CN109305720B - A reverse osmosis seawater desalination system with two-stage residual pressure recovery and a seawater desalination treatment method based thereon - Google Patents

Abstract

The invention discloses a reverse osmosis seawater desalination system with two-stage residual pressure recovery and a seawater desalination treatment method based on the same, comprising a seawater supply pump, a high-pressure pump, two groups of pressure energy exchangers and a membrane module. The seawater is increased by the seawater supply pump. In the pressure input system, the high-pressure concentrated brine transfers the pressure energy to a low-pressure seawater in the A pressure energy exchanger. After the seawater is pressurized, the pressure energy is transferred to another low-pressure seawater in the B pressure energy exchanger. The invention proposes a new reverse osmosis seawater desalination system with two-stage residual pressure recovery. Two sets of pressure energy recovery equipment are used to recover and utilize the pressure energy of high-pressure concentrated brine in two-stage residual pressure, which reduces the use of booster pumps and can Flexible adjustment of the water recovery rate of the reverse osmosis desalination system has the advantages of compact structure, flexible operation, high efficiency and energy saving.

Description

A reverse osmosis seawater desalination system with two-stage residual pressure recovery and seawater desalination based thereon Chemical processing method

technical field

The invention belongs to the technical field of seawater desalination, and relates to a reverse osmosis seawater desalination system with two-stage residual pressure recovery and a seawater desalination treatment method based thereon.

Background technique

The reverse osmosis seawater desalination technology uses a high-pressure pump to pressurize the seawater to make the pressure reach the required operating pressure, and then passes the pressurized seawater into the reverse osmosis membrane module for osmotic separation, and the desalinated water passing through the reverse osmosis membrane It becomes the product water, and the high-pressure concentrated brine that does not pass through the reverse osmosis membrane is discharged from the system.

Improving the technology of reverse osmosis system is an important way to optimize the performance of reverse osmosis desalination system. Specifically, Chinese patent (CN203402976U) discloses a cyclic reverse osmosis system, the raw water tank is connected to a filter through a conduit, the filter is connected to a permeation device through a booster pump, and the concentrated water outlet of the permeation device is connected to the original water tank, through Re-injecting concentrated water into the original water tank can improve the utilization rate of water resources; Chinese patent (CN106145267A) discloses a membrane seawater desalination system, including high-pressure pump, membrane module, booster pump, energy recovery device, etc. The seawater is pressurized and sent to the membrane module for osmotic separation, and the pressure energy of the high-pressure concentrated brine discharged from the reverse osmosis membrane module is transferred to the seawater to be pressurized through the energy recovery device, and the lost pressure drop is supplemented by the booster pump.

Although the technical solutions disclosed in the above two patents both propose a process improvement method for the reverse osmosis seawater desalination system, which reduces the energy consumption per unit of product water. However, the former does not use excess pressure recovery technology, and the energy utilization rate of the system is still not high; the latter system is more complex, including booster pumps and other devices, which increases the site area occupied by equipment investment costs.

SUMMARY OF THE INVENTION

In order to overcome the shortcoming of the above-mentioned prior art, the object of the present invention is to provide a reverse osmosis seawater desalination system with two-stage residual pressure recovery and a seawater desalination treatment method based thereon. The pressure can be used for two-stage residual pressure recovery, compact structure, reasonable design, easy to use, high efficiency and energy saving.

In order to achieve the above object, the present invention adopts the following technical solutions to be realized:

The invention discloses a reverse osmosis seawater desalination system with two-stage residual pressure recovery, comprising a seawater supply pump, an A pressure energy exchanger, a B pressure energy exchanger and a membrane module; between the B pressure energy exchanger and the membrane module, there is also a Equipped with high pressure pump;

The outlet of the seawater supply pump is divided into two paths, one is connected to the A pressure energy exchanger through the A low pressure inlet, and the other is connected to the B pressure energy exchanger through the B low pressure inlet;

The A high pressure outlet of the A pressure energy exchanger is connected to the B high pressure inlet of the B pressure energy exchanger for conveying high pressure seawater; the B low pressure outlet and the B high pressure outlet of the B pressure energy exchanger are respectively connected to the inlet of the high pressure pump through pipelines. The water outlet, the water outlet of the high pressure pump is connected with the water inlet pipe of the membrane module;

The membrane module is connected with two water outlet pipes, one is used to output desalinated water permeating the reverse osmosis membrane, and the other is connected to the A high pressure inlet of the A pressure energy exchanger, which is used to transport the unpermeated reverse osmosis to the A pressure energy exchanger. Membrane high pressure brine.

Preferably, the flow rates of the high-pressure concentrated brine and the high-pressure seawater passing into the A pressure energy exchanger are equal;

A pressure energy exchanger adopts rotary pressure energy exchanger, valve-controlled pressure energy exchanger, sliding vane pressure energy exchanger or hydraulic turbine.

Preferably, the pressures of the two seawater flows from the B low pressure outlet and the B high pressure outlet of the B pressure energy exchanger are equal.

Preferably, the flow ratio of the two seawater flows into the B pressure energy exchanger is adjusted according to the water recovery rate of the seawater desalination system.

The invention also discloses the seawater desalination treatment method of the reverse osmosis seawater desalination system with the above-mentioned two-stage residual pressure recovery, comprising the following steps:

1) Input the seawater to be treated into the seawater supply pump for pressurization treatment, a low-pressure seawater after pressurization flows into the A pressure energy exchanger through the A low-pressure inlet, and another low-pressure seawater after the pressurization flows into the B low-pressure inlet. B in the pressure energy exchanger;

2) The high-pressure concentrated brine that does not pass through the reverse osmosis membrane in the membrane module flows into the A pressure energy exchanger through the A high-pressure inlet, and the high-pressure concentrated brine in the A pressure energy exchanger does work on the inflowing low-pressure seawater, and after the work is done, the concentrated brine pressure The lower pressure flows out from the low-pressure outlet of A as waste water, and the seawater pressure after the work is raised will flow out from the high-pressure outlet of A;

3) The high-pressure seawater after the above-mentioned pressure increase flows into the B pressure energy exchanger through the B high-pressure inlet, and performs work on the low-pressure seawater pressurized by the seawater supply pump, and the high-pressure seawater pressure after the work is reduced and flows out from the B low-pressure outlet. , the low-pressure seawater pressure is raised and flows out from the high-pressure outlet of B;

4) The seawater flowing from the low-pressure outlet of B and the high-pressure outlet of B merges and flows into the high-pressure pump. After being pressurized by the high-pressure pump, it enters the membrane module for osmotic separation. The high-pressure concentrated brine passing through the reverse osmosis membrane flows into the A pressure energy exchanger from the A high pressure inlet to complete the cycle until the seawater to be treated is treated or the system stops running.

The invention also discloses a reverse osmosis seawater desalination system with two-stage residual pressure recovery, comprising a seawater supply pump, A pressure energy exchanger, B pressure energy exchanger and a membrane assembly; between the seawater supply pump and B pressure energy exchanger There is also a high-pressure pump in the room;

The outlet of the seawater supply pump is divided into two paths, one is connected to the A pressure energy exchanger through the A low pressure inlet, the other is connected to the water inlet of the high pressure pump, and the water outlet of the high pressure pump is connected to the B pressure energy exchanger through the B low pressure inlet;

The A high pressure outlet of the A pressure energy exchanger is connected to the B high pressure inlet of the B pressure energy exchanger, which is used to transport high-pressure seawater; the B low pressure outlet and the B high pressure outlet of the B pressure energy exchanger are respectively connected to the inlet of the membrane module through pipelines. water pipe.

The membrane module is connected with two water outlet pipes, one is used to output desalinated water permeating the reverse osmosis membrane, and the other is connected to the A high pressure inlet of the A pressure energy exchanger, which is used to transport the unpermeated reverse osmosis to the A pressure energy exchanger. Membrane high pressure brine.

Preferably, the pressures of the seawater flowing from the B low pressure outlet and the B high pressure outlet of the B pressure energy exchanger are equal.

Preferably, the two seawater flows into the B pressure energy exchanger are equal in flow; the B pressure energy exchanger adopts a rotary pressure energy exchanger, a valve-controlled pressure energy exchanger, a sliding vane pressure energy exchanger or a hydraulic turbine .

Preferably, the flow ratio of the high-pressure concentrated brine and the high-pressure seawater introduced into the A pressure energy exchanger is adjusted according to the water recovery rate of the seawater desalination system.

The invention also discloses a seawater desalination treatment method based on the above-mentioned two-stage residual pressure recovery reverse osmosis seawater desalination system, which is characterized by comprising the following steps:

1) Input the seawater to be treated into the seawater supply pump for pressurization treatment, a low-pressure seawater after pressurization flows into the A pressure energy exchanger through the A low-pressure inlet, and another low-pressure seawater after the pressurization flows into the B low-pressure inlet. Pressurization in the high-pressure pump;

2) The high-pressure concentrated brine that does not pass through the reverse osmosis membrane in the membrane module flows into the A pressure energy exchanger through the A high-pressure inlet, and the high-pressure concentrated brine in the A pressure energy exchanger does work on the inflowing low-pressure seawater, and after the work is done, the concentrated brine pressure The lower pressure flows out from the low-pressure outlet of A as waste water, and the seawater pressure after the work is raised will flow out from the high-pressure outlet of A;

3) The high-pressure seawater after the above-mentioned pressure increase flows into the B pressure energy exchanger through the B high-pressure inlet, and performs work on the low-pressure seawater that has been pressurized by the high-pressure pump, and the high-pressure seawater pressure after the work is reduced and flows out from the B low-pressure outlet, The low pressure seawater pressure is raised and flows out from the B high pressure outlet;

4) The seawater flowing from the low-pressure outlet of B and the high-pressure outlet of B merges and flows into the membrane module for osmotic separation. Part of the seawater passes through the reverse osmosis membrane to become desalinated water and flows out through the pipeline. The high pressure inlet flows into the A pressure energy exchanger to complete the cycle until the seawater to be treated is processed or the system stops running.

Compared with the prior art, the present invention has the following beneficial effects:

The reverse osmosis seawater desalination system with two-stage residual pressure recovery disclosed in the present invention includes a seawater supply pump, a high-pressure pump, two sets of pressure energy exchangers and membrane modules. The seawater is pressurized by the seawater supply pump and then fed into the system. The pressure energy is transferred to a low-pressure seawater in the pressure energy exchanger, and after the seawater is pressurized, the pressure energy is transferred to another low-pressure seawater in the B pressure energy exchanger. The seawater desalination system of the invention has a compact structure, is simple and flexible, easy to use, and has high efficiency and energy saving. First, compared with the traditional reverse osmosis desalination system, the use of booster pumps is reduced, which saves equipment investment and site space; secondly, the system uses energy recovery technology to recover the pressure energy of high-pressure concentrated brine, and uses secondary residual pressure recovery technology to increase It can greatly reduce the energy consumption of the high-pressure pump.

Preferably, a sliding vane pressure energy exchanger or a hydraulic turbine with an asymmetrical boosting chamber and a depressurizing chamber structure can be used for the pressure energy exchanger as required, and used in reverse osmosis systems with different water recovery rates. Different desalinated water salinity can meet different process requirements.

Description of drawings

Fig. 1 is the structural representation of the reverse osmosis seawater desalination system of the two-stage residual pressure recovery of the embodiment of the present invention 1;

2 is a schematic structural diagram of a reverse osmosis seawater desalination system with two-stage residual pressure recovery in Example 2 of the present invention.

Among them: 1 is the seawater supply pump; 2 is the A pressure energy exchanger; 3 is the B pressure energy exchanger; 4 is the high pressure pump; 5 is the membrane module; 6 is the A high pressure inlet; 7 is the A low pressure outlet; 8 is the A low pressure 9 is A high pressure outlet; 10 is B high pressure inlet; 11 is B low pressure outlet; 12 is B low pressure inlet; 13 is B high pressure outlet.

Detailed ways

In order to make those skilled in the art better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only Embodiments are part of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

It should be noted that the terms "first", "second" and the like in the description and claims of the present invention and the above drawings are used to distinguish similar objects, and are not necessarily used to describe a specific sequence or sequence. It is to be understood that the data so used may be interchanged under appropriate circumstances such that the embodiments of the invention described herein can be practiced in sequences other than those illustrated or described herein. Furthermore, the terms "comprising" and "having" and any variations thereof, are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those expressly listed Rather, those steps or units may include other steps or units not expressly listed or inherent to these processes, methods, products or devices.

Below in conjunction with accompanying drawing, the present invention is described in further detail:

Example 1

Referring to FIG. 1, a reverse osmosis seawater desalination system with two-stage residual pressure recovery disclosed in this embodiment includes: a seawater supply pump 1, A pressure energy exchanger 2, B pressure energy exchanger 3 and membrane module 5. A high pressure pump 4 is also provided between the B pressure energy exchanger 3 and the membrane module 5 . The outlet of the seawater supply pump 1 is divided into two paths, one is connected to the A pressure energy exchanger 2 through the A low pressure inlet 8, and the other is connected to the B pressure energy exchanger 3 through the B low pressure inlet 12;

The A high pressure outlet 9 of the A pressure energy exchanger 2 is connected with the B high pressure inlet 10 of the B pressure energy exchanger 3 for conveying high-pressure seawater; the B low pressure outlet 11 and the B high pressure outlet 13 of the B pressure energy exchanger 3 pass through pipes respectively. The road is connected to the water inlet of the high-pressure pump 4, and the water outlet of the high-pressure pump 4 is connected to the water inlet pipe of the membrane module 5;

The membrane module 5 is connected with two water outlet pipes, one is used to output the desalinated water passing through the reverse osmosis membrane, and the other is connected to the A high pressure inlet 6 of the A pressure energy exchanger 2, and is used to deliver the untreated water to the A pressure energy exchanger 2. High pressure brine passing through the reverse osmosis membrane.

The pretreated seawater is pressurized and fed into the system by the seawater supply pump 1, and one of the low-pressure seawater after the pressurization flows into the A pressure energy exchanger 2 through the A low pressure inlet 8, and the high pressure concentration that does not pass through the reverse osmosis membrane of the membrane module 5 is concentrated. The brine flows into the A pressure energy exchanger 2 through the A high pressure inlet 6, and the high pressure concentrated brine in the A pressure energy exchanger 2 performs work on the low pressure seawater. The high pressure flows out from the A high pressure outlet 9; the high pressure seawater flowing out from the A high pressure outlet 9 flows into the B pressure energy exchanger 3 through the B high pressure inlet 10, and another low pressure seawater after being pressurized by the seawater supply pump 1 is input through the B low pressure inlet 12. B pressure energy exchanger 3, in the B pressure energy exchanger, the high pressure sea water does work on the low pressure sea water, after the work, the high pressure sea water pressure decreases and flows out from the B low pressure outlet 11, and the low pressure sea water pressure rises and flows out from the B high pressure outlet 13; The seawater flowing out of the outlet 11 and the high-pressure outlet 13 of the B merges and flows into the high-pressure pump 4. After being pressurized by the high-pressure pump 4, it is input to the membrane module 5 for osmotic separation. A part of the desalinated water passing through the reverse osmosis membrane becomes the product water, and the rest does not pass through. The high pressure concentrated brine of the reverse osmosis membrane flows into the A pressure energy exchanger 2 from the A high pressure inlet 6 to form a cycle.

Specifically, given the operating parameters of the seawater desalination system, as a specific application example: the pressure of the pretreated seawater is 0MPa and the flow rate is 60m ³ /h by the seawater supply pump 1 to pressurize the input system to 0.3MPa. One of the low-pressure seawater with a pressure of 0.3MPa and a flow rate of 36m ³ /h flows into the A pressure energy exchanger 2 through the A low-pressure inlet 8, and the high-pressure concentrated brine that has not passed through the reverse osmosis membrane of the membrane module 5 has a pressure of 5.4MPa and a flow rate of 36m ³ /h. The A high pressure inlet 6 flows into the A pressure energy exchanger 2. In the A pressure energy exchanger 2, the high pressure concentrated brine pressure is 5.4 MPa and the flow rate is 36 ^{m 3 /} h. The brine pressure is reduced to 0.3MPa and flows out of the system from the A low pressure outlet 7 as waste water, and the seawater pressure rises to 5.145MPa and flows out from the A high pressure outlet 9; the high pressure seawater flowing out from the A high pressure outlet 9 has a pressure of 5.145MPa and a flow rate of 36m ³ /h through B The high pressure inlet 10 flows into the B pressure energy exchanger 3, and the other low pressure seawater pressure 0.3MPa and flow rate 24m ³ /h after being pressurized by the seawater supply pump 1 is input into the B pressure energy exchanger 3 through the B low pressure inlet 12, at the B pressure The high-pressure seawater pressure in the energy exchanger is 5.145MPa and the flow rate is 36m ³ /h. Work is performed on the low-pressure sea water pressure of 0.3MPa and the flow rate is 24m ³ /h. Up to 3.147MPa flows out from B high pressure outlet 13; after the seawater flowing out from B low pressure outlet 11 and B high pressure outlet 13 merges, the pressure is 3.147MPa and the flow rate is 60m ³ /h and flows into high pressure pump 4, which is pressurized to 5.5MPa input by high pressure pump 4 The membrane module 5 conducts osmosis separation, part of the desalinated water passing through the reverse osmosis membrane becomes product water, and the remaining high-pressure concentrated brine that has not passed through the reverse osmosis membrane flows into the A pressure energy exchanger 2 from the A high pressure inlet 6 to form a cycle.

It should be noted that the above pressure values all refer to gauge pressure, the energy recovery efficiency of the A pressure energy exchanger 2 and the B pressure energy exchanger 3 are both set to 95%, and the internal leakage of the equipment is ignored.

Further, in the reverse osmosis seawater desalination system of the two-stage residual pressure recovery, the pressures of the seawater flowing out from the B low pressure outlet 11 and the B high pressure outlet 13 of the B pressure energy exchanger 3 are equal, and after the two streams with equal pressures converge. into the high-pressure pump 4 .

In the reverse osmosis seawater desalination system with two-stage residual pressure recovery, the flow rates of the high-pressure concentrated brine and seawater entering the A pressure energy exchanger 2 are equal. According to the characteristics of the two flows into the A pressure energy exchanger 2, the A pressure energy exchanger 2 can be a rotary pressure energy exchanger, a valve-controlled pressure energy exchanger, a sliding vane pressure energy exchanger or a hydraulic penetrator. equality.

The reverse osmosis seawater desalination system with two-stage residual pressure recovery can adjust the flow ratio of the two seawater flows into the B pressure energy exchanger 3 to obtain the water recovery rate of different seawater desalination systems and adapt to different process requirements. According to the characteristics of the two flows into the B pressure energy exchanger 3, the B pressure energy exchanger 3 can be a sliding vane pressure energy exchanger or a hydraulic turbine. By adjusting the sliding vane pressure energy exchanger or the hydraulic turbine The structural parameters of the flat asymmetric pressurization chamber and the depressurization chamber can achieve the goal of adjusting the flow ratio.

Example 2

Referring to FIG. 2, a reverse osmosis seawater desalination system with two-stage residual pressure recovery disclosed in this embodiment includes a seawater supply pump 1, A pressure energy exchanger 2, B pressure energy exchanger 3 and membrane module 5, and the implementation of The difference from Example 1 is that the high pressure pump 4 can also be placed after the seawater supply pump 1 and before the B pressure energy exchanger 3 .

The outlet of the seawater supply pump 1 is divided into two paths, one is connected to the A pressure energy exchanger 2 through the A low pressure inlet 8, and the other is connected to the water inlet of the high pressure pump 4, and the water outlet of the high pressure pump 4 is connected to the B pressure energy through the B low pressure inlet 12. switch 3;

The A high pressure outlet 9 of the A pressure energy exchanger 2 is connected with the B high pressure inlet 10 of the B pressure energy exchanger 3 for conveying high-pressure seawater; the B low pressure outlet 11 and the B high pressure outlet 13 of the B pressure energy exchanger 3 pass through pipes respectively. The road is connected to the water inlet pipe of the membrane module 5;

The membrane module 5 is connected with two water outlet pipes, one is used to output the desalinated water passing through the reverse osmosis membrane, and the other is connected to the A high pressure inlet 6 of the A pressure energy exchanger 2, and is used to deliver the untreated water to the A pressure energy exchanger 2. High pressure brine passing through the reverse osmosis membrane.

The pretreated seawater is pressurized and fed into the system by the seawater supply pump 1, and one of the low-pressure seawater after the pressurization flows into the A pressure energy exchanger 2 through the A low pressure inlet 8, and the high pressure concentration that does not pass through the reverse osmosis membrane of the membrane module 5 is concentrated. The brine flows into the A pressure energy exchanger 2 through the A high pressure inlet 6, and the high pressure concentrated brine in the A pressure energy exchanger 2 performs work on the low pressure seawater. The high pressure flows out from the A high pressure outlet 9; the high pressure seawater flowing out from the A high pressure outlet 9 flows into the B pressure energy exchanger 3 through the B high pressure inlet 10, and another low pressure seawater after being pressurized by the seawater supply pump 1 flows into the high pressure pump 4 for increase. pressure, and then input into B pressure energy exchanger 3 through B low pressure inlet 12. In B pressure energy exchanger 3, high pressure seawater does work on low pressure seawater. After the work is done, the pressure of high pressure seawater decreases and flows out from B low pressure outlet 11, and the pressure of low pressure seawater increases. Flow out from the B high pressure outlet 13; the seawater flowing out from the B low pressure outlet 11 and the B high pressure outlet 13 is merged and then fed into the membrane module 5 for osmosis separation, part of the desalinated water passing through the reverse osmosis membrane becomes product water, and the rest does not pass through the reverse osmosis. The high-pressure concentrated brine of the membrane flows into the A-pressure energy exchanger 2 from the A high-pressure inlet 6 to form a cycle.

Specifically, given the operating parameters of the seawater desalination system, as an embodiment of the present invention: the pressure of the pretreated seawater is 0MPa, the flow rate is 60m ³ /h, and the seawater supply pump 1 is pressurized to 0.3MPa and the input system is pressurized. One of the latter low-pressure seawater has a pressure of 0.3MPa and a flow rate of 30m ³ /h and flows into the A pressure energy exchanger 2 through the A low-pressure inlet ⁸ . h flows into the A pressure energy exchanger 2 through the A high pressure inlet 6, and in the A pressure energy exchanger 2, the high pressure concentrated brine pressure is ^5.4MPa , and the flow rate is 36m ³ /h. After the concentrated brine pressure is reduced to 0.3MPa, it flows out of the system from the A low pressure outlet 7 as waste water, and the seawater pressure rises to 6.11MPa and flows out from the A high pressure outlet 9; the high pressure seawater flowing out from the A high pressure outlet 9 has a pressure of 6.11MPa and a flow rate of 30m ³ /h. It flows into the B pressure energy exchanger 3 through the B high pressure inlet 10. After being pressurized by the seawater supply pump 1, another low-pressure seawater with a pressure of 0.3 MPa and a flow rate of 30 m ³ /h flows into the high pressure pump 4 and pressurized to 4.92 MPa, and then passes through the B The low-pressure inlet 12 is input to the B pressure energy exchanger 3. In the B pressure energy exchanger 3, the high-pressure seawater pressure is 6.11MPa and the flow rate is 30m ³ /h. Work is performed on the low-pressure sea water pressure 4.92MPa and the flow rate 30m ³ /h. After the work is done, the high-pressure seawater pressure It is reduced to 5.5MPa and flows out from the B low pressure outlet 11, and the low pressure seawater pressure rises to 5.5MPa and flows out from the B high pressure outlet 13; the seawater flowing out from the B low pressure outlet 11 and the B high pressure outlet 13 merges and enters the membrane module 5 for permeation separation. The desalinated water passing through the reverse osmosis membrane becomes product water, and the remaining high-pressure concentrated brine that has not passed through the reverse osmosis membrane flows into the A pressure energy exchanger 2 from the A high pressure inlet 6 to form a cycle.

It should be noted that the above pressure values all refer to gauge pressure, the energy recovery efficiency of the A pressure energy exchanger 2 and the B pressure energy exchanger 3 are both set to 95%, and the internal leakage of the equipment is ignored.

Further, in the reverse osmosis seawater desalination system of the two-stage residual pressure recovery, the pressures of the seawater flowing out from the B low pressure outlet 11 and the B high pressure outlet 13 of the B pressure energy exchanger 3 are equal, and after the two streams with equal pressures converge. into the membrane module 5 .

The reverse osmosis seawater desalination system with two-stage residual pressure recovery can adjust the flow ratio of the concentrated brine and seawater entering the A pressure energy exchanger 2 to obtain the water recovery rate of different seawater desalination systems and adapt to different process requirements. According to the characteristics of the two flows into the A pressure energy exchanger 2, the A pressure energy exchanger 2 can be a sliding vane pressure energy exchanger or a hydraulic turbine. By adjusting the sliding vane pressure energy exchanger or the hydraulic turbine The structural parameters of the flat asymmetric pressurization chamber and the depressurization chamber can achieve the goal of adjusting the flow ratio.

In the reverse osmosis seawater desalination system of the two-stage residual pressure recovery, the two seawater flows into the B pressure energy exchanger 3 are equal in flow. According to the characteristics of the two flows into the B pressure energy exchanger 3, the B pressure energy exchanger 3 can be a rotary pressure energy exchanger, a valve-controlled pressure energy exchanger, a sliding vane pressure energy exchanger or a hydraulic penetrator. equality.

The reverse osmosis seawater desalination system with two-stage residual pressure recovery of the present invention adopts two sets of pressure energy recovery equipment to recover the pressure energy of high-pressure concentrated brine in two-stage residual pressure recovery. The advantages of the present invention are:

1 A reverse osmosis seawater desalination system using two-stage pressure energy recovery equipment to produce desalinated water is proposed, which has the advantages of compact structure, simple and flexible, easy to use, high efficiency and energy saving;

2 Compared with the traditional reverse osmosis seawater desalination system, it can reduce the use of booster pump, save the cost investment of booster pump equipment and the space occupied by the site;

3. The energy recovery technology is used to recover the pressure energy of the high-pressure concentrated brine, and the secondary residual pressure recovery technology is used to pressurize the seawater stream output from the high-pressure pump, which reduces the energy consumption of the high-pressure pump;

4 The pressure energy exchanger can be used in the reverse osmosis system with different reverse osmosis membrane permeability by adopting the sliding vane pressure energy exchanger or hydraulic turbine with the structure of asymmetric pressure boosting chamber and pressure reducing chamber according to the needs. The salinity of the desalinated water can meet different process requirements.

The above content is only to illustrate the technical idea of the present invention, and cannot limit the protection scope of the present invention. Any modification made on the basis of the technical solution proposed in accordance with the technical idea of the present invention falls within the scope of the claims of the present invention. within the scope of protection.

Claims (8)

1. A reverse osmosis seawater desalination system with two-stage residual pressure recovery is characterized by comprising a seawater supply pump (1), an A pressure energy exchanger (2), a B pressure energy exchanger (3) and a membrane assembly (5); a high-pressure pump (4) is also arranged between the pressure energy exchanger (3) and the membrane component (5);

the outlet of the seawater supply pump (1) is divided into two paths, one path is connected with the pressure energy exchanger (2) A through the low-pressure inlet (8) A, and the other path is connected with the pressure energy exchanger (3) B through the low-pressure inlet (12) B;

the A high-pressure outlet (9) of the A pressure energy exchanger (2) is connected with the B high-pressure inlet (10) of the B pressure energy exchanger (3) and is used for conveying high-pressure seawater; a B low-pressure outlet (11) and a B high-pressure outlet (13) of the B pressure energy exchanger (3) are respectively connected with a water inlet of the high-pressure pump (4) through pipelines, and a water outlet of the high-pressure pump (4) is connected with a water inlet pipe of the membrane component (5);

the membrane component (5) is connected with two water outlet pipes, one of which is used for outputting the desalted water permeating through the reverse osmosis membrane, and the other of which is connected with the A high-pressure inlet (6) of the A pressure energy exchanger (2) and is used for conveying the high-pressure strong brine which does not permeate through the reverse osmosis membrane to the A pressure energy exchanger (2); the flow rates of the high-pressure strong brine and the high-pressure seawater introduced into the pressure energy exchanger (2) A are equal; the pressure of the two streams of seawater flowing out of the B low-pressure outlet (11) and the B high-pressure outlet (13) of the B pressure energy exchanger (3) is equal.

2. The two-stage residual pressure recovery reverse osmosis seawater desalination system of claim 1,

the pressure energy exchanger A (2) adopts a rotary pressure energy exchanger, a valve-controlled pressure energy exchanger, a sliding vane type pressure energy exchanger or a hydraulic turbine.

3. A two-stage residual pressure recovery reverse osmosis seawater desalination system as claimed in claim 1, wherein the flow ratio of the two streams of seawater introduced into the B pressure energy exchanger (3) is adjusted according to the water recovery rate of the seawater desalination system.

4. The seawater desalination treatment method of the reverse osmosis seawater desalination system based on the two-stage residual pressure recovery of any one of claims 1 to 3, characterized by comprising the following steps:

1) inputting seawater to be treated into a seawater supply pump (1) for pressurization treatment, wherein one pressurized low-pressure seawater flow into an A pressure energy exchanger (2) through an A low-pressure inlet (8), and the other pressurized low-pressure seawater flow into a B pressure energy exchanger (3) through a B low-pressure inlet (12);

2) high-pressure strong brine which does not permeate a reverse osmosis membrane in the membrane component (5) flows into the pressure energy exchanger (2) through the high-pressure inlet (6) A, the high-pressure strong brine in the pressure energy exchanger (2) A does work on the inflowing low-pressure seawater, the pressure of the strong brine is reduced after the work is done and the strong brine flows out from the low-pressure outlet (7) A as wastewater, and the pressure of the seawater after the work is increased and then flows out from the high-pressure outlet (9) A;

3) the high-pressure seawater with the increased pressure flows into a pressure energy exchanger (3) of the system B through a high-pressure inlet (10) of the system B, the low-pressure seawater pressurized by a seawater supply pump (1) does work, the pressure of the high-pressure seawater after the work is reduced and flows out from a low-pressure outlet (11) of the system B, and the pressure of the low-pressure seawater is increased and flows out from a high-pressure outlet (13) of the system B;

4) the seawater flowing out of the low-pressure outlet (11) and the high-pressure outlet (13) of the water treatment system B is converged and then flows into the high-pressure pump (4), the seawater is pressurized by the high-pressure pump (4) and then is input into the membrane assembly (5) for permeation separation, a part of seawater permeates through the reverse osmosis membrane to become desalted water and flows out through a pipeline, and the rest high-pressure strong brine which does not permeate through the reverse osmosis membrane flows into the pressure energy exchanger (2) of the pressure energy exchanger A from the high-pressure inlet (6) of the pressure energy exchanger A to complete circulation until.

5. A reverse osmosis seawater desalination system with two-stage residual pressure recovery is characterized by comprising a seawater supply pump (1), an A pressure energy exchanger (2), a B pressure energy exchanger (3) and a membrane assembly (5); a high-pressure pump (4) is also arranged between the seawater supply pump (1) and the B pressure energy exchanger (3);

the outlet of the seawater supply pump (1) is divided into two paths, one path is connected with the pressure energy exchanger (2) A through a low-pressure inlet (8) A, the other path is connected with the water inlet of the high-pressure pump (4), and the water outlet of the high-pressure pump (4) is connected with the pressure energy exchanger (3) B through a low-pressure inlet (12) B;

the A high-pressure outlet (9) of the A pressure energy exchanger (2) is connected with the B high-pressure inlet (10) of the B pressure energy exchanger (3) and is used for conveying high-pressure seawater; a B low-pressure outlet (11) and a B high-pressure outlet (13) of the B pressure energy exchanger (3) are respectively connected to a water inlet pipe of the membrane module (5) through pipelines;

the membrane component (5) is connected with two water outlet pipes, one of which is used for outputting the desalted water permeating through the reverse osmosis membrane, and the other of which is connected with the A high-pressure inlet (6) of the A pressure energy exchanger (2) and is used for conveying the high-pressure strong brine which does not permeate through the reverse osmosis membrane to the A pressure energy exchanger (2); the pressure of the seawater flowing out of a low-pressure outlet (11) B and a high-pressure outlet (13) B of the pressure energy exchanger (3) B is equal; the flow rates of the two streams of seawater introduced into the pressure energy exchanger (3) B are equal.

6. A two-stage residual pressure recovery reverse osmosis seawater desalination system according to claim 5, wherein the B pressure energy exchanger (3) is a rotary pressure energy exchanger, a valve-regulated pressure energy exchanger, a sliding vane pressure energy exchanger or a hydraulic turbine.

7. A two-stage residual pressure recovery reverse osmosis seawater desalination system as claimed in claim 5, wherein the flow ratio of the high-pressure concentrated brine and the high-pressure seawater introduced into the A pressure energy exchanger (2) is adjusted according to the water recovery rate of the seawater desalination system.

8. The seawater desalination treatment method of the reverse osmosis seawater desalination system based on the two-stage residual pressure recovery of any one of claims 5 to 7, characterized by comprising the following steps:

1) inputting seawater to be treated into a seawater supply pump (1) for pressurization treatment, wherein one pressurized strand of low-pressure seawater flows into an A pressure energy exchanger (2) through an A low-pressure inlet (8), and the other pressurized strand of low-pressure seawater flows into a high-pressure pump (4) through a B low-pressure inlet (12) for pressurization;

2) high-pressure strong brine which does not permeate a reverse osmosis membrane in the membrane component (5) flows into the pressure energy exchanger (2) through the high-pressure inlet (6) A, the high-pressure strong brine in the pressure energy exchanger (2) A does work on the inflowing low-pressure seawater, the pressure of the strong brine is reduced after the work is done and the strong brine flows out from the low-pressure outlet (7) A as wastewater, and the pressure of the seawater after the work is increased and then flows out from the high-pressure outlet (9) A;

3) the high-pressure seawater with the increased pressure flows into a pressure energy exchanger (3) of the B through a high-pressure inlet (10) of the B, the low-pressure seawater subjected to pressurization treatment by a high-pressure pump (4) does work, the pressure of the high-pressure seawater subjected to the work is reduced and flows out from a low-pressure outlet (11) of the B, and the pressure of the low-pressure seawater is increased and flows out from a high-pressure outlet (13) of the B;

4) the seawater flowing out of the low-pressure outlet (11) and the high-pressure outlet (13) of the water treatment system B is converged and then flows into the membrane component (5) for permeation separation, a part of seawater permeates through the reverse osmosis membrane to become desalted water and flows out through a pipeline, and the rest high-pressure strong brine which does not permeate through the reverse osmosis membrane flows into the pressure energy exchanger (2) of the water treatment system A from the high-pressure inlet (6) of the water treatment system A to complete circulation until the seawater to be treated is treated or the system stops running.

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