Central pipe

Abstract

The utility model provides a central pipe, relates to the pipeline technical field of thermal energy engineering technology, the central pipe includes central pipe body and protruding structure, the protruding structure extends along the length direction of central pipe body and is fixed on the inside wall of central pipe body. Water flow can form local vortexes and turbulent flows at the two ends, in the length direction of the central pipe, of the protruding structures respectively, so that the contact time of the central pipe and a geothermal well is prolonged by properly reducing the flow speed of fluid in the cavity structure of the central pipe, the heat transfer efficiency of the geothermal well to the fluid in the central pipe is correspondingly improved, and the heat transfer efficiency is improved. And the utilization efficiency of geothermal resources is further improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to the pipeline technical field of heat energy engineering technology, specifically, relate to a center pipe. BACKGROUND

[0002] In the field of geothermal energy development, deep geothermal exploitation is one of the important ways, wherein, deep geothermal exploitation is mainly through geothermal well and uses center pipe to transport geothermal fluid to the ground surface to realize the utilization of geothermal energy, and in this process, the center pipe is one of the key components, mainly used for transporting geothermal fluid, and the inner wall structure of the center pipe directly affects the flow characteristics of the fluid, the heat transfer efficiency and the service life of the pipeline.

[0003] In the related art, the inner wall structure of the center pipe adopts a smooth inner wall, which can reduce the friction resistance of the fluid to a certain extent, but the heat transfer efficiency is low due to the short contact time of the high flow rate with the geothermal well, thereby reducing the utilization efficiency of geothermal resources. UTILITY MODEL CONTENT

[0004] The problem solved by the utility model is how to improve the heat transfer efficiency of the fluid in the center pipe of the geothermal well.

[0005] To solve the above problems, the utility model provides a center pipe, which comprises a center pipe body and a protruding structure, the protruding structure extends along the length direction of the center pipe body, and is fixed to the inner side wall of the center pipe body.

[0006] Optionally, the protruding structure comprises a plurality of convex edges, and the plurality of convex edges are arranged at intervals along the length direction of the center pipe body.

[0007] Optionally, the convex edge is a closed annular protrusion.

[0008] Optionally, the convex edge is an arc-shaped protrusion provided with a notch, and the notches of the adjacent two convex edges are arranged staggeredly.

[0009] Optionally, the arc-shaped protrusion is arranged in parallel or at an angle with the diameter surface of the center pipe body.

[0010] Optionally, the convex edge is a spiral protrusion.

[0011] Optionally, the end portion of the convex edge away from the center pipe body is in the shape of U, trapezoid, arc or triangle in the cross section along the radial direction of the center pipe body.

[0012] Optionally, the protruding structure is formed on the inner side wall of the center pipe body by using a laser cladding process, an electroplating process or a thermal spraying process.

[0013] Optionally, the central tube body has an inner wall structure, the inner wall structure comprises a structure layer and a smooth layer, and the smooth layer is arranged on the inner side wall of the structure layer.

[0014] Optionally, the smooth layer is formed by electroplating or laser melting.

[0015] The central tube has the following advantages:

[0016] The central tube mainly comprises a central tube body and a protruding structure, wherein the central tube body can be provided with a cavity structure penetrating in the axial direction, and the protruding structure can be arranged on the inner side wall of the central tube body in the length direction of the central tube body. During the upward conveying of the fluid in the cavity structure of the central tube, the water flow can form local vortexes and turbulent flows at both ends (for example, the upper end and the lower end) of the protruding structure in the length direction of the central tube, so as to appropriately reduce the flow rate of the fluid in the cavity of the central tube, increase the contact time with the geothermal well, and correspondingly improve the heat transfer efficiency of the geothermal well to the fluid in the central tube, thereby improving the utilization efficiency of the geothermal resources. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 Fig. 1 is a schematic view of the axial side structure of the central tube of an embodiment of the present application;

[0018] Figure 2 Fig. 2 is a schematic view of the cross-sectional structure of the central tube of an embodiment of the present application;

[0019] Figure 3 Fig. 3 is a schematic view of the axial side structure of the central tube of an embodiment of the present application;

[0020] Figure 4 Fig. 4 is a schematic view of the axial side structure of the central tube of an embodiment of the present application;

[0021] Figure 5 Fig. 5 is a schematic view of the axial side structure of the central tube of an embodiment of the present application;

[0022] Figure 6 Fig. 6 is a schematic view of the vertical cross-sectional local structure of the annular protrusion of an embodiment of the present application;

[0023] Figure 7 Fig. 7 is a schematic view of the vertical cross-sectional local structure of the annular protrusion of an embodiment of the present application;

[0024] Figure 8 Fig. 8 is a schematic view of the vertical cross-sectional local structure of the annular protrusion of an embodiment of the present application;

[0025] Figure 9 Fig. 9 is a schematic view of the vertical cross-sectional local structure of the annular protrusion of an embodiment of the present application;

[0026] Figure 10 It is the cross section local structure schematic view of the inner wall structure of the center pipe body of the embodiment of the utility model.

[0027] Mark explanation:

[0028] 1 - center pipe body; 11 - inner wall structure; 111 - structure layer; 112 - smooth layer; 2 - convex structure; 21 - convex edge; 211 - notch. DETAILED DESCRIPTION

[0029] In order to make the above-mentioned purpose, features and advantages of the utility model more obvious and easy to understand, the specific embodiments of the utility model are described in detail below with reference to the drawings. Although some embodiments of the utility model are shown in the drawings, it should be understood that the utility model can be realized in various forms, and should not be interpreted as being limited to the embodiments described herein, on the contrary, these embodiments are provided to more thoroughly and completely understand the utility model. It should be understood that the drawings and embodiments of the utility model are only for illustrative purposes, and are not used to limit the protection scope of the utility model.

[0030] The Z axis in the drawing represents the vertical direction, that is, the up-down position, and the positive direction of the Z axis represents the upper side, and the negative direction of the Z axis represents the lower side. The X axis in the drawing represents the horizontal direction and is designated as the left-right position, and the positive direction of the X axis represents the right side, and the negative direction of the X axis represents the left side. It should be noted that the meanings of the aforementioned Z axis and X axis are only for the convenience of describing the utility model and simplifying the description, and are not indicative or suggestive of the devices or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the utility model.

[0031] The term "comprising" and its variants used herein are open-ended, that is, "including but not limited to"; the term "based on" is "at least partially based on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; the term "optionally" means "optional embodiment". Related definitions of other terms will be given in the following description. It should be noted that the "first", "second", etc. concepts mentioned in the utility model are only used to distinguish different devices, modules or units, and are not used to limit the functions performed by these devices, modules or units in order or mutual dependence.

[0032] It should be noted that the modification of "one" or "multiple" mentioned in the utility model is illustrative and not limiting, and those skilled in the art should understand that, unless otherwise explicitly indicated in the context, it should be understood as "one or more".

[0033] To solve the problems in the above related technologies, the embodiment provides a central pipe.

[0034] As shown in Figure 1 and Figure 2 The utility model embodiment provides a kind of central pipe, including central pipe body 1 and protruding structure 2, the protruding structure 2 extends along the length direction of the central pipe body 1, and is fixed to the inner side wall of the central pipe body 1.

[0035] Specifically, the central pipe is inserted into the geothermal well, so that the central pipe is vertically arranged, in this case, the length direction of the central pipe body 1 refers to the extension direction of the central pipe body 1, which can also refer to the axial direction of the central pipe body 1, which can be parallel to the Z-axis direction in the coordinate system. Figure 1

[0036] The protruding structure 2 can be fixed to the inner side wall of the central pipe body 1, for example, the protruding structure 2 is arranged protruding from the inner side wall of the central pipe body 1.

[0037] In the embodiment, the central pipe mainly includes the central pipe body 1 and the protruding structure 2, wherein the central pipe body 1 can be provided with a cavity structure penetrating in the axial direction, and the protruding structure 2 can be arranged on the inner side wall of the central pipe body 1 in the length direction of the central pipe body 1. During the upward conveying of the fluid in the cavity structure of the central pipe, the water flow can form vortexes and turbulent flows at both ends (e.g., upper end and lower end) of the protruding structure 2 in the length direction of the central pipe, so as to appropriately reduce the flow rate of the fluid in the cavity structure of the central pipe, increase the contact time with the geothermal well, and accordingly improve the heat transfer efficiency of the geothermal well to the fluid in the central pipe, thereby improving the utilization efficiency of the geothermal resources. Furthermore, the generation of scale can be reduced at the lower end of the protruding structure 2 due to the reduced flow rate, the corrosion resistance and wear resistance of the inner side wall of the central pipe body are enhanced, and the service life of the central pipe is prolonged.

[0038] During the flow of the fluid in the cavity structure of the central pipe body 1 from the lower end to the upper end through the protruding structure 2, the fluid is hindered and changes direction due to the protruding structure 2, the flow rate of the fluid is reduced and accumulates to form a vortex at the lower end of the protruding structure 2. When the fluid passes over the protruding structure 2, the fluid becomes unstable due to the increased flow rate and shear force, thereby generating turbulent flow at the upper end of the protruding structure 2.

[0039] Optionally, as shown in Figures 1 to 5 The protruding structure 2 includes a plurality of protruding ribs 21, and the plurality of protruding ribs 21 are arranged at intervals in the length direction of the central pipe body 1.

[0040] Specifically, the plurality of protruding ribs 21 are arranged at intervals in the length direction of the central pipe body 1, that is, there is a certain interval between adjacent two protruding ribs 21 in the length direction of the central pipe body 1.​

[0041] In the optional embodiment, the plurality of ribs 21 are arranged along the length direction of the central pipe body 1 on the inner side wall of the central pipe body 1, so that the fluid in the cavity structure of the central pipe body 1 is transported from bottom to top, and passes through the plurality of ribs 21 arranged along the length direction of the central pipe body 1. Since the fluid generates vortex and turbulence when flowing through each rib 21, the fluid is correspondingly decelerated and accelerated multiple times at the plurality of ribs 21. In other words, the fluid exchanges heat with the geothermal well when flowing through each rib 21, effectively improving the heat transfer efficiency of the geothermal well to the fluid in the central pipe and further improving the utilization efficiency of geothermal resources.

[0042] Optionally, in combination with Figure 1 As shown in the figure, the rib 21 is a closed annular protrusion.

[0043] Specifically, the rib 21 is a closed annular protrusion, which means that each annular protrusion has no gap.

[0044] The diameter and thickness of the annular protrusion rib 21 can be related to the diameter, wall thickness and length of the central pipe, which are not limited here.

[0045] In the optional embodiment, each rib 21 is a closed annular protrusion, so that the fluid in the cavity structure of the central pipe passes through the closed annular protrusion, the fluid near the inner side wall of the central pipe body 1 fully contacts the closed annular protrusion, the flow rate of the fluid flowing through the closed annular protrusion is basically the same in the circumferential direction, the circumferential flow of the fluid flowing through the protrusion structure 2 is uniform, and the heat transfer efficiency of the geothermal well is uniform, further improving the utilization efficiency of geothermal resources.

[0046] Optionally, in combination with Figure 3 and Figure 4 As shown in the figure, the rib 21 is an arc-shaped protrusion provided with a gap 211, and the gaps 211 of the adjacent two ribs 21 are arranged staggered.

[0047] Specifically, the gaps 211 of the adjacent two ribs 21 arranged along the length direction of the central pipe are arranged staggered, that is, the gaps 211 of the adjacent two ribs 21 do not intersect or coincide on the vertical line.

[0048] In this optional embodiment, since each ridge 21 is an arc-shaped protrusion provided with a gap 211, and the gaps 211 of two adjacent ridges 21 are staggered, so that when the fluid flows through the corresponding ridge 21, the flow rate of the fluid flowing through the gap 211 of the ridge 21 will be greater than the flow rate of the fluid flowing through the lower end of the corresponding arc-shaped protrusion, and then the fluid will flow through another adjacent ridge 21 during the process of continuing to flow upward. Since the gaps 211 of the two adjacent ridges 21 are staggered, the flow rates of the fluid flowing through the arc-shaped protrusion and the gap 211 of one ridge 21 and the flow rates of the fluid flowing through the arc-shaped protrusion and the gap 211 of another ridge 21 are different, which ensures that the fluid can conduct heat with the geothermal well at each ridge 21, and ensures the utilization efficiency of geothermal resources.

[0049] Optionally, the arc-shaped protrusion is parallel to or at an angle to the diameter plane of the central pipe body 1.

[0050] Specifically, in the case of Figure 3 , the plurality of arc-shaped protrusions arranged along the length direction of the central pipe are parallel to the diameter plane of the central pipe body 1.

[0051] The diameter plane of the central pipe body 1 refers to the plane formed by a plurality of diameter lines of the central pipe body 1 in the same plane.

[0052] In the case of Figure 4 , the plurality of arc-shaped protrusions arranged along the length direction of the central pipe are at an angle to the diameter plane of the central pipe body 1; for example, in the case of Figure 4 , the inclination directions of the first and second arc-shaped protrusions and the third and fourth arc-shaped protrusions relative to the diameter plane of the central pipe body 1 can be different from top to bottom.

[0053] Optionally, in combination with Figure 5 , the ridge 21 is a spiral protrusion.

[0054] Specifically, Figure 5 , the spiral protrusion can be understood as a spiral fin provided on the inner side wall of the central pipe body 1.

[0055] In this optional embodiment, by providing a spiral protrusion on the inner side wall of the central pipe body 1, the spiral protrusion can not only guide the fluid provided in the central pipe body 1 to form rotation, generate centrifugal force, and carry particles in the fluid away from the inner side wall of the central pipe, thereby reducing the possibility of deposition and blockage, but also induce the fluid to generate secondary flow, i.e. rotational flow along the circumferential direction of the inner side wall of the central pipe body 1, which will increase the mixing of the fluid, thereby enhancing the heat conduction efficiency of the geothermal well to the fluid in the central pipe.

[0056] Optionally, Figures 6 to 9As shown, the cross-sectional shape of the end of the protrusion 21 away from the central pipe body 1 in the radial direction of the central pipe body 1 is U-shaped, trapezoidal, arc-shaped, or triangular.

[0057] Specifically, the cross-section of the central pipe body 1 in the radial direction can be parallel to the plane formed by the X-axis and the Z-axis of the coordinate system. Figure 2

[0058] The cross-sectional shape of the end of the protrusion 21 away from the central pipe body 1 in the radial direction of the central pipe body 1 can be U-shaped (see FIG. 2A), trapezoidal (see FIG. 2B), arc-shaped (see FIG. 2C), or triangular (see FIG. 2D). Figure 6 As shown, the cross-sectional shape of the end of the protrusion 21 away from the central pipe body 1 in the radial direction of the central pipe body 1 is U-shaped, trapezoidal, arc-shaped, or triangular.

[0059] As shown, the cross-sectional shape of the end of the protrusion 21 away from the central pipe body 1 in the radial direction of the central pipe body 1 is U-shaped, trapezoidal, arc-shaped, or triangular. Figure 7 As shown, the cross-sectional shape of the end of the protrusion 21 away from the central pipe body 1 in the radial direction of the central pipe body 1 is U-shaped, trapezoidal, arc-shaped, or triangular.

[0060] As shown, the cross-sectional shape of the end of the protrusion 21 away from the central pipe body 1 in the radial direction of the central pipe body 1 is U-shaped, trapezoidal, arc-shaped, or triangular. Figure 8 As shown, the cross-sectional shape of the end of the protrusion 21 away from the central pipe body 1 in the radial direction of the central pipe body 1 is U-shaped, trapezoidal, arc-shaped, or triangular.

[0061] As shown, the cross-sectional shape of the end of the protrusion 21 away from the central pipe body 1 in the radial direction of the central pipe body 1 is U-shaped, trapezoidal, arc-shaped, or triangular. Figure 9 As shown, the cross-sectional shape of the end of the protrusion 21 away from the central pipe body 1 in the radial direction of the central pipe body 1 is U-shaped, trapezoidal, arc-shaped, or triangular.

[0062] Alternatively, the protrusion structure 2 is formed on the inner side wall of the central pipe body 1 by a laser cladding process, an electroplating process, or a thermal spraying process.

[0063] Specifically, the protrusion structure 2 can be formed on the inner side wall of the central pipe body 1 by a laser cladding process according to a set route track, wherein the laser cladding process refers to a process method of adding external material to the molten pool formed on the inner side wall of the substrate (e.g., the central pipe body 1) after laser irradiation by synchronous or preset material, and making them co-solidify to form a cladding layer.

[0064] ​The raised structure 2 can be formed on the inner side wall of the central pipe body 1 by using an electroplating process according to a set route track, wherein the electroplating process refers to a process of plating a thin layer of other metal or alloy on the surface of certain metal by using electrolysis principle, which is a process of attaching a metal film on the surface of a metal or other material part by using electrolysis.

[0065] The raised structure 2 can be formed on the inner side wall of the central pipe body 1 by using a thermal spraying process according to a set route track, wherein the thermal spraying process refers to a surface processing method of spraying a molten spraying material on the surface of a cleaned and roughened part (the central pipe body 1) by high-speed airflow to form a spraying layer.

[0066] In this optional embodiment, the raised structure 2 is formed on the inner side wall of the central pipe body 1 by using a laser cladding process, an electroplating process or a thermal spraying process, so that the raised structure 2 and the central pipe body 1 form an integrated structure, thereby improving the structural stability of the central pipe formed by the raised structure 2 and the central pipe body 1. In addition, the raised structure 2 formed on the inner side wall of the central pipe body 1 by using the laser cladding process, the electroplating process or the thermal spraying process can also ensure the accuracy and consistency of the raised structure 2 on the inner wall of the central pipe, improve the manufacturing efficiency and reduce the production cost.

[0067] Optionally, in combination with Figure 10 As shown in the figure, the central pipe body 1 has an inner wall structure 11, which includes a structure layer 111 and a smooth layer 112, and the smooth layer 112 is arranged on the inner side wall of the structure layer 111.

[0068] Specifically, the smooth layer 112 is arranged on the inner side wall of the structure layer 111, in other words, the structure layer 111 can be arranged on the outer side of the smooth layer 112.

[0069] The structure layer 111 can be made of metal materials such as stainless steel, copper and aluminum, or non-metallic materials such as ceramics and graphite, so as to ensure that the central pipe not only has sufficient strength, but also has high thermal conductivity, high corrosion resistance and high wear resistance, which can prevent the central pipe from being broken and leaking, ensure the safety and reliability of geothermal exploitation, and prolong the service life of the central pipe.

[0070] The smooth layer 112 can ensure that the inner wall of the central pipe body 1 has a certain smoothness, which not only effectively prevents the fluid from scaling on the inner side wall of the cavity structure of the central pipe body 1, reduces the difficulty and cost of maintenance and cleaning, but also reduces the friction resistance of the fluid, thereby improving the utilization efficiency of geothermal resources.

[0071] Optionally, the smooth layer 112 is formed by using an electroplating process or a laser melting process.

[0072] Specifically, the smooth layer 112 can adopt micro-nano structure, for example, the smooth layer 112 can be processed in the inner wall of the structural layer 111 by means of laser cladding, electroplating and the like to form micro-nano structure, so that the inner wall structure 11 of the central pipe with the structural layer 111 and the smooth layer 112 has better anti-fouling performance, can prolong the service life and reduce the maintenance cost.

[0073] In addition, the inner wall structure 11 of the central pipe can be cleaned and maintained once every 6 months, so as to timely remove the scale and impurities in the central pipe, ensure the cleaning and smoothness of the inner wall structure 11 of the central pipe and prolong the service life of the central pipe. The cleaning mode can adopt chemical cleaning, for example, a 10% nitric acid solution is used, and the cleaning time is 2 hours; of course, other existing physical cleaning or mechanical cleaning modes can also be adopted, which are not limited here.

[0074] Although the utility model discloses as above, the protection scope of the utility model is not only limited to this. The person skilled in the art can make various changes and modifications without departing from the spirit and scope of the utility model, and these changes and modifications will fall into the protection scope of the utility model.

Claims

1. A center tube characterized in that, The center tube body (1) and the convex structure (2) extend along the length direction of the center tube body (1) and are fixed to the inner side wall of the center tube body (1); The center tube body (1) has an inner wall structure (11) comprising a structure layer (111) and a smooth layer (112), and the smooth layer (112) is arranged on the inner side wall of the structure layer (111).

2. The center tube of claim 1, wherein, The convex structure (2) comprises a plurality of convex edges (21) arranged at intervals along the length direction of the center tube body (1).

3. The center tube of claim 2, wherein, The convex edge (21) is a closed loop annular convex.

4. The center tube of claim 2, wherein, The convex edge (21) is an arc-shaped convex provided with a notch (211), and the notches (211) of adjacent two convex edges (21) are arranged staggered.

5. The center tube of claim 4, wherein, The arc-shaped convex is parallel or at an angle to the diameter plane of the center tube body (1).

6. The center tube of claim 2, wherein, The convex edge (21) is a spiral convex.

7. The center tube of claim 2, wherein, The convex edge (21) is away from the end of the center tube body (1) in the radial direction of the center tube body (1) is a U-shaped, trapezoidal, arc-shaped or triangular cross-sectional shape.

8. The center tube according to any one of claims 1 to 7, characterized in that The convex structure (2) is formed by laser cladding process, electroplating process or thermal spraying process on the inner side wall of the center tube body (1).

9. The center tube of claim 1, wherein, The smooth layer (112) is formed by electroplating process or laser melting process.

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