JPS591953B2 - Control method and device for heat storage/dissipation system using metal hydride - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for controlling a heat storage/radiation system that utilizes the heat generated during hydrogen absorption/devolatilization of a metal hydride.

Lanthanides (Lanth) are commonly referred to as hydrogen storage metals.
anide, rare earth) actinide
Including elements, transition metal elements in periods 3 to 5 of the periodic table, or alloys containing these elements, such as T1Fe, absorb a large amount of hydrogen gas under certain temperature and pressure conditions and become metal. It is known that it is easy to form hydrides, generates heat in the process, devolatilizes hydrogen under certain temperature and pressure conditions, and absorbs heat in the process.

By utilizing the above-mentioned properties of hydrogen storage metals, metal hydrides can be used as heat storage bodies to store natural energy such as solar heat, wind power, industrial waste heat, etc., and extract heat as needed for use in air conditioning, heating, etc. Although research and development of energy storage and utilization systems for energy storage and utilization are actively being carried out in various fields, there are still many problems that remain before practical application.

The metal hydride is held, heat is applied to it from the outside to store heat, hydrogen gas is devolatilized, and if necessary, the hydrogen gas is occluded to radiate heat, and this heat is transferred to a heat exchange fluid. The heat exchanger from which the heat is taken out for use is called a reaction tank.

For the above purpose, the reaction tank has a space for holding metal hydride particles and a permeable wall for supplying hydrogen gas to the metal hydride held in the space and recovering the devolatilized hydrogen gas. adjacent to the metal holding space above through;
It has a hydrogen gas holding space connected to a hydrogen gas holder by hydrogen gas piping, and a heat exchange tube installed in the metal holding space to extract reaction heat, or a heat exchange surface as a wall of the space. The heat of reaction during absorption and desorption is recovered and supplied by a heat exchange fluid via the heat exchange tube or heat exchange surface.

Now, one of the characteristics of metal hydrides is that they have a fast absorption and desorption rate of hydrogen gas, but in the case of heat storage and release systems using the same metal, this is a drawback, and the metal's heat generation and heat absorption output is reduced. Control becomes difficult.

Conventionally, as a method to adjust the calorific value output of metal hydride in response to fluctuations in heat load, a flow rate control valve is installed in the hydrogen gas piping that supplies hydrogen gas to the reaction tank, and this allows the hydrogen gas flowing into the reaction tank to be adjusted. Methods of controlling the volumetric flow rate and mass flow rate of the reactor, and methods of controlling the pressure inside the reaction tank have been considered, but when controlling with these methods, a flow rate adjustment valve and its control mechanism are required. Not only is the mechanism complicated, but it is also difficult to accommodate a wide range of heat load fluctuations. Furthermore, if the system has only one reaction tank, there is a drawback that all functions of the five systems will stop when maintenance, inspection, and repair is performed. In view of the above-mentioned drawbacks of the conventional heat output control method using a flow control valve or pressure control and the heat storage/dissipation system composed of one reaction tank, the present invention provides a method with a simple and inexpensive control mechanism. An object of the present invention is to provide a method and device for controlling a heat storage/dissipation system using a metal hydride, which can cope with a wide range of heat load fluctuations, even when the heat load is low, and which prevents all functions from stopping even during maintenance, inspection, and repair.

Hereinafter, the present invention will be described in detail with reference to the drawings showing embodiments thereof. FIG. 1 is a piping system diagram of a first embodiment of a heat storage/radiation system to which the present invention is applied.

This system is used, for example, to heat greenhouses in vegetable gardens. In this example, metallic hydrogen used throughout the system 3. Compound 1 is divided into 5 equal parts and 5 reaction vessels A, B, C
, D, and E are accommodated in the metal hydride holding spaces 3. The number of reaction vessels is not necessarily limited to five, and the type and amount of metal in each reaction vessel may be different. A hydrogen gas holding space 4 is provided surrounding the metal holding space 3 and on the outside thereof via an air-permeable wall. Hydrogen gas pipes 5a, 5b, . . . , 5e are piped between each hydrogen gas holding space and a hydrogen gas holder (not shown). Each of these hydrogen gas pipes 5a, 5b,...
, 5e respectively have an orifice 2 and valves Al, Bl, C.
1, Dl, and El are provided. The above hydrogen gas pipes and valves are connected as shown in the figure: reaction tank A is connected through valve A1; B is connected through valves B, Al; and C is connected through valves Cl, Bl, and Al. D is connected to the hydrogen gas holder via valves D, Cl, B, , A, and E is connected to the hydrogen gas holder via valves El, Dl, Cl, Bl, and Al, respectively.

The metal hydride holding space 3 of each reaction tank A, B, C, D, and E includes a heat exchange coil 6 through which a heat exchange fluid flows.
a, 6b, . . . , 6e are provided.

These heat exchange coils have valves B3, C3, D3, E3 between them.
and valves A2, B2, C2, D2, E2 are provided between the heat exchange fluid supply pipe 7 and the inflow side of each coil 6a, 6b, . . . , 6e. The discharge side of the coil 6a is connected to a heat exchange fluid discharge pipe 8. Hydrogen gas valve Al, B
l, C2, Dl, El and heat exchange fluid valves A2, B2,
C2, D2, E2; B3, C3, D3, E3 are valve opening drive signals (e.g. temperature signals) corresponding to the heat load of a heat utilization facility such as a greenhouse for a vegetable garden (a), (b), (c), (
Opening/closing is controlled by d) and (e).

Here, (ω is 1/5 load with respect to the maximum output of this system, (b) is 2/5 load, (c) is 3/5 load, (d)
is a signal corresponding to 4/5 load, and e is a signal corresponding to full load.

Also, valves controlled by signals indicated by symbols (a), (b), ..., (e) in the figure, namely Al, ..., E1;
B3, . . . E3 are in an open state against the heat load corresponding to each signal and a higher heat load, and (?, 5, . . .
..., a valve whose opening/closing is controlled by a signal indicated by ω, that is, A
2, B2, . . . , E2, the valves are open only when that signal is received, and are closed when other signals are received. Therefore, the relationship between the signal corresponding to the required heat load and the opening/closing state of the valve can be summarized as follows. The control operation when heating a greenhouse in a vegetable garden, for example, using the heat storage/dissipation system configured as described above will be described below.

During the day, when the outside temperature is high, the temperature inside the greenhouse is high, so the heat load is small, and only needs to be about I/5 of the maximum output of this heat storage/dissipation system.

At this time, since the temperature inside the greenhouse is high, the temperature signal becomes (AXa), and according to the table above, only valves Al and A2 are opened, hydrogen gas flows only through reaction tank A, and heat exchange fluid flows through the heat exchange coil. It circulates only in 6a, and only reaction tank A operates.
Therefore, in this case, the heat output is 1/5 of the maximum heat output of the system. In the evening, when the temperature inside the greenhouse drops, the temperature signal from the greenhouse becomes (b), 8, and the valves Al, Bl,
B3 and B2 are opened and reaction vessels A and B are activated.

Therefore, twice as much heat as during the day is supplied by this system. In the middle of the night, when the temperature inside the greenhouse drops further, the temperature signals from the greenhouse become (c) and (c), and reaction vessels A, B, and C are activated. At dawn, when the heat load is at its maximum, the temperature signals from the greenhouse become (d) and (d), and reaction vessels A, B, C, and D are activated.

Furthermore, when the heat load is large, for example, at midnight or dawn in the middle of the winter, the temperature signal becomes (e), ω, and all five reaction vessels are activated and the maximum heat output of this system is exerted.

Note that the orifice 2 is provided to restrict the flow rate of hydrogen gas applied to the metal hydride so that the heat output becomes uniform over a long period of time.

(For example, at a hydrogen partial pressure of 20kν or 2G, the flow coefficient CVL-4
A suitable value is x10-4. ) FIG. 2 is a piping system diagram showing a second embodiment of the heat storage/radiation system to which the present invention is applied. In this example, the total heat output of the system is divided into five equal parts, and five reactors A, B, C, D, and E are used.
The arrangement of the hydrogen gas pipes, valves and orifices to each reaction tank, and the opening/closing control method of valves A, B, C, D, and E are the same as in the first embodiment, except that The heat exchange coils 6a, 6b, . . . , 6e respectively form a jacket that contacts and surrounds the outside of the metal hydride holding space 3, and the heat exchange coils 6e, 6d of each reaction tank
, 6c, 6b, and 6a are connected in series in this order without using a valve, and the heat exchange fluid inflow pipe 7 is connected to the coil 6e.
A heat exchange fluid discharge pipe 8 is connected to the inflow end of the coil 6a, and a heat exchange fluid discharge pipe 8 is connected to the outflow end of the coil 6a.

Therefore, when the heat load is low during the day, the temperature signal (a) is emitted from the greenhouse, only valve A1 is opened, and hydrogen gas flows only to reaction tank A.

On the other hand, the heat exchange fluid is used for all the heat exchange coils 6e of the reaction vessels.
, 6d, 6c, 6b, and 6a in order, and the heat generated from the metal hydride is exchanged only at the coil 6a of the reaction tank A and supplied to the greenhouse. In the evening, the temperature signal changes to (tortoise), in the middle of the night, the temperature signal changes to (c), and as dawn approaches, the temperature signal changes to (4), and the number of operating reaction vessels decreases to 2. , 3, and 4, but the stroke of the heat exchange fluid does not change, and the change in heat load is controlled by changing the part where heat exchange is performed, that is, the heat exchange length (area). It is.

Compared to the system of the first embodiment, the system of this embodiment eliminates the need for heat exchange fluid valves A2, B2, B3, C2, C3, etc., and has a simpler mechanism, which helps to reduce costs. As described above, the present invention eliminates the need for a flow rate regulating valve, simplifies the control mechanism, contributes to cost reduction, and makes it possible to cope with a wide range of heat load fluctuations.

Furthermore, by providing a plurality of reaction vessels as a unit, it is possible to avoid stopping all functions of the system during maintenance, inspection, and repair. (In this case, it is only necessary to temporarily change the set values of the valve opening/closing signals of each valve.) Furthermore, since the reaction tank is made smaller, transportation and installation can be facilitated.

[Brief explanation of drawings]

FIG. 1 is a piping system diagram showing a first embodiment of a heat storage/radiation system to which the present invention is applied, and FIG. 2 is a piping system diagram showing a second embodiment. 1... Metal hydride, 5a, 5b,..., 5e...
・Hydrogen gas piping, 6...Heat exchange coil, A, B, C,
D, E″″3 unit reaction tank, Al9Bl9Cl9Dl
El...Hydrogen gas valve, A2, B2, C2, D2, E
2; B3, C3, D3, E3... valve for heat exchange fluid;
(a)9(b)? (c)? (d)9(e)9G09Gδ
G) 9aD9G) 31 Valve opening/closing driving signal (for example, temperature signal).

Claims (1)

[Scope of Claims] 1. A metal hydride is held, heat is applied from the outside to store heat, hydrogen gas is devolatilized, and if necessary, the hydrogen gas is occluded to release heat, and heat exchange is performed. In a method for controlling a heat storage/dissipation system equipped with a reaction tank that is recovered by fluid, a plurality of reaction tanks are provided as units, and the number of reaction tank units used is automatically switched by a signal corresponding to the heat load condition. A control method characterized by: 2. A reaction tank that holds a metal hydride, stores heat by applying heat from the outside, devolatilizes hydrogen gas, and if necessary releases heat by occluding the hydrogen gas and recovers it with a heat exchange fluid. In a control device for a heat storage/dissipation system equipped with a heat storage/dissipation system, a plurality of reaction tanks are installed as units, and the hydrogen gas piping connected to each reaction tank is connected to a certain heat load and a higher heat load of the heat utilization facility, respectively. A control device characterized in that valves are provided that are opened in response to a corresponding signal, and the magnitude of the minimum heat load for opening each valve is set by changing stepwise for each reaction tank. 3. The control device according to claim 2, wherein all of the heat exchange tubes provided in each of the reaction vessels are connected in series without any valves between them.