Single well heat exchange system and control method

Abstract

The present application relates to a kind of single well heat exchange system and control method, belong to geothermal energy development technical field.The single well heat exchange system includes inner tube, outer tube and heat exchanger, outer tube is set in the outer tube, and the inner wall between outer tube and outer tube forms water inlet channel, the inside of inner tube forms water outlet channel, the top of water outlet channel is connected with one end of heat exchanger by pipeline, the top of water inlet channel is connected with the other end of heat exchanger by pipeline and circulating pump, and water in water inlet channel enters inner tube at the bottom of inner tube;The section of inner tube is square, and inner tube has four sides, and control cable through hole is arranged at the intersection of two sides.The present application utilizes the geothermal in well section, improves the utilization rate of middle layer geothermal, and increases the geothermal energy storage of deep layer.

Description

Technical Field

[0001] This invention belongs to the field of geothermal energy development technology, and in particular relates to a single-well heat exchange system and control method. Background Technology

[0002] The large-scale development and utilization of geothermal energy for heating has played an important role in providing clean winter heating and mitigating weather conditions in northern regions. The development and utilization of medium-deep geothermal energy mainly relies on the extraction of geothermal water as the traditional heat extraction method. Its applications include geothermal hot springs, mineral water development, hot spring therapy, and heat pump technology for heating. This heat extraction method is currently widely used both domestically and internationally. It is generally developed by drilling geothermal wells or re-perforating abandoned oil exploration wells to extract geothermal water. This heat extraction method is relatively mature. The amount of geothermal resources depends on the deep geothermal field and geological and hydrogeological conditions, and is greatly affected by regional geological conditions, exhibiting a significant characteristic of uneven resource distribution. When the well depth is deep, this method not only requires high pump power, resulting in significant electricity consumption, but also suffers from the problem of insufficient utilization of medium-deep geothermal energy. Summary of the Invention

[0003] The purpose of this invention is to provide a single-well heat exchange system and control method, which reduces the power of the circulating pump by adjusting the height difference of the circulating water, saves energy, makes reasonable use of the geothermal energy in the middle section of the well, improves the utilization rate of the middle geothermal layer, and increases the deep geothermal energy storage.

[0004] A single-well heat exchange system includes an inner pipe, an outer pipe, and a heat exchanger. The outer pipe is sleeved outside the inner pipe. A water inlet channel is formed between the outer wall of the inner pipe and the inner wall of the outer pipe. A water outlet channel is formed inside the inner pipe. The top of the water outlet channel is connected to one end of the heat exchanger through a pipe. The top of the water inlet channel is connected to the other end of the heat exchanger through a pipe and a circulation pump. Water from the water inlet channel enters the inner pipe at the bottom end.

[0005] The inner tube has a square cross-section and four sides. A control cable through hole is provided at the intersection of two sides.

[0006] Optionally, the direction in which the outer pipe extends in the well is Y-direction, and the direction perpendicular to the Y-direction is X-direction, where the Y-direction is the vertical extension of the outer pipe in the well.

[0007] Optionally, a movable plate is provided at the bottom end of the inner tube. One end of the movable plate is rotatably connected to the inner wall of the inner tube. When the working position is open, the movable plate is close to or parallel to the inner wall of the inner tube, allowing water to enter the inner tube from the bottom end. When the working position is closed, the movable plate is perpendicular to the inner wall of the inner tube, thus sealing the bottom end of the inner tube, preventing water from entering the inner tube from the bottom end. A controller located on the ground controls the opening and closing of the movable plate via a control cable, which passes through a control cable through-hole.

[0008] Optionally, a slot is provided on the side wall of the inner tube, and slide rails are provided on both sides of the slot. The slide plate is installed on the slide rails and covered by the slot, and the slide plate can slide along the slide rails.

[0009] After the slide plate slides a preset distance to one side of the slide rail, the slot is not covered, and the inner cylinder is connected to the outer cylinder through the slot; when the slide plate cover is placed on the slot, the slot is covered, and the inner cylinder cannot be connected to the outer cylinder through the slot.

[0010] Optionally, in the Y direction, the inner cylinder is provided with multiple sets of slots.

[0011] Optionally, each set of slots is located on one or more sides of the inner cylinder in the X direction.

[0012] Optionally, the bottom end of the inner tube is open and not closed.

[0013] Optionally, at least one set of mesh holes and a rotating plate are provided on the side wall of the inner tube. One end of the rotating plate is rotatably connected to the side wall of the inner tube. When the station is open, the rotating plate is close to the inner wall of the inner tube or parallel to the inner wall of the inner tube and closes the mesh holes. At this time, water cannot enter the inner tube from the mesh holes on the side wall of the inner tube. When the station is closed, the rotating plate is perpendicular to the inner wall of the inner tube, thereby closing the inner tube. At this time, water cannot pass through the rotating plate from the bottom end of the inner tube upwards. Water in the water inlet channel enters the inner tube from the open mesh holes.

[0014] Alternatively, a controller located on the ground can control the opening and closing of the rotating plate via a control cable.

[0015] A control method for a single-well heat exchange system includes the following steps:

[0016] In the initial state, the controller opens the movable plate and closes the slot. Water from the bottom of the inner pipe enters the inner pipe through the inlet channel. At this time, the controller records the water temperature at the top outlet of the outlet channel as the reference water temperature.

[0017] When the movable plate is closed, the controller opens a set of slots within the preset length range of the inner cylinder. Water from the inlet channel enters the inner pipe through the opened slots. The controller compares the percentage difference between the water temperature at the top outlet of the outlet channel and the reference water temperature. If the percentage difference is within the preset threshold, the current state is maintained.

[0018] If the percentage difference exceeds the preset threshold, the controller will open multiple sets of slots within the preset length range of the inner cylinder to increase geothermal exchange until the percentage difference is within the preset threshold.

[0019] A control method for a single-well heat exchange system includes the following steps:

[0020] S1. In the initial state, the controller puts the rotating plate in the open position to close the mesh holes and the opening. Water from the bottom of the inner pipe enters the inner pipe. At this time, the controller records the water temperature at the top outlet of the water outlet as the reference water temperature.

[0021] S2. The controller puts the rotating plate in the closed position, thereby opening a set of grid holes or openings within the preset length range of the inner cylinder. Water from the inlet channel enters the inner pipe through the opened grid holes or openings. The controller compares the percentage difference between the water temperature at the top outlet of the outlet channel and the reference water temperature. If the percentage difference is within the preset threshold, the current state is maintained. At this time, the height difference of the circulating water changes, which can reduce the power of the circulating pump, save energy, and make reasonable use of the geothermal energy in the middle section of the well, thus improving the utilization rate of the geothermal energy in the middle section.

[0022] The preset length range can be a range of 0-500 meters from the bottom of the inner cylinder, a range of 500-1000 meters from the bottom of the inner cylinder, or two ranges of 500-1000 meters or 1500-2500 meters from the bottom of the inner cylinder. This invention does not limit the range.

[0023] The preset threshold can be 4%-10%, and this invention does not limit it.

[0024] S3. If the percentage difference exceeds the preset threshold, the controller will switch the rotating plate in step S2 to the open position. The controller will sequentially traverse the other rotating plates within the preset length range of the inner cylinder to the closed position, thereby opening the corresponding mesh holes or openings. Water from the inlet channel enters the inner pipe from the opened mesh holes or openings. The controller compares the percentage difference between the water temperature at the top outlet of the outlet channel and the reference water temperature until the percentage difference is within the preset threshold, at which point the traversal steps will stop.

[0025] S4. If the percentage difference still exceeds the preset threshold after the traversal in step S3, the controller will put the rotating plate in the open position to close the mesh holes and openings. Water from the water inlet channel enters the inner pipe from the bottom and exchanges heat from the depth of the well.

[0026] Beneficial technical effects:

[0027] By adjusting the height difference of the circulating water, the power of the circulating pump was reduced, saving electricity consumption. Furthermore, the geothermal energy in the middle section of the well was utilized more effectively, improving the utilization rate of the middle layer geothermal energy and increasing the deep geothermal energy storage. Attached Figure Description

[0028] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0029] Figure 1 This is a diagram of a single-well heat exchange system according to an embodiment of the present invention.

[0030] Figure 2 This is a schematic diagram of the bottom water heat exchange circulation in an embodiment of the invention.

[0031] Figure 3 This is a schematic diagram of the inner tube cross-section in an embodiment of the invention.

[0032] Figure 4 This is a schematic diagram of the circulating water height difference adjustment process in an embodiment of the present invention.

[0033] Figure 5 This is a schematic diagram of the circulating water height difference adjustment process according to another embodiment of the present invention. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0035] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Example

[0036] like Figures 1 to 4 As shown, a single-well heat exchange system includes an inner pipe 1, an outer pipe 2, and a heat exchanger 3. The outer pipe 2 is sleeved outside the inner pipe 1, and a water inlet channel is formed between the outer wall of the inner pipe 1 and the inner wall of the outer pipe 2. A water outlet channel is formed inside the inner pipe 1. The top end of the water outlet channel is connected to one end of the heat exchanger 3 through a pipe, and the top end of the water inlet channel is connected to the other end of the heat exchanger 3 through a pipe and a circulation pump. Water from the water inlet channel enters the inner pipe 1 at the bottom end to achieve the circulation of water or other media.

[0037] Optionally, the outer pipe 2 extends in the well in the Y direction, and the direction perpendicular to the Y direction is the X direction; preferably, the Y direction is the vertical extension of the outer pipe 2 in the well.

[0038] In the X direction, the cross-section of the inner tube 1 is square, that is, the inner tube 1 is a square tube. The inner tube 1 has 4 sides, and a control cable through hole is provided at the intersection of 2 sides.

[0039] A movable plate 11 is provided at the bottom end of the inner tube 1. One end of the movable plate 11 is rotatably connected to the inner wall of the inner tube 1. When the working position is open, the movable plate 11 is close to the inner wall of the inner tube 1 or parallel to the inner wall of the inner tube 1. At this time, water can enter the interior of the inner tube 1 from the bottom end. When the working position is closed, the movable plate 11 is perpendicular to the inner wall of the inner tube 1, thereby closing the bottom end of the inner tube 1. At this time, water cannot enter the interior of the inner tube 1 from the bottom end. The controller located on the ground controls the opening and closing of the movable plate 11 through the control cable. It can be understood that the control cable is passed through the control cable through hole. Optionally, the controller is located in a control box (not shown) on the ground.

[0040] Preferably, the cross-section of the movable plate 11 in the X direction is square.

[0041] Optionally, in the X direction, the cross-sectional area of ​​the movable plate 11 is less than or equal to the cross-sectional area of ​​the inner tube 1.

[0042] Preferably, a slot 12 is provided on the side wall of the inner tube 1, and slide rails are provided on both sides of the slot 12. The slide plate 13 is installed on the slide rails and covers the slot 12, and the slide plate 13 can slide along the slide rails.

[0043] After the slide plate 13 slides a preset distance to one side of the slide rail, the slot 12 is not covered, and the inner cylinder 1 communicates with the outer cylinder 2 through the slot 12; when the slide plate 13 is placed on the slot 12, the slot 12 is covered, and the inner cylinder 1 cannot communicate with the outer cylinder 2 through the slot 12. The controller located on the ground controls the opening and closing of the slide plate 13 through the control cable. Understandably, the control cable is passed through the control cable through hole; optionally, the controller is located in a control box (not shown) on the ground.

[0044] Preferably, in the Y direction, the inner cylinder 1 is provided with multiple sets of slots 12. For example, if the length of the inner cylinder 1 is 3000 meters, a set of slots 12 is provided every 100 meters in the 2500-3000 meter range, that is, a set of slots 12 is provided at the 2500m, 2600m, 2700m, 2800m and 2900m positions; and in the 1500m-2500m range, a set of slots 12 is provided every 200 meters, that is, a set of slots 12 is provided at the 1st... A set of slots 12 is set at 500 meters, 1700 meters, 1900 meters, 2100 meters and 2300 meters; in the interval of 500 meters to 1500 meters, a set of slots 12 is set every 300 meters, that is, a set of slots 12 is set at 500 meters, 800 meters, 1100 meters and 1400 meters. That is, the distance between adjacent slots 12 is equal or unequal, or the distance between adjacent slots 12 is set according to arithmetic or proportional ratio.

[0045] Preferably, each set of slots 12 is provided on one or more sides of the inner cylinder 1 in the X direction, that is, the inner cylinder 1 has four sides. At each set length, such as the 2500m, 2600m, 2700m, 2800m and 2900m, slots 12 are provided on one, two, three or four sides of the inner cylinder 1. That is, at the set length, slots 12 are provided on one or more sides of the inner cylinder 1.

[0046] Optionally, the bottom end of the outer tube 2 is also provided with multiple hydraulic fracturing segmented fractures, into which thermally conductive adhesive can be injected.

[0047] Optionally, a cement protective layer is also provided on the outside of the outer pipe 2 to improve the support strength of the segmented fracture layer of the outer pipe 2.

[0048] A control method for a single-well heat exchange system includes the following steps:

[0049] In the initial state, the controller opens the movable plate 11 and closes the slot 12. Water from the bottom of the inner pipe 1 enters the inner pipe 1 through the inlet channel. At this time, the controller records the water temperature at the top outlet of the outlet channel as the reference water temperature.

[0050] When the movable plate 11 is closed, the controller opens a set of slots 12 within the preset length range of the inner cylinder 1. Water from the inlet channel enters the inner pipe 1 through the opened slots 12. The controller compares the percentage difference between the water temperature at the top outlet of the outlet channel and the reference water temperature. If the percentage difference is within the preset threshold, the current state is maintained. At this time, the height difference of the circulating water changes, which can reduce the power of the circulating pump, save energy, and make reasonable use of the geothermal energy in the middle section of the well, thereby improving the utilization rate of the geothermal energy in the middle section.

[0051] The preset length range can be a range of 0-500 meters from the bottom of the inner cylinder 1, a range of 500-1000 meters from the bottom of the inner cylinder 1, or two ranges of 500-1000 meters or 1500-2500 meters from the bottom of the inner cylinder 1. This invention does not limit the range; or the preset length range is located in the middle section of the well.

[0052] The preset threshold can be 2%-8%, and this invention does not limit it.

[0053] If the percentage difference exceeds the preset threshold, the controller will open multiple sets of slots 12 within the preset length range of the inner cylinder 1 to increase geothermal exchange until the percentage difference is within the preset threshold.

[0054] This embodiment adjusts the height difference of the circulating water, reduces the power of the circulating pump, saves energy, makes reasonable use of the geothermal energy in the middle section of the well, improves the utilization rate of the middle layer geothermal energy, and increases the deep geothermal energy storage. Example

[0055] This embodiment is an improvement based on Embodiment 1.

[0056] like Figure 5 As shown, in a single-well heat exchange system, the bottom end of the inner pipe 1 is open, that is, the bottom end of the inner pipe 1 is not equipped with a movable plate 11, which can be understood as the bottom end of the inner pipe 1 being unclosed.

[0057] Optionally, at least one set of mesh holes 15 and a rotating plate 14 are provided on the side wall of the inner tube 1. One end of the rotating plate is rotatably connected to the side wall of the inner tube 1. When the station is open, the rotating plate 14 is close to the inner wall of the inner tube 1 or parallel to the inner wall of the inner tube 1 and closes the mesh holes 15. At this time, water cannot enter the inner tube 1 from the mesh holes 15 on the side wall of the inner tube 1. When the station is closed, the rotating plate 14 is perpendicular to the inner wall of the inner tube 1, thereby closing the inner tube 1. At this time, water cannot pass through the rotating plate 14 from the bottom end of the inner tube 1. Water in the water inlet channel enters the inner tube 1 from the open mesh holes 15.

[0058] Optionally, at least one set of openings 16 and a rotating plate 14 are provided on the side wall of the inner tube 1. One end of the rotating plate is rotatably connected to the side wall of the inner tube 1. When the station is open, the rotating plate 14 is close to the inner wall of the inner tube 1 or parallel to the inner wall of the inner tube 1 and closes the openings 16. At this time, water cannot enter the inner tube 1 from the openings 16 on the side wall of the inner tube 1. When the station is closed, the rotating plate 14 is perpendicular to the inner wall of the inner tube 1, thereby closing the inner tube 1. At this time, water cannot pass through the rotating plate 14 from the bottom end of the inner tube 1. Water from the water inlet channel enters the inner tube 1 from the open openings 16.

[0059] Optionally, multiple sets of mesh holes 15 and openings 16 are arranged adjacently or at intervals, and each set of mesh holes 15 and openings 16 corresponds to a set of rotating plates 14. The controller located on the ground controls the opening and closing of the rotating plates 14 through control cables. Understandably, the control cables are passed through the control cable through holes; optionally, the controller is located in a control box (not shown) on the ground.

[0060] Preferably, the cross-section of the rotating plate 14 in the X direction is square.

[0061] Optionally, in the X direction, the cross-sectional area of ​​the rotating plate 14 is less than or equal to the cross-sectional area of ​​the inner tube 1.

[0062] A control method for a single-well heat exchange system includes the following steps:

[0063] S1. In the initial state, the controller puts the rotating plate 14 in the open position, thereby closing the mesh hole 15 and the opening 16. Water from the water inlet channel enters the inner pipe 1 from the bottom end. At this time, the controller records the water temperature at the top outlet of the water outlet channel as the reference water temperature.

[0064] S2. The controller puts the rotating plate 14 in the closed position, thereby opening a set of grid holes 15 or openings 16 within the preset length range of the inner cylinder 1. Water from the inlet channel enters the inner pipe 1 through the opened grid holes 15 or openings 16. The controller compares the percentage difference between the water temperature at the top outlet of the outlet channel and the reference water temperature. If the percentage difference is within the preset threshold, the current state is maintained. At this time, the height difference of the circulating water changes, which can reduce the power of the circulating pump, save energy, and make reasonable use of the geothermal energy in the middle section of the well, thus improving the utilization rate of the geothermal energy in the middle section.

[0065] The preset length range can be a range of 0-500 meters from the bottom of the inner cylinder 1, a range of 500-1000 meters from the bottom of the inner cylinder 1, or two ranges of 500-1000 meters or 1500-2500 meters from the bottom of the inner cylinder 1. This invention does not limit the range.

[0066] The preset threshold can be 4%-10%, and this invention does not limit it.

[0067] S3. If the percentage difference exceeds the preset threshold, the controller will switch the rotating plate 14 in step S2 to the open position. The controller will sequentially traverse the other rotating plates 14 within the preset length range of the inner cylinder 1 to the closed position, thereby opening the corresponding mesh hole 15 or opening 16. The water in the water inlet channel enters the inner pipe 1 from the opened mesh hole 15 or opening 16. The controller compares the percentage difference between the water temperature at the top outlet of the water outlet channel and the reference water temperature until the percentage difference is within the preset threshold and then stops the traversal step.

[0068] S4. If the percentage difference still exceeds the preset threshold after the traversal in step S3, the controller puts the rotating plate 14 in the open position to close the mesh hole 15 and the opening 16. The water in the water inlet channel enters the inner pipe 1 from the bottom end and exchanges heat from the depth of the well.

[0069] In this embodiment, adjusting the height difference of the circulating water only requires controlling the rotation of one set of rotating plates 14 each time. This reduces the number of operation steps, reduces the power of the circulating pump, saves energy, makes reasonable use of the geothermal energy in the middle section of the well, improves the utilization rate of the middle geothermal layer, and increases the deep geothermal energy storage.

[0070] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0071] It should be noted that the sequence numbers of the embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0072] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, and any combination of embodiments or solutions, are similarly included within the patent protection scope of the present invention.

Claims

1. A control method for a single-well heat exchange system, the single-well heat exchange system comprising an inner pipe, an outer pipe and a heat exchanger, the outer pipe being sleeved outside the inner pipe, a water inlet channel being formed between the outer wall of the inner pipe and the inner wall of the outer pipe, a water outlet channel being formed inside the inner pipe, the top end of the water outlet channel being connected to one end of the heat exchanger via a pipe, and the top end of the water inlet channel being connected to the other end of the heat exchanger via a pipe and a circulating pump, the water in the water inlet channel entering the inner pipe at the bottom end of the inner pipe; The inner tube has a square cross-section and four sides. A control cable through hole is provided at the intersection of two sides. Multiple sets of mesh holes, openings, and rotating plates are made on the side wall of the inner tube. One end of the rotating plate is rotatably connected to the side wall of the inner tube. When the station is open, the rotating plate is close to the inner wall of the inner tube or parallel to the inner wall of the inner tube and closes the mesh holes or openings. At this time, water cannot enter the inner tube from the mesh holes or openings on the side wall of the inner tube. When the station is closed, the rotating plate is perpendicular to the inner wall of the inner tube, thus closing the inner tube. At this time, water cannot pass through the rotating plate from the bottom end of the inner tube. Water in the water inlet channel enters the inner tube from the open mesh holes or openings. Multiple sets of grid holes and openings are spaced apart, and each set of grid holes and openings corresponds to a set of rotating plates; the controller located on the ground controls the opening and closing of the rotating plates through control cables; The method includes the following steps: S1. In the initial state, the controller puts the rotating plate in the open position to close the mesh holes and the opening. Water from the bottom of the inner pipe enters the inner pipe. At this time, the controller records the water temperature at the top outlet of the water outlet as the reference water temperature. S2. The controller puts the rotating plate in the closed position, thereby opening a set of mesh holes or openings within the preset length range of the inner cylinder. Water from the inlet channel enters the inner pipe through the opened mesh holes or openings. The controller compares the percentage difference between the water temperature at the top outlet of the outlet channel and the reference water temperature. If the percentage difference is within the preset threshold, the current state is maintained. S3. If the percentage difference exceeds the preset threshold, the controller will switch the rotating plate in step S2 to the open position. The controller will sequentially traverse to make other rotating plates in the preset length range of the inner cylinder in the closed position, thereby opening the corresponding mesh holes or openings. The controller compares the percentage difference between the water temperature at the top outlet of the water outlet channel and the reference water temperature until the percentage difference is within the preset threshold and then stops traversing the steps. S4. If the percentage difference still exceeds the preset threshold after the traversal in step S3, the controller will put the rotating plate in the open position to close the mesh holes and openings. Water from the water inlet channel enters the inner pipe from the bottom and exchanges heat from the depth of the well.

2. The control method for a single-well heat exchange system as described in claim 1, characterized in that, The preset length range is a distance of 0-500 meters, 500-1000 meters, or 1500-2500 meters from the bottom of the inner cylinder.

3. The control method for a single-well heat exchange system as described in claim 1, characterized in that, The preset threshold is 4%-10%.

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