A casing heat exchanger for medium-deep geothermal holes

Abstract

The present invention belongs to the technical field of heat exchange components, and in particular, relates to a casing heat exchanger for medium-deep geothermal holes, comprising a plurality of connecting outer casings, a bottom outer casing and an installation box installed on the ground, wherein two adjacent connecting outer casings are fixedly connected, the bottom outer casing is fixedly connected to the bottom of the connecting outer casing on the same side, and a controller is fixedly installed inside the installation box. The present invention exchanges heat through a casing structure, has a large contact area for heat exchange, and has high efficiency. It is suitable for geothermal wells with small apertures and large depths, and can perform targeted heat extraction with good heat extraction effect. It can also automatically control heat exchange according to the formation temperature to avoid heat energy waste and large fluctuations in formation temperature. It can also automatically clear blockages to reduce the impact of blockages on heat exchange efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of heat exchange components, and in particular relates to a casing heat exchanger for medium-deep geothermal holes. Background Art

[0002] In the medium-deep geothermal bore heat exchange system, casing plays an extremely critical role. As the depth of geothermal development increases, the formation environment becomes complex and changeable. The casing can protect the well wall, prevent it from collapsing under high temperature, high pressure and complex geological effects, and ensure the integrity of the well.

[0003] At present, there are generally two heat exchange methods for geothermal wells. One is to extract underground hot water, exchange heat with the groundwater and then return it to the formation. The other is to allow a separate heat exchange medium to enter the geothermal well and exchange heat with the groundwater. Since this heat exchange method does not require the extraction of groundwater, it can reduce the impact on the stability of the formation, so it is relatively widely used. As one of the important components, the casing needs to have a good heat exchange efficiency to meet the heat extraction efficiency of the geothermal well. For example, the patent announcement number CN117760248A discloses a heat exchange casing for a medium-deep geothermal well and its processing technology;

[0004] Although the heat exchange sleeve disclosed in the above patent can increase the contact area between the inner wall and the heat exchange medium, and increase the contact area between the outer wall and the formation, thereby improving the heat exchange efficiency, for deep wells with a formation depth of up to 2,000 meters, since the temperatures between different formations may be different, during the heat exchange process, the heat exchanged by the heat exchange medium from the bottom of the deep well may lose temperature during the process of upstream discharge back to the ground. That is, when the temperature of the returning heat exchange medium is higher than the temperature of the formation, the heat in the heat exchange medium will flow to the low temperature area, which will not only cause partial waste of heat energy, but also may cause temperature fluctuations in different formations, affecting the stability of the formation structure. Summary of the invention

[0005] The object of the present invention is to provide a casing heat exchanger for medium-deep geothermal holes in view of the above problems.

[0006] To achieve the above object, the present invention adopts the following technical scheme: a casing heat exchanger for medium-deep geothermal holes, comprising a plurality of connecting outer casings, a bottom outer casing and an installation box installed on the ground, wherein two adjacent connecting outer casings are fixedly connected, the bottom outer casing is fixedly connected to the bottom of the connecting outer casing on the same side, a controller is fixedly installed inside the installation box, and further comprising:

[0007] A plurality of inner sleeves are arranged on the inner side of the corresponding connecting outer sleeve and the bottom outer sleeve, and the upper and lower sides of the outer wall of each inner sleeve are fixedly sleeved with a connecting ring, and the connecting outer sleeve and the bottom outer sleeve are fixedly connected to the connecting ring on the same side;

[0008] Multiple groups of sealing spacers are installed between the corresponding inner sleeve and the connecting outer sleeve, and two sealing spacers in the same group separate the inner sleeve and the connecting outer sleeve on the same side to form an air inlet cavity and an air outlet cavity. The bottom outer sleeve is enclosed with the inner sleeve through two connecting rings on the same side to form an annular cavity. Each of the air inlet cavities is installed with an air inlet component connected to the annular cavity, and each of the air outlet cavities is installed with an air outlet component connected to the annular cavity.

[0009] A plurality of detection switching units are installed on the outer side wall of the corresponding connecting outer sleeve, and the controller controls the operation of the air outlet component according to the electrical signal output by each detection switching unit.

[0010] Preferably, the air intake assembly includes multiple groups of ventilation inlet pipes and gaseous medium inlet pipes arranged on the ground, the two ventilation inlet pipes in the same group are respectively arranged on the upper and lower sides of the corresponding air intake cavity, each of the ventilation inlet pipes passes through the connecting ring on the same side, the two adjacent ventilation inlet pipes are butted against each other, the upper cavity wall of the annular cavity is fixedly inserted with a tail end air inlet pipe, and the tail end air inlet pipe is butted against the ventilation inlet pipe on the same side, the gaseous medium inlet pipe is fixedly installed on the top of the connecting outer sleeve on the same side, and the gaseous medium inlet pipe is communicated with the ventilation inlet pipe on the same side.

[0011] Preferably, the air outlet assembly includes a return end tube fixedly plugged into the upper cavity wall of the annular cavity, the lower cavity wall of each of the air outlet cavities is fixedly plugged with a ventilation outlet pipe, the tube wall of each of the ventilation outlet pipes is installed with a shunt pipe, and the shunt pipe is connected with the air outlet cavity on the same side, the upper cavity wall of each of the air outlet cavities is fixedly plugged with a transition pipe, the interior of each of the transition pipes and each of the shunt pipes is installed with a normally open solenoid valve, the tube end of the ventilation outlet pipe is fixedly connected with an insulation pipe, and the insulation pipe is connected to the transition pipe, the interior of the insulation pipe is installed with a normally closed solenoid valve, the normally open solenoid valve and the normally closed solenoid valve are both electrically connected to a controller, each of the transition pipes is connected to the ventilation outlet pipe in the adjacent connecting outer sleeve, and the tube end of the transition pipe away from the bottom outer sleeve is fixedly connected with a tail end air outlet pipe.

[0012] Preferably, each of the detection switching units includes an installation groove opened on the outer side wall of the connecting outer sleeve, and the groove opening of the installation groove is fixedly encapsulated with a heat conduction plate, and the interior of each of the installation grooves is fixedly installed with an internal temperature detector, and the temperature measuring end of each internal temperature detector is in contact with the side wall of the heat conduction plate on the same side, and the controller controls the corresponding normally closed solenoid valve and normally open solenoid valve to energize and work according to the electrical signal output by each internal temperature detector.

[0013] Preferably, each of the connecting rings is provided with an annular water cavity inside, and the tube walls of the bottom outer sleeve and each connecting outer sleeve and the side walls of the annular water cavity on the same side are jointly provided with multiple groups of water holes, and the multiple groups of water holes on the same side are evenly distributed in a circular shape about the axis of the inner sleeve.

[0014] Preferably, an external temperature detector is fixedly connected to the wall of the tail end air outlet pipe, an integrated component is installed inside the installation box, each of the internal temperature detectors is electrically connected to the corresponding integrated component through a controller, and each of the annular water passage chambers and the tail end air outlet pipe is jointly installed with a clearing component.

[0015] Preferably, the integrated component includes a plurality of indicator lights fixedly mounted on the inner wall of the installation box, the controller controls the brightness of each indicator light according to the electrical signal output by each internal temperature detector, an insulating seat is fixedly mounted on the inner wall of the installation box on the side opposite to each indicator light, and a photosensitive resistor is fixedly mounted on the side wall of the insulating seat, the light emitted by each of the indicator lights is irradiated to the photosensitive surface of the photosensitive resistor, two electromagnetic push rods are fixedly mounted on the inner wall of the installation box, the telescopic ends of the two electromagnetic push rods are both mounted with insulating blocks, a conductive strip is fixedly mounted on the end of one of the insulating blocks, and a conductive column is fixedly mounted on the end of the other insulating block, the conductive column is in sliding contact with the side wall of the conductive strip, the controller controls the corresponding electromagnetic push rod to work according to the electrical signal output by the external temperature detector, the photosensitive resistor is electrically connected to the corresponding electromagnetic push rod through the controller, and when the conductive strip is not in contact with the conductive column, the controller controls its own timing module to start timing.

[0016] Preferably, the clearing component is provided with a plurality of air holes on the upper cavity wall of each annular cavity, a first electrically-controlled valve is installed inside each of the air holes, a second electrically-controlled valve is installed inside the tail end air outlet pipe, an air pressure detector is fixedly connected to the pipe wall of the tail end air outlet pipe, and the pressure measuring end of the air pressure detector is arranged inside the tail end air outlet pipe, and the first electrically-controlled valve, the second electrically-controlled valve and the air pressure detector are all electrically connected to the controller.

[0017] Compared with the existing technology, the advantages of a casing heat exchanger for medium-deep geothermal holes are:

[0018] 1. Through the cooperation of the connecting outer sleeve, bottom outer sleeve, installation box, controller, inner sleeve, connecting ring, sealing spacer, air inlet chamber, air outlet chamber, annular chamber, air inlet assembly and air outlet assembly, heat is exchanged with the geothermal well through the sleeve structure. The contact area between the heat exchange medium and the sleeve structure is large and the heat exchange efficiency is high. It is suitable for use in geothermal wells with small apertures and large depths. Secondly, heat can be extracted from the formation as a whole or from certain formations. It has high flexibility in use and good heat extraction effect.

[0019] 2. Through the detection switching unit, the heat exchange medium can be automatically prevented from exchanging heat with the formation based on the temperature of each formation. On the one hand, it can avoid the phenomenon of heat energy being fed back to the formation and causing heat energy waste. On the other hand, it can avoid the phenomenon of excessive fluctuation of formation temperature caused by the mutual influence of different formation temperatures.

[0020] 3. Through the cooperation of the annular water cavity and the water holes, the geothermal water and the casing structure can be facilitated to have deep contact heat exchange, thereby improving the heat exchange effect. Secondly, with the external temperature detector, integration component and clearing component, the clearing work of each water hole and annular water cavity can be automatically started based on the heat exchange difference, so as to avoid blockage affecting the heat exchange efficiency as much as possible. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of a casing heat exchanger for medium-deep geothermal holes provided by the present invention;

[0022] Figure 2 It is a schematic diagram of the internal structure of an installation box of a casing heat exchanger for a mid-deep geothermal hole provided by the present invention;

[0023] Figure 3 It is a schematic diagram of the top view of the air inlet cavity and the air outlet cavity of a casing heat exchanger for a mid-deep geothermal hole provided by the present invention;

[0024] Figure 4 It is a schematic diagram of the side view structure of the topmost connected outer casing of a casing heat exchanger for a mid-deep geothermal hole provided by the present invention;

[0025] Figure 5 It is a schematic diagram of a side view of the connection structure of a connecting outer casing and a bottom outer casing of a casing heat exchanger for a mid-deep geothermal hole provided by the present invention;

[0026] Figure 6 The present invention provides a casing heat exchanger for medium-deep geothermal holes. Figure 5 A magnified view of the structure of part A;

[0027] Figure 7 It is a schematic cross-sectional structural diagram of a bottom outer casing of a casing heat exchanger for a mid-deep geothermal hole provided by the present invention;

[0028] Figure 8 It is a schematic cross-sectional structure diagram of the topmost connecting outer casing of a casing heat exchanger for a mid-deep geothermal hole provided by the present invention;

[0029] Fig. 9 The present invention provides a casing heat exchanger for medium-deep geothermal holes. Figure 8 A magnified view of the structure of part B;

[0030] Fig.10 It is a schematic diagram of the connection structure of a vent outlet pipe, a shunt pipe, a transition pipe and a thermal insulation pipe of a casing heat exchanger for a mid-deep geothermal hole provided by the present invention;

[0031] Fig.11 The present invention provides a casing heat exchanger for medium-deep geothermal holes. Figure 2 The structure of the C part is enlarged;

[0032] Fig.12 It is a three-dimensional structural schematic diagram of a connecting ring of a casing heat exchanger for medium-deep geothermal holes provided by the present invention.

[0033] In the figure: 1 connecting outer sleeve, 2 bottom outer sleeve, 3 installation box, 4 controller, 5 inner sleeve, 6 connecting ring, 7 sealing spacer, 8 air inlet cavity, 9 air outlet cavity, 10 annular cavity, 11 air inlet assembly, 111 ventilation inlet pipe, 112 gas medium inlet pipe, 113 tail air inlet pipe, 12 air outlet assembly, 121 return end pipe, 122 ventilation outlet pipe, 123 shunt pipe, 124 transition pipe, 125 normally open solenoid valve, 126 insulation pipe, 127 normally closed solenoid valve, 128 tail End outlet pipe, 13 detection switching unit, 131 installation groove, 132 heat conduction plate, 133 internal temperature detector, 14 annular water cavity, 15 water hole, 16 external temperature detector, 17 integration component, 171 indicator light, 172 insulating seat, 173 photosensitive resistor, 174 electromagnetic push rod, 175 insulating block, 176 conductive strip, 177 conductive column, 18 clearing component, 181 air hole, 182 first electric control valve, 183 second electric control valve, 184 air pressure detector. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0035] like Figure 1-Figure 12As shown, a casing heat exchanger for a medium-deep geothermal hole includes a plurality of connecting outer casings 1, a bottom outer casing 2 and an installation box 3 installed on the ground, wherein two adjacent connecting outer casings 1 are fixedly connected, the bottom outer casing 2 is fixedly connected to the bottom of the connecting outer casing 1 on the same side, a controller 4 is fixedly installed inside the installation box 3, and further includes: a plurality of inner casings 5, wherein the plurality of inner casings 5 ​​are all arranged on the inner sides of the corresponding connecting outer casings 1 and the bottom outer casing 2, and the upper and lower sides of the outer wall of each inner casing 5 are fixedly sleeved with a connecting Ring 6, and the connecting outer sleeve 1 and the bottom outer sleeve 2 are fixedly connected to the connecting ring 6 on the same side, multiple groups of sealing strips 7 are installed between the corresponding inner sleeve 5 and the connecting outer sleeve 1, and the two sealing strips 7 in the same group separate the inner sleeve 5 and the connecting outer sleeve 1 on the same side to form an air inlet cavity 8 and an air outlet cavity 9, the bottom outer sleeve 2 is enclosed by the inner sleeve 5 through the two connecting rings 6 on the same side to form an annular cavity 10, and each air inlet cavity 8 is jointly installed with an air inlet component 11 connected to the annular cavity 10, and the air inlet component 11 The invention comprises a plurality of groups of ventilation inlet pipes 111 and gaseous medium inlet pipes 112 arranged on the ground. The two ventilation inlet pipes 111 of the same group are arranged on the upper and lower sides of the corresponding air inlet cavity 8, respectively. Each ventilation inlet pipe 111 passes through the connecting ring 6 on the same side. The two adjacent ventilation inlet pipes 111 are butted against each other. The upper cavity wall of the annular cavity 10 is fixedly plugged with a tail end air inlet pipe 113, and the tail end air inlet pipe 113 is butted against the ventilation inlet pipe 111 on the same side. The gaseous medium inlet pipe 112 is fixedly installed on the top of the connecting outer sleeve 1 on the same side, and the gaseous medium inlet pipe 112 is fixedly installed on the top of the connecting outer sleeve 1 on the same side. The medium inlet pipe 112 is connected to the ventilation inlet pipe 111 on the same side. An air pressure valve is arranged on the upper side of each air inlet cavity 8 (except the top air inlet cavity 8), the tail end air inlet pipe 113 and each transition pipe 124. The gaseous medium will flow downward only after the air pressure reaches a certain pressure, so that the air pressure inside each air inlet cavity 8 and the air outlet cavity 9 is higher than the normal pressure, which can be beneficial to the heat exchange of the gaseous medium, and can support the connecting outer casing 1 from the inside, thereby improving the supporting stability of the connecting outer casing 1 on the well wall.

[0036] Each outlet cavity 9 is commonly equipped with an outlet assembly 12 connected to the annular cavity 10, and the outlet assembly 12 includes a return end pipe 121 fixedly plugged into the upper cavity wall of the annular cavity 10, and the lower cavity wall of each outlet cavity 9 is fixedly plugged with a ventilation outlet pipe 122, and the wall of each ventilation outlet pipe 122 is installed with a shunt pipe 123, and the shunt pipe 123 is connected to the outlet cavity 9 on the same side, and the upper cavity wall of each outlet cavity 9 is fixedly plugged with a transition pipe 124, and the interior of each transition pipe 124 and each shunt pipe 123 is fixedly plugged into the upper cavity wall of each outlet cavity 9. A normally open solenoid valve 125 is installed in each of them, and the end of the ventilation outlet pipe 122 is fixedly connected to an insulation pipe 126, and the insulation pipe 126 is connected to the transition pipe 124. A normally closed solenoid valve 127 is installed inside the insulation pipe 126. The normally open solenoid valve 125 and the normally closed solenoid valve 127 are both electrically connected to the controller 4. Each transition pipe 124 is connected to the ventilation outlet pipe 122 in the adjacent connecting outer sleeve 1, and the end of the transition pipe 124 away from the bottom outer sleeve 2 is fixedly connected to a tail outlet pipe 128.

[0037] Multiple detection switching units 13 are installed on the outer side wall of the corresponding connecting outer sleeve 1. The controller 4 controls the operation of the air outlet component 12 according to the electrical signal output by each detection switching unit 13. Each detection switching unit 13 includes a mounting groove 131 opened on the outer side wall of the connecting outer sleeve 1, and the groove of the mounting groove 131 is fixedly encapsulated with a heat conducting plate 132. An internal temperature detector 133 is fixedly installed inside each mounting groove 131, and the temperature measuring end of each internal temperature detector 133 is in contact with the side wall of the heat conducting plate 132 on the same side. The controller 4 controls the corresponding normally closed solenoid valve 127 and the normally open solenoid valve 125 to energize and operate according to the electrical signal output by each internal temperature detector 133.

[0038] An annular water passage cavity 14 is provided inside each connecting ring 6, and multiple groups of water holes 15 are provided on the tube walls of the bottom outer sleeve 2 and each connecting outer sleeve 1 and the side wall of the annular water passage cavity 14 on the same side. The multiple groups of water holes 15 on the same side are evenly distributed in a circular shape about the axis of the inner sleeve 5, and the aperture of the water hole 15 at one end away from the inner sleeve 5 is smaller than the aperture at the other end.

[0039] An external temperature detector 16 is fixedly connected to the wall of the tail end air outlet pipe 128, an integrated component 17 is installed inside the installation box 3, each internal temperature detector 133 is electrically connected to the corresponding integrated component 17 through the controller 4, and each annular water cavity 14 and the tail end air outlet pipe 128 are jointly installed with a clearing component 18. Within a certain temperature range, the resistance of the thermistors inside the external temperature detector 16 and the internal temperature detector 133 decreases as the temperature increases.

[0040] The integrated component 17 includes a plurality of indicator lights 171 fixedly mounted on the inner wall of the installation box 3. The controller 4 controls the brightness of each indicator light 171 according to the electrical signal output by each internal temperature detector 133. An insulating seat 172 is fixedly mounted on the inner wall of the installation box 3 on the side opposite to each indicator light 171, and a photosensitive resistor 173 is fixedly mounted on the side wall of the insulating seat 172. The light emitted by each indicator light 171 is irradiated to the photosensitive surface of the photosensitive resistor 173. Two electromagnetic push rods 174 are fixedly mounted on the inner wall of the installation box 3. The telescopic ends of the two electromagnetic push rods 174 are both installed with insulating blocks 175, one of which is an insulating block. A conductive strip 176 is fixedly installed at the end of block 175, and a conductive column 177 is fixedly installed at the end of another insulating block 175. The conductive column 177 is in sliding contact with the side wall of the conductive strip 176. The controller 4 controls the corresponding electromagnetic push rod 174 to work according to the electrical signal output by the external temperature detector 16. The photosensitive resistor 173 is electrically connected to the corresponding electromagnetic push rod 174 through the controller 4. When the conductive strip 176 is not in contact with the conductive column 177, the controller 4 controls its own timing module to start timing. Within a certain light intensity range, the photosensitive resistor 173's own resistance decreases as the light intensity increases.

[0041] The clearing component 18 is provided with a plurality of air holes 181 on the upper wall of each annular cavity 10, and a first electrically-controlled valve 182 is installed inside each air hole 181, and a second electrically-controlled valve 183 is installed inside the tail end air outlet pipe 128, and an air pressure detector 184 is fixedly connected to the wall of the tail end air outlet pipe 128, and a pressure measuring end of the air pressure detector 184 is arranged inside the tail end air outlet pipe 128, and the first electrically-controlled valve 182, the second electrically-controlled valve 183 and the air pressure detector 184 are all electrically connected to the controller 4, and the air pressure detector 184 will feed back an electrical signal to the controller 4 after detecting that the air pressure reaches the set value.

[0042] The operating principle of the present invention is now described as follows: the bottom outer casing 2 is first lowered into the geothermal well (the wellhead diameter is about 20 cm and the well depth is about 2000 meters), and then the corresponding connecting outer casing 1 is assembled and fixed with the bottom outer casing 2 (welding and other methods can be used to fix the connecting outer casing 1 and the bottom outer casing 2, as well as to fix the two adjacent connecting outer casings 1, and the butt joints of each inner casing 5, the butt joints of the bottom outer casing 2 and the connecting outer casing 1 on the same side, and the butt joints of the two adjacent connecting outer casings 1 are all provided with sealing structures), and then each connecting outer casing 1 is fixed in turn and lowered into the well. After completion, the controller 4 is connected to the external power supply circuit, and then the gaseous medium inlet pipe 112 is connected to the output end of the external medium supply device, and then the tail end outlet pipe 128 is connected to the ground heat exchange device (for example, the gaseous medium is transported to the heat exchange pipeline of the ground heat exchange device, and the heat exchange medium of the ground heat exchange device flows on the outside of the heat exchange pipeline, thereby exchanging heat with the gaseous medium to achieve the use of geothermal energy), and the medium after heat exchange is returned to the external medium supply device to achieve the circulation of the gaseous heat exchange medium. The gaseous heat exchange medium can be selected from nitrogen with excellent thermal conductivity, and then the controller 4 and the external medium supply device are started;

[0043] The external medium supply device will transport the gaseous medium to the uppermost air inlet cavity 8 through the gaseous medium inlet pipe 112 and the ventilation inlet pipe 111 on the same side, and then enter the next air inlet cavity 8 through the ventilation inlet pipe 111 on the lower side of the air inlet cavity 8. The gaseous medium can enter the annular cavity 10 at the bottom outer sleeve 2 through each ventilation inlet pipe 111 and the tail end air inlet pipe 113. Then, the gaseous medium will flow back to the corresponding ventilation outlet pipe 122 through the reflux end pipe 121 at the annular cavity 10. At this time, the gaseous medium will be discharged into the outlet cavity 9 through the diversion pipe 123 of the ventilation outlet pipe 122, and then flow into the upper ventilation outlet pipe through the transition pipe 124 on the upper side of the outlet cavity 9. In 122, the gaseous medium flows back through each air outlet pipe 122, the shunt pipe 123, and the transition pipe 124 in turn, passes through each air outlet cavity 9, and is finally discharged through the tail end air outlet pipe 128. When the gaseous medium passes through each air inlet cavity 8, the annular cavity 10, and each air outlet cavity 9 in turn, the gaseous medium exchanges heat with the bottom outer casing 2, the connecting outer casing 1, and each inner casing 5, so as to absorb the heat energy of the deep formation. After the heat absorption, the gaseous medium is discharged through the tail end air outlet pipe 128 and enters the heat exchanger on the ground. The heat exchanger on the ground can absorb the heat for utilization, and the gaseous medium exchanges heat with the ground heat exchanger and flows back to the medium supply device, and continues to circulate;

[0044] In the process of heat exchange of the strata, since the temperature of each stratum is not uniform, when the internal temperature detector 133 detects that the temperature around the stratum is lower than the threshold value (the temperature is generally set according to the theoretical temperature of the corresponding stratum depth. From the surface downward, the ground temperature will increase by 1°C for every 33 meters. By measuring the stratum temperature at a certain depth in advance, the temperature range corresponding to other stratum depths can be calculated, and the temperature can be set according to the minimum temperature required for actual heat exchange), the electrical signal strength output by the internal temperature detector 133 to the controller 4 will also be lower than the threshold value. At this time, the controller 4 will control the two normally closed solenoid valves 127 and the normally open solenoid valve 125 at the corresponding position to be energized. Open, at this time, the airflow entering the ventilation outlet pipe 122 cannot be discharged through the shunt pipe 123, and the gaseous medium will be directly discharged into the transition pipe 124 through the insulation pipe 126, and enter the next ventilation outlet pipe 122 through the transition pipe 124. Since the temperature around the formation is lower than the threshold, when the gaseous medium passes through the inside of the air outlet cavity 9, the heat in the gaseous medium may be reversely conducted to the formation. Therefore, in order to minimize the waste of heat energy, the gaseous medium entering the air outlet cavity 9 is directly discharged through the ventilation outlet pipe 122, the insulation pipe 126 and the transition pipe 124, which can effectively shorten the contact time and area between the gaseous medium and the air outlet cavity 9, thereby minimizing the waste of heat energy.

[0045] Among them, when the personnel only want to take heat from a certain stratum depth in a targeted manner, taking heat energy of about 2000 meters underground as an example, at this time, the staff controls all the normally closed solenoid valves 127 and the normally open solenoid valves 125 to be energized through the controller 4, and after the gaseous medium flows into the annular cavity 10, it will be directly discharged through the ventilation outlet pipes 122, the insulation pipes 126 and the transition pipe 124, and finally discharged through the tail end outlet pipe 128, so that the gaseous medium does not contact with the connecting outer sleeves 1 during the back discharge process, so that heat can be taken at certain stratum depths, which is flexible and convenient to use;

[0046] During the heat exchange process, since the pressure inside each annular water cavity 14 is lower than the pressure inside the formation, the geothermal water in the formation will enter the annular water cavity 14 through each water hole 15 and be discharged through the water hole 15 on the other side, thereby increasing the contact area between the geothermal water and the entire device and improving the heat exchange effect on the groundwater. However, as the groundwater flows, soil impurities carried in the water may block the water holes 15, thereby reducing the water flow rate and reducing the heat exchange effect. When too many water holes 15 are blocked, the temperature of the gaseous medium discharged through the tail end outlet pipe 128 will be significantly reduced. At this time, the temperature detected by the external temperature detector 16 is low, so the strength of the electrical signal output by the external temperature detector 16 to the controller 4 is The current intensity of the electromagnetic push rod 174 controlled by the controller 4 will also decrease. Therefore, the electromagnetic push rod 174 pushes the insulating block 175 on the same side to drive the conductive column 177 to move a smaller distance. Since the water hole 15 is blocked, the temperature of each formation will not decrease significantly. Therefore, the temperature detected by each internal temperature detector 133 is still high. At this time, the electrical signal intensity output by each internal temperature detector 133 to the controller 4 remains high. Therefore, the controller 4 controls the brightness of the corresponding indicator light 171 to increase. Therefore, the light intensity projected to the photosensitive end of the photosensitive resistor 173 is high. At this time, the resistance of the photosensitive resistor 173 is reduced. Therefore, the current intensity of the electromagnetic push rod 174 connected to the controller 4 is increased. The electromagnetic push rod 174 drives the moving distance of the conductive strip 176 through the insulating block 175 to increase, so the conductive strip 176 and the conductive column 177 will separate (the misalignment distance between the conductive column 177 and the conductive strip 176 is greater than 5 cm thick, and the conductive column 177 and the conductive strip 176 are separated). At this time, the connection circuit between the conductive strip 176 and the conductive column 177 is disconnected, and the controller 4 will control its own timing module to start timing. After the timing reaches 1 minute, the timing module of the controller 4 will feedback an electrical signal to the control circuit of the controller 4, and the controller 4 will then control the second electric control valve 183 in the tail end outlet pipe 183 to close. At this time, the gaseous medium transported to each outlet cavity 9 and each inlet cavity 8 cannot be discharged, so each outlet cavity 9 and the air pressure in each air inlet chamber 8 will increase rapidly. After the air pressure detector 184 detects that the air pressure has increased to the threshold value, the air pressure detector 184 will feedback an electrical signal to the controller 4, and the controller 4 will immediately control each first electrically controlled valve 182 to be energized and opened. At this time, the high-pressure gaseous medium will be discharged into each annular water-passing chamber 14 through each air hole 181. Under the action of high pressure, the water and impurities in each annular water-passing chamber 14 will move outward, so that each water-passing hole 15 can be cleared. After the first electrically controlled valve 182 is energized for 5 minutes, the controller 4 controls each first electrically controlled valve 182 to be de-energized and closed, and controls the second electrically controlled valve 183 to be opened, and continues the heat extraction work (the controller 4 starts after the timing of the timing module reaches the set value,It can avoid the false triggering phenomenon caused by the occasional separation of the conductive column 177 and the conductive strip 176 due to temperature fluctuation. When the timing module has not reached 1 minute, the conductive column 177 and the conductive strip 176 will be re-contacted, and the timing module will count again after the conductive column 177 and the conductive strip 176 are separated next time);

[0047] Among them, after the controller 4 receives the electrical signal feedback from the timing module, the controller 4 will send relevant prompt information to the handheld terminal (such as a mobile phone, etc.). Secondly, a container for storing the gaseous medium is provided at the external gaseous medium supply device, which is used to clear the water hole 15. After the personnel receive the prompt information sent by the controller 4 a certain number of times (generally set based on the amount of the container storing the gaseous medium), the personnel should replenish the gaseous medium in time. In order to improve the convenience of use, the gaseous medium can also be air. At this time, the personnel do not need to replenish the gaseous medium regularly.

[0048] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A casing heat exchanger for a medium-deep geothermal borehole, comprising a plurality of connecting outer casings (1), a bottom outer casing (2) and an installation box (3) installed on the ground, wherein two adjacent connecting outer casings (1) are fixedly connected, the bottom outer casing (2) is fixedly connected to the bottom of the connecting outer casing (1) on the same side, and a controller (4) is fixedly installed inside the installation box (3), characterized in that: Also includes: A plurality of inner sleeves (5) are arranged on the inner sides of the corresponding connecting outer sleeves (1) and the bottom outer sleeves (2); the upper and lower sides of the outer wall of each inner sleeve (5) are fixedly sleeved with a connecting ring (6); and the connecting outer sleeve (1) and the bottom outer sleeve (2) are fixedly connected to the connecting ring (6) on the same side; A plurality of groups of sealing spacers (7) are installed between the corresponding inner sleeve (5) and the connecting outer sleeve (1), and two sealing spacers (7) in the same group separate the inner sleeve (5) and the connecting outer sleeve (1) on the same side to form an air inlet cavity (8) and an air outlet cavity (9); the bottom outer sleeve (2) is enclosed with the inner sleeve (5) through two connecting rings (6) on the same side to form an annular cavity (10); each of the air inlet cavities (8) is installed with an air inlet assembly (11) connected to the annular cavity (10); and each of the air outlet cavities (9) is installed with an air outlet assembly (12) connected to the annular cavity (10); A plurality of detection switching units (13) are mounted on the outer side wall of the corresponding connecting outer sleeve (1), each detection switching unit (13) comprises an internal temperature detector (133), and the controller (4) controls the operation of the air outlet assembly (12) according to the electrical signal output by each detection switching unit (13).

2. A casing heat exchanger for medium-deep geothermal holes according to claim 1, characterized in that: The air intake assembly (11) comprises a plurality of groups of ventilation inlet pipes (111) and a gaseous medium inlet pipe (112) arranged on the ground. The two ventilation inlet pipes (111) in the same group are arranged on the upper and lower sides of the corresponding air intake cavity (8), respectively. Each ventilation inlet pipe (111) passes through the connecting ring (6) on the same side. Two adjacent ventilation inlet pipes (111) are butted against each other. A tail end inlet pipe (113) is fixedly inserted into the upper cavity wall of the annular cavity (10), and the tail end inlet pipe (113) is butted against the ventilation inlet pipe (111) on the same side. The gaseous medium inlet pipe (112) is fixedly installed on the top of the connecting outer sleeve (1) on the same side, and the gaseous medium inlet pipe (112) is connected to the ventilation inlet pipe (111) on the same side.

3. The casing heat exchanger for medium-deep geothermal holes according to claim 1, characterized in that: The air outlet assembly (12) comprises a return end pipe (121) fixedly plugged into the upper cavity wall of the annular cavity (10); a ventilation outlet pipe (122) is fixedly plugged into the lower cavity wall of each of the air outlet cavities (9); a shunt pipe (123) is installed on the wall of each of the ventilation outlet pipes (122), and the shunt pipe (123) is connected to the air outlet cavity (9) on the same side; a transition pipe (124) is fixedly plugged into the upper cavity wall of each of the air outlet cavities (9); a normally open solenoid valve (125) is installed inside each of the transition pipes (124) and each of the shunt pipes (123); The end of the ventilation outlet pipe (122) is fixedly connected to an insulation pipe (126), and the insulation pipe (126) is connected to a transition pipe (124). A normally closed solenoid valve (127) is installed inside the insulation pipe (126). Both the normally open solenoid valve (125) and the normally closed solenoid valve (127) are electrically connected to a controller (4). Each of the transition pipes (124) is connected to the ventilation outlet pipe (122) in the adjacent connecting outer sleeve (1). The end of the transition pipe (124) away from the bottom outer sleeve (2) is fixedly connected to a tail outlet pipe (128).

4. A casing heat exchanger for medium-deep geothermal holes according to claim 3, characterized in that: Each of the detection switching units (13) comprises a mounting groove (131) provided on the outer side wall of the connecting outer sleeve (1), and a heat conducting plate (132) is fixedly encapsulated in the groove opening of the mounting groove (131), each of the internal temperature detectors (133) is fixedly installed inside the mounting groove (131), and a temperature measuring end of each of the internal temperature detectors (133) is in contact with the side wall of the heat conducting plate (132) on the same side, and the controller (4) controls the corresponding normally closed solenoid valve (127) and normally open solenoid valve (125) to energize and operate according to the electrical signal output by each of the internal temperature detectors (133).

5. The casing heat exchanger for medium-deep geothermal holes according to claim 4, characterized in that: Each of the connecting rings (6) is provided with an annular water passage cavity (14) inside, and the tube walls of the bottom outer sleeve (2) and each of the connecting outer sleeves (1) and the side wall of the annular water passage cavity (14) on the same side are provided with multiple groups of water passage holes (15), and the multiple groups of water passage holes (15) on the same side are evenly distributed in an annular shape about the axis of the inner sleeve (5).

6. The casing heat exchanger for medium-deep geothermal holes according to claim 5, characterized in that: An external temperature detector (16) is fixedly plugged into the wall of the tail end air outlet pipe (128), an integrated component (17) is installed inside the installation box (3), each of the internal temperature detectors (133) is electrically connected to the corresponding integrated component (17) via a controller (4), and each of the annular water passage cavities (14) and the tail end air outlet pipe (128) is jointly installed with a clearing component (18).

7. The casing heat exchanger for medium-deep geothermal holes according to claim 6, characterized in that: The integrated component (17) comprises a plurality of indicator lights (171) fixedly mounted on the inner wall of the installation box (3); the controller (4) controls the brightness of each indicator light (171) according to the electrical signal output by each internal temperature detector (133); an insulating seat (172) is fixedly mounted on the inner wall of the installation box (3) on the side opposite to each indicator light (171); and a photosensitive resistor (173) is fixedly mounted on the side wall of the insulating seat (172); the light emitted by each indicator light (171) is irradiated onto the photosensitive surface of the photosensitive resistor (173); and two electromagnetic push rods (174) are fixedly mounted on the inner wall of the installation box (3); the two electromagnetic push rods (174) are The telescopic ends are both installed with insulating blocks (175), wherein a conductive strip (176) is fixedly installed at the end of one of the insulating blocks (175), and a conductive column (177) is fixedly installed at the end of the other insulating block (175), wherein the conductive column (177) is in sliding contact with the side wall of the conductive strip (176), and the controller (4) controls the corresponding electromagnetic push rod (174) to work according to the electrical signal output by the external temperature detector (16), and the photosensitive resistor (173) is electrically connected to the corresponding electromagnetic push rod (174) through the controller (4), and when the conductive strip (176) is not in contact with the conductive column (177), the controller (4) controls its own timing module to start timing.

8. The casing heat exchanger for medium-deep geothermal holes according to claim 6, characterized in that: The clearing assembly (18) is provided with a plurality of air holes (181) on the upper cavity wall of each annular cavity (10); a first electrically controlled valve (182) is installed inside each of the air holes (181); a second electrically controlled valve (183) is installed inside the tail end air outlet pipe (128); an air pressure detector (184) is fixedly plugged into the wall of the tail end air outlet pipe (128); a pressure measuring end of the air pressure detector (184) is arranged inside the tail end air outlet pipe (128); and the first electrically controlled valve (182), the second electrically controlled valve (183) and the air pressure detector (184) are all electrically connected to the controller (4).

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