A preheating installation for desalinated water in a power plant

Abstract

The application discloses a kind of preheating facilities of power plant desalted water, it is related to heat exchanger technical field.The application includes heat exchange box, the middle of heat exchange box is opened with cross cavity, the two sides of cross cavity are opened with upper heat exchange cavity and lower heat exchange cavity distributed in upper and lower, the side of upper heat exchange cavity away from cross cavity is opened with upper heat medium cavity, the side of lower heat exchange cavity away from cross cavity is opened with lower heat medium cavity, cross cavity is provided with flow guide hole between upper heat exchange cavity and lower heat exchange cavity, through-hole is arranged between upper heat exchange cavity and lower heat exchange cavity, and lifting window is arranged between upper heat exchange cavity and upper heat medium cavity, and between lower heat exchange cavity and lower heat medium cavity, the inside of heat exchange box is provided with two groups of Z-shaped heat exchange pipe groups.The application can adjust the angle of inclined pipe, and can change the height difference of inlet and outlet when adjusting, so that the device can be suitable for different working conditions, prevent the problems such as local overheating, supercooling or flow not smooth caused by uneven pressure or flow rate mismatch.

Description

Technical Field

[0001] This invention relates to the field of heat exchanger technology, and more specifically to a preheating facility for demineralized water in power plants. Background Technology

[0002] In thermal power plants, demineralized water (typically 20-40 t / h in flow rate and 4-25°C in temperature) is mainly used to replenish water lost through normal system operation. Because its quantity is relatively small, its impact on condensate temperature after being added to the condenser is minimal. However, in heating units, which continuously supply steam (up to tens to hundreds of tons per hour), the amount of demineralized water required is relatively large, which lowers the condensate temperature and necessitates the burning of more coal, significantly increasing boiler coal consumption. Therefore, heat exchange is necessary. Tubular heat exchangers are a common type of heat exchange equipment widely used in various water treatment systems in power plants. The structure of a tubular heat exchanger typically consists of multiple inner and outer pipes. Fluid flows through the inside of the pipes, and heat is transferred through the pipe walls to the fluid outside, or vice versa.

[0003] A shell-and-tube heat exchanger is disclosed in Chinese patent (publication number: CN104949552B), which mainly consists of a shell, tube boxes located on both sides of the shell, tube sheets located between the tube boxes and the shell, and heat exchange tubes installed inside the shell. A shell-side fluid inlet is provided on the outer wall of the shell near one edge of the shell, and a shell-side fluid outlet is provided on the outer wall of the shell near the other edge of the shell. Coolant enters the shell from the shell-side fluid inlet and flows out through the shell-side fluid outlet from the gap between the heat exchange tubes. A tube-side fluid inlet is provided on one end of the tube box located at the shell-side fluid inlet, and a tube-side fluid outlet is provided on the other tube box. The two ends of the heat exchange tubes are respectively fixed to the tube sheets, and the openings at both ends of the heat exchange tubes are respectively located inside the tube boxes. Multiple sets of arc-shaped plates and circular plates are arranged at intervals from the shell-side fluid inlet to the shell-side fluid outlet inside the shell. A central hole is provided in the center of the arc-shaped plate for coolant flow, and a ring of drain holes is provided along the edge of the circular plate for coolant flow.

[0004] The patent and existing technologies have the following technical problems in practical use:

[0005] 1. Traditional tubular heat exchangers typically employ a straight-flow design, resulting in relatively stable fluid flow that easily leads to laminar flow. Laminar flow has low heat transfer efficiency and struggles to fully utilize the temperature difference between the fluid and the tube wall. While some tubular heat exchangers utilize spiral or U-shaped pipe designs to improve heat exchange efficiency, these designs significantly impact fluid pressure. Under different operating conditions, uneven pressure or flow velocity mismatch can easily lead to problems such as localized overheating, undercooling, or poor flow.

[0006] 2. When traditional tubular heat exchangers exchange heat with demineralized water, impurities tend to accumulate inside the pipes, requiring regular maintenance and cleaning. Cleaning requires long downtime and is difficult. In addition, a set of tubular heat exchangers can only use one heat source medium for heat exchange, and cannot adjust the heat exchange effect according to different operating conditions, resulting in poor system adaptability. Summary of the Invention

[0007] The purpose of this invention is to provide a preheating facility for demineralized water in power plants in order to solve the above-mentioned problems.

[0008] To achieve the above objectives, the present invention specifically adopts the following technical solution:

[0009] A preheating facility for demineralized water in a power plant includes a heat exchange box. A cross cavity is provided in the center of the heat exchange box. An upper heat exchange cavity and a lower heat exchange cavity are provided on both sides of the cross cavity. An upper heat medium cavity is provided on the side of the upper heat exchange cavity away from the cross cavity, and a lower heat medium cavity is provided on the side of the lower heat exchange cavity away from the cross cavity. A flow guide hole is provided between the cross cavity and the upper and lower heat exchange cavities. A through hole is provided between the upper and lower heat exchange cavities. Lifting windows are provided between the upper heat exchange cavity and the upper heat medium cavity, and between the lower heat exchange cavity and the lower heat medium cavity.

[0010] The heat exchange box is equipped with two sets of Z-shaped heat exchange tube groups. Each Z-shaped heat exchange tube group includes multiple linearly arrayed inclined tubes. The middle of the inclined tubes is rotatably installed in the cross cavity. The inclined tubes of the two sets of Z-shaped heat exchange tube groups are distributed crosswise. Both ends of the inclined tubes are provided with hinge joints. Horizontal tubes are hinged to both sets of hinge joints. The horizontal tubes are connected to the inclined tubes through connecting hoses. A guide plate is provided on the outside of the horizontal tubes. The guide plate can block the guide holes. A telescopic tube is provided at the end of the horizontal tube away from the inclined tubes. A lifting window plate is slidably connected to the side of the lifting window away from the cross cavity. The telescopic tube is fixedly installed through the lifting window plate.

[0011] Furthermore, the top ends of the inclined tubes are connected in series via a connecting shaft, and the inner wall of the cross cavity is provided with an arc-shaped guide opening. The center of the arc-shaped guide opening is on the same axis as the rotation center of the inclined tube, and the connecting shaft can slide along the arc-shaped guide opening.

[0012] Furthermore, two sets of telescopic cylinders are fixedly installed on the top of the heat exchange box. A drive rod is fixedly installed on the telescopic end of the telescopic cylinder. A vertical guide groove is opened inside the drive rod. A sealing arc plate is fixedly installed on one end of the connecting shaft that passes through the arc-shaped guide opening. The sealing arc plate slides and seals with the arc-shaped guide opening. A transmission guide post is provided on the outside of the sealing arc plate. The transmission guide post is inserted into the vertical guide groove.

[0013] Furthermore, connecting pipe ports are provided at the top and bottom of the cross cavity, the top of the upper heat exchange cavity, the bottom of the lower heat exchange cavity, and the outer sides of the upper and lower heat medium cavities.

[0014] Furthermore, a connecting flange is provided on the connecting pipe port.

[0015] Furthermore, valve plate assemblies are provided at the inner bottom of the upper heat exchange chamber and the inner top of the lower heat exchange chamber. The valve plate assembly consists of a valve plate and a connecting swing plate. The valve plate is slidably connected to the inner bottom of the upper heat exchange chamber. The valve plate has valve holes corresponding to the through holes inside. The two ends of the connecting swing plate are flexibly connected to the valve plate and the horizontal pipe, respectively.

[0016] Furthermore, the flexible connection uses copper sheets.

[0017] Furthermore, both the valve hole and the through hole are rectangular strips.

[0018] Furthermore, both ends of the guide plate and the guide hole are designed as semicircles. The semicircular radius of the guide hole is the same as the outer diameter of the horizontal pipe, and the semicircular radius of the guide plate is greater than the outer diameter of the horizontal pipe.

[0019] The beneficial effects of this invention are as follows:

[0020] 1. This invention employs a cross design of two sets of Z-shaped heat exchange tubes as heat exchange tube groups, which makes the flow path of the fluid in the heat exchange tubes tortuous, increasing the degree of fluid turbulence. Turbulence will promote the faster transfer of heat from the fluid to the tube wall. At the same time, under the guiding effect of the two sets of Z-shaped heat exchange tube groups, the demineralized water can contact the pipe more evenly, improving the heat exchange efficiency. Furthermore, the height difference between the inlet and outlet can reduce pressure loss, thereby reducing the pressure loss caused by heat exchange.

[0021] 2. The present invention features an adjustable inclined tube angle, which can change the height difference between the inlet and outlet during adjustment, making the device suitable for different working conditions and preventing problems such as local overheating, overcooling or poor flow caused by uneven pressure or flow rate mismatch.

[0022] 3. The present invention can guide the flow of demineralized water through the setting of the guide plate and the guide hole, so that it can pass through the heat exchange tube group more evenly. By adjusting the angle of the inclined tube, the guide plate can block the guide hole, which can change the heat exchange space in the heat exchange box. This allows the equipment to be cleaned without stopping the machine. Furthermore, it can be adjusted for multi-media heat exchange according to different operating conditions, making it widely applicable. Attached Figure Description

[0023] Figure 1 This is a three-dimensional structural schematic diagram of the present invention;

[0024] Figure 2 This is a schematic diagram of the internal structure of the present invention;

[0025] Figure 3 This is a schematic diagram of the heat exchanger structure of the present invention;

[0026] Figure 4 This is a schematic diagram of the cross structure of two sets of Z-shaped heat exchanger tubes in this invention. Figure 1 ;

[0027] Figure 5 This is a schematic diagram of the cross structure of two sets of Z-shaped heat exchanger tubes in this invention. Figure 2 ;

[0028] Figure 6 This is a schematic diagram of the Z-shaped heat exchanger tube assembly structure of the present invention;

[0029] Figure 7 This is a schematic diagram of the valve plate assembly structure of the present invention.

[0030] Reference numerals: 1. Heat exchanger box; 11. Cross cavity; 12. Arc-shaped guide port; 13. Upper heat exchanger cavity; 14. Lower heat exchanger cavity; 15. Upper heat medium cavity; 16. Lower heat medium cavity; 17. Flow guide hole; 18. Through hole; 19. Lifting window; 2. Inclined tube; 21. Hinge joint; 22. Horizontal tube; 23. Connecting hose; 24. Telescopic tube; 25. Lifting window plate; 26. Flow guide plate; 27. Sealing arc plate; 28. Transmission guide column; 3. Valve plate assembly; 31. Valve plate; 32. Connecting swing plate; 33. Valve hole; 4. Telescopic cylinder; 5. Drive rod. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0032] Example 1, as Figures 1-7 As shown, a preheating facility for demineralized water in a power plant includes a heat exchange box 1. A cross cavity 11 is provided in the center of the heat exchange box 1. An upper heat exchange cavity 13 and a lower heat exchange cavity 14 are provided on both sides of the cross cavity 11. An upper heat medium cavity 15 is provided on the side of the upper heat exchange cavity 13 away from the cross cavity 11, and a lower heat medium cavity 16 is provided on the side of the lower heat exchange cavity 14 away from the cross cavity 11. A guide hole 17 is provided between the cross cavity 11 and the upper heat exchange cavity 13 and the lower heat exchange cavity 14. A through hole 18 is provided between the upper heat exchange cavity 13 and the lower heat exchange cavity 14. Lifting windows 19 are provided between the upper heat exchange cavity 13 and the upper heat medium cavity 15, and between the lower heat exchange cavity 14 and the lower heat medium cavity 16.

[0033] The heat exchange box 1 is equipped with two sets of Z-shaped heat exchange tube groups. Each Z-shaped heat exchange tube group includes multiple linearly arrayed inclined tubes 2. The middle of the inclined tubes 2 is rotatably installed in the cross cavity 11. The inclined tubes 2 of the two sets of Z-shaped heat exchange tube groups are distributed crosswise. Both ends of the inclined tubes 2 are provided with hinge joints 21. Horizontal tubes 22 are hinged in both sets of hinge joints 21. The horizontal tubes 22 and the inclined tubes 2 are connected through connecting hoses 23. A guide plate 26 is provided on the outside of the horizontal tubes 22. The guide plate 26 can block the guide hole 17. A telescopic tube 24 is provided at the end of the horizontal tubes 22 away from the inclined tubes 2. A lifting window plate 25 is slidably connected to the side of the lifting window 19 away from the cross cavity 11. The telescopic tube 24 is fixedly installed on the lifting window plate 25.

[0034] Full-channel use: At this time, the guide plate 26 is far away from the guide hole 17, and the guide plate 26 and the guide hole 17 are staggered. The inclination angle of the two sets of inclined tubes 2 is the minimum, that is, the slope is the minimum. The upper heat exchange chamber 13 and the lower heat exchange chamber 14 on both sides are connected to the cross chamber 11. At this time, the heat medium enters through the upper heat medium chamber 15 on the left, enters the upper horizontal pipe 22 through the telescopic pipe 24, and then enters the inclined tube 2. Finally, it is discharged into the lower heat medium chamber 16 on the right through the lower horizontal pipe 22 and the telescopic pipe 24, and flows out through the lower heat medium chamber 16, forming a Z-shaped flow path. Similarly, the heat medium enters the upper heat medium chamber 15 on the right and flows out from the lower heat medium chamber 16 on the left. The Z-shaped flow path not only makes the flow path of the fluid in the heat exchange tube more tortuous, increasing the turbulence of the fluid, but also promotes the faster transfer of heat from the fluid to the pipe wall. In addition, the height difference between the inlet and outlet can reduce pressure loss and reduce the pressure loss caused by heat exchange. The demineralized water enters through the lower heat exchange chambers 14 on both sides, first exchanging heat with the horizontal tubes 22 below, then entering the cross chamber 11 and rising along it to exchange heat with the inclined tubes 2. Subsequently, it enters the upper heat exchange chamber 13 through the guide holes 17. At this point, the guide plates 26 act as a barrier, ensuring the demineralized water fills the upper heat exchange chamber 13 more evenly. The demineralized water, after heat exchange, is discharged through the upper heat exchange chamber 13, resulting in an X-shaped flow path through the heat exchange tube assembly, maximizing heat absorption and achieving high heat exchange efficiency. It should be noted that the heat media entering the upper heat medium chambers 15 on both sides can be different, allowing for the simultaneous use of two heat sources.

[0035] Semi-channel use: Control one set of inclined tubes 2 to swing, so that the tilt angle of the inclined tube 2 reaches the maximum. Due to the swing of the inclined tube 2, the horizontal tube 22 swings. The horizontal tube 22 always remains horizontal under the action of the telescopic tube 24 and the lifting window plate 25. Therefore, while the horizontal tube 22 moves horizontally towards the cross cavity 11, it will also rise and fall vertically. Thus, the horizontal tube 22 can drive the guide plate 26, which was originally misaligned with the guide hole 17, to just block the guide hole 17. For example, the guide holes 17 on the upper heat exchange cavity 13 on the left and the lower heat exchange cavity 14 on the right are blocked. At this time, the demineralized water enters through the lower heat exchange cavity 14 on the left, then enters the cross cavity 11, and rises along the cross cavity 11. Then it enters the upper heat exchange cavity 13 on the right through the guide hole 17, so that the demineralized water flows through the heat exchange tube group in a Z-shaped path, which can fully absorb the heat of the single heat exchange tube group. At this time, the inside of the heat exchange tube group with the maximum swing angle of the inclined tube 2 can be flushed, and the outer tube of the horizontal tube 22 can also be flushed, so that cleaning can be carried out without stopping the machine.

[0036] Three-channel operation: Simultaneously control the swing of two sets of inclined tubes 2 to maximize the tilt angle of the two sets of inclined tubes 2. All guide holes 17 are blocked, and the through hole 18 is opened at the same time. The upper heat exchange chamber 13 and the lower heat exchange chamber 14 on the same side are connected. At this time, the upper heat exchange chamber 13 and the lower heat exchange chamber 14 on the left side form a channel, the cross chamber 11 forms a channel, and the upper heat exchange chamber 13 and the lower heat exchange chamber 14 on the right side form a channel. Heat exchange can be performed on three different cold media. The channels on both sides can also be used. The cross chamber 11 is used for flushing to clean the outer surface of the inclined tube 2.

[0037] This invention can achieve different heat exchange adjustments according to different working conditions, and the heat exchange adjustment in each state can achieve uniform heat exchange. Furthermore, when the inclined tube 2 has not swung to the maximum tilt angle, the flow rate of the heat medium can also be adjusted. Pressure stabilization control can be achieved during the heat exchange process, which can eliminate the influence of unstable heat medium water pressure on heat exchange.

[0038] In the second embodiment, based on the above embodiment, the top end of the inclined tube 2 is connected in series by a connecting shaft, and the inner wall of the cross cavity 11 is provided with an arc-shaped guide port 12. The center of the arc-shaped guide port 12 is on the same axis as the rotation center of the inclined tube 2, and the connecting shaft can slide along the arc-shaped guide port 12.

[0039] Furthermore, two sets of telescopic cylinders 4 are fixedly installed on the top of the heat exchange box 1. A drive rod 5 is fixedly installed on the telescopic end of the telescopic cylinder 4. A vertical guide groove is opened inside the drive rod 5. A sealing arc plate 27 is fixedly installed at one end of the connecting shaft that passes through the arc-shaped guide port 12. The sealing arc plate 27 slides and seals with the arc-shaped guide port 12. A transmission guide post 28 is provided on the outside of the sealing arc plate 27. The transmission guide post 28 is inserted into the vertical guide groove.

[0040] By controlling the extension of the telescopic cylinder 4, the telescopic cylinder 4 drives the drive rod 5 to move towards the middle of the cross cavity 11. The drive rod 5 drives the connecting shaft to slide along the arc-shaped guide port 12 through the transmission guide post 28, and the transmission guide post 28 will rise along the vertical guide groove. The connecting shaft drives the top of the inclined tube 2 to swing upward, thereby making the inclined tube 2 tilt angle reach the maximum. Under the action of the sealing arc plate 27, the arc-shaped guide port 12 always remains sealed and there will be no leakage. The swing control of multiple inclined tubes 2 in the same heat exchange tube group can be realized at one time, and the control is simple.

[0041] In embodiment three, based on the above embodiments, a connecting pipe port is provided at the top and bottom of the cross cavity 11, the top of the upper heat exchange cavity 13, the bottom of the lower heat exchange cavity 14, and the outer side of the upper heat medium cavity 15 and the lower heat medium cavity 16.

[0042] Furthermore, a connecting flange is provided on the connecting pipe port.

[0043] The design of the connecting port facilitates connection with external pipelines.

[0044] Example 4, based on the above examples, further includes a valve plate assembly 3 provided at the inner bottom of the upper heat exchange chamber 13 and the inner top of the lower heat exchange chamber 14. The valve plate assembly 3 is composed of a valve plate 31 and a connecting swing plate 32. The valve plate 31 is slidably connected to the inner bottom of the upper heat exchange chamber 13. The valve plate 31 has a valve hole 33 corresponding to the through hole 18 inside. The two ends of the connecting swing plate 32 are flexibly connected to the valve plate 31 and the horizontal pipe 22, respectively.

[0045] Furthermore, copper sheets are used for the flexible connection.

[0046] Furthermore, both valve hole 33 and through hole 18 are rectangular strips, which, when connected, allow for a larger flow rate.

[0047] By controlling the extension of the telescopic cylinder 4, the telescopic cylinder 4 drives the drive rod 5 to move towards the center of the cross cavity 11. The drive rod 5 drives the connecting shaft to slide along the arc-shaped guide opening 12 through the transmission guide post 28, and the transmission guide post 28 will rise along the vertical guide groove. The connecting shaft drives the top of the inclined tube 2 to swing upward, thereby making the inclined tube 2 tilt at its maximum angle. Due to the swing of the inclined tube 2, the horizontal tube 22 swings. The horizontal tube 22 always remains horizontal under the action of the telescopic tube 24 and the lifting window plate 25. Therefore, while the horizontal tube 22 moves horizontally towards the cross cavity 11, it also moves vertically up and down. Thus, the horizontal tube 22 can drive the guide plate 26, which was originally misaligned with the guide hole 17. Just as the guide hole 17 is blocked, the horizontal pipe 22 in the upper heat exchange chamber 13 rises. The horizontal pipe 22 drives the connecting swing plate 32 to rise. The connecting swing plate 32 drives the valve plate 31 to approach the cross chamber 11, so that the valve hole 33, which was originally misaligned with the through hole 18, moves to correspond with the through hole 18. However, the through hole 18 is still blocked by the valve plate 31 in the lower heat exchange chamber 14. Therefore, during half-channel heat exchange, the upper heat exchange chamber 13 and the lower heat exchange chamber 14 on the same side are not connected. Only when the two sets of inclined pipes 2 swing to the maximum angle at the same time, the upper and lower valve holes 33 correspond to the through hole 18, realizing the connection between the upper heat exchange chamber 13 and the lower heat exchange chamber 14, and three-channel heat exchange can be performed.

[0048] Example 5, based on the above examples, further includes that both ends of the guide plate 26 and the guide hole 17 are semi-circular, the semi-circular radius of the guide hole 17 is the same as the outer diameter of the horizontal pipe 22, and the semi-circular radius of the guide plate 26 is greater than the outer diameter of the horizontal pipe 22.

[0049] This design enables the horizontal tube 22 to move stably up and down within the guide hole 17, making the adjustment of the horizontal tube 22 more stable.

[0050] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A preheating facility for demineralized water in a power plant, comprising a heat exchanger (1), characterized in that, A cross cavity (11) is provided in the center of the heat exchange box (1). An upper heat exchange cavity (13) and a lower heat exchange cavity (14) are provided on both sides of the cross cavity (11). An upper heat medium cavity (15) is provided on the side of the upper heat exchange cavity (13) away from the cross cavity (11). A lower heat medium cavity (16) is provided on the side of the lower heat exchange cavity (14) away from the cross cavity (11). A flow guide hole (17) is provided between the cross cavity (11) and the upper heat exchange cavity (13) and the lower heat exchange cavity (14). A through hole (18) is provided between the upper heat exchange cavity (13) and the lower heat exchange cavity (14). A lifting window (19) is provided between the upper heat exchange cavity (13) and the upper heat medium cavity (15) and between the lower heat exchange cavity (14) and the lower heat medium cavity (16). The heat exchange box (1) is equipped with two sets of Z-shaped heat exchange tube groups. The Z-shaped heat exchange tube group includes multiple linearly arrayed inclined tubes (2). The middle of the inclined tubes (2) is rotatably installed in the cross cavity (11). The inclined tubes (2) of the two sets of Z-shaped heat exchange tube groups are distributed in a cross pattern. Both ends of the inclined tubes (2) are provided with hinge joints (21). Horizontal tubes (22) are hinged in both sets of hinge joints (21). The horizontal tubes (22) and the inclined tubes (2) are connected through connecting hoses (23). A guide plate (26) is provided on the outside of the horizontal tubes (22). The guide plate (26) can block the guide hole (17). A telescopic tube (24) is provided at the end of the horizontal tubes (22) away from the inclined tubes (2). A lifting window plate (25) is slidably connected on the side of the lifting window (19) away from the cross cavity (11). The telescopic tube (24) is fixedly installed through the lifting window plate (25).

2. The preheating facility for demineralized water in a power plant according to claim 1, characterized in that, The top of the inclined tube (2) is connected in series by a connecting shaft. The inner wall of the cross cavity (11) is provided with an arc-shaped guide port (12). The center of the arc-shaped guide port (12) and the rotation center of the inclined tube (2) are on the same axis. The connecting shaft can slide along the arc-shaped guide port (12).

3. The preheating facility for demineralized water in a power plant according to claim 2, characterized in that, Two sets of telescopic cylinders (4) are fixedly installed on the top of the heat exchange box (1). A drive rod (5) is fixedly installed on the telescopic end of the telescopic cylinder (4). A vertical guide groove is opened inside the drive rod (5). A sealing arc plate (27) is fixedly installed at one end of the connecting shaft that passes through the arc guide port (12). The sealing arc plate (27) slides and seals with the arc guide port (12). A transmission guide post (28) is provided on the outside of the sealing arc plate (27). The transmission guide post (28) is inserted into the vertical guide groove.

4. The preheating facility for demineralized water in a power plant according to claim 1, characterized in that, Connecting pipe openings are provided at the top and bottom of the cross cavity (11), the top of the upper heat exchange cavity (13), the bottom of the lower heat exchange cavity (14), and the outer sides of the upper heat medium cavity (15) and the lower heat medium cavity (16).

5. The preheating facility for demineralized water in a power plant according to claim 4, characterized in that, A connecting flange is provided on the connecting pipe port.

6. The preheating facility for demineralized water in a power plant according to claim 1, characterized in that, Valve plate assemblies (3) are provided at the bottom inner side of the upper heat exchange chamber (13) and the top inner side of the lower heat exchange chamber (14). The valve plate assembly (3) consists of a valve plate (31) and a connecting swing plate (32). The valve plate (31) is slidably connected to the bottom inner side of the upper heat exchange chamber (13). The valve plate (31) has a valve hole (33) corresponding to the through hole (18) inside. The two ends of the connecting swing plate (32) are flexibly connected to the valve plate (31) and the horizontal pipe (22) respectively.

7. A preheating facility for demineralized water in a power plant according to claim 6, characterized in that, The flexible connection uses copper sheets.

8. The preheating facility for demineralized water in a power plant according to claim 7, characterized in that, Both the valve hole (33) and the through hole (18) are rectangular strips.

9. A preheating facility for demineralized water in a power plant according to claim 1, characterized in that, Both ends of the guide plate (26) and the guide hole (17) are semi-circular. The semi-circular radius of the guide hole (17) is the same as the outer diameter of the horizontal pipe (22), and the semi-circular radius of the guide plate (26) is greater than the outer diameter of the horizontal pipe (22).

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