JPS61174102A - Refining method of hydrogen - Google Patents

Abstract

PURPOSE:To refine efficiently hydrogen with a device made into simple construction by cooling a hydrogen occluding alloy by making use of a heat medium in the stage of occluding and utilizing the vapor of the heat medium in this stage for heating of the alloy in the stage of devolatizing. CONSTITUTION:Pipes 24 into which the hydrogen occluding alloys 3 are packed are fixed into vessels 1, 2. Raw material H2 is supplied into the vessel 1. The heat medium such as ethanol is circulated through a tank 12, a pump 13 and a heat medium pipe 5 in the stage of starting releasing in the vessel 2 with which the occluding is already finished, then the temp. rise of the alloy 3 in the vessel 1 is prevented. The vapor of the heat medium enters the vessel 2 through the heat medium pipe and is condensed by the outside wall of the pipe 24 to heat the alloy 3 so as to assist the release of H2. The devolatizing of the occluding material in the vessel 2 is finished when the H2 is filled in the occluding material in the vessel 1 and therefore the valve is changed over.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a hydrogen purification method using a hydrogen storage alloy.

(Prior art) Conventionally, by utilizing the selective reactivity with hydrogen that a hydrogen storage alloy has, impurity-containing hydrogen is brought into contact with the alloy to absorb hydrogen, and then hydrogen is released from the alloy. The idea is to obtain high-purity hydrogen. According to this method, when hydrogen is absorbed, the heat generated by the reaction must be cooled and removed by a refrigerant, and conversely, when hydrogen is desorbed, it must be heated by a heat source □. Therefore, a refrigerant and a heat source were required, respectively. This requires the cost of refrigerant and heat source.
This will increase the cost of hydrogen refining and become a major constraint in areas where refrigerants and heat sources are in short supply.

There is also the idea of self-sufficiency in heat capacity, which mutually utilizes the heat capacity for cooling during occlusion and heating during desorption.

This transfers heat through a heat storage container and uses the sensible heat of a liquid with a boiling point of 100° C. (normal pressure) or higher, such as water or ethylene glycol, as a heat medium. In this method,
This increases the cost of installing a heat storage container, and in transferring heat by sensible heat of the liquid, the heat exchange capacity per volume of circulating liquid is small and the possible heat transfer coefficient is small. Therefore, there are disadvantages such as an increase in the required heat transfer area and a complicated storage container.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned drawbacks and provides a self-sufficient method for refining hydrogen by directly utilizing heat medium vapor.

(Means for Solving the Problems) The present invention provides a method for purifying hydrogen using a hydrogen storage alloy.
Relating to a hydrogen purification method characterized by indirectly cooling the alloy during hydrogen storage using the latent heat of vaporization of a heating medium, and indirectly heating the alloy during hydrogen devolatilization using the vapor of the heating medium obtained at that time. .

(Function) The present invention uses the amount of heat generated during storage to compensate for the heat absorbed during devolatilization by appropriately selecting operating conditions and heat sources during occlusion and devolatilization. For example, the temperature -F of various hydrogen storage alloys shown in Figure 1
(Consider LaNi@ in terms of i pressure characteristics. This alloy has S
Maintain equilibrium with the hydrogen partial pressure of 3 atm. Therefore, if the temperature is maintained below this temperature and the partial pressure of hydrogen is above N55 atm, the metal will be occluded to the saturation state of the alloy. Therefore,
The temperature is maintained at 100°C and the hydrogen partial pressure is stored at 55 atm or higher. At this time, the temperature of the storage material increases, so it is necessary to cool the storage material with a refrigerant of 100° C. or lower through the heat transfer wall. Also, this alloy has a temperature of 30℃ (1000/
Maintain equilibrium with the hydrogen partial pressure of 1.7 atm at T■53). Therefore, while maintaining the temperature above this temperature,
If the hydrogen partial pressure is kept below m, hydrogen will be released from the alloy.

The storage material shall be maintained at 50°C and released under a rapid partial pressure of 1.7 atm or less. At this time, the storage material must be heated with a heat source of 50°C or higher and the temperature must be maintained.

According to this setting, if an appropriate heat source is used, the amount of heat removed during occlusion can be used as the amount of heat supplied during devolatilization. In addition, Mm in Figure 1 refers to missing metal.
Rare earth alloy, for example La30%-〇050%-P
There are compositions such as r5%-M15%.

FIG. 2 is a diagram for explaining one embodiment of the method of the present invention, and FIG. 3 is a conceptual diagram of the container 1 or 2 in FIG. 2.

In the hydrogen purification apparatus having the structure shown in FIGS. 2 and 3, a container 1 and a pipe 24 filled with an occlusion material 3, here I, aNilB, are fixed by a tube plate 4 like a heat exchanger.

Raw material H! The purity of the raw material supply line 18 is about 90% (the remainder is impurities such as methane, ethane, N2, etc.), and the pressure is 57%.
The storage material 3 in the pipe 24 in the container 1 is supplied at about ATM level! The /c grains are occluded and the remaining grains are returned to the raw material return line 19. It is also assumed that container 2 has the same specifications as container 1, and has already stored KHil. The switching pulp 7.9 is closed and the purge pulp 10 is opened to purge the raw material gas in the container 2, and then the purge pulp 10 is closed and the switching valve 22 is opened to start discharging the stored horse. High purity horse is extracted from refined Shimada Loline 20.

A suitable heat medium is circulated through the tank 12, pump 13, and heat medium pipe 5.

As the heat medium, methanol, ethanol, 1-propertool, n'-butanol, 1-butanol, acetone, methyl ethyl ketone, ethylene glycol, alkylbenzene, alkylnaphthalene, diphenyl, diphenyl ether, alkyldiphenyl, light oil, etc. can be used. Ethanol (boiling point 7&5° C. (atmospheric pressure), molecular weight 46) is used here as an example. The surface areas of the pipes 240 in the containers 1 and 2 are such that the temperature of the storage material 3 is 100%.
℃ or less (based on the boiling point of ethanol 7a5℃, with a slight margin of 100℃ or less), 50℃ or higher (based on the release of hydrogen at 30℃, 1,7 atm, 50℃ or higher with a slight margin) ) is designed to be. Therefore, the temperature of the storage material 3 in the container 1 gradually increases,
7a The temperature is about to rise even higher than 5℃ (storage limit of 111℃), but the ethanol liquid in the heat medium pipe 5 begins to boil, preventing the temperature rise of the storage material 3, and 1 the vapor is released into the heat medium pipe. Hydrogen gas enters the container 2 via the hydrogen storage alloy 5, condenses on the outer wall of the pipe 24, heats the storage material 3, and helps release hydrogen from the hydrogen storage alloy. When the storage material 3 of container 1 is filled with horses,
Since the storage material 3 of the container 2 has finished devolatilization, the valve is switched. The switching valves 6.8, 17, 15, 22 are changed from open to closed, and the switching pulps 7.9, 16, 14 are changed from closed to open.

Horse storage started in container 2, switching pulp 6.8 on container 1 side
At the same time as the purge valve 11 is closed, the purge valve 11 is opened to purge the remaining raw material gas in the vessel via the purge line 21, and at an appropriate time, the purge valve 11 is closed, the switching pulp 23 is opened, and the purified horse is transferred to the purified horse loline 20. Take it out. You can continue to refine horses by switching operations like this.

(Effects of the invention) Each container is operated alternately in a cycle of 15 minutes of suction and 1.15 minutes of de-I, 1 hourly.
6 X 22.4 X 60/30X 2-557.6
Mm'' purified horse is obtained (that is, the effective horse storage capacity is about 1.2 wt%, and the filling amount of the storage material 3 is 1 for each container.
．． If it is 0 tons, fi1000XQ per cycle,
012-12kg-6kll-molO island purified amount).

When the refrigerant and heat source are supplied separately as in the conventional method, 1000XQ, 012-12 kg-
6kg-mol, reaction heat 7.2X10"X604
! h 2
(as an increase of 0℃), the amount of heat during devolatilization is 44,200 kcal
It takes 4520x cooling water for 1 hour.
4=17,280kg, heat amount 44200X4=17 Z
8 G G kcal. Therefore, the effect of the method of the present invention is significant.

Furthermore, in conventional self-contained systems where only the sensible heat of the heating medium is used, for example, when water is used as the heating medium, even if the temperature difference between the entrance and exit is 20°C, 20 kcal of heat can be transferred per 1 kg of water. Not too much. On the other hand, in the method of the present invention,
It is selected so that the latent heat of the heat medium can be utilized.

For example, in the above example, ethanol is used, and in this case, the latent heat of ethanol is 9.5 x 10” kaa
Since it is l/mol, is 1 yut of ethanol? ,
3 X I Q"/46-2012 kaal (approximately 10 times more than the conventional self-contained type described above). This affects the cost and power of the pump 13.

Also, during heat exchange with the storage material 3, the storage material (metal powder) -
Due to the configuration of the vibrator wall and heat medium, the heat transfer rate of the method of the present invention, which involves phase changes of boiling and condensation, is significantly better than the well-known convection heat transfer method with no phase change on the heat medium side. It is clear that the performance is good. This heat transfer performance is determined by the structural design of the storage device.
This is an important factor in manufacturing, especially when metals with high storage capacity are used, and are the main factor in determining the structure of the storage device. This good heat transfer performance is a major advantage in producing a low-cost storage device with a simple structure.

(Others) When using the following as the storage material, it is preferable that the raw material gas pressure and the heat medium used be as follows.

Storage material Raw material gas pressure Heat medium

[Brief explanation of drawings]

Figure 1 is a temperature-equilibrium pressure diagram of the hydrogen storage alloy used in the present invention, Figure 2 is a diagram showing an embodiment of the method of the present invention, and Figure 3 is a partial configuration of Figure 2. FIG. Sub-agents 1) Meifuku agent Ryo Hagiwara -

Claims (1)

[Claims] In a hydrogen purification method using a hydrogen storage alloy, the alloy during hydrogen storage is indirectly cooled using the latent heat of vaporization of a heating medium,
A method for refining hydrogen, characterized in that the alloy during hydrogen devolatilization is indirectly heated by the vapor of the heat medium obtained at that time.