A method of flushing for a seawater desalination system

Abstract

The application discloses a flushing method for a seawater desalination system and belongs to the technical field of seawater desalination. The flushing method for the seawater desalination system provided by the application can be used for flushing alone by using seawater, can be used for flushing together with fresh water, and can select appropriate flushing methods according to different modes of seawater purification systems. The flushing method provided by the application is gentle to inlet and outlet water pipes and RO units in a starting impact process, has a small impact on a power grid, reduces the use of fresh water, guarantees the smoothness of a pipeline system and a membrane system of the seawater desalination system, and prolongs the service life of the seawater desalination system.

Description

Technical Field

[0001] This invention belongs to the field of seawater desalination technology, specifically relating to a flushing method for a seawater desalination system. Background Technology

[0002] During the operation of seawater desalination equipment, the concentrated water pipelines, the energy recovery device, and the downstream section of the high-pressure pump are all filled with concentrated seawater. This high-salinity seawater inevitably causes corrosion to the pipeline system inside the equipment. To minimize this impact, the seawater desalination equipment must be flushed before shutdown. Existing flushing methods for seawater desalination systems involve using a dedicated freshwater flushing device or chemical flushing device. For example, Chinese invention patent application number 201710494753.6 discloses a low-pressure flushing and chemical cleaning device and its application for reverse osmosis seawater desalination. By setting up these devices, the reverse osmosis seawater desalination system does not need to be repeatedly started and stopped during these processes, thus increasing its service life, reducing equipment costs, and simplifying system control. However, these flushing methods require dedicated flushing devices and suffer from excessive freshwater consumption. Summary of the Invention

[0003] In order to overcome the shortcomings of the prior art, the technical problem to be solved by the present invention is to provide a flushing method for a seawater desalination system that does not require a separate flushing device.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a flushing method for a seawater desalination system, wherein the seawater desalination system includes: an inlet pipe, an outlet pipe, a seawater inlet valve, a raw water pump, an energy recovery device, a high-pressure pump, an RO unit, and a product water tank;

[0005] The seawater inlet valve is connected to the raw water pump through an inlet pipe. The raw water pump is connected to the high-pressure pump and the energy recovery device through inlet pipes. The high-pressure pump and the energy recovery device are connected to the RO unit through an inlet pipe. The RO unit is connected to the product water tank through an inlet pipe.

[0006] The energy recovery device is connected to the RO unit via an outlet pipe;

[0007] A freshwater inlet pipe is provided on the inlet pipe between the seawater inlet valve and the raw water pump, and a freshwater inlet valve is provided on the freshwater inlet pipe;

[0008] The rinsing method includes the following steps:

[0009] Step S1: Open the seawater inlet valve. After the seawater inlet valve is fully opened, the raw water pump starts on a ramp. After the raw water pump reaches the rated speed, the energy recovery device is started. The speed of the energy recovery device is the flushing speed.

[0010] Step S2: Increase the rotation speed of the energy recovery device to the water production rate, and then start the high-pressure pump on a ramp.

[0011] Step S3: After the production tank is full, the high-pressure pump begins to decelerate. After the high-pressure pump decelerates to 0, the energy recovery device begins to decelerate. After the energy recovery device decelerates to 0, the raw water pump begins to decelerate. After the raw water pump decelerates to 0, the seawater inlet valve is closed.

[0012] The rinsing speed is 600-750 rpm, and the water production speed is 1450 rpm.

[0013] The beneficial effects of the present invention are as follows: The flushing method for seawater desalination systems provided by the present invention eliminates the need for a separate flushing device, allowing for flushing using seawater alone. The flushing process is gentle on the inlet and outlet pipes and the RO unit (reverse osmosis membrane system), minimizes the impact on the power grid, reduces the use of fresh water, ensures the smooth flow of the piping and membrane systems of the seawater desalination system, and extends the service life of the seawater desalination system. Attached Figure Description

[0014] Figure 1 The diagram shows a flowchart of a flushing method for a seawater desalination system according to a specific embodiment of the present invention.

[0015] Figure 2 The diagram shows a flowchart of step S3 of a flushing method for a seawater desalination system according to a specific embodiment of the present invention.

[0016] Figure 3 The diagram shows steps S3 and S4 of the flushing method for a seawater desalination system according to a specific embodiment of the present invention.

[0017] Figure 4 The diagram shows steps S3 and S4 of the flushing method for a seawater desalination system according to a specific embodiment of the present invention.

[0018] Figure 5 The above is a schematic diagram of the structure of a seawater desalination system according to a specific embodiment of the present invention;

[0019] Labeling Explanation: 1. Inlet pipe; 2. Outlet pipe; 3. Seawater inlet valve; 4. Raw water pump; 5. Energy recovery device; 6. High-pressure pump; 7. RO unit; 8. Product water tank; 9. Freshwater inlet pipe; 10. Freshwater inlet valve; 11. Frequency converter. Detailed Implementation

[0020] To explain in detail the technical content, objectives, and effects of the present invention, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0021] The most crucial concept of this invention lies in effectively flushing the seawater desalination system by changing its operating mode.

[0022] Please refer to Figures 1 to 5 As shown, the present invention provides a flushing method for a seawater desalination system, the seawater desalination system comprising: an inlet pipe 1, an outlet pipe 2, a seawater inlet valve 3, a raw water pump 4, an energy recovery device 5, a high-pressure pump 6, an RO unit 7, and a product water tank 8.

[0023] The seawater inlet valve 3 is connected to the raw water pump 4 through the inlet pipe 1. The raw water pump 4 is connected to the high-pressure pump 6 and the energy recovery device 5 through the inlet pipe 1. The high-pressure pump 6 and the energy recovery device 5 are connected to the RO unit 7 through the inlet pipe 1. The RO unit 7 is connected to the product water tank 8 through the inlet pipe 1.

[0024] The energy recovery device 5 and the RO unit 7 are connected through the water outlet pipe 2;

[0025] A freshwater inlet pipe 9 is provided between the seawater inlet valve 3 and the raw water pump 4, and a freshwater inlet valve 10 is provided on the freshwater inlet pipe 9;

[0026] Among them, the raw water pump 4, the high-pressure pump 6 and the energy recovery device 5 are all driven by a frequency converter 11;

[0027] The rinsing method includes the following steps:

[0028] Step S1: Open the seawater inlet valve 3. After the seawater inlet valve 3 is fully opened, the raw water pump 4 starts on a ramp. After the raw water pump 4 reaches the rated speed, the energy recovery device 5 is started. The speed of the energy recovery device 5 is the rinsing speed.

[0029] Step S2: Increase the rotation speed of the energy recovery device 5 to the water production rate, and then start the high-pressure pump 6 on a ramp.

[0030] Step S3: After the production tank 8 is full, the high-pressure pump 6 begins to decelerate. After the high-pressure pump 6 decelerates to 0, the energy recovery device 5 begins to decelerate. After the energy recovery device 5 decelerates to 0, the raw water pump 4 begins to decelerate. After the raw water pump 4 decelerates to 0, the seawater inlet valve 3 is closed.

[0031] The rinsing speed is 600-750 rpm, and the water production speed is 1450 rpm.

[0032] The rated speed is 1450 rpm.

[0033] As can be seen from the above description, the beneficial effects of the present invention are as follows: The flushing method for seawater desalination systems provided by the present invention eliminates the need for a separate flushing device, allowing for flushing using seawater alone. The start-up impact process is gentle on the pipelines and membrane systems, with minimal impact on the power grid, reducing the use of fresh water, ensuring the smooth flow of the pipeline and membrane systems of the seawater desalination system, and extending the service life of the seawater desalination system.

[0034] Further, step S3 is as follows: after the production tank 8 is full, the high-pressure pump 6 begins to decelerate. After the high-pressure pump 6 decelerates to 0, the energy recovery device 5 begins to decelerate. At the same time, the fresh water inlet valve 10 is opened. After the fresh water inlet valve 10 is fully opened, the seawater inlet valve 3 is closed. When the energy recovery device 5 decelerates to the rinsing speed and the seawater inlet valve 3 is fully closed, the high-pressure pump 6 is jogged. After rinsing for 1-2 minutes, the energy recovery device 5 begins to decelerate. After the energy recovery device 5 decelerates to 0, the raw water pump 4 begins to decelerate. After the raw water pump 4 decelerates to 0, the fresh water inlet valve 10 is closed.

[0035] As can be seen from the above description, the above method can use fresh water to flush the seawater desalination system, and the method is applicable to situations where the system is manually started and stopped or the downtime of the seawater desalination system is known. Therefore, fresh water flushing can be selectively performed to achieve the purpose of saving water resources.

[0036] Furthermore, step S3 is as follows: after the production tank 8 is full, the high-pressure pump 6 begins to decelerate. After the high-pressure pump 6 decelerates to 0, the energy recovery device 5 begins to decelerate. The energy recovery device 5 decelerates to the flushing speed.

[0037] It also includes step S4: opening the freshwater inlet valve 10; after the freshwater inlet valve 10 is fully opened, closing the seawater inlet valve 3; after the seawater inlet valve 3 is fully closed, jogging the high-pressure pump 6; after rinsing for 1-2 minutes, the energy recovery device 5 begins to decelerate; after the energy recovery device 5 decelerates to 0, the raw water pump 4 begins to decelerate; after the raw water pump 4 decelerates to 0, closing the freshwater inlet valve 10.

[0038] As can be seen from the above description, by setting step S4, and during the process of switching from seawater flushing to freshwater flushing, energy recovery does not slow down, a strengthened flushing mode that uses both seawater and freshwater is provided. First, seawater is used for flushing for a longer period of time, and the shear force of the high-speed seawater flow washes away the scale and impurities on the membrane surface. Then, freshwater is used for flushing to replace the seawater in the system, so as to achieve the purpose of long-term shutdown.

[0039] Furthermore, step S4 is also included: after standby for more than 24 hours, the fresh water inlet valve 10 is opened. After the fresh water inlet valve 10 is fully opened, the raw water pump 4 starts at an incline. After the raw water pump 4 reaches the rated speed, the energy recovery device 5 is started. The speed of the energy recovery device 5 is the rinsing speed. The high-pressure pump 6 is jogged to rinse for 1-2 minutes. After rinsing, the energy recovery device 5 begins to decelerate. After the energy recovery device 5 decelerates to 0, the raw water pump 4 begins to decelerate. After the raw water pump 4 decelerates to 0, the fresh water inlet valve 10 is closed.

[0040] As can be seen from the above description, the above method is applicable to the full flushing of the water production tank in fully automatic mode, and the time it takes for the water production tank to be full is unknown. This method ensures that seawater is used for flushing during short-term shutdowns and fresh water is used for flushing during long-term shutdowns, thus reasonably saving fresh water resources.

[0041] Furthermore, the jogging time of the high-pressure pump 6 is 5 seconds.

[0042] Please refer to Figure 1 and Figure 5 Embodiment 1 of the present invention is as follows:

[0043] A flushing method for a seawater desalination system, the seawater desalination system comprising: an inlet pipe 1, an outlet pipe 2, a seawater inlet valve 3, a raw water pump 4, an energy recovery device 5, a high-pressure pump 6, an RO unit 7, and a product water tank 8;

[0044] The seawater inlet valve 3 is connected to the raw water pump 4 through the inlet pipe 1. The raw water pump 4 is connected to the high-pressure pump 6 and the energy recovery device 5 through the inlet pipe 1. The high-pressure pump 6 and the energy recovery device 5 are connected to the RO unit 7 through the inlet pipe 1. The RO unit 7 is connected to the product water tank 8 through the inlet pipe 1.

[0045] The energy recovery device 5 and the RO unit 7 are connected through the water outlet pipe 2;

[0046] A freshwater inlet pipe 9 is provided between the seawater inlet valve 3 and the raw water pump 4, and a freshwater inlet valve 10 is provided on the freshwater inlet pipe 9;

[0047] Among them, the raw water pump 4, the high-pressure pump 6 and the energy recovery device 5 are all driven by a frequency converter 11;

[0048] The rinsing method includes the following steps:

[0049] Step S1: Open the seawater inlet valve 3. After the seawater inlet valve 3 is fully opened, the frequency converter 11 drives the raw water pump 4 to start on the ramp. After the raw water pump 4 reaches the rated speed, the energy recovery device 5 is started. The speed of the energy recovery device 5 is the rinsing speed.

[0050] Step S2: Increase the rotation speed of the energy recovery device 5 to the water production rate, and then start the high-pressure pump 6 on a ramp.

[0051] Step S3: After the production tank 8 is full, the high-pressure pump 6 begins to decelerate. After the high-pressure pump 6 decelerates to 0, the energy recovery device 5 begins to decelerate. After the energy recovery device 5 decelerates to 0, the raw water pump 4 begins to decelerate. After the raw water pump 4 decelerates to 0, the seawater inlet valve 3 is closed.

[0052] The rinsing speed is 600-750 rpm, and the water production speed is 1450 rpm.

[0053] Please refer to Figure 1 , Figure 2 and Figure 5 Embodiment two of the present invention is as follows:

[0054] A flushing method for a seawater desalination system, the seawater desalination system comprising: an inlet pipe 1, an outlet pipe 2, a seawater inlet valve 3, a raw water pump 4, an energy recovery device 5, a high-pressure pump 6, an RO unit 7, and a product water tank 8;

[0055] The seawater inlet valve 3 is connected to the raw water pump 4 through the inlet pipe 1. The raw water pump 4 is connected to the high-pressure pump 6 and the energy recovery device 5 through the inlet pipe 1. The high-pressure pump 6 and the energy recovery device 5 are connected to the RO unit 7 through the inlet pipe 1. The RO unit 7 is connected to the product water tank 8 through the inlet pipe 1.

[0056] The energy recovery device 5 and the RO unit 7 are connected through the water outlet pipe 2;

[0057] A freshwater inlet pipe 9 is provided between the seawater inlet valve 3 and the raw water pump 4, and a freshwater inlet valve 10 is provided on the freshwater inlet pipe 9;

[0058] Among them, the raw water pump 4, the high-pressure pump 6 and the energy recovery device 5 are all driven by a frequency converter 11;

[0059] The rinsing method includes the following steps:

[0060] Step S1: Open the seawater inlet valve 3. After the seawater inlet valve 3 is fully opened, the frequency converter 11 drives the raw water pump 4 to start on the ramp. After the raw water pump 4 reaches the rated speed, the energy recovery device 5 is started. The speed of the energy recovery device 5 is the rinsing speed.

[0061] Step S2: Increase the rotation speed of the energy recovery device 5 to the water production rate, and then start the high-pressure pump 6 on a ramp.

[0062] Step S3 is as follows: After the production tank 8 is full, the high-pressure pump 6 begins to decelerate. After the high-pressure pump 6 decelerates to 0, the energy recovery device 5 begins to decelerate. At the same time, the fresh water inlet valve 10 is opened. After the fresh water inlet valve 10 is fully opened, the seawater inlet valve 3 is closed. When the energy recovery device 5 decelerates to the flushing speed and the seawater inlet valve 3 is fully closed, the high-pressure pump 6 is jogged for 5 seconds. After flushing for 1-2 minutes, the energy recovery device 5 begins to decelerate. After the energy recovery device 5 decelerates to 0, the raw water pump 4 begins to decelerate. After the raw water pump 4 decelerates to 0, the fresh water inlet valve 10 is closed.

[0063] The rinsing speed is 600-750 rpm, and the water production speed is 1450 rpm.

[0064] The rated speed is 1450 rpm.

[0065] Please refer to Figure 1 , Figure 3 and Figure 5 Embodiment 3 of the present invention is as follows:

[0066] A flushing method for a seawater desalination system, the seawater desalination system comprising: an inlet pipe 1, an outlet pipe 2, a seawater inlet valve 3, a raw water pump 4, an energy recovery device 5, a high-pressure pump 6, an RO unit 7, and a product water tank 8;

[0067] The seawater inlet valve 3 is connected to the raw water pump 4 through the inlet pipe 1. The raw water pump 4 is connected to the high-pressure pump 6 and the energy recovery device 5 through the inlet pipe 1. The high-pressure pump 6 and the energy recovery device 5 are connected to the RO unit 7 through the inlet pipe 1. The RO unit 7 is connected to the product water tank 8 through the inlet pipe 1.

[0068] The energy recovery device 5 and the RO unit 7 are connected through the water outlet pipe 2;

[0069] A freshwater inlet pipe 9 is provided between the seawater inlet valve 3 and the raw water pump 4, and a freshwater inlet valve 10 is provided on the freshwater inlet pipe 9;

[0070] Among them, the raw water pump 4, the high-pressure pump 6 and the energy recovery device 5 are all driven by a frequency converter 11;

[0071] The rinsing method includes the following steps:

[0072] Step S1: Open the seawater inlet valve 3. After the seawater inlet valve 3 is fully opened, the frequency converter 11 drives the raw water pump 4 to start on the ramp. After the raw water pump 4 reaches the rated speed, the energy recovery device 5 is started. The speed of the energy recovery device 5 is the rinsing speed.

[0073] Step S2: Increase the rotation speed of the energy recovery device 5 to the water production rate, and then start the high-pressure pump 6 on a ramp.

[0074] Step S3: After the production tank 8 is full, the high-pressure pump 6 begins to decelerate. After the high-pressure pump 6 decelerates to 0, the energy recovery device 5 begins to decelerate. The energy recovery device decelerates to the flushing speed.

[0075] Step S4: Open the freshwater inlet valve 10. After the freshwater inlet valve 13 is fully opened, close the seawater inlet valve 3. After the seawater inlet valve 3 is fully closed, jog the high-pressure pump 6 for 5 seconds. After rinsing for 1-2 minutes, the energy recovery device 5 starts to decelerate. After the energy recovery device 5 decelerates to 0, continue rinsing for 1-2 minutes. After rinsing is completed, the raw water pump 4 starts to decelerate. After the raw water pump 4 decelerates to 0, close the freshwater inlet valve 10.

[0076] The rinsing speed is 600-750 rpm, and the water production speed is 1450 rpm.

[0077] The rated speed is 1450 rpm.

[0078] Please refer to Figure 1 , Figure 4 and Figure 5 Embodiment four of the present invention is as follows:

[0079] A flushing method for a seawater desalination system, the seawater desalination system comprising: an inlet pipe 1, an outlet pipe 2, a seawater inlet valve 3, a raw water pump 4, an energy recovery device 5, a high-pressure pump 6, an RO unit 7, and a product water tank 8;

[0080] The seawater inlet valve 3 is connected to the raw water pump 4 through the inlet pipe 1. The raw water pump 4 is connected to the high-pressure pump 6 and the energy recovery device 5 through the inlet pipe 1. The high-pressure pump 6 and the energy recovery device 5 are connected to the RO unit 7 through the inlet pipe 1. The RO unit 7 is connected to the product water tank 8 through the inlet pipe 1.

[0081] The energy recovery device 5 and the RO unit 7 are connected through the water outlet pipe 2;

[0082] A freshwater inlet pipe 9 is provided between the seawater inlet valve 3 and the raw water pump 4, and a freshwater inlet valve 10 is provided on the freshwater inlet pipe 9;

[0083] The rinsing method includes the following steps:

[0084] Step S1: Open the seawater inlet valve 3. After the seawater inlet valve 3 is fully opened, the frequency converter 11 drives the raw water pump 4 to start on the ramp. After the raw water pump 4 reaches the rated speed, the energy recovery device 5 is started. The speed of the energy recovery device 5 is the rinsing speed.

[0085] Step S2: Increase the rotation speed of the energy recovery device 5 to the water production rate, and then start the high-pressure pump 6 on a ramp.

[0086] Step S3: After the production tank 8 is full, the high-pressure pump 6 begins to decelerate. After the high-pressure pump 6 decelerates to 0, the energy recovery device 5 begins to decelerate. After the energy recovery device 5 decelerates to 0, the raw water pump 4 begins to decelerate. After the raw water pump 4 decelerates to 0, the seawater inlet valve 3 is closed.

[0087] Step S4: After standby for more than 24 hours, open the fresh water inlet valve 10. After the fresh water inlet valve 10 is fully opened, the frequency converter 11 drives the raw water pump 4 to start on a ramp. After the raw water pump 4 reaches the rated speed, the energy recovery device 5 is started. The speed of the energy recovery device 5 is the flushing speed. The high-pressure pump 6 is jogged for 5 seconds, and the flushing is carried out for 1-2 minutes. After the flushing is completed, the energy recovery device 5 begins to decelerate. After the energy recovery device 5 decelerates to 0, it continues to flush for 1-2 minutes. After the flushing is completed, the raw water pump 4 begins to decelerate. After the raw water pump 4 decelerates to 0, the fresh water inlet valve 10 is closed.

[0088] The rinsing speed is 600-750 rpm, and the water production speed is 1450 rpm.

[0089] The rated speed is 1450 rpm.

[0090] In summary, the flushing method for seawater desalination systems provided by this invention eliminates the need for a separate flushing device. It can be used for flushing with seawater alone or in combination with fresh water. Appropriate flushing methods can be selected for different modes of seawater purification systems. The flushing method provided by this invention has a gentle start-up impact on the inlet and outlet pipes and RO unit, minimizes the impact on the power grid, reduces the use of fresh water, ensures the smooth flow of the piping and membrane systems of the seawater desalination system, and extends the service life of the seawater desalination system.

[0091] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent modifications made based on the content of the present invention specification and drawings, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A flushing method for a seawater desalination system, characterized in that, The seawater desalination system includes: an inlet pipe, an outlet pipe, a seawater inlet valve, a raw water pump, an energy recovery device, a high-pressure pump, an RO unit, and a product water tank; The seawater inlet valve is connected to the raw water pump through an inlet pipe. The raw water pump is connected to the high-pressure pump and the energy recovery device through inlet pipes. The high-pressure pump and the energy recovery device are connected to the RO unit through inlet pipes. The high-pressure pump and the energy recovery device are connected in parallel. The RO unit is connected to the product water tank through an inlet pipe. The energy recovery device is connected to the RO unit via an outlet pipe; A freshwater inlet pipe is provided between the seawater inlet valve and the raw water pump, and a freshwater inlet valve is provided on the freshwater inlet pipe; The rinsing method includes the following steps: Step S1: Open the seawater inlet valve. After the seawater inlet valve is fully opened, the raw water pump starts on a ramp. After the raw water pump reaches the rated speed, the energy recovery device is started. The speed of the energy recovery device is the flushing speed. Step S2: Increase the rotation speed of the energy recovery device to the water production rate, and then start the high-pressure pump on a ramp. Step S3: After the production tank is full, the high-pressure pump begins to decelerate. After the high-pressure pump decelerates to 0, the energy recovery device begins to decelerate. After the energy recovery device decelerates to 0, the raw water pump begins to decelerate. After the raw water pump decelerates to 0, the seawater inlet valve is closed. Step S4: After standby for more than 24 hours, open the freshwater inlet valve. Once the freshwater inlet valve is fully open, the raw water pump will start at a ramp. After the raw water pump reaches its rated speed, the energy recovery device will start. The speed of the energy recovery device is the flushing speed. Jog the high-pressure pump and flush for 1-2 minutes. After flushing, the energy recovery device will start to decelerate. After the energy recovery device decelerates to 0, the raw water pump will start to decelerate. After the raw water pump decelerates to 0, close the freshwater inlet valve. The rinsing speed is 600-750 rpm, and the water production speed is 1450 rpm.

2. The flushing method for a seawater desalination system according to claim 1, characterized in that, The jogging time of the high-pressure pump is 5 seconds.

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