Supercritical boiler pipeline heat transfer strengthening device and method

Abstract

The invention discloses a supercritical boiler pipeline heat transfer strengthening device and method.The supercritical boiler pipeline heat transfer strengthening device comprises a conical part and a slip rope which are arranged in a boiler pipeline, the conical part is arranged in the flowing direction of supercritical liquid in the boiler pipeline, and the small end of the conical part faces the supercritical liquid; the slip rope is arranged in the axial direction of the boiler pipeline and penetrates through the conical part, the conical part is connected with the slip rope in a sliding mode, and the conical part can stop at the protruding position of the supercritical gas film on the inner wall of the boiler pipeline. The heat transfer strengthening device is adopted for heat transfer strengthening of the supercritical boiler pipeline. The device is simple in structure and low in cost, can reduce the thickness of a similar gas film on the wall surface of the pipeline at a fixed point and strengthen local heat transfer so as to ensure the operation safety of a heat exchange pipe of the boiler, adapts to the wide-parameter-range working condition operation of the supercritical boiler, does not cause mechanical damage to the pipeline of the boiler in the use process, and ensures the operation safety of the supercritical boiler.

Description

Technical Field

[0001] This invention relates to the field of boilers, and in particular to a device and method for enhancing heat transfer in supercritical boiler pipes. Background Technology

[0002] On the one hand, it is necessary to maximize the efficiency of fossil energy utilization. Traditional coal-fired power generating units use water as the working fluid, and the boiler outlet steam temperature is limited by the oxidation and corrosion resistance of the materials, making it difficult to further improve their power generation efficiency. Replacing water with inert working fluids such as supercritical carbon dioxide is expected to further improve the boiler outlet steam parameters and increase power generation efficiency by three to four percentage points. However, supercritical carbon dioxide has poor heat transfer performance, and wall temperature rises and heat transfer deterioration are prone to occur along the flow direction of the heating pipes. On the other hand, vigorously developing renewable energy sources such as solar and wind power is another path to support the dual carbon goals. However, renewable energy is volatile and intermittent, and large-scale grid connection will affect the security of the power system. Therefore, coal-fired power plants need to implement flexible peak shaving. When solar and wind power are operating at full capacity while user electricity demand is insufficient, coal-fired power plants will operate at extremely low loads, deviating significantly from their design conditions. The supercritical water in the economizer and water-cooled walls of existing boilers may also experience heat transfer deterioration, leading to local overheating of the pipe walls, resulting in production accidents such as pipe rupture and boiler shutdown.

[0003] like Figure 1 As shown, existing technology forms an internally threaded tube by machining threaded grooves 5 integrally within the boiler pipe 1 of a supercritical boiler. This enhances overall heat transfer by expanding the heating surface. During supercritical boiler operation, the supercritical liquid 2 moves centrally within the boiler pipe 1, and a supercritical gas film 3 covers the wall of the boiler pipe 1. Under certain conditions, the supercritical gas film 3 may locally bulge 4, leading to an increase in the boiler pipe wall temperature T. w A sudden rise occurs in the flow direction z, resulting in localized heat transfer deterioration. Even though the boiler pipe 1 is equipped with threaded grooves 5, the aforementioned localized heat transfer deterioration still exists. Supercritical boilers still have the possibility of localized overheating of the pipe wall, leading to pipe rupture and boiler shutdown. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this application provides a device and method for enhancing heat transfer in supercritical boiler pipelines, thereby solving the technical problems in existing technologies such as the easy deterioration of heat transfer in supercritical boilers, the high possibility of production accidents such as tube rupture and boiler shutdown.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] A supercritical boiler pipe heat transfer enhancement device includes a conical component and a sliding cable disposed inside the boiler pipe. The conical component is arranged along the direction of supercritical liquid flow inside the boiler pipe, with one end of the conical component facing the supercritical liquid. The bottom diameter of the conical component is smaller than the inner diameter of the boiler pipe. The sliding cable is arranged along the axial direction of the boiler pipe and passes through the conical component. The conical component and the sliding cable are slidably connected. The conical component can stop at the bulge of the supercritical gas film on the inner wall of the boiler pipe.

[0007] In one embodiment, both the tapered member and the sliding cable are arranged along the central axis of the boiler pipe.

[0008] In one embodiment, the tapered member is formed by rolling and welding a sheet of metal.

[0009] In one embodiment, the tapered component is made of one of the following materials: iron, cobalt, nickel, or iron(II,III) oxide.

[0010] In one embodiment, the small end and bottom surface of the tapered member are provided with sliding holes at the central axis of the tapered member, and the sliding cable passes through the sliding holes at the small end and bottom surface of the tapered member.

[0011] In one embodiment, both the upper and lower ends of the boiler pipe are fixed with reinforcing bars, and the upper and lower ends of the sliding cable are welded and fixed to the reinforcing bars at the upper and lower ends of the boiler pipe, respectively.

[0012] In one embodiment, the inner wall of the boiler pipe is provided with threaded grooves.

[0013] In one embodiment, the sliding and stopping of the tapered member is controlled by a magnet located outside the boiler pipe.

[0014] In one embodiment, the magnet is fixed to the bottom end of the rope, and the motor controls the bottom end of the rope to move up and down. The magnet is positioned on the boiler pipe that is offset from the center line of the distance between adjacent boiler pipes and close to the tapered part controlled by the magnet.

[0015] This application also provides a method for enhancing heat transfer in supercritical boiler pipes, using the aforementioned heat transfer enhancement device, comprising the following steps: when the presence of a supercritical gas film protrusion on the inner wall of a certain boiler pipe in a supercritical boiler is detected, a conical component inside the boiler pipe is moved so that the conical component stops at the protrusion, and the stopping position of the conical component inside different boiler pipes is controlled according to the position of the protrusion on the inner wall of different boiler pipes in the supercritical boiler.

[0016] Compared with the prior art, this application has at least the following beneficial effects:

[0017] The supercritical boiler pipe heat transfer enhancement device of this invention has a simple structure and low cost. It only requires placing a conical component inside the boiler pipe, resulting in limited pressure drop within the pipe. The position of the conical component can be dynamically adjusted, precisely reducing the thickness of the gas film on the pipe wall, thus enhancing local heat transfer and ensuring the safe operation of the boiler heat exchange tubes. The heat transfer enhancement method in this application is precise and adaptable to a wide range of operating conditions for supercritical boilers. This invention uses a motor-driven magnet installed outside the pipe to non-contactly control the conical insert made of metal via a magnetic field. Controlling the conical insert does not cause mechanical damage to the boiler pipe, making it simple and reliable. The magnet is installed at a position offset from the center of the distance between adjacent heat exchange tubes, with one magnet controlling the position of the conical insert within one pipe. In each pipe of a boiler installed in parallel, the conical insert can be controlled at different positions according to the heat transfer conditions within the pipe, optimizing the overall heat transfer performance of the boiler. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the boiler piping in a supercritical boiler in the existing technology;

[0019] Figure 2 This is a schematic cross-sectional view of the boiler piping in the supercritical boiler in this application embodiment;

[0020] Figure 3 This is a schematic diagram of the boiler piping structure in the supercritical boiler in this application embodiment.

[0021] Reference numerals: 1. Boiler pipe; 2. Supercritical liquid; 3. Supercritical gas film; 4. Rise; 5. Threaded groove; 6. Conical part; 7. Sliding hole; 8. Sliding cable; 9. Reinforcing bar; 10. Magnet; 11. Rope; 12. Motor. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is described below with reference to specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0023] The terminology used in this disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The singular forms “a,” “the,” and “the” as used in this disclosure and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any and all possible combinations of one or more of the associated listed items.

[0024] It should be understood that although the terms first, second, third, etc., may be used in this disclosure to describe various information, such information should not be limited to these terms and should not be construed as indicating or implying relative importance. These terms are used only to distinguish information of the same type from one another. For example, without departing from the scope of this disclosure, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to determination."

[0025] In the description of this invention, unless otherwise specified and limited, it should be noted that the terms "installation", "connection" and "linking" should be interpreted broadly. For example, they can refer to mechanical connection or internal connection between two components. They can be direct connection or indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0026] To better understand the technical solution of the present invention, the present invention will be described in detail below with reference to the accompanying drawings.

[0027] This embodiment provides a heat transfer enhancement device for supercritical boiler pipelines, as shown in the attached figure. Figure 2 As shown, it includes a conical component 6 and a sliding cable 8 installed inside the boiler pipe 1. The conical component 6 is arranged along the direction of the flow of the supercritical liquid 2 inside the boiler pipe 1. One end of the small end of the conical component 6 faces the supercritical liquid 2. The bottom diameter of the conical component 6 is smaller than the inner diameter of the boiler pipe 1. The sliding cable 8 is arranged along the length of the boiler pipe 1. The sliding cable 8 passes through the conical component 6. The conical component 6 and the sliding cable 8 are slidably connected. The conical component 6 can stop at the bulge 4 of the supercritical gas film 3 on the inner wall of the boiler pipe 1.

[0028] In this embodiment, both the conical component 6 and the sliding cable 8 are arranged along the central axis of the boiler pipe 1. The conical component 6 is made of rolled and welded metal sheet, and the material of the conical component 6 is one of iron, cobalt, nickel, or iron(III) oxide. The small end and the bottom surface of the conical component 6 are provided with sliding holes 7 at the central axis of the conical component 6, and the sliding cable 8 passes through the sliding holes on the small end and the bottom surface of the conical component 6.

[0029] To ensure the stability of the conical component 6's movement, steel bars 9 are fixed to both the upper and lower ends of the boiler pipe 1. The upper and lower ends of the sliding cable 8 are welded and fixed to the steel bars 9 at the upper and lower ends of the boiler pipe 1, respectively. Threaded grooves 5 are provided on the inner wall of the boiler pipe 1 to further enhance heat exchange.

[0030] The sliding and stopping of the conical component 6 is controlled by a magnet 10, which is located outside the boiler pipe 1. The magnet 10 is fixed to the bottom end of the rope 11, and the motor 12 controls the up-and-down movement of the bottom end of the rope 11. To prevent the magnet 10 from affecting the movement of the conical component 6 inside adjacent boiler pipes 1, such as... Figure 3 As shown, the magnet 10 is disposed on the boiler pipe 1 that is offset from the center line of the spacing between adjacent boiler pipes 1 and close to the tapered member 6 controlled by the magnet 10.

[0031] This embodiment provides a method for enhancing heat transfer in supercritical boiler pipes, using the aforementioned supercritical boiler pipe heat transfer enhancement device, including the following steps: when the presence of a supercritical gas film 3 bulge 4 on the inner wall of a certain boiler pipe 1 in a supercritical boiler is detected, the conical member 6 inside the boiler pipe 1 is moved so that the conical member 6 stops at the bulge 4, and the stopping position of the conical member 6 inside different boiler pipes 1 is controlled according to the position of the bulge 4 on the inner wall of different boiler pipes 1 in the supercritical boiler.

[0032] When the conical component 6 stops at the protrusion 4, the supercritical liquid 2 flows through the boiler pipe 1, and the flow direction changes from along the z-axis to along the generatrix of the conical component 6. Therefore, a component is generated in the radius r direction of the boiler pipe 1. The supercritical liquid 2 impacts the original local protrusion 4 on the supercritical gas film 3, suppressing it into a smooth supercritical gas film 3. The boiler pipe wall temperature Tw rises slowly in the flow direction z, thus solving the phenomenon of local heat transfer deterioration.

[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of the invention or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in the present invention.

Claims

1. A supercritical boiler pipeline heat transfer enhancement device, characterized in that, The device includes a conical component and a sliding cable installed inside the boiler pipe. The conical component is positioned along the direction of supercritical liquid flow within the boiler pipe, with one end of the conical component facing the supercritical liquid. The bottom diameter of the conical component is smaller than the inner diameter of the boiler pipe. The sliding cable is positioned along the length of the boiler pipe and passes through the conical component. The conical component and the sliding cable are slidably connected, and the conical component can rest on the bulge of the supercritical gas film on the inner wall of the boiler pipe.

2. The heat transfer enhancement device according to claim 1, characterized in that, Both the tapered component and the sliding cable are installed along the central axis of the boiler pipe.

3. The heat transfer enhancement device according to claim 1, characterized in that, The tapered component is made of rolled and welded sheet metal.

4. The heat transfer enhancement device according to claim 3, characterized in that, The tapered component is made of one of the following materials: iron, cobalt, nickel, or iron(II,III) oxide.

5. The heat transfer enhancement device according to claim 1, characterized in that, The tapered component has sliding holes at its small end and bottom surface at the central axis of the tapered component, and the sliding cable passes through the sliding holes at the small end and bottom surface of the tapered component.

6. The heat transfer enhancement device according to claim 1, characterized in that, The upper and lower ends of the boiler pipe are fixed with steel bars, and the upper and lower ends of the sliding cable are welded and fixed to the steel bars at the upper and lower ends of the boiler pipe, respectively.

7. The heat-strengthening device according to claim 1, characterized in that, The inner wall of the boiler pipe is provided with threaded grooves.

8. The heat-strengthening device according to claim 1, characterized in that, The sliding and stopping of the tapered component is controlled by a magnet, which is located on the outside of the boiler pipe.

9. The heat-strengthening device according to claim 8, characterized in that, The magnet is fixed to the bottom end of the rope, and the motor controls the bottom end of the rope to move up and down. The magnet is set on the boiler pipe that is offset from the center line of the distance between adjacent boiler pipes and close to the tapered part controlled by the magnet.

10. A method for enhancing heat transfer in supercritical boiler pipes, characterized in that, The heat transfer enhancement device as described in any one of claims 1-9 includes the following steps: when the presence of a supercritical gas film protrusion on the inner wall of a certain boiler pipe in a supercritical boiler is detected, the conical component inside the boiler pipe is moved so that the conical component stops at the protrusion, and the stopping position of the conical component in different boiler pipes is controlled according to the position of the protrusion on the inner wall of different boiler pipes in the supercritical boiler.

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