Low closed counterflow closed cooling tower

Abstract

The utility model relates to the technical field of cooling towers, and provides a low closed countercurrent closed cooling tower which comprises a tower body, a frame plate fixedly connected to the inner side of the tower body, a heat exchange coil fixedly installed on the frame plate, an air inlet pipe fixedly connected to one end of the bottom of the tower body, and an air outlet pipe fixedly connected to the top of the tower body. A water spraying mechanism is arranged above the heat exchange coil pipe and comprises a guide seat, the bottom end of the guide seat is slidably connected with a flow dividing pipe, the bottom of the flow dividing pipe is fixedly connected with a plurality of spray heads, one end of the top of the tower body is fixedly connected with a water inlet pipe, and the bottom of the water inlet pipe is fixedly connected with a water guide hose; the outlet end of the water guiding hose communicates with the inlet end of the flow dividing pipe, and the top end of the flow dividing pipe is provided with a linkage piece which is started in cooperation with the air suction mechanism to drive the flow dividing pipe to reciprocate in the horizontal direction. The nozzle dynamically sprays water to cover the surface of the heat exchange coil, and the problem that a traditional fixed nozzle is insufficient in coverage is solved.

Description

TECHNICAL FIELD

[0001] The utility model relates to cooling tower technical field, specifically, relate to a low -profile closed -type counterflow closed cooling tower. BACKGROUND

[0002] Cooling tower is water as circulating coolant, from a system absorbs heat and discharges to the atmosphere, to reduce water temperature device, its cooling is the use of water and air flow contact after cold and hot exchange produces steam, steam volatilization takes away heat reaches the evaporation heat dissipation, convection heat transfer and radiation heat transfer etc. Principle to scatter the heat of industry or the heat of refrigeration air conditioning to reduce water temperature evaporation heat dissipation device, commonly used in central air conditioning cooling system, heating equipment cooling system etc. Field in life, cooling tower can be divided into many kinds, which open and closed are the most common two, compared with open cooling tower, closed counterflow cooling tower has the advantage of avoiding circulating water and air contact, guaranteeing the cleanliness of circulating water;

[0003] Through the retrieval, the "a counterflow closed cooling tower" in Chinese patent publication number (CN220322100U) is disclosed, including: tower body, the bottom of the tower body is provided with a water collecting pool, the water collecting pool is provided with a buffer assembly above, the buffer assembly is provided with a heat exchange coil above, the water collecting pool is communicated with a water pump on one side, the water pump is fixedly connected in the tower body, the water pump outlet is communicated with a water outlet pipeline, the water outlet pipeline passes through the inner wall of the tower body and extends to above the heat exchange coil, a plurality of spray heads are fixedly connected to the bottom of the water outlet pipeline above the heat exchange coil, a water collector is arranged above the spray heads, a top cover is arranged on the top of the tower body, an air outlet is fixedly installed in the middle of the top cover, and an air extractor is arranged in the air outlet, an air inlet is formed in the inner wall of the tower body between the buffer assembly and the heat exchange coil, and a filter assembly is fixedly connected to the outside of the air inlet.

[0004] However, in the implementation of the related technology, the patent has certain technical defects:

[0005] First, the patent supplies water to the spray head through the water pump, and then sprays water to the heat exchange coil for heat exchange, but there is a gap between adjacent spray heads, which makes the spray range density of the spray head unable to completely cover the heat exchange coil, thereby affecting the heat exchange efficiency.

[0006] Second, the patent uses a filter plate to filter the air entering the cooling tower, so that the particulate impurities in the air are filtered out, but the filtered impurities will adhere to the outer wall of the filter plate, and as the impurity accumulation increases, the filter holes of the filter plate are easily blocked, which affects the air inlet, so the filter plate needs to be replaced frequently, greatly increasing the labor intensity, therefore, the utility model provides a low -profile closed -type counterflow closed cooling tower. Utility model content

[0007] The utility model provides a low type closed reverse flow closed cooling tower has solved the problem that the water spraying range of the existing technology cannot cover heat exchange coil and influences heat exchange efficiency.

[0008] The utility model discloses a low type closed reverse flow closed cooling tower, including the tower body, the inside fixed connection of tower body has the shelf, the fixed mounting of heat exchange coil has on the shelf, the bottom fixed connection of tower body one end has the air inlet pipe, the top fixed connection of tower body has the air outlet pipe, the top of air outlet pipe inside sets up the air suction mechanism for the air extraction of tower body inside, the top of heat exchange coil is provided with the water spraying mechanism, the water spraying mechanism includes the fixed connection of the guide seat in the inside of tower body, the bottom sliding connection of guide seat has the horizontally arranged shunt pipe, the bottom fixed connection of shunt pipe has a plurality of equidistance distribution's shower nozzle along the horizontal direction, the top fixed connection of tower body one end has the water inlet pipe, the bottom fixed connection of water inlet pipe has the water guide hose, the export end of water guide hose is connected with the import end of shunt pipe, the top of shunt pipe is provided with the linkage through the cooperation air suction mechanism starts to drive shunt pipe and reciprocating activity in the horizontal direction.

[0009] Preferably, the air suction mechanism includes a bracket fixedly connected to the top of the tower body, one end of the top of the bracket is fixedly installed with a motor, the output shaft of the motor is fixedly connected with a rotating shaft, and the top of the rotating shaft is fixedly connected with an air suction impeller.

[0010] Preferably, a plurality of inclined baffles are fixedly connected to the inside of the air outlet pipe, and the plurality of baffles are equidistantly and staggeredly distributed along the vertical direction.

[0011] Preferably, the linkage includes an eccentric wheel fixedly connected to the bottom of the rotating shaft, a connecting rod is rotatably connected to the outer edge of the eccentric wheel, one end of the connecting rod away from the eccentric wheel is rotatably connected with a sleeve seat, and the sleeve seat is fixedly connected to the outside of the shunt pipe.

[0012] Preferably, a filter screen is fixedly connected to the inside of the air inlet pipe, a cleaning assembly is arranged on one side of the filter screen, the cleaning assembly includes a sliding rod penetrating through the top wall of the air inlet pipe, the sliding rod is slidingly connected with the top wall of the air inlet pipe, the bottom end of the sliding rod is fixedly connected with a mounting seat, one end of the mounting seat is fixedly connected with a brush plate inside, the bristle part of the brush plate abuts against the outer wall of the filter screen, and the top end of the sliding rod is provided with a pushing piece for driving the sliding rod to reciprocatingly slide up and down by cooperating with the horizontal reciprocating movement of the shunt pipe.

[0013] Preferably, the pushing piece comprises a fixed seat fixedly connected to the inner wall of the tower body, the sliding rod penetrates through the fixed seat and is in sliding connection with the fixed seat, the top of the sliding rod is fixedly connected with an arc convex block, the end of the shunt pipe is fixedly connected with a pressing sleeve, the pressing sleeve intermittently abuts against the arc convex block by cooperating with the shunt pipe, a reset spring is sleeved on the sliding rod, the top end of the reset spring abuts against the arc convex block, and the bottom end of the reset spring abuts against the fixed seat.

[0014] Preferably, the bottom of the tower body is fixedly connected with a water collecting tank, and one end of the bottom of the water collecting tank is fixedly connected with a drain pipe.

[0015] Preferably, the inlet end of the water inlet pipe is provided with a water supply mechanism, the water supply mechanism comprises a water tank, the top end of the water tank is provided with a water filling opening, the outlet end of the water tank is fixedly connected with a water outlet pipe, the outlet end of the water outlet pipe is fixedly connected with a water pump, the outlet end of the water pump is fixedly connected with a water supply pipe, the outlet end of the water supply pipe is connected with the water inlet pipe, the outlet end of the drain pipe is fixedly connected with a backflow pipe, and the outlet end of the backflow pipe is connected with the inside of the water tank.

[0016] The working principle and beneficial effects of the low-height closed reverse-flow closed cooling tower are as follows:

[0017] 1. The horizontal reciprocating motion of the shunt pipe driven by the linkage (eccentric wheel, connecting rod and sleeve seat combination) drives the nozzle to dynamically cover the surface of the heat exchange coil, solves the problem of insufficient coverage of the traditional fixed nozzle, significantly improves the water spraying density and uniformity, ensures the formation of a water film, and enhances the evaporation heat dissipation efficiency.

[0018] 2. The horizontal motion of the shunt pipe drives the intermittent abutment of the pressing sleeve and the arc convex block, drives the brush plate to reciprocate up and down to clean the surface of the filter screen, and avoids the blockage of the filter hole by particulate matter. This design does not require additional power, realizes self-cleaning of the filter screen, reduces the frequency of manual cleaning and downtime maintenance time.

[0019] 3. The design of the staggered inclined baffles in the air outlet pipe effectively intercepts water vapor, promotes its condensation backflow to the water collecting tank, and circulates to the water supply system through the backflow pipe. Combined with the water spraying recovery mechanism, water resource waste is greatly reduced, and the sustainability of the system is improved. BRIEF DESCRIPTION OF DRAWINGS

[0020] The low-height closed reverse-flow closed cooling tower will be further described in detail in combination with the drawings and specific embodiments.

[0021] Figure 1 It is a structure schematic view of the low-height closed reverse-flow closed cooling tower of the utility model;

[0022] Figure 2 It is an internal structure schematic view of the tower body of the utility model;

[0023] Figure 3It is a structure schematic view of the water spraying mechanism of the utility model.

[0024] Figure 4 It is a structure schematic view of the air suction mechanism of the utility model.

[0025] Figure 5 It is an internal structure schematic view of the air outlet pipe of the utility model.

[0026] Figure 6 It is a structure schematic view of the linkage of the utility model.

[0027] Figure 7 It is a structure schematic view of the cleaning assembly of the utility model.

[0028] Figure 8 It is a structure schematic view of the water supply mechanism of the utility model.

[0029] In the drawing: 1, tower body; 2, shelf plate; 3, heat exchange coil; 4, air inlet pipe; 41, filter screen; 42, cleaning assembly; 421, sliding rod; 422, mounting seat; 423, brush plate; 424, fixing seat; 425, cambered convex block; 426, pressing sleeve; 427, return spring; 5, air outlet pipe; 51, baffle; 6, air suction mechanism; 61, support; 62, motor; 63, rotating shaft; 64, air suction impeller; 7, water spraying mechanism; 71, guide seat; 72, shunt pipe; 73, spray head; 74, water inlet pipe; 75, water guide hose; 76, linkage; 761, eccentric wheel; 762, connecting rod; 763, sleeve seat; 8, water collecting tank; 9, drain pipe; 10, water supply mechanism; 101, water tank; 102, water pump; 103, water outlet pipe; 104, water supply pipe; 105, backflow pipe; 106, water filling port. DETAILED DESCRIPTION

[0030] The technical scheme in the embodiments of the utility model will be described clearly and completely below in conjunction with the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative labor are involved in the protection scope of the utility model.

[0031] For example, Figures 1-8As shown, the embodiment proposes a low type closed countercurrent closed cooling tower, which comprises a tower body 1, the inner side of the tower body 1 is fixedly connected with a shelf plate 2, the shelf plate 2 is fixedly installed with a heat exchange coil pipe 3, one end of the bottom of the tower body 1 is fixedly connected with an air inlet pipe 4, the top of the tower body 1 is fixedly connected with an air outlet pipe 5, the top end of the inner side of the air outlet pipe 5 is provided with a air suction mechanism 6 for sucking the air inside the tower body 1, the top of the heat exchange coil pipe 3 is provided with a water spraying mechanism 7, the water spraying mechanism 7 comprises a guide seat 71 fixedly connected inside the tower body 1, the bottom end of the guide seat 71 is slidably connected with a horizontally arranged shunt pipe 72, the bottom of the shunt pipe 72 is fixedly connected with a plurality of water spraying heads 73 equidistantly distributed along the horizontal direction, one end of the top of the tower body 1 is fixedly connected with a water inlet pipe 74, the bottom of the water inlet pipe 74 is fixedly connected with a water guide hose 75, the outlet end of the water guide hose 75 is communicated with the inlet end of the shunt pipe 72, and the top end of the shunt pipe 72 is provided with a linkage 76 which is started by cooperating with the air suction mechanism 6 to drive the shunt pipe 72 to reciprocate in the horizontal direction.

[0032] The cooling water is introduced into the water guide hose 75 through the water inlet pipe 74, then introduced into the shunt pipe 72 through the water guide hose 75, and then sprayed onto the outer surface of the heat exchange coil pipe 3 through the water spraying heads 73 to form a water film for evaporation heat dissipation, while the air inside the tower body 1 is discharged and the heat is discharged by starting the air suction mechanism 6, so that the linkage 76 drives the shunt pipe 72 to reciprocate in the horizontal direction, so that all the water spraying heads 73 move in the horizontal direction, so that the water spraying heads 73 spray water in the horizontal direction, thereby greatly improving the water spraying density of the water spraying heads 73, so that the water spraying range of the water spraying heads 73 can completely cover the length range of the heat exchange coil pipe 3, thereby effectively improving the heat exchange efficiency.

[0033] Further, the air suction mechanism 6 comprises a bracket 61 fixedly connected at the top of the tower body 1, one end of the top of the bracket 61 is fixedly installed with a motor 62, the output shaft of the motor 62 is fixedly connected with a rotating shaft 63, the top end of the rotating shaft 63 is fixedly connected with a air suction impeller 64, and the air suction impeller 64 is located at the top end of the inner side of the air outlet pipe 5.

[0034] By starting the motor 62 to drive the rotating shaft 63 to rotate, the rotating shaft 63 drives the air suction impeller 64 to rotate synchronously, so that the outlet pressure of the air outlet pipe 5 is reduced, so that the air inside the tower body 1 is discharged outward and the new cold air is introduced by the air inlet pipe 4, so that the air flow speed inside the tower body 1 can be accelerated, thereby improving the heat dissipation efficiency.

[0035] Further, a plurality of inclined baffles 51 are fixedly connected inside the air outlet pipe 5, and the plurality of baffles 51 are equidistantly and staggered distributed in the vertical direction. The inclined baffles 51 can effectively prevent water vapor from being discharged, so that the water vapor condenses into water droplets on the baffles 51 and falls back to be recycled, avoiding the waste of water source.

[0036] Further, the linkage 76 comprises an eccentric wheel 761 fixedly connected at the bottom of the rotating shaft 63, the outer edge of the eccentric wheel 761 is rotationally connected with a connecting rod 762, the end of the connecting rod 762 away from the eccentric wheel 761 is rotationally connected with a sleeve seat 763, and the sleeve seat 763 is fixedly connected at the outer side of the flow divider pipe 72.

[0037] By starting the motor 62 to drive the rotating shaft 63 to rotate, the eccentric wheel 761 is caused to rotate, and the connecting rod 762 drives the flow divider pipe 72 to rapidly reciprocate in the horizontal direction, so that the nozzle 73 reciprocates in the horizontal direction, the nozzle 73 performs dynamic water spraying in the horizontal direction, greatly improves the water spraying density of the nozzle 73, and the water spraying range of the nozzle 73 can completely cover the length range of the heat exchange coil 3, thereby effectively improving the heat exchange efficiency.

[0038] Further, the inner side of the air inlet pipe 4 is fixedly connected with a filter screen 41, one side of the filter screen 41 is provided with a cleaning assembly 42, the cleaning assembly 42 comprises a sliding rod 421 penetrating through the top wall of the air inlet pipe 4, the sliding rod 421 is slidingly connected with the top wall of the air inlet pipe 4, the bottom end of the sliding rod 421 is fixedly connected with a mounting seat 422, one end of the mounting seat 422 is fixedly connected with a brush plate 423 inside, the bristle part of the brush plate 423 is in abutment with the outer wall of the filter screen 41, the top end of the sliding rod 421 is provided with a pushing piece for driving the sliding rod 421 to reciprocate up and down by cooperating with the horizontal reciprocating movement of the flow divider pipe 72, the pushing piece comprises a fixed seat 424 fixedly connected with the inner wall of the tower body 1, the sliding rod 421 penetrates through and is slidingly connected with the fixed seat 424, the top of the sliding rod 421 is fixedly connected with an arc convex block 425, the end of the flow divider pipe 72 is fixedly connected with a pressing sleeve 426, the pressing sleeve 426 is intermittently in abutment with the arc convex block 425 by cooperating with the movement of the flow divider pipe 72, the sliding rod 421 is sleeved with a return spring 427, the top end of the return spring 427 is in abutment with the arc convex block 425, and the bottom end of the return spring 427 is in abutment with the fixed seat 424.

[0039] During the reciprocating sliding of the flow divider pipe 72 in the horizontal direction, the pressing sleeve 426 will reciprocate synchronously with the flow divider pipe 72, when the pressing sleeve 426 is in abutment with the arc convex block 425, the arc convex block 425 is extruded to drive the sliding rod 421 to move downward, at this time the return spring 427 is compressed to accumulate potential energy, when the pressing sleeve 426 is disengaged from the arc convex block 425, the return spring 427 releases the potential energy to make the sliding rod 421 move upward, and the cycle is repeated, so that the sliding rod 421 reciprocates up and down, and the brush plate 423 reciprocates along the outer wall of the filter screen 41, so that the brush plate 423 can dynamically clean the outer wall of the filter screen 41, effectively avoiding the problem that the filter holes of the filter screen 41 are blocked to affect air intake, greatly reducing the replacement frequency of the filter screen 41 and reducing the labor intensity.

[0040] Furthermore, a water collection tank 8 is fixedly connected to the bottom of the tower body 1, and a drain pipe 9 is fixedly connected to one end of the bottom of the water collection tank 8. A water supply mechanism 10 is provided at the inlet end of the water inlet pipe 74. The water supply mechanism 10 includes a water tank 101. A water inlet 106 is opened at the top of the water tank 101. A water outlet pipe 103 is fixedly connected to the outlet end of the water tank 101. A water pump 102 is fixedly connected to the outlet end of the water outlet pipe 103. A water delivery pipe 104 is fixedly connected to the outlet end of the water pump 102. The outlet end of the water delivery pipe 104 is connected to the inlet pipe 74. A return pipe 105 is fixedly connected to the outlet end of the drain pipe 9. The outlet end of the return pipe 105 is connected to the inside of the water tank 101.

[0041] Working principle: First, the water pump 102 is started, which causes the outlet pipe 103 to guide the cooling water inside the water tank 101 into the water supply pipe 104. Then, the cooling water is guided through the water supply pipe 104 into the water inlet pipe 74, and through the water inlet pipe 74 into the water guide hose 75. Then, the cooling water is guided through the water guide hose 75 into the distribution pipe 72. Then, the cooling water is sprayed onto the outer surface of the heat exchange coil 3 through each nozzle 73 to form a water film for evaporation and heat dissipation. At the same time, the starter motor 62 is started to drive the rotating shaft 63 to rotate. The rotating shaft 63 drives the suction impeller 64 to rotate synchronously, which reduces the outlet pressure of the air outlet pipe 5, causing the air inside the tower body 1 to be discharged to the outside and the air inlet pipe 4 to introduce new cold air. This can accelerate the air flow speed inside the tower body 1, thereby improving the heat dissipation efficiency.

[0042] When the rotating shaft 63 rotates, it synchronously drives the eccentric wheel 761 to rotate, which causes the connecting rod 762 to drive the diversion pipe 72 to slide back and forth quickly in the horizontal direction. This causes the nozzle 73 to reciprocate in the horizontal direction and spray water dynamically in the horizontal direction, which greatly increases the spray density of the nozzle 73. This allows the spray range of the nozzle 73 to completely cover the length of the heat exchange coil 3, thereby effectively improving the heat exchange efficiency.

[0043] When the water sprayed from the nozzle 73 comes into contact with the heat exchange coil 3, it will form water vapor. The water vapor will condense into water droplets and eventually drip into the water collection tank 8 for collection. Then, it will be reintroduced into the water tank 101 through the return pipe 105 for recycling, effectively saving water resources.

[0044] The above are merely preferred embodiments of the present utility model and are not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. A low-profile closed-loop counter-flow cooling tower, comprising a tower body (1), wherein a frame plate (2) is fixedly connected to the inner side of the tower body (1), a heat exchange coil (3) is fixedly installed on the frame plate (2), an air inlet pipe (4) is fixedly connected to one end of the bottom of the tower body (1), and an air outlet pipe (5) is fixedly connected to the top of the tower body (1), characterized in that, The top of the inner side of the air outlet pipe (5) is provided with a suction mechanism (6) for drawing out the air inside the tower body (1). A water spraying mechanism (7) is provided above the heat exchange coil (3). The water spraying mechanism (7) includes a guide seat (71) fixedly connected to the inner side of the tower body (1). A horizontally arranged diversion pipe (72) is slidably connected to the bottom of the guide seat (71). Several nozzles (73) are fixedly connected to the bottom of the diversion pipe (72) at equal intervals along the horizontal direction. A water inlet pipe (74) is fixedly connected to one end of the top of the tower body (1). A water guide hose (75) is fixedly connected to the bottom of the water inlet pipe (74). The outlet end of the water guide hose (75) is connected to the inlet end of the diversion pipe (72). A linkage (76) is provided at the top of the diversion pipe (72) to drive the diversion pipe (72) to reciprocate in the horizontal direction by cooperating with the suction mechanism (6).

2. The low-profile closed-loop counter-flow cooling tower according to claim 1, characterized in that, The suction mechanism (6) includes a bracket (61) fixedly connected to the top of the tower body (1). A motor (62) is fixedly installed at one end of the top of the bracket (61). A rotating shaft (63) is fixedly connected to the output shaft of the motor (62). A suction impeller (64) is fixedly connected to the top of the rotating shaft (63).

3. A low-profile closed-loop counter-flow cooling tower according to claim 2, characterized in that, The air outlet pipe (5) has several inclined baffles (51) fixedly connected to its inner side, and the baffles (51) are equidistantly and alternately distributed along the vertical direction.

4. A low-profile closed-loop counter-flow cooling tower according to claim 2, characterized in that, The linkage (76) includes an eccentric wheel (761) fixedly connected to the bottom of the rotating shaft (63), a connecting rod (762) rotatably connected to the outer edge of the eccentric wheel (761), and a sleeve (763) rotatably connected to the end of the connecting rod (762) away from the eccentric wheel (761), and the sleeve (763) fixedly connected to the outside of the diversion pipe (72).

5. A low-profile closed-loop counter-flow cooling tower according to claim 1, characterized in that, A filter screen (41) is fixedly connected to the inner side of the air intake pipe (4). A cleaning component (42) is provided on one side of the filter screen (41). The cleaning component (42) includes a slide rod (421) that penetrates the top wall of the air intake pipe (4). The slide rod (421) is slidably connected to the top wall of the air intake pipe (4). A mounting base (422) is fixedly connected to the bottom end of the slide rod (421). A brush plate (423) is fixedly connected to one end of the mounting base (422). The bristles of the brush plate (423) abut against the outer wall of the filter screen (41). A pusher is provided at the top of the slide rod (421) to drive the slide rod (421) to slide up and down by cooperating with the horizontal reciprocating movement of the diversion pipe (72).

6. A low-profile closed-loop counter-flow cooling tower according to claim 5, characterized in that, The jacking component includes a fixed seat (424) fixedly connected to the inner wall of the tower body (1). The sliding rod (421) passes through the fixed seat (424) and is slidably connected to the fixed seat (424). An arc-shaped protrusion (425) is fixedly connected to the top of the sliding rod (421). A pressure sleeve (426) is fixedly connected to the end of the diversion pipe (72). The pressure sleeve (426) intermittently contacts the arc-shaped protrusion (425) by cooperating with the movement of the diversion pipe (72). A return spring (427) is sleeved on the sliding rod (421). The top of the return spring (427) contacts the arc-shaped protrusion (425), and the bottom of the return spring (427) contacts the fixed seat (424).

7. A low-profile closed-loop counter-flow cooling tower according to claim 1, characterized in that, A water collection tank (8) is fixedly connected to the bottom of the tower body (1), and a drain pipe (9) is fixedly connected to one end of the bottom of the water collection tank (8).

8. A low-profile closed-loop counter-flow cooling tower according to claim 7, characterized in that, The inlet end of the water inlet pipe (74) is provided with a water supply mechanism (10). The water supply mechanism (10) includes a water tank (101). The top of the water tank (101) is provided with a water inlet (106). The outlet end of the water tank (101) is fixedly connected to a water outlet pipe (103). The outlet end of the water outlet pipe (103) is fixedly connected to a water pump (102). The outlet end of the water pump (102) is fixedly connected to a water delivery pipe (104). The outlet end of the water delivery pipe (104) is connected to the inlet pipe (74). The outlet end of the drain pipe (9) is fixedly connected to a return pipe (105). The outlet end of the return pipe (105) is connected to the inside of the water tank (101).

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