Water electrolysis hydrogen production flexible ammonia synthesis coupling system

Abstract

The invention discloses a water electrolysis hydrogen production flexible ammonia synthesis coupling system, and relates to the technical field of energy utilization. Comprising a renewable energy power supply, a water electrolysis hydrogen production unit, a synthesis ammonia unit, an energy recovery and transfer unit, an information prediction unit and a control unit, the water electrolysis hydrogen production unit comprises an alkaline electrolytic bath, and the alkaline electrolytic bath is connected with a renewable energy power supply; the ammonia synthesis unit comprises an ammonia synthesizer; the hydrogen source supply device is connected with the hydrogen outlet end of the alkaline electrolytic bath; the energy recovery and transfer unit comprises a first heat exchanger, one end of the first heat exchanger is connected with the ammonia synthesizer, and the other end is connected with the alkaline electrolytic bath; the information prediction unit is used for acquiring power supply prediction information and ammonia load demand prediction information of renewable energy sources, and the control unit is used for performing scheduling control on the water electrolysis hydrogen production unit and the ammonia synthesis unit. The system provided by the invention can better adapt to the volatility of the renewable energy power supply, and ensures the stable proceeding of the production process.

Description

Technical Field

[0001] The invention relates to the technical field of energy utilization, and in particular to a system for coupling water electrolysis to produce hydrogen with flexible synthesis of ammonia. Background Art

[0002] The traditional ammonia synthesis process mainly obtains raw materials by using fossil energy to produce hydrogen and air separation to produce nitrogen, and synthesizes ammonia under the action of catalysts in the synthesis tower. However, chemical plants that use fossil energy such as coal and natural gas as raw materials will emit a large amount of carbon dioxide during the hydrogen production process, exacerbating the greenhouse effect. In order to reduce carbon dioxide emissions and alleviate global warming and other negative impacts, renewable energy such as wind energy, solar energy, hydropower and geothermal energy can be used to generate electricity for electrolysis of water to produce hydrogen and synthesize ammonia to provide energy supply, thereby reducing the use of fossil energy.

[0003] Using hydrogen produced by electrolysis of water from renewable energy and nitrogen separated from low-temperature air as raw materials to synthesize ammonia can not only achieve effective local consumption of new energy, but also is an important way to transform the chemical industry into a green one. It can significantly reduce carbon emissions in the chemical industry and has great potential for scale-up. At the same time, ammonia has the potential to be a transportable renewable energy source, which can replace fossil fuels in most areas in the future and become an important part of renewable energy technology.

[0004] Compared with traditional synthetic ammonia, the green ammonia process is greatly affected by the unstable characteristics of renewable energy. When wind power and photovoltaic power are coupled into the energy supply of the synthetic ammonia system, due to the volatility of the power provided by wind power or photovoltaic power, flexible adjustment is required to ensure the stability of the production process. Therefore, it is urgent to design a system for flexible synthetic ammonia coupling with water electrolysis and hydrogen production. Summary of the invention

[0005] The main purpose of the present invention is to provide a system for the flexible coupling of water electrolysis hydrogen production and ammonia synthesis to overcome the problems existing in the prior art.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A system for flexible ammonia synthesis coupled with water electrolysis hydrogen production, comprising a renewable energy power supply, a water electrolysis hydrogen production unit, an ammonia synthesis unit, an energy recovery and transfer unit, an information prediction unit and a control unit;

[0008] The water electrolysis hydrogen production unit comprises an alkaline electrolyzer, which is connected to the renewable energy power supply to produce hydrogen and oxygen by electrolysis using the renewable energy power supply; the synthetic ammonia unit comprises an ammonia synthesizer, the air inlet end of the ammonia synthesizer is connected to a nitrogen source supply device and a hydrogen source supply device, and the hydrogen source supply device is connected to the hydrogen outlet end of the alkaline electrolyzer; the energy recovery and transfer unit comprises a first heat exchanger, one end of the first heat exchanger is connected to the ammonia synthesizer, and the other end is connected to the alkaline electrolyzer, and the first heat exchanger is used to recover the heat released by the synthetic ammonia reaction in the ammonia synthesizer, and transfer the recovered heat to the alkaline electrolyzer for reuse;

[0009] The information prediction unit is used to obtain power supply prediction information of renewable energy and ammonia load demand prediction information, and the control unit is used to dispatch and control the water electrolysis hydrogen production unit and the ammonia synthesis unit.

[0010] Furthermore, one end of the alkaline electrolyzer away from the renewable energy power supply is respectively connected to a first oxygen gas-liquid separator and a hydrogen gas-liquid separator, the gas outlet end of the first oxygen gas-liquid separator is connected to an oxygen storage tank via an oxygen compressor, and the gas outlet end of the hydrogen gas-liquid separator is connected to a hydrogen storage tank via a hydrogen compressor.

[0011] Furthermore, the gas outlet end of the hydrogen storage tank is connected to a hydrogen purification tower, and the gas outlet end of the hydrogen purification tower is connected to the hydrogen source supply device through a booster pump.

[0012] Furthermore, the outlet end of the ammonia synthesizer is sequentially connected to an ammonia separator and a liquid ammonia storage tank through pipelines, and a cooler is provided on the pipeline between the liquid ammonia storage tank and the ammonia separator.

[0013] Furthermore, it also includes a nitrogen production unit, which includes an air compressor, an oxygen-nitrogen separator, a gas-liquid separator and a liquid storage tank that are sequentially connected through pipelines, the gas-liquid separator includes a second oxygen gas-liquid separator and a nitrogen gas-liquid separator, the liquid storage tank includes a liquid oxygen storage tank and a liquid nitrogen storage tank, the liquid outlet of the second oxygen gas-liquid separator is connected to the liquid oxygen storage tank, and the liquid outlet of the nitrogen gas-liquid separator is connected to the liquid nitrogen storage tank.

[0014] Furthermore, a drying tower is provided on the pipeline between the air compressor and the oxygen-nitrogen separator, and a throttle is provided on the pipeline between the drying tower and the oxygen-nitrogen separator.

[0015] Furthermore, the gas outlets of the second oxygen gas-liquid separator and the nitrogen gas-liquid separator are connected to the pipeline between the oxygen-nitrogen separator and the throttle through a booster pump, so as to supplement the cooling capacity of the oxygen-nitrogen separator.

[0016] Furthermore, the outlet end of the liquid nitrogen storage tank is connected to a booster pump and a preheater in sequence, and the outlet end of the preheater is connected to the nitrogen source supply device.

[0017] Furthermore, the energy recovery and transfer unit also includes a second heat exchanger, one end of which is connected to the drying tower, and the other end of which is respectively connected to the preheater and the pipeline at the inlet end of the ammonia synthesizer. The second heat exchanger is used to recover the air compression heat, and use the recovered heat to heat the liquid nitrogen passing through the preheater into room temperature nitrogen, and heat the nitrogen and hydrogen at the outlet ends of the nitrogen source supply device and the hydrogen source supply device into high-temperature nitrogen and high-temperature hydrogen.

[0018] Furthermore, the information prediction unit obtains weather information for a future time period and obtains power generation prediction information for a future time period based on previous power generation information of wind power generation and photovoltaic power generation corresponding to various weather conditions; the information prediction unit obtains ammonia load demand prediction information by obtaining historical operating data of the water electrolysis hydrogen production unit and the ammonia synthesis unit and product output parameter information; the control unit adjusts the number of alkaline electrolyzer ammonia and ammonia synthesizers that are turned on and the operating power according to the power generation prediction information and the ammonia load demand prediction information.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] By setting up an energy recovery and transfer unit, the heat released by the ammonia synthesis reaction in the ammonia synthesizer is recovered, and the recovered heat is transferred to the alkaline electrolyzer for reuse, and the alkaline electrolyzer is preheated or heated, which reduces the alkali solution heating process before the start of the alkaline electrolyzer, greatly shortens the start-up time, thereby achieving rapid start-up of the alkaline electrolyzer, reducing energy consumption, and better adapting to the volatility of renewable energy power sources; and an information prediction unit and a control unit are set to obtain renewable energy power supply prediction information and ammonia load demand prediction information, and to schedule and control the water electrolysis hydrogen production unit and the ammonia synthesis unit to achieve optimal dynamic adjustment of the system, thereby improving the system's ability to absorb renewable energy volatility, and ultimately ensuring the stability of the production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the overall system of the present invention.

[0022] Figure 2 It is a schematic diagram of the water electrolysis hydrogen production unit of the present invention.

[0023] Figure 3 Schematic diagram of the synthetic ammonia unit of the present invention.

[0024] Figure 4 Schematic diagram of the nitrogen production unit of the present invention.

[0025] Among them, 1-renewable energy power supply, 2-water electrolysis hydrogen production unit, 21-alkaline electrolyzer, 22-first oxygen gas-liquid separator, 23-hydrogen gas-liquid separator, 24-oxygen compressor, 25-oxygen storage tank, 26-hydrogen compressor, 27-hydrogen storage tank, 28-hydrogen purification tower, 3-synthetic ammonia unit, 31-ammonia synthesizer, 32-ammonia separator, 33-cooler, 34-liquid ammonia storage tank, 4-nitrogen production unit, 41-air compressor, 42-drying tower, 43-oxygen and nitrogen separator, 44-second oxygen gas-liquid separator, 45-nitrogen gas-liquid separator, 46-liquid oxygen storage tank, 47-liquid nitrogen storage tank, 48-preheater, 5-nitrogen source supply device, 6-hydrogen source supply device, 7-first heat exchanger, 8-second heat exchanger. DETAILED DESCRIPTION

[0026] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0027] Combination Figures 1 to 4 This embodiment provides a system for flexible ammonia synthesis coupled with water electrolysis hydrogen production, including a renewable energy power supply 1, a water electrolysis hydrogen production unit 2, an ammonia synthesis unit 3, an energy recovery and transfer unit, an information prediction unit and a control unit.

[0028] In this embodiment, the water electrolysis hydrogen production unit 2 includes an alkaline electrolyzer 21, which is connected to the renewable energy power supply 1 to produce hydrogen and oxygen by electrolysis using the renewable energy power supply 1; the synthetic ammonia unit 3 includes an ammonia synthesizer 31, and the air inlet end of the ammonia synthesizer 31 is connected to a nitrogen source supply device 5 and a hydrogen source supply device 6, and the hydrogen source supply device 6 is connected to the hydrogen outlet end of the alkaline electrolyzer 21; the energy recovery and transfer unit includes a first heat exchanger 7, one end of the first heat exchanger 7 is connected to the ammonia synthesizer 31, and the other end is connected to the alkaline electrolyzer 21, and the first heat exchanger 7 is used to recover the heat released by the synthetic ammonia reaction in the ammonia synthesizer 31, and transfer the recovered heat to the alkaline electrolyzer 21 for reuse. By adopting this scheme, the heat released by the ammonia synthesis reaction in the ammonia synthesizer 31 is recovered by setting the first heat exchanger 7, and the recovered heat is transferred to the alkaline electrolytic cell 21 for reuse, so as to preheat or heat the alkaline electrolytic cell 21, reduce the alkali solution heating process before starting the alkaline electrolytic cell 21, greatly shorten the start-up time, thereby realizing the rapid start-up of the alkaline electrolytic cell 21, reducing energy consumption, and better adapting to the volatility of the renewable energy power source 1.

[0029] In this embodiment, the information prediction unit is used to obtain power supply prediction information of renewable energy and ammonia load demand prediction information, and the control unit is used to perform scheduling control on the water electrolysis hydrogen production unit 2 and the ammonia synthesis unit 3.

[0030] The information prediction unit obtains weather information for a future time period and obtains power generation prediction information for a future time period based on previous power generation information of wind power generation and photovoltaic power generation corresponding to various weather conditions; the information prediction unit obtains ammonia load demand prediction information by obtaining historical operating data of the water electrolysis hydrogen production unit 2 and the ammonia synthesis unit 3 and product output parameter information; the control unit adjusts the number of ammonias in the alkaline electrolyzer 21 and the ammonia synthesizer 31 that are turned on and the operating power according to the power generation prediction information and the ammonia load demand prediction information.

[0031] This solution can achieve optimal dynamic regulation of the system, thereby improving the system's ability to absorb the volatility of renewable energy and ultimately ensuring the stability of the production process.

[0032] For example, during operation, the control unit may reduce the number of alkaline electrolytic cells 21 that are opened or reduce the operating power to reduce the consumption of electrical energy.

[0033] In this embodiment, the end of the alkaline electrolyzer 21 away from the renewable energy power source 1 is respectively connected to a first oxygen gas-liquid separator 22 and a hydrogen gas-liquid separator 23, the gas outlet end of the first oxygen gas-liquid separator 22 is connected to an oxygen storage tank 25 through an oxygen compressor 24, and the gas outlet end of the hydrogen gas-liquid separator 23 is connected to a hydrogen storage tank 27 through a hydrogen compressor 26.

[0034] Preferably, the gas outlet end of the hydrogen storage tank 27 is connected to a hydrogen purification tower 28 , and the gas outlet end of the hydrogen purification tower 28 is connected to the hydrogen source supply device 6 via a booster pump.

[0035] In this embodiment, the outlet end of the ammonia synthesizer 31 is sequentially connected to an ammonia separator 32 and a liquid ammonia storage tank 34 through pipelines, and a cooler 33 is provided on the pipeline between the liquid ammonia storage tank 34 and the ammonia separator 32 .

[0036] In another embodiment, the system further includes a nitrogen production unit 4. Since the supply of raw nitrogen is also a key link in the flexibility optimization and regulation of the synthetic ammonia process, the nitrogen production unit 4 is optimized in this embodiment.

[0037] Specifically, the nitrogen production unit 4 includes an air compressor 41, an oxygen-nitrogen separator 43, a gas-liquid separator and a liquid storage tank which are sequentially connected through pipelines. The gas-liquid separator includes a second oxygen gas-liquid separator 44 and a nitrogen gas-liquid separator 45. The liquid storage tank includes a liquid oxygen storage tank 46 and a liquid nitrogen storage tank 47. The liquid outlet of the second oxygen gas-liquid separator 44 is connected to the liquid oxygen storage tank 46, and the liquid outlet of the nitrogen gas-liquid separator 45 is connected to the liquid nitrogen storage tank 47.

[0038] Preferably, a drying tower 42 is provided on the pipeline between the air compressor 41 and the oxygen-nitrogen separator 43, and a throttle is provided on the pipeline between the drying tower 42 and the oxygen-nitrogen separator 43. The outlet end of the liquid nitrogen storage tank 47 is connected to a booster pump and a preheater 48 in sequence, and the outlet end of the preheater 48 is connected to the nitrogen source supply device 5.

[0039] Preferably, the gas outlets of the second oxygen gas-liquid separator 44 and the nitrogen gas-liquid separator 45 are connected to the pipeline between the oxygen-nitrogen separator 43 and the throttle through a booster pump, so as to supplement the cooling capacity of the oxygen-nitrogen separator 43. With this solution, the cooling capacity in the system can be recovered, further saving the energy consumption of the system.

[0040] Preferably, the energy recovery and transfer unit further comprises a second heat exchanger 8, one end of the second heat exchanger 8 is connected to the drying tower 42, and the other end is respectively connected to the preheater 48 and the pipeline at the inlet end of the ammonia synthesizer 31, the second heat exchanger 8 is used to recover the air compression heat, and use the recovered heat to heat the liquid nitrogen passing through the preheater 48 into room temperature nitrogen, and heat the nitrogen and hydrogen at the outlet ends of the nitrogen source supply device 5 and the hydrogen source supply device 6 into high temperature nitrogen and high temperature hydrogen.

[0041] This solution is used to recover and utilize the air compression heat, which can not only save energy and reduce consumption but also ensure the continuous and stable supply and flexible adjustment of nitrogen in the synthetic ammonia unit 3.

[0042] In this embodiment, by providing a nitrogen production unit 4 that can continuously and stably supply nitrogen, the stable progress of the production process is further ensured.

[0043] The above description is only a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Therefore, any slight modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A system for flexible ammonia synthesis coupled with water electrolysis hydrogen production, characterized in that: It includes a renewable energy power supply, a water electrolysis hydrogen production unit, an ammonia synthesis unit, an energy recovery and transfer unit, an information prediction unit, and a control unit; The water electrolysis hydrogen production unit comprises an alkaline electrolyzer, which is connected to the renewable energy power supply to produce hydrogen and oxygen by electrolysis using the renewable energy power supply; the synthetic ammonia unit comprises an ammonia synthesizer, the air inlet end of the ammonia synthesizer is connected to a nitrogen source supply device and a hydrogen source supply device, and the hydrogen source supply device is connected to the hydrogen outlet end of the alkaline electrolyzer; the energy recovery and transfer unit comprises a first heat exchanger, one end of the first heat exchanger is connected to the ammonia synthesizer, and the other end is connected to the alkaline electrolyzer, and the first heat exchanger is used to recover the heat released by the synthetic ammonia reaction in the ammonia synthesizer, and transfer the recovered heat to the alkaline electrolyzer for reuse; The information prediction unit is used to obtain power supply prediction information of renewable energy and ammonia load demand prediction information, and the control unit is used to dispatch and control the water electrolysis hydrogen production unit and the ammonia synthesis unit.

2. A system for flexible ammonia synthesis coupled with water electrolysis hydrogen production as claimed in claim 1, characterized in that: The end of the alkaline electrolyzer away from the renewable energy power supply is respectively connected to a first oxygen gas-liquid separator and a hydrogen gas-liquid separator, the gas outlet end of the first oxygen gas-liquid separator is connected to an oxygen storage tank via an oxygen compressor, and the gas outlet end of the hydrogen gas-liquid separator is connected to a hydrogen storage tank via a hydrogen compressor.

3. A system for flexible ammonia synthesis coupled with water electrolysis hydrogen production as claimed in claim 2, characterized in that: The gas outlet end of the hydrogen storage tank is connected to a hydrogen purification tower, and the gas outlet end of the hydrogen purification tower is connected to the hydrogen source supply device through a booster pump.

4. The system for flexible ammonia synthesis coupled with water electrolysis hydrogen production as claimed in claim 1, characterized in that: The outlet end of the ammonia synthesizer is sequentially connected to an ammonia separator and a liquid ammonia storage tank through pipelines, and a cooler is provided on the pipeline between the liquid ammonia storage tank and the ammonia separator.

5. The system for flexible ammonia synthesis coupled with water electrolysis hydrogen production as claimed in claim 1, characterized in that: It also includes a nitrogen production unit, which includes an air compressor, an oxygen-nitrogen separator, a gas-liquid separator and a liquid storage tank that are sequentially connected through pipelines. The gas-liquid separator includes a second oxygen gas-liquid separator and a nitrogen gas-liquid separator. The liquid storage tank includes a liquid oxygen storage tank and a liquid nitrogen storage tank. The liquid outlet of the second oxygen gas-liquid separator is connected to the liquid oxygen storage tank, and the liquid outlet of the nitrogen gas-liquid separator is connected to the liquid nitrogen storage tank.

6. A system for coupling water electrolysis hydrogen production and flexible ammonia synthesis as claimed in claim 5, characterized in that: A drying tower is provided on the pipeline between the air compressor and the oxygen-nitrogen separator, and a throttle is provided on the pipeline between the drying tower and the oxygen-nitrogen separator.

7. A system for coupling water electrolysis hydrogen production and flexible ammonia synthesis as claimed in claim 6, characterized in that: The gas outlets of the second oxygen gas-liquid separator and the nitrogen gas-liquid separator are both connected to the pipeline between the oxygen-nitrogen separator and the throttle through a booster pump, so as to supplement the cooling capacity of the oxygen-nitrogen separator.

8. The system for flexible ammonia synthesis coupled with water electrolysis hydrogen production as claimed in claim 6, characterized in that: The outlet end of the liquid nitrogen storage tank is connected to a booster pump and a preheater in sequence, and the outlet end of the preheater is connected to the nitrogen source supply device.

9. A system for coupling water electrolysis hydrogen production and flexible ammonia synthesis as claimed in claim 8, characterized in that: The energy recovery and transfer unit also includes a second heat exchanger, one end of which is connected to the drying tower, and the other end of which is respectively connected to the preheater and the pipeline at the inlet end of the ammonia synthesizer. The second heat exchanger is used to recover the air compression heat, and use the recovered heat to heat the liquid nitrogen that has passed through the preheater into room temperature nitrogen, and heat the nitrogen and hydrogen at the outlet ends of the nitrogen source supply device and the hydrogen source supply device into high-temperature nitrogen and high-temperature hydrogen.

10. The system for flexible ammonia synthesis coupled with water electrolysis hydrogen production as claimed in claim 1, characterized in that: The information prediction unit obtains weather information for a future time period and obtains power generation prediction information for a future time period based on previous wind power generation and photovoltaic power generation and power generation information corresponding to various weather conditions; the information prediction unit obtains ammonia load demand prediction information by obtaining historical operating data of a water electrolysis hydrogen production unit and ammonia synthesis unit and product output parameter information; the control unit adjusts the number of alkaline electrolyzer ammonia and ammonia synthesizers that are turned on and the operating power according to the power generation prediction information and the ammonia load demand prediction information.

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