System and method for preparing synthetic ammonia

Abstract

The invention relates to a system and method for preparing synthetic ammonia, and the system receives a wind-light fluctuation signal of a renewable energy power generation unit through a control unit, and converts the wind-light fluctuation signal into a current signal inputted to a hydrogen production unit and a nitrogen production unit. A hydrogen flow signal and a nitrogen flow signal required by the synthesis ammonia reaction are determined according to the current signal, so that the adaptability of the whole system to renewable energy fluctuation is further improved; on the other hand, the system is in integrated linkage, and the hydrogen yield, the nitrogen yield and process parameter conditions are accurately controlled in real time, so that the system is high in overall operation precision and energy utilization efficiency, the subsequent synthesis ammonia reaction only needs to adapt to fluctuation of raw material gas, the reaction effect is good, the purity of outlet gas is high, and the overall system efficiency is high under the condition that equipment investment is not increased; meanwhile, the catalytic deoxidation unit in the system can further completely remove oxygen impurities in hydrogen and nitrogen, and the problem that impurities exceed the standard due to the volatility of renewable energy sources is avoided.

Description

Technical Field

[0001] The present disclosure belongs to the field of ammonia synthesis, and particularly relates to a system and method for preparing ammonia synthesis. Background Art

[0002] Recently, green ammonia has become the focus of global attention. Ammonia is expanding from the traditional agricultural fertilizer field to the new energy field. Due to the high unit calorific value and unit hydrogen storage density of ammonia, it has obvious advantages in its storage and transportation. The biggest difference between green ammonia and the traditional ammonia synthesis process is that the raw material of green ammonia is directly green hydrogen generated by electrolyzing water. After the green hydrogen is mixed with nitrogen separated from air, pressurized, and purified, ammonia is generated through an ammonia synthesis reactor.

[0003] Currently, due to the volatility of power generation from renewable energy sources such as wind energy and solar energy, there is a mismatch between the power generation peak and the power consumption peak, resulting in difficulties in grid connection. By electrolyzing hydrogen to convert renewable energy into hydrogen, which can be stored and transferred, therefore, the process of jointly synthesizing ammonia from renewable energy, hydrogen production system, and nitrogen production system further improves the energy utilization efficiency. However, in the current ammonia synthesis system, the hydrogen production system and the nitrogen production system are respectively operated by two sets of PLC control systems. In the electrolytic hydrogen production system, the electrolyzer control system controls the rectifier cabinet, hydrogen-oxygen separation, caustic liquor circulation pump and makeup water pump, electrolysis voltage and current, hydrogen pressure and temperature display. The purification control system uses PLC to control the temperature of the deoxidation tower and the switching of each valve of the drying tower to realize the cycle of working, regeneration, and regeneration gas recovery steps. While the nitrogen production system uses an integrated control system alone, which cannot accurately control the operating conditions of the system, resulting in the inability to accurately obtain the amounts of hydrogen and nitrogen required for the subsequent ammonia synthesis reaction, causing low overall system operation accuracy and efficiency of the ammonia synthesis process, complex operation, energy consumption loss, and low energy utilization efficiency. On the other hand, since the energy consumption of the pressure swing adsorption nitrogen production equipment is mainly compressed air, the vented oxygen-rich waste gas usually consumes more than 50% of the compressed air. The higher the purity requirement of the nitrogen separated, the more air is needed, and the higher the energy consumption. Moreover, the nitrogen production system is also prone to problems such as excessive impurities during the instantaneous operation adapting to the volatility of wind and light. Summary of the Invention

[0004] The object of the present invention is to provide a system and method for preparing ammonia synthesis. The system provided by the present invention has high adaptability to the fluctuations of renewable energy. After the system is linked, it can adjust and accurately control the hydrogen production, nitrogen production, and process parameter conditions in real time. The overall system has high operation accuracy, high energy utilization efficiency, high purity of the outlet gas, and low process energy consumption.

[0005] To achieve the above object, the present invention provides a system for preparing ammonia synthesis, characterized in that the system includes: a renewable energy power generation unit, a control unit, an electrolytic hydrogen production unit, a nitrogen production unit, a catalytic deoxidation unit, a dehydration unit, and an ammonia synthesis unit;

[0006] The control unit is respectively signal-connected to the renewable energy power generation unit, the nitrogen production unit, and the electrolytic hydrogen production unit, and is configured to receive the fluctuating power supply signal of the renewable energy power generation unit, and adjust the hydrogen production amount of the electrolytic hydrogen production unit and the nitrogen production amount of the nitrogen production unit according to the fluctuating power supply signal;

[0007] The catalytic deoxidation unit includes a first mixed gas inlet and a first mixed gas outlet; the hydrogen outlet of the hydrogen production unit and the nitrogen outlet of the nitrogen production unit are respectively communicated with the first mixed gas inlet of the catalytic deoxidation unit; the first mixed gas outlet of the catalytic deoxidation unit is communicated with the inlet of the dehydration unit;

[0008] The gas outlet of the dehydration unit is communicated with the second mixed gas inlet of the ammonia synthesis unit.

[0009] Optionally, the electrolytic hydrogen production unit includes an electrolytic water hydrogen production device, a gas-liquid separation device, and a pure water device; the electrolytic water hydrogen production device includes a pure water inlet and a hydrogen outlet, and the hydrogen outlet of the electrolytic water hydrogen production device is communicated with the inlet of the gas-liquid separation device;

[0010] The liquid phase outlet of the gas-liquid separation device is communicated with the inlet of the pure water device, and the outlet of the pure water device is communicated with the pure water inlet of the electrolytic water hydrogen production device;

[0011] The electrolytic water hydrogen production device includes one or more of an alkaline porous diaphragm electrolytic cell, an alkaline ion exchange membrane electrolytic cell, a proton exchange membrane electrolytic cell, an anion exchange membrane electrolytic cell, or a solid oxide electrolytic cell;

[0012] The gas-liquid separation device includes one or more of a horizontal gas-liquid separation device or a vertical gas-liquid separation device.

[0013] Optionally, the nitrogen production unit includes one or more of a cryogenic air separation nitrogen production device, a pressure swing adsorption nitrogen production device, or a membrane separation nitrogen production device. Preferably, the nitrogen production unit is a pressure swing adsorption nitrogen production device;

[0014] The nitrogen production unit includes an air compression and purification device and an adsorption and separation device; the compressed air outlet of the compressed air purification device is communicated with the feed inlet of the adsorption and separation device;

[0015] The air compression and purification device includes a compressor, a dryer, a precision filter, and an air buffer tank connected in sequence;

[0016] The adsorption and separation device includes one or more adsorption and separation towers arranged in parallel.

[0017] Optionally, the control unit is respectively signal-connected to the compressor, the dryer and the adsorption separation device, and adjusts the gas flow rate and power of the compressor, the power of the dryer, the nitrogen flow rate, valve opening degree and adsorption / desorption timing sequence of the adsorption separation device, so as to maintain the outlet purity of nitrogen at 99-99.99%.

[0018] Optionally, the dehydration unit includes a TSA dehydration device; the condensate outlet of the TSA dehydration device is communicated with the inlet of the pure water device;

[0019] Preferably, the TSA dehydration device includes one or more adsorption towers arranged in parallel.

[0020] The second aspect of the present invention provides a method for preparing synthetic ammonia by using the system described in the first aspect of the present invention, wherein the method includes:

[0021] Generating electricity through a renewable power generation unit and generating a fluctuating power signal;

[0022] Enabling the electrolytic hydrogen production unit to electrolyze and prepare hydrogen by using the power generation of the renewable power generation unit;

[0023] Enabling air to enter the nitrogen production unit to prepare nitrogen;

[0024] Enabling the hydrogen from the electrolytic hydrogen production unit and the nitrogen from the nitrogen production unit to enter the catalytic deoxidation unit for deoxidation treatment, and then enter the dehydration unit for dehydration treatment;

[0025] Enabling the mixed raw material gas obtained from the dehydration unit to enter the synthetic ammonia unit for synthetic ammonia reaction; wherein, the hydrogen production amount of the electrolytic hydrogen production unit and the nitrogen production amount of the nitrogen production unit are adjusted according to the fluctuating power signal.

[0026] Optionally, the adjusting the hydrogen production amount of the electrolytic hydrogen production unit and the nitrogen production amount of the nitrogen production unit according to the fluctuating power signal includes:

[0027] The electrolytic hydrogen production rectifier power supply and the control unit receive the fluctuating power signal of the renewable energy power generation unit, and adjust the hydrogen production amount of the electrolytic hydrogen production unit according to the fluctuating power signal;

[0028] The control unit receives the fluctuating power signal of the renewable energy power generation unit, determines the nitrogen demand V 氮 of the nitrogen production unit according to the fluctuating power signal, and adjusts the nitrogen production amount of the nitrogen production unit according to the nitrogen demand V 氮 .

[0029] The determining the nitrogen demand V 氮 of the nitrogen production unit according to the fluctuating power signal includes: calculating V according to formula (1) 氮;

[0030] V 氮 = n × 0.000418 × m × I × t × η, Equation (1);

[0031] Wherein, m is the number of electrolysis cells of the electrolytic hydrogen production device; I is the current signal, with the unit of A; t is the power-on time, with the unit of h; η is the current efficiency, with the unit of %; n is 2 - 4.

[0032] Optionally, adjusting the nitrogen production amount of the nitrogen production unit according to the nitrogen demand V nitrogen includes:

[0033] By adjusting the gas flow rate and power of the compressor, the power of the dryer, the nitrogen flow rate of the adsorption separation device, the valve opening degree, and the adsorption and desorption time sequence, to maintain the outlet purity of nitrogen at 99 - 99.99%.

[0034] Optionally, the purity of hydrogen in the mixed raw material gas is above 97%; the purity of nitrogen in the mixed raw material gas is above 99%;

[0035] The volume content of nitrogen in the mixed raw material gas is above 50%; the volume content of hydrogen in the mixed raw material gas is below 50%; the dew point of the mixed raw material gas is below -65°C.

[0036] Through the above technical solutions, the system provided by the present invention receives the wind-solar fluctuation signal of the renewable energy power generation unit through the control unit, converts the wind-solar fluctuation signal into a current signal input to the hydrogen production unit and the nitrogen production unit, and determines the hydrogen flow signal and the required nitrogen flow signal for the ammonia synthesis reaction according to the current signal. On the one hand, the overall adaptability of the system to renewable energy fluctuations is further improved; on the other hand, the system realizes integrated linkage through the control unit, adjusts and precisely controls the hydrogen production amount, nitrogen production amount, and process parameter conditions in real time, making the overall operation of the system accurate, with high energy utilization efficiency. The subsequent ammonia synthesis reaction only needs to adapt to the fluctuations of the raw material gas, with good reaction effects, high outlet gas purity, high overall system efficiency without increasing equipment investment. At the same time, the catalytic deoxidation unit in the system can further completely remove the oxygen impurities in hydrogen and nitrogen, avoiding the problem of excessive impurities caused by the volatility of renewable energy. And the process and operation of the present invention are simple, with low energy consumption and operating costs, which is conducive to large-scale industrial use.

[0037] Other features and advantages of the present invention will be described in detail in the subsequent specific implementation part. Brief Description of the Drawings

[0038] The accompanying drawings are used to provide a further understanding of the present invention and form a part of the specification. Together with the following specific embodiments, they are used to explain the present invention, but do not constitute a limitation to the present invention. In the accompanying drawings:

[0039] Figure 1 It is a schematic process flow diagram of Embodiment 1 of the present invention.

[0040] Explanation of the reference numerals in the drawings

[0041] 1. Renewable energy power generation unit; 2. Control unit; 3. Hydrogen production unit; 4. Nitrogen production unit; 5. Catalytic deoxidation unit; 6. Dehydration unit; 7. Booster; 8. Ammonia synthesis unit.

[0042] 31. Pure water device; 32. Electrolytic hydrogen production device; 33. Gas-liquid separation device; 41. Compressor; 42. Dryer; 43. Precision filtration device; 44. Air buffer tank; 45. First adsorption separation tower; 46. Second adsorption separation tower; 47. Air inlet; 48. Tail gas discharge port; 451-453. Valves; 461-463. Valves; 61. First adsorption tower; 62. Second adsorption tower; 611-613. Valves; 621-623. Valves. Specific embodiments

[0043] The following will describe in detail the specific embodiments of the present disclosure with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for the purpose of illustration and explanation of the present disclosure, and are not intended to limit the present disclosure.

[0044] The first aspect of the present disclosure provides a system for preparing ammonia synthesis, characterized in that the system includes: a renewable energy power generation unit, a control unit, an electrolytic hydrogen production unit, a nitrogen production unit, a catalytic deoxidation unit, a dehydration unit, and an ammonia synthesis unit;

[0045] The control unit is respectively signal-connected to the renewable energy power generation unit, the nitrogen production unit, and the electrolytic hydrogen production unit, and is used for receiving the fluctuating power supply signal of the renewable energy power generation unit, and adjusting the hydrogen production amount of the electrolytic hydrogen production unit and the nitrogen production amount of the nitrogen production unit according to the fluctuating power supply signal;

[0046] The catalytic deoxidation unit includes a first mixed gas inlet and a first mixed gas outlet; the hydrogen outlet of the hydrogen production unit and the nitrogen outlet of the nitrogen production unit are respectively communicated with the first mixed gas inlet of the catalytic deoxidation unit; the first mixed gas outlet of the catalytic deoxidation unit is communicated with the inlet of the dehydration unit;

[0047] The gas outlet of the dehydration unit is communicated with the second mixed gas inlet of the ammonia synthesis unit.

[0048] The system provided by the present disclosure receives the wind-solar fluctuation signals of the renewable energy power generation unit through a control unit, converts the wind-solar fluctuation signals into current signals input to the hydrogen production unit and the nitrogen production unit, and determines the required hydrogen flow signal and the required nitrogen flow signal for the ammonia synthesis reaction according to the current signals. On the one hand, the overall adaptability of the system to renewable energy fluctuations is further improved; on the other hand, the system realizes integrated linkage through the control unit, adjusts and precisely controls the hydrogen production, nitrogen production and process parameter conditions in real time, so that the overall operation accuracy of the system is high, the energy utilization efficiency is high, the subsequent ammonia synthesis reaction only needs to adapt to the fluctuations of the raw material gas, the reaction effect is good, the purity of the outlet gas is high, and the overall system efficiency is high without increasing equipment investment. At the same time, the catalytic deoxidation unit in the system can further completely remove the oxygen impurities in hydrogen and nitrogen, avoiding the problem of excessive impurities caused by the volatility of renewable energy. Moreover, the process and operation of the present invention are simple, the energy consumption and operation cost are low, which is conducive to large-scale industrial use.

[0049] A specific embodiment, the electrolytic hydrogen production unit includes an electrolytic water hydrogen production device, a gas-liquid separation device and a pure water device; the electrolytic water hydrogen production device includes a pure water inlet and a hydrogen outlet, and the hydrogen outlet of the electrolytic water hydrogen production device is communicated with the inlet of the gas-liquid separation device;

[0050] The liquid phase outlet of the gas-liquid separation device is communicated with the inlet of the pure water device, and the outlet of the pure water device is communicated with the pure water inlet of the electrolytic water hydrogen production device;

[0051] The electrolytic water hydrogen production device includes one or more of an alkaline porous diaphragm electrolytic cell, an alkaline ion exchange membrane electrolytic cell, a proton exchange membrane electrolytic cell, an anion exchange membrane electrolytic cell or a solid oxide electrolytic cell;

[0052] The gas-liquid separation device includes one or more of a horizontal gas-liquid separation device or a vertical gas-liquid separation device.

[0053] In the present disclosure, the control unit is signal-connected to the electrolytic water hydrogen production device in the electrolytic hydrogen production unit, and is used to receive the fluctuation power supply signal of the renewable energy power generation unit and adjust the hydrogen production amount of the electrolytic hydrogen production unit according to the fluctuation power supply signal.

[0054] A specific embodiment, the nitrogen production unit may include one or more of a cryogenic air separation nitrogen production device, a pressure swing adsorption nitrogen production device or a membrane separation nitrogen production device. Preferably, the nitrogen production unit is a pressure swing adsorption nitrogen production device;

[0055] The nitrogen production unit includes an air compression and purification device and an adsorption and separation device; the compressed air outlet of the air compression and purification device is communicated with the feed inlet of the adsorption and separation device;

[0056] The air compression and purification device includes a compressor, a dryer, a precision filter, and an air buffer tank connected in sequence;

[0057] The adsorption and separation device includes one or more adsorption and separation towers arranged in parallel.

[0058] In a specific embodiment, the control unit is respectively signal-connected to the compressor, the dryer, and the adsorption and separation device, and adjusts the gas flow rate and power of the compressor, the power of the dryer, the nitrogen flow rate, valve opening, and adsorption and desorption timing of the adsorption and separation device to maintain the outlet purity of nitrogen at 99-99.99%. In the above embodiment, the system realizes integrated linkage through the control unit, adjusts and precisely controls the process parameter conditions of the nitrogen production unit in real time, thereby precisely regulating the nitrogen production, enabling the system to have high overall operation accuracy and high energy utilization efficiency. The subsequent synthetic ammonia reaction only needs to adapt to the fluctuations of the raw material gas, and the reaction effect is good.

[0059] In a specific embodiment, the dehydration unit includes a TSA dehydration device; the condensate outlet of the TSA dehydration device is communicated with the inlet of the pure water device;

[0060] In a preferred embodiment, the TSA dehydration device includes one or more adsorption towers arranged in parallel. Preferably, the TSA dehydration device includes less than three adsorption towers arranged in parallel.

[0061] In the present disclosure, the liquid phases discharged from the dehydration unit and the gas-liquid separation device are collected and sent into the electrolytic hydrogen production device for recycling, so that there is no need or only a small amount of external water source needs to be introduced into the hydrogen production unit, further reducing the process cost.

[0062] The second aspect of the present invention provides a method for preparing synthetic ammonia using the system described in the first aspect of the present invention. Among them, the method includes:

[0063] Generating electricity through the renewable power generation unit and generating a fluctuating power signal;

[0064] Enabling the electrolytic hydrogen production unit to perform electrolysis to prepare hydrogen using the power generation of the renewable power generation unit;

[0065] Allowing air to enter the nitrogen production unit to prepare nitrogen;

[0066] Allowing the hydrogen from the electrolytic hydrogen production unit and the nitrogen from the nitrogen production unit to enter the catalytic deoxidation unit for deoxidation treatment, and then enter the dehydration unit for dehydration treatment;

[0067] Allowing the mixed raw material gas obtained from the dehydration unit to enter the synthetic ammonia unit for synthetic ammonia reaction;

[0068] Wherein, the hydrogen production amount of the electrolytic hydrogen production unit and the nitrogen production amount of the nitrogen production unit are adjusted according to the fluctuating power supply signal.

[0069] The method provided by the present disclosure can realize the linkage of the ammonia synthesis system, adjust and precisely control the hydrogen production amount, nitrogen production amount and process parameter conditions in real time, so that the overall operation accuracy of the system is high, the energy utilization efficiency is high, and the subsequent ammonia synthesis reaction only needs to adapt to the fluctuations of the raw material gas, with good reaction effect, high purity of the outlet gas, high overall system efficiency without increasing equipment investment. At the same time, the catalytic deoxidation unit in the system can further completely remove the oxygen impurities in hydrogen and nitrogen, avoiding the problem of excessive impurities caused by the volatility of renewable energy.

[0070] In the present disclosure, by controlling the unit to control the flow ratio of nitrogen in the first mixed gas to the second hydrogen within a preferred range, the energy utilization efficiency of the system can be further improved.

[0071] In a specific embodiment, the adjustment of the hydrogen production amount of the electrolytic hydrogen production unit and the nitrogen production amount of the nitrogen production unit according to the fluctuating power supply signal includes:

[0072] The electrolytic hydrogen production rectifier power supply and the control unit receive the fluctuating power supply signal of the renewable energy power generation unit, and adjust the hydrogen production amount of the electrolytic hydrogen production unit according to the fluctuating power supply signal;

[0073] The control unit receives the fluctuating power supply signal of the renewable energy power generation unit, determines the nitrogen demand V of the nitrogen production unit according to the fluctuating power supply signal 氮 and adjusts the nitrogen production amount of the nitrogen production unit according to the nitrogen demand V 氮 .

[0074] In a specific embodiment, the determination of the nitrogen demand V of the nitrogen production unit according to the fluctuating power supply signal 氮 includes: calculating V according to formula (1) 氮 ;

[0075] V 氮 = n×0.000418×m×I×t×η, formula (1);

[0076] wherein, m is the number of electrolytic cells of the electrolytic hydrogen production device; I is the current signal, with the unit of A; t is the power-on time, with the unit of h; η is the current efficiency, with the unit of %; n is 2 - 4, preferably 2 - 3.5.

[0077] In a specific embodiment, the adjustment of the nitrogen production amount of the nitrogen production unit according to the nitrogen demand V 氮 includes:

[0078] By adjusting the gas flow rate and power of the compressor, the power of the dryer, the nitrogen flow rate of the adsorption separation device, the valve opening degree, and the adsorption and desorption timing sequence, the outlet purity of nitrogen is maintained at 99-99.99%.

[0079] In the present disclosure, the hydrogen production and nitrogen production are calculated through the formulas in the above embodiments. At the same time, the control unit adjusts the process parameter conditions of the nitrogen production unit to obtain the calculated nitrogen production and ensure the nitrogen outlet purity. The above embodiments can further improve the overall operation accuracy of the system, have high energy utilization efficiency, and the subsequent ammonia synthesis reaction only needs to adapt to the fluctuations of the raw material gas, with good reaction effects, high outlet gas purity, high overall system efficiency without increasing equipment investment. At the same time, the catalytic deoxidation unit in the system can further completely remove the oxygen impurities in hydrogen and nitrogen, avoiding the problem of excessive impurities caused by the volatility of renewable energy.

[0080] In a specific embodiment, the purity of hydrogen in the mixed raw material gas is above 97%, preferably above 98%; the purity of nitrogen in the mixed raw material gas is above 99%, preferably above 99.5%.

[0081] In a specific embodiment, the volume content of nitrogen in the mixed raw material gas is above 50%, preferably 50-75%, more preferably 65-75%; the volume content of hydrogen in the mixed raw material gas is below 50%, preferably 25-50%, more preferably 25-35%; the dew point of the mixed raw material gas is below -65°C, preferably -65 to -80°C, more preferably -70 to -76°C.

[0082] The present invention will be further described below through examples, but the present invention is not limited thereby.

[0083] Example 1

[0084] The process system of this example includes: a renewable energy power generation unit 1, a control unit 2, a hydrogen production unit 3, a nitrogen production unit 4, a catalytic deoxidation unit 5, a dehydration unit 6, a booster 7, and an ammonia synthesis unit 8.

[0085] a. Generate electricity through the renewable power generation unit 1 and generate a fluctuating power signal;

[0086] b. Use the electrolytic hydrogen production rectifier power supply and the control unit to receive the fluctuating power signal from the renewable energy power generation unit, electrolyze to produce hydrogen according to the fluctuating power signal, and adjust the hydrogen production amount of the electrolytic hydrogen production unit in real time. Among them, the purity of the produced hydrogen is 99.8%;

[0087] c. Feed the air raw material gas into the nitrogen production unit to produce nitrogen. According to the fluctuating power supply signal and the hydrogen flow signal, use the control unit to adjust in real time the gas flow and power of the compressor in the nitrogen production unit, the power of the dryer, the nitrogen flow of the adsorption separation device, the valve opening degree, and the adsorption and desorption timing sequence, control the nitrogen purity to 99.9%, and control the flow ratio of nitrogen to hydrogen to 3:1;

[0088] d. Feed the hydrogen in step b and the nitrogen in step c into the catalytic deoxidation unit for deoxidation treatment, and then into the dehydration unit for dehydration treatment to obtain a mixed raw material gas. Among them, the volume content of hydrogen in the mixed raw material gas is 35.7%, the volume content of nitrogen in the mixed raw material gas is 64.2%, and the dew point of the mixed raw material gas is -76°C;

[0089] e. Feed the mixed raw material gas in step d into the ammonia synthesis unit for ammonia synthesis reaction to obtain ammonia.

[0090] Comparative Example 1

[0091] The process system of this comparative example includes: a renewable energy power generation unit, a hydrogen production unit, a nitrogen production unit, a dehydration unit, a booster, and an ammonia synthesis unit. Among them, the hydrogen production unit includes a hydrogen production controller, and the nitrogen production unit uses a conventional pressure swing adsorption nitrogen production device.

[0092] a. Generate electricity through the renewable power generation unit and generate a fluctuating power supply signal;

[0093] b. Make the hydrogen production controller of the hydrogen production unit receive the power generation of the renewable power generation unit and the fluctuating power supply signal to electrolyze and produce hydrogen. Among them, the purity of the produced hydrogen is 99.8%;

[0094] c. Feed the air raw material gas into the pressure swing adsorption nitrogen production device to produce nitrogen, and the nitrogen purity is 99.9%. Among them, the flow ratio of nitrogen to hydrogen is 2.2 - 2.8:1;

[0095] d. Feed the hydrogen in step b and the nitrogen in step c into the dehydration unit for dehydration treatment to obtain a mixed raw material gas, and feed the mixed raw material gas into the ammonia synthesis unit for ammonia synthesis reaction to obtain ammonia.

[0096] Test Example

[0097] In Example 1 and Comparative Example 1, the nitrogen purity, the nitrogen production rate of the carbon molecular sieve, and the recovery rate are tested in the following manner:

[0098] The nitrogen purity is determined according to the test standards GB / T 3864 - 2008 and GB / T 8979 - 2008;

[0099] The nitrogen production rate of the carbon molecular sieve = the amount of product nitrogen per unit time / the mass of the used molecular sieve;

[0100] Recovery rate = (Product nitrogen gas volume / Total nitrogen gas volume entering the device) × 100%.

[0101] Table 1

[0102]

[0103] It can be seen from the test results in Table 1 that the ammonia synthesis system provided by the present invention has high adaptability to the fluctuations of renewable energy. After the system is linked, it can adjust and precisely control the hydrogen production, nitrogen production, and process parameter conditions in real time. The overall operation accuracy of the system is high, the energy utilization efficiency is high. For the subsequent ammonia synthesis reaction, it only needs to adapt to the fluctuations of the feed gas, with good reaction effect, high purity of the outlet gas, and low process energy consumption.

[0104] It can be seen from the test results of Example 1 that compared with Comparative Example 1, when synthesizing ammonia using the system and method provided by the present invention, while achieving the same nitrogen purity, it can precisely control the flow ratio of nitrogen to hydrogen entering the ammonia synthesis unit, significantly improve the nitrogen production rate of carbon molecular sieve and nitrogen recovery rate, effectively reduce the nitrogen production energy consumption. At the same time, the catalytic deoxidation unit in the system can further completely remove the oxygen impurities in hydrogen and nitrogen, avoiding the problem of excessive impurities caused by the volatility of renewable energy. The prepared nitrogen and hydrogen have high purity and good ammonia synthesis reaction effect. In the comparative example, a conventional pressure swing adsorption nitrogen production device is used in the nitrogen production unit for nitrogen production, which cannot be effectively linked with the hydrogen production unit, has poor adaptability to the fluctuations of renewable energy, and the flow ratio of nitrogen to hydrogen is always in a fluctuating state, resulting in low nitrogen production rate of carbon molecular sieve and nitrogen recovery rate, and the energy utilization efficiency is lower than that of Example 1.

[0105] The preferred embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0106] In addition, it should be noted that among the various specific technical features described in the above specific embodiments, they can be combined in any suitable manner without conflict. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

[0107] In addition, any combination can be made between various different embodiments of the present invention, as long as it does not violate the idea of the present invention, it should also be regarded as the content disclosed by the present invention.

Claims

1. A system for preparing synthetic ammonia, characterized in that: The system includes: a renewable energy power generation unit, a control unit, an electrolytic hydrogen production unit, a nitrogen production unit, a catalytic deoxygenation unit, a dehydration unit and a synthetic ammonia unit; The control unit is respectively connected to the renewable energy power generation unit, the nitrogen production unit and the electrolytic hydrogen production unit by signal, and is used to receive the fluctuating power supply signal of the renewable energy power generation unit, and adjust the hydrogen production amount of the electrolytic hydrogen production unit and the nitrogen production amount of the nitrogen production unit according to the fluctuating power supply signal; The catalytic deoxygenation unit comprises a first mixed gas inlet and a first mixed gas outlet; the hydrogen outlet of the hydrogen production unit and the nitrogen outlet of the nitrogen production unit are respectively connected to the first mixed gas inlet of the catalytic deoxygenation unit; the first mixed gas outlet of the catalytic deoxygenation unit is connected to the inlet of the dehydration unit; The gas outlet of the dehydration unit is communicated with the second mixed gas inlet of the synthetic ammonia unit.

2. The system according to claim 1, characterized in that The electrolytic hydrogen production unit comprises a water electrolysis hydrogen production device, a gas-liquid separation device and a pure water device; the electrolytic hydrogen production device comprises a pure water inlet and a hydrogen outlet, and the hydrogen outlet of the electrolytic hydrogen production device is connected to the inlet of the gas-liquid separation device; The liquid phase outlet of the gas-liquid separation device is communicated with the inlet of the pure water device, and the outlet of the pure water device is communicated with the pure water inlet of the electrolytic hydrogen production device; The water electrolysis hydrogen production device comprises one or more of an alkaline porous diaphragm electrolyzer, an alkaline ion membrane electrolyzer, a proton exchange membrane electrolyzer, an anion exchange membrane electrolyzer or a solid oxide electrolyzer; The gas-liquid separation device includes one or more of a horizontal gas-liquid separation device or a vertical gas-liquid separation device.

3. The system according to claim 1, characterized in that The nitrogen production unit comprises one or more of a cryogenic air separation nitrogen production device, a pressure swing adsorption nitrogen production device or a membrane separation nitrogen production device. Preferably, the nitrogen production unit is a pressure swing adsorption nitrogen production device; The nitrogen production unit comprises an air compression and purification device and an adsorption and separation device; the compressed air outlet of the air compression and purification device is connected to the feed inlet of the adsorption and separation device; The air compression purification device comprises a compressor, a dryer, a precision filter and an air buffer tank connected in sequence; The adsorption separation device comprises one or more adsorption separation towers arranged in parallel.

4. The system according to claim 3, characterized in that The control unit is respectively connected to the compressor, the dryer and the adsorption separation device by signals, and is used to adjust the gas flow and power of the compressor, the power of the dryer, the nitrogen flow, valve opening and adsorption and desorption timing of the adsorption separation device to maintain the outlet purity of nitrogen at 99-99.99%.

5. The system according to claim 3, characterized in that The dehydration unit comprises a TSA dehydration device; the condensed water outlet of the TSA dehydration device is connected to the inlet of the pure water device; Preferably, the TSA dehydration device comprises one or more adsorption towers arranged in parallel.

6. A method for preparing synthetic ammonia using the system according to any one of claims 1 to 5, wherein: The method includes: generating electricity through a renewable power generation unit and producing a fluctuating power signal; The electrolytic hydrogen production unit uses the electricity generated by the renewable power generation unit to perform electrolysis to produce hydrogen; Allow air to enter the nitrogen production unit to prepare nitrogen; The hydrogen from the electrolytic hydrogen production unit and the nitrogen from the nitrogen production unit enter the catalytic deoxidation unit for deoxidation treatment, and then enter the dehydration unit for dehydration treatment; allowing the mixed raw gas obtained from the dehydration unit to enter the synthetic ammonia unit for synthetic ammonia reaction; Wherein, the hydrogen production amount of the hydrogen production unit by electrolysis and the nitrogen production amount of the nitrogen production unit are adjusted according to the fluctuating power supply signal.

7. The method according to claim 6, wherein: The step of adjusting the hydrogen production amount of the electrolytic hydrogen production unit and the nitrogen production amount of the nitrogen production unit according to the fluctuating power supply signal comprises: Adopting an electrolytic hydrogen production rectifier power supply and control unit to receive a fluctuating power supply signal of the renewable energy power generation unit, and adjusting the hydrogen production amount of the electrolytic hydrogen production unit according to the fluctuating power supply signal; A control unit is used to receive the fluctuating power supply signal of the renewable energy power generation unit, and the nitrogen demand V of the nitrogen production unit is determined according to the fluctuating power supply signal. 氮 , and according to the nitrogen requirement V 氮 The nitrogen production amount of the nitrogen production unit is adjusted.

8. The method according to claim 6, wherein: The nitrogen requirement V of the nitrogen production unit is determined according to the fluctuating power supply signal 氮 Including: Calculate V according to formula (1) 氮 ; V 氮 =n×0.000418×m×I×t×η, Formula (1); Among them, m is the number of electrolysis chambers of the electrolytic hydrogen production device; I is the current signal, the unit is A; t is the power-on time, the unit is h; η is the current efficiency, the unit is %; n is 2 to 4.

9. The method according to claim 4 or 6, wherein: The nitrogen requirement V 氮 Adjusting the nitrogen production amount of the nitrogen production unit comprises: The outlet purity of nitrogen is maintained at 99-99.99% by adjusting the gas flow and power of the compressor, the power of the dryer, the nitrogen flow of the adsorption separation device, the valve opening and the adsorption and desorption timing.

10. The method according to claim 6, wherein: The purity of the hydrogen in the mixed raw gas is above 97%; the purity of the nitrogen in the mixed raw gas is above 99%; The volume content of nitrogen in the mixed raw gas is more than 50%; the volume content of hydrogen in the mixed raw gas is less than 50%; and the dew point of the mixed raw gas is less than -65°C.

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