System and method for long-distance delivery of steam of nuclear power plant

Abstract

The invention discloses a system and a method for long-distance delivery of steam of a nuclear power plant. The system comprises a water delivery pipeline, a water pipe molten salt box, a power supply device, a steam delivery pipeline and a steam pipe molten salt box, the water conveying pipeline is wrapped in the water pipe molten salt box, the water pipe molten salt box contains molten salt, a molten salt electric heating device is arranged in the water pipe molten salt box, and the water conveying pipeline and the water pipe molten salt box are combined to form a water conveying pipe module; the steam conveying pipeline is wrapped in a steam pipe fused salt box, fused salt is contained in the steam pipe fused salt box, a fused salt electric heating device is arranged in the steam pipe fused salt box, and the steam conveying pipeline and the steam pipe fused salt box are combined to form a steam conveying pipe module; an outlet of the water conveying pipeline is connected with an inlet of the steam conveying pipeline, and the water conveying pipe module and the steam conveying pipe module can dynamically change according to the unit load and the steam using requirement and the boundary of water and steam. The power supply device is powered by the nuclear power plant and used for supplying power to the fused salt electric heating devices in the water pipe fused salt box and the steam pipe fused salt box, and an automatic control device and a protection device of the fused salt electric heating devices are arranged in the power supply device.

Description

Technical Field

[0001] This invention belongs to the field of nuclear energy utilization and heat energy transmission technology, specifically relating to a system and method for long-distance external transmission of steam from nuclear power plants, applicable to technical scenarios such as long-distance transmission of steam from power plants, heat energy conversion, and system control. Background Technology

[0002] In existing technologies, steam generated by nuclear power plants cannot be directly delivered to users due to radioactivity risks. The traditional solution is to use secondary loop steam to heat water through a surface heat exchanger to generate steam for external delivery. However, the main steam of pressurized water reactor nuclear power units is saturated steam with a low temperature, resulting in low steam parameters for heating water. This makes long-distance transportation of steam less valuable and fails to meet users' demands for high-parameter steam.

[0003] To address the aforementioned issues, existing technologies have proposed two improvement schemes: one is to construct an electric heating station within the nuclear power plant to generate high-quality superheated steam before long-distance transportation; the other is to construct a heating station at the user's location to reheat the transported low-parameter steam. However, both schemes have significant drawbacks: the former, involving an electric heating station within the nuclear power plant, requires a large heat exchange area and occupies a large footprint, resulting in high costs for transporting high-temperature, high-pressure steam and poor economic efficiency; the latter, involving a heating station at the user's location, also suffers from a large heat exchange area and occupies a large footprint. Furthermore, low-temperature steam transportation is susceptible to condensation, and condensation wastes heat and water, while failure to condense may lead to water hammer. Additionally, establishing an electric heating heat exchange station outside the power plant requires paying grid connection fees, further reducing the economic efficiency of steam supply.

[0004] Furthermore, existing technologies lack comprehensive consideration of pipeline material optimization, thermal storage integration, and power transmission and consumption coordination during long-distance transmission, resulting in low overall system efficiency and difficulty in meeting practical application requirements. Summary of the Invention

[0005] This invention provides a system and method for long-distance transmission of steam from nuclear power plants, aiming to ensure both safety and economic efficiency in long-distance transmission of steam from nuclear power plants.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A system for long-distance steam transmission from a nuclear power plant includes a water pipeline, a water pipe molten salt tank, a power supply device, a steam pipeline, and a steam pipe molten salt tank. The water pipeline is encased in a molten salt tank containing molten salt and equipped with an electric heating device for the molten salt. The water pipeline and the molten salt tank together form a water pipeline module. The steam pipeline is enclosed in a steam pipe molten salt tank, which contains molten salt and is equipped with a molten salt electric heating device. The steam pipeline and the steam pipe molten salt tank are combined to form a steam pipeline module. The outlet of the water pipeline is connected to the inlet of the steam pipeline. The water pipeline module and the steam pipeline module can dynamically change the water-steam boundary line according to the unit load and steam demand. The power supply unit is powered by the nuclear power plant. It supplies power to the molten salt electric heating devices in the water pipe molten salt tank and the steam pipe molten salt tank. The power supply unit is equipped with automatic control and protection devices for the molten salt electric heating devices.

[0007] A further improvement of the present invention is that multiple water supply pipe modules are arranged as needed along the entire water supply pipeline, and the multiple water supply pipe modules are connected in series to form a water supply pipeline.

[0008] A further improvement of the present invention is that multiple steam transmission pipe modules are arranged as needed along the entire steam transmission pipeline, and the multiple steam transmission pipe modules are connected in series to form a steam transmission pipeline.

[0009] A further improvement of the present invention is that it also includes a water pump and a steam user, wherein the outlet of the water pump is connected to the inlet of the water pipeline, and the outlet of the steam pipeline is connected to the steam user through a regulating valve.

[0010] A further improvement of this invention is that the water pump is an adjustable speed pump, and the needs of steam users are met through coordinated control of the water pump speed adjustment, the outlet regulating valve of the steam pipeline, the molten salt tank in the water pipe and the molten salt electric heating device in the steam pipe molten salt tank.

[0011] A further improvement of the present invention is that it also includes a demineralized water tank, a surface heat exchanger, and a hot water storage tank. The outlet of the demineralized water tank is connected to the first inlet of the surface heat exchanger, and the first outlet of the surface heat exchanger is connected to the inlet of the hot water storage tank. The outlet of the hot water storage tank is connected to the inlet of the water pump. The demineralized water in the demineralized water tank is strictly separated from the water used in the nuclear power plant.

[0012] A further improvement of the present invention is that it also includes a nuclear power steam supply pipe and a nuclear power condenser. The outlet of the nuclear power steam supply pipe is connected to the second inlet of the surface heat exchanger, and the second outlet of the surface heat exchanger is connected to the inlet of the nuclear power condenser. The steam in the nuclear power steam supply pipe comes from the main steam of the nuclear power unit or the steam extracted from the turbine. The steam in the nuclear power steam supply pipe exchanges heat and condenses into water in the surface heat exchanger before entering the nuclear power condenser.

[0013] A further improvement of the present invention is that the water pipeline sections are made of different materials, including carbon steel and alloy steel; The steam pipeline is constructed from different materials, including alloy steel and stainless steel.

[0014] A further improvement of the present invention is that the outlet working fluid of the surface heat exchanger can be replaced with steam, while eliminating the need for a hot water storage tank, a water pump, a water pipeline, and a water pipe molten salt tank. The molten salt in the water pipe molten salt tank and the steam pipe molten salt tank can be replaced by high-temperature heated oil or directly by electric heating.

[0015] A method for long-distance steam transmission from a nuclear power plant, the method being based on the aforementioned long-distance steam transmission system from a nuclear power plant, comprising: System setup: including demineralized water tank, surface heat exchanger, hot water storage tank, water pump, water pipeline, water pipe molten salt tank, steam pipeline, steam pipe molten salt tank, nuclear power steam supply pipeline, nuclear power condenser, power supply equipment and steam users; Initial heating stage: The demineralized water is heated to saturation by using the secondary loop steam of the nuclear power plant through the nuclear power steam supply pipe and surface heat exchanger, and then stored in hot water storage tanks; Water supply and heating stage: Saturated water is transported to the water supply pipeline through a water pump. The outlet pressure of the water pump is adjusted from 1MPa to 14MPa according to user needs. The temperature of the molten salt and water is gradually increased from 260℃ to 340℃ through the electric heating of the molten salt tank in the water pipe, thus completing the water heating and evaporation process. Steam superheating stage: The evaporated steam continues to be transported through the steam pipeline. During the transport process, the steam temperature is gradually increased from 340℃ to 475℃ by the heater in the molten salt tank of the steam pipeline, thus completing the steam superheating process. System control: The intelligent control system monitors the temperature, pressure and flow parameters of the entire conveying process, adjusts the electric heating power according to user needs, and ensures stable output steam parameters; at the same time, it utilizes the heat storage function of hot water storage tanks and molten salt in molten salt tanks to smooth out fluctuations in the power load of nuclear power plants and the steam consumption of users.

[0016] Compared with the prior art, the present invention has at least the following beneficial technical effects: (1) Security advantages The steam used by users is completely isolated from the steam of the nuclear power plant, eliminating the risk of radioactive leakage and meeting the basic requirements of nuclear safety.

[0017] (2) Economic advantages Using the pipelines that transport water vapor as heating surfaces saves on heat exchanger materials, reduces the land area required by power plants or heat users, lowers investment costs, and improves economic efficiency. Due to the long pipeline distance and large pipeline area, the heating power per unit area is small, and the local temperature of the pipeline is low, which helps to reduce the cost of pipelines and heating elements. Electricity transmission and consumption are carried out simultaneously, reducing transmission costs. Electricity generated by nuclear power plants can be used directly for heating, reducing electricity expenses.

[0018] (3) Advantages of technological flexibility Because the temperature of the transported medium increases from low to high, different materials of pipes can be used in sections, further saving investment; the hot water storage tanks and molten salt tanks on the pipelines in nuclear power plants have heat storage functions, which can smooth out fluctuations in electrical load and steam supply.

[0019] The following table compares the main performance indicators of the present invention with those of conventional technical solutions: Attached Figure Description

[0020] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a structural block diagram of a system for long-distance steam transmission from a nuclear power plant, according to the present invention.

[0022] Explanation of reference numerals in the attached figures: 1. Demineralized water tank; 2. Surface heat exchanger; 3. Hot water storage tank; 4. Water pump; 5. Water pipeline; 6. Water pipe molten salt tank; 7. Steam pipeline; 8. Steam pipe molten salt tank; 9. Nuclear power steam supply pipeline; 10. Nuclear power condenser; 11. Power supply equipment; 12. Steam user. Detailed Implementation

[0023] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0024] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0025] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0026] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0027] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0028] It should be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0029] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0030] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0031] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0032] Example 1 like Figure 1 As shown, the present invention provides a system for long-distance steam transmission from a nuclear power plant, comprising a water pipeline 5, a water pipe molten salt tank 6, a power supply device 11, a steam pipeline 7, and a steam pipe molten salt tank 8; The water supply pipe 5 is enclosed in the water pipe molten salt tank 6, which contains molten salt and is equipped with a molten salt electric heating device. The water supply pipe 5 and the water pipe molten salt tank 6 are combined to form a water supply pipe module. The steam pipeline 7 is enclosed in the steam pipe molten salt tank 8, which contains molten salt and is equipped with a molten salt electric heating device. The steam pipeline 7 and the steam pipe molten salt tank 8 are combined to form a steam pipeline module. The outlet of water pipeline 5 is connected to the inlet of steam pipeline 7. The water pipeline module and steam pipeline module can dynamically change the water-steam boundary line according to the unit load and steam demand. The power supply unit 11 is powered by the nuclear power plant. The power supply unit 11 is used to supply power to the molten salt electric heating devices in the water pipe molten salt tank 6 and the steam pipe molten salt tank 8. The power supply unit 11 is equipped with automatic control and protection devices for the molten salt electric heating devices. These automatic and protection controls are coordinated with the unit and user requirements.

[0033] In this embodiment, multiple water supply pipe modules are arranged along the entire water supply pipeline as needed, and the multiple water supply pipe modules are connected in series to form a water supply pipeline.

[0034] In this embodiment, multiple steam transmission pipeline modules are arranged as needed along the entire steam transmission pipeline, and the multiple steam transmission pipeline modules are connected in series to form a steam transmission pipeline.

[0035] In this embodiment, a water pump 4 and a steam user 12 are also included. The outlet of the water pump 4 is connected to the inlet of the water pipeline 5, and the outlet of the steam pipeline 7 is connected to the steam user 12 through a regulating valve.

[0036] In this embodiment, the water pump 4 is an adjustable speed pump. The water pump 4 speed adjustment, the outlet regulating valve of the steam pipeline 7, the molten salt tank 6 in the water pipe and the molten salt electric heating device in the steam pipeline molten salt tank 8 are coordinated and controlled to meet the needs of the steam user 12.

[0037] In this embodiment, it also includes a demineralized water tank 1, a surface heat exchanger 2, and a hot water storage tank 3. The outlet of the demineralized water tank 1 is connected to the first inlet of the surface heat exchanger 2, and the first outlet of the surface heat exchanger 2 is connected to the inlet of the hot water storage tank 3. The outlet of the hot water storage tank 3 is connected to the inlet of the water pump 4. The demineralized water in the demineralized water tank 1 is strictly separated from the water used in the nuclear power plant to prevent radioactive leakage. The size of the hot water storage tank 3 is determined according to the heat storage capacity requirements.

[0038] In this embodiment, the system also includes a nuclear power steam supply pipe 9 and a nuclear power condenser 10. The outlet of the nuclear power steam supply pipe 9 is connected to the second inlet of the surface heat exchanger 2, and the second outlet of the surface heat exchanger 2 is connected to the inlet of the nuclear power condenser 10. The steam in the nuclear power steam supply pipe 9 comes from the main steam of the nuclear power unit or the steam extracted from the turbine. The steam in the nuclear power steam supply pipe 9 exchanges heat and condenses into water in the surface heat exchanger 2 before entering the nuclear power condenser 10.

[0039] In this embodiment, the water pipeline sections are made of different materials, including carbon steel and alloy steel. The steam pipeline sections are made of different materials, including alloy steel and stainless steel.

[0040] In this embodiment, the working fluid at the outlet of the surface heat exchanger 2 can be replaced with steam, and the hot water storage tank 3, water pump 4, water pipeline 5 and water pipe molten salt tank 6 can be eliminated; the molten salt in the water pipe molten salt tank 6 and the steam pipe molten salt tank 8 can be replaced with high-temperature heated oil, or directly replaced with electric heating.

[0041] Example 2 This invention provides a method for long-distance steam transmission from a nuclear power plant, the method being based on the aforementioned long-distance steam transmission system from a nuclear power plant, comprising: System setup: Follow the instructions in the appendix Figure 1 The process system shown includes a demineralized water tank, a surface heat exchanger, a hot water storage tank, a water pump, a water pipeline, a water pipe molten salt tank, a steam pipeline, a steam pipe molten salt tank, a nuclear power plant steam supply pipeline, a nuclear power plant condenser, power supply equipment, and steam users. Initial heating stage: The demineralized water is heated to saturation (temperature about 270°C, pressure about 5.5 MPa) by the nuclear power plant secondary loop steam (temperature about 270°C, pressure about 5.5 MPa) through the nuclear power steam supply pipe 9 and surface heat exchanger 2, and stored in hot water storage tank 3. Water supply and heating stage: Saturated water is transported to the water supply pipeline through a water pump. The outlet pressure of the water pump can be adjusted from 1MPa to 14MPa according to user needs. The temperature of the molten salt and water is gradually increased from 260℃ to 340℃ through the electric heating of the molten salt tank 6 in the water pipe, thus completing the water heating and evaporation process. Steam superheating stage: The evaporated steam continues to be transported through the steam pipeline. During the transport process, the steam temperature is gradually increased from 340℃ to 475℃ by the heater in the steam pipe molten salt tank 8, thus completing the steam superheating process. System control: The intelligent control system monitors the temperature, pressure and flow parameters of the entire conveying process, adjusts the electric heating power according to user needs, and ensures stable output steam parameters; at the same time, it utilizes the heat storage function of hot water storage tanks and molten salt in molten salt tanks to smooth out fluctuations in the power load of nuclear power plants and the steam consumption of users.

[0042] Example 3 This example illustrates the supply of 475°C zero-carbon steam from a nuclear power plant to a chemical plant 70km away.

[0043] Implementation conditions Nuclear power plant type: Pressurized water reactor nuclear power unit User requirements: 7.5MPa, 475℃ zero-carbon steam Conveying distance: 70km Ambient temperature: -10℃ to 40℃ Implementation steps 1. System Setup The system is constructed according to the process shown in the attached diagram, including equipment such as demineralized water tank, surface heat exchanger, hot water storage tank, water pump, water pipeline, water pipe molten salt tank, steam pipeline, steam pipe molten salt tank, nuclear power steam supply pipeline, nuclear power condenser, power supply equipment, and steam users.

[0044] 2. Initial heating stage The demineralized water is heated to saturation (temperature approximately 260°C, pressure approximately 4.7 MPa) using steam from the nuclear power plant's secondary loop (temperature approximately 270°C, pressure approximately 5.5 MPa) through a surface heat exchanger.

[0045] 3. Water supply and heating stage Saturated water is pumped into a pipeline, with carbon steel pipes used for the first 20km and alloy steel pipes for the next 50km. The water temperature is gradually increased from 260℃ to 300℃ via electric heating to complete the evaporation process.

[0046] 4. Steam superheating stage The evaporated steam is then transported through a steam pipeline, and the steam temperature is gradually increased from 300℃ to 475℃ by electric heating to complete the steam superheating process.

[0047] 5. System Control The intelligent control system monitors temperature, pressure, and flow parameters throughout the entire transmission process, adjusting the electric heating power according to user needs to ensure stable output steam parameters. Simultaneously, the thermal storage functions of hot water tanks and molten salt tanks are utilized to mitigate fluctuations in the nuclear power plant's electrical load and the user's steam consumption.

[0048] Key Parameter Control Table

[0049] Implementation effect This embodiment successfully achieved the safe delivery of steam from a nuclear power plant to a chemical plant 70 km away, with output steam parameters fully meeting user requirements (7.5 MPa, 475°C zero-carbon steam). The system operates stably, provides good radioactive isolation, and is approximately 30% more economical than traditional solutions.

[0050] Example 4: Differentiated Steam Supply for Multiple Users in an Industrial Park (Transport Distance 50km) Implementation conditions Nuclear power plant type: Pressurized water reactor nuclear power unit User requirements: To provide steam with different parameters (350℃ / 3.0MPa saturated steam, 420℃ / 4.0MPa superheated steam) to 3 chemical companies and 2 building materials companies in the industrial park. Conveying distance: 50km Ambient temperature: -5℃ to 35℃ Implementation steps System setup: Two branch pipelines are set at the end of the main steam pipeline to connect to users with different parameter requirements; the hot water storage tank is expanded to 1.5 times the original design capacity to enhance the heat storage and peak shaving capacity.

[0051] Initial heating stage: The demineralized water is heated to 250℃ / 4.5MPa saturation using steam from the nuclear power plant's secondary loop (270℃ / 5.5MPa) and stored in a hot water storage tank.

[0052] Water heating stage: Carbon steel pipelines are used for the first 30km, and alloy steel pipelines are used for the next 20km; the water temperature is raised from 250℃ to 340℃ through segmented electric heating to complete the evaporation process.

[0053] In the phase of differentiated steam transmission: after the main pipeline delivers 340℃ steam to the park, the steam is superheated to 350℃ and 420℃ respectively through the local electric heating modules of the branch pipelines to meet the needs of different users.

[0054] Multi-parameter collaborative control: A distributed control system (DCS) is adopted to collect pressure and flow data from each user end in real time, and dynamically adjust the power of each heating section and the opening of branch valves to ensure parameter stability.

[0055] Key Parameter Control Table

[0056] Implementation effect To achieve differentiated steam supply with multiple parameters through a single pipeline and meet the diverse energy needs of enterprises in the park; The system's overall energy consumption is reduced by 25% compared to traditional pipeline transportation solutions, and its footprint is reduced by 30%. The thermal storage system effectively mitigates the fluctuations caused by the surge in steam consumption during the morning peak (up to 1.3 times the design value), and its annual operational stability reaches 99.8%.

[0057] Example 5: Cross-regional winter heating in northern cities (transmission distance 30km) Implementation conditions Nuclear power plant type: Pressurized water reactor nuclear power unit User requirement: To provide winter heating hot water (180℃ / 1.2MPa) for 12 million square meters of buildings in a new urban area in northern China. Conveying distance: 30km Ambient temperature: -20℃ to 10℃ Implementation steps System adaptation and modification: Replace the terminal steam pipeline with a high-temperature resistant hot water pipeline and remove the electric heating module of the superheated section; set up a heat exchange station at the city entrance to convert the delivered hot water into hot water for the secondary heating network (60℃ / 0.3MPa).

[0058] Low-temperature environment preheating: Before starting in winter, the water supply pipeline is preheated 24 hours in advance by molten salt electric heating module to prevent freezing and blockage at low temperatures.

[0059] Initial heating stage: Demineralized water is heated to 170℃ / 1.3MPa using steam from the secondary loop of the nuclear power plant and stored in a hot water storage tank.

[0060] Long-distance heat preservation and transportation: The water pipeline adopts a polyurethane insulation layer and electric heat tracing system throughout. Through segmented temperature monitoring, the heat tracing power is automatically adjusted to ensure that the temperature of the hot water is not lower than 165℃ when it is delivered to the first station.

[0061] Intelligent control of heating load: Based on weather forecasts and building heat demand models, the heat storage capacity of hot water tanks is adjusted in advance, the delivery flow is increased during morning and evening peak hours, and the heating power is reduced during off-peak hours to achieve dynamic balance between supply and demand.

[0062] Key Parameter Control Table

[0063] Implementation effect It replaced 12 coal-fired boilers in the area, achieving zero carbon emissions during the heating season and reducing soot emissions by about 2,300 tons and sulfur dioxide emissions by about 1,800 tons per year. The average temperature drop along the pipeline is 0.4℃ / km, far lower than the 1.2℃ / km of traditional hot water transportation, resulting in an improvement in thermal efficiency of approximately 25%. The thermal storage system successfully coped with the surge in heating load during the extreme cold wave (temperature dropped by 12°C), and the indoor temperature compliance rate for users was 100%.

[0064] Example 6: Long-distance transportation of high-temperature process steam in metallurgical enterprises (transportation distance 100km) Implementation conditions Nuclear power plant type: Pressurized water reactor nuclear power unit User requirement: To provide 500℃ / 5.0MPa superheated steam to a steel company 100km away for blast furnace injection and hot rolling processes. Conveying distance: 100km Ambient temperature: 0℃ to 40℃ Implementation steps Enhanced high-parameter system: The entire water pipeline is made of P91 alloy steel, and the steam pipeline is made of TP347H stainless steel; the power of the molten salt electric heating module has been increased to 1.8 times that of the original design to meet the high-temperature heating requirements.

[0065] Initial overpressure heating: The demineralized water is heated to 270℃ / 5.8MPa (higher than the secondary loop steam parameters of the nuclear power plant), utilizing the high-pressure heat storage capacity of the hot water storage tank to reduce pressure loss during transportation.

[0066] Stepwise heating evaporation: The water temperature is raised from 270℃ to 360℃ in the first 40km to complete evaporation; the steam temperature is maintained at 360℃ in the middle 30km, and then gradually superheated to 500℃ in the last 30km.

[0067] Long-distance parameter compensation: One pressure monitoring and compensation device is set up every 20km to supplement the pressure through an automatic regulating valve to ensure that the terminal steam pressure is not lower than 5.0MPa.

[0068] High-temperature safety protection: The pipeline adopts a three-layer composite insulation structure (aluminum silicate + aerogel + galvanized steel plate) to keep the surface temperature below 50℃; an online leak monitoring system is installed to provide real-time early warning of pipeline abnormalities.

[0069] Key Parameter Control Table

[0070] Implementation effect For the first time, 500℃-level high-temperature steam from a nuclear power plant was transported over a distance of 100km, fully meeting the process requirements of steel enterprises; The system heat loss is controlled within 7.8%, which reduces heat loss by more than 40% compared with the traditional direct transmission scheme; By adopting alloy steel pipes and an intelligent monitoring system, the unplanned downtime throughout the year is 0, the equipment reliability reaches 99.9%, and the annual operation and maintenance cost is reduced by 18% compared with the traditional solution.

[0071] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the scope of the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0072] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A system for long-distance steam transmission from a nuclear power plant, characterized in that, It includes a water pipeline (5), a water pipe molten salt tank (6), a power supply device (11), a steam pipeline (7), and a steam pipe molten salt tank (8); The water supply pipe (5) is enclosed in the water pipe molten salt tank (6), which contains molten salt and is equipped with a molten salt electric heating device. The water supply pipe (5) and the water pipe molten salt tank (6) are combined to form a water supply pipe module. The steam pipeline (7) is enclosed in the steam pipe molten salt tank (8), which contains molten salt and is equipped with a molten salt electric heating device. The steam pipeline (7) and the steam pipe molten salt tank (8) are combined to form a steam pipeline module. The outlet of the water pipeline (5) is connected to the inlet of the steam pipeline (7). The water pipeline module and the steam pipeline module can dynamically change the water and steam boundary line according to the unit load and steam demand. The power supply device (11) is supplied by the nuclear power plant. The power supply device (11) is used to supply power to the molten salt electric heating device in the water pipe molten salt tank (6) and the steam pipe molten salt tank (8). The power supply device (11) is equipped with an automatic control device and a protection device for the molten salt electric heating device.

2. The system for long-distance steam transmission from a nuclear power plant according to claim 1, characterized in that, Multiple water supply pipe modules are arranged as needed along the entire water supply pipeline, and these modules are connected in series to form the water supply pipeline.

3. The system for long-distance steam transmission from a nuclear power plant according to claim 1, characterized in that, Multiple steam transmission pipeline modules are arranged as needed along the entire steam transmission pipeline, and these modules are connected in series to form the steam transmission pipeline.

4. A system for long-distance steam transmission from a nuclear power plant according to claim 1, characterized in that, It also includes a water pump (4) and a steam user (12). The outlet of the water pump (4) is connected to the inlet of the water pipeline (5), and the outlet of the steam pipeline (7) is connected to the steam user (12) through a regulating valve.

5. A system for long-distance steam transmission from a nuclear power plant according to claim 4, characterized in that, The water pump (4) is a speed adjustable pump. The water pump (4) speed adjustment, the outlet regulating valve of the steam pipeline (7), the molten salt tank (6) of the water pipe and the molten salt electric heating device in the steam pipeline molten salt tank (8) are coordinated to meet the needs of the steam user (12).

6. A system for long-distance steam transmission from a nuclear power plant according to claim 4, characterized in that, It also includes a demineralized water tank (1), a surface heat exchanger (2) and a hot water storage tank (3). The outlet of the demineralized water tank (1) is connected to the first inlet of the surface heat exchanger (2), and the first outlet of the surface heat exchanger (2) is connected to the inlet of the hot water storage tank (3). The outlet of the hot water storage tank (3) is connected to the inlet of the water pump (4). The demineralized water in the demineralized water tank (1) is strictly separated from the water used in the nuclear power plant.

7. A system for long-distance steam transmission from a nuclear power plant according to claim 6, characterized in that, It also includes a nuclear power steam supply pipe (9) and a nuclear power condenser (10). The outlet of the nuclear power steam supply pipe (9) is connected to the second inlet of the surface heat exchanger (2), and the second outlet of the surface heat exchanger (2) is connected to the inlet of the nuclear power condenser (10). The steam in the nuclear power steam supply pipe (9) comes from the main steam of the nuclear power unit or the steam extracted from the turbine. The steam in the nuclear power steam supply pipe (9) exchanges heat in the surface heat exchanger (2), condenses into water, and then enters the nuclear power condenser (10).

8. A system for long-distance steam transmission from a nuclear power plant according to claim 1, characterized in that, The water pipeline is constructed from different materials in different sections, including carbon steel and alloy steel; The steam pipeline is constructed from different materials, including alloy steel and stainless steel.

9. A system for long-distance steam transmission from a nuclear power plant according to claim 6, characterized in that, The working fluid at the outlet of the surface heat exchanger (2) can be replaced with steam, and the hot water storage tank (3), water pump (4), water pipeline (5) and water pipe molten salt tank (6) are eliminated. The molten salt in the water pipe molten salt tank (6) and the steam pipe molten salt tank (8) can be replaced by high-temperature heating oil or directly by electric heating.

10. A method for long-distance external transmission of steam from a nuclear power plant, characterized in that, This method, based on the long-distance steam transmission system from a nuclear power plant as described in claim 7, includes: System setup: including demineralized water tank, surface heat exchanger, hot water storage tank, water pump, water pipeline, water pipe molten salt tank, steam pipeline, steam pipe molten salt tank, nuclear power steam supply pipeline, nuclear power condenser, power supply equipment and steam users; Initial heating stage: The demineralized water is heated to saturation by using the nuclear power plant's secondary loop steam through the nuclear power steam supply pipe (9) and surface heat exchanger (2), and then stored in the hot water storage tank (3). Water heating stage: Saturated water is transported to the water pipeline through a water pump. The outlet pressure of the water pump is adjusted from 1MPa to 14MPa according to the user's needs. The temperature of the molten salt and water is gradually increased from 260℃ to 340℃ through the electric heating of the molten salt tank (6) in the water pipe, thus completing the water heating and evaporation process. Steam overheating stage: The evaporated steam is continued to be transported through the steam pipeline. During the transport process, the steam temperature is gradually increased from 340°C to 475°C by the heater in the steam pipe molten salt tank (8) to complete the steam overheating process. System control: The intelligent control system monitors the temperature, pressure and flow parameters of the entire transportation process, adjusts the electric heating power according to user needs, and ensures stable output steam parameters; at the same time, it utilizes the heat storage function of hot water storage tanks and molten salt in molten salt tanks to smooth out fluctuations in the power load of nuclear power plants and the steam consumption of users.

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