A low thermal resistance cylindrical steam generator for nuclear energy

Abstract

This invention relates to the field of steam generator technology, specifically to a low thermal resistance cylindrical steam generator for nuclear power. It includes a shell with a steam inlet on the upper side, multiple water inlets on the lower side, and a pipe box on the right side. U-shaped heat exchange tubes are installed inside the shell, positioned and assembled via fixing holes in a vertical fixing plate. A spiral turbulence sleeve with helical ribs is coaxially arranged between the fixing holes and the heat exchange tubes. A diffuser plate with spray nozzles is installed at the pipe box, with the spray nozzle axis perpendicular to the spiral turbulence sleeve. The spray nozzles are equipped with baffles, arc-shaped guide surfaces, and guide nozzles. A polygonal flow-dividing cone and a hydrophobic anti-scaling coating are provided on the lower side of the diffuser plate. Spiral heat-conducting fins and fracture grooves are installed on the outer side of the heat exchange tubes. A pressure relief groove is opened in the fixing holes. This invention features a compact cylindrical structure and extremely low thermal resistance, eliminating heat exchange dead zones, balancing flow field pressure, and significantly improving nuclear steam generation efficiency and equipment operational stability.

Description

Technical Field

[0001] This invention relates to the field of steam generator technology, specifically to a low thermal resistance cylindrical steam generator for nuclear energy. Background Technology

[0002] Existing cylindrical steam generators for nuclear power plants are constrained by the compact installation space of the nuclear island and the high heat flux density heat transfer requirements. They suffer from fundamental technical defects in the coupling design of low thermal resistance performance and compact cylindrical structure: In order to meet the compact layout requirements, the flow channel cross-section is narrow and the tube bundle is densely arranged, which leads to a significant increase in the flow resistance of the working fluid. The overall heat transfer thermal resistance remains high, making it impossible to achieve the high efficiency heat transfer requirements of low thermal resistance and high flux. Imbalanced flow distribution in the flow channel can easily form local low flow velocity heat transfer dead zones. The interfacial heat transfer thermal resistance between the tube wall and the working fluid cannot be effectively reduced. Moreover, the fixed arrangement of the tube bundle causes heat transfer overload near the heat source section and insufficient heat transfer at the far end, further aggravating uneven thermal resistance distribution and heat loss. If the thermal resistance is reduced simply by increasing the structural size, it is difficult to adapt to the harsh operating conditions of cylindrical installation and space constraints in nuclear power systems. At the same time, the fixed tube bundle is in a local high temperature state for a long time, which will also cause problems such as thermal resistance degradation and shortened equipment life. Existing technology has always failed to meet the core requirements of compact cylindrical structure and ultra-low thermal resistance high efficiency heat transfer. Summary of the Invention

[0003] The purpose of this invention is to provide a low thermal resistance cylindrical steam generator for nuclear energy to solve the problem of uneven thermal resistance distribution.

[0004] To achieve the above objectives, the present invention provides the following technical solution: A low thermal resistance cylindrical steam generator for nuclear energy includes a shell, a steam inlet on the upper side of the shell, multiple water inlets on the lower side of the shell, a tube box on the right side of the shell, and multiple U-shaped heat exchange tubes inside the shell, one end of each heat exchange tube being fixedly connected to the tube box. Multiple fixing plates are mounted on the heat exchange tubes, all arranged vertically, and each fixing plate has fixing holes corresponding to the positions of the heat exchange tubes. The fixing plates are connected to the heat exchange tubes through these fixing holes, and the fixing holes are coaxial with the heat exchange tubes. A spiral baffle sleeve is provided, extending to the left and right ends of the fixing hole. The spiral baffle sleeve has spiral ribs on its side, and the outer side of the spiral ribs fits into the fixing hole. A diffuser plate is provided at the water inlet, and one end of the diffuser plate is fixedly installed to the pipe box. A water inlet hole is provided on the side of the diffuser plate opposite to the water inlet, and the position of the water inlet hole corresponds to that of the water inlet. Multiple water spray holes are provided on the side of the diffuser plate opposite to the spiral baffle sleeve, and the water spray holes are connected to the water inlet hole. The central axis of the spiral baffle sleeve is perpendicular to the central axis of the water spray holes.

[0005] By adopting an integrated structural layout with a top steam inlet, multiple lower water inlets, and a side tube box, coupled with a U-shaped heat exchange tube bundle fixedly connected to the tube box, and multiple vertically arranged fixing plates, precise positioning and reliable assembly of the heat exchange tubes are achieved using fixing holes on the fixing plates corresponding to the positions of the heat exchange tubes. A spiral baffle sleeve extending towards both ends of the fixing hole is installed coaxially between the fixing hole and the heat exchange tube, with the outer side of the spiral ribs on the side of the baffle sleeve tightly fitted to the fixing hole. A diffuser plate fixedly installed to the tube box is also configured at the water inlet, allowing the water inlet on the diffuser plate corresponding to the water inlet position to connect to multiple spray holes facing the spiral baffle sleeve. It is strictly ensured that the central axis of the spiral baffle sleeve is perpendicular to the central axis of the spray holes. Through this series of structured and collaborative designs, the stable and solid heat exchange tube bundle is achieved. The design ensures the overall equipment maintains a compact cylindrical shape to fit the limited installation space of the nuclear island. Furthermore, the spiral turbulence sleeve and spiral ribs significantly enhance turbulence, effectively disrupting the laminar boundary layer at the heat exchange tube walls. This fundamentally reduces the interfacial heat transfer resistance between the tube walls and the working fluid. Simultaneously, the combination of the diffuser plate and spray nozzles ensures even water distribution and precise spraying, avoiding localized low-velocity heat transfer dead zones caused by imbalanced working fluid flow distribution. The vertical axis layout ensures the working fluid spray direction precisely matches the turbulence direction of the spiral turbulence sleeve, further enhancing the working fluid disturbance effect and heat transfer uniformity, reducing flow resistance. This design balances the core requirements of a compact cylindrical structure with low thermal resistance and high-throughput, high-efficiency heat exchange. It also alleviates uneven heat transfer and localized overheating, optimizes thermal resistance distribution, and improves the stability and service life of the equipment.

[0006] Preferably, the plurality of water spray holes have a rectangular cross-section, and the cross-sectional width of the water spray hole gradually increases with the increase of the distance between the water spray hole opening and the water inlet. A baffle is provided at the center of the water spray hole, the direction of the baffle is perpendicular to that of the water inlet, and the upper surface of the baffle is attached to the fixing plate. The inner wall of the outlet of the water spray hole is provided with an arc-shaped guide surface.

[0007] By designing the spray nozzles with rectangular cross-sections, and gradually increasing the width of the cross-section as the distance between the nozzle opening and the inlet increases, and by installing a baffle plate perpendicular to the inlet direction at the center of the nozzle with its upper surface tightly fitted to the fixing plate, and by setting an arc-shaped guide surface on the inner wall of the nozzle outlet, the rectangular cross-section better matches the internal spatial layout of the cylindrical generator and the jet connection requirements of the spiral turbulence sleeve. The gradually widening design effectively compensates for the pressure loss along the water flow, ensuring uniform and stable water output from each nozzle. This avoids the formation of localized low-velocity heat exchange dead zones due to uneven flow distribution from the source. The baffle plate can divide the water flow, regulate the flow field, and prevent water flow deviation and mixing. The flow and eddy phenomena significantly improve the directionality and consistency of the water jet. Its structure, which is attached to the fixed plate, also enhances the structural stability of the overall component. The arc-shaped guide surface can significantly reduce the flow resistance at the water outlet, avoid the generation of eddies and cavitation, and guide the water flow smoothly and accurately into the spiral turbulence sleeve in a vertical direction. This design and the spiral turbulence sleeve and spiral rib structure form a highly efficient synergy, further enhancing the turbulence of the working fluid, more thoroughly destroying the laminar boundary layer of the heat exchange tube wall, continuously reducing the interfacial heat exchange thermal resistance, and making the uniform heat exchange and low thermal resistance effects more stable and prominent. It is suitable for the high-efficiency heat exchange requirements under the compact cylindrical structure of nuclear steam generators, and comprehensively improves the heat exchange uniformity and operational reliability of the equipment.

[0008] Preferably, a heat-conducting plate is provided on the outside of the heat exchange tube. The heat-conducting plate is spiral-shaped, and it is attached to the spiral turbulence sleeve. The heat-conducting plate extends along the direction of the spiral ribs.

[0009] By installing spiral heat-conducting fins on the outside of the heat exchange tube, and ensuring that the fins are tightly fitted to the spiral turbulence sleeve and extend along the direction of the spiral ribs, the spiral structure can significantly expand the effective heat exchange area of ​​the heat exchange tube, breaking through the heat exchange bottleneck of limited heat exchange area in traditional bare tubes. The close-fitting installation can eliminate the thermal resistance of the air gap between the heat-conducting fins and the spiral turbulence sleeve, allowing heat to be transferred rapidly between the heat exchange tube, heat-conducting fins, spiral turbulence sleeve, and shell-side working fluid via the shortest path and with the highest efficiency. The layout of the heat-conducting fins extending along the spiral ribs can match the spiral turbulence path of the spiral turbulence sleeve, guiding the working fluid to flow in an orderly spiral along the common trajectory of the spiral ribs and heat-conducting fins. This process further enhances the turbulence intensity of the working fluid, more comprehensively and thoroughly disrupting the laminar boundary layer on the heat exchange tube wall. It simultaneously reduces the total thermal resistance of the heat exchange interface from two dimensions: enhanced heat conduction and enhanced turbulence. By actively increasing the heat exchange area, optimizing the heat transfer path, and enhancing the spiral turbulence effect, it further amplifies the core advantages of low thermal resistance, high flux, and uniform heat exchange. This effectively solves the problems of high thermal resistance and insufficient heat flux density caused by the dense tube bundles and compact space of nuclear electric cylindrical steam generators, comprehensively improving the heat exchange efficiency and operational stability of the equipment, and better meeting the stringent requirements of high heat flux density and compact installation in nuclear energy systems.

[0010] Preferably, a flow-dividing cone is provided on the lower side of the diffuser plate corresponding to the water inlet, and the horizontal cross-section of the flow-dividing cone is polygonal. The tip of the flow-dividing cone faces the water inlet direction. Multiple evenly distributed throttling holes are opened on the bottom surface of the flow-dividing cone. The water inlet guides the water flow to the throttling holes through the independent flow-guiding surface of the flow-dividing cone. The throttling holes are connected to the spray holes.

[0011] By setting a diversion cone at the position corresponding to the water inlet on the lower side of the diffuser plate, and designing the horizontal cross-section of the diversion cone as a polygonal structure, the tip of the diversion cone is precisely oriented towards the water inlet. Multiple evenly distributed throttling holes are opened on the bottom surface of the diversion cone, allowing the water flow from the inlet to be guided to each throttling hole through an independent guide surface of the diversion cone, and then connected to each spray hole. Compared with a conventional circular cone, the polygonal horizontal cross-section diversion cone has superior structural rigidity and resistance to water flow impact, making it suitable for the harsh operating conditions of nuclear steam generators. It also allows for more regular circumferential diversion of the inlet water, preventing the formation of local eddies and flow deviations on the cone surface. The layout with the tip facing the water inlet direction provides efficient buffering and guidance for the high-speed inlet water, significantly reducing the direct impact force, stabilizing the inlet water pressure and flow field, and eliminating flow fluctuations, flow deviations, and mixing problems caused by water flow impact turbulence. The evenly distributed throttling holes on the bottom surface can control the total inlet water flow. Precise and equal division ensures that the flow rate, velocity, and pressure of each water stream remain highly consistent, solving the core problem of uneven flow distribution from the source. Independent flow guides create dedicated water delivery channels for each throttling orifice and corresponding spray nozzle, eliminating crosstalk and competition between water streams and ensuring uniform and stable outflow from all spray nozzles. The diversion cone first achieves uniform diversion, pressure stabilization, and flow stabilization of the inlet water, providing a stable and uniform foundation for the spray nozzles. Then, progressively widened spray nozzles compensate for pressure loss along the flow path, baffles regulate the water jet direction, and arc-shaped guide surfaces smoothly guide the outflow. This dual protection ensures that the water flows precisely and vertically into the spiral turbulence sleeve, enhancing the turbulence intensity of the working fluid, more thoroughly disrupting the laminar boundary layer of the heat exchange tube wall, continuously reducing the thermal resistance of the heat exchange interface, and further eliminating localized low-velocity heat exchange dead zones caused by uneven flow distribution. This optimizes the uniformity of thermal resistance distribution and comprehensively improves the heat exchange efficiency of low-thermal-resistance cylindrical steam generators for nuclear power.

[0012] Preferably, the heat-conducting sheet is provided with equidistant fracture grooves, which make the heat-conducting sheet form an intermittent flow guiding structure.

[0013] By creating equidistant fracture grooves on the heat-conducting plate, the uniformly distributed fracture grooves transform the originally continuous spiral heat-conducting plate into a discontinuous flow-guiding structure. This design effectively resolves the problems of thermal stress concentration, structural warping, and even cracking caused by repeated thermal expansion and contraction under the harsh operating conditions of high temperature, high pressure, and alternating temperature in nuclear steam generators. Simultaneously, the discontinuous structure does not disrupt the spiral flow-guiding morphology of the heat-conducting plate, preserving and continuing the fit between the heat-conducting plate and the spiral turbulence sleeve. This continuously enhances the turbulence intensity of the working fluid, thoroughly destroying the laminar boundary layer on the heat exchange tube wall, ensuring that the core effects of enhanced heat transfer and reduced interfacial thermal resistance are not diminished. Furthermore, the discontinuous flow-guiding structure can significantly improve the flow of heat. By reducing the large-area continuous contact between the working fluid and the heat-conducting plate, the probability of scale and impurities adhering and depositing on the surface of the heat-conducting plate is reduced, avoiding the continuous increase in heat exchange resistance due to scaling, and maintaining a high-efficiency heat conduction state for a long time. The equally spaced fracture grooves also make the overall stress distribution of the heat-conducting plate more uniform, significantly improving the thermal fatigue resistance and structural stability of the heat-conducting plate, making it more suitable for the long-term reliable operation requirements of nuclear power equipment. It further makes up for the shortcomings of continuous spiral heat-conducting plates, which are prone to thermal stress defects and scaling and fouling, making the high-efficiency heat exchange performance of the heat-conducting plate more stable and durable. It continuously consolidates the core advantages of low thermal resistance, high throughput and uniform heat exchange of the equipment, and comprehensively improves the operational safety, heat exchange stability and service life of low thermal resistance cylindrical steam generators for nuclear power.

[0014] Preferably, the fixing hole has multiple pressure relief grooves that connect adjacent fixing holes along its plate surface direction.

[0015] By creating multiple balanced pressure relief grooves connecting adjacent fixing holes along the plate surface in the fixing holes of the fixed plate, and through the through-channel structure between adjacent fixing holes, the pressure of the working fluid in each fixing hole area is interconnected and evenly distributed. This effectively eliminates the local pressure difference and pressure accumulation problems caused by vertical water spray from the spray holes, the turbulence of the spiral turbulence sleeve, and the dense arrangement of the heat exchange tube bundle. It significantly reduces the flow resistance and pressure fluctuation of the working fluid around the fixing holes, keeping the flow field stable and uniform. This avoids impact deformation, sealing failure, or structural fatigue damage to core components such as the fixed plate, heat exchange tubes, and spiral turbulence sleeve caused by local high pressure. At the same time, the stable pressure environment ensures that the spiral turbulence effect of the spiral turbulence sleeve is not disturbed by pressure turbulence, ensuring that the working fluid continuously scours the heat exchange tube wall in a stable turbulent state, destroying the laminar boundary layer and maintaining a low thermal resistance heat exchange state. This further solves the technical pain points of uneven pressure distribution and high flow resistance that are prone to occur in compact tube bundle layouts.

[0016] Preferably, a guide nozzle is provided on the outer side of the outlet of the water spray hole, and a guide cone surface is provided on the side of the guide nozzle opposite to the baffle plate. The outlet of the guide nozzle is aligned with the starting end of the spiral rib of the spiral turbulence sleeve.

[0017] By adding a guide nozzle at the water spray outlet and setting a guide cone on the side opposite to the baffle plate, and precisely aligning the outlet of the guide nozzle with the starting end of the spiral rib of the spiral turbulence sleeve, the guide cone can perform secondary rectification and convergence on the water flow guided by the regular and arc-shaped guide surface of the baffle plate. This effectively eliminates residual eddies and deflection at the water outlet, significantly reducing energy loss and flow resistance during water jetting. This allows the water flow to be ejected in a more concentrated, smoother, and more stable state. The guide nozzle further constrains the jetting path and direction of the water flow, preventing water diffusion and scattering, and ensuring that the water flow acts precisely and without deviation on the spiral turbulence sleeve. The outlet is aligned with the starting end of the spiral rib. The end-position design allows the water flow to directly cut into the starting position of the spiral turbulence sleeve, enabling the water flow to form a stable and orderly spiral flow from the beginning. This maximizes the turbulence effect of the spiral turbulence sleeve, better disrupts the laminar boundary layer of the heat exchange tube wall, and continuously reduces the thermal resistance of the heat exchange interface. The baffle and arc-shaped guide surface first complete the diversion and pressure stabilization, primary rectification and smooth guidance of the water flow. The guide nozzle and guide cone then achieve secondary flow convergence, precise orientation and precise docking. This dual guarantee ensures the concentration, directionality and stability of the water jet, solves the problems of water jet dispersion, docking deviation and insufficient turbulence, further improves the turbulence intensity and heat exchange uniformity of the working fluid, and eliminates local heat exchange dead zones.

[0018] Preferably, the outer surface of the flow divider cone is covered with a hydrophobic and anti-scaling coating, which is a polytetrafluoroethylene coating with a thickness of 0.1 mm to 0.3 mm.

[0019] By covering the entire outer surface of the diversion cone with a hydrophobic and anti-scaling coating, and controlling the coating thickness within the range of 0.1mm to 0.3mm, the special surface properties of the hydrophobic and anti-scaling coating effectively reduce the adhesion between the water flow and the surface of the diversion cone. This inhibits the adhesion, deposition, and scaling of pollutants such as scale, impurities, and corrosion products on the surface of the diversion cone from the source. This prevents scale buildup from clogging the cone surface, throttling orifices, and independent drainage surfaces of the diversion cone, thus avoiding impacts on water diversion and transport efficiency. Simultaneously, the 0.1mm to 0.3mm coating thickness ensures the bonding strength between the coating and the diversion cone substrate, enabling it to function effectively in nuclear steam generators. It is not easily detached under harsh working conditions of high temperature, high pressure, and high-speed water flow, and has excellent durability and impact resistance. It does not increase the external size of the diversion cone, change the flow channel cross-section and water flow path, and further reduce the flow friction resistance of water on the surface of the diversion cone, making the water diversion smoother and the pressure more stable. At the same time, it delays the corrosion and aging of the surface of the diversion cone, extends the service life of the core diversion component, and solves the technical pain points of diversion cones being prone to scaling, clogging and corrosion during long-term operation. It ensures the long-term stable operation of the diversion structure, and provides a reliable guarantee for the precise spraying of the subsequent water jet holes and the efficient turbulence of the spiral turbulence sleeve.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. By integrating the steam inlet, water inlet, and tube box into a single shell, assembling U-shaped heat exchange tubes, using vertical fixing plates with fixing holes for limiting, setting spiral turbulence sleeves and spiral ribs coaxially with the fixing holes, and ensuring that the spray holes of the diffuser plate are perpendicular to the axis of the spiral turbulence sleeve, the heat exchange tube bundle is precisely fixed and the cylindrical structure is compact. This enhances the turbulence of the working fluid in the shell side to disrupt the laminar boundary layer, reduces the heat exchange thermal resistance of the tube wall from the source, and eliminates local low-velocity heat exchange dead zones by uniformly distributing the flow. It also takes into account the need for compact installation space, low thermal resistance, and high-throughput heat exchange, and steadily improves the basic efficiency and operational safety of the equipment's heat exchange.

[0021] 2. By using rectangular progressively widened spray holes, baffle rectification, arc-shaped guide surface guidance, polygonal flow splitting cone, independent flow diversion and throttling holes, and guide nozzles and guide cone surfaces precisely aligned with the starting end of the spiral ribs, the pressure loss along the flow path is compensated, achieving uniform water distribution and stable pressure and flow. Secondary rectification and flow convergence avoid jet dispersion and flow deviation, increase the turbulence effect of the spiral turbulence sleeve, eliminate flow field disturbance and uneven heat exchange problems, solve the industry problem of unbalanced flow distribution and uneven thermal resistance distribution, and ensure efficient heat exchange and signal-like stable heat transfer efficiency in two-phase flow.

[0022] 3. By incorporating spiral heat-conducting fins on the outside of the heat exchange tubes, equidistant fracture grooves on the heat-conducting fins, a fixed-hole interconnected balanced pressure relief groove, and a hydrophobic and anti-scaling coating on the flow-dividing cone, the heat exchange area is expanded and gap thermal resistance is eliminated. This releases thermal stress to prevent structural deformation, balances flow channel pressure to reduce component impact damage, inhibits scale adhesion and flow channel blockage, maintains a low thermal resistance heat exchange state for a long time, improves resistance to thermal fatigue and erosion, comprehensively extends the service life of the equipment, and ensures the long-term stable and reliable operation of the nuclear steam generator. Attached Figure Description

[0023] Figure 1 This is a front view of the low thermal resistance cylindrical steam generator for nuclear energy according to the present invention; Figure 2 This is a left view of the low thermal resistance cylindrical steam generator for nuclear energy according to the present invention; Figure 3 for Figure 2 Cross-sectional view of AA in the middle; Figure 4 This is a structural schematic diagram of the heat exchange tubes, the fixed plate, and the diffuser plate. Figure 5 for Figure 4 Enlarged view of point B in the middle; Figure 6 This is a schematic diagram of the structure of the diffuser plate of the present invention; Figure 7 This is a front view of the diffusion plate of the present invention; Figure 8 for Figure 7 Cross-sectional view of CC in the middle; Figure 9This is a schematic diagram of the structure of the flow divider cone and the water inlet hole of the present invention; Figure 10 This is a left view of the diffuser plate and the flow-diverting cone of the present invention; Figure 11 for Figure 10 Cross-sectional view of DD in the middle; Figure 12 for Figure 11 Enlarged view at point E in the middle; Figure 13 This is a schematic diagram of the structure of the fixing plate of the present invention.

[0024] In the diagram: 1. Shell; 101. Steam inlet; 102. Water inlet; 103. Tube box; 104. Heat exchange tube; 105. Fixed end; 106. Heat medium inlet; 107. Heat medium outlet; 108. Fixed support; 2. Fixed plate; 201. Fixed hole; 202. Balance pressure relief groove; 3. Spiral turbulence sleeve; 301. Spiral rib; 4. Diffuser plate; 401. Water inlet hole; 402. Water spray hole; 403. Baffle plate; 404. Arc-shaped guide surface; 5. Heat-conducting plate; 501. Fracture groove; 6. Diverting cone; 7. Throttling orifice; 8. Guide nozzle; 801. Guide cone surface. Detailed Implementation

[0025] Please see Figures 1 to 13 This invention provides a low thermal resistance cylindrical steam generator for nuclear energy, the technical solution of which is as follows: A low thermal resistance cylindrical steam generator for nuclear energy includes a shell 1. A steam port 101 is located on the upper side of the shell 1, and multiple water inlets 102 are located on the lower side of the shell 1. Fixed supports 108 are located on both sides of each water inlet 102. A tube box 103 is located on the right side of the shell 1 and is fixedly installed at a fixed end 105 of the shell 1. A heat medium inlet 106 is located on the upper side of the fixed end 105, and a heat medium outlet 107 is located on the lower side of the fixed end 105. Both the heat medium inlet 106 and the heat medium outlet 107 are connected to heat exchange tubes 104 through the tube box 103. The shell 1 contains multiple heat exchange tubes 104, each U-shaped, with one end fixedly connected to the tube box 103. Multiple fixing plates 2 are mounted on the heat exchange tubes 104, arranged vertically. Each fixing plate 2 has fixing holes 201 corresponding to the positions of the heat exchange tubes 104. Multiple pressure relief grooves 202 connecting adjacent fixing holes 201 are formed along the plate surface of each fixing hole 201. All fixing plates 2 are connected to the heat exchange tubes 104 through the fixing holes 201, and the fixing holes 201 and heat exchange tubes 104 are coaxial. A spiral turbulence sleeve 3 is provided, with a radial single-sided gap of 0.4 mm between the inner wall of the spiral turbulence sleeve 3 and the outer wall of the heat exchange tube 104. The spiral turbulence sleeve 3 extends to the left and right ends of the fixing hole 201. Spiral ribs 301 are provided on the side of the spiral turbulence sleeve 3, and the outer side of the spiral ribs 301 fits into the fixing hole 201. A heat-conducting plate 5 is coaxially provided on the outer side of the heat exchange tube 104. The heat-conducting plate 5 is spiral-shaped and fits into the spiral turbulence sleeve 3. The heat-conducting plate 5 extends along the direction of the spiral ribs 301, so that the water flow enters the spiral path of the heat-conducting plate 5 along the rotation path of the spiral ribs 301. The heat-conducting plate 5 is provided with equidistant fracture grooves 501, which run through the entire heat-conducting plate 5. The fracture grooves 501 make the heat-conducting plate 5 form an intermittent flow guiding structure. A diffuser plate 4 is provided at the water inlet 102, and one end of the diffuser plate 4 is fixedly installed with the pipe box 103. A flow-dividing cone 6 is provided on the lower side of the diffuser plate 4 corresponding to the position of the water inlet 102. The horizontal cross section of the flow-dividing cone 6 is a regular octagon. The tip of the flow-dividing cone 6 faces the water inlet direction of the water inlet 102. The outer surface of the flow-dividing cone 6 is covered with a hydrophobic and anti-scaling coating. The coating is a polytetrafluoroethylene coating with a thickness of 0.The bottom surface of the flow-dividing cone 6 is provided with multiple evenly distributed throttling holes 7. A water inlet 401 is provided on the side of the diffuser plate 4 opposite to the water inlet 102, and the positions of the water inlet 401 and the water inlet 102 correspond. Multiple spray holes 402 are provided on the side of the diffuser plate 4 opposite to the spiral turbulence sleeve 3. The spray holes 402 are connected to the water inlet 401. The water inlet 401 guides the water flow to the throttling holes 7 through the independent flow-guiding surface of the flow-dividing cone 6. The throttling holes 7 are connected to the spray holes 402. The central axis of the spiral turbulence sleeve 3 is perpendicular to the central axis of the spray holes 402. The multiple spray holes 402 have rectangular cross-sections. The cross-sectional width of the spray hole 402 increases progressively with the increase in the distance between the spray hole 402 opening and the water inlet. The width increases by 0.5 mm for every 10 mm increase along the flow direction. A baffle plate 403 is installed at the center of the spray hole 402. The baffle plate 403 is perpendicular to the direction of the water inlet 401, and its upper surface is in contact with the fixing plate 2. An arc-shaped guide surface 404 is provided on the inner wall of the spray hole 402 outlet. A guide nozzle 8 is provided on the outer side of the spray hole 402 outlet. A guide cone surface 801 is provided on the side of the guide nozzle 8 opposite to the baffle plate 403. The outlet of the guide nozzle 8 is aligned with the starting end of the spiral rib 301 of the spiral turbulence sleeve 3.

[0026] Working principle: (Reference) Figures 1 to 13When the steam generator is running, the high-temperature heat medium enters the U-shaped heat exchange tube 104 through the heat medium inlet 106 of the pipe box 103 and flows continuously. Finally, it is discharged from the heat medium outlet 107, completing a stable heat exchange loop circulation. External cooling water enters the equipment simultaneously through multiple water inlets 102 on the lower side of the shell 1. It first reaches the polygonal flow-dividing cone 6 on the lower side of the diffuser plate 4. The tip of the flow-dividing cone 6 faces the water inlet direction, buffering, decelerating and regulating the high-speed water flow. Its surface is covered with 0.A 3mm hydrophobic and anti-scaling coating effectively inhibits the adhesion and blockage of scale and impurities in the throttling orifice 7 and the flow guide surface, ensuring long-term unobstructed water flow. Water flows through the evenly distributed throttling orifice 7 and independent flow guide surface on the bottom of the cone, where it is precisely and evenly distributed and pressure stabilized. This eliminates fluctuations in inlet flow and pressure before smoothly entering the inlet hole 401 of the diffuser plate 4. Due to the high water velocity at the inlet hole 401, the diffuser plate 4 employs a rectangular cross-section with progressively wider spray holes 402. The spray holes 402 closest to the inlet hole 401 have a smaller cross-sectional width, allowing only a portion of the high-speed water flow to pass through and be vertically projected onto the spiral turbulence sleeve 3. The majority of the remaining water flow continues to flow away from the inlet hole. The water flows in the direction of the inlet 401. As the water is transported forward, the pressure loss along the flow path causes the flow velocity to gradually decrease. Meanwhile, the cross-sectional width of the nozzles 402, which are farther away from the inlet 401, gradually increases. Through adaptive compensation of the orifice diameter, the difference in outflow caused by the decrease in flow velocity is offset, ensuring that the nozzles 402 at different positions can output water with completely consistent flow rate and velocity. This solves the problem of uneven flow distribution caused by pressure loss along the flow path. In addition, the baffles 403 arranged vertically in the center of the nozzles 402 divide the flow field and prevent flow deviation and eddy currents. The arc-shaped guide surface 404 on the inner wall of the outlet reduces flow resistance and avoids cavitation. The water then converges again through the guide cone surface 801 of the guide nozzle 8 on the outer side of the outlet. The water flow is rectified and ultimately precisely and vertically sprayed onto the starting end of the spiral rib 301 of the spiral turbulence sleeve 3. Under the forced disturbance of the spiral turbulence sleeve 3 and the spiral rib 301, the water flow forms a high-intensity spiral turbulence, which completely destroys the laminar boundary layer on the wall of the heat exchange tube 104, significantly reducing the interfacial heat transfer thermal resistance. The spiral heat-conducting plate 5 extending from the spiral rib 301 is attached to the outside of the heat exchange tube 104. Combined with the discontinuous flow guiding structure formed by the equidistant fracture groove 501, it not only greatly expands the effective heat transfer area and eliminates the thermal resistance of the heat conduction gap, but also releases the thermal stress under alternating temperature and prevents structural deformation. At the same time, it reduces the adhesion of scale and impurities. The balance pressure relief groove 20 is opened on the fixing hole 201 of the fixing plate 2. 2. Connecting adjacent fixed holes 201 enables pressure exchange in the flow channels, balancing pressure in different areas, eliminating local pressure buildup and flow resistance, and protecting core components such as the fixed plate 2, heat exchange tube 104, and spiral turbulence sleeve 3 from impact damage. Under the efficient turbulence and enhanced heat exchange, the cooling water quickly absorbs the heat transferred by the U-shaped heat exchange tube 104 and rapidly vaporizes. The generated dry steam rises steadily along the inner cavity of the shell 1 and is finally stably discharged from the steam port 101 on the upper side of the shell 1. This process achieves low thermal resistance, high throughput, uniform and efficient nuclear steam generation, effectively eliminating local low-flow-rate heat exchange dead zones and ensuring long-term stable, safe, and reliable operation of the equipment under harsh nuclear energy conditions.

[0027] The specific embodiment of the present invention has been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the embodiments described above. For those skilled in the art, various changes, modifications, substitutions, and variations made to these embodiments without departing from the principles and ideas of the present invention should still fall within the protection scope of the present invention.

Claims

1. A low thermal resistance cylindrical steam generator for nuclear energy, comprising a shell (1), a steam port (101) provided on the upper side of the shell (1), a plurality of water inlets (102) provided on the lower side of the shell (1), a tube box (103) provided on the right side of the shell (1), and a plurality of heat exchange tubes (104) provided inside the shell (1), wherein the heat exchange tubes (104) are U-shaped and one end of the heat exchange tubes (104) is fixedly connected to the tube box (103), characterized in that, Multiple fixing plates (2) are provided on multiple heat exchange tubes (104). The multiple fixing plates (2) are arranged vertically. The fixing plates (2) are provided with fixing holes (201) at corresponding positions to the heat exchange tubes (104). The multiple fixing plates (2) are connected to the heat exchange tubes (104) through the fixing holes (201). A spiral turbulence sleeve (3) is coaxially provided between the fixing hole (201) and the heat exchange tube (104). The spiral turbulence sleeve (3) extends to the left and right ends of the fixing hole (201). The spiral turbulence sleeve (3) is provided with spiral ribs (301) on the side. The outer side of the spiral ribs (301) is connected to the heat exchange tubes (104). The fixing hole (201) fits in place. A diffuser plate (4) is provided at the water inlet (102), and one end of the diffuser plate (4) is fixedly installed with the pipe box (103). A water inlet hole (401) is provided on the side of the diffuser plate (4) opposite to the water inlet (102), and the position of the water inlet hole (401) corresponds to that of the water inlet (102). A plurality of water spray holes (402) are provided on the side of the diffuser plate (4) opposite to the spiral turbulence sleeve (3). The water spray holes (402) are connected to the water inlet hole (401). The central axis of the spiral turbulence sleeve (3) is perpendicular to the central axis of the water spray holes (402).

2. A low thermal resistance cylindrical steam generator for nuclear energy according to claim 1, characterized in that, The multiple water spray holes (402) have rectangular cross sections. The cross-sectional width of the water spray holes (402) gradually increases as the distance between the water spray hole (402) opening and the water inlet increases. A baffle plate (403) is provided at the center of the water spray hole (402). The direction of the baffle plate (403) is perpendicular to that of the water inlet (401), and the upper end face of the baffle plate (403) is attached to the fixing plate (2). The inner wall of the outlet of the water spray hole (402) is provided with an arc-shaped guide surface (404).

3. A low thermal resistance cylindrical steam generator for nuclear energy according to claim 1, characterized in that, A heat-conducting plate (5) is provided on the outside of the heat exchange tube (104). The heat-conducting plate (5) is spiral in shape. The heat-conducting plate (5) is attached to the spiral turbulence sleeve (3), and the heat-conducting plate (5) extends along the direction of the spiral rib (301).

4. A low thermal resistance cylindrical steam generator for nuclear energy according to claim 2, characterized in that, A diversion cone (6) is provided on the lower side of the diffuser plate (4) at the position corresponding to the water inlet (102), and the horizontal cross section of the diversion cone (6) is polygonal. The tip of the diversion cone (6) faces the water inlet (102). Multiple evenly distributed throttling holes (7) are opened on the bottom surface of the diversion cone (6). The water inlet (401) guides the water flow to the throttling holes (7) through the independent flow guiding surface of the diversion cone (6). The throttling holes (7) are connected to the spray holes (402).

5. A low thermal resistance cylindrical steam generator for nuclear energy according to claim 3, characterized in that, The heat-conducting sheet (5) is provided with equidistant fracture grooves (501), which make the heat-conducting sheet (5) form an intermittent flow guiding structure.

6. A low thermal resistance cylindrical steam generator for nuclear energy according to claim 1, characterized in that, The fixing hole (201) has multiple pressure relief grooves (202) that connect adjacent fixing holes (201) along its plate surface direction.

7. A low thermal resistance cylindrical steam generator for nuclear energy according to claim 2, characterized in that, The water spray hole (402) has a guide nozzle (8) on the outside of its outlet. The guide nozzle (8) has a guide cone surface (801) on the side opposite to the baffle plate (403). The outlet of the guide nozzle (8) is aligned with the starting end of the spiral rib (301) of the spiral turbulence sleeve (3).

8. A low thermal resistance cylindrical steam generator for nuclear energy according to claim 4, characterized in that, The outer surface of the flow divider cone (6) is covered with a hydrophobic anti-scaling coating, which is a polytetrafluoroethylene coating with a thickness of 0.1 mm to 0.3 mm.

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