Divided-flow type flexible dynamic green ammonia synthesis system
By setting up a diversion pipeline in the green ammonia synthesis system to regulate the condensation temperature of the synthesis gas and the bed temperature of the ammonia synthesis tower, the problem of fluctuations in green ammonia production caused by the instability of renewable energy was solved, and flexible dynamic operation and stable operation of the ammonia synthesis unit were achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SHANGHAI INT ENG CONSULTING
- Filing Date
- 2025-05-14
- Publication Date
- 2026-04-28
AI Technical Summary
In traditional ammonia synthesis processes, the instability of renewable energy sources leads to significant fluctuations in green ammonia production, making continuous and stable operation difficult. There is an urgent need to develop a flexible and dynamic green ammonia synthesis system based on renewable energy to reduce the impact of load fluctuations on ammonia synthesis plants.
The flexible dynamic green ammonia synthesis system adopts a split-flow design. By setting up split pipelines in modules such as the syngas compressor unit, circulating gas compressor unit, hot gas heat exchanger, water cooler, cold gas heat exchanger, and ammonia cooler, the condensation temperature of the syngas and the bed temperature of the ammonia synthesis tower are adjusted to achieve flexible dynamic operation of the unit.
Stable operation of the ammonia synthesis unit was achieved at 10% to 110% load, reducing the impact of wind and solar power load fluctuations on the ammonia synthesis unit and ensuring the smooth and safe operation of the unit.
Smart Images
Figure CN224172466U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of green ammonia synthesis technology, and in particular to a flexible green ammonia synthesis system based on renewable energy, especially a split-flow flexible dynamic green ammonia synthesis system. Background Technology
[0002] Ammonia synthesis is one of the greatest practical innovations in the history of the chemical industry. It has promoted the large-scale industrial production of nitrogen fertilizers and made outstanding contributions to human food security and economic and social development; however, the production process emits a large amount of carbon dioxide. The traditional Haber process for ammonia synthesis indirectly results in approximately 300 million tons of carbon dioxide emissions annually, while consuming about 2% of global energy. In 2022, my country's ammonia industry emitted 220 million tons of carbon dioxide, accounting for about one-seventh of the total carbon emissions from my country's chemical industry, ranking first among chemical industries. Under this dual-carbon context, exploring a green and low-carbon development path for synthetic nitrogen is extremely urgent.
[0003] Green electricity generated from renewable energy sources (such as wind and solar power) produces hydrogen through water electrolysis. This hydrogen, combined with nitrogen separated from the air, is then synthesized into ammonia, commonly known as "green ammonia." Compared to traditional gray ammonia production, this process not only reduces reliance on fossil fuels but also significantly lowers carbon dioxide emissions. Furthermore, because its combustion produces only ammonia and water, without generating carbon dioxide, green ammonia is considered a "zero-carbon" fuel and a crucial clean energy source for the future. It offers a new solution for building a diversified clean energy supply system and possesses broad development potential.
[0004] However, due to the influence of the natural environment (such as temperature, wind, and whether the sun is blocked by clouds), wind and solar power generation is intermittent, fluctuating, and unstable. The load regulation speed of the water electrolysis hydrogen production section is relatively fast (seconds or minutes), while the traditional ammonia synthesis section is generally stable and the load regulation speed is usually slow (hours or days). Without external energy supplementation, green ammonia production has large fluctuations and it is difficult to operate continuously and stably. Therefore, there is an urgent need to develop a flexible green ammonia synthesis technology based on renewable energy that can operate stably. Utility Model Content
[0005] To address the problems of large load fluctuations and mismatched control frequencies between upstream and downstream units in the production of green ammonia using renewable energy, one of the technical problems this utility model aims to solve is to provide a split-type flexible dynamic green ammonia synthesis system, thereby improving the flexible dynamic automatic adjustment capability of the ammonia synthesis unit, reducing the impact of wind and solar power load fluctuations on the ammonia synthesis unit, and achieving stable and safe operation of the ammonia synthesis unit under 10% to 110% load.
[0006] The technical problem to be solved by this utility model can be achieved through the following technical solution:
[0007] A split-flow flexible dynamic green ammonia synthesis system includes: a syngas compressor unit, a circulating gas compressor unit, a hot gas-to-gas heat exchanger, an ammonia synthesis tower, a water cooler, a cold gas-to-gas heat exchanger, at least one ammonia cooler, and an ammonia separator. Green hydrogen and nitrogen generated from renewable energy are compressed by the syngas compressor unit and mixed with circulating gas boosted by the circulating gas compressor unit to form feed gas, which is then sent to the hot gas-to-gas heat exchanger. After exchanging heat with the reacted syngas from the ammonia synthesis tower, the mixture enters the ammonia synthesis tower for the ammonia synthesis reaction. The system then passes through the hot gas-to-gas heat exchanger... The heated syngas is cooled by the water cooler and then sent to the cold gas heat exchanger to exchange heat with the circulating gas from the ammonia separator. The syngas after heat exchange in the cold gas heat exchanger is sent to the ammonia cooler for further cooling. The cooled syngas is then sent to the ammonia separator to separate the circulating gas and green ammonia product. The green ammonia product is then discharged from the ammonia separator. The characteristic feature is that the raw material gas is divided into two streams. One stream enters the hot gas heat exchanger to exchange heat with the reacted syngas, and the other stream enters the ammonia synthesis tower directly through the first split pipeline to regulate the temperature of the bed in the ammonia synthesis tower.
[0008] In a preferred embodiment of this utility model, the raw gas after heat exchange by the hot gas-gas heat exchanger is divided into two streams. One stream enters the ammonia synthesis tower from the bottom of the tower, and the other stream enters the ammonia synthesis tower from the top of the tower through the second diversion pipeline, so as to regulate the bed temperature inside the ammonia synthesis tower.
[0009] In a preferred embodiment of this utility model, the water cooler is provided with a water cooler distribution pipeline to control the outlet gas temperature of the water cooler.
[0010] In a preferred embodiment of this utility model, the water cooler distribution line is either a distribution line for the hot-side medium of the water cooler or a distribution line for the cold-side medium of the water cooler.
[0011] In a preferred embodiment of this utility model, the cold gas heat exchanger is provided with a cold gas heat exchanger branch line to control the outlet gas temperature of the cold gas heat exchanger.
[0012] In a preferred embodiment of this utility model, the gas-to-gas heat exchanger branch line is either a branch line for the hot-side medium of the gas-to-gas heat exchanger or a branch line for the cold-side medium of the gas-to-gas heat exchanger.
[0013] In a preferred embodiment of this utility model, the ammonia cooler is provided with an ammonia cooler distribution pipeline to control the temperature of the ammonia cooler outlet gas.
[0014] In a preferred embodiment of this utility model, the ammonia cooler distribution line is a distribution line for the hot-side medium of the ammonia cooler.
[0015] In a preferred embodiment of the present invention, at least one heat recovery unit is further included, which recovers the heat of the syngas after reaction from the ammonia synthesis tower and then sends it to the hot gas heat exchanger for heat exchange.
[0016] In a preferred embodiment of this invention, the cooling capacity required by the ammonia cooler is provided by an ammonia refrigeration station.
[0017] Due to the adoption of the above technical solution, this utility model has the following characteristics:
[0018] 1. Adjust the condensation temperature of the synthesis gas step by step according to the operating load of the unit, including the condensation temperature of the synthesis gas at the outlet of the water cooler, cold gas heat exchanger and ammonia cooler, and then control the ammonia content in the synthesis loop step by step, thereby gradually adjusting the circulation gas volume of the loop, maintaining stable pressure fluctuations in the ammonia synthesis loop, and realizing flexible dynamic operation of the unit.
[0019] 2. Control the outlet gas temperature of the water cooler by setting up a water cooler distribution pipeline.
[0020] 3. Control the outlet gas temperature of the cold gas heat exchanger by setting up a branch pipeline for the cold gas heat exchanger.
[0021] 4. Control the outlet gas temperature of the ammonia cooler by setting up a diversion pipeline for the ammonia cooler.
[0022] 5. Adjust the reaction temperature in the ammonia synthesis tower according to the operating load of the unit to ensure that the temperature of the ammonia synthesis tower bed fluctuates smoothly and that the temperature of the synthesis tower bed is always higher than the catalyst activation temperature to avoid temperature jumps and achieve flexible dynamic operation of the unit.
[0023] 6. By setting up diversion pipelines at the outlets of the syngas compressor unit and the circulating gas compressor unit to directly enter the ammonia synthesis tower, the bed temperature of the ammonia synthesis tower can be adjusted to ensure its stability.
[0024] 7. By setting up a feed gas diversion pipeline at the inlet of the ammonia synthesis tower, the bed temperature of the ammonia synthesis tower can be adjusted to ensure its stability. Attached Figure Description
[0025] Figure 1 This is a schematic diagram of the process flow of the diversion-type flexible dynamic green ammonia synthesis system of this utility model; Detailed Implementation
[0026] The inventors of this invention have discovered that renewable energy sources are inherently unstable, while traditional ammonia synthesis processes generally operate stably. Without external energy supplementation, green ammonia production exhibits significant fluctuations, making continuous and stable operation difficult. Therefore, this invention presents a flexible green ammonia production process technology that enhances the flexible, dynamic, and automatic adjustment capabilities of the ammonia synthesis unit, reduces the impact of wind and solar power load fluctuations on the ammonia synthesis reaction, and ensures stable and continuous operation of the ammonia synthesis unit. Detailed explanations are provided below through specific embodiments.
[0027] This utility model provides a green ammonia synthesis system. The green ammonia synthesis device can be divided into five modules: compression, reaction, heat recovery, cooling, and separation. A process flow diagram is shown below. Figure 1 As shown.
[0028] The compression module includes a syngas compressor unit 10 and a circulating gas compressor unit 20; the reaction module includes a combined ammonia synthesis tower 30; the heat recovery module includes multiple post-tower heat recovery units 40 and a hot gas-to-gas heat exchanger 50; the cooling module includes a water cooler 60, a cold gas-to-gas heat exchanger 70 and at least one ammonia cooler 80; and the separation module includes an ammonia separator 90.
[0029] In the compression module, green hydrogen and nitrogen generated from renewable energy are pressurized to 10-14.0 MPa by the syngas compressor unit 10 and mixed with the recycle gas that has been pressurized by the recycle gas compressor unit 20. The temperature of the mixed raw material gas is 50-80°C and it is sent to the reaction module.
[0030] In the reaction module, the raw gas from the compression module is sent to the hot gas heat exchanger 50 to exchange heat with the synthesis gas after the reaction in the combined ammonia synthesis tower 30. The temperature of the raw gas after heat exchange is 170-200℃, and it enters the combined ammonia synthesis tower 30 to carry out the ammonia synthesis reaction.
[0031] The synthesis gas after the reaction in the combined ammonia synthesis tower 30 comes out from the bottom of the tower at a temperature of 400-460℃ and is sent to the heat recovery module for waste heat recovery.
[0032] In the heat recovery module, the synthesis gas coming out of the bottom of the combined ammonia synthesis tower 30 recovers heat through multiple tower post-heat recovery units 40 and hot gas-gas heat exchangers 50, and the temperature drops to 70-100℃ before being sent to the cooling module.
[0033] In the cooling module, the synthesis gas, after heat exchange in the hot gas-gas heat exchanger 50, is cooled by the water cooler 60, the cold gas-gas heat exchanger 70, and the ammonia cooler 80 until its temperature drops to -10 to 10°C, and then sent to the separation module. The cooling capacity required by the ammonia cooler 80 is provided by the ammonia refrigeration station 100.
[0034] In the separation module, the synthesis gas cooled by the ammonia cooler 80 enters the ammonia separator 90 for separation, and the separated green ammonia product is sent outside the boundary; the gaseous medium is sent to the circulating gas compressor unit 20 for pressurization after the cold gas heat exchanger 70 recovers the cold energy, and is recycled as raw material gas.
[0035] The reaction module of this invention is equipped with a flow distribution control system, which uses multiple flow distribution pipelines to control the flow and ensure the temperature of the ammonia synthesis tower.
[0036] Specifically, the raw gas from the compression module is divided into two streams by setting the first diversion pipeline 110: one stream enters the hot gas heat exchanger 50 through the main pipeline to exchange heat with the reaction synthesis gas; the other stream enters the self-combining ammonia synthesis tower 30 directly through the first diversion pipeline 110 to adjust the temperature of the bed in the self-combining ammonia synthesis tower 30.
[0037] Specifically, by setting up a second branch line 120, the feed gas after heat exchange in the hot gas-to-gas heat exchanger 50 is further divided and controlled: one stream enters the combined ammonia synthesis tower 30 from the bottom through the main line; the other stream enters the combined ammonia synthesis tower 30 from the top through the second branch line 120, thereby regulating the bed temperature inside the combined ammonia synthesis tower 30. Through feed gas branch control of the compressor unit (first branch line 110) and feed gas branch control of the hot gas-to-gas heat exchanger outlet (second branch line 120), the reaction temperature inside the combined ammonia synthesis tower 30 is kept between 350 and 500°C, ensuring stable fluctuation of the bed temperature of the combined ammonia synthesis tower 30 under different loads, while ensuring that the temperature of each bed in the combined ammonia synthesis tower 30 is always higher than the catalyst activation temperature, thus achieving flexible and dynamic operation of the unit.
[0038] The cooling module of this utility model is equipped with a flow distribution control system. By setting up multiple flow distribution pipelines, the flow distribution control is carried out step by step. The condensation temperature of the synthesis gas is adjusted step by step according to the operating load of the device, including the condensation temperature of the synthesis gas at the outlet of the water cooler 60, the cold gas heat exchanger 70 and the ammonia cooler 80. In this way, the ammonia content in the synthesis circuit is controlled step by step, thereby gradually adjusting the circulation gas volume of the circuit and maintaining the pressure stability of the ammonia synthesis circuit.
[0039] Specifically, by setting up a water cooler distribution line 61, the outlet gas temperature of the water cooler 60 is controlled. The water cooler distribution line 61 can be used for the distribution of the hot-side medium of the water cooler or the cold-side medium of the water cooler.
[0040] By setting up a cold gas heat exchanger branch line 71, the outlet gas temperature of the cold gas heat exchanger 70 can be controlled. The cold gas heat exchanger branch line 71 can be used to branch the hot side medium or the cold side medium of the cold gas heat exchanger.
[0041] By setting up the ammonia cooler diversion line 81, the outlet gas temperature of the ammonia cooler 80 is controlled. The ammonia cooler diversion line 81 is used to divert the hot-side medium of the ammonia cooler.
[0042] Specifically, a flow meter is installed on the fresh gas inlet pipeline to detect the flow rate of the fresh gas and determine the proportion of the unit load to the design value; a temperature meter is installed on the outlet gas pipelines of the water cooler 60, the cold gas heat exchanger 70, and the ammonia cooler 80 to detect the gas cooling temperature; an analytical instrument is installed on the circulating gas pipeline to detect the ammonia content in the circulating gas; and a regulating valve is installed on each branch pipeline to control the flow rate of each branch pipeline.
[0043] When the ammonia synthesis system is in normal operating condition, i.e., the unit load is 75% to 110% of the design value, the valve openings of the water cooler branch line 61, the cold gas heat exchanger branch line 71, and the ammonia cooler branch line 81 in the cooling module are zero, and there is no flow in any branch line at this time; the valve of the first branch line 110 in the reaction module is fully open, and the valve of the second branch line 120 is adjusted accordingly according to the bed inlet temperature set value (350℃ to 360℃).
[0044] When renewable energy sources fluctuate, taking the gradual reduction of the ammonia synthesis unit load as an example (from 75% to 15%), the flow detection instruments on the fresh gas inlet pipeline and the diversion control system of the cooling module, along with the analytical detection instruments on the circulating gas pipeline, control the opening of valves in the diversion pipelines. This, in turn, controls the flow rate of each diversion pipeline, increases the separation temperature of the separation module, and raises the ammonia content in the circulating gas, thereby increasing the circulating gas volume in the loop. Based on the specific load, the pressure in the ammonia synthesis loop is maintained within a reasonable range. Simultaneously, the diversion control system of the reaction module controls the valve opening in the diversion pipelines, thereby controlling the bed temperature.
[0045] Specifically, when the unit load is 75%–55% of the design value, the diversion control system opens the water cooler diversion line 61 to increase the cooling temperature of the synthesis gas at the outlet of the water cooler 60 to approximately 40°C–60°C, thereby increasing the ammonia content in the circulating gas to 3%–4%, and maintaining the ammonia synthesis loop pressure at approximately 13MPa–12MPa. Simultaneously, the diversion control system of the reaction module gradually closes the second diversion line 120, controlling the bed inlet temperature of the combined ammonia synthesis tower 30 to approximately 350°C–360°C.
[0046] Specifically, when the unit load is 55%–35% of the design value, the split control system opens the split line 71 of the cold gas heat exchanger, increasing the cooling temperature of the synthesis gas at the outlet of the cold gas heat exchanger 70 to approximately 40°C–50°C, thereby increasing the ammonia content in the circulating gas to 4%–5%. At this time, the water cooler split line 61 remains fully open, and the ammonia synthesis loop pressure is maintained at approximately 12MPa–11MPa. Simultaneously, the split control system of the reaction module gradually closes the second split line 120 until it is completely closed, and then gradually closes the first split line 110, controlling the bed inlet temperature of the combined ammonia synthesis tower 30 to approximately 360°C–380°C.
[0047] Specifically, when the unit load is 35% to 15% of the design value, the ammonia cooler branch line 81 is opened through the branch control system to increase the condensation temperature of the synthesis gas at the outlet of the ammonia cooler 80 to approximately 0℃ to 10℃, thereby increasing the ammonia content in the circulating gas to 5% to 8%. At this time, the water cooler branch line 61 and the cold gas heat exchanger branch line 71 remain fully open, and the ammonia synthesis loop pressure is maintained at approximately 11MPa to 10MPa. Simultaneously, through the branch control system of the reaction module, the first branch line 110 is gradually closed until it is completely closed, controlling the bed inlet temperature of the combined ammonia synthesis tower 30 to approximately 380℃ to 400℃.
[0048] This utility model embodiment utilizes green hydrogen generated from renewable energy sources, combined with high-purity nitrogen produced by an air separation unit, and couples it with a traditional ammonia synthesis process to produce green ammonia. When the renewable energy load changes, the above-mentioned diversion control system improves the flexible dynamic automatic adjustment capability of the ammonia synthesis unit, enabling the ammonia synthesis unit to operate stably at 10% to 110% load.
Claims
1. A split-flow flexible dynamic green ammonia synthesis system, comprising: The system includes a syngas compressor unit, a recirculating gas compressor unit, a hot gas-to-gas heat exchanger, an ammonia synthesis tower, a water cooler, a cold gas-to-gas heat exchanger, at least one ammonia cooler, and an ammonia separator. Green hydrogen and nitrogen generated from renewable energy are compressed by the syngas compressor unit and mixed with recirculating gas pressurized by the recirculating gas compressor unit to form feed gas, which is then sent to the hot gas-to-gas heat exchanger. After exchanging heat with the syngas from the ammonia synthesis tower, the mixture enters the ammonia synthesis tower for ammonia synthesis. The syngas after heat exchange in the hot gas-to-gas heat exchanger is then further processed by the... After being cooled by a water cooler, the gas is sent to a cold gas heat exchanger to exchange heat with the circulating gas from the ammonia separator. The syngas after heat exchange in the cold gas heat exchanger is sent to an ammonia cooler for cooling. The cooled syngas is then sent to the ammonia separator to separate the circulating gas and green ammonia product. The green ammonia product is then sent out from the ammonia separator. The characteristic feature is that the raw material gas is divided into two streams. One stream enters a hot gas heat exchanger to exchange heat with the reacted syngas, and the other stream enters directly into the ammonia synthesis tower through a first split pipeline to regulate the temperature of the bed in the ammonia synthesis tower.
2. The split-flow flexible dynamic green ammonia synthesis system according to claim 1, characterized in that, The raw gas, after being heated by the hot gas heat exchanger, is divided into two streams. One stream enters the ammonia synthesis tower from the bottom, and the other stream enters the ammonia synthesis tower from the top through the second diversion pipeline, thereby regulating the bed temperature inside the ammonia synthesis tower.
3. The split-flow flexible dynamic green ammonia synthesis system according to claim 2, characterized in that, The water cooler is equipped with a water cooler distribution pipeline to control the outlet gas temperature of the water cooler.
4. The split-flow flexible dynamic green ammonia synthesis system according to claim 3, characterized in that, The water cooler distribution line is either a distribution line for the hot-side medium of the water cooler or a distribution line for the cold-side medium of the water cooler.
5. The split-flow flexible dynamic green ammonia synthesis system according to claim 3, characterized in that, The cold gas heat exchanger is equipped with a cold gas heat exchanger branch line to control the outlet gas temperature of the cold gas heat exchanger.
6. The split-flow flexible dynamic green ammonia synthesis system according to claim 5, characterized in that, The gas-to-gas heat exchanger branch line is either a branch line for the hot-side medium of the gas-to-gas heat exchanger or a branch line for the cold-side medium of the gas-to-gas heat exchanger.
7. The split-flow flexible dynamic green ammonia synthesis system according to claim 1, characterized in that, The ammonia cooler is equipped with an ammonia cooler distribution line to control the temperature of the ammonia cooler outlet gas.
8. The split-flow flexible dynamic green ammonia synthesis system according to claim 7, characterized in that, The ammonia cooler distribution line is the distribution line for the hot-side medium of the ammonia cooler.
9. The split-flow flexible dynamic green ammonia synthesis system according to claim 1, characterized in that, It also includes at least one heat recovery unit, which recovers the heat of the syngas after reaction from the ammonia synthesis tower and then sends it to the hot gas heat exchanger for heat exchange.
10. A split-flow flexible dynamic green ammonia synthesis system according to claim 1, characterized in that, The cooling capacity required for the ammonia cooler is provided by the ammonia refrigeration station.