A countercurrent spray cooling tower

Abstract

The present application relates to the technical field of cooling towers, and in particular to a countercurrent spray cooling tower, comprising a first box and a second box, an air inlet pipe for circulating hot and humid air is arranged on the first box, an exhaust pipe is arranged on the second box, a connecting piece for ventilation is arranged between the first box and the second box, a cooling mechanism for eliminating heat in the hot and humid air is arranged on the first box, the cooling mechanism comprises cooling water arranged in the first box, a refrigeration element for cooling water is arranged on the first box, and a spray assembly for extracting cooling water for cooling is arranged on the first box. The present application has the effect of improving the utilization rate of water resources.

Description

Technical Field

[0001] The present application relates to the technical field of cooling towers, and in particular to a countercurrent spray cooling tower. Background Art

[0002] The formation principle of "white mist" in the cooling tower is: the saturated airflow in the cooling tower leaves the cooling tower driven by the operation of the fan. When the external temperature of the cooling tower is low, the saturated airflow condenses when it encounters cold to form white mist. The formation principle is the same as the principle of fog formed when people breathe in winter. White mist is not only a carrier of PM2.5, but also wastes a lot of water resources.

[0003] Traditional cooling towers use fillers to cool circulating water. The circulating hot water from the process unit enters the cooling tower spray system and enters the filler from top to bottom. The filler is generally made of PVC sheets. Water enters the filler and forms a water film along the PVC sheet. The outside dry and cold air enters the filler from bottom to top and exchanges heat with the water film. The water film evaporates and cools down. The air is heated and humidified to form hot and humid air. A fan is installed on the top of the cooling tower to discharge the hot and humid air out of the tower, and the circulating hot water is cooled and becomes circulating cold water.

[0004] Since the hot and humid air contains a large amount of water vapor, directly discharging it out of the cooling tower will cause the company to waste a large amount of water resources, resulting in the company's need to increase investment costs in water resource consumption, which is insufficient. Utility Model Content

[0005] In order to improve the waste of water resources in cooling towers, the present application provides a countercurrent spray cooling tower.

[0006] The present application provides a counter-current spray cooling tower adopting the following technical solution:

[0007] A countercurrent spray cooling tower comprises a first box body and a second box body, wherein the first box body is provided with an air inlet pipe for circulating humid hot air, the second box body is provided with an exhaust pipe, a connecting piece for ventilation is provided between the first box body and the second box body, the first box body is provided with a cooling mechanism for eliminating heat in the humid hot air, the cooling mechanism comprises cooling water arranged in the first box body, a refrigeration element for cooling the cooling water is provided on the first box body, and a spray assembly for extracting cooling water for cooling is provided on the first box body.

[0008] By adopting the above technical scheme, when the hot and humid air flows into the first box through the air intake pipe, the refrigeration component cools down the cooling water inside the first box, and at the same time the spray component sprays out the cooled cooling water to cool down the hot and humid air, so that the moisture in the hot and humid air quickly condenses and falls, thereby becoming a part of the cooling water. The cooled air flows to the second box through the connecting piece and is discharged from the exhaust pipe of the second box, thereby realizing the collection and utilization of the moisture in the hot and humid air, which is beneficial to reducing the consumption of water resources.

[0009] Optionally, the refrigeration component includes a refrigeration pipe disposed in a first box and electrically connected to a control system, the refrigeration pipe is immersed in cooling water, and a temperature sensor electrically connected to the control system is disposed in the first box.

[0010] By adopting the above technical solution, the temperature sensor feeds back the temperature of the cooling water in the first box to the control system. The control system lowers the temperature of the cooling water by supplying power to the refrigeration pipe for cooling, thereby maintaining a good cooling effect of the cooling water.

[0011] Optionally, the spray assembly includes a plurality of cooling plates arranged in a first box body, the plurality of cooling plates are arranged in a top-down direction, the interior of the cooling plates is hollow, a plurality of spray pipes are connected to the cooling plates, the spray pipes are rotatably provided with inclined spray blades, the spray blades are provided with spray holes connected to the spray pipes, the spray direction of the spray holes is perpendicular to the inclination direction of the spray blades, and the first box body is provided with a water supply component for supplying water to the cooling plates.

[0012] By adopting the above technical solution, a large amount of cooling water is filled into the cooling plate by the water supply component, and the cooling water is sprayed out from the spray holes on the spray blades through the spray pipe. The reaction force of the cooling water sprayed from the spray holes drives the spray blades to rotate. The rotation of the spray blades will make the water mist and humid hot air inside the first box body fully mixed, thereby cooling the humid hot air, which is beneficial to accelerate the rapid condensation of water in the humid hot air.

[0013] Optionally, the water supply component includes a water pump disposed on the first box body and electrically connected to the control system, and water supply pipes are connected between the water pump and the cooling plate, and between the water pump and the first box body.

[0014] By adopting the above technical solution, workers start the water pump through the control system, and the water pump pumps the cooling water in the first box to the inside of the cooling plate through the water supply pipe, thereby providing a higher water pressure inside the cooling plate, thereby increasing the reaction force of the cooling water sprayed out from the spray hole when the cooling water is sprayed out, which is beneficial to the rotation of the spray blades and accelerates the mixing and cooling effect of the humid hot air and water mist.

[0015] Optionally, the circumferential side walls of the cooling plate are tightly attached to the circumferential inner walls of the first box body, and a drain pipe connecting the top and bottom of the cooling plate is provided on the cooling plate, and the diameter of the drain pipe gradually decreases from top to bottom, and a baffle is provided at the bottom of the cooling plate, and the baffle is located at the liquid outlet of the drain pipe and there is a distance between the baffle and the liquid outlet of the drain pipe.

[0016] By adopting the above technical scheme, after the cooling water is sprayed out from the spray holes on the spray blades, the hot and humid air is continuously filled into the first box body, thereby the internal pressure of the cavity surrounded by the first box body and the cooling plate increases rapidly. When the gas with a certain pressure is discharged from the drain pipe, the liquefied cooling water on the top of the cooling plate is driven by the high-pressure gas to be discharged from the drain pipe, and impacts the baffle to form water mist again, so that the water mist sprayed from a cooling plate below the cooling plate flows countercurrently upward to mix with it for cooling, and because the temperature of the water mist sprayed from the cooling plate located below is lower than the temperature of the water mist formed by blocking the baffle, the hot and humid air is cooled again, and repeated cooling through multiple cooling plates is conducive to further condensation and liquefaction of moisture in the hot and humid air. When discharged from the drain pipe on the lowest cooling plate, the formed water mist will quickly liquefy into the cooling water.

[0017] Optionally, the connecting piece includes a vertical guide rod arranged at the bottom of the first box body, a ventilation cone is slidably arranged on the guide rod, one end of the ventilation cone is close to the water surface of the cooling water, and the other end is connected to a hose, the hose is connected to the second box body, and a float is arranged on the end of the ventilation cone close to the cooling water.

[0018] By adopting the above technical solution, a balance is formed between the gravity of the float and the ventilation cone, so that the air inlet end of the ventilation cone is close to the surface of the cooling water. When the water mist in the first box flows from the ventilation cone to the second box, the water mist is more easily liquefied into the cooling water, which helps to reduce the flow of water mist into the second box.

[0019] Optionally, the diameter of the ventilation cone gradually increases from top to bottom.

[0020] By adopting the above technical solution, in the process of water mist flowing to the ventilation cone, the air in the water mist flows into the second box per unit time, and at the same time it is beneficial for the moisture in the water mist to liquefy into the cooling water.

[0021] Optionally, the bottom connection between the first box body and the second box body is open and provided with a filter screen, a liquid level sensor electrically connected to the control system is provided in the second box body, a drain pipe is connected to the second box body, and an electric control valve electrically connected to the control system is provided on the drain pipe.

[0022] By adopting the above technical solution, as time goes by, the amount of moisture condensed in the hot and humid air inside the first box body increases, the water level inside the first box body continues to rise, and the cooling water flows through the filter to the inside of the second box body. When the cooling water inside the second box body triggers the liquid level sensor, the liquid level sensor feeds back the signal to the control system, the control system starts the electric control valve, and the drain pipe discharges the cooling water inside the second box body into the external collection box until the cooling water inside the second box body can no longer trigger the liquid level sensor, thereby controlling the height of the cooling water level inside the second box body.

[0023] Optionally, a partition frame is provided in the second box body, a sponge block is provided on the partition frame, the sponge block is located above the connection point between the hose and the second box body, and the circumferential outer side wall of the sponge block abuts against the circumferential inner side wall of the second box body.

[0024] By adopting the above technical solution, the moisture in the gas flowing into the second box body is further reduced during the process of passing through the sponge block and then being discharged from the exhaust pipe, which is beneficial to further improve the utilization rate of water resources.

[0025] In summary, the present application includes at least one of the following beneficial technical effects:

[0026] 1. When the hot and humid air flows into the first box through the air inlet pipe, the refrigeration component cools down the cooling water inside the first box, and the spray component sprays the cooled cooling water to cool down the hot and humid air, so that the moisture in the hot and humid air quickly condenses and falls, thus becoming part of the cooling water. The cooled air flows to the second box through the connecting piece and is discharged from the exhaust pipe of the second box, thereby realizing the collection and utilization of the moisture in the hot and humid air, which is conducive to reducing the consumption of water resources;

[0027] 2. The water supply component fills a large amount of cooling water into the cooling plate, and the cooling water is sprayed out from the spray holes on the spray blades through the spray pipe. The reaction force of the cooling water sprayed from the spray holes drives the spray blades to rotate. The rotation of the spray blades will fully mix the water mist and humid hot air inside the first box, thereby cooling the humid hot air, which is conducive to the effect of accelerating the rapid condensation of water in the humid hot air;

[0028] 3. After the cooling water is sprayed out from the spray holes on the spray blades, the hot and humid air is continuously filled into the first box body, so that the internal pressure of the cavity surrounded by the first box body and the cooling plate increases rapidly. When the gas with a certain pressure is discharged from the drain pipe, the liquefied cooling water on the top of the cooling plate is driven by the high-pressure gas to be discharged from the drain pipe, and impacts the baffle to form water mist again, so that the water mist sprayed from a cooling plate below the cooling plate flows countercurrently upward to mix with it for cooling, and because the temperature of the water mist sprayed from the cooling plate below is lower than the temperature of the water mist formed by blocking the baffle, the hot and humid air is cooled again, and the cooling is repeated multiple times through multiple cooling plates. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the structure of an embodiment of the present application.

[0030] Figure 2 It is a structural schematic diagram of the positional relationship among the ventilation cone, the float and the guide rod in the embodiment of the present application.

[0031] Figure 3 It is a cross-sectional view of the positional relationship among the first box body, the cooling plate and the refrigeration pipe in the embodiment of the present application.

[0032] Explanation of the reference numerals: 1. first housing; 2. second housing; 3. air inlet pipe; 4. exhaust pipe; 5. connecting piece; 51. guide rod; 52. ventilation cone; 53. hose; 54. float; 6. cooling mechanism; 61. cooling water; 62. refrigeration component; 621. refrigeration pipe; 622. temperature sensor; 63. spray assembly; 631. cooling plate; 632. spray pipe; 633. spray blade; 634. spray hole; 635. water supply component; 6351. water pump; 6352. water supply pipe; 7. drain pipe; 8. baffle; 9. filter screen; 10. liquid level sensor; 11. drain pipe; 12. electric control valve; 13. partition frame; 14. sponge block. DETAILED DESCRIPTION

[0033] The following is combined with Figure 1-3 This application is described in further detail.

[0034] The embodiment of the present application discloses a counter-flow spray cooling tower.

[0035] Reference Figure 1 A countercurrent spray cooling tower comprises a first box body 1 and a second box body 2. An air inlet pipe 3 for circulating humid hot air is arranged on the top of the first box body 1. An exhaust pipe 4 is connected to the top of the second box body 2. A partition frame 13 is bolted inside the second box body 2. A sponge block 14 is arranged on the partition frame 13. The circumferential outer wall of the sponge block 14 abuts against the circumferential inner wall of the second box body 2.

[0036] Reference Figure 1 , Figure 2 and Figure 3 The bottom connection between the first box body 1 and the second box body 2 is open and a filter screen 9 is bolted at the opening. A liquid level sensor 10 electrically connected to the control system is bolted inside the second box body 2. A drain pipe 11 is connected to the second box body 2, and an electric control valve 12 electrically connected to the control system is arranged on the drain pipe 11.

[0037] Reference Figure 1 , Figure 2 and Figure 3 A connecting piece 5 for ventilation is arranged between the first box body 1 and the second box body 2. The connecting piece 5 includes a vertical guide rod 51 welded to the bottom of the first box body 1. A ventilation cone 52 is slidably arranged on the guide rod 51. The diameter of the ventilation cone 52 gradually increases from top to bottom. One end of the ventilation cone 52 is close to the water surface of the cooling water 61, and the other end is connected to a hose 53. The hose 53 is connected to the second box body 2. The connection point between the hose 53 and the second box body 2 is located below the sponge block 14. A float 54 is welded to the end of the ventilation cone 52 close to the cooling water 61.

[0038] As the hot and humid air continuously rushes into the first box body 1, the hot and humid air condenses and causes the water level of the cooling water 61 in the first box body 1 to rise, and the float 54 drives the ventilation cone 52 to slide on the guide rod 51, so that the bottom end opening of the ventilation cone 52 is always close to the water surface of the cooling water 61, and the cooled air in the first box body 1 flows into the second box body 2 through the hose 53, and is discharged from the exhaust pipe 4 after being adsorbed by the sponge block 14.

[0039] The first box body 1 passes through the filter net 9, so that the water level of the cooling water 61 in the second box body 2 rises synchronously. When the cooling water 61 in the second box body 2 triggers the liquid level sensor 10, the liquid level sensor 10 feeds back the signal to the control system, and the control system starts the electric control valve 12. The drain pipe 11 discharges the cooling water 61 inside the second box body 2 to the external collection box until the cooling water 61 inside the second box body 2 can no longer trigger the liquid level sensor 10, thereby reducing the water level of the cooling water 61 inside the second box body 2.

[0040] Reference Figure 1 , Figure 2 and Figure 3 The first box body 1 is provided with a cooling mechanism 6 for removing heat from the humid hot air. The cooling mechanism 6 includes cooling water 61 filled in the first box body 1. The first box body 1 is provided with a refrigeration component 62 for cooling the cooling water 61. The refrigeration component 62 includes a refrigeration pipe 621 bolted in the first box body 1 and electrically connected to the control system. The refrigeration pipe 621 is immersed in the cooling water 61. A temperature sensor 622 electrically connected to the control system is bolted in the first box body 1.

[0041] The temperature sensor 622 feeds back the temperature of the cooling water 61 in the first box 1 to the control system. The control system supplies power to the refrigeration pipe 621 for refrigeration, so that the temperature of the cooling water 61 is always maintained within a certain temperature range.

[0042] Reference Figure 1 , Figure 2 and Figure 3 A spray assembly 63 for extracting cooling water 61 for cooling is arranged on the first box body 1. The spray assembly 63 includes a plurality of cooling plates 631 bolted to the first box body 1. The plurality of cooling plates 631 are arranged from top to bottom. The cooling plates 631 are hollow inside. The cooling plates 631 are connected to a plurality of vertical spray pipes 632. The spray pipes 632 are rotatably provided with inclined spray blades 633.

[0043] Reference Figure 1 , Figure 2 and Figure 3 A spray hole 634 communicating with the spray pipe 632 is provided on the spray blade 633, and the spray direction of the spray hole 634 is perpendicular to the inclination direction of the spray blade 633. A water supply component 635 for supplying water to the cooling plate 631 is arranged on the first box body 1. The water supply component 635 includes a water pump 6351 bolted to the first box body 1 and electrically connected to the control system. A water supply pipe 6352 is connected between the water pump 6351 and the cooling plate 631, and between the water pump 6351 and the first box body 1.

[0044] Reference Figure 1 , Figure 2 and Figure 3 The circumferential side walls of the cooling plate 631 are tightly attached to the circumferential inner walls of the first box body 1. A vertical drain pipe 7 connecting the top and bottom of the cooling plate 631 is welded on the cooling plate 631. The diameter of the drain pipe 7 gradually decreases from top to bottom. A baffle 8 is welded to the bottom of the cooling plate 631. The baffle 8 is located at the liquid outlet of the drain pipe 7 and there is a distance between the baffle 8 and the liquid outlet of the drain pipe 7.

[0045] The worker starts the water pump 6351 through the control system. The water pump 6351 pumps the cooling water 61 in the first box body 1 to the inside of the cooling plate 631 through the water supply pipe 6352, so that a higher water pressure is maintained inside the cooling plate 631. When the cooling water 61 is sprayed out from the spray hole 634 on the spray blade 633 through the spray pipe 632, the reaction force of the cooling water 61 sprayed from the spray hole 634 pushes the spray blade 633 to rotate. The rotation of the spray blade 633 will fully mix the water mist and humid hot air inside the first box body 1.

[0046] In this way, the hot and humid air is cooled. As the cooling water 61 is continuously sprayed out from the spray holes 634 on the spray blades 633 and the hot and humid air is continuously filled into the first box body 1, the internal pressure of the cavity surrounded by the first box body 1 and the cooling plate 631 increases rapidly. When the gas with a certain pressure is discharged from the drain pipe 7, the liquefied cooling water 61 on the top of the cooling plate 631 is driven by the high-pressure gas and discharged from the drain pipe 7.

[0047] And it impacts the baffle 8 at the bottom of the cooling plate 631 to form water mist again, so that the water mist sprayed from a cooling plate 631 below the cooling plate 631 flows upward against the flow and mixes with it. Since the temperature of the water mist sprayed from the cooling plate 631 below is lower than the temperature of the water mist formed by blocking the baffle 8, the cooled air is cooled again.

[0048] Through repeated cooling by multiple cooling plates 631, the moisture in the humid hot air is further quickly condensed and liquefied. When the water mist is discharged from the drain pipe 7 on the bottom cooling plate 631, the temperature of the formed water mist is close to the temperature of the cooling water 61, and the moisture in the air will quickly liquefy into the cooling water 61.

[0049] The implementation principle of a countercurrent spray cooling tower in an embodiment of the present application is as follows: a worker starts a water pump 6351 through a control system, and the water pump 6351 pumps the cooling water 61 in the first box body 1 to the inside of the cooling plate 631 through a water supply pipe 6352, so that a higher water pressure is maintained inside the cooling plate 631. When the cooling water 61 is sprayed out from the spray hole 634 on the spray blade 633 through the spray pipe 632, the reaction force of the cooling water 61 sprayed from the spray hole 634 pushes the spray blade 633 to rotate, and the rotation of the spray blade 633 will fully mix the water mist and humid hot air inside the first box body 1.

[0050] In this way, the hot and humid air is cooled. As the cooling water 61 is continuously sprayed out from the spray holes 634 on the spray blades 633 and the hot and humid air is continuously filled into the first box body 1, the internal pressure of the cavity surrounded by the first box body 1 and the cooling plate 631 increases rapidly. When the gas with a certain pressure is discharged from the drain pipe 7, the liquefied cooling water 61 on the top of the cooling plate 631 is driven by the high-pressure gas and discharged from the drain pipe 7.

[0051] And it impacts the baffle 8 at the bottom of the cooling plate 631 to form water mist again, so that the water mist sprayed from a cooling plate 631 below the cooling plate 631 flows upward against the flow and mixes with it. Since the temperature of the water mist sprayed from the cooling plate 631 below is lower than the temperature of the water mist formed by blocking the baffle 8, the cooled air is cooled again.

[0052] Through repeated cooling by multiple cooling plates 631, the moisture in the humid hot air is further quickly condensed and liquefied. When the water mist is discharged from the drain pipe 7 on the bottom cooling plate 631, the temperature of the formed water mist is close to the temperature of the cooling water 61, and the moisture in the air will quickly liquefy into the cooling water 61.

[0053] As the hot and humid air continuously rushes into the first box body 1, the hot and humid air condenses and causes the water level of the cooling water 61 in the first box body 1 to rise, and the float 54 drives the ventilation cone 52 to slide on the guide rod 51, so that the bottom end opening of the ventilation cone 52 is always close to the water surface of the cooling water 61, and the cooled air in the first box body 1 flows into the second box body 2 through the hose 53, and is discharged from the exhaust pipe 4 after being adsorbed by the sponge block 14.

[0054] The first box body 1 passes through the filter net 9, so that the water level of the cooling water 61 in the second box body 2 rises synchronously. When the cooling water 61 in the second box body 2 triggers the liquid level sensor 10, the liquid level sensor 10 feeds back the signal to the control system, and the control system starts the electric control valve 12. The drain pipe 11 discharges the cooling water 61 inside the second box body 2 to the external collection box until the cooling water 61 inside the second box body 2 can no longer trigger the liquid level sensor 10, thereby reducing the water level of the cooling water 61 inside the second box body 2.

[0055] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A countercurrent spray cooling tower, characterized in that: The invention comprises a first box body (1) and a second box body (2), wherein the first box body (1) is provided with an air inlet pipe (3) for circulating moist hot air, the second box body (2) is provided with an exhaust pipe (4), a connecting piece (5) for ventilation is provided between the first box body (1) and the second box body (2), the first box body (1) is provided with a cooling mechanism (6) for removing heat from the moist hot air, the cooling mechanism (6) comprises cooling water (61) arranged in the first box body (1), a refrigeration element (62) for cooling the cooling water (61) is provided on the first box body (1), and a spray assembly (63) for extracting the cooling water (61) for cooling is provided on the first box body (1).

2. A counter-current spray cooling tower according to claim 1, characterized in that: The refrigeration component (62) comprises a refrigeration pipe (621) arranged in the first box (1) and electrically connected to the control system, the refrigeration pipe (621) is immersed in cooling water (61), and a temperature sensor (622) electrically connected to the control system is arranged in the first box (1).

3. A counter-current spray cooling tower according to claim 1, characterized in that: The spray assembly (63) comprises a plurality of cooling plates (631) arranged in a first housing (1), the plurality of cooling plates (631) being arranged in a direction from top to bottom, the cooling plates (631) being hollow inside, the cooling plates (631) being connected to a plurality of spray pipes (632), the spray pipes (632) being rotatably provided with inclined spray blades (633), the spray blades (633) being provided with spray holes (634) communicating with the spray pipes (632), the spray direction of the spray holes (634) being perpendicular to the inclined direction of the spray blades (633), and the first housing (1) being provided with a water supply component (635) for supplying water to the cooling plates (631).

4. A counter-current spray cooling tower according to claim 3, characterized in that: The water supply component (635) comprises a water pump (6351) which is arranged on the first housing (1) and is electrically connected to the control system. A water supply pipe (6352) is connected between the water pump (6351) and the cooling plate (631), and between the water pump (6351) and the first housing (1).

5. A counter-current spray cooling tower according to claim 3, characterized in that: The circumferential side wall of the cooling plate (631) is tightly attached to the circumferential inner side wall of the first box body (1); a liquid discharge pipe (7) is provided on the cooling plate (631) and is connected to the top and bottom of the cooling plate (631); the diameter of the liquid discharge pipe (7) gradually decreases from top to bottom; a baffle (8) is provided at the bottom of the cooling plate (631); the baffle (8) is located at the liquid outlet of the liquid discharge pipe (7) and there is a gap between the baffle (8) and the liquid outlet of the liquid discharge pipe (7).

6. A counter-current spray cooling tower according to claim 1, characterized in that: The connecting member (5) comprises a vertical guide rod (51) arranged at the bottom of the first box body (1), a vent cone (52) being slidably arranged on the guide rod (51), one end of the vent cone (52) being close to the water surface of the cooling water (61), and the other end being connected to a hose (53), the hose (53) being connected to the second box body (2), and a float ball (54) being arranged on the end of the vent cone (52) close to the cooling water (61).

7. A counter-flow spray cooling tower according to claim 6, characterized in that: The diameter of the ventilation cone (52) gradually increases from top to bottom.

8. A counter-flow spray cooling tower according to claim 1, characterized in that: The bottom connection between the first box body (1) and the second box body (2) is open and provided with a filter screen (9); a liquid level sensor (10) electrically connected to a control system is provided in the second box body (2); a drainage pipe (11) is connected to the second box body (2); and an electric control valve (12) electrically connected to the control system is provided on the drainage pipe (11).

9. A counter-flow spray cooling tower according to claim 6, characterized in that: A partition frame (13) is arranged in the second box body (2), and a sponge block (14) is arranged on the partition frame (13). The sponge block (14) is located above the connection point between the hose (53) and the second box body (2), and the circumferential outer side wall of the sponge block (14) abuts against the circumferential inner side wall of the second box body (2).

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