CN110652882A - Flushing device and method for multi-section reverse osmosis membrane system - Google Patents

Abstract

The invention relates to a flushing device and a method for a multi-section reverse osmosis membrane system, wherein the flushing device comprises: a cleaning tank; the inlet of the flushing water pump is connected with the cleaning tank through a cleaning tank connecting pipeline; the two ends of the section of the front flushing pipeline are respectively connected with a washing water pump and a water inlet main pipe; the first end of the second-section intermediate pipeline is also connected with the outlet of the flushing water pump, and the second end of the second-section intermediate pipeline is respectively connected with the first-section water outlet pipeline and the second-section water inlet pipeline; the control valve group comprises a washing water pump valve arranged on a connecting pipeline of a washing water pump upstream washing pool, a two-section intermediate valve arranged on a two-section intermediate pipeline, a washing pipeline valve arranged on a section of front washing pipeline, a water inlet main pipe valve arranged on a water inlet main pipe, and a two-section washing valve arranged on a two-section water inlet pipeline. According to the invention, the problem that the first two membrane elements in the first section of membrane device of the multi-section reverse osmosis membrane system are seriously polluted is solved, the cleaning efficiency of the membrane elements is improved, and then the pollution problem of the whole multi-section reverse osmosis membrane system is relieved.

Description

A flushing device and method for a multi-stage reverse osmosis membrane system

technical field

The invention relates to a flushing device and method, in particular to a flushing device and method suitable for a multi-stage reverse osmosis membrane system polluted by organic substances, microorganisms, inorganic salts and the like.

Background technique

Reverse osmosis membranes are widely used in tap water treatment, advanced sewage treatment, seawater desalination, printing and dyeing, electroplating and other sewage purification due to their high desalination efficiency, small footprint, green environmental protection, wide application range and simple operation. Because reverse osmosis is different from traditional filtration methods, traditional filtration methods can remove the retained pollutants from the filter layer by backwashing the filter medium, and when the surface of reverse osmosis membrane concentrates salts, colloids, microorganisms, organics and other pollutants At the time, the concentrated material needs to be taken away by the concentrated water flowing parallel to the membrane. After a reverse osmosis membrane system has been running for a period of time, the fouling of the reverse osmosis membrane will cause problems such as a decrease in the desalination rate of the system, a decrease in the water output, and an increase in the pressure difference.

Membrane fouling of reverse osmosis membrane systems develops slowly, and if measures are not taken at an early stage, fouling will damage the performance of membrane elements in a relatively short period of time. Generally speaking, when the following phenomenon occurs in the reverse osmosis membrane system, it indicates that the membrane element is contaminated and should be cleaned in time: ① Under normal pressure, the product water flow rate drops by 10-15% of the normal value; ② In order to maintain normal product Water flow and water supply pressure increased by 10-15%; ③ Product water-salt permeability increased by 10-15%. These membrane fouling phenomena will reduce the water production of the reverse osmosis membrane system, increase the water supply pressure, reduce the product quality, and increase the cleaning frequency and water production cost of the reverse osmosis membrane system. Therefore, how to prevent or slow down the fouling of the reverse osmosis membrane, prolong the service life of the membrane, and improve the cleaning effect of the membrane has become an important research direction in the current reverse osmosis technology.

In the multi-stage reverse osmosis membrane system, when the water flows through the first two membrane shells of the first stage membrane element, under the action of the water supply pressure, part of the water passes through the reverse osmosis membrane, and the concentrated water side of the reverse osmosis membrane will accumulate Colloids, metal oxides, bacteria, organic matter, scale and other substances, the membrane fouling is more serious in the first two membrane shells than the subsequent membrane shells. After a period of operation, the pressure difference of a single membrane element will increase, and even telescopes may occur. The phenomenon causes damage to the physical structure of the membrane element. In the traditional membrane flushing method, the flushing water enters from the water inlet side of a membrane shell, and the water flow direction is the same as the water inlet direction during operation, resulting in poor flushing effect, and even the pollutants in the front section may be flushed to the membrane element in the rear section. Causes subsequent components to be fouled, so a more efficient flushing method is required.

SUMMARY OF THE INVENTION

In view of the above problems, the purpose of the present invention is to provide a flushing device and method for a multi-stage reverse osmosis system. By solving the problem of serious pollution of the first two membrane elements in the one-stage membrane device of the multi-stage reverse osmosis membrane system, the cleaning efficiency of the membrane elements is improved. efficiency, and then alleviate the pollution problem of the entire multi-stage reverse osmosis membrane system.

In order to achieve the above object, the present invention adopts the following technical scheme: a flushing device of a multi-stage reverse osmosis membrane system, the multi-stage reverse osmosis membrane system comprises a precision filter, a high-pressure pump, a one-stage membrane device and a two-stage membrane device connected in turn, the The flushing device includes: a cleaning tank for placing reverse osmosis product water; a flushing water pump, the inlet of the flushing water pump is connected to the cleaning tank through a cleaning tank connecting pipe; The first end is connected to the outlet of the flushing water pump, and the second end of the first section of the pre-flushing pipeline is connected to the water inlet main pipe located upstream of the precision filter; One end is also connected to the outlet of the flushing water pump, and the second ends of the first and second sections of the intermediate pipeline are respectively connected to the first section of the water outlet pipeline and the second section of the water inlet pipeline through the tee; the control valve group, the control valve group includes a set of The flushing water pump valve on the connecting pipeline of the cleaning tank upstream of the flushing pump, the first and second intermediate valves arranged on the first and second intermediate pipelines, and the flushing pipeline valve arranged on the first-stage flushing pipeline, are arranged in the A water inlet main valve located on the water inlet main pipe downstream of the high-pressure pump, and a second-stage flush valve arranged on the second-stage water inlet pipe.

In the flushing device, preferably, a first concentrated water side discharge pipeline and a second concentrated water side discharge pipeline are respectively connected to the concentrated water side discharge ports of the one-stage membrane device and the second-stage membrane device, and the control valve The group also includes a first concentrated water side discharge valve and a second concentrated water side discharge valve respectively disposed on the first concentrated water side discharge pipeline and the second concentrated water side discharge pipeline.

The flushing device, preferably, the flushing device further includes a dosing device, the dosing device includes a dosing box, and the dosing box is connected to the cleaning tank through a dosing pump, a dosing pipeline and a dosing valve. At the same time, a pre-dosing and flushing pipeline and a flushing valve are also arranged downstream of the first and second sections of the intermediate pipeline, and the first end of the pre-dosing and flushing pipeline is connected to the outlet of the flushing water pump, so The second end of the pre-dosing and flushing pipeline is connected to the water inlet main pipe between the water inlet main valve and a section of membrane device.

In the flushing device, preferably, a static mixer is further provided on the connecting pipe of the cleaning tank located downstream of the dosing pipe.

In the flushing device, preferably, sealing rings are installed on both sides of each membrane element in the one-stage membrane device.

A flushing method for a multi-stage reverse osmosis membrane system based on the above flushing device, comprising the following steps:

1) During forward flushing, open the flushing water pump valve, flushing pipeline valve, inlet main valve and second-stage flushing valve, and close the first- and second-stage intermediate valves;

2) Turn on the flushing water pump, the flushing water is connected to the flushing water pump from the cleaning pool through the cleaning pool, and is input to the water inlet main pipe from the pre-flushing pipeline, and the flushing water flows through the precision filter and the high-pressure pump Then, rinse the first-stage membrane device and the second-stage membrane device in sequence to flush away the pollutants adhering to the surface of the membrane elements in the first-stage membrane device and the second-stage membrane device, and put the first-stage membrane device and the second-stage membrane device in the membrane device. The concentrated water is replaced into purified water, and the flushing waste water flows into the waste water tank from the second concentrated water side discharge pipeline and the second concentrated water side discharge valve in the second-stage membrane device;

3) After the forward flushing is completed, the reverse flushing is performed. At this time, the first and second stage intermediate valves are opened, and the second stage cleaning valve is closed, and the flushing water is connected by the cleaning pool through the cleaning pool. , the first and second sections of the intermediate pipeline flow into each branch membrane element of the one-stage membrane device in turn, reversely flush the pollutants on the surface of each branch membrane element, and remove the pollutants from the first branch membrane element of the one-stage membrane device. Take out, the flushing waste water flows into the waste water tank through the first concentrated water side discharge pipeline and the first concentrated water side discharge valve.

In the flushing method, preferably, when the operating pressure of the first-stage membrane device and/or the second-stage membrane device rises, the dosing pump and the dosing valve are opened at this time, and dosing is added to the forward flushing water. A certain concentration of chemical agents, after the chemical agents are accurately metered by the dosing box through the dosing pump, are input into the cleaning tank connecting pipeline from the dosing pipeline, and are fully mixed by the static mixer. , turn on the flushing water pump, the flushing liquid directly enters the first-stage membrane device through the pre-dosing flushing pipeline and the flushing valve, and the flushing wastewater is discharged from the first concentrated water side of the first-stage membrane device The pipe and the first concentrate side discharge valve flow into the waste pool.

In the flushing method, preferably, after the chemical flushing is completed, the dosing valve is closed, and the forward flushing in step 2) is repeated to replace the flushing medicinal liquid in the first-stage membrane device into purified water, and the flushing wastewater passes through. The first concentrated water side discharge pipeline and the first concentrated water side discharge valve flow into the waste water tank.

In the flushing method, preferably, both forward flushing and reverse flushing are performed once every 24 hours, the flushing flow rate of a single membrane element is 9 m ³ , the flushing time is 15 min, and the flushing pressure is lower than 0.05 MPa.

In the flushing method, preferably, the frequency of chemical flushing is set to once every 7-15 days.

The present invention has the following advantages due to the adoption of the above technical solutions: 1. The present invention is aimed at the fields of reverse osmosis treatment of surface water, advanced sewage treatment, industrial sewage recycling and the like, and the first two membranes in a one-stage membrane device of a multi-stage reverse osmosis membrane system The element produces serious fouling and blocking, resulting in the problem that the pressure difference of a single membrane element increases. A flushing device and method for a multi-stage reverse osmosis membrane system is provided, which adopts forward flushing and concentrated water side backflushing, and cooperates with Bactericides, organic solvents, acids, alkali solutions and other agents can control the flow direction of the flushing liquid by controlling the valve group, and form hydraulic flushing on the surface of each membrane element, which has a good flushing effect, especially for the first section of the water inlet of the membrane device. The pollution of the first and second membrane elements has a good control effect, which greatly improves the flushing effect, and can reduce the amount of cleaning water and the dosage of chemicals. 2. When the present invention performs reverse flushing, the first membrane element in the water inlet direction is located on the side closest to the flushing and draining water, so that the accumulated fouling blocks are more likely to be flushed out of the multi-stage reverse osmosis membrane system by the flushing water. , which improves the flushing effect and prolongs the stable operation period of the multi-stage reverse osmosis membrane system.

Description of drawings

Fig. 1 is the structural representation of the flushing device of the present invention;

FIG. 2 is a schematic structural diagram of the flushing device of the present invention after adding a medicine dosing device.

Detailed ways

The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, so as to more clearly understand the objects, features and advantages of the present invention. It should be understood that the embodiments shown in the accompanying drawings are not intended to limit the scope of the present invention, but are only intended to illustrate the essential spirit of the technical solutions of the present invention.

As shown in Figure 1, the flushing device of the multi-stage reverse osmosis membrane system provided by the present invention, the multi-stage reverse osmosis membrane system comprises a precision filter a, a high-pressure pump b, a one-stage membrane device c and a second-stage membrane device d connected in sequence, the The flushing device includes: a cleaning tank 1, for placing reverse osmosis product water; a flushing water pump 3, the inlet of the flushing water pump 3 is connected to the cleaning tank 1 through the cleaning tank connecting pipe 2; a pre-flushing pipeline 4 and a pre-flushing pipeline 4 The first end of the first end is connected to the outlet of the flushing water pump 3, the second end of the first section of the pre-flushing pipeline 4 is connected to the water inlet main pipe located upstream of the precision filter a; It is also connected to the outlet of the flushing water pump 3, and the second ends of the first and second sections of the intermediate pipeline 5 are respectively connected to the first section of the water outlet pipeline and the second section of the water inlet pipeline through the three-way; The flushing water pump valve 7 on the pipeline 2, the one-two intermediate valve 8 on the one-two-section intermediate pipeline 5, and the flushing pipeline valve 9 on the one-stage pre-flushing pipeline 4 are located in the downstream of the high-pressure pump b. The water inlet main valve 10 on the water inlet main pipe, and the second-stage flush valve 11 arranged on the second-stage water inlet pipeline.

In the above embodiment, preferably, concentrated water side discharge pipes 6 and 22 are respectively connected to the concentrated water side discharge ports of the one-stage membrane device c and the second-stage membrane device d.

In the above embodiment, preferably, the control valve group further includes concentrated water side discharge valves 12 and 13 respectively disposed on the concentrated water side discharge pipes 6 and 22 .

In the above-mentioned embodiment, preferably, as shown in FIG. 2 , the flushing device further includes a drug-adding device, and the drug-adding device includes a drug-adding box 15 . The medicine valve 18 is connected with the cleaning tank connecting pipeline 2; at the same time, a pre-medication flushing pipeline 20 and a flushing valve 21 are also provided downstream of the first and second sections of the intermediate pipeline 5, and the first end of the pre-medicated flushing pipeline 20 is connected to the flushing The outlet of the water pump 3, the second end of the pre-dosing and flushing pipe 20 is connected to the water inlet main valve 10 and the water inlet main pipe between a section of membrane device c, so that the liquid medicine passes through the pre-dosing and flushing pipe 20 and the flushing valve. 21 directly into a section of membrane device c.

In the above embodiment, preferably, a static mixer 19 is further provided on the cleaning tank connecting pipe 2 located downstream of the chemical dosing pipe 17, for fully mixing the reverse osmosis product water and the chemical agent.

In the above-mentioned embodiment, preferably, sealing rings 14 are installed on both sides of each membrane element in a section of membrane device c, thereby ensuring that the water entering either side can only enter from the membrane section of the membrane element , so that forward flushing and reverse flushing can be performed alternately.

Based on the flushing device of the multi-stage reverse osmosis membrane system provided by the above embodiment, the present invention also proposes a flushing method for the multi-stage reverse osmosis membrane system, comprising the following steps:

1) During forward flushing, open the flushing water pump valve 7, flushing pipeline valve 9, inlet main valve 10 and second-stage flushing valve 11, and close the first and second-stage intermediate valve 8;

2) Turn on the flushing water pump 3, the flushing water is connected from the cleaning pool 1 to the flushing water pump 3 through the cleaning pool pipeline 2, and is input into the water inlet main pipe from a pre-flushing pipeline 4, and the flushing water flows through the precision filter a and the high-pressure pump b. The first-stage membrane device c and the second-stage membrane device d are used to flush out the organic matter, microorganisms, inorganic foulants and other pollutants adhering to the surface of the membrane elements in the first-stage membrane device c and the second-stage membrane device d, and the first-stage membrane device c and the second-stage membrane device d. The concentrated water in the second-stage membrane device d is replaced with purified water, and the flushing wastewater flows into the waste water tank from the concentrated-water side discharge pipeline 22 and the concentrated-water side discharge valve 13 in the second-stage membrane device d;

3) After the forward flushing is completed, the reverse flushing is carried out. At this time, the first and second stage intermediate valves 8 are opened, and the second stage cleaning valve 11 is closed. The second-stage intermediate pipeline 5 flows into each membrane element of the first-stage membrane device c in turn, flushes the pollutants on the surface of each membrane element in reverse, and takes the pollutants out from the first membrane element of the first-stage membrane device c, and the flushing wastewater passes through The concentrated water side discharge pipeline 6 and the concentrated water side discharge valve 12 flow into the waste water tank.

In the above embodiment, preferably, when the operating pressure of the first-stage membrane device c and/or the second-stage membrane device d increases, the dosing pump 16 and the dosing valve 18 are opened at this time, and a certain concentration is added to the forward flushing water. The chemical agent (non-oxidizing bactericide, hydrochloric acid or sodium hydroxide, etc.), the chemical agent is accurately metered by the dosing box 15 through the dosing pump 16, and then is input into the cleaning tank connection pipe 2 from the dosing pipeline 17, and passes through After the static mixer 19 is fully mixed, the flushing water pump 3 is turned on, and the flushing liquid directly enters the first-stage membrane device c through the pre-dosing flushing pipeline 20 and the flushing valve 21, and the flushing wastewater is discharged from the concentrated water side of the first-stage membrane device c. The sum and concentrated water side discharge valve 12 flows into the waste pool.

In the above embodiment, preferably, after the chemical flushing is completed, the dosing valve 18 is closed, and the forward flushing method in step 2 needs to be repeated to replace the flushing liquid in a section of membrane device c into purified water, and the flushing wastewater passes through the concentrated The water side discharge pipe 6 and the concentrated water side discharge valve 12 flow into the waste water tank.

In the above embodiment, preferably, both forward flushing and reverse flushing are performed once every 24 hours, the flushing flow rate of a single membrane element is 9 m ³ , the flushing time is 15 min, and the flushing pressure is lower than 0.05 MPa.

In the above embodiment, preferably, the frequency of chemical flushing can be set to once every 7-15 days.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Those of ordinary skill in the art should understand that they can still modify or equivalently replace the technical solutions of the present invention, but these Modifications or equivalent substitutions cannot depart from the spirit and scope of the technical solutions of the present invention.

Claims (10)

1. The utility model provides a washing unit of multistage reverse osmosis membrane system, this multistage reverse osmosis membrane system is including precision filter (a), high-pressure pump (b), one section membrane device (c) and two sections membrane device (d) that connect gradually, and its characterized in that, this washing unit includes:

the cleaning pool (1) is used for placing reverse osmosis product water;

the inlet of the washing water pump (3) is connected with the washing pool (1) through a washing pool connecting pipeline (2);

a section of pre-flushing pipeline (4), wherein the first end of the section of pre-flushing pipeline (4) is connected with the outlet of the flushing water pump (3), and the second end of the section of pre-flushing pipeline (4) is connected with a main water inlet pipe positioned at the upstream of the precision filter (a);

the first end of the second section middle pipeline (5) is also connected with the outlet of the flushing water pump (3), and the second end of the second section middle pipeline (5) is respectively connected with a first section water outlet pipeline and a second section water inlet pipeline through a tee;

the control valve group comprises a washing water pump valve (7) arranged on the upstream of the washing water pump (3) on the washing pool connecting pipeline (2), a two-section intermediate valve (8) arranged on the two-section intermediate pipeline (5), a washing pipeline valve (9) arranged on the front-arranged washing pipeline (4), a water inlet main pipe valve (10) arranged on the water inlet main pipe on the downstream of the high-pressure pump (b), and a two-section washing valve (11) arranged on the two-section water inlet pipeline.

2. The flushing device according to claim 1, characterized in that a first concentrate side discharge conduit (6) and a second concentrate side discharge conduit (22) are connected to the concentrate side discharge ports of the first stage membrane device (c) and the second stage membrane device (d), respectively, and the control valve group further comprises a first concentrate side discharge valve (12) and a second concentrate side discharge valve (13) provided on the first concentrate side discharge conduit (6) and the second concentrate side discharge conduit (22), respectively.

3. The flushing device according to claim 2, characterized in that it further comprises a dosing device, said dosing device comprising a dosing tank (15), said dosing tank (15) being connected to said washing tank connection pipe (2) by means of a dosing pump (16), a dosing pipe (17) and a dosing valve (18); simultaneously, the low reaches of pipeline (5) still are provided with leading medicine washing pipeline (20) and flush valve (21) in the middle of a two-section, the first end of leading medicine washing pipeline (20) is connected the export of washing water pump (3), the second end of leading medicine washing pipeline (20) is connected the main pipe of intaking between water main pipe valve (10) and one section membrane device (c) of intaking is responsible for.

4. The flushing device according to claim 3, characterized in that a static mixer (19) is also provided on the cleaning tank connection pipe (2) downstream of the dosing pipe (17).

5. A flushing device according to claim 1, characterized in that a sealing ring (14) is mounted on both sides of each membrane element in the length of membrane device (c).

6. A method of flushing a multi-stage reverse osmosis membrane system based on the flushing device of claim 4, comprising the steps of:

1) when the water is washed in the forward direction, the washing water pump valve (7), the washing pipeline valve (9), the water inlet main pipe valve (10) and the second-stage washing valve (11) are opened, and the second-stage intermediate valve (8) is closed;

2) opening the flushing water pump (3), inputting flushing water from the cleaning pool (1) to a water inlet main pipe through the cleaning pool connecting pipeline (2) and the flushing water pump (3), flushing the first section of membrane device (c) and the second section of membrane device (d) in sequence after the flushing water flows through the precision filter (a) and the high-pressure pump (b) so as to flush away pollutants adhered to the surfaces of membrane elements in the first section of membrane device (c) and the second section of membrane device (d) and replace concentrated water in the first section of membrane device (c) and the second section of membrane device (d) into purified water, and enabling flushing wastewater to flow into a wastewater pool through the second concentrated water side discharge pipeline (22) and the second concentrated water side discharge valve (13) in the second section of membrane device (d);

3) and carrying out reverse flushing after the forward flushing is finished, opening the second-section intermediate valve (8), closing the second-section cleaning valve (11), enabling the cleaning tank (1) to pass through the cleaning tank connecting pipeline (2) and the cleaning water pump (3) and the second-section intermediate pipeline (5) to sequentially flow into each membrane element of the first-section membrane device (c), reversely flushing pollutants on the surface of each membrane element and bringing the pollutants out of the first membrane element of the first-section membrane device (c), and enabling the flushing wastewater to flow into a wastewater tank through the first concentrated water side discharge pipeline (6) and the first concentrated water side discharge valve (12).

7. The method of claim 6, wherein the dosing pump (16) and the dosing valve (18) are opened when the operating pressure of the one-stage membrane device (c) and/or the two-stage membrane device (d) rises, chemical agents with certain concentration are added into the forward flushing water, after the chemical agents are accurately metered by the dosing tank (15) through the dosing pump (16), is input into the cleaning pool connecting pipeline (2) through the medicine adding pipeline (17), and after fully mixing through the static mixer (19), the flushing water pump (3) is opened, flushing liquid medicine directly enters the section of membrane device (c) through the preposed medicine-adding flushing pipeline (20) and the flushing valve (21), and flushing wastewater flows into a wastewater tank through the first concentrated water side discharge pipeline (6) and the first concentrated water side discharge valve (12) in the section of membrane device (c).

8. A method of flushing according to claim 7 wherein after completion of the chemical flushing, the dosing valve (18) is closed and the forward flushing of step 2) is repeated to displace the flushing liquid in the length of membrane means (c) into purified water, the flushing waste water flowing into the waste water tank through the first concentrate side discharge conduit (6) and the first concentrate side discharge valve (12).

9. The method according to claim 6, wherein the forward flushing and the reverse flushing are performed every 24H, and the flushing flow rate of the single membrane element is 9m³The flushing time is 15min, and the flushing pressure is lower than 0.05 MPa.

10. The rinsing method according to claim 6, wherein the frequency of the chemical rinsing is set to 7 to 15 days once.

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