A preheating evaporator for photo-thermal energy storage power generation

Abstract

This utility model discloses a preheating evaporator for solar thermal energy storage power generation, comprising a preheating section and an evaporation section. The preheating section includes a high-temperature side preheating cylinder located at one end of the evaporation cylinder and a low-temperature side preheating cylinder located at the other end of the evaporation cylinder. Both the high-temperature and low-temperature side preheating cylinders are connected to a tube sheet at their outer ends, and the tube sheet is provided with several heat exchange tubes. Each heat exchange tube includes a spiral section and straight tube sections integrally formed on both sides of the spiral section. Both the high-temperature and low-temperature side preheating cylinders have water inlets at their lower parts, and the evaporation cylinder has a steam outlet at its upper part. This utility model, through the combination of double-sided preheating cylinders and spiral section heat exchange tubes, ensures sufficient heat exchange and uniform heat load distribution. The spiral section of the heat exchange tube not only extends the heat exchange path and increases the heat exchange area but also compensates for the thermal expansion of the heat exchange tube, reducing the stress caused by the expansion difference between the heat exchange tube and the tube sheet, thus ensuring the stability of the preheating evaporator.

Description

Technical Field

[0001] This utility model belongs to the field of solar thermal energy storage power generation technology, and specifically relates to a preheating evaporator for solar thermal energy storage power generation. Background Technology

[0002] As the global energy structure transitions towards cleaner and lower-carbon energy, the development and utilization of renewable energy has become a core development direction in the energy sector. Solar energy, as a clean energy source with abundant reserves and wide distribution, is a key pathway to achieving energy transformation through large-scale utilization. Solar thermal energy storage technology, with its advantages of energy storage, stable power supply, and flexible dispatch, has overcome the intermittent limitations of traditional solar energy utilization and has become an important technological route for the large-scale development of solar energy.

[0003] The core energy conversion process of solar thermal energy storage power generation is "solar energy—thermal energy—mechanical energy—electrical energy": Solar energy is concentrated in a heat absorber by a concentrator, heating a heat transfer medium such as molten salt with good heat-carrying capacity, converting solar energy into thermal energy, which is then stored in a molten salt storage tank. When power generation is needed, the high-temperature molten salt releases heat to heat the heat exchange medium (usually pure water), generating high-temperature, high-pressure steam to drive a turbine and generate electricity, ultimately converting mechanical energy into electrical energy. The evaporation system is the core equipment connecting the thermal storage and power generation stages, and its performance directly affects the energy conversion efficiency and operational economy of the solar thermal energy storage power generation system.

[0004] Existing solar thermal energy storage power generation evaporation systems typically consist of multiple independent devices, including a preheater, evaporator, superheater, reheater, and steam drum. These devices are connected by complex pipelines to form a complete heat exchange medium heating process: the heat exchange medium first enters the preheater and is preheated to near its boiling point by a low-temperature heat medium, then enters the evaporator and is heated to an evaporating state by a high-temperature heat medium, and finally passes through the superheater and reheater to further enhance steam parameters to meet the operating requirements of the steam turbine. However, this multi-device, separate system architecture has significant drawbacks: on the one hand, the large number of devices and complex pipeline layout result in a large system footprint and high land costs; on the other hand, excessively long pipelines increase the flow resistance and heat loss of the heat exchange medium, and the lack of continuity in heat exchange between devices leads to low overall heat exchange efficiency of the entire evaporation system, thus restricting the energy utilization efficiency and economy of solar thermal energy storage power generation systems.

[0005] To address the aforementioned issues, the industry has proposed a technical solution that combines the preheater and evaporator into an integrated preheating evaporator. This integration reduces the number of devices, simplifies pipeline layout, and shrinks the system footprint. It also shortens the heat exchange path of the heat exchange medium, thereby reducing heat loss and flow resistance to some extent and alleviating the efficiency and space issues of separate systems.

[0006] However, existing conventional integrated preheating evaporators still have key technical defects. The core problem lies in the unreasonable design of the tube bundle layout and heat exchange channel: Currently, most mainstream preheating evaporators adopt a U-shaped tube bundle layout, with the heat exchange medium (pure water) flowing in the shell side. This layout results in a short flow path for the heat exchange medium and makes it easy to form laminar flow. Under laminar flow conditions, the convective heat transfer coefficient of the heat exchange medium is low, resulting in insufficient heat transfer between the heat medium and the heat exchange medium. Especially when the temperature gradient of the heat medium changes significantly during the heat exchange process, the heat medium at the end of the heat exchange still retains a certain amount of residual heat. However, due to insufficient heat exchange, this part of the residual heat cannot be effectively recovered and utilized, resulting in energy waste.

[0007] Furthermore, this layout suffers from uneven heat load distribution: the preheated, low-temperature heat exchange medium directly enters the evaporation zone, creating a significant temperature difference with the high-temperature heat medium, which can easily lead to localized undercooling; conversely, the high-temperature heat medium concentrates heat in the heat exchange zone, causing the tube bundle to bear excessively high heat loads locally, resulting in localized overheating. This uneven heat load, with both localized undercooling and overheating, not only further reduces the overall heat exchange efficiency of the preheating evaporator but also causes damage to the tube bundle due to concentrated thermal stress, affecting equipment operational stability and service life, and increasing maintenance costs. Utility Model Content

[0008] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a preheating evaporator for solar thermal energy storage power generation, so as to solve the problems of insufficient heat exchange and uneven heat load distribution in the existing preheating evaporators for solar thermal energy storage power generation.

[0009] To achieve the above objectives, the technical solution adopted by this utility model is as follows: A preheating evaporator for solar thermal energy storage power generation includes a preheating section and an evaporation section. The evaporation section includes an evaporation cylinder. The preheating section includes a high-temperature side preheating cylinder disposed at one end of the evaporation cylinder and a low-temperature side preheating cylinder disposed at the other end of the evaporation cylinder. The diameter of the evaporation cylinder is larger than the diameters of the high-temperature side preheating cylinder and the low-temperature side preheating cylinder. The high-temperature side preheating cylinder and the low-temperature side preheating cylinder are connected to the evaporation cylinder via connecting cylinders. Tube sheets are connected to the outer ends of both the high-temperature side preheating cylinder and the low-temperature side preheating cylinder. One side of the tube sheet is connected to... The tube sheet has several heat exchange tubes, and both ends of the heat exchange tubes are connected to the end caps on both sides. The heat exchange tubes include a spiral section and straight tube sections integrally formed on both sides of the spiral section. The spiral section is located inside the evaporator, and the straight tube sections are located inside the high-temperature side preheater and the low-temperature side preheater. The lower part of the high-temperature side preheater and the low-temperature side preheater are provided with water inlets. The lower part of the end cap near the high-temperature side preheater is provided with a heat source inlet, and the upper part of the end cap near the low-temperature side preheater is provided with a heat source outlet. The upper part of the evaporator is provided with a steam outlet.

[0010] Furthermore, the upper diameter of the connecting cylinder is smaller than its lower diameter.

[0011] Furthermore, a demister is provided on the upper part of the connecting cylinder for separating steam from water.

[0012] Furthermore, both the high-temperature side preheating cylinder and the low-temperature side preheating cylinder are equipped with several baffles arranged alternately in vertical positions.

[0013] Furthermore, the spacing between the baffles inside the low-temperature side preheating cylinder is smaller than the spacing between the baffles inside the high-temperature side preheating cylinder.

[0014] Furthermore, the length of the low-temperature side preheating cylinder is greater than the length of the high-temperature side preheating cylinder, which is used to extend the heat exchange time of the heat exchange medium in the low-temperature side preheating cylinder.

[0015] Furthermore, each of the water inlets is equipped with a flow valve, and the opening degree of the flow valve at the water inlet on the low-temperature side preheating cylinder is smaller than that at the water inlet on the high-temperature side preheating cylinder.

[0016] The beneficial effects of this utility model are: (1) This utility model uses a double-sided preheating cylinder combined with a spiral section heat exchange tube. The heat medium is cooled down along the tube side gradient. The high-temperature heat medium and the low-temperature heat medium are respectively connected to the heat exchange medium in the high-temperature side preheating cylinder and the low-temperature side preheating cylinder. This ensures the sufficiency of heat exchange and the uniformity of heat load distribution. In addition, the spiral section of the heat exchange tube not only extends the heat exchange path and increases the heat exchange area, but also compensates for the thermal expansion of the heat exchange tube, reduces the stress caused by the expansion difference between the heat exchange tube and the tube sheet, and ensures the stability of the preheating evaporator.

[0017] (2) A demister is installed at the top of the connecting cylinder to separate steam and water, ensuring the humidity requirements of the output steam.

[0018] (3) By setting up staggered baffles in the high-temperature side preheating cylinder and the low-temperature side preheating cylinder, the flow path of the heat exchange medium is changed, the heat transfer efficiency between the heat medium and the heat exchange medium is improved, and the baffles in the low-temperature side preheating cylinder are more densely arranged than those in the high-temperature side preheating cylinder, which is conducive to improving the preheating effect of the heat exchange medium in the low-temperature preheating cylinder.

[0019] (4) The length of the low-temperature side preheating cylinder is greater than that of the high-temperature side preheating cylinder. The flow valve makes the opening of the flow valve at the water inlet on the low-temperature side preheating cylinder less than that on the high-temperature side preheating cylinder, which prolongs the heat exchange time of the heat exchange medium in the low-temperature side preheating cylinder and improves the preheating effect of the heat exchange medium in the low-temperature preheating cylinder. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a preheating evaporator structure for solar thermal energy storage power generation according to this utility model.

[0021] In the diagram, 1. High-temperature side preheating cylinder; 2. Low-temperature side preheating cylinder; 3. Evaporator cylinder; 4. Connecting cylinder; 5. End cap; 6. Tube sheet; 7. Heat exchange tube; 8. Baffle plate; 9. Heat source inlet; 10. Heat source outlet; 11. Feed water inlet; 12. Steam outlet; 13. Demister. Detailed Implementation

[0022] The following will be combined with the appendix Figure 1 The technical solutions in the embodiments of this utility model are clearly and completely described herein. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0023] In the description of this utility model, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0024] like Figure 1 As shown, a preheating evaporator for solar thermal energy storage power generation includes a preheating section and an evaporation section. The evaporation section includes an evaporation cylinder 3. The preheating section includes a high-temperature side preheating cylinder 1 disposed at one end of the evaporation cylinder 3 and a low-temperature side preheating cylinder 2 disposed at the other end of the evaporation cylinder 3. The diameter of the evaporation cylinder 3 is larger than the diameters of the high-temperature side preheating cylinder 1 and the low-temperature side preheating cylinder 2. The high-temperature side preheating cylinder 1 and the low-temperature side preheating cylinder 2 are connected to the evaporation cylinder 3 through a connecting cylinder 4. Tube sheets 6 are connected to the outer ends of both the high-temperature side preheating cylinder 1 and the low-temperature side preheating cylinder 2. A head is connected to one side of the tube sheet 6. 5. A plurality of heat exchange tubes 7 are provided on the tube sheet 6, and the two ends of the heat exchange tubes 7 are connected to the end caps 5 on both sides; the heat exchange tubes 7 include a spiral section and a straight tube section integrally formed on both sides of the spiral section. The spiral section is set in the evaporation cylinder 3, and the straight tube section is set in the high-temperature side preheating cylinder 1 and the low-temperature side preheating cylinder 2; the lower part of the high-temperature side preheating cylinder 1 and the low-temperature side preheating cylinder 2 are provided with water inlets 11, the lower part of the end cap 5 near the high-temperature side preheating cylinder 1 is provided with a heat source inlet 9, the upper part of the end cap 5 near the low-temperature side preheating cylinder 2 is provided with a heat source outlet 10, and the upper part of the evaporation cylinder 3 is provided with a steam outlet 12.

[0025] like Figure 1 As shown, the upper diameter of the connecting cylinder 4 is smaller than its lower diameter, which facilitates the collection of steam to the steam outlet 12.

[0026] like Figure 1 As shown, the upper part of the connecting cylinder 4 is equipped with a demister 13 for separating steam from water; the demister 13 captures the tiny droplets entrained in the steam in the evaporation cylinder 3, ensuring the humidity requirements of the output steam.

[0027] like Figure 1 As shown, both the high-temperature side preheating cylinder 1 and the low-temperature side preheating cylinder 2 are provided with several staggered baffles 8. The baffles 8 are used to change the flow path of the heat exchange medium, thereby improving the heat transfer efficiency between the heat medium and the heat exchange medium.

[0028] like Figure 1 As shown, the spacing of the baffles 8 in the low-temperature side preheating cylinder 2 is smaller than that in the high-temperature side preheating cylinder 1. That is, the baffles 8 in the low-temperature side preheating cylinder 2 are arranged more densely than those in the high-temperature side preheating cylinder 1, which is beneficial to improving the preheating effect of the heat exchange medium in the low-temperature preheating cylinder.

[0029] The length of the low-temperature side preheating cylinder 2 is greater than that of the high-temperature side preheating cylinder 1, which is used to extend the heat exchange time of the heat exchange medium in the low-temperature side preheating cylinder 2, thereby improving the preheating effect of the heat exchange medium in the low-temperature preheating cylinder.

[0030] Each water inlet 11 is equipped with a flow valve (not shown in the figure), and the opening degree of the flow valve of the water inlet 11 on the low-temperature side preheating cylinder 2 is smaller than that of the flow valve of the water inlet 11 on the high-temperature side preheating cylinder 1. That is, the flow velocity of the heat exchange medium in the low-temperature side preheating cylinder 2 is smaller than that in the high-temperature side preheating cylinder 1, which is beneficial to prolong the heat exchange time of the heat exchange medium in the low-temperature side preheating cylinder 2 and further improve the preheating effect of the heat exchange medium in the low-temperature preheating cylinder.

[0031] like Figure 1 As shown, a preheating evaporator for solar thermal energy storage power generation operates as follows: a heat transfer medium (such as high-temperature molten salt) is used as a heat source and enters the tube side through the heat source inlet 9 at the lower part of the end cap 5 near the high-temperature side preheating cylinder 1, flowing through the interior of the heat exchange tube 7; pure water is used as a heat exchange medium and enters the shell side from the water inlet 11 at the lower part of the high-temperature side preheating cylinder 1 and the lower part of the low-temperature side preheating cylinder 2, respectively.

[0032] Within the tube side, after the heat medium enters from the heat source inlet 9, it first flows through the "straight tube section" of the heat exchange tube 7 in the high-temperature side preheating cylinder 1, then enters the "spiral section" of the heat exchange tube 7 in the evaporating cylinder 3, and finally flows through the "straight tube section" of the heat exchange tube 7 in the low-temperature side preheating cylinder 2, and is finally discharged from the heat source outlet 10 at the top of the end cap 5 near the low-temperature side preheating cylinder 2 (the temperature of the heat medium decreases gradually along the flow direction, changing from high temperature to low temperature). In addition, the spiral section of the heat exchange tube 7 not only extends the heat exchange path and increases the heat exchange area, but also compensates for the thermal expansion of the heat exchange tube 7, reduces the stress caused by the expansion difference between the heat exchange tube 7 and the tube sheet 6, and ensures the stability of the preheating evaporator.

[0033] Inside the shell side, pure water on both sides exchanges heat with the heat exchange tubes 7 in the corresponding areas. The pure water in the high-temperature preheating cylinder 1 exchanges heat with the high-temperature heat medium that has not cooled down in the tube side through the straight tube section to complete the initial preheating. The pure water in the low-temperature preheating cylinder 2 exchanges heat with the low-temperature heat medium that has cooled down after heat exchange in the evaporation section in the tube side through the straight tube section to complete the preheating by utilizing the residual heat of the heat medium.

[0034] After being preheated by the high-temperature side preheating cylinder 1 and the low-temperature side preheating cylinder 2 respectively, the pure water flows along the shell side into the evaporating cylinder 3 in the middle. At this time, the spiral section of the heat exchange tube 7 in the evaporating cylinder 3 is still connected with the heat medium from the tube side. The pure water continuously absorbs the heat transferred by the spiral section in the large volume shell side space formed by the long cylinder body and the conical cylinder body of the evaporating cylinder 3, and vaporizes after the temperature rises to the boiling point.

[0035] The qualified steam separated in the evaporator 3 is discharged through the steam outlet 12 at the top of the evaporator 3 and can be subsequently transported to equipment such as the superheater to meet the power generation needs; the low-temperature heat medium that has completed heat exchange in the tube is discharged from the heat source outlet 10 and can be recovered to the heat storage link or other waste heat utilization process according to the system design to form an energy cycle.

[0036] The above description is merely an example and illustration of the structure of this utility model. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the scope defined by the structure of this utility model, they should all fall within the protection scope of this utility model.

Claims

1. A preheating evaporator for solar thermal energy storage power generation, comprising a preheating section and an evaporation section, wherein the evaporation section includes an evaporation cylinder, characterized in that, The preheating section includes a high-temperature preheating cylinder located at one end of the evaporating cylinder and a low-temperature preheating cylinder located at the other end of the evaporating cylinder. The diameter of the evaporating cylinder is larger than the diameters of the high-temperature and low-temperature preheating cylinders. The high-temperature and low-temperature preheating cylinders are connected to the evaporating cylinder via connecting cylinders. Tube sheets are connected to the outer ends of both the high-temperature and low-temperature preheating cylinders. A head is connected to one side of the tube sheet. Several heat exchange tubes are provided on the tube sheet, and both ends of the heat exchange tubes are connected to the heads on both sides. Each heat exchange tube includes a spiral section and straight tube sections integrally formed on both sides of the spiral section. The spiral section is located inside the evaporating cylinder, and the straight tube sections are located inside the high-temperature and low-temperature preheating cylinders. Both the high-temperature and low-temperature preheating cylinders have water inlets at their lower parts. A heat source inlet is located at the lower part of the head near the high-temperature preheating cylinder, and a heat source outlet is located at the upper part of the head near the low-temperature preheating cylinder. A steam outlet is located at the upper part of the evaporating cylinder.

2. A preheating evaporator for solar thermal energy storage power generation according to claim 1, characterized in that, The upper diameter of the connecting cylinder is smaller than its lower diameter.

3. A preheating evaporator for solar thermal energy storage power generation according to claim 1, characterized in that, The upper part of the connecting cylinder is equipped with a demister for separating steam from water.

4. A preheating evaporator for solar thermal energy storage power generation according to claim 1, characterized in that, Both the high-temperature side preheating cylinder and the low-temperature side preheating cylinder are equipped with several baffles arranged alternately.

5. A preheating evaporator for solar thermal energy storage power generation according to claim 4, characterized in that, The spacing between the baffles inside the low-temperature side preheating cylinder is smaller than the spacing between the baffles inside the high-temperature side preheating cylinder.

6. A preheating evaporator for solar thermal energy storage power generation according to any one of claims 1-5, characterized in that, The length of the low-temperature side preheating cylinder is greater than that of the high-temperature side preheating cylinder, which is used to extend the heat exchange time of the heat exchange medium in the low-temperature side preheating cylinder.

7. A preheating evaporator for solar thermal energy storage power generation according to any one of claims 1-5, characterized in that, Each water inlet is equipped with a flow valve, and the opening degree of the flow valve at the water inlet on the low-temperature side preheating cylinder is smaller than that at the water inlet on the high-temperature side preheating cylinder.

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