A cross-regional water resource allocation method based on green ammonia carrier

Abstract

The application discloses a cross-regional water resource allocation method based on green ammonia carrier, and belongs to the cross field of water resource allocation and renewable energy utilization. In the water-rich water source area, water is electrolyzed to hydrogen by using water power, wind power and green power, high-purity liquid ammonia is proportionally synthesized by coupling air separation nitrogen, or is converted into urea; the liquid ammonia or the urea is long-distance transported to a water-deficient area through a railway, a pipeline and the like; by-product high-purity pure water is produced in the terminal resource utilization process and is stored in the local area, and cross-regional water transfer is completed. The application uses green ammonia / urea as a chemical carrier to replace traditional water conservancy engineering physical water transfer, avoids geological disasters, ecological destruction and cross-border dispute risks, relies on mature chemical technology to be quickly landed and linearly expanded, further absorbs surplus new energy in the northwest, helps low-carbon transformation of an industry, and has low water transfer cost and strong market feasibility.

Description

Technical Field

[0001] This invention belongs to the interdisciplinary field of water resource optimization and comprehensive utilization of renewable energy, and specifically relates to a cross-regional water resource allocation method based on green ammonia carrier, which is particularly suitable for ultra-difficult cross-basin water resource allocation scenarios. Background Technology

[0002] my country's water resources are extremely unevenly distributed in time and space. In the arid and semi-arid northwest region, with Xinjiang as the core, water scarcity has become a core bottleneck restricting ecological governance, agricultural development, industrial expansion, and improvement of people's livelihoods. On the other hand, the Yarlung Tsangpo River Basin on the Qinghai-Tibet Plateau and the Three Gorges River Basin of the Yangtze River are extremely rich in water resources. The annual runoff of the Yarlung Tsangpo River exceeds 160 billion cubic meters, and the annual runoff of the Yichang section of the Yangtze River exceeds 451 billion cubic meters. The outflow of water accounts for more than 90% of the downstream flow, indicating huge potential for water resource development and utilization.

[0003] In existing technologies, all inter-basin water transfer schemes are limited to the traditional physical water transfer framework of water conservancy projects. The core idea is to construct ultra-long, deeply buried tunnels, open channels, and pressure pipelines spanning thousands of kilometers, utilizing terrain elevation differences for gravity flow or electric pumping to achieve the physical spatial transfer of water. The most representative example is the Hongqi River water diversion project from Tibet to Xinjiang. However, such traditional engineering water transfer schemes have a fatal bottleneck that cannot be overcome:

[0004] First, the geological engineering risks are uncontrollable. The water diversion route needs to cross more than 10 deep and active fault zones on the Qinghai-Tibet Plateau, facing multiple geological disaster risks such as earthquakes, landslides, freeze-thaw cycles, rock bursts, and siltation. The construction difficulty is rare in the world, the construction period is more than 20 years, and the operation and maintenance costs are extremely high. Summary of the Invention

[0005] Second, the risks of ecological damage and cross-border disputes are prominent. The construction of the project will damage the fragile ecosystem of the plateau, and the large-scale interception of water from cross-border rivers will trigger international disputes with downstream countries, resulting in extremely high geopolitical risks.

[0006] Third, the investment scale is huge and the economic efficiency is extremely poor. The mainstream plan to divert water from Tibet to Xinjiang is estimated to have a total investment of over 1.5 trillion yuan, with an investment of over 10 yuan per cubic meter per year per unit of water volume. Moreover, the entire line must be completed to generate revenue, and the investment payback period is over 50 years, making it extremely difficult to commercially implement.

[0007] Fourth, traditional water diversion projects cannot be implemented in stages. The entire project must be completed to achieve the water transfer effect. They cannot be expanded linearly or implemented in stages, and the investment risk is completely uncontrollable.

[0008] On the other hand, green ammonia technology has achieved mature industrial application. In existing technologies, the core application scenarios of green ammonia are concentrated in three major directions: zero-carbon energy carrier, chemical raw material, and hydrogen energy storage and transportation medium. Pure water, which is a by-product of ammonia combustion / reaction, is only regarded as an insignificant by-product. No existing technology has ever used the long-distance transportation of green ammonia as the core means of cross-regional water resource allocation. Furthermore, no complete energy-water resource synergistic closed-loop solution has been designed for extremely difficult water transfer scenarios such as water diversion from Tibet to Xinjiang. There are obvious gaps and application limitations in existing technologies.

[0009] Purpose of the invention

[0010] The purpose of this invention is to overcome the above-mentioned defects of the prior art and provide a cross-regional water resource allocation method based on green ammonia carrier. This method completely solves the core pain points of traditional engineering water transfer, such as uncontrollable geological risks, serious ecological damage, prominent cross-border disputes, huge investment, and poor implementation. At the same time, it simultaneously addresses the dual needs of water-scarce areas for new energy consumption and the low-carbon transformation of high-carbon industries, thereby achieving cross-regional coordinated and optimized allocation of water resources and energy.

[0011] Technical solution

[0012] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0013] A method for cross-regional water resource allocation based on green ammonia carrier includes the following core steps:

[0014] S1 Green Electricity Hydrogen Production: In water-rich areas, renewable energy electricity is used to drive water electrolysis devices to produce high-purity hydrogen by electrolyzing pure water, while simultaneously producing oxygen as a byproduct.

[0015] S2 Green ammonia synthesis: The high-purity hydrogen gas prepared in step S1 is mixed with the high-purity nitrogen gas prepared by the air separation unit at a molar ratio of 3:1, and high-purity liquid ammonia is prepared by the ammonia synthesis unit, thus completing the chemical transformation of water resources into green ammonia.

[0016] S3 Long-distance transport: The liquid ammonia prepared in step S2 is transported to the target water-scarce area through a long-distance transport system;

[0017] S4 Terminal Resource Utilization and Pure Water Retention: In the target water-scarce area, liquid ammonia is utilized as a resource. After the liquid ammonia is completely reacted, high-purity pure water is produced as a byproduct. All the pure water is retained in the target water-scarce area, thus completing the cross-regional water resource allocation.

[0018] Furthermore, in step S1, the water source is any one or more combinations of the Yarlung Tsangpo River Basin, the Three Gorges of the Yangtze River Basin, and the estuary basin of the eastern coastal area; the renewable energy power is one or more combinations of hydropower, photovoltaic power, and wind power; the water electrolysis device is any one of alkaline electrolyzers and PEM electrolyzers; the DC power consumption for electrolysis is ≤4.5kWh / Nm³H2; and the purity of the hydrogen produced is ≥99.97%.

[0019] Furthermore, in step S1, the renewable energy power comes from the surplus off-peak renewable energy power in the target water-scarce area. The surplus renewable energy power is transmitted to the water source through the existing ±800kV and above ultra-high voltage DC transmission lines. The transmission line has a transmission loss of ≤1.8% per thousand kilometers, so there is no need to build new transmission lines and there is zero infrastructure investment.

[0020] Furthermore, in step S2, the air separation unit adopts a cryogenic air separation unit, and the nitrogen gas produced has a purity of ≥99.99%. The ammonia synthesis unit adopts a 10-20MPa low-pressure flexible ammonia synthesis process, equipped with a low-temperature high-activity ammonia synthesis catalyst, with a reaction temperature of 350-450°C, a single-pass conversion rate of ≥15%, and the liquid ammonia produced has a purity of ≥99.8%.

[0021] Furthermore, in step S2, the prepared high-purity liquid ammonia is further converted into urea through a synthesis device. Urea is used as a water resource carrier to complete subsequent long-distance transportation and end-use. After 1 ton of urea is completely reacted, ≥0.57 tons of high-purity water are produced as a byproduct, thus completely eliminating the regulatory risks of hazardous chemical transportation.

[0022] Furthermore, in step S3, the long-distance transportation system is one or more combinations of railway tank car transportation, long-distance pipeline transportation, and water-land intermodal transportation, and the transportation destination is the arid and semi-arid water-scarce region of Xinjiang. Furthermore, in step S4, the method of utilizing liquid ammonia resources is one or more combinations of coal chemical raw material substitution, agricultural fertilizer production, pure ammonia gas turbine combined cycle power generation, and power plant denitrification, wherein the efficiency of pure ammonia gas turbine combined cycle power generation is ≥58%, and ≥1.59 tons of high-purity water are produced as byproducts after 1 ton of liquid ammonia is completely reacted. Furthermore, in step S4, the high-purity water produced as a byproduct meets the requirements of the "Standards for Drinking Water Quality" GB5749-2022 and can be directly used for ecological desertification control, agricultural irrigation, industrial circulating water, and domestic water supply in the target water-scarce areas. Furthermore, the entire process of steps S1-S4 is implemented using the existing chemical production capacity outsourcing model, without the need to build new production plants and equipment. The entire closed-loop process can be completed within 3 months with zero heavy asset investment. Furthermore, steps S1-S4 construct a multi-source, multi-channel coordinated water transfer system, simultaneously setting up multiple aquaculture bases along the Yarlung Tsangpo River in Tibet, the Three Gorges Dam in Yichang, and the eastern coastal areas. Each base forms a complementary seasonal power supply system and a risk mitigation mechanism to achieve uninterrupted and stable water transfer throughout the year. Beneficial effects Compared with the prior art, the present invention has the following outstanding substantive features and significant beneficial effects: First, it completely breaks through all the core bottlenecks of traditional water diversion schemes. This invention is the first to propose using green ammonia / urea as a water resource carrier to achieve cross-regional water diversion through chemical transformation. It eliminates the need to build extremely difficult and long tunnels and channels, and completely avoids uncontrollable factors such as construction risks in the geological fault zone of the Qinghai-Tibet Plateau, ecological damage to the plateau, and international disputes over cross-border rivers. The construction period is shortened from 20 years in the traditional scheme to 3-18 months, and it can be implemented in stages and on different scales. It can be effective without the need for full-line connection, and completely solves the implementation problem of the traditional scheme. Secondly, this invention achieves dual cross-regional optimized allocation of energy and water resources. It can transform surplus off-peak wind and solar power that cannot be absorbed in water-scarce areas such as Xinjiang into core energy for water resource allocation. The energy loss throughout the process is borne by the originally abandoned new energy power. This not only solves the industry pain point of high wind and solar curtailment rates in Northwest China, but also achieves the core goal of cross-regional water transfer. At the same time, by replacing coal-based ammonia with green ammonia, it realizes the low-carbon transformation of the coal chemical industry in Northwest China. It achieves multiple benefits and has extremely strong comprehensive value. Third, the project risks are completely controllable, and the economic benefits far exceed those of traditional solutions. All aspects of the entire process of this invention are mature industrial technologies that have been commercially applied for decades, without any disruptive technological bottlenecks. After large-scale implementation, the comprehensive cost per unit of water volume can be as low as 3.8 yuan / cubic meter, which is far lower than traditional inter-basin water transfer solutions. All costs can be covered by the sale of green ammonia, carbon emission reduction revenue, and by-product oxygen revenue, achieving zero cost of water transfer and additional profit, and is fully capable of market commercialization. Fourth, it can be linearly expanded without any ceiling limitations. This solution can be effective without the need for full-line connection and can be linearly expanded from 1 million tons / year to 100 million tons / year and then to 1 billion tons / year. Each step can achieve actual water transfer effect, and the investment risk is completely controllable, completely breaking the scale ceiling of traditional water transfer projects. Attached Figure Description Figure 1 is a full process flow diagram of the method described in this invention; Figure 2 is a closed-loop block diagram of the multi-source, multi-channel coordinated water transfer system of the present invention; Figure 3 is an energy and material balance diagram of Embodiment 1 of the present invention. Detailed Implementation The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the following embodiments. Example 1 This example is a demonstration project for the annual production of 100,000 tons of green ammonia from Tibet to Xinjiang. The specific implementation steps are as follows: 1. Green electricity supply: Surplus off-peak wind and solar power from the Zhundong New Energy Base in Xinjiang are transmitted to Linzhi, Tibet via the completed Changji-Guquan ±1100kV UHVDC transmission line. The line is 2,800 kilometers long, with a total transmission loss of 4.2%, a power supply capacity of 120MW, an annual power supply of 1.08 billion kWh, and a comprehensive electricity price of 0.18 yuan / kWh. 2. Hydrogen production by water electrolysis: Along the Yarlung Tsangpo River in Nyingchi, Tibet, four 30MW alkaline electrolyzer clusters are installed, with a single unit having a hydrogen production capacity of 6000Nm³ / h. High-purity hydrogen is produced by electrolyzing purified water from the Yarlung Tsangpo River. The DC power consumption for electrolysis is 4.3kWh / Nm³H2, the hydrogen purity is 99.97%, the annual consumption of pure water is 180,000 tons, the annual production of high-purity hydrogen is 17,700 tons, and 140,000 tons of high-purity oxygen are produced as a byproduct. 3. Air separation for nitrogen production and green ammonia synthesis: Two 4000 Nm³ / h cryogenic air separation units are installed to produce high-purity nitrogen gas with a purity of 99.99%, with an annual production of 78,800 tons of high-purity nitrogen gas; a hydrogen-nitrogen mixture is mixed at a molar ratio of 3:1, pressurized to 15 MPa, and fed into two 50,000-ton / year ammonia synthesis towers, using iron-cobalt-based low-temperature catalysts, with a reaction temperature of 380-420°C, producing 100,000 tons of 99.8% high-purity liquid ammonia annually, with a comprehensive power consumption of 10,800 kWh per ton of ammonia; 4. Long-distance transportation: Liquid ammonia is transported to the Zhundong Coal Chemical Base in Xinjiang via the Qinghai-Tibet Railway tank cars. The one-way transportation time is 72 hours, the annual transportation capacity is 100,000 tons of liquid ammonia, and the unit transportation cost is 220 yuan / ton. 5. Terminal utilization and pure water retention: 100,000 tons of green ammonia will completely replace coal-based ammonia as a raw material for coal chemical industry. After the liquid ammonia is fully reacted, 159,000 tons of high-purity water will be produced as a byproduct. All of this water will be retained in Xinjiang for coal chemical circulating water and irrigation of surrounding protective forests, achieving an annual reduction of 180,000 tons of carbon dioxide emissions.

[0023] Example 2 This example is a demonstration project of the Yichang Three Gorges water source area, with a designed annual water conveyance capacity of 1 million tons. The specific implementation steps are as follows: 1. Green electricity supply: Relying on the existing Changji-Guquan ±1100kV and Hami-Chongqing ±800kV ultra-high voltage transmission lines, we purchase surplus wind and solar power from Xinjiang during off-peak hours. The total line loss is about 5%, and the comprehensive electricity price delivered to the plant is 0.18 yuan / kWh. During the high-water season, we complement the Three Gorges Dam's off-peak hydropower to achieve stable power supply throughout the year. 2. Capacity building: The project adopts a contract manufacturing model, relying on the existing 2 million tons / year synthetic ammonia production capacity around Yichang. There is no need to build new plant buildings and equipment. The annual green ammonia production capacity is designed to be 630,000 tons, corresponding to an annual water transfer capacity of 1 million tons. 3. Transportation plan: Urea will be used as the transportation medium, and transported by car via the Jiaoliu Line-Longhai Line-Lanxin Line railway. The entire journey from Yichang to Urumqi, Xinjiang is 3200 kilometers, with a unit transportation cost of 150 yuan / ton. There is no risk of hazardous chemical supervision. 4. Terminal application: Long-term procurement agreements have been signed with Xinjiang coal chemical enterprises and agricultural input groups. All urea will be used as a raw material substitute for coal chemical industry and as agricultural fertilizer. The 1 million tons of pure water produced as a by-product after the reaction will be stored in Xinjiang and used for industrial circulating water, agricultural irrigation and desertification control.

[0024] Example 3 This embodiment is a multi-source, multi-channel coordinated water transfer system, simultaneously setting up three major ammonia production bases: the Yarlung Tsangpo River in Tibet, the Three Gorges Dam in Yichang, and the eastern coastal area. The Tibet base mainly produces ammonia through hydropower during the summer high-water season, the Yichang base mainly provides stable supply throughout the year, and the coastal base achieves dual-track operation, with 50% of the production capacity used for water transfer to Xinjiang and the other 50% sold at high prices locally in the coastal area. The three bases complement each other seasonally and provide a risk mitigation mechanism, achieving uninterrupted and stable water transfer 365 days a year, with a total annual water transfer capacity of 5 million tons.

Claims

1. A method for cross-regional water resource allocation based on ammonia-based carrier, characterized in that, Includes the following steps: S1 Green Electricity Hydrogen Production: In water-rich areas, renewable energy electricity is used to drive water electrolysis devices to produce high-purity hydrogen by electrolyzing pure water, while simultaneously producing oxygen as a byproduct. S2 Green ammonia synthesis: The high-purity hydrogen gas prepared in step S1 is mixed with the high-purity nitrogen gas prepared by the air separation unit at a molar ratio of 3:1, and high-purity liquid ammonia is prepared by the ammonia synthesis unit, thus completing the chemical transformation of water resources into green ammonia. S3 Long-distance transport: The liquid ammonia prepared in step S2 is transported to the target water-scarce area through a long-distance transport system; S4 Terminal Resource Utilization and Pure Water Retention: In the target water-scarce area, liquid ammonia is utilized as a resource. After the liquid ammonia is completely reacted, high-purity pure water is produced as a byproduct. All the pure water is retained in the target water-scarce area, thus completing the cross-regional water resource allocation.

2. The method for cross-regional water resource allocation based on green ammonia carrier according to claim 1, characterized in that, In step S1, the water source is any one or more combinations of the Yarlung Tsangpo River Basin, the Three Gorges of the Yangtze River Basin, and the estuary basin of the eastern coastal area; the renewable energy power is one or more combinations of hydropower, photovoltaic power, and wind power; the water electrolysis device is any one of alkaline electrolyzers and PEM electrolyzers; the DC power consumption for electrolysis is ≤4.5kWh / Nm³H2; and the purity of the hydrogen produced is ≥99.97%.

3. The method for cross-regional water resource allocation based on green ammonia carrier according to claim 1, characterized in that, In step S1, the renewable energy power comes from the surplus off-peak renewable energy power in the target water-scarce area. The surplus renewable energy power is transmitted to the water source through the built ±800kV and above ultra-high voltage DC transmission lines. The transmission loss per thousand kilometers of the transmission line is ≤1.8%.

4. The method for cross-regional water resource allocation based on green ammonia carrier according to claim 1, characterized in that, In step S2, the air separation unit adopts a cryogenic air separation unit, and the nitrogen gas produced has a purity of ≥99.99%. The ammonia synthesis unit adopts a 10-20MPa low-pressure flexible ammonia synthesis process, equipped with a low-temperature high-activity ammonia synthesis catalyst, with a reaction temperature of 350-450°C, a single-pass conversion rate of ≥15%, and the liquid ammonia produced has a purity of ≥99.8%.

5. The method for cross-regional water resource allocation based on green ammonia carrier according to claim 1, characterized in that, In step S2, the prepared high-purity liquid ammonia is further converted into urea through a synthesis device. Urea is used as a water resource carrier to complete subsequent long-distance transportation and end-use. After 1 ton of urea is completely reacted, ≥0.57 tons of high-purity water are produced as a byproduct.

6. The method for cross-regional water resource allocation based on green ammonia carrier according to claim 1, characterized in that, In step S3, the long-distance transportation system is one or more combinations of railway tank car transportation, long-distance pipeline transportation, and water-land intermodal transportation, and the transportation destination is the arid and semi-arid water-scarce region of Xinjiang.

7. The method for cross-regional water resource allocation based on green ammonia carrier according to claim 1, characterized in that, In step S4, the method of utilizing liquid ammonia resources is one or more combinations of coal chemical raw material substitution, agricultural fertilizer production, pure ammonia gas turbine combined cycle power generation, and power plant denitrification, wherein the efficiency of pure ammonia gas turbine combined cycle power generation is ≥58%, and ≥1.59 tons of high-purity water are produced as byproducts after 1 ton of liquid ammonia is completely reacted.

8. The method for cross-regional water resource allocation based on green ammonia carrier according to claim 1, characterized in that, In step S4, the high-purity water produced as a byproduct meets the requirements of the "Standards for Drinking Water Quality" GB5749-2022 and can be directly used for ecological desertification control, agricultural irrigation, industrial circulating water, and domestic water supply in the target water-scarce areas.

9. The method for cross-regional water resource allocation based on green ammonia carrier according to claim 1, characterized in that, The entire process of steps S1-S4 is implemented using the existing chemical production capacity outsourcing model, without the need to build new production plants and equipment, and the entire closed-loop process can be completed within 3 months.

10. The method for cross-regional water resource allocation based on green ammonia carrier according to claim 1, characterized in that, Steps S1-S4 construct a multi-source, multi-channel coordinated water transfer system, simultaneously setting up multiple water production bases in the Yarlung Tsangpo River in Tibet, the Three Gorges Dam in Yichang, and the eastern coastal areas. Each base forms a complementary seasonal power supply system and a risk mitigation mechanism to achieve uninterrupted and stable water transfer throughout the year.

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