A synthetic ammonia system based on a volatile hydrogen source and its control method

Abstract

An ammonia synthesis system based on a volatile hydrogen source and its control method. Since the nitrogen supply device is used to introduce nitrogen into the hydrogen storage container to maintain the pressure stability in the hydrogen storage container, the ammonia synthesis system keeps the amount of hydrogen provided by the hydrogen supply device in itself stable; in addition, since the hydrogen supply device with fluctuating hydrogen supply amount can be, for example, a hydrogen production device that uses green electric energy to produce hydrogen, the ammonia synthesis system based on a volatile hydrogen source provided by the present invention can not only meet the traditional application scenarios of raw material synthesis gas, but also be well applicable to the application scenario of using green electric energy to produce hydrogen to obtain raw material hydrogen. Even under the fluctuation of the full load range of green electric energy, stable production of ammonia can be ensured; compared with the traditional gaseous hydrogen storage ammonia synthesis process, the system can achieve a 100% reuse rate without decompression of gaseous hydrogen storage, thus effectively ensuring the technical economy and operation and maintenance economy of the device.

Description

Technical Field

[0001] The present invention relates to the technical field of ammonia synthesis, and more specifically, to an ammonia synthesis system based on a fluctuating hydrogen source and a control method thereof. Background Art

[0002] Traditional and mature ammonia synthesis processes use fossil energy sources (coal, oil, natural gas, petrochemical tail gas, etc.) as raw materials to produce ammonia synthesis gas, and the source of synthesis gas is relatively stable. The ammonia synthesis process can be adjusted according to the quality parameters (temperature, pressure, flow rate, composition, etc.) of the ammonia synthesis gas to meet the production requirements.

[0003] At present, in order to accelerate the promotion of industrial green development, effectively promote energy conservation and consumption reduction, and achieve cost reduction and efficiency increase, various ammonia production technologies have received more and more extensive attention, such as using green electric energy to produce hydrogen and then synthesize ammonia. However, there is a contradiction between the instability of the hydrogen supply provided by the hydrogen production device using green electric energy and the high stability requirement of the traditional ammonia synthesis for the hydrogen source. Breaking through the above technical bottleneck has become an urgent technical problem to be solved in this field. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide an ammonia synthesis system based on a fluctuating hydrogen source and a control method thereof. In addition to being able to meet the traditional raw material synthesis gas application scenarios, it can also be well applicable to the ammonia synthesis application scenarios where the hydrogen supply fluctuates, such as the application scenarios of using unstable (regular and irregular fluctuations) green electric energy such as wind power, photovoltaic power, and hydropower to produce hydrogen as raw material hydrogen and then synthesize ammonia. Even when the green electric energy fluctuates within the full load range of 0 - 100%, stable ammonia synthesis production can be ensured.

[0005] One aspect of the present application provides an ammonia synthesis system based on a fluctuating hydrogen source, including:

[0006] A hydrogen supply device, the hydrogen supply provided by which fluctuates;

[0007] A hydrogen storage container for storing the hydrogen provided by the hydrogen supply device;

[0008] A nitrogen supply device for communicating with the hydrogen storage container to introduce nitrogen into the hydrogen storage container to keep the pressure in the hydrogen storage container stable.

[0009] Optionally, the hydrogen storage container includes a plurality of hydrogen storage containers for storing hydrogen at different pressures, and the number is greater than or equal to two; the nitrogen supply device is respectively connected to each hydrogen storage container to ensure the pressure stability in each hydrogen storage container by supplementing nitrogen.

[0010] Optionally, the hydrogen storage container includes a low-pressure hydrogen storage container, a medium-pressure hydrogen storage container, and a high-pressure hydrogen storage container.

[0011] Optionally, the ammonia synthesis system based on a fluctuating hydrogen source further includes:

[0012] A combined compression system; the combined compression system at least includes a hydrogen compressor unit; the gas inlet of the hydrogen compressor unit is connected to a hydrogen supply device, and the outlet is connected to an ammonia synthesis unit.

[0013] Optionally, the low-pressure hydrogen storage container is connected to the hydrogen outlet of the hydrogen supply device; the medium-pressure hydrogen storage container is connected to the inter-stage gas outlet of the hydrogen compressor unit; the high-pressure hydrogen storage container is connected to the gas outlet of the hydrogen compressor unit.

[0014] Optionally, the nitrogen supply device introduces nitrogen gas into each hydrogen storage container from the bottom.

[0015] Optionally, the nitrogen supply device is an air separation device, and the air separation device includes: a nitrogen production device and / or a backup nitrogen system.

[0016] Optionally, when the nitrogen supply device is the nitrogen production device, there are two flow paths for the nitrogen gas led out from the nitrogen production device. One is connected to the hydrogen storage container, and the other provides a nitrogen source for the ammonia synthesis reaction.

[0017] Optionally, the low-pressure hydrogen storage container is a vertical pressure vessel or a spherical pressure vessel; hydrogen can flow bidirectionally at equal pressure between the low-pressure hydrogen storage container and the pipeline at the gas inlet of the hydrogen compressor unit.

[0018] Optionally, the medium-pressure hydrogen storage container is a vertical high-pressure hydrogen storage container; hydrogen can flow bidirectionally at equal pressure between the medium-pressure hydrogen storage container and the inter-stage of the hydrogen compressor unit.

[0019] Optionally, the high-pressure hydrogen storage container is a high-pressure hydrogen storage tube bundle; hydrogen can flow bidirectionally at equal pressure between the high-pressure hydrogen storage container and the pipeline at the gas outlet of the hydrogen compressor unit.

[0020] Optionally, the combined compression system further includes a nitrogen compressor unit and a recycle gas compressor unit; the gas inlet of the nitrogen compressor unit is connected to the nitrogen supply device, and the outlet is connected to the ammonia synthesis unit; the recycle gas compressor unit is used to compress the recycle gas discharged from the ammonia synthesis unit for recycling.

[0021] Optionally, the ammonia synthesis system based on a fluctuating hydrogen source further includes:

[0022] A control center for controlling the combined compression system, the nitrogen supply device, and the ammonia synthesis unit.

[0023] Optionally, the applicable application scenarios of the ammonia synthesis system based on a fluctuating hydrogen source include ammonia synthesis from hydrogen produced by new energy, ammonia synthesis from hydrogen produced by fixed-bed gasification, and ammonia synthesis from hydrogen produced by plasma gasification.

[0024] On the other hand, the present application provides a control method for an ammonia synthesis system based on a volatile hydrogen source. The ammonia synthesis system is the ammonia synthesis system described in any one of the previous aspects of the present application. The control method is applied to a control center in the ammonia synthesis system. The control method includes:

[0025] Judge whether the pressure of the hydrogen storage container in the ammonia synthesis system is less than a preset pressure value;

[0026] If the pressure of the hydrogen storage container is less than the preset pressure value, first control the nitrogen supply device in the ammonia synthesis system to introduce nitrogen into the hydrogen storage container, and then return to execute the step of judging whether the pressure of the hydrogen storage container in the ammonia synthesis system is less than the preset pressure value.

[0027] Optionally, before judging whether the pressure of the hydrogen storage container in the ammonia synthesis system is less than the preset pressure value, it further includes:

[0028] Judge whether the amount of hydrogen provided by the hydrogen supply device in the ammonia synthesis system fluctuates;

[0029] If the amount of hydrogen provided by the hydrogen supply device fluctuates, execute the step of judging whether the pressure of the hydrogen storage container in the ammonia synthesis system is less than the preset pressure value.

[0030] Optionally, it further includes:

[0031] Judge whether the hydrogen / nitrogen ratio input to the ammonia synthesis unit in the ammonia synthesis system is greater than a set ratio;

[0032] If the hydrogen / nitrogen ratio is greater than the set ratio, increase the amount of nitrogen introduced into the ammonia synthesis unit by the nitrogen supply device according to the difference between the hydrogen / nitrogen ratio and the set ratio.

[0033] Optionally, if the hydrogen / nitrogen ratio is less than the set ratio, it further includes:

[0034] Reduce the amount of nitrogen introduced into the ammonia synthesis unit by the nitrogen supply device according to the difference between the hydrogen / nitrogen ratio and the set ratio.

[0035] Optionally, if the ammonia synthesis system includes a nitrogen compressor unit, increasing or decreasing the amount of nitrogen introduced into the ammonia synthesis unit by the nitrogen supply device includes:

[0036] Increase or decrease the working load of the nitrogen compressor unit.

[0037] The present invention provides an ammonia synthesis system based on a volatile hydrogen source, comprising: a hydrogen supply device, the hydrogen quantity provided by the hydrogen supply device fluctuates; a hydrogen storage container for storing the hydrogen provided by the hydrogen supply device; a nitrogen supply device for communicating with the hydrogen storage container to introduce nitrogen into the hydrogen storage container to keep the pressure in the hydrogen storage container stable. Since the nitrogen supply device is used to introduce nitrogen into the hydrogen storage container to keep the pressure in the hydrogen storage container stable, the ammonia synthesis system makes the hydrogen quantity provided by the hydrogen supply device in itself stable; in addition, since the hydrogen supply device with fluctuating hydrogen quantity can be, for example, a hydrogen production device using green electric energy, the ammonia synthesis system based on a volatile hydrogen source provided by the present invention, in addition to being able to meet the traditional raw material synthesis gas application scenarios, can also be well applicable to the ammonia synthesis scenarios with fluctuating hydrogen supply, such as the application scenarios of synthesizing ammonia by using unstable (regular and irregular fluctuations) green electric energy such as wind power, photovoltaic power and hydropower to produce raw material hydrogen, and even under the full load range fluctuation of green electric energy from 0 to 100%, can ensure stable production of ammonia; compared with the traditional gaseous hydrogen storage ammonia synthesis process, the system provided by the present invention can achieve a 100% reuse rate without pressure reduction of gaseous hydrogen storage, that is, there is no pressure loss for the stored and reused hydrogen, thus effectively ensuring the technical economy and operation and maintenance economy of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of the ammonia synthesis system based on a volatile hydrogen source provided by an embodiment of the present invention;

[0039] Figures 2 - 4 They are respectively flow schematic diagrams of three implementation manners of the control method of the ammonia synthesis system based on a volatile hydrogen source provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0040] Next, the technical solutions of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work shall fall within the protection scope of the present invention.

[0041] The present invention provides an ammonia synthesis system based on a volatile hydrogen source, comprising:

[0042] a hydrogen supply device, the hydrogen quantity provided by the hydrogen supply device fluctuates;

[0043] a hydrogen storage container for storing the hydrogen provided by the hydrogen supply device;

[0044] a nitrogen supply device for communicating with the hydrogen storage container to introduce nitrogen into the hydrogen storage container to keep the pressure in the hydrogen storage container stable.

[0045] In the present invention, the hydrogen storage container preferably comprises a plurality of hydrogen storage containers for storing hydrogen at different pressures, and the number of the plurality of hydrogen storage containers is preferably greater than or equal to two; the nitrogen supply device is respectively connected to each hydrogen storage container to ensure the pressure stability in each hydrogen storage container by supplementing nitrogen.

[0046] In a preferred embodiment of the present invention, the hydrogen storage container preferably includes a low-pressure hydrogen storage container, a medium-pressure hydrogen storage container, and a high-pressure hydrogen storage container.

[0047] In the present invention, the ammonia synthesis system based on a fluctuating hydrogen source preferably further comprises:

[0048] A combined compression system; the combined compression system at least comprises a hydrogen compression unit; the gas inlet of the hydrogen compression unit is connected to the hydrogen supply device, and the outlet is connected to the ammonia synthesis unit.

[0049] In the present invention, the low-pressure hydrogen storage container is connected to the hydrogen outlet of the hydrogen supply device; the medium-pressure hydrogen storage container is connected to the inter-stage gas outlet of the hydrogen compression unit; the high-pressure hydrogen storage container is connected to the gas outlet of the hydrogen compression unit.

[0050] In the present invention, the nitrogen supply device introduces nitrogen into each hydrogen storage container from the bottom.

[0051] In the present invention, the nitrogen supply device may only include an air separation device; the nitrogen supply device may also include an air separation device and a nitrogen storage device; wherein, the air separation device includes: a nitrogen production device and / or a backup nitrogen system.

[0052] In a preferred embodiment of the present invention, the nitrogen supply device is the nitrogen production device, and there are two flow paths for the nitrogen led out from the nitrogen production device, one of which is communicated with the hydrogen storage container, and the other provides a nitrogen source for the ammonia synthesis reaction.

[0053] It should be noted that if the nitrogen supply device only includes an air separation device, both flow paths are led out from the air separation device. At this time, it is preferred that each device in the air separation device leads out two above-mentioned flow paths; if the nitrogen supply device includes an air separation device and a nitrogen storage device, the two flow paths can be led out from the nitrogen storage device and the air separation device respectively. At this time, it is preferred that each device in the air separation device leads out one corresponding above-mentioned flow path.

[0054] In the present invention, the low-pressure hydrogen storage container is preferably a vertical pressure vessel or a spherical pressure vessel; hydrogen can flow bidirectionally at equal pressure between the low-pressure hydrogen storage container and the pipeline at the gas inlet of the hydrogen compression unit.

[0055] In the present invention, the medium-pressure hydrogen storage container is preferably a vertical high-pressure hydrogen storage container; hydrogen can flow isobarically and bidirectionally between the medium-pressure hydrogen storage container and the inter-stage of the hydrogen compressor unit.

[0056] In the present invention, the high-pressure hydrogen storage container is a high-pressure hydrogen storage tube bundle; hydrogen can flow isobarically and bidirectionally between the high-pressure hydrogen storage container and the pipeline at the gas outlet of the hydrogen compressor unit.

[0057] In the present invention, the combined compression system preferably further includes a nitrogen compressor unit and a recycle gas compressor unit; the gas inlet of the nitrogen compressor unit is connected to the nitrogen supply device, and the outlet is connected to the ammonia synthesis unit; the recycle gas compressor unit is used to compress the recycle gas discharged from the ammonia synthesis unit for recycling.

[0058] In the present invention, the ammonia synthesis system based on a fluctuating hydrogen source preferably further includes:

[0059] A control center for controlling the combined compression system, the nitrogen supply device, and the ammonia synthesis unit.

[0060] In the present invention, the application scenarios applicable to the ammonia synthesis system based on a fluctuating hydrogen source preferably include ammonia synthesis from hydrogen produced by new energy, ammonia synthesis from hydrogen produced by fixed-bed gasification, and ammonia synthesis from hydrogen produced by plasma gasification.

[0061] Since the nitrogen supply device is used to introduce nitrogen into the hydrogen storage container to maintain the pressure stability in the hydrogen storage container, the ammonia synthesis system makes the amount of hydrogen provided by the hydrogen supply device in itself remain stable; in addition, since the hydrogen supply device with a fluctuating hydrogen supply amount can be, for example, a hydrogen production device that uses green electric energy to produce hydrogen, the ammonia synthesis system based on a fluctuating hydrogen source provided by the present invention, in addition to being able to meet the traditional raw material syngas application scenarios, can also be well applicable to the ammonia synthesis scenarios with a fluctuating hydrogen supply amount, such as the application scenarios of producing raw material hydrogen by using unstable (regular and irregular fluctuations) green electric energy such as wind power, photovoltaic, and hydropower to synthesize ammonia. Even when the green electric energy fluctuates in the full load range of 0 to 100%, stable ammonia synthesis can be ensured; compared with the traditional gaseous hydrogen storage ammonia synthesis process, the system provided by the present invention can achieve a 100% reuse rate without pressure reduction of gaseous hydrogen storage, and there is no pressure loss for the hydrogen stored and reused, effectively ensuring the technical economy and operation and maintenance economy of the device.

[0062] Taking the green power hydrogen production ammonia synthesis system as an example, the above-mentioned ammonia synthesis system based on a fluctuating hydrogen source will be further explained as follows:

[0063] See Figure 1 as shown Figure 1Schematic diagram of the ammonia synthesis system based on a fluctuating hydrogen source provided by an embodiment of the present invention; wherein, 11 is a new energy power supply unit, 10 is a combined compression system, 01 is a hydrogen production device, 02 is an air separation device, 03 is a hydrogen compressor unit, 04 is a nitrogen compressor unit, 05 is a recycle gas compressor unit, 06 is an ammonia synthesis unit, 07 is a low-pressure hydrogen storage container, 08 is a medium-pressure hydrogen storage container, 09 is a high-pressure hydrogen storage container, and 12 is a control center.

[0064] On this basis, the ammonia synthesis system based on a fluctuating hydrogen source as a whole includes:

[0065] The combined compression system 10; the hydrogen compressor unit 03, the nitrogen compressor unit 04, and the recycle gas compressor unit 05 are provided inside the combined compression system 10;

[0066] The hydrogen production device 01 is connected to the gas inlet of the hydrogen compressor unit 03;

[0067] The new energy power supply unit 11 that provides electric energy for the hydrogen production device 01;

[0068] The air separation device 02 connected to the gas inlet of the nitrogen compressor unit 04; the air separation device 02 is provided with an air inlet;

[0069] The ammonia synthesis unit 06 is respectively connected to the gas outlet of the hydrogen compressor unit 03 and the gas outlet of the nitrogen compressor unit 04; the ammonia synthesis unit 06 is provided with a recycle gas outlet and a recycle gas inlet, and is respectively connected to the recycle gas compressor unit 05;

[0070] The low-pressure hydrogen storage container 07, the medium-pressure hydrogen storage container 08, and the high-pressure hydrogen storage container 09 are respectively connected to the air separation device 02; the low-pressure hydrogen storage container 07 is connected to the hydrogen outlet of the hydrogen production device 01, the medium-pressure hydrogen storage container 08 is connected to the inter-stage gas outlet of the hydrogen compressor unit 03, and the high-pressure hydrogen storage container 09 is connected to the gas outlet of the hydrogen compressor unit 03.

[0071] The ammonia synthesis system based on a fluctuating hydrogen source provided by the present invention can solve the problem of energy loss in the processes of hydrogen storage and reuse in the process of synthesizing ammonia with unstable green electric energy for hydrogen production.

[0072] In the present invention, the ammonia synthesis system based on a fluctuating hydrogen source includes a combined compression system 10, a hydrogen production device 01, a new energy power supply unit 11, an air separation device 02, an ammonia synthesis unit 06, a low-pressure hydrogen storage container 07, a medium-pressure hydrogen storage container 08, and a high-pressure hydrogen storage container 09.

[0073] In the present invention, a hydrogen compressor unit 03, a nitrogen compressor unit 04 and a recycle gas compressor unit 05 are provided inside the combined compression system 10. Among them, the hydrogen compressor unit 03 is provided with a gas inlet, a gas outlet and an isobaric bidirectional flow pipeline. The above-mentioned gas inlet (hydrogen inlet) is connected to the hydrogen production device 01; the nitrogen compressor unit 04 is provided with a gas inlet and a gas outlet. The above-mentioned gas inlet (nitrogen inlet) is connected to the air separation device 02; the recycle gas compressor unit 05 is provided with a recycle gas inlet and a recycle gas outlet. Among them, the recycle gas inlet of the recycle gas compressor unit 05 is connected to the recycle gas outlet of the ammonia synthesis unit 06, and the recycle gas outlet of the recycle gas compressor unit 05 is connected to the recycle gas inlet of the ammonia synthesis unit 06.

[0074] In the present invention, the hydrogen production device 01 is used to produce hydrogen. In the present invention, the pressure of the hydrogen produced by the hydrogen production device is preferably 1.5 MPa to 4.5 MPa.

[0075] In the present invention, the new energy power supply unit 11 supplies electric energy to the hydrogen production device 01; the new energy power supply unit preferably includes, but is not limited to, a wind power new energy power supply unit, a photovoltaic new energy power supply unit or a hydropower new energy power supply unit.

[0076] There is a contradiction between the instability of the above-mentioned green hydrogen production and the high stability requirements of the traditional ammonia synthesis for the hydrogen source. The key of the present invention is to provide an ammonia synthesis system based on a fluctuating hydrogen source, which can provide an energy-saving, stable and reliable technology for the hydrogen storage link in the field of green hydrogen production for ammonia synthesis, and provide an energy-saving solution for the contradiction and technical bottleneck between the instability of green hydrogen production and the high stability requirements of the traditional ammonia synthesis for the hydrogen source.

[0077] In the present invention, the air separation device 02 is used to prepare nitrogen. It is provided with an air inlet and a nitrogen outlet. The air separation device 02 is connected to the gas inlet of the nitrogen compressor unit 04 through the nitrogen outlet.

[0078] In the present invention, the air separation device 02 includes: a nitrogen production device and / or a backup nitrogen system. Among them, the nitrogen production device is used to provide nitrogen for the hydrogen storage container and the nitrogen outlet under normal circumstances, and the backup nitrogen system is used to provide nitrogen for the hydrogen storage container and the nitrogen outlet when the nitrogen production device stops, so as to maintain the normal operation of the ammonia synthesis system.

[0079] In the present invention, the pressure of the high-pressure nitrogen after being pressurized by the nitrogen compressor unit 04 is preferably 14 MPa to 22 MPa.

[0080] In the present invention, the ammonia synthesis unit 06 is used to produce ammonia; it is provided with a hydrogen inlet, a nitrogen inlet, a recycle gas outlet and a recycle gas inlet; wherein, the ammonia synthesis unit 06 is connected to the gas outlet of the hydrogen compressor unit 03 through the hydrogen inlet, and is connected to the gas outlet of the nitrogen compressor unit 04 through the nitrogen inlet; the recycle gas outlet and the recycle gas inlet of the ammonia synthesis unit 06 are respectively connected to the recycle gas compressor unit 05.

[0081] In the present invention, the low-pressure hydrogen storage container 07, the medium-pressure hydrogen storage container 08 and the high-pressure hydrogen storage container 09 are respectively connected to the air separation unit 02; at the same time, the low-pressure hydrogen storage container 07 is connected to the hydrogen outlet of the hydrogen production device 01, the medium-pressure hydrogen storage container 08 is directly connected to the intermediate stage of the hydrogen compressor unit 03, and the high-pressure hydrogen storage container 09 is connected to the gas outlet of the hydrogen compressor unit 03; when the pressure in the low-pressure hydrogen storage container 07, the medium-pressure hydrogen storage container 08 or the high-pressure hydrogen storage container 09 is less than the pressure in the corresponding connecting pipeline, hydrogen flows from the corresponding connecting pipeline into the corresponding hydrogen storage container until the pressures of the two are equal; when the pressure in the corresponding hydrogen storage container is greater than the pressure in the corresponding connecting pipeline, hydrogen flows from the corresponding hydrogen storage container into the corresponding connecting pipeline until the pressures of the two are equal.

[0082] In the present invention, the low-pressure hydrogen storage container 07 is preferably a vertical pressure vessel or a spherical pressure vessel, and the storage pressure is applicable to various types of electrolytic hydrogen production processes such as ALK, PEM, AME, etc., and the hydrogen storage pressure is preferably 1.5 MPa to 4.5 MPa; hydrogen can flow bidirectionally at equal pressure between the low-pressure hydrogen storage container 07 and the pipeline at the gas inlet of the hydrogen compressor unit 03.

[0083] In the present invention, the medium-pressure hydrogen storage container 08 is preferably a vertical high-pressure hydrogen storage container, and medium-pressure hydrogen is led out from the intermediate stage of the ammonia synthesis hydrogen compressor, and the hydrogen storage pressure is preferably 6 MPa to 12 MPa; hydrogen can flow bidirectionally at equal pressure between the medium-pressure hydrogen storage container 08 and the intermediate stage of the hydrogen compressor unit 03.

[0084] In the present invention, the high-pressure hydrogen storage container 09 is preferably a high-pressure hydrogen storage tube bundle, and the storage pressure meets the technical requirements of traditional various types of ammonia synthesis processes, and the hydrogen storage pressure is preferably 12 MPa to 22 MPa; hydrogen can flow bidirectionally at equal pressure between the high-pressure hydrogen storage container 09 and the pipeline at the gas outlet of the hydrogen compressor unit 03.

[0085] The present invention adopts the above-mentioned high, medium and low pressure coupled hydrogen storage: by reasonably allocating the proportions of hydrogen storage facilities at three levels, namely hydrogen storage in the hydrogen production device (low pressure), intermediate hydrogen storage in the compression system (medium pressure), and hydrogen storage in the ammonia synthesis system (high pressure), a hydrogen storage scheme with the optimal technical economy can be formulated for various types of ammonia synthesis scenarios, which can not only ensure the technical reliability of hydrogen production from new energy for ammonia synthesis, but also ensure the optimal technical economy; in actual production, hierarchical hydrogen storage can better solve the stability of the system pressure during the process from electrolytic hydrogen production, hydrogen pressurization to syngas configuration and use, reduce the fluctuation impact on equipment, and improve the service life of the device.

[0086] In the present invention, the air separation device 02 can ensure the stable output of hydrogen in the low-pressure hydrogen storage container 07, the medium-pressure hydrogen storage container 08 and the high-pressure hydrogen storage container 09 respectively by supplementing nitrogen, so as to ensure the stable supply of hydrogen volume, and preferably realized by the nitrogen production device in the air separation device 02.

[0087] The present invention can realize the following process: isobaric hydrogen storage process: when the hydrogen in the hydrogen storage container is reused, nitrogen from the nitrogen supply device, such as the air separation device 02, is introduced into the container from the bottom of the hydrogen storage container. Relying on the characteristic that the density of nitrogen is greater than that of hydrogen, the release pressure of the reused hydrogen is maintained unchanged, achieving the energy-saving effect in the hydrogen storage and reuse process; in addition, the nitrogen introduced into the system during the isobaric hydrogen storage process finally enters the ammonia synthesis unit 06 after being mixed with hydrogen, and the remaining nitrogen gap is supplemented and precisely controlled by the nitrogen compressor unit 04.

[0088] In the present invention, the green power hydrogen production isobaric energy-saving hydrogen storage ammonia synthesis system preferably further includes:

[0089] A control center 12 that can respectively control the operation of the combined compression system 10, the hydrogen production device 01, the new energy power supply unit 11, the air separation device 02 and the ammonia synthesis unit 06.

[0090] The ammonia synthesis system based on the fluctuating hydrogen source provided by the present invention has the following beneficial effects:

[0091] (1) Solve the contradiction and bottleneck between the fluctuation of hydrogen supply, such as the fluctuation of new energy electrolytic hydrogen production, and the high stability requirement of the traditional ammonia synthesis process. The proposed ammonia synthesis system operates more stably and is more flexible in regulation;

[0092] (2) It well solves the problem of high energy consumption caused by the head loss in the hydrogen storage link, solves the problem of extremely high investment in chemical energy storage in the ammonia synthesis industry (energy storage power station; chemical energy storage refers to electrochemical energy storage, battery; the unit cost of storing electrical energy in the battery is higher than the unit cost of storing hydrogen in the battery, and replacing electrochemical energy storage with energy-saving hydrogen storage can reduce the investment in the ammonia synthesis process), can greatly reduce the share of chemical energy storage in the whole device, and even can cancel the chemical energy storage device, greatly improving the technical economy of the device.

[0093] (3) Solved the problem of poor economy of the current mainstream low-pressure hydrogen storage process, which has high investment in hydrogen storage equipment due to low hydrogen storage density. The coupled process technology of hydrogen storage in the hydrogen production device (low pressure), hydrogen storage between compression systems (medium pressure), and hydrogen storage in the ammonia synthesis system (high pressure) can customize the proportion of hydrogen storage facilities at each level according to specific application scenarios;

[0094] (4) In addition to being applicable to the application scenario of hydrogen production from new energy for ammonia synthesis, the solution of the present invention is also applicable to ammonia synthesis processes using all other types of unstable hydrogen sources, such as ammonia synthesis systems using fixed-bed gasification hydrogen production processes, plasma gasification hydrogen production processes, etc.

[0095] The present invention provides an ammonia synthesis system based on a fluctuating hydrogen source, including: a hydrogen supply device, the hydrogen quantity provided by the hydrogen supply device fluctuates; a hydrogen storage container for storing the hydrogen provided by the hydrogen supply device; a nitrogen supply device for communicating with the hydrogen storage container to introduce nitrogen into the hydrogen storage container to keep the pressure in the hydrogen storage container stable. The ammonia synthesis system based on a fluctuating hydrogen source provided by the present invention can not only meet the traditional application scenarios of raw material synthesis gas, but also be well applicable to the ammonia synthesis application scenario where the hydrogen supply quantity fluctuates. For example, in the application scenario of synthesizing ammonia by using unstable (regular and irregular fluctuations) green electric energy such as wind power, photovoltaic, and hydropower to produce raw material hydrogen, even when the green electric energy fluctuates within the full load range of 0 to 100%, stable production of ammonia can be ensured; compared with the traditional gaseous hydrogen storage ammonia synthesis process, the system provided by the present invention can achieve a 100% reuse rate without decompression of gaseous hydrogen storage, and there is no pressure loss for the hydrogen stored and reused, effectively ensuring the technical economy and operation and maintenance economy of the device.

[0096] The present invention also provides an implementation manner of a control method for an ammonia synthesis system based on a fluctuating hydrogen source, wherein the ammonia synthesis system is the ammonia synthesis system described above in the present invention; the control method is applied to a control center in the ammonia synthesis system.

[0097] Its specific process is as Figure 2 shown, and specifically includes the following steps:

[0098] S110. Judge whether the pressure of the hydrogen storage container in the ammonia synthesis system is less than a preset pressure value.

[0099] If the pressure of the hydrogen storage container is less than the preset pressure value, first execute step S120, and then return to execute step 110; if the pressure of the hydrogen storage container is greater than or equal to the preset pressure value, execute step S130.

[0100] Among them, the preset pressure value is the pressure value of the hydrogen storage container when the ammonia synthesis system can operate normally, which can be set according to actual needs and is not specifically limited here, and all are within the protection scope of this application.

[0101] S120. Control the nitrogen supply device in the ammonia synthesis system to introduce nitrogen into the hydrogen storage container.

[0102] S130. Prohibit the nitrogen supply device in the ammonia synthesis system from introducing nitrogen into the hydrogen storage container.

[0103] Since the density of nitrogen is greater than that of hydrogen, after nitrogen enters the hydrogen storage container, it always remains at the bottom. Therefore, while maintaining the pressure of the hydrogen storage container unchanged, it does not affect the release of hydrogen.

[0104] The present invention also provides another implementation manner of the control method for the ammonia synthesis system based on a volatile hydrogen source, and its specific process is as Figure 3 shown; before the above step S110, this implementation manner further includes the following steps:

[0105] S210. Judge whether the amount of hydrogen provided by the hydrogen supply device in the ammonia synthesis system fluctuates.

[0106] If the amount of hydrogen provided by the hydrogen supply device fluctuates, then execute step S110 first; if the amount of hydrogen provided by the hydrogen supply device does not fluctuate, then do not execute step S110.

[0107] In practical applications, when the new energy power supply unit connected to the ammonia synthesis system operates stably at full load, the amount of hydrogen provided by the hydrogen supply device is stable; when the new energy power supply unit connected to the ammonia synthesis system operates at low load or fails and shuts down, the amount of hydrogen provided by the hydrogen supply device will fluctuate.

[0108] The present invention also provides another implementation manner of the control method for the ammonia synthesis system based on a volatile hydrogen source, and its specific process is as Figure 4 shown; on the basis of the above implementation manner, this implementation manner further includes the following steps:

[0109] S310. Judge whether the hydrogen / nitrogen ratio input to the ammonia synthesis unit in the ammonia synthesis system is greater than the set ratio.

[0110] If the above hydrogen / nitrogen ratio is greater than the set ratio, then execute step S320; if the above hydrogen / nitrogen ratio is less than or equal to the set ratio, then execute step S330.

[0111] S320. According to the difference between the above hydrogen / nitrogen ratio and the set ratio, increase the amount of nitrogen introduced by the nitrogen supply device into the ammonia synthesis unit.

[0112] In practical applications, if the ammonia synthesis system includes a nitrogen compressor unit, the amount of nitrogen introduced into the ammonia synthesis unit by the nitrogen supply device is increased by increasing the working load of the nitrogen compressor unit.

[0113] S330. According to the difference between the above hydrogen / nitrogen ratio and the set ratio, the amount of nitrogen introduced into the ammonia synthesis unit by the nitrogen supply device is reduced.

[0114] In practical applications, if the ammonia synthesis system includes a nitrogen compressor unit, the amount of nitrogen introduced into the ammonia synthesis unit by the nitrogen supply device is reduced by reducing the working load of the nitrogen compressor unit.

[0115] To further illustrate the present invention, the following embodiments are used for detailed description.

[0116] Embodiment

[0117] See Figure 1 as shown Figure 1 is a schematic diagram of an ammonia synthesis system based on a fluctuating hydrogen source provided by an embodiment of the present invention; wherein, 11 is a new energy power supply unit, 10 is a combined compression system, 01 is a hydrogen production device, 02 is an air separation device, 03 is a hydrogen compressor unit, 04 is a nitrogen compressor unit, 05 is a recycle gas compressor unit, 06 is an ammonia synthesis unit, 07 is a spherical low-pressure hydrogen storage container, 08 is a medium-pressure hydrogen storage container, 09 is a high-pressure hydrogen storage container, and 12 is a control center.

[0118] (1) Process flow description:

[0119] The green power produced by the new energy power supply unit 11 is sent into the hydrogen production device 01, and qualified low-pressure hydrogen (1.5 MPa) is produced through power conversion equipment and hydrogen production equipment. After being stored and buffered in the spherical low-pressure hydrogen storage container 07, it enters the hydrogen compressor unit 03 in the combined compression system 10 for pressurization. After the first-stage (one-stage) compression increases the hydrogen pressure to 8.5 MPa, it enters the medium-pressure hydrogen storage container 08 for storage and buffering, and then enters the second-stage (two-stage) compression to continue pressurizing to the ammonia synthesis required pressure of 16.5.0 MPa, and is sent into the high-pressure hydrogen storage container 09 for storage and buffering. Then, it is mixed with high-pressure nitrogen (16.5 MPa) from the air separation device 02 and pressurized by the nitrogen compressor unit 04 and enters the ammonia synthesis unit 06 for ammonia synthesis reaction, and finally produces product ammonia (purity 99.9% wt and yield 99.98%).

[0120] The low-pressure nitrogen gas (0.4 MPa) produced by the air separation unit 02 is pressurized by the nitrogen gas compressor unit 04 in the combined compression system 10, and then mixed with the high-pressure hydrogen gas from the hydrogen gas compressor unit 03 and the stored and reused hydrogen gas in the high-pressure hydrogen storage container 09, and the component is precisely adjusted to configure the ammonia synthesis gas and sent to the ammonia synthesis unit 06. The nitrogen gas generated in the air separation unit 02 is introduced into the bottoms of the spherical low-pressure hydrogen storage container 07, the medium-pressure hydrogen storage container 08, and the high-pressure hydrogen storage container 09 respectively. When the stored hydrogen gas is reused, it is supplemented into each hydrogen storage container in a timely manner to ensure the stable pressure of the reused hydrogen gas.

[0121] The ammonia synthesis reaction is a cyclic reaction. Only part of the synthesis gas passing through the reactor once is converted into ammonia. The synthesis gas that is not converted is called recycle gas after the product ammonia is separated, and after being pressurized by the recycle gas compressor unit 05, it returns to the synthesis system for re-reaction.

[0122] The low-pressure, medium-pressure, and high-pressure hydrogen storage container facilities are equipped with perfect and reliable pressure indicating alarms to monitor the pressure of hydrogen gas in real time.

[0123] (2) New energy power supply unit full-load operation condition:

[0124] When the new energy power supply unit 11 operates stably at full load, the hydrogen production device 01, the air separation unit 02, the combined compression system 10, and the ammonia synthesis unit 06 in the process flow all operate stably at full load. The spherical low-pressure hydrogen storage container 07, the medium-pressure hydrogen storage container 08, and the high-pressure hydrogen storage container 09 are filled with hydrogen gas at corresponding pressures, and the entire new energy hydrogen production and ammonia synthesis device operates stably to produce product ammonia. Under the normal and stable operating conditions of the system, the backup nitrogen gas system of the air separation unit 02 is in a standby state, and the nitrogen gas supplement for the spherical low-pressure hydrogen storage container 07, the medium-pressure hydrogen storage container 08, and the high-pressure hydrogen storage container 09 is in a cut-off state.

[0125] (3) New energy power supply unit switches to low-load operation condition:

[0126] When the new energy power supply unit 11 switches from full-load operation to low-load operation (or fluctuates), the main equipment of the air separation unit 02 reduces production load accordingly, and the air separation backup nitrogen gas system starts to ensure the stable supply of nitrogen gas for the whole system. The hydrogen production device 01 reduces production load according to the power supply situation. The nitrogen gas supplement systems at the bottoms of the spherical low-pressure hydrogen storage container 07, the medium-pressure hydrogen storage container 08, and the high-pressure hydrogen storage container 09 start to ensure that the hydrogen gas in each hydrogen storage container is stably injected into the main process system, and finally ensure that the combined compression system 10 and the ammonia synthesis unit 06 continue to operate stably at full load for a certain period of time. The full-load stable operation time is determined by the capacities of the spherical low-pressure hydrogen storage container 07, the medium-pressure hydrogen storage container 08, and the high-pressure hydrogen storage container 09.

[0127] To ensure the reliable and stable operation of the entire new energy hydrogen production and ammonia synthesis plant, the main process system can adjust (automatically or manually) the production load to ensure the long-term stable operation of the plant.

[0128] (4) New energy power supply unit fault shutdown condition:

[0129] When the new energy power supply unit 11 suddenly shuts down due to a fault during full-load or low-load operation, a stop signal is sent to the control center 12. The hydrogen production device 01 stops producing hydrogen due to the loss of power supply; the main equipment of the air separation device 02 stops due to the loss of power supply, and the air separation backup nitrogen system starts to ensure the stable supply of nitrogen to the whole system. The nitrogen replenishment systems at the bottoms of the spherical low-pressure hydrogen storage container 07, medium-pressure hydrogen storage container 08, and high-pressure hydrogen storage container 09 start to ensure that hydrogen in each hydrogen storage container is stably injected into the main process system to ensure the safe operation of the whole system. After receiving the load reduction signal from the control center, the combined compression system 10 and the ammonia synthesis unit 06 adjust the production load to safely shut down the device.

[0130] The ammonia synthesis plant runs at 100% load and is adjusted to 70% load. When the hydrogen content in the gas at the outlet of the hydrogen compressor unit 03 is monitored to be lower than 95% vol, the control center 12 issues an interlock shutdown signal for the entire new energy hydrogen production and ammonia synthesis plant, and the plant shuts down safely. During the process of adjusting the load of the entire ammonia synthesis plant to shutdown, the ammonia production is maintained at more than 70% of the rated production, with a purity of 99.9% wt and a yield of 99.98%.

[0131] It should be noted that the numbers mentioned in the above embodiments are only specific examples. In actual applications, including but not limited to this, no specific limitations are made here and it can be determined according to specific situations, all within the protection scope of this application.

[0132] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A synthetic ammonia system based on a volatile hydrogen source, characterized in that include: A hydrogen supply device, wherein the amount of hydrogen provided by the hydrogen supply device fluctuates; A hydrogen storage container, used to store the hydrogen provided by the hydrogen supply device; the hydrogen storage container includes a low-pressure hydrogen storage container, a medium-pressure hydrogen storage container and a high-pressure hydrogen storage container; A nitrogen supply device, used to communicate with the hydrogen storage container to introduce nitrogen into the hydrogen storage container to maintain a stable pressure in the hydrogen storage container; Combined compression system; the combined compression system at least comprises a hydrogen compressor unit; the gas inlet of the hydrogen compressor unit is connected to a hydrogen supply device, and the outlet is connected to an ammonia synthesis unit; hydrogen can flow in both directions at equal pressure between the low-pressure hydrogen storage container and the pipeline at the gas inlet of the hydrogen compressor unit; hydrogen can flow in both directions at equal pressure between the medium-pressure hydrogen storage container and the sections of the hydrogen compressor unit; hydrogen can flow in both directions at equal pressure between the high-pressure hydrogen storage container and the pipeline at the gas outlet of the hydrogen compressor unit.

2. The synthetic ammonia system based on a volatile hydrogen source according to claim 1, characterized in that The hydrogen storage container includes a plurality of hydrogen storage containers for storing hydrogen at different pressures, the number of which is greater than or equal to two; the nitrogen supply device is connected to each hydrogen storage container respectively to ensure the pressure stability in each hydrogen storage container by replenishing nitrogen.

3. The synthetic ammonia system based on a volatile hydrogen source according to claim 1, characterized in that The low-pressure hydrogen storage container is connected to the hydrogen outlet of the hydrogen supply device; the medium-pressure hydrogen storage container is connected to the inter-stage gas outlet of the hydrogen compressor unit; and the high-pressure hydrogen storage container is connected to the gas outlet of the hydrogen compressor unit.

4. The synthetic ammonia system based on a volatile hydrogen source according to claim 2, characterized in that The nitrogen supply device introduces nitrogen from the bottom of each hydrogen storage container.

5. The synthetic ammonia system based on a volatile hydrogen source according to claim 1, characterized in that The nitrogen supply device is an air separation device, and the air separation device includes: a nitrogen production device and / or a backup nitrogen system.

6. The synthetic ammonia system based on a volatile hydrogen source according to claim 5, characterized in that When the nitrogen supply device is the nitrogen production device, the nitrogen gas drawn out from the nitrogen production device has two flow paths, one of which is connected to the hydrogen storage container, and the other provides a nitrogen source for the synthetic ammonia reaction.

7. The synthetic ammonia system based on a volatile hydrogen source according to claim 1, characterized in that The low-pressure hydrogen storage container is a vertical pressure container or a spherical pressure container.

8. The synthetic ammonia system based on a volatile hydrogen source according to claim 1, characterized in that The medium-pressure hydrogen storage container is a vertical high-pressure hydrogen storage container.

9. The synthetic ammonia system based on a volatile hydrogen source according to claim 1, characterized in that The high-pressure hydrogen storage container is a high-pressure hydrogen storage tube bundle.

10. The synthetic ammonia system based on a volatile hydrogen source according to claim 1, characterized in that The combined compression system also includes a nitrogen compressor unit and a circulating gas compressor unit; the gas inlet of the nitrogen compressor unit is connected to the nitrogen supply device, and the outlet is connected to the synthetic ammonia unit; the circulating gas compressor unit is used to compress the circulating gas discharged from the synthetic ammonia unit for recycling.

11. The synthetic ammonia system based on a volatile hydrogen source according to claim 10, characterized in that The synthetic ammonia system based on a fluctuating hydrogen source also includes: A control center is used to control the combined compression system, the nitrogen supply device and the synthetic ammonia unit.

12. The synthetic ammonia system based on a volatile hydrogen source according to any one of claims 1 to 11, characterized in that The application scenarios of the synthetic ammonia system based on a fluctuating hydrogen source include hydrogen production and ammonia synthesis from new energy, hydrogen production and ammonia synthesis from fixed bed gasification, and hydrogen production and ammonia synthesis from plasma gasification.

13. A control method for a synthetic ammonia system based on a volatile hydrogen source, characterized in that The synthetic ammonia system is the synthetic ammonia system according to any one of claims 1 to 12, and the control method is applied to a control center in the synthetic ammonia system; the control method comprises: Determining whether the pressure of the hydrogen storage container in the synthetic ammonia system is less than a preset pressure value; If the pressure of the hydrogen storage container is less than the preset pressure value, the nitrogen supply device in the synthetic ammonia system is first controlled to introduce nitrogen into the hydrogen storage container, and then the process returns to the step of determining whether the pressure of the hydrogen storage container in the synthetic ammonia system is less than the preset pressure value.

14. The control method according to claim 13, characterized in that Before determining whether the pressure of the hydrogen storage container in the ammonia synthesis system is less than a preset pressure value, it further includes: Determining whether the amount of hydrogen provided by the hydrogen supply device in the ammonia synthesis system fluctuates; If the amount of hydrogen provided by the hydrogen supply device fluctuates, then perform the step of determining whether the pressure of the hydrogen storage container in the ammonia synthesis system is less than a preset pressure value.

15. The control method according to claim 13 or 14, characterized in that, It further includes: Determining whether the hydrogen / nitrogen ratio input to the ammonia synthesis unit in the ammonia synthesis system is greater than a set ratio; If the hydrogen / nitrogen ratio is greater than the set ratio, then according to the difference between the hydrogen / nitrogen ratio and the set ratio, increase the amount of nitrogen introduced into the ammonia synthesis unit by the nitrogen supply device.

16. The control method according to claim 15, characterized in that, If the hydrogen / nitrogen ratio is less than the set ratio, then it further includes: According to the difference between the hydrogen / nitrogen ratio and the set ratio, reduce the amount of nitrogen introduced into the ammonia synthesis unit by the nitrogen supply device.

17. The control method according to claim 16, characterized in that, If the ammonia synthesis system includes a nitrogen compressor unit, then increasing or decreasing the amount of nitrogen introduced into the ammonia synthesis unit by the nitrogen supply device includes: Increasing or decreasing the working load of the nitrogen compressor unit.

Images