JPH0114268B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for efficiently generating high temperatures by combining three metal hydrides or mixtures and utilizing their hydrogen desorption-storage cycle.

Many metals and alloys have the property of easily reacting with hydrogen to produce hydrides while generating heat, and when the hydrides produced in this way are heated, they return to the state of metals and alloys while producing hydrogen. Therefore, technology to obtain high or low temperatures by utilizing heat generation and endotherm during the reaction with hydrogen and the decomposition of hydrides has recently been attracting attention.

By the way, conventional high temperature generation methods using metal hydrides as a medium are carried out by combining one or two types of metal hydrides that have characteristics suitable for a given purpose, but it is difficult to use them practically. Due to the limited temperature range that can be used as a metal hydride or heat source, it is currently not possible to efficiently obtain high temperatures.

On the other hand, unused energy such as natural energy such as solar heat, atmospheric heat, seawater energy, geothermal heat, factory waste heat, and surplus heat that exists at low energy levels can be converted into high-level energy that can be used for various purposes. Conversion is becoming a major social issue from the standpoint of energy conservation and utilization of unused energy.

The present inventors have conducted extensive research in order to develop a method for generating high-level energy that can be used for various purposes using metal hydrides or low-level energy sources that were not available with conventional technology. As a result, it was discovered that the objective could be achieved by combining three types of metal hydrides having different hydrogen equilibrium pressure characteristics to form a heat release-endotherm cycle, and based on this knowledge, the present invention was made. Ivy.

That is, the present invention provides three types of metal hydrides or mixtures having different hydrogen equilibrium pressure characteristics.
MH, M′H and M″H are selectively used, (a) MH exhibiting the highest hydrogen equilibrium pressure is thermally decomposed by heat from the supplied heat source at a temperature t ₁ , (b) the process released by (a) is A process of absorbing hydrogen into M″H which exhibits the lowest hydrogen equilibrium pressure at temperature t _{2 (} t ₂ > t ₁ ) and generating a desired high temperature; (c) a process of generating a desired high _temperature ; In ₂ ), the process of thermally decomposing M″H using heat from the supply heat source, the hydrogen released in (d) and (c) is heated to a temperature of t ₃ (t ₃ <t ₁ ′
)
(e) A process in which M′H exhibits a hydrogen equilibrium pressure intermediate between MH and M″H in (e) M′H is heated by heat from a supplied heat source at a temperature t ₁ ″ (t ₁ ″>t ₃ ). _The hydrogen released by _the decomposition process and (f) (e) _is
″)
The present invention provides a high temperature generation method characterized by repeating a cycle consisting of a process in which MH is absorbed in MH.

Next, the heat radiation-endothermic cycle of the method of the present invention will be explained with reference to the accompanying drawings. Figure 1 is a graph showing the hydrogen equilibrium pressure characteristics of three metal hydrides, MH, M'H, and M″H, with the reciprocal of temperature on the horizontal axis and the hydrogen equilibrium pressure on the vertical axis. In the figure, hydrogen is A
→ B → C → D → E → F → A cycle is followed by repeated absorption and release with the metal hydride, during which a high temperature of maximum t _B is generated. The upper limit of this t _B is
Pressure at point A of MH P Almost equal to _A
This is the temperature t B ′ at point _B ′ of M″H corresponding to P _B ′.

That is, when the metal hydride MH exhibiting the highest hydrogen equilibrium pressure is thermally decomposed by a supplied heat source at point A, and the hydrogen generated at this time is absorbed by the metal hydride M″H exhibiting the lowest hydrogen equilibrium pressure, An exothermic reaction occurs, and the temperature rises to a temperature t _B corresponding to point B. Next, this M″H is thermally decomposed at point C by the heat from the supplied heat source, and the resulting hydrogen is converted to MH at point D. and M″H, which exhibits a hydrogen equilibrium pressure between
Further, this is thermally decomposed at point E using heat from a supplied heat source. Next, the hydrogen generated at this time is absorbed into the metal hydride MH at point F, and the thermal decomposition reaction is carried out again at point A using the heat supplied from the heat source.

In this case, the metal hydrides MH, M′H and M″H
As a supply heat source that provides heat to decompose,
Since it is practically desirable to use the same heat source, the temperatures t ₁ , t ₁ ', and
It is preferable that t ₁ ″ be the same, but of course these temperatures can be different if necessary. Also, the temperature at which the metal hydride absorbs hydrogen, that is, the temperature at point D and point E, t ₃ and t ₃ ′ are also
It is convenient to carry out the process at the same ambient temperature, but a different temperature can be selected if necessary.

The metal hydride used as a heat medium in the method of the present invention is not particularly limited, as long as it is a combination of three types having different hydrogen equilibrium pressure characteristics.
The metal constituting this metal hydride may be a single substance or an alloy. Further, the metal hydride may be a single metal hydride or a mixture of two or more metal hydrides.

An example of such a combination is LaNi ₅ −
Hydride combination of TiMn _1.5 −MmNi ₅ , LaNi _4.7
Hydride combinations of Al _0.3 −MmNi _4.5 Al _0.5 −Ti _0.8 Zr _0.2 Cr _0.8 Mn _1.2 , LaNi ₅ −MmNi _4.9 Al _0.1 −TiCo _0.5
Hydride combination of Mn _0.5 , MmNi _4.5 Al _0.5 −
Examples include a combination of hydrides of MmNi ₅ -TiCo. These can be used in any desired form, such as powder, pellet, or held on a porous support.

Next, as a supply heat source in the method of the present invention,
Solar heat collected by flat plate solar collectors, waste heat from factories, waste heat from boilers, household waste heat, etc. are used.

FIG. 2 is an explanatory diagram showing an example of an apparatus for carrying out the method of the present invention. In this figure, metal hydrides MH, M″H and M′H are contained in pressure vessels 1, 2 and 3, respectively. First, as shown in the figure, only the valve 6 of the communicating pipe is opened, and the valves 7 and 8 of the other communicating pipes are closed.
By opening the valve 9 of the heat transfer tube from the solar heat collector 4, the MH in the pressure vessel 1 is heated. The hydrogen released by this heating is introduced into the pressure vessel 2 through the communication pipe, where it reacts with M″H and generates high temperature. When the reaction with hydrogen is completed, valve 6 is closed, valve 7 is opened, and then valve 10 of the heat transfer tube is opened to heat the pressure vessel 2. Therefore, M″H is thermally decomposed. The hydrogen thus released is sent through the communication pipe into the pressure vessel 3, where it reacts with M'H. Then valve 7
is closed, valve 8 is opened, and then valve 11 of the heat transfer tube is opened to heat M'H in pressure vessel 3 to cause thermal decomposition, and the released hydrogen is transferred to pressure vessel 1. Absorb into MH. During this cycle, the heat generated by the reaction of M'H, MH, and hydrogen is dissipated by appropriate means such as air cooling or water cooling.

By repeating the above operations, the required high temperature can be continuously generated.

As described above, according to the present invention, high temperatures can be efficiently generated using a low temperature heat source, and three types of metal hydrides are appropriately combined.
The types of metal hydrides that can be used, as they can form a cycle between the heat source temperature and the target high temperature
The freedom of choice regarding the type of heat source can be significantly expanded.

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 In the apparatus shown in FIG.
MmNi ₅ hydride, LaNi ₅ hydride in pressure vessel 2,
Each pressure container 3 was filled with 1 kg of TiMn _1.5 hydride powder.

The container used at this time was made of SUS-316 and had an outer diameter of 42.7
mm, length 30cm.

Next, the pressure vessel 1 was heated to approximately 80°C using solar heat, and the released hydrogen was sent to the pressure vessel 2 through the valve 6 for reaction, resulting in a usable high temperature of up to 157°C. Ta. Next, the pressure vessel 2 is heated to about 80°C in the same manner as described above to cause a decomposition reaction, and the generated hydrogen is passed through the valve 7 to the pressure vessel 3.
to absorb hydrogen at approximately 40°C. When this is further heated and the generated hydrogen is sent to the pressure vessel 1 via the valve 8, the MmNi ₅ hydride is regenerated.

Therefore, by repeating this cycle, using low level energy of about 80℃,
It is possible to obtain temperatures as high as 157℃. Also,
At this time, regeneration of MmNi ₅ hydride can be performed with a low heat source of 40°C or less by passing through TiMn _1.5 .

FIG. 3 is a temperature-hydrogen equilibrium pressure graph showing the thermal cycle in this example.

Example 2 Instead of MmNi ₅ , LaNi ₅ and TiMn _1.5 in Example 1, Ti _0.8 Zr _0.2 Cr _0.8 Mn _1.2 , LaNi _4.7 Al _0.3 and
Using MmNi _4.5 Al _0.5 and in exactly the same manner as in Example 1, it was possible to obtain a high temperature of 160°C from factory waste heat of about 55°C. For the heat source during regeneration, a low temperature of 10°C was sufficient.

A temperature-hydrogen equilibrium pressure graph showing the thermal cycle in this example is shown in FIG.

[Brief explanation of drawings]

FIG. 1 is a graph showing hydrogen equilibrium pressure characteristics for explaining the thermal cycle of the present invention, FIG. 2 is an explanatory diagram of an example of an apparatus for carrying out the method of the present invention, and FIG.
4 and 4 are graphs showing hydrogen equilibrium pressure characteristics in Examples of the present invention. In FIG. 2, 1, 2, and 3 are pressure containers, 4 is a solar heat collector, and 5 is an object to be heated.

Claims (1)

[Claims] 1. Three metal hydrides or mixtures MH, M′H and M″H having different hydrogen equilibrium pressure characteristics
(a) The process of thermally decomposing the MH exhibiting the highest hydrogen equilibrium pressure by heat from the supplied heat source at a temperature t ₁ , (b) The process of thermally decomposing the MH exhibiting the highest hydrogen equilibrium pressure by the heat from the supplied heat source, (b) The hydrogen released by (a) is decomposed at a temperature t ₂ (t ₂ > t ₁ ), the _process of absorbing hydrogen into M _″ H exhibiting the lowest equilibrium hydrogen pressure and generating _a desired high temperature; In the process of thermal decomposition _by heat from ( _d ) (c) _, the hydrogen released by
)
A process in which M′H exhibits a hydrogen equilibrium pressure intermediate between MH and M″H absorbs the hydrogen at (e) M′H is heated by heat from the supplied heat source at a temperature t ₁ ″ (t ₁ ″>t ₃ ). _The hydrogen released by _the decomposition process and (f) (e) _is
″)
A high temperature generation method characterized by repeating a cycle consisting of a process of absorption into MH. 2. The method according to claim 1, in which t ₁ , t ₁ ', and t _{1 '} ' are at the same temperature. 3. The method according to claim 1, in which t ₃ and t ₃ ' are at the same temperature. Method.