Super-effect pulsation concentration device suitable for reverse osmosis or nanofiltration membrane filtration system

Abstract

The invention discloses a super-effect pulsation concentration device suitable for a reverse osmosis or nanofiltration membrane filtration system. The super-effect pulsation concentration device comprises four membrane units, namely a first-stage first-section concentration unit, a first-stage second-section concentration unit, a first-stage third-section concentration unit and a second-stage high-pressure reverse osmosis membrane unit, a water tank and an electric control system. Each membrane unit comprises a water feeding pump, a security filter, a high-pressure pump, a reverse osmosis membrane or nanofiltration membrane assembly, a circulating pump, an energy storage tank assembly, a pulse generation unit, a flow sensor and a pressure sensor. And the working medium is high-concentration saline water or solution. The device is applied to the fields of high-concentration salt wastewater, zero emission of power plants, chemical engineering, wet smelting and the like which need to concentrate and separate liquid working media. The pressure energy recovery of the high-pressure side of the membrane filtration system is realized through the combination technology of the energy storage tank assembly and the pulse generation unit; by adopting a periodic pulsating traveling wave filtering mode, sediments on the membrane surface are reduced, the concentration efficiency of the system is improved, and the operation cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of application of concentration and pressure energy recovery of high-pressure fluid working medium, and in particular to a super-efficient pulsating concentration device suitable for reverse osmosis or nanofiltration membrane filtration systems. Background Art

[0002] A large amount of wastewater is generated during the production process of industrial enterprises. China's coal chemical projects will generate about 475 million tons of wastewater in 2020, including difficult-to-treat saline wastewater. High-salt wastewater brings serious pollution and harms the environment and enterprise production. The problem of concentrated brine has become a bottleneck restricting the development of the industry. The treatment process commonly used for high-salt wastewater is: wastewater pretreatment, ultrafiltration, reverse osmosis, nanofiltration to MVR evaporation and crystallization. MVR evaporation and crystallization has the disadvantages of high energy consumption and high cost. Membrane water treatment technology with reverse osmosis membrane or nanofiltration membrane as the core is an important high-salt wastewater treatment technology. The use of membrane concentration technology can greatly reduce the working medium to be treated entering the MVR evaporation and crystallization process, but the existing technology has problems such as high system operating pressure, high energy consumption, and low concentration of the working medium. In the future chemical and wet metallurgical material concentration projects, the application prospects of membrane concentration technology are broad. Membrane process technology plays an important role in the above-mentioned fields. The present invention can overcome the problems of high operating pressure, high energy consumption, low concentration degree and low energy recovery efficiency of the existing membrane concentration system.

[0003] Existing concentration technology suitable for reverse osmosis or nanofiltration membrane filtration system system process such as Figure 8 As shown. The existing membrane system uses graded treatment to improve the water quality of the membrane permeate effluent and reduce the salt content of the produced water; it uses segmented treatment to improve the recovery rate of the membrane system and increase the concentration of the working medium on the concentrated water side. The multi-stage and multi-segment membrane treatment form is a classic process form of reverse osmosis or nanofiltration membrane method. The system configuration criteria of the existing membrane concentration device are consistent with the above, but in practice, the specific combination of several stages and segments needs to be determined according to the specific conditions of the working medium and the concentration requirements. Existing membrane concentration devices rarely have energy recovery functions, and the specific operating processes of membrane concentration and filtration systems are also different.

[0004] Existing energy recovery devices are mainly used in large-scale seawater desalination, including centrifugal turbine energy recovery devices, isobaric or positive displacement energy recovery devices, energy cycle or triple cluster energy recovery devices. Centrifugal turbine energy recovery device system configuration is as follows Fig. 9As shown in the figure, a hydraulic turbine is used to convert pressure energy into mechanical energy, and then the mechanical energy is converted into seawater pressure energy to achieve energy recovery. There is a certain loss of pressure energy in both conversion processes, so the total energy recovery efficiency is below 90%. The low-pressure seawater enters the membrane assembly after being pressurized by the high-pressure pump. The high-pressure brine discharged by the membrane assembly is converted into rotational mechanical energy in the turbine. The turbine is coaxial with the high-pressure pump motor and drives the high-pressure pump to operate together. The energy recovery device achieves energy saving and consumption reduction by inputting shaft work to the high-pressure pump motor. Compared with the single high-pressure pump pressurization method, the flow rate and lifting pressure of the fluid output remain unchanged. Another implementation scheme of the centrifugal turbine energy recovery device is to directly connect the hydraulic turbine to the high-pressure pump coaxially, and the turbine directly drives the high-pressure pump to operate. Its essence is a hydraulically driven pump or turbocharger. The high-pressure brine of the centrifugal turbine energy recovery device undergoes a two-step conversion process of "pressure energy-mechanical energy-pressure energy". Its energy conversion efficiency is generally around 50-70% and it needs to be coaxially connected to the high-pressure pump to achieve energy recovery. Therefore, the device has the disadvantages of low energy conversion efficiency, large equipment size, and high requirements for device installation and positioning. The isobaric energy recovery device is also called a positive displacement energy recovery device. Its system configuration is as follows: Fig.10 As shown, it is the most widely used in existing energy recovery devices. Isobaric energy recovery devices can be divided into two categories in principle: valve-controlled type and rotor type. The low-pressure working medium is divided into two paths by the low-pressure pump and transported to the high-pressure pump and the isobaric energy recovery component respectively. One path of low-pressure working medium is directly added to high pressure by the high-pressure pump and then transported to the reverse osmosis membrane component. The other path of low-pressure seawater first enters the isobaric energy recovery component and exchanges pressure with the high-pressure working medium discharged by the membrane component, and then enters the membrane component after being boosted to high pressure by the booster pump. The system's water production energy consumption is greatly reduced. The valve-controlled energy recovery component includes three parts: an active switching valve, a pressure exchange chamber, and a check valve group. The active switching valve and the check valve group cooperate with each other to realize the orderly switching of the pressurization and pressure relief processes, and the pressure energy exchange is carried out in the pressure exchange chamber. The most important feature of the rotor-type energy recovery component is that the high-speed rotation of the rotor realizes the rapid switching of the pressurization and pressure relief processes, and the pressure exchange is realized in multiple axial channels set on the rotor. The flow rate of the high-pressure pump of the isobaric energy recovery device is basically consistent with the processing capacity of the membrane assembly, and the energy conversion efficiency is slightly higher than that of the centrifugal turbine energy recovery device. However, fine particles can easily cause the rotary valve core to get stuck or the sealing surface to be scratched. There are also problems such as low energy conversion efficiency, internal leakage of the device, and salinity mixing between the working medium stock solution and the concentrated fluid on the high-pressure side of the membrane assembly. This type of energy recovery device does not have products for small flow or smaller-scale systems. Energy recovery in large-scale systems requires multiple such energy recovery devices to be connected in parallel. The system configuration of an energy cycle or triple cluster energy recovery device is as follows: Fig.11As shown, it is basically similar to the isobaric energy recovery device. The flow rate of its high-pressure pump is basically consistent with the processing capacity of the membrane component. The high-pressure working medium of this type of energy recovery device can circulate and cross-flow, and has strong adaptability to the processing capacity of the membrane system. However, the energy circulation system has a large number of valve configurations and complex pipelines. The fluid is prone to produce sediments and contaminate the membrane surface under high concentration conditions, and it is easy to produce concentration polarization, resulting in uneven flux when the membrane element is working, reducing the energy recovery efficiency and causing the separation and concentration performance of the membrane filtration system to decrease. Summary of the invention

[0005] In order to overcome the above defects in the existing concentration devices, the present invention discloses a super-efficient pulsating concentration device suitable for reverse osmosis or nanofiltration membrane filtration system. Compared with the existing membrane concentration device, the hardware configuration and system operation mode are different, and a pulse generating unit and an energy storage tank assembly are used; Figure 3 As shown, periodic pulsating traveling wave filtration is adopted. The present invention realizes the concentration of the working medium and the recovery of the pressure energy on the concentrated water side of the membrane system; the working medium is high-concentration salt water or solution.

[0006] In order to achieve the above-mentioned purpose, the technical scheme of the present invention is: a super-efficient pulsating concentrator suitable for a reverse osmosis or nanofiltration membrane filtration system, which is composed of four membrane filtration units, namely a first-stage first-section concentrator unit, a first-stage second-section concentrator unit, a first-stage third-section concentrator unit and a second-stage high-pressure reverse osmosis membrane unit, a water tank and an electronic control system. The concentrate sides of the first-stage first-section concentrator unit, the first-stage second-section concentrator unit, and the first-stage third-section concentrator unit are connected in series by water tanks, pipelines, and valves; the produced water outlet of the first-stage first-section concentrator unit and the concentrated water inlet of the second-stage high-pressure reverse osmosis membrane unit are connected in series by pipelines, valves, and water pumps; the concentrated water outlet of the second-stage high-pressure reverse osmosis membrane unit and the produced water outlet of the first-stage second-section concentrator unit are refluxed to the working medium inlet pipeline of the first-stage first-section concentrator unit by pipeline valves; the produced water outlet of the first-stage third-section concentrator unit is connected to the water tank in the inlet pipeline of the first-stage second-section concentrator unit by pipeline valves; the membrane permeate of the second-stage high-pressure reverse osmosis membrane unit is connected to the produced water outlet pipeline; the high-pressure circulation pipeline on the concentrate side of the first-stage third-section concentrator unit is connected to the concentrated medium outlet.

[0007] Each monomer membrane filtration unit of the concentration device includes a water supply pump, a safety filter, a high-pressure pump, an energy storage tank assembly, a circulation pump, a reverse osmosis membrane or a nanofiltration membrane assembly, a pressure safety valve, an exhaust valve, a pulse generating unit, a flow sensor, a pressure sensor, and an electronic control system; the water supply pump and the safety filter are connected in series with a pipeline; the outlet of the safety filter is connected to the high-pressure pump by a branch pipe; the outlet pipeline of the high-pressure concentrated water side of the reverse osmosis membrane or nanofiltration membrane assembly is connected to the inlet pipeline of the circulation pump; the outlet pipeline of the high-pressure pump is connected to the outlet pipeline of the circulation pump by a three-way joint; the device also includes an energy storage tank assembly, a pressure safety valve, and a pulse generating unit component; the outlet of the safety filter is connected to the energy storage tank by a branch pipe The tank assembly and the pulse generating unit inlet are connected; the circulating pump outlet pipeline is connected to the inlet pipeline of the energy storage tank assembly, and the outlet pipeline of the energy storage tank assembly is connected to the high-pressure concentrated water side inlet of the reverse osmosis membrane or nanofiltration membrane assembly; a circulating pipeline is formed between the concentrated water side of the reverse osmosis membrane or nanofiltration membrane assembly, the circulating pump and the energy storage tank assembly to realize the filtration and concentration functions of the membrane system; the pulse generating unit outlet pipeline is connected to the energy storage tank assembly outlet main pipe with a three-way joint; the high-pressure concentrated water inlet side pipeline of the reverse osmosis membrane or nanofiltration membrane assembly is connected to the pressure safety valve; valves are provided at the inlets and outlets of the water supply pump, safety filter, high-pressure pump, energy storage tank assembly, circulating pump, reverse osmosis membrane or nanofiltration membrane assembly and pulse generating unit.

[0008] The circulating pump in the single membrane filtration unit pressurizes the high-pressure working medium at the outlet of the concentrated water side of the reverse osmosis membrane or nanofiltration membrane assembly and mixes it with the high-pressure working medium from the high-pressure pump. The mixed working medium flows through the energy storage tank assembly and then flows through the concentrated water side of the reverse osmosis membrane or nanofiltration membrane assembly. Part of the working medium permeates through the membrane surface to become permeate, and the remaining high-pressure and high-concentration working medium flows out of the membrane assembly and enters the inlet of the circulating pump. The working medium forms a high-pressure, large-flow, circulating cross-flow operation mode. The flow rate of the circulating pump is about 1 to 5 times that of the high-pressure pump.

[0009] Before the monomer membrane filter unit is put into operation, it is first filled with liquid by the water supply pump. After the device is completely filled with the working medium, the high-pressure pump and the circulation pump are started, and the device is put into operation. The initial pressure of the operation is set by the control system, and the specific set value is reached by changing the operating frequency of the water supply pump motor. As the working medium operates in high pressure, large flow, and circulating cross-flow mode, the concentration of the working medium becomes higher and higher, and the osmotic pressure gradually rises. The electronic control system increases the operating frequency of the high-pressure pump unit, the output power of the high-pressure pump increases, the operating pressure of the working medium rises, and the output of the membrane filtration system remains unchanged. When the operating pressure of the working medium rises to the maximum set value, the device completes a working cycle. The maximum set value is determined according to the specific conditions of the working medium, generally 5.0~8.0MPa. The energy storage tank assembly is divided into two parts: the energy storage working group and the energy storage standby group, which alternately participate in the cyclic operation of the energy recovery device. When the operating pressure of the device reaches the maximum set value, the energy storage working group participating in the circulating operation in the energy storage tank assembly exits operation and switches to the energy storage standby group; the energy storage standby group in the energy storage tank assembly participates in the circulating operation and switches to the energy storage working group. After the energy storage tank that has been out of operation is drained and replenished, it becomes an energy storage standby group waiting for the next cycle to be put into operation. The cycle period is determined by the effective residence time of the working medium in the energy storage tank assembly or the effective energy storage volume and the maximum working pressure factor of the device design. The unit operates in a high-pressure, large-flow, and cyclic cross-flow cycle mode.

[0010] In each working cycle of the single membrane filtration unit, the pulse generating unit receives the replenishment fluid from the security filter, and quickly injects the replenishment fluid into the connecting pipe at the inlet of the concentrated water side of the reverse osmosis membrane or nanofiltration membrane assembly under hydraulic or electric drive. The inlet pipe is also the outlet main pipe of the energy storage tank assembly; the output of the pulse generating unit changes the operating pressure of the reverse osmosis membrane or nanofiltration membrane assembly, and the concentrated water pressure pulsates with high pressure; the system realizes periodic pulsating traveling wave filtration. The number, time and pulse pressure of high-pressure pulses are preset by the system, and the electronic control system also compares the detection value of the pressure sensor with the set value, and excites the pulse after the preset conditions are met.

[0011] This device realizes the concentration and energy recovery of the working medium according to periodic pulsating traveling wave filtration. The high-pressure pulse of the working medium increases the turbulence degree of the medium on the concentrated water side of the membrane, prevents impurities in the highly concentrated brine from being deposited on the membrane surface, reduces concentration polarization, and improves the flux balance of membrane filtration, thereby improving the operating efficiency of the membrane concentration system and the energy recovery efficiency of the high-pressure side pressure energy of the device. The system configuration of the present invention is simple and compact, and can realize energy recovery for membrane concentration systems with different processing capacities, with strong adaptability. The present device can reduce the high energy consumption problem in the membrane process and improve the concentration efficiency of the system. The concentration of the working medium after concentration is close to its saturation concentration at the temperature. The present invention promotes industrial upgrading and realizes energy-saving, low-carbon and sustainable development. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a two-stage three-stage system flow chart of the super-efficient pulsating concentrator applicable to the reverse osmosis or nanofiltration membrane filtration system of the present invention; Figure 2 This is a system configuration diagram of a single membrane filtration unit of a super-efficient pulsating concentration device applicable to a reverse osmosis or nanofiltration membrane filtration system of the present invention; Figure 3 It is a schematic diagram of the operating pressure of a single membrane filtration unit of a super-efficient pulsating concentration device applicable to a reverse osmosis or nanofiltration membrane filtration system of the present invention; Figure 4 This is a structural diagram of an energy storage tank of a super-efficient pulsating concentration device applicable to a reverse osmosis or nanofiltration membrane filtration system of the present invention; Figure 5 This is a structural diagram of a pulse generating unit of a super-efficient pulsating concentration device applicable to a reverse osmosis or nanofiltration membrane filtration system of the present invention; Figure 6 It is a two-stage system flow chart of the super-efficient pulsating concentrator applicable to the reverse osmosis or nanofiltration membrane filtration system of the present invention; Figure 7 It is a two-stage two-stage system flow chart of the super-efficient pulsating concentrator applicable to the reverse osmosis or nanofiltration membrane filtration system of the present invention; Figure 8 It is a system block diagram of an existing concentration device; Fig. 9 It is a system configuration diagram of a centrifugal turbine energy recovery device in the prior art; Fig.10 It is a system configuration diagram of an isobaric or positive displacement energy recovery device of the prior art; Fig.11 It is a system configuration diagram of a prior art energy cycle or triple cluster energy recovery device.

[0013] Figure numerals: 1: water feed pump; 2: safety filter; 3: high-pressure pump; 4: energy storage tank assembly; 5: circulation pump; 6: reverse osmosis membrane or nanofiltration membrane assembly; 7: pressure safety valve; 8: pulse generating unit; 9: end cover; 10: fixed orifice plate; 11: shell; 12: thin-walled energy storage tube; 13: floating orifice plate; 14: actuator; 15: piston rod; 16: cylinder body; 17: piston; 18: centrifugal turbine; 19: booster pump; 20: isobaric energy recovery assembly; 21: energy circulation system; 22: exhaust valve; 23: pressure sensor; 24: flow sensor; 25: pressure sensor; 26: flow sensor; 27: pressure sensor; 28: flow sensor; 29: flow sensor. DETAILED DESCRIPTION

[0014] The function of the ultra-efficient pulsating concentrator of the reverse osmosis or nanofiltration membrane filtration system is to follow the process or use requirements, such as Figure 3As shown, a periodic pulsating traveling wave operation mode is used to achieve concentration of the working medium, minimize the energy consumption during the system concentration operation, and combine the energy storage tank component 4 to recover the pressure energy of the high-pressure working medium on the concentrated water side of the reverse osmosis or nanofiltration membrane concentration system, thereby improving the system operation efficiency and reducing the operation cost.

[0015] The present invention is based on energy recovery technology to achieve low energy consumption and ultra-efficient concentration of the working medium. Existing energy recovery devices mainly include centrifugal turbine energy recovery devices, isobaric energy recovery devices, and energy circulation energy recovery devices. The system configuration of the centrifugal turbine energy recovery device is as follows: Fig. 9 As shown, it is composed of a water supply pump 1, a security filter 2, a high-pressure pump 3, a centrifugal turbine 18, a reverse osmosis membrane or a nanofiltration membrane assembly 6, an instrument, a valve, and an electronic control system. The low-pressure seawater is pressurized by the high-pressure pump 3 and enters the reverse osmosis membrane or the nanofiltration membrane assembly 6. The high-pressure brine discharged from the reverse osmosis membrane or the nanofiltration membrane assembly 6 is converted into rotational mechanical energy in the centrifugal turbine 18. The centrifugal turbine 18 is coaxial with the motor of the high-pressure pump 3 and drives the high-pressure pump 3 to operate together. Another scheme of the centrifugal turbine energy recovery device is to directly connect the centrifugal turbine 18 to the high-pressure pump 3 coaxially, and the centrifugal turbine 18 directly drives the high-pressure pump 3 to operate. Its essence is a hydraulically driven pump or a turbocharger. The high-pressure brine of the centrifugal turbine energy recovery device undergoes a two-step conversion process of "pressure energy-mechanical energy-pressure energy". Its energy conversion efficiency is generally about 50-70% and needs to be coaxially connected with the high-pressure pump 3 to realize energy recovery and utilization. Therefore, the device has the disadvantages of low energy conversion efficiency, large equipment volume, and high requirements for device installation and positioning. Isobaric energy recovery device is also called positive displacement energy recovery device. Its system configuration is as follows: Fig.10 As shown, it is composed of a water supply pump 1, a security filter 2, a high-pressure pump 3, a booster pump 19, an isobaric energy recovery component 20, a reverse osmosis membrane or a nanofiltration membrane component 6, an instrument, a valve, and an electronic control system. This device is the most widely used in existing energy recovery devices. Isobaric energy recovery devices can be divided into two categories in principle: valve-controlled type and rotor type. The low-pressure working medium is divided into two paths by the water supply pump 1 and is respectively delivered to the high-pressure pump 3 and the isobaric energy recovery component 20. One path of the low-pressure working medium is directly added to the high pressure by the high-pressure pump 3 and then delivered to the reverse osmosis membrane or the nanofiltration membrane component 6. The other path of the low-pressure working medium first enters the isobaric energy recovery component 20 (such as a rotor-type isobaric energy recovery component or a valve-controlled energy recovery component) and exchanges pressure with the high-pressure working medium discharged from the reverse osmosis membrane or the nanofiltration membrane component 6, and then enters the reverse osmosis membrane or the nanofiltration membrane component 6 after being raised to high pressure by the booster pump 19. The system's water production energy consumption is greatly reduced. The device has internal leakage and mixing problems between the working medium raw liquid and the concentrated fluid on the concentrated water side of the reverse osmosis membrane or nanofiltration membrane assembly 6. The system configuration of the energy cycle or triple cluster energy recovery device is as follows Fig.11As shown, it is composed of a water supply pump 1, a security filter 2, a high-pressure pump 3, an energy circulation system 21, a reverse osmosis membrane or a nanofiltration membrane assembly 6, instruments, valves, and an electronic control system. The high-pressure working medium of this type of energy recovery device can circulate and cross-flow, which is consistent with the working mode of the existing closed-loop reverse osmosis membrane filtration system and has strong adaptability to the processing capacity of the membrane system. However, its core component, the energy circulation system, has the problems of a large number of valve configurations and complex pipelines; the fluid is prone to sediment contamination of the membrane surface under high-concentration circulating flow conditions, and is prone to concentration polarization, resulting in uneven flux when the membrane element is working, thereby affecting the energy recovery efficiency of the device and reducing the separation performance of the membrane filtration system.

[0016] The existing technology of membrane system usually adopts the method of graded treatment to improve the water quality of membrane permeate effluent, which can reduce the salt content of produced water; the method of segmented treatment is adopted to improve the recovery rate of membrane system and increase the concentration of working medium on the concentrated water side. The multi-stage and multi-segment membrane treatment form is the classic process form of reverse osmosis or nanofiltration membrane method. The system configuration of existing membrane concentration technology is as follows: Figure 8 As shown, its principle is consistent with the above-mentioned classic membrane process, but in practice, the specific combination of several stages and sections needs to be determined according to the specific conditions of the working medium and the concentration requirements. Existing membrane concentration devices rarely use energy recovery methods, and the specific operating processes of membrane concentration and filtration systems are also different.

[0017] The present invention discloses a super-efficient pulsating concentration device suitable for reverse osmosis or nanofiltration membrane filtration system, which adopts a multi-stage and multi-segment membrane concentration form. Figure 3 As shown, a periodic pulsating traveling wave operation mode is adopted, combined with an energy storage tank assembly 4, to achieve concentration of the working medium, recover the pressure energy of the high-pressure working medium on the concentrated water side of the reverse osmosis or nanofiltration membrane concentration system, improve the system operation efficiency, and reduce the operation cost.

[0018] The present invention is applicable to a super-efficient pulsating concentration device for a reverse osmosis or nanofiltration membrane filtration system, and the process flow of the two-stage three-stage membrane concentration system is as follows: Figure 1As shown, it is composed of four membrane filtration units, namely, the first stage first section concentrator unit, the first stage second section concentrator unit, the first stage third section concentrator unit and the second stage high pressure reverse osmosis membrane unit, a water tank and an electric control system. The concentrated water side of the three units of the first stage first section concentrator unit, the first stage second section concentrator unit and the first stage third section concentrator unit are connected in series by water tanks, pipelines and valves; the produced water outlet of the first stage first section concentrator unit and the concentrated water inlet of the second stage high pressure reverse osmosis membrane unit are connected in series by pipelines, valves and water pumps; the concentrated water outlet of the second stage high pressure reverse osmosis membrane unit and the produced water outlet of the first stage second section concentrator unit are connected to the working medium inlet pipeline of the first stage first section concentrator unit by pipeline valves; the produced water outlet of the first stage third section concentrator unit is connected to the water tank in the inlet pipeline of the first stage second section concentrator unit by pipeline valves; the membrane permeate of the second stage high pressure reverse osmosis membrane unit is connected to the produced water outlet pipeline; the concentrated medium outlet pipeline is set on the concentrated water side high pressure circulation main pipe of the first stage third section concentrator unit.

[0019] The invention is applicable to a super-efficient pulsating concentration device for a reverse osmosis or nanofiltration membrane filtration system. Figure 1 It can be seen that there are four membrane filtration units, namely, the first stage first section concentrator unit, the first stage second section concentrator unit, the first stage third section concentrator unit and the second stage high pressure reverse osmosis membrane unit. The system configuration of any of the above membrane filtration units is as follows: Figure 2 As shown, it is composed of a water supply pump 1, a security filter 2, a high-pressure pump 3, an energy storage tank assembly 4, a circulation pump 5, a reverse osmosis membrane or a nanofiltration membrane assembly 6, a flow sensor 24, a flow sensor 26, a flow sensor 28, a flow sensor 29, a pressure sensor 23, a pressure sensor 25, a pressure sensor 27, and an electronic control system. The system working medium is seawater, reverse osmosis concentrated water, other high-concentration salt water or solution. Figure 2 As shown in FIG. 1 , PI represents a pressure gauge; PIT represents a pressure sensor; and FIT represents a flow sensor. The energy storage tank assembly 4 is composed of a plurality of energy storage tanks connected in parallel. The energy storage tank monomer structure is as follows: Figure 4 As shown, it is composed of an end cover 9, a fixed orifice plate 10, a shell 11, a thin-walled energy storage tube 12, and a floating orifice plate 13. One end of the thin-walled energy storage tube 12 is connected to the fixed orifice plate 10, and the other end is connected to the floating orifice plate 13 to form an assembly. The assembly is fixed to one end of the shell 11 by the fixed orifice plate 10 and the end cover 9, and is installed in the shell 11 by the floating orifice plate 13; the other end of the shell 11 is fixed by the end cover 9; the thin-walled energy storage tube 12 is a thin-walled seamless straight tube, and can also be a thin-walled corrugated steel tube, and the material is corrosion-resistant material. The structure of the pulse generating unit 8 is shown in FIG. Figure 5As shown, it is composed of an actuator 14, a piston rod 15, a cylinder body 16, and a piston 17. The actuator 14 adopts a hydraulic cylinder or an electric push rod. In the pulse generating unit 8, one end of the piston rod 15 is connected to the actuator 14, and the other end is connected to the piston 17. The piston 17 is installed in the cylinder body 16; the actuator 14 drives the piston 17 to reciprocate in the cylinder body 16 through the piston rod 15 under the drive of the electronic control system.

[0020] In any membrane filtration unit monomer of the present invention, the original working medium inlet is connected to the inlet of the water supply pump 1 through a pipeline valve, and the outlet of the water supply pump 1 is connected to the inlet of the security filter 2 through a pipeline valve; the water supply pump 1 and the security filter 2 are connected in series by pipelines; the outlet of the security filter 2 is divided into three branches, which are respectively connected to the inlets of the high-pressure pump 3, the energy storage tank assembly 4, and the pulse generating unit 8 by pipelines; the outlet pipeline of the high-pressure concentrated water side of the reverse osmosis membrane or nanofiltration membrane assembly 6 is connected to the inlet pipeline of the circulation pump 5, the outlet pipeline of the circulation pump 5 is connected to the inlet main pipe pipeline of the energy storage tank assembly 4, and the outlet main pipe pipeline of the energy storage tank assembly 4 is connected to the inlet of the high-pressure concentrated water side of the reverse osmosis membrane or nanofiltration membrane assembly 6; a circulation pipeline is formed between the reverse osmosis membrane or nanofiltration membrane assembly 6, the circulation pump 5 and the energy storage tank assembly 4; the outlet pipeline of the high-pressure pump 3 is connected to the circulation pump 5 by a three-way joint. outlet pipeline; the outlet pipeline of the pulse generating unit 8 is connected to the outlet main pipe of the energy storage tank assembly 4 by a three-way joint; the high-pressure concentrated water inlet side pipeline of the reverse osmosis membrane or nanofiltration membrane assembly 6 is connected to the pressure safety valve 7; the outlet pipeline of the high-pressure pump 3 is installed with a flow sensor 26 and a pressure sensor 25; the high-pressure concentrated water inlet side main pipe pipeline of the reverse osmosis membrane or nanofiltration membrane assembly 6 is respectively installed with a flow sensor 24 and a pressure sensor 23; the high-pressure concentrated water outlet side main pipe pipeline of the reverse osmosis membrane or nanofiltration membrane assembly 6 is respectively installed with a flow sensor 28 and a pressure sensor 27; the water outlet main pipe of the reverse osmosis membrane or nanofiltration membrane assembly 6 is installed with a flow sensor 29; the water supply pump 1, the security filter 2, the high-pressure pump 3, the energy storage tank assembly 4, the circulation pump 5, the reverse osmosis membrane or nanofiltration membrane assembly 6 and the pulse generating unit 8, the inlet and outlet of the above-mentioned components are all provided with valves. The exhaust valve 22 and the pipeline are connected at the highest position of the working medium high-pressure circulation main pipe. The energy storage tank assembly 4, the reverse osmosis membrane or nanofiltration membrane assembly 6, and the pulse generating unit 8 are respectively connected with the emptying valve and pipeline. The reverse osmosis membrane or nanofiltration membrane assembly 6 is skid-assembled together to form a membrane frame assembly.

[0021] In any membrane filtration unit monomer of the present invention, the circulation pump 5 pressurizes the high-pressure working medium at the outlet of the concentrated water side of the reverse osmosis membrane or nanofiltration membrane assembly 6 and mixes it with the high-pressure working medium stock solution from the high-pressure pump 3. The mixed working medium flows through the energy storage tank assembly 4 and then flows through the concentrated water side of the reverse osmosis membrane or nanofiltration membrane assembly 6. Part of the pure water passes through the membrane surface to become the produced water effluent, and the remaining high-pressure and high-concentration working medium flows out of the reverse osmosis membrane or nanofiltration membrane assembly and enters the inlet of the circulation pump 5. The working medium operates in a high-pressure, large-flow, circulating cross-flow form.

[0022] In any monomer of the membrane filtration unit of the present invention, the water supply pump 1, the high-pressure pump 3 and the circulation pump 5 are connected to the variable frequency motor, and the operating frequency thereof is adjusted by the corresponding frequency converter of the electric control system. Before being put into operation, the water supply pump 1 is first filled with liquid. After the device is completely filled with the working medium, the high-pressure pump 3 and the circulation pump 5 are started, and the device is put into operation. Only 1 to 4 membrane elements are installed in each reverse osmosis membrane or nanofiltration membrane shell. At the initial stage of the operation of the membrane filtration unit, the pressure of the working medium is set by the control system, and the specific set value is reached by changing the operating frequency of the water supply pump 1 motor. As the working medium operates in the high-pressure, large-flow, and circulating cross-flow mode, the concentration of the working medium becomes higher and higher, and the osmotic pressure gradually rises. The electric control system increases the operating frequency of the high-pressure pump 3 unit, the output power of the high-pressure pump 3 increases, and the operating pressure of the working medium rises. Under the control of the electric control system, the output of the membrane filtration system is kept unchanged. When the operating pressure of the working medium rises to the maximum set value, the device completes a working cycle. The maximum set value is determined according to the specific conditions of the working medium, generally 5.0 to 8.0 MPa. The energy storage tank assembly 4 is composed of multiple energy storage tanks connected in parallel. A thin-walled energy storage tube 12 is arranged inside the energy storage tank. The thin-walled energy storage tube 12 is installed between the orifice plates at both ends, one of which is a fixed orifice plate 10 and the other end is a floating orifice plate 13. The working medium flows in the thin-walled energy storage tube 12. When the pressure of the working medium is higher, the thin-walled energy storage tube 12 undergoes greater free elastic deformation and stores pressure energy; the pressure inside the thin-walled energy storage tube is consistent with the pressure of the working medium inside it, and the pressure of the outer shell of the tube is consistent with the atmospheric pressure. The inside of the energy storage tank assembly 4 can be divided into two parts: an energy storage working group and an energy storage standby group. The two parts alternately participate in the circulation operation of the working medium according to the operating pressure of the device. During the operation of the system, when the pressure value of the pressure sensor 23 detected by the electronic control system reaches the maximum working pressure set by the system, the opening and closing status of the inlet and outlet valves of the energy storage tank are changed, and the energy storage working group in the running energy storage tank assembly 4 is switched to the energy storage standby group to exit the system operation, and the energy storage standby group is switched to the energy storage working group to participate in the system operation. During the switching process, the two energy storage tanks are first connected, and part of the elastic deformation energy of the thin-walled energy storage tube in the energy storage working group is released and converted into the working medium pressure energy in the energy storage standby group. When the working medium pressures in the two are equal, the energy conversion is completed, and then the working state of the two energy storage tanks is switched through the valve action. The original energy storage working group that has exited operation becomes the energy storage standby group after drainage and rehydration, waiting to be put into operation in the next cycle. Its cycle is determined by the effective residence time or effective energy storage volume of the working medium in the energy storage tank assembly 4, and the maximum working pressure factor of the device design. The electronic control system detects the pressure values ​​of the pressure sensor 23, the pressure sensor 27 and the pressure difference between the two. When the pressure difference reaches the set value, the electronic control system drives the actuator 14 to act, and the pulse generating unit 8 outputs the pulse flow of the working medium, and the reverse osmosis or nanofiltration membrane filtration system realizes pulsating filtration.As described above, the membrane filtration unit unit operates periodically in a high pressure, large flow, and circulating cross-flow mode, and the flow rate of the circulating pump 5 is about 1 to 5 times the flow rate of the high pressure pump 3 .

[0023] In each circulating filtration cycle of any membrane filtration unit in the present invention, the branch pipeline at the outlet of the security filter 2 replenishes the pulse generating unit 8. The electronic control system detects the pressure values ​​of the pressure sensor 23 and the pressure sensor 27 and the pressure difference between the two. When the pressure difference reaches the set value, or according to the system preset time as a trigger condition and sends a control signal, the hydraulic or electric actuator 14 of the pulse generating unit 8 can drive the replenishing liquid in its cylinder 16 to quickly press into the concentrated water side of the reverse osmosis membrane or nanofiltration membrane assembly 6, change the operating pressure of the reverse osmosis membrane or nanofiltration membrane assembly 6, and the concentrated water pressure will pulsate under high pressure. The system realizes periodic pulsating traveling wave filtration, as shown in the following example. Figure 3 As shown in the figure, the number of high-voltage pulses in each working cycle is 0 to 5 times, the duration of the high-voltage pulse is 10 to 30 seconds, and the pulse pressure is 0.5 to 0.95 times the maximum working pressure set by the system. Figure 3 The high-pressure pulsating traveling wave operation shown in the figure reduces the accumulation of deposits on the membrane surface, reduces the concentration polarization phenomenon on the membrane surface, improves the flux balancing performance of the membrane element, and improves the system operation efficiency.

[0024] The present invention discloses a super-efficient pulsating concentration device for reverse osmosis or nanofiltration membrane filtration system, wherein the two-stage three-stage system is as follows: Figure 1 As shown, the working medium flows through the first stage first section concentrator unit, the first stage second section concentrator unit, and the first stage third section concentrator unit in sequence. After three-stage membrane concentration and circulating concentration in the high-pressure pipeline on the concentrated water side of the first stage third section concentrator unit to reach the set concentration, the concentrated medium is discharged from the concentrated water outlet of the first stage third section concentrator unit. During the concentration process, the permeate concentrated by the membrane of the first stage first section concentrator unit is separated and purified by the membrane filtration system of the second stage high-pressure reverse osmosis membrane unit into reusable fresh water, which is output as system produced water; the working medium on the concentrated water side of the second stage high-pressure reverse osmosis membrane unit and the permeate of the first stage second section concentrator unit flow back to the working medium inlet pipeline of the first stage first section concentrator unit; the permeate of the first stage third section concentrator unit flows back to the inlet pipeline of the first stage second section concentrator unit and enters the second stage concentrator unit for cyclic concentration.

[0025] The ultra-efficient pulsating concentrator of the reverse osmosis or nanofiltration membrane filtration system can be configured according to the two-stage one-stage system process, as follows: Figure 6 As shown; it can also be configured according to the two-stage two-stage system process, as shown in Figure 7 shown.

[0026] The water supply pump 1, the safety filter 2, the high-pressure pump 3, the energy storage tank assembly 4, the circulation pump 5, the reverse osmosis membrane or the nanofiltration membrane assembly 6 and the pulse generating unit 8 in the membrane unit can be configured in a unit system, or in a mother pipe system or in other combinations. The replenishment and drainage of the energy storage tank assembly 4 and the pulse generating unit 8 can be configured with a water pump to realize fluid transportation. Figure 1 , Figure 2 The system configuration is only a preferred embodiment of the present invention, and does not limit the implementation mode and protection scope of the present invention. For those skilled in the art, it should be appreciated that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. An ultra-efficient pulsating concentrator suitable for a reverse osmosis or nanofiltration membrane filtration system, comprising four membrane filtration units, namely, a first-stage first-stage concentrator unit, a first-stage second-stage concentrator unit, a first-stage third-stage concentrator unit and a second-stage high-pressure reverse osmosis membrane unit, a water tank and an electric control system; wherein any of the membrane filtration units comprises a feed water pump (1), a safety filter (2), a high-pressure pump (3), a circulation pump (5), a reverse osmosis membrane or nanofiltration membrane assembly (6), a flow sensor (24, 26, 28, 29), and a pressure sensor (23, 25, 27); the feed water pump (1), the safety filter (2), the high-pressure pump (3), the circulation pump (5), the reverse osmosis membrane or nanofiltration membrane assembly (6), a flow sensor (24, 26, 28, 29), and a pressure sensor (23, 25, 27); The filter (2) and the high-pressure pump (3) are connected in series by pipelines; the outlet of the high-pressure pump (3) is connected to the inlet main pipe of the concentrated water side of the membrane system; the inlet and outlet of the concentrated water side of the reverse osmosis membrane or nanofiltration membrane assembly (6) and the circulation pump (5) are connected by pipelines to form a high-pressure circulation loop; the electronic control system and the water supply pump (1), the high-pressure pump (3), the circulation pump (5), the flow sensor (24, 26, 28, 29), and the pressure sensor (23, 25, 27) are electrically connected; the concentrated water side of the reverse osmosis membrane or nanofiltration membrane assembly (6) and the circulation pump (5) are connected by a high-pressure circulation pipeline; it is characterized in that Any membrane filtration unit further comprises an energy storage tank assembly (4) and a pulse generating unit (8); the unit realizes the mutual conversion between the pressure energy of the working medium and the mechanical energy of the energy storage tank assembly (4); the pulse generating unit (8) stimulates the pulsation of the flow rate and pressure of the working medium; the energy storage tank assembly (4), the pulse generating unit (8) and the electronic control system are electrically connected; and the circulating pump (5), the concentrated water side of the reverse osmosis membrane or the nanofiltration membrane assembly (6) and the energy storage tank assembly (4) are connected by a high-pressure circulating pipeline.

2. The ultra-efficient pulsating concentration device suitable for reverse osmosis or nanofiltration membrane filtration system as claimed in claim 1, characterized in that In any of the membrane filtration units, the outlet of the safety filter (2) is connected to the inlet main pipe of the energy storage tank assembly (4) by a branch pipe; the outlet main pipe of the energy storage tank assembly (4) is connected to the high-pressure concentrated water side inlet of the membrane assembly (6); the energy storage tank assembly (4) is composed of a plurality of energy storage tanks and valves at both ends thereof connected in parallel by pipelines; the energy storage tank assembly (4) is divided into an energy storage working group and an energy storage standby group, and the electronic control system switches the energy storage tank assembly (4) into groups to participate in system operation by changing the opening and closing states of the inlet and outlet valves of the energy storage tanks.

3. The ultra-efficient pulsating concentrator suitable for reverse osmosis or nanofiltration membrane filtration system as claimed in claim 2, characterized in that In any of the membrane filtration units, the energy storage tank in the energy storage tank assembly (4) is composed of an end cover (9), a fixed orifice plate (10), a shell (11), a thin-walled energy storage tube (12), and a floating orifice plate (13); one end of the thin-walled energy storage tube (12) is connected to the fixed orifice plate (10), and the other end is connected to the floating orifice plate (13) to form an assembly; the assembly is fixed to one end of the shell (11) by means of the fixed orifice plate (10) and the end cover (9), and is installed in the shell (11) by means of the floating orifice plate (13); the other end of the shell (11) is fixed by means of the end cover (9); the thin-walled energy storage tube (12) is a thin-walled seamless straight tube, or a thin-walled corrugated steel tube, and is made of corrosion-resistant material.

4. The ultra-efficient pulsating concentrator suitable for reverse osmosis or nanofiltration membrane filtration system as claimed in claim 3, characterized in that In any of the membrane filtration units, the outlet of the safety filter (2) is connected to the inlet of the pulse generating unit (8) by a branch pipe; the outlet of the pulse generating unit (8) is connected to the outlet main pipe of the energy storage tank assembly (4); the pulse generating unit (8) is composed of an actuator (14), a piston rod (15), a cylinder body (16), and a piston (17); one end of the piston rod (15) is connected to the actuator (14), and the other end is connected to the piston (17), and the piston (17) is installed in the cylinder body (16); the actuator (14) is driven by the electronic control system to push the piston (17) through the piston rod (15) to move back and forth in the cylinder body (16).

5. The ultra-efficient pulsating concentrator suitable for reverse osmosis or nanofiltration membrane filtration system as claimed in claim 4, wherein in any membrane filtration unit, the electronic control system detects the flow value of the flow sensor (29), changes the operating frequency of the motor of the high-pressure pump (3), so that the flow value of the flow sensor (29) is consistent with the set value of the water production output; characterized in that During the operation of the membrane filtration unit, when the electronic control system detects that the pressure value of the pressure sensor (23) reaches the maximum working pressure set by the system, the opening and closing conditions of the inlet and outlet valves of the energy storage tank are changed, and the energy storage working group in the running energy storage tank assembly (4) is switched to the energy storage standby group to exit the system operation, and the energy storage standby group is switched to the energy storage working group to participate in the system operation; the electronic control system detects the pressure values ​​of the pressure sensors (23, 27) and the pressure difference between the two. When the pressure difference reaches the set value, the electronic control system drives the actuator (14) to operate, and the pulse generating unit (8) outputs the pulse flow of the working medium, so that the reverse osmosis or nanofiltration membrane filtration system realizes pulsating filtration.

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