JP3323322B2 - Method and apparatus for improving hydrogen purity - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for improving hydrogen purity.

[0002]

2. Description of the Related Art A conventional hydrogen purity improving device is disclosed in, for example, Japanese Patent Application Laid-Open No. 3-271101. This hydrogen purity improvement device connects a hydrogen utilization device and a hydrogen recovery container having a built-in hydrogen storage alloy and having a heating device and a cooling device attached thereto through an absorption pipe having a first pressure control valve, and connecting the valve. The discharge gas line having the above is connected to the hydrogen recovery container. According to this hydrogen purity improvement device, the purge gas line at the time of absorption is attached to the hydrogen recovery container connected to the hydrogen utilization device, and the purge gas line at the time of absorption is provided with a pressure control valve to adjust the set pressure of the pressure control valve. With this simple structure, it is possible to obtain a hydrogen gas having an improved hydrogen purity from either a low-purity hydrogen gas or a high-purity hydrogen gas at a high recovery rate by using one apparatus. Further, regardless of the purity of the low-purity hydrogen, a high-purity hydrogen gas can be obtained with high efficiency by fully utilizing the hydrogen storage capacity of the hydrogen storage alloy.

[0003] However, this conventional hydrogen purity improving apparatus can perform a process for improving the hydrogen purity of both low-purity hydrogen gas and high-purity hydrogen gas, but uses a single hydrogen recovery vessel. Due to the structure, there is a technical problem that each processing cannot be performed efficiently. In other words, the treatment for gradually improving the hydrogen purity of the low-purity hydrogen gas requires a large amount of treatment, and the treatment for maintaining the hydrogen purity of the high-purity hydrogen gas at a substantially constant level requires a small treatment amount. Should give priority to improving the hydrogen recovery rate,
A single hydrogen recovery vessel cannot address these effectively.

Another method for recovering low-concentration hydrogen using a conventional hydrogen storage alloy and purifying it to high purity is described in Japanese Patent Application Laid-Open No. 59-83905.
That is, a hydrogen gas raw material gas containing impurities was introduced into the most upstream container of a group of a plurality of serially connected containers holding the hydrogen storage alloy, and hydrogen gas was stored in the hydrogen storage alloy in the container. Thereafter, the present invention relates to a method for purifying hydrogen gas by releasing hydrogen gas, introducing the hydrogen gas into the next container, and repeating the same process in sequence.

[0005] However, another conventional method is a method in which the entire amount of hydrogen gas released after occlusion in the upstream vessel is introduced into the next vessel, and the same process is sequentially repeated to purify the hydrogen gas. In addition, since there is no means for switching the containers connected in series to a parallel state, it is not possible to perform efficient recovery and purification according to the purity of hydrogen gas. In particular, since the hydrogen is actively collected from the purge gas from the upstream vessel and is not reused, the hydrogen purity of the high-purity hydrogen gas is maintained with priority given to the improvement of the hydrogen recovery rate even if the processing amount is reduced. There is a technical problem that the processing cannot be performed effectively with a small amount of purge gas released to the outside. In addition, since this conventional method is intended for continuous processing, it is necessary to arrange two or more vessels in parallel as a hydrogen recovery device, and similarly as a device for purifying hydrogen. Two or more containers are arranged in parallel. For this reason, the device becomes very large.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of such a conventional technical problem.
The invention uses a plurality of hydrogen recovery containers CH1 and CH2 that are connected in series to the hydrogen utilization device 1 and that each contain a hydrogen storage alloy that stores hydrogen as a hydride. To one of the hydrogen recovery containers CH
After that, the hydrogen gas stored in one of the hydrogen recovery containers CH1 is released, and the hydrogen gas containing the impure gas is initially discharged into the other hydrogen recovery container CH2 when the hydrogen gas is released from the hydrogen recovery container CH1. The hydrogen gas released from one of the hydrogen recovery containers CH1 is returned to the hydrogen utilization device 1, and the storage and release of the hydrogen gas in the one hydrogen recovery container CH1 are repeated a plurality of times. The hydrogen gas occluded in the hydrogen recovery container CH2 is released, and the hydrogen gas containing the impurity gas is released to the outside at the initial stage of releasing the hydrogen gas from the other hydrogen recovery container CH2. A hydrogen gas released from the gas to the hydrogen utilization device 1. According to a second aspect of the present invention, there is provided a hydrogen utilization apparatus 1 and a plurality of hydrogen utilization apparatuses 1 connected in parallel, each of which stores hydrogen as a hydride and includes cooling devices 8a and 8b and heating devices 7a and 7b. A first valve 11 and a second valve 13 which are provided on each hydrogen inflow side of the hydrogen recovery vessels CH1 and CH2 and the hydrogen recovery vessels CH1 and CH2 in a parallel state and have an opening / closing function, and are provided on each hydrogen outflow side, Third valve 34 having function
And the fourth valve 35 and the hydrogen recovery containers CH1, CH
2 connected in series, and a series valve 36 having an opening / closing function.
Recycling pipes 37, 42, 50 attached with 46, 51
And discharge purge gas lines 39 and 28 connected to the hydrogen outflow sides of the hydrogen recovery containers CH1 and CH2 and having purge valves 38 and 29, respectively .
These hydrogen gases were stored in one of the hydrogen recovery containers CH1.
Later, the hydrogen gas occluded in one hydrogen recovery container CH1
And release hydrogen gas from the hydrogen recovery container CH1.
Recycle hydrogen gas including impure gas at the beginning of
The other hydrogen recovery container C through pipes (37, 42, 50)
H2 to occlude and then store the other hydrogen
The hydrogen gas stored in the chamber CH2 is released, and the other
In the early stage of releasing hydrogen gas from the hydrogen recovery container CH2,
Purge gas line 39 for discharging hydrogen gas including pure gas,
28 to the outside, and then the other hydrogen recovery container
Reflux hydrogen gas released from CH2 to hydrogen utilization device 1
Is hydrogen purity improving apparatus according to claim Rukoto is.

[0007]

According to the first aspect of the present invention, a predetermined amount of hydrogen gas in the hydrogen utilization device 1 is introduced into one of the hydrogen recovery containers CH1 and stored in the hydrogen storage alloy. One hydrogen recovery container C
When enough hydrogen has been occluded in H1, the supply of hydrogen gas to one hydrogen recovery container CH1 is stopped. Next, hydrogen is released from one hydrogen recovery container CH1. At the initial stage of the release, hydrogen gas containing some impurity gas released from one hydrogen recovery container CH1 is discharged to the other hydrogen recovery container CH2.
And stored in the hydrogen storage alloy of the other hydrogen recovery container CH2.

When a predetermined amount of the hydrogen gas is introduced into the other hydrogen recovery container CH2, one of the hydrogen recovery containers CH1
The remaining high-purity hydrogen gas in the inside is refluxed into the hydrogen utilization device 1. When the hydrogen gas in one hydrogen recovery container CH1 is sufficiently released, the occlusion and release of hydrogen in one hydrogen recovery container CH1 and the occlusion of hydrogen in the other hydrogen recovery container CH2 are performed in the same manner. Do.

If the hydrogen has been occluded a predetermined number of times (for example, four times) in the other hydrogen recovery container CH2, the next (fifth) hydrogen occlusion is performed in one hydrogen recovery container CH1. Then, the hydrogen stored in the hydrogen storage alloy in the other hydrogen recovery container CH2 is released. At that time, early in the release,
A hydrogen gas containing a relatively large amount of an impure gas is released to the outside, and then a relatively high-purity hydrogen gas in the other hydrogen recovery container CH2 is returned to the hydrogen utilization device 1. By repeating the above procedure, the purity of hydrogen in the hydrogen utilization device 1 is maintained. Thus, both hydrogen recovery containers CH1, C
By using the hydrogen purity improving apparatus in a batch type with H2 in series, the throughput of hydrogen is smaller than in the parallel state, but the purge gas released to the outside is small, and the hydrogen recovery rate is improved. Therefore, the amount of replenishment hydrogen is suppressed to a small amount.

According to the invention of claim 2, the cooling devices 8a,
8b and each hydrogen recovery container C provided with heating devices 7a and 7b
The first and second valves 11 and 13 on the hydrogen inflow side and the third and third valves on the hydrogen outflow side are provided in H1 and CH2 and have an opening / closing function.
Fourth valves 34, 35, hydrogen recovery containers CH1, CH2 are connected in series, and series valves 36, 4 having an opening / closing function
Recycling pipes 37, 42, 50 attached to 6,51
In addition, by using purge gas lines 39, 28 at the time of discharge connected to the hydrogen outflow side of each of the hydrogen recovery containers CH1, CH2 and having purge valves 38, 29, the hydrogen recovery containers CH1, CH2 are connected in series in the same manner as in the first embodiment. Can be obtained.

That is, only the first valve 11 is opened to introduce a predetermined amount of hydrogen gas in the hydrogen utilization device 1 into one of the hydrogen recovery containers CH1, and occluded in the hydrogen storage alloy cooled by the cooling device 8a. If enough hydrogen is stored in one hydrogen recovery container CH1, one hydrogen recovery container C
Since a rapid pressure increase occurs in H1, this is detected by, for example, a pressure gauge, and based on the detection signal, the first valve 11 is closed and one of the hydrogen recovery containers CH1 is closed.
From this state, the series valves 36, 46, 51
Is instantaneously opened, and a hydrogen gas containing a small amount of impurity gas released from one hydrogen recovery container CH1 in a heated state by the heating device 7a is introduced into the other hydrogen recovery container CH2 cooled by the cooling device 8b. The hydrogen is stored in the hydrogen storage alloy of the other hydrogen recovery container CH2.

When a predetermined amount of the hydrogen gas is introduced into the other hydrogen recovery container CH2, the series valves 36, 46, 5
1 and at the same time, the third valve 34 is opened to recirculate the remaining high-purity hydrogen gas in one hydrogen recovery container CH1 into the hydrogen utilization device 1. When the hydrogen gas in one hydrogen recovery container CH1 is sufficiently released, the valves 11, 34 and the series valves 36, 46, 51 are opened and closed, and the hydrogen in the one hydrogen recovery container CH1 is opened and closed in the same procedure. The storage and release of hydrogen and the storage of hydrogen in the other hydrogen recovery container CH2 are performed.

If the hydrogen has been occluded a predetermined number of times (for example, four times) in the other hydrogen recovery container CH2, the next (fifth) hydrogen occlusion is performed in one hydrogen recovery container CH1. Then, the hydrogen stored in the hydrogen storage alloy in the other hydrogen recovery container CH2 is released. At this time, the purge valve 38 is instantaneously opened at the beginning of the discharge, and the other hydrogen recovery container CH2 is heated by the heating device 7b to discharge the purge gas containing a relatively large amount of impurity gas from the purge gas line 39 to the outside. Thereafter, the purge valve 38 is closed and the fourth valve 35 is opened to open the other hydrogen recovery container C
A relatively high-purity hydrogen gas in H2 is refluxed into the hydrogen utilization device 1. By repeating the above procedure, the purity of hydrogen in the hydrogen utilization device 1 is maintained. As described above, by using the hydrogen purity improving device with the two hydrogen recovery containers CH1 and CH2 in series, the amount of hydrogen to be processed is smaller than that in the parallel state, but the amount of purge gas released to the outside is small, Recovery rate is improved. Therefore, the amount of replenishment hydrogen is suppressed to a small amount.

Further, the hydrogen recovery containers CH1, C
The effect of connecting H2 in parallel can be obtained. That is, when the hydrogen purity is improved, the first and second valves 11, 13
And the third and fourth valves 34, 35 and the series valves 36, 46, 51 are closed to close both hydrogen recovery containers CH1,
CH2 is placed in a parallel state. Further, both hydrogen recovery containers CH1 and CH2 are cooled by cooling devices 8a and 8b, and relatively low-purity hydrogen gas in hydrogen utilization device 1 is introduced into both hydrogen recovery containers CH1 and CH2. In this way, the hydrogen storage alloy in each of the hydrogen recovery containers CH1 and CH2 stores hydrogen sufficiently while the hydrogen gas in the hydrogen utilization device 1 flows toward the hydrogen recovery containers CH1 and CH2.

[0015] The end of the hydrogen storage is generally determined by a temporary increase in the pressure in the hydrogen recovery containers CH1 and CH2 due to the filling of the hydrogen gas in the hydrogen recovery containers CH1 and CH2. The pressure rise is detected, for example, by the pressure gauges of both hydrogen recovery containers CH1, CH2, and the first and second valves 11, 13 are closed based on the detection signals.

Next, when the hydrogen storage alloy in both the hydrogen recovery containers CH1 and CH2 is heated by the heating devices 7a and 7b to release hydrogen, the purge valves 38 and 29 must be instantaneously turned on at the beginning of the release. After opening, the impurity gases remaining in the hydrogen recovery containers CH1 and CH2 without being occluded by the hydrogen storage alloy are released from the purge gas lines 39 and 28, the purge valves 38 and 29 are closed, and the third and fourth valves are closed. 34 and 35 are opened, and the released hydrogen gas is returned to the hydrogen utilization device 1. Hydrogen gas corresponding to the impurity gas released from the purge gas lines 39 and 28 is appropriately replenished from the hydrogen supply device. Since the two hydrogen recovery containers CH1 and CH2 are batch-processed in parallel, the replenishment hydrogen amount increases in accordance with the processing amount, and conversely, the recovery rate is low. In this way,
The hydrogen purity can be improved, and the predetermined hydrogen purity can be substantially maintained by operating at predetermined time intervals and appropriately stopping the operation.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 4 show a hydrogen purity improving device according to a first embodiment of the present invention. In the figure, reference numeral 1 denotes a hydrogen utilization device, specifically a hydrogen-cooled generator that discharges used hydrogen gas at various concentrations. CH1 is a first hydrogen recovery container that contains a hydrogen storage alloy (metal hydride) that stores hydrogen as a hydride, and that heats the entire hydrogen storage alloy and a cooling device 8 that cools the hydrogen storage alloy.
a, and a pressure gauge 21 for detecting an internal pressure.
a. CH2 is a second hydrogen recovery container, which contains a hydrogen storage alloy (metal hydride), includes a heating device 7b for heating the entire hydrogen storage alloy and a cooling device 8b for cooling, and a pressure gauge for detecting the internal pressure. 21b.

Each of the cooling devices 8a and 8b has a function of cooling the hydrogen storage alloy so as to absorb hydrogen, and is, for example, a cold water supply device for supplying cold water. Each heating device 7a, 7
“b” has a function of heating the hydrogen storage alloy so as to release hydrogen, and is, for example, a steam supply device that supplies steam, an electric heater, or the like. The heating devices 7a and 7b and the cooling devices 8a and 8b are controlled based on detection signals from the temperature sensors 22a and 22b. Hydrogen storage alloys
It reacts with hydrogen gas and reversibly absorbs or releases hydrogen gas. This reaction is based on the hydrogen equilibrium pressure-
It is performed based on temperature characteristics (PT characteristics). From the temperature condition at the hydrogen equilibrium pressure, hydrogen gas is absorbed when cooled to a low temperature, and hydrogen gas is released when heated to a high temperature. The ordinary heating devices 7a and 7b in each of the hydrogen recovery containers CH1 and CH2 heat the hydrogen storage alloy to about 80 to 98 ° C. to release hydrogen gas. However,
Steam can be supplied and heated to about 110 to 170 ° C. to release hydrogen gas.

The absorption pipe 10 connected to the hydrogen outlet of the hydrogen utilization device 1 is branched into a pipe 12 having a first valve 11 having an opening / closing function and a pressure control function, and a pipe 14 having a second valve 13. One pipe 12 is connected to the hydrogen inflow section of the first hydrogen recovery vessel CH1, and the other pipe 14 is connected to the hydrogen inflow section of the second hydrogen recovery vessel CH2. Further, it is connected to the hydrogen outlet of the first hydrogen recovery container CH1 and is connected to the first branch product gas line 31 having the third valve 34 having an opening / closing function, and to the hydrogen outlet of the second hydrogen recovery container CH2. The second branched product gas line 32 including the fourth valve 35 having a function merges with the product gas line 33 and is connected to the hydrogen inlet of the hydrogen utilization device 1.

Further, the hydrogen outflow portion of the first hydrogen recovery container CH1 and the hydrogen inflow portion of the second hydrogen recovery container CH2 are connected by a recycling pipe 37 having a series valve 36 having an opening / closing function. . Further, a purge gas line 39 including a first purge valve 38 having an opening / closing function and a pressure control function as a purge valve and a flow meter 40 is connected to a hydrogen outlet of the second hydrogen recovery container CH2.
Hydrogen outlet of purge tank CH1 and purge gas line 3
9 is the upstream side of the flow meter 40 with the branch purge gas line 28 having a second purge valve 29 having an opening / closing function.
Are connected by However, although the first to fourth valves 11 to 35 and the first purge valve 38 are shown as pressure control valves in FIG. 1, when the pressure in the hydrogen utilization device 1 is relatively stable (normal power generation). Machine)
It may have only the opening and closing function.

Thus, the series valve 36 is closed, and the first valve 11 and the second valve 13 are opened.
By opening the third valve 34 and the fourth valve 35,
The first hydrogen recovery container CH1 and the second hydrogen recovery container CH2 can be connected to the hydrogen utilization device 1 in parallel. Further, by opening the series valve 36, the first hydrogen recovery container CH1 and the second hydrogen recovery container CH2 can be connected in series. For example, the second valve 13 and the third valve 34 are further closed, and the first valve 11 and the By opening the four valves 35 or the first purge valve 38, the first hydrogen recovery container CH1 and the second hydrogen recovery container CH2 are connected to the hydrogen utilization device 1 in series. Reference numeral 41 denotes a hydrogen supply device connected to the product gas line 33 and supplying pure hydrogen, for example, a hydrogen cylinder.

Next, the operation of the hydrogen purity improving device will be described. First, a case where the hydrogen purity in the hydrogen utilization device 1 is gradually improved will be described. In this case, it is necessary to treat a relatively large amount of hydrogen gas, and the hydrogen recovery containers CH1 and CH2 are placed in a parallel state, and a batch process is performed. When the hydrogen purity is improved, the first valve 11 and the second valve 13 are opened, and the third valve 34 and the fourth valve 35 are opened.
And the series valve 36 and the first and second purge valves 3
8, 29 are closed, and both hydrogen recovery containers CH1, CH2 are placed in a parallel state. Further, both hydrogen recovery containers CH1 and CH2 are cooled by the cooling devices 8a and 8b, and the hydrogen utilization device 1 is cooled.
The relatively low-purity hydrogen gas in the two hydrogen recovery containers CH1,
Introduce to CH2. In this way, the hydrogen storage alloy in each of the hydrogen recovery containers CH1 and CH2 stores hydrogen sufficiently while the hydrogen gas in the hydrogen utilization device 1 flows toward the hydrogen recovery containers CH1 and CH2.

At the end of the hydrogen storage, the pressure in the hydrogen recovery vessels CH1 and CH2 generally rises temporarily due to the filling of the hydrogen gas in the hydrogen recovery vessels CH1 and CH2. Both hydrogen recovery containers CH1, CH
The first and second pressure gauges 21a and 21b detect the pressure and close the first valve 11 and the second valve 13 based on the detection signal.

Next, when the hydrogen storage alloy in both hydrogen recovery containers CH1 and CH2 is heated by the heating devices 7a and 7b to release hydrogen, the first purge valve 38 and the second purge valve are used at the beginning of the release. 29 is opened instantaneously and both hydrogen recovery containers CH1 and CH2 are not stored in the hydrogen storage alloy.
Purging gas lines 39 and 28
, The first purge valve 38 and the second purge valve 29 are closed, the third valve 34 and the fourth valve 35 are opened, and the first branch product gas line 31 and the second
The released hydrogen gas is returned to the hydrogen utilization device 1 through the branch product gas line 32 and the product gas line 33. The hydrogen gas corresponding to the impurity gas released from the purge gas lines 39 and 28 is appropriately replenished from the hydrogen supply device 41. Since the two hydrogen recovery containers CH1 and CH2 are batch-processed in parallel, the replenishment hydrogen amount increases in accordance with the processing amount. In the case of performing the process of substantially maintaining at 9.9%, the recovery rate is as low as 92%, and the replenishment hydrogen amount from the hydrogen supply device 41 is relatively large at 38 m ³ / day.

Thus, a pair of hydrogen recovery containers CH
By connecting the CH1 and CH2 in parallel, as shown by a curve (a) in FIG. 3, for example, when the hydrogen purity in the hydrogen utilization device 1 is relatively low, such as 99.5 to 99.7% or more. And can be improved to a predetermined hydrogen purity (about 99.88%), and the curves (b), (c), and (c) in FIG.
As shown in (d), for example, by operating every predetermined time when the hydrogen purity in the hydrogen utilization device 1 is about 99.88%, and appropriately stopping the operation as shown by the broken line in FIG. A predetermined hydrogen purity (about 99.88%) can be substantially maintained. Thus, a pair of hydrogen recovery containers CH
1 and CH2, both hydrogen recovery containers CH1 and CH2
By performing the batch processing with 2 in parallel, the processing amount can be increased and the purity of the hydrogen gas can be improved and maintained.

[0026]

[Table 1]

Next, a case in which hydrogen gas of relatively high purity is released from the hydrogen utilization device 1 to maintain the hydrogen purity in the hydrogen utilization device 1 will be described. In this case, the amount of treatment may be small, but it is important to improve the recovery rate. Therefore, a hydrogen purity improving device is used in which the two hydrogen recovery containers CH1 and CH2 are connected in series.

That is, the second valve 13, the third valve 34, the second purge valve 29, and the series valve 36 shown in black in FIG. 4 are closed, and the first valve 11 is opened.
A predetermined amount of hydrogen gas in the hydrogen utilization device 1 is introduced into the first hydrogen recovery container CH1 as shown by a in FIG. 2, and is stored in the hydrogen storage alloy cooled by the cooling device 8a. First
If enough hydrogen has been occluded in the hydrogen recovery container CH1,
Since a rapid pressure rise occurs in the first hydrogen recovery container CH1, this is detected by the pressure gauge 21a, and based on the detection signal, the first valve 11 is closed, and the fourth valve 35 and the first purge valve 38 are provided. Close. In this state,
The series valve 36 is momentarily opened, and the hydrogen gas containing a small amount of impurity gas released from the first hydrogen recovery container CH1 heated by the heating device 7a is cooled by the cooling device 8b to the second hydrogen recovery container CH2. It is introduced and stored in the hydrogen storage alloy in the second hydrogen recovery container CH2 as shown by b in FIG.

When a predetermined amount of the hydrogen gas has been introduced into the second hydrogen recovery container CH2, the series valve 36 is closed, and at the same time, the third valve 34 is opened to open the remaining high-purity hydrogen in the first hydrogen recovery container CH1. The gas is returned to the hydrogen utilization device 1 through the first product gas line 31 and the product gas line 33. When the hydrogen gas in the first hydrogen recovery container CH1 is sufficiently released, the third valve 34 is closed, the first valve 11 is opened, and the first hydrogen recovery container CH1 is opened in the same procedure.
Storage and release of hydrogen in 1 and second hydrogen recovery vessel CH
The hydrogen in 2 is occluded.

After the hydrogen has been absorbed into the second hydrogen recovery container CH2 a predetermined number of times (four times as shown in FIG. 2 in this example), the next (fifth) hydrogen is stored in the first hydrogen recovery container CH1. During the storage of hydrogen, the hydrogen stored in the hydrogen storage alloy in the second hydrogen recovery container CH2 is released. At this time, first, the first purge valve 38 is instantaneously opened with the fourth valve 35 kept closed, and the inside of the second hydrogen recovery container CH2 is heated by the heating device 7b to contain a relatively large amount of impurity gas. The purge gas is released from the purge gas line 39 to the outside. After that, the first purge valve 38 is closed and the fourth valve 35 is opened to open the second hydrogen recovery container CH2.
The high-purity hydrogen gas inside is recycled into the hydrogen utilization device 1 through the second branch product gas line 32 and the product gas line 33. By repeating the above procedure, the purity of hydrogen in the hydrogen utilization device 1 is maintained substantially constant as shown by the curve (e) in FIG.

Thus, the two hydrogen recovery containers CH1, CH
By using the hydrogen purity improving device in the state of 2 in series, the throughput of hydrogen is smaller than in the parallel state, but the amount of purge gas released to the outside by opening the first purge valve 38 is small, and the hydrogen recovery rate is reduced. improves. However, as shown in Table 1 above, when performing a process of substantially maintaining the hydrogen purity at 99.9% in the hydrogen utilization apparatus 1 of a normal size, the recovery rate is relatively high at 99.2%. , So
The amount of hydrogen supplied from the hydrogen supply device 41 is as small as 5 m ³ / day. When the hydrogen gas in the hydrogen utilization device 1 has a low concentration, it is possible to improve the purity of hydrogen by operating in series.

Further, it is also possible to use both hydrogen recovery vessels CH1 and CH2 in series and use the hydrogen purity improving device as a flow type. This case is suitable when the low-purity hydrogen gas is released from the hydrogen utilization device 1. First, the set pressure of the first valve 11 is set to a pressure which does not prevent the flow of the low-purity hydrogen gas into the two hydrogen recovery containers CH1 and CH2 due to the fluctuation of the gas pressure in the hydrogen utilization device 1. The pressure of 38 is applied to both hydrogen recovery containers CH1 and CH2.
, That is, a set pressure slightly lower than the pressure at which hydrogen gas is not supplied in balance with the set pressure of the first valve 11. Then, the series valve 36 is opened, and the second valve 13,
The third valve 34, the fourth valve 35, and the second purge valve 29 are closed, respectively, and both cooling devices 8a, 8
b, the insides of the two hydrogen recovery containers CH1 and CH2 are cooled, and the low-purity hydrogen gas in the hydrogen utilization device 1 is absorbed by the absorption pipe 1.
0 and the pipe 12 are introduced into the first hydrogen recovery vessel CH1, and the recycle pipe 37 is introduced into the second hydrogen recovery vessel CH2. Impurity gas accumulates in both hydrogen recovery containers CH1 and CH2 as the hydrogen storage alloy stores hydrogen, and when the pressure in both hydrogen recovery containers CH1 and CH2 exceeds the set pressure of first purge valve 38, the impurity gas is released. Since the significantly increased low-purity hydrogen gas is discharged to the outside from the purge gas line 39, hydrogen storage by the hydrogen storage alloy is continued.

When the hydrogen storage alloy stores hydrogen sufficiently,
Due to the outflow of hydrogen gas, the flow rate of the purge gas line 39 is rapidly increased by the flow meter 40 or the pressure gauges 21a and 21b are increased.
This can be detected as a pressure increase caused by the first valve 11 and the first purge valve 3 based on the detection signal.
8 are closed together.

When hydrogen is released from the hydrogen storage alloy in both the hydrogen recovery containers CH1 and CH2, the first valve 11 and the first purge valve 38 are both kept closed and the insides of both the hydrogen recovery containers CH1 and CH2 are heated. To the first purge valve 38 and the second purge valve 2 as necessary.
9 is opened instantaneously to purge impurity gases with purge gas lines 39, 28
, The third valve 34 and the fourth valve 35 are both opened, and the high-purity hydrogen gas is joined from the first branch product gas line 31 and the second branch product gas line 32 to the product gas line 33. Reflux to the hydrogen utilization device 1.
If sufficient hydrogen is released from the hydrogen storage alloy in both hydrogen recovery containers CH1 and CH2, both hydrogen recovery containers CH1 and C2
Since the pressure in H2 decreases, the pressure is
1b, the third valve 34 and the fourth valve 3
Close 5. In the case where hydrogen is released from the hydrogen storage alloy in the hydrogen recovery containers CH1 and CH2, the second branch product gas is kept in series through the recycle pipe 37 without connecting the hydrogen recovery containers CH1 and CH2 in parallel. It is also possible to recirculate to the hydrogen utilization device 1 only from the line 32. Thus, a pair of hydrogen recovery containers CH1, CH
2, only the two hydrogen recovery containers CH1 and CH2 are connected in series, and the hydrogen purity improving device is of a flow type to improve the hydrogen purity.

When the hydrogen gas in the hydrogen utilization device 1 is low-purity hydrogen gas and its purity fluctuates, the more the impurity gas is, the earlier the two hydrogen recovery containers CH1 and CH1 are.
Since the pressure in CH2 reaches the saturation pressure and the hydrogen storage capacity of the hydrogen storage alloy is impaired, a valve operation to improve this point is performed. That is, at the time of hydrogen storage, the pressure of the first valve 11 is set, the insides of both the hydrogen recovery containers CH1, CH2 are cooled, and the lower the concentration of hydrogen gas in the hydrogen utilization device 1, the lower the set pressure of the first purge valve 38. To both hydrogen recovery containers C
The pressure is set lower than the saturation pressure in H1 and CH2, the impure gas flows out of the purge gas line 39 at an early stage, and the hydrogen storage capacity of the hydrogen storage alloy in both the hydrogen recovery containers CH1 and CH2 is maintained for a long time to sufficiently supply hydrogen. Absorb.

As a demonstration test, the hydrogen purity improving device was operated, and both the hydrogen recovery vessels CH1 and CH2 were continuously operated in parallel, and the operation time was 97.8% to 99.9 in 104 hours of operation.
% Improved hydrogen purity. In addition, it was proved that the device was continuously operated in a series system and could be maintained at a purity of 99.88% at a recovery of 99%. In the conventional method, the recovery rate is at most 92%.

FIG. 5 shows a hydrogen purity improving apparatus according to a second embodiment of the present invention, and the same reference numerals are given to substantially the same parts as in the first embodiment, and the description thereof will be omitted. In the second embodiment, the series valve 36 and the recycle pipe 37 in the first embodiment are omitted, and a first series valve 46 is provided from the pipe 12 between the first valve 11 and the first hydrogen recovery container CH1. The first recycle pipe 42 is branched, and the second recycle pipe 43 having the second series valve 47 is branched from the pipe 14 between the second valve 13 and the second hydrogen recovery container CH2. The second recycle pipe 43 is connected to the purge gas line 39 by a third recycle pipe 44 having an eighth valve 48. Specifically, the first of the purge gas lines 39
A fifth valve 45 is provided downstream of the purge valve 38, and a third recycle pipe 44 is connected between the first purge valve 38 and the fifth valve 45, so that the branch purge gas line 28, the third recycle pipe 44, and the second The recycling pipe 43 and the first recycling pipe 42 constitute a recycling pipe capable of connecting the first hydrogen recovery container CH1 and the second hydrogen recovery container CH2 in series. Normally, the first series valve 46 is closed and the seventh valve 47 is open.

According to the hydrogen purity improving device according to the second embodiment, the first hydrogen recovery container CH1 and the second hydrogen recovery container CH2
Are connected in parallel with the first embodiment. However, the fifth valve 45 is opened and closed in accordance with the opening and closing of the first purge valve 38. When the hydrogen purifying apparatus is used with both hydrogen recovery vessels CH1 and CH2 connected in series, the branch purge gas line 28 having the second purge valve 29, the third recycle pipe 44 having the eighth valve 48, and the seventh valve The second recycle pipe 43 having 47 serves as the series valve 36 and the recycle pipe 37 of the first embodiment. That is, the first
The series valve 46 is closed, and the second purge valve 29, the eighth valve 48, and the second series valve 47 are all opened. Thereby, the hydrogen gas in the hydrogen utilization device 1 is transferred to the second hydrogen recovery container C.
H2, and conversely, the second hydrogen recovery vessel CH2
Gas containing a small amount of impurity gas discharged from the first hydrogen recovery container CH1 can be introduced.

FIG. 6 shows a hydrogen purity improving apparatus according to a third embodiment of the present invention. The same parts as those in the first embodiment are denoted by the same reference numerals, and their description is omitted. In the third embodiment, the series valve 36 and the recycle pipe 37 are omitted compared to the first embodiment, and the first valve 11 and the first
The pipe 12 between the hydrogen recovery container CH1 and the second valve 1
The pipe 14 between the third hydrogen recovery container CH2 and the second hydrogen recovery vessel CH2 is connected by a recycle pipe 50 having a series valve 51. The recycle pipe 50 having the series valve 51 functions as the series valve 36 and the recycle pipe 37 of the first embodiment.

In contrast to the first embodiment, the first valve 11 is connected to the second valve 13, the third valve 34 is connected to the fourth valve 35, and the second purge valve 29 is connected to the first purge valve 38.
First, the first hydrogen recovery container CH1 is replaced with the second hydrogen recovery container CH2.
The hydrogen gas containing a small amount of impurity gas released from the first hydrogen recovery container CH1 is shown by a solid line in FIG. It flows in the direction of the arrow and can be introduced into the second hydrogen recovery container CH2. Of course, it flows in the direction of the arrow shown by the broken line in FIG.
Hydrogen gas containing some impurity gas discharged from the first hydrogen recovery container CH1 can also be introduced. FIG.
In the second embodiment shown in FIG.
The same function as the recycling pipe 50 having the series valve 51 can also be obtained by the first recycling pipe 42 having the recycling pipe 43 and the first series valve 46.

Incidentally, in the first to third embodiments, each of the valves 11, 13, 29, 34, 35, 36, 38, 4
The opening / closing operation time of 5, 46, 47, 51 is set by a timer, and each valve 11, 13, 29, 34, 3
By measuring the number of opening / closing operations of 5, 36, 38, 45, 46, 47, 51 using a counter, automatic operation can be performed while controlling the opening / closing operation time and the number of opening / closing operations.

[0042]

As will be understood from the above description,
According to the method and apparatus for improving hydrogen purity according to the present invention,
The following effects can be obtained. According to the first aspect of the present invention, a plurality of hydrogen recovery containers are connected in series, and hydrogen is sequentially recovered from the purge gas from the hydrogen recovery container and reused. A process for maintaining the hydrogen purity of high-purity hydrogen gas, which is performed with priority given to improvement, can be effectively performed. According to the invention of claim 2, a treatment for increasing the amount of treatment to improve the hydrogen purity of the low-purity hydrogen gas and a treatment for the high-purity hydrogen gas that prioritizes the improvement of the hydrogen recovery rate even when the treatment amount is reduced Treatment to maintain hydrogen purity,
Good compatibility can be achieved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a hydrogen purity improving device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an absorption / release operation of a pair of hydrogen recovery containers.

[Fig. 3] Operation / stop time of the hydrogen purity improvement device-
FIG. 3 is a diagram showing hydrogen purity characteristics in a hydrogen utilization device.

FIG. 4 is an explanatory view of the operation.

FIG. 5 is a schematic view showing a hydrogen purity improving device according to a second embodiment of the present invention.

FIG. 6 is a schematic view showing a hydrogen purity improving device according to a third embodiment of the present invention.

[Explanation of symbols]

1: hydrogen utilization device, 7a, 7b: heating device, 8a, 8
b: cooling device, 11: first valve, 13: second valve
28: branch purge gas line (purge gas line at discharge), 29: second purge valve, 34: third valve, 3
5: 4th valve, 36, 51: In-line valve, 37, 5
0: recycle pipe, 38: first purge valve (purge valve), 39: purge gas line at the time of release, 42: first
Recycle pipe (recycle pipe), 43: second recycle pipe (recycle pipe), 44: third recycle pipe (recycle pipe), 46: first series valve (series valve), CH1: first hydrogen recovery container, CH2: Second hydrogen recovery container.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tomoki Kamiki Kansai Electric Power Co., Inc. Himeji No. 2 Power Station, Tsumaka Tokiwa-cho, Shima-ku, Himeji City, Hyogo Prefecture Inside Japan Steel Works (72) Inventor Fumio Ito 4 Chazu-cho, Muroran City, Hokkaido Inside Japan Steel Works Co., Ltd. Kaihei 6-48702 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C01B 3/00 C01B 3/56

Claims (2)

(57) [Claims] Claims: 1. An apparatus connected in series to a hydrogen utilization device (1),
After using a plurality of hydrogen recovery containers (CH1 and CH2) each containing a hydrogen storage alloy that stores hydrogen as a hydride, hydrogen gas from the hydrogen utilization device 1 is stored in one of the hydrogen recovery containers (CH1). The hydrogen gas occluded in one hydrogen recovery container (CH1) is released, and the hydrogen gas containing the impure gas is initially discharged from the hydrogen recovery container (CH1) to the other hydrogen recovery container (CH2).
To one of the hydrogen recovery containers (CH
The hydrogen gas released from 1) is refluxed to the hydrogen utilization device (1), and the storage and release of the hydrogen gas in one hydrogen recovery container (CH1) is repeated a plurality of times, and then the other hydrogen recovery container (CH2) The hydrogen gas occluded in the second hydrogen recovery container (CH2) is released, and the hydrogen gas containing the impure gas is released to the outside at the initial stage of releasing the hydrogen gas from the other hydrogen recovery container (CH2). A method for improving the purity of hydrogen, wherein the released hydrogen gas is refluxed to a hydrogen utilization device (1). 2. A hydrogen utilization device (1) and a hydrogen storage alloy which is connected in parallel to the hydrogen utilization device (1) and stores hydrogen as a hydride, respectively, and has a cooling device (8a, 8b) and a heating device. A plurality of hydrogen recovery containers (CH1, CH2) each including a device (7a, 7b); and a first valve (11) provided on each hydrogen inlet side of the hydrogen recovery containers (CH1, CH2) in a parallel state and having an opening / closing function. And a second valve (13), a third valve (34) and a fourth valve (35) provided on each hydrogen outflow side and having an open / close function, and the hydrogen recovery containers (CH1, CH2) connected in series. A series valve (36, 46, 51) having an opening / closing function is connected to an attached recycling pipe (37, 42, 50) and a hydrogen outlet side of each hydrogen recovery container (CH1, CH2), and a purge valve (38) , And a release time of the purge gas line (39,28) with a 29), one housing the hydrogen once the hydrogen gas from the hydrogen utilization device (1)
One of the hydrogen recovery containers after occlusion in the vessel (CH1)
(CH1) to release the hydrogen gas occluded.
In the early stage of releasing hydrogen gas from the recovery container (CH1),
Hydrogen gas containing pure gas is recycled through pipes (37, 42,
50) to the other hydrogen recovery container (CH2 )
Occlusion, and then the other hydrogen recovery container (CH2)
Release hydrogen gas stored in
Impurity gas at the beginning of releasing hydrogen gas from the container (CH2)
Purge gas line (39, 2)
8) Released to the outside, and then the other hydrogen recovery container
Hydrogen utilization device using hydrogen gas released from (CH2)
(1) is refluxed in hydrogen purity improving apparatus according to claim Rukoto.