Evaporator with simplified inlet and outlet connection structure for carbon dioxide working medium

Abstract

The application discloses a kind of evaporators of simplified inlet and outlet connection structure of carbon dioxide working substance, and relates to an evaporator.To solve the problems of complex structure of existing high-temperature gas cooled reactor steam generator, corrosion and scale and thermal resistance of water as working substance, the evaporator of simplified inlet and outlet connection structure of carbon dioxide working substance is composed of multiple heat exchange units, upper header, upper small header, lower small header and lower header.The chemical properties of CO2 used in the application are relatively stable, reducing the risk of leakage, high efficiency, more compact structure, and reducing the flow resistance of helium.The application optimizes the inlet and outlet tube bundle structure of working substance, simplifies the inlet and outlet structure of working substance, is mature and reliable, can realize modular construction and installation, reduces the manufacturing difficulty, shortens the installation and construction time, and reduces investment.

Description

TECHNICAL FIELD

[0001] The present application relates to an evaporator. BACKGROUND

[0002] The existing high-temperature gas cooled steam generator uses water vapor as the working medium, and the inlet and outlet connecting pipe structure is complex, mostly using small pipes for connection, with a large number of connections, small pipes, bent pipes and winding pipes, complex connection, high installation precision, difficult manufacturing process, long installation time, low manufacturing yield of the heating unit, high manufacturing cost, and limited space, which cannot realize modularization. Once the water vapor pipe of the steam generator with water vapor as the working medium leaks, helium gas will cause the reactor to be useless, the nuclear power plant to be shut down, and great economic losses and social benefits will be caused. After the leakage, the helium gas pollutes the environment and endangers human life safety. At the same time, water is used as the working medium, the water side has a fast corrosion rate on the boiler heating surface, and is easy to produce scale and thermal resistance. SUMMARY

[0003] In order to solve the problems of complex structure of the existing high-temperature gas cooled steam generator and corrosion, scale and thermal resistance caused by using water as the working medium, the present application provides a carbon dioxide working medium evaporator with a simplified inlet and outlet connecting structure.

[0004] The carbon dioxide working medium evaporator with a simplified inlet and outlet connecting structure comprises a plurality of heat exchange units, an upper header tank, an upper small header tank, a lower small header tank and a lower header tank.

[0005] The heat exchange unit is composed of a plurality of composite pipes with different radii and concentrically stacked together, the composite pipe is composed of an outer sleeve pipe, a spiral pipe and an inner sleeve pipe, and the spiral pipe is arranged between the outer sleeve pipe and the inner sleeve pipe; the working medium in the spiral pipe is CO2; the upper part of the evaporator is provided with a top shell passage, the shell body of the top shell passage extends downward to form a guard plate; a plurality of heat exchange units are arranged in the guard plate in the middle part of the evaporator, the lower part of the evaporator is provided with a bottom shell passage, the shell body of the bottom shell passage extends upward to form a pressure shell, the upper end of the pressure shell is open, and the guard plate is inserted into the pressure shell from the open upper end of the pressure shell; a helium gas inlet is arranged on the left side of the top shell passage; the upper header tank is arranged in the header tank shell body on the right side of the top shell passage; a plurality of upper small header tanks are arranged above the plurality of heat exchange units in the top shell passage; each upper small header tank is in communication with the spiral pipes in the plurality of heat exchange units, and the upper small header tank is in communication with the upper header tank through an upper header tank connecting pipe; the lower header tank is arranged below the outside of the evaporator; a plurality of lower small header tanks are arranged below the plurality of heat exchange units in the bottom shell passage; each lower small header tank is in communication with the spiral pipes in the plurality of heat exchange units, and the lower small header tank is in communication with the lower header tank through a lower header tank connecting pipe; the upper small header tank is a horizontal strip-shaped header tank, and a plurality of upper small header tanks are arranged in parallel with each other and distributed in two plane layers; the lower small header tank is a horizontal strip-shaped header tank, and a plurality of lower small header tanks are arranged in parallel with each other and distributed in two plane layers.

[0006] The principles and benefits of the present application are:

[0007] I. The operation process of the steam generator of the present application is:

[0008] ①, Helium flow: high-temperature helium from the reactor enters the steam generator through the helium inlet, the helium flows from top to bottom, flows to the bottom shell passage from the gap between the inner sleeve and the outer sleeve, and finally discharges from the steam generator through the gap between the pressure shell and the protective plate, and returns to the reactor. During this period, the high-temperature helium will transfer the heat carried by the spiral pipe to the internal CO2 working medium; ②, CO2 gas flow: low-temperature CO2 gas is distributed to multiple lower small headers in the lower header, and the lower small headers are distributed to the connected spiral pipes, and the CO2 in the spiral pipes is collected to different upper small headers after absorbing heat, and then collected to the upper header from the upper small headers, completing the collection. The high-temperature CO2 can be used to drive the generator in the steam turbine high-pressure cylinder to generate electricity.

[0009] II. The chemical properties of CO2 used in the present application are relatively stable, the corrosion rate is slow under medium and low temperature conditions, CO2 working medium does not produce dirt, no phase change occurs, the risk of leakage is reduced, the range of material selection requirements of CO2 for parts is relatively wide, and the difficulty of material selection of key parts is reduced. The present application uses CO2 as the working medium, so that the efficiency of the steam generator is high, the heat transfer area can be reduced, the heating surface area is small, and the structure is more compact; the space occupied by the key parts and the whole system is small, compared with the large amount of boiler pipes required by water vapor, the flow deviation of each heat exchange unit is reduced, the flow resistance of helium is reduced, and the occurrence of thermal stress, thermal fatigue, high-temperature corrosion or metal embrittlement caused by high-temperature and high-pressure gas flow is reduced. The present application optimizes the inlet and outlet pipe bundle structure of the working medium, simplifies the inlet and outlet structure of the working medium, the structure is mature and reliable, can realize modular construction and installation, reduces the process manufacturing difficulty, shortens the installation and construction time, and reduces the investment. BRIEF DESCRIPTION OF DRAWINGS

[0010] Fig. 1 It is a structure schematic view of the evaporator with simplified inlet and outlet connection structure of the carbon dioxide working medium in Example 1;

[0011] Fig. 2 It is a top view of the upper small header 6 in the top shell passage 2;

[0012] Fig. 3 It is a side view of the upper small header 6 in the top shell passage 2;

[0013] Fig. 4 It is a cross-sectional view of one heat exchange unit 7;

[0014] Fig. 5 It is a distribution diagram of the heat exchange unit 7 in the protective plate 8. DETAILED DESCRIPTION

[0015] The technical solution of the present application is not limited to the following specific embodiments, but also includes any reasonable combination of the specific embodiments.

[0016] Specific embodiment one: the evaporator of the simplified inlet and outlet connection structure of the carbon dioxide working medium in this embodiment is composed of a plurality of heat exchange units 7, an upper header tank 4, upper small header tanks 6, lower small header tanks 10, and a lower header tank 13.

[0017] The heat exchange unit 7 is composed of a plurality of composite tubes with different radii and concentrically stacked together, the composite tube is composed of an outer sleeve tube 14, a spiral tube 15, and an inner sleeve tube 16, and the spiral tube 15 is arranged between the outer sleeve tube 14 and the inner sleeve tube 16; the working medium in the spiral tube 15 is CO2; the upper part of the evaporator is provided with a top shell channel 2, the shell of the top shell channel 2 extends downward to form a guard plate 8; a plurality of heat exchange units 7 are arranged in the guard plate 8 in the middle part of the evaporator, the lower part of the evaporator is provided with a bottom shell channel 12, the shell of the bottom shell channel 12 extends upward to form a pressure shell 9, the upper end of the pressure shell 9 is open, and the guard plate 8 is inserted into the pressure shell 9 from the open upper end of the pressure shell 9; the left side of the top shell channel 2 is provided with a helium gas inlet 1; the upper header tank 4 is arranged in the header tank shell 5 on the right side of the top shell channel 2; a plurality of upper small header tanks 6 are arranged above a plurality of heat exchange units 7 in the top shell channel 2; each upper small header tank 6 is in communication with the spiral tube 15 in a plurality of heat exchange units 7, and the upper small header tank 6 is in communication with the upper header tank 4 through an upper header tank connecting pipe 3; the lower header tank 13 is arranged below the outside of the evaporator; a plurality of lower small header tanks 10 are arranged below a plurality of heat exchange units 7 in the bottom shell channel 12; each lower small header tank 10 is in communication with the spiral tube 15 in a plurality of heat exchange units 7, and the lower small header tank 10 is in communication with the lower header tank 13 through a lower header tank connecting pipe 11; the upper small header tank 6 is a horizontally arranged strip-shaped header tank, a plurality of upper small header tanks 6 are arranged in parallel with each other and distributed in two plane layers; the lower small header tank 10 is a horizontally arranged strip-shaped header tank, a plurality of lower small header tanks 10 are arranged in parallel with each other and distributed in two plane layers.

[0018] The chemical property of CO2 is relatively stable, the corrosion rate is slow under low temperature condition, CO2 working medium does not produce dirt, no phase change occurs, the risk of leakage is reduced, the range of material selection requirements of CO2 for components is relatively wide, and the difficulty of material selection of key components is reduced. The steam generator with CO2 as the working medium has high efficiency, can reduce the heat transfer area, has small heating surface area, and has a more compact structure; the space occupied by the key components and the whole system is small, compared with the large amount of boiler pipeline equipment required by water vapor, the flow deviation of each heat exchange unit is reduced, the flow resistance of helium is reduced, and the occurrence of thermal stress, thermal fatigue, high temperature corrosion or metal embrittlement caused by high temperature and high pressure gas flow washing is reduced. The inlet and outlet structure of the working medium is simplified by optimizing the inlet and outlet pipe bundle structure of the working medium, the structure is mature and reliable, can realize modular construction and installation, reduce the process manufacturing difficulty, shorten the installation and construction time, and reduce the investment.

[0019] Specific implementation method two: the difference between this implementation method and specific implementation method one is that the center of the innermost composite pipe in the heat exchange unit 7 is provided with a center pipe 17.

[0020] Specific implementation method three: the difference between this implementation method and specific implementation method one or two is that the material of the outer sleeve pipe 14, the spiral pipe 15 and the inner sleeve pipe 16 is 690H alloy steel pipe or T91 alloy steel pipe.

[0021] Specific implementation method four: the difference between this implementation method and one of specific implementation methods one to three is that the upper small header 6 is 5, 3 upper small headers 6 are arranged in the lower layer plane, and 2 upper small headers 6 are arranged in the upper layer plane.

[0022] Specific implementation method five: the difference between this implementation method and one of specific implementation methods one to four is that the lower small header 10 is 5, 3 lower small headers 10 are arranged in the lower layer plane, and 2 lower small headers 10 are arranged in the upper layer plane.

[0023] Specific implementation method six: the difference between this implementation method and one of specific implementation methods one to five is that the lengths of the spiral pipes 15 in different composite pipes in the heat exchange unit 7 are the same.

[0024] Example 1:

[0025] In combination Figs. 1-5 It is explained that the evaporator with simplified inlet and outlet connection structure of carbon dioxide working medium in this embodiment is composed of a plurality of heat exchange units 7, an upper header 4, an upper small header 6, a lower small header 10 and a lower header 13;

[0026] The heat exchange unit 7 is composed of multiple composite pipes with different radii and concentrically stacked together, the composite pipe is composed of an outer sleeve pipe 14, a spiral pipe 15 and an inner sleeve pipe 16, the spiral pipe 15 is arranged between the outer sleeve pipe 14 and the inner sleeve pipe 16, the length of the spiral pipe 15 in different composite pipes in the heat exchange unit 7 is the same; the center of the innermost composite pipe in the heat exchange unit 7 is provided with a center pipe 17; the materials of the outer sleeve pipe 14, the spiral pipe 15 and the inner sleeve pipe 16 are 690H alloy steel pipes, the working medium in the spiral pipe 15 is CO2; the upper part of the evaporator is provided with a top shell channel 2, the shell of the top shell channel 2 extends downward to form a guard plate 8; multiple heat exchange units 7 are arranged in the guard plate 8 in the middle part of the evaporator, the lower part of the evaporator is provided with a bottom shell channel 12, the shell of the bottom shell channel 12 extends upward to form a pressure shell 9, the upper end of the pressure shell 9 is open, the guard plate 8 is inserted into the pressure shell 9 from the open upper end of the pressure shell 9; the left side of the top shell channel 2 is provided with a helium inlet 1; an upper header tank 4 is arranged in a header tank shell 5 on the right side of the top shell channel 2; five upper small header tanks 6 are arranged above multiple heat exchange units 7 in the top shell channel 2; each upper small header tank 6 is in communication with the spiral pipe 15 in multiple heat exchange units 7, the upper small header tank 6 is in communication with the upper header tank 4 through an upper header tank connecting pipe 3; a lower header tank 13 is arranged below the evaporator; five lower small header tanks 10 are arranged below multiple heat exchange units 7 in the bottom shell channel 12; each lower small header tank 10 is in communication with the spiral pipe 15 in multiple heat exchange units 7, the lower small header tank 10 is in communication with the lower header tank 13 through a lower header tank connecting pipe 11; the upper small header tank 6 is a horizontally arranged strip-shaped header tank, five upper small header tanks 6 are arranged in parallel with each other and distributed in two plane layers, three upper small header tanks 6 are arranged in the lower plane layer and two upper small header tanks 6 are arranged in the upper plane layer; the lower small header tank 10 is a horizontally arranged strip-shaped header tank, five lower small header tanks 10 are arranged in parallel with each other and distributed in two plane layers; three lower small header tanks 10 are arranged in the lower plane layer and two lower small header tanks 10 are arranged in the upper plane layer;

[0027] The chemical property of CO2 used in the embodiment is relatively stable, the corrosion rate is slow under low-temperature conditions, CO2 working medium does not produce dirt, no phase change occurs, the risk of leakage is reduced, the range of material selection requirements of CO2 for parts is relatively wide, and the difficulty of material selection of key parts is reduced. The steam generator using CO2 as the working medium has high efficiency, can reduce the heat transfer area, has small heating surface area, and has a more compact structure; the space occupied by the key parts and the whole system is small, compared with a large amount of boiler pipes and equipment required by water vapor, the flow deviation of each heat exchange unit is reduced, the flow resistance of helium is reduced, and the occurrence of thermal stress, thermal fatigue, high-temperature corrosion or metal embrittlement caused by high-temperature and high-pressure gas flow washing is reduced. The structure of the inlet and outlet pipe bundles of the working medium is optimized, the inlet and outlet structure of the working medium is simplified, the structure is mature and reliable, modular construction and installation can be realized, the process manufacturing difficulty is reduced, the installation and construction time is shortened, and the investment is reduced.

Claims

1. An evaporator with a simplified inlet and outlet connection structure for carbon dioxide working fluid, characterized by: An evaporator with a simplified inlet and outlet connection structure for a carbon dioxide working medium is composed of a plurality of heat exchange units (7), an upper header (4), an upper small header (6), a lower small header (10), and a lower header (13); The heat exchange unit (7) is composed of a plurality of composite tubes with different radii and concentrically stacked together, the composite tube being composed of an outer sleeve (14), a spiral tube (15) and an inner sleeve (16), the spiral tube (15) being arranged between the outer sleeve (14) and the inner sleeve (16); the working medium in the spiral tube (15) is CO2; a top shell channel (2) is arranged on the upper part of the evaporator, and the shell of the top shell channel (2) extends downward to form a guard plate (8); a plurality of heat exchange units (7 ) is arranged in the guard plate (8) in the middle of the evaporator, and the lower part of the evaporator is provided with a bottom shell channel (12), the shell of the bottom shell channel (12) extends upward to form a pressure shell (9), the upper end of the pressure shell (9) is open, and the guard plate (8) is inserted into the pressure shell (9) through the upper end opening of the pressure shell (9); a helium inlet (1) is provided on the left side of the top shell channel (2); the upper header (4) is provided in the header shell (5) on the right side of the top shell channel (2); several upper small headers The box (6) is arranged above the plurality of heat exchange units (7) in the top shell channel (2); each upper small header box (6) is connected to the spiral tubes (15) in the plurality of heat exchange units (7), and the upper small header box (6) is connected to the upper header box (4) through the upper header box connecting pipe (3); the lower header box (13) is arranged below the outside of the evaporator; a plurality of lower small header boxes (10) are arranged below the plurality of heat exchange units (7) in the bottom shell channel (12); each lower small header box (10) is connected to the upper header box (4) through the upper header box connecting pipe (3); the lower header box (13) is arranged below the outside of the evaporator; a plurality of lower small header boxes (10) are arranged below the plurality of heat exchange units (7) in the bottom shell channel (12); each lower small header box (10) is connected to the upper header box (4) through the upper header box connecting pipe (3); the lower header box (13) is arranged below the outside of the evaporator; the plurality of lower small header boxes (10) are arranged below the plurality of heat exchange units (7) in the bottom shell channel (12); each lower small header box (10) is connected to the upper header box (4) through the upper header box connecting pipe (3); the lower header box (13 ... ) are connected to the spiral tubes (15) in the plurality of heat exchange units (7), and the lower small header (10) is connected to the lower header (13) through the lower header connecting pipe (11); the upper small header (6) is a horizontally arranged strip header, and the plurality of upper small headers (6) are arranged parallel to each other and distributed in two plane layers; the lower small header (10) is a horizontally arranged strip header, and the plurality of lower small headers (10) are arranged parallel to each other and distributed in two plane layers.

2. The evaporator with a simplified inlet and outlet connection structure for carbon dioxide according to claim 1, characterized in that: A central tube (17) is provided at the center of the innermost composite tube in the heat exchange unit (7).

3. The evaporator with a simplified inlet and outlet connection structure for carbon dioxide according to claim 1, characterized in that: The outer sleeve (14), the spiral tube (15) and the inner sleeve (16) are made of 690H alloy steel pipe or T91 alloy steel pipe.

4. The evaporator with a simplified inlet and outlet connection structure for carbon dioxide according to claim 1, characterized in that: There are five upper small headers (6), three of which are arranged in the lower plane layer, and two of which are arranged in the upper plane layer.

5. The evaporator with a simplified inlet and outlet connection structure for carbon dioxide working medium according to claim 1, characterized in that: There are five lower small headers (10), three of which are arranged in the lower plane layer, and two of which are arranged in the upper plane layer.

6. The evaporator with a simplified inlet and outlet connection structure for carbon dioxide working medium according to claim 1, characterized in that: The lengths of the spiral tubes (15) in different composite tubes in the heat exchange unit (7) are the same.

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