Flexible green ammonia synthesis system
Through the synthesis towers A and B installed in parallel, the heat storage unit is used to collect photovoltaic or wind energy heat, solving the ammonia synthesis system problems caused by renewable energy instability, and achieving flexible production and low-energy consumption ammonia synthesis.
Patent Information
- Application Number
- CN202422037747.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-22
- Publication Date
- 2025-07-22
- Estimated Expiration
- 2034-08-22
AI Technical Summary
In the case of unstable renewable energy supply, existing ammonia synthesis systems require a large number of hydrogen storage tanks and power storage facilities or frequent shutdowns, resulting in high investment and shortened equipment life and large electrical auxiliary thermal energy consumption.
The synthesis tower A and synthesis tower B are used to collect the heat generated by photovoltaic or wind energy using the heat storage unit, and heat the synthesis tower A when the supply of hydrogen and nitrogen is insufficient to maintain the catalyst temperature, and the synthesis tower B is started using the heat of the synthesis tower A to achieve flexible production.
It reduces the demand for energy storage facilities, reduces energy consumption, extends the equipment life, and ensures the stable operation of the ammonia synthesis system.
Smart Images
Figure CN223128006U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of ammonia synthesis, and particularly relates to a flexible green ammonia synthesis system. Background Art
[0002] Hydrogen has received wide attention as a green energy source because it produces neither carbon dioxide nor other harmful pollutants after combustion. Replacing traditional fossil fuels such as petroleum and coal with hydrogen energy has very positive significance for environmental protection; green hydrogen specifically refers to hydrogen produced using renewable energy sources (such as solar energy, wind energy, biomass energy, etc.), which can achieve carbon-free emissions throughout the production cycle and is of great significance for reducing greenhouse gas emissions.
[0003] Currently, industrial ammonia synthesis using hydrogen is carried out at a pressure of 15.2 - 30.4 MPa and a temperature of 400 - 520 °C. Specifically, it is to make nitrogen and hydrogen undergo a catalytic reaction to synthesize ammonia; for existing industrial production, nitrogen is directly obtained by separating from air, and hydrogen is usually produced using fossil energy. In the context of global carbon reduction, green chemical industry has become a trend, and the hydrogen required for ammonia synthesis will be produced by electrolyzing water using renewable energy sources such as solar energy and wind energy; however, solar energy, wind energy, etc. have intermittency and instability. For example, under normal circumstances, solar energy is available during the day but not at night; for ammonia synthesis, the activation temperature of the catalyst is generally around 400 °C, and the heat released by the reaction of hydrogen and nitrogen is used to continuously maintain the temperature of the ammonia synthesis tower to keep the catalytic reaction uninterrupted; however, when hydrogen cannot be supplied to the ammonia synthesis system at night or under no-light conditions, currently, a large number of hydrogen storage tanks and electricity storage facilities are often installed, the system is shut down, or electric auxiliary heating is used to maintain the temperature of the ammonia synthesis tower; installing hydrogen storage tanks and electricity storage facilities will increase the overall project investment, and both hydrogen storage and electricity storage have risks, and hydrogen storage tanks are major hazard sources; when using the shutdown method, not only a large amount of energy is consumed when starting again, but also frequent start-stop of equipment will affect the service life of the equipment; using electric auxiliary heating to maintain the temperature of the ammonia synthesis tower requires a large amount of energy. Summary of the Utility Model
[0004] The purpose of the utility model is to provide a flexible green ammonia synthesis system. When the supply of hydrogen and nitrogen generated based on photovoltaic or wind energy is sufficient, the heat generated by synthesis tower B is collected by the heat storage unit at this time; then, when the supply of hydrogen and nitrogen generated based on photovoltaic or wind energy decreases, first, the heat storage unit is used to heat synthesis tower A to control the temperature inside synthesis tower A to rise to the startup temperature. At this time, only synthesis tower A with a small design production capacity is started, and the heat generated by ammonia synthesis in synthesis tower A is used to maintain a relatively high temperature inside synthesis tower B, facilitating the subsequent normal startup of synthesis tower B, thus solving the problems raised in the existing background art.
[0005] To solve the above technical problems, the present utility model is realized through the following technical solutions:
[0006] The present utility model is a flexible green ammonia synthesis system, which includes a synthesis tower A and a synthesis tower B arranged in parallel, a hydrogen production unit and a nitrogen production unit for feeding a hydrogen-nitrogen mixed gas into the synthesis tower A and / or the synthesis tower B, and an ammonia separation unit for processing and separating the mixed gas prepared and produced by the synthesis tower A and / or the synthesis tower B to obtain a mixed gas and ammonia; it further includes a heat storage unit, the heat storage unit includes a heat storage device, the intake end of the heat storage device is connected and arranged in a first heat exchange interlayer in the synthesis tower B, the first heat exchange interlayer is connected and arranged in a second heat exchange interlayer in the synthesis tower A, the second heat exchange interlayer is connected to a nitrogen circulation compressor, the outlet end of the heat storage device is connected to a tubular lye heater arranged in a lye tank, and the tubular lye heater is connected to the nitrogen circulation compressor.
[0007] When the synthesis system operates, it includes a standby state and a normal operation state;
[0008] When in the normal operation state, the gases obtained by the hydrogen production unit and the nitrogen production unit are sent into the synthesis tower B through a mixed gas compressor, and after the reaction is completed in the synthesis tower B, the prepared and produced mixed gas is sent into the ammonia separation unit; at the same time, the nitrogen circulation compressor sends nitrogen into the first heat exchange interlayer in the synthesis tower B through the second heat exchange interlayer for heating and heat exchange and then returns to the heat storage device for heat exchange and energy storage, and at the same time, the heat-exchanged nitrogen returns to the second heat exchange interlayer through the tubular lye heater and the nitrogen circulation compressor;
[0009] When in the standby state, the gases obtained by the hydrogen production unit and the nitrogen production unit are sent into the synthesis tower A through a mixed gas compressor, and after the reaction is completed in the synthesis tower A, the prepared and produced mixed gas is sent into the ammonia separation unit; at the same time, the nitrogen circulation compressor sends nitrogen into the first heat exchange interlayer in the synthesis tower B through the second heat exchange interlayer for heating and heat exchange and then returns to the heat storage device for heat exchange and energy storage, and at the same time, the heat-exchanged nitrogen returns to the second heat exchange interlayer through the tubular lye heater and the nitrogen circulation compressor; and the electrolyte in the hydrogen production unit is introduced into the lye tank for heat preservation.
[0010] Furthermore, the design production capacity ratio of the synthesis tower A and the synthesis tower B is 1:2 - 5.
[0011] Furthermore, both the hydrogen production unit and the nitrogen production unit are powered by a renewable energy power generation system; the hydrogen production unit includes a hydrogen production device with an electrolytic cell, and the hydrogen produced by the hydrogen production device is purified and then sent into a hydrogen storage tank through a hydrogen compressor; the nitrogen production unit includes a nitrogen production device, and the nitrogen produced by the nitrogen production device is sent into a nitrogen storage tank through a nitrogen compressor; the gases stored in the nitrogen storage tank and the hydrogen storage tank are sent into a high-temperature heat exchanger through a mixed gas compressor, and after heat exchange in the high-temperature heat exchanger, they are sent into synthesis tower A or synthesis tower B.
[0012] Furthermore, the ammonia separation unit includes a cold exchanger, the heat medium inlet of the cold exchanger is connected to synthesis tower A and synthesis tower B, and its heat medium outlet is connected to the heat medium inlet of an ammonia cooler; the heat medium outlet of the ammonia cooler is connected to an ammonia separator, the ammonia separator is connected to a liquid ammonia storage tank and the refrigerant inlet of the cold exchanger, and the refrigerant outlet of the cold exchanger is connected to the intake end or the outlet end of the mixed gas compressor.
[0013] Furthermore, both the refrigerant inlet and the refrigerant outlet of the ammonia cooler are connected to an ice machine system.
[0014] The utility model has the following beneficial effects:
[0015] With the parallel arrangement of synthesis tower A and synthesis tower B in the utility model, when the supply of hydrogen and nitrogen generated based on photovoltaic or wind energy is sufficient, the heat generated by synthesis tower A and B is collected by the heat storage unit at this time; furthermore, when the supply of hydrogen and nitrogen generated based on photovoltaic or wind energy decreases and the temperature generated by the ammonia synthesis reaction in the synthesis tower cannot maintain the catalytic reaction, first use the heat storage unit to heat synthesis tower A to control the temperature of synthesis tower A above the activation temperature of the catalyst. After the supply of hydrogen and nitrogen is stable, start synthesis tower A with a smaller design production capacity, and use the heat generated by ammonia synthesis in synthesis tower A to heat synthesis tower B to reach the activation temperature of the catalyst, so that synthesis tower B is put into production.
[0016] Of course, it is not necessary for any product implementing the utility model to achieve all the above-mentioned advantages simultaneously. Description of the Drawings
[0017] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the utility model. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.
[0018] Figure 1 It is the process of the flexible green ammonia synthesis system of the utility model Figure 1 ;
[0019] Figure 2For the process of the flexible green ammonia synthesis system of the present utility model Figure 2 . Specific embodiments
[0020] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present utility model.
[0021] In the description of the present utility model, it should be understood that the terms "opening", "upper", "lower", "thickness", "top", "middle", "length", "inner", "periphery", etc. indicating orientation or positional relationship are only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the components or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present utility model.
[0022] Please refer to Figure 1 As shown, the present utility model is a flexible green ammonia synthesis system, including a synthesis tower A11 and a synthesis tower B12 arranged in parallel. The synthesis tower A11 and the synthesis tower B12 are in series during daily use; the synthesis gas in the ammonia synthesis system of the present utility model is prepared into hydrogen and nitrogen by a hydrogen production unit and a nitrogen production unit respectively; and both the hydrogen production unit and the nitrogen production unit are powered by a renewable energy power generation system. Due to the well-known disadvantage of the instability of renewable energy power generation, the production of hydrogen and nitrogen is also unstable.
[0023] Based on the unstable characteristics of the production of hydrogen and nitrogen, the present utility model takes solar energy as the renewable energy power generation system for illustration. Since photovoltaic power generation has the characteristics of being available during the day but not at night under normal circumstances, in practice, hydrogen and nitrogen are sufficiently supplied during the day, but insufficiently supplied at night; therefore, the ammonia synthesis system operates at full load during the day and at low load at night. Furthermore, during the day, the synthesis tower A11 and the synthesis tower B12 are started together, and at night, the synthesis tower A11 with a smaller designed production capacity is controlled to start.
[0024] Meanwhile, a heat storage unit is also provided, which includes a heat storage device 15. The intake end of the heat storage device is connected to a first heat exchange interlayer arranged in the synthesis tower B12. The first heat exchange interlayer is connected to a second heat exchange interlayer arranged in the synthesis tower A11. The second heat exchange interlayer is connected to a nitrogen circulation compressor 13. The outlet end of the heat storage device is connected to a tubular lye heater 14 arranged in a lye tank. The tubular lye heater 14 is connected to the nitrogen circulation compressor 13. When it is realized, during the day when the supply of hydrogen and nitrogen is sufficient, the heat storage unit is used to collect the heat generated by the synthesis towers A and B. When the supply of hydrogen and nitrogen decreases at night and the temperature generated by the ammonia synthesis reaction in the synthesis tower cannot maintain the catalytic reaction, first, the heat storage unit is used to heat the synthesis tower A to control the temperature of the synthesis tower A to be maintained above the activation temperature of the catalyst. When the supply of hydrogen and nitrogen is stable, the synthesis tower A with a small design production capacity is started, and the heat generated by the ammonia synthesis in the synthesis tower A is used to heat the synthesis tower B to above the activation temperature of the catalyst, and then the synthesis tower B is put into production.
[0025] Among them, the first heat exchange interlayer and the second heat exchange interlayer have the same structure, and they are respectively arranged on the peripheral side walls of the synthesis tower B12 and the synthesis tower A11.
[0026] Meanwhile, at night, because there is no electric energy, the electrolyzer does not work, but the electrolyte in the electrolyzer also needs to maintain a certain temperature. In this application, the tubular lye heater 14 is used to heat the electrode liquid in the lye tank, that is, when in use, the electrolyte in the electrolyzer needs to be introduced into the lye tank at night; of course, in another embodiment, the tubular lye heater 14 can also be directly arranged in the electrolyzer.
[0027] It can be known that when the synthesis system of this application operates, it includes a standby state and a normal operation state, that is, during the day, the synthesis system is in a normal operation state, and at night, the synthesis system is in a low-load operation or standby state.
[0028] When in the normal operation state, the gases obtained by the hydrogen production unit and the nitrogen production unit are sent into the synthesis tower B12 through a mixture compressor 2. After the reaction is completed in the synthesis tower B12, the prepared mixed gas is sent into an ammonia separation unit; at the same time, the nitrogen circulation compressor 13 sends nitrogen into the first heat exchange interlayer in the synthesis tower B12 through the second heat exchange interlayer for heating and heat exchange, and then returns to the heat storage device 15 for heat exchange and energy storage. At the same time, the heat-exchanged nitrogen flows back to the second heat exchange interlayer through the tubular lye heater 14 and the nitrogen circulation compressor 13.
[0029] When in low-load operation or standby state, the gases obtained from the hydrogen production unit and the nitrogen production unit are sent into the synthesis tower A11 through the mixed gas compressor 2. After the reaction is completed in the synthesis tower A11, the prepared mixed gas is sent into the ammonia separation unit. At the same time, the nitrogen circulation compressor 13 sends nitrogen into the first heat exchange interlayer in the synthesis tower B12 through the second heat exchange interlayer for heating and heat exchange, and then returns to the heat storage device 15 for heat exchange and energy storage. At the same time, the heated nitrogen flows back to the second heat exchange interlayer through the tubular caustic solution heater 14 and the nitrogen circulation compressor 13. And the electrolyte in the hydrogen production unit is sent into the caustic solution tank for heat preservation.
[0030] In this technical solution, the designed production capacity ratio of the synthesis tower A11 and the synthesis tower B12 is 1:2 - 5, that is, the internal volume of the synthesis tower A11 is smaller than that of the synthesis tower B12, realizing the normal operation of the synthesis tower A11 under low nitrogen and hydrogen supply, and the normal operation of the synthesis tower B12 under high nitrogen and hydrogen supply.
[0031] The hydrogen production unit includes a hydrogen production device 21 of an electrolytic cell. The hydrogen generated by the hydrogen production device 21 is purified and then sent into the hydrogen storage tank 212 through the hydrogen compressor 211. The nitrogen production unit includes a nitrogen production device 22. The nitrogen generated by the nitrogen production device 22 is sent into the nitrogen storage tank 222 through the nitrogen compressor 221. The gases stored in the nitrogen storage tank 222 and the hydrogen storage tank 212 are sent into the high-temperature heat exchanger 3 through the mixed gas compressor 2, and after heat exchange in the high-temperature heat exchanger 3, they are sent into the synthesis tower A11 or the synthesis tower B12.
[0032] In this application, it also includes an ammonia separation unit for processing and separating the mixed gas prepared by the synthesis tower A11 and / or the synthesis tower B12 to obtain a mixed gas and ammonia. The ammonia separation unit includes a cold exchanger 4. The heat medium inlet of the cold exchanger 4 is connected to the synthesis tower A11 and the synthesis tower B12, and its heat medium outlet is connected to the heat medium inlet of the ammonia cooler 7. The heat medium outlet of the ammonia cooler 7 is connected to the ammonia separator 5. The ammonia separator 5 is connected to the liquid ammonia storage tank 6 and the refrigerant inlet of the cold exchanger 4. The refrigerant outlet of the cold exchanger 4 is connected to the intake end or the outlet end of the mixed gas compressor 2. The refrigerant inlet and the refrigerant outlet of the ammonia cooler 7 are both connected to the ice machine system 8.
[0033] It can be understood that on the above basis, such as Figure 2 , a nitrogen preheater 220 is connected to the outlet end of the nitrogen storage tank 222. When in use, the heat inside the heat storage device 15 is used to heat the raw material nitrogen to a certain temperature, and then it enters the synthesis tower A11 after being pressurized by the mixed gas compressor 2. This can reduce the heat loss in the synthesis tower A11. It is mainly used in the low-load operation stage of the system. When the self-exothermic heat of the ammonia synthesis reaction in the synthesis tower A11 cannot meet the preheating of the raw material gas and the natural heat dissipation, the temperature is not enough and the catalytic reaction stops. Therefore, by increasing the nitrogen inlet temperature, the heat loss is reduced.
[0034] In the description of this specification, the descriptions referring to the terms "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present utility model. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.
[0035] The preferred embodiments of the present utility model disclosed above are only used to help explain the present utility model. The preferred embodiments do not describe all the details in detail, nor do they limit the present utility model to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification in order to better explain the principle and practical application of the present utility model, so that those skilled in the art can well understand and utilize the present utility model. The present utility model is only limited by the claims and their full scope and equivalents.
Claims
1. A flexible green ammonia synthesis system, characterized in that: It includes a synthesis tower A (11) and a synthesis tower B (12) which are arranged in parallel; It also includes a hydrogen production unit and a nitrogen production unit for feeding a hydrogen-nitrogen mixed gas into the synthesis tower A (11) and / or the synthesis tower B (12); It further includes a heat storage unit. The heat storage unit includes a heat storage device (15). The intake end of the heat storage device is connected to a first heat exchange interlayer arranged in the synthesis tower B (12). The first heat exchange interlayer is connected to a second heat exchange interlayer arranged in the synthesis tower A (11). The second heat exchange interlayer is connected to a nitrogen circulation compressor (13). The outlet end of the heat storage device is connected to a tubular caustic solution heater (14) arranged in a caustic solution tank. The tubular caustic solution heater (14) is connected to the nitrogen circulation compressor (13); It also includes an ammonia separation unit for processing the mixed gas produced by the synthesis tower A (11) and / or the synthesis tower B (12) and separating it to obtain a mixed gas and ammonia; When the synthesis system operates, it includes a standby state and a normal operation state; When in the normal operation state, the gases obtained by the hydrogen production unit and the nitrogen production unit are sent into the synthesis tower B (12) through a mixed gas compressor (2). After the reaction is completed in the synthesis tower B (12), the produced mixed gas is sent into the ammonia separation unit. At the same time, the nitrogen circulation compressor (13) sends nitrogen into the first heat exchange interlayer in the synthesis tower B (12) through the second heat exchange interlayer for heating and heat exchange, and then returns to the heat storage device (15) for heat exchange and energy storage. At the same time, the heat-exchanged nitrogen returns to the second heat exchange interlayer through the tubular caustic solution heater (14) and the nitrogen circulation compressor (13); When in the standby state, the gases obtained by the hydrogen production unit and the nitrogen production unit are sent into the synthesis tower A (11) through a mixed gas compressor (2). After the reaction is completed in the synthesis tower A (11), the produced mixed gas is sent into the ammonia separation unit. At the same time, the nitrogen circulation compressor (13) sends nitrogen into the first heat exchange interlayer in the synthesis tower B (12) through the second heat exchange interlayer for heating and heat exchange, and then returns to the heat storage device (15) for heat exchange and energy storage. At the same time, the heat-exchanged nitrogen returns to the second heat exchange interlayer through the tubular caustic solution heater (14) and the nitrogen circulation compressor (13); and the electrolyte in the hydrogen production unit is sent into the caustic solution tank for heat preservation.
2. The flexible green ammonia synthesis system according to claim 1, wherein The designed production capacity ratio of the synthesis tower A (11) and the synthesis tower B (12) is 1:2 - 5.
3. The flexible green ammonia synthesis system according to claim 1, characterized in that, Both the hydrogen production unit and the nitrogen production unit are powered by a renewable energy power generation system (20). The hydrogen production unit includes a hydrogen production device (21) of an electrolytic cell. The hydrogen produced by the hydrogen production device (21) is purified and then sent into a hydrogen storage tank (212) through a hydrogen compressor (211). The nitrogen production unit includes a nitrogen production device (22). The nitrogen produced by the nitrogen production device (22) is sent into a nitrogen storage tank (222) through a nitrogen compressor (221); The gases stored in the nitrogen storage tank (222) and the hydrogen storage tank (212) are sent into a high-temperature heat exchanger (3) through a mixed gas compressor (2). After heat exchange in the high-temperature heat exchanger (3), they are then sent into the synthesis tower A (11) or the synthesis tower B (12).
4. A flexible green ammonia synthesis system according to claim 1, wherein, The ammonia separation unit includes a cold exchanger (4), the hot medium inlet of the cold exchanger (4) is connected to the synthesis tower A (11) and the synthesis tower B (12), and its hot medium outlet is connected to the hot medium inlet of the ammonia cooler (7); The hot medium outlet of the ammonia cooler (7) is connected to the ammonia separator (5), the ammonia separator (5) is connected to the liquid ammonia storage tank (6) and the refrigerant inlet of the cold exchanger (4), and the refrigerant outlet of the cold exchanger (4) is connected to the intake end or the outlet end of the mixed gas compressor (2).
5. A flexible green ammonia synthesis system according to claim 4, characterized in that, Both the refrigerant inlet and the refrigerant outlet of the ammonia cooler (7) are connected to the ice machine system (8).