JPS5899102A - Activating method for alloy for occluding hydrogen - Google Patents

Abstract

PURPOSE:To reactivate an alloy for occluding hydrogen by simple operation when the performance of the alloy is deteriorated by repeating the occlusion and release of hydrogen, by treating the alloy under pressure of hydrogen other than stationary running conditions. CONSTITUTION:A heat exchange tube 5 through which a heat medium from a process P is passed is installed in a regenerator 1 packed with an alloy for occluding hydrogen such as an Ni-Mg alloy. The regenerator 1 is connected to a tank 2 foe storing hydrogen with piping 3a, 3b to form a heat controller for the process P in which a surplus of heat and demand for heat are repeated at certain time intervals. When the heat medium in the process P has an excess of heat, hydrogen in the alloy is released by heating with the heat and the medium is cooled. The released hydrogen is fed to the tank 2 with a compressor 4. When the heat medium requires heat, hydrogen is occluded in the alloy and the medium is heated. When the performance of the alloy is deteriorated by repeating said operations, by closing a valve V5 and opening a valve V6, the heat medium is bypassed, and by evacuating the regenerator 1 or feeding highly compressed hydrogen, the alloy is reactivated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for activating a water g* metal alloy. decrease)
The present invention relates to a method for activating hydrogen storage alloys with simple operations.

Water bulk storage alloys have the unique property of generating heat when storing hydrogen and releasing hydrogen, and development of applications for heat storage material sieves is underway by utilizing this property. The present inventor, Hiromu, also utilized the excellent heat storage performance of water bulk storage alloys to store heat during surplus heat in various process controls, and to release the stored heat during heat demand, thereby making effective use of thermal energy μ. We are conducting research to achieve this goal, and have already developed a method as shown in Figure @1. That is, Fig. 1 is a schematic diagram showing an example of heat control in a process in which heat surplus and heat demand are repeated at time intervals. and hydrogen pipes 8m and 8b connecting the two, and the hydrogen pipe 8b is provided with a pressure N bridge 4.

Heat exchange tubes 5 through which heat mediums from various processes P pass are arranged in the heat storage tank 1, and hydrogen is transferred between the heat storage tank 1 and the hydrogen-rich tank 2 by opening and closing the pulps Vl to 4. let me,
*Using heat generated during water accumulation absorption and heat absorption during hydrogen release of the water bulk storage alloy in the heat tank 1, heat storage during heat surplus IJ and heat release during heat demand are performed, that is, the heat medium in process P is When there is a heat surplus U (a condition requiring cooling), the hydrogen in the hydrogen storage alloy is released by the excess heat supplied by the heat exchange pipe, and the heat medium is cooled by the accompanying heat absorption, and the hydrogen is released. The water volume is passed through the pulp vl * V 3 to the compressor 4
After being pressurized, it is sent to the hydrogen storage tank 2 through pulp v4. On the other hand, when MK in process P is in a heat demand state (condition requiring heating), pulp V 3 e
Close V4 and open Pulp V2, water storage snow tank 2
From there, hydrogen is sent to the heat storage tank 1 and stored in the water bulk storage alloy.
The heat generated at this time heats the heat medium in the heat exchange tube 6. The above-mentioned absorbed water volume and released hydrogen amount are determined by using pulp ■1 so that the temperature of the heating medium is detected by the temperature indicator M14 moderator 7 installed in the heating medium return path and the detection effect or heating effect is adjusted according to the detected temperature. Adjust the opening. 9#-i hydrogen replenishment line is shown in the figure. With this method, heat is stored by heat absorption during hydrogen release and heated by heat generation during hydrogen storage, so the surplus heat during the afterburning process is almost completely retained. heat wine
It can be used for heating at various times, and enables load leveling of heat load fluctuations in various processes. Moreover, since this heat storage and heat release occur reversibly due to the movement of hydrogen, it must be carried out continuously for a long period of time as long as the hydrogen storage alloy does not lose its activity. As a result, it became clear that as the number of hydrogen storage and desorption increases, the activity of the above alloy gradually decreases, and in particular, the hydrogen storage activity significantly decreases (for example, as shown in Figure 2). Mg-28 as a hydrogen storage alloy
When using 1'l Ni, the elapsed time of the hydrogen absorption and release repetition process and to, 9 [ΔH/Mg, Q, 07
When generalized to atom/atom, 90 points (i.e. 0.
068 a t om/a * om)].

As time passes, the hydrogen storage rate decreases significantly.

In other words, to,9 immediately after filling is extremely short at about 50 seconds, but 1
After 00 hours have elapsed, tO, about 90 seconds.

After 200 hours, it gradually increases to about 170 seconds.

After 800 hours have elapsed, it takes about 290 seconds, about six times as long as the initial filling time. Therefore, in order to continue continuous operation for a long time, it is necessary to recover the delay in the hydrogen absorption rate by some method, and the specific measure for this is fi! of the control constant during hydrogen absorption and release. , for example, increase the gain of proportional WJJfv. The precept is not to control the pressure, but to apply the so-called 2-position (repeatedly wave-like rapid fluctuations in hydrogen pressure to the base metal filling system) to prevent the water #IA suction speed from decreasing. However, these methods are extremely difficult to operate, and there is also the risk of over V neatness of the heating medium crystallinity, hunting, etc., so it is difficult to find a practical method. ^.

The present inventors have focused on the above-mentioned circumstances and have conducted research with the aim of developing a method for reducing the hydrogen storage spJ through continuous use and activating the nine-hydrogen storage alloy in a simple manner. ′
The present invention was completed as a result of such research, and its configuration is such that in the process of repeatedly storing and releasing hydrogen using a water bulk storage alloy, when the water bulk storage activity of the alloy decreases, The gist lies in activating the hydrogen storage activity of the alloy by exposing the alloy to a hydrogen pressure that is lower than the equilibrium dissociation pressure during steady operation, or by setting the hydrogen pressure to Km that is lower than the equilibrium dissociation pressure. .・In the present invention, as shown in Fig. 2, water volume at a pressure higher than the equilibrium dissociation pressure during steady operation is applied to the water volume storage alloy whose hydrogen storage activity has decreased due to long-term continuous use (during hydrogen storage). , or by actively suctioning and removing hydrogen from the alloy-filled system to rapidly lower the hydrogen pressure (during hydrogen release), such stimulation can activate water bulk storage activity to the same level as fresh 4. .

For example, FIG. 8 shows the example of FIG.
After 20 hours, the activity of tO,9 decreased to 800e, and the filling thread of nine hydrogen storage alloy (Mg-28,8*Ni)
Applying hydrogen pressure of 22.5 kg/-, 87 Mg was
, Ft52, the hydrogen absorption rate (tg, g) after activation treatment for a certain period of time, and after repeated hydrogen absorption and release, when the activity decreases again, this time the hydrogen of the alloy filled system is This graph shows a series of hydrogen absorption rates measured when activation treatment is performed by actively suctioning and removing and lowering the hydrogen pressure.

As is clear from FIG. 8, the first activation treatment m (high-pressure hydrogen treatment
, sl is approximately 44 seconds, and the initial filling hydrogen is restored. In addition, after the second activation treatment (low-pressure hydrogen treatment) BK, the water and snow storage IjA 4 degrees tO,9 after the treatment was about 52 seconds, and the water volume storage activity reached the initial stage of filling.

In other words, if a hydrogen storage alloy whose activity has been reduced due to continuous operation is removed with hydrogen at normal pressure or low pressure during steady operation, the water bulk storage activity will be increased to the same level as a fresh hydrogen storage alloy. It can be recovered.

Therefore, 5j! I'm going to give it to you.

A high level of hydrogen storage rate can be sustained for a long time.

The thickness increase activated by such high-pressure or low-pressure hydrogen treatment has not necessarily been clarified.

You can think of it as follows.

■ Immediately after the start of operation, microcracks occur in the alloy sheet due to hydrogen absorption and release, increasing the surface area, resulting in a high level of hydrogen absorption rate.

As time -1JX elapses, the main black cracks are sintered by the heat generated during water occlusion, and the activity gradually decreases.

However, when hydrogen is absorbed or released more rapidly than in the steady state by the above activation treatment, microcracks occur again in the sintered material on the surface of the alloy 1, and Table 1IlildI expands to recover the hydrogen storage activity.

■Immediately after the start of operation, lattice defects are formed in the alloy due to hydrogen storage and release, and this is thought to have a positive effect on hydrogen storage activity, but as one hour passes, the strain eases and the number of active sites decreases. However, the hydrogen storage activity decreases. However, due to the above activation treatment, large strain lattice defects are created within the alloy again.

Water bulk storage activity is restored at high levels t.

In Figures 2 and 8, Ir1Mg-28 and acsNi are used as examples, but such activity reduction and activation effects over time are also observed in other hydrogen storage alloys (e.g. LaNi3゜TIF6N1).
．． T1Co, ZrMn, 2. LaCO5, V, Mg$1
In the case of , the trend is similar, although there are differences in degree.

In addition, when the above activation treatment is performed in the heat storage control process as shown in Fig. 1, when the heat surplus and heat demand of the heating medium that is used in the process PWc is zero, the pulp v5 is closed and the vapor valve V6 is opened. All you have to do is bypass the heating medium and then reduce the pressure inside the heat storage #1 or supply high-pressure ice/snow (the operation is extremely simple and there is no need to interrupt the actual operation. Pressurization or depressurization of the filled threads should be carried out at once within as short a time as possible in order to enhance the embroidery effect.

It is not necessary to carry out the process for 4 times after activation to reach a steady dissociation pressure, but it may be carried out in stages.

Outline of the present invention As described above, the hydrogen storage alloy whose hydrogen storage activity has decreased can be activated by an extremely simple operation.
By doing so, the properties of the alloy as a heat storage material, etc. can be maintained at a high level for a long period of time, and it will be possible to prevent browning. .

[Brief explanation of drawings]

#I1 Figure II'i A simplified perspective diagram showing a practical example of a hydrogen storage alloy to which the present invention is applied. Figure 2 is a graph showing changes in hydrogen storage rate over time of a hydrogen storage alloy. It is a graph showing activity recovery trends due to activation treatment. 1... Heat storage tank 2... Water storage bulk tank Rm,
gb...Water bulk piping 4...Pressure machine applicant! Toyobo Co., Ltd. Page 1 continued 0 Inventor: Osamu Tanaka 803-803 Miyamachi, Suzuka type Applicant: Toyobo Co., Ltd. 2-2-8 Dojimahama, Kita-ku, Osaka

Claims (1)

[Claims] (Note) In the process of repeatedly storing and desorbing hydrogen using a hydrogen storage alloy, when the hydrogen storage activity of the alloy decreases, the alloy is brought to a high hydrogen pressure (the equilibrium dissociation pressure during steady operation). A method for activating a water bulk storage alloy, characterized by exposing it to hydrogen pressure or exposing it to a hydrogen pressure lower than the above-mentioned normal internal pressure.