Circulating pump system

Abstract

The invention provides a circulating pump system, which relates to the technical field of circulating pump water delivery and comprises a circulating pump used for delivering fluid from a low position to a high position or enabling the fluid to circularly flow in a pipeline; the pipeline is a fluid conveying channel and is used for connecting the circulating pump and various devices so as to ensure that the fluid can smoothly and circularly flow; the valve is used for controlling the flow, the pressure and the direction of the fluid, and the valve is connected to the pipeline; and the control device is used for monitoring and controlling the running state of the circulating pump system, the running state comprises starting and stopping of the motor and the flow and pressure of fluid, and the circulating pump and the valve are electrically connected with the control device. The circulating pump is controlled through the control device, the pipeline and the valve, the technical problems that in the water conveying process of an existing circulating pump, resource waste is likely to be caused, and waste heat loss is serious after the waste water treatment pressure is large are effectively solved, and intelligent adjustment can be conducted according to the actual water conveying state of the circulating pump.

Description

Technical Field

[0001] The invention relates to the technical field of circulating pump water delivery, in particular to a circulating pump system. Background Art

[0002] The circulation pump system is based on the principles of fluid dynamics and mechanical motion. Specifically, the circulation pump creates a certain negative pressure in the pump body through rotating mechanical parts (such as impellers) to extract the fluid. After the fluid is sucked into the pump body, the rotation of the impeller pushes the fluid to the outlet through centrifugal force. The pushed fluid leaves the pump body through the outlet and enters the inlet of the system pipeline or equipment, thereby realizing the circulation of the fluid. This system is widely used in many fields such as chemical industry, petroleum, electricity, food, heating, air conditioning, etc.

[0003] At present, since the circulating pump needs to transport hot water when delivering water, the circulating pump system cannot guarantee the quality of hot water when transporting hot water, and it will also cause water quality loss of hot water, and cannot achieve high-quality recycling of circulating water, resulting in a large amount of water resource waste, while increasing the pressure of wastewater treatment during the hot water circulation process, and also affecting the working efficiency of the circulating pump system's water quality circulation. Therefore, a circulating pump system is proposed to address the above problems. Summary of the invention

[0004] The present invention provides a circulation pump system to solve at least one of the problems raised by the above background technology.

[0005] In order to solve the above technical problems, the present invention discloses a circulation pump system, comprising:

[0006] Circulation pumps are used to transport fluids from a low place to a high place, or to circulate fluids in a pipeline;

[0007] Pipeline: Pipeline is a channel for fluid transportation, used to connect circulation pumps and various equipment to ensure that the fluid can circulate smoothly;

[0008] Valves are used to control the flow, pressure and direction of fluids. Valves are connected to pipelines.

[0009] The control device is used to monitor and control the operating status of the circulation pump system, including the start and stop of the motor, the flow rate and pressure of the fluid. The circulation pump and the valve are electrically connected to the control device respectively.

[0010] Preferably, the water inlet of the circulation pump is connected to a return pipe, and the water outlet of the circulation pump is connected to the heater through a delivery pipe, the water outlet at the top of the heater is connected to a water outlet pipe, and the water outlet of the water outlet pipe is connected to a water supply mechanism, and a water outlet valve is provided on the water outlet pipe.

[0011] Preferably, the water supply mechanism includes four three-way solenoid valves and four relays, and the water outlets of the water outlet pipes are respectively arranged with four three-way solenoid valves at intervals, the water inlets of the three-way solenoid valves are connected to the water outlets of the water outlet pipes, and the four three-way solenoid valves are respectively electrically connected to the four relays in a one-to-one correspondence.

[0012] Preferably, it also includes a plurality of low-temperature pipes and a plurality of high-temperature pipes, the water inlets of the plurality of low-temperature pipes are connected one-to-one to the first water outlet of the three-way solenoid valve, and the water inlets of the plurality of high-temperature pipes are connected one-to-one to the other water outlet of the three-way solenoid valve, the low-temperature pipes are used to transport circulating water to the circulating water low-temperature pipes, and the high-temperature pipes are used to transport circulating water to the circulating water high-temperature pipes.

[0013] Preferably, the three-way solenoid valve is a 24VDC model, which is an electromagnetic proportional valve controlled by a 24V DC signal, each of which is provided with a water inlet and two water outlets, and the relay is a 24VDC model.

[0014] Preferably, the first water outlet at the bottom of the heater is connected to the water inlet of the drain pump through a first water pipe, and the water outlet of the drain pump is connected to the water inlet of the water make-up tank through a delivery pipe 2, the middle part of the delivery pipe 2 is connected to the water supply heating network through a delivery pipe 3, and the water outlet of the water make-up tank is connected to the return pipe through a delivery pipe 4.

[0015] Preferably, it also includes a first electric regulating valve and a second electric regulating valve, the first electric regulating valve is arranged on the delivery pipeline 2 between the drain pump and the delivery pipeline 3, and the second electric regulating valve is arranged on the delivery pipeline 3, and the flow regulating valve is arranged between the delivery pipeline 3 and the water replenishment tank.

[0016] Preferably, it also includes a drain tank, the water inlet of the expansion tank is connected to the second water outlet at the bottom of the heater through a second water supply pipe, the water outlet of the expansion tank is connected to the drain tank through a pipeline, and the water outlet of the drain tank is respectively connected to the first drain pipe and the second drain pipe, the first drain pipe is sequentially provided with a first drain pump, a first manual regulating valve, a first check valve and a third electric regulating valve, the second drain pipe is sequentially provided with a second drain pump, a second manual regulating valve, a second check valve and a fourth electric regulating valve, the water outlets of the first drain pipe and the second drain pipe are connected to the return pipe through a third supply pipe, and the third drain pipe is provided with a third check valve.

[0017] The circulating pump system provided by the present invention has the following beneficial effects compared with the prior art:

[0018] 1. The above-mentioned circulation pump system controls the circulation pump through the control device, valve and pipeline. When the circulation pump system is blocked during water delivery, it can deal with the blockage in time and can make intelligent adjustments according to the actual working state of the water delivery pipeline. The operation is simple and convenient, which effectively improves the stability and accuracy of the circulation pump system.

[0019] 2. The above-mentioned circulating pump system can, while flushing the heater body, deliver circulating water with high-quality heat to the heater through the circulating pump, increase the initial temperature of the return water, and deliver it to the water supply mechanism after heating; the normal setting of the drain tank can flush the pipes between the heater and the drain pump and the pipes between the drain pump and the water supply heating network, and make the flushing water with high-quality heat flow into the make-up water tank, flow from the make-up water tank into the circulating pump and then enter the water inlet of the heater, increase the initial temperature of the return water, and deliver it to the water supply mechanism after heating to cooperate with the circulation pump in delivering the circulating water. The above-mentioned can effectively utilize the heat of the flushing water for heating, reduce the wastewater discharge and treatment pressure of the heating power plant, and further reduce the coal consumption of the heating unit. Compared with the existing technology, it has the advantages of high comprehensive utilization rate, water resource saving, and stable operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 A schematic structural diagram of a circulation pump system provided by an embodiment of the present invention;

[0022] Figure 2 A schematic structural diagram of the water delivery operation of the circulating pump system provided in an embodiment of the present invention.

[0023] Reference numerals:

[0024] 1. Circulation pump; 2. Return pipe; 3. Delivery pipeline 1; 4. Heater; 5. Outlet pipe; 6. Water supply mechanism; 7. Outlet valve; 8. Three-way solenoid valve; 9. Relay; 10. Low-temperature pipeline; 11. High-temperature pipeline; 12. First water pipeline; 13. Drain pump; 14. Delivery pipeline 2; 15. Make-up water tank; 16. Delivery pipeline 3; 17. Water supply and heating network; 18. Delivery pipeline 4; 19. First electric regulating valve; 20. Second electric Regulating valve; 21. Flow regulating valve; 22. Expansion box; 23. Second water delivery pipe; 24. Drain box; 25. First drainage pipe; 26. Second drainage pipe; 27. First drainage pump; 28. First manual regulating valve; 29. ​​First non-return valve; 30. Third electric regulating valve; 31. Second drainage pump; 32. Second manual regulating valve; 33. Second non-return valve; 34. Fourth electric regulating valve; 35. Third non-return valve; 36. Third delivery pipe. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] The present invention provides the following embodiments

[0027] Example 1

[0028] The embodiment of the present invention provides a circulation pump system, such as Figure 1 As shown, including:

[0029] Circulation pumps are used to transport fluids from a low place to a high place, or to circulate fluids in a pipeline;

[0030] Pipeline: Pipeline is a channel for fluid transportation, used to connect circulation pumps and various equipment to ensure that the fluid can circulate smoothly;

[0031] Valves are used to control the flow, pressure and direction of the fluid. Valves are connected to the pipeline to ensure the safe and stable operation of the circulation pump system;

[0032] The control device is used to monitor and control the operating status of the circulation pump system, including the start and stop of the motor, the flow rate and pressure of the fluid. The circulation pump and the valve are electrically connected to the control device respectively.

[0033] The working principle and beneficial effects of the above technical solution are:

[0034] The present invention provides a circulating pump system that controls a circulating pump 1 through intelligent control. The circulating pump 1 cooperates with valves and pipelines to transport circulating water, and the control device can periodically detect the valve and pipeline flow in real time, and adjust according to the current operating state to ensure the smooth flow of the pipeline and the stable operation of the circulating water transportation. The circulating pump 1 provided in the system is the core component of the system, which is responsible for transporting the fluid from a low place to a high place, or making the fluid circulate in the pipeline. According to the structure and characteristics, the circulating pump 1 can be divided into a plurality of types such as a centrifugal circulating pump 1 and a volumetric circulating pump 1; the pipeline is a channel for fluid transportation, connecting the circulating pump 1 and various equipment to ensure that the fluid can circulate smoothly; the valve is used to control the flow, pressure and direction of the fluid to ensure the safe and stable operation of the system; the control device is used to monitor and control the operating state of the circulating pump system, including the start and stop of the motor, the flow and pressure of the fluid and other parameters, as well as to realize the functions of fault alarm and automatic protection, so as to better control the real-time adjustment of a circulating pump system when carrying circulating water, and realize the reliability of the circulating pump system in the circulating water transportation process.

[0035] The above-mentioned circulation pump system has the following advantages: high efficiency, the circulation pump 1 system can effectively realize the circulation and transportation of the fluid, has high transportation efficiency, and can transport the fluid to the designated location in a short time; good stability, the circulation pump system is usually designed with automatic control and monitoring functions, which can ensure the stability and reliability of the system operation and reduce the downtime caused by failures; high flexibility, the circulation pump system can also be flexibly configured according to different process requirements, adapt to a variety of fluids and working conditions, and meet the use requirements of different occasions; energy saving and environmental protection, modern circulation pump systems usually adopt efficient motor and pump body design, which can reduce energy consumption, reduce energy consumption and environmental pollution; easy maintenance, the various components of the circulation pump system are relatively independent, easy to maintain and repair, and when a failure occurs, the problem can be quickly located and repaired, reducing maintenance time and cost; finally, the circulation pump system is widely used in heating, cooling, water treatment, industrial processes and other fields, and has broad application prospects and market demand.

[0036] The above invention not only improves the operating efficiency and economy of the circulating pump 1, but also reduces maintenance costs and failure rates, providing strong guarantees for the safe and stable operation of the circulating pump system. A circulating pump system is an efficient and reliable automatic control system, which is of great significance for ensuring the normal operation of circulating water transportation.

[0037] Example 2

[0038] On the basis of Example 1, Figure 2As shown, the water inlet of the circulation pump 1 is connected to the return pipe 2, and the water outlet of the circulation pump 1 is connected to the heater 4 through a delivery pipe 3, the water outlet at the top of the heater 4 is connected to the water outlet pipe 5, and the water outlet of the water outlet pipe 5 is connected to the water supply mechanism 6, and the water outlet valve 7 is arranged on the water outlet pipe 5.

[0039] Preferably, the water supply mechanism 6 includes four three-way solenoid valves 8 and four relays 9, and the water outlets of the water outlet pipe 5 are respectively arranged with four three-way solenoid valves 8 at intervals, the water inlet of the three-way solenoid valve 8 is connected to the water outlet of the water outlet pipe 5, and the four three-way solenoid valves 8 are respectively electrically connected to the four relays 9 in a one-to-one correspondence.

[0040] Preferably, it also includes a plurality of low-temperature pipes 10 and a plurality of high-temperature pipes 11, the water inlets of the plurality of low-temperature pipes 10 are connected one-to-one to the first water outlet of the three-way solenoid valve 8, and the water inlets of the plurality of high-temperature pipes 11 are connected one-to-one to the other water outlet of the three-way solenoid valve 8, the low-temperature pipes 10 are used to transport circulating water to the circulating water low-temperature pipes, and the high-temperature pipes 11 are used to transport circulating water to the circulating water high-temperature pipes 11.

[0041] Preferably, the three-way solenoid valve 8 is a 24VDC model, which is an electromagnetic proportional valve controlled by a 24V DC signal, and is provided with a water inlet and two water outlets. The relay 9 is a 24VDC model.

[0042] Preferably, the first water outlet at the bottom of the heater 4 is connected to the water inlet of the drain pump 13 through the first water supply pipe 12, and the water outlet of the drain pump 13 is connected to the water inlet of the water replenishment tank 15 through the delivery pipe 2 14, and the middle part of the delivery pipe 2 14 is connected to the water supply heating network 17 through the delivery pipe 3 16, and the water outlet of the water replenishment tank 15 is connected to the return pipe 2 through the delivery pipe 4 18.

[0043] Preferably, it also includes a first electric regulating valve 19 and a second electric regulating valve 20, the first electric regulating valve 19 is arranged on the delivery pipeline 2 14 between the drain pump 13 and the delivery pipeline 3 16, and the second electric regulating valve 20 is arranged on the delivery pipeline 3 16, and the flow regulating valve 21 is arranged between the delivery pipeline 3 16 and the water replenishment tank 15.

[0044] Preferably, it also includes a drain tank 24, the water inlet of the expansion tank 22 is connected to the second water outlet at the bottom of the heater 4 through the second water supply pipe 23, the water outlet of the expansion tank 22 is connected to the drain tank 24 through a pipeline, and the water outlet of the drain tank 24 is respectively connected to the first drain pipe 25 and the second drain pipe 26, the first drain pipe 25 is sequentially provided with a first drain pump 27, a first manual regulating valve 28, a first non-return valve 29 and a third electric regulating valve 30, the second drain pipe 26 is sequentially provided with a second drain pump 31, a second manual regulating valve 32, a second non-return valve 33 and a fourth electric regulating valve 34, the water outlets of the first drain pipe 25 and the second drain pipe 26 are connected to the return pipe 2 through a third supply pipe, and the third drain pipe is provided with a third non-return valve 35.

[0045] The working principle and beneficial effects of the above technical solution are:

[0046] In the above-mentioned circulation pump system, when the circulation pump 1 system starts to work, the circulation pump 1 arranged in the circulation pump system starts to run, the water inlet of the circulation pump 1 is connected to the return pipe 2, and the water outlet of the circulation pump 1 is connected to the heater 4 through the conveying pipe 3, the heater 4 adopts electromagnetic heating, and generates an alternating magnetic field through the electronic circuit board, so that the iron-containing container cuts the magnetic lines of force and generates eddy currents at the bottom of the container, and the eddy currents make the iron atoms move irregularly at high speed to generate heat energy. This heating method has a high heat conversion rate, which can reach up to 95%; and the water outlet of the water outlet pipe 5 is connected to the water supply mechanism 6, and the water outlet pipe 5 is provided with a water outlet mechanism. Valve 7, the water outlet valve 7 is convenient for adjusting the flow rate of water delivered by the circulating pump system to the water supply mechanism 6, and can be closed in time to stop the water supply when the system fails; at the same time, the water supply mechanism 6 is composed of four three-way solenoid valves 8 and four relays 9, and the water outlet of the water outlet pipe 5 is respectively arranged with four three-way solenoid valves 8 at intervals, and the water inlet of the three-way solenoid valve 8 is connected with the water outlet of the water outlet pipe 5. The three-way solenoid valve 8 selects a 24VDC model, which is an electromagnetic proportional valve controlled by a 24V DC signal, and is respectively provided with a water inlet and two water outlets. The relay 9 selects a 24VDC model. The above settings can be The mechanism 6 performs precise control when delivering circulating water, and the circulating water delivered by the circulating pump system can be intelligently adjusted by adjusting the three-way solenoid valve 8 and the relay 9; at the same time, a plurality of low-temperature pipes 10 and a plurality of high-temperature pipes 11 are arranged in the water supply mechanism 6, and the water inlets of the plurality of low-temperature pipes 10 are connected one by one to the first water outlet of the three-way solenoid valve 8, and the water inlets of the plurality of high-temperature pipes 11 are connected one by one to the other water outlet of the three-way solenoid valve 8. The low-temperature pipes 10 are used to deliver circulating water to the circulating water low-temperature pipes, and the high-temperature pipes 11 are used to deliver circulating water to the circulating water high-temperature pipes 11. The low-temperature pipe 10 and the high-temperature pipe 11 are respectively provided so as to more accurately regulate the circulating water delivery at different temperatures, and to complete the circulating water delivery more reliably and efficiently; by providing the first electric regulating valve 19 and the second electric regulating valve 20, the first electric regulating valve 19 is provided on the delivery pipe 2 14 between the drain pump 13 and the delivery pipe 3 16, and the second electric regulating valve 20 is provided on the delivery pipe 3 16, and the flow regulating valve 21 is provided between the delivery pipe 3 16 and the water replenishment tank 15, which can facilitate the cleaning of the internal pipes of the water supply and heating network 17 and reduce blockages during the delivery process. The above invention does not require manual operation when delivering circulating water, and can automatically detect and eliminate the water flow in the pipe, thereby improving work efficiency, and the material is durable and reliable, with a long service life; it is easy to install, small in size, light in weight, and easy to install and maintain.

[0047] When the above-mentioned circulation pump system is delivering circulating water, at the initial stage of the heater 4 being put into use, when flushing the heater 4 body, the first drainage pump 27 and the second drainage pump 31 are turned on, and at the same time, the first manual regulating valve 28, the second manual regulating valve 32, the first non-return valve 29, the second non-return valve 33, the third electric regulating valve 30 and the fourth electric regulating valve 34 are opened, and when delivering hot water, the hot water is circulated and delivered to the expansion tank 2, and enters the drain tank 24 after being depressurized by the expansion tank 2, and then enters the circulation pump 1 after being pressurized by the first drainage pump 27 and the second drainage pump 31, and the flushing water with high-quality heat is delivered to the return water port of the heater 4 connected to the delivery pipe 13 through the circulation pump 1, so as to realize the flushing of the heater 4 body and the recycling of high-quality heat flushing water; when flushing the pipeline between the heater 4 and the drain pump 13, the first electric regulating valve 19 and the flow regulating valve 21 are opened, and the second electric regulating valve 20 is closed, and the condensate flowing out through the normal drain outlet of the heater 4 passes through the heater 4, enters the drain pump 13, passes through the first electric regulating valve 19 and the flow regulating valve 21, flows into the water supply tank 15, and then enters the circulating pump 1 through the return pipe 2 of the circulating pump 1. The flushing water with high-quality heat is delivered to the water inlet of the heater 4 through the circulating pump 1, so as to realize the flushing of the pipeline between the heater 4 and the drain pump 13 and the recycling of the high-quality heat flushing water. When flushing the pipeline between the drain pump 13 and the water supply heating network 17, the first electric regulating valve 19 is closed, the second electric regulating valve and the flow regulating valve 21 are opened, and the reverse water supply of the water supply heating network 17 is controlled. The water of the water supply heating network 17 passes through the second electric regulating valve 20 and the flow regulating valve 21 in turn and enters the water supply tank 15, and then enters the circulating pump 1 through the return port of the circulating pump 1, so as to realize the flushing of the pipeline between the drain pump 13 and the water supply heating network 17, thereby effectively improving the blockage caused by the circulating pump 1 when using the pipeline for transportation, and improving the efficiency of the circulating pump system for circulating water transportation.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A circulation pump system, characterized in that: include: Circulation pumps are used to transport fluids from a low place to a high place, or to circulate fluids in a pipeline; Pipeline: Pipeline is a channel for fluid transportation, used to connect circulation pumps and various equipment to ensure that the fluid can circulate smoothly; Valves are used to control the flow, pressure and direction of fluids. Valves are connected to pipelines. The control device is used to monitor and control the operating status of the circulation pump system, including the start and stop of the motor, the flow rate and pressure of the fluid. The circulation pump and the valve are electrically connected to the control device respectively.

2. A circulation pump system according to claim 1, characterized in that: The water inlet of the circulation pump (1) is connected to a return pipe (2), and the water outlet of the circulation pump (1) is connected to the heater (4) through a delivery pipe (3), the water outlet at the top of the heater (4) is connected to a water outlet pipe (5), and the water outlet of the water outlet pipe (5) is connected to a water supply mechanism (6), and a water outlet valve (7) is provided on the water outlet pipe (5).

3. A circulation pump system according to claim 2, characterized in that: The water supply mechanism (6) comprises four three-way solenoid valves (8) and four relays (9), and the water outlets of the water outlet pipes (5) are respectively arranged with four three-way solenoid valves (8) at intervals, the water inlets of the three-way solenoid valves (8) are connected to the water outlets of the water outlet pipes (5), and the four three-way solenoid valves (8) are respectively electrically connected to the four relays (9) in a one-to-one correspondence.

4. A circulation pump system according to claim 3, characterized in that: It also comprises a plurality of low-temperature pipes (10) and a plurality of high-temperature pipes (11), wherein the water inlets of the plurality of low-temperature pipes (10) are connected one-to-one to the first water outlet of the three-way solenoid valve (8), and the water inlets of the plurality of high-temperature pipes (11) are connected one-to-one to the other water outlet of the three-way solenoid valve (8), wherein the low-temperature pipes (10) are used to transport circulating water to the circulating water low-temperature pipes, and the high-temperature pipes (11) are used to transport circulating water to the circulating water high-temperature pipes (11).

5. A circulation pump system according to claim 4, characterized in that: The three-way solenoid valve (8) is a 24VDC model, which is an electromagnetic proportional valve controlled by a 24V DC signal, and is provided with a water inlet and two water outlets. The relay (9) is a 24VDC model.

6. A circulation pump system according to claim 2, characterized in that: The first water outlet at the bottom of the heater (4) is connected to the water inlet of the drain pump (13) through the first water delivery pipe (12), and the water outlet of the drain pump (13) is connected to the water inlet of the water supply tank (15) through the second delivery pipe (14), the middle part of the second delivery pipe (14) is connected to the water supply heating network (17) through the third delivery pipe (16), and the water outlet of the water supply tank (15) is connected to the return pipe (2) through the fourth delivery pipe (18).

7. A circulation pump system according to claim 6, characterized in that: It also includes a first electric regulating valve (19) and a second electric regulating valve (20), wherein the first electric regulating valve (19) is arranged on the second delivery pipeline (14) between the drain pump (13) and the third delivery pipeline (16), and the second electric regulating valve (20) is arranged on the third delivery pipeline (16), and the flow regulating valve (21) is arranged between the third delivery pipeline (16) and the water supply tank (15).

8. A circulation pump system according to claim 2, characterized in that: The device also comprises an expansion box (22), wherein the water inlet of the expansion box (22) is connected to the second water outlet at the bottom of the heater (4) through a second water delivery pipe (23), the water outlet of the expansion box (22) is connected to a drain box (24) through a pipeline, and the water outlet of the drain box (24) is respectively connected to a first drain pipe (25) and a second drain pipe (26), wherein the first drain pipe (25) is provided with a first drain pump (27), a first manual regulating valve (28), a first non-return valve (29) and a third electric regulating valve (30) in sequence, and the second drain pipe (26) is provided with a second drain pump (31), a second manual regulating valve (32), a second non-return valve (33) and a fourth electric regulating valve (34) in sequence, and the first drain pipe (25) is provided with a first manual regulating valve (28), a first non-return valve (29) and a third electric regulating valve (30) in sequence. The outlets of the drain pipe (25) and the second drain pipe (26) are connected to the return pipe (2) through the third delivery pipe. Furthermore, a third one-way valve (35) is provided on the third drainage pipe.

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