Steam generator with axial-flow preheater

Abstract

The invention belongs to the technical field of nuclear reactor systems, and particularly relates to a steam generator with an axial-flow preheater. A middle end socket assembly and a lower end socket assembly are connected with the lower end of a lower cylinder body, a tube plate is fixedly installed at the bottom in the lower cylinder body, the inner diameter of the lower cylinder body is smaller than that of an upper cylinder body, a conical cylinder body is arranged between the lower cylinder body and the upper cylinder body, an upper end socket is installed at the upper end of the upper cylinder body, and a heat transfer tube bundle is installed on the tube plate. The heat transfer tube bundle penetrates through the tube plate and then is communicated with the lower sealing head assembly to form a loop, a water inlet and a water outlet are formed in the bottom of the lower sealing head assembly, a steam-water separation device is installed on the top in the upper sealing head, and the axial flow type preheater is arranged in the steam generator. And flow control is carried out through a semi-annular pore plate at the inlet of the cold side descending channel. According to the invention, the specified proportion distribution of the feed water and the recirculating water of the steam generator on the cold side and the hot side of the secondary side can be realized, and the running state is stable.

Description

Technical Field

[0001] The invention belongs to the technical field of nuclear reactor systems, and in particular relates to a steam generator with an axial flow preheater. Background Art

[0002] The new high-efficiency steam generator adopts an axial flow preheater to enhance heat transfer design. This design puts forward new and more requirements for the flow distribution of the water supply on the cold and hot sides of the secondary side of the steam generator. It is necessary to ensure the reliability of the water supply distribution structure at a higher flow rate, and to ensure that the fluid resistance characteristic setting of the distribution structure can achieve the distribution ratio of the medium in different flow channels under different working conditions. The axial flow preheater in the traditional natural circulation steam generator can no longer meet this requirement. Therefore, the present invention provides a steam generator with an axial flow preheater to meet the requirements of the new high-efficiency steam generator for secondary side fluid distribution. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a steam generator with an axial flow preheater. Without increasing the appearance of the steam generator equipment, a set of internal combined structures corresponding to the axial flow preheater is used to achieve a specified proportion of feed water and recirculating water of the steam generator on the cold and hot sides of the secondary side, thereby improving the heat exchange efficiency of the steam generator by about 20%, having a simple operation mode, strong automatic adaptability to various working conditions, and a stable operating state.

[0004] The technical solution adopted by the present invention is:

[0005] A steam generator with an axial flow preheater comprises a lower head assembly, a tube sheet, a lower cylinder, a heat transfer tube bundle, a conical cylinder, an upper cylinder, an upper head, a steam-water separation device, and an axial flow preheater. The lower head assembly is connected to the lower end of the lower cylinder, a tube sheet is fixedly installed at the bottom of the lower cylinder, the inner diameter of the lower cylinder is smaller than that of the upper cylinder, a conical cylinder is arranged between the lower cylinder and the upper cylinder, an upper head is installed at the upper end of the upper cylinder, a heat transfer tube bundle is installed on the tube sheet, the heat transfer tube bundle is connected with the lower head assembly after passing through the tube sheet to form a loop, a water inlet and a water outlet are arranged at the bottom of the lower head assembly, a steam-water separation device is installed at the top of the upper head, the axial flow preheater is arranged inside the steam generator, all the feed water is transported to the cold side descending channel through a semi-annular main feed water device, and the flow rate is controlled through a semi-annular orifice plate at the entrance of the cold side descending channel to realize automatic matching of the feed water and recirculation water ratio of each power platform.

[0006] The axial flow preheater comprises a secondary side partition plate, which is a rectangular plate structure and is located in the tube gallery area of ​​the heat transfer tube bundle. The secondary side partition plate forcibly divides the secondary side tube bundle area into a cold side and a hot side.

[0007] The axial flow preheater includes a double-layer sleeve descending channel, the outer side of the heat transfer tube bundle is sleeved with the double-layer sleeve descending channel, the double-layer sleeve descending channel includes an inner circle of a complete cylindrical sleeve, and an outer circle of a semi-cylindrical sleeve, and the double-side boundaries of the secondary side partition plate are in contact with the inner wall of the complete cylindrical sleeve; one end of the secondary side partition plate is fixedly mounted on the tube sheet, and the other end extends upward to two-thirds of the height of the heat transfer tube bundle.

[0008] The complete cylindrical sleeve extends upward to the interior of the upper cylinder, and its upper structure cooperates with the conical cylinder. The top of the complete cylindrical sleeve is connected with the center of the steam-water separation device, and downward water outlet channels are provided on both sides of the steam-water separation device. The water outlet channels are connected with the double-layer sleeve descending channel and the cavity formed by the lower cylinder; a water inlet is provided at the bottom of the complete cylindrical sleeve, and a main water distribution device is provided on the upper part of the semi-ring cylindrical sleeve.

[0009] The main body of the main water supply distribution device is a semi-annular structure, which is located at the upper part of the entrance of the cold side descending channel. The main water supply distribution device is located in the conical cylinder section, and includes a main water supply connection nozzle, a water supply mother pipe, a water supply distribution mother pipe, and a J-type final water supply distribution pipe. One end of the main water supply connection nozzle is connected to the external water supply, and the other end is connected to the water supply mother pipe. Water supply distribution mother pipes are respectively provided on both sides of the water supply mother pipe, which together constitute a semi-annular structure. One end of a plurality of J-type final water supply distribution pipes is connected to the water supply distribution mother pipe, and the other end is connected to the cavity formed by the complete cylindrical sleeve and the semi-annular cylindrical sleeve. A semi-annular plate orifice plate is provided on the top of the semi-annular cylindrical sleeve of the final water supply of the main water supply distribution device, and the opening thereof is circular, and the circular opening is larger than the diameter of the J-type final water supply distribution pipe; each J-type final water supply distribution pipe is inserted into the opening of an annular plate.

[0010] The gap between the J-shaped final-stage water supply distribution pipe and the circular hole is in the range of 20% to 30% of the diameter of the J-shaped final-stage water supply distribution pipe.

[0011] The axial flow preheater includes an auxiliary / starting water supply device, which is installed between the steam-water separation device and the complete cylindrical sleeve. The auxiliary / starting water supply device is used to cooperate with the main water supply device to jointly complete the water supply function under various operating conditions of the steam generator.

[0012] At low power levels and when the secondary side of the equipment is filled with water, feeding low-temperature and low-flow feed water into the secondary side of the steam generator through the auxiliary / start-up feed water device can effectively reduce the risks of water hammer and thermal stratification in the main feed water pipe and improve the safety and stability of the equipment.

[0013] The ratio of the difference between the inner radius of the double complete cylindrical sleeve and the semi-ring cylindrical sleeve to the difference between the inner radius of the semi-ring cylindrical sleeve and the lower cylinder body is between 55% and 75%.

[0014] The main body of the main water supply distribution device is a semi-annular structure made of a nickel-based alloy material; the double-layer sleeve is made of carbon steel material; and the secondary side partition plate is made of a nickel-based alloy material.

[0015] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0016] (1) The steam generator with an axial flow preheater provided by the present invention can enhance the heat transfer effect of the steam generator, significantly improve the heat transfer efficiency of the steam generator without increasing the heat transfer area, and increase the steam pressure. Alternatively, when the steam pressure remains unchanged, the heat transfer area can be saved by about 20%, thereby reducing the weight of the equipment.

[0017] (2) The steam generator with an axial flow preheater provided by the present invention can significantly improve the equipment efficiency without adding any additional equipment shape, and has the characteristics of simple structure, safety and stability, and significantly improved equipment compactness and economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 A schematic structural diagram of a steam generator with an axial flow preheater provided by the present invention;

[0020] Figure 2 for Figure 1 Middle AA section top view;

[0021] Figure 3 for Figure 1 Top view of the middle BB section;

[0022] In the figure: 1-lower head assembly, 2-tube sheet, 3-lower cylinder, 4-heat transfer tube bundle, 5-conical cylinder, 6-upper cylinder, 7-upper head, 8-steam-water separation device, 9-main water supply distribution device, 10-double-layer sleeve descending channel, 11-secondary side partition plate, 12-auxiliary / start-up water supply device. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0025] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0026] like Figure 1-3 As shown, a steam generator with an axial flow preheater provided by the present invention comprises a lower head assembly 1, a tube sheet 2, a lower cylinder 3, a heat transfer tube bundle 4, a conical cylinder 5, an upper cylinder 6, an upper head 7, a steam-water separation device 8, and an axial flow preheater. The axial flow preheater comprises a main water supply distribution device 9, a double-layer sleeve descending channel 10, a secondary side partition plate 11, and an auxiliary / start-up water supply device 12. The lower head assembly 1 is connected to the lower end of the lower cylinder 3, and the bottom of the lower cylinder 3 is fixedly installed with a tube sheet 2. The inner diameter of the lower cylinder 3 is smaller than that of the upper cylinder 6. A conical cylinder 5 is provided between the lower cylinder 3 and the upper cylinder 6. An upper head 7 is installed on the upper end of the upper cylinder 6. A heat transfer tube bundle 4 is installed on the tube sheet 2. The heat transfer tube bundle 4 passes through the tube sheet 2 and is connected with the lower head assembly 1 to form a loop. A water inlet and a water outlet are provided at the bottom of the lower head assembly 1.

[0027] The secondary side partition plate 11 is a rectangular plate structure, located in the pipe gallery area of ​​the heat transfer tube bundle 4, and the secondary side partition plate 11 forcibly divides the secondary side tube bundle area into a cold side and a hot side; the outer side of the heat transfer tube bundle 4 is sheathed with a double-layer sleeve descending channel 10, and the double-layer sleeve descending channel 10 includes an inner circle of a complete cylindrical sleeve and an outer circle of a semi-cylindrical sleeve, and the double-side boundaries of the secondary side partition plate 11 are in contact with the inner wall of the complete cylindrical sleeve;

[0028] The complete cylindrical sleeve extends upward to the interior of the upper cylinder 6, and its upper structure cooperates with the conical cylinder 5. A steam-water separation device 8 is installed on the top of the upper head 7. The top of the complete cylindrical sleeve is connected to the center of the steam-water separation device 8, and there are preferably two connecting channels. Downward water outlet channels are provided on both sides of the steam-water separation device 8, and the water outlet channels are connected to the cavity formed by the double-layer sleeve descending channel 10 and the lower cylinder 3; a water inlet is opened at the bottom of the complete cylindrical sleeve, and a main water supply distribution device 9 is provided on the upper part of the semi-ring cylindrical sleeve. The main water supply distribution device 9 is a semi-ring structure and is located at the upper part of the entrance of the cold side descending channel.

[0029] The main water supply distribution device 9 is located in the cone body 5 section, including the main water supply nozzle, the water supply main pipe, the water supply distribution main pipe, and the J-shaped final water supply distribution pipe. Figure 2 As shown, one end of the main water supply nozzle is connected to the external water supply, and the other end is connected to the water supply mother pipe. Water supply distribution mother pipes are respectively arranged on both sides of the water supply mother pipe, together forming a semi-annular structure. One end of a plurality of J-type final-stage water supply distribution pipes is connected to the water supply distribution mother pipe, and the other end is connected to the cavity formed by the complete cylindrical sleeve and the semi-annular cylindrical sleeve. A semi-annular plate orifice plate is arranged on the top of the semi-annular cylindrical sleeve of the final-stage water supply of the main water supply distribution device 9, and the opening thereof is circular, and the circular opening is larger than the diameter of the J-type final-stage water supply distribution pipe; each J-type final-stage water supply distribution pipe is inserted into the opening of a ring plate, and the gap between the J-type final-stage water supply distribution pipe and the circular hole is in the range of 20% to 30% of the diameter of the J-type final-stage water supply distribution pipe, and the distribution adopts the J-type final-stage water supply distribution pipe outlet structure evenly arranged on the upper part of the semi-annular pipe;

[0030] One end of the secondary side partition plate 11 is fixedly mounted on the tube sheet 2 , and the other end extends upward to two-thirds of the height of the heat transfer tube bundle 4 .

[0031] The auxiliary / start-up water supply device 12 is installed between the steam-water separation device 8 and the complete cylindrical sleeve. The auxiliary / start-up water supply device 12 is used to cooperate with the main water supply device 9 to jointly complete the water supply function of the steam generator under various working conditions. Generally, the auxiliary / start-up water supply is only used at low power levels and when the secondary side of the equipment is filled with water. The water supply with a lower temperature and a small flow rate is fed into the secondary side of the steam generator through the auxiliary / start-up water supply device 12, which can effectively reduce the water hammer and thermal stratification risks of the main water supply pipe and improve the safety and stability of the equipment.

[0032] The ratio of the difference between the inner radius of the double complete cylindrical sleeve and the semi-annular cylindrical sleeve to the difference between the inner radius of the semi-annular cylindrical sleeve and the lower cylinder 3 is between 55% and 75%.

[0033] The main body of the main water supply distribution device 9 is a semi-annular structure made of nickel-based alloy material.

[0034] The double-layer sleeve 10 is made of carbon steel.

[0035] The secondary side partition plate 11 is made of nickel-based alloy material.

[0036] The main feed water connection nozzle is arranged at the position of the conical cylinder of the steam generator, and the central axis of the connection nozzle is perpendicular to the wall surface of the conical cylinder.

[0037] The present invention adds an axial flow preheater design to achieve enhanced heat transfer of the steam generator. The structural design of the axial flow preheater adopts ① a secondary side partition plate to forcibly divide the secondary side tube bundle area into a cold side and a hot side, ② a double-layer sleeve design to form an independent main feed water descending channel, and ③ a semi-annular main feed water distribution device and an outer sleeve inlet interception structure are set to adjust the distribution ratio of the secondary side feed water and the recirculating water on the cold and hot sides. The combined structure of these three aspects together constitutes the axial flow preheater.

[0038] The working principle of the present invention is:

[0039] The steam generator of the present invention can realize the functions of water distribution on the secondary side of the steam generator and automatic distribution of circulating water when the steam generator is running at each power platform. During operation, all the water supply on the secondary side is introduced into the opening of the top sealing plate of the semi-annular channel of the double-layer sleeve 10 descending channel through the J-shaped final-stage water supply distribution pipe of the main water supply, so that all the water supply enters the semi-annular descending channel (that is, the cold side descending channel). At the same time, a certain flow of water is dried and separated from the steam-water separation device 8 at the top of the steam generator as recirculating water, and merges with the main water supply flow through the gap between the J-shaped final-stage water supply distribution pipe and the opening of the top sealing plate of the semi-annular channel, and enters the semi-annular descending channel together. This merged flow reaches the secondary side surface of the tube sheet along the cold side descending channel, and then turns back. Due to the presence of the secondary side partition plate, it can only enter the cold side area of ​​the heat transfer tube bundle 4 for heat exchange, and is converted into saturated wet steam after heat exchange and rises into the steam-water separation device 8 for steam-water separation. The dry steam separated and dried by the steam-water separation device flows out from the outlet of the upper head 7, and the separated recirculating water returns to the inlet of the descending channel (the gap area between the cone body 5 and the tube bundle sleeve 4) again. A small part of the recirculating water enters the gap between the J-type final-stage feed water distribution pipe and the opening of the top cover plate of the semi-annular channel, and merges with the main feed water flow. Most of the recirculating water enters the annular cavity gap between the sleeve 10 and the lower cylinder 3, flows downward to the surface of the tube sheet 2, and then returns to the hot side tube bundle area for heat exchange. Through the above process, the axial flow preheater distributes the flow of the main feed water and the recirculating water on both sides of the cold and hot sides of the secondary side tube bundle of the steam generator to realize the enhanced heat transfer process of the steam generator and achieve the purpose of efficient heat exchange.

[0040] The axial flow preheater is a combined internal component of the steam generator with enhanced heat transfer function. It does not require any additional equipment size increase based on the traditional natural circulation steam generator structure. All feed water is transported to the cold side descending channel through a semi-annular main feed water device, and the flow is controlled through a semi-annular orifice plate at the entrance of the cold side descending channel to achieve automatic matching of the feed water and recirculating water ratios for each power platform.

[0041] 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 the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0042] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A steam generator with an axial flow preheater, characterized in that: The heat exchanger comprises a lower head assembly (1), a tube sheet (2), a lower cylinder (3), a heat transfer tube bundle (4), a conical cylinder (5), an upper cylinder (6), an upper head (7), a steam-water separation device (8), and an axial flow preheater. The lower head assembly (1) is connected to the lower end of the lower cylinder (3). The tube sheet (2) is fixedly installed at the bottom of the lower cylinder (3). The inner diameter of the lower cylinder (3) is smaller than that of the upper cylinder (6). The conical cylinder (5) is provided between the lower cylinder (3) and the upper cylinder (6). The upper end of the upper cylinder (6) is provided with an upper head (7). ), a heat transfer tube bundle (4) is installed on the tube sheet (2), and the heat transfer tube bundle (4) passes through the tube sheet (2) and is connected to the lower head assembly (1) to form a loop, and a water inlet and a water outlet are provided at the bottom of the lower head assembly (1), and a steam-water separation device (8) is installed at the top of the upper head (7), and the axial flow preheater is arranged inside the steam generator, and all the feed water is transported to the cold side descending channel through the semi-annular main feed water device, and the flow rate is controlled through the semi-annular orifice plate at the entrance of the cold side descending channel, so as to realize automatic matching of the feed water and recirculation water ratio of each power platform.

2. The steam generator with an axial flow preheater according to claim 1, characterized in that: The axial flow preheater comprises a secondary side partition plate (11), which is a rectangular plate-shaped structure and is located in the tube gallery area of ​​the heat transfer tube bundle (4). The secondary side partition plate (11) forcibly divides the secondary side tube bundle area into a cold side and a hot side.

3. The steam generator with an axial flow preheater according to claim 2, characterized in that: The axial flow preheater comprises a double-layer sleeve descending channel (10), the outer side of the heat transfer tube bundle (4) is sleeved with the double-layer sleeve descending channel (10), the double-layer sleeve descending channel (10) comprises an inner circle of a complete cylindrical sleeve and an outer circle of a semi-cylindrical sleeve, and the double-side boundaries of the secondary side partition plate (11) are in contact with the inner wall of the complete cylindrical sleeve; one end of the secondary side partition plate (11) is fixedly mounted on the tube sheet (2), and the other end extends upward to two-thirds of the height of the heat transfer tube bundle (4).

4. The steam generator with an axial flow preheater according to claim 3, characterized in that: The complete cylindrical sleeve extends upward to the interior of the upper cylinder (6), and its upper structure cooperates with the conical cylinder (5). The top of the complete cylindrical sleeve is connected to the center of the steam-water separation device (8). The steam-water separation device (8) is provided with downward water outlet channels on both sides. The water outlet channels are connected to the double-layer sleeve descending channel (10) and the cavity formed by the lower cylinder (3); a water inlet is opened at the bottom of the complete cylindrical sleeve, and a main water distribution device (9) is provided on the upper part of the semi-circular cylindrical sleeve.

5. The steam generator with an axial flow preheater according to claim 4, characterized in that: The main body of the main water supply distribution device (9) is a semi-annular structure, which is located at the upper part of the entrance of the cold side descending channel. The main water supply distribution device (9) is located in the cone body (5) section, and includes a main water supply nozzle, a water supply mother pipe, a water supply distribution mother pipe, and a J-type final water supply distribution pipe. One end of the main water supply nozzle is connected to the external water supply, and the other end is connected to the water supply mother pipe. Water supply distribution mother pipes are respectively arranged on both sides of the water supply mother pipe, together forming a semi-annular structure. One end of a plurality of J-type final water supply distribution pipes is connected to the water supply distribution mother pipe, and the other end is connected to the cavity formed by the complete cylindrical sleeve and the semi-annular cylindrical sleeve. A semi-annular plate orifice plate is arranged on the top of the semi-annular cylindrical sleeve of the final water supply of the main water supply distribution device (9), and its opening is circular, and the circular opening is larger than the diameter of the J-type final water supply distribution pipe; each J-type final water supply distribution pipe is inserted into the opening of a ring plate.

6. The steam generator with an axial flow preheater according to claim 5, characterized in that: The gap between the J-shaped final-stage water supply distribution pipe and the circular hole is in the range of 20% to 30% of the diameter of the J-shaped final-stage water supply distribution pipe.

7. The steam generator with an axial flow preheater according to claim 5, characterized in that: The axial flow preheater comprises an auxiliary / starting water supply device (12), wherein the auxiliary / starting water supply device (12) is installed between the steam-water separation device (8) and the complete cylindrical sleeve, and the auxiliary / starting water supply device (12) is used to cooperate with the main water supply device (9) to jointly complete the water supply function under various operating conditions of the steam generator.

8. The steam generator with an axial flow preheater according to claim 7, characterized in that: When the power level is low and the secondary side of the equipment is filled with water, the feed water with a relatively low temperature and a small flow rate is fed into the secondary side of the steam generator through the auxiliary / start-up feed water device (12), which can effectively reduce the water hammer and thermal stratification risks of the main feed water pipe and improve the safety and stability of the equipment.

9. The steam generator with an axial flow preheater according to claim 3, characterized in that: The ratio of the difference between the inner radius of the double complete cylindrical sleeve and the semi-annular cylindrical sleeve to the difference between the inner radius of the semi-annular cylindrical sleeve and the lower cylinder (3) is between 55% and 75%.

10. The steam generator with an axial flow preheater according to claim 5, characterized in that: The main body of the main water supply distribution device (9) is a semi-annular structure made of a nickel-based alloy material; the double-layer sleeve (10) is made of carbon steel material; and the secondary side partition plate (11) is made of a nickel-based alloy material.

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