CN212299510U - A coaxial casing heat exchanger used in medium-deep formation boreholes - Google Patents

Abstract

The utility model discloses a coaxial sleeve heat exchanger used for drilling in medium-depth stratum, which comprises an outer sleeve and a heat insulation inner pipe coaxially arranged at the inner side of the outer sleeve, wherein the inner side at the bottom end of the outer sleeve is coaxially provided with an inverted cone-shaped opening, and the bottom end of the heat insulation inner pipe is coaxially fixed with a cone-shaped plug; the lower part of the heat insulation inner pipe is radially provided with a water inlet, and the upper end of the heat insulation inner pipe extends out of the outer sleeve and is provided with a water outlet filtering device. The utility model can only exchange the geothermal energy of the middle and deep layers without pumping the underground hot water, thereby realizing the sustainable development and utilization of the geothermal resources of the middle and deep layers; the water outlet filtering device is arranged to remove impurities such as silt in water, so that equipment is prevented from being damaged due to the impurities in the water, blockage is avoided, and the impurities can be cleaned without stopping the pump; a heat exchange ring network is arranged on the inner side wall of the outer sleeve, so that the heat exchange area is increased, the heat taking amount of a single well is increased, and the heat supply capacity of a ground heat supply system is improved; the heat insulation inner pipe adopts aerogel as the insulating layer, and is thermal-insulated effectual, reduces the wet return heat loss.

Description

Coaxial sleeve heat exchanger used in medium-depth stratum drilling

Technical Field

The utility model relates to a geothermal energy application technical field, especially a coaxial double-pipe heat exchanger that is used for in well deep stratum drilling.

Background

The terrestrial heat has the characteristics of cleanness, environmental protection, good stability, cyclic utilization and the like, and is a practical and competitive renewable energy source. The total amount of Chinese hydrothermal geothermal resources is 1.25 trillion tons of standard coal, and the annual available coal yield is 18.65 billion tons of standard coal. Medium and low temperature is mainly used (the total amount of resources is 1.23 trillion tons, 18.47 million tons can be collected in the year), and high temperature is used as an auxiliary (the total amount of resources is 141 million tons, 0.18 million tons can be collected in the year). At present, the central heating technology of the intermediate and deep geothermal energy is relatively mature. By the end of 2015, the geothermal heating area of the middle and deep layers in China reaches 1 hundred million square meters. The geothermal heating areas of provinces and cities such as Hebei, Tianjin and the like are all over 2000 ten thousand square meters.

The research of the current coaxial sleeve heat exchanger also faces a plurality of problems which need to be solved urgently, such as low coaxiality precision, serious heat dissipation loss of a water return pipe, low return water temperature, low comprehensive utilization efficiency of geothermal resources, more sediment impurities in return water, damage to heat pump equipment or pipeline blockage and the like.

SUMMERY OF THE UTILITY MODEL

The utility model aims at solving the problem, a coaxial sleeve heat exchanger for in the drilling of well deep stratum has been designed.

The technical scheme of the utility model is that, the coaxial sleeve heat exchanger used for drilling in the medium-depth stratum comprises an outer sleeve and a heat insulation inner pipe coaxially arranged at the inner side of the outer sleeve, wherein the inner side of the bottom end of the outer sleeve is coaxially provided with an inverted cone-shaped opening, and the bottom end of the heat insulation inner pipe is coaxially fixed with a cone-shaped plug; the conical plug comprises an inverted cone matched with the inverted cone opening, the top end of the inverted cone is fixedly connected with the bottom end of the heat insulation inner pipe, a sealing sleeve attached to the inner wall of the inverted cone opening to seal the inverted cone opening is sleeved on the inverted cone, and a limiting ring used for limiting the sealing sleeve to fall off is fixed at the bottom end of the inverted cone; the lower part of the heat insulation inner pipe is radially provided with a water inlet, and the upper end of the heat insulation inner pipe extends out of the outer sleeve and is provided with a water outlet filtering device.

Preferably, the water outlet filtering device comprises a main filtering pipeline and a collecting box, the main filtering pipeline is communicated with the heat insulation inner pipe, a coarse filtering net and a fine filtering net are arranged in the horizontal section of the main filtering pipeline along the backflow direction, the collecting box is vertically provided with the coarse filtering pipeline and the fine filtering pipeline which are communicated with the collecting box, the coarse filtering pipeline and the fine filtering pipeline are respectively arranged at the upstream of the coarse filtering net and the upstream of the fine filtering net, the coarse filtering pipeline and the fine filtering pipeline are respectively provided with two upper layers and two lower layers of butterfly valves which are arranged at intervals, the opening and closing states of the two upper layers of butterfly valves and the two lower layers of butterfly valves are opposite, the collecting box is fixedly provided with a shaft seat and a speed reduction stepping motor, a rotating shaft is rotatably arranged on; the butterfly valve closing mechanism comprises a rotating shaft and butterfly valves, and is characterized by further comprising an incomplete gear transmission mechanism connected with the rotating shaft and the butterfly valves, wherein the rotating shaft drives the butterfly valves to open and close through the incomplete gear transmission mechanism, so that the butterfly valves on two upper layers are opened and closed synchronously under the closing state of the butterfly valves on two lower layers, or the butterfly valves on the two lower layers are opened and closed synchronously under the closing state of the butterfly valves on the two upper layers.

Preferably, incomplete gear drive includes that two upper and lower two-layer intervals are installed in the pivot and respectively with the incomplete end face fluted disc that upper and lower two-layer butterfly valve corresponds, all install two dials the board on the terminal surface of incomplete end face fluted disc, all install incomplete gear on the valve rod of butterfly valve, incomplete gear that two upper butterfly valves are connected sets up in opposite directions and with the incomplete end face fluted disc intermittent type meshing of upper strata, incomplete gear that two lower layers butterfly valves are connected sets up in opposite directions and with the incomplete end face fluted disc intermittent type meshing of lower floor, all install on the incomplete gear terminal surface and dial board complex driving lever, dial the board and the cooperation of driving lever contact in order to drive incomplete gear and the meshing of incomplete end face fluted disc.

Preferably, a heat exchange ring net is fixed on the inner wall of the outer sleeve, and the axis of the heat exchange ring net is coaxial with the axis of the outer sleeve.

Preferably, the heat exchange ring network is made of copper.

Preferably, the bottom of the outer sleeve is in an inverted cone shape which narrows gradually.

Preferably, the heat insulation inner pipe comprises an inner pipe and an outer inner pipe, the outer inner pipe is coaxially sleeved on the inner side of the inner pipe and is positioned above the water inlet, a heat insulation layer is arranged between the inner pipe and the outer inner pipe, and the heat insulation layer is sealed through sealing ring bodies arranged at the upper end and the lower end of the inner pipe and the outer inner pipe.

Preferably, the thermal insulation layer is filled with thermal insulation materials.

Preferably, the thermal insulation material is aerogel.

The utility model has the advantages that:

1. circulating water is injected into the outer sleeve, the circulating water flows downwards in the outer sleeve in a heat exchange manner to absorb a high-temperature rock-soil layer and then flows back to a ground source heat pump unit on the stratum through the heat insulation inner pipe, the ground source heat pump unit exchanges heat with an indoor air conditioner terminal system to provide a continuous and stable heat source for a ground heat supply system, and the water after heat exchange is circularly injected into the outer sleeve, so that circulation is formed in a reciprocating manner, only middle-deep geothermal energy can be exchanged on the premise of not extracting underground hot water, and sustainable development and utilization of middle-deep geothermal resources are realized;

2. the water outlet filtering device is arranged to remove impurities such as silt in water, so that equipment damage caused by the impurities in the water is avoided, a two-stage filtering mode is adopted, the filtering effect is good, blockage is avoided, and the impurities can be cleaned without stopping a pump;

3. the inner side wall of the outer sleeve is provided with the heat exchange ring network, so that the heat exchange area is increased, circulating water flows downwards and can contact with the heat exchange ring network to absorb heat and be fully disturbed, the heat exchange efficiency of the heat exchanger is improved, the heat taking amount of a single well is increased, the heat supply capacity of a ground heat supply system is improved, and the comprehensive cost of the system is reduced;

4. the outer sleeve is convenient to lower to the reserved anchor hole, the sealing performance is good, the coaxiality of the outer sleeve and the heat insulation inner pipe is high, and the service life is long;

5. the heat insulation inner pipe adopts aerogel as the insulating layer, and is thermal-insulated effectual, reduces the wet return heat loss.

Drawings

FIG. 1 is a schematic structural diagram of the heat exchanger of the present invention;

FIG. 2 is a schematic structural view of an outer sleeve and a heat exchange ring network;

FIG. 3 is a schematic view of the filter apparatus of FIG. 1;

FIG. 4 is an enlarged view of a portion of FIG. 1;

FIG. 5 is a partial enlarged view of B in FIG. 1;

FIG. 6 is a schematic view of a partial gear train;

FIG. 7 is a schematic view of the engagement process of the upper incomplete end-face fluted disc and the incomplete gear;

FIG. 8 is a schematic illustration of the relationship between the position of the lower incomplete end-toothed disc and the incomplete gear during the procedure of FIG. 8;

FIG. 9 is a partial schematic view of a filter apparatus;

figure 10 is a cross-sectional view of the heat exchanger of the present invention;

in the figure, 1, an outer sleeve; 11. an inverted cone-shaped opening; 2. a heat-insulating inner pipe; 21. a water inlet; 22. an inner tube; 23. an outer inner tube; 24. a thermal insulation layer; 25. a sealing ring body; 3. a conical plug; 31. an inverted cone; 32. sealing sleeves; 33. a limiting ring; 4. a filtration device; 41. a main filtration conduit; 411. a coarse filter screen; 412. a fine filter screen; 42. a collection box; 43. a coarse filtration pipeline; 44. a fine filtration pipeline; 45. a butterfly valve; 46. a shaft seat; 47. a deceleration stepping motor; 48. a rotating shaft; 49. an incomplete gear drive; 491. an incomplete end face fluted disc; 491a, an annular wall; 491b, end face teeth; 492. dialing a plate; 493. an incomplete gear; 494. a deflector rod; 5. and (4) a heat exchange ring network.

Detailed Description

The utility model is described in detail with reference to the accompanying drawings, as shown in fig. 1-3, a coaxial sleeve heat exchanger used for drilling in medium-deep stratum comprises an outer sleeve 1 and a heat insulation inner pipe 2 coaxially arranged at the inner side of the outer sleeve 1, the outer sleeve 1 is made of galvanized steel pipe, the heat conduction effect is good, the strength is high, the corrosion resistance is good, and the heat exchanger can be used in medium-deep stratum for a long time; in order to facilitate the driving of the outer sleeve 1 into the medium-depth stratum and reduce the pressure of water and mud to the outer sleeve 1 in the process of driving the outer sleeve 1 into the medium-depth stratum, the inner side of the bottom end of the outer sleeve 1 is coaxially provided with an inverted cone-shaped opening 11, so that the outer sleeve 1 is easily driven into a reserved anchor hole, then the well washing operation is carried out on the outer sleeve 1, and water, silt and the like in the outer sleeve 1 are pumped out by using well washing equipment; in order to prevent circulating water from mixing into bottom sediment, a conical plug 3 is coaxially fixed at the bottom end of the heat insulation inner pipe 2 to seal the inverted conical opening 11; the conical plug 3 comprises an inverted cone 31 matched with the inverted cone opening 11, the top end of the inverted cone 31 is fixedly connected with the bottom end of the heat insulation inner pipe 2, a sealing sleeve 32 attached to the inner wall of the inverted cone opening 11 to seal the inverted cone opening 11 is sleeved on the inverted cone 31, and a limiting ring 33 used for limiting the sealing sleeve 32 to fall off is fixed at the bottom end of the inverted cone 31; the heat insulation inner pipe 2 is put down after the well washing operation, under the action of the self gravity of the heat insulation inner pipe 2 and the plug, the sealing sleeve 32 is tightly pressed and attached to the inverted cone-shaped opening 11 so as to seal the inverted cone-shaped opening 11, slurry in the stratum is prevented from entering the heat exchanger from the inverted cone-shaped opening 11 to cause pollution to circulating water, the design of the inverted cone-shaped opening 11 and the inverted cone-shaped cylinder 31 not only can play a good sealing effect, but also can better press and fix the conical plug 3 under the action of water pressure, the coaxial stability of the heat insulation inner pipe 2 and the outer sleeve 1 is kept, the lower part of the heat insulation inner pipe 2 is radially provided with a water inlet 21, the upper end of the heat insulation inner pipe 2 extends out of the outer sleeve 1 and is provided with a water outlet filtering device 4, the circulating water enters from the circulating water inlet end at the upper part of, the ground source heat pump machine exchanges heat with an indoor air conditioner terminal system, so that refrigeration or heating of a building is achieved, impurities such as silt in water are removed by arranging the water outlet filtering device 4, and equipment damage caused by the impurities in the water is avoided.

As a preferred embodiment of the present invention, in order to improve the filtering effect and avoid clogging, a water outlet filtering device 4 is provided, as shown in fig. 3 and fig. 7 to 9, the water outlet filtering device 4 includes a main filtering pipe 41 and a collecting box 42, the collecting box 42 is disposed on the ground, the main filtering pipe 41 is communicated with the heat insulation inner pipe 2, the main filtering pipe 41 has a horizontal section, a coarse filtering net 411 and a fine filtering net 412 are disposed in the horizontal section of the main filtering pipe 41 along the backflow direction, the coarse filtering net 411 and the fine filtering net 412 perform primary coarse filtering and secondary fine filtering on the circulating water, the diameter of the filtering net of the coarse filtering net 411 is larger than that of the fine filtering net 412, the coarse filtering net 411 mainly filters large-particle gravels in the circulating water, the fine filtering net 412 mainly filters small-particle sediments in the circulating water, and; a coarse filter pipeline 43 and a fine filter pipeline 44 which are communicated with the collecting box 42 are vertically arranged on the collecting box 42, the coarse filter pipeline 43 and the fine filter pipeline 44 are respectively arranged at the upstream of the coarse filter screen 411 and the fine filter screen 412, two upper-layer butterfly valves 45 and two lower-layer butterfly valves 45 which are arranged at intervals are respectively arranged on the coarse filter pipeline 43 and the fine filter pipeline 44, the opening and closing states of the two upper-layer butterfly valves 45 and the two lower-layer butterfly valves 45 are opposite, the two lower layers are closed in most of time, the two upper-layer butterfly valves 45 are opened in most of time, large-particle sand intercepted by the coarse filter screen 411 can be accumulated on a butterfly plate of the lower-layer butterfly valve 45 in the coarse filter pipeline 43, and small-particle sand intercepted by the fine filter screen 412 can be accumulated on a butterfly plate of the lower-layer; a shaft seat 46 and a speed-reducing stepping motor 47 are fixedly mounted on the collecting box 42, a rotating shaft 48 is rotatably mounted on the shaft seat 46, the speed-reducing stepping motor 47 is in transmission connection with the rotating shaft 48, the speed-reducing stepping motor 47 and the rotating shaft 48 are in transmission connection with the rotating shaft 48 through a transmission assembly, and the transmission assembly can be a belt transmission assembly and comprises a driving belt pulley connected with the output end of the speed-reducing stepping motor 47, a driven belt pulley mounted on the rotating shaft 48 and a transmission belt in tension connection with the driving belt pulley and the driven belt pulley; the butterfly valve device is characterized by further comprising an incomplete gear 493 transmission mechanism 49 connected with the rotating shaft 48 and the butterfly valves 45, wherein the rotating shaft 48 drives the butterfly valves 45 to open and close through the incomplete gear 493 transmission mechanism 49, so that the butterfly valves 45 on the two upper layers are opened and closed synchronously in the closed state of the butterfly valves 45 on the two lower layers, or the butterfly valves 45 on the two lower layers are opened and closed synchronously in the closed state of the butterfly valves 45 on the two upper layers; butterfly valve 45 of two upper strata seals in step, with cut off coarse filtration pipeline 43 and smart filtration pipeline 44 lower part and main filtration pipeline 41's passageway, avoid carrying out the circulating water together with impurity, the butterfly valve 45 of two lower floors is opened in step when two upper butterfly valves 45 are closed, impurity receives dead weight whereabouts discharge to collecting box 42, the impurity of being convenient for discharge, avoid leading to main filtration pipeline 41 to block up too much in coarse filtration pipeline 43 and the smart filtration pipeline 44 impurity, make the circulating water flow unobstructed, when carrying out impurity clearance simultaneously, the water pump need not stop work, terrestrial heat's utilization efficiency has been improved greatly.

Further, as shown in fig. 3 and 6-8, in order to realize the synchronous opening and closing of the two upper butterfly valves 45 when the two lower butterfly valves 45 are in the closed state, or the synchronous opening and closing of the two lower butterfly valves 45 when the two upper butterfly valves 45 are in the closed state, an incomplete gear 493 transmission mechanism 49 is provided, the incomplete gear 493 transmission mechanism 49 comprises two incomplete end-face toothed discs 491 which are respectively installed on the rotating shaft 48 at intervals and correspond to the upper and lower butterfly valves 45, two shifting plates 492 are respectively installed on the end faces of the incomplete end-face toothed discs 491, incomplete gears 493 are respectively installed on the valve rods of the butterfly valves 45, the incomplete gears 493 connected with the two upper butterfly valves 45 are oppositely arranged and are intermittently meshed with the upper incomplete end-face toothed discs 491, the incomplete gears 493 connected with the two lower butterfly valves 45 are oppositely arranged and are intermittently meshed with the lower incomplete end-face toothed discs 491, and shifting rods 494 matched with the shifting plates 492 are respectively installed on the, the shifting plate 492 is in contact fit with the shifting rod 494 to drive the incomplete gear 493 to mesh with the incomplete end-face toothed disc 491; the two incomplete end-face fluted discs 491 on the upper and lower layers have the same structure, two end-face teeth 491b which are symmetrical along the axis are arranged on the annular wall 491a on the outer edge of the upper end face, the incomplete end-face fluted discs 491 are quartered, the end-face teeth 491b are positioned in two opposite quadrants, the top ends of the end-face teeth 491b are flush with the top end of the annular wall 491a, and the incomplete end-face fluted discs 491 on the upper layer and the incomplete end-face fluted discs 491 on the lower layer are arranged in a staggered way by 90 degrees; in the filtering state, the lower butterfly valve 45 is closed, and the upper butterfly valve 45 is opened; when impurities are cleaned, the speed reduction stepping motor 47 drives the rotating shaft 48 to rotate 90 degrees counterclockwise at a slow speed, the shifting plate 492 of the incomplete end face fluted disc 491 on the upper layer pushes the shifting rod 494, the end face teeth 491b of the incomplete end face fluted disc 491 on the upper layer and the incomplete gear 493 connected with the two butterfly valves 45 on the upper layer undergo a non-meshing-non-meshing process, and during the meshing process, the incomplete gear 493 rotates and drives the valve rod and the valve core of the butterfly valve 45 on the upper layer to rotate 270 degrees, so that the valve core moves from a vertical opening state to a horizontal closing state, a vertical opening state and a horizontal closing state, and the butterfly valves 45 on the upper layer are closed; the speed-reducing stepping motor 47 drives the rotating shaft 48 to rotate counterclockwise again by 90 degrees slowly, the end face teeth 491b of the incomplete end face fluted disc 491 on the lower layer and the incomplete gear 493 connected with the two butterfly valves 45 on the lower layer undergo the process of non-meshing, meshing and non-meshing, during the meshing process, the incomplete gear 493 rotates and drives the valve rod and the valve core of the butterfly valve 45 on the lower layer to rotate by 270 degrees, so that the valve core moves from the vertical opening state to the horizontal closing state, the vertical opening state and the horizontal closing state, during the process, impurities fall into the collecting box 42, in the process, the shifting plate 492 and the shifting rod 494 on the upper layer are far away, the incomplete gear 493 and the end face teeth are far away and are not meshed any more, the missing tooth position of the incomplete gear 493 on the upper layer is opposite to the annular wall 491a of the incomplete end face fluted disc 491 on the upper layer, so that the incomplete gear 493 on, the circulating water and impurities are prevented from being transported out together; the incomplete end-face fluted disc 491 finishes one time of impurity cleaning every time rotating 180 degrees; the principle is the same as the above when the impurities are cleaned again.

Preferably, in order to improve the heat exchange efficiency, increase the heat exchange area and simultaneously keep the heat insulation inner tube 2 stable, as shown in fig. 2 and 10, a heat exchange ring network 5 is fixed on the inner wall of the outer sleeve 1, the heat exchange ring network 5 is arranged at intervals from top to bottom, the axis of the heat exchange ring network 5 is coaxial with the axis of the outer sleeve 1, the heat insulation inner tube 2 is inserted between the heat exchange ring networks 5, a gap is left between the outer wall of the heat insulation inner tube 2 and the inner ring of the heat exchange ring network 5 so as to lower the heat insulation inner tube 2, the heat exchange ring network 5 is welded with the outer sleeve 1, and the heat transferred by the heat; because the circulating water in the outer sleeve 1 can only contact with the outer sleeve 1 for heat exchange, and the heat exchange area is small, the heat exchange looped network 5 is arranged, so that the circulating water between the outer sleeve 1 and the heat insulation inner pipe 2 can contact with the heat exchange looped network 5 for heat exchange, the heat exchange area is increased, and the circulating water absorbs more geothermal energy.

Preferably, in order to improve the heat exchange efficiency, the heat exchange ring network 5 is preferably made of metal with good guiding performance, so that the heat exchange ring network 5 is made of copper, and certainly, the heat exchange ring network 5 can also be made of other metals such as steel.

Preferably, as shown in fig. 1-2, in order to reduce the resistance when the outer sleeve 1 is lowered to the reserved anchor hole, the bottom of the outer sleeve 1 is set to be in the shape of an inverted cone which gradually narrows, and this design is favorable for centering the whole heat exchanger.

Preferably, in order to reduce the heat exchange amount between the circulating water in the heat insulation inner tube 2 and the outside in the ascending process, the heat insulation inner tube 2 is made of heat insulation material, in this embodiment, the heat insulation inner tube 2 comprises an inner tube 22 and an outer tube 23, both the inner tube 22 and the outer tube 23 can be made of PE pipes, the outer tube 23 is coaxially sleeved on the inner side of the inner tube 22 and is located above the water inlet 21, a heat insulation layer 24 is arranged between the inner tube 22 and the outer tube 23, the heat insulation layer 24 is sealed by a sealing ring body 25 arranged at the upper end and the lower end of the inner tube 22 and the outer tube 23, the heat insulation layer 24 is filled with heat insulation material, the heat insulation material is preferably.

Above-mentioned technical scheme has only embodied the utility model discloses technical scheme's preferred technical scheme, some changes that this technical field's technical personnel probably made to some parts wherein have all embodied the utility model discloses a principle belongs to within the protection scope of the utility model.

Claims (9)

1. A coaxial casing heat exchanger for use in a medium-deep formation borehole, comprising an outer casing (1) and a thermally insulated inner pipe (2) coaxially arranged on the inside of the outer casing (1), characterized in that , the inner side of the bottom end of the outer sleeve (1) is coaxially provided with an inverted conical opening (11), and the bottom end of the thermal insulation inner pipe (2) is coaxially fixed with a conical plug (3); The plug (3) comprises an inverted conical cylinder (31) adapted to the inverted conical opening (11), the top of the inverted conical cylinder (31) is fixedly connected with the bottom end of the thermal insulation inner pipe (2), the The inverted conical cylinder (31) is covered with a sealing sleeve (32) which is fitted with the inner wall of the inverted conical opening (11) to seal the inverted conical opening (11). A limit ring (33) for limiting the falling off of the sealing sleeve (32); a water inlet (21) is radially opened at the lower part of the thermal insulation inner tube (2), and the upper end of the thermal insulation inner tube (2) protrudes from the outer sleeve (1) and is equipped with a water outlet filter device (4). 2. A coaxial casing heat exchanger for use in medium-deep formation boreholes according to claim 1, characterized in that the effluent filter device (4) comprises a main filter pipe (41) and a collection box (42), the main filter pipe (41) is communicated with the thermal insulation inner pipe (2), and a coarse filter screen (411) and a fine filter screen (412) are arranged in the horizontal section of the main filter pipe (41) along the backflow direction ), the collection box (42) is vertically installed with a coarse filter pipe (43) and a fine filter pipe (44) that communicate with the collection box (42). The coarse filter pipe (43) and the fine filter pipe (44) ) are respectively arranged upstream of the coarse filter screen (411) and the fine filter screen (412), the coarse filter pipe (43) and the fine filter pipe (44) are both provided with two upper and lower butterfly valves (45) arranged at intervals , the opening and closing states of the two upper butterfly valves (45) and the two lower butterfly valves (45) are opposite, and a shaft seat (46) and a deceleration stepping motor (47) are fixedly installed on the collection box (42). A rotating shaft (48) is rotatably installed on the (46), and the decelerating stepper motor (47) is connected with the rotating shaft (48) in a drive; it also includes an incomplete gear (493) connected with the rotating shaft (48) and each butterfly valve (45). Transmission mechanism (49), the rotating shaft (48) drives each butterfly valve (45) to open and close through the incomplete gear (493) transmission mechanism (49), so that the two upper butterfly valves (45) are connected to the two lower butterfly valves (45) Synchronous opening and closing in the closed state, or synchronous opening and closing of the two lower butterfly valves (45) in the closed state of the two upper butterfly valves (45). 3. A coaxial casing heat exchanger for use in medium-deep formation boreholes according to claim 2, characterized in that the incomplete gear (493) transmission mechanism (49) comprises two upper and lower two Incomplete end-face toothed discs (491) are installed on the rotating shaft (48) at intervals and corresponding to the upper and lower butterfly valves (45) respectively, and two dials are installed on the end surfaces of the incomplete end-face toothed discs (491). (492), incomplete gears (493) are installed on the valve stems of the butterfly valves (45), and the incomplete gears (493) connected to the two upper butterfly valves (45) are arranged opposite to each other and are 491) Intermittent meshing, the incomplete gears (493) connected to the two lower butterfly valves (45) are arranged opposite to each other and intermittently mesh with the lower incomplete end face toothed disc (491). The dial (492) is matched with the dial lever (494), the dial plate (492) is in contact with the dial rod (494) to drive the incomplete gear (493) to engage with the incomplete end face gear plate (491). 4 . The coaxial casing heat exchanger according to claim 1 , wherein a heat exchange ring network ( 5 ) is fixed on the inner wall of the outer casing ( 1 ), The axis of the heat exchange ring network (5) is coaxial with the axis of the outer sleeve (1). 5 . The coaxial casing heat exchanger according to claim 4 , wherein the heat exchange ring ( 5 ) is made of copper. 6 . 6 . The coaxial casing heat exchanger according to claim 1 , wherein the bottom of the outer casing ( 1 ) has a gradually narrowed inverted cone shape. 7 . 7. A coaxial casing heat exchanger for use in medium-deep formation boreholes according to claim 1, characterized in that the insulating inner pipe (2) comprises an inner inner pipe (22) and an outer inner pipe (22) An inner tube (23), the outer inner tube (23) is coaxially sleeved inside the inner inner tube (22) and located above the water inlet (21), between the inner inner tube (22) and the outer inner tube (23) A thermal insulation layer (24) is provided, and the thermal insulation layer (24) is sealed by sealing ring bodies (25) installed on the upper and lower ends of the inner inner tube (22) and the outer inner tube (23). 8 . The coaxial casing heat exchanger according to claim 7 , wherein the heat insulating layer ( 24 ) is filled with heat insulating material. 9 . 9 . The coaxial casing heat exchanger according to claim 8 , wherein the thermal insulation material is aerogel. 10 .

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