An electro-hydrogen co-production system and method coupling near-isothermal compression with chemical energy

Abstract

The present invention provides an electric-hydrogen co-production system and method coupling near-isothermal compression with chemical energy. After air is compressed by a dual-tank near-isothermal compression module, the high-pressure air is stored. The preheated and heated high-pressure air is mixed with fuel for combustion expansion work. The exhaust gas after combustion expansion work heats water to generate steam. A part of methanol is uniformly mixed with steam and then undergoes a reforming reaction to generate hydrogen and carbon dioxide. Another part of methanol absorbs heat and cracks to generate hydrogen and carbon monoxide, and the carbon monoxide serves as the fuel for combustion expansion. After the exhaust gas after combustion expansion work heats water, the waste heat is used to preheat the high-pressure air, the carbon dioxide generated by the reforming reaction heats the high-pressure air, and the hydrogen generated by the reforming reaction and the cracking reaction further heats the high-pressure air. The low-grade compression heat generated during the near-isothermal compression process and contained in the high-pressure gas and the water in the water tank is fully utilized, avoiding the use of a methanol steam generator while preheating methanol and saving energy.

Description

Technical Field

[0001] The invention belongs to the technical field of energy storage, and particularly relates to an electric-hydrogen co-production system and method coupling near-isothermal compression with chemical energy. Background Art

[0002] Hydrogen has the characteristic of high combustion calorific value, which is 3 times that of gasoline, 3.9 times that of alcohol, and 4.5 times that of coke. The product of hydrogen combustion is water, which is the cleanest energy in the world. Therefore, hydrogen energy is regarded as the clean energy with the greatest development potential in the 21st century. Among them, methanol cracking to produce hydrogen and methanol steam reforming to produce hydrogen are two important hydrogen production methods. However, both of these two hydrogen production methods have the problem of high energy consumption. Especially when using electric energy for heating in the methanol preheating and evaporation stages, it will lead to the conversion of a large amount of high-grade heat sources into low-grade heat sources, which is not conducive to the economy of the system. Moreover, the products of the two hydrogen production methods still have a certain temperature. If not utilized, it will still cause a large amount of energy waste problems. In the process of compressing air in a double-tank near-isothermal compressed air energy storage system, due to the untimely heat exchange of the generated compression heat, the gas at the outlet of the water-air tank still has a certain temperature. And as the number of compressions increases, the water temperature in the water-air tank will rise. If this part of heat is not utilized, it will lead to a large amount of energy waste. In addition, to ensure the operation of the expander under stable conditions, high-pressure gas storage generally needs to be throttled to a certain pressure by a throttle valve and then enter the expander to do work, which will cause a large amount of pressure energy loss. And when releasing energy, the supplementary heat of high-pressure air will also consume a large amount of energy. Summary of the Invention

[0003] In order to solve the problems existing in the prior art, the invention provides an electric-hydrogen co-production system and method coupling near-isothermal compression with chemical energy. By coupling a double-tank near-isothermal compressed air energy storage with methanol cracking to produce hydrogen and methanol steam reforming to produce hydrogen, the low-grade compression heat generated in the near-isothermal compression process and contained in the high-pressure gas and the water in the water-air tank is fully utilized, avoiding the use of a methanol vapor generator while preheating methanol and saving energy. The invention uses the water that has absorbed heat in the water-air tank as the water source for steam, thus saving the energy consumption of the steam generator. The waste heat of the expander exhaust is first used to heat the steam generator and then enters the recuperator to heat the high-pressure air, realizing the cascade utilization of energy while fully utilizing the low-grade exhaust waste heat. At the same time, the products of methanol cracking and methanol reforming also enter the recuperator to heat the high-pressure air, further making full use of energy. In addition, the coupling of methanol cracking to produce hydrogen and methanol steam reforming to produce hydrogen can supply heat to the energy release section of the near-isothermal compressed air energy storage system while utilizing the water in the water-air tank, further improving the energy efficiency.

[0004] To achieve the above object, the technical solution adopted by the present invention is as follows: An electric-hydrogen co-production system coupling near-isothermal compression and chemical energy includes a dual-tank near-isothermal compression module, a heat exchanger, a gas storage chamber, a regenerator group, a mixer, a methanol steam reforming reactor, a methanol cracking reactor, and a combustion expansion unit connected in sequence; the regenerator group includes a first regenerator, a second regenerator, and a third regenerator connected in sequence, and the exhaust port of the combustion expansion unit is connected to the inlet of the steam generator; the outlet of the steam generator is connected to the first regenerator and the mixer; the mixer is provided with a methanol inlet, a steam inlet, and a mixed gas outlet, and the mixed gas outlet of the mixer is connected to the inlet of the methanol steam reforming reactor. The methanol inlets of the mixer and the methanol cracking reactor are connected to a methanol storage device, and the pipelines from the methanol storage device to the mixer and the methanol cracking reactor pass through the cold side of the heat exchanger; the hydrogen outlet of the methanol steam reforming reactor and the hydrogen outlet of the methanol cracking reactor are connected to the second regenerator and the hydrogen storage tank, the carbon dioxide outlet of the methanol steam reforming reactor is connected to the third regenerator, and the air outlet of the third regenerator is connected to the combustion expansion unit; the carbon monoxide outlet of the methanol cracking reactor is connected to the combustion expansion unit; the cold side inlet of the steam generator is connected to the outlet of the hot water storage tank.

[0005] The methanol storage device includes a first methanol tank, a methanol pump, and a second methanol tank connected in sequence. The hot side of the heat exchanger is arranged between the methanol pump and the second methanol tank, and the outlet of the second methanol tank is connected to the methanol inlets of the mixer and the methanol cracking reactor.

[0006] The combustion expansion unit includes a first combustion chamber, a first expander, a second combustion chamber, and a second expander connected in sequence. The inlet of the first combustion chamber is respectively connected to the carbon monoxide outlet of the methanol cracking reactor and the air outlet of the third regenerator; the second combustion chamber is connected to the carbon monoxide outlet of the methanol cracking reactor. The exhaust port of the second expander is connected to the hot side inlet of the steam generator, the hot side outlet of the steam generator is connected to the hot side of the first regenerator, the hot side outlet of the first regenerator is emptied or connected to a carbon dioxide recovery device, and the cold side of the first regenerator communicates with the outlet of the gas storage chamber.

[0007] A pressure reducing device is arranged between the outlet of the gas storage chamber and the inlet of the first regenerator. The pressure reducing device includes an automatic regulating nozzle and a power impeller. The automatic regulating nozzle and a power impeller are arranged in a housing in sequence along the medium flow direction. The fluid enters from the housing inlet, first passes through the automatic regulating nozzle, then drives the power impeller, and flows out from the housing outlet; a pressure sensor is arranged on the automatic regulating nozzle, and the power impeller is connected to the power rotating shaft in the mixer.

[0008] The mixer includes a power rotating shaft, an axial-flow impeller, a reflux baffle and corresponding gas channels. Among them, the power impeller is connected to the axial-flow impeller through the power rotating shaft, and the axial-flow impeller is divided into upper and lower parts; the power rotating shaft, the axial-flow impeller and the reflux baffle are all arranged in a sealed chamber. There are upper and lower parts of reflux baffles arranged outside the axial-flow impeller, and a fluid outlet is arranged between the upper and lower parts of the reflux baffles. Among them, the lower part of the reflux baffle and the outside of the fluid outlet are provided with an outer baffle, and the upper edge of the outer baffle is connected to the lower part of the upper part of the reflux baffle. The lower part of the reflux baffle, the fluid outlet and the outer baffle form a fluid channel, and the fluid channel communicates with the mixed gas outlet of the mixer; the water vapor inlet and the methanol inlet of the mixer are respectively opened at the top and the bottom, and the mixed gas outlet is opened at the upper part of the mixer.

[0009] The drain outlet of the double-tank near-isothermal compression module is sequentially connected to a water pump and a water vapor generator along the medium flow direction. The water pump is connected to the cold-side inlet of the water vapor generator, and the cold-side outlet of the water vapor generator is connected to the mixer.

[0010] The double-tank near-isothermal compression module includes a surface reservoir, a first water-gas tank, a variable-frequency water pump, a second water-gas tank and a hot water storage tank. The air inlets of the first water-gas tank and the second water-gas tank are connected, and the water inlets and outlets of the first water-gas tank and the second water-gas tank are interconnected. The water inlets of the first water-gas tank and the second water-gas tank are connected to the surface reservoir, and variable-frequency water pumps are arranged at the water inlets of the first water-gas tank and the second water-gas tank. The water outlets of the first water-gas tank and the second water-gas tank are connected to the hot water storage tank; a first water temperature sensor and a second water temperature sensor are respectively arranged on the first water-gas tank and the second water-gas tank. A first throttle valve, a fourth throttle valve, a second throttle valve and a third throttle valve are respectively arranged at the outlet of the surface reservoir, the inlet of the hot water storage tank, the inlet and outlet of the first water-gas tank and the inlet and outlet of the second water-gas tank.

[0011] Both the methanol cracking reactor and the methanol steam reforming reactor are connected to the solar photovoltaic panel and are reactors heated by electromagnetic induction internal heat sources; or the methanol cracking reactor and the methanol steam reforming reactor are heated by a solar thermal energy storage system. The solar thermal energy storage system uses molten salt as the heat storage medium. After the high-temperature molten salt enters the methanol cracking reactor and the methanol steam reforming reactor to release heat, it returns to the solar thermal energy storage system to absorb heat.

[0012] Based on the same concept, a method for co-producing electricity and hydrogen by coupling near-isothermal compression with chemical energy is also provided. After the air is compressed by the double-tank near-isothermal compression module, the high-pressure air is stored. The preheated and heated high-pressure air is mixed with fuel for combustion expansion work. The exhaust gas after combustion expansion work heats water to generate steam. A part of methanol is mixed evenly with steam and then undergoes a reforming reaction to generate hydrogen and carbon dioxide. Another part of methanol absorbs heat and then undergoes cracking to generate hydrogen and carbon monoxide. The carbon monoxide serves as fuel during combustion expansion. After the exhaust gas after combustion expansion work heats water, the waste heat is used to preheat the high-pressure air. The carbon dioxide generated by the reforming reaction further heats the high-pressure air. The hydrogen generated by the reforming reaction and the cracking reaction heats the high-pressure air again. Methanol absorbs the thermal energy generated by air compression before cracking and mixing. By changing the ratio of methanol vapor entering the methanol cracking reactor and the methanol steam reforming reactor, the hydrogen production and power generation of the system are changed, and the production of electric energy and hydrogen is controlled. By adjusting the near-isothermal compression ratio and expansion ratio, different grades of thermal energy are utilized.

[0013] Based on the system for co-producing electricity and hydrogen by coupling near-isothermal compression with chemical energy according to the present invention, the double-tank near-isothermal compression module repeatedly compresses air and releases heat in the heat exchanger to heat methanol. The high-pressure air is stored in the gas storage chamber. The high-pressure air is preheated and heated twice in sequence in the regenerator group. A part of the methanol after absorbing heat enters the mixer to be mixed with steam, and then enters the methanol steam reforming reactor for reforming reaction. Another part of the methanol enters the methanol cracking reactor for cracking reaction. The carbon dioxide generated by the reforming reaction enters the second regenerator to heat the high-pressure air. The hydrogen generated by the reforming reaction and the cracking reaction enters the third regenerator to heat the high-pressure air. The heated high-pressure air enters the combustion expansion unit. The carbon monoxide generated by the cracking reaction enters the combustion expansion unit as fuel. The exhaust gas of the combustion expansion unit enters the steam generator to heat water to generate steam, and then enters the first regenerator to preheat the high-pressure air.

[0014] Compared with the prior art, the present invention has at least the following beneficial effects:

[0015] The present invention couples near-isothermal compressed air energy storage with methanol cracking for hydrogen production and methanol steam reforming for hydrogen production, which not only makes full use of low-grade heat sources at all levels but also has the functions of energy storage and hydrogen production. By coupling double-tank near-isothermal compressed air energy storage with methanol cracking for hydrogen production and methanol steam reforming for hydrogen production, the low-grade compression heat generated during the near-isothermal compression process and contained in the high-pressure gas and the water in the water-gas tank is fully utilized, avoiding the use of a methanol vapor generator while preheating methanol and saving energy. The present invention uses the water that has absorbed heat in the water-gas tank as the water source for steam, thus saving the energy consumption of the steam generator. The waste heat of the expander exhaust is first used to heat the steam generator and then enters the recuperator to heat the high-pressure air, enabling the cascade utilization of energy while making full use of the low-grade exhaust waste heat. At the same time, the products of methanol cracking and methanol reforming also enter the recuperator to heat the high-pressure air, further making full use of energy. In addition, the coupling of methanol cracking for hydrogen production and methanol steam reforming for hydrogen production can supplement heat to the energy release section of the near-isothermal compressed air energy storage system while utilizing the water in the water-gas tank, further improving the energy efficiency.

[0016] Further, the exhaust of the last stage of the expander is used to provide heat for the steam generator, which not only makes full use of the low-grade exhaust waste heat but also generates steam. The exhaust after providing heat for the steam generator further heats the high-pressure air, realizing the cascade utilization of energy and being beneficial to improving the efficiency of the system.

[0017] Further, the products of the methanol steam reforming reactor and the methanol cracking reactor are used to further heat the high-pressure air, thereby saving the demand for carbon monoxide in the combustion chamber and reducing the heat consumption of the compressed air energy storage system.

[0018] Further, a pressure reducing device is combined with a mixer. The high-pressure gas is depressurized and accelerated through an automatic regulating nozzle to keep the inlet pressure of the first-stage expander constant, which is beneficial to the stable operation of the system. Moreover, the accelerated high-pressure gas flow is used to drive the power impeller to rotate, converting the kinetic energy of the gas into the mechanical energy of the axial-flow impeller, further accelerating the mixing of methanol vapor and steam in the mixer and being beneficial to the progress of the methanol steam reforming reaction.

[0019] Further, both the methanol cracking reactor and the methanol steam reforming reactor are heated by means of electromagnetic induction internal heat sources. The electric energy is provided by solar photovoltaic panels or a solar thermal energy storage system is used to provide heat sources, reducing carbon emissions.

[0020] Based on the electro-hydrogen co-production method of the present invention, the present invention uses near-isothermal compression heat to preheat methanol and generate methanol vapor, avoiding the investment in a methanol vapor generator. At the same time, the low-grade compression heat is utilized, and the conversion of high-grade electrical energy into low-grade thermal energy caused by the use of an electric heater is also avoided. The water in the water-air tank after compressing air multiple times is used as the water source of the steam generator, which can make full use of the heat absorption of water in the water-air tank and further improve the system efficiency. The air of the combustion-expansion unit is preheated and heated to improve the unit efficiency. At the same time, the exhaust gas of the combustion-expansion unit is used to heat water. After generating steam, the high-pressure air is preheated to make full use of the thermal energy. It is also possible to control the hydrogen production and power generation of the system by adjusting the ratio of methanol vapor entering the methanol cracking reactor and the methanol steam reforming reactor, so as to control the production of electrical energy and hydrogen, and obtain a solution suitable for different needs, thereby enhancing the flexibility of the system. It is also possible to obtain the optimal energy utilization solution by adjusting parameters such as the near-isothermal compression ratio and the expander expansion ratio, and achieve the full utilization of every low-grade heat source. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is an electro-hydrogen co-production system coupling near-isothermal compression and chemical energy according to the present invention.

[0022] Figure 2 This is a schematic diagram of the pressure-reducing device and the mixer in the present invention.

[0023] Figure 3 This is a schematic diagram of the regenerator group in the present invention.

[0024] In the figure: 1, surface reservoir; 2, first throttle valve; 3, second throttle valve; 4, third throttle valve; 5, first water-air tank; 6, second water-air tank; 7, variable-frequency water pump; 8, first water temperature sensor; 9, second water temperature sensor; 10, fourth throttle valve; 11, hot water storage tank; 12, water pump; 13, steam generator; 14, heat exchanger; 15, gas storage chamber; 16, pressure-reducing device; 17, regenerator group; 18, first combustion chamber; 19, first expander; 20, second combustion chamber; 21, second expander; 22, first methanol tank; 23, methanol pump; 24, second methanol tank; 25, fifth throttle valve; 26, mixer; 27, methanol steam reforming reactor; 28, sixth throttle valve; 29, methanol cracking reactor; 30, seventh throttle valve; 31, eighth throttle valve; 32, hydrogen storage tank; 33, photovoltaic panel; 161, automatic adjustment nozzle; 162, pressure sensor; 163, power impeller; 261, power rotating shaft; 262, axial-flow impeller; 263, reflux baffle; 171, first regenerator; 172, second regenerator; 173, third regenerator. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] The present invention will be elaborated in detail below in combination with specific embodiments and the accompanying drawings.

[0026] The present invention couples double-tank near-isothermal compressed air energy storage with methanol cracking hydrogen production and methanol steam reforming hydrogen production, fully utilizes the low-grade compression heat generated during the near-isothermal compression process and contained in the high-pressure gas and the water in the water-gas tank, avoids the use of a methanol vapor generator, preheats methanol at the same time, and saves energy.

[0027] As Figure 1 shown, an electric-hydrogen co-production system coupling near-isothermal compression with chemical energy provided by the present invention includes a near-isothermal compressed air energy storage unit, a methanol cracking hydrogen production unit, and a methanol steam reforming hydrogen production unit;

[0028] Specifically, it includes a surface reservoir 1, a first throttle valve 2, a second throttle valve 3, a third throttle valve 4, a first water-gas tank 5, a second water-gas tank 6, a variable-frequency water pump 7, a first water temperature sensor 8, a second water temperature sensor 9, a fourth throttle valve 10, a hot water storage tank 11, a water pump 12, a steam generator 13, a heat exchanger 14, a gas storage chamber 15, a pressure reduction device 16, a regenerator group 17, a first combustion chamber 18, a first expander 19, a second combustion chamber 20, a second expander 21, a first methanol tank 22, a methanol pump 23, a second methanol tank 24, a fifth throttle valve 25, a mixer 26, a methanol steam reforming reactor 27, a sixth throttle valve 28, a methanol cracking reactor 29, a seventh throttle valve 30, an eighth throttle valve 31, a hydrogen storage tank 32, a photovoltaic panel 33, an automatic adjustment nozzle 161, a pressure sensor 162, a power impeller 163, a power rotating shaft 261, an axial-flow impeller 262, a reflux baffle 263, a first regenerator 171, a second regenerator 172, and a third regenerator 173.

[0029] The near-isothermal compressed air energy storage unit includes a double-tank near-isothermal compression module, a heat exchanger 14, a gas storage chamber 15, a pressure reduction device 16, a regenerator group 17, and an energy release module connected in sequence; the methanol cracking hydrogen production unit includes a first methanol tank 22, a methanol pump 23, a heat exchanger 14, a second methanol tank 24, and a methanol cracking reactor 29 connected in sequence, and a sixth throttle valve 28 is arranged on the pipeline connecting the second methanol tank 24 and the methanol cracking reactor 29; the methanol steam reforming hydrogen production unit includes a water pump 12, a steam generator 13, a mixer 26, a methanol steam reforming reactor 27, a regenerator group 17, and a hydrogen storage tank 32 connected in sequence, and the hydrogen outlet of the methanol steam reforming reactor 27 and the hydrogen outlet of the methanol cracking reactor 29 are connected to the second regenerator 172 in the regenerator group 17.

[0030] The combustion and expansion unit serves as an energy release module. The energy release module includes a first combustion chamber 18, a first expander 19, a second combustion chamber 20, and a second expander 21 connected in sequence. The inlet of the first combustion chamber 18 is respectively connected to the carbon monoxide outlet of the methanol cracking reactor 29 and the air outlet of the regenerator group 17. The second combustion chamber 20 is connected to the carbon monoxide outlet of the methanol cracking reactor 29. The exhaust port of the second expander 21 is connected to the hot-side inlet of the steam generator 13. The cold-side inlet of the steam generator 13 is connected to the hot water storage tank 11. The cold-side outlet of the steam generator 13 is connected to the steam inlet of the mixer 26. The hot-side outlet of the steam generator 13 is connected to the regenerator group 17.

[0031] The double-tank near-isothermal compression module includes a surface water storage tank 1, a first water-gas tank 5, a variable-frequency water pump 7, a second water-gas tank 6, and a hot water storage tank 11. The inlets of the first water-gas tank 5 and the second water-gas tank 6 are connected. The water inlets and outlets of the first water-gas tank 5 and the second water-gas tank 6 are interconnected. The inlets of the first water-gas tank 5 and the second water-gas tank 6 are connected to the surface water storage tank 1. A variable-frequency water pump 7 is provided at the inlets of the first water-gas tank 5 and the second water-gas tank 6. The outlets of the first water-gas tank 5 and the second water-gas tank 6 are connected to the hot water storage tank 11. A first water temperature sensor 8 and a second water temperature sensor 9 are respectively provided on the first water-gas tank 5 and the second water-gas tank 6. A first throttle valve 2, a fourth throttle valve 10, a second throttle valve 3, and a third throttle valve 4 are respectively provided at the outlet of the surface water storage tank 1, the inlet of the hot water storage tank 11, the inlet and outlet of the first water-gas tank 5, and the inlet and outlet of the second water-gas tank 6.

[0032] The pressure reduction device 16 includes an automatic regulating nozzle 161 and a power impeller 163. The automatic regulating nozzle 161 and a power impeller 163 are sequentially arranged along the medium flow direction in a housing. The fluid enters from the housing inlet, first passes through the automatic regulating nozzle 161, then drives the power impeller 163, and flows out from the housing outlet. A pressure sensor 162 is provided on the automatic regulating nozzle.

[0033] Reference Figure 3 , the regenerator group 17 includes a first regenerator 171, a second regenerator 172, and a third regenerator 173 connected in sequence.

[0034] The mixer 26 includes a power rotating shaft 261, an axial-flow impeller 262, a reflux baffle 263 and corresponding gas channels. Among them, the power impeller 163 is connected to the axial-flow impeller 262 through the power rotating shaft 261. The axial-flow impeller 262 is divided into upper and lower parts, and the gas flow directions are opposite during operation. The power rotating shaft 261, the axial-flow impeller 262 and the reflux baffle 263 are all arranged in a sealed chamber. Upper and lower parts of reflux baffles are arranged outside the axial-flow impeller 262, and a fluid outlet is arranged between the upper and lower parts of the reflux baffles. Among them, the lower part of the reflux baffle and the outside of the fluid outlet are provided with an outer baffle, and the upper edge of the outer baffle is connected to the lower part of the upper part of the reflux baffle. The lower part of the reflux baffle, the fluid outlet and the outer baffle form a fluid channel, and the fluid channel communicates with the outlet of the mixer 26. The upper and lower parts of the fluid flow together towards the fluid channel under the action of the two parts of the axial-flow impeller 262 with opposite turning directions, making the mixing more uniform.

[0035] The methanol cracking reactor 29 and the methanol steam reforming reactor 27 are both connected to the solar photovoltaic panel 33, and both are reactors heated by an electromagnetic induction internal heat source.

[0036] The steam generator 13 is connected to the exhaust port of the second expander 21. The hydrogen outlets of the methanol cracking reactor 29 and the methanol steam reforming reactor 27 are both connected to the second recuperator 172. The carbon dioxide outlet of the methanol steam reforming reactor 27 is connected to the third recuperator 173. The carbon monoxide outlet of the methanol cracking reactor 29 is respectively connected to the first combustion chamber 18 and the second combustion chamber 20 through the seventh throttle valve 30 and the eighth throttle valve 31. The second methanol tank 24 is connected to the mixer 26 through a throttle valve. The steam generator 13 is connected to the first recuperator 171.

[0037] The first water-gas tank 5, the second water-gas tank 6, the hot water storage pool 11, the mixer 26 and the second methanol tank 24 are all made of materials with good heat preservation performance, or an insulating layer is arranged outside them.

[0038] All throttle valves in the present invention adopt automatic control valves.

[0039] Based on the near-isothermal compression coupled with chemical energy electric hydrogen co-production system and method described in the present invention, it is as follows:

[0040] During energy storage, air is compressed by the dual-tank compression module and then enters the heat exchanger 14. After releasing heat in the heat exchanger 14, it enters the gas storage chamber 15. Under the action of the variable-frequency water pump 7, the water in the water-gas tank repeatedly compresses the air. As the number of compressions increases, the water temperature gradually rises. When the set temperature is reached, the throttle valve at the inlet and outlet of one of the water-gas tanks opens, the throttle valve at the inlet and outlet of the other water-gas tank closes, and the throttle valve at the inlet of the hot water storage tank 11 opens. The hot water enters the hot water storage tank 11 under the action of the variable-frequency water pump 7. After the hot water completely enters the hot water storage tank 11, the fourth throttle valve 10 at the inlet of the hot water storage tank 11 closes, and the first throttle valve 2 at the outlet of the surface water storage tank 1 opens. The normal-temperature water in the surface water storage tank 1 enters the water-gas tank under the action of the variable-frequency water pump 7. When the water volume reaches the predetermined water level, the first throttle valve 2 at the outlet of the surface water storage tank 1 closes, and the second throttle valve 3 and the third throttle valve 4 at the inlets and outlets of the two water-gas tanks both open to perform the next gas compression cycle. At the same time, the liquid methanol in the first methanol tank 22 enters the heat exchanger 14 under the action of the methanol pump 23, and after absorbing heat in the heat exchanger 14, it becomes high-temperature methanol vapor and enters the second methanol tank 24 for storage.

[0041] During energy release, the high-pressure gas in the gas storage chamber 15 enters the pressure reduction device 16 to adjust the pressure and then enters the regenerator group 17. After absorbing heat in the regenerator group 17, it enters the first combustion chamber 18, is reheated in the first combustion chamber 18, enters the first expander 19, releases energy by doing work, enters the second combustion chamber 20, is reheated, enters the second expander 21 to release energy by doing work, and then the tail exhaust gas with waste heat enters the steam generator 13 to supply heat to it. According to the second law of thermodynamics, there is still waste heat in the tail exhaust gas after supplying heat to the steam generator 13. Therefore, the tail exhaust gas after supplying heat to the steam generator 13 enters the regenerator group 17 to supply heat and then is discharged; a part of the methanol vapor in the second methanol tank 24 enters the methanol cracking reactor 29 through the sixth throttle valve 28, fully reacts in the methanol cracking reactor 29, and the reaction product hydrogen enters the hydrogen storage tank 32 after releasing heat in the regenerator group 17. The reaction product carbon monoxide enters the first combustion chamber 18 and the second combustion chamber 20 through the seventh throttle valve 30 and the eighth throttle valve 31 respectively to participate in combustion and supply heat to the high-pressure air; another part of the methanol enters the mixer 26 through the fifth throttle valve 25. At the same time, the water in the hot water storage tank 11 enters the steam generator 13 under the action of the water pump 12, becomes steam after fully absorbing heat, and enters the mixer 26. The methanol vapor and steam are fully mixed and then enter the methanol steam reforming reactor 27. The methanol vapor and steam fully react in the methanol steam reforming reactor 27. The reaction product carbon dioxide enters the regenerator group 17 to release heat and then is discharged or recycled. The reaction product hydrogen is mixed with the hydrogen generated by methanol cracking and then enters the hydrogen storage tank 32.

[0042] A carbon dioxide gas tank is provided at the carbon dioxide outlet of the regenerator group 17.

[0043] ReferenceFigure 2 After high-pressure air enters the pressure-reducing device 16, it passes through the automatic regulating nozzle 161 to reduce pressure and increase speed, forming a high-speed air flow that impacts the power impeller 163, further reducing the pressure. The pressure sensor 162 can sense the air flow pressure at the outlet of the pressure-reducing device 16. Through negative feedback regulation, the throat flow area and outlet area of the automatic regulating nozzle 161 are automatically adjusted to always maintain a constant air flow pressure at the outlet of the pressure-reducing device 16. At the same time, the power impeller 163 drives the axial-flow impeller 262 to rotate through the power rotating shaft 261. The axial-flow impeller is composed of upper and lower parts, and the blade shapes are arranged in opposite directions, that is, the suction directions are opposite. The water vapor and methanol vapor are respectively driven by the upper and lower parts of the axial-flow impeller 262 to accelerate and approach the middle of the mixer 26. The two air flows are accelerated and mixed under the action of high-speed impact. According to the principle of conservation of momentum, the speed of the two air flows decreases after mixing and spreads around, and then enters the mixed air flow channel. Under the action of the return baffle 263, the mixed air flow flows in the same direction in the mixed air flow channel, and further mixes in the mixed air flow channel and then enters the methanol steam reforming reactor 27.

[0044] Reference Figure 1 and Figure 3 After the exhaust gas heated by the water vapor generator 13 passes through the first regenerator 171 of the regenerator group 17, it preliminarily heats the high-pressure air from the gas storage chamber 15. The hydrogen generated by the methanol cracking reactor 29 and the methanol steam reforming reactor 27 passes through the second regenerator 172 of the regenerator group 17 to heat the high-pressure air again. The carbon dioxide generated by the methanol steam reforming reactor 27 passes through the third regenerator 173 of the regenerator group 17 to further heat the high-pressure air.

[0045] The main chemical reaction occurring in the methanol steam reforming reactor 27 is:

[0046] CH 3 OH(g)+H 2 O(g)→CO 2 (g)+3H 2 (g)

[0047] The main chemical reaction generated by the methanol cracking reactor 29 is:

[0048] CH 3 OH(g)→CO(g)+2H 2 (g)

[0049] The present invention can adjust the proportion of methanol vapor entering the two reactors, thereby changing the hydrogen production and power generation of the system, and obtaining a suitable solution for different needs; it can also obtain the optimal solution for energy utilization by adjusting parameters such as the near-isothermal compression ratio and the expansion ratio of the expander, so as to make full use of every low-grade heat source.

[0050] Both the methanol cracking reactor 29 and the methanol steam reforming reactor 27 can be heated by means of electromagnetic induction internal heat source, and the electric energy is provided by the solar photovoltaic panel 33.

[0051] The methanol cracking reactor 29 and the methanol steam reforming reactor 27 can also be heated by the solar thermal energy storage system. The solar thermal energy storage system uses molten salt as the heat storage medium. After the high-temperature molten salt enters the methanol cracking reactor 29 and the methanol steam reforming reactor 27 to release heat, it returns to the solar thermal energy storage system to absorb heat.

[0052] In summary, by coupling the double-tank near-isothermal compressed air energy storage with methanol cracking hydrogen production and methanol steam reforming hydrogen production, the present invention makes full use of the low-grade compression heat generated during the near-isothermal compression process and contained in the high-pressure gas and the water in the water and gas tank, avoids the use of the methanol vapor generator while preheating methanol and saving energy. The present invention uses the water that has absorbed heat in the water and gas tank as the water source for steam, thereby saving the energy consumption of the steam generator. The exhaust waste heat of the expander is first used to heat the steam generator and then enters the recuperator to heat the high-pressure air, realizing the cascade utilization of energy while making full use of the low-grade exhaust waste heat. At the same time, the products of methanol cracking and methanol reforming also enter the recuperator to heat the high-pressure air, further making full use of energy. In addition, the coupling of methanol cracking hydrogen production and methanol steam reforming hydrogen production can supplement heat for the energy release section of the near-isothermal compressed air energy storage system while utilizing the water in the water and gas tank, further improving the energy efficiency.

Claims

1. An electro-hydrogen co-production system coupling near-isothermal compression with chemical energy, characterized in that, it includes a double-tank near-isothermal compression module, the hot side of a heat exchanger (14), a gas storage chamber (15), a regenerator group (17), a mixer (26), a methanol steam reforming reactor (27), a methanol cracking reactor (29), and a combustion expansion unit connected in sequence; the regenerator group (17) includes a first regenerator (171), a second regenerator (172), and a third regenerator (173) connected in sequence, and the exhaust port of the combustion expansion unit is connected to the inlet of a steam generator (13); the outlet of the steam generator (13) is connected to the first regenerator (171) and the mixer (26); the mixer (26) is provided with a methanol inlet, a steam inlet, and a mixed gas outlet, the mixed gas outlet of the mixer (26) is connected to the inlet of the methanol steam reforming reactor (27), the methanol inlets of the mixer (26) and the methanol cracking reactor (29) are connected to a methanol storage device, and the pipelines from the methanol storage device to the mixer (26) and the methanol cracking reactor (29) pass through the cold side of the heat exchanger (14); the hydrogen outlet of the methanol steam reforming reactor (27) and the hydrogen outlet of the methanol cracking reactor (29) are connected to the second regenerator (172) and a hydrogen storage tank (32), the carbon dioxide outlet of the methanol steam reforming reactor (27) is connected to the third regenerator (173), and the air outlet of the third regenerator (173) is connected to the combustion expansion unit; the carbon monoxide outlet of the methanol cracking reactor (29) is connected to the combustion expansion unit; the water outlet of the double-tank near-isothermal compression module is connected to the inlet of a hot water storage tank (11), and the cold side inlet of the steam generator (13) is connected to the outlet of the hot water storage tank (11); the methanol storage device includes a first methanol tank (22), a methanol pump (23), and a second methanol tank (24) connected in sequence, the cold side of the heat exchanger (14) is arranged between the methanol pump (23) and the second methanol tank (24), and the outlet of the second methanol tank (24) is connected to the methanol inlets of the mixer (26) and the methanol cracking reactor (29).

2. The electro-hydrogen co-production system coupling near-isothermal compression with chemical energy according to claim 1, characterized in that, the combustion expansion unit includes a first combustion chamber (18), a first expander (19), a second combustion chamber (20), and a second expander (21) connected in sequence, the inlet of the first combustion chamber (18) is respectively connected to the carbon monoxide outlet of the methanol cracking reactor (29) and the air outlet of the third regenerator (173); the second combustion chamber (20) is connected to the carbon monoxide outlet of the methanol cracking reactor (29), the exhaust port of the second expander (21) is connected to the hot side inlet of the steam generator (13), the hot side outlet of the steam generator (13) is connected to the hot side of the first regenerator (171), the hot side outlet of the first regenerator (171) is emptied or connected to a carbon dioxide recovery device, and the cold side of the first regenerator (171) communicates with the outlet of the gas storage chamber (15).

3. The electro-hydrogen co-production system coupling near-isothermal compression with chemical energy according to claim 1, characterized in that, A pressure reducing device (16) is provided between the outlet of the gas storage chamber (15) and the inlet of the first regenerator (171). The pressure reducing device (16) includes an automatic regulating nozzle (161) and a power impeller (163). The automatic regulating nozzle (161) and a power impeller (163) are arranged in sequence along the medium flow direction in a housing. The fluid enters from the housing inlet, first passes through the automatic regulating nozzle (161), then drives the power impeller (163), and flows out from the housing outlet. A pressure sensor (162) is provided on the automatic regulating nozzle, and the power impeller (163) is connected to the power rotating shaft (261) in the mixer (26).

4. The near-isothermal compression coupled with chemical energy electro-hydrogen co-production system according to claim 1, characterized in that, The mixer (26) includes a power rotating shaft (261), an axial flow impeller (262), a return baffle (263) and corresponding gas channels. Among them, the power impeller (163) is connected to the axial flow impeller (262) through the power rotating shaft (261), and the axial flow impeller (262) is divided into upper and lower parts; the power rotating shaft (261), the axial flow impeller (262), and the return baffle (263) are all arranged in a sealed chamber. Upper and lower return baffles are arranged outside the axial flow impeller (262), and a fluid outlet is arranged between the upper and lower return baffles. Among them, an outer baffle is arranged outside the lower return baffle and the fluid outlet, and the upper edge of the outer baffle is connected to the lower part of the upper return baffle. The lower return baffle, the fluid outlet, and the outer baffle form a fluid channel, and the fluid channel communicates with the mixed gas outlet of the mixer (26); the steam inlet and the methanol inlet of the mixer (26) are respectively opened at the top and the bottom, and the mixed gas outlet is opened at the upper part of the mixer (26).

5. The near-isothermal compression coupled with chemical energy electro-hydrogen co-production system according to claim 1, characterized in that, The drain outlet of the double-tank near-isothermal compression module is sequentially connected to a water pump (12) and a steam generator (13) along the medium flow direction. The water pump (12) is connected to the cold-side inlet of the steam generator (13), and the cold-side outlet of the steam generator (13) is connected to the mixer (26).

6. The near-isothermal compression coupled with chemical energy electro-hydrogen co-production system according to claim 1, characterized in that, The double-tank near-isothermal compression module includes a surface reservoir (1), a first water-gas tank (5), a variable-frequency water pump (7), and a second water-gas tank (6). The inlets of the first water-gas tank (5) and the second water-gas tank (6) are connected. The water inlets and outlets of the first water-gas tank (5) and the second water-gas tank (6) are interconnected. The inlets of the first water-gas tank (5) and the second water-gas tank (6) are connected to the surface reservoir (1), and variable-frequency water pumps (7) are provided at the inlets of the first water-gas tank (5) and the second water-gas tank (6). The outlets of the first water-gas tank (5) and the second water-gas tank (6) are used as the outlets of the double-tank near-isothermal compression module and are connected to a hot water storage tank (11). A first water temperature sensor (8) and a second water temperature sensor (9) are respectively provided on the first water-gas tank (5) and the second water-gas tank (6). A first throttle valve (2), a fourth throttle valve (10), a second throttle valve (3), and a third throttle valve (4) are respectively provided at the outlet of the surface reservoir (1), the inlet of the hot water storage tank (11), the inlet and outlet of the first water-gas tank (5), and the inlet and outlet of the second water-gas tank (6).

7. The near-isothermal compression coupled with chemical energy for power and hydrogen co-production system according to claim 1, characterized in that, both the methanol cracking reactor (29) and the methanol steam reforming reactor (27) are connected to the solar photovoltaic panel (33), and both are reactors heated by an electromagnetic induction internal heat source; or the methanol cracking reactor (29) and the methanol steam reforming reactor (27) are heated by a solar thermal energy storage system, and the solar thermal energy storage system uses molten salt as the heat storage medium. After the high-temperature molten salt enters the methanol cracking reactor (29) and the methanol steam reforming reactor (27) to release heat, it returns to the solar thermal energy storage system to absorb heat.

8. A method for power and hydrogen co-production by near-isothermal compression coupled with chemical energy, characterized in that, Based on the near-isothermal compression coupled with chemical energy for power and hydrogen co-production system according to any one of claims 1-7, after the air is compressed by the double-tank near-isothermal compression module, the high-pressure air is stored. The preheated and heated high-pressure air is mixed with fuel for combustion expansion work. The exhaust gas after combustion expansion work heats water to generate steam. A part of methanol is mixed evenly with steam for reforming reaction to generate hydrogen and carbon dioxide, and another part of methanol absorbs heat and cracks to generate hydrogen and carbon monoxide. The carbon monoxide is used as fuel during combustion expansion. After the exhaust gas after combustion expansion work heats water, the waste heat is used to preheat the high-pressure air. The carbon dioxide generated by the reforming reaction further heats the high-pressure air. The hydrogen generated by the reforming reaction and the cracking reaction heats the high-pressure air again. Methanol absorbs the thermal energy generated by air compression before cracking and mixing. By changing the methanol vapor ratio entering the methanol cracking reactor and the methanol steam reforming reactor, the hydrogen production and power generation of the system are changed, and the production of electric energy and hydrogen is controlled. By adjusting the near-isothermal compression pressure ratio and expansion ratio, different grades of thermal energy are utilized.

9. The power and hydrogen co-production method according to claim 8, characterized in that, After the double-tank near-isothermal compression module repeatedly compresses air, it releases heat in the heat exchanger (14) to heat methanol, stores high-pressure air in the air storage chamber (15), and the high-pressure air is preheated and heated twice in sequence in the recuperator group (17); a part of the methanol after absorbing heat enters the mixer (26) to be mixed with water vapor and then enters the methanol steam reforming reactor (27) for reforming reaction; another part of the methanol enters the methanol cracking reactor (29) for cracking reaction. The carbon dioxide generated by the reforming reaction enters the second recuperator (172) to heat the high-pressure air, and the hydrogen generated by the reforming reaction and the cracking reaction enters the third recuperator (173) to heat the high-pressure air; the heated high-pressure air enters the combustion expansion unit, and the carbon monoxide generated by the cracking reaction enters the combustion expansion unit as fuel. After the exhaust gas of the combustion expansion unit enters the steam generator (13) to heat water to generate steam, it then enters the first recuperator (171) to preheat the high-pressure air.

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