1. A metal hydride reactor filled with composite compaction unit bodies in a modularized mode is characterized by comprising a reactor shell (1), a reaction bed (2) positioned in the shell, a hydrogen inlet and outlet pipe (3) arranged on the shell and a heat exchange pipe (4) positioned in the center of the reaction bed; the reaction bed is formed by modular filling of unit bodies formed by compounding and compacting metal hydride and expanded graphite, the unit bodies are provided with through holes which are communicated up and down and are used for absorbing and releasing hydrogen, the unit body modular filling structure of the reaction bed is formed, the unit bodies are of a ring layer structure in the radial direction, the unit bodies of adjacent ring layers, the outer edge surface of the unit body positioned on the inner ring is attached to the inner edge surface of the unit body positioned on the outer ring, the inner edge surface of the unit body positioned on the innermost ring is attached to the outer edge surface of the heat exchange tube, and the mass content of the expanded graphite of the unit bodies is gradually reduced from the inner ring layer to the outer ring layer; and a heat exchange fluid is introduced into the heat exchange tube and used for cooling or heating the metal hydride in the unit body.

2. The modular filled composite compacted unit cell metal hydride reactor as claimed in claim 1, wherein the expanded graphite mass content of the unit cells constituting the reaction bed is gradually decreased in a gradient manner by the circle layers, and the expanded graphite mass content of the unit cell of the outermost circle layer is not less than 3%, and the expanded graphite mass content of the unit cell of the innermost circle layer is not more than 30%.

3. The modular composite packed compacted unit cell filled metal hydride reactor as claimed in claim 2, wherein the gradient of the gradual decrease of the unit cell expanded graphite mass content in the reaction bed in the circle layers is 0.5-10%.

4. A modular packed composite packed cell metal hydride reactor as claimed in any one of claims 1 to 3, wherein the reactor bed has a plurality of modular packed cell layers in the axial direction, each modular packed layer has the same structure, and the cell through holes in the lower layer are butted against the cell through holes in the upper layer to form a flow path for hydrogen absorption and release.

5. A modular packed composite packed cell metal hydride reactor as claimed in claim 4, in which the reaction bed is constructed by modular packing of the same cells of the same configuration and dimensions, the cells filling as much of the entire reactor shell as possible.

6. The metal hydride reactor as claimed in claim 5, wherein the unit bodies forming the reaction bed are regular hexagonal prism unit bodies with side length of 10-80 mm and height of 3-60 mm, and the center of the unit bodies is provided with hydrogen gas flow holes.

7. The modular filling composite compacted unit body metal hydride reactor as claimed in claim 6, wherein the inside diameter of the shell of the reactor is controlled to be 100 to 800mm, and the reactor bed formed by modular filling of the unit bodies is radially set to 2 to 8 lap areas in terms of the mass content of expanded graphite.

8. A modular composite packed compact metal hydride reactor as claimed in any of claims 1 to 4 in which the reaction bed is spaced from the reactor shell at the heat exchange fluid outlet by a distance of not less than 5mm to form a hydrogen gas inlet and outlet chamber, a gas distribution chamber is provided at the inlet stage and a gas collection chamber is provided at the outlet stage.

9. A modular packed composite packed cell metal hydride reactor as claimed in any one of claims 1 to 4, wherein the heat exchange fluid introduced into the heat exchange tubes for cooling or heating the metal hydride in the cell is a single phase convective heat exchange fluid or a phase change convective heat exchange fluid.

10. The modular filled composite compaction unit cell metal hydride reactor of claim 9 wherein the single phase convective heat transfer fluid is water, air, molten salt or a thermally conductive oil; the phase-change convective heat transfer fluid is a refrigerant or water.

Background

The reaction process of hydrogen absorption by the hydrogen storage alloy to form metal hydride will give off heat. And the metal hydride is decomposed into a hydrogen storage alloy and hydrogen gas after being heated. By utilizing the characteristic, the metal hydride can be applied to the field of thermochemical heat storage and has the advantages of good reversibility, large reaction heat, low corrosivity, easy control of reaction and the like. In addition, the metal hydride has great application potential in the heat utilization fields of refrigeration, air conditioning, heat pump and the like.

The metal hydride reactor is the core of the thermal storage system, and the performance of the overall thermal storage system depends on the heat transfer performance of the reactor. The heat transfer performance of the metal hydride reactor is enhanced, which is beneficial to improving the reaction rate of hydrogen absorption and desorption and the heat storage power. Among them, the addition of expanded graphite in the metal hydride bed is a very effective reactor heat transfer enhancement measure. For example, when 10 wt.% expanded graphite is added to magnesium hydride and pressed into a composite compacted unit, the effective thermal conductivity in the radial direction of the bed layer is greatly improved compared with that of a powdery bed layer, and 8W/(m · K) is achieved. And with the increase of the content of the expanded graphite, the effective heat conductivity coefficient of the bed layer is also greatly improved.

However, the method has the disadvantages that as the filling amount of the expanded graphite is increased, the expanded graphite does not participate in hydrogen absorption and desorption reaction, the hydrogen storage density per unit volume of a reactor bed layer is reduced, and the volume heat storage density is reduced along with the reduction of the hydrogen storage density per unit volume. At present, the composite compaction unit body is generally made into a cylindrical shape and is filled into a reactor shell in a multi-block stacking mode. However, the small size of the metal hydride and expanded graphite composite compacted unit body is also a difficulty in how to efficiently load the composite compacted unit body into a large-diameter reactor and ensure high hydrogen flowability. Therefore, how to solve the above problems becomes a focus of research in the art.

Disclosure of Invention

The invention aims to overcome the defects in the prior art, and provides a metal hydride reactor formed by modularly filling composite compaction unit bodies with different expanded graphite contents according to heat flow change, so as to solve the problem that the hydrogen storage density per unit volume of a reaction bed can be reduced along with the increase of the filling amount of the expanded graphite in the metal hydride reactor in the prior art.

The purpose of the invention can be realized by the following technical scheme.

The invention provides a metal hydride reactor with a modularized filling composite compaction unit body, which comprises a reactor shell, a reaction bed positioned in the shell, a hydrogen inlet and outlet pipe arranged on the shell and a heat exchange pipe positioned in the center of the reaction bed; the reaction bed is formed by modular filling of unit bodies formed by compounding and compacting metal hydride and expanded graphite, each unit body is provided with a through hole which is communicated up and down and is used for absorbing and releasing hydrogen, a unit body modular filling structure of the reaction bed is formed, each unit body is of a ring layer structure in the radial direction, the unit bodies of adjacent ring layers, the outer edge surface of each unit body positioned on the inner ring is attached to the inner edge surface of each unit body positioned on the outer ring, the inner edge surface of each unit body of the innermost ring is attached to the outer edge surface of the heat exchange tube, and the mass content of the expanded graphite of each unit body is gradually reduced from the inner ring layer to the outer ring layer; and a heat exchange fluid is introduced into the heat exchange tube and used for cooling or heating the metal hydride in the unit body.

The invention can further adopt the following technical measures which can be respectively adopted, also can be adopted in combination or even can be adopted together.

Preferably, the mass content of the unit body expanded graphite forming the reaction bed can be gradually reduced in a gradient manner according to the ring layer, the mass content of the unit body expanded graphite of the outer ring layer is preferably not less than 3%, and the mass content of the unit body expanded graphite of the inner ring layer is preferably not more than 30%; further preferably, the gradient of the gradual decrease of the mass content of the unit volume expanded graphite forming the reaction bed is generally controlled within the range of 0.5-10%.

Preferably, the reaction bed is modularly filled with a plurality of layers of unit bodies in the axial direction, each layer of modularized filling structure is the same, and the unit body through holes positioned on the lower layer are butted with the unit body through holes positioned on the upper layer to form a flow channel for hydrogen absorption and release.

Preferably, the reaction bed is formed by modularly filling unit bodies with the same structure and the same size; the unit bodies forming the reaction bed fill the whole reactor shell as much as possible, so that the space utilization rate in the reactor is improved.

Preferably, the unit bodies forming the reaction bed can be regular hexagonal prism-shaped unit bodies with the side length of 10-80 mm and the height of 3-60 mm, and hydrogen circulation holes are formed in the centers of the unit bodies.

Preferably, the inner diameter of the shell of the reactor is controlled within the range of 100-800 mm, the reaction bed formed by modular filling of unit bodies can be set into 2-8 zone layers according to the mass content of the expanded graphite in the radial direction.

Preferably, the reaction bed is spaced from the reactor shell at the heat exchange fluid outlet end by a distance of not less than 5mm to form a hydrogen inlet and outlet chamber, which serves as a gas distribution chamber during the gas inlet phase and a gas collection chamber during the gas outlet phase.

Preferably, a single-phase convective heat transfer fluid or a phase-change convective heat transfer fluid is introduced into the heat transfer pipe to cool or heat the metal hydride in the unit body; further, the single-phase convective heat transfer fluid is water, air, molten salt or heat transfer oil; the phase-change convective heat transfer fluid is a refrigerant or water.

Compared with the prior art, the invention has the beneficial effects that:

1) according to the invention, unit bodies with different expanded graphite mass contents are filled in a modularized mode according to the direction of the heat flow of the reaction bed layer of the metal hydride reactor, the expanded graphite mass content of the unit body positioned in the inner ring area with large heat flow density of the reaction bed layer is higher, and the expanded graphite mass content of the unit body positioned in the outer ring area with small heat flow density of the reaction bed layer is lower. The heat conductivity coefficient of the unit body formed by compounding and compacting the metal hydride and the expanded graphite is increased along with the increase of the content of the expanded graphite, the unit body with the modularized filling expanded graphite content changed along with the distribution of heat flow is beneficial to the uniform distribution of the temperature of a reaction bed layer, the hydrogen absorption reaction rate is increased, and the heat storage efficiency of the reactor is increased along with the increase of the heat storage efficiency.

2) The center of each composite compaction unit body is provided with the hole, so that the contact area of the reaction bed layer and hydrogen can be increased, the reaction bed layer and the hydrogen can be fully contacted, the hydrogen absorption and release reaction of the composite compaction unit bodies can be supplemented and discharged in time, and the hydrogen inlet and outlet cavity between the shell at the hydrogen inlet and outlet end and the reaction bed provides enough circulation space for the hydrogen, so that the high fluidity of the hydrogen is ensured.

Drawings

FIG. 1 is a schematic axial cross-sectional view of a metal hydride reactor in accordance with one embodiment of the present invention;

FIG. 2 is a schematic top view of the embodiment of the metal hydride reactor of FIG. 1;

fig. 3 is a schematic radial cross-sectional view of the metal hydride reactor of the embodiment of fig. 1.

Wherein: 1-a shell; 2-a reaction bed; 3-hydrogen inlet and outlet pipes; 4-heat exchange tube.

Detailed Description

The invention will be further described with reference to specific embodiments and the accompanying drawings.

Examples

As shown in fig. 1, 2 and 3, a metal hydride reactor which is modularized and is filled with a composite compacted unit body with expanded graphite content changing with heat flow comprises a shell 1, a reaction bed 2, a hydrogen inlet and outlet pipe 3 and a heat exchange pipe 4, wherein the reaction bed 2 is arranged inside the shell 1 to form a reaction cavity, the hydrogen inlet and outlet pipe 3 is arranged on the outer surface of the shell, and the heat exchange pipe 4 penetrates through the center of the reaction bed; the reaction bed is formed by modularly filling unit bodies which are formed by compounding and compacting metal hydride with through holes in the center and expanded graphite in the same specification. The unit body modularization filling structure is arranged in the radial direction, four circles of unit bodies are arranged from inside to outside, the unit bodies are divided into 3 circle layer parts according to the mass content of expanded graphite, the inner circle layer comprises unit bodies of a first circle and a second circle, the middle circle layer is a unit body of a third circle, the outer circle layer is a unit body of a fourth circle, the mass content of the expanded graphite of the unit bodies of the inner circle layer is 17%, the mass content of the expanded graphite of the unit bodies of the middle circle layer is 10%, the mass content of the expanded graphite of the unit bodies of the outer circle layer is 3%, and the average mass content of the expanded graphite of a reaction bed is guaranteed to be 10%. The unit body modularization filling structures are in the axial direction, each layer of filling structure is the same, and through holes of the unit bodies on the upper layer and the lower layer are connected to form a hydrogen flow channel. The reactor shell is filled with the unit bodies forming the reaction bed as much as possible to improve the space utilization rate in the reactor, but the reaction bed is arranged at the outlet end of the heat exchange fluid and is spaced from the reactor shell by at least 5mm to form a hydrogen inlet and outlet chamber, the hydrogen inlet stage is used as a gas distribution chamber, and the hydrogen outlet stage is used as a gas gathering chamber. The unit body of the embodiment is a regular hexagonal prism with a uniaxial pressing pressure of 100MPa, the side length of the cross section is 13mm, and the height is 15 mm; the shell is a columnar shell with the inner diameter of 187mm, the height of 500mm and the inner volume of 13.73L; the inner diameter of the heat exchange pipe is 20mm, and the outer surface of the heat exchange pipe is a hexahedron matched with the regular hexagonal prism-shaped composite compaction unit body; the shell and the heat exchange tube are both made of 316L stainless steel; the heat exchange fluid in the heat exchange tube is heat transfer oil Dowtherm A, and the inlet flow velocity is 0.2 m/s. The total mass of the co-filled magnesium hydride in the reactor of this example was 11.72kg, and the total mass of the expanded graphite was 1.34 kg; the magnesium hydride is activated magnesium hydride powder with an average particle size of 1-10 μm, and the expanded graphite in the unit body is of the same type. The reactor of this example was equipped with a heating device, heated to an initial temperature of 570K, and subjected to a hydrogen-absorbing reaction under a hydrogen pressure of 2 MPa.

For comparison, the metal hydride reactor has uniform materials, dimensions, operation parameters and the like, and the only difference lies in the change of the reaction bed layer, the unit bodies in the reaction bed layer are all uniformly filled with the expanded graphite with the mass content of 10 percent, the filling amount of the expanded graphite is the same as that of the metal hydride bed layer shown in figure 3, and the main technical index of the reactor, namely the heat storage power per unit weight is simulated and calculated through numerical simulation software.

In this example, the heat storage power per unit weight of the metal hydride reactor comprising the unit cells in which the content of the expanded graphite was changed by the heat flow was 40.95 W.kg, as compared with the reactor in which the bed was uniformly filled with 10% of the expanded graphite^-1The increase was 53.70 W.kg^-1The increase is 31.13%.

The above description is only exemplary of the present invention and should not be taken as limiting the invention, as any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention will fall within the protection scope of the appended claims.