阅读说明：本技术 压能复合型脱盐工艺 (Pressure energy composite desalting process ) 是由 张玉新 李威 于 2020-04-15 设计创作，主要内容包括：本发明提供一种压能复合型脱盐工艺,包括1)进液：利用高压泵和循环泵泵送盐水到压能回收容器；2)反渗透：利用循环泵将压能回收容器中的盐水泵送入反渗透管路进行反渗透,浓水回流至压能回收容器,同时高压泵泵送盐水补充到压能回收容器来维系压力；3)排液：步骤2)进行预定反渗透时间后,利用高压泵和循环泵排出压能回收容器中的浓盐水；4)重复步骤1)～3)预定周期；5)冲洗：利用循环泵和高压泵泵送淡水对压能回收容器和膜组件进行冲洗,再利用循环泵和高压泵排出冲洗后汇入压能回收容器中的冲洗水,重复进行步骤1)～5)。本发明中水泵数量少、不停机运转,使得成本降低、管路简化、节能降耗、使用寿命长。(The invention provides a pressure energy composite type desalting process, which comprises the following steps of 1) feeding liquid: pumping the brine to a pressure energy recovery vessel by using a high-pressure pump and a circulating pump; 2) reverse osmosis: pumping the salt water in the pressure energy recovery container into a reverse osmosis pipeline by using a circulating pump for reverse osmosis, refluxing concentrated water to the pressure energy recovery container, and pumping the salt water by using a high-pressure pump to supplement the salt water to the pressure energy recovery container to maintain the pressure; 3) liquid drainage: step 2) discharging strong brine in the pressure energy recovery container by using a high-pressure pump and a circulating pump after the reverse osmosis is carried out for a preset reverse osmosis time; 4) repeating the steps 1) to 3) for a preset period; 5) washing: pumping fresh water by using a circulating pump and a high-pressure pump to flush the pressure energy recovery container and the membrane component, discharging flushing water which is converged into the pressure energy recovery container after flushing by using the circulating pump and the high-pressure pump, and repeatedly performing the steps 1) to 5). The invention has the advantages of less water pumps, no shutdown operation, low cost, simplified pipeline, energy saving, consumption reduction and long service life.)

1. A pressure energy composite type desalination process is characterized by comprising the following steps:

1) liquid feeding: sending the brine into a pressure energy recovery container through a first liquid inlet pipeline by using a high-pressure pump, and sending the brine into the pressure energy recovery container through a second liquid inlet pipeline by using a circulating pump;

2) reverse osmosis: after the pressure energy recovery container is filled with brine, pumping the brine in the pressure energy recovery container into a reverse osmosis pipeline with a membrane component by using the circulating pump to perform reverse osmosis treatment, enabling fresh water to flow out and concentrated water to flow back to the pressure energy recovery container, and simultaneously supplementing the brine to the pressure energy recovery container through the first liquid inlet pipeline by using a high-pressure pump to maintain the system pressure of normal operation;

3) liquid drainage: after the reverse osmosis in the step 2) is carried out for a preset reverse osmosis time, all the strong brine in the pressure energy recovery container is discharged by the high-pressure pump through a first liquid discharge pipeline and the circulating pump through a second liquid discharge pipeline;

4) repeating the steps 1) to 3) for a preset period;

5) washing: respectively pumping fresh water through a first fresh water flushing pipeline and a second fresh water flushing pipeline which respectively correspond to the circulating pump and the high-pressure pump to flush the pressure energy recovery container and the membrane module for preset flushing time, respectively discharging flushing water which is flushed and then gathered into the pressure energy recovery container through the first liquid discharge pipeline and the second liquid discharge pipeline which respectively correspond to the circulating pump and the high-pressure pump, and then repeatedly performing the steps 1-5).

2. The pressure energy composite type desalination process of claim 1, wherein the membrane module comprises a plurality of modules arranged in parallel, and each module comprises 1-3 reverse osmosis membrane elements arranged in series in the same membrane shell.

3. The pressure energy composite desalination process of claim 2, wherein the reverse osmosis membrane element is a reverse osmosis membrane with a diameter of 4 inches, and the optimal water supply flow is 2-3 m for cultivation/h; or the reverse osmosis membrane element is a reverse osmosis membrane with the diameter of 8 inches, and the optimal water supply flow is 8-12 m/h.

4. The pressure energy complex desalination process according to any one of claims 1 to 3, wherein the first liquid inlet pipeline, the first liquid outlet pipeline and the first fresh water flushing pipeline have a first common pipeline, and the high-pressure pump is arranged on the first common pipeline; the second liquid inlet pipeline, the reverse osmosis pipeline, the second liquid discharge pipeline and the second fresh water flushing pipeline are provided with a second common pipeline, and the circulating pump is arranged on the second common pipeline; the high-pressure pump is a variable-frequency high-pressure pump, and the circulating pump is a variable-frequency circulating pump; and the pipelines and the pumps are automatically controlled by a PLC controller.

5. The pressure energy composite type desalination process of claim 4, wherein the first liquid inlet pipeline, the first liquid outlet pipeline and the first fresh water flushing pipeline are respectively provided with an electromagnetic valve at two sides of the first common pipeline for controlling the pipelines to be opened and closed; the second liquid inlet pipeline, the second liquid discharge pipeline and the second fresh water flushing pipeline are provided with a third common pipeline, the third common pipeline comprises the second common pipeline, an electromagnetic valve positioned outside the second common pipeline and a one-way valve positioned between the electromagnetic valve and the second common pipeline, and the second liquid inlet pipeline, the second liquid discharge pipeline and the second fresh water flushing pipeline are respectively provided with an electromagnetic valve at two sides of the third common pipeline for controlling the pipelines to be opened and closed; and the reverse osmosis pipeline is provided with an electromagnetic valve respectively at two sides of the second common pipeline for controlling the opening and closing of the reverse osmosis pipeline.

6. The pressure energy complex desalination process of claim 5, wherein the second feed line, the reverse osmosis line, and the second fresh water flushing line have a fourth common line comprising the second common line, the fourth common line comprising the membrane module located outside the second common line, and a solenoid valve for opening and closing the common lines located between the membrane module and the pressure energy recovery vessel; the first fresh water flushing pipeline and the second fresh water flushing pipeline are provided with a common fresh water inlet pipeline, and the common fresh water inlet pipeline is provided with the electromagnetic valve and the one-way valve for controlling the pipelines to be opened and closed.

7. The pressure-energy compound type desalination process of claim 6, wherein a ninth electromagnetic valve, the high-pressure pump, a first normally open manual valve and a first electromagnetic valve are sequentially arranged on the first liquid inlet pipeline in the liquid inlet direction; a seventh electromagnetic valve, the high-pressure pump, the first normally open manual valve and a third electromagnetic valve are sequentially arranged on the first liquid discharge pipeline in the liquid discharge direction; an eighth electromagnetic valve, a second one-way valve, the high-pressure pump, the first normally open manual valve and the first electromagnetic valve are arranged on the first fresh water flushing pipeline in the flushing direction; the ninth electromagnetic valve, the fifth electromagnetic valve, the first one-way valve, the circulating pump, the second normally open manual valve, the membrane module and the second electromagnetic valve are sequentially arranged on the second liquid inlet pipeline in the liquid inlet direction; the seventh electromagnetic valve, the fifth electromagnetic valve, the first one-way valve, the circulating pump, the second normally open manual valve and the fourth electromagnetic valve are sequentially arranged on the second liquid discharge pipeline in the liquid discharge direction; the eighth electromagnetic valve, the second one-way valve, the circulating pump, the second normally open manual valve, the membrane module and the second electromagnetic valve are arranged on the second fresh water flushing pipeline in the flushing direction; the reverse osmosis pipeline is provided with the second electromagnetic valve, the membrane module, the second normally open manual valve, the circulating pump and a sixth electromagnetic valve in the reverse osmosis direction; and a tenth electromagnetic valve is arranged on the pressure energy recovery container.

8. The pressure energy complex desalination process according to claim 7, wherein before the step 1) is started, the first solenoid valve, the second solenoid valve, the third solenoid valve, the fourth solenoid valve, the fifth solenoid valve, the sixth solenoid valve, the seventh solenoid valve, the eighth solenoid valve, the ninth solenoid valve, and the tenth solenoid valve are in a normally closed state; in the step 1), the first solenoid valve, the second solenoid valve, the fifth solenoid valve, the ninth solenoid valve, and the tenth solenoid valve are in an open state, the third solenoid valve, the fourth solenoid valve, the sixth solenoid valve, the seventh solenoid valve, and the eighth solenoid valve are in a closed state, and the high-pressure pump and the circulation pump are started to operate for a first predetermined time.

9. The pressure energy complex desalination process according to claim 8, wherein in the step 2), the first solenoid valve, the second solenoid valve, the sixth solenoid valve and the ninth solenoid valve are in an open state, the third solenoid valve, the fourth solenoid valve, the fifth solenoid valve, the seventh solenoid valve, the eighth solenoid valve and the tenth solenoid valve are in a closed state, and the high-pressure pump and the circulation pump continue to operate for a second predetermined time.

10. The pressure energy complex type desalination process according to claim 9, wherein in the step 3), the third solenoid valve, the fourth solenoid valve, the fifth solenoid valve and the seventh solenoid valve are in an open state, and the tenth solenoid valve is opened after a third predetermined time is delayed, the first solenoid valve, the second solenoid valve, the sixth solenoid valve, the eighth solenoid valve, the ninth solenoid valve and the tenth solenoid valve are in a closed state, and the high-pressure pump and the circulation pump continue to operate for a fourth predetermined time; and, the predetermined period in the step 4) is six.

11. The pressure energy complex desalination process according to claim 10, wherein in the step 5), the first solenoid valve, the second solenoid valve, the fifth solenoid valve, the eighth solenoid valve and the tenth solenoid valve are in an open state, the third solenoid valve, the fourth solenoid valve, the sixth solenoid valve, the seventh solenoid valve and the ninth solenoid valve are in a closed state, and after a fifth predetermined time, the third solenoid valve, the fourth solenoid valve, the fifth solenoid valve, the seventh solenoid valve and the tenth solenoid valve are in an open state, and the first solenoid valve, the second solenoid valve, the sixth solenoid valve, the eighth solenoid valve and the ninth solenoid valve are in a closed state, and after a sixth predetermined time, the process returns to the step 1).

12. The pressure energy composite type desalination process of claim 11, wherein the PLC is used for performing full-automatic linkage control on the electromagnetic valves and the pumps.

The technical field is as follows:

the invention relates to the technical field of desalination, in particular to a pressure energy composite type desalination process.

Background art:

the world's direct use of fresh water resources by humans is less than 0.3% of the total water resources, and the growth of the population, the development of agriculture and industry, has led to a rapid decrease in fresh water, especially clean fresh water. About 3 hundred million people need to obtain domestic water by desalting treatment of saline water or saline groundwater, so that the desalting has strategic significance and development prospect.

The applicant previously provided a pressure energy composite desalination process: each pump (namely, a high-pressure pump and a circulating pump) works intermittently, is switched by a PLC controller, and is provided with a water supply and drainage pump for supplying water and draining water to a system specially. Although such a working mode makes the structure compact, the cost low and the energy consumption low, the following problems still exist: 1) the water pumps are frequently started, and the requirements on the pumps and the sealing of the pumps are high; 2) the control flow is complex because not only the switching of the valve but also the alternate operation of the pump exist; 3) the number of pumps is large, a pipeline system is complex, and the engineering quantity is large; 4) the pump switches frequently, so that the energy consumption is large.

Disclosure of Invention

In order to overcome the defects, the invention provides the pressure energy composite type desalination process which has the advantages of no stop, less energy consumption and simple control flow when various water pumps work.

Therefore, the invention provides a pressure energy composite type desalting process which is characterized by comprising the following steps:

1) liquid feeding: sending the brine into a pressure energy recovery container through a first liquid inlet pipeline by using a high-pressure pump, and sending the brine into the pressure energy recovery container through a second liquid inlet pipeline by using a circulating pump;

2) reverse osmosis: after the pressure energy recovery container is filled with brine, pumping the brine in the pressure energy recovery container into a reverse osmosis pipeline with a membrane component by using the circulating pump to perform reverse osmosis treatment, enabling fresh water to flow out and concentrated water to flow back to the pressure energy recovery container, and simultaneously supplementing the brine to the pressure energy recovery container through the first liquid inlet pipeline by using a high-pressure pump to maintain the system pressure of normal operation;

3) liquid drainage: after the reverse osmosis of the step 2) is carried out for a preset reverse osmosis time, all the strong brine in the pressure energy recovery container is discharged by the high-pressure pump through a first liquid discharge pipeline and the circulating pump through a second liquid discharge pipeline;

4) repeating the steps 1) to 3) for a preset period;

5) washing: pumping fresh water through a first fresh water flushing pipeline and a second fresh water flushing pipeline which respectively correspond to the circulating pump and the high-pressure pump to flush the pressure energy recovery container and the membrane module for a preset flushing time, discharging the flushed water which is collected into the pressure energy recovery container after flushing through a first liquid discharge pipeline and a second liquid discharge pipeline which respectively correspond to the circulating pump and the high-pressure pump, and then repeatedly performing the steps 1) to 5).

In the invention, the water pump is not stopped in each production flow, so that the frequency conversion starting is reduced, and the service life of the unit is longer; the number of the water pumps is reduced from three in the prior art to two, so that the cost is reduced, and a pipeline system is simplified; 4) because each water pump runs continuously when working, the starting frequency of the pump is greatly reduced, energy is saved and consumption is reduced.

Furthermore, the membrane module comprises a plurality of modules which are arranged in parallel, and each module is provided with 1-3 reverse osmosis membrane elements which are arranged in the same membrane shell in series.

Because the membrane module has high integration degree and the number of the reverse osmosis membrane elements connected in series in the same module is small, the occupied area can be saved by 40-60% in 1) and the investment cost is reduced; 2) the utilization rate of each reverse osmosis membrane element is relatively balanced, and the average service life of the reverse osmosis membrane elements is prolonged; 3) the reverse osmosis membrane elements embedded in the same membrane shell are reduced in number compared with the prior art, so that the maintenance and overhaul are convenient; 4) the membrane component arrangement mode of a plurality of modules which are arranged in parallel and a small number of reverse osmosis membrane elements connected in series in each module can greatly reduce the working pressure of the high-pressure pump, save energy and reduce consumption.

Further, the reverse osmosis membrane element is a reverse osmosis membrane with the diameter of 4 inches, and the optimal water supply flow is 2-3 m for cultivation/h; or the reverse osmosis membrane element is a reverse osmosis membrane with the diameter of 8 inches, and the optimal water supply flow is 8-12 m/h.

Through the arrangement, the use of a scale inhibitor can be omitted, and the cost is saved.

Still further, the first liquid inlet line, the first liquid discharge line, and the first fresh water flushing line have a first common line, and the high-pressure pump is provided on the first common line; the second liquid inlet pipeline, the reverse osmosis pipeline, the second liquid discharge pipeline and the second fresh water flushing pipeline are provided with a second common pipeline, and the circulating pump is arranged on the second common pipeline; the high-pressure pump is a variable-frequency high-pressure pump, and the circulating pump is a variable-frequency circulating pump; and the pipelines and the pumps are automatically controlled by a PLC controller.

The common pipeline is arranged, so that the common and non-stop use of each water pump in each process step can be ensured, the use number of the pumps is reduced, the frequent start and stop of the pumps are avoided, the service life is prolonged, the energy consumption is saved, and the cost is reduced; the high-pressure pump and the circulating pump are controlled by frequency conversion, and the salt content of the produced fresh water and the salt content of the concentrated seawater can be flexibly adjusted as required in a larger range; the PLC is started by one key, so that the control is simple and convenient.

Still further, the first liquid inlet pipeline, the first liquid outlet pipeline and the first fresh water flushing pipeline are respectively provided with an electromagnetic valve at two sides of the first common pipeline for controlling the opening and closing of the pipelines; the second liquid inlet pipeline, the second liquid discharge pipeline and the second fresh water flushing pipeline are provided with a third common pipeline, the third common pipeline comprises the second common pipeline, an electromagnetic valve positioned outside the second common pipeline and a one-way valve positioned between the electromagnetic valve and the second common pipeline, and the second liquid inlet pipeline, the second liquid discharge pipeline and the second fresh water flushing pipeline are respectively provided with an electromagnetic valve at two sides of the third common pipeline for controlling the pipelines to be opened and closed; the reverse osmosis pipeline is provided with an electromagnetic valve respectively arranged at two sides of the second common pipeline for controlling the opening and the closing of the reverse osmosis pipeline.

Through the control of the electromagnetic valves at the two ends of each pipeline, the pipelines can be ensured to be unblocked when needing to be opened and unblocked when needing to be closed, so that liquid feeding, reverse osmosis, liquid discharging and flushing according to a preset path are ensured.

Further, the second liquid inlet line, the reverse osmosis line, and the second fresh water flushing line may have a fourth common line including the second common line, the fourth common line including the membrane module located outside the second common line, and an electromagnetic valve for opening and closing the lines located between the membrane module and the pressure energy recovery vessel; the first fresh water flushing pipeline and the second fresh water flushing pipeline have a common fresh water inlet pipeline, and the electromagnetic valve and the one-way valve for controlling the pipelines to be opened and closed are arranged on the common fresh water inlet pipeline.

Through the shared arrangement of the pipelines, the arrangement of the pipelines can be effectively simplified, the efficiency is improved, and the cost is reduced.

Still further, a ninth electromagnetic valve, the high-pressure pump, a first normally open manual valve and a first electromagnetic valve are sequentially arranged on the first liquid inlet pipeline in the liquid inlet direction; a seventh electromagnetic valve, the high-pressure pump, the first normally open manual valve and a third electromagnetic valve are sequentially arranged on the first liquid discharge pipeline in the liquid discharge direction; an eighth electromagnetic valve, a second one-way valve, the high-pressure pump, the first normally open manual valve and the first electromagnetic valve are arranged on the first fresh water flushing pipeline in the flushing direction; the ninth electromagnetic valve, the fifth electromagnetic valve, the first one-way valve, the circulating pump, the second normally open manual valve, the membrane module and the second electromagnetic valve are sequentially arranged on the second liquid inlet pipeline in the liquid inlet direction; the seventh electromagnetic valve, the fifth electromagnetic valve, the first check valve, the circulating pump, the second normally open manual valve and the fourth electromagnetic valve are sequentially arranged on the second liquid discharge pipeline in the liquid discharge direction; the eighth electromagnetic valve, the second check valve, the circulating pump, the second normally open manual valve, the membrane module, and the second electromagnetic valve are disposed on the second fresh water flushing pipeline in the flushing direction; the reverse osmosis pipeline is provided with the second electromagnetic valve, the membrane module, the second normally open manual valve, the circulating pump and a sixth electromagnetic valve in the reverse osmosis direction; the pressure energy recovery container is provided with a tenth electromagnetic valve.

Through the arrangement of the electromagnetic valves on the pipelines and the arrangement of some electromagnetic valves shared by different pipelines, the opening and closing of the pipelines can be cooperatively controlled through the PLC.

Still further, before the start of the step 1), the first solenoid valve, the second solenoid valve, the third solenoid valve, the fourth solenoid valve, the fifth solenoid valve, the sixth solenoid valve, the seventh solenoid valve, the eighth solenoid valve, the ninth solenoid valve, and the tenth solenoid valve are normally closed; in the step 1), the first solenoid valve, the second solenoid valve, the fifth solenoid valve, the ninth solenoid valve, and the tenth solenoid valve are in an open state, the third solenoid valve, the fourth solenoid valve, the sixth solenoid valve, the seventh solenoid valve, and the eighth solenoid valve are in a closed state, and the high-pressure pump and the circulation pump are started up and operated for a first predetermined time. Further, the first predetermined time is 5 min.

Through the arrangement, other pipelines are closed, and only the first liquid inlet pipeline and the second liquid inlet pipeline are unblocked, so that liquid is fed into the pressure energy recovery container.

Further, in the step 2), the first solenoid valve, the second solenoid valve, the sixth solenoid valve, and the ninth solenoid valve are in an open state, the third solenoid valve, the fourth solenoid valve, the fifth solenoid valve, the seventh solenoid valve, the eighth solenoid valve, and the tenth solenoid valve are in a closed state, and the high-pressure pump and the circulation pump continue to operate for a second predetermined time. Further, the second predetermined time is 34.5 min.

Through the arrangement, only the reverse osmosis pipeline is unblocked under the condition that other pipelines are closed, so that reverse osmosis is completed.

Still further, in the step 3), the third solenoid valve, the fourth solenoid valve, the fifth solenoid valve, and the seventh solenoid valve are in an open state, the tenth solenoid valve is opened with a delay of a third predetermined time, the first solenoid valve, the second solenoid valve, the sixth solenoid valve, the eighth solenoid valve, the ninth solenoid valve, and the tenth solenoid valve are in a closed state, and the high-pressure pump and the circulation pump continue to operate for a fourth predetermined time; the predetermined cycle in the step 4) is six.

Through the arrangement, only the first liquid discharge pipeline and the second liquid discharge pipeline are unblocked under the condition that other pipelines are closed, so that liquid discharge is completed.

Further, in the step 5), the first solenoid valve, the second solenoid valve, the fifth solenoid valve, the eighth solenoid valve, and the tenth solenoid valve are in an open state, the third solenoid valve, the fourth solenoid valve, the sixth solenoid valve, the seventh solenoid valve, and the ninth solenoid valve are in a closed state, and after the state continues for a fifth predetermined time, the third solenoid valve, the fourth solenoid valve, the fifth solenoid valve, the seventh solenoid valve, and the tenth solenoid valve are in an open state, the first solenoid valve, the second solenoid valve, the sixth solenoid valve, the eighth solenoid valve, and the ninth solenoid valve are in a closed state, and the state continues for a sixth predetermined time, and then the step 1 is returned).

Through the arrangement, only the first fresh water flushing pipeline and the second fresh water flushing pipeline are unblocked, so that fresh water flushing is completed; after the fresh water flushing is finished, only the first liquid discharge pipeline and the second liquid discharge pipeline are unblocked, so that the flushing water is discharged.

And further, the PLC is used for carrying out full-automatic linkage control on each electromagnetic valve and each pump.

These and other aspects of the invention are apparent from and will be elucidated with reference to the embodiments described hereinafter.

Description of the drawings:

the structure and further objects and advantages of the present invention will be better understood by the following description taken in conjunction with the accompanying drawings, in which like reference characters identify like elements, and in which:

FIG. 1 is a schematic diagram of a pressure-energy complex desalination unit for use in a pressure-energy complex desalination process according to an embodiment of the present invention, wherein the flow direction of the fluid in the fluid replenishing step is shown by arrows;

FIG. 2 is a view similar to FIG. 1, but with arrows showing the direction of fluid flow during the reverse osmosis step;

FIG. 3 is a view similar to FIG. 1, but with arrows showing the direction of fluid flow during the draining step;

FIG. 4 is a view similar to FIG. 1, but with arrows showing the direction of fluid flow during the flushing step;

fig. 5 is a schematic structural diagram of a membrane module of the pressure-energy complex type desalination unit shown in fig. 1.

The specific implementation mode is as follows:

the following description of the embodiments of the present invention will be made with reference to the accompanying drawings. However, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed manner.

As referred to herein, "desalination" includes desalination of sea water, brackish water, industrial wastewater, and the like; the term "brine" as used herein includes water having a relatively high salt content, such as seawater, brackish water, and industrial waste water.

Referring to fig. 1 to 4, in a pressure energy complex type desalination process according to an embodiment of the present invention, the process includes the following steps:

1) liquid feeding: saline water is sent into the pressure energy recovery container 1 through the first liquid inlet pipe 11 by the high-pressure pump M1, and simultaneously, saline water is sent into the pressure energy recovery container 1 through the second liquid inlet pipe 12 by the circulating pump M2, and the flow direction of the fluid in the step is shown by arrows in fig. 1;

2) reverse osmosis: after the pressure energy recovery vessel 1 is filled with the brine, the brine in the pressure energy recovery vessel 1 is sucked into the reverse osmosis pipeline 21 with the membrane component 2 by using the circulating pump M2 to perform reverse osmosis treatment, the fresh water produced by the reverse osmosis pipeline 21 flows out, the produced concentrated water flows back to the pressure energy recovery vessel 1, and simultaneously the brine is supplemented into the pressure energy recovery vessel 1 through the first liquid inlet pipeline 11 by using the high-pressure pump M1 to maintain the system pressure of normal operation, wherein the flow direction of the fluid in the step is shown as an arrow in fig. 2;

3) liquid drainage: after the reverse osmosis of step 2) is performed for a predetermined reverse osmosis time, the concentrated brine in the pressure energy recovery vessel 1 is completely discharged by the high-pressure pump M1 through the first discharge line 31 and simultaneously by the circulation pump M2 through the second discharge line 32, and the flow direction of the fluid in this step is as shown by the arrow in fig. 3;

4) repeating the steps 1) to 3) for a predetermined period, wherein the predetermined period is 6 periods in the embodiment;

5) washing: pumping fresh water through a first fresh water flushing pipeline 51 and a second fresh water flushing pipeline 52 corresponding to the pressure energy recovery container 1 and the membrane module 2 by using a circulating pump M2 and a high-pressure pump M1 respectively to flush the pressure energy recovery container 1 and the membrane module 2 for a preset flushing time, discharging the flushed water collected into the pressure energy recovery container 1 through a first discharge pipeline 31 and a second discharge pipeline 32 corresponding to each other by using a circulating pump M2 and a high-pressure pump M1 respectively, wherein the flow direction of the fluid in the step is shown by arrows in FIG. 4, and then repeating the steps 1) -5).

As shown in fig. 5 and with reference to fig. 1-4, the membrane module 2 includes a plurality of modules arranged in parallel, each module having 1-3 reverse osmosis membrane elements 21 arranged in series within the same membrane housing 20, the membrane module 2 having a total saltwater inlet 22, a total freshwater outlet 24, and a total concentrate outlet 26. In one embodiment, reverse osmosis membrane element 21 is a 4 inch diameter reverse osmosis membrane and has an optimal water feed flow of 2-3 m for a full harvest; in another embodiment, reverse osmosis membrane element 21 is a reverse osmosis membrane with a diameter of 8 inches and the optimal water supply flow rate is 8-12 m/h.

As shown in fig. 1, a ninth electromagnetic valve X9, a high-pressure pump M1, a first normally open manual valve S1 and a first electromagnetic valve X1 are sequentially arranged on the first liquid inlet pipeline 11 in the liquid inlet direction; a seventh electromagnetic valve X7, a high-pressure pump M1, a first normally open manual valve S1 and a third electromagnetic valve X3 are sequentially arranged on the first liquid discharge pipeline 31 in the liquid discharge direction; an eighth electromagnetic valve X8, a second one-way valve Z2, a high-pressure pump M1, a first normally open manual valve S1 and a first electromagnetic valve X1 are arranged on the first fresh water flushing pipeline 51 according to the flushing direction; a ninth electromagnetic valve X9, a fifth electromagnetic valve X5, a first one-way valve Z1, a circulating pump M2, a second normally open manual valve S2, a membrane module 2 and a second electromagnetic valve X are sequentially arranged on the second liquid inlet pipeline 12 in the liquid inlet direction; a seventh electromagnetic valve X7, a fifth electromagnetic valve X5, a first check valve Z1, a circulating pump M2, a second normally open manual valve S2 and a fourth electromagnetic valve X4 are sequentially arranged on the second liquid discharge pipeline 32 in the liquid discharge direction; an eighth electromagnetic valve X8, a second one-way valve Z2, a circulating pump M2, a second normally open manual valve S2, the membrane module 2 and a second electromagnetic valve X2 are arranged on the second fresh water flushing pipeline 52 according to the flushing direction; the reverse osmosis pipeline 21 is provided with a second electromagnetic valve X2, a membrane module 2, a second normally open manual valve S2, a circulating pump M2 and a sixth electromagnetic valve X6 in the reverse osmosis direction; the pressure energy recovery container 1 is provided with a tenth electromagnetic valve X10.

As shown in fig. 1 to 4, the first liquid inlet line 11, the first liquid outlet line 31, and the first fresh water flushing line 51 have a first common line on which the high-pressure pump M1 is provided; the second liquid inlet pipeline 12, the reverse osmosis pipeline 21, the second liquid discharge pipeline 32 and the second fresh water flushing pipeline 52 are provided with a second common pipeline, and the circulating pump M2 is arranged on the second common pipeline; among them, the high-pressure pump M1 is configured as a variable-frequency high-pressure pump, for example, in a manner that the high-pressure pump M1 is connected with an inverter B1, and the circulation pump M2 is configured as a variable-frequency circulation pump, for example, in a manner that the circulation pump M2 is connected with an inverter B2; the start and stop of each pump is controlled by a PLC controller (not shown), and the opening and closing of each pipeline is controlled by the PLC controller by means of the valves.

Specifically, before the start of step 1), the first solenoid valve X1, the second solenoid valve X2, the third solenoid valve X3, the fourth solenoid valve X4, the fifth solenoid valve X5, the sixth solenoid valve X6, the seventh solenoid valve X7, the eighth solenoid valve X8, the ninth solenoid valve X9, and the tenth solenoid valve X10 are normally closed by the control of the PLC controller;

in step 1), the first solenoid valve X1, the second solenoid valve X2, the fifth solenoid valve X5, the ninth solenoid valve X9 and the tenth solenoid valve X10 are brought into an open state, the third solenoid valve X3, the fourth solenoid valve X4, the sixth solenoid valve X6, the seventh solenoid valve X7 and the eighth solenoid valve X8 are brought into a closed state, and the high-pressure pump M1 and the circulation pump M2 are activated for the first predetermined time by the control of the PLC controller. In the present embodiment, the first predetermined time is 5 min.

In step 2), the first solenoid valve X1, the second solenoid valve X2, the sixth solenoid valve X6 and the ninth solenoid valve X9 are in an open state, the third solenoid valve X3, the fourth solenoid valve X4, the fifth solenoid valve X5, the seventh solenoid valve X7, the eighth solenoid valve X8 and the tenth solenoid valve X10 are in a closed state, and the high-pressure pump M1 and the circulation pump M2 continue to operate for a second predetermined time, that is, a predetermined reverse osmosis time, by the control of the PLC controller. Further, the predetermined reverse osmosis time was 34.5 min.

In step 3), the third solenoid valve X3, the fourth solenoid valve X4, the fifth solenoid valve X5 and the seventh solenoid valve X7 are in an open state and the tenth solenoid valve X10 is opened after delaying for a third predetermined time under the control of the PLC controller, while the first solenoid valve X1, the second solenoid valve X2, the sixth solenoid valve X6, the eighth solenoid valve X8, the ninth solenoid valve X9 and the tenth solenoid valve X10 are in a closed state, and the high-pressure pump M1 and the circulation pump M2 continue to operate for a fourth predetermined time. In the present embodiment, the third predetermined time may be 5S, and the fourth predetermined time may be 5 min.

In step 5), the first solenoid valve X1, the second solenoid valve X2, the fifth solenoid valve X5, the eighth solenoid valve X8 and the tenth solenoid valve X10 are in an open state, the third solenoid valve X3, the fourth solenoid valve X4, the sixth solenoid valve X6, the seventh solenoid valve X7 and the ninth solenoid valve X9 are in a closed state, after the state lasts for a fifth predetermined time, the third solenoid valve X3, the fourth solenoid valve X4, the fifth solenoid valve X5, the seventh solenoid valve X7 and the tenth solenoid valve X10 are in an open state, the first solenoid valve X1, the second solenoid valve X2, the sixth solenoid valve X6, the eighth solenoid valve X8 and the ninth solenoid valve X9 are in a closed state, and after the state lasts for a sixth predetermined time, the step 1) is returned. In the present embodiment, the fifth predetermined time may be 3min, and the sixth predetermined time may be 3 min.

It should be noted that although specific values are given for the times and periods of steps 1) to 5) in the present embodiment, it should be understood that in other embodiments, the times and periods may be adjusted according to actual needs to meet different requirements. In the whole process from step 1) to step 5), the high-pressure pump M1 and the circulation pump M2 are both operated at all times, and are not stopped without failure, and are stopped only when desalination production is not performed.

As shown in fig. 1 to 4, the first liquid inlet pipeline 11, the first liquid outlet pipeline 31 and the first fresh water flushing pipeline 51 are respectively provided with one electromagnetic valve on two sides of the first common pipeline for controlling the opening and closing of the pipelines, specifically, as shown in fig. 1, the first liquid inlet pipeline 11 is respectively provided with a ninth electromagnetic valve X9 and a first electromagnetic valve X1 on two sides of the first common pipeline; as shown in fig. 3, the first drain line 31 is provided with a seventh solenoid valve X7 and a third solenoid valve X3 on both sides of the first common line; as shown in fig. 4, the first fresh water flushing line 51 is provided with an eighth solenoid valve X8 and a first solenoid valve X1 on both sides of the first common line, respectively;

the second inlet line 12, the second outlet line 32, and the second fresh water flush line 52 have a third common line that includes the second common line and includes a fifth solenoid valve X5, which is one solenoid valve located outside the second common line, and a first check valve Z1, which is one check valve located between the fifth solenoid valve X5 and the second common line. The second liquid inlet line 12, the second liquid outlet line 32, and the second fresh water flushing line 52 are each provided with one solenoid valve on each of two sides of the third common line to control the opening and closing of the lines, specifically, as shown in fig. 1, the second liquid inlet line 12 is provided with a ninth solenoid valve X9 and a second solenoid valve X2 on each of two sides of the third common line, as shown in fig. 3, the second liquid outlet line 32 is provided with a seventh solenoid valve X7 and a fourth solenoid valve X4 on each of two sides of the third common line, as shown in fig. 4, the second fresh water flushing line 52 is provided with an eighth solenoid valve X8 and a second solenoid valve X2 on each of two sides of the third common line; as shown in fig. 2, the reverse osmosis pipeline 21 is provided with a solenoid valve X on each side of the second common pipeline for controlling the opening and closing thereof, and specifically, is provided with a second solenoid valve X2 and a sixth solenoid valve X6 on each side of the second common pipeline.

As shown in fig. 2 and referring to fig. 1 and 4, the second liquid inlet line 12, the reverse osmosis line 21, and the second fresh water flushing line 52 have a fourth common line including the second common line and including the membrane module 2 located outside the second common line and one electromagnetic valve for opening and closing the lines, i.e., a second electromagnetic valve X9, located between the membrane module 2 and the pressure energy recovery vessel 1; the first and second fresh water flushing lines 51 and 52 have a common fresh water inlet line, and an eighth solenoid valve X8 as a solenoid valve for controlling the opening and closing of the lines and a second check valve Z2 as a check valve are provided on the common fresh water inlet line.

As shown in fig. 1 to 4, in the present embodiment, in order to protect the pressure energy recovery container 1 from high pressure, the tenth electromagnetic valve X10, a mechanical relief valve V1 and a pressure-sensitive gauge P1 are provided, so that when the pressure-sensitive gauge P1 reaches a first predetermined pressure value, for example, 5.5MPa, the tenth electromagnetic valve X10 is opened to relieve the pressure; when the pressure sensing meter P1 reaches a second preset pressure value, for example 7MPa, the mechanical pressure relief valve V1 is opened to relieve the pressure; in addition, when the frequency converters B1 and B2 respectively detect that the high-pressure pump M1 and the circulating pump M2 are overloaded, the frequency converters communicate with the PLC controller and control the high-pressure pump M1 and the circulating pump M2 to stop.

Note that, in the present embodiment, as shown in fig. 1 to 4 and with reference to fig. 5, the first liquid inlet line 11 and the second liquid inlet line 12 have a common brine inlet 120; the first drain line 31 and the second drain line 32 have a common drain outlet 320; the first and second fresh water flush lines 51 and 52 have a common fresh water inlet 520; fresh water produced by the membrane modules 2 flows out through the total fresh water outlet 24. It should be understood that the brine inlet 120 described above communicates with, for example, the brine basin 14; the drain outlet 320 is, for example, in communication with the concentrate tank 34; the fresh water inlet 520 and the total fresh water outlet 24 may be in communication with the same fresh water basin 54.

Additionally, it should be understood that in the feed process shown in FIG. 1, the membrane modules 2 do not undergo reverse osmosis, but rather act as water pathways, and that in the feed process, brine enters the membrane modules 2 from the total concentrate outlet 26 of the membrane modules 2, then exits the total brine inlet 22 of the membrane modules 2, and finally enters the pressure energy recovery vessel 1.

While the technical features of the present invention have been disclosed above, it is to be understood that various changes and modifications in structure may be suggested to one skilled in the art, which includes all the features disclosed herein either individually or in any combination as deemed to be evident from the teachings herein. Such variations and/or combinations are within the skill of the art to which the invention pertains and are within the scope of the following claims.