An organic liquid hydrogen storage and ammonia synthesis coupling system and method

Abstract

This invention belongs to the field of hydrogen energy storage and chemical technology, and discloses a coupling system and method for organic liquid hydrogen storage and ammonia synthesis. The system includes an organic liquid hydrogen storage subsystem, an ammonia synthesis subsystem, and an energy exchange system. The organic liquid hydrogen storage subsystem is equipped with a hydrogen absorption device and a dehydrogenation device; the ammonia synthesis subsystem is equipped with a synthesis tower and a hydrogen purification device to supply hydrogen; the energy exchange system uses a heat exchanger to use the waste heat from the ammonia synthesis reaction for cooling the organic liquid hydrogen absorption process or heating the dehydrogenation process. The hydrogen produced by the dehydrogenation device can be purified by the same hydrogen purification device and then supplied to the synthesis tower; the system can flexibly switch operating modes: when hydrogen prices are high, the hydrogen absorption device operates to store hydrogen; when hydrogen prices are low, the dehydrogenation device operates to release hydrogen to produce ammonia. This invention achieves energy complementarity and process coupling between hydrogen energy storage and transportation and ammonia synthesis production, significantly improving overall energy efficiency and reducing carbon emissions and operating costs.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen energy storage and chemical technology, and in particular to an organic liquid hydrogen storage and ammonia synthesis coupling system and method. Background Technology

[0002] Hydrogen energy, as a zero-carbon and highly efficient secondary energy source, has become one of the core carriers of energy transformation; while the synthetic ammonia industry, as a key link in agricultural production and basic chemical industry, has long faced the bottleneck of high energy consumption and high carbon emissions in its traditional production model. The technological coupling of the two is not only an important path to solve the problem of large-scale hydrogen energy storage and transportation, but also a core direction to promote the low-carbon upgrading of the synthetic ammonia industry, which has significant energy strategic and industrial economic value.

[0003] Currently, hydrogen storage and transportation are limited by safety, economy, and stability, and existing technologies each have their limitations: High-pressure gaseous hydrogen storage is commercially mature, but it has low hydrogen density, high transportation costs, and significant safety risks. Long-distance transportation also requires frequent pressurization, reducing equipment lifespan and increasing energy consumption; Low-temperature liquid hydrogen storage has high density, but requires a temperature of -253℃, with refrigeration energy consumption accounting for 30%-40%, and is prone to evaporation losses, making it only suitable for ultra-large-scale short-distance transportation; Solid-state hydrogen storage has high safety, but its capacity is limited and the conditions for hydrogen absorption and desorption are harsh; Organic liquid hydrogen storage utilizes the hydrogenation and dehydrogenation properties of organic liquid carriers to transform hydrogen from a gaseous hazardous chemical into a room-temperature and atmospheric-pressure liquid chemical. It has the characteristics of being non-flammable, non-explosive, non-toxic, non-corrosive, non-volatile, and having good thermal conductivity, making it suitable for large-scale, long-distance, long-term, high-safety, and low-cost hydrogen storage, transportation, and application scenarios. However, it has the following problems:

[0004] 1. Organic liquids require a high temperature of 250-300℃ for dehydrogenation. Traditional organic liquids require a high-power electric heater or steam heat exchanger for dehydrogenation, resulting in high energy consumption. In addition, the organic liquids usually use dibenzyltoluene, which requires a hydrogen content of more than 99.5%. During the dehydrogenation process, a small amount of impurities will be released, which requires an additional purification system, resulting in high investment costs and poor economic efficiency.

[0005] 2. Organic liquids generate a lot of heat during hydrogen absorption. Traditional technologies use circulating cooling water or air cooling to cool the liquid, which not only increases energy consumption but also fails to make good use of the heat generated, resulting in energy loss.

[0006] In summary, current organic liquid hydrogen storage technology and the synthetic ammonia industry face significant technical bottlenecks in areas such as energy consumption complementarity, impurity treatment, and system flexibility. There is an urgent need to develop a highly efficient and synergistic coupling system that can achieve low-carbon, low-cost, and highly stable operation of hydrogen energy storage and transportation and synthetic ammonia production through energy cascade utilization, synergistic impurity removal, and dynamic control of operating conditions. This would provide key technical support for the integration and upgrading of the hydrogen energy industry chain with traditional high-carbon industries. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide an organic liquid hydrogen storage and ammonia synthesis coupling system and method to achieve synergistic operation of organic liquid hydrogen storage and ammonia synthesis, improve energy utilization efficiency, reduce carbon emissions, and simplify the process flow.

[0008] The technical solution of this invention to solve the technical problem is as follows:

[0009] A first aspect of the present invention is to provide an organic liquid hydrogen storage and ammonia synthesis coupling system, comprising:

[0010] An organic liquid hydrogen storage subsystem includes a hydrogen absorption device for carrying out an organic liquid hydrogenation reaction and a dehydrogenation device for carrying out an organic liquid dehydrogenation reaction.

[0011] A synthetic ammonia subsystem includes a synthesis tower for performing ammonia synthesis and a hydrogen purification unit for supplying raw material hydrogen to the synthesis tower.

[0012] An energy exchange system includes a first heat exchanger and a second heat exchanger, wherein the first heat exchanger is configured to heat boiler feedwater using waste heat from the ammonia synthesis reaction, and the second heat exchanger is configured to heat or cool an organic liquid flowing through it using a medium heated or heated from the first heat exchanger.

[0013] The hydrogen outlet of the dehydrogenation unit is connected to the inlet of the hydrogen purification unit via a dehydrogenation pipeline, so that the hydrogen produced by dehydrogenation is purified and supplied to the synthesis tower; the hydrogen inlet of the hydrogen absorption unit is connected to the outlet of the hydrogen purification unit via a hydrogen absorption pipeline, so as to receive hydrogen from the hydrogen purification unit for hydrogenation reaction; the organic liquid circulation pipeline of the organic liquid hydrogen storage subsystem is connected to the second heat exchanger to achieve heat exchange with the energy exchange system.

[0014] Furthermore, the organic liquid hydrogen storage subsystem also includes a hydrogen-lean storage tank, a hydrogen-rich storage tank, a circulation pump, and connecting pipelines; the inlet of the circulation pump can be selectively connected to the hydrogen-lean storage tank or the hydrogen-rich storage tank, and its outlet is divided into two paths through pipelines, one path connecting to the inlet of the hydrogen absorption device, and the other path connecting to the second heat exchanger through a circulation bypass; the second heat exchanger can be selectively connected to the hydrogen-lean storage tank or the hydrogen-rich storage tank through pipelines.

[0015] Furthermore, the energy exchange system also includes a boiler water preheating subsystem, which includes a booster pump, a second heat exchanger, and connecting pipelines; the inlet of the booster pump can be selectively connected to the boiler water inlet main or the boiler water return main, and its outlet is connected to the boiler water inlet main after passing through the shell side of the second heat exchanger; the boiler water return main is connected to the shell side outlet of the first heat exchanger, and the shell side inlet of the first heat exchanger is connected to the boiler water inlet main.

[0016] Furthermore, the boiler water preheating subsystem also includes a temperature control valve, a hydrogen absorption temperature gauge, and a dehydrogenation temperature gauge; the temperature control valve is located on the pipeline from the outlet of the booster pump to the second heat exchanger; the hydrogen absorption temperature gauge is used to detect the temperature of the organic liquid after heat exchange leaving the hydrogen absorption device, and the dehydrogenation temperature gauge is used to detect the temperature of the organic liquid leaving the dehydrogenation device; the coupling system also includes a selector configured to selectively transmit the detection signal from the hydrogen absorption temperature gauge or the dehydrogenation temperature gauge to the temperature control valve to control the flow rate of the medium flowing through the shell side of the second heat exchanger, thereby regulating the temperature of the organic liquid.

[0017] Furthermore, the ammonia synthesis subsystem also includes a synthesis gas compressor, a hydrogen-nitrogen ratio regulating valve, and a hydrogen-nitrogen ratio analyzer; the synthesis gas compressor is installed on the pipeline from the outlet of the hydrogen purification unit to the synthesis tower; the hydrogen-nitrogen ratio regulating valve is installed on the medium-pressure nitrogen pipeline connecting the outlet of the hydrogen purification unit to the synthesis gas main; the hydrogen-nitrogen ratio analyzer is installed on the synthesis gas main and is signal-connected to the hydrogen-nitrogen ratio regulating valve for adjusting the hydrogen-nitrogen ratio in the synthesis gas.

[0018] Furthermore, a dehydrogenation compressor is installed on the dehydrogenation pipeline, and a hydrogen absorption compressor is installed on the hydrogen absorption pipeline.

[0019] Furthermore, the tube-side inlet of the first heat exchanger is connected to the outlet of the synthesis tower for cooling the gaseous ammonia obtained after synthesis; a cooled gaseous ammonia temperature gauge is installed at the tube-side outlet of the first heat exchanger, and a boiler water regulating valve is installed on the boiler water return main pipe; the cooled gaseous ammonia temperature gauge is signal-connected to the boiler water regulating valve.

[0020] Furthermore, the organic liquid hydrogen storage subsystem also includes an organic liquid flow regulating valve and an organic liquid flow meter, which are installed on the pipeline at the outlet of the circulating pump and are signal connected to each other.

[0021] A second aspect of the present invention is to provide a method for coupling organic liquid hydrogen storage and ammonia synthesis, based on the above-mentioned coupling system, including the following modes:

[0022] First mode: When the economics of selling hydrogen are high, the hydrogen absorption device is operated, so that the hydrogen-poor liquid reacts with the hydrogen from the hydrogen purification device in the hydrogen absorption device to generate a hydrogen-rich liquid for storage; at the same time, the reaction heat generated by the hydrogen absorption device is removed using the energy exchange system.

[0023] Second mode: When purchasing hydrogen is economically viable, the dehydrogenation unit is operated to dehydrogenate the hydrogen-rich liquid into a hydrogen-poor liquid and hydrogen. The hydrogen is then purified by the hydrogen purification unit and supplied to the synthesis tower to produce ammonia. At the same time, the energy exchange system is used to provide the heat required for the reaction of the dehydrogenation unit.

[0024] Furthermore, the organic liquid is one or more of dibenzyltoluene, methylcyclohexane, or N-ethylcarbazole and its derivatives.

[0025] The advantages and positive effects of this invention are:

[0026] 1. This invention realizes the synergistic operation of organic liquid hydrogen storage and ammonia synthesis. By storing hydrogen energy through the hydrogenation of organic liquid, and then providing hydrogen for ammonia synthesis after dehydrogenation, it solves the problem of the traditional ammonia synthesis hydrogen source relying on fossil fuels, and at the same time realizes the large-scale storage and efficient utilization of hydrogen energy.

[0027] 2. Based on the characteristics of the two processes of organic liquid hydrogen storage and ammonia synthesis, this invention utilizes the hydrogen purification process of the original ammonia synthesis to purify the hydrogen produced by dehydrogenation, thereby reducing investment costs. At the same time, the impurities removed during the hydrogen purification process can be recycled according to their composition, further improving resource utilization.

[0028] 3. This invention utilizes the waste heat from the dehydrogenation reaction and the ammonia synthesis reaction, along with the heat absorbed by the hydrogen absorption reaction, to make rational use of the energy utilization system, thereby improving the overall energy utilization efficiency of the system.

[0029] 4. This invention sets up two systems for hydrogen absorption and dehydrogenation, which can accommodate both high-priced external sales and low-priced internal hydrogen procurement, effectively reducing operating costs and improving market competitiveness.

[0030] 5. This invention uses organic liquid hydrogen storage to replace traditional fossil fuel hydrogen production, reducing carbon dioxide emissions from the ammonia synthesis process at the source, which meets the requirements of green and low-carbon development. Attached Figure Description

[0031] Figure 1 : Process flow diagram of the present invention.

[0032] Wherein: R1 - Synthesis Tower, R2 - Hydrogen Absorption Unit, R3 - Dehydrogenation Unit, E1 - First Heat Exchanger, E2 - Second Heat Exchanger, T1 - Lean Hydrogen Storage Tank, T2 - Rich Hydrogen Storage Tank, P1 - Booster Pump, P2 - Circulation Pump, C1 - Syngas Compressor, C2 - Hydrogen Absorption Compressor, C3 - Dehydrogenation Compressor, PSA - Hydrogen Purification Unit, 1 - Raw Material Gas Main Pipeline, 2 - Refined Gas Main Pipeline, 3 - Syngas Pipeline, 4 - Ammonia Gas Pipeline, 5 - After Cooling 6-Ammonia gas pipeline, 7-Boiler water inlet main pipe, 8-Cold water pipeline, 9-Preheat water pipeline, 10-Boiler water return main pipe, 11-Boost water pipeline, 12-Circulating pump inlet pipeline, 13-Circulating pump outlet pipeline, 14-Hydrogen-rich liquid pipeline, 15-Hydrogen-lean liquid outlet pipeline, 16-Hydrogen absorption pipeline, 17-Dehydrogenation pipeline, 18-Medium-pressure nitrogen pipeline, 19-Hydrogen-rich liquid outlet pipeline, 20-Hydrogen absorption unit inlet pipeline V1 - Pre-hydrogen absorption manual valve, V2 - Post-hydrogen absorption manual valve, V3 - Post-dehydrogenation manual valve, V4 - Pre-hydrogen absorption manual valve, V5 - Lean hydrogen liquid feed valve, V6 - Rich hydrogen liquid feed valve, V7 - Lean hydrogen liquid discharge valve, V8 - Rich hydrogen liquid discharge valve, XV1 - Cold water shut-off valve, XV2 - Hot water shut-off valve, XV3 - Preheat shut-off valve, XV4 - Booster pump outlet shut-off valve, XV5 - Circulation bypass shut-off valve, TV1 - Temperature control valve, TV2 - Boiler water regulating valve, FV1 - organic liquid flow regulating valve, AV1 - hydrogen-nitrogen ratio regulating valve, TI1 - boiler water inlet temperature gauge, TI2 - boiler water return temperature gauge, TI3 - preheating temperature gauge, TI4 - preheating temperature gauge, TIC1 - hydrogen absorption temperature gauge, TIC2 - dehydrogenation temperature gauge, TIC3 - cooling ammonia gas temperature gauge, FIC1 - organic liquid flow meter, AIC1 - hydrogen-nitrogen ratio analyzer, KY1 - selector. Detailed Implementation

[0033] The present invention will be further described in detail below through specific embodiments. The following embodiments are merely descriptive and not limiting, and should not be used to limit the scope of protection of the present invention.

[0034] like Figure 1 As shown, an organic liquid hydrogen storage and ammonia synthesis coupling system includes a hydrogen purification unit PSA, a synthesis gas compressor C1, a synthesis tower R1, a hydrogen absorption unit R2, a dehydrogenation unit R3, a first heat exchanger E1, a hydrogen absorption compressor C2, a dehydrogenation compressor C3, a boiler water preheating system, and an organic liquid circulation system. Its process flow is as follows: Figure 1As shown: The upstream raw gas is connected to the PSA inlet of the hydrogen purification unit through the raw gas main pipe 1. The raw gas main pipe 1 is connected to the dehydrogenation unit R3 through the dehydrogenation pipeline 17. The dehydrogenation compressor C3 is installed on the dehydrogenation pipeline 17. The PSA outlet of the hydrogen purification unit is divided into three streams. One stream is connected to the inlet of the synthesis gas compressor C1 through the refined gas main pipe 2. The hydrogen-nitrogen ratio analyzer AIC1 is installed on the refined gas main pipe 2. The second stream is connected to the refined gas main pipe 2 through the medium-pressure nitrogen pipeline 18. The hydrogen-nitrogen ratio regulating valve AV1 is installed on the medium-pressure nitrogen pipeline 18. The third stream is connected to the hydrogen absorption unit R2 through the hydrogen absorption pipeline 16. The hydrogen absorption compressor C2 is installed on the hydrogen absorption pipeline 16. The outlet of the synthesis gas compressor C1 is connected to the inlet of the synthesis tower R1 via the synthesis gas pipeline 3. The outlet of the synthesis tower R1 is connected to the tube-side inlet of the first heat exchanger E1 via the ammonia gas pipeline 4. The tube-side outlet of the first heat exchanger E1 is connected downstream via the cooled ammonia gas pipeline 5, and a cooled ammonia gas temperature gauge TIC3 is installed on the cooled ammonia gas pipeline 5. The shell-side inlet of the first heat exchanger E1 is connected to the boiler water inlet main 6, and the shell-side outlet of the first heat exchanger E1 is connected to the boiler water return main 10, and a boiler water regulating valve TV2 is installed on the boiler water return main 10. A boiler water preheating system is connected to the boiler water inlet main 6 and the boiler water return main 10.

[0035] The boiler water preheating system includes a booster pump P1, a second heat exchanger E2, a cold water shut-off valve XV1, a hot water shut-off valve XV2, a preheating shut-off valve XV3, a booster pump outlet shut-off valve XV4, and a temperature control valve TV1. The boiler water inlet main pipe 6 is connected to the inlet of the booster pump P1 via a cold water pipeline 7, and a cold water shut-off valve XV1 is installed on the cold water pipeline 7. The boiler water return main pipe 10 is connected to the inlet of the booster pump P1 via a hot water pipeline 9, and a hot water shut-off valve XV2 is installed on the hot water pipeline 9. The outlet of the booster pump P1 is connected to the shell-side inlet of the second heat exchanger E2 via a booster water pipeline 11, and a temperature control valve TV1 and a booster pump outlet shut-off valve XV4 are installed sequentially on the booster water pipeline 11. The shell-side outlet of the second heat exchanger E2 is connected to the boiler water inlet main pipe 6 via a preheating hot water pipeline 8, and a preheating shut-off valve XV3 is installed on the preheating hot water pipeline 8.

[0036] The organic liquid circulation system includes a hydrogen-lean storage tank T1, a hydrogen-rich storage tank T2, a circulation pump P2, a pre-hydrogen absorption hand valve V1, a post-hydrogen absorption hand valve V2, a post-dehydrogenation hand valve V3, a pre-hydrogen absorption hand valve V4, a hydrogen-lean liquid feed valve V5, a hydrogen-rich liquid feed valve V6, a hydrogen-lean liquid discharge valve V7, a hydrogen-rich liquid discharge valve V8, a circulation bypass shut-off valve XV5, an organic liquid flow regulating valve FV1, an organic liquid flow meter FIC1, a hydrogen absorption temperature meter TIC1, and a dehydrogenation temperature meter TIC2. The lean hydrogen storage tank T1 is connected to the circulating pump inlet pipeline 12 via the lean hydrogen liquid discharge valve V7. The rich hydrogen storage tank T2 is connected to the circulating pump inlet pipeline 12 via the rich hydrogen liquid discharge valve V8. The circulating pump inlet pipeline 12 is connected to the inlet of the circulating pump P2. The outlet of the circulating pump P2 is connected to one end of the circulating pump outlet pipeline 13. An organic liquid flow regulating valve FV1 and an organic liquid flow meter FIC1 are installed sequentially on the circulating pump outlet pipeline 13. At the other end of the circulating pump outlet pipeline 13, it splits into two streams. One stream is connected to the inlet of the hydrogen absorption device R2 via the hydrogen absorption device inlet pipeline 20. A hydrogen absorption pre-hand valve V1 is installed on the hydrogen absorption device inlet pipeline 20. The second stream is connected to the tube-side inlet of the second heat exchanger E2 via the circulation bypass shut-off valve XV5. One end of the hydrogen-rich liquid outlet pipeline 19 is connected to the tube-side inlet of the second heat exchanger E2. A hydrogen absorption temperature gauge TIC1 is installed on the hydrogen-rich liquid outlet pipeline 19. At the other end of the hydrogen-rich liquid outlet pipeline 19, it splits into two streams. One stream is connected to the hydrogen-lean liquid storage tank T1 through the hydrogen-lean liquid feed valve V5, and the other stream is connected to the hydrogen-rich liquid storage tank T2 through the hydrogen-rich liquid feed valve V6. One end of the tube-side outlet of the second heat exchanger E2 is connected to the hydrogen-rich liquid pipeline 14. The other end of the hydrogen-rich liquid pipeline 14 splits into two streams. One stream is connected to the outlet of the hydrogen absorption device R2 through the hydrogen absorption post-hand valve V2, and the other stream is connected to the inlet of the dehydrogenation device R3 through the hydrogen absorption pre-hand valve V4. The outlet of the dehydrogenation device R3 is connected to one end of the hydrogen-lean liquid outlet pipeline 15. A dehydrogenation post-hand valve V3 and a dehydrogenation temperature gauge TIC2 are installed sequentially on the hydrogen-lean liquid outlet pipeline 15. The other end of the hydrogen-lean liquid outlet pipeline 15 is connected to the hydrogen-rich liquid outlet pipeline 19.

[0037] A boiler water inlet temperature gauge TI1 is installed on the boiler water inlet main pipe 6. The boiler water inlet temperature gauge TI1 is an online temperature gauge used to monitor the temperature on the boiler water inlet main pipe 6.

[0038] A boiler water return temperature gauge TI2 is installed on the boiler water return main pipe 10. The boiler water return temperature gauge TI2 is an online temperature gauge used to monitor the temperature on the boiler water return main pipe 10.

[0039] A preheating temperature gauge TI3 is installed on the pressurized water pipeline 11. The preheating temperature gauge TI3 is an online temperature gauge used to monitor the temperature on the pressurized water pipeline 11.

[0040] A preheated temperature gauge TI4 is installed on the preheated hot water pipeline 8. The preheated temperature gauge TI4 is an online temperature gauge used to monitor the temperature on the preheated hot water pipeline 8.

[0041] The hydrogen absorption temperature gauge TIC1 and the dehydrogenation temperature gauge TIC2 are online temperature gauges. The hydrogen absorption temperature gauge TIC1, the dehydrogenation temperature gauge TIC2 and the temperature control valve TV1 are connected to the selector KY1 via cable signal, which is used to select whether the temperature control valve TV1 accepts the control of the hydrogen absorption temperature gauge TIC1 or the dehydrogenation temperature gauge TIC2 as an online temperature gauge.

[0042] The cooled ammonia gas temperature gauge TIC3 is an online temperature gauge, and it is connected to the boiler water regulating valve TV2 via a cable signal connection.

[0043] The organic liquid flow meter FIC1 is an online flow meter, and the organic liquid flow meter FIC1 is connected to the organic liquid flow regulating valve FV1 via a cable signal connection.

[0044] The hydrogen-nitrogen ratio analyzer AIC1 is an online analyzer, and the hydrogen-nitrogen ratio analyzer AIC1 is connected to the hydrogen-nitrogen ratio regulating valve AV1 via a cable signal connection.

[0045] The organic liquid can be any recyclable organic liquid such as dibenzyltoluene, methylcyclohexane, N-ethylcarbazole and its derivatives.

[0046] This invention can set up two production modes according to market conditions. One mode is when the hydrogen energy market is good and the price of hydrogen is high, so hydrogen is sold to the outside world. The other mode is when the price of hydrogen is low, so hydrogen is purchased to produce ammonia.

[0047] Example 1: Hydrogen is expensive, so we sell hydrogen to the outside world. The hydrogen absorption unit R2 produces hydrogen, and the dehydrogenation unit R3 is on standby.

[0048] The dehydrogenation hand valve V3, the hydrogen absorption pre-absorption hand valve V4, the hydrogen-rich liquid discharge valve V8, and the circulation bypass shut-off valve XV5 are all closed. First, close the hydrogen-rich liquid feed valve V6 and the cold water shut-off valve XV1. Then, open the hydrogen absorption pre-absorption hand valve V1, the hydrogen absorption post-absorption hand valve V2, the lean hydrogen liquid feed valve V5, the lean hydrogen liquid discharge valve V7, the hot water shut-off valve XV2, the preheating shut-off valve XV3, and the booster pump outlet shut-off valve XV4. Start the circulation pump P2. Use the organic liquid flow meter FIC1 to control the organic liquid flow regulating valve FV1 to establish lean hydrogen liquid circulation. After the lean hydrogen liquid circulation is established, start the booster pump P1. Selector KY1 selects the hydrogen absorption temperature meter TIC1 for control. Temperature control valve TV1 controls the heating rate at 50°C per hour. Once the temperature of hydrogen absorption thermometer TIC1 reaches the catalyst activation temperature of hydrogen absorption unit R2, hydrogen absorption compressor C2 is started to supply hydrogen to the system. When the temperature rise rate of hydrogen absorption thermometer TIC1 increases, hot water shut-off valve XV2 is closed and cold water shut-off valve XV1 is opened, switching to cooling mode. Temperature control valve TV1 is controlled by hydrogen absorption thermometer TIC1 to maintain the temperature of hydrogen absorption thermometer TIC1 at the reaction temperature. After the catalyst of hydrogen absorption unit R2 is activated, the lean hydrogen liquid feed valve V5 is closed and the rich hydrogen liquid feed valve V6 is opened. Organic liquid flow meter FIC1 controls the conversion rate by controlling organic liquid flow regulating valve FV1. Simultaneously, hydrogen-nitrogen ratio analyzer AIC1 controls the hydrogen-nitrogen ratio regulating valve AV1 to maintain it at 3:1. Cooled ammonia gas temperature meter TIC3 controls boiler water regulating valve TV2 to ensure the ammonia gas temperature does not exceed the limit.

[0049] Example 2: Hydrogen is inexpensive, so a hydrogen purchase model is adopted, in which the dehydrogenation unit R3 produces hydrogen and the hydrogen absorption unit R2 is used as a backup.

[0050] The pre-hydrogen absorption hand valve V1, post-hydrogen absorption hand valve V2, lean hydrogen liquid discharge valve V7, and cold water shut-off valve XV1 are all in the closed state. First, close the lean hydrogen liquid feed valve V5, then open the dehydrogenation post-hand valve V3, the hydrogen absorption pre-hand valve V4, the hydrogen-rich liquid feed valve V6, the circulation bypass shut-off valve XV5, the hydrogen-rich liquid discharge valve V8, the hot water shut-off valve XV2, the preheating shut-off valve XV3, and the booster pump outlet shut-off valve XV4. Start the circulation pump P2. Use the organic liquid flow meter FIC1 to control the organic liquid flow regulating valve FV1 to establish hydrogen-rich liquid circulation. After the hydrogen-rich liquid circulation is established, start the booster pump P1. Use the selector KY1 to select the dehydrogenation temperature meter TIC2 and control the temperature control regulating valve TV1. Control the heating rate at 50°C per hour. When the temperature of the dehydrogenation temperature meter TIC2 reaches the catalyst activation temperature of the dehydrogenation unit R3, start the dehydrogenation compressor C3 to compress the generated hydrogen to the PSA inlet of the hydrogen purification unit. Use the dehydrogenation temperature meter TIC2 to control the temperature control regulating valve TV1 to keep the temperature of the dehydrogenation temperature meter TIC2 stable at the reaction temperature. After the catalyst in the dehydrogenation unit R3 is activated, the hydrogen-rich liquid feed valve V6 is closed and the hydrogen-lean liquid discharge valve V7 is opened. The organic liquid flow meter FIC1 controls the conversion rate by controlling the organic liquid flow regulating valve FV1. At the same time, the hydrogen-nitrogen ratio regulating valve AV1 is maintained at 3:1 by the hydrogen-nitrogen ratio analyzer AIC1, and the boiler water regulating valve TV2 is controlled by the cooled ammonia gas temperature meter TIC3 to ensure that the ammonia gas temperature does not exceed the limit.

[0051] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several modifications and improvements can be made without departing from the inventive concept, and these all fall within the protection scope of the present invention.

Claims

1. An organic liquid hydrogen storage and ammonia synthesis coupling system, characterized in that, include: An organic liquid hydrogen storage subsystem includes a hydrogen absorption device (R2) for carrying out an organic liquid hydrogenation reaction and a dehydrogenation device (R3) for carrying out an organic liquid dehydrogenation reaction. A synthetic ammonia subsystem includes a synthesis tower (R1) for performing ammonia synthesis and a hydrogen purification unit (PSA) for supplying hydrogen as feedstock to the synthesis tower (R1). An energy exchange system includes a first heat exchanger (E1) and a second heat exchanger (E2), wherein the first heat exchanger (E1) is configured to heat boiler feedwater using waste heat from the ammonia synthesis reaction, and the second heat exchanger (E2) is configured to heat or cool the organic liquid flowing through it using a heated or preheated medium from the first heat exchanger (E1). The hydrogen outlet of the dehydrogenation device (R3) is connected to the inlet of the hydrogen purification device (PSA) via a dehydrogenation pipeline (17), so that the hydrogen produced by dehydrogenation is purified and supplied to the synthesis tower (R1); the hydrogen inlet of the hydrogen absorption device (R2) is connected to the outlet of the hydrogen purification device (PSA) via a hydrogen absorption pipeline (16) to receive hydrogen from the hydrogen purification device (PSA) for hydrogenation reaction; the organic liquid circulation pipeline of the organic liquid hydrogen storage subsystem is connected to the second heat exchanger (E2) to achieve heat exchange with the energy exchange system.

2. The coupling system according to claim 1, characterized in that, The organic liquid hydrogen storage subsystem also includes a hydrogen-lean tank (T1), a hydrogen-rich tank (T2), a circulation pump (P2), and connecting pipelines; the inlet of the circulation pump (P2) can be selectively connected to the hydrogen-lean tank (T1) or the hydrogen-rich tank (T2), and its outlet is divided into two paths through pipelines, one path connecting to the inlet of the hydrogen absorption device (R2), and the other path connecting to the second heat exchanger (E2) through a circulation bypass; the second heat exchanger (E2) can be selectively connected to the hydrogen-lean tank (T1) or the hydrogen-rich tank (T2) through pipelines.

3. The coupling system according to claim 2, characterized in that, The energy exchange system also includes a boiler water preheating subsystem, which includes a booster pump (P1), a second heat exchanger (E2), and connecting pipelines; the inlet of the booster pump (P1) can be selectively connected to the boiler water inlet main (6) or the boiler water return main (10), and its outlet is connected to the boiler water inlet main (6) after passing through the shell side of the second heat exchanger (E2); the boiler water return main (10) is connected to the shell side outlet of the first heat exchanger (E1), and the shell side inlet of the first heat exchanger (E1) is connected to the boiler water inlet main (6).

4. The coupling system according to claim 3, characterized in that, The boiler water preheating subsystem further includes a temperature control valve (TV1), a hydrogen absorption temperature gauge (TIC1), and a dehydrogenation temperature gauge (TIC2); the temperature control valve (TV1) is installed on the pipeline from the outlet of the booster pump (P1) to the second heat exchanger (E2); the hydrogen absorption temperature gauge (TIC1) is used to detect the temperature of the organic liquid after heat exchange leaving the hydrogen absorption device (R2), and the dehydrogenation temperature gauge (TIC2) is used to detect the temperature of the organic liquid leaving the dehydrogenation device (R3); the coupling system further includes a selector (KY1), which is configured to selectively transmit the detection signal of the hydrogen absorption temperature gauge (TIC1) or the dehydrogenation temperature gauge (TIC2) to the temperature control valve (TV1) to control the flow rate of the medium flowing through the shell side of the second heat exchanger (E2), thereby regulating the temperature of the organic liquid.

5. The coupling system according to claim 1, characterized in that, The ammonia synthesis subsystem also includes a synthesis gas compressor (C1), a hydrogen-nitrogen ratio regulating valve (AV1), and a hydrogen-nitrogen ratio analyzer (AIC1). The synthesis gas compressor (C1) is installed on the pipeline from the outlet of the hydrogen purification unit (PSA) to the synthesis tower (R1). The hydrogen-nitrogen ratio regulating valve (AV1) is installed on the medium-pressure nitrogen pipeline (18) connecting the outlet of the hydrogen purification unit (PSA) to the synthesis gas main. The hydrogen-nitrogen ratio analyzer (AIC1) is installed on the synthesis gas main and is signal-connected to the hydrogen-nitrogen ratio regulating valve (AV1) for adjusting the hydrogen-nitrogen ratio in the synthesis gas.

6. The coupling system according to claim 1, characterized in that, A dehydrogenation compressor (C3) is installed on the dehydrogenation pipeline (17), and a hydrogen absorption compressor (C2) is installed on the hydrogen absorption pipeline (16).

7. The coupling system according to claim 3, characterized in that, The tube-side inlet of the first heat exchanger (E1) is connected to the outlet of the synthesis tower (R1) for cooling the gaseous ammonia obtained after synthesis; the tube-side outlet of the first heat exchanger (E1) is equipped with a cooled gaseous ammonia temperature gauge (TIC3), and a boiler water regulating valve (TV2) is installed on the boiler water return main pipe (10). The cooled gaseous ammonia temperature gauge (TIC3) is signal-connected to the boiler water regulating valve (TV2).

8. The coupling system according to claim 2, characterized in that, The organic liquid hydrogen storage subsystem also includes an organic liquid flow regulating valve (FV1) and an organic liquid flow meter (FIC1), which are installed on the pipeline at the outlet of the circulating pump (P2) and are signal connected to each other.

9. A method for coupling organic liquid hydrogen storage and ammonia synthesis, implemented based on the coupling system described in any one of claims 1-8, characterized in that, Includes the following modes: First mode: When the economics of selling hydrogen are high, the hydrogen absorption device (R2) is operated, so that the hydrogen-deficient liquid reacts with the hydrogen from the hydrogen purification unit (PSA) in the hydrogen absorption device (R2) to generate a hydrogen-rich liquid for storage; at the same time, the reaction heat generated by the hydrogen absorption device (R2) is removed using the energy exchange system. Second mode: When purchasing hydrogen is economically viable, the dehydrogenation unit (R3) is operated to dehydrogenate the hydrogen-rich liquid into a hydrogen-poor liquid and hydrogen. The hydrogen is then purified by the hydrogen purification unit (PSA) and supplied to the synthesis tower (R1) to produce ammonia. At the same time, the energy exchange system is used to provide the heat required for the reaction of the dehydrogenation unit (R3).

10. The coupling method according to claim 9, characterized in that, The organic liquid is one or more of dibenzyltoluene, methylcyclohexane, or N-ethylcarbazole and its derivatives.

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