CN114573179A

CN114573179A - Water purification system, water purification device and control method of water purification system

Info

Publication number: CN114573179A
Application number: CN202210222250.4A
Authority: CN
Inventors: 任富佳; 胡进华; 陈天; 张富元; 彭慧琳; 王轩; 郁明跃
Original assignee: Hangzhou Robam Appliances Co Ltd
Current assignee: Hangzhou Robam Appliances Co Ltd
Priority date: 2022-03-09
Filing date: 2022-03-09
Publication date: 2022-06-03

Abstract

The invention belongs to the technical field of water purification, and particularly discloses a water purification system, a water purification device and a control method of the water purification system. The water purification system includes a membrane filtration unit and a desalination filtration unit arranged in series along an effluent direction, the desalination filtration unit configured to: the desalination filter unit is in a water-passing state in which only a water flow is conducted when the desalination filter unit is not applied with an electric field, and is in a desalination state or a regeneration state when the desalination filter unit is applied with an electric field. The water purifying device comprises the water purifying system, and the control method is applied to the water purifying system. The water purification system, the water purification device and the control method disclosed by the invention can solve the problem of 'first cup of water', improve the drinking water safety and reduce the waste of water resources.

Description

Water purification system, water purification device and control method of water purification system

Technical Field

The invention belongs to the technical field of water purification, and particularly discloses a water purification system, a water purification device and a control method of the water purification system.

Background

With the increasing concern of people on drinking water safety, water purifiers such as water purifiers and water dispensers with water purification functions become common electrical appliances for family life, and the quality of life of people is improved while people drink water conveniently.

Reverse osmosis water purification machine adopts reverse osmosis membrane to filter water mostly, and reverse osmosis water purification machine is at the during operation, and the hydrone of former aquatic and the mineral element of ionic state get into the pure water side through reverse osmosis membrane under certain water pressure effect, and the concentrated water side at reverse osmosis membrane is held back to most inorganic salt, organic matter etc. in former aquatic to realize the water purification effect. When the reverse osmosis water purifier stops working, under the action of concentration gradient potential energy on two sides of the reverse osmosis membrane, salt ions, heavy metals, micromolecular organic matters and the like on the concentrated water side can be slowly diffused to the pure water side, so that the TDS value of the pure water side is increased. Especially, after the purifier stood for a period of time and worked again, the TDS value of the pure water side can be higher than under the normal water purification state more relatively to when leading to the purifier to move once more, salt content is higher in the pure water when the purifier is the initial play water, can reach several times of the normal play water TDS value of purifier even, is unfavorable for the user to use.

The prior art generally reduces the TDS value of a "first cup of water" in three ways: (1) when the water purifier stops working for a period of time, directly draining the first cup of water with the high TDS value; (2) when the water purifier stops working for a period of time, the first cup of water with high TDS value flows back to the water inlet of the reverse osmosis membrane for re-filtration; (3) when the purifier stop work, use the pure water replacement reverse osmosis membrane dense water side's of retaining jar dense water to reduce the concentration gradient of reverse osmosis membrane both sides, thereby can reduce the TDS value of first cup of water by a wide margin.

The first mode is adopted to reduce the TDS value, which causes water resource waste, increases the waiting time for water receiving and influences the use experience of customers; the second method of reducing the TDS value also needs to increase the waiting time for water receiving; the third mode needs back washing for replacing concentrated water, which causes waste of a large amount of water resources, and needs a water storage tank to store pure water, which causes complex structure and increased cost of the water purifier.

Disclosure of Invention

The invention aims to provide a water purification system, a water purification device and a control method of the water purification system, so as to improve the water outlet quality of the water purification system, reduce the waste of water resources and improve the use experience of users.

In order to achieve the purpose, the invention adopts the following technical scheme:

a water purification system comprising a membrane filtration unit and a desalination filtration module arranged in series along an effluent direction, the desalination filtration module comprising a desalination filtration unit in series with the membrane filtration unit, the desalination filtration unit configured to: the desalination filter unit is in a water-passing state in which only a water flow is conducted when the desalination filter unit is not applied with an electric field, and is in a desalination state or a regeneration state when the desalination filter unit is applied with an electric field.

As an optional technical solution of the water purification system, the desalination filter module further comprises a bypass pipe and a bypass control valve, the bypass pipe is connected in parallel with the desalination filter unit, and the bypass control valve is used for controlling the pure water effluent of the membrane filter unit to selectively flow to the bypass pipe or the desalination filter unit.

As an optional technical solution of the water purification system, the desalination and filtration module further comprises a first purified water TDS detection device connected in series between the membrane filtration unit and the desalination and filtration unit;

and/or, the desalination filtration module further comprises a second purified water TDS detection device, and the second purified water TDS detection device is connected in series on the water outlet pipeline of the desalination filtration unit.

As an optional technical solution of the water purification system, the desalination and filtration module includes the first purified water TDS detection device and a flow detection device, and the flow detection device is connected in series to an outlet pipeline of the desalination and filtration unit.

As an optional technical scheme of the water purification system, the desalination filter module is detachably arranged in the water purification system.

As an optional technical scheme of the water purification system, the water purification system further comprises a return pipe, wherein the first end of the return pipe is communicated with a water outlet of the desalination filtering unit, the second end of the return pipe is communicated with a water inlet of the membrane filtering unit, and a return control valve for controlling the on-off of the return pipe is arranged on the return pipe.

As an alternative solution to the water purification system, a one-way valve is arranged on the return pipe, and the one-way valve only allows water in the return pipe to flow from the first end of the return pipe to the second end of the return pipe.

As an optional technical scheme of the water purification system, the water purification system further comprises a booster pump, the booster pump is connected in series with the water inlet pipeline of the membrane filtration unit, and the second end of the return pipe is communicated with the water inlet of the booster pump.

As an optional technical scheme of the water purification system, a concentrated water outlet of the membrane filtration unit is connected with a concentrated water discharge pipe, a concentrated water discharge valve and a switch electromagnetic valve are connected in series on the concentrated water discharge pipe, the concentrated water discharge valve is used for regulating and controlling the flow of the concentrated water discharge pipe, and the switch electromagnetic valve is used for controlling the on-off of the concentrated water discharge pipe.

As an optional technical scheme of the water purification system, a water outlet of the desalination and filtration unit is connected with a discharge pipe, and a discharge control valve for controlling the on-off of the discharge pipe is arranged on the discharge pipe.

As an optional technical scheme of the water purification system, the water purification system further comprises a pre-filtering unit, wherein the pre-filtering unit is connected to the upstream of the membrane filtering unit in series;

and/or, the water purification system further comprises a post-filtration unit, and the post-filtration unit is connected in series to the downstream of the desalination filtration unit.

As an optional technical scheme of the water purification system, when the desalination filter unit is applied with a first electric field, the desalination filter unit is in the desalination state, and when the desalination filter unit is applied with a second electric field, the desalination filter unit is in the regeneration state, and the first electric field and the second electric field are opposite in direction.

A water purification device comprises the water purification system.

A control method of a water purification system, wherein the water purification system adopts the water purification system, and the control method comprises the following steps:

when the desalination and filtration unit is in the water direct connection state, if a preset desalination condition is met, the desalination and filtration unit is controlled to be switched to the desalination state, and if a preset regeneration condition is met, the desalination and filtration unit is controlled to be switched to the regeneration state;

when the desalination filtering unit is in a desalination state, if a preset desalination finishing condition is met, controlling the desalination filtering unit to be switched to the water straight-through state;

and when the desalination and filtration unit is in the regeneration state, if a preset regeneration ending condition is met, controlling the desalination and filtration unit to be switched to the water straight-through state.

As an optional technical solution of the above control method, the preset desalination condition is: the TDS value of the pure water prepared by the membrane filtration unit is higher than a first preset TDS value, the desalination rate of the membrane filtration unit is smaller than a first membrane desalination rate, or the time length of the membrane filtration unit without water passing is longer than a preset shutdown time length;

and/or the preset regeneration conditions are as follows: the current actual desalination rate of the desalination filtering unit is lower than a first preset desalination rate; or after the last regeneration, the total water passing amount of the desalting and filtering unit in the desalting state is larger than the pre-passing water amount; or, the total amount of ions currently adsorbed by the desalination filter unit is greater than or equal to a first preset ion amount; or, the current actual total desalination rate of the water purification system is less than the preset total desalination rate;

and/or the preset desalination finishing conditions are as follows: the time length of the desalination filter unit in the desalination state reaches the preset desalination time length; or, the current salt rejection of the membrane filtration unit is greater than the second salt rejection; or the TDS value of the pure water prepared by the membrane filtration unit is less than or equal to a second preset TDS value of the pure water;

and/or the preset regeneration end condition is as follows: the ion amount released by the desalination filter unit is greater than or equal to a second first preset ion amount; or the time length of the desalination and filtration unit in the regeneration state reaches the preset regeneration time length; or the difference value of the current TDS value at the water outlet and the water inlet of the desalination filter unit is smaller than a preset difference value.

As an optional technical scheme of the control method, the water purification system further comprises a return pipe, wherein a first end of the return pipe is communicated with a water outlet of the desalination and filtration unit, a second end of the return pipe is communicated with a water inlet of the membrane filtration unit, and a return control valve for controlling the on-off of the return pipe is arranged on the return pipe;

the control method further comprises the following steps: controlling the backflow control valve to close when the desalination filtration unit is in the desalination state or the water pass-through state; and when the desalination and filtration unit is in the regeneration state, controlling the backflow control valve to be opened, so that the membrane filtration unit, the desalination and filtration unit and the backflow pipe are connected in series to form a backflow circulation pipeline.

As an optional technical scheme of the control method, a concentrated water outlet of the membrane filtration unit is connected with a concentrated water discharge pipe, and a concentrated water discharge valve and a switch electromagnetic valve are arranged on the concentrated water discharge pipe in series;

the control method further comprises the following steps: when the desalination filtration unit is in the desalination state or the water through state, the switch electromagnetic valve is adjusted to be in an open state, and the concentrated water discharge valve is in a first flow state; and when the desalination and filtration unit is in a regeneration state, adjusting the concentrated water discharge valve to be in a full-open state, and intermittently supplying power to the on-off solenoid valve.

As an optional technical solution of the above control method, when the switching electromagnetic valve is intermittently supplied with power, in a single power supply duration of two adjacent power supplies, a preceding single power supply duration is longer than or equal to a succeeding single power supply duration;

and/or when the switching electromagnetic valve is intermittently powered on, in the single power-off time of two adjacent power-off times, the previous single power-off time is shorter than or equal to the next single power-off time.

As an optional technical scheme of the control method, when the number of times of supplying power to the switching electromagnetic valve is less than or equal to a preset number of times, the single power supply duration is greater than the immediately following single power-off duration; when the times of supplying power to the switching electromagnetic valve is greater than the preset times, the single power supply time length is less than the single power-off time length immediately after the single power-off time length.

As an optional technical scheme of the control method, the water purification system further comprises a bypass pipe and a bypass control valve, wherein the bypass pipe is connected with the desalination filter unit in parallel;

the control method further comprises, when the desalination filtration unit is in the regeneration state or the desalination state, controlling the membrane filtration unit to be disconnected from the bypass pipe by the bypass control valve; when the desalination filter unit is in the water direct connection state, the bypass control valve controls the membrane filter unit to be communicated with the bypass pipe.

The invention has the beneficial effects that:

according to the water purification system provided by the invention, the desalination filter unit is connected in series at the downstream of the membrane filter unit, and the water filtered by the membrane filter unit can be subjected to secondary desalination treatment through the desalination filter unit, so that the TDS value of pure water flowing out of the water outlet can be reduced, and even if the water purification system is not used after standing for a long time, the TDS value of the first cup of water after the water purification system is turned on again cannot be too high, the drinking water safety is ensured, the waste of water resources caused by directly discharging 'the first cup of water' or directly discharging concentrated water at the concentrated water side of the membrane filter unit is avoided, and the normal water discharge of the water purification system is not interfered when the desalination unit carries out desalination, so that the waiting time of a user is reduced; meanwhile, the desalination and filtration unit has a desalination state and a water direct connection state, when the TDS value of the pure water prepared by the membrane filtration unit belongs to the range of normal drinking water, the desalination and filtration unit can be in the water direct connection state without desalination treatment, and when the TDS value of the pure water prepared by the membrane filtration unit is higher, the desalination and filtration unit is in the desalination state to carry out desalination treatment, so that the desalination and filtration unit is effectively prevented from being in a working state all the time, the overall cost of the water purification system is reduced, and the service life of the desalination and filtration unit is prolonged; furthermore, because the desalination filter unit has a regeneration state, when the desalination filter unit adsorbs more salt ions to influence the ion adsorption capacity of the desalination filter unit in the desalination state, the desalination filter unit can be regenerated, thereby ensuring the recovery of the ion adsorption capacity of the desalination filter unit in the desalination state and ensuring the service performance of the water purification system.

According to the water purifying device provided by the invention, by adopting the water purifying system, the consistency of the water outlet quality of the water purifying device can be improved, the use experience of a user is improved, and the water resource loss of the water purifying device is reduced.

The control method of the water purification system provided by the invention can improve the water consumption experience of users, reduce the water source loss during water purification, save the water purification cost and reduce the waiting time for water receiving.

Drawings

Fig. 1 is a schematic structural diagram of a water purification system according to a first embodiment of the present invention;

fig. 2 is a schematic structural diagram of a water purification system provided in the second embodiment of the present invention;

FIG. 3 is a schematic structural diagram of a water purification system provided in the third embodiment of the present invention;

fig. 4 is a schematic structural diagram of a water purification system provided by the fourth embodiment of the invention;

FIG. 5 is a schematic structural diagram of a desalination filter module provided in the fifth embodiment of the present invention;

FIG. 6 is a schematic structural diagram of a desalination filter module according to a sixth embodiment of the present invention;

FIG. 7 is a schematic structural diagram of a desalination and filtration module provided in the seventh embodiment of the present invention.

The figures are labeled as follows:

1. a membrane filtration unit; 2. a desalination filtration unit; 3. a pre-filtering unit; 4. a post-filtration unit; 5. a water driving device; 6. a first purified water TDS detection device; 7. a second purified water TDS detection device; 8. a raw water TDS detection device; 9. a water purification pipeline; 10. a water inlet control valve; 11. a concentrated water discharge pipe; 12. a concentrate discharge valve; 13. a return pipe; 14. a reflux control valve; 15. a one-way valve; 16. a high voltage switch; 17. a discharge pipe; 18. an exhaust control valve; 19. switching on and off the electromagnetic valve; 20. a bypass pipe; 21. a bypass control valve; 22. a flow detection device;

100. and (5) a water using device.

Detailed Description

The present invention will be described in further detail with reference to the drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.

In the description of the present invention, unless expressly stated or limited otherwise, the terms "connected," "connected," and "fixed" are to be construed broadly, e.g., as meaning permanently connected, removably connected, or integral to one another; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.

In the description of the present embodiment, the terms "upper", "lower", "right", etc. are used in an orientation or positional relationship based on that shown in the drawings only for convenience of description and simplicity of operation, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used only for descriptive purposes and are not intended to have a special meaning.

Example one

This embodiment provides a water purification system, and it can be applied to and carries out filtration purification in the purifier who supplies to drink to water to improve the purity degree of drinking water usefulness, reduce purifier's "first cup of water" TDS value, improve purifier's use and experience. The water purifier can be, but is not limited to, a faucet water purifier, a direct drinking water dispenser and the like, and the type and the structure of the water purifier are not limited by the invention.

Specifically, as shown in fig. 1, the water purification system provided by this embodiment includes a water driving device 5, a membrane filtration unit 1 and a desalination filtration module, which are sequentially connected in series along a water outlet direction and through a purified water pipeline 9, the desalination filtration module includes a desalination filtration unit 2, a water inlet of the membrane filtration unit 1 is connected to a raw water inlet of the water purification system, a pure water outlet of the membrane filtration unit 1 is communicated to the water inlet of the desalination filtration unit 2, a water outlet of the desalination filtration unit 2 is communicated to a water outlet of the water purification system, and the water outlet is used for connecting a water consumption device 100 to supply pure water to the water consumption device 100. The water driving device 5 is used for driving water flow to flow from the raw water inlet to the used water outlet. The desalination filter unit 2 is configured to: when the desalination filter unit 2 is not applied with an electric field, the desalination filter unit 2 is in a water-passing state in which only the water flow is conducted, and when the desalination filter unit 2 is applied with an electric field, the desalination filter unit 2 is in a desalination state or a regeneration state.

According to the water purification system provided by the embodiment, the desalination and filtration unit 2 is connected in series at the downstream of the membrane filtration unit 1, and the water filtered by the membrane filtration unit 1 can be desalted again through the desalination and filtration unit 2, so that the TDS value of the pure water flowing out of the water outlet can be reduced, and even if the water purification system is not used after standing for a long time, the TDS value of the first cup of water after the water purification system is turned on again cannot be too high, the drinking water safety is ensured, and the waste of water resources caused by the direct discharge of the 'first cup of water' or the direct discharge of the concentrated water at the concentrated water side of the membrane filtration unit 1 is avoided; meanwhile, because the desalination filter unit 2 has a desalination state and a water straight-through state, when the TDS value of the pure water prepared by the membrane filter unit 1 belongs to the range of normal drinking water, the desalination filter unit 2 can be in the water straight-through state without desalination treatment, and when the TDS value of the pure water prepared by the membrane filter unit 1 is higher, the desalination filter unit 2 is in the desalination state to carry out desalination treatment, so that the desalination filter unit 2 is effectively prevented from being in a working state all the time, the overall cost of the water purification system is reduced, and the service life of the desalination filter unit 2 is prolonged; furthermore, since the desalination filter unit 2 has a regeneration state, when the desalination filter unit 2 adsorbs a large amount of salt ions and affects the ion adsorption capacity of the desalination filter unit 2 in the desalination state, the desalination filter unit 2 can be regenerated, thereby ensuring the ion adsorption capacity of the desalination filter unit 2 in the desalination state to be recovered, and ensuring the usability of the water purification system.

The membrane filtration unit 1 may be a reverse osmosis filter element, a nanofiltration filter element, an electrodialysis membrane filter element, or the like, or may be other filter elements which perform water filtration and purification by using the osmosis principle. The membrane filtration unit 1 is provided with a water inlet, a pure water outlet and a concentrated water outlet, the water inlet and the concentrated water outlet are communicated with the concentrated water side of the membrane filtration unit 1, and the pure water outlet is communicated with the pure water side of the membrane filtration unit 1. The concentrated water outlet is connected with a concentrated water discharging pipe 11, and a concentrated water discharging valve 12 is arranged on the concentrated water discharging pipe 11.

The concentrated water discharge valve 12 can be used for adjusting the discharge flow of the concentrated water discharge pipe 11, when the concentrated water discharge valve 12 is in a small flow opening state and the water driving device 5 is in a working state, water molecules and ions in the concentrated water side enter the pure water side through the permeable membrane under the action of water pressure, and part of concentrated water is discharged through the concentrated water discharge pipe 11 so as to reduce the ion concentration in the concentrated water side; when the concentrate discharge valve 12 is opened, because the concentrate outlet water resistance is smaller than the permeable membrane, the water in the concentrate side is discharged through the concentrate discharge pipe 11, thereby realizing the replacement of the concentrate side water and avoiding the influence of the too high concentration of ions and impurities in the concentrate side water on the filtering effect of the membrane filtering unit 1. The arrangement of the concentrate discharge valve 12 is conventional in the art and will not be described in detail herein.

In order to collect the discharged concentrated water, the water purification system may further include a waste water tank communicated with the concentrated water discharging pipe 11 to store the discharged concentrated water, thereby enabling the concentrated water to be recycled. In other embodiments, the concentrate discharge pipe 11 can also be communicated to the domestic water end.

Preferably, the water driving device 5 is a booster pump, the booster pump is connected in series with the upstream of the membrane filtration unit 1, and the booster pump can increase the flow speed of water flow, so that the water flow entering the membrane filtration unit 1 can be flushed on the surface of the permeable membrane, and the filtration efficiency of the membrane filtration unit 1 is improved.

For improving the life of membrane filtration unit 1 and improving water purification system's filter effect, the upper reaches of membrane filtration unit 1 are established ties and are had prefiltration unit 3, and prefiltration unit 3 is used for carrying out the coarse filtration to the raw water that flows into the raw water import, reduces macromolecule or the large granule impurity that gets into membrane filtration unit 1, reduces the probability of the scale deposit of membrane filtration unit 1, jam to improve membrane filtration unit 1's life. The pre-filtering unit 3 may be, but is not limited to, a PAC composite filter element, a paper folding carbon rod loading filter element, an ultrafiltration carbon rod composite filter element, or a PP cotton filter element, and the like, and those skilled in the art may freely set the pre-filtering unit according to actual situations, and the invention does not specifically limit the type of the pre-filtering unit 3.

In order to further improve the water purification effect of the water purification system, the water purification system further comprises a post-filtration unit 4 connected in series to the downstream of the desalination filtration unit 2, wherein the post-filtration unit 4 is used for further filtering the water purified by the membrane filtration unit 1 or the desalination filtration unit 2, so as to further improve the quality of the pure water flowing out of the water outlet end of the water purification system. The post-filtering unit 4 may include, but is not limited to, a carbon rod filter element, a carbon fiber filter element, or a carbon rod ultrafiltration composite filter element, and the like, and the filtering precision of the post-filtering unit 4 is greater than that of the pre-filtering unit 3.

A water inlet control valve 10 is also connected in series in the purified water pipeline 9, and the water inlet control valve 10 is used for closing or opening the water inlet pipeline so as to realize the connection or disconnection of the water inlet of the whole purified water system. In the present embodiment, the intake control valve 10 is disposed between the pre-filtering unit 3 and the water driving device 5, so that it is possible to make the water passing through the intake control valve 10 already water filtered by the pre-filtering unit 3, prevent the intake control valve 10 from being clogged with impurities, and improve the operational safety and lifespan of the intake control valve 10. In other embodiments, the inlet water control valve 10 may also be disposed upstream of the pre-filter unit 3.

The water inlet control valve 10 is preferably an electromagnetic valve, the water purification system further comprises a controller, and the water inlet control valve 10 is in communication connection with the controller, so that automatic electric control of the water inlet control valve 10 can be realized, and the operation automation of the water purification system is improved.

The water purification pipeline 9 is also provided with a high-pressure switch 16, and the high-pressure switch 16 is arranged between the desalination filter unit 2 and the water outlet end of the water purification system in series to control the water supply to the water outlet end. In the present embodiment, the high-voltage switch 16 is connected in series between the post-filter unit 4 and the desalination filter unit 2, and in other embodiments, the high-voltage switch 16 may be connected in series downstream of the post-filter unit 4.

Preferably, in the present embodiment, when the desalination filter unit 2 is applied with the first electric field, the desalination filter unit 2 is in a desalination state capable of adsorbing ions in water, and when the desalination filter unit 2 is applied with the second electric field, the desalination filter unit 2 is in a regeneration state releasing ions, and the first electric field and the second electric field are opposite in direction. This can reduce the difficulty of controlling the application of the electric field.

In this embodiment, the desalination filter unit 2 includes an ion exchange membrane filter element, and the ion exchange membrane filter element includes cation exchange membrane (positive membrane for short) and anion exchange membrane (negative membrane for short) that relative and interval set up, forms the rivers passageway that supplies rivers to pass through between positive membrane and the negative membrane, and the import of rivers passageway communicates with the pure water outlet of membrane filter unit 1, and the export of rivers passageway forms the delivery port intercommunication of desalination filter unit 2. When the water purification system is in an operating state and the desalination filter unit 2 is in a desalination state, the power supply assembly applies a first electric field directed from the cathode membrane to the anode membrane to the desalination filter unit 2, so that cations in the water flowing through the water flow channel move to the anode membrane and are adsorbed on the anode membrane, and anions move to the cathode membrane and are adsorbed on the cathode membrane, thereby realizing the adsorption of ions by the desalination filter unit 2. When the desalination filter unit 2 needs to be in a regeneration state, a reverse electric field (i.e. a second electric field) is applied through the power supply assembly, so that anions adsorbed on the negative membrane and cations adsorbed on the positive membrane are separated from the surface and carried away with the water flow. When the desalination filter unit 2 is in the water-passing state, ions in the water flowing between the negative and positive membranes are not affected, i.e., when the desalination filter unit 2 corresponds to a piping structure. In other embodiments, the desalination filter unit 2 may be other existing filter element structures that perform desalination by ion adsorption and have a regeneration function, such as a membrane capacitance desalination filter element.

To control the electric field applied to the desalination filter unit 2, the desalination filter module further comprises a power supply assembly for supplying power to the desalination filter unit 2 to switch the desalination filter unit between a water-passing state, a desalination state and a regeneration state.

Preferably, the water outlet of the desalination filter unit 2 is connected to one end of a drain pipe 17, the other end of the drain pipe 17 is connected to the concentrate pipe 11 or the water tank, and a drain control valve 18 is disposed on the drain pipe 17. That is, in this embodiment, when the desalination filter unit 2 needs to be regenerated, the high-voltage switch 16 is turned off, the discharge control valve 18, the water inlet valve and the water driving device 5 are turned on, a water flow sequentially passing through the water inlet end-pre-filter unit 3-membrane filter unit 1-desalination filter unit 2-discharge pipe 17-concentrated water discharge pipe 11 is formed in the water purification system, the power supply module applies a second electric field to the desalination filter unit 2, and ions released into water in the desalination filter unit 2 enter the discharge pipe 17 to be discharged under the driving of the water flow, so that the problems of poor water convenience, easy outflow of water to the ground and the like caused by that the discharged water of the desalination filter unit 2 is directly discharged out of the water outlet of the water purification system in the regeneration state can be avoided.

Further, for the opportunity that the desalination filtration unit 2 carries out various state switch of control better, the desalination filtration module still includes water purification TDS detection device, and clean system includes the controller, and power supply unit and water purification TDS detection device all are connected with the controller communication, and the controller can be according to the condition that the structure control power supply unit that TDS detection device detected applys the electric field to desalination filtration unit 2 to control desalination filtration unit 2's state switch.

That is, through setting up water purification TDS detection device, can control desalination filter unit 2 more accurately and switch to the opportunity of desalination state or regeneration state to can reduce desalination filter unit 2's operating time when improving water purification system's water purification effect and water purification efficiency, reduce water purification system's running cost, energy saving consumed the festival.

In this embodiment, preferably, the purified water TDS detection device comprises a first purified water TDS detection device 6 and/or a second purified water TDS detection device 7. First water purification TDS detection device 6 establishes ties between membrane filtration unit 1 and desalination filtration unit 2 for detect the first water purification TDS value of the water that membrane filtration unit 1 pure water outlet flows out, second water purification TDS detection device 7 establishes ties to desalination filtration unit 2's low reaches, is used for detecting the second water purification TDS value of desalination filtration unit 2's outlet pipe water.

Further, the water purification system further includes a raw water TDS detection device 8, and the raw water TDS detection device 8 is configured to detect a raw water TDS value of the water flowing into the membrane filtration unit 1, so that the desalination effect of the membrane filtration unit 1 and the desalination effect of the desalination filtration unit 2 can be more accurately determined.

Further, the desalination filter module is detachably mounted in the water purification system, so that the desalination filter module can be disassembled and assembled according to the actual situation of the membrane filter unit 1, and the universality is high.

The invention also provides a control method applied to the water purification system, and the control method comprises the following steps:

when the desalination filter unit 2 is in the water straight-through state, if a preset desalination condition is met, controlling the desalination filter unit 2 to be switched to the desalination state, and if a preset regeneration condition is met, controlling the desalination filter unit 2 to be switched to the regeneration state;

when the desalination filter unit 2 is in a desalination state, if a preset desalination finishing condition is met, controlling the desalination filter unit 2 to be switched to the water straight-through state;

when the desalination filter unit 2 is in the regeneration state, if a preset regeneration end condition is met, the desalination filter unit 2 is controlled to be switched to the water straight-through state.

In the present embodiment, the desalting conditions are preset: the desalination rate of the membrane filtration unit 1 is less than the first membrane desalination rate; the preset desalting finishing conditions are as follows: the rejection rate of the membrane filtration unit 1 is greater than the second membrane rejection rate.

Specifically, assuming that the raw water TDS value detected by the raw water TDS detection device 8 is c, if the first purified water TDS value detected by the first purified water TDS detection device 6 is a, the rejection rate L of the membrane filtration unit 1 is 1-a/c. That is, when L is less than the first membrane rejection L₁If the preset desalination condition is reached, judging that the desalination filter unit 2 needs to be switched to a desalination state; when L is greater than or equal to the second membrane rejection L₂If the preset desalination completion condition is reached, it is determined that the desalination filter unit 2 can be switched from the desalination state to the water-through state. Preferably, 0.5 < L₁≤0.85，0.7＜L₂≤0.9，L₁Less than L₂。

The desalination rate L of the membrane filtration unit 1 is used as a reference for judging the switching time of the desalination state of the desalination filtration unit 2, the desalination time of the desalination filtration unit 2 can be judged by comprehensively considering the desalination effect of the membrane filtration unit 1, so that the control of the switching time of the desalination state of the desalination filtration unit 2 is not influenced by the model and the designed desalination rate of the membrane filtration unit 1, and meanwhile, the control method can be suitable for water purification systems of different membrane filtration units 1.

In another embodiment, the preset desalination condition may be that the TDS value of the pure water produced by the membrane filtration unit 1 is higher than the first preset TDS value. That is, in this setting, the condition for determining whether the desalination filter unit 2 is switched into or out of the desalination state may be controlled only by the first purified water TDS value of the first purified water TDS detection device 6 without providing the raw water TDS detection device 8. Specifically, when the first TDS value of the purified water is greater than the first preset TDS value, it indicates that the TDS value of the water flowing out of the pure water outlet of the membrane filtration unit 1 is high, and the desalination filtration unit 2 needs to be started to perform the desalination process again, i.e., the desalination filtration unit 2 needs to be switched to the desalination state.

In this embodiment, since the first purified water TDS value decreases with the operation of the membrane filtration unit 1 and the discharge of the concentrate on the concentrate side, it is also possible to set the preset desalination completion condition as: the TDS value of the pure water produced by the membrane filtration unit 1 is higher than the second preset TDS value. That is, when the first purified water TDS value decreases to the second preset TDS value, the desalination filter unit 2 switches from the desalination state to the water-through state.

In another embodiment, the preset desalination condition may be: the time that the membrane filtration unit 1 is not electrified is longer than the preset shutdown time. When the water non-flowing time of the membrane filtering unit 1 is longer than the preset time, it indicates that the membrane filtering unit 1 does not perform filtering operation for a long time, ions in the concentrated water side permeate into the pure water side more, when the water purifying device is started again for water purification, the TDS value of the first cup of water will be too high, re-desalination treatment needs to be performed, and the desalination filtering unit 2 needs to be switched to a desalination state. The control method does not need to be provided with the first TDS detection device, is low in cost, and is relatively low in control precision.

In another embodiment, the preset desalination termination condition may be: the time length of the desalination filter unit 2 in the desalination state reaches the preset desalination time length. Namely, the timing of the desalination and filtration unit 2 for each desalination completion is controlled by a preset desalination time period preset in the controller. The control method is simple and easy to control.

Further, in the present embodiment, the preset regeneration conditions are: the current actual desalination rate of the desalination filter unit 2 is lower than a first preset desalination rate; the preset regeneration conditions are as follows: the difference value of the current TDS values of the water outlet and the water inlet of the desalination and filtration unit 2 is smaller than a preset difference value.

Specifically, the first purified water TDS value detected by the first purified water TDS value detection device 6 is a, and the second purified water TDS value detected by the second purified water TDS value detection device 7 is b. The current actual salt rejection rate of the desalination filter unit 2 means that the desalination filter unit 2 is in desalinationThe salt rejection m in the state, i.e., m, is 1-b/a. When the desalination filter unit 2 is in a desalination state and m is less than a first preset desalination rate m₁If the desalination rate of the desalination filter unit 2 is determined to be difficult to satisfy the demand for continuous desalination, the desalination filter unit 2 needs to be switched to the regeneration state. Preferably, 0.5 < m₁＜0.9。

When the desalination filter unit 2 is in the regeneration state, the ions adsorbed in the desalination filter unit 2 are released into the water, which will result in the concentration of ions at the water outlet of the desalination filter unit 2 being greater than the concentration at the water inlet of the desalination filter unit 2, and when the TDS values detected at the water inlet and the water outlet are equal, it indicates that all the ions adsorbed on the desalination filter unit 2 are released, i.e. the regeneration is completely finished. That is, when b-a is less than or equal to a predetermined difference N, the desalination filter unit 2 substantially completes regeneration, and N is preferably less than or equal to 2.

In another embodiment, the predetermined regeneration end condition may be: the desalination filter unit 2 is in the regeneration state for a period of time longer than a preset regeneration period of time.

The embodiment also provides a water purification device, which comprises the water purification system.

Example two

As shown in fig. 2, the present embodiment provides a water purification system and a control method using the same, and the water purification system provided in the present embodiment is based on a further improvement of the water purification system in the first embodiment, and the structure identical to that in the first embodiment is not repeated in the present embodiment.

In this embodiment, the water purification system further includes a return pipe 13, a first end of the return pipe 13 is communicated with the water outlet of the desalination and filtration unit 2, a second end of the return pipe 13 is communicated with the water inlet of the membrane filtration unit 1, and the return pipe 13 is provided with a return control valve 14 for controlling the on-off of the return pipe 13.

Through setting up back flow 13 and backward flow control valve 14, when desalination filter unit 2 needs to regenerate, high pressure switch 16 closes, backward flow control valve 14 opens, the water that carries the ion among the desalination filter unit 2 flows back to the water inlet department of booster pump through back flow 13, and after the booster pump pressure boost, flow direction membrane filter unit 1 filters once more, thereby can avoid desalination filter unit 2 when regeneration, the direct discharge of water that flows out from desalination filter unit 2, can reduce the waste of water resource. Meanwhile, ions are accumulated on the concentrated water side after flowing back to the membrane filtration unit 1 along with the water flow, and can be directly discharged through the concentrated water discharge pipe 11 without arranging a separate drainage structure for the desalination filtration unit 2.

Furthermore, the return pipe 13 is provided with a return check valve 15, and the check valve 15 only allows water flow to flow from the first end to the second end of the return pipe 13, so that water on the concentrated water side is prevented from directly entering the water outlet of the purified water pipeline 9 through the return pipe 13, and the use reliability of the water purification system is ensured.

In the present embodiment, one end of the return pipe 13 is connected to the upstream of the water inlet of the booster pump, thereby enabling the booster pump to circulate the driving water flow on the circulation line of the booster pump-membrane filtration unit 1-desalination filtration unit 2-return pipe 13, eliminating the need for separately providing the water-driving device 5 for the return operation, and reducing the overall cost of the purification system.

In this embodiment, preferably, the raw water TDS detection device 8 is located at the upstream of the second end of the return pipe 13, so that the raw water TDS detection device 8 is not connected in series to the return circulation pipeline, and the raw water TDS value detected by the raw water TDS detection device 8 is guaranteed to be the TDS value of the water filtered only by the pre-filtering unit 3, thereby improving the accuracy of the detection result.

The control method provided in this embodiment may refer to the control method provided in the first embodiment, and in this embodiment, the control method further includes: when the desalination filtration unit 2 is in the regeneration state, the reflux control valve 14 is opened to circulate the water flow in a reflux circulation line formed by the membrane filtration unit 1, the desalination filtration unit 2, the reflux pipe 13 and the booster pump.

EXAMPLE III

As shown in fig. 3, the present embodiment provides a water purification system and a control method of the water purification system, and the water purification system provided in the present embodiment is based on a further improvement of the water purification system in the second embodiment, and the structure identical to that in the second embodiment is not repeated in the present embodiment.

In this embodiment, the concentrate discharge pipe 11 is provided with a switch solenoid valve 19, and the switch solenoid valve 19 is used for controlling the on-off of the concentrate discharge pipe 11, that is, when the switch solenoid valve 19 is closed, the concentrate discharge pipe 11 is completely disconnected, no water flows, and when the switch solenoid valve 19 is opened, the water flow on the concentrate discharge pipe 11 depends on the on-off of the concentrate discharge valve 12.

When the desalination filter unit 2 is regenerated, since the regeneration of the desalination filter unit 2 needs a certain time to be completed, if the ion concentration of the concentrated water side of the membrane filter unit 1 reaches a large value during the regeneration of the desalination filter unit 2, the regeneration effect of the desalination filter unit 2 is affected. In order to solve the above problems, when the desalination filter unit 2 is regenerated, the regeneration efficiency of the desalination filter unit 2 is improved by pulse-type drainage, that is, the switch solenoid valve 19 is intermittently energized to intermittently discharge the water on the concentrated water side of the membrane filter unit 1, thereby saving water by backflow and avoiding an excessively high ion concentration on the concentrated water side.

That is, the present embodiment provides a control method, based on the control method in the second embodiment, further including: when the desalination filter unit 2 is in a desalination state or a water through state, the regulating switch electromagnetic valve 19 is in an open state, and the concentrated water discharge valve 12 is in a first flow state; when the desalination filter unit 2 is in the regeneration state, the rich water discharge valve 12 is regulated to be in the fully open state, and the on-off solenoid valve 19 is intermittently supplied with power.

For example, if the desalination filter unit 2 needs 300 seconds to complete regeneration, the concentrate discharge valve 12 is controlled to be turned on and off as follows: the method comprises the steps of electrifying for 60s, powering off for 10s, electrifying for 40s, powering off for 20s, powering on for 20s, powering off for 60s, powering on for 10s, powering off for 60s, and electrifying for 20 s.

The above-described single power-on duration and single power-off duration are exemplary. At the time of regeneration of the desalination filter unit 2, ions released to the desalination filter unit 2 gradually decrease as the regeneration process proceeds, so that the ion concentration of the ion flowing back into the drain pipe 17 decreases, that is, at the initial stage of regeneration of the desalination filter unit 2, the ion concentration of the concentrate side of the membrane filter unit 1 increases quickly, and therefore, preferably, the initial stage of the desalination filter unit 2, the time period for energizing the switching solenoid valve 19 is longer than that at the later stage, and similarly, the single time period for deenergizing the switching solenoid valve 19 may be shorter at the initial stage of the regeneration process and may gradually increase as the regeneration process proceeds.

That is, preferably, the control method further includes: when the switch solenoid valve 19 is intermittently supplied with power, of the single power supply periods of two adjacent power supplies, the preceding single power supply period is longer than or equal to the succeeding single power supply period; and/or, in the intermittent power supply of the switch electromagnetic valve 19, in the single power-off duration of two adjacent power-off, the previous single power-off duration is shorter than or equal to the next single power-off duration. Therefore, the regeneration efficiency can be ensured, and meanwhile, the regeneration efficiency is improved and the water resource loss is reduced.

More preferably, the control method further includes: when the number of times of supplying power to the switching solenoid valve 19 is less than or equal to a preset number of times, the single power supply duration is longer than the immediately following single power-off duration; when the number of times of supplying power to the switching solenoid valve 19 is greater than the preset number of times, the single power supply time period is shorter than the single power off time period immediately following it. The regeneration effect is ensured, the regeneration time is shortened, and the water resource loss is reduced. The specific times of the preset times can be set according to the actual use condition.

Example four

The embodiment provides a water purification system and a control method of the water purification system, and the water purification system provided by the embodiment is based on a further improvement of the water purification system in the second embodiment, and the structure identical to the second embodiment is not repeated in the second embodiment.

As shown in fig. 4, in the present embodiment, the desalination filter module further includes a bypass pipe 20 and a bypass control valve 21 connected in parallel with the desalination filter unit 2, one end of the bypass pipe 20 is connected between the first purified water TDS detection device 6 and the water inlet of the desalination filter unit 2, the other end of the bypass pipe 20 is connected between the second purified water TDS detection device 7 and the water outlet of the desalination filter unit 2, and the bypass control valve 21 is used for controlling the flow of the purified water effluent of the membrane filter unit 1 to selectively flow to the bypass pipe 20 or the desalination filter unit 2.

When the desalination filter unit 2 is in a water straight-through state, the water passing through the desalination filter unit 2 has a back pressure of about 0.2MPa, which reduces the water flow by 10-20%. To solve this problem, in the present embodiment, when no voltage is applied to the desalination filter unit 2, the bypass control valve 21 is in an open state, and at this time, since the water resistance of the bypass pipe 20 is smaller than that of the desalination filter unit 2, the water flow directly flows through the bypass pipe 20 to the water outlet, whereby the flow rate of the water flow at the water outlet end can be increased.

In the present embodiment, the bypass control valve 21 is an electromagnetic valve installed on the bypass pipe 20, and only controls the on/off of the bypass pipe 20, and the bypass control valve 21 is connected to the controller in communication, so as to improve the convenience of control. In other embodiments, the bypass control valve 21 may also be a three-way valve, a water inlet of the three-way valve is communicated with the pure water outlet of the membrane filtration unit 1, one water outlet of the three-way valve is communicated with the water inlet of the desalination filtration unit 2, the other water outlet of the three-way valve is communicated with the bypass pipe 20, and the three-way valve is controlled to selectively flow the effluent of the membrane filtration unit 1 to the bypass pipe 20 or the desalination filtration unit 2.

The control method provided in this embodiment may be performed with reference to the second embodiment or the third embodiment, and on the basis of the control method provided in the second embodiment or the third embodiment, the control method provided in this embodiment further includes: when the desalination filter unit 2 is switched to the water through state, the bypass control valve 21 is switched to conduct the pure water outlet of the membrane filter unit 1 and the passage of the bypass pipe 20; when the desalination filter unit 2 is switched to the desalination state or the regeneration state, the bypass control valve 21 is switched to disconnect the bypass pipe 20.

EXAMPLE five

As shown in fig. 5, the present embodiment provides a water purification system and a control method of the water purification system, and compared with the above embodiments, the water purification system provided by the present embodiment only has differences in the arrangement of the desalination filter modules, and the present embodiment does not describe the same structure as that of the other embodiments again.

In contrast to the above described embodiment, only one purified water TDS detection device is provided in this embodiment, i.e. in this embodiment, only the second purified water TDS detection device 7 is provided downstream of the desalination filter unit 2. With this arrangement, the timing of the start and end of regeneration of the desalination filter unit 2 can be judged by the average salt rejection rate of the water purification system.

That is, in the present embodiment, the preset regeneration conditions are: the current actual total desalination rate of the water purification system is less than the preset total desalination rate.

Specifically, the TDS value detected by the raw water TDS detection device 8 is c, the TDS value detected by the second purified water TDS detection device 7 is b, and the current actual total desalination rate of the water purification system means that when the membrane filtration unit 1 is operating normally and the desalination filtration unit 2 is in the desalination state, the average desalination rate of the water purification system, that is, the average desalination rate n is 1-b/c. When n is less than or equal to the preset total salt rejection rate n₁And in the meantime, it is judged that the whole desalination efficiency of the water purification system is not enough to meet the desalination requirement, that is, it can be judged that the desalination filter unit 2 needs to be regenerated. Preferably, 0.7 < n₁≤0.9。

In this embodiment, the preset regeneration ending condition may be: the time period during which the desalination filter unit 2 is in the regeneration state reaches a preset regeneration time period.

Further, the preset desalination conditions may be: when the desalination filter unit 2 is in the water-passing state, the total desalination rate of the water purification system is less than a second preset total desalination rate (i.e. the desalination rate of the membrane filter unit 1); or, the TDS value of the pure water prepared by the membrane filtration unit 1 is higher than the first preset TDS value (i.e. the value detected by the second pure water TDS detection device 7 is higher than the first preset TDS value); or the duration of the water failure of the membrane filtration unit 1 is longer than the preset shutdown duration.

Further, the preset desalination end condition may be: the time length of the desalination filter unit 2 in the desalination state reaches the preset desalination time length; or, the current salt rejection rate of the membrane filtration unit 1 is greater than the second salt rejection rate; or the TDS value of the pure water prepared by the membrane filtration unit 1 is less than or equal to a second preset pure water TDS value;

it can be understood that, in the present embodiment, when the desalination filter unit 2 is in the water passing state, the TDS value detected by the second purified water TDS detection device 7 is the TDS value of the pure water prepared by the membrane filter unit 1, i.e. the actual desalination rate of the membrane filter unit 1 can be calculated according to the raw water TDS value c detected by the raw water TDS detection device 8 and the second purified water TDS value b detected by the second purified water TDS detection device 7.

EXAMPLE six

As shown in fig. 6, the present embodiment provides a water purification system and a control method thereof, and the water purification system provided by the present embodiment is a further improvement of the water purification system provided by any one of the first to fourth embodiments, and the same structure as that described above is not repeated in the present embodiment.

In this embodiment, the TDS detection device includes a first TDS detection device 6 and a second TDS detection device 7, and the desalination filter module further includes a flow detection device 22, and the flow detection device 22 is disposed at the downstream of the desalination filter unit 2 for detecting the water flow of the water outlet. Further, flow detection device 22 establishes ties and sets up in second water purification TDS detection device 7's low reaches to can judge the ion total amount M that adsorbs in the time t through the detected value of flow and the second water purification TDS value that second water purification TDS detection device 7 detected.

That is, in the present embodiment, the preset regeneration conditions are: the total amount of ions currently adsorbed by the desalination filter unit 2 is greater than or equal to a first preset ion amount.

Specifically, the first purified water TDS value detected by the first purified water TDS detection device 6 is a, the second purified water TDS value detected by the second purified water TDS detection device 7 is b, the flow rate detected by the flow rate detection device 22 at time t is u, and the total amount of ions adsorbed by the desalination filter unit 2 during time t is M,

when M is greater than or equal to the first preset ion amount, the desalination filter unit 2 is indicated to adsorbThe ions are already close to saturation and need to be regenerated.

Further, the preset regeneration end conditions are as follows: the total amount of ions released by the desalination filter unit 2 during this regeneration process is greater than or equal to a second predetermined amount of ions.

Specifically, when the desalination filter unit 2 is in the regeneration state, the desalination filter unit 2 releases an amount of ions M' during time t of

If M' is greater than or equal to the second predetermined amount of ions, it indicates that desalination filter unit 2 has been regenerated.

Preferably, the second predetermined amount of ions is equal to the first predetermined amount of ions.

This embodiment still provides a purifier, including foretell water purification system.

EXAMPLE seven

As shown in fig. 7, the present embodiment provides a water purification system and a control method of the water purification system, and the water purification system provided by the present embodiment is substantially the same as the water purification system provided by the sixth embodiment, except that the second purified water TDS detection device 7 is not provided in the present embodiment.

The control method provided in this embodiment may refer to the above control method, except that in this embodiment, the preset regeneration condition is: after the last regeneration, the total water passing amount of the desalination filter unit 2 in the desalination state is larger than the preset water passing amount.

Specifically, the desalination filter unit 2 is in the desalination state for a time period t each time_iThe flow rate detected by the flow rate detection device 22 is q every time the desalination filtration unit 2 is in the desalination state_iThe amount of water passing through the desalination filter unit 2 in the single desalination state is q_it_iThe total water flow of the desalination filter unit 2 is, wherein N is the number of times the desalination filter unit 2 has been switched to the desalination state since the last regeneration.

It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A water purification system comprising a membrane filtration unit (1) and a desalination filtration module arranged in series along an effluent direction, the desalination filtration module comprising a desalination filtration unit (2) in series with the membrane filtration unit (1), the desalination filtration unit (2) being configured to: when the desalination filter unit (2) is not applied with an electric field, the desalination filter unit (2) is in a water-through state in which only a water flow is conducted, and when the desalination filter unit (2) is applied with an electric field, the desalination filter unit (2) is in a desalination state or a regeneration state.

2. The water purification system of claim 1, wherein the desalination filtration module further comprises a bypass pipe (20) and a bypass control valve (21), the bypass pipe (20) being arranged in parallel with the desalination filtration unit (2), the bypass control valve (21) being adapted to control the pure water effluent of the membrane filtration unit (1) to selectively flow to the bypass pipe (20) or to the desalination filtration unit (2).

3. The water purification system of claim 1, wherein the desalination filter module further comprises a first purified water TDS detection device (6), the first purified water TDS detection device (6) being connected in series between the membrane filter unit (1) and the desalination filter unit (2);

and/or, the desalination filter module further comprises a second purified water TDS detection device (7), and the second purified water TDS detection device (7) is connected in series on a water outlet pipeline of the desalination filter unit (2).

4. The water purification system of claim 3, wherein the desalination filter module comprises the first purified water TDS detection device (6) and a flow detection device (22), the flow detection device (22) being connected in series to an outlet line of the desalination filter unit (2).

5. The water purification system of claim 1, wherein the desalination filter module is removably mounted in the water purification system.

6. The water purification system according to any one of claims 1 to 5, further comprising a return pipe (13), wherein a first end of the return pipe (13) is communicated with a water outlet of the desalination filter unit (2), a second end of the return pipe (13) is communicated with a water inlet of the membrane filter unit (1), and a return control valve (14) for controlling the on-off of the return pipe (13) is arranged on the return pipe (13).

7. A water purification system according to claim 6, wherein a one-way valve (15) is arranged on the return pipe (13), the one-way valve (15) allowing only water in the return pipe (13) to flow from the first end of the return pipe (13) to the second end of the return pipe (13).

8. The water purification system of claim 6, further comprising a booster pump connected in series to the water inlet line of the membrane filtration unit (1) and the second end of the return pipe (13) is in communication with a water inlet of the booster pump.

9. The water purification system according to claim 6, wherein a concentrate outlet of the membrane filtration unit (1) is connected with a concentrate discharge pipe (11), the concentrate discharge pipe (11) is provided with a concentrate discharge valve (12) and a switch solenoid valve (19) in series, the concentrate discharge valve (12) is used for regulating and controlling the flow of the concentrate discharge pipe (11), and the switch solenoid valve (19) is used for controlling the on-off of the concentrate discharge pipe (11).

10. The water purification system as claimed in any one of claims 1 to 5, wherein a discharge pipe (17) is connected to a water outlet of the desalination filter unit (2), and a discharge control valve (18) for controlling the on-off of the discharge pipe (17) is arranged on the discharge pipe (17).

11. Water purification system according to any one of claims 1-5, further comprising a pre-filtration unit (3), the pre-filtration unit (3) being connected in series upstream of the membrane filtration unit (1);

and/or, the water purification system further comprises a post-filtration unit (4), wherein the post-filtration unit (4) is connected in series to the downstream of the desalination filtration unit (2).

12. The water purification system of any one of claims 1-5, wherein the desalination filter unit (2) is in the desalination state when a first electric field is applied to the desalination filter unit (2), and wherein the desalination filter unit (2) is in the regeneration state when a second electric field is applied to the desalination filter unit (2), the first and second electric fields being opposite in direction.

13. A water purification apparatus comprising a water purification system as claimed in any one of claims 1 to 12.

14. A control method for a water purification system, applied to the water purification system according to any one of claims 1 to 12, the control method comprising:

when the desalination filter unit (2) is in the water through state, if a preset desalination condition is met, controlling the desalination filter unit (2) to be switched to the desalination state, and if a preset regeneration condition is met, controlling the desalination filter unit (2) to be switched to the regeneration state;

when the desalination and filtration unit (2) is in a desalination state, if a preset desalination finishing condition is met, controlling the desalination and filtration unit (2) to be switched to the water direct connection state;

when the desalination and filtration unit (2) is in the regeneration state, if a preset regeneration ending condition is met, the desalination and filtration unit (2) is controlled to be switched to the water through state.

15. The control method according to claim 14, wherein the preset desalination condition is: the TDS value of the pure water prepared by the membrane filtration unit (1) is higher than a first preset TDS value, the desalination rate of the membrane filtration unit (1) is smaller than a first membrane desalination rate, or the duration of the membrane filtration unit (1) without water is larger than a preset shutdown duration;

and/or the preset regeneration conditions are as follows: the current actual desalination rate of the desalination filter unit (2) is lower than a first preset desalination rate; or, after the last regeneration, the total water passing amount of the desalting and filtering unit (2) in the desalting state is larger than the pre-passing water amount; or, the total amount of ions currently adsorbed by the desalination filter unit (2) is greater than or equal to a first preset ion amount; or, the current actual total desalination rate of the water purification system is less than the preset total desalination rate;

and/or the preset desalination finishing conditions are as follows: the time length of the desalination filter unit (2) in the desalination state reaches the preset desalination time length; or, the current salt rejection of the membrane filtration unit (1) is greater than the second salt rejection; or the TDS value of the pure water prepared by the membrane filtration unit (1) is less than or equal to a second preset TDS value of the pure water;

and/or the preset regeneration end condition is as follows: the ion amount released by the desalination filter unit (2) is more than or equal to a first preset ion amount; or the time length of the desalination and filtration unit (2) in the regeneration state reaches the preset regeneration time length; or the difference value of the current TDS values at the water outlet and the water inlet of the desalination and filtration unit (2) is smaller than a preset difference value.

16. The control method according to claim 14, wherein the water purification system further comprises a return pipe (13), a first end of the return pipe (13) is communicated with the water outlet of the desalination and filtration unit (2), a second end of the return pipe (13) is communicated with the water inlet of the membrane filtration unit (1), and a return control valve (14) for controlling the on-off of the return pipe (13) is arranged on the return pipe (13);

the control method further comprises the following steps: controlling the backflow control valve (14) to close when the desalination filtration unit (2) is in the desalination state or the water pass-through state; when the desalination and filtration unit (2) is in the regeneration state, the backflow control valve (14) is controlled to be opened, so that the membrane filtration unit (1), the desalination and filtration unit (2) and the backflow pipe (13) are connected in series to form a backflow circulation pipeline.

17. The control method according to claim 16, characterized in that a concentrate discharge pipe (11) is connected to a concentrate outlet of the membrane filtration unit (1), and a concentrate discharge valve (12) and an on-off solenoid valve (19) are arranged on the concentrate discharge pipe (11) in series;

the control method further comprises the following steps: when the desalination filtration unit (2) is in the desalination state or the water-through state, the on-off solenoid valve (19) is adjusted to be in an open state, and the rich water discharge valve (12) is in a first flow state; when the desalination filtration unit (2) is in the regeneration state, the concentrate discharge valve (12) is regulated to be in a fully open state, and power is intermittently supplied to the on-off solenoid valve (19).

18. The control method according to claim 17, characterized in that, in intermittently supplying the switching solenoid valve (19), of the single supply periods of two adjacent supplies, the preceding single supply period is longer than or equal to the succeeding single supply period;

and/or, when the switching electromagnetic valve (19) is intermittently powered, in the single power-off time of two adjacent power-off times, the previous single power-off time is shorter than or equal to the next single power-off time.

19. The control method according to claim 18, characterized in that when the number of times the on-off solenoid valve (19) is energized is less than or equal to a preset number, the single energization period is longer than the immediately subsequent single deenergization period; when the frequency of supplying power to the switching electromagnetic valve (19) is greater than the preset frequency, the single power supply time is less than the single power-off time immediately after the single power-off time.

20. The control method according to claim 14, wherein the water purification system further comprises a bypass pipe (20) and a bypass control valve (21), the bypass pipe (20) being arranged in parallel with the desalination filter unit (2);

the control method further comprises controlling the membrane filtration unit (1) to be out of communication with the bypass pipe (20) by the bypass control valve (21) when the desalination filtration unit (2) is in the regeneration state or the desalination state; when the desalination and filtration unit (2) is in the water-through state, the bypass control valve (21) controls the membrane filtration unit (1) to be communicated with the bypass pipe (20).