の飽和水素吸蔵量（以下、単に「飽和水素吸蔵量」と称す）は、１５８ＮＬである。
ここで、水素平衡圧は、水素吸蔵合金の圧力-組成等温線（ＰＣＴ線）の測定方法（ＪＩＳ Ｈ７２０１）に基づく真空原点法によって得られた水素吸蔵合金のＰＣＴ線において、水素吸蔵量（Ｈ／Ｍ）が０．５における圧力と定義する。
また、飽和水素吸蔵量は、水素吸蔵工程、パージ工程、洗浄工程と冷却工程がそれぞれ実施される際の所定温度における水素吸蔵合金の圧力-組成等温線（ＰＣＴ線）の測定方法（ＪＩＳ Ｈ７２０１）に基づく真空原点法によって得られた水素吸蔵合金のＰＣＴ線において、圧力が５．０ＭＰａにおける水素吸蔵量と定義する。
＜熱媒および冷媒条件＞
熱媒条件：８０℃温水・流量３Ｌ／min
冷媒条件：２０℃冷水・流量３Ｌ／min
＜１塔ごとのサイクルパターン＞
水素吸蔵工程：３０分
待機工程：５分
パージ工程：５分
洗浄工程：１０分
加熱工程：１５分
水素放出工程：３０分
冷却工程：２５分
＜洗浄工程条件＞
水素回収塔１ａ〜１ｄ毎の洗浄用水素の流量（以下、単に「洗浄用水素の流量」と称す）：０．４ＮＬ／ｍｉｎ
∴ 洗浄用水素の流量／上記水素含有ガスＡ中の水素の流量＝０．２５
水素回収塔１ａ〜１ｄ毎の洗浄用水素の量（以下、単に「洗浄用水素の量」と称す）：
４ＮＬ
∴ 洗浄用水素の量／上記飽和水素吸蔵量×１００＝２．５ｍｏｌ％
The experimental conditions are as follows.
<Purified gas (hydrogen-containing gas A) conditions>
Pressure: 0.9 MPa
Temperature: 20 ° C
Flow rate: 2.0NL / min
Composition: H 2 : 80%, CO 2 : 20% (hydrogen partial pressure 0.72 MPa)
流量 The flow rate of hydrogen in the gas to be purified (hydrogen-containing gas A) is 1.6 NL / min.
<Hydrogen storage alloy>
It is an AB5 hydrogen storage alloy (for example, MmNi 4.025 Co 0.4 Mn 0.275 Al 0.3 ) adjusted so that the hydrogen equilibrium pressure at 25 ° C. is 0.1 MPa.
Further, the saturated hydrogen storage amount of the AB5 hydrogen storage alloy in each of the hydrogen recovery towers 1a to 1d (hereinafter simply referred to as “saturated hydrogen storage amount”) is 158NL.
Here, the hydrogen equilibrium pressure is the hydrogen storage amount (H in the hydrogen storage alloy PCT line obtained by the vacuum origin method based on the pressure-composition isotherm (PCT line) measurement method (JIS H7201) of the hydrogen storage alloy. / M) is defined as the pressure at 0.5.
The saturated hydrogen storage amount is a method for measuring the pressure-composition isotherm (PCT line) of a hydrogen storage alloy at a predetermined temperature when the hydrogen storage process, purge process, cleaning process and cooling process are performed (JIS H7201). In the PCT line of the hydrogen storage alloy obtained by the vacuum origin method based on the above, it is defined as the hydrogen storage amount at a pressure of 5.0 MPa.
<Heat medium and refrigerant conditions>
Heating medium conditions: 80 ° C hot water, flow rate 3L / min
Refrigerant conditions: 20 ° C cold water, flow rate 3L / min
<Cycle pattern for each tower>
Hydrogen storage process: 30 minutes Standby process: 5 minutes Purge process: 5 minutes Cleaning process: 10 minutes Heating process: 15 minutes Hydrogen releasing process: 30 minutes Cooling process: 25 minutes <Cleaning process conditions>
Flow rate of cleaning hydrogen for each of the hydrogen recovery towers 1a to 1d (hereinafter simply referred to as “flow rate of cleaning hydrogen”): 0.4 NL / min
流量 Flow rate of cleaning hydrogen / flow rate of hydrogen in hydrogen-containing gas A = 0.25
Amount of cleaning hydrogen for each of the hydrogen recovery towers 1a to 1d (hereinafter simply referred to as “amount of cleaning hydrogen”):
4NL
量 Amount of cleaning hydrogen / saturated hydrogen storage amount x 100 = 2.5 mol%
以上の工程を３０サイクル行ったところ、水素回収率は９０％、得られた高純度水素の平均濃度は９９．９９９９％が得られた。 When the above steps were performed for 30 cycles, a hydrogen recovery rate of 90% and an average concentration of the obtained high purity hydrogen of 99.9999% were obtained.
〔比較例１〕
実験条件は、上記実施例（本発明）において、洗浄工程とこれに付随する洗浄オフガスの回収を除く構成にしている以外は上記実施例と同じである。その結果、水素回収率は８５％、得られた高純度水素の平均濃度は９９．９％であった。
[Comparative Example 1]
The experimental conditions are the same as those in the above example (the present invention) except that the cleaning step and the recovery of the cleaning off gas associated therewith are excluded. As a result, the hydrogen recovery rate was 85%, and the average concentration of the obtained high purity hydrogen was 99.9%.
〔比較例２〕
実験条件は、上記実施例（本発明）において、洗浄工程は設けられているが、これに付随する洗浄オフガスの回収を除く構成にしている。それ以外は上記実施例と同じである。その結果、水素回収率は８７％、得られた高純度水素の平均濃度は９９．９９９９％であった。
[Comparative Example 2]
The experimental condition is that the cleaning step is provided in the above-described embodiment (the present invention), but the recovery of the cleaning off-gas associated therewith is excluded. The rest is the same as the above embodiment. As a result, the hydrogen recovery rate was 87%, and the average concentration of the obtained high purity hydrogen was 99.9999%.
〔比較例３〕
実験条件は、洗浄工程における洗浄用水素の流量を０．０５ＮＬ／ｍｉｎ、洗浄用水素の量を０．５ＮＬとした以外は上記実施例と同じである。
∴ 洗浄用水素の流量／上記水素含有ガスＡ中の水素の流量＝０．０３１
∴ 洗浄用水素の量／上記飽和水素吸蔵量×１００＝０．３２ｍｏｌ％
[Comparative Example 3]
The experimental conditions are the same as in the above example except that the flow rate of cleaning hydrogen in the cleaning process is 0.05 NL / min and the amount of cleaning hydrogen is 0.5 NL.
流量 Flow rate of cleaning hydrogen / flow rate of hydrogen in hydrogen-containing gas A = 0.031
量 Amount of cleaning hydrogen / saturated hydrogen storage amount x 100 = 0.32 mol%
その結果、水素回収率は９０％、得られた高純度水素の平均濃度は９９．９７％であった。 As a result, the hydrogen recovery rate was 90%, and the average concentration of the obtained high purity hydrogen was 99.97%.
〔比較例４〕
実験条件は、洗浄工程における洗浄用水素の流量を３．２ＮＬ／ｍｉｎ、洗浄用水素の量を３２ＮＬとした以外は上記実施例と同じである。
∴ 洗浄用水素の流量／上記水素含有ガスＡ中の水素の流量＝２．０
∴ 洗浄用水素の量／上記飽和水素吸蔵量×１００＝２０．２ｍｏｌ％
[Comparative Example 4]
The experimental conditions are the same as in the above example except that the flow rate of cleaning hydrogen in the cleaning process is 3.2 NL / min and the amount of cleaning hydrogen is 32 NL.
流量 Flow rate of cleaning hydrogen / flow rate of hydrogen in hydrogen-containing gas A = 2.0
量 amount of cleaning hydrogen / saturated hydrogen storage amount x 100 = 20.2 mol%
その結果、水素回収率は８５％、得られた高純度水素の平均濃度は９９．９９９９％であった。このような水素回収率の低下を招いたのは、洗浄工程における洗浄用水素の量が多くなった結果、冷却工程にて洗浄オフガスを回収した塔が次に水素精製工程に入る際、水素を吸蔵した状態から水素精製を開始するためであると考えられる。 As a result, the hydrogen recovery rate was 85%, and the average concentration of the obtained high purity hydrogen was 99.9999%. This decrease in the hydrogen recovery rate was caused by an increase in the amount of hydrogen for cleaning in the cleaning process, so that the tower that recovered the cleaning off-gas in the cooling process next entered the hydrogen purification process. This is considered to be for starting hydrogen purification from the occluded state.
以上のように、高純度水素の平均濃度が９９．９９９９％で、水素回収率が９０％以上を満足するのは上記実施例（本発明）のみである。 As described above, only the above-described example (the present invention) satisfies the average concentration of high purity hydrogen of 99.9999% and the hydrogen recovery rate of 90% or more.
なお、本実施例ならびに比較例で用いた水素含有ガスＡの水素濃度は８０％、圧力は０．９ＭＰａとしたが、必ずしもこの濃度に限られたものではなく、温度ならびに水素分圧が用いる水素吸蔵合金の水素平衡圧以上であればどの圧力・温度でも高純度水素精製は可能である。 The hydrogen concentration of the hydrogen-containing gas A used in this example and the comparative example was 80% and the pressure was 0.9 MPa. However, the hydrogen concentration is not necessarily limited to this concentration. High-purity hydrogen purification is possible at any pressure and temperature as long as it exceeds the hydrogen equilibrium pressure of the storage alloy.
また、本実施例においては、洗浄用水素の流量／水素含有ガスＡ中の水素の流量＝０．２５、洗浄用水素の量／飽和水素吸蔵量×１００＝２．５ｍｏｌ％の場合について説明したが、必ずしもこれに限定されるものではなく、水素含有ガスＡ中の水素の流量に対する洗浄用水素の流量の比が０．０５以上１．００未満の条件を満足し、飽和水素吸蔵量に対する洗浄用水素の量の比が０．５ｍｏｌ％以上２０ｍｏｌ％未満の条件を満足するように構成されるのが好ましい。 Further, in this example, the case where the flow rate of cleaning hydrogen / the flow rate of hydrogen in the hydrogen-containing gas A = 0.25, the amount of cleaning hydrogen / saturated hydrogen storage amount × 100 = 2.5 mol% has been described. However, it is not necessarily limited to this, and the ratio of the flow rate of the cleaning hydrogen to the flow rate of hydrogen in the hydrogen-containing gas A satisfies the condition of 0.05 or more and less than 1.00, and the cleaning with respect to the saturated hydrogen storage amount It is preferable that the ratio of the amount of hydrogen used is configured to satisfy the condition of 0.5 mol% or more and less than 20 mol%.
また、水素以外のガスに特に水素吸蔵合金の被毒要因となるＣＯが含まれている場合は、前段でＣＯ選択吸着剤を用いて除去してもよい。 Further, in the case where CO other than hydrogen, which is a poisoning factor of the hydrogen storage alloy, is contained in the gas other than hydrogen, it may be removed using a CO selective adsorbent in the previous stage.
１ａ、１ｂ、１ｃ、１ｄ：水素回収塔
２ａ、２ｂ、２ｃ、２ｄ：媒体流通路
３：圧力コントロール弁
４、５：弁
６：真空ポンプ
７、８：マスフローコントローラ
Ａ：水素含有ガス
Ｂ：オフガス
Ｃ：高純度水素（製品水素）
1a, 1b, 1c, 1d: Hydrogen recovery towers 2a, 2b, 2c, 2d: Medium flow passage 3: Pressure control valve 4, 5: Valve 6: Vacuum pump 7, 8: Mass flow controller A: Hydrogen-containing gas B: Off gas C: High purity hydrogen (product hydrogen)
Claims (8)
前記パージ工程と前記水素放出工程との間に、前記パージ工程後にも水素回収塔内に残る不純物を前記高純度水素の一部（以下、「洗浄用水素」と称す）を用いて洗浄する洗浄工程を有し、
この洗浄工程で排出される洗浄オフガスを回収し、この回収した洗浄オフガスを水素吸蔵工程が実施されるタイムステップにある水素回収塔および／または水素吸蔵工程の直前に設けた水素回収塔内の水素吸蔵合金を予め冷却する冷却工程が実施されるタイムステップにある水素回収塔に供給するようにしたことを特徴とする高純度水素精製方法。 A hydrogen storage step of passing the hydrogen-containing gas through a hydrogen recovery tower filled with a hydrogen storage alloy, and storing the hydrogen in the hydrogen-containing gas into the hydrogen storage alloy, and the hydrogen after storing the hydrogen in the hydrogen storage alloy A purge step for purging the impurity gas remaining in the recovery tower; and a hydrogen release step for releasing high-purity hydrogen by releasing the hydrogen stored in the hydrogen storage step after the purge step. In the purified high purity hydrogen purification method,
Cleaning that cleans impurities remaining in the hydrogen recovery tower after the purging step with a part of the high-purity hydrogen (hereinafter referred to as “cleaning hydrogen”) between the purging step and the hydrogen releasing step. Having a process,
The cleaning off-gas discharged in this cleaning process is recovered, and the recovered cleaning off-gas is supplied to the hydrogen recovery tower in the time step where the hydrogen storage process is performed and / or the hydrogen in the hydrogen recovery tower provided immediately before the hydrogen storage process. A high-purity hydrogen refining method, characterized in that it is supplied to a hydrogen recovery tower at a time step in which a cooling step for cooling the storage alloy in advance is performed.
前記ＡＢ５系水素吸蔵合金の温度制御用の媒体流通路が前記水素回収塔の内側または外側に設けられ、
前記水素吸蔵工程、パージ工程、洗浄工程と冷却工程においては、前記媒体流通路に０℃以上４０℃未満の媒体を流通させ、
前記水素放出工程と加熱工程においては、前記媒体流通路に４０℃以上１５０℃未満の媒体を流通させることを特徴とする請求項２に記載の高純度水素精製方法。 The hydrogen storage alloy is an AB5-based hydrogen storage alloy, and the hydrogen equilibrium pressure at 25 ° C. of the AB5-based hydrogen storage alloy is 0.05 MPa or more and 0.3 MPa or less,
A medium flow passage for temperature control of the AB5 hydrogen storage alloy is provided inside or outside the hydrogen recovery tower,
In the hydrogen storage step, purge step, cleaning step and cooling step, a medium having a temperature of 0 ° C. or higher and lower than 40 ° C. is circulated through the medium flow path,
The high-purity hydrogen purification method according to claim 2, wherein in the hydrogen releasing step and the heating step, a medium having a temperature of 40 ° C or higher and lower than 150 ° C is circulated through the medium flow path.
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| JP2014152087A (en) * | 2013-02-12 | 2014-08-25 | Kobe Steel Ltd | Hydrogen production apparatus |
| CN115724402A (en) * | 2022-12-08 | 2023-03-03 | 西安交通大学 | Method and system for purifying industrial byproduct hydrogen-containing tail gas and hydrogen |
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| JPS5556001A (en) * | 1978-10-19 | 1980-04-24 | Chiyoda Chem Eng & Constr Co Ltd | Production of hydrogen from off gas or the like |
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| JP2014152087A (en) * | 2013-02-12 | 2014-08-25 | Kobe Steel Ltd | Hydrogen production apparatus |
| CN115724402A (en) * | 2022-12-08 | 2023-03-03 | 西安交通大学 | Method and system for purifying industrial byproduct hydrogen-containing tail gas and hydrogen |
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