Middle-deep geothermal well heat exchange device and method

Abstract

The invention belongs to the technical field of heat exchange equipment, and particularly relates to a medium-deep geothermal well heat exchange device and method.The medium-deep geothermal well heat exchange device comprises a heat exchange pipe, the heat exchange pipe is located in a geothermal well, and the heat exchange pipe is externally connected with heat collection equipment through a pipeline; the heat exchanger further comprises an outer wall cleaning mechanism, and the outer wall cleaning mechanism is used for cleaning the outer wall of the heat exchange tube, so that the heat conduction efficiency of the heat exchange tube is maintained. By arranging the outer wall cleaning mechanism, in the long-term use process of the heat exchange tube, cleaning balls adopting controllable telescopic structural bodies are put into a cleaning annular space, collision and friction are generated between the cleaning balls and the heat exchange tube by means of sedimentation of the cleaning balls in water, and then the heat exchange tube is cleaned by means of collision and friction. And the scale deposited on the surface of the heat exchange tube falls off, so that the heat exchange tube is prevented from being isolated from underground water by the scale, the heat conduction rate of the heat exchange tube is maintained, and the heat exchange effect on terrestrial heat is maintained.

Description

Technical Field

[0001] The present invention belongs to the technical field of heat exchange equipment, and in particular to a heat exchange device and method for a medium-deep geothermal well. Background Art

[0002] Geothermal energy, as a clean and renewable energy source, occupies an increasingly important position in the energy structure. my country is rich in geothermal resources. Reasonable development and utilization of geothermal resources can not only reduce dependence on fossil fuels, but also effectively reduce environmental pollution.

[0003] Traditional geothermal energy development is mostly concentrated on shallow geothermal resources, and the development and utilization technology of medium and deep geothermal resources is not mature enough. In the initial development, groundwater is usually extracted to extract medium and deep geothermal energy to the surface, and then the heat energy in the groundwater is collected through heat exchange. However, due to the high content of impurities in groundwater, the extracted groundwater not only needs to undergo multi-stage filtration, but also needs to prevent the slightly soluble substances in the groundwater from being deposited inside the heat exchanger, making the process implementation more difficult. In addition, during the extraction and recharge of groundwater resources, it is easy to cause pollution and waste of water resources.

[0004] In order to solve the above problems, various solutions have been proposed in the related art. Among them, the solution of directly extending the heat exchange equipment into the medium-deep geothermal well and directly exchanging heat with the groundwater without extracting groundwater has received a good response when implemented. For example, a medium-deep geothermal well heat exchange device and method disclosed in the related patent, application number: CN202411124228.1, in which the heat exchange tube is extended into the geothermal well, and then heat exchange is directly carried out in the deep layer of the geothermal well. At the same time, a mechanical mechanism is set up to clean the inner wall of the heat exchange tube to maintain the heat exchange effect. However, in actual application, it is found that due to the presence of slightly soluble scale in the groundwater, the scale in the groundwater is deposited on the outer wall of the heat exchange tube during a long period of heat exchange, resulting in a continuous decrease in the heat exchange efficiency of the heat exchange tube. Because the heat exchange tube extends too deep in the geothermal well, it is difficult to mechanically clean the outer wall of the heat exchange tube. Therefore, when this solution is implemented, there are also major disadvantages.

[0005] In view of this, the present invention proposes a medium-deep geothermal well heat exchange device and method to solve the above-mentioned technical problems. Summary of the invention

[0006] In order to make up for the deficiencies of the prior art and solve the above-mentioned technical problems, the present invention proposes a heat exchange device and method for a medium-deep geothermal well.

[0007] The technical solution adopted by the present invention to solve the technical problem is: a medium-deep geothermal well heat exchange device described in the present invention comprises a heat exchange pipe, the heat exchange pipe is located in the geothermal well, and the heat exchange pipe is connected to an external heat collection device through a pipeline;

[0008] It also includes an outer wall cleaning mechanism, which is used to clean the outer wall of the heat exchange tube to maintain the heat conduction efficiency of the heat exchange tube;

[0009] The outer wall cleaning mechanism comprises a cover shell, a cleaning ball and an intercepting mesh plate;

[0010] The cover is sleeved on the outside of the heat exchange tube, a clean annulus is formed between the cover and the heat exchange tube, and a floating annulus is formed between the cover and the inner wall of the geothermal well. The cover is a grid-like structure, and an opening is provided at the bottom of the cover;

[0011] The cleaning ball is a controllable telescopic structure. In the initial state, the density of the cleaning ball is greater than the density of water, and after being fully expanded, the density of the cleaning ball is less than the density of water. The cleaning ball enters the deep layer of the geothermal well from the cleaning annulus;

[0012] An interception mesh plate is fixedly installed at the bottom of the heat exchange tube. The mesh opening of the interception mesh plate is larger than the minimum diameter of the cleaning ball. The interception mesh plate is used to intercept the cleaning ball.

[0013] Preferably, fins are fixedly mounted on the heat exchange tubes, the fins are used to increase the contact area between the heat exchange tubes and groundwater, the fins are spiral structures, and the fins, the heat exchange tubes and the cover form spiral grooves.

[0014] Preferably, the cleaning ball comprises a telescopic shell, an expansion frame and an angle block;

[0015] The telescopic shell is made of elastic material and is a cavity-type structure;

[0016] The expansion frame is fixedly installed inside the telescopic shell. The expansion frame is composed of an electric telescopic rod, and the control circuit of the electric telescopic rod has a timing start and stop function. Evenly distributed corner blocks are fixedly installed on the telescopic shell, and the corner blocks are made of hard materials.

[0017] Preferably, the telescopic shell is made of a heat-insulating material, a heat-insulating plate is fixedly installed inside the telescopic shell, and the expansion frame is in contact with the telescopic shell through the heat-insulating plate.

[0018] Preferably, the heat insulation board corresponds to the corner edge block one by one, and the heat insulation board and the corner edge block are fixedly connected by bolts.

[0019] Preferably, it also includes an impact assembly, which is fixedly mounted on the housing and is used to drive the cleaning ball to move in the cleaning annulus;

[0020] The impact assembly includes a pressure pump, a connecting pipe and an impact pipe;

[0021] The pressure pump is installed outside the geothermal well, and a connecting pipe is fixedly installed at the output end of the pressure pump. The connecting pipe is fixedly installed on the cover shell, and the connecting pipe extends along the depth direction of the geothermal well. Evenly distributed impact pipes are fixedly installed on the connecting pipe, and the impact pipes are all inclined. The inclination direction of the impact pipes is the same as the inclination direction of the fins.

[0022] Preferably, the pressure pump is an air compressor, and a one-way valve is installed in the opening of the impact pipe.

[0023] Preferably, the cover shell is formed by splicing a plurality of arc-shaped plates, and the plurality of arc-shaped plates are elastically connected by connecting springs. The top of the cover shell is designed in a funnel shape, and a gravity ring is installed in the cleaning annulus. The inner diameter of the gravity ring is larger than the maximum outer diameter of the heat exchange tube and the fin. In the initial state, the gravity ring is suspended above the cleaning annulus.

[0024] Preferably, the cross section of the spiral groove is designed to be conical, and the diameter of the spiral groove gradually decreases as the distance from the heat exchange tube decreases.

[0025] A heat exchange method for a medium-deep geothermal well, the method comprising the following steps:

[0026] S1. Heat exchange: After the heat exchange device is installed in the deep layer of the geothermal well, the staff starts the heat collection device to control the circulation of the heat exchange medium in the heat collection device and the heat exchange pipe to collect the heat energy in the geothermal well;

[0027] S2. Impact: In a certain heat exchange cycle, a batch of cleaning balls at room temperature are poured into the cleaning annulus. Under the action of gravity, the cleaning balls roll down and impact along the spiral groove;

[0028] S3, impact: synchronously start the impact assembly, extract the outside air and pump it into the connecting pipe and the impact pipe, and finally spray it into the spiral groove, impacting the groundwater and cleaning balls in the spiral groove;

[0029] S4, recovery: the cleaning ball finally falls onto the intercepting mesh plate, and the time is counted during the descent. When the set time is reached, the expansion frame stretches, causing the volume and buoyancy of the cleaning ball to increase, and the cleaning ball floats up along the floating annulus;

[0030] S5, circulation: the cleaning balls that float to the surface of the geothermal well are recovered by the staff, cooled down, and poured into the cleaning annulus again, and the operation is repeated to complete the cleaning of the fins and the outer wall of the heat exchange tube.

[0031] The beneficial effects of the present invention are as follows:

[0032] 1. The heat exchange device and method for a medium-deep geothermal well described in the present invention, by providing an outer wall cleaning mechanism, during the long-term use of the heat exchange tube, by dropping a cleaning ball with a controllable telescopic structure into the cleaning annulus, utilizing the settling of the cleaning ball in the water, causing the cleaning ball to collide and rub against the heat exchange tube, and then utilizing the collision and friction to cause scale deposited on the surface of the heat exchange tube to fall off, thereby preventing the scale from isolating the heat exchange tube from groundwater, maintaining the thermal conductivity of the heat exchange tube, and further maintaining the heat exchange effect on the geothermal.

[0033] 2. The heat exchange device and method for a medium-deep geothermal well described in the present invention forms a spiral structure by surrounding fins, and cooperates with heat exchange tubes and a cover to form a spiral groove. When a cleaning ball is dropped into the cleaning annulus, the cleaning ball falls into the spiral groove under the action of gravity and moves downward along the spiral groove. Under the action of the spiral groove, the movement path of the cleaning ball is extended, and the cleaning ball is restricted by the spiral groove, so that the contact effect between the cleaning ball and the fins and heat exchange tubes is enhanced, thereby enhancing the effect of removing scale on the heat exchange tubes and fins during the descent of the cleaning ball. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The present invention will be further described below in conjunction with the accompanying drawings.

[0035] Figure 1 is a stereogram of the present invention;

[0036] Figure 2 It is a stereoscopic diagram of the assembly of the connecting pipe and the fins in the present invention;

[0037] Figure 3 is a schematic diagram of the installation of the present invention in a geothermal well;

[0038] Figure 4 It is a stereoscopic diagram of the assembly of the connecting pipe and the curved plate;

[0039] Figure 5 yes Figure 4 A partial enlarged view of the middle part;

[0040] Figure 6 It is a three-dimensional picture of a cleaning ball;

[0041] Figure 7 This is a diagram of the internal structure of the cleaning ball;

[0042] Figure 8 is a flow chart of the method of the present invention;

[0043] In the figure: 1. heat exchange tube; 11. intercepting mesh plate; 12. fin; 13. spiral groove; 2. cleaning ball; 21. telescopic shell; 22. expansion frame; 23. corner block; 24. insulation board; 25. pressure pump; 26. connecting pipe; 27. impact pipe; 3. cover shell; 31. arc plate; 32. connecting spring; 4. gravity ring. DETAILED DESCRIPTION

[0044] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0045] like Figures 1 to 7 As shown, a medium-deep geothermal well heat exchange device and method described in the present invention comprises a heat exchange tube 1, wherein the heat exchange tube 1 is located in the geothermal well, and the heat exchange tube 1 is connected to an external heat collection device through a pipeline;

[0046] It also includes an outer wall cleaning mechanism, which is used to clean the outer wall of the heat exchange tube 1, thereby maintaining the heat conduction efficiency of the heat exchange tube 1;

[0047] The outer wall cleaning mechanism comprises a cover shell 3, a cleaning ball 2 and an intercepting mesh plate 11;

[0048] The cover shell 3 is sleeved on the outside of the heat exchange tube 1, a clean annulus is formed between the cover shell 3 and the heat exchange tube 1, and a floating annulus is formed between the cover shell 3 and the inner wall of the geothermal well. The cover shell 3 is a grid-like structure, and the bottom of the cover shell 3 is open;

[0049] The cleaning ball 2 is a controllable telescopic structure. In the initial state, the density of the cleaning ball 2 is greater than the density of water. After being fully expanded, the density of the cleaning ball 2 is less than the density of water. The cleaning ball 2 enters the deep layer of the geothermal well from the cleaning annulus.

[0050] An interception mesh plate 11 is fixedly installed at the bottom of the heat exchange tube 1 . The mesh opening of the interception mesh plate 11 is larger than the minimum diameter of the cleaning ball 2 . The interception mesh plate 11 is used to intercept the cleaning ball 2 .

[0051] During a long period of heat exchange, the continuous exchange of heat energy will cause the groundwater temperature around the heat exchange tube 1 to change, thereby causing slightly soluble calcium ions, magnesium ions, etc. in the water to be deposited on the heat exchange tube 1 in the form of precipitation, thereby isolating the groundwater from the heat exchange tube 1. Since the thermal conductivity of the scale formed by the deposition is poor, the heat exchange effect between the groundwater and the heat exchange medium inside the heat exchange tube 1 becomes poor. In order to maintain the use of the heat exchange tube 1, the present invention provides an outer wall cleaning mechanism to clean the outer wall of the heat exchange tube 1, thereby preventing the scale from being continuously deposited, thereby enabling the heat exchange tube 1 to always be in direct contact with the groundwater, thereby maintaining the heat exchange between the heat exchange tube 1 and the groundwater.

[0052] Specifically, since the heat exchange tube 1 continues to extend into the medium-deep geothermal well, and its extension depth can reach several thousand meters, it is not suitable to use a more complex mechanical mechanism to clean the outer wall of the heat exchange tube 1. At the same time, since the heat exchange tube 1 is always in the groundwater, scale deposition occurs all the time, so the heat exchange tube 1 needs to be frequently cleaned. In order to reduce the difficulty of cleaning the heat exchange tube 1, in the present invention, when the heat exchange tube 1 is installed, a cover 3 is installed on the outside of the heat exchange tube 1. The cover 3 is composed of a grid-shaped structure. In other embodiments of the present invention, the cover 3 can also be composed of a structure with a through hole. The cover 3 is used to cover the heat exchange tube 1 and facilitate groundwater to penetrate the cover 3. At the same time, the bottom opening of the cover 3 is set. During the periodic cleaning process of the heat exchange tube 1, the staff puts a batch of cleaning balls 2 in a normal temperature state into the cleaning annulus formed by the cover 3 and the heat exchange tube 1. Since the density of the cleaning ball 2 is greater than the density of water when it is in the contracted state, the cleaning ball 2 moves downward along the cleaning annulus under the action of gravity. The cleaning ball 2 moves until it reaches the bottom of the heat exchange tube 1 and is intercepted by the interception mesh plate 11. During this process, expansion and friction occur between the cleaning ball 2 and the heat exchange tube 1, thereby causing the scale deposited on the heat exchange tube 1 to fall off. At the same time, during the sinking process, the cleaning ball 2 always exchanges heat with the groundwater, causing the temperature of the cleaning ball 2 to rise. Since the cleaning ball 2 is a controllable telescopic structure, as the temperature of the cleaning ball 2 rises, the volume of the cleaning ball 2 increases and the density decreases. Finally, the density of the cleaning ball 2 is less than the density of water. At this time, the cleaning ball 2 increases in volume, resulting in an increase in its buoyancy. In addition, its density is less than the density of water. Therefore, under the action of buoyancy, the cleaning ball 2 will continue to rise and be salvaged by the staff on the liquid surface for use in the next cleaning operation. During the continuous cleaning process, the scale on the surface of the heat exchange tube 1 is cleaned, and during the long heat exchange process, the deposition of scale on the heat exchange tube 1 can be effectively prevented by periodically performing cleaning operations, thereby maintaining the heat exchange efficiency of the heat exchange tube 1.

[0053] The present invention provides an outer wall cleaning mechanism. During the long-term use of the heat exchange tube 1, a cleaning ball 2 with a controllable telescopic structure is thrown into the cleaning annulus. The cleaning ball 2 is used to settle in the water, so that the cleaning ball 2 and the heat exchange tube 1 collide and rub. The collision and friction are then used to cause scale deposited on the surface of the heat exchange tube 1 to fall off, thereby preventing the scale from isolating the heat exchange tube 1 from groundwater, maintaining the heat conduction rate of the heat exchange tube 1, and maintaining the heat exchange effect on the ground heat.

[0054] As a preferred embodiment of the present invention, a fin 12 is fixedly mounted on the heat exchange tube 1 , and the fin 12 is used to increase the contact area between the heat exchange tube 1 and groundwater. The fin 12 is a spiral structure, and the fin 12 , the heat exchange tube 1 , and the cover 3 form a spiral groove 13 .

[0055] The provision of the fins 12, on the one hand, increases the contact area between the heat exchange tube 1 and the groundwater, thereby enhancing the heat exchange effect between the heat exchange tube 1 and the groundwater; on the other hand, the fins 12 form a spiral structure around the heat exchange tube 1 and cooperate with the heat exchange tube 1 and the cover 3 to form a spiral groove 13. When the cleaning ball 2 is dropped into the cleaning annulus, under the action of gravity, the cleaning ball 2 falls into the spiral groove 13 and moves downward along the spiral groove 13. Under the action of the spiral groove 13, the movement path of the cleaning ball 2 is extended, and the cleaning ball 2 is restricted by the spiral groove 13, so that the contact effect between the cleaning ball 2 and the fins 12 and the heat exchange tube 1 is enhanced, thereby enhancing the scale removal effect on the heat exchange tube 1 and the fins 12 during the descent of the cleaning ball 2.

[0056] As a preferred embodiment of the present invention, the cleaning ball 2 includes a telescopic shell 21, an expansion frame 22 and an angle block 23;

[0057] The telescopic housing 21 is made of elastic material and is a hollow structure.

[0058] The expansion frame 22 is fixedly installed inside the telescopic shell 21. The expansion frame 22 is composed of an electric telescopic rod, and the control circuit of the electric telescopic rod has a timing start and stop function. Evenly distributed corner edge blocks 23 are fixedly installed on the telescopic shell 21, and the corner edge blocks 23 are made of hard material.

[0059] In the present invention, an electric telescopic rod is used to form an expansion skeleton 22, and a timing circuit is added to the control circuit of the electric telescopic rod, so that the electric telescopic rod has a timing start and stop function, and a power supply is installed in the control circuit of the electric telescopic rod to provide power support for the extension and retraction of the electric telescopic rod. When the staff puts the cleaning ball 2, the staff first starts the timing circuit in the cleaning ball 2 manually or through an electromagnetic signal, and then puts the cleaning ball 2 into the cleaning annulus. As time goes by, the cleaning ball 2 eventually falls onto the intercepting mesh plate 11. As time goes by, when the time reaches a preset duration, the timing circuit controls the control circuit of the expansion skeleton 22 to be connected, thereby expanding the cleaning ball 2, resulting in a specific and stable volume expansion function of the cleaning ball 2, which is convenient for the use of the cleaning ball 2. The telescopic shell 21 made of elastic material and the corner block 23 made of hard material not only prevent the expansion skeleton 22 from being directly hit, but also isolate the external water, thereby extending the service life of the cleaning ball 2.

[0060] It should be noted that the sinking rate of the cleaning ball 2 in water mainly depends on the difference between its density and the density of water, and is also affected by factors such as temperature and the viscosity resistance of water. As the falling rate of the ball in water continues to increase, when the gravity of the ball and the resistance of the fluid to it are equal, the movement rate of the ball is its terminal rate. By calculating its terminal rate, the sinking rate of the cleaning ball 2 in water can be determined. For example, in the present invention, a cleaning ball 2 with an overall density close to 7.8 g / cm2 is used to carry out a sinking experiment in water, which confirms that the sinking terminal rate of the cleaning ball 2 is 1.34°. The rate is close to 10m / s. Therefore, in medium-deep geothermal wells, the sinking time of the cleaning ball 2 can be roughly calculated according to the extension depth of the heat exchange tube 1. In actual application, the staff can also use the cleaning ball 2 of the same volume and density to conduct a descent experiment. By monitoring the descending cleaning ball 2, the actual descent time of the cleaning ball 2 is measured, and then the preset value of the timing circuit in the cleaning ball 2 is adjusted. When the cleaning ball 2 is used in different geothermal wells, the expansion time of the expansion skeleton 22 can be flexibly adjusted, so that the movement of the cleaning ball 2 is more consistent with the process settings.

[0061] As a preferred embodiment of the present invention, the telescopic shell 21 is made of heat-insulating material, a heat-insulating plate 24 is fixedly installed inside the telescopic shell 21 , and the expansion frame 22 is in contact with the telescopic shell 21 through the heat-insulating plate 24 .

[0062] The heat insulation plates 24 correspond to the corner blocks 23 one by one, and the heat insulation plates 24 and the corner blocks 23 are fixedly connected by bolts.

[0063] The telescopic shell 21 is made of heat-insulating material, preferably heat-resistant silicone. At the same time, a heat insulation board 24 is arranged between the telescopic shell 21 and the expansion skeleton 22, so that the efficiency of temperature conduction to the expansion skeleton 22 is reduced during the lifting and lowering of the cleaning ball 2 in the groundwater, thereby avoiding the negative impact of high temperature on the control circuit and timing circuit of the expansion skeleton 22. At the same time, the heat insulation board 24 is connected to the corner block 23 by bolts, and then the expansion skeleton 22 is connected to the heat insulation board 24. During the lifting and lowering process of the cleaning ball 2, the extension and retraction of the expansion skeleton 22 will inevitably drive the movement of the corner block 23, so that the corner block 23 always protects the expansion skeleton 22 to avoid the expansion of the expansion skeleton 22 directly with external objects.

[0064] As a preferred embodiment of the present invention, it also includes an impact assembly, which is fixedly mounted on the housing 3 and is used to drive the cleaning ball 2 to move in the cleaning annulus;

[0065] The impact assembly includes a pressure pump 25, a connecting pipe 26 and an impact pipe 27;

[0066] The pressure pump 25 is installed outside the geothermal well, and a connecting pipe 26 is fixedly installed at the output end of the pressure pump 25. The connecting pipe 26 is fixedly installed on the cover 3. The connecting pipe 26 extends along the depth direction of the geothermal well. Evenly distributed impact pipes 27 are fixedly installed on the connecting pipe 26. The impact pipes 27 are all inclined, and the inclination direction of the impact pipes 27 is the same as the inclination direction of the fins 12.

[0067] The pressure pump 25 is an air compressor, and a one-way valve is installed in the opening of the impact pipe 27.

[0068] In order to further enhance the impact force of the cleaning ball 2 when it moves in the cleaning annulus, an impact assembly is provided in the present invention. After the cleaning ball 2 is dropped, the staff manually starts the pressure pump 25. The pressure pump 25 in the present invention is preferably an air compressor. The pressure pump 25 continuously extracts air when working, and pumps it into the connecting pipe 26 and the impact pipe 27 with a booster pump, and ejects it from the one-way valve at the end of the impact pipe 27. The ejected air column directly acts on the groundwater and indirectly acts on the cleaning ball 2, thereby increasing the groundwater flow rate and enhancing the impact force of the cleaning ball 2 moving in the cleaning annulus, thereby effectively enhancing the impact effect on the scale on the fin 12 and the outer wall of the heat exchange tube 1. At the same time, the setting of the one-way valve also prevents groundwater from entering the impact pipe 27 and the connecting pipe 26. Therefore, during long-term use, the probability of blockage of the impact pipe 27 and the connecting pipe 26 can be avoided.

[0069] As a preferred embodiment of the present invention, the cover shell 3 is spliced ​​by multiple arc plates 31, and the multiple arc plates 31 are elastically connected by connecting springs 32. The top of the cover shell 3 is designed in a funnel shape, and a gravity ring 4 is installed in the clean annulus. The inner diameter of the gravity ring 4 is larger than the maximum outer diameter of the heat exchange tube 1 and the fin 12. In the initial state, the gravity ring 4 is suspended above the clean annulus.

[0070] The cross section of the spiral groove 13 is designed to be conical, and as the distance from the heat exchange tube 1 decreases, the diameter of the spiral groove 13 gradually decreases.

[0071] In the process of the cleaning ball 2 moving downward along the spiral groove 13, there is a probability that the cleaning ball 2 is blocked and stays in the spiral groove 13. At this time, after the cleaning is completed, the staff releases the gravity ring 4 suspended on the cleaning annulus with the cooperation of the external winch, causing the gravity ring 4 to move downward to the cleaning annulus. Since the inner diameter of the gravity ring 4 is larger than the maximum outer diameter of the heat exchange tube 1 and the fin 12, and the cross-section of the spiral groove 13 is conical, as the gravity ring 4 descends, the multiple arc plates 31 constituting the cover 3 move away from each other, thereby increasing the width of the cleaning annulus, making it easier for the blocked cleaning ball 2 to fall downward, and then re-suspending the gravity ring 4. Under the elastic action of the connecting spring 32, the multiple arc plates 31 are re-assembled into the cover 3, which can continuously guide the movement of the cleaning ball 2 and filter the groundwater entering the cleaning annulus during long-term use to prevent large-volume debris from adhering to the heat exchange tube 1 or the fin 12.

[0072] like Figure 8 As shown, a heat exchange method for a medium-deep geothermal well comprises the following steps:

[0073] S1. Heat exchange: After the heat exchange device is installed in the deep layer of the geothermal well, the staff starts the heat collection device to control the circulation of the heat exchange medium in the heat collection device and the heat exchange pipe 1 to collect the heat energy in the geothermal well;

[0074] S2, impact: In a certain heat exchange cycle, a batch of cleaning balls 2 at room temperature are poured into the cleaning annulus. Under the action of gravity, the cleaning balls 2 roll downward along the spiral groove 13 and impact;

[0075] S3, impact: synchronously start the impact assembly, extract the outside air and pump it into the connecting pipe 26 and the impact pipe 27, and finally spray it into the spiral groove 13, impacting the groundwater in the spiral groove 13 and the cleaning ball 2;

[0076] S4, recovery: the cleaning ball 2 finally falls onto the intercepting mesh plate 11, and the time is counted during the descent. When the set time is reached, the expansion frame 22 is extended, causing the volume and buoyancy of the cleaning ball 2 to increase, and the cleaning ball 2 floats up along the floating annulus;

[0077] S5, circulation: the two cups of cleaning balls that float to the surface of the geothermal well are recovered by the staff, cooled, and poured into the cleaning annulus again, and the operation is repeated to complete the cleaning of the fins 12 and the outer wall of the heat exchange tube 1.

[0078] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A heat exchange device for a medium-deep geothermal well, comprising a heat exchange tube (1), wherein the heat exchange tube (1) is located in the geothermal well, and the heat exchange tube (1) is connected to an external heat collection device through a pipeline; Features: It also comprises an outer wall cleaning mechanism, which is used to clean the outer wall of the heat exchange tube (1) to maintain the heat conduction efficiency of the heat exchange tube (1); The outer wall cleaning mechanism comprises a cover shell (3), a cleaning ball (2) and an intercepting mesh plate (11); The cover shell (3) is sleeved on the outside of the heat exchange tube (1), a clean annulus is formed between the cover shell (3) and the heat exchange tube (1), and a floating annulus is formed between the cover shell (3) and the inner wall of the geothermal well. The cover shell (3) is a grid-like structure, and the bottom of the cover shell (3) is open; The cleaning ball (2) is a controllable telescopic structure. In the initial state, the density of the cleaning ball (2) is greater than the density of water. After being fully expanded, the density of the cleaning ball (2) is less than the density of water. The cleaning ball (2) enters the deep layer of the geothermal well from the cleaning annulus. An interception mesh plate (11) is fixedly mounted on the bottom of the heat exchange tube (1), the mesh opening of the interception mesh plate (11) being larger than the minimum diameter of the cleaning ball (2), and the interception mesh plate (11) is used to intercept the cleaning ball (2).

2. A medium-deep geothermal well heat exchange device according to claim 1, characterized in that: The heat exchange tube (1) is fixedly mounted with a fin (12), the fin (12) being used to increase the contact area between the heat exchange tube (1) and groundwater, the fin (12) being a spiral structure, the fin (12) and the heat exchange tube (1) and the cover (3) forming a spiral groove (13).

3. A medium-deep geothermal well heat exchange device according to claim 2, characterized in that: The cleaning ball (2) comprises a telescopic shell (21), an expansion frame (22) and an angle block (23); The telescopic housing (21) is made of elastic material and is a hollow structure. The expansion frame (22) is fixedly mounted inside the telescopic housing (21); the expansion frame (22) is composed of an electric telescopic rod, and the control circuit of the electric telescopic rod has a timing start and stop function; evenly distributed corner edge blocks (23) are fixedly mounted on the telescopic housing (21); the corner edge blocks (23) are made of hard material.

4. A medium-deep geothermal well heat exchange device according to claim 3, characterized in that: The telescopic shell (21) is made of a heat-insulating material, a heat-insulating plate (24) is fixedly installed inside the telescopic shell (21), and the expansion frame (22) is in contact with the telescopic shell (21) through the heat-insulating plate (24).

5. A medium-deep geothermal well heat exchange device according to claim 4, characterized in that: The heat insulation board (24) corresponds to the corner edge block (23) one by one, and the heat insulation board (24) and the corner edge block (23) are fixedly connected by bolts.

6. A medium-deep geothermal well heat exchange device according to claim 5, characterized in that: It also includes an impact assembly, which is fixedly mounted on the housing (3) and is used to drive the cleaning ball (2) to move in the cleaning annulus; The impact assembly comprises a pressure pump (25), a connecting pipe (26) and an impact pipe (27); The pressure pump (25) is installed outside the geothermal well. A connecting pipe (26) is fixedly installed at the output end of the pressure pump (25). The connecting pipe (26) is fixedly installed on the cover (3). The connecting pipe (26) extends along the depth direction of the geothermal well. Evenly distributed impact pipes (27) are fixedly installed on the connecting pipe (26). The impact pipes (27) are all inclined. The inclination direction of the impact pipes (27) is the same as the inclination direction of the fins (12).

7. A medium-deep geothermal well heat exchange device according to claim 6, characterized in that: The pressure pump (25) is an air compressor, and a one-way valve is installed in the opening of the impact pipe (27).

8. A medium-deep geothermal well heat exchange device according to claim 7, characterized in that: The cover shell (3) is formed by splicing a plurality of arc-shaped plates (31), and the plurality of arc-shaped plates (31) are elastically connected via connecting springs (32). The top of the cover shell (3) is designed to be funnel-shaped. A gravity ring (4) is installed in the clean annulus. The inner diameter of the gravity ring (4) is larger than the maximum outer diameter of the heat exchange tube (1) and the fin (12). In an initial state, the gravity ring (4) is suspended above the clean annulus.

9. A medium-deep geothermal well heat exchange device according to claim 8, characterized in that: The cross section of the spiral groove (13) is designed to be conical, and as the distance from the heat exchange tube (1) decreases, the diameter of the spiral groove (13) gradually decreases.

10. A heat exchange method for a medium-deep geothermal well, characterized in that: The method uses a medium-deep geothermal well heat exchange device as described in claim 9, and the method comprises the following steps: S1. Heat exchange: After the heat exchange device is installed in the deep layer of the geothermal well, the staff starts the heat collection device to control the circulation of the heat exchange medium in the heat collection device and the heat exchange pipe (1) to collect the heat energy in the geothermal well; S2, impact: In a certain heat exchange cycle, a batch of cleaning balls (2) at room temperature are poured into the cleaning annulus, and the cleaning balls (2) roll and impact downward along the spiral groove (13) under the action of gravity; S3, impact: synchronously start the impact assembly, extract the outside air and pump it into the connecting pipe (26) and the impact pipe (27), and finally spray it into the spiral groove (13), thereby impacting the groundwater in the spiral groove (13) and the cleaning ball (2); S4, recovery: the cleaning ball (2) finally falls onto the intercepting mesh plate (11), and the time is counted during the descent. When the set time is reached, the expansion frame (22) is extended, so that the volume and buoyancy of the cleaning ball (2) increase, and the cleaning ball (2) floats up along the floating annulus; S5, circulation: the cleaning balls (2) that float to the surface of the geothermal well are recovered by the staff, cooled, and poured into the cleaning annulus again, and the operation is repeated to complete the cleaning of the fins (12) and the outer wall of the heat exchange tube (1).

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