阅读说明：本技术 反应堆蒸汽发生器c型管束 (C-shaped tube bundle of reactor steam generator ) 是由 郝建立 李明芮 马俊杰 陈文振 于 2020-12-16 设计创作，主要内容包括：本发明公开了一种反应堆蒸汽发生器C型管束,保持原有蒸汽发生器并联U型管束总的传热面积和管束的高度基本不变,包括顶部联箱、底部联箱、左C型管、右C型管以及一回路热流体接管；所述左C型管和右C型管的结构相同,均为C型管状结构,二者左右对称布置；所述顶部联箱和底部联箱分别位于蒸汽发生器的顶部和底部,二者的左右两侧分别通过左C型管和右C型管连接；所述一回路热流体接管从外部接入顶部联箱。本发明从根本上解决了蒸汽发生器倒流的问题,有效降低了系统一回路流动阻力,总压降随流量的变化曲线不存在负的斜率区,流量分配较U型管更加均匀,对反应堆自然循环能力有较大提高。(The invention discloses a C-shaped tube bundle of a reactor steam generator, which keeps the total heat transfer area and the height of the tube bundle of an original parallel U-shaped tube bundle of the steam generator unchanged basically and comprises a top header, a bottom header, a left C-shaped tube, a right C-shaped tube and a loop thermal fluid connecting pipe; the left C-shaped pipe and the right C-shaped pipe have the same structure and are both C-shaped tubular structures, and the left C-shaped pipe and the right C-shaped pipe are arranged in a left-right symmetrical mode; the top header and the bottom header are respectively positioned at the top and the bottom of the steam generator, and the left side and the right side of the top header and the bottom header are respectively connected through a left C-shaped pipe and a right C-shaped pipe; and the primary loop hot fluid connecting pipe is connected into the top header from the outside. The invention fundamentally solves the problem of backflow of the steam generator, effectively reduces the flow resistance of a loop of the system, has no negative slope region on the change curve of the total pressure drop along with the flow, has more uniform flow distribution than a U-shaped pipe, and greatly improves the natural circulation capacity of the reactor.)

1. The utility model provides a reactor steam generator C type tube bank, keeps original parallelly connected U type tube bank total heat transfer area of steam generator and the height of tube bank unchangeable basically which characterized in that: comprises a top header (1), a bottom header (2), a left C-shaped pipe (3), a right C-shaped pipe (4) and a primary loop thermal fluid connecting pipe (5); the left C-shaped pipe (3) and the right C-shaped pipe (4) have the same structure and are both C-shaped tubular structures, and the left C-shaped pipe and the right C-shaped pipe are arranged in a bilateral symmetry manner; the top header (1) and the bottom header (2) are respectively positioned at the top and the bottom of the steam generator, and the left side and the right side of the top header and the bottom header are respectively connected through a left C-shaped pipe (3) and a right C-shaped pipe (4); the primary loop hot fluid connecting pipe (5) is connected into the top header (1) from the outside.

2. The reactor steam generator C-tube bundle of claim 1, wherein: when the reactor normally operates, hot fluid flowing out of the reactor core enters the top header (1) from a primary hot fluid connecting pipe (5), then flows through the left C-shaped pipe (3) and the right C-shaped pipe (4) respectively, and after heat transfer is carried out on the hot fluid and secondary side fluid, cold fluid flows downwards into the bottom header (2), flows out of the bottom header (2), flows into the reactor core through a pipeline, absorbs heat generated by the reactor core, and forms circular flow.

3. The reactor steam generator C-tube bundle of claim 1, wherein: the upper and lower sections of the C-shaped tubular structure are bent pipes, and the middle section of the C-shaped tubular structure is a straight pipe section.

4. A reactor steam generator C-tube bundle according to claim 3, wherein: the inner diameter and the outer diameter of the left C-shaped pipe (3) and the right C-shaped pipe (4) are the same as those of the original U-shaped pipe, the height of the straight pipe sections of the left C-shaped pipe and the right C-shaped pipe is the same as that of the straight pipe sections of the original U-shaped pipe, and the radius of the bent pipe is half of that of the bent pipe of the original U-shaped pipe.

5. The reactor steam generator C-tube bundle of claim 1, wherein: the top header (1) and the bottom header (2) both adopt cylindrical structures.

6. The reactor steam generator C-tube bundle of claim 5, wherein: the top header (1) and the bottom header (2) are arranged in a layered mode.

7. The reactor steam generator C-tube bundle of claim 6, wherein: the left C-shaped pipe (3) and the right C-shaped pipe (4) are arranged in parallel, the parallel C-shaped pipes are grouped according to pipe lengths, and each group of C-shaped pipes are respectively connected with the corresponding layers of the top header (1) and the bottom header (2).

8. A reactor steam generator C-tube bundle according to any one of claims 1 to 7, characterized in that: the volumes of the top header (1) and the bottom header (2) are respectively the same as the volumes of the inlet and outlet chambers of the prototype steam generator.

Technical Field

The invention belongs to the technical field of nuclear power, relates to a nuclear power device, and particularly relates to a C-shaped tube bundle of a reactor steam generator.

Background

Nuclear Power plants (Nuclear Power plants) are plants that use Nuclear fuel instead of ordinary fuel to generate thermal energy and convert it into Power by fission reactions of the Nuclear fuel in a Nuclear reactor. It can be used as a main power device of a ship. Nuclear power plants are comprised primarily of nuclear reactors, power generating systems and equipment, such as nuclear steam supply systems and nuclear power plant turbines, and the like, as well as systems and equipment necessary to ensure the proper operation of the equipment, personnel health and safety. The nuclear fuel produces fission reaction in the reactor of the nuclear power plant, releases huge energy, and is absorbed by the continuously circulating cooling water, and the latter transfers heat to the water in the second loop through the steam generator, so that the heat is converted into steam and then the steam is sent to the steam turbine to do work. The nuclear power plant has high power, and can be used for years after being filled with nuclear fuel once. The ships equipped with nuclear power devices have almost unlimited endurance, so that the nuclear power devices are mainly used for large ships and submarines.

The main problems and drawbacks of the prior art include:

nuclear power plants can rely on natural circulation to remove the heat generated by the reactor during normal operation or during accident conditions, which is critical to maintaining reactor safety. However, compared with forced circulation, natural circulation driving force is relatively small, and system parameter coupling is strong, so that the conventional vertical U-shaped tube steam generator for the reactor is easy to generate flow instability phenomenon, particularly backflow phenomenon under the working condition of natural circulation. In the natural circulation working condition, the backflow phenomenon can occur in the U-shaped pipe of the steam generator part, so that the primary loop coolant with lower temperature in the outlet chamber flows back to the inlet chamber. The effective heat transfer area of the steam generator is reduced due to the occurrence of backflow, backflow fluid is mixed and dissipated with incoming flow of a hot section in an inlet chamber in a complex mode, the flow resistance coefficient of the steam generator under the natural circulation condition is high, the forced circulation working condition is increased by multiple times, the natural circulation flow of the system is lower than the design value, the reactor is safe to operate, and in a part of natural circulation tests, the situation that natural circulation cannot be established in a loop system once occurs, and the safety of the reactor is greatly challenged.

For a nuclear power device for a ship, the operating environment is complex and changeable, the working condition changes frequently, and particularly, the operating parameters of fluid in a U-shaped pipe can change in the process of converting forced circulation into natural circulation. The backflow phenomenon not only greatly reduces the natural circulation capacity of a loop system, but also mutually couples and influences the flow and heat transfer of fluid on the secondary side of the steam generator, and brings great challenges to the safety of the reactor. The existing method for solving the backflow of the steam generator mainly comprises the design of an asymmetric U-shaped pipe and the arrangement of a rising non-heat exchange section, and the two technologies can effectively reduce backflow critical flow and critical pressure drop, so that a steam generator parallel U-shaped pipe bundle can avoid the backflow interval to operate, but the backflow problem cannot be fundamentally solved.

Disclosure of Invention

Aiming at the problems and the defects in the prior art, the invention provides the C-shaped tube bundle of the reactor steam generator, which fundamentally solves the problem of backflow of the steam generator, effectively reduces the flow resistance of a loop of the system, has no negative slope region in the change curve of the total pressure drop along with the flow, has more uniform flow distribution compared with a U-shaped tube, and greatly improves the natural circulation capacity of the reactor.

Therefore, the invention adopts the following technical scheme:

a C-shaped tube bundle of a reactor steam generator keeps the total heat transfer area and the height of the tube bundle of an original parallel U-shaped tube bundle of the steam generator basically unchanged, and comprises a top header, a bottom header, a left C-shaped tube, a right C-shaped tube and a loop thermal fluid connecting tube; the left C-shaped pipe and the right C-shaped pipe have the same structure and are both C-shaped tubular structures, and the left C-shaped pipe and the right C-shaped pipe are arranged in a left-right symmetrical mode; the top header and the bottom header are respectively positioned at the top and the bottom of the steam generator, and the left side and the right side of the top header and the bottom header are respectively connected through a left C-shaped pipe and a right C-shaped pipe; and the primary loop hot fluid connecting pipe is connected into the top header from the outside.

Further, when the reactor normally operates, hot fluid flowing out of the reactor core enters the top header from the primary hot fluid connecting pipe, then flows through the left C-shaped pipe and the right C-shaped pipe respectively, and after heat transfer is carried out between the left C-shaped pipe and the right C-shaped pipe and secondary side fluid, cold fluid flows into the bottom header downwards, flows out of the bottom header, flows into the reactor core through a pipeline, absorbs heat generated by the reactor core, and forms circular flow.

Preferably, the upper and lower sections of the C-shaped tubular structure are bent pipes, and the middle section is a straight pipe section.

Preferably, the inner diameter and the outer diameter of the left C-shaped pipe and the right C-shaped pipe are the same as those of the original U-shaped pipe, the height of the straight pipe sections of the left C-shaped pipe and the right C-shaped pipe is the same as that of the straight pipe sections of the original U-shaped pipe, and the radius of the bent pipe is half of that of the bent pipe of the original U-shaped pipe.

Preferably, the top header and the bottom header are both of cylindrical configuration.

Further, the top header and the bottom header are arranged in layers.

Furthermore, the left C-shaped pipe and the right C-shaped pipe are arranged in parallel, the parallel C-shaped pipes are grouped according to pipe lengths, and each group of C-shaped pipes is connected with the corresponding layers of the top header and the bottom header respectively.

Preferably, the top header and the bottom header have the same volume as the inlet and outlet chambers of the prototype steam generator, respectively.

Compared with the prior art, the invention has the beneficial effects that:

(1) in the device arrangement, the water tank is connected with the heat transfer pipe to replace the original pipe plate, so that the requirement on the diameter of the heat transfer pipe can be reduced, and more and thinner heat transfer pipes can be arranged.

(2) After the C-shaped pipe is adopted, the flow resistance of a primary loop of the system can be effectively reduced.

(3) After the C-shaped pipe is adopted, a negative slope area does not exist in the change curve of the total pressure drop along with the flow.

(4) The power of the C-shaped pipe of the steam generator is basically consistent with that of the U-shaped pipe, the circulation condition is forced, and the beam flow distribution of the parallel C-shaped pipe is more uniform than that of the U-shaped pipe.

(5) The problem of steam generator refluence has fundamentally been solved.

(6) The steam generator adopts a C-shaped pipe to greatly improve the natural circulation capacity of the reactor.

Drawings

FIG. 1 is a schematic structural diagram of a C-shaped tube bundle of a reactor steam generator according to the present invention.

FIG. 2 is a schematic view of an original U-shaped tube.

FIG. 3 shows the primary and secondary heat transfer coefficients of the boiling sections of the secondary sides of the C-shaped tube and the U-shaped tube according to the embodiment of the present invention.

FIG. 4 is a temperature distribution diagram of the first and second sides of the C-shaped tube and the U-shaped tube according to the embodiment of the present invention.

FIG. 5 is a graph of the gravitational pressure drop of a primary thermal fluid nozzle as a function of flow rate for an embodiment of the present invention.

FIG. 6 is a graph of the change in gravitational pressure drop of a C-tube with flow rate in an embodiment of the present invention.

FIG. 7 is a graph of resistance to pressure drop across a primary thermal fluid nozzle as a function of flow in an embodiment of the present invention.

FIG. 8 is a graph of resistance-pressure drop of a C-tube as a function of flow rate in an embodiment of the present invention.

FIG. 9 is a graph showing the inlet-outlet pressure drop of U-shaped tubes and C-shaped tubes as a function of inlet flow rate in the embodiment of the present invention.

Description of reference numerals: 1. a top header; 2. a bottom header; 3. a left C-shaped pipe; 4. a right C-shaped pipe; 5. a primary thermal fluid take-over.

Detailed Description

The present invention will be described in detail with reference to the accompanying drawings and specific embodiments, which are provided for illustration only and are not to be construed as limiting the invention.

In order to fundamentally solve the problem of backflow of the steam generator, the invention provides a new heat transfer pipe structure design scheme, namely a C-shaped pipe. Under the condition of keeping the total heat transfer area and the height of the parallel U-shaped tube bundle of the steam generator basically unchanged, the design is shown in figure 1 and comprises the following steps: a top header 1, a bottom header 2, a left C-shaped pipe 3, a right C-shaped/4 and a primary thermal fluid connecting pipe 5. As shown in FIG. 2, the inner diameter and the outer diameter of the original U-shaped pipe are the same as those of the original U-shaped pipe, and the height of the straight pipe section of the original U-shaped pipe is the same as that of the straight pipe section of the original U-shaped pipe and is Hu; the length of the tube is half of the length of the original U-shaped tube, namely 0.5 Lu; the radius of the bent pipe is half of that of the bent pipe of the original U-shaped pipe, namely 0.5 Ru. During normal operation, hot fluid flowing out of the reactor core enters the top header 1 from a primary hot fluid connecting pipe 5, then flows through the left C-shaped pipe 3 and the right C-shaped pipe 4 respectively, and after heat transfer is carried out on the hot fluid and secondary side fluid, cold fluid flows downwards into the bottom header 2, flows out of the header, flows into the reactor core through a pipeline, absorbs heat generated by the reactor core, and forms circular flow. Top header 1 and bottom header 2 adopt cylindrical design, in order to reduce the influence of the fluid action of gravity to flow distribution in the header, all carry out the layer design to top header 1 and bottom header 2, divide into groups parallelly connected C type pipe according to the pipe length, and the layer that every group C type union coupling header corresponds. In order to meet the requirement of the fluid filling amount in the steam generator, the volume of the header is ensured to be the same as that of the inlet and outlet cavities of the prototype steam generator.

Examples

The steam generator is used as a calculation object, the heat exchange area of the single-side C-shaped pipe is half of that of the U-shaped pipe, so that the flow rates of the primary side and the secondary side of the C-shaped pipe are half of that of the U-shaped pipe, the inlet and outlet temperatures of the primary side and the secondary side of the C-shaped pipe are consistent with those of the U-shaped pipe, and the designed operation reference parameters of the C-shaped pipe are shown in.

TABLE 1 steam generator C-tube operating reference parameters

FIG. 3 shows the heat transfer coefficients of the primary and secondary sides of the boiling sections of the secondary sides of the C-shaped tubes and the U-shaped tubes, wherein the horizontal and vertical coordinates are normalized, and since the preheating section is shorter than the boiling section and is not analyzed heavily, the heat transfer coefficients of the two tube types are exponentially reduced as can be seen from FIG. 3; the inlet temperature and the secondary side operation working condition are kept the same, the heat transfer coefficient of the U-shaped pipe is higher than that of the C-shaped pipe, and the Reynolds number is lower than that of the U-shaped pipe mainly because the flow speed in the single-side C-shaped pipe is half of that of the U-shaped pipe. Fig. 4 shows the temperature distribution of the first and second sides of the C-shaped pipe and the U-shaped pipe, and it can be seen from fig. 4 that the temperature of the first and second sides of the C-shaped pipe is exponentially distributed; under the condition of natural circulation, the temperature difference between the inlet and the outlet of the C-shaped pipe is slightly lower than that between the inlet and the outlet of the U-shaped pipe, so that the total heat exchange amount between the C-shaped pipe on the left side and the C-shaped pipe on the right side and the secondary side is basically the same as that of the U-shaped pipe; the temperature drop speed of the primary side of the single-side C-shaped pipe is obviously higher than that of the U-shaped pipeAscending section, which is mainly due to the fact that the flow of the one-sided C-tube is half of the flow of the U-tube, combined with the results calculated according to FIG. 4 andit can be concluded that the C-tube temperature drops more rapidly. By calculating the height of the preheating sections of the two tube types, the following can be obtained: the height of the preheating section corresponding to the U-shaped pipe ascending section, the height of the preheating section corresponding to the U-shaped pipe descending section and the height of the preheating section corresponding to the C-shaped pipe are respectively as follows: x is the number of_u、4.8x_u、3.0x_uThe height of the preheating section of the C-shaped pipe is between the heights of the preheating sections corresponding to the ascending section and the descending section of the U-shaped pipe.

When studying the driving force and the flow resistance of the fluid in the U-shaped pipe, the whole pipe pass from the inlet to the outlet of the U-shaped pipe is usually calculated, and since the inlet and the outlet of the U-shaped pipe are at the same horizontal height, when calculating the pressure drop of the C-shaped pipe, the gravity pressure drop and the resistance pressure drop in the hot fluid pipe of the primary circuit need to be considered, as shown in fig. 5 to 8, it can be derived from the following figures: different from the calculation results of the resistance pressure drop and the gravity pressure drop of the U-shaped pipe, the gravity pressure drop of a primary loop connecting pipe is unchanged along with the reduction of the flow, and the gravity pressure drop and the resistance pressure drop of the C-shaped pipe and the resistance pressure drop of the primary loop connecting pipe are gradually reduced. The research on key factors of backflow occurrence shows that the adoption of the C-shaped pipe can have important influence on the backflow characteristic of the SG.

Fig. 9 shows the pressure drop of the inlet and outlet of the U-shaped pipe and the C-shaped pipe along with the change of the inlet flow, and it can be seen from the figure that the pressure drop of the inlet and outlet of the C-shaped pipe gradually decreases (the absolute value increases) along with the decrease of the inlet flow at the primary side of SG, the lower the flow, the higher the decreasing rate, and the calculation result is consistent with the experimental conclusion of the C-shaped pipe; under the same flow working condition, the pressure drop of the inlet and the outlet of the U-shaped pipe is larger than that of the C-shaped pipe; along with the reduction of the inlet flow, the pressure drop curve of the inlet and the outlet of the U-shaped pipe has an inflection point and a negative slope region, while the pressure drop curve of the inlet and the outlet of the C-shaped pipe has no inflection point, and a conclusion can be obtained according to a backflow theory: the C-shaped pipe structure can avoid the occurrence of backflow.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and scope of the present invention are intended to be covered thereby.