Photo-thermal coupling methanol reforming hydrogen and power cogeneration system

Abstract

The application discloses a photo-thermal coupling methanol reforming hydrogen and electricity cogeneration system, which comprises a photo-thermal unit, a heat storage unit, a methanol reforming hydrogen production unit, a fuel cell unit and a steam turbine power generation unit, the heat storage unit is connected with the photo-thermal unit, the methanol reforming hydrogen production unit, the fuel cell unit and the steam turbine power generation unit respectively, and the fuel cell unit is connected with the methanol reforming hydrogen production unit and the steam turbine power generation unit respectively; the photo-thermal unit stores the heat energy of solar radiation in the heat storage unit, the heat storage unit supplies heat to the methanol reforming hydrogen production unit, the methanol reforming reaction occurs in the methanol reforming hydrogen production unit, hydrogen produced is supplied to the fuel cell unit, the fuel cell unit generates electricity through hydrogen and discharges high-temperature water vapor, and the heat energy of the discharged high-temperature water vapor is directly supplied to the steam turbine power generation unit or stored in the heat storage unit and supplied to the steam turbine power generation unit through the heat storage unit. The methanol reforming hydrogen production and electricity generation can be realized with high efficiency and low carbon.

Description

Technical Field

[0001] This invention belongs to the field of methanol-to-hydrogen technology, specifically relating to a photothermal coupled methanol reforming hydrogen-power cogeneration system. Background Technology

[0002] Methanol reforming hydrogen production technology is a process that converts methanol and water into hydrogen and carbon dioxide under the action of a catalyst. This process has the advantages of low cost, high hydrogen purity, simple equipment, and convenient storage and transportation, and has become one of the important sources of industrial hydrogen. With the refinement and improvement of the hydrogen energy industry, methanol reforming hydrogen production technology has greater development potential in small-scale flexible hydrogen production scenarios.

[0003] Currently, China is the world's largest producer and consumer of methanol, with an annual production capacity exceeding 90 million tons, accounting for approximately 60% of global methanol production. This provides a solid industrial foundation for methanol reforming to produce hydrogen. Furthermore, methanol can serve as a stable carrier for hydrogen energy, enabling the safe, efficient, and low-cost transport of hydrogen from production to consumption, significantly reducing storage and transportation costs and enhancing the practical application and safety of hydrogen energy. As a crucial technological link in the hydrogen consumption process, methanol reforming technology helps solve the challenges in hydrogen production, storage, transportation, and refueling, providing a safe and efficient pathway for the practical application of hydrogen energy.

[0004] Methanol-to-hydrogen (MCH) power generation is an extended application of methanol-to-hydrogen production. It converts hydrogen obtained from methanol reforming into electricity via fuel cells, enabling on-demand hydrogen production and avoiding the need for large-scale hydrogen storage and long-distance transportation, thus simplifying the hydrogen energy supply chain. Furthermore, the carbon dioxide produced during methanol reforming can be centrally emitted, making it easy to capture and utilize, which helps reduce greenhouse gas emissions.

[0005] The main reactions occurring during methanol reforming for hydrogen production are as follows, with methanol reforming being the primary reaction and methanol cracking being a secondary reaction. The selectivity of methanol reforming is typically greater than 95%.

[0006] Methanol reforming: CH3OH(g) + H2O(g) → CO2(g) + 3H2(g) + 48.17 kJ / mol

[0007] Methanol cracking: CH3OH(g) → CO(g) + 2H2(g) + 89.3 kJ / mol

[0008] Based on the methanol reforming and methanol cracking reactions described above, the main products of the methanol reforming hydrogen production process are hydrogen and carbon dioxide. However, since carbon monoxide is present in the products, it needs to be removed through water-gas shift or methanation reactions. The specific details of the water-gas shift and methanation reactions are as follows:

[0009] Water-gas shift reaction: CO(g) + H₂O(g) → CO₂(g) + H₂(g) - 41.2 kJ / mol

[0010] Methanation: CO(g) + 3H₂(g) → CH₄(g) + H₂O(g) - 204.7 kJ / mol

[0011] From a material perspective, methanol reforming produces three molecules of hydrogen for every molecule of carbon dioxide emitted, making it a relatively efficient and low-carbon hydrogen production method. However, from an energy perspective, methanol reforming is a net endothermic process, requiring fuel combustion for energy. The combustion or production of fuels such as coal, methanol, or hydrogen emits additional carbon dioxide. Therefore, the current carbon dioxide emissions from methanol reforming processes far exceed their theoretical values, making it difficult to achieve low-carbon hydrogen production and power generation. Summary of the Invention

[0012] In view of the shortcomings of the prior art, the present invention provides a photothermal coupled methanol reforming hydrogen cogeneration system, which can realize efficient and low-carbon methanol hydrogen production and power generation.

[0013] The technical solution adopted by this invention to solve its technical problem is:

[0014] A solar-thermal coupled methanol reforming hydrogen-power cogeneration system includes a solar thermal unit, a thermal storage unit, a methanol reforming hydrogen production unit, a fuel cell unit, and a steam turbine power generation unit. The thermal storage unit is connected to the solar thermal unit, the methanol reforming hydrogen production unit, the fuel cell unit, and the steam turbine power generation unit, respectively. The fuel cell unit is connected to both the methanol reforming hydrogen production unit and the steam turbine power generation unit. The solar thermal unit stores the thermal energy from solar radiation in the thermal storage unit. The thermal storage unit supplies heat to the methanol reforming hydrogen production unit, enabling the methanol reforming reaction to occur in the methanol reforming hydrogen production unit and supplying the produced hydrogen to the fuel cell unit. The fuel cell unit converts the chemical energy of hydrogen and oxygen into electrical energy and discharges high-temperature steam. The thermal energy of the discharged high-temperature steam is used to directly supply heat to the steam turbine power generation unit or stored in the thermal storage unit and supplied to the steam turbine power generation unit through the thermal storage unit, enabling the steam turbine power generation unit to generate steam.

[0015] Further, the methanol reforming hydrogen production unit includes an evaporator, a first tubular reactor, a second tubular reactor, a first heat exchanger, a first condenser, and a pressure swing adsorption (PSA) separator. The outlet of the evaporator is connected to the inlet of the first tubular reactor, the outlet of the first tubular reactor is connected to the inlet of the second tubular reactor, the outlet of the second tubular reactor is connected to the inlet of the first heat exchanger, the outlet of the first heat exchanger is connected to the inlet of the first condenser, and the outlet of the first condenser is connected to the inlet of the PSA separator. The PSA separator... The hydrogen outlet of the reactor is connected to the hydrogen inlet of the fuel cell unit; the evaporator is used to evaporate the mixture of methanol and water; the first tubular reactor is used for methanol gas-water vapor reforming reaction; the second tubular reactor is used for methanation reaction; the first heat exchanger is used to reduce the gas at the outlet of the second tubular reactor to a certain temperature above room temperature; the first condenser is used to reduce the gas at the outlet of the first heat exchanger to room temperature and remove water; the pressure swing adsorption separator is used to separate the gas at the outlet of the first condenser to obtain high-purity hydrogen and recover carbon dioxide.

[0016] Furthermore, the solar thermal unit is a trough solar thermal unit, and includes a parabolic trough concentrator and a heat collection tube. The parabolic trough concentrator is used to focus sunlight onto the heat collection tube, and the low-temperature heat transfer oil in the heat storage unit is used to enter the heat collection tube and absorb the heat energy of solar radiation and convert it into high-temperature heat transfer oil.

[0017] Furthermore, the heat storage unit includes a high-temperature heat transfer oil tank, a low-temperature heat transfer oil tank, a high-temperature molten salt tank, a low-temperature molten salt tank, a high-temperature high-pressure water tank, and a low-temperature water tank;

[0018] The oil outlet of the low-temperature heat transfer oil tank is connected to the oil inlet of the photothermal unit, and the oil outlet of the photothermal unit is connected to the oil inlet of the high-temperature heat transfer oil tank.

[0019] The outlet of the high-temperature heat transfer oil tank is connected to the high-temperature inlet of the second heat exchanger, the low-temperature outlet of the second heat exchanger is connected to the inlet of the low-temperature heat transfer oil tank, the outlet of the first tubular reactor is connected to the low-temperature inlet of the second heat exchanger, and the high-temperature outlet of the second heat exchanger is connected to the inlet of the first tubular reactor.

[0020] The oil outlet of the high-temperature heat transfer oil tank is connected to the oil inlet of the second tubular reactor, and the oil outlet of the second tubular reactor is connected to the oil inlet of the high-temperature heat transfer oil tank.

[0021] The outlet of the low-temperature heat transfer oil tank is connected to the inlet of the first heat exchanger, and the outlet of the first heat exchanger is connected to the inlet of the high-temperature heat transfer oil tank.

[0022] The outlet of the low-temperature water tank is connected to the low-temperature inlet of the first condenser, and the high-temperature outlet of the first condenser is connected to the inlet of the high-temperature and high-pressure water tank.

[0023] The outlet of the high-temperature and high-pressure water tank is connected to the inlet of the evaporator, and the outlet of the evaporator is connected to the inlet of the low-temperature water tank.

[0024] The exhaust port of the fuel cell unit is connected to the inlet of the third heat exchanger, the outlet of the third heat exchanger is connected to the inlet of the fourth heat exchanger, the molten salt outlet of the low-temperature molten salt tank is connected to the molten salt inlet of the third heat exchanger, and the molten salt outlet of the third heat exchanger is connected to the molten salt inlet of the high-temperature molten salt tank.

[0025] The low-temperature outlet of the fourth heat exchanger is connected to the inlet of the water processor, the outlet of the water processor is connected to the inlet of the demineralized water tank, the outlet of the low-temperature water tank is connected to the low-temperature inlet of the fourth heat exchanger, and the high-temperature outlet of the fourth heat exchanger is connected to the inlet of the high-temperature and high-pressure water tank.

[0026] The molten salt outlet of the high-temperature molten salt tank is connected to the molten salt inlet of the fifth heat exchanger, the molten salt outlet of the fifth heat exchanger is connected to the molten salt inlet of the low-temperature molten salt tank, the oil outlet of the low-temperature heat transfer oil tank is connected to the oil inlet of the fifth heat exchanger, and the oil outlet of the fifth heat exchanger is connected to the oil inlet of the high-temperature heat transfer oil tank.

[0027] Furthermore, the steam turbine power generation unit includes a steam turbine, a generator, and a second condenser. The steam turbine is connected to the generator, and the exhaust port of the steam turbine is connected to the air inlet of the second condenser. The heat energy of the high-temperature steam discharged from the exhaust port of the fuel cell unit is used to heat the water discharged from the low-temperature outlet of the second condenser, or the heat energy stored in the heat storage unit is used to heat the water discharged from the low-temperature outlet of the second condenser.

[0028] Furthermore, the heat energy of the high-temperature water vapor discharged from the exhaust port of the fuel cell unit is used to heat the water discharged from the low-temperature outlet of the second condenser. Specifically, the exhaust port of the fuel cell unit is also connected to the high-temperature air inlet of the sixth heat exchanger, the low-temperature water outlet of the sixth heat exchanger is connected to the water inlet of the water processor, the low-temperature water inlet of the sixth heat exchanger is connected to the low-temperature water outlet of the second condenser, and when the water supply of the second condenser is insufficient, the low-temperature water inlet of the sixth heat exchanger is also connected to the water outlet of the demineralized water tank, and the high-temperature air outlet of the sixth heat exchanger is connected to the air inlet of the steam turbine.

[0029] Furthermore, the thermal energy stored in the heat storage unit is used to heat the water discharged from the low-temperature outlet of the second condenser. Specifically, the low-temperature outlet of the second condenser is connected to the low-temperature inlet of the seventh heat exchanger, and in the event of insufficient water supply from the second condenser, the low-temperature inlet of the seventh heat exchanger is also connected to the outlet of the demineralized water tank. The air outlet of the seventh heat exchanger is connected to the air inlet of the eighth heat exchanger, and the outlet of the high-temperature, high-pressure water tank is connected to the high-temperature inlet of the seventh heat exchanger. The low-temperature outlet of the heat exchanger is connected to the inlet of the low-temperature water tank; the oil outlet of the high-temperature heat transfer oil tank is connected to the oil inlet of the eighth heat exchanger, the oil outlet of the eighth heat exchanger is connected to the oil inlet of the low-temperature heat transfer oil tank, and the air outlet of the eighth heat exchanger is connected to the air inlet of the ninth heat exchanger; the molten salt outlet of the high-temperature molten salt tank is connected to the molten salt inlet of the ninth heat exchanger, the molten salt outlet of the ninth heat exchanger is connected to the molten salt inlet of the low-temperature molten salt tank, and the air outlet of the ninth heat exchanger is connected to the air inlet of the steam turbine.

[0030] Furthermore, the first heat exchanger is used to reduce the gas temperature at the outlet of the second tubular reactor to below 200°C.

[0031] Furthermore, the drain outlet of the first condenser is connected to the inlet of the low-temperature water tank.

[0032] Furthermore, the reaction temperature of the methanol gas-water vapor reforming reaction occurring in the first tubular reactor is less than or equal to 280°C, the reaction temperature of the methanation reaction occurring in the second tubular reactor is less than or equal to 380°C, the gas temperature at the outlet of the second tubular reactor is less than or equal to 400°C, the external heating temperature of the photothermal unit is 390-400°C, the high-temperature water vapor temperature discharged from the exhaust port of the fuel cell unit is 750-800°C, the high-temperature water vapor temperature at the outlet of the third heat exchanger is 300±5°C, the temperature of the heat transfer oil in the high-temperature heat transfer oil tank is greater than or equal to 380°C, the temperature of the heat transfer oil in the low-temperature heat transfer oil tank is less than or equal to 160°C, the temperature of the molten salt in the high-temperature molten salt tank is 580±5°C, the temperature of the molten salt in the low-temperature molten salt tank is 290±5°C, the temperature of the high-temperature high-pressure water in the high-temperature high-pressure water tank is 180±5°C, and the temperature of the methanol gas and water vapor mixture obtained through the evaporator is less than or equal to 140°C.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] The photothermal coupled methanol reforming hydrogen-power cogeneration system of this invention includes a photothermal unit, a thermal storage unit, a methanol reforming hydrogen production unit, a fuel cell unit, and a steam turbine power generation unit. The thermal storage unit is connected to the photothermal unit, the methanol reforming hydrogen production unit, the fuel cell unit, and the steam turbine power generation unit, respectively. The fuel cell unit is connected to the methanol reforming hydrogen production unit and the steam turbine power generation unit, respectively. First, the energy required for methanol reforming hydrogen production is directly provided by the thermal storage unit, which in turn is provided by the heat from the high-temperature steam discharged from the photothermal unit and the recovered fuel cell unit. Therefore, the need for fuel combustion heating is fundamentally eliminated, ensuring that the entire methanol reforming hydrogen production process emits only stoichiometric carbon dioxide, i.e., for every 1 mole of methanol consumed, 3 moles of hydrogen and 1 mole of carbon dioxide are produced, thereby minimizing carbon emissions. Second, due to the addition of the thermal storage unit, this system can operate without sunlight, achieving continuous hydrogen production and power generation. Furthermore, the methanol reforming hydrogen production unit, fuel cell unit, and steam turbine power generation unit can be operated independently or semi-independently through the thermal storage unit, thereby achieving more flexible and wide-range operation. For example, after hydrogen is extracted, the hydrogen intake of the fuel cell unit decreases, resulting in a drop in power generation. The thermal storage unit can then provide heat to generate more high-temperature and high-pressure steam, thereby increasing the output power of the steam turbine power generation unit and ensuring the stability of the overall power generation. Similarly, when it is necessary to adjust the power generation, the amount of hydrogen entering the fuel cell unit can be adjusted by changing the methanol feed rate, or the proportion of energy recovered from the fuel cell unit's exhaust gas to the thermal storage unit can be changed to alter the output power of the steam turbine power generation unit, thus achieving a significant range of power generation regulation. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the photothermal coupled methanol reforming hydrogen cogeneration system in this invention;

[0036] Figure 2 This is a schematic diagram showing the specific layout of the photothermal coupled methanol reforming hydrogen cogeneration system in this invention. Detailed Implementation

[0037] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0038] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0039] like Figure 1 As shown, a solar-thermal coupled methanol reforming hydrogen-power cogeneration system includes a solar-thermal unit, a thermal storage unit, a methanol reforming hydrogen production unit, a fuel cell unit, and a steam turbine power generation unit. The thermal storage unit is connected to the solar-thermal unit, the methanol reforming hydrogen production unit, the fuel cell unit, and the steam turbine power generation unit, respectively. The fuel cell unit is connected to the methanol reforming hydrogen production unit and the steam turbine power generation unit, respectively. The solar-thermal unit stores the thermal energy of solar radiation in the thermal storage unit. The thermal storage unit supplies heat to the methanol reforming hydrogen production unit, enabling the methanol reforming reaction to occur in the methanol reforming hydrogen production unit and supplying the produced hydrogen to the fuel cell unit. The fuel cell unit converts the chemical energy of hydrogen and oxygen into electrical energy and discharges high-temperature steam. The thermal energy of the discharged high-temperature steam is used to directly supply heat to the steam turbine power generation unit or stored in the thermal storage unit and supplied to the steam turbine power generation unit through the thermal storage unit, enabling the steam turbine power generation unit to generate steam.

[0040] First, the energy required for methanol reforming to produce hydrogen is directly provided by the thermal storage unit, which in turn is powered by the heat from the high-temperature water vapor emitted by the solar thermal unit and the recovered fuel cell unit. This fundamentally eliminates the need for fuel combustion heating, ensuring that the entire methanol reforming hydrogen production process emits only stoichiometric amounts of carbon dioxide – that is, for every 1 mole of methanol consumed, 3 moles of hydrogen and 1 mole of carbon dioxide are produced, thus minimizing carbon emissions. Second, due to the addition of the thermal storage unit, the system can operate even without sunlight, enabling continuous hydrogen production and power generation. Furthermore, the methanol reforming hydrogen production unit, fuel cell unit, and steam turbine power generation unit can be operated independently or semi-independently through the thermal storage unit, thereby achieving more flexible and wide-range operation. For example, after hydrogen is extracted, the hydrogen intake of the fuel cell unit decreases, resulting in a drop in power generation. The thermal storage unit can then provide heat to generate more high-temperature and high-pressure steam, thereby increasing the output power of the steam turbine power generation unit and ensuring the stability of the overall power generation. Similarly, when it is necessary to adjust the power generation, the amount of hydrogen entering the fuel cell unit can be adjusted by changing the methanol feed rate, or the proportion of energy recovered from the fuel cell unit's exhaust gas to the thermal storage unit can be changed to alter the output power of the steam turbine power generation unit, thus achieving a significant range of power generation regulation.

[0041] In one embodiment, such as Figure 2 As shown, the solar thermal unit is a trough solar thermal unit, which includes a parabolic trough concentrator and a heat collection tube. The parabolic trough concentrator is used to focus sunlight onto the heat collection tube. The low-temperature heat transfer oil in the heat storage unit is used to enter the heat collection tube and absorb the heat energy of solar radiation and convert it into high-temperature heat transfer oil.

[0042] In one embodiment, such as Figure 2 As shown, the methanol reforming hydrogen production unit includes an evaporator, a first tubular reactor, a second tubular reactor, a first heat exchanger, a first condenser, and a pressure swing adsorption separator. The outlet of the evaporator is connected to the inlet of the first tubular reactor, the outlet of the first tubular reactor is connected to the inlet of the second tubular reactor, the outlet of the second tubular reactor is connected to the inlet of the first heat exchanger, the outlet of the first heat exchanger is connected to the inlet of the first condenser, the outlet of the first condenser is connected to the inlet of the pressure swing adsorption separator, and the outlet of the first condenser is connected to the inlet of the low-temperature water tank. The hydrogen outlet of the pressure swing adsorption (PSA) separator is connected to the hydrogen inlet of the fuel cell unit. An evaporator evaporates the methanol-water mixture. A first tubular reactor is used for methanol gas-water vapor reforming, and a second tubular reactor is used for methanation. A first heat exchanger cools the gas from the outlet of the second tubular reactor to a temperature below ambient level. A first condenser cools the gas from the outlet of the first heat exchanger to ambient temperature and removes water. The PSA separator separates the gas from the outlet of the first condenser to obtain high-purity hydrogen and recover carbon dioxide. In this way, the carbon dioxide emitted from the methanol reforming hydrogen production unit is concentrated at the carbon dioxide outlet of the PSA separator, thus facilitating carbon dioxide capture.

[0043] Among them, such as Figure 2 As shown, the thermal storage unit includes a high-temperature thermal oil tank, a low-temperature thermal oil tank, a high-temperature molten salt tank, a low-temperature molten salt tank, a high-temperature high-pressure water tank, and a low-temperature water tank;

[0044] The oil outlet of the low-temperature heat transfer oil tank is connected to the oil inlet of the photothermal unit, and the oil outlet of the photothermal unit is connected to the oil inlet of the high-temperature heat transfer oil tank. Preferably, the oil outlet of the low-temperature heat transfer oil tank is connected to the oil inlet of the heat collector tube, and the oil outlet of the heat collector tube is connected to the oil inlet of the high-temperature heat transfer oil tank.

[0045] The outlet of the high-temperature heat transfer oil tank is connected to the high-temperature inlet of the second heat exchanger, the low-temperature outlet of the second heat exchanger is connected to the inlet of the low-temperature heat transfer oil tank, the outlet of the first tubular reactor is connected to the low-temperature inlet of the second heat exchanger, and the high-temperature outlet of the second heat exchanger is connected to the inlet of the first tubular reactor. In this way, the high-temperature heat transfer oil in the high-temperature heat transfer oil tank can heat the low-temperature heat transfer oil in the first tubular reactor in the second heat exchanger to provide the heat required for the methanol gas-water vapor reforming reaction to occur in the first tubular reactor.

[0046] The outlet of the high-temperature heat transfer oil tank is connected to the inlet of the second tubular reactor, and the outlet of the second tubular reactor is connected to the inlet of the high-temperature heat transfer oil tank. In this way, the high-temperature heat transfer oil in the high-temperature heat transfer oil tank can provide a stable reaction temperature for the methanation reaction that occurs in the second tubular reactor by entering and exiting the second tubular reactor.

[0047] The outlet of the low-temperature heat transfer oil tank is connected to the inlet of the first heat exchanger, and the outlet of the first heat exchanger is connected to the inlet of the high-temperature heat transfer oil tank. In this way, the gas at the outlet of the second tubular reactor can be cooled to a temperature below room temperature in the first heat exchanger, and the heat energy carried by the gas at the outlet of the second tubular reactor can be stored in the heat transfer oil.

[0048] The outlet of the low-temperature water tank is connected to the low-temperature inlet of the first condenser, and the high-temperature outlet of the first condenser is connected to the inlet of the high-temperature and high-pressure water tank. In this way, the gas at the outlet of the first heat exchanger can be cooled to room temperature and dehydrated in the first condenser, and the heat carried by the gas at the outlet of the first heat exchanger can be stored in the water. Specifically, the dehydration involves condensing the water vapor in the gas discharged from the outlet of the first heat exchanger into water in the first condenser and then introducing it into the low-temperature water tank.

[0049] The outlet of the high-temperature and high-pressure water tank is connected to the inlet of the evaporator, and the outlet of the evaporator is connected to the inlet of the low-temperature water tank. In this way, the high-temperature water in the high-temperature and high-pressure water tank can be used in the evaporator to evaporate the mixture of methanol and water.

[0050] The exhaust port of the fuel cell unit is connected to the inlet of the third heat exchanger, the outlet of the third heat exchanger is connected to the inlet of the fourth heat exchanger, the molten salt outlet of the low-temperature molten salt tank is connected to the molten salt inlet of the third heat exchanger, and the molten salt outlet of the third heat exchanger is connected to the molten salt inlet of the high-temperature molten salt tank. In this way, the high-temperature water vapor discharged from the exhaust port of the fuel cell unit can be used to heat the low-temperature molten salt in the third heat exchanger.

[0051] The low-temperature outlet of the fourth heat exchanger is connected to the inlet of the water processor, the outlet of the water processor is connected to the inlet of the demineralized water tank, the outlet of the low-temperature water tank is connected to the low-temperature inlet of the fourth heat exchanger, and the high-temperature outlet of the fourth heat exchanger is connected to the inlet of the high-temperature and high-pressure water tank. In this way, the high-temperature steam discharged from the outlet of the third heat exchanger can be used to heat the water in the fourth heat exchanger.

[0052] The molten salt outlet of the high-temperature molten salt tank is connected to the molten salt inlet of the fifth heat exchanger, the molten salt outlet of the fifth heat exchanger is connected to the molten salt inlet of the low-temperature molten salt tank, the oil outlet of the low-temperature heat transfer oil tank is connected to the oil inlet of the fifth heat exchanger, and the oil outlet of the fifth heat exchanger is connected to the oil inlet of the high-temperature heat transfer oil tank. In this way, the low-temperature heat transfer oil can be heated by the high-temperature molten salt in the fifth heat exchanger.

[0053] The thermal storage unit has three thermal storage sub-units with different heat grades, which can be graded for recovery and utilization of heat of different grades, thereby achieving higher energy utilization efficiency.

[0054] Preferably, such as Figure 2 As shown, the steam turbine power generation unit includes a steam turbine, a generator, and a second condenser. The steam turbine is connected to the generator, and the exhaust port of the steam turbine is connected to the inlet of the second condenser. The second condenser is used to cool the low-temperature steam discharged from the steam turbine. The thermal energy of the high-temperature steam discharged from the exhaust port of the fuel cell unit is used to heat the water discharged from the low-temperature outlet of the second condenser. If the water supply to the second condenser is insufficient and the operating conditions of the steam turbine are not met, the thermal energy of the high-temperature steam discharged from the exhaust port of the fuel cell unit is also used to heat the water discharged from the outlet of the demineralized water tank to obtain high-temperature, high-pressure steam, which is then fed into the steam turbine to drive the generator for power generation. Alternatively, the thermal energy stored in the thermal storage unit is used to heat the water discharged from the low-temperature outlet of the second condenser. If the water supply to the second condenser is insufficient and the operating conditions of the steam turbine are not met, the thermal energy stored in the thermal storage unit is also used to heat the water discharged from the outlet of the demineralized water tank to obtain high-temperature, high-pressure steam, which is then fed into the steam turbine to drive the generator for power generation. Both of these methods can drive the steam turbine power generation unit independently or jointly.

[0055] Preferably, the thermal energy of the high-temperature water vapor discharged from the exhaust port of the fuel cell unit is used to heat the water discharged from the low-temperature outlet of the second condenser, specifically: such as Figure 2As shown, the exhaust port of the fuel cell unit is also connected to the high-temperature air inlet of the sixth heat exchanger, the low-temperature water outlet of the sixth heat exchanger is connected to the water inlet of the water processor, the low-temperature water inlet of the sixth heat exchanger is connected to the low-temperature water outlet of the second condenser, and when the water supply to the second condenser is insufficient and the operating conditions of the steam turbine are not met, the low-temperature water inlet of the sixth heat exchanger is also connected to the water outlet of the demineralized water tank, and the high-temperature air outlet of the sixth heat exchanger is connected to the air inlet of the steam turbine. In this way, the high-temperature steam discharged from the exhaust port of the fuel cell unit can be directly used in the sixth heat exchanger to heat the water discharged from the low-temperature water outlet of the second condenser or the water discharged from the demineralized water tank, converting it into high-temperature, high-pressure steam, which is then fed into the steam turbine to drive the generator for power generation.

[0056] Preferably, the thermal energy stored in the thermal storage unit is used to heat the water discharged from the low-temperature outlet of the second condenser, specifically: such as Figure 2 As shown, the low-temperature water outlet of the second condenser is connected to the low-temperature water inlet of the seventh heat exchanger. When the water supply to the second condenser is insufficient and the operating conditions of the steam turbine are not met, the low-temperature water inlet of the seventh heat exchanger is also connected to the outlet of the demineralized water tank. The air outlet of the seventh heat exchanger is connected to the air inlet of the eighth heat exchanger. The outlet of the high-temperature, high-pressure water tank is connected to the high-temperature water inlet of the seventh heat exchanger, and the low-temperature water outlet of the seventh heat exchanger is connected to the inlet of the low-temperature water tank. The oil outlet of the high-temperature thermal oil tank is connected to the oil inlet of the eighth heat exchanger, and the oil outlet of the eighth heat exchanger is connected to the oil inlet of the low-temperature thermal oil tank. The air outlet of the eighth heat exchanger is connected to the air inlet of the ninth heat exchanger. The molten salt outlet of the high-temperature molten salt tank is connected to the molten salt inlet of the ninth heat exchanger, and the molten salt outlet of the ninth heat exchanger is connected to the molten salt inlet of the low-temperature molten salt tank. The air outlet of the ninth heat exchanger is connected to the air inlet of the steam turbine. In this way, high-temperature water can be used in the seventh heat exchanger to preheat the steam entering the eighth heat exchanger, high-temperature heat transfer oil can be used in the eighth heat exchanger to preheat the steam entering the ninth heat exchanger, and high-temperature molten salt can be used in the ninth heat exchanger to heat the steam entering it and turn it into high-temperature and high-pressure steam, which is then fed into a steam turbine to drive a generator to generate electricity.

[0057] The first heat exchanger is used to reduce the temperature of the gas at the outlet of the second tubular reactor to below 200°C.

[0058] The reaction temperature of the methanol gas-water vapor reforming reaction in the first tubular reactor is less than or equal to 280℃, the reaction temperature of the methanation reaction in the second tubular reactor is less than or equal to 380℃, the gas temperature at the outlet of the second tubular reactor is less than or equal to 400℃, the external heating temperature of the solar thermal unit can reach 390-400℃, the high-temperature water vapor temperature discharged from the exhaust port of the fuel cell unit is 750-800℃, the high-temperature water vapor temperature at the outlet of the third heat exchanger is 300±5℃, the temperature of the heat transfer oil in the high-temperature heat transfer oil tank is greater than or equal to 380℃, the temperature of the heat transfer oil in the low-temperature heat transfer oil tank is less than or equal to 160℃, the temperature of the molten salt in the high-temperature molten salt tank is 580±5℃, the temperature of the molten salt in the low-temperature molten salt tank is 290±5℃, the temperature of the high-temperature high-pressure water in the high-temperature high-pressure water tank is 180±5℃, and the temperature of the methanol gas and water vapor mixture obtained through the evaporator is less than or equal to 140℃.

[0059] The direct current generated by the fuel cell unit is converted into alternating current by an AC-DC converter and then transmitted externally.

[0060] In summary, this photothermal coupled methanol reforming hydrogen-power cogeneration system recovers thermal energy from solar radiation and high-temperature water vapor at the exhaust port of the fuel cell unit, and utilizes this thermal energy to provide the necessary heat for the methanol reforming reaction, thereby achieving continuous and stable hydrogen production and power generation. By comprehensively utilizing different heat transfer media, it achieves energy recovery of thermal energy of different grades and efficient cascade energy utilization. In addition, since it does not require fuel combustion to provide heat for the methanol reforming hydrogen production process, this invention can achieve efficient and low-carbon chemical hydrogen production and power generation.

[0061] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A photothermal coupled methanol reforming hydrogen-power cogeneration system, characterized in that: The system includes a solar thermal unit, a thermal storage unit, a methanol reforming hydrogen production unit, a fuel cell unit, and a steam turbine power generation unit. The thermal storage unit is connected to the solar thermal unit, the methanol reforming hydrogen production unit, the fuel cell unit, and the steam turbine power generation unit, respectively. The fuel cell unit is connected to both the methanol reforming hydrogen production unit and the steam turbine power generation unit. The solar thermal unit stores the heat energy from solar radiation in the thermal storage unit. The thermal storage unit supplies heat to the methanol reforming hydrogen production unit, enabling the methanol reforming reaction to occur in the methanol reforming hydrogen production unit and supplying the produced hydrogen to the fuel cell unit. The fuel cell unit converts the chemical energy of hydrogen and oxygen into electrical energy and discharges high-temperature steam. The heat energy of the discharged high-temperature steam is used to directly supply heat to the steam turbine power generation unit or stored in the thermal storage unit and supplied to the steam turbine power generation unit through the thermal storage unit, enabling the steam turbine power generation unit to generate steam. The methanol reforming hydrogen production unit includes an evaporator, a first tubular reactor, a second tubular reactor, a first heat exchanger, a first condenser, and a pressure swing adsorption (PSA) separator. The outlet of the evaporator is connected to the inlet of the first tubular reactor, the outlet of the first tubular reactor is connected to the inlet of the second tubular reactor, the outlet of the second tubular reactor is connected to the inlet of the first heat exchanger, the outlet of the first heat exchanger is connected to the inlet of the first condenser, and the outlet of the first condenser is connected to the inlet of the PSA separator. The hydrogen production unit of the PSA separator... The gas outlet is connected to the hydrogen inlet of the fuel cell unit; the evaporator is used to evaporate the mixture of methanol and water; the first tubular reactor is used for methanol gas-water vapor reforming reaction; the second tubular reactor is used for methanation reaction; the first heat exchanger is used to reduce the gas at the outlet of the second tubular reactor to a certain temperature above room temperature; the first condenser is used to reduce the gas at the outlet of the first heat exchanger to room temperature and remove water; the pressure swing adsorption separator is used to separate the gas at the outlet of the first condenser to obtain high-purity hydrogen and recover carbon dioxide. The heat storage unit includes a high-temperature heat transfer oil tank, a low-temperature heat transfer oil tank, a high-temperature molten salt tank, a low-temperature molten salt tank, a high-temperature high-pressure water tank, and a low-temperature water tank; The oil outlet of the low-temperature heat transfer oil tank is connected to the oil inlet of the photothermal unit, and the oil outlet of the photothermal unit is connected to the oil inlet of the high-temperature heat transfer oil tank. The outlet of the high-temperature heat transfer oil tank is connected to the high-temperature inlet of the second heat exchanger, the low-temperature outlet of the second heat exchanger is connected to the inlet of the low-temperature heat transfer oil tank, the outlet of the first tubular reactor is connected to the low-temperature inlet of the second heat exchanger, and the high-temperature outlet of the second heat exchanger is connected to the inlet of the first tubular reactor. The oil outlet of the high-temperature heat transfer oil tank is connected to the oil inlet of the second tubular reactor, and the oil outlet of the second tubular reactor is connected to the oil inlet of the high-temperature heat transfer oil tank. The outlet of the low-temperature heat transfer oil tank is connected to the inlet of the first heat exchanger, and the outlet of the first heat exchanger is connected to the inlet of the high-temperature heat transfer oil tank. The outlet of the low-temperature water tank is connected to the low-temperature inlet of the first condenser, and the high-temperature outlet of the first condenser is connected to the inlet of the high-temperature and high-pressure water tank. The outlet of the high-temperature and high-pressure water tank is connected to the inlet of the evaporator, and the outlet of the evaporator is connected to the inlet of the low-temperature water tank. The exhaust port of the fuel cell unit is connected to the inlet of the third heat exchanger, the outlet of the third heat exchanger is connected to the inlet of the fourth heat exchanger, the molten salt outlet of the low-temperature molten salt tank is connected to the molten salt inlet of the third heat exchanger, and the molten salt outlet of the third heat exchanger is connected to the molten salt inlet of the high-temperature molten salt tank. The low-temperature outlet of the fourth heat exchanger is connected to the inlet of the water processor, the outlet of the water processor is connected to the inlet of the demineralized water tank, the outlet of the low-temperature water tank is connected to the low-temperature inlet of the fourth heat exchanger, and the high-temperature outlet of the fourth heat exchanger is connected to the inlet of the high-temperature and high-pressure water tank. The molten salt outlet of the high-temperature molten salt tank is connected to the molten salt inlet of the fifth heat exchanger, the molten salt outlet of the fifth heat exchanger is connected to the molten salt inlet of the low-temperature molten salt tank, the oil outlet of the low-temperature heat transfer oil tank is connected to the oil inlet of the fifth heat exchanger, and the oil outlet of the fifth heat exchanger is connected to the oil inlet of the high-temperature heat transfer oil tank.

2. The photothermal coupled methanol reforming hydrogen-power cogeneration system according to claim 1, characterized in that: The solar thermal unit is a trough-type solar thermal unit, which includes a parabolic trough concentrator and a heat collection tube. The parabolic trough concentrator is used to focus sunlight onto the heat collection tube. The low-temperature heat transfer oil in the heat storage unit is used to enter the heat collection tube and absorb the heat energy of solar radiation and convert it into high-temperature heat transfer oil.

3. The photothermal coupled methanol reforming hydrogen-power cogeneration system according to claim 1, characterized in that: The steam turbine power generation unit includes a steam turbine, a generator, and a second condenser. The steam turbine is connected to the generator, and the exhaust port of the steam turbine is connected to the inlet of the second condenser. The heat energy of the high-temperature steam discharged from the exhaust port of the fuel cell unit is used to heat the water discharged from the low-temperature outlet of the second condenser, or the heat energy stored in the heat storage unit is used to heat the water discharged from the low-temperature outlet of the second condenser.

4. The photothermal coupled methanol reforming hydrogen-power cogeneration system according to claim 3, characterized in that, The heat energy of the high-temperature water vapor discharged from the exhaust port of the fuel cell unit is used to heat the water discharged from the low-temperature outlet of the second condenser. Specifically, the exhaust port of the fuel cell unit is also connected to the high-temperature air inlet of the sixth heat exchanger, the low-temperature water outlet of the sixth heat exchanger is connected to the water inlet of the water processor, the low-temperature water inlet of the sixth heat exchanger is connected to the low-temperature water outlet of the second condenser, and when the water supply of the second condenser is insufficient, the low-temperature water inlet of the sixth heat exchanger is also connected to the water outlet of the demineralized water tank, and the high-temperature air outlet of the sixth heat exchanger is connected to the air inlet of the steam turbine.

5. A photothermal coupled methanol reforming hydrogen cogeneration system according to claim 3, characterized in that, The thermal energy stored in the heat storage unit is used to heat the water discharged from the low-temperature outlet of the second condenser. Specifically: the low-temperature outlet of the second condenser is connected to the low-temperature inlet of the seventh heat exchanger, and in the event of insufficient water supply to the second condenser, the low-temperature inlet of the seventh heat exchanger is also connected to the outlet of the demineralized water tank; the air outlet of the seventh heat exchanger is connected to the air inlet of the eighth heat exchanger; the outlet of the high-temperature high-pressure water tank is connected to the high-temperature inlet of the seventh heat exchanger; the low-temperature outlet of the seventh heat exchanger is connected to the inlet of the low-temperature water tank; the oil outlet of the high-temperature thermal oil tank is connected to the oil inlet of the eighth heat exchanger; the oil outlet of the eighth heat exchanger is connected to the oil inlet of the low-temperature thermal oil tank; the air outlet of the eighth heat exchanger is connected to the air inlet of the ninth heat exchanger; the molten salt outlet of the high-temperature molten salt tank is connected to the molten salt inlet of the ninth heat exchanger; the molten salt outlet of the ninth heat exchanger is connected to the molten salt inlet of the low-temperature molten salt tank; and the air outlet of the ninth heat exchanger is connected to the air inlet of the steam turbine.

6. The photothermal coupled methanol reforming hydrogen-power cogeneration system according to claim 1, characterized in that: The first heat exchanger is used to reduce the temperature of the gas at the outlet of the second tubular reactor to below 200°C.

7. The photothermal coupled methanol reforming hydrogen-power cogeneration system according to claim 1, characterized in that: The drain outlet of the first condenser is connected to the inlet of the low-temperature water tank.

8. The photothermal coupled methanol reforming hydrogen-power cogeneration system according to claim 1, characterized in that: The reaction temperature of the methanol gas-water vapor reforming reaction occurring in the first tubular reactor is less than or equal to 280°C; the reaction temperature of the methanation reaction occurring in the second tubular reactor is less than or equal to 380°C; the gas temperature at the outlet of the second tubular reactor is less than or equal to 400°C; the external heating temperature of the photothermal unit is 390-400°C; the high-temperature water vapor temperature discharged from the exhaust port of the fuel cell unit is 750-800°C; the high-temperature water vapor temperature at the outlet of the third heat exchanger is 300±5°C; the temperature of the heat transfer oil in the high-temperature heat transfer oil tank is greater than or equal to 380°C; the temperature of the heat transfer oil in the low-temperature heat transfer oil tank is less than or equal to 160°C; the temperature of the molten salt in the high-temperature molten salt tank is 580±5°C; the temperature of the molten salt in the low-temperature molten salt tank is 290±5°C; the temperature of the high-temperature high-pressure water in the high-temperature high-pressure water tank is 180±5°C; and the temperature of the methanol gas and water vapor mixture obtained through the evaporator is less than or equal to 140°C.

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