In-pipe evaporation coil pipe type evaporator for high-capacity solar photo-thermal power generation

Abstract

The utility model discloses an in-pipe evaporation coil pipe type evaporator for high-capacity solar photo-thermal power generation, and relates to the technical field of evaporators. The problems that an existing high-capacity photo-thermal power station evaporator is of a U-pipe type structure, equipment cannot be large, and the number of evaporators is too large are solved. The evaporator adopts the S-shaped tube bundle, so that the diameter of the tube plate can be reduced, and under the same temperature and pressure parameters, the smaller the diameter of the tube plate is, the thinner the thickness is, so that the problems that the tube plate is too thick, tube holes are difficult to machine and equipment cannot be large-sized due to the fact that a conventional U-tube type evaporator is adopted for large-capacity solar photo-thermal power generation are solved. Medium in the snake-shaped tube bundle spirally flows along the tube bundle, and the flowing is beneficial to formation of turbulent flow, so that heat exchange can be enhanced. Medium flow outside the tube bundle completely transversely penetrates through the tube bundle, the heat exchange coefficient is higher compared with flow on the shell side of a U-tube type evaporator, and therefore the whole heat exchange effect of the coil tube type evaporator is better. The evaporator is suitable for the technical field of evaporators.

Description

Technical Field

[0001] The utility model relates to the technical field of evaporators, in particular to an in-tube evaporation coil-type evaporator for large-capacity solar thermal power generation. Background Art

[0002] As a renewable energy source with built-in energy storage, CSP offers several inherent advantages over other renewable energy sources, such as wind and photovoltaics. These advantages include 24-hour stable power output, regardless of weather conditions, and the ability to participate in grid peak and frequency regulation. These advantages have led to its growing popularity. In recent years, the scale of CSP projects under construction in China has seen unprecedented growth, and the capacity of individual CSP units has also continued to increase. The first wave of CSP demonstration projects, which mostly employed 50MW units, has evolved to 100MW units for large-scale wind and solar projects in recent years, with some reaching 150MW and 200MW. In the future, CSP unit capacity is expected to exceed 300MW. This increase in unit capacity will help reduce the cost of CSP. Given the current trend of declining national policy support for CSP, if CSP is to compete with wind and photovoltaic power, expanding to larger capacities is a must.

[0003] As a key heat exchanger in a CSP (Concentrated Solar Power Generation) (SGS) system, the evaporator carries the largest heat transfer load of all heat exchangers in the system, resulting in the largest heat transfer area and equipment volume. For example, in a current mainstream 100MW CSP SGS system, the evaporator typically uses a U-tube heat exchanger configuration, with two units installed. This requirement is primarily due to the large heat transfer area required by the evaporator. Using a single U-tube configuration would result in an excessively large tube diameter, increased tube sheet thickness, and tube hole machining difficulties exceeding current manufacturing standards. As the capacity of a single CSP unit continues to increase, the number of evaporators will also increase. This poses a significant cost penalty for CSP, as a larger number of evaporators increases the unit cost and the number of associated instruments, valves, and piping increases. Furthermore, SGS system control becomes more complex, increasing the complexity of system layout and piping design. Utility Model Content

[0004] In order to solve the problem that the existing large-capacity solar thermal power station evaporator adopts a U-tube structure, which makes the equipment unable to be large-scaled and thus leads to an excessive number of evaporators, the utility model proposes an in-tube evaporation coil evaporator for large-capacity solar thermal power generation.

[0005] The utility model discloses an in-tube evaporation coil-type evaporator for large-capacity solar thermal power generation, which comprises a coil heat exchanger 1, a serpentine tube bundle 2, an upper tube sheet 3, an upper tube box 4, a lower tube sheet 5, a lower tube box 6, a shell-side inlet pipe 7, a shell-side outlet pipe 8, a riser group 9, a downcomer group 10, a steam drum 11, a primary steam-water separator 12, a secondary steam-water separator 13 and a steam outlet pipe 14;

[0006] The outer surface of the coiled tube heat exchanger 1 is provided with a shell-side inlet pipe 7 and a shell-side outlet pipe 8 in sequence along the length direction. A serpentine tube bundle 2 is provided inside the coiled tube heat exchanger 1. A lower tube box 6 is provided at the bottom open end of the coiled tube heat exchanger 1, and a lower tube plate 5 is provided at the connection between the lower tube box 6 and the bottom open end of the coiled tube heat exchanger 1. An upper tube box 4 is provided at the top open end of the coiled tube heat exchanger 1. An upper tube plate 3 is provided at the connection between the upper tube box 4 and the top open end of the coiled tube heat exchanger 1. The two input ports on the upper tube box 4 are respectively provided with a rising tube group 9. The top of the rising tube group 9 is connected to the middle steam-water circulation port of the steam drum 11. A first-level steam-water separator 12 is respectively provided on both sides of the interior of the steam drum 11. A second-level steam-water separator 13 is provided at the top of the steam drum 11. A steam outlet pipe 14 is provided at the top center of the steam drum 11. A downcomer group 10 is respectively provided at the two output ends of the lower tube box 6. The top of the downcomer group 10 is connected to the end steam-water circulation port of the steam drum 11.

[0007] Furthermore, the upper tube box 4, the upper tube sheet 3, the serpentine heat exchanger 1, the serpentine tube bundle 2, the lower tube sheet 5 and the lower tube box 6 are coaxially arranged;

[0008] Furthermore, the inner diameters of the riser pipe group 9 and the downcomer pipe group 10 are the same;

[0009] Furthermore, the steam drum 11 is arranged directly above the coiled tube heat exchanger 1;

[0010] Furthermore, the riser pipe group 9 includes two straight pipes and an elbow, and the two straight pipes are connected by the elbow;

[0011] Furthermore, the structures of the riser group 9 and the downcomer group 10 are the same;

[0012] Furthermore, the two first-stage steam-water separators 12 inside the steam drum 11 are both cyclone separators or eddy current separators;

[0013] Furthermore, the secondary steam-water separator 13 inside the steam drum 11 adopts a corrugated plate or wire mesh structure;

[0014] Furthermore, when the coiled tube evaporator is in operation, the water level is at the centerline of the steam drum 11, and the tubes of the coiled tube heat exchanger 1, the riser tube group 9, and the downcomer tube group 10 are filled with saturated water. At this point, a high-temperature medium, such as molten salt or thermal oil, is introduced through the shell-side inlet pipe 7 located at the upper portion of the coiled tube heat exchanger 1. The high-temperature medium flows downward within the shell, through the coiled tube bundle 2, and is withdrawn through the shell-side outlet pipe 8 located at the lower portion of the coiled tube heat exchanger 1. The saturated water within the coiled tube bundle 2 is heated by the high-temperature medium outside the tube bundle, generating steam. Because the density of the steam-water mixture is lower than that of saturated water, a natural circulation driving force is generated by the density difference within the closed circuit formed by the steam drum 11, downcomer tube group 10, coiled tube heat exchanger 1, and riser tube group 9. The circulating power propels the steam-water mixture within the serpentine tube bundle 2 upward, passing through the upper tube box 4 into the riser tube group 9 and then into the steam drum 11. Once in the steam drum 11, the steam-water mixture first enters the primary steam-water separator 12 for preliminary separation. After primary separation, the steam, carrying a small amount of water, flows upward within the steam drum 11 into the secondary steam-water separator 13 for fine separation. Once the steam meets the required quality, it is discharged through the steam outlet pipe 14 of the steam drum 11. The water separated by the primary and secondary steam-water separators 12 and 13 is collected in the water space below the centerline of the steam drum 11. It then flows back through the downcomer group 10 to the lower tube box 6 of the serpentine heat exchanger 1 and reenters the serpentine tube bundle 2 for evaporation. Through this continuous circulation of water, the saturated water evaporates and the steam and water separate, continuously generating the required steam.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] The present invention overcomes the shortcomings of the prior art. The evaporator adopts a serpentine tube bundle to reduce the diameter of the tube sheet. Under the same temperature and pressure parameters, the smaller the tube sheet diameter, the thinner the thickness. This solves the problem of large-capacity solar thermal power generation using conventional U-tube evaporators, which leads to excessive thickness of the tube sheet, difficulty in processing the tube holes, and the inability to scale up the equipment. The medium in the serpentine tube bundle flows along the tube bundle spirally. This flow is conducive to the formation of turbulence and can enhance heat exchange. The medium flow outside the tube bundle is all transverse to the tube bundle. Compared with the shell-side flow of the U-tube evaporator, the heat transfer coefficient is higher, so the overall heat exchange effect of the serpentine evaporator is better. The serpentine evaporator adopts a vertical structure heat exchanger. Compared with the horizontal structure of the conventional U-tube evaporator, it is more conducive to the flow of the steam-water mixture in the tube, does not form steam resistance, and the water dynamics are safer and more reliable. The steam drum of the serpentine evaporator is arranged directly above the serpentine heat exchanger, which is more compact and can reduce the length of the riser group and the downcomer group, saving pipeline materials. The steam drum adopts two-stage steam-water separation, which has better steam-water separation effect and higher steam quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1This is a front view of a coiled tube evaporator for large-capacity solar thermal power generation described in the utility model;

[0018] Figure 2 It is a side sectional view of an in-tube evaporation coil-type evaporator for large-capacity solar thermal power generation described in the utility model. DETAILED DESCRIPTION

[0019] Specific implementation method 1: Combination Figure 1 and Figure 2 This embodiment describes an in-tube evaporator for large-capacity solar thermal power generation, which comprises a coiled tube heat exchanger 1, a serpentine tube bundle 2, an upper tube sheet 3, an upper tube box 4, a lower tube sheet 5, a lower tube box 6, a shell-side inlet pipe 7, a shell-side outlet pipe 8, a riser tube group 9, a downcomer tube group 10, a steam drum 11, a primary steam-water separator 12, a secondary steam-water separator 13, and a steam outlet pipe 14.

[0020] The outer surface of the coiled tube heat exchanger 1 is provided with a shell-side inlet pipe 7 and a shell-side outlet pipe 8 in sequence along the length direction. A serpentine tube bundle 2 is provided inside the coiled tube heat exchanger 1. A lower tube box 6 is provided at the bottom open end of the coiled tube heat exchanger 1, and a lower tube plate 5 is provided at the connection between the lower tube box 6 and the bottom open end of the coiled tube heat exchanger 1. An upper tube box 4 is provided at the top open end of the coiled tube heat exchanger 1. An upper tube plate 3 is provided at the connection between the upper tube box 4 and the top open end of the coiled tube heat exchanger 1. The two input ports on the upper tube box 4 are respectively provided with a rising tube group 9. The top of the rising tube group 9 is connected to the middle steam-water circulation port of the steam drum 11. A first-level steam-water separator 12 is respectively provided on both sides of the interior of the steam drum 11. A second-level steam-water separator 13 is provided at the top of the steam drum 11. A steam outlet pipe 14 is provided at the top center of the steam drum 11. A downcomer group 10 is respectively provided at the two output ends of the lower tube box 6. The top of the downcomer group 10 is connected to the end steam-water circulation port of the steam drum 11.

[0021] In this embodiment, when the coiled tube evaporator is in operation, the water level is at the centerline of the steam drum 11, and the tubes of the coiled tube heat exchanger 1, the riser tube group 9, and the downcomer tube group 10 are filled with saturated water. At this point, a high-temperature medium, such as molten salt or thermal oil, is introduced through the shell-side inlet pipe 7 located at the upper portion of the coiled tube heat exchanger 1. The high-temperature medium flows downward within the shell, through the coiled tube bundle 2, and is withdrawn through the shell-side outlet pipe 8 located at the lower portion of the coiled tube heat exchanger 1. The saturated water within the coiled tube bundle 2 is heated by the high-temperature medium outside the tube bundle, generating steam. Because the density of the steam-water mixture is lower than that of saturated water, a natural circulation driving force is generated by the density difference within the closed circuit formed by the steam drum 11, downcomer tube group 10, coiled tube heat exchanger 1, and riser tube group 9. The circulating power propels the steam-water mixture within the serpentine tube bundle 2 upward, passing through the upper tube box 4 into the riser tube group 9 and then into the steam drum 11. Once in the steam drum 11, the steam-water mixture first enters the primary steam-water separator 12 for preliminary separation. After primary separation, the steam, carrying a small amount of water, flows upward within the steam drum 11 into the secondary steam-water separator 13 for fine separation. Once the steam meets the required quality, it is discharged through the steam outlet pipe 14 of the steam drum 11. The water separated by the primary and secondary steam-water separators 12 and 13 is collected in the water space below the centerline of the steam drum 11. It then flows back through the downcomer group 10 to the lower tube box 6 of the serpentine heat exchanger 1 and reenters the serpentine tube bundle 2 for evaporation. Through this continuous circulation of water, the saturated water evaporates and the steam and water separate, continuously generating the required steam.

[0022] Specific implementation method 2: Combination Figure 1 and Figure 2 This embodiment is described. This embodiment further limits the evaporator described in the specific embodiment one. This embodiment describes an in-tube evaporation coil-type evaporator for large-capacity solar thermal power generation, in which the upper tube box 4, upper tube plate 3, coil heat exchanger 1, serpentine tube bundle 2, lower tube plate 5 and lower tube box 6 are coaxially arranged.

[0023] Specific implementation method three: Combination Figure 1 and Figure 2 This embodiment is described as a further limitation of the evaporator described in the first embodiment. This embodiment describes an in-tube evaporation coil-type evaporator for large-capacity solar thermal power generation, in which the inner diameters of the riser group 9 and the downcomer group 10 are the same.

[0024] Specific implementation method four: Combination Figure 1 and Figure 2This embodiment is described as a further limitation of the evaporator described in the first embodiment. This embodiment describes an in-tube evaporation coil-type evaporator for large-capacity solar thermal power generation, in which the steam drum 11 is arranged directly above the coil heat exchanger 1.

[0025] Specific implementation method five: Combination Figure 1 and Figure 2 This embodiment is described as a further limitation of the evaporator described in the third embodiment. In this embodiment, an in-tube evaporation coil-type evaporator for large-capacity solar thermal power generation is described. The riser tube group 9 includes two straight tubes and an elbow, and the two straight tubes are connected by the elbow.

[0026] In this specific embodiment, two straight pipes are connected by elbows to form a riser pipe group 9. By providing an appropriate number of elbows, the thermal expansion of the pipeline can be absorbed and the thermal stress of the pipeline can be reduced.

[0027] Specific implementation method six: combination Figure 1 and Figure 2 This embodiment is described as a further limitation of the evaporator described in the fifth embodiment. This embodiment describes an in-tube evaporation coil-type evaporator for large-capacity solar thermal power generation, and the structures of the riser group 9 and the downcomer group 10 are the same.

[0028] Specific implementation method seven: combination Figure 1 and Figure 2 This embodiment is described as a further limitation of the evaporator described in the first embodiment. In this embodiment, an in-tube evaporation coil-type evaporator for large-capacity solar thermal power generation is described. The two primary steam-water separators 12 inside the steam drum 11 are both cyclone separators or eddy current separators.

[0029] In this specific embodiment, the two primary steam-water separators 12 are both cyclone separators or eddy current separators for primary coarse separation of the steam-water mixture.

[0030] Specific implementation method eight: combination Figure 1 and Figure 2 This embodiment further defines the evaporator described in the first embodiment. In this embodiment, a coiled tube evaporator for large-capacity solar thermal power generation is provided. The secondary steam-water separator 13 inside the steam drum 11 is constructed of a corrugated plate or wire mesh structure.

[0031] In this embodiment, the secondary steam-water separator 13 adopts a corrugated plate or wire mesh structure for secondary fine separation of water vapor.

[0032] How it works

[0033] When a coiled tube evaporator is in operation, the water level is at the centerline of the steam drum 11, and the tubes of the coiled tube heat exchanger 1, the riser tube group 9, and the downcomer tube group 10 are filled with saturated water. At this point, a high-temperature medium, such as molten salt or thermal oil, is introduced through the shell-side inlet pipe 7 located at the upper portion of the coiled tube heat exchanger 1. The high-temperature medium flows downward within the shell, through the coiled tube bundle 2, and is withdrawn through the shell-side outlet pipe 8 located at the lower portion of the coiled tube heat exchanger 1. The saturated water within the coiled tube bundle 2 is heated by the high-temperature medium outside the bundle, generating steam. Because the density of the steam-water mixture is lower than that of saturated water, a natural circulation driving force is generated by the density difference within the closed circuit formed by the steam drum 11, downcomer tube group 10, coiled tube heat exchanger 1, and riser tube group 9. The circulating power propels the steam-water mixture within the serpentine tube bundle 2 upward, passing through the upper tube box 4 into the riser tube group 9 and then into the steam drum 11. Once in the steam drum 11, the steam-water mixture first enters the primary steam-water separator 12 for preliminary separation. After primary separation, the steam, carrying a small amount of water, flows upward within the steam drum 11 into the secondary steam-water separator 13 for fine separation. Once the steam meets the required quality, it is discharged through the steam outlet pipe 14 of the steam drum 11. The water separated by the primary and secondary steam-water separators 12 and 13 is collected in the water space below the centerline of the steam drum 11. It then flows back through the downcomer group 10 to the lower tube box 6 of the serpentine heat exchanger 1 and reenters the serpentine tube bundle 2 for evaporation. Through this continuous circulation of water, the saturated water evaporates and the steam and water separate, continuously generating the required steam.

Claims

1. An in-tube evaporation coil-type evaporator for large-capacity solar thermal power generation, characterized by: It comprises a coil heat exchanger (1), a coil tube bundle (2), an upper tube sheet (3), an upper tube box (4), a lower tube sheet (5), a lower tube box (6), a shell side inlet pipe (7), a shell side outlet pipe (8), a riser tube group (9), a downcomer tube group (10), a steam drum (11), a first-stage steam-water separator (12), a second-stage steam-water separator (13) and a steam outlet pipe (14); The outer surface of the coil heat exchanger (1) is provided with a shell side inlet pipe (7) and a shell side outlet pipe (8) in sequence along the length direction. The interior of the coil heat exchanger (1) is provided with a serpentine tube bundle (2). The bottom open end of the coil heat exchanger (1) is provided with a lower tube box (6), and the connection between the lower tube box (6) and the bottom open end of the coil heat exchanger (1) is provided with a lower tube plate (5). The top open end of the coil heat exchanger (1) is provided with an upper tube box (4), and the connection between the upper tube box (4) and the top open end of the coil heat exchanger (1) is provided with an upper tube plate (3). The two input ports are respectively provided with a rising pipe group (9), the top end of the rising pipe group (9) is connected to the middle steam-water circulation port of the steam drum (11), a first-stage steam-water separator (12) is respectively provided on both sides of the interior of the steam drum (11), a second-stage steam-water separator (13) is provided at the top end of the steam drum (11), a steam outlet pipe (14) is provided at the center of the top of the steam drum (11), and a downpipe group (10) is respectively provided at the two output ends of the downpipe box (6), and the top end of the downpipe group (10) is connected to the end steam-water circulation port of the steam drum (11).

2. The in-tube evaporation coil-type evaporator for large-capacity solar thermal power generation according to claim 1, characterized in that: The upper tube box (4), upper tube plate (3), serpentine heat exchanger (1), serpentine tube bundle (2), lower tube plate (5) and lower tube box (6) are coaxially arranged.

3. The in-tube evaporation coiled tube evaporator for large-capacity solar thermal power generation according to claim 1, characterized in that: The inner diameters of the pipes of the rising pipe group (9) and the downcomer pipe group (10) are the same.

4. The in-tube evaporator for large-capacity solar thermal power generation according to claim 1, characterized in that: The steam drum (11) is arranged directly above the coiled tube heat exchanger (1).

5. The in-tube evaporation coiled tube evaporator for large-capacity solar thermal power generation according to claim 3, characterized in that: The rising pipe group (9) comprises two straight pipes and an elbow, and the two straight pipes are connected via the elbow.

6. The in-tube evaporation coiled tube evaporator for large-capacity solar thermal power generation according to claim 5, characterized in that: The structures of the rising pipe group (9) and the downcomer group (10) are the same.

7. The coiled tube evaporator for large-capacity solar thermal power generation according to claim 1, characterized in that: The two first-stage steam-water separators (12) inside the steam drum (11) are both cyclone separators or eddy current separators.

8. The in-tube evaporator for large-capacity solar thermal power generation according to claim 1, characterized in that: The secondary steam-water separator (13) inside the steam drum (11) adopts a corrugated plate or wire mesh structure.

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