CN111003764A - Electric desalting system for reclaimed water and application thereof - Google Patents
Electric desalting system for reclaimed water and application thereof Download PDFInfo
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- CN111003764A CN111003764A CN201911409509.0A CN201911409509A CN111003764A CN 111003764 A CN111003764 A CN 111003764A CN 201911409509 A CN201911409509 A CN 201911409509A CN 111003764 A CN111003764 A CN 111003764A
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- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
- C02F1/469—Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis
- C02F1/4693—Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis electrodialysis
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- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2301/00—General aspects of water treatment
- C02F2301/08—Multistage treatments, e.g. repetition of the same process step under different conditions
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Abstract
The invention relates to a water treatment system, in particular to an electric desalting system for reclaimed water. It comprises a roll-type electric desalting device; the roll-type desalting device comprises a first filter, a first-stage spiral roll-type electric desalting membrane stack, a second-stage spiral roll-type electric desalting membrane stack and a concentrated water tank; the first filter comprises a filtering water inlet end and a filtering water outlet end; the filtered water outlet end is connected with the first raw water inlet end, and the first fresh water outlet end is connected with the second fresh water inlet end; the first concentrated water inlet end is connected with the second concentrated water inlet end in parallel; the water outlet end of the first concentrated water is connected in parallel with the water outlet end of the second concentrated water. The connecting mode of the special structure of the invention is arranged, the front and the rear concentrated water chambers are connected in parallel, the concentrated water flow is short, the concentration difference between the concentrated water and the fresh water in the rear membrane stack is small, and the effective conductivity of the concentrated water is prevented from being reduced, so that the resistance pressure drop of the concentrated water can be prevented from being increased and the current efficiency can be prevented from being reduced.
Description
Technical Field
The invention relates to a water treatment system, in particular to an electric desalting system for reclaimed water.
Background
With the shortage of fresh water resources in recent years and the increasing serious environmental pollution, many countries in the world face the crisis of fresh water, and the water resources become strategic resources which restrict the development of social economy and the living environment of human beings. The desalting treatment is a new industry, has wide market development prospect and huge market space.
In order to save water and realize the recycling of industrial wastewater by petrochemical enterprises, the effluent of the membrane bioreactor is desalted and recycled, and fresh water is used as make-up water of an open circulating cooling water system. High concentrations of chloride and sulfate in water accelerate corrosion of carbon steel. The quality of industrial water for urban sewage recycling (GB/T19923-2005) requires that the concentration of chloride ions in make-up water of an open circulating cooling water system is not more than 250 mg/L. In particular, when a stainless steel heat exchanger is present in the recirculating cooling water system, the make-up water is required to have a chloride ion concentration of less than 100 mg/L.
Spiral wound electrodialysis membrane stacks are reported by T.Wen et al (desalinization, 101, (1995), p 79-91). The membrane stack is formed by spirally rolling a plurality of ion exchange membranes and separation nets around a central pipe. The outer layer is sleeved with an electrode plate, and the central pipe is used as a water collecting pipe and also used as an electrode. Two ends of the membrane are sealed by glue, and the other two ends are used as water inlet and outlet channels. Fresh water and concentrated water enter the membrane stack through the guide pipe, one stream flows axially, the other stream flows spirally and radially, and cross flow passes through the liquid flow channel. Under the direct current electric field, the anions and the cations in the fresh water chamber are transferred to the concentrated water side through the ion exchange membrane, so that the desalination of the fresh water is realized.
When the spiral-wound electrodialysis membrane stack is used for desalting wastewater with high temporary hardness, the membrane surfaces of the electrodes and the ion exchange membranes are quickly scaled, and frequent acid washing is needed to recover the desalting performance of the membrane stack.
Meanwhile, the desalter equipment in the market is placed in a single mode, so that the occupied area is large, the installation is not facilitated, and the later-stage maintenance is also not facilitated.
Disclosure of Invention
The invention aims to provide an electric desalting system for reclaimed water, which can slow down the increase of the resistance voltage drop of concentrated water in a membrane stack and the reduction of current efficiency.
The technical purpose of the invention is realized by the following technical scheme:
an electric desalting system for reclaimed water comprises a roll-type electric desalting device;
the roll type electric desalting device comprises a first filter, a first-stage spiral roll type electric desalting membrane stack, a second-stage spiral roll type electric desalting membrane stack and a concentrated water tank;
the first filter comprises a filtering water inlet end and a filtering water outlet end;
the first-stage spiral-wound type electric desalting membrane stack comprises a first raw water inlet end, a first concentrated water inlet end, a first fresh water outlet end and a first concentrated water outlet end;
the second spiral-wound type electric desalting membrane stack comprises a second fresh water inlet end, a second concentrated water inlet end, a second fresh water outlet end and a second concentrated water outlet end;
the filtered water outlet end is connected with the first raw water inlet end, and the first fresh water outlet end is connected with the second fresh water inlet end;
the first concentrated water inlet end is connected with the second concentrated water inlet end in parallel; the first concentrated water outlet end and the second concentrated water outlet end are connected in parallel.
The connection mode of the front-stage concentrated water chamber and the rear-stage fresh water chamber of the roll-type electric desalting system is parallel connection and concentrated water circulation, the connection mode of the front-stage concentrated water chamber and the rear-stage fresh water chamber is series connection, and fresh water passes through the system at one time. Fresh water and concentrated water enter the membrane stack through the guide pipe. The spiral roll type electric desalting device with the specific structure is applied and connected, the front and rear concentrated water chambers are connected in parallel, the concentrated water flow is short, the concentration difference of concentrated water and fresh water in the rear membrane stack is small, the concentrated water flowing out from the central tube of the upper membrane stack carries gas generated by electrode reaction and cannot enter the concentrated water chamber of the lower membrane stack, the effective conductivity of the concentrated water is prevented from being reduced, and therefore the resistance voltage drop and the current efficiency of the concentrated water can be prevented from being increased.
Preferably, the electric desalting system for the reclaimed water comprises a combined bracket and more than two roll-type electric desalting devices movably connected to the combined bracket;
the combined bracket comprises a fresh water inlet pipe, a fresh water outlet pipe, a concentrated water inlet pipe, a concentrated water outlet pipe and an electrode water outlet pipe.
The roll type electric desalting system adopts a specific combined support connecting structure, and a specific roll type electric desalting device is combined and installed, so that the module integration level under the roll type structure is high, the floor area is greatly reduced through a drawer type or vertical stacking and placing mode, the installation is facilitated, and the later maintenance is also facilitated.
Preferably, the combined support is a multi-layer vertical combined support, the roll-type electric desalting device is vertically arranged, and the fresh water inlet pipe, the fresh water outlet pipe, the concentrated water inlet pipe, the concentrated water outlet pipe and the polar water outlet pipe are connected and arranged at the lower end part of each layer of roll-type electric desalting device.
The combined bracket of the device is a vertical combined bracket with more than two layers, is installed and combined into a pipeline system which is orderly connected, and can process a large amount of industrial raw water in unit area so as to prepare high-quality pure water.
Preferably, the combined support is a multi-layer drawer type combined support, the roll-type electric desalting device is horizontally arranged, and the fresh water inlet pipe, the fresh water outlet pipe, the concentrated water inlet pipe, the concentrated water outlet pipe and the polar water outlet pipe are connected and arranged on the side face of one end of each layer of roll-type electric desalting device.
The combined bracket of the device is a drawer type combined bracket with more than two layers, and is installed and combined into a pipeline system which is connected in order; the electric desalting devices in each layer of drawers can be increased or reduced according to actual conditions, so that the installation is facilitated, later maintenance is facilitated, and a large amount of industrial raw water can be treated in a unit area, so that high-quality pure water is prepared.
Preferably, the roll-type electric desalting device is an electric dialyzer.
Preferably, the roll-type electric desalting device is a large-flux roll-type electric desalting device and comprises a shell and a membrane core; the membrane core comprises a core body and an end cover, the core body is arranged in the outer shell, and the end cover is sleeved in the connecting part of the sealing sleeve and the outer shell; the membrane unit comprises a positive membrane and a negative membrane;
the shell body is a UPVC shell formed in a segmented mode;
the end cover is an arched end cover, and a plurality of limiting bayonet locks capable of being clamped on the outer shell are uniformly arranged on the outer wall of the arched end cover at intervals.
The electric desalting device can realize the directional migration of ions under the action of a direct current electric field through the selective permeation action of an electromagnetic field on anions and cations through anion and cation exchange membranes, thereby completing the deep desalting of water.
According to the large-flux roll-type electric desalting component, the strength of an electric field in the flow direction of water to be purified is changed by the roll-type wound membrane core and the internal and external arranged negative and positive stages, so that the step-by-step separation of different particles is completed, the electric energy is fully utilized, and the scaling tendency of a concentrated water chamber is relieved; further saving system pipelines and occupied space and reducing the cost of water per ton; the arched end cover is clamped with the shell, so that the arched end cover is not easy to turn over due to the internal pressure of the component and is tightly connected; the setting of spacing bayonet lock has improved the holistic bearing capacity of arch end cover.
Preferably, the first raw water inlet end is connected with a water inlet main pipe, the water inlet main pipe comprises a plurality of water flow inlet branch pipes which are annularly arranged, the water flow inlet branch pipes are connected with a fresh water inlet main pipe body together, and the fresh water inlet main pipe body is provided with a first raw water inlet end.
Preferably, a filter plate is arranged on the end face of the membrane core, water distribution holes are formed in the filter plate and are horn-shaped holes, large holes of the horn-shaped holes face upwards, needle holes are formed in the side face of each horn-shaped hole and communicated with the lower surface of the filter plate, and ribs which are radially arranged are formed on the outer wall of each horn-shaped hole. Therefore, the fresh water can be distributed more uniformly, and the pressure difference between two sides of the membrane is easy to regulate and control.
Preferably, the fresh water flow in the first-stage spiral-wound type electric desalting membrane stack is axial flow, and the fresh water flow in the second-stage spiral-wound type electric desalting membrane stack is axial flow; the concentrated water in the first-stage spiral-wound type electric desalting membrane stack flows in a radial direction, the dilute water in the second-stage spiral-wound type electric desalting membrane stack flows in a radial direction, and the flow direction of the dilute water flows from the outer electrode to the central tube in a spiral manner. The structure of the invention can adjust the working voltage to make each stage of membrane stack operate under the optimal working condition.
Preferably, the primary spiral-wound type electric desalting membrane stack and the secondary spiral-wound type electric desalting membrane stack are supplied with direct current by independent electric channels; a concentrated water pump and a concentrated water regulating valve K are arranged on a pipeline of the concentrated water tank communicated with the first concentrated water inlet end and the second concentrated water inlet end; and a degasser is additionally arranged at the top of the concentrated water tank. Therefore, the gas carried by the backflow concentrated water can be removed, and the gas generated by the electrode reaction carried by the concentrated water flowing out of the central tube of the previous-stage membrane stack is further prevented from entering the concentrated water chamber of the next-stage membrane stack, so that the effective conductivity of the concentrated water is prevented from being reduced, and the resistance pressure drop and the current efficiency of the concentrated water can be prevented from being increased.
Preferably, the second-stage spiral-wound type electric desalting membrane stack is connected with a third-stage spiral-wound type electric desalting membrane stack, and the second fresh water outlet end is connected with a third-stage fresh water inlet end of the third-stage spiral-wound type electric desalting membrane stack; the second concentrated water inlet end is connected in parallel with the third concentrated water inlet end of the third spiral wound type electric desalting membrane stack; the second concentrated water outlet end is connected in parallel with the third concentrated water outlet end of the third-stage spiral roll type electric desalting membrane stack.
The multistage spiral-wound type electric desalting membrane pile is arranged in a series-parallel connection structure of concentrated fresh water, so that the desalting effect can be further improved while the current efficiency is prevented from being reduced.
Preferably, the filtering water inlet end is connected with a raw water pump, and the outlet of the concentrated water pump is provided with a second filter; the filtering precision of the first filter and the second filter is 5 μm or 10 μm. The outlets of the raw water pump and the concentrated water pump are provided with filters, so that suspended matters in the inlet water can be removed better.
The second technical purpose of the invention is realized by the following technical scheme:
an electric desalting system for desalting regenerated water is applied to the desalting of regenerated water, and comprises a step of adjusting the inflow rate of concentrated water of each stage of membrane stack to be equal to or lower than the inflow rate of fresh water, and a step of keeping the inflow pressure of the concentrated water of each stage to be equal to or lower than the inflow pressure of the fresh water by 0.008-0.012 MPa.
According to the invention, by adjusting the flow and pressure of the concentrated and dilute water of each stage of membrane stack and combining the application and connection mode of the spiral roll type electric desalting device with a specific structure, the front and rear concentrated water chambers are connected in parallel, the concentrated water flow is short, the concentration difference of the concentrated water and the fresh water in the rear stage of membrane stack is small, the effective conductivity reduction of the concentrated water is effectively avoided, and thus the resistance voltage drop increase and the current efficiency reduction of the concentrated water can be prevented.
Preferably, the inflow rate of the concentrated water is adjusted to be 0.8-0.9 times of the inflow rate of the fresh water, and the inflow pressure of the concentrated water is equal to the inflow pressure of the fresh water.
The inventor finds that the resistance pressure drop increase and the current efficiency decrease of the concentrated water can be more effectively prevented by the specific concentrated-dilute-water flow and pressure setting of each stage of the membrane stack and the application and connection mode of the spiral-wound type electric desalting device with a specific structure.
Preferably, the outlet water flow of the polar water of each stage of the membrane stack is adjusted to be 1-4% of the raw water flow, and more preferably 2-3%; when the system is in operation, part of the concentrated water is continuously led out of the room from the concentrated water pump 5, and meanwhile, the same amount of raw water is supplemented to the concentrated water tank. The concentration multiple of the concentrated water is 4-7 times, and the preferred concentration multiple is 4 times.
The inventor further finds that by combining specific polar water flow and concentrate setting of each stage of membrane stack with specific structure of spiral-wound type electric desalting device application and connection mode, the resistance pressure drop increase and current efficiency decrease of concentrate can be more effectively prevented.
Preferably, a pH value regulator is continuously metered into the concentrated water tank, and the pH value of the inlet water of the concentrated water is regulated to 4-7. Preferably, the pH value is 5-6. The pH regulator is preferably sulfuric acid or hydrochloric acid, more preferably hydrochloric acid.
The inventor further finds that the concentration difference of the concentrated water and the fresh water in the later stage membrane stack can be small by adjusting the pH value in the concentrated water tank, and the effective conductivity of the concentrated water is effectively prevented from being reduced, so that the resistance voltage drop of the concentrated water is effectively prevented from being increased and the current efficiency is prevented from being reduced.
In conclusion, the invention has the following beneficial effects:
1. in the specific spiral roll type electric desalting device structure, the front and rear concentrated water chambers are connected in parallel, the concentrated water flow is short, the concentration difference between the concentrated water and the fresh water in the rear membrane stack is small, the transport volume of homonymous ions is small, the bubble effect is avoided, and the current efficiency is high;
2. the spiral-wound electric desalting device is applied to the desalting of the regenerated water, and the concentration difference of the concentrated water and the fresh water in the later stage of membrane stack is small by adjusting the combination setting of the concentrated and fresh water flow and the pressure, the setting of the polar water flow and the concentrated water, and the pH value adjustment in the concentrated water tank and combining the application and the connection mode setting of the spiral-wound electric desalting device with a specific structure, so that the effective conductivity reduction of the concentrated water is more effectively avoided, and the resistance voltage drop increase and the current efficiency reduction of the concentrated water can be prevented.
3. The structure is simple, and the volume of the equipment can be reduced;
4. the device can be integrally moved in a modularized manner, so that the device is heavy and needs to be carried by a single machine;
5. the pipeline connection is clear and orderly, and the maintenance is convenient;
6. the device can be installed according to actual requirements, and can be connected in parallel or in series, so that the utilization rate of the device is improved.
Drawings
FIG. 1 is a schematic diagram of the connection of an electric desalting system for regenerated water according to the present invention;
FIG. 2 is a front view of the drawer type sectional shelf unit of the present invention;
FIG. 3 is a top view of the drawer type sectional shelf assembly of the present invention;
FIG. 4 is a top view of the vertical modular support of the present invention;
FIG. 5 is a front view of the vertical modular support of the present invention;
FIG. 6 is a top view of the water inlet manifold of the spiral wound electro-desalination membrane stack of the present invention;
FIG. 7 is a schematic structural diagram of a water inlet manifold of the spiral wound type electro-desalting membrane stack of the invention;
FIG. 8 is a schematic view of the arched end cap of the spiral wound electro-desalination membrane stack of the present invention;
FIG. 9 is a schematic diagram of the water pore structure of the spiral-wound electric desalting membrane pile.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
As shown in fig. 1 to fig. 9, the electric desalting system for reclaimed water comprises a roll-type electric desalting device, and the roll-type electric desalting device 2 comprises a first filter 21, a first-stage spiral roll-type electric desalting membrane stack 22, a second-stage spiral roll-type electric desalting membrane stack 23 and a concentrate tank 24; the first filter 21 includes a filtered water inlet end 211 and a filtered water outlet end 212; the first-stage spiral-wound type electro-desalting membrane stack 22 comprises a first raw water inlet end 221, a first concentrated water inlet end 222, a first fresh water outlet end 223 and a first concentrated water outlet end 224; the second spiral wound type electro-desalting membrane stack 23 comprises a second fresh water inlet end 231, a second concentrated water inlet end 232, a second fresh water outlet end 233 and a second concentrated water outlet end 234; the filtered water outlet end 212 is connected with the first raw water inlet end 221, and the first fresh water outlet end 223 is connected with the second fresh water inlet end 231; the first concentrated water inlet end 222 is connected in parallel with the second concentrated water inlet end 232; the first concentrated water outlet end 224 is connected in parallel with the second concentrated water outlet end 234.
The electric desalting system for the reclaimed water comprises a combined bracket 1 and more than two rolled electric desalting devices 2 movably connected to the combined bracket 1; the combined bracket 1 comprises a fresh water inlet pipe 11, a fresh water outlet pipe 12, a concentrated water inlet pipe 13, a concentrated water outlet pipe 14 and a polar water outlet pipe 15.
The sectional shelf 1 is preferably a vertical sectional shelf or a drawer sectional shelf. The roll-type electric desalting devices can be connected in series or in parallel according to actual needs, and preferably more than two roll-type electric desalting devices 2 are connected in parallel.
When the combined support 1 is a multi-layer vertical combined support, the roll-type electric desalting device 2 can be vertically arranged, and the fresh water inlet pipe 11, the fresh water outlet pipe 12, the concentrated water inlet pipe 13, the concentrated water outlet pipe 14 and the polar water outlet pipe 15 are preferably connected and arranged at the lower end part of each layer of the roll-type electric desalting device 2.
When the combined support 1 is a multi-layer drawer type combined support, the roll-type electric desalting devices 2 can be horizontally placed, and the fresh water inlet pipe 11, the fresh water outlet pipe 12, the concentrated water inlet pipe 13, the concentrated water outlet pipe 14 and the polar water outlet pipe 15 are preferably connected and arranged on one side surface of each layer of the roll-type electric desalting devices 2.
In order to improve the filtration flux and the utilization rate of unit area, the roll-type electric desalting device 2 is a large-flux roll-type electric desalting device which comprises a shell and a membrane core; the membrane core comprises a core body and an end cover 255, the core body is arranged in the outer shell, and the end cover 255 is sleeved in the connecting part of the sealing sleeve and the outer shell; the membrane unit comprises a positive membrane and a negative membrane; the outer shell is a UPVC shell formed in a segmented mode; the end cover 255 is an arched end cover, and a plurality of limiting bayonet pins 255a which can be clamped on the outer shell body are uniformly arranged on the outer wall of the arched end cover at intervals. The first raw water inlet end 221 is connected with the water inlet main pipe 20, the water inlet main pipe 20 comprises a plurality of water flow inlet branch pipes 201 which are annularly arranged, the water flow inlet branch pipes 201 are jointly connected with the fresh water inlet main pipe body 202, and the fresh water inlet main pipe body 202 is provided with the first raw water inlet end 221. The end cover 255 is an arched end cover, and a plurality of limiting bayonet pins 255a which can be clamped on the outer shell 211 are uniformly arranged on the outer wall of the arched end cover at intervals.
The membrane core end face is provided with a filter plate 227, the filter plate 227 is provided with water distribution holes 2271, the water distribution holes 2271 are horn holes, large holes of the horn holes face upwards, pinholes 2272 are arranged on the side face of the horn holes and communicated with the lower surface of the filter plate 227, and ribs 2273 formed in a radial arrangement mode are arranged on the outer wall of the horn holes.
The fresh water in the first-stage spiral-wound type electro-desalting membrane stack 22 flows axially, and the fresh water in the second-stage spiral-wound type electro-desalting membrane stack 23 flows axially; the concentrated water in the first-stage spiral-wound type electro-desalting membrane stack 22 flows in a radial direction, and the dilute water in the second-stage spiral-wound type electro-desalting membrane stack 23 flows in a radial direction, and flows in a spiral manner from the outer electrode to the central tube.
The first-stage spiral-wound type electric desalting membrane stack 22 and the second-stage spiral-wound type electric desalting membrane stack 23 are supplied with direct current by independent electric channels; a concentrated water pump 25 and a concentrated water regulating valve K are arranged on a pipeline of the concentrated water tank 24 communicated with the first concentrated water inlet end 222 and the second concentrated water inlet end 232; a deaerator 26 is added to the top of the concentrate tank 24.
The second-stage spiral-wound type electric desalting membrane stack 23 is connected with a third-stage spiral-wound type electric desalting membrane stack 27, and the second fresh water outlet end 223 is connected with a third-stage fresh water inlet end of the third-stage spiral-wound type electric desalting membrane stack; the second concentrated water inlet end 222 is connected in parallel with the third concentrated water inlet end of the third-stage spiral wound electro-desalting membrane stack; the second concentrated water outlet end 224 is connected in parallel with the third concentrated water outlet end of the third spiral-wound electro-desalting membrane stack.
The filtering water inlet end 211 is connected with a raw water pump 28, and the outlet of the concentrated water pump 25 is provided with a second filter 29; the first filter 21 and the second filter 29 have a filtering accuracy of 5 μm or 10 μm.
The effluent of an MBR membrane bioreactor in a water treatment workshop of a certain petrochemical enterprise is used as make-up water of an open circulating cooling water system after electrodialysis desalination. The conductivity of raw water is 2240mg/L, the hardness of calcium and magnesium is 328mg/L, and the total alkalinity is 100 mg/L. The chloride ion concentration is 450 mg/L. The conductivity of the fresh water is required to be lower than 800mg/L, and the concentration of chloride ions is required to be lower than 100 mg/L.
Application example 1
The raw water is pressurized by a raw water pump, flows through a 10 mu m filter and then enters a spiral wound type electro-desalting membrane stack. Fresh water and concentrated water enter the membrane stack through the guide pipe, the fresh water flows axially, and the concentrated water flows to the central pipe from the outer wall in a spiral mode. The polar water is led out from the polar water chamber to the direct-discharge polar water tank. Each membrane stack is supplied with direct current by an independent electrical channel. The first stage operating voltage is adjusted to 72V, and the second stage operating voltage is adjusted to 70V. The two-stage operating current is 38A. The flow rate of raw water is 6m3The flow rate of concentrated water is 5m3H is used as the reference value. The water inlet pressure of raw water is 0.1MPa, and the water inlet pressure of concentrated water is 0.1 MPa. The flow rate of each stage of polar water is adjusted to be 150L/h. The concentration multiple of the concentrated water is 5 times. And (4) metering hydrochloric acid into the concentrated water tank, and controlling the pH value to be 4. After 4 hours of stable operation, samples were taken for fresh water quality analysis. 595mg/L of fresh water conductivity, 91mg/L of calcium and magnesium hardness and 90mg/L of chloride ion concentration.
When the system is actually installed and used, the volume of equipment can be reduced, and the condition that the device is heavy and needs to be carried by a single machine is avoided; the maintenance is convenient, and if a plurality of assemblies are stacked together, the maintenance is inconvenient although the occupied area is small; the device can be installed according to actual requirements, a plurality of devices can be connected in parallel or in series, and the utilization rate of the device is improved.
Application example 2
The raw water is pressurized by a raw water pump, flows through a filter with the diameter of 5 mu m and then enters a spiral-wound type electro-desalting membrane stack. Fresh water and concentrated water enter the membrane stack through the guide pipe, the fresh water flows axially, and the concentrated water flows to the central pipe from the outer wall in a spiral mode. The polar water is led out from the polar water chamber to the direct-discharge polar water tank. Each membrane stack is supplied with direct current by an independent electrical channel. The first stage operating voltage 72V and the second stage operating voltage 71V are regulated. The two-stage operating current is 38A. The flow rate of raw water is 6m3The flow rate of concentrated water is 4.8m3H is used as the reference value. The water inlet pressure of raw water is 0.1MPa, and the water inlet pressure of concentrated water is 0.09MPa. The flow rate of each stage of polar water is adjusted to be 60L/h. The concentration multiple of the concentrated water is 4 times. And (4) metering hydrochloric acid into the concentrated water tank, and controlling the pH value to be 7. After 4 hours of stable operation, samples were taken for fresh water quality analysis. The conductivity of fresh water is 587mg/L, the hardness of calcium and magnesium is 88mg/L, and the concentration of chloride ions is 86 mg/L.
Application example 3
The raw water is pressurized by a raw water pump, flows through a 10 mu m filter and then enters a spiral wound type electro-desalting membrane stack. Fresh water and concentrated water enter the membrane stack through the guide pipe, the fresh water flows axially, and the concentrated water flows to the central pipe from the outer wall in a spiral mode. The polar water is led out from the polar water chamber to the direct-discharge polar water tank. Each membrane stack is supplied with direct current by an independent electrical channel. The first stage operating voltage is adjusted to 72V and the second stage operating voltage is adjusted to 69V. The two-stage working current is 37.5A. The flow rate of raw water is 6m3The flow rate of concentrated water is 6m3H is used as the reference value. The water inlet pressure of raw water is 0.1MPa, and the water inlet pressure of concentrated water is 0.1 MPa. The flow rate of each stage of polar water is adjusted to 240L/h. The concentration multiple of the concentrated water is 7 times. And (4) metering hydrochloric acid into the concentrated water tank, and controlling the pH value to be 5.5. After 4 hours of stable operation, samples were taken for fresh water quality analysis. The conductivity of the fresh water is 578mg/L, the hardness of the calcium and the magnesium is 86mg/L, and the concentration of the chloride ion is 80 mg/L.
Application example 4
And adjusting the inflow rate of the concentrated water of each stage of the membrane stack to be equal to the inflow rate of the fresh water, and keeping the inflow pressure of the concentrated water of each stage lower than the inflow pressure of the fresh water by 0.008 MPa.
Adjusting the effluent flow of the polar water of each stage of membrane stack to be 1% of the flow of the raw water; when the system is in operation, part of the concentrated water is continuously led out of the room from the concentrated water pump 5, and meanwhile, the same amount of raw water is supplemented to the concentrated water tank. The concentration multiple of the concentrated water is 7 times.
And continuously metering a pH value regulator into the concentrated water tank 4, and regulating the pH value of the inlet water of the concentrated water to 4. The pH value regulator is hydrochloric acid. The first filter 1 and the second filter 9 have a filtering accuracy of 5 μm. Sampling and analyzing the quality of the fresh water. The conductivity of the fresh water is 556mg/L, the hardness of the calcium and the magnesium is 82mg/L, and the concentration of chloride ions is 78 mg/L.
Application example 5
And adjusting the inflow rate of the concentrated water of each stage of the membrane stack to be 0.9 times of the inflow rate of the fresh water, and keeping the inflow pressure of the concentrated water of each stage equal to or lower than the inflow pressure of the fresh water by 0.01 MPa.
Adjusting the outlet flow of the polar water of each stage of membrane stack to be 4% of the flow of the raw water; when the system is in operation, part of the concentrated water is continuously led out of the room from the concentrated water pump 5, and meanwhile, the same amount of raw water is supplemented to the concentrated water tank. The concentration multiple of the concentrated water is 4 times.
And continuously metering a pH value regulator into the concentrated water tank 4, and regulating the pH value of the inlet water of the concentrated water to 7. The pH value regulator is sulfuric acid. The first filter 1 and the second filter 9 have a filtering accuracy of 10 μm. Sampling and analyzing the quality of the fresh water. The conductivity of the fresh water is 548mg/L, the hardness of the calcium and the magnesium is 79mg/L, and the concentration of chloride ions is 75 mg/L.
Application example 6
The water inlet flow of the concentrated water is adjusted to be 0.8 times of the water inlet flow of the fresh water, and the water inlet pressure of the concentrated water is equal to the water inlet pressure of the fresh water.
Adjusting the outlet flow of the polar water of each stage of membrane stack to be 3% of the flow of the raw water; when the system is in operation, part of the concentrated water is continuously led out of the room from the concentrated water pump 5, and meanwhile, the same amount of raw water is supplemented to the concentrated water tank. The concentration multiple of the concentrated water is 6 times.
And continuously metering a pH value regulator into the concentrated water tank 4, and regulating the pH value of the inlet water of the concentrated water to 6. The pH value regulator is hydrochloric acid. The first filter 1 and the second filter 9 have a filtering accuracy of 10 μm. Sampling and analyzing the quality of the fresh water. The conductivity of the fresh water is 537mg/L, the hardness of the calcium and the magnesium is 76mg/L, and the concentration of chloride ions is 73 mg/L.
Comparative example 1
The two-stage spiral wound electrodialysis membrane stacks are connected in series for desalting the regenerated water. The concentrated water chamber and the fresh water chamber are connected in series. See fig. 1. Raw water enters the spiral-wound electrodialysis membrane stack after passing through a 10-micron filter. Fresh water and concentrated water enter the membrane stack through the guide pipe, the fresh water flows axially, and the concentrated water flows to the central pipe from the outer wall in a spiral mode. The polar water is led out from the polar water chamber to the direct-discharge polar water tank. Each membrane stack is supplied with direct current by an independent electrical channel. The first stage working voltage is adjusted to 72V, and the second stage working voltage is adjusted to 85V. The two-stage operating current is 38A. The flow rate of raw water is 6m3The flow rate of concentrated water is 5m3H is used as the reference value. The water inlet pressure is 0.1 MPa. The flow rate of each stage of polar water is adjusted to be 150L/h. The concentration multiple of the concentrated water is 4 times. Concentrated water tank meterHydrochloric acid was added in an amount to control the pH at 5.5. After 4 hours of stable operation, samples were taken for fresh water quality analysis. The conductivity of the fresh water is 880mg/L, the hardness of the calcium and the magnesium is 116mg/L, and the concentration of chloride ions is 122 mg/L.
Comparative example 2
The same as in comparative example 1, except that the flow rate of the raw water was 6m3H, concentrate flow 7m3H is used as the reference value. The water inlet pressure of raw water is 0.1MPa, and the water inlet pressure of concentrated water is 0.12 MPa. Sampling and analyzing the quality of the fresh water. The conductivity of the fresh water is 920mg/L, the hardness of the calcium and the magnesium is 125mg/L, and the concentration of chloride ions is 131 mg/L.
From the examples and comparative examples it can be seen that:
1. when the system in the embodiment and the application embodiment is used for desalting and reusing the regenerated water, in a specific spiral roll type electric desalting system structure, the front and rear concentrated water chambers are connected in parallel, the concentrated water flow is short, the concentration difference between the concentrated water and the fresh water in the rear stage membrane stack is small, the transport volume of homonymous ions is small, the bubble effect is avoided, and the current efficiency is high;
2. the application in the reclaimed water desalination is that the concentration difference of the concentrated water and the fresh water in the later stage membrane stack is small by adjusting the combined setting of the concentrated and fresh water flow and the pressure of each stage of membrane stack, the setting of the polar water flow and the concentrated water, and the pH value adjustment in the concentrated water tank and combining the application of a spiral roll type electric desalination system with a specific structure and the setting of a connection mode, so that the effective conductivity reduction of the concentrated water is effectively avoided, the resistance pressure drop increase and the current efficiency reduction of the concentrated water can be prevented, and the more thorough reclaimed water desalination effect of the electric desalination is obtained;
3. the spiral wound type electro-desalting membrane stack of comparative example 1 was used for desalting and recycling of the above-mentioned regenerated water by connecting them in series, as shown in the figure. The concentrated water chamber and the fresh water chamber are connected in series. The finally obtained fresh water has high conductivity, high calcium and magnesium hardness and high chloride ion concentration, which shows that the electric desalting effect is not as good as that of the application embodiment. On one hand, as the flow of the concentrated water and the fresh water is prolonged, the concentration difference of the concentrated water and the fresh water is increased, the selective permeability of the membrane is reduced, the transport amount of the homonymous ions is increased, the diffusion of the electrolyte concentration difference is intensified, and the current efficiency is reduced. On the other hand, the concentrated water flowing out of the central tube of the previous membrane stack carries the gas generated by the electrode reaction to enter the concentrated water chamber of the next membrane stack. The dispersion of the bubbles enables the concentrated water in the next-stage membrane stack to form a gas-liquid mixed system, so that the effective conductivity of the concentrated water is reduced, the resistance voltage drop of the concentrated water is increased, and the current efficiency is further reduced.
The present embodiment is only for explaining the present invention, and it is not limited to the present invention, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present invention.
Claims (10)
1. An electric desalting system for reclaimed water is characterized by comprising a roll-type electric desalting device (2);
the roll type electric desalting device (2) comprises a first filter (21), a first-stage spiral roll type electric desalting membrane stack (22), a second-stage spiral roll type electric desalting membrane stack (23) and a concentrated water tank (24);
the first filter (21) comprises a filter water inlet end (211) and a filter water outlet end (212);
the first-stage spiral-wound type electro-desalting membrane stack (22) comprises a first raw water inlet end (221), a first concentrated water inlet end (222), a first fresh water outlet end (223) and a first concentrated water outlet end (224);
the second spiral-wound type electro-desalting membrane stack (23) comprises a second fresh water inlet end (231), a second concentrated water inlet end (232), a second fresh water outlet end (233) and a second concentrated water outlet end (234);
the filtering water outlet end (212) is connected with the first raw water inlet end (221), and the first fresh water outlet end (223) is connected with the second fresh water inlet end (231);
the first concentrated water inlet end (222) is connected with the second concentrated water inlet end (232) in parallel; the first concentrated water outlet end (224) is connected with the second concentrated water outlet end (234) in parallel.
2. An electric desalination system for regenerated water according to claim 1 characterized by comprising a combined support (1) and more than two roll-type electric desalination devices (2) movably connected to the combined support (1);
the combined bracket (1) comprises a fresh water inlet pipe (11), a fresh water outlet pipe (12), a concentrated water inlet pipe (13), a concentrated water outlet pipe (14) and a polar water outlet pipe (15).
3. An electric desalination system for regenerated water according to claim 1, characterized in that: the combined support (1) is a multilayer vertical combined support, the roll-type electric desalting device (2) is vertically arranged, and the fresh water inlet pipe (11), the fresh water outlet pipe (12), the concentrated water inlet pipe (13), the concentrated water outlet pipe (14) and the polar water outlet pipe (15) are connected and arranged at the lower end part of each layer of roll-type electric desalting device (2).
4. An electric desalination system for regenerated water according to claim 1, characterized in that: the combined support (1) is a multilayer drawer type combined support, the roll-type electric desalting devices (2) are horizontally arranged, and the fresh water inlet pipe (11), the fresh water outlet pipe (12), the concentrated water inlet pipe (13), the concentrated water outlet pipe (14) and the polar water outlet pipe (15) are connected and arranged on the side face of one end of each layer of roll-type electric desalting device (2).
5. An electric desalination system for regenerated water according to claim 2 or 3, characterized in that: the roll-type electric desalting device (2) is a large-flux roll-type electric desalting device and comprises a shell and a membrane core; the membrane core comprises a core body and an end cover (255), the core body is arranged in the outer shell, and the end cover (255) is sleeved in the connecting part of the sealing sleeve and the outer shell; the membrane unit comprises a positive membrane and a negative membrane;
the shell body is a UPVC shell formed in a segmented mode;
the end cover (255) is an arched end cover, and a plurality of limiting clamping pins (255 a) which can be clamped on the outer shell are uniformly arranged on the outer wall of the arched end cover at intervals.
6. An electric desalination system for regenerated water according to claim 5, characterized in that: the membrane core terminal surface is provided with filter plate (227), be provided with water distribution hole (2271) on filter plate (227), water distribution hole (2271) are the bell mouth, the bell mouth macropore is up, the bell mouth side is equipped with pinhole (2272) and leads to filter plate (227) lower surface, be provided with bead (2273) that radial arrangement formed on the bell mouth outer wall.
7. An electric desalination system for regenerated water according to claim 1, characterized in that: the fresh water in the first-stage spiral-wound type electric desalting membrane stack (22) flows axially, and the fresh water in the second-stage spiral-wound type electric desalting membrane stack (23) flows axially; concentrated water in the first-stage spiral-wound type electric desalting membrane stack (22) flows in a radial direction, and fresh water in the second-stage spiral-wound type electric desalting membrane stack (23) flows in a radial direction, and flows from the outer electrode to the central tube in a spiral manner.
8. An electric desalination system for regenerated water according to claim 1, characterized in that: the primary spiral-wound type electric desalting membrane stack (22) and the secondary spiral-wound type electric desalting membrane stack (23) are supplied with direct current by independent electric channels; a concentrated water pump (25) and a concentrated water regulating valve K are arranged on a pipeline of the concentrated water tank (24) communicated with the first concentrated water inlet end (222) and the second concentrated water inlet end (232); and a degasser (26) is additionally arranged at the top of the concentrated water tank (24).
9. An electric desalination system for regenerated water according to claim 7 or 8, characterized in that: the second-stage spiral-wound type electric desalting membrane stack (23) is connected with a third-stage spiral-wound type electric desalting membrane stack (27), and the second fresh water outlet end (223) is connected with a third-stage fresh water inlet end of the third-stage spiral-wound type electric desalting membrane stack; the second concentrated water inlet end (222) is connected with the third concentrated water inlet end of the third-stage spiral roll type electric desalting membrane stack in parallel; the second concentrated water outlet end (224) is connected in parallel with the third concentrated water outlet end of the third-stage spiral-wound type electric desalting membrane stack.
10. An application of an electric desalting system for reclaimed water in reclaimed water desalting is characterized in that: the method comprises the steps of adjusting the inflow rate of the concentrated water of each stage of membrane stack to be equal to or lower than the inflow rate of the fresh water, and keeping the inflow pressure of the concentrated water of each stage to be equal to or lower than the inflow pressure of the fresh water by 0.008-0.012 MPa.
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