JP5690165B2 - PSA high purity hydrogen production method - Google Patents

Description

  The present invention relates to a pressure swing adsorption (hereinafter referred to as “PSA”) type high-purity hydrogen production method for efficiently producing high-purity hydrogen used in fuel cells and the like.

  In recent years, coupled with measures to prevent global warming, the departure of energy from crude oil dependence has become an important issue on a global scale, and not only developed countries in Europe, where efforts for environmental conservation are ahead, but also the United States and Japan. In other Asian countries as well, efforts toward the practical application of fuel cells using hydrogen gas as an energy source have become active.

Much research has been carried out on the production method of hydrogen gas used as fuel for fuel cells, but the most inexpensive and highly feasible production methods are currently natural gas, LPG, kerosene, gasoline, methanol as raw materials. In this method, dimethyl ether or the like is used to reform these to produce hydrogen gas. In a method for producing hydrogen gas by reforming such raw materials, for example, a process for producing hydrogen by reforming natural gas, the steam reforming method is usually used most often. The main component of natural gas is methane (CH ₄ ), and hydrogen is generated by the following two-stage reaction in the steam reforming method.

(1) Reforming reaction
CH ₄ + H ₂ O → CO + 3H ₂
(2) Metamorphic reaction
CO + H ₂ O → CO ₂ + H ₂

If the reaction as described above proceeds ideally, the products are only H ₂ and CO ₂ , but actually, in order to use excess water vapor from the viewpoint of preventing carbon generation by methane coking, In the gas after the quality reaction and the modification reaction (hereinafter referred to as “reformed gas”), together with hydrogen (H ₂ ), water vapor (H ₂ O), unreacted methane (CH ₄ ), carbon monoxide ( CO), and carbon dioxide (CO ₂ ). In general, fuel hydrogen for a fuel cell vehicle is required to have a hydrogen purity of about 5N (99.999% by volume (hereinafter, "volume%" is simply referred to as "%")). From the viewpoint of preventing poisoning deterioration of platinum (Pt) used as an electrode catalyst for polymer fuel cells, it is necessary to lower the concentration to 10 ppm or less, and when considering the durability of the fuel cell, about 0.2 ppm or less. It is said that it is necessary to reduce the concentration.

  As a method for producing high-purity hydrogen as described above from reformed gas, a PSA-type high-purity hydrogen production method that can recover hydrogen at a high recovery rate using two-stage PSA has been developed (for example, Patent Document 1). See). In the technique disclosed in Patent Document 1, the second stage PSA adsorption tower is used as a cleaning gas for regeneration of the adsorbent in the first and second stage PSA adsorption towers and as a pressure increasing gas for each PSA adsorption tower. It is based on using a part of the high purity hydrogen (product hydrogen) obtained in (1). Also disclosed is a technique in which off-gas discharged from the second stage PSA adsorption tower is used as a cleaning gas for regeneration of the adsorbent in the first stage PSA adsorption tower.

  In addition, in a pure hydrogen production apparatus using PSA, a technique is also disclosed in which off-gas is used to raise the temperature of a catalytic combustor or a reformer provided downstream of the catalytic combustor (see, for example, Patent Document 2). ).

JP 2007-015910 A JP 2004-352511 A

  In the PSA-type high-purity hydrogen production method disclosed in the above-mentioned Patent Document 1, the cleaning gas for regeneration of the adsorbent in each of the first and second PSA adsorption towers and the purified gas as the pressurizing gas for each PSA adsorption tower are used. Product hydrogen is lost because pure hydrogen is consumed. Further, the off-gas discharged from the second stage PSA adsorption tower is used as a cleaning gas for regeneration of the adsorbent in the first stage PSA adsorption tower, so that the loss of product hydrogen is somewhat reduced. However, hydrogen is still contained in the off gas discharged from the second stage PSA adsorption tower, and this hydrogen is discharged as it is from the first stage PSA adsorption tower as an off gas. There was a problem of preventing improvement.

  Further, the method of utilizing off-gas in the pure hydrogen production apparatus disclosed in Patent Document 2 does not basically lead to an improvement in the recovery rate of high-purity hydrogen.

  An object of the present invention is to provide a PSA-type high-purity hydrogen production method capable of reducing loss of product hydrogen and recovering high-purity hydrogen from reformed gas at a high recovery rate.

In order to achieve this object, the invention according to claim 1 of the present invention provides:
A reforming step for reforming the reforming raw material to obtain a hydrogen-rich reformed gas, and the reformed gas whose pressure has been increased to a predetermined pressure is passed through a first PSA adsorption tower filled with a CO adsorbent to produce CO. A CO adsorption step for adsorbing and removing CO to remove CO, a CO adsorbent regeneration step for regenerating the CO adsorbent, and a first pressure increase step for increasing the pressure in the first PSA adsorption tower to a predetermined pressure. The CO removal gas obtained in the first removal step and the CO adsorption step is passed through a second PSA adsorption tower filled with an unnecessary gas adsorbent other than CO to adsorb and remove unnecessary gas other than CO. An unnecessary gas adsorption step other than CO for obtaining pure hydrogen, an unnecessary gas adsorbent regeneration step for regenerating unnecessary gas adsorbent other than CO, and a pressure in the second PSA adsorption tower are increased to a predetermined pressure. 2 boost steps and A second removal step, a temporary storage step for temporarily storing the high-purity hydrogen obtained in the second removal step in a buffer tank provided at a subsequent stage of the second PSA adsorption tower, and the second A hydrogen storage step of passing off gas discharged from the PSA adsorption tower through a hydrogen storage tank filled with a hydrogen storage alloy, and storing the hydrogen in the off gas into the hydrogen storage alloy at a predetermined temperature and pressure, and the hydrogen storage step A hydrogen storage step having a hydrogen release step of releasing the hydrogen stored in the hydrogen storage alloy at a predetermined timing after the step into the hydrogen storage tank at a predetermined temperature and a predetermined pressure, and
In the CO adsorbent regeneration step and the first pressure increase step, high-purity hydrogen temporarily stored in the buffer tank (hereinafter referred to as “high-purity hydrogen in the buffer tank”) and hydrogen released into the hydrogen storage tank (Hereinafter referred to as “hydrogen in the hydrogen storage tank”) at least the hydrogen in the hydrogen storage tank is used as the regeneration gas for the regeneration of the CO adsorbent and the pressurizing gas for the first PSA adsorption tower,
In the unnecessary gas adsorbent regeneration step other than the CO and the second boosting step, at least the high-purity hydrogen in the buffer tank and the high-purity hydrogen in the buffer tank out of the high-purity hydrogen in the buffer tank and the hydrogen in the hydrogen storage tank are converted into the CO. A PSA-type high-purity hydrogen production method characterized by being used as a cleaning gas for regeneration of an unnecessary gas adsorbent other than the above and as a pressurizing gas for the second PSA adsorption tower.

The invention according to claim 2 is the invention according to claim 1,
The first PSA adsorption tower is further filled with H ₂ O adsorbent for adsorbing and removing water vapor (hereinafter referred to as “H ₂ O”) in the reformed gas whose pressure has been increased to the predetermined pressure. By
Play the first removal step, a "CO and _H 2 O" sorbent _{step H 2} O was adsorbed and removed to obtain a "CO and _H 2 O" stripping gas with CO, the CO adsorbent and _{H 2} O adsorbent A CO adsorbent and H ₂ O adsorbent regeneration step, and a first pressure increasing step for increasing the pressure in the first PSA adsorption tower to a predetermined pressure,
In the second removal step, the “ CO and H ₂ O ” removal gas obtained in the “ CO and H ₂ O ” adsorption step is filled with an unnecessary gas adsorbent other than “ CO and H ₂ O ” . and the unnecessary gas adsorption steps other than through the second PSA adsorption tower "CO and _H 2 O" other unwanted gases removed by adsorption obtain high purity hydrogen "CO and _H 2 O", the "CO and _H 2 O and "CO and H ₂ O" unnecessary gas adsorbent regeneration step except for reproducing unnecessary gas adsorption agent other than "a second boosting step which boosts the pressure of the second PSA adsorption tower at a predetermined pressure It has a configuration that
In the CO adsorbent and H ₂ O adsorbent regeneration step and the first pressure increase step, at least hydrogen in the hydrogen storage tank out of high purity hydrogen in the buffer tank and hydrogen in the hydrogen storage tank is Used as a cleaning gas for regeneration of the CO adsorbent and H ₂ O adsorbent and the pressure increasing gas of the first PSA adsorption tower,
In the unnecessary gas adsorbent regeneration step other than the “ CO and H ₂ O ” and the second boosting step, at least the high-purity hydrogen in the buffer tank and the hydrogen in the hydrogen storage tank are in the buffer tank. High-purity hydrogen is used as a cleaning gas for regenerating unnecessary gas adsorbents other than the “ CO and H ₂ O ” , and as a pressurizing gas for the second PSA adsorption tower.

The invention according to claim 3 is the invention according to claim 1 or 2,
The reforming step is one of the following steps (a) to (e).
(A) Step of reforming the reforming raw material with steam to obtain a hydrogen-rich reformed gas (b) Step of reforming the reforming raw material after reforming with steam to obtain a hydrogen-rich reformed gas ( c) Step of reforming a hydrocarbon-containing fuel by partial oxidation to obtain a hydrogen-rich reformed gas (d) Reforming the hydrocarbon-containing fuel by partial oxidation and simultaneously reforming with steam to hydrogen-rich reforming Step of obtaining gas (e) Step of obtaining a hydrogen-rich reformed gas by reforming a hydrocarbon-containing fuel with steam and then circulating a crude separation membrane such as a ceramic filter to increase the hydrogen concentration

The invention according to claim 4 is the invention according to any one of claims 1 to 3,
Each of the first PSA adsorption tower, the second PSA adsorption tower, and the hydrogen storage tank includes three or more.

The invention according to claim 5 is the invention according to any one of claims 1 to 4,
In the hydrogen releasing step, heat generated in the reforming step is used to obtain a predetermined temperature and a predetermined pressure for releasing the hydrogen stored in the hydrogen storage alloy into the hydrogen storage tank. .

As described above, according to the PSA method high-purity hydrogen production method according to the present invention,
A first removal step using a first PSA adsorption tower; a second removal step using a second PSA adsorption tower provided downstream of the first removal step; and the second removal. A temporary storage step of temporarily storing the high-purity hydrogen (product hydrogen) obtained in the step in a buffer tank provided at the subsequent stage of the second PSA adsorption tower; and an off-gas discharged from the second PSA adsorption tower. A hydrogen storage step for storing hydrogen in the off-gas in the hydrogen storage alloy at a predetermined temperature and a predetermined pressure through a hydrogen storage tank filled with a hydrogen storage alloy, and at a predetermined timing after the hydrogen storage step A hydrogen storage and release step having a hydrogen release step of releasing hydrogen stored in the alloy into the hydrogen storage tank at a predetermined temperature and a predetermined pressure,
In the CO adsorbent regeneration step and the first pressure increase step in the first removal step, at least hydrogen in the hydrogen storage tank out of high purity hydrogen in the buffer tank and hydrogen in the hydrogen storage tank is converted into the CO. Used as a cleaning gas for regeneration of the adsorbent and a pressure increasing gas for the first PSA adsorption tower,
In the unnecessary gas adsorbent regeneration step other than CO and the second pressure increase step in the second removal step, at least the high purity hydrogen in the buffer tank and the hydrogen in the hydrogen storage tank are high. In order to use pure hydrogen as a cleaning gas for regenerating unnecessary gas adsorbents other than CO and a pressurizing gas for the second PSA adsorption tower,
It is possible to provide a PSA type high-purity hydrogen production method capable of reducing product hydrogen loss and recovering high-purity hydrogen from reformed gas at a high recovery rate.

It is explanatory drawing which illustrates typically the outline | summary of a structure of the PSA system high purity hydrogen manufacturing apparatus which concerns on one Embodiment of this invention.

    Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is an explanatory view for schematically explaining an outline of a configuration of a PSA type high-purity hydrogen production apparatus according to an embodiment of the present invention.

In FIG. 1, 1 is a reformer for reforming a reforming raw material A to obtain a hydrogen-rich reformed gas B, and 2 is boosted to a high pressure {eg, 0.9 MPaG (gauge pressure)} as a predetermined pressure. reformate CO with the gas B _{H 2} O was adsorbed and removed "CO and _H 2 O" stripping gas first PSA apparatus for obtaining, 3 is provided downstream of the first PSA unit 2, the "CO and A _second PSA device for obtaining high-purity hydrogen (product hydrogen) C by adsorbing and removing unnecessary gases other than “ CO and H ₂ O ” from the “ H ₂ O ” removal gas, and 4 is provided in the subsequent stage of the second PSA device 3 The buffer tank 5 temporarily stores the high-purity hydrogen (product hydrogen) C obtained by the second PSA device 3, and occludes and releases the hydrogen in the off-gas D discharged from the second PSA device 3. Hydrogen storage tank (5a) filled with hydrogen storage alloy 5b, a hydrogen storage portion composed 5c).

The first PSA apparatus 2 has three first PSA adsorption towers 2a, 2b, and 2c, and each first PSA adsorption tower 2a, 2b, and 2c includes a CO adsorbent and an H ₂ O adsorbent. Is filled. As this CO adsorbent, for example, one in which copper (I) chloride is supported on alumina is used, and activated alumina is used as the H ₂ O adsorbent. In the first PSA adsorption tower (2a, 2b, 2c), the CO adsorbent and the H ₂ O adsorbent are respectively installed on the downstream side and the H ₂ O adsorbent on the upstream side. Is preferred.

The second PSA apparatus 3 includes three second PSA adsorption towers 3a, 3b, and 3c, and each of the second PSA adsorption towers 3a, 3b, and 3c includes other than “ CO and H ₂ O ” . Unnecessary gas adsorbent is filled. As an unnecessary gas (that is, CO ₂ , CH ₄ ) adsorbent other than “ CO and H ₂ O ” , for example, activated carbon is used.

  The hydrogen storage unit 5 includes three hydrogen storage tanks 5a, 5b, and 5c, and the hydrogen storage tanks 5a, 5b, and 5c are filled with a hydrogen storage alloy. As this hydrogen storage alloy, for example, an AB5 hydrogen storage alloy is used.

  Line 101 is an introduction line of reformed gas B. The line 101 and the first PSA adsorption towers 2a, 2b, and 2c are connected to each other through a valve PU-1A, a valve PU-1B, and a valve PU-1C.

  The line 102 is a line used for depressurizing the inside of the first PSA adsorption towers 2a, 2b, and 2c. Each of the first PSA adsorption towers 2a, 2b, and 2c after completion of pressure equalization (see the pressure equalization step described later) is used. It is used to further reduce the pressure to near normal pressure (for example, 0.1 MPaG) (see the first pressure reducing step described later). The line 102 is connected to the first PSA adsorption towers 2a, 2b, and 2c via the valve V16, the valve PU-3A, the valve PU-3B, and the valve PU-3C, respectively. The exhaust gas in the line 102 is exhausted as off-gas E.

  The line 103 further depressurizes each first PSA adsorption tower 2a, 2b, 2c, which has been depressurized to near atmospheric pressure (first depressurizing step), to a negative pressure of atmospheric pressure or lower (for example, −0.05 MPaG or lower) ( The vacuum pump 6 and the first PSA adsorption towers 2a, 2b, 2c are respectively connected via a valve V17, a valve PU-3A, a valve PU-3B, and a valve PU-3C. Connected. The exhaust gas of the vacuum pump in line 103 is exhausted as off-gas E.

The line 104 collects the “ CO and H ₂ O ” removal gas obtained by removing the “ CO and H ₂ O ” from the reformed gas B in the first PSA adsorption towers 2a, 2b, and 2c. Are connected to the first PSA adsorption towers 2a, 2b and 2c via valves PU-2A, PU-2B and PU-2C, respectively. The second PSA adsorption towers 3a, 3b, 3c are connected via a valve V10, a valve PV-1A, a valve PV-1B, and a valve PV-1C.

A line 105 is a high-purity hydrogen recovery line obtained by removing unnecessary gases other than “ CO and H ₂ O ” in the second PSA adsorption towers 3a, 3b, and 3c. The second PSA adsorption tower 3a, 3b and 3c are connected to each other through a valve PV-2A, a valve PV-2B, and a valve PV-2C. The recovered high-purity hydrogen is temporarily stored in the buffer tank 4.

The line 106 is a line for performing pressure equalization (see the pressure equalization step in the second PSA adsorption towers 3a, 3b, and 3c described later), and the completion of unnecessary gas adsorption steps other than “ CO and H ₂ O ” described later. The second PSA adsorption tower and the second PSA adsorption tower after the unnecessary gas adsorbent regeneration step other than “ CO and H ₂ O ” to be described later are used to equalize the gas. Specifically, among the valves PV-4A, PV-4B, and PV-4C, two second valves connected to two towers that perform pressure equalization are opened, and the other second valves are closed by closing the other valves. It is possible to equalize the pressure in the PSA adsorption tower.

  The line 107 is a line used for depressurizing the inside of the second PSA adsorption towers 3a, 3b, and 3c. Each of the second PSA adsorption towers 3a, 3b, and 3c for which pressure equalization (see the pressure equalization step described later) has been completed is performed. It is used to further reduce the pressure to near normal pressure (for example, 0.1 MPaG) (see the first pressure reducing step described later). The line 107 is connected to the second PSA adsorption towers 3a, 3b, and 3c through the valves PV-3A, PV-3B, and PV-3C, respectively, and the off-gas D is supplied from the hydrogen storage alloy through the valve V14. A line for introducing hydrogen into the filled hydrogen storage tanks 5a, 5b, and 5c and causing the hydrogen storage alloy to store hydrogen in the offgas D at a predetermined temperature (for example, 20 ° C.) and a predetermined pressure (for example, 0.1 MPaG). But there is. The line 107 and the hydrogen storage tanks 5a, 5b, and 5c are connected through a valve V14, a valve PW-1A, a valve PW-1B, and a valve PW-1C.

  The line 108 further depressurizes each of the second PSA adsorption towers 3a, 3b, and 3c, which has been depressurized to near atmospheric pressure (first depressurizing step), to a negative pressure of atmospheric pressure or lower (for example, −0.05 MPaG or lower) ( The vacuum pump 7 and the second PSA adsorption towers 3a, 3b, 3c are respectively connected to the valve V15, the valve PV-3A, the valve PV-3B, and the valve PV-3C. The exhaust gas from the vacuum pump 7 is introduced into the hydrogen storage tanks 5a, 5b, 5c filled with the hydrogen storage alloy as the off gas D, and the hydrogen in the off gas D is set to a predetermined temperature (for example, 20 ° C.) and It is also a line for allowing the hydrogen storage alloy to store under a predetermined pressure (for example, −0.05 MPaG or less). Further, the vacuum pump 7 and the hydrogen storage tanks 5a, 5b, and 5c are connected through a valve PW-1A, a valve PW-1B, and a valve PW-1C.

A line 109 is a first hydrogen gas stored in the hydrogen storage alloy, which is described later with hydrogen released into the hydrogen storage tanks 5a, 5b, and 5c under a predetermined temperature (for example, 200 ° C.) and a predetermined pressure (for example, 0.9 MPaG). Pressures in the first PSA adsorption towers 2a, 2b, and 2c, which will be described later, and for the regeneration step for regenerating the CO adsorbent and H ₂ O adsorbent in the PSA adsorption towers 2a, 2b, and 2c of , 0.9 MPa) is a line that is supplied for the first boosting step. The line 109 and the hydrogen storage tanks 5a, 5b, and 5c are connected through a valve V18, a valve PW-2A, a valve PW-2B, and a valve PW-2C. The line 109 and the first PSA adsorption towers 2a, 2b, and 2c are connected to each other through a valve PU-4A, a valve PU-4B, and a valve PU-4C.

The line 110 is used for an unnecessary gas adsorbent regeneration step other than “ CO and H ₂ O ” in the second PSA adsorption towers 3a, 3b, and 3c, which will be described later, with respect to the hydrogen released into the hydrogen storage tanks 5a, 5b, and 5c. This is a line for supplying a second pressure increasing step for increasing the pressure in second PSA adsorption towers 3a, 3b, and 3c described later to a predetermined pressure (for example, 0.9 MPaG). The pressure in the second PSA adsorption towers 3a, 3b and 3c for the unnecessary gas adsorbent regeneration step other than “ CO and H ₂ O ” and the pressure in the second PSA adsorption towers 3a, 3b and 3c described later is set to a predetermined pressure (for example, , 0.9 MPaG), the high-purity hydrogen temporarily stored in the buffer tank 4 is supplied via the valve V12 together with the hydrogen supplied via the line 110 described above. Is done. The line 110 and the hydrogen storage tanks 5a, 5b, and 5c are connected through a valve V19, a valve PW-2A, a valve PW-2B, and a valve PW-2C. The line 110 and the second PSA adsorption towers 3a, 3b, and 3c are connected to each other via a valve V13 and a valve PV-5A, a valve PV-5B, and a valve PV-5C, respectively. In addition, the buffer tank 4 and the second PSA adsorption towers 3a, 3b, and 3c are connected to each other via a valve PV12 and a valve PV-5A, a valve PV-5B, and a valve PV-5C, respectively.

  First, the reforming process will be described.

(Reforming process)
In the reforming step of the present invention, for example, a reformer 1 comprising a combination of a steam reformer and a transformer that are usually used may be used. After reforming the reforming raw material A containing hydrocarbons such as natural gas with steam in a reformer to make a gas mainly composed of H ₂ and CO, steam is further added to this gas in the transformer. The reformed gas B which is added and transformed to form H ₂ as a main component (hydrogen-rich) is generated. During this reformed gas B, other _{H 2,} etc. with a small amount of _{CO 2, CH 4, H 2} O, remaining the CO of about 0.9%. In the first removal step described below for adsorbing and removing H ₂ O together with CO, which is a subsequent step of the reforming step, and in the second removing step described later for adsorbing and removing unnecessary gases other than “ CO and H ₂ O ” . Since the adsorption reaction is accelerated at lower temperatures, a heat exchanger (not shown) for cooling the high-temperature reformed gas B is provided in the line 101 between the reformer 1 and the first PSA device 2. It is desirable to provide it.

Next, “ CO and H ₂ O ” adsorption removal, CO adsorbent and H ₂ O adsorbent regeneration and pressure increase in the first PSA adsorption tower in the first removal step, which is a subsequent step of the reforming step The procedure will be specifically described. Although only the operation procedure of the first PSA adsorption tower 2a will be described below, the operation uses three towers of the first PSA adsorption towers 2a, 2b and 2c as shown in the time table of Table 1 below. And do it cyclically.

1) [ “ CO and H ₂ O ” adsorption step]: The reformed gas B whose pressure has been increased to the predetermined pressure (0.9 MPaG) is introduced into the first PSA adsorption tower 2a, and CO and H ₂ O are converted into CO, respectively. removed by the adsorbent and _{H 2} O adsorbent to recover a "CO and _H 2 O" stripping gas, further introducing the "CO and _H 2 O" stripping gas into the second PSA adsorption tower 3a (valve PU -3A, valve PU-4A: closed, valve PU-1A, valve PU-2A, valve V10: open).

2) [Pressure equalization step]: The above-mentioned “ CO and H ₂ O ” adsorption step is completed, and a part of the gas in the first PSA adsorption tower 2a is removed from the CO adsorbent and H ₂ O adsorbent regeneration step. 1 is transferred to the PSA adsorption tower 2c. Here, for example, when the “ CO and H ₂ O ” adsorption operation is performed on the first PSA adsorption tower 2 a at 0.9 MPaG, the CO adsorbent and the H ₂ O adsorbent of the first PSA adsorption tower 2 a are decompressed. In this step, the internal pressures of the first PSA adsorption towers 2a and 2c are all about 0.4 MPaG (valves V18, PU-1A, PU-2A, PU-3A, PU-1C, PU -2C, PU-3C: closed, PU-4A, PU-4C: open). During this pressure equalization step, unnecessary gases other than hydrogen in the hydrogen storage tank 5c are exhausted as off-gas E (valves V18, V19, PW-2A, PW-2B, PW-1C: closed, valve V20, PW-2C: Open), and then hydrogen stored in the hydrogen storage alloy is released into the hydrogen storage tank 5c at the predetermined temperature and pressure (hydrogen release step) to prepare for the next hydrogen supply.

  3) [First decompression step]: The internal pressure of the first PSA adsorption tower 2a after the pressure equalization step is reduced to near normal pressure (for example, 0.1 MPaG) (valves PU-1A, PU-2A, PU- 4A: closed, valve V16, PU-3A: open).

  4) [Second Depressurization Step]: The first PSA adsorption tower 2a depressurized to a pressure close to normal pressure is further depressurized to a negative pressure (for example, −0.05 MPaG or less) using the vacuum pump 6 (valve PU−). 1A, PU-2A, PU-4A: closed, valve V17, PU-3A: open).

5) [CO adsorbent and H ₂ O adsorbent regeneration step]: The hydrogen in the hydrogen storage tank 5c is replaced with the CO adsorbent and H in the first PSA adsorption tower 2a in a state where the first PSA adsorption tower 2a is decompressed. _{As a} cleaning gas for regeneration of ₂ O adsorbent, CO adsorbent and H ₂ O adsorbent are regenerated (valve V10, PU-1A, PU-2A, PW-2A, PW-2B, PW-1C: closed, Valve V17, PU-3A, PU-4A, V18, PW-2C: open).

6) [pressure equalization step]: CO adsorbent and the first PSA adsorption tower 2b reproduction of _{H 2} O adsorbent has finished the first "CO and _H 2 O" sorbent step PSA adsorption tower 2a ended Part of the gas is transferred (valve V18, PU-1A, PU-2A, PU-3A, PU-1B, PU-2B, PU-3B: closed, valves PU-4A, PU-4B: opened). During this pressure equalization step, unnecessary gases other than hydrogen in the hydrogen storage tank 5a are exhausted as off-gas E (valves V18, V19, PW-1A, PW-1B, PW-2B, PW-1C, PW). -2C: closed, valve V20, PW-2A: opened), and then the hydrogen stored in the hydrogen storage alloy is released into the hydrogen storage tank 5a at the predetermined temperature and pressure (hydrogen release step). Prepare for hydrogen supply.

7) [First pressurization step]: Hydrogen in the hydrogen storage tank 5a is supplied as a pressurization gas into the first PSA adsorption tower 2a, and the pressure in the first PSA adsorption tower 2a is set to “ CO and H _2. O ” is increased to the above-mentioned predetermined pressure for adsorption (valve V10, PU-1A, PU-2A, PU-3A, PW-1A, PW-2B, PW-2C: closed, valve V18, PU-4A, PW-2A: Open).

8) The above operation steps 1) to 7) are repeated, and “ CO and H ₂ O ” adsorption removal, CO adsorbent and H ₂ O adsorbent regeneration, and pressurization in the first PSA adsorption tower are repeated.

Next, unnecessary gas adsorption removal other than “ CO and H ₂ O ” in the second removal step, which is a step subsequent to the first removal step, regeneration of unnecessary gas adsorbent other than “ CO and H ₂ O ” , and second Each operation procedure of pressure increase in the second PSA adsorption tower will be specifically described. In the following, only the operation procedure of the second PSA adsorption tower 3a will be described, but the operation uses three towers of the second PSA adsorption towers 3a, 3b and 3c as shown in the time table of Table 2 below. And do it cyclically.

11) [ "CO and _H 2 O" other unnecessary gas adsorption step: introducing the "CO and _H 2 O" stripping gas obtained in the first removal step to the second PSA adsorption tower 3a, " with the CO and H ₂ O "other unnecessary gas is removed by unwanted gas adsorbent other than" CO and H ₂ O ", and recover high purity hydrogen, and further temporarily stores the high-purity hydrogen into the buffer tank 4 Product hydrogen C is obtained (valve PV-3A, valve PV-4A, PV-5A: closed, valve V10, PV-1A, valve PV-2A: open).

12) [Pressure equalization step]: The unnecessary gas adsorption step other than “ CO and H ₂ O ” is finished, and a part of the gas in the second PSA adsorption tower 3a is used as an unnecessary gas other than “ CO and H ₂ O ”. The adsorbent regeneration step is transferred to the second PSA adsorption tower 3c. Here, for example, in the case of performing the unnecessary gas adsorption operation other than "CO and _H 2 O" a second PSA adsorption tower 3a by 0.9MPaG, "CO and _H 2 O" in the second PSA adsorption tower 3a Since unnecessary gas adsorbents other than those are regenerated under reduced pressure, the internal pressures of the second PSA adsorption towers 3a and 3c are all about 0.4 MPaG in this step (valves V11, PV-1A, PV-2A, PV -3A, PV-5A, PV-1C, PV-2C, PV-3C, PV-5C: closed, PV-4A, PV-4C: open). During this pressure equalization step, unnecessary gases other than hydrogen in the hydrogen storage tank 5c are exhausted as off-gas E (valves V18, V19, PW-2A, PW-2B, PW-1C: closed, valve V20, PW-2C: Open), and then hydrogen stored in the hydrogen storage alloy is released into the hydrogen storage tank 5c at the predetermined temperature and pressure (hydrogen release step) to prepare for the next hydrogen supply.

  13) [First decompression step]: The internal pressure of the second PSA adsorption tower 3a after the pressure equalization step is reduced to near normal pressure (for example, 0.1 MPaG), and off-gas D is filled with a hydrogen storage alloy. Hydrogen is introduced into the hydrogen storage tank 5a, and the hydrogen in the offgas D is stored in the hydrogen storage alloy at a predetermined temperature (for example, 20 ° C.) and a predetermined pressure (for example, 0.1 MPaG) (hydrogen storage step). 1A, PV-2A, PV-4A, PV-5A, PW-2A, PW-1B, PW-2B, PW-1C, PW-2C: closed, valves V14, PV-3A, PW-1A: opened).

  14) [Second Depressurization Step]: The second PSA adsorption tower 3a depressurized to a pressure close to normal pressure is further depressurized to a negative pressure (for example, −0.05 MPaG or less) using the vacuum pump 7, and the off-gas D Is introduced into a hydrogen storage tank 5a filled with a hydrogen storage alloy, and hydrogen in the offgas D is stored in the hydrogen storage alloy at a predetermined temperature (for example, 20 ° C.) and a predetermined pressure (for example, 0.1 MPaG) (hydrogen Occlusion step) (valves PV-1A, PV-2A, PV-4A, PV-5A, PW-2A, PW-1B, PW-2B, PW-1C, PW-2C: closed, valve V15, PV-3A PW-1A: Open).

15) [Regeneration step of unnecessary gas adsorbent other than “ CO and H ₂ O ” ]: The high-purity hydrogen in the buffer tank 4 and the hydrogen in the hydrogen storage tank 5c are removed while the second PSA adsorption tower 3a is decompressed. 2 is used as a cleaning gas for regeneration of unnecessary gas adsorbents other than “ CO and H ₂ O ” in the PSA adsorption tower 3a, and unnecessary gas adsorbents other than “ CO and H ₂ O ” are regenerated, and off-gas D is The hydrogen storage tank 5a filled with the hydrogen storage alloy is introduced, and the hydrogen in the offgas D is stored in the hydrogen storage alloy at the predetermined temperature and pressure (hydrogen storage step) (valves V18, V20, PV-1A). , PV-2A, PV-4A, PW-2A, PW-1B, PW-2B, PW-1C: closed, valves V12, V13, V15, V19, PV-5A, PV-3A, PW-1A, PW- 2C: ).

16) [pressure equalization step: the end of the "CO and _H 2 O" other than the second unnecessary gas adsorption steps other than "CO and _H 2 O" in PSA adsorption tower 3a, the reproduction of unwanted gas adsorbent ended A part of the gas in the second PSA adsorption tower 3b is transferred (valve V11, PV-1A, PV-2A, PV-3A, PV-5A, PV-1B, PV-2B, PV-3B, PV- 5B: closed, valves PV-4A, PV-4B: open). During this pressure equalization step, unnecessary gases other than hydrogen in the hydrogen storage tank 5a are exhausted as off-gas E (valves V18, V19, PW-1A, PW-1B, PW-2B, PW-1C, PW -2C: closed, valve V20, PW-2A: opened), and then the hydrogen stored in the hydrogen storage alloy is released into the hydrogen storage tank 5a at the predetermined temperature and pressure (hydrogen release step). Prepare for hydrogen supply.

17) [Second pressurization step]: The high-purity hydrogen in the buffer tank 4 and the hydrogen in the hydrogen storage tank 5a are supplied into the second PSA adsorption tower 3a as the pressurization gas, and the second PSA adsorption tower 3a is supplied. The internal pressure is increased to the predetermined pressure for adsorbing unnecessary gases other than “ CO and H ₂ O ” (valves V18, V20, PV-1A, PV-2A, PV-3A, PV-4A, PW- 1A, PW-1B, PW-2B, PW-1C, PW-2C: closed, valves V12, V13, V19, PV-5A, PW-2A: open).

18) above 11) to repeat step 17), "CO and _H 2 O" other unnecessary gas adsorption removal, "CO and _H 2 O" other unwanted gas adsorbent regeneration and second PSA adsorption tower Repeat the boosting.

In the present embodiment, in the first removal process having the CO adsorbent and H ₂ O adsorbent regeneration step and the first pressure increase step, hydrogen in any of the hydrogen storage tanks 5a, 5b, and 5c is converted into the CO adsorbent. And a cleaning gas for regeneration of the H ₂ O adsorbent and a pressurizing gas for the first PSA adsorption tower,
In the second removal step having the unnecessary gas adsorbent regeneration step other than “ CO and H ₂ O ” and the second pressure increasing step, the high-purity hydrogen in the buffer tank 4 and any of the hydrogen storage tanks 5a, 5b, The example in which the hydrogen in 5c is used as a cleaning gas for regeneration of an unnecessary gas adsorbent other than “ CO and H ₂ O ” and a pressure increasing gas for the second PSA adsorption tower has been described, but the present invention is not necessarily limited to this. Absent.

That is, in order to satisfy the technical idea of the present invention,
In the first removal step having a CO adsorbent and H ₂ O adsorbent regeneration step and a first pressure increase step, at least the hydrogen storage in the high purity hydrogen in the buffer tank and the hydrogen in the hydrogen storage tank. Hydrogen in the tank is used as a cleaning gas for regeneration of the CO adsorbent and H ₂ O adsorbent and a pressure increasing gas for the first PSA adsorption tower,
In the second removal process including the unnecessary gas adsorbent regeneration step other than “ CO and H ₂ O ” and the second pressure increasing step, the high purity hydrogen in the buffer tank and the hydrogen in the hydrogen storage tank At least the high-purity hydrogen in the buffer tank may be used as a cleaning gas for regenerating unnecessary gas adsorbents other than the “ CO and H ₂ O ” and a pressure increasing gas for the second PSA adsorption tower. Thereby, at least hydrogen in the off-gas D is utilized, and loss of product hydrogen can be reduced, and high-purity hydrogen can be recovered from the reformed gas at a high recovery rate.

  However, by adopting the configuration of the present embodiment, it is not necessary to use high-purity hydrogen (that is, product hydrogen) in the buffer tank in the first removal step, and the second removal is performed. In the process, the amount of high-purity hydrogen (that is, product hydrogen) in the buffer tank can be reduced, so that loss of product hydrogen can be further reduced and high-purity hydrogen can be recovered from the reformed gas at a higher recovery rate. Is preferred.

In the present embodiment, an example is described in which H ₂ O is adsorbed and removed together with CO in the first removing step, and unnecessary gases other than “ CO and H ₂ O ” are adsorbed and removed in the second removing step. However, it is not necessarily limited to this. For example, the configuration may be such that CO is adsorbed and removed in the first removal step, and unnecessary gases other than CO are adsorbed and removed in the second removal step. However, by adopting a configuration as in this embodiment (that is, a configuration in which H ₂ O is adsorbed and removed together with CO in the first removal step), the hydrogen storage alloy filled in the hydrogen storage tank is further deteriorated. Therefore, high purity hydrogen can be obtained at a high recovery rate over a long period of time while reducing loss of product hydrogen.
Note that "H _{2 O} adsorbed removed with CO" in the first removal step described above, an effect that through the adsorption step which can adsorb and remove CO and H _{2 O,} respectively full necessarily CO and H _{2 O} and However, it is not limited to the removal. In addition, the term “ adsorption removal of unnecessary gases other than “ CO and H ₂ O ” ” in the second removal step described above means that the unnecessary gas is passed through an adsorption step capable of adsorbing and removing the unnecessary gas. It is not limited to complete removal. Further, “CO removal by adsorption” in the first removal step described above means that an adsorption step that can absorb and remove CO is performed, and is not necessarily limited to complete removal of CO. Further, “adsorption removal of unnecessary gases other than CO” in the second removal step described above means that the unnecessary gas is passed through an adsorption step that can be removed by adsorption, and the unnecessary gas is not necessarily completely removed. It is not limited.

  Moreover, in this embodiment, although the example which has 3 towers in each of the 1st PSA apparatus 2 and the 2nd PSA apparatus 3 was demonstrated, it is not necessarily limited to this. For example, each of the first PSA device 2 and the second PSA device 3 may have two or four or more towers. However, in the case of two towers, pressure equalization cannot be performed, and the pressure energy of the high-pressure gas cannot be effectively recovered. In the present embodiment, the example in which the hydrogen storage unit 5 includes three hydrogen storage tanks has been described. However, the present invention is not necessarily limited thereto, and at least a plurality of hydrogen storage tanks may be provided.

In this embodiment, the off-gas D is stored in hydrogen in any of the first depressurization step, the second depressurization step, and the unnecessary gas adsorbent regeneration step other than “ CO and H ₂ O ” in the second removal step. Although the example introduced into the tank 5a has been described, the present invention is not necessarily limited to this, and at least the off-gas D in the unnecessary gas adsorbent regeneration step other than “ CO and H ₂ O ” is introduced into the hydrogen storage tank 5a. I just need it. Moreover, in this embodiment, although the example using the material by which copper chloride (I) as a copper halide (I) was carry | supported to alumina was demonstrated as CO adsorption agent, it is not necessarily limited to this. Absent. For example, as the CO adsorbent, copper (I) halide and / or copper (II) halide is supported on one or more carriers selected from the group consisting of silica, alumina, activated carbon, graphite and polystyrene resin. A material obtained by reducing or treating this material is preferably used. However, a material in which copper (I) chloride is supported on the alumina carrier used in this embodiment has a high selectivity for CO and is recommended.

(Example)
In order to confirm the effect of the present invention, a hydrogen purification experiment (high-purity hydrogen production experiment) was performed using the PSA system high-purity hydrogen production apparatus (same as the present embodiment) shown in FIG. The reforming raw material A is methanol, and the composition of the reformed gas B obtained by reforming the methanol by the reformer 1 is H ₂ : 70.3%, H ₂ O: 6.2%, CO: 0.00. 9%, CO ₂ : 22.5%, CH ₄ : 0.1%. In addition, the operation procedure in the first and second removal steps is the same as that in the above-described embodiment (that is, according to Tables 1 and 2 above).
<Time of each step in Table 1>
- "CO and _H 2 O" sorbent Step: 5 minutes - pressure equalization step: 10 seconds, a first decompression step: 50 seconds, a second pressure reduction step: 3 min - CO adsorbent and _{H 2} O adsorbent regeneration steps: Minute pressure equalization step: 10 seconds First pressure increase step: 4 minutes 50 seconds <Time of each step in Table 2>
・ Unnecessary gas adsorption step other than “ CO and H ₂ O ” : 5 minutes ・ equal pressure step: 10 seconds ・ first decompression step: 50 seconds ・ second decompression step: 3 minutes ・ other than “ CO and H ₂ O ” Unnecessary gas adsorbent regeneration step: 1 minute-Pressure equalization step: 10 seconds-Second pressure increase step: 4 minutes 50 seconds <Adsorbent used>
・ H ₂ O adsorbent: activated alumina (made by Union Showa: Part No. D-201)
・ CO adsorbent: Copper (I) chloride supported on alumina (co-developed by Kansai Thermochemical Co., Ltd.)
・ Unnecessary gas adsorbent other than “ CO and H ₂ O ” : Activated carbon (manufactured by Nippon Enviro Chemical: product number G2X)
<Used hydrogen storage alloy>
・ AB5 hydrogen storage alloy

(Comparative example)
The comparative example is different from the above embodiment in that it does not have the hydrogen storage unit 5 above all. In the comparative example, the off-gas D of the second PSA device 3 is used as the cleaning gas for regeneration of the CO adsorbent and the H ₂ O adsorbent in the first removal step, and each PSA adsorption of the first PSA device 2 is performed. Only the high-purity hydrogen (product hydrogen) C in the buffer tank 4 is used as the boosting gas for the tower, and the cleaning gas for regenerating unnecessary gas adsorbent other than “ CO and H ₂ O ” in the second removal step and the second The difference from the above embodiment is that only the high-purity hydrogen (product hydrogen) C in the buffer tank 4 is used as the pressure-increasing gas for each PSA adsorption tower of the second PSA apparatus 3. However, the operation time tables of the first and second removal steps are basically the same as those in Tables 1 and 2 above. Also, except for the conditions described here, in principle, the conditions are the same as in the above embodiment.

(Experimental result)
The recovery rates of high-purity hydrogen (99.999%) in Examples and Comparative Examples were 90.5% and 80.2%, respectively. The reason why the recovery rate of the example was improved by 10.3% as compared with the recovery rate of the comparative example was attributed to the effective utilization of hydrogen in the offgas D. In particular, in this embodiment, the off-gas D is used without using the high-purity hydrogen (product hydrogen) C in the buffer tank 4 as the pressure-increasing gas of the PSA adsorption towers 2a, 2b, and 2c of the first PSA device 2. The hydrogen in the hydrogen storage tanks 5a, 5b, 5c extracted from the inside was utilized, and the cleaning gas for regenerating unnecessary gas adsorbent other than “ CO and H ₂ O ” and the second in the second removal step The hydrogen in the hydrogen storage tanks 5a, 5b, and 5c extracted from the off-gas D is also used as the pressurizing gas for each of the PSA adsorption towers 3a, 3b, and 3c of the PSA apparatus 3 of the This is largely due to the effect of the substantial reduction in the amount of pure hydrogen (product hydrogen) C used.

  However, the high-purity hydrogen and hydrogen storage tanks 5a, 5b in the buffer tank 4 are used as the cleaning gas for regeneration of the CO adsorbent in the first removal step and the pressurizing gas for the first PSA adsorption towers 2a, 2b, 2c. Cleaning gas for regeneration of unnecessary gas adsorbent other than CO in the second removal step, and each PSA of the second PSA device 3 using at least hydrogen in the hydrogen storage tanks 5a, 5b, 5c in the hydrogen in 5c Adopting a configuration using high-purity hydrogen in the buffer tank 4 and at least high-purity hydrogen in the buffer tank 4 out of hydrogen in the hydrogen storage tanks 5a, 5b, and 5c as the boosting gas for the adsorption towers 3a, 3b, and 3c. If this is the case, the operational effects of the present invention can be obtained even if the operational effects as in the above-described embodiment are not reached (that is, the loss of product hydrogen is reduced and reforming is performed). Possible recovery of high purity hydrogen from the scan at a high recovery rate.).

1: reformer 2: first PSA devices 2a, 2b, 2c: first PSA adsorption tower 3: second PSA devices 3a, 3b, 3c: second PSA adsorption tower 4: buffer tank 5: hydrogen Storage parts 5a, 5b, 5c: Hydrogen storage tank A: Reforming raw material B: Reformed gas C: High-purity hydrogen (product hydrogen)
D, E: Off gas

Claims (5)

A reforming step for reforming the reforming raw material to obtain a hydrogen-rich reformed gas, and the reformed gas whose pressure has been increased to a predetermined pressure is passed through a first PSA adsorption tower filled with a CO adsorbent to produce CO. A CO adsorption step for adsorbing and removing CO to remove CO, a CO adsorbent regeneration step for regenerating the CO adsorbent, and a first pressure increase step for increasing the pressure in the first PSA adsorption tower to a predetermined pressure. The CO removal gas obtained in the first removal step and the CO adsorption step is passed through a second PSA adsorption tower filled with an unnecessary gas adsorbent other than CO to adsorb and remove unnecessary gas other than CO. An unnecessary gas adsorption step other than CO for obtaining pure hydrogen, an unnecessary gas adsorbent regeneration step for regenerating unnecessary gas adsorbent other than CO, and a pressure in the second PSA adsorption tower are increased to a predetermined pressure. 2 boost steps and A second removal step, a temporary storage step for temporarily storing the high-purity hydrogen obtained in the second removal step in a buffer tank provided at a subsequent stage of the second PSA adsorption tower, and the second A hydrogen storage step of passing off gas discharged from the PSA adsorption tower through a hydrogen storage tank filled with a hydrogen storage alloy, and storing the hydrogen in the off gas into the hydrogen storage alloy at a predetermined temperature and pressure, and the hydrogen storage step A hydrogen storage step having a hydrogen release step of releasing the hydrogen stored in the hydrogen storage alloy at a predetermined timing after the step into the hydrogen storage tank at a predetermined temperature and a predetermined pressure, and
In the CO adsorbent regeneration step and the first pressure increase step, high-purity hydrogen temporarily stored in the buffer tank (hereinafter referred to as “high-purity hydrogen in the buffer tank”) and hydrogen released into the hydrogen storage tank (Hereinafter referred to as “hydrogen in the hydrogen storage tank”) at least the hydrogen in the hydrogen storage tank is used as the regeneration gas for the regeneration of the CO adsorbent and the pressurizing gas for the first PSA adsorption tower,
In the unnecessary gas adsorbent regeneration step other than the CO and the second boosting step, at least the high-purity hydrogen in the buffer tank and the high-purity hydrogen in the buffer tank out of the high-purity hydrogen in the buffer tank and the hydrogen in the hydrogen storage tank are converted into the CO. A PSA-type high-purity hydrogen production method, characterized by being used as a cleaning gas for regeneration of an unnecessary gas adsorbent other than the above and as a pressurizing gas for the second PSA adsorption tower. The first PSA adsorption tower is further filled with H ₂ O adsorbent for adsorbing and removing water vapor (hereinafter referred to as “H ₂ O”) in the reformed gas whose pressure has been increased to the predetermined pressure. By
Play the first removal step, a "CO and _H 2 O" sorbent _{step H 2} O was adsorbed and removed to obtain a "CO and _H 2 O" stripping gas with CO, the CO adsorbent and _{H 2} O adsorbent A CO adsorbent and H ₂ O adsorbent regeneration step, and a first pressure increasing step for increasing the pressure in the first PSA adsorption tower to a predetermined pressure,
In the second removal step, the “ CO and H ₂ O ” removal gas obtained in the “ CO and H ₂ O ” adsorption step is filled with an unnecessary gas adsorbent other than “ CO and H ₂ O ” . and the unnecessary gas adsorption steps other than through the second PSA adsorption tower "CO and _H 2 O" other unwanted gases removed by adsorption obtain high purity hydrogen "CO and _H 2 O", the "CO and _H 2 O and "CO and H ₂ O" unnecessary gas adsorbent regeneration step except for reproducing unnecessary gas adsorption agent other than "a second boosting step which boosts the pressure of the second PSA adsorption tower at a predetermined pressure It has a configuration that
In the CO adsorbent and H ₂ O adsorbent regeneration step and the first pressure increase step, at least hydrogen in the hydrogen storage tank out of high purity hydrogen in the buffer tank and hydrogen in the hydrogen storage tank is Used as a cleaning gas for regeneration of the CO adsorbent and H ₂ O adsorbent and the pressure increasing gas of the first PSA adsorption tower,
In the unnecessary gas adsorbent regeneration step other than the “ CO and H ₂ O ” and the second boosting step, at least the high-purity hydrogen in the buffer tank and the hydrogen in the hydrogen storage tank are in the buffer tank. _2. The PSA system according to claim 1, wherein high-purity hydrogen is used as a cleaning gas for regenerating an unnecessary gas adsorbent other than the “ CO and H ₂ O ” and a pressurizing gas for the second PSA adsorption tower. High purity hydrogen production method. The PSA system high-purity hydrogen production method according to claim 1 or 2, wherein the reforming step is one of the following steps (a) to (e).
(A) Step of reforming the reforming raw material with steam to obtain a hydrogen-rich reformed gas (b) Step of reforming the reforming raw material with steam and then modifying to obtain a hydrogen-rich reformed gas ( c) Step of reforming the hydrocarbon-containing fuel by partial oxidation to obtain a hydrogen-rich reformed gas (d) Reforming the hydrocarbon-containing fuel by partial oxidation and simultaneously reforming with steam to hydrogen-rich reforming Step for obtaining gas (e) Step for obtaining a hydrogen-rich reformed gas by reforming a hydrocarbon-containing fuel with steam and then circulating a crude separation membrane such as a ceramic filter to increase the hydrogen concentration   4. The PSA-type high-purity hydrogen production according to claim 1, wherein each of the first PSA adsorption tower, the second PSA adsorption tower, and the hydrogen storage tank includes three or more. 5. Method.   In the hydrogen releasing step, heat generated in the reforming step is used to obtain a predetermined temperature and a predetermined pressure for releasing the hydrogen stored in the hydrogen storage alloy into the hydrogen storage tank. The PSA method high-purity hydrogen production method according to any one of claims 1 to 4.

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