SOLAR-DRIVEN METHANOL REFORMING SYSTEM FOR HYDROGEN PRODUCTION

Abstract

A solar-driven methanol reforming system for hydrogen production includes a water storage tank, high-temperature solar collector tubes, a thermocouple, valves, preheaters, an evaporator, a reactor, a heat exchanger, a mixed solution (methanol and water) storage tank, a gas separator, a pump, a carbon dioxide storage tank, a hydrogen storage tank, and pipes; the present invention utilizes solar energy to provide heat required for hydrogen production by methanol reforming, and stores some heat in a phase change material to supply heat for the methanol reforming reaction when sunlight is weak; the system does not need additional energy supply, thus saving energy consumption from traditional electric heating or fuel heating.

Claims

1. A solar-driven methanol reforming system for hydrogen production, comprising a water storage tank, high-temperature solar collector tubes, a thermocouple, valves, a preheater, an evaporator, a reactor, a heat exchanger, a mixed solution (methanol and water) storage tank, a gas separator, a pump, a carbon dioxide storage tank, a hydrogen storage tank, and pipes.

2. The solar-driven methanol reforming system according to claim 1, wherein different valves are opened based on the temperature of water at an outlet of the high-temperature solar collector tube; when the optimal range of the temperature T1 is 250° C.-300° C., valves 51, 52, 56, and 58 are opened, while other valves are closed. When the optimal range of the temperature T2 is 100° C.-250° C., valves 51, 54, 56, and 57 are opened, while other valves are closed; when the optimal range of the temperature T3 is 50° C.-100° C., valves 53 and 55 are opened, while other valves are closed; when the optimal range of the temperature T4 is below 50° C., no valve will be opened; classified utilization of solar energy is realized under different lighting conditions.

3. The solar-driven methanol reforming system according to claim 1, wherein the reactor comprising a gas diffusion chamber containing a plurality of porous medium plates, a gas confluence chamber, a separator, a plurality of branch pipes, primary confluence units, and secondary confluence units; the outer surface of each of the branch pipes is covered with a phase change material at certain intervals, the melting point of the phase change material is T1, and the outer surface of the branch pipe without the phase change material and the surface of the phase change material are covered with catalyst coatings; when water vapor flows in the branch pipes, part of the heat in the branch pipes is used for the methanol reforming reaction, and some heat is transferred to a phase change material for storage; under different lighting conditions, sufficient heat can be provided for the methanol reforming reaction, to ensure the normal reaction.

4. The solar-driven methanol reforming system according to claim 1, wherein the evaporator comprising a gas confluence chamber, a separator, a plurality of branch pipes, a plurality of spray nozzles, primary confluence units, and secondary confluence units; the outer surface of each of the branch pipes is covered with a phase change material at certain intervals, and the melting point of the phase change material is T2; the mixed solution of methanol and water is atomized by means of a spray nozzle, resulting in faster evaporation.

5. The solar-driven methanol reforming system according to claim 1, wherein the preheater comprising a transfer unit, a confluence unit, branch pipes, heating plates, mixed solution (methanol and water) flow channel plates, fins, and a phase change material, and the melting point of the phase change material selected is T3.

6. The solar-driven methanol reforming system according to claim 5, wherein the flow channels of the heating plate and the mixed solution (methanol and water) flow channel plate in the preheater are S-shaped with a gradient distance, that is, from the inlet to the outlet of a flow channel, the contact area between the fluid in the flow channel and a flow channel wall continuously increases, and the heat exchange efficiency is further improved, thus avoiding the problem that the heat exchange efficiency continuously declines due to the continuous temperature rise of the mixed solution of methanol and water from the inlet to the outlet of the flow channel; the heating plates and the mixed solution flow channel plates are alternately placed, and fins and phase change materials are placed between them, and also outside the outermost two plates.

7. The solar-driven methanol reforming system according to claim 3, wherein the gas confluence chamber and the gas diffusion chamber are funnel-shaped or in other shapes with tapered openings.

8. The solar-driven methanol reforming system according to claim 3, wherein the evaporator and the reactor adopt a gradual two-stage separator to ensure more uniform distribution of water vapor in each branch pipe.

9. The solar-driven methanol reforming system according to claim 1, wherein gas inlet and outlet pipes are connected by a gas separation membrane, the gas separation is completed by means of the gas separation membrane, the pipe on a side surface of the gas separator is connected to a hydrogen storage tank, and a gas outlet pipe is connected to a carbon dioxide storage tank.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] FIG. 1 is a schematic diagram of system composition of the present invention;

[0023] FIG. 2 is a schematic diagram of the structure of a preheater;

[0024] FIG. 3 is a schematic diagram of the structure of an evaporator;

[0025] FIG. 4 is a schematic diagram of the structure of a reactor;

[0026] FIG. 5 is a schematic diagram of the structure of a gas separator;

[0027] FIG. 6 is a schematic diagram of the structure of a separator;

[0028] FIG. 7 is a schematic diagram of the structure of a S-shaped flow channel with a gradient distance; and

[0029] FIG. 8 is a schematic diagram of the structure of a gas diffusion chamber.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] Through a pump 2, water in a water storage tank 1 is transferred to high-temperature solar collector tubes 3 connected in series for continuous heating. The system opens different valves according to the temperature of water at an outlet of the high-temperature solar collector tube detected by a thermocouple 4. When the optimal range of the detected temperature T1 is 250° C.-300° C., valves 51, 53, 56, and 58 are opened, while other valves are closed. Water vapor flows into a reactor 6 through a pipe 61 and is evenly separated to a branch pipe 63 through a separator 62. After being transferred to the branch pipe 63 and a phase change material 64, some heat is accumulated in a primary confluence unit 65 and a secondary confluence unit 66 in succession, flows out of a reactor 6 from a pipe 67 and then flows to an evaporator 7. Water vapor flows into the evaporator 7 through the pipe 67 and is evenly separated to a branch pipe 72 through a separator 71. After being transferred to the branch pipe 72 and a phase change material 76, some heat is accumulated in a primary confluence unit 73 and a secondary confluence unit 74 in succession, flows out of the evaporator from a pipe 75 and then flows to a preheater 6. Water vapor flows into a transfer unit 81 in the preheater 6 from the pipe 75, and then the water vapor in the transfer unit 81 is transferred to a heating plate 88 through a branch pipe 82. After flow in the heating plate 88 in a S-shaped loop with a gradient distance, the water vapor is transferred to a confluence unit 83 through the branch pipe 82, then flows out of a preheater 8 through a pipe 84, and finally flows back to the water storage tank 1. When the optimal range of the detected temperature T2 is 200° C.-300° C., valves 51, 52, 56, and 57 are opened, while other valves are closed, and in this case, water vapor returns to the water storage tank 1 after flowing through the evaporator 7 and the preheater 6. When the optimal range of the detected temperature T3 is 100° C.-200° C., valves 54 and 55 are opened, while other valves are closed, and in this case, water vapor returns to the water storage tank 1 after flowing through the preheater 8. When the optimal range of the detected temperature T4 is below 50° C., no valve will be opened.

[0031] The mixed solution in a mixed solution (methanol and water) storage tank 10 is transferred to a heat exchanger 11 through a pump 9. After heat exchange with the mixed gas of hydrogen and carbon dioxide generated by the methanol reforming reaction in the heat exchanger 11, the mixed solution flows into the preheater 8 through a pipe 89. Then, through the branch pipe 82, the mixed solution in the transfer unit is transferred to a mixed solution flow channel plate 87. After flow in the mixed solution flow channel plate 87 in a S-shaped loop with a gradient distance, the mixed solution is pooled in a confluence unit 811 through the branch pipe 82, then flows out of the preheater from a pipe 812, and flows to the evaporator 7. After flowing into the evaporator 7 through the pipe 812, the preheated mixed solution is ejected from a spray nozzle 77, and is vaporized upon exposure to the branch pipe 72 heated and the phase change material 76 subjected to heat storage. After confluence in a gas confluence chamber 79, the mixed solution gas flows out of the evaporator 7 through a pipe 710 and then flows to the reactor 6. The mixed solution gas flowing into the reactor 6 moves downward after being evenly diffused by means of a porous medium plate 69 in a gas diffusion chamber 68. When the mixed solution gas is exposed to a catalyst covering the surfaces of the branch pipe 63 and the phase change material 64, methanol reforming reaction occurs, followed by generation of hydrogen and carbon dioxide. The mixed gas of hydrogen and carbon dioxide moves downwards, flows out of the reactor 6 through a pipe 611 after confluence in a confluence chamber 610, and then flows to the heat exchanger 11. After heat exchange with the mixed solution of methanol and water in the heat exchanger 11, the mixed gas flows to a gas separator 14. The mixed gas flows into the gas separator through a pipe 1401 and is separated when passing through a gas separation membrane 1402. Hydrogen is separated outside the membrane and then flows into a hydrogen storage tank 12 through a pipe 1403. Carbon dioxide that cannot penetrate the membrane continues to move inside the membrane, and finally flows into a carbon dioxide storage tank 13 through a pipe 1404.

[0032] The present invention utilizes solar energy to provide heat required for hydrogen production by methanol reforming, and stores some heat in a phase change material to supply heat for the methanol reforming reaction when sunlight is weak. The system does not need additional energy supply, thus saving energy consumption from traditional electric heating or fuel heating. The hydrogen produced by means of the system is very pure and can be directly used for hydrogenation of fuel cell vehicles. The separated carbon dioxide can be recycled and reused.