Flexible storage and transportation system and method for liquid ammonia external transportation pipeline

Abstract

The invention discloses a flexible storage and transportation system and method for a liquid ammonia outward transportation pipeline, and belongs to the technical field of liquid ammonia transportation, the system comprises a liquid ammonia supply and distribution system, a liquid ammonia storage system and an efficient outward transportation system, the liquid ammonia supply and distribution system is arranged at the downstream of a liquid ammonia production system and the upstream of the outward transportation pipeline, and is used for carrying out flow distribution control on liquid ammonia; the liquid ammonia storage system is arranged at the downstream of the liquid ammonia supply and distribution system and is used for receiving liquid ammonia input by the liquid ammonia supply and distribution system and providing a temporary storage space; and the efficient output system is used for introducing the liquid ammonia of the liquid ammonia storage system into the main line when the upstream liquid ammonia production capacity is insufficient, and the liquid ammonia is mixed with the upstream produced liquid ammonia and then enters the output pipeline. According to the invention, the purposes of overcoming upstream production fluctuation, optimizing the preparation and storage cost and stabilizing the output capacity can be achieved when the liquid ammonia is coupled to be prepared and conveyed.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of liquid ammonia transportation, and particularly relates to a flexible storage and transportation system and method for a liquid ammonia delivery pipeline. BACKGROUND

[0002] Ammonia can be used as a hydrogen carrier for efficient storage and transportation, realizing energy conversion or industrial application. Liquid ammonia transportation through a pipeline is an effective means to realize planned long-distance transportation.

[0003] Due to the obvious intermittency and instability of wind and light resources, the process of green hydrogen synthesis from green electricity and green hydrogen to liquid ammonia will cause great fluctuations, and time mismatching will be caused on the supply side and the consumption side of liquid ammonia. Although various energy storage and supplement modes have been proposed for green renewable energy storage and utilization, and balanced output is realized through energy conversion, great investment in energy storage systems and equipment will be brought.

[0004] At present, the conventional liquid oil pipeline can basically guarantee stable delivery flow due to the stable supply and processing of upstream fossil fuels and the sufficient consumption of downstream. In contrast, for the scenario of liquid ammonia delivery after green electricity preparation, due to the demand for stability of liquid ammonia supply downstream, it is necessary to overcome the problem of fluctuation of liquid ammonia output caused by unstable upstream energy supply to maintain stable operation of the pipeline transportation system. Therefore, it is urgent to comprehensively consider forming a flexible liquid ammonia pipeline supply system. SUMMARY

[0005] The purpose of the present application is to overcome the defects of the prior art, provide a flexible storage and transportation system and method for a liquid ammonia delivery pipeline, stably supply and control the delivery flow of the liquid ammonia delivery pipeline, effectively balance the fluctuation of green electricity ammonia preparation upstream and the stability of delivery, and overcome the fluctuation of upstream production to the greatest extent. The intermediate green hydrogen medium storage is replaced by efficient liquid ammonia storage, and problems such as temporary liquid ammonia supply and optimization of liquid ammonia transportation energy consumption are considered to comprehensively ensure efficient and stable operation of the liquid ammonia delivery pipeline prepared based on renewable energy.

[0006] The purpose of the present application is achieved by the following technical solutions:

[0007] A flexible storage and transportation system for a liquid ammonia delivery pipeline, which is realized based on a conventional liquid ammonia delivery pipeline system, wherein the conventional liquid ammonia delivery pipeline system comprises a delivery trunk, and the system comprises:

[0008] A liquid ammonia supply and distribution system, which obtains liquid ammonia, distributes the delivery amount of the liquid ammonia, inputs the liquid ammonia within a preset flow range into an efficient delivery system, and inputs the liquid ammonia exceeding the preset flow into a liquid ammonia storage system;

[0009] A liquid ammonia storage system receives the liquid ammonia supplied by the liquid ammonia supply distribution system and provides a liquid ammonia storage device as a temporary storage space for liquid ammonia;

[0010] A high-efficiency delivery system controls the delivery of liquid ammonia. When the delivery amount of liquid ammonia is higher than a first delivery threshold, the liquid ammonia to be delivered is pressurized, and the liquid ammonia to be stored is introduced into the liquid ammonia storage system. When the delivery amount of liquid ammonia is lower than the first delivery threshold, the liquid ammonia stored in the liquid ammonia storage system is injected and mixed with the liquid ammonia distributed by the liquid ammonia supply distribution system before entering the delivery main line.

[0011] Further, the flexible liquid ammonia delivery pipeline storage system further comprises:

[0012] A pressure monitoring device is arranged to monitor the pressure of the liquid ammonia storage device and the pressure of the delivery main line. When the pressure of the liquid ammonia storage device is higher than the pressure of the delivery main line, the liquid ammonia in the liquid ammonia storage device is directly pressurized and injected into the delivery main line. When the pressure of the liquid ammonia storage device is lower than the pressure of the delivery main line, the liquid ammonia in the liquid ammonia storage device is pressurized and injected into the delivery main line.

[0013] Further, the high-efficiency delivery system comprises a first delivery pump, a second delivery pump, and a delivery pressurizing pump. The first delivery pump is arranged at the output end of the liquid ammonia supply distribution system. The output end of the first delivery pump is connected to the liquid ammonia storage system and the second delivery pump. The output end of the second delivery pump is connected to the first inlet of the static mixer of the delivery main line. The input end of the delivery pressurizing pump is connected to the output end of the liquid ammonia storage system. The output end of the delivery pressurizing pump is connected to the second inlet of the static mixer of the delivery main line. The outlet of the static mixer is connected to the delivery main line. The delivery pressurizing pump is also connected in parallel with a delivery regulating valve at both ends.

[0014] Further, the liquid ammonia supply distribution system comprises a liquid ammonia preparation outlet pipeline and a distribution branch. The inlet of the liquid ammonia preparation outlet pipeline obtains liquid ammonia from an upstream liquid ammonia preparation system. The outlet of the liquid ammonia preparation outlet pipeline is connected to the inlet of the first delivery pump. A first outlet pipeline shut-off valve is arranged on the liquid ammonia preparation outlet pipeline.

[0015] The inlet of the distribution branch is connected to the outlet of the first delivery pump through a branch regulating valve. The outlet of the distribution branch is connected to the liquid ammonia storage system through a branch shut-off valve.

[0016] Further, the liquid ammonia storage system comprises an injection pipeline and a delivery pipeline. The inlet of the injection pipeline is connected to the liquid ammonia supply distribution system. The outlet of the injection pipeline is connected to the liquid ammonia storage device. The liquid ammonia storage device is connected to the high-efficiency delivery system through the delivery pipeline.

[0017] Further, the injection pipeline comprises a first injection pipeline and a second injection pipeline, the liquid ammonia storage device comprises a first liquid ammonia storage device and a second liquid ammonia storage device, the delivery pipeline comprises a first delivery branch pipeline, a second delivery branch pipeline and a delivery main pipeline, the first injection pipeline outlet and the first delivery branch pipeline inlet are connected to the first liquid ammonia storage device, the second injection pipeline outlet and the second delivery branch pipeline inlet are connected to the second liquid ammonia storage device, and the first delivery branch pipeline outlet and the second delivery branch pipeline outlet are connected to the high-efficiency delivery system through the delivery main pipeline.

[0018] The first liquid ammonia storage device and the second liquid ammonia storage device alternately store the liquid ammonia input into the liquid ammonia storage system.

[0019] Further, the liquid ammonia delivery pipeline flexible storage and delivery system further comprises:

[0020] A liquid ammonia backup supply system provides temporary liquid ammonia supply to the liquid ammonia storage system when the liquid ammonia supply and distribution system fails to obtain liquid ammonia.

[0021] Further, the liquid ammonia backup supply system comprises a movable liquid ammonia injection system, and the movable liquid ammonia injection system output end is connected to the branch pipeline cutoff valve output end through a reserved injection valve.

[0022] Further, the liquid ammonia storage device is further provided with a temperature adjusting system for adjusting the temperature of the liquid ammonia storage device, so as to control the storage pressure at the back of the liquid ammonia storage device.

[0023] In another aspect, the application further provides a liquid ammonia delivery pipeline flexible storage and delivery method, which is realized based on any one of the above-mentioned liquid ammonia delivery pipeline flexible storage and delivery systems, and the method comprises:

[0024] When the amount of liquid ammonia obtained by the liquid ammonia supply and distribution system is greater than the preset flow rate, the liquid ammonia is delivered at the set delivery flow rate, and the remaining liquid ammonia is stored in the liquid ammonia storage system;

[0025] When the amount of liquid ammonia obtained by the liquid ammonia supply and distribution system is less than the preset flow rate, the liquid ammonia in the liquid ammonia storage system is injected into the high-efficiency delivery system, and the liquid ammonia input by the liquid ammonia supply and distribution system and the liquid ammonia input by the liquid ammonia storage system are mixed uniformly in the high-efficiency delivery system and then input into the delivery trunk pipeline.

[0026] The application has the following beneficial effects:

[0027] (1) The present application is directed to the characteristics of the medium properties of the liquid ammonia pipeline and green production, stable external transport, from the perspective of efficient, safe and stable storage and transport, a complete set of flexible storage and transport measures are proposed, a liquid ammonia supply distribution system is set up, the purpose is to prepare liquid ammonia based on the fluctuation of renewable energy required for green liquid ammonia preparation, and the part exceeding the set transport capacity is distributed to the storage tank for storage, so as to make full use of renewable energy.

[0028] (2) The present application sets up a liquid ammonia storage system, which is used as a relay for flexible storage and transport, stores the liquid ammonia produced during the day, temporarily supplies the liquid ammonia, and replenishes the pipeline with liquid ammonia at night to make up for the insufficient running capacity of the upstream liquid ammonia preparation unit at night. The operation mode of the liquid ammonia storage system is different from that of the conventional oil pipeline storage tank, which fully balances the fluctuation of green liquid ammonia production and the stability of liquid ammonia transportation. In addition, the liquid ammonia storage system also sets up a storage tank temperature regulation system for moderate heating of the medium inside the storage tank using daytime renewable energy. The medium storage pressure can be increased within a safe range by fully utilizing the external renewable energy during the day to reduce the external transportation energy consumption. In addition, the storage tank is operated separately, and for each storage tank, the idea of injecting storage on the first day and discharging on the second day is used to fully utilize the daytime energy and reasonably increase the pressure in the storage tank to reduce the external transportation energy consumption.

[0029] (3) The present application sets up an efficient external transport system, which is used to solve the problem of liquid ammonia production caused by insufficient renewable energy supply of the liquid ammonia production system at night. The system uses liquid ammonia storage tanks to supply the transportation flow and solves the problem of reduced liquid ammonia production at night. The system fully considers the advantages of storage tank heating and pressure increase, and considers the difference in liquid ammonia pressure between daytime and nighttime storage tanks to fully utilize the pressure in the storage tank.

[0030] (4) The present application sets up a liquid ammonia standby supply system to provide temporary liquid ammonia supply to the liquid ammonia storage tank after the upstream ammonia production system is unexpectedly shut down, and to maintain the stable transportation of the downstream trunk pipeline through the liquid ammonia external transport pipeline.

[0031] (5) The present application can use liquid ammonia itself as a kind of energy storage medium, replacing the schemes of electricity storage and hydrogen storage, and optimizing the construction of auxiliary equipment. From the perspective of maintaining stable supply, the daytime renewable energy is fully utilized by setting up a storage tank system, which has a positive contribution to optimizing the operation cost. In addition, the liquid ammonia in the storage tank is moderately heated during the day, which increases the storage pressure under the premise of safety, and uses part of the pressure to support part of the liquid ammonia to directly pass through the booster pump into the external transport system, reducing the operation energy consumption and saving the operation cost. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is a schematic diagram of a liquid ammonia external transport pipeline flexible storage and transport system structure according to an embodiment of the present application.

[0033] Reference: 1 - upstream shutoff valve, 2 - export trunk, 3 - export downstream shutoff valve, 11 - liquid ammonia production outlet pipeline, 12 - first outlet pipeline shutoff valve, 13 - distribution branch, 14 - branch regulating valve, 15 - branch flow transmitter, 16 - branch shutoff valve, 17 - branch pressure transmitter, 21 - first storage tank injection pipeline, 22 - second storage tank injection pipeline, 23 - first storage tank injection shutoff valve, 24 - second storage tank injection shutoff valve, 25 - first storage tank, 26 - second storage tank, 27 - storage tank top communication valve, 28 - storage tank top communication pipe, 29 - first storage tank export branch, 30 - second storage tank export branch, 31 - first storage tank export shutoff valve, 32 - second storage tank export shutoff valve, 33 - storage tank export main pipe, 34 - storage tank export pressure transmitter, 35 - storage tank export flow transmitter, 36 - first storage tank temperature regulating system, 37 - second storage tank temperature regulating system, 41 - primary export pump, 42 - primary export pump front pressure transmitter, 43 - primary export pump rear pressure transmitter, 44 - inter-pump shutoff valve, 45 - secondary export pump, 46 - trunk static mixer, 47 - export flow transmitter, 48 - export pressure transmitter, 49 - storage tank export booster pump, 50 - storage tank export regulating valve, 51 - storage tank export main pipe end shutoff valve. DETAILED DESCRIPTION

[0034] The advantages and effects of the present application can be easily understood by those skilled in the art from the description of the embodiments of the present application. The present application can also be implemented or applied in other different embodiments, and the details in the description can be modified or changed based on different views and applications without departing from the spirit of the present application. It should be noted that the following examples and features in the examples can be combined with each other without conflict.

[0035] All other embodiments obtained by those skilled in the art without creative labor based on the embodiments of the present application are within the scope of protection of the present application.

[0036] At present, the conventional liquid oil pipeline can basically ensure stable export flow due to stable supply and processing of upstream fossil fuels and sufficient consumption of downstream. In contrast, for the scenario of liquid ammonia export after green electricity preparation, due to the demand for stable supply of liquid ammonia downstream, it is necessary to overcome the problem of fluctuation of liquid ammonia output caused by unstable energy supply upstream to maintain stable operation of the pipeline transportation system, therefore, it is urgent to comprehensively consider to form a flexible supply system of liquid ammonia pipeline.

[0037] In order to solve the above technical problems, the following embodiments of a flexible storage and transportation system and method of a liquid ammonia export pipeline of the present application are proposed.

[0038] Example 1

[0039] Reference Figure 1 As Figure 1 The structure of the flexible storage and transportation system of the liquid ammonia delivery pipeline in this embodiment is shown. The system includes a liquid ammonia supply and distribution system, a liquid ammonia storage system, a high-efficiency delivery system, and a liquid ammonia standby supply system. The system needs to rely on a conventional liquid ammonia delivery pipeline system, which includes an upstream cutoff valve 1, a delivery main pipeline 2, a downstream cutoff valve 3, etc., which is not the innovative content of this embodiment.

[0040] The liquid ammonia preparation outlet pipeline 11, the outlet pipeline first cutoff valve 12, the distribution branch pipeline 13, the branch pipeline regulating valve 14, the branch pipeline flow transmitter 15, the branch pipeline cutoff valve 16, and the branch pipeline pressure transmitter 17 constitute the liquid ammonia supply and distribution system, which is used to distribute the liquid ammonia produced to the maximum extent during the day when green electricity is sufficient. On the one hand, it maintains the stability of the pipeline delivery, and on the other hand, it shunts the excess liquid ammonia produced and inputs it into the liquid ammonia storage system.

[0041] Specifically, in the system shown, the liquid ammonia preparation outlet pipeline 11 is connected to the upstream liquid ammonia preparation system and is made of carbon steel, which is used to input the liquid ammonia prepared upstream into the system; the outlet pipeline first cutoff valve 12 is arranged at the starting end of the liquid ammonia preparation outlet pipeline 11 and is an electric ball valve made of carbon steel, which is used to connect or cut off the upstream liquid ammonia supply; the distribution branch pipeline 13 is arranged on one side of the liquid ammonia preparation outlet pipeline 11 and is installed downstream of the primary delivery pump 41 and is made of carbon steel, which is preferably the same pipe diameter as the liquid ammonia preparation outlet pipeline 11, and is used to introduce the excess liquid ammonia produced during the day into the liquid ammonia storage tank; the branch pipeline regulating valve 14 is arranged at the starting end of the distribution branch pipeline 13 and is an electric regulating valve made of carbon steel, which is used to control the flow of liquid ammonia entering the storage tank system during the day and maintain the stability of the liquid ammonia delivery flow; the branch pipeline flow transmitter 15 is arranged downstream of the branch pipeline regulating valve 14 and is used to display the flow of liquid ammonia entering the liquid ammonia storage system in real time, which cooperates with the delivery flow transmitter 47 to support the opening degree control of the branch pipeline regulating valve 14; the branch pipeline cutoff valve 16 is arranged downstream of the branch pipeline flow transmitter 15 and is an electric ball valve made of carbon steel, which is used to connect or cut off the liquid ammonia supply and distribution system; the branch pipeline pressure transmitter 17 is arranged at the branch pipeline cutoff valve 16 and is used to display the pressure of the pipeline downstream of the branch pipeline regulating valve 14 in real time.

[0042] The first storage tank injection pipeline 21, the second storage tank injection pipeline 22, the first storage tank injection cut-off valve 23, the second storage tank injection cut-off valve 24, the first storage tank 25, the second storage tank 26, the storage tank top communication valve 27, the storage tank top communication pipeline 28, the first storage tank external delivery branch pipeline 29, the second storage tank external delivery branch pipeline 30, the first storage tank external delivery cut-off valve 31, the second storage tank external delivery cut-off valve 32, the storage tank external delivery main pipeline 33, the storage tank external delivery pressure transmitter 34, the storage tank external delivery flow transmitter 35, the first storage tank temperature regulation system 36, the second storage tank temperature regulation system 37, etc. constitute a liquid ammonia storage system, which is used to receive liquid ammonia supplied by the liquid ammonia supply distribution system and provide temporary storage space, also receive liquid ammonia supplied by the liquid ammonia standby supply system and provide temporary storage space, and the storage tank temperature regulation system is additionally provided to moderately heat the liquid ammonia storage tank during the day to increase the storage pressure of the liquid ammonia storage tank, thereby moderately increasing the liquid ammonia pressure of the inlet pipeline, optimizing the operating energy consumption, and also moderately heating the medium in the storage tank in winter.

[0043] Specifically, in the system shown, the first storage tank injection pipe 21, made of carbon steel, connects the distribution branch pipe 13 and the first storage tank 25, and is used to provide a liquid ammonia flow path; the second storage tank injection pipe 22, made of carbon steel, connects the distribution branch pipe 13 and the second storage tank 26, and is used to provide a liquid ammonia flow path; the first storage tank injection shut-off valve 23, made of carbon steel, is installed on the first storage tank injection pipe 21 and is used to connect or disconnect the flow path of liquid ammonia into the first storage tank 25; the second storage tank injection shut-off valve 24, made of carbon steel, is installed on the second storage tank injection pipe 22 and is used to connect or disconnect the flow path of liquid ammonia into the second storage tank 26; the first storage tank 25 and the second storage tank 26 are preferably spherical. The storage tank, made of carbon steel, is equipped with an insulation layer. The design pressure is preferably based on the saturated vapor pressure of liquid ammonia at 50°C, and the volume of a single tank is designed based on the total daily liquid ammonia output. A top-connecting valve 27, made of carbon steel and electrically adjustable, is installed on the top-connecting pipe 28. It is used to introduce liquid ammonia gas from the top of another tank before filling the first tank 25 or the second tank 26 begins, providing back pressure to the tank to be filled. Preferably, the initial back pressure is 0.5 MPa or higher. The top-connecting pipe 28, made of carbon steel, connects the tops of the first tank 25 and the second tank 26, providing a connecting flow channel for the gas phase space at the top of the tanks. The first tank's outgoing branch pipe 29... The second storage tank external discharge branch pipe 30 is respectively installed at the lower part of the first storage tank 25 and the second storage tank 26, made of carbon steel, and is used to provide a discharge channel for the liquid ammonia stored in the storage tanks; the first storage tank external discharge shut-off valve 31 and the second storage tank external discharge shut-off valve 32 are respectively installed on the first storage tank external discharge branch pipe 29 and the second storage tank external discharge branch pipe 30, which are electric ball valves made of carbon steel; the storage tank external discharge main pipe 33 connects the first storage tank external discharge branch pipe 29 and the second storage tank external discharge branch pipe 30 and then connects to the main static mixer 46, made of carbon steel, and is used to provide a main flow channel for the liquid ammonia discharged from the storage tanks; the storage tank external discharge pressure transmitter 34 and the storage tank external discharge flow transmitter 35 are sequentially installed at the beginning of the storage tank external discharge main pipe 33, and are distributed as follows: The system is used to monitor the pressure and temperature of liquid ammonia at the location in real time. The first tank temperature regulation system 36 and the second tank temperature regulation system 37 are respectively installed at the bottom of the first tank 25 and the second tank 26. They preferably include a heating / cooling medium circulation system, a medium power system, internal coils of the tank, and a renewable energy supply system. They are used to provide heating for the liquid ammonia inside the first tank 25 or the second tank 26 during the day. They can also adjust the temperature of the liquid ammonia medium inside the tank to be close to that of the external environment. Furthermore, the heating temperature of the liquid ammonia inside the tank does not exceed 90% of the design temperature of the tank, so as to appropriately increase the saturated vapor pressure of the liquid ammonia inside the tank, thereby increasing the storage pressure of the liquid ammonia.

[0044] The high-efficiency external delivery system is composed of a first-stage external delivery pump 41, a first-stage external delivery pump front pressure transmitter 42, a first-stage external delivery pump rear pressure transmitter 43, an inter-pump blocking valve 44, a second-stage external delivery pump 45, a trunk static mixer 46, an external delivery flow transmitter 47, an external delivery pressure transmitter 48, a storage tank external delivery booster pump 49, a storage tank external delivery regulating valve 50, a storage tank external delivery main pipe end blocking valve 51 and the like, and is used for flexible control of daytime and nighttime liquid ammonia external delivery in view of liquid ammonia production fluctuation. When the daytime liquid ammonia production is high, the liquid ammonia needing external delivery is pressurized by the first-stage external delivery pump and the second-stage external delivery pump, and the liquid ammonia needing storage is introduced into the liquid ammonia storage tank. When the nighttime upstream liquid ammonia production is insufficient, the liquid ammonia of the liquid ammonia storage system is injected into the trunk in the injection station, is uniformly mixed with the upstream produced liquid ammonia, enters the external delivery pipeline, and the pressure detection interlock function is used to take the external delivery trunk pressure as the detection object, and the trunk pressurization energy consumption is optimized. When the storage tank pressure is higher than the external delivery trunk pressure, the liquid ammonia of the storage tank is directly pressurized into the trunk after pressure regulation by the regulating valve. When the storage tank pressure is lower than the external delivery trunk pressure, the liquid ammonia of the storage tank is pressurized by the storage tank external delivery booster pump and is injected into the trunk, so that high-efficiency and energy-saving external delivery is realized.

[0045] Specifically, in the system shown, the primary delivery pump 41 is preferably a canned pump made of carbon steel, used to provide primary pressure for the liquid ammonia produced upstream, to provide the pressure for the liquid ammonia to enter the secondary delivery pump 45 and the first storage tank 25 and the second storage tank 26; the primary delivery pump front pressure transmitter 42 is arranged upstream of the primary delivery pump 41, used to detect the liquid ammonia pressure at this point in real time; the primary delivery pump rear pressure transmitter 43 is arranged downstream of the primary delivery pump 41, used to detect the liquid ammonia pressure at this point in real time; the pump intercut-off valve 44 is an electric ball valve made of carbon steel, used to connect or isolate the primary delivery pump 41 and the secondary delivery pump 45; the secondary delivery pump 45 is arranged downstream of the primary delivery pump 41, preferably a canned pump made of carbon steel, used to provide secondary pressure for the liquid ammonia after primary pressure, to meet the delivery pressure requirement; the trunk static mixer 46 is arranged downstream of the secondary delivery pump 45, made of carbon steel, connected to the directly produced liquid ammonia pressurized by the secondary delivery pump 45 and the stored liquid ammonia from the first storage tank 25 and the second storage tank 26, to fully mix the liquid ammonia from the two sources and coordinate the medium temperature; the delivery flow transmitter 47 and the delivery pressure transmitter 48 are arranged downstream of the trunk static mixer 46 in sequence, respectively, used to detect the liquid ammonia flow and pressure at the corresponding points in real time; the storage tank delivery booster pump 49 is arranged on the storage tank delivery main pipe 33, preferably a canned pump made of carbon steel, used to provide pressure boosting and flow adjustment functions when the liquid ammonia discharged from the first storage tank 25 and the second storage tank 26 cannot directly enter the delivery trunk, to meet the pressure requirement for entering the delivery trunk; the storage tank delivery regulating valve 50 is an electric regulating valve made of carbon steel, arranged in the bypass of the storage tank delivery booster pump 49, used to provide pressure regulating and flow adjusting functions when the liquid ammonia discharged from the first storage tank 25 and the second storage tank 26 has sufficient pressure to directly enter the delivery trunk; the storage tank delivery main pipe end cut-off valve 51 is arranged downstream of the storage tank delivery booster pump 49 and the storage tank delivery regulating valve 50, an electric ball valve made of carbon steel, used to connect or isolate the flow passage of the storage tank liquid ammonia entering the downstream trunk.

[0046] The movable liquid ammonia injection system 61, the reserved injection valve 62 and the like constitute a liquid ammonia standby supply system, used to provide temporary liquid ammonia supply to the liquid ammonia storage tank after the upstream ammonia production system is unexpectedly stopped, and to maintain stable delivery of the downstream trunk pipeline through the liquid ammonia delivery pipeline.

[0047] Specifically, in the system shown, the movable liquid ammonia injection system 61 is preferably a liquid ammonia tank truck, a matching booster pump and a pipeline, used to temporarily supplement liquid ammonia to the liquid ammonia storage tank, to meet the trunk delivery requirement; the reserved injection valve 62 is an electric ball valve made of carbon steel, one side connected to the distribution branch pipe 13 and the other side connected to the movable liquid ammonia injection system 61 (the other side is disconnected by a blind flange, replaced when used).

[0048] The working principle of the liquid ammonia delivery pipeline flexible storage and delivery system provided in the embodiment is as follows:

[0049] (1) At present, most of the liquid ammonia is still prepared by fossil fuels, which has high carbon emissions. Therefore, the preparation of green hydrogen by green electricity and the further synthesis of liquid ammonia has become an ideal way in the double carbon path; under the influence of the national double carbon strategy and supply-side reform, the transition from traditional synthetic ammonia to green ammonia has become an inevitable trend. Due to the obvious intermittency and instability of wind and light resources, it will cause great fluctuations in the process of green electricity preparation of green hydrogen and green hydrogen synthesis of liquid ammonia, and cause time mismatching on the supply side and the consumption side of liquid ammonia. Although a variety of energy storage and energy supplement modes have been proposed for green renewable energy storage and utilization, and balanced output is achieved through energy conversion, it will bring a large investment in energy storage systems and equipment. Therefore, the present invention proposes a flexible storage and transportation system and method for liquid ammonia pipeline, which stores the liquid ammonia produced during the day in the storage tank and supplements the pipeline during the night, so as to fully utilize renewable energy, maintain the stability of the liquid ammonia production system and ensure the supply of pipeline.

[0050] (2) Due to the sufficient renewable energy during the day, it can be utilized as much as possible to fully produce liquid ammonia. Therefore, a liquid ammonia supply distribution system and a liquid ammonia storage system are provided to distribute the liquid ammonia produced during the day, part of which enters the pipeline system to meet the stable transportation capacity, and the other part is distributed to the liquid ammonia storage system for storage.

[0051] (3) Since liquid ammonia has different saturated vapor pressures at different temperatures, and the liquid ammonia tank requires strength design according to the highest atmospheric temperature it may face, the liquid ammonia discharged from the liquid ammonia production unit (temperature is generally around 20℃) has room for temperature rise after entering the storage tank, and moderately increasing the temperature of the liquid ammonia in the storage tank will increase the storage pressure to some extent, which can be used as the power during the liquid ammonia discharge process. Therefore, a storage tank temperature regulation system is provided in the liquid ammonia storage system to moderately heat the medium inside the storage tank using daytime renewable energy, which can fully utilize the daytime external renewable energy to increase the medium storage pressure within a safe range, reduce the energy consumption of pipeline transportation, and separate the operation of the storage tank. According to the idea of injecting storage on the first day and discharging on the second day, the daytime energy is fully utilized to reasonably increase the pressure in the storage tank and reduce the energy consumption of pipeline transportation.

[0052] (4) Since there is a certain temperature difference between the liquid ammonia stored in the storage tank and the directly produced liquid ammonia, for long-distance liquid ammonia pipeline transportation, the temperature fluctuation of the inlet medium needs to be controlled to reduce the fluctuation of the transportation pressure. Therefore, a dry line static mixer is provided in the efficient pipeline transportation system to fully mix the directly produced pipeline transportation liquid ammonia and the pipeline transportation liquid ammonia discharged from the storage tank.

[0053] (5) In order to guarantee the stable transportation of the downstream trunk pipeline, the application also provides a liquid ammonia standby supply system for providing temporary liquid ammonia supply to the liquid ammonia storage tank after the upstream ammonia production system is unexpectedly stopped.

[0054] The embodiment is based on the characteristics of the medium physical properties of the liquid ammonia pipeline and green production and stable transportation, and proposes a complete flexible storage and transportation measure from the perspective of high efficiency, safety and stability, and sets up a liquid ammonia supply distribution system, which aims to fully utilize renewable energy based on the fluctuation of the green liquid ammonia production, to produce more liquid ammonia during the day, and to distribute the part exceeding the set transportation capacity to the storage tank for storage, so as to fully utilize the renewable energy.

[0055] The embodiment sets up a liquid ammonia storage system, which aims to serve as a relay of flexible storage and transportation, to store the liquid ammonia produced during the day and the temporary standby supply liquid ammonia, and to supplement the liquid ammonia to the pipeline at night to make up for the insufficient running capacity of the upstream liquid ammonia production unit at night, and the running mode of the liquid ammonia storage system is different from that of the conventional oil pipeline storage tank, which fully balances the fluctuation of green liquid ammonia production and the stability of liquid ammonia transportation, in addition, the liquid ammonia storage system also sets up a storage tank temperature regulation system for moderately heating the medium in the storage tank by using the daytime renewable energy, which can fully utilize the external renewable energy during the day to increase the medium storage pressure within the safe range, reduce the energy consumption of external transportation, and separate the operation of the storage tank, for each storage tank, according to the idea of injecting storage on the first day and discharging after pressure increase on the second day, fully utilize the daytime energy, reasonably improve the pressure in the storage tank, and reduce the energy consumption of external transportation.

[0056] The embodiment sets up a high-efficiency external transportation system, which aims to solve the problem of liquid ammonia production caused by insufficient renewable energy supply of the nighttime liquid ammonia production system, to supplement the transportation flow by using the liquid ammonia storage tank, to solve the problem of reduced nighttime liquid ammonia production, and to fully consider the favorable conditions of storage tank heating and pressure increase, to consider the difference between daytime and nighttime liquid ammonia pressure in the storage tank, and to realize the full utilization of the pressure in the storage tank.

[0057] The embodiment sets up a liquid ammonia standby supply system for providing temporary liquid ammonia supply to the liquid ammonia storage tank after the upstream ammonia production system is unexpectedly stopped, and maintaining the stable transportation of the downstream trunk pipeline through the liquid ammonia external transportation pipeline.

[0058] The embodiment can use liquid ammonia itself as a kind of energy storage medium, replacing the schemes of electricity storage and hydrogen storage, and optimizing the construction of auxiliary equipment; from the perspective of maintaining stable supply, the daytime renewable energy is fully utilized by setting up a storage tank system, which has a positive contribution to optimizing the operation cost; in addition, the daytime moderate heating scheme for the medium in the liquid ammonia storage tank is further adopted, which improves the storage pressure under the premise of safety, and uses the part of the pressure to support part of the liquid ammonia to directly cross the booster pump into the external transportation system, reduces the operation energy consumption, and saves the operation cost.

[0059] Example 2

[0060] This embodiment, based on the working principle of the flexible storage and transportation system for liquid ammonia export pipelines described in the previous embodiment, provides a flexible storage and transportation method for liquid ammonia export pipelines, which specifically includes the following steps:

[0061] Step 1: Analyze downstream demand and upstream production data to determine the flexible storage and transportation scale for liquid ammonia export pipelines. Specifically, determine a stable pipeline flow rate based on the average daily downstream demand for liquid ammonia, ideally with the designed export flow rate equal to the average daily downstream demand. Since the upstream liquid ammonia synthesis process is affected by fluctuations in renewable energy (electricity and wind power), the hydrogen production and ammonia synthesis systems should be operated at full capacity during the day, ensuring that liquid ammonia production exceeds export volume. Excess liquid ammonia is stored in the liquid ammonia storage system. During nighttime periods of low renewable energy supply, the hydrogen production and ammonia synthesis systems should ideally operate at minimum load through grid power and wind power generation. The produced liquid ammonia is mixed with the liquid ammonia stored in the liquid ammonia storage system and exported according to downstream demand. Ideally, each liquid ammonia storage tank should be configured to store one day's total export volume, with at least two liquid ammonia storage tanks preferred.

[0062] Step Two: During daytime operation, liquid ammonia is transported through the efficient external transmission system according to the set external transmission flow rate. The remaining liquid ammonia is stored through the liquid ammonia storage system, and the two storage tanks adopt an alternating storage mode. Specifically, the upstream shut-off valve 1, the external transmission main line 2, and the downstream shut-off valve 3 are opened to connect the external transmission pipeline system; the first shut-off valve 12, the branch pipe regulating valve 14, and the branch pipe shut-off valve 16 of the outlet pipeline are opened to connect the liquid ammonia supply and distribution system; taking the filling of the first storage tank 25 and the maintenance of the storage in the second storage tank 26 as an example, the injection shut-off valve 23 of the first storage tank is opened, the external transmission shut-off valve 31 of the first storage tank is closed, and the inlet pipeline of the liquid ammonia storage system is connected; furthermore, the top connecting valve 27 of the storage tank is opened to fill the first storage tank 25 to 0 using the liquid ammonia in the second storage tank 26. The pressure is increased to 5 MPa. Then, the top connecting valve 27 of the storage tank is closed to provide initial back pressure downstream of the branch regulating valve 14. The first-stage export pump 41, the inter-pump shut-off valve 44, and the second-stage export pump 48 are sequentially activated to connect to the high-efficiency export system. The signal is detected by the export flow transmitter 49, and the opening of the branch regulating valve 14 is adjusted to ensure a stable flow of liquid ammonia into the export trunk line 2. The remaining liquid ammonia is stored in the liquid ammonia storage system. After completing the daytime filling of the first storage tank 25, the first storage tank injection shut-off valve 23 is closed. The second storage tank 26 is filled the following day using the aforementioned steps. It should be noted that on the same day as filling the first storage tank 25, temperature and pressure adjustments are performed on the second storage tank 26, and the stored medium in the second storage tank 26 is discharged and transported at night. This process is repeated for the first storage tank 25 and the second storage tank 26.

[0063] Step three: during the process of injecting liquid ammonia into the first storage tank 25 in the daytime, the second storage tank 26 storage pressure lifting operation is carried out synchronously. Specifically, the second storage tank temperature regulation system 37 is opened, and the slow heating of the liquid ammonia in the storage tank is carried out by using the daytime light heat, green electricity and the like to provide energy for the temperature regulation system, and the heating temperature is not more than 90% of the design temperature of the storage tank, so as to appropriately increase the saturated vapor pressure of the liquid ammonia in the storage tank, thereby increasing the storage pressure of the liquid ammonia. It should be noted that when the liquid ammonia is injected into the second storage tank 26 in the daytime, the first storage tank 25 storage pressure lifting operation is carried out synchronously, and the reciprocating cycle is repeated.

[0064] Step four: after entering the night, due to the significant reduction of the upstream liquid ammonia production, the liquid ammonia in the storage tank is injected into the main line. Specifically, taking the second storage tank 26 as an example, the branch pipe regulating valve 14 and the branch pipe shut-off valve 16 are closed, the second storage tank external delivery shut-off valve 32 is opened, the inter-pump shut-off valve 44 is kept open, the liquid ammonia in the second storage tank 26 is introduced into the main line static mixer 46 through the storage tank external delivery main pipe 33, mixed with the upstream produced and pressurized liquid ammonia, and then input into the downstream delivery main line 2 to supply the downstream users. When the second storage tank 26 medium pressure is higher than the starting pressure of the delivery main line 2, the storage tank external delivery regulating valve 50 is opened to control the flow of liquid ammonia from the second storage tank 26 into the delivery main line 2 and to carry out pressure regulation; when the second storage tank 26 medium pressure is lower than the starting pressure of the delivery main line 2, the storage tank external delivery regulating valve 50 is closed, and the storage tank external delivery booster pump 49 is opened to control the flow of liquid ammonia from the second storage tank 26 into the delivery main line 2 and to carry out pressure lifting. It should be noted that if the first storage tank 25 is implemented for external discharge operation, the second storage tank external delivery shut-off valve 32 is closed, the first storage tank external delivery shut-off valve 31 is opened, and the rest of the operation is consistent with the second storage tank 26 external discharge operation.

[0065] Step five: when the upstream liquid ammonia production system fails to produce liquid ammonia and cannot reach the delivery amount, the liquid ammonia standby supply system is used to supplement the liquid ammonia storage tank, and the temporarily pulled liquid ammonia is injected into the delivery main line 2 by using the buffer of the liquid ammonia storage tank. Specifically, the outlet pipeline first shut-off valve 12, the first-stage delivery pump 41, the branch pipe regulating valve 14, the branch pipe shut-off valve 16 and the inter-pump shut-off valve 44 are closed, the movable liquid ammonia injection system 61 is connected to the reserved injection valve 62, the liquid ammonia is continuously supplemented into the first storage tank 25 or the second storage tank 26 after being pressurized by the self-provided booster, and the first storage tank 25 or the second storage tank 26 continuously delivers liquid ammonia to the delivery main line 2 through the storage tank external delivery main pipe 33 and the storage tank external delivery booster pump 49, so as to maintain the liquid ammonia delivery amount.

[0066] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A flexible storage and transportation system for liquid ammonia export pipelines, the system being implemented based on a conventional liquid ammonia export pipeline system, the conventional liquid ammonia export pipeline system including an export trunk line, characterized in that, The system includes: A liquid ammonia supply and distribution system, wherein the liquid ammonia supply and distribution system acquires liquid ammonia, distributes the outgoing volume of the liquid ammonia, inputs liquid ammonia within a preset flow range into a high-efficiency outgoing system, and inputs liquid ammonia exceeding the preset flow into a liquid ammonia storage system; A liquid ammonia storage system, wherein the liquid ammonia storage system receives liquid ammonia input from the liquid ammonia supply and distribution system and provides a liquid ammonia storage device as a temporary storage space for liquid ammonia; The high-efficiency external transmission system controls the external transmission of liquid ammonia. When the external transmission volume of liquid ammonia is higher than a first external transmission threshold, the liquid ammonia to be transmitted is pressurized, and the liquid ammonia to be stored is introduced into the liquid ammonia storage system. When the external transmission volume of liquid ammonia is lower than the first external transmission threshold, the liquid ammonia stored in the liquid ammonia storage system is injected and mixed evenly with the liquid ammonia distributed by the liquid ammonia supply and distribution system before entering the external transmission trunk line.

2. The flexible storage and transportation system for liquid ammonia export pipeline as described in claim 1, characterized in that, The flexible storage and transportation system for liquid ammonia export pipeline also includes: A pressure monitoring device is installed to monitor the pressure of the liquid ammonia storage device and the pressure of the external transmission line. When the pressure of the liquid ammonia storage device is higher than the pressure of the external transmission line, the liquid ammonia in the liquid ammonia storage device is directly injected into the external transmission line. When the pressure of the liquid ammonia storage device is lower than the pressure of the external transmission line, the liquid ammonia in the liquid ammonia storage device is pressurized and then injected into the external transmission line.

3. The flexible storage and transportation system for liquid ammonia export pipeline as described in claim 1, characterized in that, The high-efficiency external transmission system includes a primary external transmission pump, a secondary external transmission pump, and an external transmission booster pump. The primary external transmission pump is located at the output end of the liquid ammonia supply and distribution system. The output end of the primary external transmission pump is connected to both the liquid ammonia storage system and the secondary external transmission pump. The output end of the secondary external transmission pump is connected to the first inlet of the main line static mixer. The input end of the external transmission booster pump is connected to the output end of the liquid ammonia storage system. The output end of the external transmission booster pump is connected to the second inlet of the main line static mixer. The outlet of the main line static mixer is connected to the external transmission main line. External transmission regulating valves are also connected in parallel at both ends of the external transmission booster pump.

4. The flexible storage and transportation system for liquid ammonia export pipeline as described in claim 3, characterized in that, The liquid ammonia supply and distribution system includes a liquid ammonia preparation outlet pipe and a distribution branch pipe. The inlet of the liquid ammonia preparation outlet pipe obtains liquid ammonia from the upstream liquid ammonia production system, and the outlet of the liquid ammonia preparation outlet pipe is connected to the inlet of the primary external pump. The liquid ammonia preparation outlet pipe is equipped with an outlet pipe first shut-off valve. The inlet of the distribution branch pipe is connected to the outlet of the primary external pump through a branch pipe regulating valve, and the outlet of the distribution branch pipe is connected to the liquid ammonia storage system through a branch pipe shut-off valve.

5. The flexible storage and transportation system for liquid ammonia export pipeline as described in claim 1, characterized in that, The liquid ammonia storage system includes an injection pipeline and an external transmission pipeline. The inlet of the injection pipeline is connected to the liquid ammonia supply and distribution system, and the outlet of the injection pipeline is connected to the liquid ammonia storage device. The liquid ammonia storage device is connected to the high-efficiency external transmission system through the external transmission pipeline.

6. The flexible storage and transportation system for liquid ammonia export pipeline as described in claim 5, characterized in that, The injection pipeline includes a first injection pipeline and a second injection pipeline; the liquid ammonia storage device includes a first liquid ammonia storage device and a second liquid ammonia storage device; the export pipeline includes a first export branch pipe, a second export branch pipe, and an export main pipe; the outlet of the first injection pipeline and the inlet of the first export branch pipe are connected to the first liquid ammonia storage device; the outlet of the second injection pipeline and the inlet of the second export branch pipe are connected to the second liquid ammonia storage device; and the outlet of the first export branch pipe and the outlet of the second export branch pipe are connected to the high-efficiency export system through the export main pipe. The first liquid ammonia storage device and the second liquid ammonia storage device alternately store the liquid ammonia input into the liquid ammonia storage system.

7. The flexible storage and transportation system for liquid ammonia export pipeline as described in claim 4, characterized in that, The flexible storage and transportation system for liquid ammonia export pipeline also includes: A liquid ammonia backup supply system, which provides temporary liquid ammonia supply to the liquid ammonia storage system when the liquid ammonia supply and distribution system is unable to obtain liquid ammonia.

8. The flexible storage and transportation system for liquid ammonia export pipeline as described in claim 7, characterized in that, The liquid ammonia backup supply system includes a portable liquid ammonia injection system, and the output end of the portable liquid ammonia injection system is connected to the output end of the branch pipe shut-off valve through a reserved injection valve.

9. The flexible storage and transportation system for liquid ammonia export pipeline as described in claim 1, characterized in that, The liquid ammonia storage device is also equipped with a temperature regulation system for regulating the temperature of the liquid ammonia storage device, thereby controlling the storage pressure at the back of the liquid ammonia storage device.

10. A flexible storage and transportation method for liquid ammonia via pipeline, characterized in that, The method is implemented based on the flexible storage and transportation system for liquid ammonia export pipelines as described in any one of claims 1-9, and the method includes: When the amount of liquid ammonia obtained by the liquid ammonia supply and distribution system is greater than the preset flow rate, the liquid ammonia is transported according to the set output flow rate, and the remaining liquid ammonia is stored through the liquid ammonia storage system. When the amount of liquid ammonia obtained by the liquid ammonia supply and distribution system is less than the preset flow rate, the liquid ammonia in the liquid ammonia storage system is injected into the high-efficiency external transmission system. The liquid ammonia input from the liquid ammonia supply and distribution system and the liquid ammonia input from the liquid ammonia storage system are mixed evenly through the high-efficiency external transmission system and then input into the external transmission trunk line.

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