JPH0231003B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling the hydrogenation reactivity of a metal hydride in a hydrogen gas storage alloy powder storage container.

Conventionally, a control method as shown in FIG. 1 has been known as one method for controlling the reactivity of hydrogenation (including dehydrogenation, hereinafter the same) in an alloy powder storage container for storing hydrogen gas. That is, while measuring the hydrogen gas flow rate (ΔQ absorption/Δt) during hydrogen gas absorption flowing into the hydrogen storage alloy powder storage container 1 from the hydrogen gas tank 3 via the flow rate control valve 4, using the storage flow meter 5,
The hydrogen gas flow rate (Δrelease/Δt) when the hydrogen gas is discharged from the hydrogen gas conduit 7 via the two-way valve 8 to the hydrogen gas tank 3 is measured using the discharge flow meter 6, and based on these flow rate measurements. Then, the flow rate calculators 9 and 10 perform integral calculations to obtain the hydrogen storage amount and hydrogen release amount, and further, based on these calculated values, the hydrogenation reactivity calculator 11 calculates the hydrogenation reactivity, The flow control valve 4 is operated based on the calculated value. Therefore, in such a control method, the control circuit is complicated, the hydrogen gas flowmeter used is very expensive, and the storage flowmeter 5 and the discharge flowmeter 6 are required.
The disadvantage is that the cost of the control device becomes very high because each of them must be arranged independently, and two flow rate calculators must also be provided.

In addition, as a control method other than the above-mentioned control method, the equilibrium dissociation pressure is measured by focusing on the correlation between the equilibrium dissociation pressure and temperature and the degree of hydrogenation reaction, and the equilibrium dissociation pressure corresponding to the temperature of the system - hydrogenation reaction is calculated. There is a method of controlling using a degree diagram. However, even in this control method, it is difficult to perform the control reliably and smoothly due to the following drawbacks. That is, the hydrogenation reactivity cannot be uniquely determined from the equilibrium dissociation pressure.
It is necessary to prepare a large number of equilibrium dissociation pressure diagrams and hydrogenation reactivity diagrams for each temperature. The equilibrium dissociation pressure-hydrogenation reactivity diagram generally takes the form shown in Figure 2, but in the plateau region BC, the change in equilibrium dissociation pressure is very small with respect to changes in hydrogenation reactivity. As the sensitivity decreases, measurement errors increase, and in extreme cases, measurements become impossible.

The present invention eliminates all the drawbacks of these conventional methods,
This was done with the aim of providing a method for reliably and quickly controlling the hydrogenation reactivity of metal hydrides by employing a simple detection mechanism that utilizes the volumetric expansion phenomenon of alloy powder accompanying the hydrogenation reaction. Such a control method of the present invention is such that an alloy powder of the same type as the alloy powder is filled approximately in the center of a main container containing hydrogen gas storage alloy powder, and the main container is in communication with the inside of the main container. A pressure-resistant small container having a mouth and a strain gauge attached to the outer wall surface is arranged, and the stress applied to the strain gauge of the pressure-resistant small container is measured to detect the degree of hydrogenation reaction, and the detected reaction The gist lies in that the flow rate of hydrogen storage into the main body container is adjusted based on the temperature.

The configuration and effects of the present invention will be explained below based on the drawings of the embodiments, but the embodiments below are merely representative examples, and the present invention also includes implementations with appropriate changes as described above and below. . Components that are the same as those in FIG. 1 are designated by the same reference numerals. FIG. 3 is a schematic explanatory diagram of the hydrogenation reactivity detection device 21 used in the control method of the present invention. That is, the short cylindrical bottle-shaped pressure-resistant small container 22 illustrated in the figure is filled with hydrogen-absorbing alloy powder 23 up to the neck 22a, and a filter 24 is placed on the surface of the alloy powder in the neck 22a. place In order to hold down the filter 24, a cap 25 having a hydrogen gas communication port 25a in the center is attached to the neck part 22.
a, while a strain gauge 26 is fixed to the bottom surface 22b of the small container 22, and a conducting wire 27 is further connected to the strain gauge 26. In addition, the filter 24 is equipped with a cap 25 in advance.
It may be attached to the bottom surface of the cap 25, or in some cases, it may be provided on the top surface side of the cap 25. The shape of the small container 22 is not particularly limited, nor is the wall thickness particularly limited, but the fixed wall surface 22b of the strain gauge 26 may be made thinner to increase the strain sensitivity of the strain gauge 26. . Furthermore, it goes without saying that the strain gauge 26 may be fixed by bolts, welding, etc. in addition to adhesive.

When hydrogen gas is stored in the small container 22 of such a detection device 21, the alloy powder 23 undergoes a hydrogenation reaction and expands in volume, and as a result, internal stress is applied to the wall surface 22b. This stress is measured by the strain meter 26, and after repeating this occlusion several times until the relationship between the hydrogenation reaction and the stress has settled down to a stable state, a calibration curve as shown in FIG. 4 is determined. Although this calibration curve differs depending on the type of hydrogen storage alloy, based on this calibration curve, the hydrogenation reactivity can be uniquely determined by wall stress regardless of temperature.
Depending on the pressure resistance of the small container 22, the stress due to volumetric expansion during the hydrogenation reaction may be too large and the pressure resistance of the small container 22 may be too large.
In cases where it is desired to have a packing density that does not cause 2 to break, or to mix a highly compressible solid powder that is inert to hydrogen with the alloy powder and fill it in the small container 22. There is also.

Next, a method of controlling the hydrogenation reactivity of metal hydrides using such a detection device 21 will be explained. That is, as shown in FIG. 5 (schematic explanatory drawing), a main body container (hereinafter simply referred to as "main container") 1 containing alloy powder for storing hydrogen gas is filled with alloy powder 2, and at the same time, the hydrogen gas conduit 7 is A detection device 21, which is suitably filled with the same type of alloy powder at a position on the reaction side of the filter 7a, is buried in the approximate center of the alloy packed layer in the container 1, and the conductor 27 of the strain gauge 26 is sealed from the main container 1. The conducting wire 27 is taken out to the outside through the strain-stress converter 2.
9, and constitutes a control circuit in which the strain-stress converter 29, hydrogenation reactivity converter 30, hydrogen gas comparison controller 31, and flow control valve 4 are electrically connected. In this way, the hydrogenation reactivity of the metal hydride in the main container 1 becomes the same as that in the detection device 21 through the communication port 25a, so it is detected by the strain meter 26 as an internal stress in the small container 22, and the strain-stress The stress on the wall surface 22b is detected by the converter 29, and at the same time, the hydrogenation reactivity at that time is calculated by the hydrogenation reactivity converter 30. Therefore, a comparison calculation between the calculated value and a preset or required hydrogenation reactivity is performed in the hydrogen gas comparison controller 31, and the flow rate control valve 4 is opened and closed according to the deviation value. The flow rate of stored hydrogen gas is appropriately controlled. Thereby, the hydrogenation reactivity of the metal hydride can be controlled reliably and quickly.

Although the control method of the present invention is configured as described above,
In short, by using a detection mechanism configured to uniquely determine the hydrogenation reactivity by capturing internal stress, and by adopting a control circuit connected to a hydrogen gas flow rate control valve, the following can be achieved. Now we can enjoy the benefits.

Since the control circuit is simple and there is no need to use an expensive hydrogen gas flow meter, the cost of the control device is low.

Since the hydrogenation reactivity can be uniquely determined from the stress, there is no need to prepare a large number of equilibrium dissociation pressure diagrams and hydrogenation reactivity diagram data for each temperature as in the conventional method.

Since pressure is used as the measurement parameter, the measurement sensitivity is very good and the measurement error is extremely small, so the hydrogenation reactivity can be controlled reliably.

For the same reason as above, changes in reactivity are quickly detected. Moreover, the hydrogenation reactivity is instantaneously calculated within the control circuit, and the hydrogen gas storage flow rate to be corrected is indicated, so the hydrogenation reactivity can be controlled extremely quickly, making so-called dynamic control possible. becomes.
Since the small container is placed approximately at the center of the hydrogen storage alloy powder to be loaded, it is possible to detect a hydrogenation reactivity that approximates the average value of the total amount of the alloy powder in the main container.

[Brief explanation of drawings]

Fig. 1 is a schematic explanatory diagram illustrating a conventional hydrogenation reactivity control method, Fig. 2 is a graph showing the correlation between hydrogenation reactivity and equilibrium dissociation, and Fig. 3 is a graph used in the control method of the present invention. A schematic explanatory diagram of the hydrogenation reactivity detection device, Fig. 4 is a graph showing the correlation between the internal stress acting on the wall surface of the detection device and the hydrogenation reactivity, and Fig. 5
The figure is a schematic explanatory diagram illustrating the hydrogenation reactivity control method according to the present invention. 1...Hydrogen storage alloy powder storage main body container, 4...
...Hydrogen gas flow rate controller, 21...Hydrogenation reactivity detection device, 22...Pressure resistant small container, 2, 23...Hydrogen storage alloy powder, 7a, 24...Filter,
25a...Hydrogen gas communication port, 25...Cap,
26...Strain meter, 27...Conducting wire, 28...Seal mechanism, 29...Strain-stress converter, 30...Hydrogenation reactivity converter, 31...Hydrogen gas comparison controller.

Claims (1)

[Claims] 1 A main body container containing hydrogen gas storage alloy powder is filled with alloy powder of the same kind as the above alloy powder in the approximate center thereof, has a communication port with the inside of the main body container, and has a strain gauge on the outer wall surface. A pressure-resistant small container is installed, and the stress applied to the strain gauge of the small container is measured to detect the degree of hydrogenation reactivity,
A method for controlling the hydrogenation reactivity of a metal hydride, comprising adjusting the hydrogen storage flow rate of the main body container based on the detected reactivity.